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Biomedical subjects

R M Klein

Publications and source records attributed to R M Klein.

At least 181 records · Page 10Linked to original sources
PubMed1979

Alteration of neonatal rat parotid gland acinar cell proliferation by guandethidine-induced sympathectomy.

Newborn rats were injected with guanethidine-sulfate (20 micrograms/g body weight) every 48 hr from 12 hr after birth until day 14 (eight injections per animal). The guanethidine treatment resulted in an 86% absolute reduction in cell number in the superior cervical ganglia of 15 day old rats. The cells which remained after guanethidine treatment showed destruction of mitochondria and an extensive decrease in endoplasmic reticulum. Chemical sympathectomy with guanethidine induced a 3.1 hr lengthening of the acinar cell generation cycle time (17.4 hr to 20.5 hr), resulting from a longer G1 period (6.9 hr in the control group as compared to 10.5 hr in the guanethidine-treated group), as well as a cecrease in the mean percentage of [3H]thymidine-labeled acinar cells (22.3 +/- 0.5% to 19.3 +/- 0.5%) and mean acinar cell mitotic index (2.6 +/- 0.2% to 2.1 +/- 0.1%). A circadian rhythm was found to exist in parotid gland acinar cell mitotic activity of 15 day old rats and the amplitude of the rhythm was reduced from 26.5% to 14.9% in guanethidine-treated rats. This study indicates that the diminution of sympathetic influence on the developing parotid gland results in a slight, but significant alteration in acnar cell proliferation.

Animals↗
PubMed1979

Analysis of intestinal cell proliferation after guanethidine-induced sympathectomy. II. Percentage labelled mitoses studies.

Neonatal administration of guanethidine-sulfate results in an alteration of the cell proliferative pattern of the small intestinal epithelium of the young adult rat. Sympathectomy with guanethidine has previously been shown to depress mitotic, labelling, and total cellular migration indices while increasing the generation cycle time (Tc) of small intestinal crypt cells as measured by a stathmokinetic method. The present study showed that the G1, S and G2 phases of the crypt cell cycle are altered by sympathectomy, G1 accounting for most of the increase in Tc. In addition, the percentage of [3H]-thymidine labelled crypt cells is reduced and the duration of crypt cell transit is lengthened by guanethidine-induced sympathectomy.

Animals↗
PubMed1978

Analysis of intestinal cell proliferation after guanethidine-induced sympathectomy. I. Stathmokinetic, labelling index, mitotic index, and cellular migration studies.

Guanethidine-induced sympathectomy in the rat during the neonatal period (injection of 20 microgram/g body weight every 48 h from day of birth until day 14) produces an absolute reduction in the number of sympathetic ganglion cells, but no significant alteration of body weight. Superior cervical ganglia show 79.8% fewer cell bodies at 15 days and 92.3% at 45 days; coeliac ganglia exhibit an 81.0% reduction at 15 days and 89.6% at 45 days in guanethidine-treated rats as compared to normal controls. The sympathetic ganglion cells that remain after treatment have an abnormal morphological appearance with distended mitochondria and depletion of endoplasmic reticulum. Sympathectomy produces a prolongation of the generation cycle time (Tc) as measured by the colchicine-induced mitotic arrest technique, and a decrease in labelling, mitotic, and migration indices. In addition, sympathectomy suppresses the amplitude of the circadian rhythm in mitotic activity. The general suppression of this activity in the intestinal epithelium is more pronounced in the jejunum and ileum than in the duodenum. Variation in the effectiveness of sympathectomy on the inhibition of intestinal cell proliferation may be related to segmental differences in cell proliferation, to segmental differences in innervation, and/or to segmental variation in the effectiveness of guanethidine.

Animals↗
PubMed1978

Visual dominance in the pigeon.

In Experiment 1, three pigeons were trained to obtain grain by depressing one foot treadle in the presence of a 746-Hertz tone stimulus and by depressing a second foot treadle in the presence of a red light stimulus. Intertrial stimuli included white light and the absence of tone. The latencies to respond on auditory element trials were as fast, or faster, than on visual element trials, but pigeons always responded on the visual treadle when presented with a compound stimulus composed of the auditory and visual elements. In Experiment 2, pigeons were trained on the auditory-visual discrimination task using as trial stimuli increases in the intensity of auditory or visual intertrial stimuli. Again, pigeons showed visual dominance on subsequent compound stimulus test trials. In Experiment 3, on compound test trials, the onset of the visual stimulus was delayed relative to the onset of the auditory stimulus. Visual treadle responses generally occurred with delay intervals of less than 500 milliseconds, and auditory treadle responses generally occurred with delay intervals of greater than 500 milliseconds. The results are discussed in terms of Posner, Nissen, and Klein's (1976) theory of visual dominance in humans.

Journal Article↗
PubMed1977

Attention and visual dominance: a chronometric analysis.

Three chronometric experiments, each comparing vision and kinesthesis, were conducted to study visual dominance. The time required to switch attention from vision and from kinesthesis was equal, while switching to kinesthesis was faster than switching to vision (Experiment 1). Responses to a combined visual-kinesthetic stimulus were slower than responses to a kinesthetic stimulus alone when the subject was expecting the bimodal stimulus. The visual dominance effect was shown to depend on the subject knowing the modality of the stimulus in advance (Experiment 2). When subjects were instructed to attend one modality they had equal difficulty with conflicting visual and kinesthetic information (Experiment 3). These findings suggest that visual dominance results from a bias to attend vision when that modality seems adequate for the task. Te bias to attend vision may develop to overcome a deficiency in visual alerting.

Acoustic Stimulation↗
PubMed1977

Isoproterenol and G2 acinar cells in the developing rat parotid gland.

In the present study, premitotic period (G2)-delayed or blocked acinar cells were identified in the parotid gland of the neonatal rat. The noncycling G2 cells retain the potential to divide and respond to administration of the sympathomimetic amine, isoproterenol (IPR). The effects of IPR on suckling and weaned rats were compared. Both groups showed the presence of G2-acinar cells with a possible age-related change occurring after weaning.

Animals↗
PubMed1976

Cystoid macular edema in the first week after cataract extraction.

Fluorescein angiography was safely performed in 100 consecutive cases of cataract extraction during the first postoperative week. Seventy-five percent of the 100 eyes had good quality fluorescein angiograms. Four eyes demonstrated cystoid macular edema. Therefore, the incidence of cystoid macular edema in the first week after cataract surgery was low when compared to the reported incidence (40%) four to six weeks postoperatively.

Adult↗
PubMed1975

Chlordiazepoxide (librium)-induced changes in intraspecific attack and selected non-agonistic behaviors in male Siamese fighting fish.

Two experiments were undertaken to determine the effects of chlordiazepoxide on intraspecific attack behavior and selected non-aggressive behaviors in male Siamese fighting fish. In Exp. 1, pairs of fish fought while immersed in either 15 mug/ml or 30 mug/ml of chlordiazepoxide, or plain water. The drug groups showed significantly less attack (e.g., biting, jawlocking) than the control group, without noticeable behavioral toxicity. Also, in the drug groups alone, some variants of the copulatory clasp, seen in normal mating, occurred in many pairs. In Exp. 2, individual fish were isolated in one of the same doses or plain water for a period equivalent to that of Exp. 1. These doses produced no changes in measures of arousal, locomotion, and feeding behavior, as compared to the control condition. The drug-related appearance of the intermale mating-like behavior is discussed in terms of a theoretical formulation postulating a mutually inhibitory relationship between sex and aggression in fish.

Aggression↗
PubMed1975

Lacquer crack lesions in pathologic myopia.

In evaluating the anatomic and functional status of 22 eyes of 14 patients demonstrating lacquer cracks, these lesions occurred in the eyes of young adults with posterior staphylomas and markedly increased axial lengths. Decreased visual acuity and altered visual fields were the rule; choroidal hemorrhage and focal chorioretinal atrophy were less frequently associated. Fluorescein angiography revealed early and late pseudofluorescence and late staining of the lesions. These clinical data suggest that lacquer cracks represent healed, mechanical breaks in the pigment epithelium-Bruch's membrane-choriocapillaris complex. The presence of these lesions implies a guarded prognosis for the retention of central vision.

Adolescent↗