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Biomedical subjects

G L Colice

Publications and source records attributed to G L Colice.

At least 55 records · Page 3Linked to original sources
PubMed1992

Blood biochemical characteristics of cattle at sea level and at moderately high altitude (3,000 m).

We investigated the biochemical composition of blood from Holstein cows, native breed (criollas), and cows descended from fighting bulls (Vacas de lidia) raised at an altitude of 3,000 m (moderately high altitude, MHA), and compared the results with those from Holsteins and cows of similar genetic ancestry as the criollas (scrub cows), both raised at sea level (SL), to determine blood biochemical values characteristic of adaptation to high altitude. Only potassium and calcium concentrations were similar among groups. Glucose concentration was lower in MHA cows, with the exception of Vacas de lidia. Serum bicarbonate concentration was lower in MHA cows; this finding can be explained by hyperventilation in the hypoxic environment. Serum magnesium concentration was lower in SL and MHA Holsteins than in other groups. Serum phosphate concentration was lower in scrub cows, MHA Holsteins, and criollas than in other groups. Cholesterol concentrations were lower in SL Holsteins, whereas triglycerides were higher in scrub cows and MHA Vacas de lidia. Concentration of high-density lipoprotein was significantly greater in Vacas de lidia and less in MHA criollas than in the other groups. Uric acid and total protein were higher in MHA groups. Using radioimmunoassay for human proteins, thyroxine-binding globulin was undetectable. Total and free thyroxine and free triiodothyronine were higher in scrub cows, followed by Vacas de lidia; lower values were detected in SL and MHA Holsteins and MHA criollas.

Altitude↗
PubMed1991

Does the mediastinum of patients with non-small cell lung cancer require histologic staging? Future standards for computed tomography.

We asked whether noninvasive staging of the mediastinum is a reasonable alternative to invasive staging in patients with non-small cell lung cancer. Decision analysis was used to compare strategies relying upon mediastinoscopy, bronchoscopy with transbronchial needle aspiration, and/or thoracotomy for histologic or cytologic confirmation of mediastinal stage to two strategies primarily relying upon computed tomography for assessing the mediastinum. Life expectancy was the outcome of interest. Extensive sensitivity analysis showed that, if the specificity of computed tomography for mediastinal disease was above 0.90, a strategy primarily relying upon computed tomography to stage the mediastinum would provide a life expectancy within 1 month of that provided by invasive testing. The difference in life expectancy between the invasive and noninvasive staging strategies decreased further as the prior probability of unresectable disease increased. Surprisingly, the sensitivity of computed tomography for mediastinal disease was of little importance in determining overall life expectancy. These results suggest that noninvasive imaging techniques might reliably replace invasive mediastinal staging if their specificity exceeds 0.90.

Carcinoma, Non-Small-Cell Lung↗
PubMed1991

Technical standards for tracheal tubes.

To provide an appropriate context for understanding the standards for tracheal tubes, this article first summarizes some of the historical highlights leading to the development of present-day tracheal tubes. It also describes the current manufacturing guidelines for tracheal tubes and the rationale for these standards.

Humans↗
PubMed1990

Decision analysis, public health policy, and isoniazid chemoprophylaxis for young adult tuberculin skin reactors.

As part of a plan to eliminate tuberculosis in America, tuberculin skin testing was advised for all US citizens, with isoniazid chemopreventive therapy administered to appropriate positive reactors. Implementation of this plan, however, may be limited by concerns over which skin test reactors should receive isoniazid therapy. Recent decision analyses suggest that, contrary to American Thoracic Society guidelines, asymptomatic skin test reactors under age 35 years with normal chest roentgenograms and no predisposing conditions to tuberculosis reactivation will not benefit from isoniazid chemopreventive therapy. Repeated analysis of these studies reveals that calculated life expectancy depends on estimates of the probability of certain chance outcomes. If the isoniazid-related hepatitis case-fatality rate is below 1%, isoniazid chemopreventive therapy appears to be beneficial. A literature review suggests that this rate is indeed this low. If the tuberculosis case-fatality rate is above 6.7%, also supported by the literature, the advantages of isoniazid therapy are further increased. This repeated analysis should reassure physicians that isoniazid chemoprophylaxis for tuberculin skin test reactors is beneficial to the individual and consonant with public health policies.

Adult↗
PubMed1989

Beta-endorphin activity and hypercapnic ventilatory responsiveness after marathon running.

To investigate the hypothesis that endurance exercise may lead to a decrease in ventilatory chemosensitivity as possibly mediated by an increase in endogenous beta-endorphins, we measured hypercapnic ventilatory responsiveness (HCVR) and circulating beta-endorphin immunoreactivity in six runners before and after a marathon (42.2 km) race and after administration of 10 mg iv naloxone. Similar testing was performed at identical time periods on the day before the marathon as control data. On each occasion, HCVR was measured twice 15 min apart, and the mean value was used for analysis. Six active (training distance 50-104 km/wk) and experienced (no. of marathons completed, 1-25) runners participated in the study. There were no significant changes in beta-endorphin activity or HCVR on the control day. All runners experienced a rise in beta-endorphin activity from premarathon (21.3 +/- 16.0 pg/ml) to immediate postmarathon (89.6 +/- 84.9 pg/ml) values (P less than 0.05). However, HCVR showed no significant change at any of the three testing periods on the marathon day. To investigate whether a time delay may have affected the lack of response to naloxone, additional testing was performed in five subjects, except that 10 mg iv naloxone was given within 10 min after completion of the marathon, and then HCVR was measured. Although there was a greater than fourfold increase in beta-endorphin immunoreactivity after the marathon, there was no significant change in HCVR after naloxone administration. We conclude that natural increases in endogenous beta-endorphin activity associated with marathon running do not modulate central chemosensitivity.

Adult↗
PubMed1989

Laryngeal complications of prolonged intubation.

In this study, 82 patients who experienced translaryngeal intubation (TLI) for more than four days were prospectively evaluated for laryngeal complications. At the time of extubation or tracheostomy, direct laryngoscopy was performed in these patients and laryngeal damage evaluated. A typical pattern of laryngeal damage was seen, consisting of mucosal ulcerations along the posterior-medial aspects of both vocal cords and varying degrees of laryngeal edema in 77 patients (94 percent). Performance of a tracheostomy and presence of neuromotor activity were associated with the severity of laryngeal damage, but duration of TLI was not. Laryngoscopy was repeated at two-week intervals in 54 patients and laryngeal damage was resolved within four weeks in 63 percent. These 54 patients were evaluated for adverse clinical effects arising from TLI-induced laryngeal pathology and no relationship was found between laryngeal pathology seen at initial laryngoscopy and the development of adverse effects.

Hoarseness↗
PubMed1989

Neurologic disorders and respiration.

The impact of neurologic disorders on the respiratory system is considered as a functional-anatomic-pathologic sequence. Functional roles of the central, peripheral, and autonomic nervous systems in respiration are described. The effects of pathologic conditions are then discussed based on this functional-anatomic background.

Autonomic Nervous System↗
PubMed1988

Regulation of aldosterone secretion during hypoxemia at sea level and moderately high altitude.

The aldosterone and cortisol responses to small doses of ACTH (0.125, 0.25, 0.5, and 1.25 micrograms) after dexamethasone administration were measured in normal subjects at sea level while breathing room air (mean O2 saturation, 97 +/- 0.9%) and again while breathing hypoxic gas to lower the O2 saturation to 90%. A population of subjects matched for age and sex adapted to 3000 meters above sea level living in Colombia, South America, was also studied (mean O2 saturation, 94 +/- 0.7%). Hypoxemia, either induced at sea level or as a consequence of high altitude living, resulted in significant inhibition of aldosterone secretion after progressive administration of increasing doses of ACTH, but did not affect the cortisol response to ACTH. In addition, it was associated with higher plasma atrial natriuretic hormone levels. PRA declined only during acute hypoxemia induced at sea level and did not change during sea level normoxemia or high altitude living. Plasma sodium and potassium concentrations were no different in the three experimental conditions. We conclude that hypoxemia inhibits ACTH-stimulated aldosterone secretion and speculate that atrial natriuretic hormone may have mediated this effect.

Adrenocorticotropic Hormone↗
PubMed1986

Aldosterone response to angiotensin II during hypoxemia.

Exercise in humans causes increases in plasma renin activity (PRA) and plasma aldosterone concentrations (PAC) except when performed at high altitude or while the subjects breathe hypoxic gas. Under those conditions, PRA increases with exercise but PAC does not. We speculated that the PAC suppression during hypoxemic exercise was due to hypoxemia-induced release of a circulating inhibitor of angiotensin II-mediated aldosterone secretion. To test this hypothesis, we measured the PAC response to graded infusions of angiotensin II during hypoxemia and normoxemia. Eight normal volunteers were given increasing doses of angiotensin II (first 2 ng X kg-1 X min-1 and then 4, 8, and finally 12 ng X kg-1 X min-1, each for 20-min periods) on 2 separate days, once while breathing room air and the other day while breathing hypoxic gas adjusted to maintain the subjects' hemoglobin saturation at 90%. The PAC response to different doses of angiotensin II did not significantly differ during hypoxemia from normoxemia. We conclude that our model of hypoxemia does not cause release of an inhibitor of angiotensin II-mediated aldosterone release.

Adult↗
PubMed1986

The effect of furosemide during normoxemia and hypoxemia.

The effect of furosemide infusion was studied in 6 normal subjects and 6 patients with severe COPD and right ventricular failure during normoxemia and hypoxemia. In normal subjects, hypoxemia alone caused an insignificant (p less than 0.15) fall in plasma aldosterone concentrations (PAC). Intravenously administered furosemide resulted in significant (p less than 0.05) increases in PAC during both normoxemia and hypoxemia. After furosemide treatment mean arterial pressure (MAP) was significantly lower and arginine vasopressin (AVP) was significantly higher (p less than 0.05) with hypoxemia than with normoxemia. These changes in MAP and AVP were strongly correlated (r = -0.84). Urinary losses of water and sodium were similar after furosemide treatment with hypoxemia and normoxemia. In patients with right ventricular failure, neither changes in oxygenation nor furosemide infusion affected the markedly elevated baseline PRA and PAC levels. Arginine vasopressin levels were significantly higher with hypoxemia than with normoxemia, but urinary losses of water and salt did not differ between the 2 study days. We conclude that hypoxemia does not affect the PAC increase or urinary volume and sodium response to furosemide.

Adult↗
PubMed1986

Tracheal stenosis complicating cutaneous burns: an underestimated problem.

Upper airway obstruction complicating thermal injury is usually considered as an acute problem that occurs during the initial 24 h after exposure. We report 3 patients who developed symptomatic upper airway obstruction caused by severe tracheal stenosis late in the course of burn management. The interaction of inhalation airway injury, mechanical trauma from tracheal intubation, and other etiologic factors commonly present in this setting demands close monitoring for this potential problem, and careful reconsideration of the indications for "prophylactic" intubation.

Adolescent↗
PubMed1986

Pulmonary edema.

The lungs are marvelously designed to handle fluid. The mechanical properties of the lungs and the lymphatics act simply and efficiently to drain fluid out of the pulmonary interstitium. Despite the enormous blood flow through the pulmonary and bronchial circulation, a dynamic equilibrium is maintained between fluid fluxing out of the vasculature into the pulmonary interstitium and fluid being drained out of the lungs by the lymphatics. This is obviously important because maintaining "dry" air spaces is essential for normal pulmonary function. Fluid accumulates in the lung when flux across the vascular endothelium exceeds lymphatic drainage. Two different types of abnormalities will result in accumulation of fluid, an increase in pulmonary microvascular pressure and an increase in the pulmonary vascular endothelial permeability to protein. Regardless of the type of abnormality causing pulmonary edema, fluid tends to accumulate in the lungs in a predictable pattern based on the same mechanical properties that normally keep the lung dry. Only by understanding the normal process of fluid handling will the clinician truly appreciate the consequences of pulmonary edema.

Aged↗
PubMed1985

Effect of hypoxemia on the renin-angiotensin-aldosterone system in humans.

Hypoxemia was induced in five subjects older than 40 (group 1) and five younger than 35 yr (group 2) on normal and low-salt diets by having the subjects breathe hypoxic gas. The fractional inspired O2 of the hypoxic gas was regulated so that group 1 hemoglobin saturations fell to 90% for 1 h. Group 2 subjects had desaturation to 90% for 1 h followed by desaturation to 80% for a 2nd h. Plasma renin activity (PRA), angiotensin-converting enzyme activity (ACE), and plasma cortisol levels did not change during hypoxemia. Plasma aldosterone levels fell in both groups during the 1st h of hypoxemia. Decreases were greatest during salt restriction and were significant (P less than 0.01) for the combined groups. Plasma aldosterone levels plateaued during the 2nd h of more severe hypoxemia in group 2. Hepatic blood flow, measured by indocyanine green clearance, and the adrenal response to exogenous adrenocorticotropic hormone, measured by changes in plasma cortisol and aldosterone, were not changed by hypoxemia in group 2 subjects. These results indicate that plasma aldosterone falls during hypoxemia despite unchanged PRA, ACE, hepatic blood flow, and adrenal function.

Adrenal Glands↗
PubMed1985

Effect of normoxemic and hypoxemic exercise on renin and aldosterone.

Five subjects (group 1) performed progressive treadmill exercise on 2 separate days, once while breathing room air (normoxemic) and the other time while breathing gas with a fractional inspired O2 of 17% (hypoxemic). Five other subjects (group 2) performed two progressive treadmill exercise tests on each of 2 separate days in a crossover design. On 1 day normoxemic exercise was first, followed by hypoxemic exercise, and on the other day the pattern was reversed. Plasma renin activity (PRA) increased to a similar extent with hypoxemic exercise as with normoxemic exercise. Plasma aldosterone concentrations (PAC) rose to a significantly higher level during normoxemic exercise than with hypoxemic exercise. Comparing changes in PRA to PAC with progressive exercise revealed dissociation of PAC from PRA during hypoxemic exercise. The PAC response remained depressed when normoxemic exercise followed hypoxemic exercise. These results indicate that hypoxemia interferes with PRA-mediated aldosterone secretions. The mechanism of this inhibition is unclear.

Adolescent↗
PubMed1985

Comparison of computerized tomography with fiberoptic bronchoscopy in identifying endobronchial abnormalities in patients with known or suspected lung cancer.

Determining the presence and extent of endobronchial involvement is an important part of the evaluation of patients with known or suspected lung cancer. Bronchoscopy is accepted as the best technique for such an evaluation. We have studied the potential usefulness of computerized tomography (CT) for examining the airways by retrospectively comparing CT scans with fiberoptic bronchoscopy findings in 53 patients with known or suspected lung cancer undergoing both tests during the same hospitalization. We have found CT to be moderately accurate in predicting the presence of airway abnormalities (sensitivity from 63 to 85%, specificity form 61 to 77%) but inaccurate in defining the type of abnormality seen at bronchoscopy (localized mucosal abnormality, endobronchial mass, or extrinsic compression). We feel that CT, using standard techniques, should not be relied on for the identification of endobronchial abnormalities in patients with known or suspected lung cancer.

Bronchoscopy↗
PubMed1985

Neurogenic pulmonary edema.

Neurogenic pulmonary edema is an anomaly because it cannot be categorized into either of the two major types of pulmonary edema. Both high-pressure and increased-permeability abnormalities may be involved in the pathogenesis of neurogenic pulmonary edema. Furthermore, the mechanisms responsible for these abnormalities appear quite complex. The high-pressure insult appears to be a function of systemic hypertension, pulmonary venoconstriction, negative and positive inotropic factors, and intrinsic myocardial function. Mediators of the pulmonary endothelial permeability defect have not been defined. Although the high-pressure and increased-permeability abnormalities seem to develop through separate mechanisms, their combined effect is probably synergistic on the accumulation of extravascular lung water. The neurologic pathways responsible for initiating neurogenic pulmonary edema remains a mystery. Despite the questions and uncertainties still surrounding neurogenic pulmonary edema, the substantial progress made in understanding the clinical expression, incidence, and pathogenesis of this syndrome does provide a framework for a reasonable approach to its clinical management.

Adult↗