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Biomedical subjects

R Haque

Publications and source records attributed to R Haque.

At least 73 records · Page 4Linked to original sources
PubMed1976

The epidemiology and natural history of streptococcal pyoderma: an endemic disease of the rural southern United States.

In order to study the natural history of endemic pyoderma, the host and environmental risk factors to infection, the immunologic response and the risk of acute glomerulonephritis (AGN) a prospective study was done between June 29 and December 13, 1970 in 444 black children aged 2-6 years attending project Headstart centers in Holmes County, Mississippi. The weekly prevalence of pyoderma was about 40-50% during July and August but decreased to 4% during the last week of the study. "Pyoderma-type" serotypes of group A streptococci were isolated from about 70% of the skin lesions and similar serotypes were also commonly isolated from the pharynx. The seasonal prevalence and T and M typing pattern of most of the pharyngeal isolates mirrored the skin isolates. Many of the streptococci appear to belong to previously unrecognized M-types and one strain has been designated provisional M type 67 by the International Subcommittee on Pneumococci and Streptococci. Staphylococci were also isolated commonly from the skin lesions, especially late in their evolution. Despite an 80% incidence of streptococcal pyoderma during the summer months, only 3 children (0.67%) developed AGN; all of these children had clinically mild disease. The risk of a major outbreak of AGN in populations like these is substantial. Surveillance for clusters of AGN is indicated and widespread benzathine penicillin prophylaxis should be used in the event of an outbreak. Also, further research to determine the long term prognosis of clinically mild AGN and to detect useful laboratory markers of nephritogenicity are indicated.

Age Factors↗
PubMed1976

Chemical structure and properties of selected benzene compounds in relation to biological activity.

Four fundamental physical parameters of series of benzene derivatives were studied to ascertain correlations with biological activity. These included octanol/water coefficient, vapor pressure, infrared absorption (out-of-plane C-H vibration), and the pi values. Each physicochemical constant exhibited a partial correlation with biological activity suggesting that each played a role. It was presumed that more precise and specific data on the biological activity would have permitted a better correlation. It is postulated that the biological activity of a compound is due to the sum of such physicochemical factors as: partition coefficient, molecular geometry and spatial orientation, electronic characteristics of the molecular orbitals, and vibrational-rotational frequencies of constituent groups.

Animals↗
PubMed1976

Physicochemical properties of some organophosphates in relation to their chronic toxicity.

Organophosphates in increasing amounts and wider varieties of molecular structure are being used to replace the organochlorine pesticides. It has been assumed that the organophosphates as a class would have a minimal chronic toxicity due to rapid hydrolysis and an unfavorable partitioning as regards to lipids. The physicochemical properties of a number of representative organophosphates were determined, including the octanol/water partition coeffecient, hydrolysis, and binding to proteins. Those having a halogenated aryl substitution were found to have partition coefficients not largely different from the organochlorines, suggesting the possibility of fat deposition. Certain of these compounds are sufficiently stable toward hydrolysis to allow bioaccumulation to occur. These preliminary findings appear to indicate a correlation between readily determined physical properties and the potential for chronic effects in this class of compounds.

Animals↗
PubMed1975

Human pesticide poisonings by a fat-soluble organophosphate insecticide.

In five cases of dichlofenthion poisoning due to suicidal ingestions, unusual toxicologic features were encountered. Initial symptoms were mild or delayed and severe cholinergic crises did not appear until 40 to 48 hours after ingestion. Two patients died, and in the three survivors, cholinesterase symptoms persisted for five to 48 days. An almost total inhibiton of both cholinesterase enzymes continued in one patient for 66 days, and prolonged antidotal therapy was required. Residues of the intact pesticide were detected in fat after 54 days in one patient, and in the blood for 75 days in another patient. The partition coefficient of dichlofenthion in fat was 20 times greater than parathion, and exceeded only by leptophos. Considering the chemical and toxicologic properties of this compound, we postulated that the mechanism of protracted intoxication is a slow release from adipose reservoirs.

Adipose Tissue↗
PubMed1971

Binding of DDT to lecithin.

An interaction between DDT and lecithin is indicated by the reciprocal effects of each compound on the proton magnetic resonance spectrum of the other. The phosphoryl choline moiety of the lecithin and the benzylic proton of the DDT seem to be involved. The most pronounced response in the proton magnetic resonance spectrum of the lecithin produced by increasing concentration s of DDT was a change in the chemical shift of the resonance peak due to the protons of the choline methyl groups. Increasing concentrations of lecithin produced changes in the chemical shift of the resonance peaks of the benzylic proton and adjacent ring protons of the DDT. Equilibrium constant of 0.597 +/-0.015 molal(-1) was obtained for this interaction.

DDT↗