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Biomedical subjects

A Fein

Publications and source records attributed to A Fein.

At least 127 records · Page 7Linked to original sources
PubMed1980

Pathophysiology and management of the complications resulting from fire and the inhaled products of combustion: review of the literature.

Respiratory dysfunction is a major consequence of smoke inhalation and significant surface burns. Carbon monoxide intoxication, asphyxia, and upper airway obstruction occur early, whereas pulmonary edema and bacterial pneumonia may be delayed for days or weeks. The noxious constituents of smoke are believed to stimulate irritant receptors producing bronchoconstriction and to cause chemical injury to the airway mucosa and the alveolar-capillary membrane producing pulmonary edema. Pneumonia occurs in most patients who survive the initial injury. Thorough history and physical and laboratory examinations may forecast the severity of injury. Treatment includes administration of oxygen, use of bronchodilators, and when necessary, mechanical ventilation. The long-term sequelae of smoke inhalation are unknown.

Asphyxia↗
PubMed1980

Carbon monoxide effect on alveolar epithelial permeability.

A carbon monoxide (CO)-intoxicated patient developed increased permeability-type pulmonary edema demonstrated by a normal capillary wedge pressure and production of protein-rich edema fluid. To investigate the effect of CO on alveolar-epithelial permeability, a radio-active labelled isotope, 51Cr-EDTA (MW 377), was instilled into the airways of rabbits. Subsequent egress of the marker from the lungs into arterial blood was determined in serial arterial blood samples. The 51Cr-EDTA counts increased significantly within 15 minutes in the CO-exposed animals, compared with the control animals, while dynamic lung compliance fell, airways resistance rose, and arterial blood pressure decreased. Ultrastructural study of the lungs of CO-exposed animals revealed epithelial and endothelial cell swelling, in terstitial edema, and alveolar type II cells depleted of lamellar bodies. These findings support the possibility that carbon monoxide intoxication is associated with increased alveolar-epithelial permeability.

Adult↗
PubMed1979

Both photons and fluoride ions excite limulus ventral photoreceptors.

Illuminating Limulus ventral photoreceptors with dim light results in a response composed of discrete waves. In the dark, adding 10 mM sodium fluoride to the artificial seawater that bathes the photoreceptor includes discrete waves. The fluoride-induced waves are similar to those evoked by light. These findings suggest that fluoride induces a process similar or identical to visual excitation of the photoreceptor.

Animals↗
PubMed1979

The value of edema fluid protein measurement in patients with pulmonary edema.

Alveolar fluid and plasma proteins were analyzed in 24 patients with florid pulmonary edema, in 21 of whom pulmonary capillary wedge pressure (Pcw) was also measured. In all patients with Pcw less than 20 mm Hg, the edema fluid to plasma protein ratio exceeded 0.6; the mean edema fluid to plasma protein ratio in the four patients with cardiogenic edema (increased Pcw) was 0.46. In the 21 patients in whom full data were available, the net intravascular filtration force (Pcw - plasma colloid osmotic pressure) was less than -4 mm Hg, the value at which (according to others) pulmonary edema should occur, in only 10. When the interstitial colloid osmotic pressure, approximated by the osmotic pressure of edema fluid protein, was added, the net filtration force became positive in 17 of 21 patients. Comparison of the protein concentrations of edema fluid and plasma aids in the diagnostic separation of increased permeability from high hydrostatic pressure edema and adds to our understanding of the relative osmotic and hydrostatic forces that contribute to pulmonary edema when the alveolar-capillary membrane is damaged.

Adolescent↗
PubMed1979

Evaluation of transthoracic electrical impedance in the diagnosis of pulmonary edema.

To evaluate the clinical usefulness of measuring transthoracic electrical impedance in patients with pulmonary edema, we studied 27 normal subjects and 33 patients. In normal subjects, impedance increased when body position changed from supine to standing (p less than 0.01) and when lung volume increased from residual volume to total lung capacity (p less than 0.01). Impedance values vari7 omega) when measured hourly without removing the electrodes. In only five of 11 patients with clinically severe pulmonary edema and five of eight with radiologically severe pulmonary edema were impedance values outside the normal range. Changes in impedance values correlated with changes in clinical and radiographic indexes of pulmonary edema. We conclude that (1) single measurements of impedance are useless in diagnosing pulmonary edema, and (2) impedance changes as predicted as pulmonary edema increases and decreases, and these changes are readily detected by simpler methods of evaluation.

Adult↗
PubMed1978

A quantitative comparison of the time-course of sensitivity changes produced by calcium injection and light adaptation in Limulus ventral photoreceptors.

The time-course of light and dark adaptation was quantitatively compared with the time-course of the onset of and recovery from desensitization produced by intracellular calcium injection in Limulus ventral photoreceptors. The onset of light adaptation tended to be faster (by 60-90 s) than the onset of desensitization produced by intracellular Ca++ injection. The initial portion of the time-course of dark adaptation was faster (about 10-20 s) than the time-course of recovery from desensitization produced by intracellular Ca++ injection. The final portion of recovery from Ca++ injection had the same time-course as a comparable dark adaptation.

Animals↗
PubMed1977

Enhancement and phototransduction in the ventral eye of limulus.

Limulus ventral photoreceptors were voltage clamped to the resting (dark) potential and stimulated by a 20-ms test flash and a 1-s conditioning flash. At a constant level of adaptation, we measured the response to the test flash given in the dark (control) and the incremental response produced when the test flash occurred within the duration of the conditioning flash. The incremental response is defined as the response to the conditioning and test flashes minus the response to the conditioning flash given alone. When the test flash was presented within 100 ms after the onset of the conditioning flash we observed that: (a) for dim conditioning flashes the incremental response equaled the control response; (b) for intermediate intensity conditioning flashes the incremental response was greater than the control response (we refer to this as enhancement); (c) for high intensity conditioning flashes the incremental response nearly equaled the control response. Using 10-mum diam spots of illumnination, we stimulated two spatially separate regions of one photoreceptor. When the test flash and the conditioning flash were presented to the same region, enhancement was present; but when the flashes were applied to separate regions, enhancement was nearly absent. This result indicates that enhancement is localized to the region of illumination. We discuss mechanisms that may account for enhancement.

Action Potentials↗
PubMed1977

A quantitative comparison of the effects of intracellular calcium injection and light adaptation on the photoresponse of Limulus ventral photoreceptors.

Calcium ions were iontophoretically injected into ventral photoreceptors of Limulus by passing current between two intracellular pipettes. Changes in sensitivity and photoresponse time course were measured for both light adaptation and Ca++ injection. We found for some photoreceptors that there was no significant difference in the photoresponse time course for desensitization produced by light adaptation or by Ca++ injection. In other photoreceptors, the time delay of photoresponse for Ca++ injection was slightly longer than for light adaptation. The variability of threshold response amplitude and time delay decreases when the photoreceptor is desensitized by either light adaptation or Ca++ injection. The peak amplitude versus log stimulus intensity relationships for controls, light adaptation, and Ca++ injection all could be described very closely by a single template curve shifted along the log intensity axis. A 40- to 50-fold change in sensitivity is associated with a 2-fold change in photoresponse time delay for both light adaptation and Ca++ injection.

Adaptation, Ocular↗
PubMed1977

Increased intracellular sodium mimics some but not all aspects of photoreceptor adaptation in the ventral eye of Limulus.

The effects of the intracellular iontophoretic injection of Na+ ions have been quantitatively compared with adaptation in ventral photoreceptors of Limulus. We find that: (a) both light adaptation and sodium injection are associated with a decrease in the variability of the threshold response amplitued; (b) both light adaptation and sodium injection are associated with a decrease in the absolute value of the temporal dispersion of the threshold response time delay; (c) the same template curve adequately fits the intensity response relationships measured under light adaptation and Na+ injection; (d) both light adaptation and Na+ injection produce a fourfold decrease in response time delay for a desensitization of 3 log units; (e) the time coures of light adaptation and dark adaptation is significantly faster than the onset of and recovery from desensitization produced by Na+ injection; (f) unlike local illumination, Na+ injection does not produce localized desensitization of the photoreceptor. These findings suggest that a rise in intracellular Na+ concentration makes at most only a minor contribution (probably less than 5%) to the total adaptation of these receptors in the intensity range we have examined (up to 3 log units above absolute threshold). However, changes in intracellular Na+ concentration may contribute to certain components of light and dark adaptation in these receptors.

Action Potentials↗
PubMed1977

The effect of Imuran on implantation and early embryonic development in rats.

Pregnant rats were injected daily with 2, 4, and 20 mg/kg of Imuran from the first day of gestation until sacrificed on Days 6-12. Gravid uteri, as well as maternal organs, were removed and examined histologically. According to the histologic findings, the treatment with the high dose of 20 mg/kg/day Imuran induced injuries to the blastocyst. Starting from Day 8, the trophoblastic layer lost its continuity and maternal blood invaded into the blastocystic cavity resulting in destruction of embryonic tissues. This degeneration progressed until evident resorption on Day 12. Smaller doses, such as 2 or 4 mg/kg of Imuran, did not result in early trophoblastic damage. The effect seemed to be the result of the antimetabolic effect of Imuran acting on the proliferating trophoblast through the maternal blood.

Animals↗