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Biomedical subjects

M H Bernstein

Publications and source records attributed to M H Bernstein.

12 recordsLinked to original sources
PubMed1979

Independence of brain and body temperatures in flying American kestrels, Falco sparverius.

Brain and body temperatures were measured via small thermocouples implanted in the anterior hypothalami and colons, respectively, of five adult American kestrels (F. sparverius, mean mass 119 g) during descending flights in a wind tunnel at angles of 4 and 6 degrees below horizontal, at 10 m.s-1 air speed, and at 23 degrees C air temperature. For comparison, temperatures were recorded from resting birds at 22.5-36.1 degrees C air temperatures. Colonic (Tc) and hypothalamic (Th) temperatures both increased after the onset of flight; steady-state levels were attained after 1 min in the hypothalamus and after 5 or more min in the colon. The steady-state difference (delta T = Tc - Th) averaged 1.2 degrees C, higher by 0.5 degrees C than delta T in resting kestrels. The establishment of delta T during flight may be correlated with increased respiratory and corneal evaporation. The response apparently confines most stored body heat to noncranial regions, thus protecting brain tissue from thermal extremes.

Animals↗
PubMed1979

Fine structure of fetal human testis and epididymis.

Observations on the structure of the human fetal testis and epididymis at 16 weeks' gestation have been made with the light and electron microscope. The fetal testis is organized into solid cords surrounded by a well-defined cellular investment. The basement membrane is multilaminated with a highly redundant basal lamina. The germ cells rest on thin processes from adjacent Sertoli cells. Intercellular bridges between centrally located germ cells have been observed. The epididymis is remarkably well developed. The tall pseudostratified epithelium lines a discrete duct with a patent lumen. Stereocilia and cilia are seen on apical surface of the principal cells.

Cytoplasm↗
PubMed1978

Malachite green: applications in electron microscopy.

Incorporation of malachite green into a glutaraldehyde fixative results in enhanced staining of a number of cellular elements. Ribosomes and myofilaments exhibit increased electron density, but cell membranes generally are not stained. In certain tissues, lipid inclusions are uniformly and heavily stained. Other populations of lipid droplets exhibit differential affinity for malachite green, facilitating their division into subclasses. In addition to its function as a dye, malachite green has previously been reported to stabilize lipid elements soluble in aqueous glutaraldehyde. Such a component was observed in the stroma of uterine endometrium. The variety of cell components which exhibit increased contrast after preparation with malachite green suggests that this technique may find widespread application in fine structure studies.

Adrenal Cortex↗
PubMed1977

Measurement of evaporative water loss in small animals by dew-point hygrometry.

This paper presents the procedures and equations to be utilized for measurement of evaporative water loss (mw), by use of the dew-point hygrometer, in small animals exposed to air containing water vapor in an open-flow system. The system accounted accurately for the water evaporated from a bubble flask. In addition, hygrometric measurements of pulmocutaneous mw in pigeons (Columba livia, mean mass 0.31 kg) agreed closely with simultaneous gravimetric measurements, utilizing a desiccant in the sample stream, in a manner independently of air temperature (Ta, 20 or 40 degrees C), ambient water vapor pressure (PW, 4-16 10(2) Pa), or mw (5-66 mg-min-1). Evaporation in pigeons was independent of PW at 20 degrees C, but increased with decreasing PW at 40 degrees C, suggesting differences in ventilatory adjustments to changes in PW at the two temperatures.

Animals↗
PubMed1976

Ventilation and respiratory evaporation in the flying crow, Corvus ossifragus.

Tidal volume (VT), respiration frequency (f) and respiratory evaporation (mre) were measured in the passeriform fish crow, Corvus ossifragus (mass 0.28 kg), during steady state, horizontal, wind-tunnel flight, at air speeds of 7.4-11.0 m-sec-1 and air temperatures (TA) of 12-28 degrees C. Ventilation (V1) of the respiratory system was calculated as f-VT. All parameters were independent of speed. Respiration frequency was independent of TA. VT and V1 were independent of TA below 23 degrees C, but above 23 degrees C increased linearly, as did mre. Oxygen extraction (E), the fraction of available oxygen removed from respiratory system air, was calculated using oxygen consumption data (VO2) reported previously, and VI. E was independent of TA below 23 degrees C, where mean E, similar to that in crows resting at 20 degrees C, was substantially higher than in resting mammals of the same mass. E decreased at higher TA, reflecting hyperventilation accompanying elevated mre. mre accounted for the loss of only 17% of total metabolic heat production (Hp), as calculated from VO2, with a partial efficiency of 25%. Thus most heat loss must follow cutaneous evaporative, or nonevaporative routes.

Animals↗
PubMed1975

The localisation of bovine sperm hyaluronidase.

Hyaluronidase is a component of the acrosome of bovine spermatozoa. Utilizing fluorescein and peroxidase-labelled antibodies, the enzyme has been localised at both the light and electron microscopic levels. Antibodies against purified bovine testicular hyaluronidase were prepared in New Zealand white rabbits. Immunodiffusion, immunoelectrophoresis, and immuno-inhibition studies of the antiserum demonstrated the presence of an antibody specific for bovine sperm hyaluronidase with no cross reactivity to other sperm-associated antigens. Fluorescence microscopy of ejaculated bovine spermatozoa show the enzyme to be limited to the anterior portion of the acrosome with a sharp termination at the rostral border of the equatorial segment of the acrosome. Light microscopic studies with peroxidase-labelled antiserum were similar to the fluorescent findings. Fine structure studies revealed reaction product predominately associated with the matrix of the acrosome cap. Within the acrosome, more intense localisation was observed in the apical densities, while no product was visualised within the equatorial segment. These findings are compatible with the hypothesis that the enzyme functions to facilitate the passage of spermatozoa between cells.

Acrosome↗
PubMed1975

Light dependence of osmium reactivity in mouse photoreceptor cells.

Mouse photoreceptor cells exhibit local accumulations of osmium deposits after prolonged osmic staining at slightly elevated temperatures. Deposits were evident along the membranes of outer segment lamellae, Golgi cisternae and vesicles, nuclear envelopes, and synaptic vesicles. Other membranes within the photoreceptor cells were unreactive. No osmium reactivity was seen in other cells of the retina except for osmiophilic outer segment material which had been phagocytized by the pigment epithelium. In the outer segments, inner segments, and synaptic regions of the photoreceptor cells, the amount of osmium reactivity was increased by light stimulation and decreased following extended dark adaptation. The possible significance of the localized osmium reactivity is discussed.

Animals↗