Protein C Deficiency Causing Recurrent Myocardial Infarction in a Young Male

Protein C is one of the most important factors that prevent blood from clotting. Protein C deficiency usually leads to venous thrombosis. We intend to report a male of 38 years admitted in coronary care unit of Dhaka Medical College Hospital, who suffered recurrent episodes of myocardial infarction, whose traditional risk factors were well controlled. Ultimately he was diagnosed with protein C deficiency, which is not commonly implicated in arterial thrombosis. Protein C deficiency can rarely cause severe life threatening arterial thrombosis, like myocardial infarction. Many more cases are reported in recent literature. It can happen sporadically. A high degree of suspicion should be maintained if traditional risk factors are absent in instances of arterial thrombosis, to look for protein C deficiency.

Folic acid supplementation on red kidney bean-induced diarrhoea and enteric bacterial translocation into mesenteric lymph nodes in rats: a pilot study

Deaths following childhood diarrhoea, a major health problem in developing countries, are often associated with malnutrition and septicaemic complications. Folic acid has been used in the treatment of acute and chronic diarrhoea in the tropics. Using a rat model, we evaluated the protective effect of large doses of folic acid on diarrhoea, small intestinal bacterial overgrowth and translocation of enteric bacteria into mesenteric lymph nodes induced by a raw red kidney bean-based diet containing lectin (phytohemagglutinin). Long-Evans rats in 2 groups of 5 each (60 g to 70 g in weight, 28 d old) were used. All 10 rats, individually kept in metabolic cages, received a raw red kidney bean-based diet for 10 d, and 5 of them also received a daily folic acid supplement (160 microg/g feed) both during and for 10 d before the experiment. The faecal weight was measured and a quantitative aerobic bacterial culture of the small intestinal mucosal scrapings and of the mesenteric lymph nodes was made. Folic acid supplementation did not reduce faecal output nor did it prevent loss of body weight associated with lectin-induced diarrhoea. However, the mean total count of enteric bacteria translocated to the mesenteric lymph nodes was significantly reduced in the supplemented rats (1.27 +/- 0.61 vs 2.66 +/- 0.84, p = 0.028) and a trend towards reduced bacterial count in the small intestinal mucosal scrapings (0.40 +/- 0.89 vs 1.42 +/- 1.31, p = 0.16) was documented. A significant positive correlation was also seen between the bacterial count in the jejunal mucosal scrapings and in the mesenteric lymph nodes.

CONCLUSION

Although large-dose folic acid supplementation did not prevent diarrhoea and malnutrition induced by a lectin-based diet, it substantially reduced the count of enteric bacteria translocated into the mesenteric lymph nodes and showed a trend towards a reduction in indigenous bacteria adhering to jejunal mucosa. These findings could be of relevance in the prevention of septicaemic complications following many clinical conditions, including diarrhoea with malnutrition in children known to have bacteraemic and septicaemic complications.

Low-density lipoprotein (LDL)-induced monocyte-endothelial cell adhesion, soluble cell adhesion molecules, and autoantibodies to oxidized-LDL in chronic renal failure patients on dialysis therapy

Premature atherosclerosis is a major cause of morbidity and mortality in chronic renal failure patients undergoing dialysis. In this study, we compared autoantibodies to oxidized low-density lipoprotein (OX-LDL), soluble cell adhesion molecules (CAMs), and the effect of both LDL and OX-LDL on monocyte endothelial cell adhesion in chronic renal failure patients on hemodialysis (HD, n = 16) and peritoneal dialysis (PD, n = 17) compared with matched healthy control subjects (C, n = 17). In addition, we studied the effect of supplementation with RRR-alpha-tocopherol (AT) 800 IU/d for 12 weeks on the above measures. LDL and OX-LDL induced adhesion of U937 cells to cultured endothelium, soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intracellular adhesion molecule-1 (sICAM-1), and soluble E-selectin (sE-selectin); autoantibodies to OX-LDL and markers of lipid peroxidation were determined before and after AT supplementation. Native LDL from PD patients induced greater monocyte-endothelial cell adhesion than LDL from C subjects (43.8% +/- 17.0% v25.3% +/- 17.7%, respectively, P = .0028). OX-LDL from chronic renal failure patients on both PD and HD stimulated greater adhesion than OX-LDL from the C subjects (68.0% +/- 18.5% and 57.6% +/- 15.1% v 40.9% +/- 17.3%, respectively, P < .01); OX-LDL from PD patients induced greater adhesion than that from HD patients (P < .01). Plasma methylglyoxal levels were significantly increased in both HD and PD groups, with higher levels in the HD group. Chronic renal failure patients on HD and PD also had higher levels of plasma sVCAM-1 and sE-selectin than C subjects (P < .01), indicating endothelial activation. Titers of autoantibodies to OX-LDL were not elevated in renal failure patients. Supplementation with AT 800 IU/d for 12 weeks, while resulting in significant enrichment with AT in LDL, did not have a significant effect on any of the parameters studied. This study makes the novel observation that the LDL of chronic renal failure patients on HD and PD appears to be potentially more atherogenic, since it induces greater monocyte-endothelial cell adhesion.

Alpha-tocopherol supplementation decreases the oxidative susceptibility of LDL in renal failure patients on dialysis therapy

Atherosclerotic cardiovascular disease is the leading cause of death in patients with end stage renal disease (ESRD) who have undergone dialysis treatment. The oxidation of low density lipoprotein (LDL) appears to be a crucial step in the pathogenesis of atherosclerosis. The increased oxidative stress and attendant increased oxidizability of lipoproteins, such as LDL could contribute to the accelerated atherosclerosis in dialysis patients. Since alpha-tocopherol (AT) is the major antioxidant in LDL, the aim of the present study was to test the effectiveness of RRR-AT supplementation (800 I.U. per day) for 12 weeks on the susceptibility of LDL to oxidation. The study subjects comprised patients with chronic renal failure on hemodialysis (HD), peritoneal dialysis (PD), and age and sex matched controls (C). Plasma fatty acids, lipoproteins and AT levels were measured in these subjects before and after supplementation. Also, LDL AT and oxidizability was studied. LDL was isolated by ultracentrifugation at baseline and after 12 weeks of supplementation, and subjected to a 5-h time course of copper catalyzed oxidation. Oxidation was measured by the formation of conjugated dienes (CD) and lipid peroxides (LP). Supplementation with AT did not alter the plasma lipid or lipoprotein profile of these subjects. Plasma lipid-standardized AT and LDL AT concentrations were not different among the groups at baseline. AT supplementation significantly increased plasma lipid-standardized AT (C=150%, HD=149%, PD=217%, P<0.001) and LDL AT concentrations (C=94%, HD=94%, PD=135%, P<0.003). AT enrichment of LDL resulted in a significant prolongation in conjugated diene lag phase in all groups (C=34%, HD=21%, PD=54%, P<0.02). Lipid peroxide lag phase was also increased significantly in C (27%,) and PD (40%) groups after AT supplementation (P<0.01). There was a significant positive correlation between plasma lipid standardized AT and lag phase (r=0. 54, P=0.0003). Overall, AT decreased the susceptibility of LDL to oxidation in patients with chronic renal failure but the benefit appears to be greater in patients on PD. Therefore, AT supplementation may also provide a measure of protection against CAD in patients with chronic renal failure on dialysis therapy.

The contribution of fructose and nitric oxide to oxidative stress in hamster islet tumor (HIT) cells through the inactivation of glutathione peroxidase

Reducing sugars, such as glucose and fructose, are known to play a role in the initiation of apoptosis in pancreatic beta-cells. The data collected in this study show that fructose increases H2O2 levels and lipid peroxidation of hamster islet tumor (HIT) cells, which originated from hamster pancreatic beta-cells. In an attempt to clarify the mechanism of this oxidative stress, we were able to show that glutathione peroxidase (GPx) is inactivated by fructose, and that mRNA expression of GPx is suppressed by fructose. Nitric oxide (NO) is also known to bring about apoptosis. The presence of NO increases intracellular peroxide levels in HIT cells as judged by flow cytometric analysis. These data suggest that fructose and nitric oxide suppress the activity or expression of GPx, and, as a result, permit an increase in intracellular peroxides or lipid peroxidation. This represents a major contribution to the main mechanism of apoptosis by fructose and NO.

alpha-Tocopherol enrichment of monocytes decreases agonist-induced adhesion to human endothelial cells

BACKGROUND

Monocyte-endothelium adhesion is a crucial early event in atherogenesis. Several reports indicate that alpha-tocopherol (AT) is a potent antioxidant in plasma and LDL and also has intracellular effects that are antiatherogenic. Recently, it has been shown that AT supplementation results in decreased monocyte-endothelial cell adhesion. However, there is a paucity of data on the mechanisms by which AT inhibits adhesion of monocytes. We studied the effect of AT enrichment of a human monocytic cell line, U937, on adhesion to human umbilical vein endothelial cells (HUVECs).

METHODS AND RESULTS

Both lipopolysaccharide (LPS)- and N-formyl-methionyl-leucyl-phenylalanine (FMLP)-stimulated U937 adhesion to HUVECs were studied. AT (50 and 100 micromol/L) significantly decreased adhesion of both LPS- and FMLP-stimulated U937 cells to HUVECs (LPS-treated cells, P<0.0125; FMLP-treated cells, P<0.05). Expression of the adhesion molecules CD11a, CD11b, CD11c, very late antigen-4 (VLA-4), and L-selectin, as assessed by flow cytometry, was increased in the stimulated U937 cells, and AT resulted in significant reduction in the expression of CD11b and VLA-4. In addition, activation of the transcription factor nuclear factor-kappaB (NF-kappaB), as assessed by gel shift assays, was inhibited by pretreatment with AT in LPS-treated U937 cells.

CONCLUSIONS

AT significantly decreases adhesion of activated monocytes to endothelial cells by decreasing expression of CD11b and VLA-4 on monocytes, possibly by inhibiting the activation of NF-kappaB.

TGF-beta1 triggers oxidative modifications and enhances apoptosis in HIT cells through accumulation of reactive oxygen species by suppression of catalase and glutathione peroxidase

Transforming growth factor-beta1 (TGF-beta1) is a multifunctional polypeptide that is related to the progression of chronic pancreatitis. However, the mechanism of beta-cell damage by TGF-beta1 is unknown. Treatment with TGF-beta1 enhanced internucleosomal DNA cleavage caused by exogenous hydrogen peroxide in a hamster pancreatic beta-cell line (HIT). TGF-beta1 also induced protein oxidation, assessed by measuring carbonyl groups in proteins, and was involved in reactions that lead to lipid peroxidation. This eventually destructs membrane lipids and forms malondialdehyde. We have investigated its effects on two major antioxidative enzymes, catalase and glutathione peroxidase (GPx). TGF-beta1 suppressed mRNA expression as well as reduced the activities of catalase and GPx. The decrease in the catalase and GPx activities in TGF-beta1-treated cells resulted in an increase in intracellular peroxides as judged by flow cytometric analysis using a peroxide-sensitive dye, 2',7'-dichlorofluorescin diacetate. These data suggest that the augmented production of reactive oxygen species by TGF-beta1 through suppression of antioxidative enzymes may cause cellular damage and consequent apoptosis and induce pancreatitis or diabetes.

Reducing sugars trigger oxidative modification and apoptosis in pancreatic beta-cells by provoking oxidative stress through the glycation reaction

Several reducing sugars brought about apoptosis in isolated rat pancreatic islet cells and in the pancreatic beta-cell-derived cell line HIT. This apoptosis was characterized biochemically by inter-nucleosomal DNA cleavage and morphologically by nuclear shrinkage, chromatin condensation and apoptotic body formation. N-Acetyl-L-cysteine, an antioxidant, and aminoguanidine, an inhibitor of the glycation reaction, inhibited this apoptosis. We also showed directly that proteins in beta-cells were actually glycated by using an antibody which can specifically recognize proteins glycated by fructose, but not by glucose. Furthermore, fluorescence-activated cell sorting analysis using dichlorofluorescein diacetate showed that reducing sugars increased intracellular peroxide levels prior to the induction of apoptosis. Levels of carbonyl, an index of oxidative modification, and of malondialdehyde, a lipid peroxidation product, were also increased. Taken together, these results suggest that reducing sugars trigger oxidative modification and apoptosis in pancreatic beta-cells by provoking oxidative stress mainly through the glycation reaction, which may explain the deterioration of beta-cells under conditions of diabetes.

A fluorescent assay method for GDP-L-Fuc:N-acetyl-beta-D-glucosaminide alpha 1-6fucosyltransferase activity, involving high performance liquid chromatography

An assay method for GDP-L-Fuc:N-acetyl-beta-D-glucosaminide alpha 1-6fucosyltransferase (alpha 1-6FucT; EC 2.4.1.68) activity has been developed, involving a fluorescent pyridylaminated substrate. A glycopeptide derived from bovine gamma-globulin was coupled with 4-(2-pyridylamino)butylamine (PABA) through the peptide bond, and the following substrate was obtained. [equation: see text] The substrate and guanosine diphospho-fucopyranoside (GDP-Fuc) were incubated with a crude enzyme extract for 2 h, and then the enzymatic product was separated by reversed phase HPLC. Quantitation of the product involved measurement of the fluorescence intensity of the fucosylated pyridylaminated sugar. The structures of both synthesized GnGn-bi-Asn-PABA (substrate), and synthesized GnGnF-bi-Asn-PABA (product) were analyzed by 1H NMR. The enzymatic product was also analyzed by 1H NMR and was found to have alpha 1-6fucose at the reducing end GlcNAc. This method is highly specific for alpha 1-6FucT and is applicable for various experiments, including purification and cell culture ones.

The protective role of glutathione peroxidase in apoptosis induced by reactive oxygen species

Selenium-dependent glutathione peroxidase (GPx) plays a protective role in oxidative stress-induced apoptosis. In this study, we demonstrated that MDBK cells, a bovine renal epithelial cell line, exhibited internucleosomal DNA fragmentation characteristic of apoptotic cell death under selenium-deficient conditions with lower doses of hydrogen peroxide (H2O2) than under selenium-supplemented ones. This was due to a decreased amount of GPx in the cells under selenium-deficient conditions, because other antioxidative enzyme activities were not affected by the selenium supplementation. Cumene hydroperoxide also induced DNA fragmentation in selenium-deficient cells but no ladder formation was observed. Flow cytometric analysis showed that selenium-deficient cells were less capable of scavenging intracellular peroxides after exposure to exogenous H2O2 than selenium-supplemented ones. In contrast, there was no difference in viability between selenium-supplemented and non-supplemented cells in cell survival after exposure to menadione, which activates the electron transport system and increases intracellular superoxide radicals. Clofibrate, a peroxisomal proliferator and an inducer of catalase (CAT), partially protected both Se-deficient and Se-supplemented cells from exogenous H202. We concluded that selenium-deficient cells were more easily brought to apoptotic cell death by peroxides, but not by superoxide radicals, than selenium-supplemented ones and that CAT could compensate for the depletion of GPx to a certain degree by scavenging H2O2.

Fragmentation of ceruloplasmin following non-enzymatic glycation reaction

Bovine ceruloplasmin underwent fragmentation following non-enzymatic glycosylation. Western blot and ELISA analyses indicated that a polyclonal rabbit antiserum to hexitolysine reacted with bovine ceruloplasmin after incubation with 0.1 M glucose. The same fragmentation was seen upon exposure of the protein to a hydrogen peroxide bolus. Both catalase and EDTA blocked peroxide-dependent fragmentation. Incubation with glucose resulted in a time-dependent release of Cu2+. The released Cu2+ appeared to participate in a Fenton-type reaction to produce hydroxyl radicals, which effected the fragmentation. Hydroxyl radical scavengers such as thiourea, mannitol, methionine, and formate inhibited this cleavage. ESR spectral studies also supported participation of hydroxyl radicals. Inhibition by EDTA of the fragmentation induced by an H2O2 bolus also supports a role for copper in a Fenton-type reaction. Taken together these results suggest that reactive oxygen species, such as superoxide anion and H2O2, were formed by the Maillard reaction which led to hydroxyl radicals being produced by a copper-dependent Fenton-type reaction. Both processes are likely to be involved in the fragmentation of ceruloplasmin.

Peptide-containing nerves in human urinary bladder

Nerves containing immunoreactive vasoactive intestinal polypeptide (VIP), substance P and two newly discovered peptides, neuropeptide tyrosine (NPY) and PHI (peptide having N-terminal histidine and C-terminal isoleucine), have been found in the human urinary bladder by immunocytochemistry and radioimmunoassay. Somatostatin immunoreactivity was detected by radioimmunoassay. The VIP-immunoreactive nerves were widely distributed in all regions, but were particularly dense beneath the epithelium and in the muscle layer. Scattered intramural ganglia were found to be reactive to VIP antiserum. Higher concentrations of extractable VIP were detected in the trigone than in the dome. VIP- and PHI-immunoreactive nerves were similarly distributed, the latter being less numerous. NPY-immunoreactive nerves were seen mainly in the muscle layer, particularly in the trigonal area. The distribution patterns of VIP- and NPY-immunoreactive nerves resembled those of the previously reported cholinergic and adrenergic nerves, respectively. Many blood vessels were found to be innervated by both types of immunoreactive nerves. Scattered substance P-immunoreactive fibers were occasionally seen, being present in the submucosa and around the detrusor muscles. The significance of these nerves remains to be elucidated.

Peptidergic innervation of the human male genital tract

Four peptides--vasoactive intestinal polypeptide, substance P, somatostatin and a peptide-like avian pancreatic polypeptide--have been found in nerves of the human male genitalia using highly sensitive and specific methods of immunocytochemistry and radioimmunoassay. Five other peptides (met-enkephalin, leu-enkephalin, neurotensin, bombesin and cholecystokinin-8) were absent. Vasoactive intestinal polypeptide was the most abundant peptide, its highest concentration being in the proximal corpus cavernosum. Immunoelectron microscopy localized this peptide to large (97 +/- 20 nm), round, electron-dense granules of p-type nerve terminals. Vasoactive intestinal polypeptide-immunoreactive neuronal cell bodies were found in the prostate gland and the root of the corpus cavernosum. Substance P immunoreactive material was present in smaller concentration and was mainly localized in nerves around the corpuscular receptors of the glans penis. Somatostatin immunoreactive nerves were associated mainly with the smooth muscle of the seminal vesicle and the vas deferens. When antiserum to avian pancreatic polypeptide was applied, certain nerves were stained, particularly in the vas deferens, the prostate gland and the seminal vesicle. However, chromatography detected no pure avian pancreatic polypeptide suggesting the presence of a structurally related substance, possibly neuropeptide Y, which cross-reacts with the avian pancreatic polypeptide antiserum. Similar distributions between vasoactive intestinal polypeptide-immunoreactive and acetylcholinesterase-positive nerves and between avian pancreatic polypeptide-immunoreactive and adrenergic nerves were observed. A general neuronal marker, neuron-specific enolase, was used to investigate the general pattern of the organ's innervation. The abundance and distribution patterns of these peptide-immunoreactive nerves indicate that they may play important roles in the male sexual physiology.

Repeated application of first-layer antiserum improves immunofluorescence staining: a modification of the indirect immunofluorescence staining procedure

Repeated application of the first-layer antiserum in the indirect immunofluorescence technique considerably improves the immunostaining. The modified method reveals more antigenic sites and increases the contrast between specific and background stainings, particularly where sparsely distributed antigenic areas are to be investigated. The effect of this novel immunostaining procedure is compared with that of the routine procedure and of other modifications. Possible mechanisms for the improving effect are discussed. A procedure of combined modifications is recommended for exploration of non-abundant antigens or for achieving a high-quality photograph.