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Biomedical subjects

L Jacobson

Publications and source records attributed to L Jacobson.

At least 145 records · Page 8Linked to original sources
PubMed1991

A prospective study of intraoperative pulse oximetry failure.

Since pulse oximetry is now an ASA standard for intraoperative monitoring, we sought to determine the intraoperative failure rate for this device. We prospectively evaluated the intraoperative failure rate of our pulse oximeters at the four University of Washington Hospitals (University of Washington Medical Center, Veterans Affairs Medical Center [VAMC], Children's Hospital and Medical Center, and Harborview Medical Center [HMC]) recorded from April 1989 to August 1989. We defined failure as the inability to obtain any oximetry reading for a cumulative period of more than 30 minutes during any anesthetic procedure after all equipment malfunctions had been eliminated. Our puse oximeters failed in 124 of 11,046 cases studied; this is a failure rate of 1.12%, which ranged from 0.56% at HMC to 4.24% at VAMC. The failure rate at VAMC (4.24%) was significantly higher than the other hospitals (p less than 0.001). Those cases associated with the pulse oximeter failure had the following characteristics: (1) an ASA status of 3 or higher, (2) lengthy operations, and (3) elderly patients. When the device did fail in a patient, it did not function for 32% of the mean anesthesia time. We conclude that the intraoperative use of the pulse oximetry can provide information about blood oxygen saturation in most patients. However, in approximately 1% of the patients we studied in the operating room, mechanically functioning pulse oximeters failed to provide readings of blood oxygen saturations during routine operative use.

Equipment Failure↗
PubMed1991

Regulation of basal ACTH secretion by corticosterone is mediated by both type I (MR) and type II (GR) receptors in rat brain.

The mechanisms involved in the physiology of the secretion of ACTH are reviewed. The secretion is regulated by the biological consequences of the occupancy of high affinity mineralocorticoid (MR) and lower affinity glucocorticoid receptors (GR) for corticosterone at specific sites of the rat brain. The regulation by this mechanism of basal secretion during the circadian rhythm, the effect of adrenalectomy and of corticosterone replacement is discussed. Experiments with RU486, a specific glucocorticoid antagonist, suggest that occupancy of both MR and GR is required for normal control of ACTH at the time of peak activity. The occupancy of the GR for a few hours per day apparently suffices to maintain steady levels of the products of GR-responsive genes throughout the body.

Adrenal Glands↗
PubMed1991

An objective comparison of intrathecal lidocaine versus fentanyl for the treatment of lower extremity spasticity.

The reduction of spasticity after administration of intrathecal fentanyl, 35 micrograms, and intrathecal lidocaine, 50 mg, was compared with preinjection spasticity levels in ten subjects with central nervous system disease or injury. Spasticity was objectively assessed by an electronic instrument that simultaneously measures degrees of extension and force during passive knee extension. Duration of spasticity relief and adverse effects were recorded. Both drugs equally reduced spasticity and increased the range of motion. There were no supraspinal side effects from the fentanyl, whereas three subjects became hypotensive after receiving lidocaine. The reduction of spasticity with intrathecal fentanyl lasted at least 3 h. The authors postulate that fentanyl reduced spasticity by an effect on spinal pathways. Intrathecal fentanyl should be considered as an alternative to lidocaine for diagnostic blocks in patients with spasticity.

Adult↗
PubMed1991

The role of the hippocampus in feedback regulation of the hypothalamic-pituitary-adrenocortical axis.

There is considerable, although not entirely consistent, evidence that the hippocampus inhibits most aspects of HPA activity, including basal (circadian nadir) and circadian peak secretion as well as the onset and termination of responses to stress. Although much of the evidence for these effects rests only on the measurement of corticosteroids, recent lesion and implant studies indicate that the hippocampus regulates adrenocortical activity at the hypothalamic level, via the expression and secretion of ACTH secretagogues. Such inhibition results largely from the mediation of corticosteroid feedback, although more work is required to determine whether the hippocampus supplies a tonic inhibitory input in the absence of corticosteroids. It must be noted that the hippocampus is not the only feedback site in the adrenocortical system, since removal of its input only reduces, but does not abolish, the efficacy of corticosteroid inhibition, and since other elements of the axis appear eventually to compensate for deficits in feedback regulation. The importance of other feedback sites is further suggested not only by the presence of corticosteroid receptors in other parts of the brain and pituitary, but also by the improved prediction of CRF levels by combined hypothalamic and hippocampal receptor occupancy. The likelihood of feedback mediated by nonhippocampal sites underscores the need for future work to characterize hippocampal influence on HPA activity in the absence of changes in corticosteroid secretion. However, despite the fact that the hippocampus is not the only feedback site, it is distinguished from most potential feedback sites, including the hypothalamus and pituitary, by its high content of both type I and II corticosteroid receptors. The hippocampus is therefore capable of mediating inhibition over a wide range of steroid levels. The low end of this range is represented by corticosteroid inhibition of basal (circadian nadir) HPA activity. The apparent type I receptor specificity of this inhibition and the elevation of trough corticosteroid levels after hippocampal damage support a role for hippocampal type I receptors in regulating basal HPA activity. It is possible that basal activity is controlled in part through hippocampal inhibition of vasopressin, since the inhibition of portal blood vasopressin correlates with lower levels of hippocampal receptor occupancy, and the expression of vasopressin by some CRF neurons is sensitive to very low corticosteroid levels. At the high end of the physiological range, stress-induced or circadian peak corticosteroid secretion correlates strongly with occupancy of the lower affinity hippocampal type II receptors.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Cortex↗
PubMed1991

Normative data for a brief neuropsychological screening battery. Multicenter AIDS Cohort Study.

This study reports normative data for a group of 733 homosexual/bisexual men stratified by age (range 25 to 54 years) and by education on the following six neuropsychological tests: (1) Digit Span (WAIS-R), (2) Rey Auditory Verbal Learning Test, (3) Symbol Digit Modalities Test, (4) Controlled Oral Word Association Test, (5) Grooved Pegboard, and (6) The Trail Making Test. Analysis demonstrates that both age and education are important determinants of performance for several of these measures.

AIDS Dementia Complex↗
PubMed1991

An antagonist to vasoactive intestinal peptide affects cellular functions in the central nervous system.

A vasoactive intestinal peptide (VIP) antagonist was synthesized and used to investigate the interactions of VIP with its receptors present in the central nervous system (CNS). The VIP antagonist is a hybrid peptide consisting of a portion of VIP and a portion of neurotensin, designed to change the membrane permeability of the VIP portion. The hybrid antagonist displaced 80 to 90% of [125I]VIP binding to cell cultures from cerebral cortex, hippocampus or spinal cord. The displacement curve was biphasic, suggesting two binding sites. In the case of cortical astrocytes, the antagonist had a Ki of 45 pM at one site and a Ki of 74 nM at the other. At the lower affinity binding site, the antagonist was about 10-fold more potent than VIP in displacing radiolabeled VIP. The accumulation of cyclic AMP (cAMP) in VIP-stimulated cortical glia cultures was decreased by the new antagonist (EC50, 59 nM). This decrease in cAMP was greater than that achieved in the presence of other putative VIP antagonists. Finally, the addition of 1 nM hybrid antagonist to dissociated spinal cord cultures resulted in a 42% reduction in neuronal cell counts as compared with controls, and the EC50 of this effect was about 30 pM, which corresponded closely to the Ki of antagonist displacement of [125I]VIP binding at the high-affinity site. The antagonist appears to be a competitive blocker for both VIP-mediated increases in cAMP formation or VIP-associated maintenance of neuronal survival in spinal cord cultures. Thus, we describe a potent VIP antagonist which interacts with two functionally distinct VIP receptors in the CNS.

Amino Acid Sequence↗
PubMed1991

Cognitive skills & development competencies for conducting research critiques.

As the nursing profession expands its unique scientific body of knowledge, it is essential that all professional nurses become capable of evaluating the scientific and clinical merits of this information generated by nursing research. Three developmental levels of research critique skills are delineated by the nurse reader's competencies: novice, intermediate, and advanced. Each developmental level is described in relation to five cognitive skills which underlie the proposed competencies: knowledge, comprehension, analysis, evaluation, and synthesis.

Education, Nursing↗
PubMed1991

The dynamic flexometer: an instrument for the objective evaluation of spasticity.

Anesthesiologists may care for patients who have spasticity in the operating room or pain clinic. A number of therapeutic modalities for treatment of spasticity exist, but there are few simple objective methods for evaluating their effect. We describe one instrument, the Dynamic Flexometer, that measures the force required to move the limb passively through its maximum range of motion. The data presented validate the instrument's reliability. Two clinical cases presented here demonstrate the instrument's utility. This device may be of value to anesthesiologists involved in the care of patients with spasticity.

Disability Evaluation↗
PubMed1991

Physician-nurse collegiality in the medical school curriculum: exploratory workshop and student questionnaire.

Medical education is the key to improvements in physician-nurse relationships and communication. The results of a workshop for second-year medical students on collegiality organized by The Mount Sinai Hospital Department of Nursing and the Mount Sinai School of Medicine are presented. The workshop follow-up roundtable discussion is summarized and the results of a survey of medical students' perception of professional nursing are presented.

Adult↗
PubMed1990

Cardiovascular effects of acute changes in extracellular ionized calcium concentration induced by citrate and CaCl2 infusions in chronically instrumented dogs, conscious and during enflurane, halothane, and isoflurane anesthesia.

To study the cardiovascular effects of low blood ionized calcium ion concentrations [Ca2+] induced by citrate infusion followed by high [Ca2+], induced by CaCl2 infusion awake and during enflurane (2.5% ET), halothane (1.2% ET), and isoflurane (1.6% ET) anesthesia, dogs were chronically instrumented to measure heart rate, aortic, left atrial, and left ventricular (LV) blood pressures, and cardiac output. In conscious dogs low [Ca2+] (decreased 0.35 mM); increased heart rate (HR) and mean aortic pressure (MAP) and decreased stroke volume (SV) and LV dP/dtmax. Low [Ca2+] increased HR during all three anesthetics and decreased LV dP/dtmax except during isoflurane anesthesia. Low [Ca2+] produced more hemodynamic depression during enflurane anesthesia than during anesthesia with halothane or isoflurane increasing left atrial pressure and decreasing MAP and SV. The differences seen were partially related to decreased systemic vascular resistance during halothane and isoflurane anesthesia. In conscious dogs following high [Ca2+] (increased 0.37 mM); only MAP and LV dP/dtmax increased. LVdP/dtmax was also increased by high [Ca2+] during all three anesthetics without a change in MAP. Cardiac output increased during halothane and isoflurane anesthesia but was unchanged during enflurane. It would appear that the hemodynamic sensitivity for the effects of changing [Ca2+] was enflurane greater than halothane greater than isoflurane greater than awake. The results suggest that the effects of changes in [Ca2+] induced by citrate and CaCl2 infusion are modified by the three volatile anesthetics.

Anesthesia, Inhalation↗
PubMed1990

Induction of fos-like immunoreactivity in hypothalamic corticotropin-releasing factor neurons after adrenalectomy in the rat.

To identify brain sites responding to the removal of corticosterone feedback by adrenalectomy (ADX), rat brains were processed for fos immunocytochemistry 1, 3, and 7 days after ADX, sham-ADX, or no surgery using a polyclonal antiserum to fos residues 132-154. Compared to SHAM, ADX rats exhibited strong fos-like immunoreactivity (FLI) only in the parvocellular neurons of the paraventricular hypothalamic nuclei (PVN) 1, 3, and 7 days after surgery. Replacement with a corticosterone pellet at the time of adrenalectomy (ADX + B) prevented this increase in PVN FLI in three of four rats at 1 day, all rats at 3 days, and two of seven rats 7 days after surgery; 100 micrograms/ml corticosterone in the drinking water for 2 days before perfusion reversed ADX-induced increases in PVN FLI in 7-day ADX rats. Providing 25 micrograms/ml corticosterone in the drinking water to ADX rats for 5 days after surgery did not prevent expression of PVN FLI, even though this dose has been shown to normalize morning basal ACTH levels in ADX rats. Virtually all parvocellular PVN neurons expressing FLI after ADX costained for CRF. Some parvocellular neurons also expressed both fos and vasopressin. In all rats, many brain regions expressed FLI that was not related to adrenalectomy. We conclude that the changes in neuronal FLI correlate with demonstrated changes in neuroendocrine activity after ADX; however, suppression of ADX-induced FLI may require higher replacement levels of corticosterone than inhibition of ADX-induced ACTH secretion.

Adrenalectomy↗
PubMed1990

The effect of fresh lymphocytes on increased sensitivity of HIV-1 isolation: a multicenter study.

A multicenter study was undertaken to determine the sensitivity and reproducibility of markers for human immunodeficiency virus type 1 (HIV-1) viral growth and the effect of various preparations of lymphocytes on the sensitivity of standard and routinely used procedures for HIV-1 isolation. In phase 1, cocultivated culture supernatants obtained from 10 HIV-1 cultures were transported to three Multicenter AIDS Cohort Study (MACS) Virology Laboratories. Three commercial HIV-p24 antigen capture (AC) tests and two reverse transcriptase (RT) assays were used to ascertain the replication of HIV-1. The Du Pont and Abbott AC assays were found to be most sensitive (85-100%), and the RT assay with 24-h incubation period had comparable sensitivity (75-100%). In phase II, the sensitivity of standard cocultivation procedure for HIV-1 isolation was compared using freshly phytohemagglutinin-P (PHA-P)-stimulated, stimulated-frozen, and frozen-thawed and then stimulated normal human peripheral blood mononuclear cells (PBMCs) as cocultivating cells. Blood samples from 13 HIV-1 infected individuals with various CD4+ cell counts were cocultivated in each of the three MACS laboratories using one of the aforementioned normal PBMCs. The PHA-P-stimulated fresh normal PBMC showed a maximum isolation rate of 100% (13 of 13) with an average of 8 days to positivity. This rate of isolation was significantly greater than other rates using any one of the other PBMC preparations. These findings demonstrated that the use of freshly PHA-P stimulated PBMCs maximized HIV-1 isolation from blood when a sensitive HIV-1 p24 AC assay or RT assay with overnight incubation is employed for the detection of HIV in culture supernatant.

Blood Preservation↗
PubMed1989

The group as an object in the cultural field.

This paper illuminates the interplay between group and individual processes by exploring members' notions of the group itself. What members hold in common about the "group" is understood as an object in the cultural field, which is a particular kind of transitional phenomenon (Winnicott). The paper connects this notion to Bion's concept of "basic assumptions," and describes members' motivations for creating the "group" as well as its role in the psychotherapy group. The object in the cultural field is then further elaborated in its more general role in the relation between the individual and the group, which leads to a consideration of psychotherapy groups in terms of their value in facilitating living in the social world.

Culture↗
PubMed1989

Intrathecal fentanyl depresses nociceptive flexion reflexes in patients with chronic pain.

To investigate the selective role of intraspinal opioids on the perception and modulation of pain, seven subjects with chronic hip or back pain and one subject with C-6 quadriplegia received 25 micrograms of intrathecal fentanyl. The effect of lumbar intrathecal fentanyl on reported pain, nociceptive flexor withdrawal reflexes, a monosynaptic motor arc (H-reflex), and supraspinal effects such as miosis, nausea, respiratory depression was evaluated. In five of eight subjects the flexor withdrawal reflex was completely abolished within 15 min. In the others the reflex was significantly depressed from control values. Decreases in reported pain paralleled the decrease in the flexor reflex, H-reflexes remained unchanged, and no supraspinal side effects were observed. It is likely that these selective changes observed were from the isolated effect of fentanyl modulating nociception at the spinal cord level.

Aged↗