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Biomedical subjects

S L Klein

Publications and source records attributed to S L Klein.

53 records · Page 3Linked to original sources
PubMed1984

Cerebral and systemic vascular effects of naloxone in pentobarbital-anesthetized normal dogs.

In this study, 10 mongrel dogs were anesthetized with sodium pentobarbital and nitrous oxide. Blood flow was determined using the radioactive microsphere technique before and after the bolus intravenous injection of naloxone (10 mg/kg). Naloxone significantly increased cerebral blood flow to cerebral cortex and the total cerebral hemisphere without an associated change in the cerebral metabolic rate of oxygen. The increase in cerebral blood flow was proportional to the elevation in mean arterial pressure. There were no consistent changes in electrical activity as measured by electroencephalography (EEG) and Fourier analysis of EEG. Systemically, naloxone induced a proportional rise in mean arterial pressure and peripheral vascular resistance and also stimulated the myocardium, as evidenced by an improved cardiac index and stroke volume. These data suggest that naloxone may interfere with cerebral autoregulation or have direct vasodilatory effects on cerebral blood vessels that are not associated with opiate receptor blockade or changes in cerebral metabolism. In addition, naloxone did not appear to reverse the cerebral depressive effects of pentobarbital. Systemically, naloxone seemed to potentiate pentobarbital-induced vasoconstriction and reverse myocardial depression.

Anesthesia↗
PubMed1981

Recovery from experimentally induced problem-solving deficits in neonatal Peking ducklings as a function of environmental stimulation.

Neonatal Peking ducklings were reared in 3 different environments containing varied light and sound stimulation. One group was exposed to the stimulative environment only during the last 3 prenatal days, 1 group was placed in the stimulative environment at the time of hatching, and the 3rd group was exposed to the stimulative environment both pre- and postnatally. No differences in performance in a detour learning task were noted between controls and experimentals from the 1st 2 groups (prenatal stimulation only and postnatal stimulation only); however, the group receiving both pre- and postnatal stimulation solved the detour task significantly faster than their controls. This learning improvement as a function of the stimulative environment represents a partial recovery from the deficit produced as a result of the experimental paradigm in which the shell covering the air space was replaced with clear plastic wrap, a procedure which has been shown to reduce oxygen consumption and lead to learning retardation.

Animals↗
PubMed1980

Learning deficits in the neonatal Peking duckling produced by decreased oxygen consumption during late prenatal periods: a cautionary note.

Neonatal Peking ducklings were tested in a detour problem-solving task following replacement of the shell overlying the air space of the egg on Prenatal Day 24 (total incubation period: 27 days) with a plastic wrap. This procedure, a common practice in behavioral embryology, resulted in a significant decrease in oxygen consumption, and a protracted retardation in the mastery of the learning task, with experimental ducklings solving the problem at a mean age of 5.27 days, compared with 2.32 days for controls. These results serve to underscore the problems that may be encountered as a result of any interference with the integrity of the egg during the prenatal period.

Animals↗
PubMedDate not supplied

Lipopolysaccharide facilitates partner preference behaviors in female prairie voles.

Exposure to proinflammatory cytokines (e.g., IL-1beta) or lipopolysaccharide (LPS) produces an acute activation of the immune response and results in a repertoire of behavioral patterns collectively termed sickness behaviors. Although nonspecific responses to pathogenic infection have traditionally been viewed as maladaptive effects of infection, sickness behaviors may have significant, adaptive value for the host. One set of adaptive behaviors affected by infection among mammals and birds is mate choice. In Experiment 1, female prairie voles exhibited the expected increase in blood corticosterone concentrations in response to a 0.1 cc i.p. LPS injection (50 microg), indicating activation of the endocrine system. A separate cohort of females was injected with LPS or saline and paired for 6 h with a novel, previously unpaired male. Following the cohabitation period, LPS-injected females spent significantly more time (p < 0.05) with the familiar partner when given a choice between familiar and unfamiliar males in a three-chamber apparatus designed to test partner preferences. Saline-injected females spent significantly more time with the unfamiliar male. In Experiment 2, males injected with LPS or saline spent equal amounts of time with familiar and unfamiliar females following a 6 h cohabitation with a naive female, and therefore, did not exhibit preferences. From a proximate perspective, this study provides evidence that sickness behaviors influence female, but not male, partner preference in prairie voles.

Animals↗
PubMedDate not supplied

Hormonal and immunological mechanisms mediating sex differences in parasite infection.

The prevalence and intensity of infections caused by protozoa, nematodes, trematodes, cestodes, and arthropods is higher in males than females. The primary thesis of this review is that immunological differences exist between the sexes that may underlie increased parasitism in males compared to females. Several field and laboratory studies link sex differences in immune function with circulating steroid hormones; thus, the roles of sex steroids, including testosterone, oestradiol, and progesterone, as well as glucocorticoids will be discussed. Not only can host hormones affect responses to infection, but parasites can both produce and alter hormone concentrations in their hosts. The extent to which changes in endocrine-immune interactions following infection are mediated by the host or the parasite will be considered. Although males are more susceptible than females to many parasites, there are parasites for which males are more resistant than females and endocrine-immune interactions may underlie this sex reversal. Finally, although immunological differences exist between the sexes, genetic and behavioural differences may explain some variability in response to infection and will be explored as alternative hypotheses for how differences between the sexes contribute to dimorphic responses to parasites.

Behavior↗
PubMedDate not supplied

Conscious sedation for procedures under local or topical anesthesia.

For many surgical procedures in otolaryngology general anesthesia is not required, but it is difficult to block completely all noxious sensations with local or topical anesthesia. Intravenously administered antianxiety and analgesic drugs can make the procedure more tolerable for the patient. A technique of conscious sedation based upon titrating diazepam to specific eye signs and fentanyl to specific end points is described. Safety is maintained by ensuring that the patient is always in verbal contact with the surgeon. The rationale for administering the sedative before the narcotic is presented along with the treatment of side effects and untoward responses to the drugs.

Administration, Topical↗
PubMedDate not supplied

Effects of hemorrhage on regional cerebral blood flow in awake and in isoflurane-anesthetized rats.

During hemorrhage, redistribution of cerebral blood flow may occur. We compared the effects of hemorrhage on regional cerebral blood flow in awake rats and in rats anesthetized with 1% or 2% isoflurane. In half of each group, regional cerebral blood flow was measured without hemorrhage. The other half was slowly bled to a mean arterial blood pressure of 40-45 mm Hg before measuring the regional cerebral blood flow. Without hemorrhage, the cortical regional blood flow was greater in the awake animals than that of the caudal part of the brain. In the 2% isoflurane group, however, the regional cerebral blood flow of the caudal part was greater than the cortical regional cerebral blood flow. After hemorrhage, a similar decrease (-45%) of the regional cerebral blood flow was observed in each brain region and the pattern of distribution of it remained unchanged in all experimental groups. However, the absolute value of the cortical flow was higher in the awake animals than in the isoflurane groups. Our experiment demonstrated that hemorrhage decreased the regional cerebral blood flow. However, it did not alter the redistribution of the cerebral blood flow in awake animals nor in the animals anesthetized with isoflurane.

Anesthesia↗