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Biomedical subjects

D Cohen

Publications and source records attributed to D Cohen.

At least 649 records · Page 36Linked to original sources
PubMed1983

Pharmacokinetics of ceftriaxone in patients with renal failure and in those undergoing hemodialysis.

The pharmacokinetic parameters of ceftriaxone in eight patients with end-stage renal disease were determined during dialysis and during the interdialysis period. The mean half-life, clearance, and apparent volume of distribution during dialysis were 16 h, 722 ml/h, and 16.7 liters, respectively. During the interdialysis period, the half-life was 14 h, clearance was 739 ml/h, and volume of distributions was 14 liters. Individual variability in plasma concentrations occurred even in patients with apparently normal hepatic function. Based on these parameters, a dose of 1 g every 24 h would yield concentrations in excess of the concentrations needed to inhibit most gram-positive and gram-negative aerobic species.

Adult↗
PubMed1983

Predominance of renal and absence of hepatic metabolism of pancreatic polypeptide in the dog.

Pancreatic polypeptide (PP) metabolism was studied in the dog. Metabolic clearance rate (MCR) of PP was found to be 9.5 +/- 0.9 ml . kg-1 . min-1, accounted for predominantly by renal extraction (34.9 +/- 2.6% of exogenous PP), which comprised 45.5 +/- 5.8% of total PP clearance. Hepatic extraction of both endogenous (-9.9 +/- 6.1%) and exogenous (2.2 +/- 1.4%) PP infused to pharmacological levels was negligible, as was its splanchnic extraction (4.2 +/- 0.9%). Renal organ clearance of exogenous PP (3.7 +/- 0.3 ml . kg-1 . min-1) closely approximated that of inulin (3.6 +/- 0.3 ml . kg-1 . min-1), indicating that renal PP metabolism occurs entirely by glomerular filtration without contribution from peritubular uptake mechanisms. Urinary PP, chromatographically indistinguishable from that in plasma but quantitatively accounting for less than 1% of overall renal PP uptake, indicated virtually complete renal degradation of the peptide to nonimmunoreactive fragments. Renal PP extraction was shown to be nonsaturable. Plasma half disappearance time of PP was 10.1 +/- 1.0 min and apparent distribution space 307 +/- 39 ml/kg. Linkage between the hepatic action and degradation of insulin and glucagon has been proposed, and in this light absent hepatic PP extraction is noteworthy. This finding, reminiscent of the hepatic handling of metabolically inert C-peptide and biologically inactive glucagon peptides, is consistent with the absence of demonstrable physiological function of PP.

Animals↗
PubMed1983

Magnetic measurement of S-T and T-Q segment shifts in humans. Part I: Early repolarization and left bundle branch block.

The direct-current magnetocardiogram not only shows the features usually seen on the electrocardiogram, but also shows the T-Q (baseline) shift due to cardiac injury current. The first direct-current magnetocardiogram measurements of the human heart are presented here. The hypothesis tested is that there is no injury current associated with the S-T shift seen in two electrocardiogram abnormalities: early repolarization, and left bundle branch block. The data from three typical early repolarization subjects and one typical left bundle branch block patient are presented. It is found, in each case, that although there is appreciable S-T shift, there is essentially no baseline shift on the direct-current magnetocardiogram. The absence of baseline shift proves that the S-T shifts in these cases are not "apparent" shifts, caused by a dc injury current which is interrupted during the S-T interval; instead, these are "true" S-T shifts caused by a current flowing only during systole, presumably due to an altered repolarization of the ventricles. It is also found that the direct-current magnetocardiogram does not have routine clinical application because of a practical problem. This is the presence of false baseline shifts due to noncardiac currents, mostly in the gastrointestinal tract, which could be suppressed in only about one-third of the subjects. However, the direct-current magnetocardiogram may be useful as a research tool, for clarifying the cause of the S-T shift in selected subjects.

Electrocardiography↗
PubMed1983

Magnetic measurement of S-T and T-Q segment shifts in humans. Part II: Exercise-induced S-T segment depression.

The direct-current magnetocardiogram, which shows the T-Q (baseline) shift, is used to clarify the cause of S-T depression induced by stress testing in the human heart. Measurements are made of the amount of baseline shift associated with the S-T depression. Results are presented of a well-documented patient, with typical coronary artery disease, undergoing a two-step exercise test. Before exercise, there was no S-T or baseline shift. During exercise, the S-T segment became depressed and the baseline segment was simultaneously elevated, at about 70% of the S-T amplitude. After termination of exercise, the baseline elevation disappeared somewhat more rapidly than the S-T depression. These results were consistent in repeated tests of this patient. Because the baseline shift is a reflection of an injury current, these results confirm the belief that exercise-induced S-T depression is mostly due to an injury current which is interrupted during the S-T interval. The baseline shift seen here is the first non-invasive measurement of an injury current in the human heart, and its presence and time-course generally agree with measurements in the animal heart. This work also confirms that the direct-current magnetocardiogram, although not practical for clinical purposes, is useful as a research tool.

Heart↗
PubMed1983

Metabolism of C-peptide in the dog. In vivo demonstration of the absence of hepatic extraction.

The in vivo hepatic metabolism of connecting peptide (C-peptide) in relation to that of insulin has not been adequately characterized. A radioimmunoassay for dog C-peptide was therefore developed and its metabolism studied in conscious mongrel dogs, with sampling catheters chronically implanted in their portal and hepatic veins and femoral artery. The hepatic extraction of endogenous C-peptide under basal conditions was negligible (4.3 +/- 4.5%) and was similar to the hepatic extraction of C-peptide measured during the constant exogenous infusion of C-peptide isolated from dog pancreas. Simultaneously measured hepatic extraction of endogenous and exogenously infused insulin were 43.8 +/- 7.6 and 47.5 +/- 4.4%, respectively. The metabolic clearance rate of infused C-peptide was 11.5 +/- 0.8 ml/kg per min and was constant over the concentration range usually encountered under physiological conditions. In additional experiments, the effect of parenteral glucose administration on the hepatic extraction of C-peptide and insulin was investigated. The hepatic extraction of C-peptide (6.2 +/- 4.0%) was again negligible in comparison with that of insulin (46.7 +/- 3.4%). Parenteral glucose administration did not affect the hepatic extraction of either peptide irrespective of whether it was infused peripherally, intraportally, or together with an intraportal infusion of gastrointestinal inhibitory polypeptide. The fasting C-peptide insulin molar ratio in both the portal vein (1.2 +/- 0.1) and femoral artery (2.1 +/- 0.3) was also unaffected by the glucose stimulus. These results therefore indicate that, since the hepatic extraction of C-peptide is negligible and its clearance kinetics linear, the peripheral C-peptide concentration should accurately reflect the rate of insulin secretion. New approaches to the quantitation of hepatic extraction and secretion of insulin by noninvasive techniques are now feasible.

Animals↗
PubMed1983

A controlled clinical trial of alprazolam for the treatment of anxiety.

The authors report the results of a large-scale double-blind study comparing the anxiolytic effects of alprazolam, a triazolobenzodiazepine; diazepam, a 1,4-benzodiazepine; and placebo in 151 anxious outpatients. Alprazolam and diazepam produced similar clinical improvement, which was significantly larger than improvement produced by placebo and was clearly evident after only 1 week of treatment. The incidence of sedation was lower with alprazolam than with diazepam.

Adult↗
PubMed1983

The effectiveness of videotape in patient education on depression.

The effectiveness of videotape for patient education on depression was assessed. The videotape was shown to members of a general patient population and accompanying persons in the waiting area of a health maintenance organization (HMO) clinic, then evaluated according to pre- and post-test questionnaire responses before and after viewing the tape. The patients' knowledge of depression increased significantly (p less than or equal to 0.002) as a result of the videotape intervention. Although attitudes were not affected, 91.7% found it useful and 38.3% thought it reassuring. There was a high demand for access to more health educational videotapes.

Attitude↗
PubMed1983

AA protein-related renal amyloidosis in drug addicts.

Reports of renal amyloidosis occurring among narcotic addicts have been limited, for the most part, to case reports. In a prospective survey of 150 addicts examined at autopsy in the Office of the Chief Medical Examiner of the City of New York, 7 cases of renal amyloidosis were found. Immunohistologic examination demonstrated that in all of the 7 cases, the amyloid was AA protein-related. The amyloid extracted from the kidneys of two addicts and analyzed biochemically did not differ from the AA amyloid secondary to chronic infectious and inflammatory diseases. The combined data of previous reports and the present survey demonstrate that addicts who are subcutaneous users with skin infections most frequently develop amyloidosis. Our data demonstrating renal amyloidosis in 26% of addicts with chronic suppurative skin infections suggest that such addicts are at high risk for the development of amyloidosis.

Adult↗
PubMed1983

[Diffuse retinal epitheliopathy and central serous chorioretinopathy].

Follow-up examinations were conducted in 27 patients (51 eyes) affected by diffuse retinal pigment epitheliopathy (D.R.P.E.), over an average period of 37 months. This disease associates multiple subretinal foci of leakage resulting in retinal serous detachments (R.S.D.), often widespread alterations in retinal pigment epithelium, and frequent small serous detachments of retinal pigment epithelium. The course is chronic and recurrence of subretinal leakage is common. Involvement of macular pigment results in poor long-term visual prognosis. Features of these patients were compared with those of 138 patients affected by central serous choroidopathy (C.S.C.). Both D.R.E.P. and C.S.C. are more frequent in males, and demonstrate subretinal leakages and transient retinal serous detachments. Nevertheless, numerous data differentiate these two diseases, D.R.P.E. being detected at a later age (49 years) than C.S.C. (39 years). Bilaterality of the affection is more frequent in D.R.E.P. (88 p. cent) while serous detachment is less frequent in D.R.P.E. (31 p. cent) than in C.S.C. (82 p. cent). Small foci of subretinal leakage are present in both diseases but they are frequently multiple, scattered, extra-macular and mainly peripapillary in D.R.P.E.; they are chronic or recurrent and are present usually in an area of pigment epithelium depigmentation. These changes are often vertically oriented downwards towards the inferior periphery of the fundus. In D.R.P.E. there are frequently visual fields defects (70,5 p. cent) corresponding to the area of pigmentary involvement, dyschromatopsy (64 p. cent) and E.O.G. abnormalities (75 p. cent). D.R.P.E. and C.S.C. are two closely related diseases but they differ by the extent and diversity of the pigment epithelium lesions functional impairment, and visual prognosis. Photocoagulation of leaking spots resulting in macular detachment appears to be justified as in C.S.C. Long-term prognosis depends on the degree of extension of pigmentary changes into the macular area.

Adult↗
PubMed1982

[Polymorphism of HLA genes: I. Demonstration of a close correlation between DNA fragments determined by BglI restriction enzyme and HLA class I antigens].

Description of DNA fragments associated to HLA class I gene is possible by using restriction enzymes which determine these fragments and specific DNA probes which permit their detection. In one family, with a child presenting a recombination between HLA-A and C, six fragments determined by the enzyme BglI were found to be polymorphic. The informative fragments segregate with HLA, either with a whole haplotype or with one of the two recombinant segments of the HLA complex. In a small sample of population they correlate with one (A11) or with a group of known cross-reactive antigens serologically defined (A3 and A11; A25 and A26. Another fragment is associated with unknown cross-reactive antigens (A2 and A29).

DNA↗
PubMed1982

Discrimination and imitation of facial expression by neonates.

Human neonates (average age, 36 hours) discriminated three facial expressions (happy, sad, and surprised) posed by a live model as evidenced by diminished visual fixation on each face over trials and renewed fixations to the presentation of a different face. The expressions posed by the model, unseeen by the observer, were guessed at greater than chance accuracy simply by observing the face of the neonate, whose facial movements in the brow, eyes, and mouth regions provided evidence for imitation of the facial expressions.

Behavior↗
PubMed1982

Motoric laterality and eye dominance suggest unique pattern of cerebral organization in schizophrenia.

The performance of 26 young patients with early-onset schizophrenia on motoric laterality and eye dominance was compared with that of 24 psychiatric inpatients suffering from an early and diffuse brain damage, 16 nonpsychotic non-brain-damaged psychiatric inpatients, and 36 university students. All subjects were in late adolescence. These schizophrenic patients showed more left-sidedness on all the laterality measures. Left eye dominance was highly prevalent in the schizophrenic group (about 75% of the subjects) and had high diagnostic usefulness. In addition, laterality measures of the schizophrenic patients were highly incongruous. Our results support the hypothesis of a specific left hemispheric dysfunction in schizophrenia that is neither shared by all psychiatric patients nor resembles a generalized insult to the brain. Although the left hemispheric dysfunction in schizophrenia is considered to be neurological, the etiological contributions of brain insults and of genetic and environmental factors are unclear.

Adolescent↗