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Biomedical subjects

J A Benson

Publications and source records attributed to J A Benson.

At least 73 records · Page 4Linked to original sources
PubMed1987

Responsibilities of primary physicians in organ donation.

As transplantation success rates have improved, the demand for donor organs has steadily increased. A shortage of donor organs has led to legislation requiring hospital personnel to provide families routinely with the opportunity to authorize organ donation. Primary physicians have an important role in identifying potential donors while continuing to assure that the survivors' needs are met. The major implications of organ donation for the primary physician are reviewed. Patients who die will more frequently be eligible as cornea, skin, or bone donors, but the criteria for both tissue and internal organ donation are reviewed. Ethical issues unique to organ donation and responses of survivors to donation requests are described. If appropriately offered, the opportunity to authorize an anatomic gift can be a source of comfort to survivors while the donation provides the benefits of transplantation to persons on organ waiting lists.

Ethics, Medical↗
PubMed1986

Predictors of the performance of foreign medical graduates on the 1982 certifying examination in internal medicine.

This study describes a cohort of foreign medical school graduates (FMGs) who first sat for the American Board of Internal Medicine's (ABIM) 1982 certifying examination, compares their performance with that of US medical school graduates, describes differences between US citizen FMGs and alien FMGs, and examines which background factors predict success on the ABIM examination. Data for this study were derived by combining information retained by the Educational Commission for Foreign Medical Graduates with ABIM data. Most FMGs who took the 1982 ABIM certifying examination for the first time were educated in and citizens of Asia, but a sizable minority were US citizens educated in Europe. Scores and program directors' ratings were lower for FMGs than US medical school graduates, and they attended different types of training programs. United States citizen FMGs were very similar to alien FMGs. Foreign medical school graduates who did well on the ABIM examination had done well on the Educational Commission for Foreign Medical Graduates examination and were rated highly by their residency program director.

Achievement↗
PubMed1985

An analysis of the knowledge base of practicing internists as measured by the 1980 recertification examination.

The performance of practicing internists on the American Board of Internal Medicine's 1980 Recertification Examination was examined in two studies. In the first study, a psychometric common-item equating technique was used to compare the performance of 1980 recertification candidates with that of 1979 certification candidates. Results showed that the knowledge base of practicing internists was similar to that of residents completing training. The second study analyzed the performance of 1980 recertification candidates to determine whether being certified or having an interest in a subspecialty affects a physician's performance on items in that area. The results showed that subspecialists do significantly better than general internists on items pertaining to their area of specialization. Similar outcomes were found for internists with a special interest in a subspecialty area. These findings establish the importance of continued periodic evaluation and support the development of an evaluation tool tailored to the physician's area of concentration.

Adult↗
PubMed1984

Epidemiological study of Pasteurella multocida and Bordetella bronchiseptica in atrophic rhinitis.

An epidemiological study of atrophic rhinitis was carried out in four pig herds. Observations were made of (i) infection with Bordetella bronchiseptica and Pasteurella multocida, (ii) the presence of brachygnathia superior (BS score), (iii) the extent (grade) of turbinate atrophy and pneumonia at slaughter and (iv) growth rates from two to 16 weeks of age and average daily weight gains to slaughter. In two of the herds with no history of atrophic rhinitis, B bronchiseptica and non-toxigenic strains of P multocida were isolated; only one of 47 pigs (2 per cent) had a BS score greater than +10 mm and the most severe turbinate atrophy observed in 21 pigs at slaughter was grade 3. In contrast, from two herds with atrophic rhinitis, toxigenic strains of P multocida were isolated as well as B bronchiseptica and non-toxigenic P multocida. BS scores of greater than +10 mm were present in six of 47 pigs (13 per cent) of which five were infected with toxigenic P multocida and had severe turbinate atrophy of grade 4 or 5. There was no significant reduction in growth rates in the affected compared with the unaffected herds nor in the affected compared with the unaffected pigs in the same herd. Neither was there a correlation between progressive disease and the extent of pneumonia found at slaughter. It was concluded that in field cases of the disease, high BS scores plus severe turbinate atrophy were associated with infection by toxigenic type-D strains of P multocida.

Animals↗
PubMed1984

Octopamine alters rhythmic activity in the isolated cardiac ganglion of the crab, Portunus sanguinolentus.

When applied to the isolated cardiac ganglion of Portunus, octopamine decreases the ganglionic burst frequency and increases the burst duration in a dose-dependent manner over the concentration range 10(-8) M to 10(-6) M. These effects are accompanied by a hyperpolarization (maximum 5 mV) of the cardiac ganglion motor neurones and a decrease in the magnitude of the interburst pacemaker potential in these neurones. The evidence that octopamine plays a cardiomodulatory role in vivo is discussed.

Action Potentials↗
PubMed1984

A survey of clinical skills evaluation practices in internal medicine residency programs.

For the past 12 years, directors of residency training programs in internal medicine have had the responsibility for evaluating and reporting on the clinical competence of their residents who pursue certification by the American Board of Internal Medicine ( ABIM ). The board requires that residents demonstrate satisfactory clinical skills to take its certifying examination. In this article, the authors review the evaluation processes of 75 internal medicine residencies visited by the board in 1978-1982. The methods of evaluation used by the residencies are described and compared with the findings from an earlier cycle of visits in 1972-1975. In addition, information is presented on residents persuaded to leave the field of internal medicine. The results are encouraging, since they signify increased attention to the clinical method by graduate medical educators. This has been demonstrated by an improved, continuing commitment to the assessment of residents' clinical skills by program directors since the inception of the ABIM 's Hospital Visit Program.

Certification↗
PubMed1984

The influence of daylength, body weight, and age on the reproductive ability of broiler breeder cockerels.

June-hatched broiler breeder cockerels of two strains were evaluated for reproductive performance in mating pens from 22 to 48 weeks of age. Two light programs with maximum daily daylengths of 15.5 or 16.5 hr were studied. An increase in the light day to 16.5 hr did not significantly affect the male reproductive traits except in number of completed matings and percent packed sperm volume (PSV). The males on 16.5 hr of light had significantly fewer completed matings than did the males on 15.5 hr. Strain 1 males on 16.5 hr produced significantly more spermatozoa at 35 and 40 weeks of age than males on 15.5 hr of light. Male body weights of both strains were significantly lower at 30 weeks of age on the longer daylength. Body weights of cockerels in all treatment groups increased with aging. The range in male body weight markedly influenced the percentage of producing cockerels with aging. During the late egg cycle, the number of producing males increased as body weight increased. The overall mean age of peak in the percentage of males in semen production was 44 weeks of age, which was 7 weeks later than peak egg production. Hatchability was significantly lower for male Strain 2, which had a higher percent PSV and a higher number of attempted matings than did Strain 1. Body weight was significantly correlated with male vent feather-wear at all ages and with the percentage of producing males at 48 weeks of age. The percentage of producing males was correlated with vent feather-wear, evert score, semen volume, and PSV. These results emphasize the importance of body weight selection for optimum breeding flock performance.

Aging↗
PubMed1983

Serotonin increases an anomalously rectifying K+ current in the Aplysia neuron R15.

Previous work has shown that serotonin causes an increase in K+ conductance in the identified Aplysia neuron R15. This response is mediated by cAMP-dependent protein phosphorylation. The results presented here show that the K+ channel modulated by serotonin is an anomalous or inward rectifier (designated IR) that is present in R15 together with the three other distinct K+ channels previously described for this cell. Several lines of evidence indicate that this inward rectifier is partially activated in the resting cell and is further activated by serotonin. Voltage clamp analysis of resting and serotonin-evoked membrane currents at various external K+ concentrations shows that both currents have reversal potentials close to the potassium equilibrium potential, exhibit similar dependences in magnitude on external K+ concentration, and display marked anomalous rectification. The effects of particular monovalent and divalent cations are also similar on the resting and serotonin-evoked currents. Rb+, Cs+, and Ba2+ block both currents while Tl+ can substitute for K+ as a charge carrier and channel activator in both. These properties are characteristics of anomalous rectifiers in other systems. Furthermore, measurement of the voltage dependence of inactivation for the fast transient K+ current shows that this current cannot account for the anomalously rectifying K+ conductance in R15. The inward rectifier is therefore a separate current mediated by its own channels, the activity of which can be modulated by serotonin.

Animals↗
PubMed1981

The neuropeptide proctolin acts directly on Limulus cardiac muscle to increase the amplitude of contraction.

The pentapeptide proctolin increases the amplitude of contraction but not heart beat frequency of the isolated heart of Limulus polyphemus. It acts directly on the heart muscle and has no effects on the neurones of the cardiac ganglion or on the cardiac neuromuscular EJPs. A peptide with molecular weight, enzymatic susceptibilities and physiological effects similar to those of proctolin occurs in the Limulus cardiac ganglion. It is suggested that proctolin, or a family of proctolin-like peptides, may modulate muscle contraction in more than one subphylum of the Arthropoda.

Animals↗
PubMed1981

Performance of U.S. citizen-foreign medical graduates on certifying examinations in internal medicine.

Increasing numbers of U.S. citizens are studying medicine abroad and returning for graduate medical education and practice. The numbers and performance of U.S. citizen and all other graduates of foreign medical schools on the certifying examination of the American Board of Internal Medicine were compared with those of graduates of U.S. medical schools for 1975-1980. Numbers of first-taker U.S. citizen foreign medical school graduates increased whereas numbers of all other foreign medical school graduates decreased during this period. In 1980, U.S. citizens represented 19 percent of all first-taker foreign medical school graduates. During the study period, annual examinations were passed by 79 to 82 percent of U.S. medical school graduates, 15 to 38 percent of U.S. citizen foreign medical school graduates, and 27 to 45 percent of all other foreign medical school graduates taking an examination for the first time. On each examination, U.S. citizen foreign medical school graduates did not do as well as all other foreign medical school graduates. Members of all groups met the same postdoctoral training requirements.

Certification↗
PubMed1980

Serotonin-induced hyperpolarization of an indentified Aplysia neuron is mediated by cyclic AMP.

Addition of serotonin to the medium bathing an Aplysia abdominal ganglion causes a change in the endogenous bursting activity of the identified neuron R15. At serotonin concentrations in the micromolar range, the predominant effect is an increase in depth and duration of the interburst hyperpolarization and consequent decrease in burst rate. At higher concentrations (10 microM) serototin can inhibit bursting completely. We have shown previously that these changes can be mimicked by bath application or intracellular injection of several cyclic AMP analogs substituted at the 8 position. Voltage clamp analysis indicates that serotonin and cyclic AMP analogs both cause an increase in membrane slope conductance in R15, with reversal potentials for the responses between -75 and -80 mV, close to the K+ equilibrium potential. When the K+ concentration in the bathing medium is changed, the reversal potentials change in a manner suggesting that serotonin and cyclic AMP analogs on K+ conductance are not additive. Furthermore, the effects of low concentrations of serotonin can be potentiated by the phosphodiesterase inhibitor Ro 20-1724. A pharmacological analysis indicates that the serotonin receptor that mediates hyperpolarization in R15 is similar to the serotonin receptor that we have shown to be coupled to adenylate cyclase. The present electrophysiological and pharmacological observations, together with our previous biochemical and pharmacological results, demonstrate that the serotonin-induced hyperpolarization of neuron R15 is mediated by cyclic AMP.

Animals↗
PubMed1980

Burst reset and frequency control of the neuronal oscillators in the cardiac ganglion of the crab, Portunus sanguinolentus.

1. The five large and four small neurones in the cardiac ganglion of the crab, Portunus, are electrotonically coupled and behave as a single relaxation oscillator, exhibiting periodic bursting activity in vitro. Recorded from the large neurone somata, this activity consists of 200-400 ms slow depolarizations called 'driver potentials' (Tazaki & Cooke, 1979a), accompanied by attenuated action potentials and EPSP's from small neurone input. 2. There is a strong positive correlation between the duration of the driver potential and the duration of the following interburst interval in the spontaneously active ganglion. This correlation is preserved during prolonged depolarization and hyperpolarization. 3. When a driver potential is prematurely terminated by an injected current pulse, the following interburst interval is shortened in direct proportion to the decrease in driver potential duration. 4. When a driver potential or a burst of high-frequency action potential activity is evoked by a depolarizing current pulse, the cardiac oscillator resets to the point of maximum hyperpolarization of the burst cycle, and the following interburst interval is of normal duration. Resetting following an evoked driver potential is complete. Partial resetting occurs only after short, evoked action potential bursts in the absence of a driver potential. 5. Reset of the oscillator causes phase shifts in the subsequent cycles of activity, which vary with the phase of application and duration of the injected current pulse. Response curves have been constructed for a comprehensive range of durations and intensities of hyperpolarizing and depolarizing current pulses applied at all phases of the oscillator cycle. 6. The phase shifts are composed of contributions from the duration of the current pulse, from the premature initiation of the slow depolarizing pacemaker potential due to early termination of the burst, and from the change in interburst interval correlated with truncation of the driver potential. 7. Considering the cardiac ganglion as a relaxation oscillator, frequencey control by entrainment to periodically applied current pulses was quantitatively predicted from the phase-response curves and experimentally confirmed. 8. A high concentration (10(-5) M) of octopamine can inhibit driver potential activity in the large neurones. This was used to examine possible frequency modulating effects of electrotonic feedback from the large neurone driver potentials onto the small neurone pacemaker activity. 9. The observations are discussed in relation to the ionic model for driver potentials and slow pacemaker potential activity in the cardiac ganglion, as proposed by Tazaki & Cooke (1979a, b).

Action Potentials↗