Effects of Helicobacter pylori vacuolating cytotoxin on primary cultures of human gastric epithelial cells

BACKGROUND: Many Helicobacter pylori strains produce a cytotoxin that induces cytoplasmic vacuolation in various types of eukaryotic cells. In contrast with the marked cell vacuolation that occurs in vitro in response to this cytotoxin, comparatively little epithelial vacuolation has been observed in the gastric mucosa of H pylori infected persons. AIMS: Experiments were performed to determine the susceptibility of human gastric epithelial cells in vitro to H pylori vacuolating cytotoxin activity. METHODS: Human gastric epithelial cells, harvested from upper gastrointestinal endoscopic biopsy specimens, were incubated overnight with broth culture supernatants from either a wild type cytotoxin producing (tox+) H pylori strain or an isogenic mutant strain that lacks cytotoxin activity. RESULTS: Prominent cytoplasmic vacuolation occurred in response to tox+ supernatant, but not supernatant from the isogenic mutant strain. Primary human gastric epithelial cells were significantly more sensitive to H pylori vacuolating cytotoxin activity than were either HeLa or AGS cells. Exposure of human gastric epithelial cells to high concentrations of tox+ supernatant for 48 hours caused lethal cell injury. CONCLUSIONS: These studies indicate that primary human gastric epithelial cells are highly sensitive to H pylori vacuolating cytotoxin activity.     

Chronic exposure of cultured bovine endothelial cells to oxidized LDL abolishes prostacyclin release

We investigated the effect of chronic exposure (3 days) with low-density lipoprotein (LDL) and oxidized (Ox)-LDL on the unstimulated and stimulated formation of prostacyclin (6-keto-prostaglandin [PG]F1 alpha) and total inositol phosphates (IPs) by cultured bovine aortic endothelial cells. Neither basal nor bradykinin-stimulated (1 to 10 nmol/L) formation of 6-keto-PGF1 alpha was affected by LDL, except at the highest concentration of bradykinin tested (100 nmol/L). In the presence of the antioxidants N-acetyl-L-cysteine (NAC, 10 mumol/L) or vitamin E (100 mumol/L), basal and bradykinin-stimulated formation of 6-keto-PGF1 alpha was potentiated by 20 micrograms protein/mL of LDL. Ox-LDL decreased unstimulated formation of the eicosanoid from 3.1 +/- 0.2 pg/micrograms protein in control cells to 1.6 +/- 0.1 and 0.5 +/- 0.1 pg/microgram protein after 3-day incubation with 5 and 20 micrograms protein/mL of Ox-LDL, respectively (P < .05). As in the basal state, Ox-LDL decreased bradykinin-induced 6-keto-PGF1 alpha formation. NAC or vitamin E did not influence Ox-LDL-induced endothelial cell changes in eicosanoid production. IPs formation by endothelial cells increased to a similar extent in the presence of 20 micrograms protein/mL of either LDL or Ox-LDL. However, no change was apparent in the bradykinin (10 mumol/L)-induced increase in total IPs formation after incubation with the lipoproteins. The data indicate that chronic exposure to Ox-LDL abolishes the production of prostacyclin by cultured endothelial cells. The oxidatively modified lipoprotein seems to more specifically affect the prostacyclin pathway.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibition of tuberoinfundibular dopaminergic neural activity during suckling: involvement of mu and kappa opiate receptor subtypes

Previous studies have shown that mu (mu) and kappa (kappa) opioid antagonists inhibit suckling-induced prolactin release. Prolactin responses elicited by pup suckling or opioid administration are mediated, at least in part, by suppression of dopamine (DA) release from tuberoinfundibular dopaminergic (TIDA) neurons in the hypothalamus. We examined the effects of the mu opiate receptor antagonist, beta-funaltrexamine (beta-FNA), and the kappa opiate receptor antagonist, nor-binaltorphimine (nor-BNI) on the activity of TIDA neurons in lactating rats. TIDA neuronal activity was determined by measuring DOPA accumulation in the caudate putamen (CP) and median eminence (ME). The effects of opioid antagonist treatment were determined in pup-deprived (low circulating prolactin levels) or pup-suckled rats (high circulating prolactin levels). The accumulation of 5-hydroxytryptophan (5-HTP) in the medial preoptic area (MPOA), the anterior hypothalamus (AH) and the median eminence (ME) was quantified as an index of serotonergic activity in the same animals for comparative purposes. In vehicle treated rats, suckling caused a significant and selective decrease in DOPA accumulation in the ME. beta-FNA (5 micrograms, i.c.v.) pretreatment significantly increased DOPA accumulation in the ME of pup-deprived and pup-suckled rats. beta-FNA pretreatment also prevented the suckling-induced suppression of DOPA accumulation in the ME. In contrast to the actions of beta-FNA, pretreatment with nor-BNI (8 micrograms, i.c.v.) did not significantly affect the activity of the TIDA neurons in pup-deprived or pup-suckled rats. Suckling alone did not alter 5-HTP accumulation in any of the brain regions examined, and neither opioid antagonist had appreciable effects on 5-HTP accumulation. These results demonstrate that the EOP tonically inhibit the TIDA neurons in both pup-deprived and pup-suckled, post-partum female rats by acting through the mu, but not the kappa, opiate receptor subtype. Furthermore, the suckling-induced inhibition of TIDA neurons is also mediated through the EOP acting at mu, but not kappa opioid receptors.     

Promotion of healthy lifestyle: knowledge and attitudes of primary care physicians

Preretinal neovascularization and chronic retinal oedema are the two major sight-threatening complications that can occur during diabetic retinopathy. Ocular neovascularization is strongly associated with retinal ischaemia, and growth factors have been implicated in its pathogenesis. The ischaemic retina is assumed to secrete growth factors that stimulate residual vessels to proliferate. Interest has focused on basic fibroblast growth factor (bFGF), insulin-like growth factor-1 (IGF-1), platelet-derived growth factor (PDGF), transforming growth factor beta (TGF beta) and more recently vascular endothelial cell growth factor (VEGF). Histologic studies have demonstrated the presence of growth factor proteins and receptors and/or their mRNA, mainly VEGF, PDGF, and bFGF, in preretinal membranes of patients with proliferative diabetic retinopathy. Elevated intravitreal levels of IGF-1 and VEGF correlating with neovascular activity have been found in some patients. However, a direct causal relationship between ischaemia, growth factors and neovascularization has not been clearly demonstrated despite considerable research work. To date, the growth factor correlating most closely with neovascularization is VEGF. As many growth factors seem to be produced during the neovascular process, their specific inhibition probably will have limited effects. Laser photocoagulation of the retina has proved beneficial for regression of new vessels, probably through destruction of the ischaemic retina producing neovascular growth factors, and is currently the only treatment for proliferative diabetic retinopathy. Inhibition of IGF-1 by somatostatin analogs has produced unsatisfactory results. Other vascular inhibitors are currently being studied.     

Hydroxychloroquine reverses thrombogenic properties of antiphospholipid antibodies in mice

BACKGROUND: Previous studies have demonstrated that human monoclonal and polyclonal anticardiolipin antibodies have thrombogenic properties in vivo. Using such a model in which these antibodies have been shown to increase both the size of an induced thrombus and the duration of time in which such a clot lasts, we investigated whether hydroxychloroquine alters the dynamics of such thrombus formation. METHODS AND RESULTS: Three groups of nine mice were injected with purified immunoglobulin G (IgG) from a patient with the antiphospholipid syndrome (IgG-APS) and then fed with hydroxychloroquine at various doses (100, 6, and 3 mg/kg body wt). Three control groups of mice were also studied, including mice injected with IgG-APS and then fed with placebo, as well as two other groups injected with IgG from normal human serum and fed either hydroxychloroquine or placebo. A standardized thrombogenic injury was subsequently induced in the femoral vein of each mouse and the area (size) of thrombus measured as well as the total period of time that thrombus was present. Mice treated with hydroxychloroquine and IgG-APS showed significantly smaller thrombi that persisted for a shorter period of time compared with animals treated with IgG-APS and placebo. CONCLUSIONS: Hydroxychloroquine significantly diminished both thrombus size and total time of thrombus formation in mice previously injected with IgG-APS.     

Thyroid status and exercise tolerance. Cardiovascular and metabolic considerations

Both hypo- and hyperthyroidism are characterised by exercise intolerance. In hypothyroidism, inadequate cardiovascular support appears to be the principal factor involved. Insufficient skeletal muscle blood flow compromises exercise capacity via reduced oxygen delivery, and endurance through decreased delivery of blood-borne substrates. The latter effect results in increased dependence on intramuscular glycogen. Additionally, decreased mobilisation of free fatty acids from adipose tissue and, consequently, lower plasma free fatty acid levels compound the problem of reduced lipid delivery to active skeletal muscle in the hypothyroid state. In contrast, cardiovascular support is enhanced in hyperthyroidism, implicating other factors in exercise tolerance. Greater reliance on muscle glycogen appears to be the primary reason for decreased endurance. Biochemical changes with hyperthyroidism that would favour enhanced flux through glycolysis may account for this dependence on glycogen. Deviations from normal thyroid function, and the ensuing exercise tolerance, require appropriate medical therapy to attain euthyroid status.     

Cataract surgery and YAG-laser capsulotomy following vitrectomy for diabetic retinopathy

The present study was initiated to assess time-course and risk factors for the development of cataract and posterior-capsule opacification as well as complications of cataract surgery and YAG-laser capsulotomy following vitrectomy for diabetic retinopathy. The charts of all patients undergoing vitrectomy for diabetic retinopathy during a 5-year period in a university eye hospital were retrospectively reviewed. The course of 306 consecutive eyes in which the lens was retained during vitrectomy was analyzed for subsequent cataract surgery and YAG-laser capsulotomy. The first 6 months after cataract or YAG-laser surgery were examined for the occurrence of complications. Data were analyzed with regard to the time course using Kaplan-Meier life-table analysis. The proportion of eyes that underwent cataract surgery after vitrectomy increased nearly linearly with time, approaching 75% after 5 years. Silicone tamponade (relative risk 1.9; P = 0.0005) and transscleral retinal cryotherapy (relative risk 1.4; P = 0.003) were risk factors for subsequent cataract surgery. No significant cataractogenous effect of intravitreal gas as compared with balanced salt solution was found. YAG-laser capsulotomy was performed in 60% of vitrectomized diabetic eyes within 2 years but in only 10% of nondiabetic controls (P < 0.0001). Within 6 months of extracapsular cataract surgery with implantation of an intraocular lens (IOL) in 54 eyes, no serious complication was observed. After YAG-laser capsulotomy, vitreous hemorrhage occurred within 6 months in 6 of 21 eyes. In conclusion, cataract surgery was performed in 75% of the phakic eyes within 5 years of vitrectomy for diabetic retinopathy. Posterior capsular opacification is particularly common in this subset of eyes. No serious complication was observed after extracapsular cataract surgery with IOL implantation, but YAG-laser capsulotomy was associated with an increased risk for vitreous hemorrhage.     

One-year prevalence of psychiatric disorder in Ontarians 15 to 64 years of age

OBJECTIVE: To present the one-year prevalence of 14 psychiatric disorders in a community sample of Ontarians aged 15 to 64 years. METHOD: Data on psychiatric disorders were collected on 9953 respondents using the University of Michigan revision of the Composite International Diagnostic Interview (UM-CIDI). DSM-III-R criteria were used to define the psychiatric disorders. RESULTS: Almost 1 in 5 Ontarians (18.6%) had one or more of the disorders measured in the survey. Among 15-to 24-year-olds, 1 in 4 was affected. The distribution of individual disorders varied by sex and age. CONCLUSION: Because of the immense burden of suffering associated with psychiatric disorders, clinical and research efforts in this area should receive high priority within the health budget.     

Diminished levels of insulin-like growth factor-I in lungs in streptozotocin-induced diabetes: relation to nutritional status and growth

It is yet unknown whether the impaired nutritional status of streptozotocin-induced diabetic rats influences changes in levels of insulin-like growth factor-I (IGF-I) in this experimental model of diabetes. To explore this possibility, simultaneous studies were undertaken of rats made diabetic by streptozotocin (75 mg/kg body wt, intraperitoneally) and undernourished control rats with similar somatic growth rate (determined by body weight gain), in comparison with normal controls. Serum IGF-I levels were diminished in the untreated diabetic and undernourished control animals, but more so in the diabetic group. Lung IGF-I levels (per lung and per lung DNA) and DNA contents were diminished to similar degrees in the untreated diabetic animals and the undernourished control group. Lung dry weights of the diabetic rats were greater than those of the undernourished control group, such that lung IGF-I/100 mg tissue dry wt in the former was significantly lower than in the latter group. Insulin treatment of the diabetic rats restored their body weights, serum and lung IGF-I levels, and DNA contents to normal control values. Lung IGF-I levels in the diabetic rats correlated strongly with serum glucose (r = .75) and body weight (r = .79), and moderately with lung weight (r = .43) and lung DNA (r = .58). These findings suggest that the diminished lung IGF-I levels in streptozotocin-induced diabetes may be related to the impaired nutritional status and/or somatic growth of the experimental animals, and that this relationship may be responsible, at least in part, for the diminished lung cellular proliferation observed in experimental diabetic animals.