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P Jacobs

Publications and source records attributed to P Jacobs.

At least 523 records · Page 29Linked to original sources
PubMed1979

Bone marrow culture in vitro. A technique for analysis and permanent recording of cellular composition.

The in vitro cloning of haematopoietic progenitor cells derived from blood or bone marrow is now an established technique for the study of normal and abnormal blood formation. In semi-solid agar the results are conventionally recorded as the number of clusters or colonies that grow on the plate under controlled culture conditions. However, the demonstration of detailed morphology within these cellular aggregates remains unsatisfactory. Aspiration techniques are cumbersome and invariably disturb cellular relationships within the supporting matrix while supravital staining is limited by variable uptake of dye by the agar. We describe a method in which the entire cell-containing layer is removed from the Petri dish, fixed, and after mounting on a glass-slide, is air-dried. This preparation stains well with a wide variety of biological dyes, is minimally influenced by background colouration of the culture medium and excellent demonstration of morphologic detail is possible. A permanent record of the cellular composition of the culture is easily obtained by mounting the stained agar disc.

Animals↗
PubMed1978

A cytogenetic survey of an institution for the mentally retarded. II. C-band chromosome heteromorphisms.

Heteromorphisms of chromosomes 1, 9, and 16 were studied by C-banding in a population of 403 mentally retarded individuals from diverse ethnic groups. A significant difference in the distribution of heteromorphisms was found among the different racial groups. The Orientals had a larger C-band on chromosome 1 and a smaller C-band on chromosome 9 than the other racial groups while the Caucasians had a larger C-band on chromosome 9. The Oriental group also had a significantly greater proportion of inverted C-bands. No differences were found in the distribution of C-band heteromorphisms among different etiologic categories of mental retardation.

Adult↗
PubMed1978

Inversions and other unusual heteromorphisms detected by C-banding.

Sixteen patients with unusual heteromorphisms involving alterations of the length and/or position of centromeric heterochromatin are described. Family studies showed that the heteromorphisms were present in other relatives and segregated in the expected 1:1 ratio. There was a significantly greater frequency of unusual heteromorphisms among Orientals than in other races studied.

Asian People↗
PubMed1978

Skin necrosis after warfarin therapy.

A rare but potentially lethal complication of coumarin and its congeners is skin necrosis. A case of skin necrosis due to warfarin is reported and the literature is reviewed. It is suggested that if necrosis develops, the coumarin therapy should be terminated, and the patient should immediately be heparinized. Heparin, which never causes necrosis, can be used freely if further anticoagulation therapy is required, and may well prevent necrosis due to the thrombotic process.

Adolescent↗
PubMed1978

A reappraisal of the role of Pityrosporum orbiculare in pityriasis versicolor and the significance of extracellular lipase.

Pityrosporum orbiculare is an obligate lipophilic yeast in vitro, which suggests it possesses an extracellular lipase crucial for nutrition. If present in vivo, the enzyme would enable the yeast to utilize skin surface lipids, which may therfore play an important role in the pathogenesis of pityriasis versicolor. Cultured P. orbiculare and biopsy material from patients with pityriasis versicolor were investigated for the presence of lipase by electron microscope histochemistry. At sites of lipase activity, fatty acid hydrolyzed from Tween 80 substrate reacts with Ca++ ions to form an insoluble Ca++ soap. Exchange of Ca++ with Pb++ enables the sites of lipase activity to be visualized as electron dense deposits of insoluble lead soap. Surface lipase activity was apparent when the technique was applied to P. orbiculare grown on lipid containing medium and its specificity confirmed by removal of substrate and inhibition by di-isopropyl fluorophosphate and quinine hydrochloride, but not by sodium fluoride. When the same technique was applied to stratum corneum infected with Pityrosporum furfur (Malassez), no reaction product could be detected. It is postulated that lipase, although critical for fungal nutrition in vitro, is unlikely to be of importance in vivo. Skin surface lipids are therefore probably not relevant to the pathogenesis of pityriasis versicolor.

Histocytochemistry↗
PubMed1978

Haematology today.

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Acute Disease↗