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Biomedical subjects

M Karam

Publications and source records attributed to M Karam.

49 records · Page 3Linked to original sources
PubMed1985

Seroepidemiological investigations of onchocerciasis in a hyperendemic area of West Africa.

Immunological study of individuals (aged 4 to 70 years) living in an area of Mali hyperendemic for onchocerciasis revealed an 83% prevalence of skin microfilariae (mf). Microfilariae counts from skin snips were highly age-dependent. Screening for concomitant helminth infections showed a low prevalence of hookworms and Mansonella (Dipetalonema) perstans, but neither schistosomiasis nor bancroftian filariasis. Immunological results revealed strong correlation between radioallergosorbent test (RAST) and skin test (5 and 50 ng adult O. volvulus extract), between RAST and total IgE, and between IFAT and ELISA. A negative correlation exists between mf counts and skin tests and between mf counts and RAST; the lowest median values were obtained in the group with high mf counts. Skin sensitizing antibodies were detected in most locally born children aged 4-5 years. Intradermal tests showed a high rate of sensitization to O. volvulus antigen in mf-negative children, whereas ELISA and IFAT values were significantly lower in these children than in mf-positive children. Increasing concentrations of circulating IgE antibodies were found in children aged 4-11 years by RAST, and, in individuals aged 12-19 years (age group for which mf counts sharply increase), skin testing revealed a state of anergy. In long lasting infections (adults greater than 20 years) skin reactivity was comparable to that of young children or was depressed. ELISA and IFAT achieved similar results in each age group.

Adolescent↗
PubMed1985

Preliminary data on the genetic differentiation of Onchocerca volvulus in Africa (Nematoda: Filarioidea).

Data are reported on the genetic structure of three Onchocerca volvulus populations, respectively from Mali (savanna), Ivory Coast (forest), and Zaire (forest gallery in savanna). Electrophoretic analysis, carried out on 25 gene-enzyme systems, has shown a remarkable genetic heterogeneity existing within O.volvulus. Zaire and West Africa populations appear chiefly differentiated at Mdh-1 and 6Pgdh loci, their average Nei's genetic distance being 0.11. In West Africa Nei's D found between the savanna and forest samples is 0.04. The savanna population from Zaire is more similar to the savanna one from Mali (D = 0.09) than to the forest one from Ivory Coast (D = 0.13). This appears mainly due to the loci Ldh and Hbdh (possibly linked), some alleles of which seem to be selected for in forest populations (Ldh110, Hbdh108), while others in the savanna ones (Ldh100, Hbdh100). The hypothesis that the discrepant epidemiological patterns of human onchocerciasis are related to intrinsic differences in the parasite seems supported by the obtained data. The differences in allele frequencies found at the reported loci appear strong enough to allow biochemical identification of O. volvulus populations from different geographic regions and different habitats.

Alleles↗
PubMed1985

Suramin in the treatment of onchocerciasis: the efficacy of low doses on the parasite in an area with vector control.

In a village hyperendemic for onchocerciasis in Burkina Faso, where the vector had been controlled by the Onchocerciasis Control Programme since 1976, 65 patients were treated with doses of 37 to 71 mg/kg suramin in 1979. The viability and fertility of the adult parasites were studied in 217 nodules excised from 42 patients one month to four years after treatment using the collagenase technique. Most of the worms had survived the treatment. Male worms were more susceptible to suramin than female worms. The development of intrauterine stages initially continued, but was completely suppressed after several months. The female worms remained sterile in those patients who had received more than 60 mg/kg suramin. In other ones 11 and 13% of the female worms showed new embryonic stages in the uteri during two follow-up examinations in the second year. In a final examination in 1983 the reproduction had declined again. However, the reproductivity of the superannuated worms had considerably decreased in the untreated patients as well. All patients had shown a very high microfilardermia in 1979. After treatment the microfilarial densities dropped to levels near zero depending on the dose of suramin administered, but in none of the patients was the reduction complete during the first year of the treatment. Microfilariae gradually reappeared in the second year in several patients who had received less than 60 mg/kg suramin. In the final follow-up in 1983 most of the treated patients had become negative in skin counts, although they still harboured viable worms.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Mechanism of decreased left ventricular stroke volume during inspiration in man.

Radionuclide ventriculography was performed in 15 healthy subjects during quiet breathing and during inspiration against a 24 cm H2O threshold load with a respiratory gating technique. Inspiratory threshold loading caused an inspiratory decrease in ejection fraction from 64% to 59% (p less than .001). Stroke counts proportional to stroke volume decreased by 9.6% (p less than .02) due to an increase in end-systolic counts of 15.9% (p less than .05). End-diastolic counts decreased in four subjects and increased in three subjects, but the mean counts did not change significantly. These findings suggest that negative pleural pressure causes an impediment to left ventricular ejection comparable to an increase in arterial pressure. Respiratory gating of radionuclide ventriculography during loaded breathing is suggested as a controlled stress on the ventricle for diagnostic purposes.

Adolescent↗
PubMed1983

General considerations on endemic treponematosis in the rural Sahel region of Upper Volta.

A sero-immunological survey conducted by indirect immunofluorescence technique has made it possible to determine accurately the prevalence and distribution of treponematoses in the Sahel rural region of Upper Volta. The number of carriers of antitreponemal antibodies varies from one place to another, but is particularly high in a nomad community, where prevalence attains 84.2%. The magnitude of endemic foci can also be expressed in terms of maximal titer and geometric mean of antibody titers. The seropositive values increase as a function of age, but sex is not a significant factor as regards prevalence, which would appear to depend essentially on the way of life, habits and promiscuity.

Adolescent↗
PubMed1982

Error in blood-pressure measurement due to incorrect cuff size in obese patients.

Trained nurse-specialists obtained 84 000 blood-pressure measurements in 1240 obese subjects using cuffs of the three standard adult sizes in a randomised order. The differences in readings between the three cuffs were smallest in non-obese subjects and became progressively greater with increasing arm circumference (AC) in the obese population. The regular cuff (12 X 23 cm) showed the greatest bias in relation to AC. Formulae and a table have been derived to correct the measurement error caused by cuffs of inappropriate size at various ACs. The reported high prevalence of hypertension in obese subjects may be greatly overestimated.

Arm↗
PubMedDate not supplied

A DNA sequence specific for forest form Onchocerca volvulus.

Onchocerciasis, or river blindness, is caused by infection with Onchocerca volvulus, a filarial parasite which infects about 40 million people in Africa and Latin America. Epidemiological, clinical, entomological and serological studies of African onchocerciasis led to the hypothesis that Onchocerca volvulus exists in different forms in the forest and savannah. It is uncertain if these differences are due to genetic differences within O. volvulus itself, or to epigenetic factors, such as differences in the host populations. To date no basic biochemical differences between the forest and savannah populations of O. volvulus has been found, although isoenzyme studies have shown that differences in allele frequency between forest and savannah populations exist. Here we describe the isolation of a DNA sequence that seems to be specific for the forest form of O. volvulus, the first indication of a basic genetic difference between the savannah and forest forms.

Base Sequence↗
PubMedDate not supplied

[Effect of the use of drinking water on the pathogenic fecal flora in a Sahel rural region].

Within the scope of a village hydraulic programme, in a Sahel rural area, an investigation was conducted in a school to determine the effect of the use of drinking water on fecal flora. One year following the installation of a hydraulic pump, it was observed that pathogenic salmonellae, shigellae and amoebic cysts had virtually disappeared. In contrast, the perennial character of viral contamination was demonstrated. Water guaranteed potable, therefore, appears to be an essential factor in the prevention of infections due to fecal pathogenic microorganisms. It is essential, however, that the areas surrounding the pumps be subjected to strict supervision to avoid pollution of the underground water sheet.

Adenoviridae↗