Evaluation of haloperidol--ketamine mixture (1:1) anaesthesia in dogs.

Four clinically healthy dogs of either sex, aged 3-5 years, weighing between 9 and 18 kg and maintained under uniform management conditions, were administered haloperidol (5 mg/ml) and ketamine (50 mg/ml) intravenously in 1:1 ratio until the pedal reflex was lost. The calculated doses of haloperidol and ketamine were 1.71 and 17.05 mg/kg body weight intravenously, respectively. Corneal and palpebral reflexes were maintained although pain reflexes were absent up to 20 min of the cocktail administration. The induction of anaesthesia was quick and smooth. There was moderate to good muscle relaxation and analgesia. Mean arterial and central venous pressures and tidal volume decreased significantly (P < 0.05) from baseline values. Significant tachycardia and hyperglycemia were observed.

Phase-IV multicentre clinical study of risperidone in the treatment of outpatients with schizophrenia. The RIS-CAN-3 Study Group.

OBJECTIVE: Since most clinical trials of atypical antipsychotics have been conducted in hospitalized patients, a Phase-IV, multicentre, 8-week, open-label, flexible-dose study was performed to assess the efficacy and safety of risperidone in outpatients with schizophrenia. METHOD: Three hundred and thirty patients with a Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) diagnosis of schizophrenia were enrolled at 61 Canadian sites. Upon trial entry, the patients had their neuroleptic and antiparkinsonian drugs discontinued, and treatment with risperidone was initiated at a dose of 2 mg daily, then increased by 2 mg daily on each of the 2 following days until the initial target dose of 6 mg daily was reached on day 3. No further titration was allowed until day 14, after which the dose could be increased or decreased. RESULTS: During the stabilization phase (days 14-56), the dose was unchanged in 44% of the patients, increased in 24%, decreased in 23%, and titrated both up and down in 9% of the patients. In the efficacy-evaluable population (n = 292), treatment with risperidone produced substantial (-26.4) and significant (P = 0.0001) improvement in the total Positive and Negative Syndrome Scale (PANSS) score. At the end of the study (week 8), 85% of patients were classified as clinically improved according to an a priori definition (that is, 20% or more decrease from baseline in total PANSS score). On their last study visit, 75% of patients reported their experience with risperidone as better than their previous neuroleptic therapy. Risperidone was generally well tolerated. The adverse events reported by more than 5% of the patients were insomnia, nausea, headache, somnolence, dizziness, fatigue, anxiety, vomiting, and ejaculation disorder. Seventy-four percent of the reported treatment-related adverse events were recorded during the first 2 weeks of the trial, possibly because of the discontinuation of prior neuroleptic and antiparkinsonian drugs followed by immediate upward titration of risperidone. However, only 8.5% of adverse events were reported to have occurred during week 3, and only 0.8% of adverse events were reported for week 8. Risperidone treatment produced significant improvements over baseline in the incidence and severity of extrapyramidal symptoms (EPS). A slight but statistically significant increase in body weight was observed. CONCLUSIONS: The results of this open-label, Phase-IV trial in a large population of outpatients with schizophrenia found that risperidone was superior to the neuroleptics that patients had previously taken in terms of efficacy and severity of EPS. Our results suggest the use of risperidone at lower doses in outpatients with schizophrenia.

The impact of permethrin impregnated bednets on the malaria vector Anopheles maculatus (Diptera: Culicidae) in aboriginal villages of Pos Betau Pahang, Malaysia.

The effect of permethrin impregnated bednets on Anopheles maculatus Theobald was studied in four villages in Pos Betau, Pahang, Malaysia from August 1990 to July 1992. Collections of mosquitos were carried out indoors and outdoors from 1900 to 0700 hours. All mosquitos were dissected for sporozoites and parity. In May 1991 two villages received bednets impregnated with permethrin at 0.5 g/m2 and two villages received placebo bednets. There was a significant difference in the sporozoite and parous rates between the treated and control villages after the distribution of bednets (p < 0.05). There was no significant difference in the bites/man/night of An. maculatus between the pre and post treatment periods in the control villages. However there was a significant difference in bites/man/night between pre and post treatment in the treated villages (p < 0.001).

Studies on Japanese encephalitis vector mosquitoes in Selangor, Malaysia.

Mosquito collections were carried out from May to June 1992 and from September to December 1992 in an area where a case of Japanese encephalitis was confirmed. A total of 40,072 mosquitoes belonging to 35 species and 8 genera were collected. The dominant species in that locality were Culex vishnui, Culex tritaeniorhynchus, Culex pseudovishnui, Culex gelidus, Aedes butleri, and Mansonia uniformis.

Residual activity of cyhalothrin 20% EC on cattle as determined by mosquito bioassays.

The residual effectiveness of 0.005mg/ml of cyhalothrin applied to cattle was determined against three species of mosquitos: Anopheles maculatus Theobald. Anopheles dirus Peyton and Harrison Mansonia uniformis Theobald. Twenty-four hour post exposure mortality and the degree of successful blood engorgement were determined by exposing mosquitos for 10 minutes to cattle. Three replicated assays were conducted and mortality determined at 1, 2, 7, 14 and 21 days after each treatment. An initial mortality of 92-94% for An. dirus and Ma. uniformis and 79% for An. maculatus was obtained. Percentage mortality declined to 10%, 18% and 31% for An. maculatus, An. dirus and Ma. uniformis respectively on day 7 post application. On day 21 post application, percentage mortality was 2-3% for the three species of mosquitos.

Studies on the effect of lambdacyhalothrin on Anopheles maculatus Theobald and its response to residual spraying at Jeram Kedah, Negeri Sembilan, Malaysia.

A field trial was carried out to study the effect of lambdacyhalothrin on Anopheles maculatus in trap huts in Jeram Kedah, Negeri Sembilan, Malaysia. Two trap huts were built, of which one was sprayed with lambdacyhalothrin at a dosage of 25 mg ai/m2 and the other served as control. Eight collectors commenced collecting mosquitos from 1900 to 2400 hours, two each indoors and outdoors. Bioassay was also carried out in the treated and control huts to determine susceptibility of adult mosquitos to lambdacyhalothrin. In the treated hut more mosquitos were present during the pre- spraying period. Lambdacyhalothrin gave a mortality of 100% against An. maculatus for 8 months.

Studies on the effect of translocation of chemical insecticides in Eicchornia host plant on Mansonia mosquitos--a potential control method.

A novel method for the control of Mansonia larvae was developed and tested. In this method, foliar absorption and translocation of a chemical insecticide, monocrotophos, a known systemic insecticide was studied in the Eicchornia plant. Acetone solution of the insecticide was painted onto leaves of the plant. At daily intervals, stems were severed and divided into equal sections which were introduced into bowls. Larvae of Aedes aegypti were tested for the presence of monocrotophos. It was found that translocation of the insecticide occurred at different rates in the stems and in some plants the chemical was also released into the surrounding water. Based on these results, 2 insecticides namely, monocrotophos and temephos were painted onto leaves of the host plant and their translocation to the root and water environment was examined by testing with Mansonia and Aedes aegypti larvae. The results again confirmed the translocation process and it was found that the insecticides were secreted into the surrounding water, thereby killing the larvae. However, in leaves painted with permethrin (synthetic pyrethroid) or flufenoxuron (chitin synthesis inhibitor), such a process was not detected. The potential of this new concept in Mansonia larval control is examined.

Determination of insecticide susceptibility in Culex quinquefasciatus Say adults by rapid enzyme microassays.

Rapid enzyme microassays for the detection of resistance due to organophosphate and carbamate in individual field-collected strains of Culex quinquefasciatus adults were conducted. These tests allowed accurate differentiation by eye, on the basis of color changes of susceptible and resistant individuals. Two separate tests were conducted for the biochemical assays. In the insensitive acetylcholinesterase (AChE) test, acetylthiocholine iodide (ACTH) and 5,5-dithiobis-(2-nitrobenzoic acid) (DTNB) were used as substrate and coupling agent respectively. The resulting yellow chromophore indicated AChE activity. Test results showed that the color intensity decreased as increasing concentrations of propoxur were added, thereby confirming the susceptibility of the enzyme to inhibitor. Assay of non-specific esterase however, indicated elevated levels which were correlated with degree of malathion resistance. Electrophoretic data revealed the presence of 2 esterase bands in all strains. It was concluded that such a pattern was not contributory to malathion resistance in adults.

Long-term efficacy of single-dose mass treatment with diethylcarbamazine citrate against diurnally subperiodic Wuchereria bancrofti: eight years' experience in Samoa.

A single-dose of diethylcarbamazine citrate (DEC, 6 mg per kg body weight) was administered in three mass treatment campaigns to > 80% of the estimated total Samoan population (160,000) in 1982, 1983, and 1986. The effect of the drug was evaluated before and after each campaign by conducting four blood surveys covering 9600 to 13,700 people from 26-34 villages on each occasion. The drug reduced the prevalence of Wuchereria bancrofti microfilariae from 5.6% to 2.5% (a 55% reduction), while the transmission potential (the estimated mosquito infection rate if everyone is equally exposed to mosquito bites) dropped from 2.18 to 0.67 (a 70% reduction). The total number of microfilariae in the Samoan population is estimated to have been reduced by 80%. A spaced, single-dose treatment with DEC at a 1-2-year interval therefore seems to be an effective control measure against diurnally subperiodic W. bancrofti.

Chemotherapy and chemoprophylaxis of Angiostrongylus malaysiensis infection in rats with levamisole and mebendazole.

The chemoprophylactic and chemotherapeutic effects of levamisole and mebendazole on Angiostrongylus malaysiensis infection in rats were studied. Both drugs were ineffective in preventing infection while the post-infection treatment showed 100% efficacy. Furthermore, levamisole and mebendazole when given in combination appeared to have an antagonistic effect.

Seasonal prevalence of the helminth fauna of the wood rat Rattus tiomanicus (Miller) in West Malaysia.

A helminthological examination of 367 wood rats, Rattus tiomanicus, in an oil-palm. estate 24 miles north of Kuala Lumpur conducted during 1973 revealed 8 species of helminths: 5 nematodes. Angiostrongylus malaysiensis (54.2% of the rats infected), Hepatojarakus malayae (48.5%), Nippostrongylus braziliensis (48.0%), Gongylonema neoplasticum (0.3%), Syphacia muris (17.7%); 3 cestodes, Hymenolepis diminuta (6.0%), Hymenolepis nana (7.6%), Hydatigera taeniaeformis (cysticercus) (12.0%) and 1 pentastomid, Armillifer sp. (nymph) (0.8%). Overall helminthic infection rates seemed to be higher than those previously reported in this host species.