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Biomedical subjects

J M Hinson

Publications and source records attributed to J M Hinson.

At least 19 recordsLinked to original sources
PubMed1999

Zanamivir in the prevention of influenza among healthy adults: a randomized controlled trial.

CONTEXT: The neuraminidase inhibitor zanamivir, a sialic acid analog administered directly to the respiratory tract, has been demonstrated in clinical studies to be effective in treatment of type A and B influenza. It has also been shown to prevent influenza infection and disease in an experimental model. OBJECTIVE: To examine the efficacy of zanamivir, administered once daily, in the prevention of influenza infection and disease. DESIGN: Double-blind, randomized, placebo-controlled trial. SETTING: Two midwestern university communities. PARTICIPANTS: A total of 1107 healthy adults (mean age [range], 29 [18-69] years) were recruited in November 1997, before the influenza season. INTERVENTION: At the start of the influenza outbreak, 554 subjects were randomized to receive placebo and 553 to receive zanamivir. The drug, 10 mg once per day, or identical placebo was administered by oral inhalation for a 4-week period. MAIN OUTCOME MEASURES: Illness occurrence was recorded by participants daily and records were evaluated weekly. Specimens were collected for viral isolation when symptoms were reported within 3 days of illness onset. Infection was also identified by testing paired serum samples for rise in antibody titer against the circulating influenza viruses. RESULTS: Zanamivir was 67% efficacious (95% confidence interval [CI], 39%-83%; P<.001) in preventing laboratory-confirmed clinical influenza meeting the case definition and 84% efficacious (95% CI, 55%-94%; P=.001) in preventing laboratory-confirmed illnesses with fever. All influenza infections occurring during the season, with or without symptoms, were prevented with an efficacy of 31% (95% CI, 4%-50%; P=.03). The nature and incidence of adverse events in the zanamivir group did not differ from placebo. Compliance with the once-daily dosage was high. CONCLUSIONS: Zanamivir administered once daily is efficacious and well tolerated in the prevention of influenza for a 4-week period in healthy adults.

Adult↗
PubMed1993

Dobutamine, but not dopamine, augments the normal chronotropic response to acute hypoxemia.

Infusion of exogenous dopamine has been shown to alter both the hypoxic and the hypercapnic ventilatory response, but its effects on the hypoxic and the hypercapnic cardiac response have not been reported. The purpose of this study was to determine if cardiac responses to hypoxemia and hypercapnia are altered by infusion of either dopamine (DOP) or its analog dobutamine (DBT). Baseline mean arterial blood pressure (MAP) and heart rate (HR) were measured in 7 normal male subjects while normal saline was infused intravenously (NS1) for 30 min. Each subject then underwent both a eucapnic hypoxemic challenge (EHC), and a hyperoxic hypercapnic challenge (HHC). In a double-blinded randomized fashion either DOP1 or DBT1 was selected and infused at 5 micrograms/kg/min for 30 min. EHC and HHC were again performed. This sequence was then repeated following a second NS infusion (NS2) and the alternate vasopressor. On a second study day, the dose of dopamine (DOP2) selected was that sufficient to induce a similar rise in MAP as seen with DBT1. Following NS and DOP1 there was a reproducible significant linear increase in HR with progressive hypoxemia seen in all subjects. This response was significantly augmented following infusion of DBT1 (p < 0.03), but no such augmentation was noted with DOP2. No significant change in HR was noted during HHC. The mechanisms responsible for this augmentation of hypoxemic response during dobutamine infusion are unclear, and do not appear to be related to a rise in MAP. We speculate that it is due to an effect of dobutamine on beta 1-receptor activity.

Adult↗
PubMed1993

The effects of transtracheal gas delivery on central inspiratory neuromuscular drive.

Previous studies have shown transtracheal delivery of low-flow oxygen (TTO) decreases inspired minute ventilation (Veinsp) and have postulated that this would result in a decrease in the work of breathing (WOB). We hypothesized that a fall in central inspiratory neuromuscular drive (CIND) with TTO would reflect a fall in WOB. We measured resting ventilatory parameters (RVP) and CIND by the mouth occlusion pressure technique (MOP) at different gas flow rates through the catheter in 21 subjects (13 men, 8 women; mean age, 60 +/- 10.6 years) with severe COPD with a mature intratracheal oxygen catheter (ITOC). We also constructed a lung/chest wall analog (LCA) to determine if flow through the catheter would alter pressure changes during inspiration. Inspiratory tidal volume (Vtinsp) and minute ventilation (Veinsp) decreased proportionally to the gas flow rate through the catheter. However, with increasing flow through the catheter, P0.1 increased in the LCA, presumably due to the Bernoulli effect. The lack of a similar change in the subject group suggests that CIND does, in fact, fall, and that possibly there is a decrease in WOB. This effect may be of benefit to patients with severe COPD.

Catheters, Indwelling↗
PubMed1992

Patterns of responding within sessions.

Rates of responding changed systematically across sessions for rats pressing levers and keys and for pigeons pressing treadles and pecking keys. A bitonic function in which response rates increased and then decreased across sessions was the most common finding, although an increase in responding also occurred alone. The change in response rate was usually large. The function relating responding to time in session had the following general characteristics: It appeared early in training, and further experience moved and reduced its peak; it was flatter for longer sessions; and it was flatter, more symmetrical, and peaked later for lower than for higher rates of reinforcement. Factors related to reinforcement exerted more control over the location of the peak rate of responding and the steepness of the decline in response rates than did factors related to responding. These within-session changes in response rates have fundamental theoretical and methodological implications.

Animals↗
PubMed1991

Strut fixation of an extensive flail chest.

The indications for and preferred approaches to operative stabilization of posttraumatic chest wall instability are uncertain. We suggest this simple, rapid, and effective approach to surgical stabilization by Luque rod strutting of the flail segment when operation is required.

Aged↗
PubMed1989

Discrete and continuous measures of dimensional stimulus control.

In two sets of experiments, we examined dimensional stimulus control of pigeons' responses to a visual flicker-rate continuum. In the first experiment, responses to a single key were reinforced periodically during stimuli from one half of the stimulus continuum, and responses during other stimuli were extinguished. In the second experiment, two response keys were simultaneously available, with reinforcement for each response alternative associated with different halves of the stimulus continuum. Conditions of the second experiment involved either free-operant or discrete-trial stimulus presentations. Results from these experiments show that positive dimensional contrast appeared in discrimination tasks with one or two response alternatives, but only with free-operant procedures. In addition, discrimination between stimulus classes established by differential reinforcement was assessed as accurately by continuous rate measures as by discrete response choice in the two-alternative situation. The general implication of these experiments is that response rate measures, when properly applied, may reveal sources of variation within stimulus classes, such as dimensional contrast, that are not evident with discrete measures.

Animals↗
PubMed1988

Absolute and relative measures of dimensional contrast.

Two sets of experiments examined the discriminative performance of pigeons on a visual flicker-rate continuum using a maintained generalization procedure. In the first experiment, responses during the intermediate stimulus value were not reinforced, whereas responses during all other stimuli were reinforced periodically. In the second experiment, training was similar to the first, with the exception of one condition in which stimuli adjacent to the negative stimulus border were eliminated from the discrimination set. Results from both experiments show that positive dimensional contrast seems to represent a relative enhancement of discrimination gradient form, rather than an absolute increase in responding with respect to prior baseline. Further, the form and magnitude of positive dimensional contrast are not predictable from the form and magnitude of baseline response rates. Results from the second experiment indicate that eliminating border stimuli increased response-rate differences between positive and negative stimuli, but did not necessarily diminish the magnitude of positive dimensional contrast.

Animals↗
PubMed1986

Nonexertional heatstroke. Physiologic management and cooling in 14 patients.

Fourteen patients with nonexertional heatstroke were evaluated in a general hospital during the summer of 1980. They were managed according to a prospectively devised protocol designed to effect heat dissipation primarily via convection and evaporation rather than by conduction. The time from entry into the emergency room to the first recorded rectal temperature of less than 103 degrees F (39.4 degrees C) ranged from 34 to 89 minutes (median, 60 minutes). Only one patient died; none had residual neurologic deficits. The use of these methods can result in a low incidence of permanent neurologic impairment and a low fatality rate.

Adult↗
PubMed1986

Bronchial responsiveness to nonantigenic bronchoconstrictors in awake sheep.

The experiments were designed to further characterize pulmonary responsiveness to nonantigenic aerosol bronchoconstrictors in unanesthetized sheep. The distribution of aerosol histamine responsiveness was described among 55 sheep. Within day reproducibility of aerosol histamine (n = 18) and carbachol (n = 8) responsiveness was studied and aerosol histamine and carbachol responsiveness were compared (n = 9). The effects of cyclooxygenase inhibition with meclofenamate (n = 7) and ibuprofen (n = 8) on pulmonary responsiveness to aerosol histamine was studied as was the effect of ibuprofen (n = 6) on pulmonary responsiveness to aerosol carbachol. A log normal unimodal distribution of pulmonary responsiveness to aerosol histamine was described. Within day pulmonary responsiveness to aerosol histamine was highly reproducible while pulmonary responsiveness to aerosol carbachol decreased slightly, but not significantly, on the second challenge. Pulmonary responsiveness to aerosol histamine correlated with pulmonary responsiveness to aerosol carbachol (r = 0.85, P less than 0.05). Meclofenamate did not significantly attenuate pulmonary responsiveness to aerosol histamine. Ibuprofen attenuated pulmonary responsiveness to aerosol histamine (P less than 0.05) but not to aerosol carbachol. These experiments supply basic information related to pulmonary responsiveness to nonantigenic bronchoconstrictors in awake sheep.

Aerosols↗
PubMed1986

Range effects in successive discrimination.

In two sets of experiments we examined pigeons' discrimination performance with a visual flicker-rate continuum, using a conventional successive discrimination procedure. In the first experiment, responses during the intermediate stimulus value were never reinforced, while responses during stimuli on either end of the continuum were reinforced periodically. In the second experiment, responses during stimuli from one end of the continuum were never reinforced, while responses during stimuli from the other end of the continuum were reinforced periodically. Results from both experiments show that discrimination between unchanged positive and negative stimulus values is a function of the range over which the total stimulus set varies. These range effects are comparable to effects found in absolute judgment tasks in human and animal psychophysics. In addition, the range effects reported here are not due to channel capacity, but may depend instead on variability in judgment criteria.

Animals↗
PubMed1984

Effects of granulocyte depletion on pulmonary responsiveness to aerosol histamine.

The effects of granulocyte depletion with hydroxyurea on pulmonary responsiveness to aerosol histamine were studied in 10 chronically instrumented unanesthetized sheep. Sheep were studied when granulocyte counts were normal (B), after 3 days of hydroxyurea but before granulocyte counts had dropped below 700 cells/mm3 (H), and after granulocyte counts had fallen below 200 cells/mm3 (D). Hydroxyurea itself had no effect on aerosol histamine responsiveness and the results were unaffected by the order of experimentation. All 10 sheep were less responsive (P less than 0.05) to aerosol histamine when granulocyte depleted effective dose of histamine that caused a reduction to 65% of control dynamic compliance (ED65Cdyn = 23.98 +/- 4.70 mg/ml) compared with base line (ED65Cdyn = 7.06 +/- 1.86 mg/ml). Those sheep initially most responsive to aerosol histamine had the greatest attenuation in their airway responsiveness to aerosol histamine (P less than 0.05). There was a significant negative correlation between absolute granulocyte counts in peripheral blood and pulmonary responsiveness to aerosol histamine during base-line (B) condition (r = -0.74, P less than 0.05) and for the data as a whole [r = -0.69, P less than 0.05 (B + H + D)]. Circulating granulocytes and/or pulmonary inflammation may contribute to pulmonary responsiveness to bronchial challenge.

Aerosols↗
PubMed1984

Effects of platelet depletion on the unanesthetized sheep's pulmonary response to endotoxemia.

The effect of platelet depletion on the unanesthetized sheep's pulmonary response to endotoxemia was studied in eight unanesthetized sheep. Platelets were depleted with rabbit anti-sheep platelet antibodies (APA). Bolus injections of APA alone caused marked pulmonary hypertension (PPA increased from 21 +/- 2 to 62 +/- 5 cm H2O +/- SE) and alterations in lung mechanics (dynamic compliance of the lung [Cdyn] decreased to 38.5 +/- 4.6% and resistance to air flow across the lung [RL] increased to 705 +/- 162% +/- SE of control), which were attenuated by pretreatment with meclofenamate. It was possible to deplete platelets before endotoxemia through a slow continuous infusion of APA without altering base-line values of the measured variables. Platelet depletion did not significantly attenuate the alterations in pulmonary hemodynamics, lung mechanics, lung fluid and solute exchange, or the normal increase in lung lymph concentrations of thromboxane B2 or 6-keto-PGF1 alpha observed following endotoxemia in the sheep. We conclude that normal circulating platelet counts are not required for the full expression of the sheep's response to endotoxemia.

Animals↗
PubMed1983

Effect of endotoxin on airway responsiveness to aerosol histamine in sheep.

This study tested the hypothesis that in the awake sheep, airway responsiveness to aerosol histamine would be increased acutely by endotoxemia. Eleven sheep were chronically instrumented to allow for measurements of lung lymph flow, vascular pressures, and lung mechanics. Awake sheep were studied in a whole-body plethysmograph designed to measure dynamic compliance (Cdyn), resistance of the lung (RL), and functional residual capacity (FRC). Pulmonary responsiveness to aerosol histamine was assessed by giving five breaths of increasing concentrations of histamine (0.1-50 mg/ml) until Cdyn decreased to 65% (of control) or until 50 mg/ml of histamine had been given. Escherichia coli endotoxin (0.2-0.5 microgram/kg) was then infused, and at 5 h after endotoxemia pulmonary responsiveness to aerosol histamine was remeasured. After endotoxin, 9 of the 11 sheep exhibited decreased Cdyn at a lower concentration of histamine compared with the preendotoxin level (P less than 0.05). The mean of the log dose of histamine necessary to reduce Cdyn to 65% of control was 1.00 +/- 0.16 (SE) before endotoxin and 0.027 +/- 0.29 5 h after endotoxin; i.e., histamine responsiveness was increased. In the last 3 sheep studied, atropine (0.1 mg/kg iv) was given after the second aerosol histamine challenge, and a third dose-response curve was performed. Atropine did not return the endotoxin-induced increase in histamine responsiveness to base line. There was no correlation between the change in histamine responsiveness and the endotoxin-induced changes in Cdyn, FRC, RL, alveolar-arterial O2 difference, pulmonary arterial pressure, or lung lymph flow.

Aerosols↗
PubMed1983

Effect of granulocyte depletion on altered lung mechanics after endotoxemia in sheep.

To examine the role of circulating granulocytes in the airway changes caused by endotoxemia, we measured the response of chronically instrumented unanesthetized sheep to endotoxemia before and after granulocyte depletion with hydroxyurea. Granulocyte depletion did not affect the increases in mean pulmonary arterial pressure caused by endotoxin [peak pressure 59 +/- 8 cmH2O +/- (SE) control, 51 +/- 8 cmH2O granulocyte depleted]. However, the early (30-60 min after endotoxin) airway response to endotoxemia was markedly attenuated. Without granulocyte depletion, endotoxin caused dynamic compliance (Cdyn) to decrease to 41 +/- 10% of the base-line value and total lung resistance (RL) to increase to 283 +/- 61% of base line. When animals were granulocyte depleted, endotoxin decreased Cdyn to 69 +/- 6% (P less than 0.05) of base line and increased RL to 141 +/- 20% of base line (P less than 0.05). Granulocyte depletion also attenuated the effect of endotoxin on arterial oxygenation. During the maximum airway response to endotoxin, the alveolar-to-arterial oxygen gradient was 47 +/- 5 Torr in control studies and 32 +/- 2 Torr in granulocyte depleted studies (P less than 0.05). We conclude that interaction of granulocytes with the lung contributes to the changes in lung mechanics observed following endotoxemia and that the early pulmonary hypertension and the early alterations in lung mechanics caused by endotoxemia are caused by separate processes.

Agranulocytosis↗
PubMed1981

Gram-stain neutrality of Mycobacterium tuberculosis.

Although the Gram stain is a frequently used technique, its application to mycobacterial identification is confusing. A recent clinical experience is presented to demonstrate the gram-neutrality of the air-dried bacillus.

Aged↗
PubMed1981

Catamenial pneumothorax in sisters.

Two sisters had documented pelvic endometriosis and catamenial pneumothoraxes. Both were typical of the 54 reported cases of catamenial pneumothorax in that pneumothoraxes were always on the right and occurred only at menses with onset in the fourth decade. One patient was asymptomatic during 11 months of menstrual suppression with hormones but subsequently required surgery where diaphragmatic perforations were found. The other patient was treated with isoxazole ethisterone with no pneumothoraxes while under suppression. These patients are unlike any of the previously reported cases of familial pneumothoraxes. We have not found a previous report of a familial catamenial pneumothorax.

Adult↗