L-arginine partially reverses established adrenocorticotrophin-induced hypertension and nitric oxide deficiency in the rat

BACKGROUND: L-arginine treatment prevents adrenocorticotrophin (ACTH) induced hypertension in the rat. This study examined whether L-arginine treatment could reverse established ACTH hypertension and its effects on markers of decreased NO activity. METHODS: Sixty-four male Sprague-Dawley rats were randomly divided into 6 groups given 12 days of treatment: (1) sham (0.9% NaCl, 0.5 ml/kg, subcutaneously, sc, n = 16); (2) ACTH (0.5 mg/kg/day, sc, n = 16); (3) sham + L-arginine (0.6% in food, from treatment day 8 onwards, n = 10); (4) ACTH + L-arginine (n = 10); (5) sham + D-arginine (0.6% in food, from T 8 onwards) (n = 6); and (6) ACTH + D-arginine (n = 6). Systolic blood pressure, water intake, urine volume, and body weight were measured every second day. At the end of the experiments, plasma and urinary nitrate/nitrite (NOx), plasma amino acid concentrations (in groups 1-4), and urinary cyclic guanosine monophosphate (cGMP) concentrations were measured. RESULTS: Sham, sham + L-arginine, and sham + D-arginine treatments did not affect blood pressure. ACTH increased systolic blood pressure (from 121 +/- 1 to 147 +/- 2 mmHg, p < 0.001, pooled control vs treatment day 12, mean +/- sem), and this was partially reversed by L-arginine (group 4: from 141 +/- 2 on day 8 to 133 +/- 1 mmHg on day 12, n = 10, p < 0.001). In contrast, D-arginine did not affect blood pressure in ACTH-treated rats (group 6). ACTH increased water intake and urine volume and decreased body weight, and L-arginine administration did not alter these parameters. ACTH decreased plasma citrulline (group 1 vs 2: 115 +/- 7 vs 67 +/- 6 micro M/L, n = 16, p < 0.001) and NOx concentrations (group 1 vs 2: 8.3 +/- 0.8 vs 4.5 +/- 0.6 microM/L, n= 10, p < 0.001) and these decreases were reversed by L-arginine treatment (group 4: citrulline 98 +/- 9 micro M/L, NOx 9.1 +/- 1.6 micro M/L, group 2 vs 4, both p < 0.05). ACTH produced marked increases in urinary cGMP excretion (group 1 vs 2: 0.5 +/- 0.1 vs 1.9 +/- 0.4 nmol/24 h, p < 0.01). CONCLUSION: Supplementation with L-arginine partly reversed established ACTH-induced hypertension and restored plasma NOx and citrulline concentrations to levels seen in sham-treated rats. These data are consistent with previous studies suggesting that functional NO deficiency has a role in ACTH-induced hypertension in rats.     

Zonal differentiation in the rat adrenal cortex

The factors that establish and maintain adrenocortical zonation are poorly understood. The capsular adrenal gland of the rat has been shown to develop into a functionally zoned tissue in autotransplanted glands in vivo. To examine this in vitro, capsular gland preparations (largely glomerulosa (zg) with some fasciculata (zf) were cultured in vitro in Eagles MEM (3.6mM K+) for 14 days. Zonal differentiation was determined by immunocytochemical localisation of inner zone antigen (IZA, zf/reticularis specific) and Pref-1 (zg specific). In the absence of further additions these preparations invariably maintained a good zonal arrangement of zg and zf over the whole period, though without significant cellular proliferation. Neither the daily addition of the stimulants, maximally 8.3mM potassium, 1nM ACTH, or 100nM angiotensin II (AII), or the AII type 1 receptor antagonist losartan (10microM) had any significant effect on the glands intrinsic capacity to maintain zonation in vitro. Aldosterone output declined rapidly under control conditions (3.6mM K+), but was stimulated by AII, or high K+ reaching a maximum after 7 days, and thereafter declined. However at higher K+ conditions (5.6mM) aldosterone was not supported by angiotensin II. Corticosterone secretion increased autonomously after 2 days in 3.6mM K+ then declined. At higher K+ conditions corticosterone rapidly declined. The factors studied had no effect on the inherent property of the adrenal gland to express the zg or zf phenotype. However the functional steroidogenic capacity of the adrenocortical cells was affected in a highly specific and complex manner by the added stimulants.     

Alcohol and HIV: a study among sexually active adults in rural southwest Uganda

OBJECTIVE: To investigate the association between alcohol consumption and HIV sero-positivity in a rural Ugandan population. METHODS: The adult population residing in a cluster of 15 neighbouring villages has been kept under epidemiological surveillance for HIV infection using annual censuses and sero-surveys since 1989. At the eighth annual survey all respondents were asked about their history of alcohol consumption, the sale of alcohol in their household, and other socio-demographic information. After informed consent, blood was drawn for HIV serology. RESULTS: Of the total adult population 3279 (60%) were interviewed; 48% were males; 905 (27%) had not started sexual activity and were excluded from further analysis. Of the remaining 2374, 8% were HIV infected, 57% had ever drunk alcohol, and 4% lived in households where alcohol was sold. Living in a household where alcohol was sold was associated with a history of having ever drunk alcohol (OR 2.9, 95% CI : 1.7-4.8). HIV prevalence among adults living in households selling alcohol was 15% compared with 8% among those living in households not selling alcohol (OR 2.0, 95% CI : 1.1-3.6). Individuals who had ever drunk alcohol experienced an HIV prevalence twice that of those who had never drunk, 10% versus 5% (OR 2.0, 95% CI : 1.5-2.8). This association remained after adjusting for potential confounders including sale of alcohol in the household and Muslim religion (OR 1.8, 95% CI : 1.2-2.7). Only age, marital status and having ever drunk alcohol independently predicted HIV sero-positivity in a logistic regression model. CONCLUSIONS: We have demonstrated an association between a history of alcohol consumption and being HIV sero-positive. This unexplored factor may explain in part the observed lower prevalence of HIV infection among Muslims. Public health campaigns need to stress the relationship between HIV and alcohol.     

Men's attitudes to condoms and female controlled means of protection against HIV and STDs in south-western Uganda

There is widespread demand for the development of female controlled methods of protection against sexually transmitted diseases and HIV. The success of such methods will depend on their acceptability to women and their male partners. Currently, the only form of HIV prevention under women's control is the female condom. This paper reports on men's attitudes to female controlled methods in southwest Uganda. Data were collected in individual interviews with 50 men and 7 focus group discussions with 42 men. The men's attitudes to male condoms, female condoms and female controlled methods of protection generally were characterized by ambiguity and anxiety. Though men liked the male condom because it protects against infection and unwanted pregnancy, they were worried by rumors that it was unreliable. The central theme in the discussions was the anxiety of men about retaining control over their female partners. While men wanted women to be protected, they also wanted to remain in control, at least to some extent, of the means of protection. Once suitable female controlled methods have been identified, it will be necessary to use education and social marketing in a manner that men can be reassured of the positive benefits of these products to them as well as to women.     

An experimental study using sodium salicylate to reduce cochlear changes induced by furosemide

Summary Furosemide is a loop diuretic which has been found to be ototoxic in humans and experimental animals. The ototoxic effects seem to be directed primarily towards the stria vascularis, since its shrinkage and extracellular edema have been observed in correlation with electrophysiologic changes. The present study was designed to examine the interaction of sodium salicylate and furosemide on the cochlear microstructures. Chinchillas weighing 400–600 g were used in all tests performed. The endocochlear potential (EP) was monitored continuously through a microelectrode inserted through the basilar membrane. A control group of animals was injected with 0.5 ml saline intravenously (IV) 30 min before 25 mg/kg furosemide was given. The experimental group of animals was injected with 50 mg/kg sodium salicylate IV 30 min before 25 mg/kg furosemide. The control animals were found to have a mean decrease in EP of 61.1 ±7.0 mV. In contrast, the experimental group had very little alteration of the EP following furosemide injection (18.7±3.9 mV). These findings suggest that sodium salicylate markedly reduces the ototoxic effect of furosemide. This effect may be mediated by an alteration of local or systemic prostaglandin metabolism, or may be due to inhibition of organic acid uptake in the cochlea.     

Physical effects of reuse and repeated ethylene oxide sterilization on transscleral cyclophotocoagulation laser G-probes

PURPOSE: The authors documented the physical effects of reuse and repeated ethylene oxide sterilization on transscleral cyclophotocoagulation laser G-probes. METHODS: Transscleral cyclophotocoagulation was performed using G-probes on fresh porcine eyes. Each of two G-probes was used for four transscleral cyclophotocoagulation procedures, with three cycles of ethylene oxide sterilization in between. The power output from the G-probes was measured by a laser output meter before and after each transscleral cyclophotocoagulation procedure. The G-probes were also examined under a slit lamp for signs of physical damage. RESULTS: Repeated use of the G-probe in transscleral cyclophotocoagulation, with ethylene oxide sterilization in between, resulted in an average decrease of 3% in laser energy delivered per repeated cycle of use up to the fourth cycle. No signs of physical damage were found. CONCLUSIONS: Laser G-probes remain functional after repeated use and ethylene oxide resterilization for up to four cycles. No visible physical damage to the probes was identified. It is safe and cost-effective to reuse G-probe for transscleral cyclophotocoagulation with ethylene oxide sterilization, provided the surgeon stays alert for signs of probe damage. This alertness should be retained regardless of whether new or old G-probes are used.     

Intracameral lidocaine in trabeculectomy. A preliminary safety and efficacy study

PURPOSE: To study the safety and efficacy of intracameral lidocaine as anaesthesia in trabeculectomy for primary open-angle glaucoma. METHODS: Trabeculectomy under intracameral anaesthesia using 1% preservative-free lidocaine was performed in 10 patients with primary open-angle glaucoma. Intraoperative pain score, postoperative intraocular pressure (IOP) and endothelial cell count at 3 months were recorded. RESULTS: The mean pain score was 1.70 +/- 1.34. The mean IOP was lowered from 24.60 +/- 8.28 mmHg preoperatively to 14.1 +/- 3.11 mm Hg postoperatively. There was no significant decrease in the mean endothelial cell count 3 months after the surgery (P = 0.375). CONCLUSION: Intracameral lidocaine may be a safe and effective alternative anaesthesia method in trabeculectomy for uncomplicated primary open-angle glaucoma.     

Incisional surgery for angle closure glaucoma

Angle closure glaucoma remains a major challenge for ophthalmologists. The three main challenges in the treatment of angle closure glaucoma are, firstly, to achieve rapid reduction of intraocular pressure in acute angle closure glaucoma, secondly, to prevent progression to chronic angle closure glaucoma, and thirdly, to manage established chronic angle closure glaucoma. Incisional surgery for angle closure glaucoma is typically required when laser surgery and/or medical therapy fail to control the intraocular pressure or control progressive synechial closure. The role for surgical iridectomy and emergency trabeculectomy in the modern management of acute angle closure glaucoma is diminishing. Trabeculectomy, goniosynechialysis, cyclodestructive procedures, and glaucoma implant are effective surgical options for chronic angle closure glaucoma, but none of them have been shown to be more effective than the others with proper comparative clinical trials. Trabeculectomy and goniosynechialysis are often combined with cataract extraction, which appears to offer additional pressure-control benefits to patients with chronic angle closure glaucoma.