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Biomedical subjects

B A Weiss

Publications and source records attributed to B A Weiss.

18 recordsLinked to original sources
PubMed2006

Creatine supplementation does not impair the thermoregulatory response during a bout of exercise in the heat.

AIM: The aim of this work was to examine the effects of creatine (Cr) supplementation on resting body water volumes and on core temperature and sweat loss during a bout of exercise in a warm environment. METHODS: Twenty-four aerobically trained male subjects (age 22.93+/-3.01 years, height 179.52+/-7.28 cm, mass 82.06+/-14.32 kg) volunteered to participate in this study. Each subject was assessed for resting body water volumes and for body mass (BM), heart rate (HR), blood pressure (BP), and core temperature immediately before and following a 60-min bout of exercise in a warm environment. Core temperature, HR, and BP were also recorded at 10-min intervals during exercise. Subjects were then randomly assigned to either a Cr or placebo (P) group. Each subject returned following a 5-day supplementation period and was reassessed using identical testing procedures. BM was measured using a standard electronic scale. Body water volumes were assessed using a multi-frequency BIS (Xitron Technologies, San Diego, CA, USA). Core body temperature was measured using a CorTemp Disposable Temperature Sensor and a CT2000 Miniaturized Ambulatory Recorder (HTI Technologies, Inc., Palmetto, FL, USA). RESULTS: The Cr group experienced a significant increase in all body water volumes. No changes were observed in the P group. No changes in core temperature or sweat loss were observed in either group following supplementation. CONCLUSIONS: Cr loading did not impair the thermoregulatory response during a bout of exercise in the heat.

Adult↗
PubMed1995

Biological parents regaining their rights: a psycholegal analysis of a new era in custody disputes.

The evolving American family presents new psycholegal dilemmas. Recently many publicized landmark cases have involved custody disputes in which settlements turn on the genetic component. Although the court acknowledges the principle of "the best interest of the child" as important to the determination of custody, this interest is not absolutely paramount. Court rulings have taken the position that the rights of biological parents are a threshold issue that must be resolved first. Thus, children may be removed from their adoptive and psychological parents through a court order. The authors present a psycholegal analysis of important cases with a guideline for the future.

Adolescent↗
PubMed1994

Bringing baby home: a comprehensive case management program for obstetrical services.

Originally presented to the Society of Home Health Care Management of the American College of Physician Executives at its November 16, 1993, meeting in Tucson, Ariz., the program described in this article was the winner of the College's 1994 Innovations Award in Medical Quality Management, sponsored by Merck Sharp & Dohme. The program shows the potential of case management for both improvement in the quality of care and containment of costs for a managed care population with a substantial Medicaid segment. This article is part of a continuing series on innovative programs in home health care.

Awards and Prizes↗
PubMed1991

Intracellular Ca2+ and protein kinase C interact to regulate alpha 1-adrenergic- and bradykinin receptor-stimulated phospholipase A2 activation in Madin-Darby canine kidney cells.

Alpha 1-Adrenergic receptors and bradykinin receptors are two distinct membrane receptors that stimulate phospholipid breakdown and arachidonic acid and arachidonic acid metabolite release. In the current studies, we have examined several mechanisms to assess their possible contribution to arachidonic acid release in the Madin-Darby canine kidney cell line by agonist stimulation of these receptors: 1) activation of phospholipase A2 (PLA2); 2) sequential activation of phospholipase C, diacylglycerol lipase, and monoacylglycerol lipase; and 3) inhibition of the sequential action of fatty acyl-CoA synthetase and lysophosphatide acyltransferase. Experiments were conducted to measure the stimulation of lysophospholipid production by epinephrine and bradykinin, the rate of incorporation of [3H]arachidonic acid into stimulated and unstimulated cells, and the effect on [3H]arachidonic acid release of treating cells with exogenous phospholipase C. The data indicate that stimulation of PLA2 activity is regulated by alpha 1-adrenergic and bradykinin receptors and that this stimulation is mediated, at least in part, by the activation of protein kinase C. We find that the role of diacylglycerol in arachidonic acid release is as an activator of protein kinase C and not as a substrate for a lipase. Moreover, the hormonal agonists do not appear to inhibit fatty acid reacylation. Experiments using the Ca2(+)-sensitive dye fura-2 and the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid suggest that bradykinin activates PLA2 by a transient elevation of intracellular Ca2+. This action appears to be less important for activation of PLA2 by epinephrine. Taken together, these data are consistent with the following conclusions. 1) Hormone-stimulated arachidonic acid release in Madin-Darby canine kidney-D1 cells occurs as a consequence of PLA2 activation. 2) The ability of an agonist both to mobilize Ca2+ and to activate protein kinase C contributes to its efficacy as a stimulator of PLA2-mediated arachidonic acid release.

Animals↗
PubMed1990

Differential activation of protein kinase C alpha is associated with arachidonate release in Madin-Darby canine kidney cells.

The heterogeneity of the protein kinase C (PKC) gene family strongly suggests that different isoforms may have distinct functions in mediating signal transduction. However, there is very little direct evidence for this. PKC has been implicated in arachidonate (AA) release in many cell types. We sought to investigate whether bradykinin- and phorbol ester-stimulated AA release in Madin-Darby canine kidney (MDCK) cells was correlated with differential activation of PKC isoforms. Using phorbol esters to (i) activate the enzyme and (ii) to down-regulate it, we report that differential activation (translocation) of PKC alpha is associated with AA release in MDCK cells and that specific down-regulation of PKC alpha is associated with a loss of AA release in response to stimulation with dioctanoylglycerol and phorbol ester. We also demonstrate that bradykinin-stimulated AA release was associated with differential activation of PKC alpha and was inhibited in PKC alpha down-regulated cells. Thus, we conclude that the PKC alpha isoform is likely to be responsible for mediating AA release in these cells.

Animals↗
PubMed1989

Injectable cross-linked collagen with improved flow properties.

Aqueous suspensions of glutaraldehyde cross-linked fibrillar collagen and non-cross-linked fibrillar collagen were examined by rheometry, particle size analysis, and microscopic techniques. Although cross-linked collagen suspensions were similar to non-cross-linked suspensions by microscopic and size analyses, they differed in rheometric properties. Concentric cylinder Couette flow, shear creep, uniaxial creep, and porous bed flow all revealed that cross-linked collagen was more resistant to deformation and flow than non-cross-linked collagen. These results were in agreement with in vivo dermal implantation studies, both in pig and human; i.e., compared to non-cross-linked collagen, the cross-linked formulation was more difficult to inject into tissue and did not spread uniformly, sometimes giving rise to palpable lumps or large masses evident in histological sections. When hyaluronic acid was blended with cross-linked collagen to achieve a final hyaluronate concentration of 5 mg/mL, there was a significant improvement in ease of injection into tissue. Rheometry on blends of hyaluronate and cross-linked collagen demonstrated that the blend required lower forces to achieve deformation and flow, compared to cross-linked collagen alone. Particle size analysis on the blend showed a reduction in fiber aggregate dimensions, compared to cross-linked collagen alone.

Animals↗
PubMed1989

AIDS and confidentiality: legal concept and its application in psychotherapy.

Persons with positive HIV appear to have the same right to confidentiality as other medical psychiatric patients. The ethical and legal duties of practitioners who learn that their HIV positive patients are endangering others is discussed. The essential policies of the CDC, AMA, and APA are reviewed along with the current legal situation. One conclusion reached is that applying the Tarasoff doctrine to warn/protect a third party, if that party may already be infected, is useful only when the third party is moral and sensible enough to cease behavior that would spread the disease to others.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Defining the role of protein kinase C in epinephrine- and bradykinin-stimulated arachidonic acid metabolism in Madin-Darby canine kidney cells.

Madin-Darby canine kidney cells (MDCK) are known to release free arachidonic acid and arachidonic acid metabolites (AA) in response to tumor-promoting phorbol esters, such as tetradecanoyl phorbol-13-acetate, and to agonists active at alpha 1-adrenergic and bradykinin B2 receptors. These experiments were conducted to define the role of Ca2+/phospholipid-dependent protein kinase (protein kinase C) activation in the stimulation of AA release, in the clonal isolate cell line MDCK-D1, by use of three inhibitors of protein kinase C, sphingosine, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), and staurosporine. We found that alpha 1-adrenergic- and bradykinin-stimulated [3H]AA release can be distinguished by differential dependence on protein kinase C; epinephrine-stimulated release was more dependent on protein kinase C activation than was bradykinin-stimulated release. The inhibition of bradykinin-stimulated AA release by sphingosine (20.2 +/- 6.1%) was substantially less than the inhibition observed for tetradecanoyl phorbol-13-acetate- (67.2 +/- 5.5%) and epinephrine-stimulated release (50.2 +/- 9.2%). These findings were confirmed by results using H-7 and staurosporine. The relative independence of bradykinin-stimulated AA release of protein kinase C was also demonstrated by the inability of phorbol ester-induced down-regulation of protein kinase C to eliminate bradykinin-stimulated AA release. The inhibition of alpha 1-adrenergic receptor-mediated AA release by sphingosine, H-7, and staurosporine was not due to a change in receptor number or affinity. Analysis of the products comprising [3H]AA release indicated that treatment with sphingosine did not change the composition of the released AA (34-48% prostaglandin E2, 17-27% free arachidonic acid, and 25-51% unidentified metabolites). These results indicate that two different types of hormone receptors in the same cell type can promote AA release by mechanisms that differ in their dependence on protein kinase C. The protein kinase C-dependent mechanism may represent protein kinase C-mediated activation of phospholipase A2.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1979

Evidence that the colored shadow effect is retinal.

Polarized lenses were employed to present the images of the colored shadows effect separately to each eye. The phenomenon was perceived only when both images were viewed on the same retina, leading to the conclusion that the effect is entirely retinal in origin and does not involve the central nervous system.

Cerebral Cortex↗
PubMed1979

Evidence that line illusions originate in the central nervous system.

Polarized lenses were employed to present the components of four line illusions separately to each eye. The phenomena were perceived even when both images were disparately presented, leading to the conclusion that the effect originates in the central nervous system and does not require the retina.

Brain↗
PubMed1969

Auditory sensitivity in the bullhead catfish (Ictalurus nebulosis).

The auditory sensitivity of 4 specimens of the bullhead catfish (Ictalurus nebulosis) was determined by shock-avoidance training in an aquatic shuttle box. The range of hearing extended from 100 to 4000 cycles per second, with the maximum sensitivity around 600 to 700 cycles per second.

Animals↗