Effects of vitamin D supplementation and exercise training on physical performance in Chilean vitamin D deficient elderly subjects

The aim was to assess the effects of resistance training and vitamin D supplementation on physical performance of healthy elderly subjects. Ninety-six subjects, aged 70 years or more with 25 OH vitamin D levels of 16 ng/ml or less, were randomized to a resistance training or control group. Trained and control groups were further randomized to receive in a double blind fashion, vitamin D 400 IU plus 800 mg of calcium per day or calcium alone. Subjects were followed for nine months. Serum 25 OH vitamin D increased from 12.4+/-2.2 to 25.8+/-6.5 ng/ml among subjects supplemented with vitamin D. Trained subjects had significant improvements in quadriceps muscle strength, the short physical performance test and timed up and go. The latter improved more in trained subjects supplemented with vitamin D. At the end of the follow up, gait speed was higher among subjects supplemented with vitamin (whether trained or not) than in non-supplemented subjects (838+/-147 and 768+/-127 m/12 min, respectively, p=0.02). Romberg ratio was lower among supplemented controls than non-supplemented trained subjects (128+/-40% and 144+/-37%, respectively, p=0.05). In conclusion, vitamin D supplementation improved gait speed and body sway, and training improved muscle strength.

A high body mass index protects against femoral neck osteoporosis in healthy elderly subjects

OBJECTIVE

In a large sample of elderly subjects, we assessed the possible protective effect of obesity on the development of osteoporosis.

METHODS

Healthy subjects 70 y or older and of low socioeconomic level were studied. Bone mineral density was measured in the femoral neck by using a Lunar Prodigy double beam densitometer and compared measurements with appropriate standards. Osteoporosis was defined according to criteria of the World Health Organization (WHO). Body weight and height were recorded simultaneously, and body mass index (BMI) was calculated as weight (kg) divided by height (m2). Age-adjusted odds ratios for femoral osteoporosis were calculated for WHO-proposed BMI ranges in women and men, with an odds of one for a BMI below 25 kg/m2.

RESULTS

Eight hundred forty-five subjects (615 women and 230 men; mean age, 75 +/- 4.4 y) were studied. Mean BMI was 28.1 +/- 4.7 kg/m2. Twenty five percent of women and 11% of men had osteoporosis (P < 0.001). Forward stepwise multiple regression analysis showed BMI to be the best independent predictor of bone mineral density in women and men. The age-adjusted odds ratios for femoral osteoporosis were 0.34 (95% confidence interval [CI], 0.21 to 0.55) and 0.13 (95% CI, 0.04 to 0.43) for women and men with a BMI between 25 and 30 kg/m2, respectively. The odds ratios for women and men with a BMI between 30 and 35 kg/m2 were 0.21 (95% CI, 0.11 to 0.39) and 0.09 (95% CI, 0.01 to 0.67), respectively

CONCLUSIONS

This study confirms the protective effect of a high BMI on femoral neck bone mineral density among elderly subjects. The risk for osteoporosis among men and women with a BMI above 30 kg/m2 was approximately 33% compared with subjects with a normal BMI.

Purification and characterization of patagonfibrase, a metalloproteinase showing α-fibrinogenolytic and hemorrhagic activities, from Philodryas patagoniensis snake venom

Venoms of Colubridae snakes are a rich source of novel compounds, which may have applications in medicine and biochemistry. In the present study, we describe the purification and characterization of a metalloproteinase (patagonfibrase), the first protein to be isolated from Philodryas patagoniensis (Colubridae) snake venom. Patagonfibrase is a single-chain protein, showing a molecular mass of 53,224 Da and an acidic isoelectric point (5.8). It hydrolyzed selectively the Aalpha-chain of fibrinogen and when incubated with fibrinogen or plasma, the thrombin clotting time was prolonged. Prominent hemorrhage developed in mouse skin after intradermal injection of patagonfibrase. When administered into mouse gastrocnemius muscle, it induced local hemorrhage and necrosis, and systemic bleeding in lungs. Patagonfibrase showed proteolytic activity toward azocasein, which was enhanced by Ca(2+) and inhibited by Zn(2+), cysteine, dithiothreitol and Na(2)EDTA. Patagonfibrase impaired platelet aggregation induced by collagen and ADP. Thus, patagonfibrase may play a key role in the pathogenesis of disturbances that occur in P. patagoniensis envenomation, and may be used as a biological tool to explore many facets of hemostasis.

Premature loss of muscle mass and function in type 2 diabetes

INTRODUCTION

Muscle mass and function are among the most relevant factors that contribute to an optimal quality of life, and are strong predictors of mortality in the elderly. Loss of lean tissues and deterioration of muscle function have been described as one of the many complications of type 2 diabetes mellitus (DM2), but most studies do not isolate age as an intervening factor.

AIM

To study whether adult DM2 patients up to 60years of age have decreased muscle mass and function compared with healthy non-diabetic (ND) subjects of similar age.

METHODOLOGY

Appendicular fat-free mass (ApFFM) by dual X-ray absorptiometry (DEXA), handgrip strength (HS), quadriceps strength (QS), 12 min walking capacity (12MW) and the Timed Up and Go test (TUG) were measured in 100 DM2 patients and 39 ND controls. Muscle quality, or the ratio between lean mass and muscle strength of upper and lower limbs, and the functional limitations associated with pain and stiffness assessed according to the Western Ontario and McMaster Universities Arthrosis Index (WOMAC) were also recorded. Specific tests were performed to rule out microvascular diabetic complications (retinal and peripheral nerves), metabolic control, kidney function and vitamin D status and examine their association with ApFFM and function.

RESULTS

ApFFM was significantly higher among DM2 female patients and lower among diabetic men. However opposite results were obtained when individual values were corrected for body mass index (BMI), specifically among women, who were more likely to be obese. As for muscle strength and global functionality tests, significantly better performances in TUG, 12MW, QS and HS were observed among ND subjects of both sexes. These differences prevailed even after excluding diabetic patients with microvascular complications as well as those with more than 10years of diabetes. Muscle quality was also significantly better among ND women. Higher scores of pain and stiffness in the WOMAC scale correlated with 12MW and TUG in both groups but did not correlate with ApFFM.

CONCLUSIONS

We found a clear deterioration of lean mass and muscle functions among adult DM2 patients of up to 60years old, independent of length of disease, metabolic control, vitamin D status and presence of microvascular complications and pain.

Proteolytic, edematogenic and myotoxic activities of a hemorrhagic metalloproteinase isolated from Bothrops alternatus venom

A hemorrhagic metalloproteinase has been isolated from Bothrops alternatus venom from specimens that inhabit the north-east region of Argentina. The present study aimed at evaluating the proteolytic, hemorrhagic, edematogenic and myotoxic activities of the purified metalloproteinase, in order to consider its participation on the phatophysiology of the intoxication by Bothrops alternatus venom. The hemorrhagic metalloproteinase was isolated by a combination of DEAE-Cellulose chromatography and gel filtration on Sephadex G-75. The enzyme showed a molecular mass around 55k Da, it exhibited a hemorrhagic activity with a minimal hemorrhagic dose of 1.9 microg, almost two fold minor than the whole venom (3.6 microg). The enzyme showed a weak proteolytic activity on casein (18.72 U/mg enzyme), similar to the one exhibited by the whole venom (20 U/mg venom). Besides, the ability to degrade casein could be detected by SDS-PAGE; beta-casein was the fraction that showed the higher degradation, followed by alphas(1)-casein and kappa-casein degradation. The hemorrhagic metalloproteinase rapidly hydrolysed the A alpha-chain of fibrinogen, followed by B beta-chain degradation and leaving the gamma-chain unaffected. Proteolytic activities were inhibited by EDTA whereas they were not inhibited by benzamidine and PMSF. The metalloproteinase showed several polypeptides chains after autocatalytic processing, including a chain of 28k Da, it could be the processed disintegrin-like and cysteine-rich domains. The isolated enzyme exhibited myotoxic activity with high CK levels at 6h, due to local ischemia resulting of its hemorrhagic activity, and a significant edema-inducing effect (MED=1.3 microg), corroborated both results by the histological observations of samples of gastrocnemius muscle. These findings showed that this hemorrhagic metalloproteinase, possesses high edematogenic and myotoxic activities and, in despite of exhibiting a weak proteolytic activity, it is able to degrade fibrinogen. So, this enzyme would contribute markedly to the phatophysiology of the bothropic envenomation.

Single and multiple selenium-zinc-iodine deficiencies affect rat thyroid metabolism and ultrastructure

This study was conducted to evaluate the effects of single and combined deficiencies of Se, Zn and I on thyroid function in rats. Rats were fed amino acid-based diets for 6 wk starting from weaning. The diets contained either low or adequate amounts of these minerals. In addition to the control and control pair-fed groups, seven experimental groups were formed: Se deficient (Se-); I deficient (I-); Zn deficient (Zn-); Se and I deficient (Se-I-); Zn and I deficient (Zn-I-); Se and Zn deficient (Se-Zn); and Se, I and Zn deficient (Se-I-Zn-). Serum triiodothyronine (T3) was significantly lower than in controls in Zn-, Se-Zn- and Se-I- groups. Serum total thyroxine (T4) and free T4 were significantly lower and thyroid-stimulating hormone (TSH) greater in all iodine-deficient groups, regardless of Se or Zn status. Thyroid glutathione peroxidase activity was significantly reduced in Se- and Se-Zn- groups. Nevertheless, in the groups with a concurrent I deficiency, the activity of this enzyme was significantly greater than in controls. Severe alterations of the follicle cellular architecture, including signs compatible with apoptosis, were observed in the Zn- and Se-Zn- groups. These alterations appeared to be less severe when iodine deficiency was simultaneously present. Single and multiple deficiencies of Se, Zn and I have distinct effects on thyroid metabolism and structure.

Aromatase activity of human mesenchymal stem cells is stimulated by early differentiation, vitamin D and leptin

Human mesenchymal stem cells (hMSCs) are multipotent cells present in bone marrow, which differentiate into osteoblasts and adipocytes, among other lineages. Oestrogens play a critical role in bone metabolism; its action may affect the adipocyte to osteoblast ratio in the bone marrow. In hMSCs, oestrogens are synthesized from C19 steroids by the enzyme aromatase cytochrome P450. In this study, we assessed whether aromatase enzymatic activity varied through early osteogenic (OS) and adipogenic (AD) differentiation. Also, we studied the effect of leptin and 1,25 dihydroxyvitamin D3 (1,25(OH)2D3) on aromatase cell activity. Finally, we analysed whether conditions that modify oestrogen generation by cells affected hMSCs differentiation. For these purposes, hMSCs derived from post-menopausal women (65-86 years old) were cultured under basal, OS or AD conditions, in the presence or the absence of leptin and 1,25(OH)2D3. Aromatase activity was measured by the tritiated water release assay and by direct measurement of steroids synthesized from 3H-labelled androstenedione or testosterone. Our results showed that different OS and AD patterns of aromatase activity developed during the first period of differentiation (up to 7 days). A massive and sharp surge of aromatase activity at 24 h characterized early OS differentiation, while increased but constant aromatase activity was increased through adipogenesis. Both leptin and vitamin D increased aromatase activity during osteogenesis, but not during adipogenesis; finally, we showed that favourable aromatase substrates concentration restrained MSCs adipogenesis but improved osteogenesis. Thus, it could be inferred that a high and early increase of local oestrogen concentration in hMSCs affects their commitment either restraining AD or facilitating OS differentiation, or both.

Phospholipase A(2) enhances the endothelial cell detachment effect of a snake venom metalloproteinase in the absence of catalysis

Microvessel disruption leading to hemorrhage stands among the most dangerous consequences of envenomings by snakes of the family Viperidae. A PIII metalloproteinase (SVMP), balteragin, purified from the venom of the snake Bothrops alternatus, displays a potent hemorrhagic effect, and a moderate myotoxicity in vivo. Previous studies described the ability of this SVMP to induce the detachment of C2C12 myoblasts in culture, without causing cytolysis. Surprisingly, a purified acidic phospholipase A2 (PLA2) from the same venom was found to increase this detaching activity of the SVMP on myoblasts. Since endothelial cells are a natural target of SVMPs in vivo, the possibility that this synergistic effect is also observed on this cell type was explored in the present work. In addition, a first approach of the mechanism of action of this effect was studied. Results clearly confirm that the acidic PLA2, despite lacking toxicity towards endothelial cells, significantly enhances the detaching effect of the SVMP even at a concentration as low as 1 μg/mL. Inhibition of enzymatic activity of the PLA2 by chemical modification with p-bromophenacyl bromide did not affect the synergistic activity, suggesting that this effect is not dependent on phospholipase enzymatic activity and may instead be the consequence of an interaction of the PLA2 with endothelial cell plasma membrane. To our knowledge, this is the first report of a synergistic action of a non toxic PLA2 in enhancing the detachment of endothelial cells induced by a metalloproteinase.

Expression of the cutaneous lymphocyte-associated antigen in circulating T cells in drug-allergic reactions

BACKGROUND

Mechanisms underlying the production of delayed cutaneous reactions to drugs are poorly characterized. The cutaneous lymphocyte-associated antigen (CLA) is a skin-homing T cell receptor that defines T lymphocytes associated with the cutaneous immune response. We studied the percentage and activation phenotype of circulating CLA+ T cells in drug allergic patients and healthy controls.

METHODS

PBMCs were isolated from heparinized venous blood by Ficoll density gradient. Lymphocytes were stained for flow cytometry with anti-CLA, anti-CD3 and anti-HLA-DR mAbs. Five-parameter analysis was performed on an Ortho Cytoron Absolute flow cytometer.

RESULTS

We found increased percentages of circulating CLA+ T cells in drug-allergic patients compared to controls. Moreover, CLA+ T cells from drug-allergic individuals expressed a higher percentage of the T cell activation marker HLA-DR.

CONCLUSIONS

These results suggest that CLA+ T cells may play a role in the pathology of delayed cutaneous reactions to drugs. Further studies are in progress to elucidate the role of skin-homing T cells in allergic reactions to drugs.

Hemorrhagic activity of the Duvernoy's gland secretion of the xenodontine colubrid Philodryas patagoniensis from the north-east region of Argentina

Colubrid snakes belonging to Philodryas genus, widespread all over South America, bring about lesions (swelling, ecchymosis, transient bleeding from the bite site punctures), that are similar to those produced by Bothrops species (yarará). In the present work we began the characterization of Philodryas patagoniensis venom. We examined if this venom produces hemorrhagic lesions as those observed in victims bitten by Philodryas olfersii. Hemorrhagic, proteolytic and fibrinogenolytic activities were evaluated, and histological observations in samples of gastrocnemius muscle were carried out. Inhibition studies were carried out in metal chelator (ethylenediaminetetraacetic acid) presence. Our results show a small Minimum Hemorrhagic Dose (MHD=0.035 microg) and a high proteolytic activity (143 U/mg), and prove the capacity of this venom to degrade fibrinogen in vitro rendering it unclottable by thrombin, supporting the presence of proteases, principally metalloproteases, in P. patagoniensis venom that are able to alterate the vascular wall and degrade fibrinogen, being both activities responsible of a high hemorrhagic activity.

Methylation status in healthy subjects with normal and high serum folate concentration

OBJECTIVE

We assessed the impact of high serum folate concentration on erythrocyte S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH) concentrations, SAM/SAH ratio, CpG methylation levels across the promoter region of the extracellular superoxide dismutase (ec-SOD) gene, and ec-SOD activity in healthy men.

METHODS

Serum folate levels were measured in 111 subjects who were categorized in quintiles according to their folate status. Subjects located at the lowest, middle, and upper quintiles were selected for assessment of SAM and SAH by high-performance liquid chromatography, C677T genotype of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene, ec-SOD methylation of CpG sites in lymphocytes genomic DNA by bisulfate treatment, and ec-SOD activity by a chemical assay.

RESULTS

Sixteen subjects were in the lowest serum folate quintile (<23.6 nmol/L), 17 in the middle (>34-<42 nmol/L), and 14 in the highest (>45nmol/L). SAM concentration was higher in the upper than in the middle and lowest quintiles (5.57 +/- 1.58, 2.52 +/- 0.97, 2.29 +/- 1.2 micromol/L; P < 0.0001). SAH concentration was higher in the upper compared with the lowest quintile (0.76 +/- 0.24 versus 0.52 +/- 0.23 micromol/L, P < 0.001). There were no differences in the SAM/SAH ratio, ec-SOD activity, methylation status of CpG sites of the ec-SOD gene, and TMTHFR C677T genotype between groups.

CONCLUSION

Serum folate concentrations in the highest quintile among healthy humans are associated with increased erythrocyte SAM and SAH concentrations, but not with SAM/SAH ratio or with methylation levels of CpG sites across the promoter region of the ec-SOD gene. Further research is required to determine if these findings are beneficial or harmful.

Antibody response to pneumococcal capsular polysaccharide vaccine in Down syndrome patients

The majority of children with Down syndrome (DS) tend to have frequent bacterial infections including recurrent respiratory infections. Our objective was to evaluate the production of antibodies to pneumococcal polysaccharide antigens after active immunization in DS subjects. IgG antibodies to pneumococcal serotypes (1, 3, 6B, 9V, and 14) were measured before and 6 weeks after immunization with a 23-valent pneumococcal vaccine (Pneumo23, Pasteur-Merrieux) in 6- to 13-year-old DS children (N = 17) and in aged-matched normal controls (N = 30). An adequate response was defined as a 4-fold increase over baseline or a post-immunization level of specific pneumococcal serotype antibody > or = 1.3 microg/mL. After immunization, all DS children had an increase in post-immunization levels against all serotypes analyzed. A 4-fold or more increase was observed in all DS children concerning serotypes 1 and 14, in 90% of subjects for serotypes 3 and 9V, and in 65% for serotype 6B. Regarding this increase, 8 of the 17 DS children had an adequate response to all serotypes analyzed, 8/17 patients to 4 serotypes and 1/17 to 3 serotypes. However, when we compared post-immunization levels between DS children and controls, we observed lower levels in the former group (P < 0.05) for all serotypes except serotype 3. We conclude that pneumococcal polysaccharide immunization could be beneficial for these DS children.

Effects of enalapril or nifedipine on muscle strength or functional capacity in elderly subjects. A double blind trial

INTRODUCTION

The inhibition of angiotensin-converting enzyme could be useful to avoid sarcopenia in the elderly.

MATERIALS AND METHODS

We compared in a prospective double blind trial, the effects of treatment with enalapril or nifedipine on muscle performance in hypertensive elderly subjects. Patients were followed for nine months, and at baseline, 4.5 months and the end of follow-up, quadriceps and hand grip muscle strength, walking capacity, timed up and go and the short physical performance test were measured.

RESULTS

During follow-up, more subjects on nifedipine than on enalapril discontinued the medication due to side-effects. No differences in the evolution of muscle strength, walking capacity or functional measures were observed. At nine months, plasma angiotensin-converting enzyme activity decreased by 6.0+/-2.5 U/L among patients on enalapril and increased by 8.5+/-4.2 U/L (p<0.001) among patients on nifedipine.

CONCLUSION

In this group of elderly subjects, enalapril was not superior to nifedipine with regard to the age-related decline of muscle performance.

Quantitation of soluble HLA class I heterodimers and beta 2-microglobulin in patients with active pulmonary tuberculosis

Beta 2m serum levels have been shown to be increased in patients with tuberculosis and HIV infection. We determined the stability of beta 2m and of sHLA-I dimers in serum, and then determined the levels of both molecules in 60 non-HIV-infected patients with active pulmonary tuberculosis and in 55 adult controls. The levels of sHLA-I in samples kept at room temperature declined by 8% at 30 minutes, 16% at 60 minutes, and 36% at 120 minutes. Beta 2m levels remained stable at all times tested. Mean sHLA-I levels were 0.99 +/- 0.16 micrograms/ml in controls and 1.34 +/- 0.11 micrograms/ml in patients with tuberculosis (P < 0.0001). Beta 2m levels were 1.23 +/- 0.26 micrograms/ml in controls and 2.26 +/- 0.64 micrograms/ml in patients with tuberculosis (P < 0.0001). All patients with tuberculosis had elevation of sHLA-I and/or beta 2m above 1 standard deviation of normal values. However, there was no correlation between sHLA-I and beta 2m levels in individual samples. Evaluation of sHLA-I holds the promise of further understanding of the biology and genetic regulation of the immune response to mycobacterial infection.

Muscle and skin necrotizing and edema-forming activities of Duvernoy's gland secretion of the xenodontine colubrid snake Philodryas patagoniensis from the north-east of Argentina

Philodryas patagoniensis is a colubrid snake spread by all South America, but very little is known about the composition and biological activities of its Duvernoy's gland secretion. In order to characterize it, we studied edematogenic, dermonecrotic and myonecrotic activities. For edematogenic activity, solutions containing different amounts of secretion were injected s.c. in the right foot pad of mice, both feet were subsequently cut off and weighed individually. For myonecrotic activity, mice were injected i.m. with solutions containing 40 microg of secretion, and at various time intervals mice were bled to determine serum creatine kinase activity and gastrocnemius muscles were removed for microscopic examination (Hematoxylin-Eosin stain). For dermonecrotic activity, solutions containing different amounts of secretion were injected into the shaved dorsal skin of mice; the necrotic lesion was measured on the inner surface of the skin and trimmed for microscopic examination (Hematoxylin-Eosin stain). Phospholipase A(2) activity was evaluated using a kinetic method. Results showed that P. patagoniensis Duvernoy's gland secretion exhibits a high edematogenic activity and moderate myonecrotic and dermonecrotic activities, while lacking phospholipase A(2) effect. Regarding edema, a 30% increase in the weight was produced by injecting 0.26 microg of Duvernoy's gland secretion. Microscopically, myonecrosis reached its highest intensity 12 h after injection, which was also demonstrated by serum creatine kinase levels. Dermonecrosis was proportional to the amount of secretion injected, with a minimum necrotizing dose of 15.7 microg. Myonecrotic, edematogenic and dermonecrotic activities were inhibited when the secretion was pre-incubated with 1 mM Na(2)EDTA. This suggests that the enzymes responsible for those activities are mostly metalloproeinases. All the studies carried out up to now demonstrate the potential toxicity of P. patagoniensis Duvernoy's gland secretion (which inhabits the north-east region of Argentina) and that the local lesions caused by this colubrid snake are very similar to those found in bothropic accidents. This latter suggests a more careful evaluation of the victims when considering the medical treatment to be adopted.

Skeletal muscle ceramide species in men with abdominal obesity

BACKGROUND

Obesity is a risk factor for diabetes and its consequences, including accelerated ageing and mortality. The underlying factor could be accumulation of certain lipid moieties, such as ceramides (CER) and diacylgycerol (DAG) within muscle tissue, which are known to promote insulin resistance (IR), induce inflammation and oxidative injury, ultimately altering muscle function.

AIM

First, to study the relationship between body composition and age (independent variables) with skeletal muscle accumulation of lipid species, oxidative injury and strength. Second, to analyze the relationship between muscle tissue metabolites and insulin resistance, inflammation and lymphocyte telomere length, the latter as an indicator of ageing.

METHODOLOGY

The sample included 56 healthy sedentary males, scheduled for inguinal hernia surgery, aged 27 to 80 y. Each individual was subject to anthropometric measurements, body composition assessment through radiologic densitometry (DEXA), measurement of handgrip and quadriceps strength, serum biochemical parameters (lipoproteins, creatinine, high sensitivity C reactive protein [hsCRP], fasting and post glucose insulin and glucose concentrations for calculation of IR through the Matsuda and HOMA-IR indexes), and extraction of peripheral leukocytes for measurement of telomere length. During the surgical procedure, a sample of muscle tissue was obtained (anterior abdominal oblique) in order to measure CER and DAG (and sub species according to chain length and saturation) by mass spectrometry, 4 hydroxy-2-nonenal adducts (4-HNE) using electron microscopy immunohistochemistry, and carboxymethyl-lisine (CML) by immunohistochemistry, the latter as indicators of oxidative stress (OS).

RESULTS

Body mass index (BMI) of twenty six individuals was > 25 k/m2, while BMI of 7 was > 30 k/m2. Overweight/obese individuals, did not exhibit differences in skeletal muscle lipid metabolites, however total CER and specific long chain CER sub-species (20 and 22 carbon) increased significantly among individuals with a central fat distribution (n = 14) as well as in glucose intolerant subjects (n =23). A negative association was found between mononuclear leukocyte telomere length and 20 and 22 carbon CER (rho = - 0.4 and -0.5 0 p < 0.05). Muscle strength was not associated with any of the measured muscle metabolites or markers of OS. A multiple regression analysis accepted central abdominal fat and telomere length as significant predictors of CER (R2 = 0.28).

CONCLUSIONS

An association was found between accumulation of specific ceramide species in muscle tissue and abdominal obesity, glucose intolerance and shortening of leukocyte telomeres, although not with muscle oxidative injury or dysfunction.

Hyperhomocysteinemia in healthy young men and elderly men with normal serum folate concentration is not associated with poor vascular reactivity or oxidative stress

The mechanism by which homocysteine (Hcy) causes endothelial dysfunction is probably mediated by oxidative stress. The aim of this study was to evaluate the effect of oxidative stress on endothelial function in young and elderly hyperhomocysteinemic (HHcy) men. A total of 35 HHcy (Hcy > 15 micro mol/L), young (n = 15; 20-40 y) and elderly men (n = 20; > 65 y) and 33 normohomocysteinemic (NHcy; controls) young (n = 14) and elderly (n = 19) men (Hcy < 13 micro mol/L), without classic cardiovascular risk factors were recruited. Serum Hcy, folate, and vitamin B-12, whole-blood glutathione, plasma total antioxidants status, TBARS, and 8-F(2alpha) isoprostanes were determined. Noninvasive ultrasound measurements of endothelium-dependent (EDVR) and -independent dilatation (EIVR) were performed. EDVR, EIVR, and markers of oxidative stress did not differ among the groups. Folate concentrations were higher in elderly than in young men (P < 0.001), independent of Hcy concentrations. Vitamin B-12 concentrations were lower in HHcy than in NHcy elderly men (P < 0.045). EDVR was correlated with folate concentrations in young men (r = 0.40, P = 0.04) and negatively with BMI in elderly men (r = -0.52, P = 0.002). In the present study, HHcy with normal serum folate concentrations was not associated with poor EDVR or oxidative stress in healthy young and elderly men.

The hypothalamic-pituitary-adrenal axis in infantile malnutrition

We studied the circadian rhythm and the response of the hypothalamic-pituitary-adrenal (HPA) axis to ovine corticotrophin releasing hormone (oCRH) stimulation and dexamethasone suppression in 32 children with grade II-III marasmus. Children were studied prior to and after nutritional rehabilitation. Mean baseline plasma cortisol concentrations were elevated at admission and decreased significantly after nutritional rehabilitation. Mean +/- SEM plasma cortisol response to oCRH increased from a basal of 480 +/- 41 to a peak of 582 +/- 58 nmol/l at the time of admission, and from a basal of 234 +/- 27 to a peak of 532 +/- 41 nmol/l after caloric rehabilitation. Dexamethasone suppression in the malnourished group was associated with a decrease in the mean +/- SEM basal plasma cortisol concentration from 397 +/- 44 to 171 +/- 44 nmol/l. After caloric rehabilitation, basal cortisol levels decreased from 259 +/- 27 to 22 +/- 5 nmol/l following dexamethasone. Our results support the concept that malnutrition is associated with decreased responsiveness to oCRH and incomplete dexamethasone suppression, and that these abnormalities are restored after nutritional rehabilitation.

Duvernoy's gland secretion of Philodryas patagoniensis from the northeast of Argentina: its effects on blood coagulation

Duvernoy's gland secretion of Philodryas patagoniensis exhibits high hemorrhagic activity, containing enzymes that are able to degrade the vascular wall. In this work we aim to determine if the secretion can also affect the hemostatic system by causing changes in blood coagulation. Procoagulant and coagulant activities were evaluated on plasma and fibrinogen, respectively. The delay in the thrombin clotting time of fibrinogen previously incubated with the secretion was also determined. Specific hydrolysis of fibrinogen and fibrin incubated with the secretion at different time intervals was shown by electrophoresis on polyacrylamide gel. To determine the structural characteristics of the enzymes degrading fibrinogen and fibrin, secretion were incubated in the presence of 45 mM Na(2)EDTA, 40 mM Benzamidine, and/or 2 mM PMSF before the incubation with fibrinogen or fibrin, respectively. The effect in vivo was investigated in adult male rats injected with different dose of secretion, aliquots of blood were withdrawn at different time intervals, and the fibrinogen concentration was determined. Duvernoy's gland secretion of P. patagoniensis did not clot plasma or fibrinogen. It exhibited a potent fibrinogenolytic activity degrading the Aalpha-chain faster than the Bbeta-chain, whereas gamma-chain was resistant. This latter corresponded with a strong delay in the thrombin clotting time of fibrinogen (4 mg/ml) pre-incubated with the secretion, being 9.53 microg the amount of protein from Duvernoy's gland secretion that increased the thrombin clotting time from 20 to 60 s. In vivo, the loss of rat plasma fibrinogen was proportional to the amount of secretion injected. The secretion also hydrolyzed fibrin degrading the alpha-monomer. Inhibition studies with Na(2)EDTA, Benzamidine, and/or PMSF showed that metalloproteinases and serinoproteinases are the main enzymes responsible for the hydrolyzing activity on fibrinogen and fibrin. All these results demonstrate that Duvernoy's gland secretion of P. patagoniensis possesses enzymes able to hydrolyze plasma components playing a relevant role in the blood coagulation. These hydrolyzing activities and those acting on the wall of blood vessels let the secretion exhibit a high hemorrhagic activity, which may result in permanent sequelae or even cause the death of the victims bitten by this colubrid snake.