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Biomedical subjects

J A Hall

Publications and source records attributed to J A Hall.

At least 145 records · Page 8Linked to original sources
PubMed1989

Intracoronary injections of salbutamol demonstrate the presence of functional beta 2-adrenoceptors in the human heart.

To demonstrate the presence of functional cardiac beta 2-adrenoceptors in man, we studied the responses to intracoronary injections of salbutamol in three groups of six patients. We injected salbutamol, a selective beta 2-adrenoceptor agonist, into the right coronary artery to avoid peripheral vasodilator action and to stimulate the sinoatrial node directly. Salbutamol injections caused a sinus tachycardia. The same doses of salbutamol injected into the aortic root caused no change in heart rate, ruling out a systemic effect. The mean dose required to cause an increase in heart rate of 30 beats/min (IHR30) was 2.6 micrograms in the first group of six patients. In 12 other patients salbutamol was given after beta-blockade to confirm the beta 2-selectivity of the responses. Doses of practolol (beta 1-selective blockade) and of propranolol (beta 1- and beta 2-blockade) that had equal beta 1-blocking activity were used. In six patients who were given practolol, the mean IHR30 dose was 2.1 micrograms. In six patients who were given propranolol, the mean IHR30 dose was significantly greater at 64 micrograms (p less than 0.001, practolol vs. propranolol). This study demonstrates that direct cardiac beta 2-adrenoceptor stimulation in man has a positive chronotropic effect.

Albuterol↗
PubMed1989

Stable xenon versus radiolabeled microsphere cerebral blood flow measurements in baboons.

Regional cerebral blood flow was simultaneously determined using the stable xenon computed tomographic and the radioactive microsphere techniques over a wide range of blood flow rates (less than 10-greater than 300 ml/100 g/min) in 12 baboons under conditions of normocapnia, hypocapnia, and hypercapnia. A total of 31 pairs of determinations were made. After anesthetic and surgical preparation of the baboons, cerebral blood flow was repeatedly determined using the stable xenon technique during saturation with 50% xenon in oxygen. Concurrently, cerebral blood flow was determined before and during xenon administration using 15-microns microspheres. In Group 1 (n = 7), xenon and microsphere determinations were made repeatedly during normocapnia. In Group 2 (n = 5), cerebral blood flow was determined using both techniques in each baboon during hypocapnia (PaCO2 = 20 mm Hg), normocapnia (PaCO2 = 40 mm Hg), and hypercapnia (PaCO2 = 60 mm Hg). Xenon and microsphere values in Group 1 were significantly correlated (r = 0.69, p less than 0.01). In Group 2, values from both techniques also correlated closely across all levels of PaCO2 (r = 0.92, p less than 0.001). No significant differences existed between the slopes or y intercepts of the regression lines for either group and the line of identity. Our data indicate that the stable xenon technique yields cerebral blood flow values that correlate well with values determined using radioactive microspheres across a wide range of cerebral blood flow rates.

Animals↗
PubMed1989

Relationship of plasma gastrin immunoreactivity and gastroesophageal sphincter pressure in clinically normal dogs and in dogs with previous gastric dilatation-volvulus.

Fasting and postprandial gastroesophageal sphincter pressure (GESP) and plasma gastrin immunoreactivity were measured in 6 dogs from 9 through 60 months after treatment for and recovery from gastric dilatation-volvulus (GDV). The GESP was not significantly increased in these dogs, compared with that in clinically normal dogs in either the fasting or postprandial state. Corresponding plasma gastrin immunoreactivity was not significantly increased in dogs of the GDV-recovered group, compared with that in clinically normal dogs (fasting or postprandial). An exaggerated increase in GESP in response to food-induced gastrin release was not observed in dogs of the GDV-recovered group. Exogenously administered pentagastrin (3-micrograms/kg bolus, IV) increased fasting GESP in clinically normal dogs over a 4-minute test period (P = 0.01). Gastric distention in response to oral administration of isosmolar saline solution (500 ml) did not significantly increase GESP or plasma gastrin immunoreactivity in clinically normal dogs. In anesthetized clinically normal dogs, gastric distention in response to use of balloons filled to exert intragastric pressure of 30 mm of Hg also did not cause significant increase in plasma gastrin immunoreactivity. Increased GESP, secondary to hypergastrinemia or gastric distention, is an unlikely cause of eructation failure in dogs with GDV.

Animals↗
PubMed1989

Using proxies to evaluate quality of life. Can they provide valid information about patients' health status and satisfaction with medical care?

Instruments using interview data to measure health status have been increasingly used to measure patient outcomes. To assess the potential utility of proxy responses about health status when subjects are unable to respond, the authors compared the responses of 60 subject and proxy pairs on instruments measuring overall current health, functional status, social activity, emotional health, and satisfaction with medical care. Proxies were asked to respond as they thought the subject would. Subject and proxy responses were strongly correlated with each other for overall health, functional status, social activity, and emotional health (P less than .001), and moderately correlated for satisfaction (P less than .005). Proxies reported lower emotional health and satisfaction than did subjects (P less than .005). Proxy and subject mean responses were generally similar for overall health, functional status, and social activity. However, those proxies who spent more time per week helping the subject rated the subject's functional status and social activity as more impaired than did the subject (P less than .05). Subjects who had poorer overall health tended to rate their health relatively lower than did the proxies (P less than .05). These results suggest that use of proxies intermingled with subjects to measure health status through interview may lead to biased results.

Activities of Daily Living↗
PubMed1988

Sodium chloride depletion in a cat with fistulated meningomyelocele.

Decreased serum and CSF chloride concentrations were documented in a 5-year-old Manx cat referred for evaluation of anorexia. Inadequate chloride intake coupled with chloride loss through a fistulated meningomyelocele probably caused chloride deficiency. The inciting cause of anorexia was not determined. The cat was treated with 0.9% NaCl solution. Normal serum and CSF chloride concentrations were restored. Lumbar myelography was performed to delineate the meningocutaneous tract, which then was dissected surgically and was ligated. The cat's body attempted to maintain normal CSF chloride concentration even though the serum chloride concentration was decreased markedly. Calculations made on the basis of rate of CSF production, CSF chloride concentration, and duration of anorexia provided supportive evidence for an active transport system for chloride from plasma to CSF.

Animals↗
PubMed1988

Changes in myosin and C-protein isoforms proceed independently of the conversion to singly innervated neuromuscular junctions in developing pectoral muscle.

Changes in contractile protein expression during myogenesis are usually categorized as developmentally programmed or neuronally dependent. Studies on aneurogenic chick embryos indicated that the neuronally dependent phase begins at about Embryonic Day 15, immediately prior to the fetal transition in myosin and C-protein expression. The prime candidate for the neuronal event that induces the fetal transition is the conversion to the adult form of singly innervated neuromuscular junctions (NMJs), which occurs contemporaneously with the fetal transition. Using curare to inhibit the conversion to focal innervation, we find that the fetal transition proceeds unimpaired, demonstrating that there is no causal link between the fetal transition and the conversion to focal innervation. Furthermore, because the doses of curare used inhibit motor activity by more than 80%, the fetal transition can occur in the absence of normal levels of motor activity. These observations show that the fetal transition in ovo is not induced by either a specific change in innervation or use. Rather, the dependence on innervation seems to be a consequence of the need for muscle activity to prevent atrophy, and the fetal transition appears to have characteristics more like the preprogrammed contractile protein transitions that precede it.

Acetylcholinesterase↗
PubMed1988

DSP-4 treatment produces abnormal tyrosine hydroxylase immunoreactive fibers in rat hippocampus.

DSP-4 has been used as selective toxin for central norepinephrine (NE) systems. The depletion of NE by DSP-4 is though to result from neurotoxic destruction of locus coeruleus terminals and axons. We have used tyrosine hydroxylase immunocytochemistry (TH-IR), silver stains for neural degeneration, and electron microscopy to examine the morphological effects of DSP-4 treatment on the rat hippocampus. Animals survived for either 2 or 5 weeks after DSP-4 treatment. DSP-4 depleted hippocampal norepinephrine levels to 15% of control values. Abnormally enlarged TH-IR fibers were found in the hippocampus of DSP-4-treated animals. No evidence of fiber degeneration was found following light or electron microscopic examination of the dentate hilus in DSP-4-treated animals. These data suggest that DSP-4 treatment does not destroy NE terminals, but may produce an intraneuronal lesion leading to an accumulation of TH and a depletion of norepinephrine within the terminal fields.

Animals↗
PubMed1988

Meta-analysis of satisfaction with medical care: description of research domain and analysis of overall satisfaction levels.

Consumer satisfaction with medical care was examined in a meta-analysis of 221 studies. For each study, (1) a coding form was filled out that described sample characteristics, design, and instrument methodology, and (2) the study sample's overall satisfaction level was transformed to a 0.00-1.00 scale. This article summarizes the study attributes as compiled from the coding form, presents grand satisfaction means over all studies, and tests for differences in satisfaction between studies that employed different methods of research.

Community Health Services↗
PubMed1988

What patients like about their medical care and how often they are asked: a meta-analysis of the satisfaction literature.

A meta-analysis of studies on consumer satisfaction with medical care yielded 221 studies that reported relations between satisfaction and other variables, of which 107 reported satisfaction levels for two or more aspects of medical care. A method was developed to derive the relative levels of patient satisfaction with 11 aspects of care across these 107 studies. Humaneness and technical quality of medical care were ranked near the top, while the bottom five ranks were occupied by aspects of care that reflected the provider's attention to other patient needs and the patient's relation to the system as a whole. In addition, it was demonstrated that different aspects of medical care are measured with extremely uneven frequencies in satisfaction instruments.

Consumer Behavior↗
PubMed1988

Meta-analysis of correlates of provider behavior in medical encounters.

This article summarizes the results of 41 independent studies containing correlates of objectively measured provider behaviors in medical encounters. Provider behaviors were grouped a priori into the process categories of information giving, questions, competence, partnership building, and socioemotional behavior. Total amount of communication was also included. All correlations between variables within these categories and external variables (patient outcome variables or patient and provider background variables) were extracted. The most frequently occurring outcome variables were satisfaction, recall, and compliance, and the most frequently occurring background variables were the patient's gender, age, and social class. Average correlations and combined significance levels were calculated for each combination of process category and external variable. Results showed significant relations of small to moderate average magnitude between these external variables and almost all of the provider behavior categories. A theory of provider-patient reciprocation is proposed to account for the pattern of results.

Adult↗
PubMed1987

Hyperammonemia associated with urethral obstruction in a dog.

Hyperammonemia was documented in a 10-week-old male Lhasa Apso referred for urethral obstruction and rupture. Results of liver function tests were normal. Staphylococcus sp was isolated from urine. Anomalies of the portal vascular system and hepatic insufficiency are the most common causes of hyperammonemia in the dog. Hyperammonemia, however, in the absence of recognizable concurrent hepatic disease, also may result from urinary stasis and infection with urea-splitting organisms.

Ammonia↗
PubMed1987

Effects of a low-fat, low-cholesterol diet on serum lipids, platelet aggregation and thromboxane formation.

The purpose of this study was to test the effects of a low-fat, low-cholesterol diet on serum lipids, platelet aggregation, thromboxane formation and blood pressure. Fifteen hyperlipidemic males with normal blood pressure were treated for 2 weeks. Resting supine blood pressure, total serum cholesterol, HDL-cholesterol, the ratio of total cholesterol/HDL-cholesterol and triglycerides all were significantly reduced. The maximum aggregation and velocity of aggregation for isolated platelets stimulated with either ADP or collagen was significantly reduced. Thromboxane formation during 5 min of platelet aggregation with collagen or ADP was also significantly reduced. These results have important implications for hypertension and atherosclerotic cardiovascular disease.

Blood Pressure↗
PubMed1987

Xenon/computed tomography cerebral blood flow measurements. Methods and accuracy.

We performed a series of five baboon experiments to compare cerebral blood flow measured with an improved stable xenon/CT method and the radiolabelled microsphere technique at a PaCO2 of 40 mm Hg. The xenon/CT method was implemented by fitting the arterial xenon uptake with a double exponential function, by measuring the oxygen and carbon dioxide concentrations continuously during each breath and by taking into account the lung-to-brain transit time of xenon. The time of xenon inhalation was extended to 30 minutes to obtain more reliable estimates of CBF in white matter regions. The results indicate an overall correlation coefficient of 0.92 between the two methods and good numeric agreement.

Animals↗
PubMed1987

Task versus socioemotional behaviors in physicians.

This paper investigates associations among physicians' task-oriented and socioemotional behaviors during the medical encounter. The study is an analogue, using as source data the audiotapes and transcripts of two standardized patient cases presented by trained patient simulators to 43 primary care practitioners. Transcripts were scored for physician proficiency and were content-analyzed to assess the process of communication and information content. Physicians' speech errors were counted, and vocal affect ratings were made of filtered audiotape excerpts. Physician communications reflected by these measures were classified as task-oriented or socioemotional. Findings indicated: 1) Most aspects of physician style were reliable across visits. 2) Physicians adopted either a patient-oriented or a physician-oriented approach to task performance, as characterized by giving information and counseling versus giving directions and asking questions, respectively. 3) Verbal and nonverbal socioemotional measures were not related. 4) Physicians tended to adopt either a style characterized by information-giving and proficiency or a social orientation with patients. 5) Physicians who were more medically informative had more interested and anxious voices compared with the less informative physicians. Thus, although the more medically informative physicians spent less time making socioemotional utterances, they had a voice quality that may compensate for that neglect.

Affect↗
PubMed1987

Relations between physicians' behaviors and analogue patients' satisfaction, recall, and impressions.

This paper investigates associations between physicians' task-oriented and socioemotional behaviors, on the one hand, and analogue patients' satisfaction, recall of information, and global impressions. The study is based on role-playing subjects' responses to interactions between physicians and simulated patients. Audiotapes of two standardized patient cases presented by trained patient simulators to 43 primary care physicians were rated by role-playing patients (N = 258), and electronically filtered excerpts from the encounters were rated for vocal affect by 37 independent judges. Content analysis was made of the visits' transcripts to assess interaction process and to identify all medical information communicated. Finally, speech error rate was calculated from a combination of audiotape and transcript. Findings revealed that role-playing patients clearly distinguished task from socioemotional behaviors of the physicians, and a consistent pattern of association emerged between physicians' task behaviors and role-playing patients' satisfaction, recall, and impressions. Within the task domain, patient-centered skills (i.e., giving information and counseling) were consistently related to patient effects in a positive direction, but physician-centered behaviors (i.e., giving directions and asking questions) demonstrated the opposite relationship. A negative pattern of association was also evident between physicians' socioemotional behaviors and patient effects.

Affect↗
PubMed1987

The emergence of geriatric assessment units. The "new technology of geriatrics".

Previous studies have suggested that geriatric assessment units may provide important benefits to the care of elderly persons. In early 1985 we surveyed personnel at 104 (91%) of the existing 114 geriatric assessment units associated with medical schools and Veterans Administration medical centers for information on the units' development and operation. Although almost 80% of the units were hospital based, most (61%) provided care for outpatients. Nearly half (47%) began operation in 1983 or later; of those in existence before 1983, two thirds have increased their capacity since then. The types of personnel and their training differed substantially among units. Fifty percent of the physicians had had no formal training in geriatrics. Of the 104 units, 99 (95%) did routine assessment. The estimated time spent per new patient in outpatient units was 2.7 +/- 2.1 (SD) hours. These data suggest that geriatric assessment units are proliferating rapidly, have differing structures, and consume substantial resources. Further efforts are needed to define their optimal structure, targets, and function.

Geriatrics↗