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Biomedical subjects

U G Mason

Publications and source records attributed to U G Mason.

13 recordsLinked to original sources
PubMed1995

Clinical features of vocal cord dysfunction.

Vocal cord dysfunction (VCD) is a respiratory condition characterized by adduction of the vocal cords with resultant airflow limitation at the level of the larynx. Previously, this condition was described in case reports and in small series. This study reviews all patients hospitalized from 1984 through 1991 in whom VCD was diagnosed. Demographic, historical, physiologic, laboratory, and psychiatric factors were statistically analyzed. Ninety-five patients met the criteria for proved VCD; of these, 53 also had asthma. All patients had laryngoscopic evidence of paradoxical vocal cord motion, with inspiratory and/or early expiratory vocal cord adduction. The patients with VCD without asthma were predominantly young women. In these patients, asthma had been misdiagnosed for an average of 4.8 years. Their medications were identical to those of a control group of patients with severe asthma. Thirty-four of the 42 patients with VCD without asthma were receiving prednisone regularly at an average daily dose of 29.2 mg. Medical utilization was enormous with the VCD group, averaging 9.7 emergency room visits and 5.9 admissions in the year prior to presentation. Also, 28% of the patients with VCD had been intubated. We conclude that VCD can masquerade as asthma and that it often coexists with asthma. This study helps to define the historical and clinical features of VCD.

Adult↗
PubMed1987

Response to therapy of pulmonary Mycobacterium avium-intracellulare infection correlates with results of in vitro susceptibility testing.

Seventy-five patients with pulmonary infection caused by Mycobacterium avium-intracellulare were studied to determine whether results of therapy correlated with in vitro susceptibility testing of mycobacterial isolates. Fifty patients responded to therapy and 25 were nonresponders. The total number of drugs received by responders did not differ significantly from the total number of drugs received by nonresponders. However, responders received significantly more drugs to which their isolate was susceptible in vitro than did nonresponders (2.4 +/- 1.2 versus 1.4 +/- 1.0, p less than 0.001). We conclude that patients with pulmonary M. avium-intracellulare infection should receive chemotherapeutic agents to which their isolate is susceptible in vitro.

Antitubercular Agents↗
PubMed1986

Pathologic findings in disseminated Mycobacterium avium-intracellulare infection. A report of 11 cases.

The pathology of disseminated Mycobacterium avium-intracellulare (MAI) was studied in 20 specimens from 11 patients. The patients ranged from 28 to 65 years and included 8 immunosuppressed and 3 immunocompetent hosts. Specimens of lymph node (five), spleen (one), liver (four), bone (three), pulmonary tissue (three), skin (three), and an aortic aneurysm were included. All cultured specimens grew MAI, but only two-thirds of these showed acid-fast bacilli (AFB) on staining. Some tissues (liver, spleen) showed granulomas similar to those seen in tuberculosis. Other tissues (skin, bone, bronchus) showed necrotizing acute and chronic inflammation with histiocytes but no definite granulomas. Lymph nodes showed a variety of nonnecrotizing and necrotizing granulomatous lesions. In skin, bone, and some lymph nodes, MAI infection appears to be histopathologically distinguishable from tuberculosis. The cases reported here are distinct from those reported in some children and patients with the acquired immunodeficiency syndrome who have massive histiocytic infiltrates with innumerable intracellular AFB. This difference may be due to a specific defect in host response involving T-cell macrophage interaction.

Adult↗
PubMed1985

The bone marrow in disseminated Mycobacterium avium-intracellulare infection.

Thirteen cases of disseminated Mycobacterium avium-intracellulare (MAI), representing a total of 27 bone marrow specimens, were studied. The patients ranged from 25 to 46 years of age and included ten immunocompromised and three immunocompetent hosts. Peripheral blood findings included anemia in all patients, leukopenia in 73%, thrombocytopenia in 45%, and pancytopenia in 45%. Fourteen of the specimens (52%) showed granulomas ranging from small, subtle lymphohistiocytic aggregates to larger lymphohistiocytic lesions and clusters of epithelioid histiocytes; almost half of these lesions were missed initially. Rare acid-fast bacilli were seen in only one case, but 53% grew MAI on culture. In one case of the acquired immunodeficiency syndrome, culture was positive in the absence of inflammation or AFB on staining. These findings are not significantly different from those reported in disseminated Mycobacterium tuberculosis infection.

Adult↗
PubMed1985

Disseminated infection with Mycobacterium avium-intracellulare. A report of 13 cases and a review of the literature.

Thirteen cases of disseminated infection with Mycobacterium avium-intracellulare (MAI) seen at the National Jewish Hospital and Research Center and 24 cases from the literature were analyzed to define clinical and therapeutic features of the disease. Disseminated MAI infection was a disease of immunocompromised and apparently normal hosts. It was acquired from the environment by unknown mechanisms, usually entering the body through the lungs and spreading to include the reticuloendothelial system, bones, and less commonly, the skin. Diagnosis was often delayed and required culture of tissue or secretions. Medical personnel must maintain a high index of suspicion for MAI disease, especially in immunocompromised hosts. These patients should be monitored carefully for evidence of MAI with frequent cultures of blood and bone marrow. Blood culture systems able to recover MAI promptly and reliably should be employed (52, 64). New diagnostic aids, such as the standardized preparation of PPD-B currently being prepared or tests for antibody to MAI, will help in differentiating MAI from other processes. If MAI is recovered, broad-spectrum therapy should be instituted. Response to combination antimicrobial chemotherapy in the patients surveyed in this report was gratifying. Over two-thirds of treated patients responded to therapy. New antimycobacterial agents such as ansamycin and thienamycin have been shown to have activity against MAI in vitro (40, 81, 92) and may further improve therapeutic efficacy. Studies of in vitro synergy, currently in progress in our laboratory, will also help define the optimal therapeutic regimen for each individual patient. While the patients presented in this report had a reassuring response to therapy, those who had many bacilli in the tissues had a poorer outcome. Patients with AIDS often have this lepromatous histology (37) and thus may respond more poorly than the patients in this report even when optimal therapy is employed. Careful monitoring of AIDS patients for MAI infection may permit earlier institution of therapy and improve the chances for control of the infection. Studies to assess the relationship of in vitro sensitivity to therapeutic response in these patients are currently underway in our laboratory. It is hoped that early institution of therapy and optimization of regimens according to in vitro sensitivity data will lead to decreased morbidity and mortality in all patients with MAI infection.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Modulation of immunologic responses in nontuberculous mycobacterial infections with indomethacin.

We have previously reported that impaired in vitro cellular immunity is a common finding in patients with nontuberculous mycobacterioses and that the subnormal responses may be improved by indomethacin. Subsequently, we have studied the in vivo effects of indomethacin on cell-mediated immune functions of four patients with Mycobacterium avium-intracellulare infections. Prior to treatment none of the patients had delayed cutaneous reactions to purified protein derivative (PPD) of the tubercle bacillus, and their lymphocytes had subnormal in vitro proliferation responses to tuberculins from M. tuberculosis and M. avium-intracellulare and to phytohemagglutinin. The administration of indomethacin reconstituted both the in vitro lymphocyte responses and delayed cutaneous hypersensitivity. We propose that the impairment of T-cell dependent immune functions is mediated by a suppressive factor (or factors) that is a metabolic product(s) of the cyclooxygenase pathway of arachidonic acid metabolism. Preferential inhibition of this pathway with indomethacin allows the expression of cell-mediated responses.

Dermatitis, Atopic↗
PubMed1983

Bronchiolitis obliterans. Report of three cases with detailed physiologic studies.

We describe three patients with bronchiolitis obliterans seen at our hospital during the last two years. Their ages were 25, 49 and 69 years. One developed the disease secondary to a probable viral infection, another inhaled fumes, and the third was exposed to unknown precipitating factors. Lung biopsy showed changes compatible with bronchiolitis obliterans in the first two, while in the third, changes were compatible with bronchiolitis obliterans and interstitial pneumonitis. Pulmonary function tests of patient 1 showed severe airflow limitation, increased total lung capacity, a shift of the pressure-volume curve upward with a normal slope, and an elevation of upstream resistance. In patient 3 (bronchiolitis obliterans with interstitial pneumonitis) total lung capacity was normal, the pressure volume curve was shifted slightly to the right and upstream resistance was increased. After treatment with steroids, clinical improvement was observed along with normalization of the pressure-volume curve and a decline in the upstream resistance.

Adult↗
PubMed1979

Vectorcardiographic detection of early hemodynamic abnormalities in chronic obstructive pulmonary disease.

The ability of the vectorcardiogram to detect mild circulatory abnormalities in patients with chronic obstructive pulmonary disease (COPD) is unclear. Therefore, vectorcardiographic changes were correlated with hemodynamic measurements made at rest and during supine exercise in 32 patients with COPD and no clinical or electrocardiographic evidence of right ventricular hypertrophy. Twelve patients had normal hemodynamic data (group 1), nine had abnormal hemodynamic data only during exercise (group 2), and 11 had abnormal hemodynamic data at rest and during exercise (group 3). The extent of rightward terminal QRS forces noted on the vectorcardiogram was significantly less in group 1 (5.5 +/- 8.7 percent) than in either group 2 (19.0 +/- 10.7 percent) or group 3 (17.8 +/- 14.8 percent). Sixty-five percent (13) of the 20 patients with hemodynamic abnormalities had rightward terminal QRS forces of 15 percent or more, whereas only 8 percent (one) of the 12 patients with normal hemodynamic data had such forces of 15 percent or more. The mean of the rightward terminal QRS forces in 27 age-matched normal subjects was 5.0 +/- 5.4 percent, and only one subject had forces of 15 percent or more. We conclude that hemodynamic abnormalities are frequent in patients with COPD and no clinical evidence of right ventricular hypertrophy and that the vectorcardiogram provides an indirect method of detecting these abnormalities.

Adult↗