Ischaemic Heart Disease: A Secondary Prevention Trial Using Clofibrate

A trial is reported of the effects of giving clofibrate to prevent progression of pre-existing ischaemic heart disease. There were two groups randomly distributed between clofibrate (350 patients) and placebo (367 patients) regimens. The trial lasted about six years and was conducted in 19 hospitals in Scotland. The criteria of acceptance into the trial were precise and were monitored by one observer. The standards of diagnosis of events were defined and all protocols and electrocardiograms were read blind by one observer.Three categories of patients were admissible to the trial: (1) patients with one myocardial infarction (W.H.O. E.C.G. criteria) between 8 and 16 weeks before the start of the trial; (2) patients with angina of a duration of 3 to 24 months, provided their E.C.G. showed signs of myocardial ischaemia at rest or after exercise; and (3) patients with one recent myocardial infarction and pre-existing angina as defined above.There were fewer deaths in patients with angina (categories 2 and 3 above) treated with clofibrate than in those on placebo. The mortality in the former group was reduced by 62%, and this is a statistically significant difference. Clofibrate did not have any statistically significant effect in reducing the rate of non-fatal infarction in patients with angina or in those with myocardial infarction and pre-existing angina, though a beneficial trend was evident when both subgroups were combined (a 44% reduction compared with the placebo group). There was a significant reduction in all events (fatal and non-fatal) in patients with angina (“all anginas”) in the clofibrate-treated group; the rate was reduced by 53%.Clofibrate did not alter the overall mortality or morbidity rates in patients admitted to the trial with recent myocardial infarction without preceding angina of more than three months'' duration. In one subgroup there was a statistically significant adverse effect in the clofibrate-treated group. The lack of any overall effect in patients with myocardial infarction might be related to the unexpectedly low mortality rate (2·97%) in the placebo group; it is usually in the region of 4-9% per annum after first myocardial infarction.In patients categorized as “all anginas” there was significant reduction in events whether the initial serum cholesterol level was high (greater than 260 mg/100 ml) or normal. Clofibrate seemed to have a small but not significant beneficial effect in patients with myocardial infarction with initially high serum cholesterol levels, but was of no value in those with initially normal serum cholesterol levels. There was no significant relationship between the response or lack of response of serum cholesterol to clofibrate and the incidence of events either in patients with angina or in those with infarction.The main conclusion of this trial is that clofibrate had a beneficial effect in reducing mortality and, to a lesser extent, morbidity in patients who presented with angina (“all anginas”). This effect was independent of initial serum cholesterol levels or the extent to which serum cholesterol was lowered. The drug had no significant overall effect on prognosis in patients with myocardial infarction alone.     

Action of Deflocculating Agents on Saccharomyces cerevisiae Class III Brewer''s Yeast

Earlier work with a fluorescent aid indicated that flocculent brewer's yeast may have more surface lipids than nonflocculent types. Organic solvents were checked against flocculent Gilliland yeasts. It was found that those reagents which affect “free” lipids had no dispersive action, and those which remove “bound” fats had a powerful dispersive action against such yeasts. There was no indication that such an action could be correlated with other physical properties of the solvents. The uranyl ion is known for its ability to complex with phospholipids, and it was found to have a powerful dispersive action on Gilliland yeasts. Its effect was compared with that of glucose in its dispersion of yeast flocs, and possible cell “sites” were suggested. This, along with other work, suggests the possibility that lipids are directly or indirectly involved in yeast flocculation.     

SERUM LIPIDS IN NORMAL AND ABNORMAL SUBJECTS—Observations on Controlled Experiments

The relationship of diet to serum lipids and to atherosclerosis is a controversial subject. The data presented indicate that diets containing very large amounts of vegetable fat are consistently associated with a sharp fall in serum cholesterol and phospholipid, whereas administration of equal amounts of fat of animal origin is associated with a rise of the serum lipids to levels noted on an average mixed diet.In critical evaluation of elderly hospitalized diabetic patients with advanced atherosclerosis it was observed that there was close mathematical correlation between serum content of cholesterol, “lipoproteins,” and phospholipids. There was no obvious correlation between the degree or kind of atherosclerosis and any one of the lipid entities followed. Coronary occlusion occurred in a patient with one of the lowest levels of cholesterol and of lipoprotein.     

Action of Deflocculating Agents on Saccharomyces cerevisiae Class III Brewer's Yeast

Earlier work with a fluorescent aid indicated that flocculent brewer''s yeast may have more surface lipids than nonflocculent types. Organic solvents were checked against flocculent Gilliland yeasts. It was found that those reagents which affect “free” lipids had no dispersive action, and those which remove “bound” fats had a powerful dispersive action against such yeasts. There was no indication that such an action could be correlated with other physical properties of the solvents. The uranyl ion is known for its ability to complex with phospholipids, and it was found to have a powerful dispersive action on Gilliland yeasts. Its effect was compared with that of glucose in its dispersion of yeast flocs, and possible cell “sites” were suggested. This, along with other work, suggests the possibility that lipids are directly or indirectly involved in yeast flocculation.     

High Total Cholesterol in Peripheral Blood Correlates with Poorer Hearing Recovery in Idiopathic Sudden Sensorineural Hearing Loss

Idiopathic sudden sensorineural hearing loss (ISSHL) is a common otologic emergency whose cause is still unclear. The importance of blood lipids in the pathogenesis of ISSHL is widely reported in literature. In fact elevated levels of low density lipoprotein cholesterol (LDL), total cholesterol (TC) and apolipoprotein B (Apo-B) have been proposed as risk factors for this pathology. No correlation has been described between serum lipid parameters and the prognosis of ISSHL. Aim of the present study was to identify prognostic factors associated with hearing recovery in a group of patients affected by ISSHL. Ninety-four patients with the diagnosis of ISSHL hospitalized between March 2013 and October 2014 were included in this study. Patients’ blood sampling and hearing assessments were carried out. Patients were divided into two groups as “recovered” and “unrecovered”, according to their response to the treatment. We found a statistically significant higher level of total cholesterol in the unrecovered group compared to the recovered one (p = 0.03). None of the other routine laboratory parameters have shown a statistically significant difference between the patients successfully treated and patients with poor outcomes. Total cholesterol concentrations may be a prognostic factor for recovery in ISSHL and should be assessed together with routine tests in patients with this condition. The other routine laboratory parameters seem to have no effect on the development and prognosis of this pathology.     

Relation between Serum Cholesterol and Triglyceride Concentration and Haemoglobin Values in Non-anaemic Healthy Persons

In a study of 2,458 healthy non-anaemic subjects a positive correlation was found between haemoglobin levels and serum cholesterol and triglyceride levels. This may be due to simple changes in plasma volume, which may increase when the haemoglobin concentration decreases. Such an association between plasma lipid levels and haemoglobin values might be of importance in the aetiology of coronary heart disease, as a high haemoglobin value is known to be a “risk factor” in myocardial infarction.     

The Association between Pre-Treatment Serum 25-Hydroxyvitamin D and Survival in Newly Diagnosed Stage IV Prostate Cancer

Background/Aims

Emerging evidence in the literature suggests a positive association between serum 25-hydroxyvitamin D [25(OH)D], a standard indicator of vitamin D status, and survival in certain types of cancer. We investigated this relationship in newly diagnosed stage IV prostate cancer patients.

Methods

A consecutive cohort of 125 newly diagnosed stage IV prostate cancer patients underwent a baseline serum 25(OH)D evaluation prior to receiving any treatment at our institution between January 2008 and December 2011. We used the vitamin D categories of “deficient (<20 ng/ml)”, “insufficient (20 to 32 ng/ml)”, and “sufficient (>32 ng/ml)”. Cox regression was used to evaluate the prognostic significance of serum 25(OH)D after adjusting for relevant confounders.

Results

Mean age at diagnosis was 60 years. Of the 125 patients, 32 (25.6%) were deficient, 49 (39.2%) were insufficient and 44 (35.2%) were sufficient in vitamin D at the time of diagnosis. The median survival in deficient, insufficient and sufficient cohorts was 47.8, 44.0 and 52.6 months respectively (p = 0.60). On univariate analysis, four variables demonstrated a statistically significant association with survival: nutritional status, bone metastasis, corrected serum calcium and serum albumin (p<0.05 for all). On multivariate analysis, five variables demonstrated statistically significant associations with survival: hospital location, age, bone metastasis, serum albumin and corrected serum calcium (p<0.05 for all). Serum vitamin D status was not significant on either univariate or multivariate analysis.

Conclusion

Contrary to previously published research, we found no significant association between pre-treatment serum 25(OH)D and survival in newly diagnosed stage IV prostate cancer patients. The lack of a significant association between serum vitamin D and survival in our study could perhaps be due to the fact that the disease was far too advanced in our patients for vitamin D levels to have any impact on prognosis.     

Serum Lipids in Cholelithiasis: Effect of Chenodeoxycholic Acid Therapy

Hypercholesterolaemia has been predicted as a possible complication of chenodeoxycholic acid treatment for gall stones. To exclude this, fasting serum lipids were measured in patients with stones before and at monthly intervals for six months after starting chenodeoxycholic acid. Before treatment half of a group of 36 patients with presumed cholesterol gall stones had serum cholesterol levels exceeding 260 mg/100 ml or serum triglyceride values greater than 160 mg/100 ml or both; these lipid levels were significantly greater than those in control subjects matched for age and sex. Treatment with chenodeoxycholic acid (0·5-1·5 g/day by mouth) did not change serum cholesterol levels but did significantly reduce serum triglyceride concentrations from a pretreatment level of 118 (± S.E. of mean 11·7) mg/100 ml to 95 (± 7·2) mg/100 ml after six months of therapy. The mechanism of this triglyceride-lowering action of chenodeoxycholic acid is not known, but it may have therapeutic value in patients with hypertriglyceridaemia.     

Concentrations of carbohydrates and lipids of guinea pigs after five days starvation

The concentrations of serum total lipids, cholesterol and triglycerides of guinea pigs were determined under normal conditions and after 5 days fasting. Serum glucose and liver glycogen levels were also estimated under both conditions. The amounts of serum total lipids and cholesterol were significantly increased as a result of starvation, whereas, fasting had no significant effect on serum triglycerides. Liver glycogen was rapidly decreased in response to starvation in a highly significant manner. However, starvation did not affect serum glucose of guinea pigs.     

Molecular basis of accessible plasma membrane cholesterol recognition by the GRAM domain of GRAMD1b

Cholesterol is essential for cell physiology. Transport of the “accessible” pool of cholesterol from the plasma membrane (PM) to the endoplasmic reticulum (ER) by ER‐localized GRAMD1 proteins (GRAMD1a/1b/1c) contributes to cholesterol homeostasis. However, how cells detect accessible cholesterol within the PM remains unclear. We show that the GRAM domain of GRAMD1b, a coincidence detector for anionic lipids, including phosphatidylserine (PS), and cholesterol, possesses distinct but synergistic sites for sensing accessible cholesterol and anionic lipids. We find that a mutation within the GRAM domain of GRAMD1b that is associated with intellectual disability in humans specifically impairs cholesterol sensing. In addition, we identified another point mutation within this domain that enhances cholesterol sensitivity without altering its PS sensitivity. Cell‐free reconstitution and cell‐based assays revealed that the ability of the GRAM domain to sense accessible cholesterol regulates membrane tethering and determines the rate of cholesterol transport by GRAMD1b. Thus, cells detect the codistribution of accessible cholesterol and anionic lipids in the PM and fine‐tune the non‐vesicular transport of PM cholesterol to the ER via GRAMD1s.     

Correlation between the extent of coronary atherosclerosis and lipid profile

Increased concentration of low density lipoprotein (LDL) cholesterol or decreased level of high density lipoprotein (HDL) cholesterol are important risk factors for coronary atherosclerosis. However, an independent association of triglycerides (TG) with atherosclerosis is uncertain.The aim of this prospective study was to evaluate the relationship between serum lipid levels and the extent of coronary atherosclerosis in patients with suspected coronary artery disease (CAD) and no previous myocardial infarction who were not treated with lipids lowering therapy or low-lipid diet.The study was conducted in 141 patients (53.6 ± 7.8 years old; 32 female) who underwent a routine coronary angiography for CAD diagnosis. A modified angiographic Gensini Score (GS) was used to reflect the extent of coronary atherosclerosis. Fasting serum lipid concentrations were determined using cholesterol esterase/peroxidase (CHOD/PAP) enzymatic method for total cholesterol and its fractions and lipase glycerol kinase (GPO/PAP) enzymatic method TG evaluation. The association of Gensini Score with variables characterising lipid profile was analysed with the use of Pearson correlation (r co-efficient; p value).GS was positively correlated with total cholesterol (r = 0.404; p < 0.001), LDL cholesterol (r = 0.484; p < 0.001) and TG (r = 0.235; p = 0.005). There was a negative correlation between Gensini Score and HDL cholesterol (r = –0.396; p < 0.001).In angina pectoris patients with no previous myocardial infarction, the extent of coronary atherosclerosis is positively correlated with pro-atherogenic lipids, i.e. total cholesterol, LDL cholesterol and TG and negatively correlated with antiatherogenic HDL cholesterol.     

The HDL hypothesis: does high-density lipoprotein protect from atherosclerosis?

There is unequivocal evidence of an inverse association between plasma high-density lipoprotein (HDL) cholesterol concentrations and the risk of cardiovascular disease, a finding that has led to the hypothesis that HDL protects from atherosclerosis. This review details the experimental evidence for this “HDL hypothesis”. In vitro studies suggest that HDL has a wide range of anti-atherogenic properties but validation of these functions in humans is absent to date. A significant number of animal studies and clinical trials support an atheroprotective role for HDL; however, most of these findings were obtained in the context of marked changes in other plasma lipids. Finally, genetic studies in humans have not provided convincing evidence that HDL genes modulate cardiovascular risk. Thus, despite a wealth of information on this intriguing lipoprotein, future research remains essential to prove the HDL hypothesis correct.     

A Major Fraction of Glycosphingolipids in Model and Cellular Cholesterol-containing Membranes Is Undetectable by Their Binding Proteins

Glycosphingolipids (GSLs) accumulate in cholesterol-enriched cell membrane domains and provide receptors for protein ligands. Lipid-based “aglycone” interactions can influence GSL carbohydrate epitope presentation. To evaluate this relationship, Verotoxin binding its receptor GSL, globotriaosyl ceramide (Gb₃), was analyzed in simple GSL/cholesterol, detergent-resistant membrane vesicles by equilibrium density gradient centrifugation. Vesicles separated into two Gb_3/cholesterol-containing populations. The lighter, minor fraction (<5% total GSL), bound VT1, VT2, IgG/IgM mAb anti-Gb₃, HIVgp120 or Bandeiraea simplicifolia lectin. Only IgM anti-Gb₃, more tolerant of carbohydrate modification, bound both vesicle fractions. Post-embedding cryo-immuno-EM confirmed these results. This appears to be a general GSL-cholesterol property, because similar receptor-inactive vesicles were separated for other GSL-protein ligand systems; cholera toxin (CTx)-GM1, HIVgp120-galactosyl ceramide/sulfatide. Inclusion of galactosyl or glucosyl ceramide (GalCer and GlcCer) rendered VT1-unreactive Gb₃/cholesterol vesicles, VT1-reactive. We found GalCer and GlcCer bind Gb₃, suggesting GSL-GSL interaction can counter cholesterol masking of Gb₃. The similar separation of Vero cell membrane-derived vesicles into minor “binding,” and major “non-binding” fractions when probed with VT1, CTx, or anti-SSEA4 (a human GSL stem cell marker), demonstrates potential physiological relevance. Cell membrane GSL masking was cholesterol- and actin-dependent. Cholesterol depletion of Vero and HeLa cells enabled differential VT1B subunit labeling of “available” and “cholesterol-masked” plasma membrane Gb₃ pools by fluorescence microscopy. Thus, the model GSL/cholesterol vesicle studies predicted two distinct membrane GSL formats, which were demonstrated within the plasma membrane of cultured cells. Cholesterol masking of most cell membrane GSLs may impinge many GSL receptor functions.     

Anatomic Characteristics Associated with Head Splitting in Cabbage (Brassica oleracea var. capitata L.)

Cabbage belonging to Brassicaceae family is one of the most important vegetables cultivated worldwide. The economically important part of cabbage crop is head, formed by leaves which may be of splitting and non-splitting types. Cabbage varieties showing head splitting causes huge loss to the farmers and therefore finding the molecular and structural basis of splitting types would be helpful to breeders. To determine which anatomical characteristics were related to head-splitting in cabbage, we analyzed two contrasting cabbage lines and their offspring using a field emission scanning electron microscope. The inbred line “747” is an early head-splitting type, while the inbred line “748” is a head-splitting-resistant type. The petiole cells of “747” seems to be larger than those of “748” at maturity; however, there was no significant difference in petiole cell size at both pre-heading and maturity stages. The lower epidermis cells of “747” were larger than those of “748” at the pre-heading and maturity stages. “747” had thinner epidermis cell wall than “748” at maturity stage, however, there was no difference of the epidermis cell wall thickness in the two lines at the pre-heading stage. The head-splitting plants in the F₁ and F₂ population inherited the larger cell size and thinner cell walls of epidermis cells in the petiole. In the petiole cell walls of “747” and the F₁ and F₂ plants that formed splitting heads, the cellulose microfibrils were loose and had separated from each other. These findings verified that anomalous cellulose microfibrils, larger cell size and thinner-walled epidermis cells are important genetic factors that make cabbage heads prone to splitting.     

Clinical Investigation in Psychiatry

A study involving correlations between personality and the fasting serum cholesterol level of normal volunteers on a fat-free diet was used to illustrate techniques of clinical investigation in psychiatry. Precise data were not quoted, but the procedure was described to show how behavioural studies differ from biological ones. Somatotyping (no significant correlation), excretion of catecholamines under stress (raised with high cholesterol levels) and classical conditioning (no significant correlation) were used as examples of simple biological functions. These were contrasted with trait ratings where one observer predicted cholesterol levels with a high degree of accuracy and another with a low and unreliable one. It seemed that the most important trait being rated was “aggressiveness”, and this was probably differentially elicited by the two observers, the one male and authoritarian, the other female and permissive. Such an interaction distorted the information obtained to a degree seldom seen in other data-gathering situations. Estimated and actual achievement on a competitive pin-ball game failed to show significant correlations with other traits. Questionnaires on the attitudes of the subjects'' mothers suggested some correlation between severity of training and aggressivity. The techniques of personality investigation described embraced behavioural observations which, it was suggested, were ill-taught in existing undergraduate medical curricula.     

Modification of myosin isozymes and SR Ca2+-pump ATPase of the diabetic rat heart by lipid-lowering interventions

To define metabolic influences on cardiac myosin expression and sarcoplasmic reticulum (SR) Ca²⁺-stimulated ATPase streptozotocin-diabetic rats were treated for 9–10 wk with etomoxir, an inhibitor of carnitine palmitoyl transferase I (CPT-1) and fatty acid synthesis, or an antilipolytic drug, acipimox. Etomoxir reduced myosin V₃ of diabetic rats but did not normalize it. However, the high serum triglyceride, free-fatty acid and cholesterol concentrations in diabetic animals were greatly reduced. After bypassing the CPT-1 inhibition with a medium-chain fatty acid (miglyol) diet, the V₃ contents and serum lipids were still reduced in the etomoxir-treated diabetic rats; V₃ was also reduced in diabetic rats fed miglyol or treated with acipimox. Since low serum insulin or triiodothyronine concentrations in diabetic rats were not improved by these interventions but changes in V₃ were correlated with those in triglyceride, free-fatty acid and cholesterol concentrations, it is likely that myosin may be influenced by some metabolic factors. To assess the role of adrenergic influences, diabetic rats (7–8 wk) were treated with an antisympathotonic drug, moxonidine, a -adrenoceptor blocking drug, propranolol, and a bradycardic drug, tedisamil. Myosin V₃ was not reduced significantly in moxonidine-treated or propranolol-treated rats in comparison to untreated diabetic rats. Serum thyroid hormones and insulin were not altered, whereas triglycerides were reduced but not significantly by these antiadrenergic agents. Lowering serum lipids in diabetic rats by treatment with etomoxir, miglyol and acipimox increased the depressed SR Ca²⁺-stimulated ATPase activity. On the other hand, in diabetic rats treated with moxonidine, propranolol or tedisamil, the ATPase activity was not increased significantly. These results suggest that normalization of blood lipids is important for improving subcellular organelle function in diabetic hearts with impaired glucose utilization.     

Hongyuan Yang: Tracking lipids,one droplet at a time

Hongyuan Yang investigates lipid trafficking and lipid droplet biogenesis.

Hongyuan Yang grew up in a small city east of Beijing, China. From his childhood, Hongyuan recalls that “food was not abundant, so I was hungry at times, but education was free and good.” Driven by his curiosity for science, after completing his undergraduate studies at Peking University Health Science Center, China, he enrolled at Columbia University, NY, for his doctoral training. Under the guidance of his advisor, Dr. Stephen Sturley, Hongyuan studied lipids in budding yeast. The laboratory’s research department fostered a strong interest in lipids and atherosclerosis, and after earning his PhD, Hongyuan obtained a faculty position at the National University of Singapore (NUS) in 1999. In 2007, he moved to the University of New South Wales (UNSW) in Sydney, Australia, to continue his scientific journey exploring lipids. We contacted Hongyuan to learn more about his career and interests.Hongyuan Robert Yang. Photo courtesy of UNSW.What interested you about lipids?My five-year doctoral study focused entirely on the enzymes Sterol O-Acyltransferases (SOAT, also known as ACAT, Acyl-CoA Cholesterol Acyltransferases), which catalyze the formation of sterol esters from sterols/cholesterol and fatty acyl CoAs (1). SOATs, integral membrane proteins of the ER, are potential therapeutic targets for heart disease and Alzheimer’s disease. Since then, I have been fascinated by two things related to SOAT: first, what happens upstream of SOAT, i.e., how exogenous cholesterol reaches SOAT/ER; and second, what happens downstream of SOAT, i.e., how its product—cholesterol esters—is stored in cells in the form of lipid droplets (LDs).These are fundamental questions in cell biology. While reading on how cholesterol arrives at the ER for esterification by SOAT/ACAT in the late 1990s, I realized that the trafficking of most lipids was poorly characterized with little molecular insight. Significant progress has been made in the last 20 years, but the lack of tools that track the movement of lipids has hampered our understanding of the selectivity, efficacy, and kinetics of lipid trafficking. Few cell biologists cared about LDs ∼20 years ago, even though LDs are prominent cellular structures in many disease conditions. Each LD comprises a hydrophobic core of storage lipids (triglycerides and sterol esters) wrapped by a monolayer of phospholipids. Largely considered inert lipid granules, LDs originate from the ER and are relatively simple cellular structures as compared with other organelles (see image). Now, we know that LDs are not that simple: their biogenesis is tightly regulated, they actively interact with other organelles, and they regulate many aspects of cellular function as well as disease progression. Astonishingly, we still have little understanding of how LDs originate from the ER. I am very much intrigued by the complexity of these two seemingly simple cellular processes, i.e., lipid trafficking and LD biogenesis.What are some of the scientific questions currently of interest in your laboratory?We are currently focusing on how LDs originate from the ER. The first significant paper from my own laboratory was the discovery of seipin as a key regulator of LD formation (2). Results from many groups have demonstrated that seipin can organize the formation of LDs; however, the exact molecular function of seipin remains mysterious. Our data suggest that seipin may directly impact the level and/or distribution of lipids such as phosphatidic acid near sites of LD biogenesis, and the effect of seipin deficiency on LD formation is secondary to changes in local lipids. We are now working hard to test this hypothesis. Moreover, data from my laboratory and others indicated that nonbilayer lipids may have a greater impact on the biogenesis of LDs than that of other ER-derived structures, such as COPII vesicles. This may result from the monolayer nature of the LD surface. We hope to dissect the dynamic changes of lipids at ER domains where LDs are born. More broadly, the ER is a fascinating organelle to me. The simple division of ER into sheets and tubules does not reflect the dynamic nature of this organelle. Dissecting the composition and organization of lipids and proteins of the ER would help answer key questions relating to LD biogenesis, and it is therefore one of our future directions.Another major focus is to understand how cholesterol and phosphatidylserine are moved between organelles. We have been working on how low-density lipoprotein (LDL)–derived cholesterol (LDL-C) reaches the ER for two decades. The release of LDL-C from lysosomes requires the Niemann Pick C1&2 proteins, whose malfunction causes lysosomal cholesterol accumulation and a lethal genetic disorder affecting young children. The Ara Parseghian Medical Research Foundation has led the way in supporting research into cholesterol trafficking, and I take this opportunity to thank their generous support. Once released from lysosomes, LDL-C is believed to reach the plasma membrane first and then the ER. We identified ORP2 as a possible carrier of LDL-C to the plasma membrane using a PI(4,5)P₂ gradient (3). There must be other carriers and/or pathways because ORP2 deficiency only causes a minor accumulation of cholesterol in lysosomes. Another interesting question is what prevents LDL-C from reaching the ER directly from lysosomes, given the close contact between lysosomes and the ER. We reported that ORP5 may bring LDL-C directly to the ER (4). However, it was later found that ORP5 binds and transfers phosphatidylserine, not cholesterol. Thus, our observed link between ORP5 and cholesterol is through some indirect yet unknown mechanism. We have been perplexed by these observations for many years, but a recent study demonstrated that phosphatidylserine is required for the trafficking of LDL-C, establishing a close link between cholesterol and phosphatidylserine (5). We are now trying to understand how the trafficking and distribution of cholesterol, phosphatidylserine, and PI(4,5)P₂ are interconnected. For a long time, I felt that it was impossible to figure out the molecular details governing the cellular trafficking of lipids due to redundant pathways and a lack of tools to track lipids. Recent progress in this field has given me hope.Lipid droplets in a HeLa cell are shown in red (BODIPY), with their surface in green. DAPI (blue) labels DNA. Image courtesy of Hongyuan Yang.What kind of approach do you bring to your work?Besides honesty and open-mindedness, we emphasize rigor and comprehensiveness. We often make our initial discoveries in cell-based screens. This approach has many advantages, but it also gives rise to artifacts and cell-line specific observations. We aim to complement our initial findings with biochemical and structural analyses in vitro as well as animal studies in vivo. To further establish the reproducibility of our data, I often ask my close friends and collaborators to independently repeat the key findings of a study before submission. It generally takes a long time for us to complete a study, but I believe the effort will pay off in the long run.What did you learn during your training that helped prepare you for being a group leader? What were you unprepared for?During my PhD at Columbia, I was most impressed with the general attitude of my mentors toward research. No matter how much they have achieved, they take every new experiment and every poster presentation seriously.As I did not have postdoctoral training, I was somewhat unprepared at the beginning of my independent career. One difficult challenge was knowing when to finish a paper and project. We often kept working and working. I have now gotten a lot better.You’ve done research on three continents throughout your career. Can you tell us about some of these transitions?During the last year of my doctoral studies at Columbia, I was offered a lecturer position by the Department of Biochemistry at NUS. It was a very hard decision to leave the United States, but I was excited by the prospect of starting my own laboratory at a top institution. Life at NUS was very good overall, despite some struggles. I had to make ∼700 slides for teaching during the first year and my start-up fund was 10,000 Singapore dollars (~6,000 USD). But the graduate students were fully supported by the university, and most of them are hard working and talented. The crucial screen that led to the discovery of seipin as a key regulator of LD formation was performed at NUS (2). I enjoyed my time at NUS, where I was promoted and tenured. However, my family and I could not get used to the heat and humidity. We looked for a place with better climate, and it happened that my current employer, UNSW, had an opening in 2006. Moving continents with two kids was very disruptive, and I had zero publications in 2007. Our work on seipin was delayed and almost got scooped. I was also very worried about funding in Australia since I hardly knew anyone and the funding system. It turned out that the Australian community was very supportive of our research from day one. I have also been very fortunate to receive generous support from the Ara Parseghian Medical Research Foundation, based in the United States, after my move to Sydney.Hongyuan’s “metabolism team” after a basketball game. Photo courtesy of Hongyuan Yang.What has been the biggest accomplishment in your career so far?While I am mostly recognized for discovering seipin’s role in lipid droplet formation, I am prouder of the work we have done on lipid trafficking and the oxysterol binding proteins. We struggled mightily for the first 15 years. At one point in 2015, I seriously considered abandoning this line of research. But we persisted and discovered their roles in regulating plasma membrane PI(4,5)P₂ and cholesterol, as well as in lipid droplet formation (3, 6).What has been the biggest challenge in your career so far?The biggest challenge has to do with the subject of my research topic: the fundamental cell biology of lipids. The sorting, distribution, and storage of cellular lipids are clearly very important topics in biology, but they are sometimes too fundamental to explain to funding agencies and new students. These days, lipid research is not as “sexy” as other topics. But there are so many unanswered questions in lipidology. I strongly believe that lipid research is going to be the next “big thing” as new techniques such as cryoEM now allow us to appreciate lipids and membrane proteins with unprecedented clarity.Who were your key influences early in your career?Besides mentors and teachers at Columbia, I really enjoyed reading and studying the works by Drs. Mike Brown and Joseph Goldstein, Ta-Yuan Chang, and Scott Emr. While they were not my teachers, their work inspired and impacted many young scientists, including me.What is the best advice you have been given?I have been given many pieces of great advice during my career. The best one in my view is “Less is more.” I was once told, “You would be better off with a lab of six than twelve.” Initially, I did not get it because I thought that a bigger group would allow me to explore more directions and be more productive. The reality is that, as a little-known junior researcher, few experienced people would join my laboratory. Funding is also a major limiting factor. Supervising a large number of students is fulfilling, but it also takes away some of my own time to think critically about the projects. I have largely kept my group under six, and this allows me to better supervise and guide the trainees. People say, “Once your team has more than 15 members, you become a manager instead of a scientist.” My own experience corroborates that statement because I struggled quite a bit when my group reached 12 at one point.What hobbies do you have?I am heavily into sports, especially basketball and tennis. I follow the NBA closely, and Jeremy Lin is my hero. I still play basketball at least twice a week. I am the captain of a basketball team comprised of scientists working on metabolism (see image). We play real, refereed basketball games against local teams during conferences. As I am getting older, I have also picked up tennis. I watch coaching videos on YouTube but still need a lot of work on my forehand. Through sports, I learned teamwork and the spirit of fighting to the last second. If I were not a scientist, I would probably run a sports-related business.What has been your biggest accomplishment outside of the laboratory?I got married and had children relatively early. Both of my kids are now in college and they appear to be decent human beings. I have been extremely lucky because my wife did most of the heavy lifting in looking after the kids. It was still a struggle for me to balance work and parental duties during the early days of my independent career. I am very proud and happy with where we are as a family right now.Any tips for a successful research career?Everyone is unique. Knowing your strengths and especially your weaknesses can be crucial to your success. My undergraduate training was in medicine and health management, and my PhD work focused on genetics and cell biology, so my understanding of physical chemistry is rather inadequate. I am also very bad at developing new methods. To alleviate these deficiencies, I constantly monitor new methods in my field and I purposefully look for collaborators with strong chemistry backgrounds. I have benefited immensely from such efforts.     

Respiratory Insufficiency in Acute Myocardial Infarction

Arterial blood gases and pH were assessed in 115 patients who had suffered a myocardial infarction, with or without complicating cardiogenic shock or cardiac standstill. In 11 of the 78 uncomplicated cases and in 16 of the 37 complicated cases, the arterial O₂ tension was much lower than would be expected on the basis of a three-fold drop in cardiac output, indicating considerable right to left shunting. The death rate in the patients with uncomplicated myocardial infarction was 32% and that of the complicated cases 65%. In both groups it was greatest when the arterial pH was low, indicating that correction of the acidosis is essential. In many instances administration of 100% oxygen is inadequate to restore the oxygen tension to normal levels, and controlled ventilation may be necessary to maintain adequate alveolar ventilation. The findings indicate the necessity for repeated assessment of the arterial blood gas tensions and pH in any patient who has suffered a myocardial infarction. If the management of such patients is designed to provide adequate oxygenation, to maintain adequate alveolar ventilation and to correct the acid-base disturbances, the patient may be tided over the stage of “cardiac pump failure”.     

Using the “reverse Warburg effect” to identify high-risk breast cancer patients: Stromal MCT4 predicts poor clinical outcome in triple-negative breast cancers

We have recently proposed a new model of cancer metabolism to explain the role of aerobic glycolysis and L-lactate production in fueling tumor growth and metastasis. In this model, cancer cells secrete hydrogen peroxide (H₂O₂), initiating oxidative stress and aerobic glycolysis in the tumor stroma. This, in turn, drives L-lactate secretion from cancer-associated fibroblasts. Secreted L-lactate then fuels oxidative mitochondrial metabolism (OXPHOS) in epithelial cancer cells, by acting as a paracrine onco-metabolite. We have previously termed this type of two-compartment tumor metabolism the “reverse Warburg effect,” as aerobic glycolysis takes place in stromal fibroblasts, rather than epithelial cancer cells. Here, we used MCT4 immunostaining of human breast cancer tissue microarrays (TMAs; >180 triple-negative patients) to directly assess the prognostic value of the “reverse Warburg effect.” MCT4 expression is a functional marker of hypoxia, oxidative stress, aerobic glycolysis and L-lactate efflux. Remarkably, high stromal MCT4 levels (score = 2) were specifically associated with decreased overall survival (<18% survival at 10 years post-diagnosis). In contrast, patients with absent stromal MCT4 expression (score = 0), had 10-year survival rates of ∼97% (p-value < 10⁻³²). High stromal levels of MCT4 were strictly correlated with a loss of stromal Cav-1 (p-value < 10⁻¹⁴), a known marker of early tumor recurrence and metastasis. In fact, the combined use of stromal Cav-1 and stromal MCT4 allowed us to more precisely identify high-risk triple-negative breast cancer patients, consistent with the goal of individualized risk-assessment and personalized cancer treatment. However, epithelial MCT4 staining had no prognostic value, indicating that the “conventional” Warburg effect does not predict clinical outcome. Thus, the “reverse Warburg effect” or “parasitic” energy-transfer is a key determinant of poor overall patient survival. As MCT4 is a druggable target, MCT4 inhibitors should be developed for the treatment of aggressive breast cancers, and possibly other types of human cancers. Similarly, we discuss how stromal MCT4 could be used as a biomarker for identifying high-risk cancer patients that could likely benefit from treatment with FDA-approved drugs or existing MCT-inhibitors (such as, AR-C155858, AR-C117977 and AZD-3965).Key words: caveolin-1, oxidative stress, pseudohypoxia, lactate shuttle, MCT4, metabolic coupling, tumor stroma, predictive biomarker, SLC16A3, monocarboxylic acid transporter, two-compartment tumor metabolism     

Nicotinic acid and DP1 blockade: studies in mouse models of atherosclerosis

The use of nicotinic acid to treat dyslipidemia is limited by induction of a “flushing” response, mediated in part by the interaction of prostaglandin D₂ (PGD₂) with its G-protein coupled receptor, DP1 (Ptgdr). The impact of DP1 blockade (genetic or pharmacologic) was assessed in experimental murine models of atherosclerosis. In Ptgdr^−/−ApoE^−/− mice versus ApoE^−/− mice, both fed a high-fat diet, aortic cholesterol content was modestly higher (1.3- to 1.5-fold, P < 0.05) in Ptgdr^−/−ApoE^−/− mice at 16 and 24 weeks of age, but not at 32 weeks. In multiple ApoE^−/− mouse studies, a DP1-specific antagonist, L-655, generally had a neutral to beneficial effect on aortic lipids in the presence or absence of nicotinic acid treatment. In a separate study, a modest increase in some atherosclerotic measures was observed with L-655 treatment in Ldlr^−/− mice fed a high-fat diet for 8 weeks; however, this effect was not sustained for 16 or 24 weeks. In the same study, treatment with nicotinic acid alone generally decreased plasma and/or aortic lipids, and addition of L-655 did not negate those beneficial effects. These studies demonstrate that inhibition of DP1, with or without nicotinic acid treatment, does not lead to consistent or sustained effects on plaque burden in mouse atherosclerotic models.