PubMed Health⌕ Search

Biomedical subjects

L M Cohen

Publications and source records attributed to L M Cohen.

At least 73 records · Page 4Linked to original sources
PubMed1985

Microcomputer programs for prediction and comparative evaluation of protein secondary structure from nucleotide sequence data: application to ribulose-1,5-bisphosphate carboxylase sequences.

Apple II PASCAL computer programs are described for routine evaluation of protein secondary structures predicted from DNA or amino acid sequence data. The programs predict protein secondary structure using the directional information algorithm of Garnier et al. (1978), and calculate hydrophobicity (Kyte and Doolittle, 1982), hydrophilicity (Hopp and Woods, 1981), hydrophobic moment (Eisenberg et al., 1984b), and secondary structure propensity profiles. The novel feature of these programs is the application of numeric and graphic methods, designed to facilitate detection and characterization of structural similarities/divergences using the aforementioned structural parameters. The use of the programs is demonstrated on a set of sequences from the large and small subunits of ribulose-1,5-bisphosphate carboxylase.

Base Sequence↗
PubMed1984

Schistosoma mansoni: long-term maintenance of clones by microsurgical transplantation of sporocysts.

Schistosoma mansoni sporocysts originally derived from monomiracidially infected Biomphalaria glabrata snails were serially transplanted into the cephalopedal sinus of anesthetized snails by the microsurgical implantation of fragments of parasitized hepatopancreas and ovotestis. Three to six passages each of five male and five female clones were maintained for as long as 2.0 years. Of the recipient snails which survived surgery, 87% released cercariae, usually beginning 5-7 weeks after surgery. The percentage of snails which released cercariae increased with successive passages. The mean survival time of surgically infected snails after cercarial emergence began was 9.2 +/- 0.5 weeks, nearly the same as that of miracidially infected snails. Longevities of snails infected with male or female clones were similar. Recipient snail size and age did not influence cloning success. Beginning 5 weeks from the onset of cercarial emergence large numbers of cercariae (a mean of 3900/snail from male clones and 1300/snail from females) were obtained during each shedding period. These results clearly demonstrate that the microsurgical transplantation of sporocysts is a practical means of maintaining and expanding populations of genetically homogeneous schistosomes (clones).

Animals↗
PubMed1983

Schistosoma mansoni: adult worm chemoattraction with barriers of specific molecular weight exclusions.

Chemoattraction studies were done with Schistosoma mansoni adults from mice. To test for attraction or repulsion, some worm pairs were separated mechanically and the individuals placed in polycarbonate chambers. Experiments were done at 37 C and chambers contained dialysis tube chimneys. In all cases, heterosexual attraction occurred when one worm, but not two worms, were placed in the chimneys. Unperforated chimneys with specific molecular weight (Mr) exclusions were compared with perforated chimneys to study heterosexual attraction. Attraction was similar in designs using perforated chimneys and those with 50,000 and 12,000 Mr exclusions, but none was seen in chimney designs with 1000 Mr exclusions.

Animals↗
PubMed1982

A current perspective of pseudocyesis.

Pseudocyesis is a diagnosis out of medical antiquity in with the physiological and psychological concomitants of pregnancy develop in the absence of the true gravid state. Along with other dramatic and polymorphous psychiatric disorders pseudocyesis appears to have decreased in frequency or altered its clinical manifestation in this century. The author discusses the reasons behind these changes and describes a comparable modern neuroendocrine diagnosis, the galactorrhea-amenorrhea hyperprolactinemia syndrome. He advocates the combined use of the term pseudocyesis for a selected population of patients.

Amenorrhea↗
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↗
PubMedDate not supplied

Effects of (+)-octanoylcarnitine in intact myocardium.

Fatty acid metabolites (long-chain esters of CoA and carnitine) which collect in ischemic myocardium can form amphiphiles capable of disrupting subcellular performance. It is important to document the role of these amphiphiles in intact tissue. D-Octanoylcarnitine was chosen because of its previously described effects on inhibiting palmitoylcarnitine transferase (PCT-II) in in vitro and in vivo liver preparations. This inhibition will shift tissue levels of CoA and carnitine intermediates and thus alter amphiphile levels. The compound's actions in cardiac muscle are unknown. Dose response curves were developed in intact hearts to test the influence of D-octanoylcarnitine at pharmacological concentrations. Measurements were obtained in working, extracorporeally perfused, swine hearts. Drug was administered either systemically (IV) or via direct intracoronary (IC) infusions into the left anterior descending coronary circulation. Excess fatty acids were provided to ensure adequate fatty acid substrate for oxidation. Coronary flow was controlled at aerobic levels. Systemic administration of D-octanoylcarnitine (0.8-6.8 mM) resulted in transient peripheral hypotension which caused correlative decreases in 14CO2 production from labeled palmitate. Infusion of D-octanoylcarnitine (0.5-3.9 mM) IC did not cause appreciable hypotension and was not associated with suppression of fatty acid oxidation. No build-up of carnitine esters was noted in treated hearts but acyl CoA levels were reduced (p less than or equal to 0.002). This latter finding was modestly related to increasing dose schedule of the compound in the IC group. The lack of suppression in fatty acid oxidation argues against significant inhibition of PCT II and lessens the attractiveness of using D-octanoylcarnitine in intact myocardium to selectively block fatty acid utilization at this locus.

Acetyl Coenzyme A↗
PubMedDate not supplied

Patient attitudes and psychological considerations in dialysis discontinuation.

The authors surveyed 36 adult patients who were maintained with chronic renal dialysis concerning their attitudes about dialysis discontinuation. Few subjects reported having ever considered stopping the life-support treatment. When asked to consider 12 hypothetical scenarios in which they might consider stopping treatment (e.g., onset of dementia or blindness), most subjects would still not consider discontinuation. Consideration of dialysis discontinuation was directly correlated with the patient's educational level. Follow-up after 1 year underscored the substantial differences between the responses the subjects gave to the 12 hypothetical scenarios and their real-life responses when they were later faced with decisions to actually terminate treatment. Psychiatrists have an opportunity to participate in the complex clinical and ethical decisions associated with advance directives and patients' right to refuse life-support treatment.

Adult↗
PubMedDate not supplied

Denying the dying. Advance directives and dialysis discontinuation.

A structured interview was administered to a sample of patients on maintenance dialysis and their attending physicians to obtain information on the documentation of their end-of-life treatment preferences. The majority of the patients reported never having considered stopping dialysis, or having discussed with their nephrologist or family the circumstances in which treatment should be discontinued. Only 7 patients (6%) had completed an advance directive; these patients were all men (P = 0.01) and tended to be better educated (P = 0.02). Only one of the nine physicians had completed an advance directive. In most cases, the dialysis patients and their treatment team staff were preoccupied with the struggles of daily life and had avoided or denied considerations of terminal illness and death. The literature on denial, medical illness, and dying is also reviewed as it relates to dialysis patients, end-of-life treatment, and terminal care.

Adult↗