Pharmacokinetics of Isoniazid,Pyrazinamide, and Ethambutol in Newly Diagnosed Pulmonary TB Patients in Tanzania

Exposure to lower-than-therapeutic levels of anti-tuberculosis drugs is likely to cause selection of resistant strains of Mycobacterium tuberculosis and treatment failure. The first-line anti-tuberculosis (TB) regimen consists of rifampicin, isoniazid, pyrazinamide, and ethambutol, and correct management reduces risk of TB relapse and development of drug resistance. In this study we aimed to investigate the effect of standard of care plus nutritional supplementation versus standard care on the pharmacokinetics of isoniazid, pyrazinamide and ethambutol among sputum smear positive TB patients with and without HIV. In a clinical trial in 100 Tanzanian TB patients, with or without HIV infection, drug concentrations were determined at 1 week and 2 months post initiation of anti-TB medication. Data was analysed using population pharmacokinetic modelling. The effect of body size was described using allometric scaling, and the effects of nutritional supplementation, HIV, age, sex, CD4+ count, weight-adjusted dose, NAT2 genotype, and time on TB treatment were investigated. The kinetics of all drugs was well characterised using first-order elimination and transit compartment absorption, with isoniazid and ethambutol described by two-compartment disposition models, and pyrazinamide by a one-compartment model. Patients with a slow NAT2 genotype had higher isoniazid exposure and a lower estimate of oral clearance (15.5 L/h) than rapid/intermediate NAT2 genotype (26.1 L/h). Pyrazinamide clearance had an estimated typical value of 3.32 L/h, and it was found to increase with time on treatment, with a 16.3% increase after the first 2 months of anti-TB treatment. The typical clearance of ethambutol was estimated to be 40.7 L/h, and was found to decrease with age, at a rate of 1.41% per year. Neither HIV status nor nutritional supplementations were found to affect the pharmacokinetics of these drugs in our cohort of patients.     

Cardiac Dysfunction in a Porcine Model of Pediatric Malnutrition

Background

Half a million children die annually of severe acute malnutrition and cardiac dysfunction may contribute to the mortality. However, cardiac function remains poorly examined in cases of severe acute malnutrition.

Objective

To determine malnutrition-induced echocardiographic disturbances and longitudinal changes in plasma pro-atrial natriuretic peptide and cardiac troponin-T in a pediatric porcine model.

Methods and Results

Five-week old piglets (Duroc-x-Danish Landrace-x-Yorkshire) were fed a nutritionally inadequate maize-flour diet to induce malnutrition (MAIZE, n = 12) or a reference diet (AGE-REF, n = 12) for 7 weeks. Outcomes were compared to a weight-matched reference group (WEIGHT-REF, n = 8). Pro-atrial natriuretic peptide and cardiac troponin-T were measured weekly. Plasma pro-atrial natriuretic peptide decreased in both MAIZE and AGE-REF during the first 3 weeks but increased markedly in MAIZE relative to AGE-REF during week 5–7 (p≤0.001). There was overall no difference in plasma cardiac troponin-T between groups. However, further analysis revealed that release of cardiac troponin-T in plasma was more frequent in AGE-REF compared with MAIZE (OR: 4.8; 95%CI: 1.2–19.7; p = 0.03). However, when release occurred, cardiac troponin-T concentration was 6.9-fold higher (95%CI: 3.0–15.9; p<0.001) in MAIZE compared to AGE-REF. At week 7, the mean body weight in MAIZE was lower than AGE-REF (8.3 vs 32.4 kg, p<0.001), whereas heart-weight relative to body-weight was similar across the three groups. The myocardial performance index was 86% higher in MAIZE vs AGE-REF (p<0.001) and 27% higher in MAIZE vs WEIGHT-REF (p = 0.025).

Conclusions

Malnutrition associates with cardiac dysfunction in a pediatric porcine model by increased myocardial performance index and pro-atrial natriuretic peptide and it associates with cardiac injury by elevated cardiac troponin-T. Clinical studies are needed to see if the same applies for children suffering from malnutrition.     

Teaching acid/base physiology in the laboratory

Acid/base homeostasis is one of the most difficult subdisciplines of physiology for medical students to master. A different approach, where theory and practice are linked, might help students develop a deeper understanding of acid/base homeostasis. We therefore set out to develop a laboratory exercise in acid/base physiology that would provide students with unambiguous and reproducible data that clearly would illustrate the theory in practice. The laboratory exercise was developed to include both metabolic acidosis and respiratory alkalosis. Data were collected from 56 groups of medical students that had participated in this laboratory exercise. The acquired data showed very consistent and solid findings after the development of both metabolic acidosis and respiratory alkalosis. All results were consistent with the appropriate diagnosis of the acid/base disorder. Not one single group failed to obtain data that were compatible with the diagnosis; it was only the degree of acidosis/alkalosis and compensation that varied.     

Potomacanthus lobatus gen. et sp. nov., a new flower of probable Lauraceae from the Early Cretaceous (Early to Middle Albian) of eastern North America

A charcoalified fossil flower, Potomacanthus lobatus gen. et sp. nov., is described from the Early Cretaceous (Early to Middle Albian) Puddledock locality, Virginia, USA. Internal floral structure was studied using nondestructive synchrotron-radiation x-ray tomographic microscopy (SRXTM). The flower is bisexual and trimerous. The perianth consists of two whorls of tepals. The androecium has two whorls of fertile stamens. Anthers open by two distally hinged valves. The gynoecium consists of a single carpel that is plicate in the style and ascidiate in the ovary and contains a single pendant ovule. The fossil flower shares many similarities with flowers of extant Lauraceae and is unlike flowers of other families of Laurales. However, the fossil flower also differs in detail from all extant or fossil Lauraceae, particularly in configuration of the androecium. The new taxon, together with previously described but more fragmentary material from the Puddledock locality, provides the earliest fossil record of plants more closely related to Lauraceae than to any other extant family. It reveals several derived morphological characters that are potential synapomorphies among extant representatives of the family Lauraceae and contributes to the growing evidence for an early diversification of Laurales before the end of the Early Cretaceous.     

When Earth started blooming: insights from the fossil record

Recent palaeobotanical studies have greatly increased the quantity and quality of information available about the structure and relationships of Cretaceous angiosperms. Discoveries of extremely well preserved Cretaceous flowers have been especially informative and, combined with results from phylogenetic analyses of extant angiosperms (based mainly on molecular sequence data), have greatly clarified important aspects of early angiosperm diversification. Nevertheless, many questions still persist. The phylogenetic origin of the group itself remains as enigmatic as ever and, in some cases, newly introduced techniques from molecular biology have given confusing results. In particular, relationships between the five groups of extant seed plants remain uncertain, and it has sometimes proved difficult to reconcile estimates of the time of divergence between extant lineages made using a 'molecular clock' with the fossil record. One result, however, is becoming increasingly clear: a great deal of angiosperm diversity is extinct. Some groups of angiosperms were evidently more diverse in the past than they are today. In other cases, fossils defy assignment to extant groups at the family level or below. This raises the possibility that evolutionary conclusions based solely upon extant taxa that are merely relics of groups that were once much more diverse might be misled by the effects of extinction. It also introduces the possibility that some early enigmatic fossils might represent lineages that diverged from the main line of angiosperm evolution below the most recent common ancestor of all extant taxa. These, and other questions, are among those that need to be addressed by future palaeobotanical research.     

Patterns of floristic diversity in semi-natural coastal vegetation of Lebanon and implications for conservation

The current understanding of the status of the vegetation in Lebanon is largely derived from herbarium data and associated floristic studies produced by early 20th century field botanists. In common with other areas in the Mediterranean, the Lebanese coastline is highly threatened by unregulated development, yet current patterns of species richness along the Lebanese coastal zone are little studied. The objective of this study was to assess the floristic richness of the Lebanese coastal zone and to provide baseline information for conservation planning. For this purpose, permanent sample plots (6m×100m) were established in 26 selected vegetation communities in coastal habitats. Monthly field collections of plant specimens were undertaken between October 1999 and July 2000. A total of 441 species were collected and identified. None of the recorded species are currently considered globally threatened, but two are Lebanese endemics (Matthiola crassifolia Boiss. & Gaill., Origanum ehrenbergii Boiss.). Species richness varied between communities, ranging from six species in a littoral limestone pavement community to 113 in an abandoned terrace community. The similarity between communities, based on Sorensen indices, was low and a large number of species were recorded only once. Cluster analysis showed a grouping of different communities within locations in some instances and the clustering of similar community types regardless of location in others. Species richness in riparian and littoral communities consisted mostly of habitat non-specific species. The low community similarity, patchy species distribution, and predominance of habitat non-specific species all point to the need to complement in situ conservation measures with ex situ conservation.     

Phase I and II metabolism and carbohydrate metabolism in cultured cryopreserved porcine hepatocytes

Primary porcine hepatocytes were cryopreserved using freezing boxes or a programmable freezer (PF). Upon thawing and culturing in 12-well plates cryopreserved hepatocytes were compared with their fresh controls on days 1 and 2 after plating. Cryopreserved hepatocytes attached approximately as well as fresh hepatocytes and useful cultures were obtained. In cryopreserved hepatocytes, coumarin 7-hydroxylation, 6beta-testosterone hydroxylation and p-nitrophenol glucuronidation were reduced to about 10-40, 35 and 40%, respectively, compared to their fresh counterparts. Glycogen synthesis in cryopreserved hepatocytes was reduced to about 30% on day 1 of culture and about 47% on day 2 of culture compared to the synthesis in fresh hepatocytes. Both fresh and cryopreserved hepatocytes increased the synthesis by twofold in response to stimulation with insulin. Reduced basal levels of glycogen and of glycogen synthesis could be explained by an increased energy demand in cryopreserved hepatocytes needing to repair damages caused by cryopreservation. Glycogenolysis was reduced to about 50% in cryopreserved hepatocytes and gluconeogenesis to about 40% of the glucose production in fresh hepatocytes. In both fresh and cryopreserved hepatocytes the glucose production from glycogenolysis and gluconeogenesis, respectively, was increased fourfold in response to stimulation with glucagon. Overall, the hepatocytes cryopreserved in boxes had a tendency to perform better than hepatocytes cryopreserved in a programmable freezer. In conclusion, the cryopreserved hepatocytes were metabolic active; however, to a lower extent than the fresh hepatocytes, although, the cryopreserved hepatocytes responded as well as the fresh hepatocytes to insulin and glucagon.     

Apocrine cysts of the breast: biomarkers, origin, enlargement, and relation with cancer phenotype

Up to one-third of women aged 30-50 years have cysts in their breasts and are presumed to be at increased risk of developing breast cancer. Here we present an extensive proteomic and immunohistochemistry (IHC) study of breast apocrine cystic lesions aimed at generating specific biomarkers and elucidating the relationship, if existent, of apocrine cysts with cancer phenotype. To this end we compared the expression profiles of apocrine macrocysts obtained from mastectomies from high risk cancer patients with those of cancerous and non-malignant mammary tissue biopsies collected from the same patients. We identified two biomarkers, 15-hydroxyprostaglandin dehydrogenase and 3-hydroxymethylglutaryl-CoA reductase, that were expressed specifically by apocrine type I cysts as well as by apocrine metaplastic cells in type II microcysts, terminal ducts, and intraductal papillary lesions. No expression of these markers was observed in non-malignant terminal ductal lobular units, type II flat cysts, stroma cells, or fat tissue as judged by IHC analysis of matched non-malignant tissue samples collected from 93 high risk patients enrolled in our cancer program. IHC analysis of the corresponding 93 primary tumors indicated that most apocrine changes have little intrinsic malignant potential, although some may progress to invasive apocrine cancer. None of the apocrine lesions examined, however, seemed to be a precursor of invasive ductal carcinomas, which accounted for 81% of the tumors analyzed. Our studies also provided some insight into the origin, development, and enlargement of apocrine cysts in mammary tissue. The successful identification of differentially expressed proteins that characterize specific steps in the progression from early benign lesions to apocrine cancer opens a window of opportunity for designing and testing new approaches for pharmacological intervention, not only in a therapeutic setting but also for chemoprevention, to inhibit cyst development as both 15-hydroxyprostaglandin dehydrogenase and 3-hydroxymethylglutaryl-CoA reductase are currently being targeted for chemoprevention strategies in various malignancies.     

Identification of amyloidogenic proteins in the microbiomes of a rat Parkinson's disease model and wild‐type rats

Cross seeding between amyloidogenic proteins in the gut is receiving increasing attention as a possible mechanism for initiation or acceleration of amyloid formation by aggregation‐prone proteins such as αSN, which is central in the development of Parkinson''s disease (PD). This is particularly pertinent in view of the growing number of functional (i.e., benign and useful) amyloid proteins discovered in bacteria. Here we identify two amyloidogenic proteins, Pr12 and Pr17, in fecal matter from PD transgenic rats and their wild type counterparts, based on their stability against dissolution by formic acid (FA). Both proteins show robust aggregation into ThT‐positive aggregates that contain higher‐order β‐sheets and have a fibrillar morphology, indicative of amyloid proteins. In addition, Pr17 aggregates formed in vitro showed significant resistance against FA, suggesting an ability to form highly stable amyloid. Treatment with proteinase K revealed a protected core of approx. 9 kDa. Neither Pr12 nor Pr17, however, affected αSN aggregation in vitro. Thus, amyloidogenicity does not per se lead to an ability to cross‐seed fibrillation of αSN. Our results support the use of proteomics and FA to identify amyloidogenic protein in complex mixtures and suggests that there may be numerous functional amyloid proteins in microbiomes.