Search PubMed⌕ Search

Biomedical subjects

J A Benson

Publications and source records attributed to J A Benson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Tracheal rupture in cats: 16 cases (1983-1998).

OBJECTIVE: To determine causes of tracheal rupture in cats and the mechanism of injury. DESIGN: A retrospective study was conducted to identify cats with tracheal rupture. A second study was conducted to establish mechanism of injury, and a third study was conducted to determine volume of air needed to obtain an airtight seal when inflating the cuff of an endotracheal tube in a cat. ANIMALS: 16 cats with clinical signs of tracheal rupture, 10 cat cadavers, and 20 clinically normal cats that were undergoing anesthesia. PROCEDURES: Details were extracted from medical records of 16 cats with tracheal rupture (9 treated surgically and 7 treated conservatively). For the cadaver study, the trachea of each cat cadaver was intubated and observed during overinflation of the endotracheal tube cuff. For clinically normal cats, volume of air needed to obtain an airtight seal for the endotracheal tube was recorded. RESULTS: Most ruptures were associated with cats anesthetized for dental procedures. Clinical signs associated with tracheal rupture included subcutaneous emphysema, coughing, gagging, dyspnea, anorexia, and fever. Tracheoscopy was the method of choice for documenting tracheal rupture. Surgical and conservative management were successfully used, unless the injury extended to the carina. In the cadaver study, overinflation of the endotracheal tube cuff with > 6 ml of air resulted in tracheal rupture in 7 of 10 cadavers. For clinically normal cats, the volume of air (mean +/- SD) needed to obtain an airtight seal was 1.6 +/- 0.7 ml. CLINICAL IMPLICATIONS: Overinflation of an endotracheal tube cuff may result in tracheal rupture in cats.

Anesthesia, Dental↗
PubMed1998

Pharmacology of recombinant gamma-aminobutyric acidA receptors rendered diazepam-insensitive by point-mutated alpha-subunits.

Amino acids in the alpha- and gamma-subunits contribute to the benzodiazepine binding site of GABA(A)-receptors. We show that the mutation of a conserved histidine residue in the N-terminal extracellular segment (alpha1H101R, alpha2H101R, alpha3H126R, and alpha5H105R) results not only in diazepam-insensitivity of the respective alphaxbeta2,3gamma2-receptors but also in an increased potentiation of the GABA-induced currents by the partial agonist bretazenil. Furthermore, Ro 15-4513, an inverse agonist at wild-type receptors, acts as an agonist at all mutant receptors. This conserved molecular switch can be exploited to identify the pharmacological significance of specific GABA(A)-receptor subtypes in vivo.

Amino Acid Sequence↗
PubMed1998

Postsynaptic clustering of major GABAA receptor subtypes requires the gamma 2 subunit and gephyrin.

Most fast inhibitory neurotransmission in the brain is mediated by GABAA receptors, which are mainly postsynaptic and consist of diverse alpha and beta subunits together with the gamma 2 subunit. Although the gamma 2 subunit is not necessary for receptor assembly and translocation to the cell surface, we show here that it is required for clustering of major postsynaptic GABAA receptor subtypes. Loss of GABAA receptor clusters in mice deficient in the gamma 2 subunit, and in cultured cortical neurons from these mice, is paralleled by loss of the synaptic clustering molecule gephyrin and synaptic GABAergic function. Conversely, inhibiting gephyrin expression causes loss of GABAA receptor clusters. The gamma 2 subunit and gephyrin are thus interdependent components of the same synaptic complex that is critical for postsynaptic clustering of abundant subtypes of GABAA receptors in vivo.

Animals↗
PubMed1996

Using information technology strategically in home care.

As home healthcare agencies examine new and innovative ways to deliver quality care more efficiently, the historical role of information technology as a way to automate clerical tasks will be significantly broadened to facilitate the true value of technology to home care providers. More importantly, a reduction in time spent on paperwork will allow agency caregivers to spend more time with clients. This article looks beyond the boundaries of desktop computing and examines the costs and benefits of network computing to develop strategic advantages for home healthcare agencies.

Community Health Nursing↗
PubMed1996

Pharmacological modulation of the diazepam-insensitive recombinant gamma-aminobutyric acidA receptors alpha 4 beta 2 gamma 2 and alpha 6 beta 2 gamma 2.

We characterized modulation of the gamma-aminobutyric acid (GABA)-evoked responses of the diazepam-insensitive alpha 4 beta 2 gamma2 and alpha 6 beta 2 gamma 2 recombinant GABAA receptors. The partial agonist bretazenil potentiated the responses of both receptors with similar dose dependence but with a higher maximal enhancement at the alpha 4 beta 2 gamma 2 receptor. The bretazenil-induced potentiation was reduced by the benzodiazepine antagonist flumazenil. At a high concentration (10 microM), flumazenil was a weak potentiator of the GABA response. The partial agonist imidazenil was inactive. The imidazobenzodiazepine inverse agonist Ro 15-4513, which is known to bind with high affinity to the alpha 6 beta 2 gamma 2 receptor, potentiated the GABA responses of the alpha 4 beta 2 gamma 2 and alpha 6 beta 2 gamma 2 receptor subtypes with similar dose dependence over the concentration range of 0.1-10 microM. Methyl-6, 7-dimethoxy-4-ethyl-beta-carboline, a beta-carboline inverse agonist, had a similar potentiating effect when tested at a concentration of 10 microM. The alpha 4 beta 2 gamma 2 and alpha 6 beta 2 gamma 2 receptor-mediated currents had equal sensitivities to furosemide and Zn2+ ions, both of which reduced the GABA-evoked responses. The alpha 6 beta 2 gamma 2 receptor but not the alpha 4 beta 2 gamma 2 receptor exhibited a low level of spontaneous activity in the absence of GABA; this resting current could be directly potentiated by Ro 15-4513, methyl-6,7-dimethoxy-4-ethyl-beta-carboline, bretazenil and flumazenil and was blocked by picrotoxin. Thus, although the alpha 4 beta 2 gamma 2 receptors are insensitive to benzodiazepine binding site full agonists, such as diazepam, they can be modulated by certain ligands acting as partial and inverse agonists at diazepam-sensitive receptors and thereby contribute to the respective pharmacological profiles.

Animals↗
PubMed1994

Expression of mRNA for the N-methyl-D-aspartate (NMDAR1) receptor by the enteric neurons of the rat.

In this study, in situ hybridization techniques were employed to map the distribution of enteric neurons which express mRNA for the glutamate N-methyl-D-aspartate receptor 1 (NMDAR1). We hybridized tissue sections from the stomach, duodenum, ileum and descending colon of adult rats with a 1.43-kB riboprobe cleaved from a clone of the NMDA receptor. Enteric neurons expressing the mRNA were found in both myenteric and submucosal ganglia at each of the sampling sites. Possible functions of NMDA receptors on enteric neurons are discussed.

Animals↗
PubMed1994

Rectal mucosectomy.

Explore the source record for details and available documents.

Colorectal Neoplasms↗
PubMed1993

Stoichiometry of a recombinant GABAA receptor deduced from mutation-induced rectification.

Ligand-gated ion channels generally display a heterooligomeric subunit structure. The present report describes an electrophysiological method that provides criteria indicating the subunit stoichiometry of a recombinant GABAA receptor composed of alpha 3, beta 2 and gamma 2 subunits. Our results exclude the stoichiometries 3 alpha 1 beta 1 gamma, 1 alpha 3 beta 1 gamma, 1 alpha 1 beta 3 gamma and suggest that the possible subunit stoichiometries for this receptor are 2 alpha 1 beta 2 gamma, 2 alpha 2 beta 1 gamma or 1 alpha 2 beta 2 gamma, of which the alpha subunit composition 2 alpha 1 beta 2 gamma may be favoured. The method is based on the quantification of the outward rectification of the GABA-evoked current induced by point mutation of charged amino acids located near the ion channel pore.

Amino Acid Sequence↗
PubMed1992

Integrating emerging disciplines.

The dynamics of medicine force us to continually update the content of residency curricula. Before selecting the material to be added or withdrawn from the curricula, goals for the desired product must be established. Further, the potential effects of emerging disciplines on the structure and composition of departments and residencies must be carefully considered. The Residency Review Committee for Internal Medicine (RRC-IM) is the principal instrument for forcing the integration of emerging disciplines into clinical education. Several questions must be considered when deciding how best to integrate these new disciplines. Should selected internists be designated to teach them? What are the most appropriate training sites? Which disciplines should be linked for pedagogic efficiency and relevance? How do we separate the educational pathways for generalists and subspecialists? The strategy of requiring additional training for a second certificate from the American Board of Internal Medicine (ABIM) has served internal medicine well for 50 years. Innovations in science and technology, however, are occurring at an accelerated pace. One solution may be to separate standardized residency training into multiple 4-year tracks that produce variously skilled graduates.

Accreditation↗
PubMed1992

Inhibition of dipteran larval neuromuscular synaptic transmission by analogues of philanthotoxin-4.3.3: a structure-activity study.

1. The blocking action of delta-philanthotoxin (PhTX-4.3.3), a wasp toxin composed of a polyamine chain, an aromatic amino acid (tyrosyl) nucleus and an aliphatic (butanoic) acid was studied, together with 33 structural analogues, at the glutamatergic neuromuscular synapse in larvae of the house fly, Musca domestica. 2. Shortening of the polyamine or the aliphatic acid chain, or removing the aromatic nucleus caused a decrease in potency. 3. An increase in potency was obtained by elongating the molecule in any of several directions: elongation of the polyamine chain with amine containing groups, by iodination of the aromatic moiety and by aliphatic or aromatic elongation of the butanoic acid.

Animals↗
PubMed1991

Certification and recertification: one approach to professional accountability.

Professional accountability requires a self-regulating profession to set and maintain credible, useful standards for its members. Voluntary certification and recertification--evaluation by peers--serves the responsibility of the profession to establish and enforce its own standards. The goal of certification by the American Board of Internal Medicine is to improve the quality of medical care by ensuring that the certified internist and subspecialist possess the knowledge, skills, and attitudes essential to the provision of excellent care. Without a true constituency and with a valid certification process, the Board provides a credential sought by nearly every graduate resident and acceptable both to the profession and patients. Recertification now presents the opportunity to foster continuing scholarship and self-improvement throughout the career of an internist.

Certification↗
PubMed1991

Changes in the medical knowledge of candidates for certification.

PURPOSE: To determine whether the medical knowledge of candidates from different types of medical schools changed between 1983 and 1988. SUBJECTS: Candidates for certification who took the 1983 to 1988 examinations in internal medicine were divided into five groups according to the type and location of the medical school they had attended and, in some instances, their citizenship: graduates of U.S. medical schools, of Canadian medical schools, and of osteopathic medical schools as well as U.S. citizens who graduated from foreign medical schools and non-U.S. citizens who graduated from foreign medical schools. DESIGN: Performance on items that were common to four pairs of the 1983 to 1988 certifying examinations (1983 and 1985, 1984 and 1986, 1985 and 1987, and 1986 and 1988) was analyzed. RESULTS: The scores of graduates of U.S. medical schools decreased, and the scores of non-U.S. citizens who graduated from foreign medical schools increased. Trends in the performance of graduates of Canadian and osteopathic medical schools and of U.S. citizens who graduated from foreign medical schools were not discernible. CONCLUSIONS: The cumulative decline in the performance of graduates from U.S. medical schools and the progressive improvement in the performance of non-U.S. citizens who graduated from foreign medical schools may ultimately manifest itself in patient care.

Canada↗