Possible mechanisms of action of the compounds injected intralesionally in the treatment of cutaneous leishmaniasis, in addition to their direct effects on the parasites.

By injecting uninfected rabbits intradermally with one of the test compounds or the isotonic saline (0.9% NaCl) used as a control, the possible mechanisms of the indirect action of some drugs used intralesionally in the treatment of human cutaneous leishmaniasis [sodium stibogluconate, 2% zinc sulphate, and hypertonic (7% NaCL) saline] were explored. The 24 injected rabbits (six for the control and six for each test compound) were followed up for 30 days, both macroscopically, with checks for erythema and increases in skin thickness, and microscopically, with the histopathological examination of sections of biopsies from the injection sites. Although the microscopy revealed inflammatory-cell infiltration, beginning with eosinophils, followed by lymphocytes and finally by the proliferation of fibroblasts, at all of the injection sites, these changes were most intense with the sodium stibogluconate and 2% zinc sulphate, less marked with the hypertonic saline, and minimal and relatively short-lived with the isotonic saline. Presumably as a result of their metal content, sodium stibogluconate and zinc sulphate each probably induce tissue damage and, subsequently, severe inflammatory changes. The antileishmanial activity of hypertonic saline, however, may be entirely attributable to its osmotic effects.

The mechanism behind the antileishmanial effect of zinc sulphate. II. Effects on the enzymes of the parasites.

When used in vitro, zinc sulphate has a direct antileishmanial effect. To see if this effect involved the inhibition of the parasites' enzymes, extracts of the promastigotes and axenic amastigotes of Leishmania major (MHOM/IQ/93/MRC6) and L. tropica (MHOM/IQ/93/MRC2) were prepared. Zinc sulphate, at various concentrations, was then added to samples of these extracts before the activities, in the samples, of certain key enzymes of the Embden-Meyerhof pathway, hexose-monophosphate shunt and citric-acid cycle, and of two enzymes associated with virulence (protease and acid phosphatase), were determined. The zinc was found to inhibit every enzyme investigated, usually in a dose-dependent manner. Thus the direct antileishmanial effect of zinc may result, partially or entirely, from the inhibition of enzymes that are necessary for the parasites' carbohydrate metabolism and virulence.

The mechanism behind the antileishmanial effect of zinc sulphate. I. An in-vitro study.

In an attempt to determine the possible mechanism(s) behind the antileishmanial activity of zinc sulphate, promastigotes, axenic amastigotes and intracellular amastigotes of both Leishmania major and L. tropica were incubated with different concentrations of the compound. For each of the two Leishmania species, all three forms were found to be inhibited by the zinc sulphate, in a dose-dependent manner, the promastigotes being the most resistant form, followed by the axenic amastigotes. These results indicate that zinc sulphate has a direct antileishmanial effect. Compared with macrophages from starch-treated mice, the macrophages recovered from mice that had been injected intraperitoneally with zinc sulphate (daily for the 4 days prior to the macrophage collection) or BCG (once, 4 days before the cell collection) showed increased phagocytosis and increased killing of L. major and L. tropica. As the effects of the zinc sulphate were not statistically different from those of the known immunomodulating agent BCG, zinc sulphate appears to have an immunomodulating effect, in addition to its direct antileishmanial effect.

Acetylator phenotype in Iraqi patients with systemic lupus erythematosus.

The study was designed to determine the acetylator status in patients with systemic lupus erythematosus (SLE) and compare it to a matched group of healthy volunteers. Disease severity was determined using the revised American College of Rheumatology criteria for classification and the SLE disease activity index. After an overnight fast, each participant received a single oral dose of 100 mg dapsone. After 3 hours, plasma dapsone/monoacetyldapsone ratio was determined. In the control group, frequency of slow acetylators was 73.3%; frequency of rapid acetylators was 26.7%. In SLE patients, frequency of slow acetylators was 78.0%; frequency of rapid acetylators was 12.0%. However, 8.0% were non-acetylators (monoacetyldapsone not detected in plasma). There was no association between acetylator status and severity of SLE.

Acetylator phenotype in Iraqi patients with systemic lupus erythematosus

The study was designed to determine the acetylator status in patients with systemic lupus erythematosus [SLE] and compare it to a matched group of healthy volunteers. Disease severity was determined using the revised American College of Rheumatology criteria for classification and the SLE disease activity index. After an overnight fast, each participant received a single oral dose of 100 mg dapsone. After 3 hours, plasma dapsone/monoacetyldapsone ratio was determined. In the control group, frequency of slow acetylators was 73.3%; frequency of rapid acetylators was 26.7%. In SLE patients, frequency of slow acetylators was 78.0%; frequency of rapid acetylators was 12.0%. However, 8.0% were non-acetylators [monoacetyldapsone not detected in plasma]. There was no association between acetylator status and severity of SLE

Benzodiazepines protect against ethanol-induced gastric mucosal damage in vitro.

The protective effects of drugs acting at the benzodiazepine receptors against ethanol-induced gastric damage were investigated using a newly developed in vitro model of the ethanol-induced gastric damage. The rat stomachs were isolated from the whole animal and kept in Kreb's solution at 37 degrees C. Gastric damage was induced by administration of 1 mL of 50% V/V ethanol into the isolated rat stomach. Administration of the benzodiazepine agonist, clonazepam (25, 50, 100 microg), or the partial benzodiazepine inverse agonist Ro15-4513 (50 or 100 microg), significantly protected against ethanol-induced gastric damage when these agents were administered 15 min before ethanol. The protective effects of these drugs were blocked by the benzodiazepine receptor antagonist flumazenil (200-400 microg). Flumazenil alone was found to aggravate ethanol-induced gastric damage (200-400 microg). The results of this study give evidence for the involvement of central-type benzodiazepine receptors located in the stomach in the protective action of benzodiazepines against ethanol-induced gastric damage.

Oral zinc sulphate in the treatment of acute cutaneous leishmaniasis.

A clinical trial to evaluate the efficiency of oral zinc sulphate in the treatment of cutaneous leishmaniasis was conducted. One-hundred and four patients with parasitologically proven cutaneous leishmaniasis were included in the trial. Patients were assigned randomly to receive 2.5, 5 or 10 mg/kg of zinc sulphate orally, and a control group of patients did not receive any treatment. All patients were followed up for 45 days. At the end of the follow-up period, lesions were assessed and parasitological proof of cure or otherwise was sought. Results showed that the cure rate for the 2.5 mg/kg group was 83.9%, for the 5 mg/kg treatment group it was 93.1% and for the 10 mg/kg treatment group it was 96.9%. No lesions in the control group showed any sign of healing during the follow-up period. Therefore, oral zinc sulphate can be recommended as a very safe therapy for cutaneous leishmaniasis.

Reinfestation in cutaneous leishmaniasis: a new look at predisposing conditions.

OBJECTIVE: A prospective study of cases of reinfestation with cutaneous leishmaniasis is carried out to try to identify if there is any associated condition which might predispose to reinfestation. METHODS: Over a 2 year period, cases of reinfestation with cutaneous leishmaniasis presenting in the Department of Dermatology, were collected. RESULTS: Thirteen cases showing a typical scar with a parasitologically proven new infection were included. The mean age of patients was 54.69+/-2.65 years. The time lapse between the two infections was 52.38+/-2.60 years. The scar of the primary infection was mainly on the face while the lesion was mostly on the limbs. Six patients had diabetes mellitus, one patient was pregnant and three received either oral corticosteroids or other immunosuppressive drug treatment. CONCLUSION: It is concluded that in patients with reinfestation it is important to take a careful medical history and send for a fasting blood glucose, as there is a chance of one in two that the patient may be diabetic.

A new in vitro model for ethanol-induced gastric mucosal damage.

A new in vitro model for ethanol-induced gastric damage is described. The stomach was dissected from the rat, a polyethylene cannula introduced into the remnants of the esophagus, and the pyloric end tied off. With the cardiac and pyloric regions of the stomach secured by thread to a vertical glass rod or tube, the whole was suspended in an organ bath containing aerated Krebs solution. Fifteen minutes later, ethanol was introduced via the esophageal cannula. After an additional 60 min, the stomach was removed from the Krebs solution, opened along the mid line, and the lesions studied. Comparisons were made with a conventional in vivo model. Results show that the lesion number, length, and total lesion area obtained by the in vitro model were comparable to those obtained in the older in vivo model. Histopathologically, lesions induced by both models were also comparable. Clonazepam, a drug previously used in the in vivo model, was tested in this model. Results indicate that clonazpam protected against ethanol-induced gastric damage in vitro. The new model provides a method to study the action of drugs on the stomach alone and to exclude in indirect actions of drugs via other sites in the body.

Zinc sulphate in the treatment of cutaneous leishmaniasis: an in vitro and animal study.

This study was designed to evaluate the effectiveness of zinc sulphate both in vitro and in an animal model against both strains of old world cutaneous leishmaniasis. The in vitro sensitivities of promastigotes and axenic amastigotes of both Leishmania major and L. tropica to zinc sulphate was determined, the LD50 calculated and compared to the standard treatment for cutaneous leishmaniasis pentavalent antimony compounds. The results show that the two forms of both strains were sensitive to zinc sulphate and their respective LD50 were lower compared to the pentavalent antimony compound. Furthermore the sensitivities of the forms of both strains were tested using a simple slide method and compared to results of the standard method. To confirm this result, zinc sulphate was administered orally to mice infected with cutaneous leishmaniasis both therapeutically and prophylactically. Results showed that oral zinc sulphate was effective in both treatment and prophylaxis for cutaneous leishmaniasis. These results encourage the use of oral zinc sulphate in the treatment of cutaneous leishmaniasis clinically.

A comparative controlled trial of intralesionally-administered zinc sulphate, hypertonic sodium chloride and pentavalent antimony compound against acute cutaneous leishmaniasis.

A comparative clinical trial between two newly introduced intralesional treatments for acute leishmaniasis and the established treatment of intralesionally-administered pentavalent antimony compounds was performed. Treatments were allocated randomly to a total of 63 patients who received 2% zinc sulphate, 7% sodium chloride solutions or sodium stibogluconate intralesionally. A number of patients were left without treatment as controls. Patients were followed-up for 45 days, the results showing that the three treatments gave comparable cure rates by the end of the follow-up period. However, zinc sulphate gave a high cure rate (94.8%) usually with a single injection.

Role of endorphins in benzodiazepine-induced hyperglycaemia in mice.

The possibility that benzodiazepine-induced hyperglycaemia is mediated through the release of endogenous endorphins was tested. The results show that naloxone, the opiate antagonist, potentiated clonazepam-induced hyperglycaemia. Treatment with increasing doses of morphine for six days, which induced tolerance to endorphins, did not affect clonazepam-induced hyperglycaemia. The results indicate that endorphins do not mediate benzodiazepine-induced hyperglycaemia.

Prevention of ethanol-induced gastric damage by the imidazobenzodiazepines Ro 15-4513 and Ro 15-3505 in rats.

The protective effects of the imidazobenzodiazepines Ro 15-4513 and Ro 15-3505 against ethanol-induced gastric damage were investigated. Gastric lesions were induced in rats by the oral administration of 1 ml of absolute ethanol. Ro 15-4513 (2.5-10 mg/kg, IP) or Ro 15-3505 (5-20 mg/kg, IP), administered 30 min before ethanol, protected against ethanol-induced gastric damage. The protective effects of these compounds were blocked by the benzodiazepine antagonist, flumazenil (10 mg/kg, IP). These results present evidence for the involvement of the GABA-benzodiazepine receptor complex in the pathogenesis of ethanol-induced gastric damage.

Protection against ethanol-induced gastric damage by drugs acting at the GABA-benzodiazepine receptor complex.

The protective effects of drugs acting at the GABA-benzodiazepine receptor complex against ethanol-induced gastric damage in rats were investigated. Gastric lesions were induced by administration of 1 ml absolute ethanol orally to rats. Administration of clonazepam (0.625-2.5 mg/kg, IP), which binds with high affinity to the benzodiazepine binding site of the GABA-benzodiazepine receptor complex, or Ro 5-3663 (2.5 or 5 mg/kg), which binds to the piorotoxinin site of the receptor complex, protected against ethanol-induced gastric damage. The protective effect of clonazepam (1.25 mg/kg, IP) against ethanol-induced gastric damage was reversed, dose dependently, by the specific benzodiazepine antagonist, flumazenil (5-20 mg/kg, IP). This protective effect of clonazepam or Ro 5-3663 seems to be specific to ethanol-induced gastric damage, since neither drug protected against indomethacin-induced gastric damage. These results present for the first time evidence of the involvement of drugs acting at GABA-benzodiazepine receptors in protection against ethanol-induced gastric damage.

Effect of CGS 9896 on stress-induced gastric ulcer in rat.

1. The effects of CGS 9896, a partial benzodiazepine agonist, and chlordiazepoxide, a full benzodiazepine agonist, on stress-induced gastric ulcers as well as blood glucose were compared. 2. Ulceration in the glandular stomach was induced by 2 h restraint at 4 degrees C. 3. CGS 9896 reduced significantly the ulcer parameters but did not affect blood glucose. The effect of CGS 9896 was dose-dependently blocked by the benzodiazepine antagonist flumazepil. 4. Chlordiazepoxide reduced the ulcer parameters but increased blood glucose. 5. Since CGS 9896 lacks sedative effects but reduced ulcer parameters, the anti-ulcer and sedative effects of drugs acting at benzodiazepine receptors are disassociated. 6. Benzodiazepine-induced hyperglycaemia does not play a major role in the anti-ulcer effects.

Effect of some drugs acting at the central-type benzodiazepine receptors on blood glucose in mice.

1. The effects of some drugs acting at the central-type benzodiazepines receptors on blood glucose levels in mice were studied. 2. Clonazepam, injected intraperitoneally in doses of 0.625-5 mg, produced a dose-dependent increase in blood glucose 30 min after administration. 3. The hyperglycaemic effect of clonazepam (2.5 mg/kg, i.p.) was dose-dependently reduced by Ro 15-1788 (10-40 mg/kg, i.v.), a benzodiazepine antagonist. 4. Ro 5-3663, a GABA antagonist which may act at the picrotoxinin site, produced a significant increase in blood glucose (5 or 10 mg/kg, i.p.); however, when given together with clonazepam (2.5 mg/kg, i.p.) attenuation of the hyperglycaemic effect was observed. 5. Pk 8165, a partial agonist, lacked an effect on blood glucose over the dose range of 5-20 mg/kg, i.p. but caused a slight increase in blood glucose in a dose of 40 mg/kg, i.p.

Effect of dipyridamole on blood glucose and liver cyclic AMP levels and platelet count during endotoxaemia in mice.

1. Blood glucose, liver cyclic AMP (cAMP) levels, and platelet count were studied at different times during a 12 h interval after intravenous (i.v.) endotoxin injection (40 mg/kg) in mice. 2. Blood glucose and liver cAMP levels showed a progressive decrease in endotoxic mice and the decrease was significant after 8 and 12 h. 3. Dipyridamole (50 mg/kg) administered intraperitoneally (i.p.) 7 h post-endotoxin improved blood glucose and liver cAMP levels. 4. Platelet counts were decreased after 1 h in endotoxic mice and remained decreased up to 8 h. Dipyridamole administered soon after endotoxin improved platelet counts in endotoxic mice and increased survival rate to 100%.