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Biomedical subjects

K L Cohen

Publications and source records attributed to K L Cohen.

At least 73 records · Page 4Linked to original sources
PubMed1979

Effect of phenylephrine on normal and regenerated endothelial cells in cat cornea.

Topical commercial phenylephrine HCl (Neo-Synephrine 10%) has been shown to cause an increase in corneal thickness and reversible vacuolization of corneal endothelial cells in rabbits. Using an in vivo model of regenerated corneal endothelial cells in the cat, we compared the cytotoxicity of phenylephrine-HCl 10% to regenerated and to normal, nonregenerated cells. Following removal of the epithelium, topical application of the drug causes the appearance of anterior and posterior bands of stromal edema and reversible vacuolization in both normal and regenerated endothelial cells. Phenylephrine was not more damaging to the regenerated cells. Polymorphonuclear leukocytes infiltrated between the regenerating cells 24 hr after treatment but did not appear to destroy them. Phenylephrine may therefore be implicated as a causative factor of corneal edema and postoperative inflammation.

Animals↗
PubMed1978

Incidence of pituitary tumors following adrenalectomy. A long-term follow-up study of patients treated for Cushing's disease.

The long-term follow-up of 21 patients who had undergone bilateral adrenalectomy for Cushing's disease has revealed eight definite and two suspected cases of pituitary tumors. The average time from adrenalectomy to the diagnosis of the pituitary tumor was 6 1/2 years, with a range of 1 1/2 to 12 years. The incidence of tumors in this study (38%) is higher than that reported by others and may reflect (1) that none of these patients received pituitary irradiation in addition to adrenalectomy, (2) the length of follow-up, and (3) the high index of suspicion and early diagnosis of pituitary tumors in recent years. These data raise the question of whether bilateral adrenalectomy alone is an acceptable form of therapy for Cushing's disease. For patients treated in this way, a life-long commitment should be made to undergo annual reexamination for the possible occurrence of a pituitary neoplasm.

Adenoma↗
PubMed1978

Contribution of human somatomedin activity to the serum growth requirement of human skin fibroblasts and chick embryo fibroblasts in culture.

Although purified human somatomedins and related peptides have been shown to stimulate growth-related processes in cultured human skin fibroblasts, it is unknown whether the serum macromolecules required for the routine growth of human fibroblasts in culture include the somatomedins. To evaluate this question we have obtained sera from five GH-deficient patients before and after GH treatment and have compared these pre- and post-GH sera for their ability to stimulate [3H]thymidine incorporation into DNA and cell multiplication in the patients' own fibroblasts in culture. Subconfluent human fibroblasts demonstrated a dose-dependent increase in thymidine incorporation and cell number when exposed to human sera. Pre- and post-GH sera were equipotent. Partial purification of somatomedin activity by boiling sera at pH 5.5 diminished the level of thymidine incorporation to 10-20% of the level achieved with unboiled sera but did not unmask a difference between pre- and post-GH sera. In contrast to the results in human fibroblasts, boiled post-GH sera were 2- to 5-fold more potent than pre-GH sera in stimulating thymidine incorporation in chick embryo fibroblasts. Mixing experiments failed to demonstrate inhibition of thymidine incorporation by boiled pre-GH sera. Boiled post-GH sera also were twice as active as boiled pre-GH sera in stimulating multiplication of chick embryo fibroblasts and confirmed that thymidine incorporation reflected DNA synthesis. GH added directly to chick embryo fibroblasts did not stimulate thymidine incorporation. We conclude that despite the presence of specific receptors for somatomedin-like peptides on human skin fibroblasts, somatomedins are not a major component of the serum macromolecules required for the routine growth of human fibroblasts in culture. In contrast, in chick embryo fibroblasts, somatomedins do appear to constitute an important part of the serum macromolecules supporting cell growth.

Animals↗
PubMed1978

Ocular emergencies.

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Arterial Occlusive Diseases↗
PubMed1976

The serum half-life of somatomedin activity: evidence for growth hormone dependence.

The serum half-life of somatomedin (SM) activity has been measured following the intravenous injection of SM activity into hypophysectomized rats. A [3H]thymidine incorporation assay in chick embryo fibroblasts (CEFs) has been utilized to measure SM activity. Cell cycle analysis data obtained with the flow microfluorometer shows that the [3H]thymidine incorporation data reflects actual DNA synthesis. When normal rat serum was injected, a half-life for SM activity of approximately 3 h was determined. In marked contrast, when serum from hypophysectomized (hypox) rats acutely treated with growth hormone (GH) was used as the source of SM actively, the half-life of the SM actively was short, approximately 8 min. However, when serum from hypox rats chronically treated with GH was injected, the half-life was again long, approximately 4 h. SM activity has been separated from its binding proteins by boiling under acid conditions or chromatography on Sephadex G-50 in 1 N acetic acid. The half-life of this partially purified SM activity was short, in the range of 10-30 min finally, recombination of the partially purified sm activity with the large proteins in normal serum extended in half-life of the sm from 10-03 min to about 2 h. These data indicate that the serum half-life of SM activity is GH dependent and suggest that the serum binding protein, like SM itself, is under GH control.

Animals↗
PubMed1976

Increased risk for spondylitis stigmata in apparently healthy HL-AW27 men.

Evidence for ankylosing spondylitis was sought by clinical, radiologic, and ophthalmologic examination in HL-A W27-positive men, aged 18 or older, selected from a tissue-donor population. Back pain of 3 months' duration or longer (P less than 0.05), back stiffness, restricted lumbar flexion and chest expansion, sacroiliac erosions (P less than 0.05) and sclerosis, and ophthalmologic sequels of anterior uveitis were found more often in the 24 men of the W27 group than in a control group of 31 men lacking this antigen. Based upon accepted criteria, 3 W27 persons had definite spondylitis and an additional 3 W27 persons and one control subject had findings strongly suggestive of spondylitis (P less than 0.05). This striking frequency, if extrapolated to the general population, would place approximately 1 of 4 W27-positive men at risk for this disease.

Adolescent↗
PubMed1975

Growth hormone-dependent serum stimulation of DNA synthesis in chick embryo fibroblasts in culture.

We have investigated the role of GH in the serum requirement for the multiplication of chick embryo fibroblasts (CEF-S) in culture . Serum from hypophysectomized (hypox.) rats is much less effective than normal serum in stimulating the incorporation of (3H-methyl]thymidine into DNA. More importantly, bovine GH(bGH) treatment of the hypox. rat restores 60% or more of the activity in the 3H-thymidine incorporation assay. Bovine GH is inactive when tested directly in the assay. Mixing experiments show that the decreased activity of hypox. serum is not due to the presence of an inhibitor in the hypox. serum. The GH is dependent factor is nondialysable and stable to Boiling at pH5.5. boiling the normal, hypox. and bGH treating hypox. rat sera results not only in enhancement of the activity but also a more linear dose response curve in the 3H-thymidine incorporation assay. The thesis because measurements of cell numbers show the CEFs multiply less well in boiled normal rat serum and bGH treatment of the hypox. rat restores approximately half of the multiplication stimulating activity of normal boiled rat serum. CEFs in culture may provide a satisfactory in vitro system for the study of the mechanism of action of the growth hormone dependent anabolic factors found in serum.

Animals↗
PubMed1975

Comparison of somatomedin activity in rat serum and lymph.

A chick embryo fibroblast (CEF) assay has been used to measure the somatomedin activity in serum and lymph from normal rats. Lymph contains about one-half the SM activity found in serum. The somatomedin activites in serum and lymph have identical elution volumes on Sephadex G-50 in 1N acetic acid. Chromatography at neutral pH demonstrates that somatomedin peptides are bound to large proteins in both normal rat serum and lymph. The relative restriction of somatomedin to the intravascular space may be due to this protein binding.

Animals↗
PubMed1974

Craniopagus twins.

Craniopagus twins are described. At the age of 24 years, the twins appeared to have adapted well to their disability. The site of union, their relatively advanced age, and the high risk of operation were the reasons for not proposing surgical separation. Perceptive upbringing and adaptation to the disability may be alternatives to the neurosurgical management of this birth defect.

Adaptation, Psychological↗