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Biomedical subjects

J B Hall

Publications and source records attributed to J B Hall.

At least 73 records · Page 4Linked to original sources
PubMed1994

Effects of recombinant bovine somatotropin and dietary energy intake on growth, secretion of luteinizing hormone, follicular development, and onset of puberty in beef heifers.

The effects of dietary energy and recombinant bovine somatotropin (bST) on pattern of LH release, follicular development, and onset of puberty were studied in 40 Angus heifers. At 7 mo of age, heifers were assigned to a 2 x 2 factorial experiment; the main effects were dietary energy (high [HDE]: 14.15 Mcal of ME/d or moderate [MDE]: 10.84 Mcal of ME/d) and somatotropin (bST; 350 mg every 2 wk or vehicle). Beginning at 9 mo of age, heifers were observed twice daily for estrous activity. From 10.5 to 12 mo of age, five heifers from each treatment group were selected for weekly ultrasound examination of ovarian structures and biweekly sequential blood sampling to determine concentrations of LH. Somatotropin treatment altered intermediary metabolism in a manner consistent with enhanced accretion of lean tissue and decreased deposition of fat. The HDE heifers were younger (P < .001) at puberty than the MDE heifers, but BW at puberty was not different among treatment groups. Age and body weight at puberty were not affected by bST. Frequency of LH pulses increased within the 10.5 to 12 mo of age sampling window in HDE-treated heifers but not in MDE heifers (dietary energy x month of age; P < .02). Secretion of LH was unaffected by bST. Ovaries of bST-treated heifers tended (P < .09) to have fewer follicles > 5 mm in diameter than those of vehicle-treated heifers. We conclude that chronic treatment with bST did not alter age at puberty or pattern of LH release in heifers and that even modest differences in energy intake influence the timing of the prepubertal increase in pulsatile LH release.

Animals↗
PubMed1994

Techniques for ventilating patients with obstructive pulmonary disease.

In patients with obstructive lung disease, a strategy of mechanical ventilation that prolongs expiratory time and limits lung hyperinflation can decrease barotrauma. To prolong expiratory time, decrease minute ventilation and inspiratory time. Side effects of this strategy--high peak pressures and hypercapnia--are generally well tolerated. Additional goals for COPD patients include resting and strengthening respiratory muscles and decreasing load on the respiratory system. Short-acting benzodiazepines and morphine are effective for sedation and analgesia. Paralytic agents should be considered only if adequate control of the patient's cardiopulmonary status cannot be achieved by sedation alone.

Barotrauma↗
PubMed1994

Appraisal of the modalities used to evaluate an initial abnormal Papanicolaou smear.

OBJECTIVE: To examine the efficacy of the different modalities used to evaluate an initial abnormal Papanicolaou smear. METHODS: The study population comprised 214 nonpregnant women referred with a Papanicolaou smear diagnosis of cervical intraepithelial neoplasia. Each patient was evaluated by a repeat Papanicolaou smear, colposcopy, and colposcopically directed cervical biopsies. Immediate loop excision was performed to remove the entire transformation zone in all patients. Kappa statistics were calculated to determine agreement among the modalities, and logistic regression was used for determining relative risks (RR). RESULTS: There was 53% agreement between the initial and repeat Papanicolaou smears. When low-grade squamous intraepithelial lesion (SIL) was diagnosed by Papanicolaou smear, there was 89% agreement with the colposcopic impression. However, a colposcopic impression of high-grade SIL was found in only one-third of the women diagnosed with high-grade SIL by Papanicolaou smear. A comparison of the histology of the cervical biopsy and the loop specimen revealed 57% agreement. Univariate analysis indicated that each modality was able to predict the RR of high-grade dysplasia in the loop specimen at a statistical significance level of .05. A colposcopic impression of high-grade dysplasia conferred an RR of 7.43 (95% confidence interval [CI] 2.17-25.49) for high-grade dysplasia in the loop specimen. An initial Papanicolaou smear diagnosis of high-grade SIL did not contribute to the multivariate model for calculating the risk of high-grade dysplasia, as the RR was 1.6 (95% CI 0.68-3.81). CONCLUSION: Patients with an initial Papanicolaou smear showing low-grade SIL would benefit from a repeat Papanicolaou smear and colposcopically directed biopsies before proceeding with loop diathermy. In contrast, patients with a colposcopic impression of high-grade dysplasia combined with high-grade SIL on Papanicolaou smear appear to be candidates for immediate loop excision.

Adolescent↗
PubMed1993

Absence of supply dependence of oxygen consumption in patients with septic shock.

We tested whether oxygen consumption (VO2) was dependent on oxygen delivery (QO2) in 10 patients with septic shock when QO2 was changed by the use of the inotropic agent, dobutamine. The mean acute physiology and chronic health evaluation (APACHE) II score of the patients was 27.3 +/- 8.1 with a mean blood pressure on entry of 66.8 +/- 12.4 mm Hg, and all had been volume resuscitated to a pulmonary artery occlusion pressure of greater than 10 mm Hg. We measured VO2 by analysis of respiratory gases (VO2G) while calculating VO2 by the Fick equation (VO2F) at three different O2 deliveries. When the dobutamine infusion rate was increased from 2.5 +/- 4.0 to 12.3 +/- 6.0 micrograms/kg/min, thermodilution cardiac output increased from 7.7 +/- 2.6 to 10.1 +/- 2.7 L/min (P < .01). Accordingly, dobutamine increased QO2 from 13.5 +/- 3.8 to 18.2 +/- 4.3 mL/min per kg (increase of 36.4% +/- 19.7%; P < .01), but VO2G did not increase (3.2 +/- 0.5 to 3.2 +/- 0.6 mL/min per kg). During these same interventions, the VO2F tended to increase (2.9 +/- 0.7 to 3.4 +/- 0.8 mL/min per kg, P < .06), presumably a spurious correlation because of measurement errors shared by the calculation of VO2F and QO2. Neither lactic acidosis nor acute respiratory distress syndrome (ARDS) conferred supply dependence of VO2G, but the presence of ARDS was predictive of death in this cohort. It is concluded that VO2 is independent of QO2 in patients with septic shock and lactic acidosis. These data confirm that maximizing QO2 beyond values achieved by initial fluid and vasoactive drug resuscitation of septic shock does not improve tissue oxygenation as determined by respiratory gas measurement of VO2.

Adult↗
PubMed1993

Effects of acute, intracerebroventricular administration of insulin on serum concentrations of luteinizing hormone, insulin, and glucose in ovariectomized lambs during restricted and ad libitum feed intake.

To test the hypothesis that the increase in pulsatile LH secretion associated with increased feed intake in growth-restricted lambs is due to elevated insulin concentrations, we evaluated the effects of intracerebroventricular (ICV) administration of insulin on patterns of LH in ovariectomized ewe lambs. After weaning (10 wk of age), 12 lambs were fed to maintain a mean body weight of 18.3 kg. At approximately 32 wk of age a permanent cannula was inserted into the lateral ventricle of each lamb. For the first experiment, animals received 3 ICV injections of either 500 ng (n = 6) or 500 micrograms (n = 6) insulin. Blood samples were collected every 10 min for 8 h, with animals receiving injections at 2, 4, and 6 h. Patterns of LH during the 2-h preinjection period were compared to those in the subsequent 2-h periods following each insulin injection. Insulin did not affect mean LH, LH pulse frequency, or LH pulse amplitude. Only the 500-micrograms injections increased (p < 0.0001) peripheral insulin and decreased (p < 0.001) peripheral glucose. The experimental protocol was repeated during a second experiment conducted after 2 wk of ad libitum feeding, when animals weighed an average of 21.4 kg. Increased feed intake was associated with increases in mean LH, LH pulse frequency, and insulin (p < 0.05). Both doses of insulin decreased (p < 0.01) mean LH and LH pulse frequency. The 500-micrograms injections increased (p < 0.0001) peripheral insulin and decreased (p < 0.001) glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Metered-dose inhaler versus nebulized albuterol in mechanically ventilated patients.

In nonintubated patients, beta 2-agonist bronchodilators are equally effective when delivered by metered-dose inhalers (MDI) or nebulizers (NEB). The delivery of these drugs by MDI to intubated, mechanically ventilated patients has become a widespread practice. To compare the efficacy of the two delivery systems and establish optimal dosing, we prospectively randomized 10 mechanically ventilated patients, with increased airways resistance, to receive albuterol by either MDI or nebulizer in incrementally higher doses. After a 4-hr washout, patients were crossed-over to receive the drug by the alternative route of administration. Albuterol delivered by NEB to a total dose of 2.5 mg reduced the inspiratory flow-resistive pressure (peak-pause airway pressures) from 21.5 +/- 5.7 to 17.6 +/- 5.4 cm H2O (p < 0.01). Nebulized albuterol at cumulative doses of 7.5 mg led to further reductions in 8 of 10 patients (p < 0.1), but led to toxic side effects in 4 of them; in the remaining 6 patients toxicity occurred at a cumulative dose of 15.0 mg. By contrast, albuterol in cumulative doses reaching 100 puffs (9 mg) from an MDI administered into an endotracheal tube adapter did not significantly reduce resistive pressures, and produced no toxicity. We conclude that nebulized albuterol provides objective physiologic improvement, while albuterol administered by MDI through an endotracheal tube adapter has no effect in mechanically ventilated patients with airflow obstruction. Nebulizer treatments can and should be titrated to higher-than-conventional doses, using toxic side-effects and physiologic response to guide therapy.

Adult↗
PubMed1993

Pleural effusion masquerading as myocardial infarction.

The effects of pleural effusions on the ECG have not been well studied. We report herein the case of a patient with extreme QRS axis deviation mimicking acute myocardial infarction. Thoracentesis caused the return of a more normal axis.

Aged↗
PubMed1992

Does tyrosine act as a nutritional signal mediating the effects of increased feed intake on luteinizing hormone patterns in growth-restricted lambs?

We tested the hypothesis that the increase in LH secretion associated with elevated feed intake in nutritionally growth-restricted lambs is due to increased availability of tyrosine (TYR). Ovariectomized ewe lambs with abomasal cannulae were fed a complete diet in amounts (0.6 Mcal of net energy/day) sufficient to maintain a body weight of 21.7 +/- 1.0 kg between 10 and 32 wk of age. At 32 wk of age, lambs were assigned at random to one of three treatments: 1) maintenance feeding + abomasal infusion of water (M; n = 6); 2) maintenance feeding + abomasal infusion of TYR (M + TYR; n = 7); or 3) twice maintenance feeding + abomasal infusion of water (TM; n = 6). TYR (1.25 g/100 ml water) or water (100 ml) was delivered as a bolus injection at 0600, 1200, 1800, and 2400 h daily for 23 days. Plasma concentrations of TYR 10 and 22 days after initiation of treatments were higher (p less than 0.001) in the TM and M + TYR groups compared to the M group and were elevated (p less than 0.001) in the M + TYR group compared to the TM group. Concentrations of TYR in hypothalami were higher (p less than 0.01) in the M + TYR and TM groups than in the M group, and greater (p less than 0.005) in the M + TYR group compared to the TM group. Overall, there was a linear (p less than 0.001) correlation between plasma and hypothalamic concentrations of TYR.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Effects of nutrition and season on the onset of puberty in the beef heifer.

Age at puberty is a major determinant of lifetime reproductive efficiency of beef cows. Research conducted during the past 20 yr has documented the major endocrine events leading to first ovulation in heifers. The critical event seems to be a prepubertal increase in pulsatile LH secretion. Environment influences timing of puberty onset in beef heifers. Nutrition and season are two of the better-defined variables that have been studied. Age at puberty is related inversely to plane of nutrition. The effect of nutrition on sexual maturation involves effects on timing of the prepubertal increase in LH secretion and seems to involve the LH pulse generating system located in the hypothalamus. The precise mechanism by which nutrition influences pulsatile LH secretion has not been elucidated, but signals reflecting metabolic status seem to be involved. Seasonal conditions of the early (birth to 6 mo of age) and late (6 to 12 mo of age) postnatal periods also influence timing of puberty onset in the heifer. Autumn-born heifers attain puberty at younger ages than do spring-born heifers, and exposure to spring-summer temperatures and photoperiods during the second 6 mo of life reduces age at puberty regardless of season of birth. Photoperiod may be the major seasonal cue that influences puberty onset in cattle. Limited evidence suggests that melatonin, a pineal hormone, is involved with transducing photic stimuli into neuroendocrine signals that influence LH secretion. If the physiological mechanisms mediating the effects of nutrition and season on timing of puberty onset are determined, then management strategies for reducing age at puberty can be enhanced.

Animal Nutritional Physiological Phenomena↗
PubMed1991

Effects of dietary energy level on luteinizing hormone and adrenal function in the post partum beef cow.

The effects of dietary energy and suckling on adrenal function and luteinizing hormone (LH) concentrations were investigated in primiparous postpartum cows. Ten heifers were assigned at calving to either high (22.8 Mcal/day) or low (15.2 Mcal/day) energy diets. Blood samples were collected every 15 minutes for 8 hours on 28, 42, and 56 days post partum. Calves were allowed to suckle ad libitum during sampling periods. Serum samples were analyzed by radioimmunoassay for LH and cortisol. Concentrations of catecholamines were quantified by reverse-phase HPLC. Body weights were decreased (P<0.01) by low energy intake. In addition, low energy diet cows had lower mean LH concentrations (0.97+/-0.09 vs 1.57+/-0.07 ng/ml), P<0.05) than high energy diet cows. Luteinizing hormone concentrations in high energy diet cows increased with days post partum, resulting in a treatment-by-time interaction (P<0.005). Treatment did not affect mean cortisol concentrations. However, within 15 minutes of suckling cortisol release was significantly above baseline in 77% of the observed suckling events. Dihydroxyphenylalanine (DOPA) increased in high energy diet cows compared with that of low energy diet cows (2,833+/-243 vs 1,294+/-243 pg/ml, P<0.01). Norepinephrine (NE) and 3,4-dihydroxyphenylacetic acid (DOPAC) were not influenced by treatment. Plasma NE decreased during the postpartum interval (P<0.005). These data suggest that reduced energy intake may prevent the increase in LH associated with increasing days post partum and alter adrenal function. In addition, spontaneous suckling events elicit a release of cortisol.

Journal Article↗
PubMed1991

A comparison study of pain associated with endocervical sampling techniques.

Endocervical curettage (ECC) is an important tool in the diagnosis and treatment of cervical neoplasia. Its use has been limited, however, because of the pain it can cause. We show that the use of a soft plastic curette cause statistically less pain without compromising the quantity or quality of the sample.

Adult↗
PubMed1991

Efficacy of daily routine chest radiographs in intubated, mechanically ventilated patients.

OBJECTIVE: To determine the efficacy of daily routine chest radiographs in intubated, mechanically ventilated patients. DESIGN: With approval of our Institutional Review Board, data were collected prospectively to compare bedside clinical assessment of the patient with the routine chest radiograph in determining the occurrence of new findings. Before review of the daily chest film, patients underwent careful evaluation of clinical and physiologic variables by critical care physicians, who then documented the new findings and the diagnostic and therapeutic interventions required. These results were compared with the interpretations of the daily chest film by radiologists blinded to the clinical assessment. Correlations were made of the new major (requiring immediate intervention) and new minor (abnormal but not requiring immediate intervention) findings noted by clinical assessment and chest radiography. SETTING: This study was conducted in a ten-bed medical/surgical ICU admitting 650 to 750 patients/yr, a majority of whom require intubation and mechanical ventilation. PATIENTS: Seventy-seven episodes of intubation and mechanical ventilation in 74 patients were evaluated. Only patients with translaryngeal intubation and a requirement for mechanical ventilation beyond 24 hrs were considered for inclusion in this study. Major admitting diagnoses included malignancy, aspiration pneumonia, sepsis, liver failure, chronic obstructive pulmonary disease, and adult respiratory distress syndrome. INTERVENTIONS: Specific interventions were not made by study design; instead, clinical practice with and without the routine chest radiograph was compared. MEASUREMENTS AND MAIN RESULTS: The measure of comparison between the chest radiograph and clinical assessment was the correlation between the two for a number of major and minor findings defined in advance. A total of 538 chest radiographs were examined; of these, 354 (65.8%) did not disclose either new major or new minor findings as defined. One hundred sixty-three radiographs disclosed only new minor findings, 40.5% of which were anticipated by bedside assessment. However, in 13 (17.6%, 95% confidence interval 9% to 26%) of our 74 patients, new major findings were discovered only by chest radiography. CONCLUSIONS: These data demonstrate that, while a large percentage of radiographs will not disclose new findings, routine daily studies have a substantial impact on the management of intubated, mechanically ventilated patients in the ICU. These findings support the use of daily chest radiographs in critically ill patients.

Adolescent↗
PubMed1990

Management of the critically ill asthmatic patient.

Status asthmaticus is a life-threatening condition characterized by rapid or inexorable progression of airflow obstruction that may lead to respiratory failure. It must be distinguished from other causes of dyspnea with signs of airflow limitation, and therapy must then be directed at relief of bronchospasm and airway inflammation, with use of multiple pharmacologic agents. Patients require moment-to-moment assessment until airway disease reverses. During this early portion of their course, intubation and mechanical ventilation may be required. Successful management on the ventilator requires an understanding of underlying abnormalities of lung mechanics and the interaction of the lungs and circulation.

Asthma↗
PubMed1990

The mechanism of respiratory arrest in inspiratory loading and hypoxemia.

Respiratory arrests occur in the clinical setting of respiratory failure, but the mechanism is unclear. We used a dog model with increased inspiratory resistance and hypoxemia to explore the cause. We hypothesized that respiratory muscle fatigue (RMF) played a role in these respiratory arrests, and that the combination of hypoxia and resistive loading would produce respiratory arrest by the mechanism of RMF. Our preparation had transdiaphragmatic pressures that were 40% of maximum (Pdimax = 46.3 +/- 10.0 cm H2O) and progressive hypoxia resulting in a final arterial PO2 of 38 +/- 9 mm Hg and a phrenic vein O2 content of 1.8 +/- 1.1 mg/dl. Instead of failure associated with carbon dioxide retention and RMF, we saw a rapid decrease in tidal volume and respiratory rate, leading to apnea over 30 to 60 s while the diaphragm still responded with significant pressure generation when externally stimulated. These results suggest that respiratory muscle fatigue may not be a major factor in respiratory arrests associated with inspiratory loading and hypoxia, but that suppression of central drive, induced by the combination of inspiratory loading and hypoxemia, may be important.

Acid-Base Equilibrium↗
PubMed1990

Yellow nails, lymphedema and pleural effusion. Treatment of chronic pleural effusion with pleuroperitoneal shunting.

Pleural effusion secondary to lymphedema may be chronic, symptomatic and refractory to treatment, occasionally requiring invasive and painful procedures such as chemical pleurodesis, open pleural abrasion or pleurectomy to achieve control of the effusion and gain symptomatic relief. We report a patient with yellow nail syndrome and chronic pleural effusion successfully treated with pleuroperitoneal shunting.

Aged↗