Microphotometric determination of glycogen in single fibres of human quadriceps muscle

Synopsis A technique for the quantitation of glycogen in single fibres of human skeletal muscle is described. By using microphotometry the loss of glycogen from cryostat sections during a PAS-staining procedure was shown to be negligible. Further, it was found that nearly all the PAS-positive material (98.5%) inside a muscle fibre is glycogen. A significantly higher mean glycogen concentration (P<0.001) was found in type II fibres than in type I fibres in the resting quadriceps muscle of sedentary young males. The coefficient of variation for the glycogen concentration within each fibre type was found to be 17% and 15% for type I and type II respectively. The specificity of the PAS-staining technique for glycogen was confirmed by a statistically significant correlation (r=0.78,P<0.001) between the glycogen concentration measured biochemically and that calculated from microphotometry and area and thickness measurements. With the technique described, it seems possible to measure the glycogen concentration of single muscle fibres in serial sections and to calculate this in standard biochemical terms.     

Cellular patterns of post-mortem glycogenolysis in longissimus dorsi muscles of pigs at different live weights

Synopsis Serial frozen sections of longissimus dorsi muscles from twelve Canadian Yorkshire breed pigs at different live weights (13–86kg) were stained for glycogen by the periodic acid-Schiff (PAS) reaction and reacted for NAD tetrazolium reductase to determine the mitochondrial content of muscle fibres. Sections from muscles taken immediatelypost mortem and at 5 hrpost mortem were compared and the patterns of glycogenolysis in high, intermediate and low mitochondrial content fibres were assessed on the basis of the percentage of initially PAS-positive fibres which became PAS-negative 5 hrpost mortem. This form of assessment was necessary because not all fibres were PAS-positive immediatelypost mortem. In smaller pigs, only a few muscle fibres depleted their stainable glycogen by 5 hr and most of these fibres had a high mitochondrial content. In larger pigs, most or all initially PAS-positive fibres became PAS-negative by 5 hrpost mortem. Fibres with a low mitochondrial content accounted for most of the glycogenolysis detected histochemically in larger animals. The overall percentage of PAS-positive fibres was related to glycogen concentration (mg/g),r=0.52,P<0.025, when samples with all PAS-positive fibres were excluded.     

Quantitative histochemical assessment of the heterogeneity of glycogen phosphorylase activity in liver parenchyma of fasted rats using the semipermeable membrane technique and the PAS reaction

Summary Glycogen phosphorylase (EC 2.4.1.1) has been demonstrated in sections of liver from rats starved for 24 h. The method is based on the measurement of the amount of glycogen formed after incubation in a gelled medium containing glucose 1-phosphate as substrate, using the semipermeable membrane technique. Glycogen was demonstrated with the periodic acid-Schiff (PAS) reaction.Phosphorylase activity appeared to be highest in periportal areas. The optimum substrate concentration for revealing activity of the enzyme was 60–120mm. After incubation in the absence of substrate, the staining intensity, as measured cytophotometrically as the mean integrated absorbance at 560 nm, was similar to that of an unincubated section.p-Chloromercuribenzoate, a non-specific inhibitor of glycogen phosphorylase activity, reduced the formation of final reaction product attributable to phosphorylase activity completely. The Michaelis constants (K _m ) of the enzyme in periportal and pericentral areas differed. This was probably due to the presence of thea form only in periportal areas and of thea andb forms in pericentral areas. The mean integrated absorbances in both the periportal and pericentral areas increased linearly with incubation time (4–16 min). A linear relationship was also found with section thickness (4–10 µm). The total activity of glycogen phosphorylase in the periportal areas was double the pericentral activity.It is concluded that the semipermeable membrane technique, combined with the PAS reaction for glycogen, can be used as a valid method for the demonstration and quantification of glycogen phosphorylase activity in livers from starved rats.     

Diurnal variation in glycogen phosphorylase activity in rat liver. A quantitative histochemical study

The diurnal variations of the glycogen content and of glycogen phosphorylase activity in periportal and pericentral areas of rat liver parenchyma have been analyzed in periodic acid Schiff (PAS)-stained cryostat sections using quantitative microdensitometry. Glycogen content and phosphorylase activity were always higher in periportal areas than in pericentral areas throughout the daily cycle. The glycogen content was highest at the end of the active period during darkness and lowest at the end of the resting period. Phosphorylase activity appeared to be inversely correlated with the glycogen content in both areas. It is concluded that the glycogen content is regulated by phosphorylase activity, which may be due to local cAMP concentration.     

High‐normal tsh values in obesity: Is it insulin resistance or adipose tissue's guilt?

Objective:

Clinical evidences reported subclinical alterations of thyroid function in obesity, although the relationship between thyroid status and obesity remains unclear. We cross‐sectionally investigated the influence of metabolic features on hypothalamic–pituitary–thyroid axis in obesity.

Design and Methods:

We enrolled 60 euthyroid subjects with no history of type 2 diabetes mellitus and assessed the relationship of thyroid function with insulin resistance, measured using euglycemic clamp, and abdominal fat volume, quantified by computed tomography scan (CT scan). Thyroid stimulating hormone (TSH) correlated with BMI (r = 0.46; P = 0.02), both visceral (r = 0.58; P = 0.02) and subcutaneous adipose tissue volumes (r = 0.43; P = 0.03) and insulin resistance (inverse relationship with insulin sensitivity–glucose uptake: r = ?0.40; P = 0.04).

Results:

After performing multivariate regression, visceral adipose tissue volume was found to be the most powerful predictor of TSH (β = 3.05; P = 0.01), whereas glucose uptake, high‐density lipoprotein (HDL) cholesterol, low‐density lipoprotein (LDL) cholesterol, subcutaneous adipose tissue volume, and triglycerides were not. To further confirm the hypothesis that high‐normal TSH values could be dependent on adipose tissue, and not on insulin resistance, we restricted our analyses to moderately obese subjects' BMI ranging 30‐35 kg/m². This subgroup was then divided as insulin resistant and insulin sensitive according to the glucose uptake (≤ or >5 mg·kg^?1·min^?1, respectively). We did not find any statistical difference in TSH (insulin resistant: 1.62 ± 0.65 µU/ml vs. insulin sensitive: 1.46 ± 0.48; P = not significant) and BMI (insulin resistant: 32.2 ± 1.6 kg/m² vs. insulin sensitive: 32.4 ± 1.4; P = not significant), thus confirming absence of correlation between thyroid function and insulin sensitivity per se.

Conclusion:

Our study suggests that the increase in visceral adipose tissue is the best predictor of TSH concentration in obesity, independently from the eventual concurrent presence of insulin resistance.

     

Morphological and immunological confirmation of the presence of chlamydiae in the gut tissues of the chesapeake bay clam,Mercenaria mercenaria

The original electron microscopic identification by other investigators in 1977 of chlamydiae in the gut tissues of the Chesapeake Bay hard clam (Mercenaria mercenaria) is corroborated and further supported by evidence ofChlamydia-specific immunofluorescence (IF). Our electron microscopy demonstrated that gut tissue cells were heavily infected with chlamydiae in all stages of development but the intrachlamydial phage-like particles reported in 1977 were not seen. Tissue sections stained with IF reagents were strongly positive, and IF was blocked in varying degrees with chlamydial antisera produced in a goat and a turkey. The IF-positive tissue sections contained intracytoplasmic inclusions that stained darkly with Lugol's iodine (indicating the presence of glycogen) while IF-negative tissues had little if any iodinestaining material. Furthermore, electron micrographs of chlamydiae-containing phagosomes showed numerous rosettes of electron-dense particles typical of glycogen. The presence of iodine-positive phagosomes with electron dense rosettes suggests that the organisms are glycogen-producing chlamydiae biochemically related toChlamydia trachomatis. Repeated attempts to cultivate chlamydiae from the clam tissues in cell cultures and laboratory animals failed.     

Staining of demineralized cartilage

Summary Safranin O in the orthochromatic form stains articular cartilage proteoglycan quantitatively in histological sections of demineralized cartilage. This was shown by scanning microdensitometry of stained sections of undemineralized and demineralized articular cartilage and by biochemical analysis of ³⁵S labelled cartilage subjected to demineralization. In constrast, Alcian Blue staining is affected by unknown factors other than simply the amount of proteoglycan present. Alcoholic formalin fixes articular cartilage proteoglycan more successfully than formol Zenker for subsequent rapid demineralization. Alcoholic formalin does not preserve cellular appearance as well as formol Zenker. Staining of articular cartilage with PAS appears unaffected by demineralization.     

Associations of testosterone and sex hormone binding globulin with adipose tissue hormones in midlife women

Objective:

Regulators of adipose tissue hormones remain incompletely understood, but may include sex hormones. As adipose tissue hormones have been shown to contribute to numerous metabolic and cardiovascular disorders, understanding their regulation in midlife women is of clinical importance. Therefore, we assessed the associations between testosterone (T) and sex hormone binding globulin (SHBG) with leptin, high molecular weight (HMW) adiponectin, and the soluble form of the leptin receptor (sOB‐R) in healthy midlife women.

Design and Methods:

Cross‐sectional analyses were performed using data from 1,881 midlife women (average age 52.6 (±2.7) years) attending the sixth Annual follow‐up visit of the multiethnic Study of Women's Health Across the Nation.

Results:

T was weakly negatively associated with both HMW adiponectin and sOB‐R (r = ?0.12 and r = ?0.10, respectively; P < 0.001 for both), and positively associated with leptin (r = 0.17; P < 0.001). SHBG was more strongly and positively associated with both HMW adiponectin and sOB‐R (r = 0.29 and r = 0.24, respectively; P < 0.001 for both), and more strongly and negatively associated with leptin (r = ?0.27; P < 0.001). Adjustment for fat mass, insulin resistance, or waist circumference only partially diminished associations with HMW adiponectin and sOB‐R, but attenuated associations with leptin. In conclusion, in these midlife women, lower SHBG values, and to a lesser extent, higher T levels, were associated with lower, or less favorable, levels of adiponectin and sOB‐R, independent of fat mass.

Conclusions:

These data suggest that variation in these adipose hormones resulting from lower SHBG levels, and possibly, though less likely, greater androgenicity, may contribute to susceptibility for metabolic and cardiovascular outcomes during midlife in women.

     

Visualisation of capillaries in human skeletal muscle

 A double staining method combining Ulex europaeus agglutinin I lectin (UEA-I) and collagen type IV staining was used to determine the capillary density and the number of capillaries relative to different fibre types in human skeletal muscles. The result of this combined staining was compared with that of other staining methods including amylase-periodic acid Schiff (PAS), UEA-I, anti-collagen type IV and anti-von Willebrand factor. Muscle biopsy specimens, 12 from M. vastus lateralis and 6 from M. soleus, were obtained from 18 healthy young men. Compared with amylase-PAS staining, double staining showed a larger number of capillaries surrounding type I (+9.6%), type IIA (+8.6%) and type IIB (+11.6%) fibres in the M. vastus lateralis specimens (P<0.001 for all differences). The capillary to fibre ratio (cap·fibre^–1) and the capillary density (cap·mm^–2) were 8.3% (P<0.002) and 7.9% (P<0.001) larger, respectively. In the M. soleus specimens, cap·fibre^–1 and cap·mm^–2 were 7.4 and 9.9% larger, respectively, by double staining compared with PAS staining. Further comparisons showed that the cap·fibre^–1 and cap·mm^–2 obtained with double staining were similar to the values determined by the UEA-I staining, but greater than that measured by the collagen type IV method. The double staining gave a more marked stain of capillaries and revealed muscle fibre borders clearly, which is an advantage in studies that require comparisons between serial sections using computerised image analyses. It is concluded that the double staining method is superior to either the UEA-I, collagen type IV or the traditional amylase-PAS staining methods in analysing capillary density of normal human skeletal muscle. Accepted: 17 October 1996     

The utility of antisera to canine growth hormone and canine prolactin for immunocytochemical staining of the dog pituitary gland

Summary Fluorescent microspectrophotometry using dichroic mirror vertical epi-illumination of tissue sections stained with the PAS reaction (periodic acid and pararosaniline Schiff reagent) provides a measure of the relative concentration of 1:2 glycols within and between tissue sections. In PAS reacted sections of agarose gel, pararosaniline Schiff fluorescence increases linearly as the concentration of agarose increases (r=0.97, p<0.05). The concentration of glycogen within liver as measured by a phenol-based tissue assay is linearly correlated with pararosaniline Schiff fluorescence of formalin fixed liver sections (r=0.87, p<0.05). These relationships are unaffected by alcina blue or hematoxylin. Heretofore the amount of color reaction as measured by densitometry at the pararosaniline absorption peak was claimed to be an unreliable indicator of the amount of reactive glycol present in tissue. Our observations indicate that when the concentration of Schiff reagent exceeds an empiric limit relative to available polysaccharides, the Schiff reagent-tissue complex reflects light at the excitation wavelength instead of fluorescing the emission spectra. This can be circumvented by using dilute pararosaniline-Schiff reagent, shortening the staining period, and lowering the temperature of the staining medium.While routine PAS staining reactions are followed by washing in running water to develop the red color seen with broad spectrum illumination, water development is unnecessary for the dye-tissue complex to fluoresce. The fluorescent emission peak and the maximum excitation peak of both developed and undeveloped pararosaniline-Schiff-reagent-tissue complexes are 645–50 nm and 540–45 nm, respectively. These spectral characteristics are not changed by binding to oxidation products of different glycoproteins or polysaccharides. Intense exposure to room light, but not 100 repetitive short (0.13 s) exposures, causes partial photodecomposition.Quantitative assessment of cytofluorescence requires definition of the optical system used to measure emission. In the microspectrophotometer employed in this study, dichroic mirrors reflect light with variable efficiency depending on wavelength from the light source to the stage, and variably block light reflected or emitted from the specimen, serving as crude barrier filters. These dichroic mirror characteristics are influenced by the exact nature of the optical coating on the surface of each individual mirror. Since the optical coating of similar mirrors may vary, the properties of individual mirrors must be considered in the interpretation of spectral data and in determining the proper optical conditions for quantification of cytofluorescence.This investigation was supported by National Institutes of Health Research Service Award IF32 NS 517701 PTHA from the National Institute of Neurological and Communicative Disorders and Stroke and the National Cancer Institute Grant R01 CA 17341     

In vivo nuclear magnetic resonance studies on the lugworm Arenicola marina. I. Free inorganic phosphate and free adenylmonophosphate concentrations in the body wall and their dependence on hypoxia

The cytoplasmic concentrations of free inorganic phosphate and free AMP in the body wall of the lugworm Arenicola marina were estimated in order to verify their proposed regulatory role in glycogenolysis during anaerobiosis (Kamp 1993). Using in vivo ³¹P nuclear magnetic resonance spectroscopy the concentration of free inorganic phosphate was determined to be 4.7±0.7 mmol·1^-1 (±standard deviation, n=3) varying with season (Juretschke and Kamp 1995). These values were two to three times lower than those measured in perchloric acid extracts. In contrast, values for the phosphagen phosphotaurocyamine assessed biochemically in the extracts and by in vivo nuclear magnetic resonance were very similar. During the transition from normoxia to hypoxia the concentration of free inorganic phosphate increased to the same extent and at the same rate as the concentration of phosphotaurocyamine decreased. A discrepancy was also found for the biochemically determined AMP and ADP concentrations in the extract and those derived from the equilibrium constants of the taurocyamine kinase (ADP_free) and adenylate kinase (AMP_free) reactions. Calculated concentrations of ADP_free and AMP_free in normoxic specimens were about two or even four orders of magnitude lower than the values determined in extracts. During hypoxia the concentrations of AMP and ADP increase moderately when measured biochemically in extracts, while the values for ADP_free and AMP_free rise three- and nine-fold during the first 3 h of hypoxia. Thereafter, the levels stay constant due to a progressive acidosis. If during hypoxia pH_i is stabilized by addition of buffering substances to the incubation medium, both ADP_free and AMP_free rise continuously. The significant changes found for the concentrations of free inorganic phosphate and AMP_free support their assumed regulatory role in glycogenolysis during anaerobiosis, though these AMP_free values seem too low to actually activate glycogen phosphorylase. The strong effect of pH_i on the levels of ADP_free and AMP_free suggest a mechanism by which acidosis prevents a continuing increase of glycogenolysis (ATP-producing pathway) during prolonged anaerobiosis (protective effect of acidosis).Abbreviations ADP _free cytoplasmic adenosine diphosphate - AK adenylate kinase - AMP _free cytoplasmic adenosine monophosphate - CK creatine kinase - GPase glycogen phosphorylase - MW molecular weight - Int P _i integral of P_i-signal - NMR nuclear magnetic resonance - P _i-free cytoplasmic inorganic phosphate - PCA perchlori acid - PFK 6-phosphofructokinase - PME phosphomonoester - PPA phenylphosphonic acid - (P)Tc (phospho)taurocyamine - S _f saturation factor - Sw sea water - TcK taurocyamine kinase - TRA triethanolamine - TRIS tris(hydroxymethyl)aminomethane     

A Comparative Study by δ13C-Analysis of Crassulacean Acid Metabolism (CAM) in Kalanchoë (Crassulaceae) Species of Africa and Madagascar

The carbon isotope ratios (δ¹³C values) of samples of Kalanchoë species collected in Africa were compared with previous data obtained with species from Madagascar. In contrast to the Malagasy species which cover the whole range of δ¹³C values from ?10 to ? 30%_o, indicating high inter- and intraspecific diversity of CAM performance, in the African species nearly all δ¹³C values were less negative than ?18%₀. Thus, in the African species the CAM behaviour is characterized by CO₂ uptake proceeding mainly during the night. The distribution of δ¹³C values among the species clearly mirrors the taxonomic groups and the three sections of the genus Kalanchoë sensu lato. The Kitchingia section comprises only groups having CAM with a high proportion of carbon acquisition by the C₃-pathway of photosynthesis. The same holds true for the first three groups of the Bryophyllum section, whereas in the following groups of the section CAM with CO₂ proceeding mainly during the night is common. The latter CAM mode is typical also for the majority of groups and species in the section Eukalanchoë. The African Kalanchoë species belong to the Eukalanchoë section, whereas in Madagascar all three sections are abundant. The data support the view that the centre of adaptive radiation of the genus is located in Madagascar. They also suggest that high CAM variability is abundant in the more primitive taxa of the genus, whereas the phylogenetically more derived taxa show a stereotype CAM with CO₂ uptake taking place only during the night.     

Phylogenetic clustering of wingbeat frequency and flight‐associated morphometrics across insect orders

Wingbeat frequency in insects is an important variable in aerodynamic and energetic analyses of insect flight and often is studied on a family‐ or species‐level basis. Meta‐analyses of these studies report order‐level patterns suggesting that flight strategy is moderately well conserved phylogenetically. Studies incorporated into these meta‐analyses, however, use variable methodologies across different temperatures, which may confound results and phylogenetic patterns. In the present study, a high‐speed camera is used to measure wingbeat frequency in a wide variety of species (n = 102) under controlled conditions aiming (i) to determine the validity of previous meta‐analyses showing phylogenetic clustering of flight strategy and (ii) to identify new evolutionary patterns between wingbeat frequency, body mass, wing area, wing length and wing loading at the order level. All flight‐associated morphometrics significantly affect wingbeat frequency. Linear models show that wing area explains the most amount of variation in wingbeat frequency (r² = 0.59, P ≤ 0.001), whereas body mass explains the least (r² = 0.09, P ≤ 0.01). A multiple regression model incorporating both body mass and wing area is the best overall predictor of wingbeat frequency (r² = 0.84, P ≤ 0.001). Order‐level phylogenetic patterns across relationships are consistent with previous studies. Thus, the present study provides experimental validation of previous meta‐analyses and provides new insights into phylogenetically conserved flight strategies across insect orders.     

Length–weight relationships of nine fish species from the Tongjiang section of the Songhua River,China

Length–weight relationships were evaluated for nine fish species from the Tongjiang section of the Songhua River in China. A total of 675 fish specimens were collected from 4 May to 29 October 2014. Length–weight relationships for six fish species (Romanogobio tenuicorpus, Leuciscus waleckii, Opsariichthys bidens, Microphysogobio amurensis, Pelteobagrus ussuriensis and Misgurnus mohoity) were new to FishBase in 2015, but the length–weight relationships of P. ussuriensis was studied by Ma in 2015. New data on M. mohoity is offered, and this study also shows new maximum total lengths for three fish species. The r² values ranged from .95 to .99. Values of b varied from 2.504 to 3.471.     

A flow cytometric study of c-erbB-3 expression in breast cancer

In order to assess the specificity of biotinylated anti-c-erbB-3 antibody, screening was performed on a series of tumour cell lines and lymphocytes. Staining was found to be consistent, with good reproducibility. Twenty-nine consecutive breast cancer samples were obtained from women treated with tamoxifen and undergoing elective mastectomy. Twenty-eight invasive ductal carcinomas and 1 DCIS were stained for c-erbB-3 expression: 2 were grade I (Bloom and Richardson), 15 grade II, and 11 grade III tumours, 1 being unclassified; 16 were axillary node positive and 10 node negative; in 2 cases no nodes were sampled. Tumours examined by flow cytometry were stained with cytokeratin FITC antibody and the cytokeratin-positive population gated. Using Mann-Whitney analysis no association was seen between c-erbB-3 expression and Bloom and Richardson grade or axillary node status. In the tumour samples c-erbB-3 expression was found to show an association with EGF-R (P=0.021r ²=0.16), PgR (P=0.02,r ²=0.16), c-myc (P<0.0001,r ²=0.5), c-jun (P=0.001,r ²=0.4) and c-fos (P=0.001,r ²=0.5) but not with c-erbB-2 (P=0.2,r ²=0.06), ER (P=0.4,r ²=0.02) or p53 1801 (P=0.05,r ²=0.2). Expression of c-erbB-3 may not be an independent marker of prognosis, but it is associated with other markers of poor prognosis and early cellular events linked with aberrant growth and differentiation.This study was supported by The North of England Cancer Research Campaign     

Chemical and histochemical studies of normal and diseased gastrointestinal tract. IV. A comparison of histochemical and chemical methods for the estimation of side chain O-acylated sialic acids

Summary Statistically significant correlations were obtained between a chemical assay for the proportion of colonic epithelial glycoprotein sialic acids with side chainO-acyl substituents and two histochemical methods, the PBT-KOH-PAS sequence (r _s=0.7485 forN=31,P=0.01, one-sided test) and the PAPT-KOH-Bh-PAS procedure (r _s=0.7024 forN=34). A positive correlation (r _s=0.8654 forN=30,P=0.01) was also obtained between the results of the two histochemical procedures. It is concluded that, on average, histochemical observations are a reliable semiquantitative comparative method for the estimation of side chainO-acetylated sialic acids.     

Inter- and intra-habitat relationships between woodland cryptostigmata species diversity and the diversity of soil and litter microhabitats

Summary Soil animal communities contain a large number of species exhibiting a low degree of trophic specialization. Competition between animal species with similar food requirements is frequently reduced by partitioning habitat space and this ecological principle is demonstrated for woodland mite communities. Microhabitat diversity was determined for the litter (L), fermentation (F) and humus (H) sub-horizons using gelatine embedded soil sections and compared with mite species diversity for the same layers of the soil and litter profile. Cryptostigmata species diversity was correlated with microhabitat diversity (r=0.67, P<0.01) in six woodland soils with a range of humus forms. Intra-habitat relationships were determined for one site on two sampling occasions: in November an exceptionally high correlation was obtained (r=0.91, P<0.001) but samples collected in February showed a lower correlation (r=0.63, P<0.01). Within sub-horizon relationships showed significant correlations for the L (r=0.59, P<0.01) and H sub-horizons (r=0.72, P=0.001). The F sub-horizon data were more variable than the other two sub-horizons but a correlation of 0.60 (P=0.05) was obtained for the intrahabitat study.     

Argyrophilic nucleolar organizer regions and bromodeoxyuridine and 3[H]-thymidine labelling indices in colorectal cancer

The count of argyrophilic nucleolar organizer regions (AgNORs) has been proposed as a useful method for evaluating cell replication in human tumours. The current study was undertaken to compare AgNOR values in colorectal cancers with two better established methods for investigating cell proliferation such as bromodeoxyuridine (BrdUrd) and ³[H]-thymidine (³[H]dT) labelling indices (LIs). Because some concern still exists regarding accuracy and reproducibility of AgNOR quantifying methods, we carried out a control study by independently repeating the same measurements (number, area and area per silver-stained NOR particle) in two centres with different operators and computer-assisted image analysers on 40 colorectal carcinomas. AgNOR values recorded in the two centres were strictly correlated (r= 0.75; P < 0.001 for number; r= 0.62, P < 0.01 for area; r= 0.63, P < 0.001 for area per silver-stained NOR particle) and the range of values were almost identical. Then, AgNOR values were compared with BrdUrd and ³[H]dT LIs, respectively obtained by in vivo incorporation and in vitro incubation in the same series of colorectal carcinomas. No correlation was found between AgNOR values and BrdUrd or ³[H]dT LIs. BrdUrd and ³[H]dT LIs were instead reciprocally significantly correlated. No evident correlation was seen between LIs or AgNOR values and clinico-pathological parameters of the tumour. In conclusion, in colorectal neoplasms, AgNOR values did not appear to relate with more direct parameters of cell proliferation. It follows that AgNOR reliability as a biomarker of cell proliferation remains questionable.     

Production of 1,2‐propanediol in photoautotrophic Synechocystis is linked to glycogen turn‐over

We utilized a photoautotrophic organism to synthesize 1,2‐propanediol from carbon dioxide and water fueled by light. A synthetic pathway comprising mgsA (methylglyoxal synthase), yqhD (aldehyde reductase), and adh (alcohol dehydrogenase) was inserted into Synechocystis sp. PCC6803 to convert dihydroxyacetone phosphate to methylglyoxal, which is subsequently reduced to acetol and then to 1,2‐propanediol. 1,2‐propanediol could be successfully produced by Synechocystis, at an approximate rate of 55 μmol h^?1 g_CDW^?1. Surprisingly, maximal productivity was observed in the stationary phase. The production of 1,2‐propanediol was clearly coupled to the turn‐over of intracellular glycogen. Upon depletion of the glycogen pool, product formation stopped. Reducing the carbon flux to glycogen significantly decreased final product titers. Optimization of cultivation conditions allowed final product titers of almost 1 g L^?1 (12 mM), which belongs to the highest values published so far for photoautotrophic production of this compound.

     

Plasma stearoyl‐CoA desaturase indices: Association with lifestyle,diet, and body composition

Objective:

Stearoyl‐coenzyme A desaturase‐1 (SCD1) is a key enzyme in fatty acid and energy metabolism. Increased hepatic SCD1 activity is associated with obesity and obesity‐related diseases. We examined the relations of two plasma SCD activity indices (16:1n‐7/16:0, 18:1n‐9/18:0) with body composition, and the association of lifestyle and dietary variables with the plasma SCD indices.

Design and Methods:

This population‐based, cross‐sectional study of 2021 elderly (71–74 y) men and women from the Hordaland Health Study in Western Norway was conducted using a validated food frequency questionnaire, body composition measurements by dual‐energy X‐ray absorptiometry and determination of the plasma fatty acid profile.

Results:

In multivariate regression analyses, plasma SCD indices were positively associated with BMI and body fat (P < 0.001 for both). From the 2.5th to 97.5th percentiles of plasma SCD‐16 and SCD‐18 indices, fat mass differed by about 8 kg and 5 kg, respectively. Intake of polyunsaturated fatty acids were negatively associated with SCD‐16 (partial r = ?0.30) and SCD‐18 (partial r = ?0.24) (P < 0.001 for both). Alcohol intake was positively associated with SCD‐16 (partial r = 0.26) and SCD‐18 (partial r = 0.16) (P < 0.001 for both), whereas coffee consumption and physical activity were inversely associated with SCD‐16 (P = 0.026 and P = 0.006, respectively) and SCD‐18 (P = 0.001 and P = 0.022, respectively).

Conclusions:

In this elderly population, plasma markers of SCD1 activity are associated with increased adiposity. Furthermore, modifiable dietary habits and lifestyle are associated with plasma SCD indices. These results suggest that SCD1 activity may be a promising target for weight control.