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Biomedical subjects

M Alpers

Publications and source records attributed to M Alpers.

At least 55 records · Page 3Linked to original sources
PubMed1977

Pathogenesis of reovirus type 1 hydrocephalus in mice. Significance of aqueductal changes.

The pathogenesis of hydrocephalus following reovirus type 1 inoculation of neonatal mice has been examined by light microscopy, radiology, immunofluorescence, and electron microscopy. The reovirus infection causes an acute ependymitis and leptomeningitis, followed by a fibrous arachnoiditis and arachnoid villitis. Hydrocephalus develops in proportion to the degree of inflammatory/fibrotic changes within the cerebrospinal fluid pathways. With the beginning of hydrocephalus there is radiographic evidence of basal cistern blockage. As the hydrocephalic state progresses, axial herniation and compression of the midbrain result in the appearance of aqueduct stenosis. We demonstrate that the stenosis of the aqueduct is a secondary phenomenon, not causally related to the pathogenesis of hydrocephalus, and discuss the significance of this finding to human aqueduct stenosis.

Animals↗
PubMedDate not supplied

Malaria: how useful are clinical criteria for improving the diagnosis in a highly endemic area?

To assess the validity of clinical criteria, we investigated 2096 outpatients diagnosed as malaria cases by nurses at a rural health subcentre in a highly endemic area of Papua New Guinea. 73% of the children < 10 years old had a positive blood slide for any species of Plasmodium and 32% had > or = 10,000 P. falciparum parasites per microL. For adults the frequencies were 51% and 9%, respectively. Stepwise logistic regression identified spleen size, no cough, temperature, no chest indrawing, and normal stools as significant predictors for a positive blood slide in children; no cough and normal stools predicted a positive blood slide in adults. Fever, no cough, vomiting, and enlarged spleen were significant predictors for a P. falciparum parasitaemia > or = 10,000/microL in children; in adults the only predictor was vomiting. In children the association of no cough and enlarged spleen had the best predictive value for a positive blood slide, and a temperature > or = 38 degrees C had the best predictive value for a P. falciparum parasitaemia > or = 10,000 microL. In adults, no major symptom had a good predictive value for a positive blood slide but vomiting had the best predictive value for a P. falciparum parasitaemia > or = 10,000/microL. When microscopy is not available, these findings can help in areas of high endemicity to determine which patients with a history of fever are most likely to have malaria and, more importantly, for which patients another diagnosis should be strongly considered.

Adolescent↗
PubMedDate not supplied

Human cerebral malaria: lack of significant association between erythrocyte rosetting and disease severity.

The ability of Plasmodium falciparum isolates from 103 Papua New Guinea children with cerebral malaria and 158 children with uncomplicated malaria to form rosettes in vitro was studied. Of these, 81 isolates from cerebral malaria and 151 isolates from uncomplicated malaria grew to schizogony and were included in the rosetting analysis. Wide variation occurred in the level of rosette formation, with all isolates from both cerebral and uncomplicated malaria patients being able to form rosettes. No statistically significant difference existed between the geometric mean rosetting rate of isolates obtained from cerebral malaria and those from uncomplicated malaria (9% versus 8.6%, P = 0.27). The ability of acute sera to inhibit rosette formation was not significantly different between 18 cerebral malaria cases and 20 controls tested [mean reduction in rosetting rate 6.1% (SD 11.5) versus 8.4% (SD 12.3), P = 0.57]. The rosetting rate of cerebral malaria cases was not associated with the clinical outcome. Among the clinical and laboratory variables tested, only blood group and parasite density were significantly associated with rosetting. These data do not support the hypothesis that rosette formation is associated with cerebral malaria in Papua New Guinea, but indicate that rosetting is an intrinsic property of parasites occurring in all manifestations of the disease.

Adolescent↗
PubMedDate not supplied

The late biting habit of parous Anopheles mosquitoes and pre-bedtime exposure of humans to infective female mosquitoes.

Using the all-night landing catch method (18:00-06:00) we showed, for Anopheles gambiae in Sierra Leone and A. punctulatus in Papua New Guinea, that parous females have a tendency to bite later than nulliparous ones. The biting habit of sporozoite-infected A. punctulatus was also investigated. The sporozoite rates for Plasmodium falciparum and P. vivax were 1.8 and 1.4% respectively, but only one (1.3%) of 76 females infected with P. falciparum was caught between 18:00 and 21:00. A significantly higher proportion (11.6%) of mosquitoes infected with P. vivax was caught in the same period. The late biting habit of mosquitoes infected with P. falciparum is discussed in relation to the differential biting habits of parous and nulliparous females. We conclude with a hypothesis that, in areas where Anopheles mosquitoes have a late-biting cycle and low parous rate, exposure to mosquitoes infected with P. falciparum during the pre-bedtime period (18:00-22:00) is very low. This hypothesis could explain why insecticide-treated bed nets protect children better in areas of seasonal transmission, where nulliparous females tend to predominate, than in areas of perennial transmission, where parous females are usually more numerous. The same hypothesis is compatible with the finding in Papua New Guinea that insecticide-impregnated bed nets are more protective against P. falciparum than against P. vivax malaria.

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