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Biomedical subjects

R L Moss

Publications and source records attributed to R L Moss.

At least 235 records · Page 13Linked to original sources
PubMed1980

Sarcomere length-tension relations of frog skinned muscle fibres at lengths above the optimum.

1. Single twitch fibres were dissected from anterior tibial muscles of the frog, Rana pipiens, and were then either chemically or mechanically skinned. Short segments of the skinned fibres were transferred to an experimental chamber and mounted between a force transducer and a stationary wire. 2. The average sarcomere length was determined from light photomicrographs of the segments obtained during activation and while relaxed. Activations were maximal, in solutions of pCa 5.49 and at 5 degrees C. Fibre segments having regions in which the striation pattern was highly non-uniform were rejected. 3. The relationship between tension and average sarcomere length was determined for sarcomere lengths between 2.1 and 3.8 micrometer. Tension always decreased when sarcomere length was increased above about 2.2 micrometer. Tension plotted against over-all average sarcomere length lay above data obtained from living fibres by Gordon, Huxley & Julian (1966a, b). 4. Good agreement with living fibre results was found when tension was plotted against the shortest average sarcomere length within a portion of the segment. 5. These findings indicate that sarcomere length non-uniformities greatly influence the shape of the sarcomere length-tension relation in skinned fibres at long lengths. In addition, no evidence was found for a length-dependent influence of calcium on tension development at long lengths during maximal activation.

Animals↗
PubMed1980

Intra- and extrahypothalamic luteinizing hormone-releasing hormone (LHRH) distribution in the rat with special reference to mesencephalic sites which contain both LHRH and single neurons responsive to LHRH.

In addition to hypothalamic sites known to contain LHRH, several extrahypothalamic structures in both male and female rats were discovered to contain the decapeptide. In the mesencephalon, the fasciculus retroflexus, interpeduncular nucleus and midbrain central grey contained readily detectable quantities of LHRH. Single neurons responsive to microiontophoretically applied LHRH were also discovered in the mesencephalon suggesting a physiological role for the decapeptide in neuronal events at the level of the midbrain.

Animals↗
PubMed1980

Physician attitudes toward pharmacists counseling patients on adverse drug reactions.

The attitudes of physicians in a university teaching hospital toward pharmacist counseling of patients regarding adverse reactions to prescribed medications were studied. A questionnaire mailed to 120 physicians in each of the three groups affiliated with the Medical College of Virginia Hospitals (teaching faculty, house staff, and community practitioners with attending privileges) listed 56 potential adverse reactions associated with commonly prescribed medications in 13 therapeutic categories. For each physician group, half of the questionnaires pertained to inpatient and half to outpatient situations. The physicians were asked whether their patients should be informed about the possible reactions and, if so, if the physician alone, the pharmacist alone, or both should do the counseling. When "pharmacists only" and "both" data were combined for the 199 responses, over 50% of the respondents accepted pharmacists as patient counselors for all listed reactions except the three pertaining to antipsychotic agents. Class of medication significantly influenced attitude (p less than 0.05), with pharmacist participation in counseling being most acceptable for reactions involving anticoagulants, antibiotics, and analgesics, and least acceptable for those involving antipsychotics, cardiac glycosides, and antianxiety agents. Acceptability also was influenced by physician type (p less than 0.05), being lowest among community physicians, and was slightly higher in outpatient versus inpatient situations (p less than 0.05). The study indicates that physicians will accept pharmacist counseling with respect to adverse drug reactions, especially on a partnership basis.

Attitude of Health Personnel↗
PubMed1979

Roles of gonadotropins and releasing hormones in hypothalamic control of lordotic behavior in ovariectomized, estrogen-primed rats.

Intrahypothalamic effects of gonadotropins (luteinizing hormone and follicle-stimulating hormone), thyrotropin-releasing hormone (TRH), and luteinizing-hormone-releasing hormone (LRH) on lordotic behavior were evaluated in ovariectomized (OVX) rats maintained at different receptivity levels. Under conditions of low receptivity in which LRH has been shown to enchance mating behavior, medial preoptic area (MPOA) infusions of luteinizing hormone (LH) caused significant depressions in the lordotic response, whereas LH infusions into the arcuate ventromedial area (ARC-VM) had no sigificant effect. Follicle-stimulating hormone (FSH) infusions into either area did not alter the behavioral response. In the second experiment, in which OVX rats were primed with higher doses of estrone to maintain high ptrinfusion receptivity, MPOA or ARC-VM infusions of either LH or TRH were shown to depress lordotic behavior significantly, whereas neither LRH nor FSH was observed to inhibit the behavioral response. A third experiment evaluated the effects of LH, FSH, and TRH on LRH-facilitated mating behavior. Infusions of LRH into either the MPOA or the ARC-VM significantly enhanced mating behavior, whereas the addition of either TRH or LH to the LRH infusates abolished this response. The addition of FSH to LRH infusates neither enhanced nor depressed the behavioral response to MPOA or ARC-VM infusions of LRH. The antagonistic effects of LH and TRH on LRH-facilitated mating behavior were correlated with previous observations of antagonistic effects on hypothalamic unit activity and monoamine metabolism. The antagonistic interrelation between LRH and LH may represent a mechanism for the activation and coordination of sexual receptivity with ovulation.

Animals↗
PubMed1979

Sarcomere length-tension relations of frog skinned muscle fibres during calcium activation at short lengths.

1. Single twitch fibres were isolated from anterior tibial muscles of the frog, Rana pipiens. The relationship between sarcomere length and steady tetanic tension at 5 degrees C was obtained from these living fibres in the range of sarcomere lengths between about 2.2 and 1.3 microns . These fibres were then either mechanically or chemically skinned. 2. Segments were cut from the skinned fibres and mounted in an experimental chamber using a technique designed to minimize segment compliance at the points of attachment. A piece approximately 1 mm in length remained exposed to the bathing solution. 3. The segments were photographed through a light microscope at magnifications of about 460 or 110 X during activation and relaxation, so that the sarcomere lengths could be determined from a part or the whole of the segment. Activations were done with solutions of pCa either 5.49 or 6.09 and at a temperature of 5 degrees C. Fibre segments which developed striation pattern irregularities during contraction were rejected. 4. The sarcomere length-tension relation obtained from these segments in the sarcomere length range 1.3-2.2 microns was similar to that obtained from the same fibres while still living. The results were similar at the two values of pCa used. 5. These results do not support the view that sarcomere length dependent variation in the amount of calcium which is released during tetanic stimulation is a major determinant of the form of the length-tension relation in living muscle fibres at sarcomere lengths less than about 2.0 microns.

Animals↗
PubMed1978

The effect of ovariectomy on the responsiveness of preoptic-septal neurons to microelectrophoresed estrogen.

Extracellular potentials were recorded from medical preoptic-septal (MPOA-S) neurons in 2-week and 3--4 month ovariectomized rats, and the effects of microelectrophoresed 17beta-estradiol hemisuccinate (17betaE2S), acetylcholine (Ach), cortisol hemisuccinate (CS) and glutamate (Glut) were studied. 17betaE2S failed to produce changes in the firing rate of the majority of MPOA-S neurons tested, but Ach excited 48% of these neurons. MPOA-S neurons showed very little response to either Glut or CS. Previous findings from this laboratory have demonstrated that MPOA-S neurons recorded in 4-day cyclic female rats will respond to 17betaE2S. Therefore, the present results suggest that the ovarian steroids are necessary for maintaining this electrical sensitivity. Also, the involvement of a specific membrane or cytoplasmic receptor is discussed.

Acetylcholine↗