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Biomedical subjects

S Arnold

Publications and source records attributed to S Arnold.

190 records · Page 11Linked to original sources
PubMedDate not supplied

Peptidergic transmission in the brain. V. Systemic correlates of central activation.

Inhibition of the hippocampus by the medial amygdala is mediated by vasopressin-like peptide. Because vasopressin has action on the periphery as well as the brain, we conducted experiments to evaluate the relationship between possible peripheral actions and the central effects of the endogenous peptide. In the acutely anesthetized rat, peptide-mediated inhibition of the hippocampus is not associated with significant changes in heart rate, blood pressure or body temperature. Peripheral injections of peptide agonist fail to evoke the central inhibition, and peripheral injections of peptide antagonist fail to block the central inhibition. Stimulation of central nuclei that contain vasopressin or a similar peptide also fail to duplicate the effect of stimulating the amygdala. We conclude that the peptidergic transmission is independent of peripheral causes or correlates.

Amygdala↗
PubMedDate not supplied

Peptidergic transmission in the brain. IV. Sex hormone dependence in the vasopressin/oxytocin system.

The medial amygdaloid nucleus (AME) synthesizes a peptide similar to arginine vasopressin and projects peptidergic fibers to the ipsilateral hippocampus in the male rat. In previous studies, we have shown that the peptide acts as a transmitter and, using in vitro and in vivo electrophysiology, we have characterized its mechanism of action. Previous anatomical work has shown that the peptidergic fibers are more dense in male rats than females and are obliterated entirely by castration. Here we report the results of our attempt to find an electrophysiological correlate of these anatomical findings. First, we show specific mediation by a vasopressin- or oxytocin-like peptide by use of a structural vasotocin antagonist. Then we show that castration obliterates the peptidergic signal in males. However, we were unable to find any sex difference that corresponded to the male/female disparity noted in the density of the peptidergic fibers. The strength, nature and stimulus-response characteristics were the same between males and females. Apart from a very subtle difference in the duration of the signal, no physiological correlate of the sexual dimorphism could be found with our techniques. We conclude that the neurophysiology partly complements the anatomy and biochemistry of this system.

Amygdala↗
PubMedDate not supplied

Functional MRI of language-related activation in left frontal schizencephaly.

Brain activation associated with covert verb generation was studied in a right-handed patient with an asymptomatic left frontal schizencephaly by functional magnetic resonance imaging. Activation of the dysplastic neuronal tissue lining the cleft and the adjacent cortex was found, indicating participation of the malformed region in physiologic cerebral functions. This finding may have clinical impact in patients with medically intractable seizures due to malformations of the cortical development prior to epilepsy surgery.

Adult↗
PubMedDate not supplied

Surgical treatment of male dogs with urinary incontinence due to urethral sphincter mechanism incompetence.

A modified technique for fixation of the deferent ducts to the abdominal wall as a therapy for urinary incontinence caused by urethral sphincter mechanism incompetence (USMI) in male dogs is described, and the results in seven dogs are reported. The goal of this treatment was to achieve an effect similar to colposuspension in female dogs with USMI. An increase in urethral length of an average of 28 mm was obtained (range, 5 to 50 mm, measured radiographically). Preoperatively, the neck of the bladder was located intrapelvically in five of seven dogs. Postoperatively, the neck of the bladder was located intra-abdominally, near the caudo-ventral abdominal wall, in all dogs. After a follow-up period of 12 to 49 months, the response to surgery, based on lack of or decrease of incontinence, was excellent in three dogs, good in another three, and poor in one dog.

Animals↗
PubMedDate not supplied

Career paths of geriatric nurse practitioners employed in nursing homes.

The career paths of geriatric nurse practitioners (GNPs) trained with support from the W. K. Kellogg Foundation through the Mountain States Health Corporation (MSHC) were studied. Under this program, GNPs were recruited from sponsoring nursing homes and returned to GNP positions in the sponsoring facilities following training. Training was carried out under a continuing education model offered through six university-based schools of nursing. Questionnaires were sent to the 111 GNPs trained. Of the 102 respondents, 97 provided complete information about past and present education, work experience, and job functions. The GNPs were women with a median age of 45 years, and they were employed in rural settings in the western United States. More than 45 percent of the nurses had at least a baccalaureate degree at the time of GNP training. The GNPs remained employed in long-term care positions that implemented the practitioner role. The median length of GNP employment in their first jobs after training was more than 4.5 years. The resignation rate from this first position was 1.66 resignations for each 10 years of GNP employment. Job changes were likely to be attributed to organizational changes with subsequent positions shifting toward a diversification of the GNP role. The study demonstrates the success of the MSHC program in introducing and retaining GNPs in nursing homes.

Career Mobility↗
PubMedDate not supplied

Preparing children for a surgical experience.

1. Little research has been conducted on the specific fears of children undergoing surgery. One study reported that the events most remembered about the surgical experience were riding to the operating room, receiving injections, waking up in pain, and not being allowed to eat or drink. The most feared events were injections and the anesthesia mask. 2. Many hospitals have developed formal and informal orientation programs for preparing children for surgery. Special orientation days with themes may be offered. Films/videos, slide presentations, coloring books, photograph albums, puppet shows, and tours often are used to introduce the child to the surgical environment. A visit to the operating room may be a part of the program. In some cases, play therapy in a mock operating room is used. 3. A warm, open, honest environment is crucially important. There should be a willingness to discuss the child's ideas, fears, and misconceptions concerning their perioperative experience. In addition, children should be given the opportunity to learn about their body, the health care profession, and the surgical setting.

Adolescent↗
PubMedDate not supplied

Effects of novel and conventional anti-cancer agents on human endothelial permeability: influence of tumour secreted factors.

A number of anti-cancer agents have been implicated in vascular toxicity. The effects have been attributed to direct drug toxicity towards endothelium. Little attention has been focussed on the interaction between anticancer drugs, endothelial cells and tumour secreted factors. It is well known that tumours can secrete factors such as vascular permeability factor which do affect endothelial cells and could alter their response to the vascular effects of anticancer drugs. In the present study, we have examined, in vitro, the direct effects of vinblastine (VBL), 5-fluorouracil (5-FU), melphalan (L-PAM) and the novel tubulin inhibitor combretastatin A-1 (CBS) on endothelial permeability under normal and tumour simulated conditions. Monolayers of human umbilical vein endothelial cells (HUVEC) grown on membrane filters were incubated in drug in normal growth medium or medium conditioned by the human melanoma cell line, RPMI-7951 (TCM). VBL caused a rapid increase in permeability during the first 20 minutes, which was maintained for the duration of the experiment (120 minutes). The effect was not altered by TCM or restored to control levels when VBL was replaced by drug-free medium. Similarly, CBS caused a rapid increase in permeability; however, in contrast to VBL, this increase was enhanced by TCM. The changes induced by VBL and CBS were accompanied by contraction of the endothelial F-actin cytoskeleton. Neither L-PAM nor 5-FU altered the permeability of HUVEC monolayers. This study demonstrates that certain anti-cancer agents have a direct effect on endothelial cells, leading to an increase in the permeability of endothelial monolayers. Both VBL and CBS have vascular components in their mode of action which may lead to vascular collapse and tumour necrosis.

Antineoplastic Agents↗