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Biomedical subjects

J Cohn

Publications and source records attributed to J Cohn.

At least 37 records · Page 2Linked to original sources
PubMed1981

Intact megakaryocytes in the venous blood as a marker for thrombopoiesis.

A total of 110 children, aged 0-15 years, were investigated for circulating megakaryocytes in cubital venous blood using the saponin-haemolysis leucoconcentration technique. The average number of megakaryocytes decreased from 17.8 per ml blood in the first year of life to 5.5 after the 6th year, which is the same value as in adult humans. The intact thrombocytogenic megakaryocyte value decreases from about 40% in the first year of life to only a few percent (less than 5%) after the 10th year, the same value as in adult humans. There was a significantly higher number of megakaryocytes in children aged 0-6 years than in those aged 7-15 years. We concluded that occurrence of intact megakaryocytes greater than or equal to 25% in the venous blood is a sign of a normal thrombopoietic activity in the bone marrow, and the percentage of intact megakaryocytes in cubital venous blood reflects the decrease in thrombopoiesis in the bone marrow of fingers, hands and forearms during childhood. The decline in thrombopoietic activity is concentrated in three periods: 1-3, 6-7, and 10-11 years. An occurrence of intact megakaryocytes greater than 5% in venous blood draining organs or bone marrow is a sign of some thrombopoietic activity.

Adolescent↗
PubMed1981

Noninvasive cardiopulmonary monitoring.

Contrast dilution curves have been utilized for evaluation of hemodynamic function. Noninvasive techniques for this purpose usually have been qualitative, expensive, and cumbersome with minimal applicability to the newborn infant. The technique of roentgen densitometry has been utilized to screen children with heart murmurs. Characteristic curve patterns were identified for normal subjects and for patients with shunts with correlation to catheterization data. This technique is now being applied in a quantitative fashion to estimate cardiac output and left-to-right ductal shunts. Cardiac output volumes were inversely proportional to the difference of the second moments of the dilution curves obtained--the second moment being a measurement of the peak dispersion. The estimation of the percent of left-to-right shunt is related to the exponential decay of the left-sided curve.

Absorptiometry, Photon↗
PubMed1980

Persistence of viral hepatitis A and B in an isolated Caucasian population.

The persistence of viral hepatitis A (HAV) and hepatitis B (HBV) in the Faroe Islands, a Caucasian, high sanitary standard, isolated area, was studied by means of notified clinical cases of hepatitis and by specific antibody testing of population samples. Large epidemics of hepatitis occurred on the Faroe Islands in 1928-1930 and 1955-1958, although sporadic cases have been continuously recorded. Presence of antibody to HAV (anti-HAV) was confined to age groups exposed to the epidemics, while antibody to HBV surface antigen (anti-HBs) was demonstrated in all age groups, including children. This study provides further evidence for the concept of HAV as a self-limited infection, unable to maintain itself by chronic virus carriers. HBV, by contrast, again is shown to survive even in small populations with high sanitary conditions and to have no recognizable risk factors.

Adolescent↗
PubMed1980

Asbestos, lead, and the family: household risks.

Although the intrafamilial transmission of infectious diseases has long been recognized, the induction of environmental disease in household contacts is being increasingly documented and requires a higher index of suspicion. An incidental radiographic finding, such as pleural thickening or calcification, or even interstitial pulmonary fibrosis in a young person without obvious occupational exposure to asbestos, should prompt the physician to clarify the parental occupational history. Likewise, unexpected evidence of lead induced abnormalities, such as elevated blood lead and/or erythrocyte protoporphyrin levels, should focus the examiner's attention on possible intrafamilial transmission, treatment, and prevention.

Adult↗
PubMed1979

Glucose-6-phosphate dehydrogenase deficiency in a native Danish family. A new variant.

Deficiency of red cell glucose-6-phosphate dehydrogenase was found in a native Danish family, in which 2 boys suffered from severe haemolytic anaemia. The mother and 3 sisters of the boys were heterozygotes for G-6-PD deficiency. The biochemical investigations indicate that this deficient G-6-PD is very similar to the Mediterranean variant; however, this variant gene may represent another example of G-6-PD 'Helsinki' or an unique variant with properties similar to G-6-PD B(--).

Adult↗
PubMed1977

Bile pigment formation by skin heme oxygenase: studies on the response of the enzyme to heme compounds and tissue injury.

Skin heme oxygenase is locally elevated by stimuli such as tissue injury and injections of whole blood, myoglobin, and hematin. The enzyme activity is also increased at the proximity of the injection site of chemicals such as cobalt and cobalt-protoporphyrin-IX (cobalt-heme). Protoporphyrin-IX, the tetrapyrrole nucleus of type-b heme compounds, was ineffective in altering the enzyme activity in vivo. The developmental pattern of heme oxygenase in skin was compared to that of the enzyme in liver. The enzyme activity in both organs was greatest during the 1st postpartum wk and declined to adult levels after 2 wk. The physiological implications of the increased activity of skin heme oxygenase are discussed, and it is concluded that the activity of the hepatic heme oxygenase system and that of the skin are regulated by the same mechanism.

Animals↗
PubMed1977

Congenital hypomegakaryocytic thrombocytopenia associated with bilateral absence of the radius - the TAR syndrome.

A case of the TAR syndrome is described which presented bilateral absence of the radius and pronounced thrombocytopenia at birth; when seen at the age of 6, growth and development was within normal limits, except for the upper extremities, and no signs of an haemorrhagic diathesis were seen. A careful family study brought 2 additional cases to light: a female second cousin was found to have bilateral absent radius, but no haematological abnormalities when seen at the age of 10. Her younger brother had died at the age of 3 months with severe thrombocytopenia and heavily malformed, flipper-like upper extremities. The broad clinical variation of the syndrome should be kept in mind in genetic studies and counselling.

Abnormalities, Multiple↗
PubMed1977

Hepatitis, type B in haemophiliacs. Relation to the source of clotting factor concentrates.

36 children aged 3 to 18 years receiving substitution therapy for haemophilia during the period 1970 to 1976 were studied for infection with hepatitis B virus by assays for HBsAg, anti-HBs, and anti-HBc. Clinical hepatitis B occurred in 3 patients (8%) and serological evidence of infection was found in further 13 (36%). The occurrence of infection was associated with age but less so with the total amount of transfusion. Estimates of the risk of infection by clotting factor material of different origin indicated a figure of 1:53,000 I.U. for Danish volunteer donor preparations as well as for commercial products, the risk being apparently increased following the use of pooled blood donor material and non-Scandinavian products respectively.

Adolescent↗