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Biomedical subjects

R B Gammon

Publications and source records attributed to R B Gammon.

8 recordsLinked to original sources
PubMed1995

Clinical risk factors for pulmonary barotrauma: a multivariate analysis.

Previous investigations have suggested that elevated airway pressures increase the risk of ventilator-induced pneumothorax. However, risk factor analysis using multivariate techniques has not been done. We investigated the hypothesis that airway pressures would not independently correlate with pneumothorax when underlying disease was considered. All ventilated patients over a 1 yr period in the Hohenburg Critical Care Unit at the University of Alabama were followed until death or discharge from the ICU. Ventilator data were collected daily and the presence of pneumomediastinum and pneumothorax determined by review of chest radiographs. Maximal values of airway pressures, minute ventilation, tidal volume, and respiratory rate, as well as age, sex, and underlying disease, were entered into logistic regression analysis. A total of 168 patients was studied, and 20 experienced pneumothorax. Multivariate analysis of the entire ventilated population revealed that only the presence of ARDS independently correlated with pneumothorax. A similar analysis performed on the ARDS population revealed independent correlation only with male sex. Trends toward elevation in airway pressures were seen that did not reach statistical significance. We conclude that development of pneumothorax is most closely correlated with underlying disease, specifically ARDS, and that the associations previously noted between airway pressures and barotrauma largely relate to the occurrence of high airway pressures in ARDS.

Adult↗
PubMed1994

Vitamin A is excreted in the urine during acute infection.

Episodes of acute infection are thought to deplete body stores of vitamin A. The mechanism by which this might occur is not known, but increased metabolic requirements are presumed to play a role. We have found, however, that significant amounts of retinol and retinol-binding protein (RBP) were excreted in the urine during serious infections, whereas only trace amounts were found in the urine of healthy control subjects. The geometric mean excretion rate in 29 subjects with pneumonia and sepsis was 0.78 mumol retinol/d. Subjects with fever (temperature > or = 38.3 degrees C) excreted significantly more retinol (geometric mean = 1.67 mumol/d) than did those without fever (0.18 mumol/d; t = 3.53, P < 0.0015). Aminoglycoside administration and low glomerular filtration rates (< 35 mL/min) were also associated with higher rates of urinary retinol excretion. Thirty-four percent of patients excreted > 1.75 mumol retinol/d, equivalent to 50% of the US recommended dietary allowance. These data show that vitamin A requirements are substantially increased during serious infections because of excretion of retinol in the urine, and suggest that these losses are due to pathologic changes associated with the febrile response.

Adult↗
PubMed1992

Pulmonary barotrauma in mechanical ventilation. Patterns and risk factors.

The incidence of mediastinal emphysema (ME) and pneumothorax (PTX) was analyzed to determine the roentgenographic patterns and risk factors for the development of barotrauma in a population of mechanically ventilated patients. The roentgenograms of 139 intubated patients admitted to our medical intensive care unit over a ten-month period were evaluated for the presence of ME and PTX. Barotrauma was diagnosed in 34 of these patients, and ME was the initial manifestation in 24 patients. Of these patients with initial ME, ten subsequently developed PTX, a positive predictive value of 42 percent. The adult respiratory distress syndrome (ARDS) patient population was at highest risk for barotrauma, with an intermediate risk seen in those admitted with COPD or pneumonia. Values of peak inspiratory pressure, positive end-expiratory pressure level, respiratory rate, tidal volume, and minute ventilation were significantly elevated in patients who developed barotrauma as compared with patients who did not develop barotrauma. However, these elevations in part reflect the high incidence of barotrauma in the ARDS population, a patient group in which all of the above parameters were elevated.

Barotrauma↗
PubMed1992

Bronchiolitis obliterans organizing pneumonia associated with systemic lupus erythematosus.

Bronchiolitis obliterans organizing pneumonia (BOOP) is a pathologic entity characterized by the formation of plugs of fibrous tissue in bronchioles and alveolar ducts. It has been described in association with several connective tissue diseases including rheumatoid arthritis, polymyositis-dermatomyositis, and mixed connective tissue disease. Well-documented reports of BOOP in patients with systemic lupus erythematosus (SLE) are limited. We report two patients with SLE who presented with subacute respiratory illnesses due to BOOP, adding further strength to the association of this entity with SLE.

Adult↗
PubMed1991

Modulation of bFGF in lung fibroblasts by TGF-beta and PDGF.

Growth factors produced by alveolar macrophages are thought to promote the fibroblast proliferation within interstitial spaces of fibrotic lungs. This study investigated the possibility that the macrophage-produced growth factors might modulate the expression of basic fibroblast growth factor (bFGF) by lung fibroblasts. To evaluate this question, bFGF gene expression and protein production were evaluated in normal adult human lung fibroblast cell lines. Under normal culture conditions, the fibroblasts expressed the bFGF gene as two major transcripts (7.1, 3.7 kb). The addition of fetal calf serum (FCS) to serum-starved fibroblasts caused a 5- to 10-fold increase in bFGF expression. Steady-state bFGF expression was increased 108% by platelet-derived growth factor (PDGF) and 602% by transforming growth factor-beta (TGF-beta). Insulin-like growth factor-1 had no significant effect on bFGF expression. Nuclear runoff studies demonstrated that both PDGF and TGF-beta increased the relative rates of bFGF transcription in the fibroblasts. Western blot analysis of lysates from fibroblasts treated with either PDGF or TGF-beta had no detectable increase in bFGF protein above unstimulated controls. However, the simultaneous addition of PDGF and TGF-beta, or FCS, produced a marked increase in bFGF. These experiments show that two growth factors present in the alveolar airspace compartment of fibrotic lungs can promote the expression of bFGF within lung fibroblasts.

Adult↗