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Biomedical subjects

V Navaratnam

Publications and source records attributed to V Navaratnam.

At least 91 records · Page 5Linked to original sources
PubMed1975

Effects of vagotomy on the distribution of cholinesterases in the cat medulla oblongata.

Histochemical study of the distribution of cholinesterases in the cat medulla oblongata reveals that all neurones in the dorsal motor nucleus of the vagus (DMV) contain true cholinesterase (AChE) but, while most contain this enzyme alone, a small proportion of cells contain pseudocholinesterase (BuChE) as well. Cervical vagotomy affects the two types of cell to different degrees of severity. The BuChE-containing neurones lose their enzyme completely within 2-3 weeks and they atrophy and disappear as a result of the operation. On the other hand, the reaction is less severe and is reversible in those cells containing AChE only. Vagotomy also causes reduction of AChE and BuChE staining in the nearby area subpostrema; the depletion here is pronounced at 2-3 weeks and recovery occurs within the year. These findings suggest that some cells in the area subpostrema project peripherally via the vagus and that the area is part of the vagal nuclear complex. Moreover, capilllaries in the area contain AChE and BuChE in the endothelial lining and this is one of the few areas of the cat hindbrain to exhibit such vascular enzyme activity. The ependyma of the area postrema, which overlies the area subpostrema, is heavily stained for BuChE but this is unaffected by vagotomy.

Animals↗
PubMed1974

The effect of phase-shift on the passive avoidance response in rats and the modifying action of chlordiazepoxide.

1 In rats trained to a 12 h light-12 h dark cycle, advancing the phase by 6 h produced a resynchronization of the 24 h variation in passive avoidance response (PAR) which was completed after 10 days.2 The attainment of the new steady state was preceded by a period of disruption which was greatest 5 days after phase-shift.3 The presence of chlordiazepoxide (62.5-500 mug/ml) in the drinking water during the days after phase-shift produced a dose-dependent lessening of the disruptive effect of phase-shift, and a more rapid adaptation to the new light-dark cycle.

Animals↗
PubMedDate not supplied

Chemosuppression of malaria by the triple combination mefloquine/sulfadoxine/pyrimethamine: a field trial in an endemic area in Malaysia.

Malaria, particularly that due to chloroquine-resistant Plasmodium falciparum, which requires management with antimalarial drugs capable of protecting against multiresistant strains, has emerged in Malaysia. A study was carried out to assess the efficacy and tolerability of 2 dosages of mefloquine/sulfadoxine/pyrimethamine (MSP; RO 13-5112) compared to Fansidar in a malaria endemic area. 914 subjects in 3 random groups were studied. Occurrence of malaria was assessed both clinically as well as by blood films. Plasma drug levels were also measured. The results showed that the low dose of MSP was completely effective in suppressing parasitaemia. 2.7% of the study population reported adverse drug reactions, the lowest incidence being in subjects on the low dose; their blood chemical profiles were also the least affected. The plasma levels of pyrimethamine and sulfadoxine achieved in the low dose group were slightly higher than expected, but there was no significant difference in bioavailability. The study showed that, for chemoprophylaxis, a low dose of MSP provided effective protection with minimal side effects.

Animals↗
PubMedDate not supplied

Plasmodium falciparum: increased proportion of severe resistance (RII and RIII) to chloroquine and high rate of resistance to sulfadoxine-pyrimethamine in Peninsular Malaysia after two decades.

Uncomplicated falciparum malaria patients were randomly assigned to receive either 25 mg/kg chloroquine (CHL) over 3 d or a statim dose of 25 mg/kg sulfadoxine (SDX) plus 1.25 mg/kg pyrimethamine (PYR). Patients were followed up for 28 d and the parasite response graded according to World Health Organization criteria. Overall resistance to CHL was 63.3% and 47.4% to SDX/PYR. RI, RII and RIII rates were 9.1%, 42.4% and 12.1% for CHL and 10.5%, 21.1% and 15.8% for SDX/PYR, respectively. Degree and rates of resistance to CHL were significantly correlated with pre-treatment parasite density, but not those to SDX/PYR. Plasma CHL and SDX/PYR levels were within the reported ranges and were not significantly different in patients with sensitive and resistant responses.

Adolescent↗
PubMedDate not supplied

A study on socio-medical variables of drug-dependent persons volunteering for treatment in Penang, Malaysia.

There has been a rapid increase in the past five years in the numbers of hospitalized drug dependents. While the studied population was clearly unrepresentative of the country-wide drug using population, it illustrates how the problem is neither limited to one particular stratum of society, nor to the few "traditional" drugs. Indeed, an increasingly youthful group of individuals drawn from all backgrounds is not only becoming dependent upon opiates, but is also using a range of other drugs, all of which are available on the market at relatively low cost. The market prices of drugs have an effect on the pattern of drug use; and many individuals move directly from tobacco to heroin smoking. Drug abuse continues to be a considerable public and governmental concern, and enforcement and treatment programmes are rapidly expanding in attempts to resolve this problem.

Adolescent↗