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Biomedical subjects

B Cohen

Publications and source records attributed to B Cohen.

At least 325 records · Page 18Linked to original sources
PubMed1988

[Drug ototoxicity. Medicolegal aspects].

Drug ototoxicity is a preoccupying iatrogenic complication. Experimental studies over recent years, in particular a pharmacokinetic study of the elimination of aminoglycosides, have enabled the authors to define rules of prescription for parenteral aminoglycosides designed to reduce to a minimum the risk associated with their use. New aminoglycosides such as Netromycin appear to be associated with reduced toxicity. The medico-legal consequences of this complication are still rare, although more precise rules of prescription tend to make the experts more rigorous. The experimental evidence of cochleovestibular toxicity of aminoglycosides applied locally in the presence of a perforated tympanum leaves no room for doubt. The principal factor seems to be the duration of treatment. The prescription of a local aminoglycoside in the presence of a perforated tympanum would only appear to be justified from a legal point of view when absolutely indicated by antibiotic sensitivity tests.

Aged↗
PubMed1987

A new chemical method for etching metal frameworks of the acid-etched prosthesis.

Alloys containing beryllium, silicon, boron, and all nickel base alloys are etched well by the method described, with the exception of Fore alloy manufactured by the Unitek Corp. Alloys containing chrome and cobalt cannot be etched with Met-Etch gel. The advantages of using this method of chemical etching are (1) this conservative procedure can be performed in two clinical sessions, (2) the etching of the framework can be effectively controlled by the dentist or the laboratory technician, and (3) if the metal framework is dislodged it can be cleaned, etched, and reattached during the same appointment.

Acid Etching, Dental↗
PubMed1987

Baclofen and velocity storage: a model of the effects of the drug on the vestibulo-ocular reflex in the rhesus monkey.

1. Baclofen had a characteristic effect on vestibular and optokinetic nystagmus in rhesus monkeys. Each aspect of nystagmus that is dependent on the velocity-storage mechanism in the vestibulo-ocular reflex (v.o.r.) was altered by the drug: (a) Baclofen reduced the dominant time constant of the v.o.r. in a dose-dependent manner up to 5 mg/kg, the highest dosage used. The alteration in v.o.r. time constant began within 15 min of injection, was maximal between 1 and 4 h, and lasted for 14-18 h. This effect mirrors changes in plasma levels of baclofen after oral doses in humans (Faigle, Keberle & Agen, 1980). (b) Slow-phase velocities of steady-state nystagmus induced by rotation about axes tilted from the vertical (off-vertical axis rotation, o.v.a.r.) were reduced after baclofen and could not be maintained at previous levels. (c) There was a dose-dependent decline in the steady-state gain of optokinetic nystagmus (o.k.n.), and at the highest dosages little o.k.n. was induced. In parallel, the peak velocity and falling time constant of optokinetic after-nystagmus (o.k.a.n.) were reduced. Since baclofen is a GABA agonist, systems utilizing GABA and acting on GABAB receptors appear to produce inhibitory control of velocity storage. 2. The step gain of the v.o.r., measured at the beginning and end of constant-velocity rotation in darkness, was unaffected by baclofen, as were saccades, quick phases of nystagmus, and the ability to hold positions of fixation or to generate linear slow phases of nystagmus. This indicates that it is possible to use baclofen to manipulate the dominant time constant of the v.o.r. and of o.k.a.n. in relative isolation from effects on other oculomotor components. 3. Baclofen caused a dose-dependent reduction in the initial jump in eye velocity at the onset of o.k.n., suggesting that the initial jump is also under inhibitory control of GABAB receptors. However, there were still occasional slow phases with velocities up to 30-40 deg/s after baclofen, and animals were capable of visually suppressing the v.o.r. This indicates that pathways responsible for causing rapid changes in slowphase velocity were capable of functioning, at least intermittently, in the presence of the drug.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Influence of HLA matching, donor age, and cyclosporine on unrelated pediatric renal allograft survival.

Results in this study demonstrate that HLA matching has a beneficial effect on the survival of renal allograft in pediatric recipients. The introduction of a child-match procedure may have led to a lower degree of HLA well-matched grafts because of the small size of the pediatric waiting list. The poor results obtained in the group of children aged less than 6 years may have been due to a difference in physical condition at the moment of transplantation. This may explain why 4 of 20 (20%) of the failures in that age-group were due to patient death. The best results with the child-match procedure were obtained if the donor and recipient were both aged between 6 and 15 years. The overall graft survival in all children was improved by the use of Cs. An increase of approximately 10% was observed in this group of patients. The numbers in this group are too small, however, to permit any meaningful analysis of the influence of Cs on HLA matching. Finally, the overall results in this report demonstrate that renal transplantation is an effective form of therapy for end-stage renal disease in children.

Adolescent↗
PubMed1987

Legal and ethical implications of surrogate mother contracts.

Numerous legal and ethical issues are raised by the use of surrogate arrangements as a reproductive alternative. The purpose of this article is to provide physicians and other health care professionals with a basic overview of the legal issues and to outline some of the ethical considerations so that they might make more well-informed decisions about their personal involvement in surrogate arrangements and to better counsel their patients who might be considering such arrangements.

Contract Services↗
PubMed1987

Semisynthetic human insulin: biological and pharmacokinetic effects in normal subjects.

The assessment of pharmacokinetic and pharmacodynamic properties of semisynthetic human insulin produced by enzymatic conversion was done in normal subjects, and compared to those of highly purified pork insulin. Ten healthy volunteers were submitted to an intravenous injection of 0.06 U/kg of regular insulin, semisynthetic (Actrapid HM) and monocomponent pork insulin (Actrapid MC) in succession. No significant differences were pointed out as far as the pharmacokinetic parameters, immunoreactivity and hypoglycemic effect of both types of insulin are concerned. Only a stronger inhibition of endogenous insulin secretion, expressed by a significantly lower plasma-C-peptide levels, was observed after PPI. Stimulation of glucagon secretion was similar with both types of insulin.

Adult↗
PubMed1987

Comparative characteristics of predictive eye-hand tracking.

Eye and arm-hand movements were recorded in human subjects under three conditions. In the first a spot of light moved 30 deg back and forth sinusoidally at different frequencies. Limits of ocular pursuit were about 60 deg/sec at a frequency of about 1 Hz. In the second condition the arm and hand pointed a lever at the spot of light and pursued the moving visual target together with the eyes. The maximum velocity and frequency of ocular pursuit increased by about 20-30% with the addition of arm-hand movements. The arm and hand could move the lever faster than the eyes could pursue, but phase relations with regard to position between arm-hand movements and the visual target deteriorated at about 2 Hz when the eyes were unable to pursue the target. In the third condition the arm and hand drove the lever in self-paced movements, and the eyes pursued a target at the end of the lever. Maximum eye velocity increased slightly in two of three subjects in this condition, but no eye movements were made above 2.2 Hz. In contrast, self-paced arm and hand movements were made at frequencies up to 5 Hz and velocities of 400 deg/sec. The data are consistent with previous studies that indicate that the limits of ocular pursuit can be extended when eye movements are coupled to efferent signals and/or proprioceptive input from the skeletal motor system. The data also support previous findings of a dual-mode control system for the skeletal musculature during repetitive movements (Freund 1986).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Recovery surgery in cancer of the tongue. Apropos of 101 cases].

Results of 101 salvage glossectomies, after unsuccessful treatment of cancer of tongue by radiotherapy, showed a 3-year survival of 39% and a 5-year of 31%. Carcinologic failures represented 81% of causes of death: 17% due to distant metastases, 6% to a second focus and principally 32% to local recurrence. Local recurrence varied as a function of tumor size but also of site and type of surgical treatment. Tumors of the mobile tongue have a relatively good prognosis, even when the total organ is involved, with attachment to floor of mouth if an anterior transverse glossectomy is performed. Inversely, lateralized tumors spreading to base and to the mobile tongue treated by partial longitudinal glossectomy tend to have a high frequency of failure of local therapy, probably partly avoidable by wider excision. These same local failures of treatment are the cause of the worsening prognosis after total glossectomy in patients who had been poorly selected perhaps and presented extralingual spread not controlled by surgery. Finally, the authors emphasize the need for a collaboration of the patient in the choice of therapy, which involves surgery with functional sequelae that risk to be extremely heavy.

Adult↗
PubMed1986

Vibrotactile frequency discrimination at short durations.

This experiment investigated how frequency discrimination of a sinusoidal, mechanical vibration applied to the tip of the right index finger is affected by shortening the duration of the stimuli from 200 ms to 30 ms. Using a standard stimulus of 100 Hz at 30 dB above threshold, seven comparison frequencies (at intervals of 10 Hz) were judged as higher or lower in frequency according to the method of constant differences. Vibrotactile stimuli were matched for subjective intensity across both frequency and duration. Difference limens for vibrotactile frequency were found to decline slightly from 200 ms to 50 ms (attributable to practice) and to increase noticeably at 30 ms. This result is discussed in relation to the seemingly contradictory results for auditory pitch discrimination.

Adult↗