Biomedical subjects
F S Virant
Publications and source records attributed to F S Virant.
Exercise-induced bronchospasm: epidemiology, pathophysiology, and therapy.
Exercise induced bronchospasm (EIB) is a common clinical problem seen in most individuals with chronic asthma and in nearly half the allergic population. Bronchospasm is typically present 5-15 min after cessation of activity, with spontaneous resolution usually occurring within 20-60 min. The stimulus for EIB is apparently a combination of airway cooling and drying, which results in pulmonary mast cell mediator release. Bronchospasm is generally more severe if there is greater baseline bronchial hyperreactivity or higher intensity of exercise. The treatment of choice for EIB is preexercise administration of a beta-adrenergic agonist. Other useful therapies may include cromolyn, theophylline, calcium channel blockers, anticholinergics, and antihistamines. The crucial step for clinicians caring for these patients is making the diagnosis of EIB. The condition responds well to therapy, and treatment may allow for greater enjoyment of activity and enhanced athletic performance.
Cromolyn versus triamcinolone acetonide for youngsters with moderate asthma.
Although both cromolyn (C) and inhaled corticosteroids are anti-inflammatory therapies for childhood asthma, there are few controlled comparisons of these medications for asthma therapy in children. None were conducted in the United States, and none specifically study triamcinolone acetonide (T) versus C. This 12-week evaluation followed 31 youths, aged 8 to 18 years, with moderate asthma who were assigned to receive C or T according to a prerandomized and blinded code. Patients were instructed to take two inhalations from the study metered-dose inhaler (active T or placebo) and to inhale the contents of one study-provided ampule (C, 20 mg, or placebo) from a compressor-driven home nebulizer three times per day. Patients also used albuterol, two inhalations from a metered-dose inhaler, three times a day (before study medication) and, additionally, if needed. Patients maintained a daily diary, recording extra medication use, adverse experiences, peak flow rates morning and night, and asthma symptom scores. Laboratory assessment of pulmonary function was done at 1, 4, 8, and 12 weeks. Cosyntropin challenge and methacholine bronchoprovocation challenge were performed at the beginning and end of the study. C and T provided similar, adequate asthma control. Symptoms of wheezing, cough, and chest tightness decreased, and daily peak expiratory flow rate increased with both regimens compared to during a 2-week baseline when patients received medication only as needed. There was no significant change in methacholine sensitivity and no change in endocrine function, as measured with fasting plasma control before and after administration of cosyntropin.(ABSTRACT TRUNCATED AT 250 WORDS)
Immunologic defects in patients with refractory sinusitis.
Sixty-one patients with chronic sinusitis who were referred for an allergy evaluation were evaluated for immunologic competence including assessment of quantitative serum immunoglobulin levels, IgG subclass levels, and response to pneumococcal and Haemophilus influenzae vaccines. In addition to chronic sinus disease, recurrent otitis media and asthma exacerbation were common problems in this group. Five patients had an elevated age-adjusted IgE level and 22 patients had positive prick tests to one or more environmental inhalants; these findings suggest an allergic component in this subgroup. Twelve additional patients had highly reactive intradermal tests to common environmental allergens, which also may be clinically significant for underlying atopy. Eleven patients had low immunoglobulin levels, 6 had low immunoglobulin levels and vaccine hyporesponsiveness, and 17 had poor vaccine response only. Thus, 34 of 61 patients with refractory sinusitis had abnormal results on immune studies, with depressed IgG3 levels and poor response to pneumococcal antigen 7 being most common. In addition to allergy, immunologic incompetence may be an important etiologic factor in patients with chronic, refractory sinusitis.
Human nasal epithelium: characterization and effects of in vitro exposure to sulfur dioxide.
Human nasal turbinate tissue from surgical specimens was dissected free of connective tissue, and primary epithelial cultures were established by explant techniques. Transmission electron microscopy revealed that cultured cells retained homogeneous cytoplasmic granules, tonofilaments, and desmosomes and formed a homogeneous monolayer. The epithelial cells stained positively with cytokeratin antibodies AE1, AE3, and 35BH11 but failed to stain with two other cytokeratin antibodies, AE2 and 34BE12. Staining was also positive with anti-desmoplakin I and II but negative with antivimentin (43BE8), anti-desmin, and anti-human factor VIII antibodies. Cultured cells were exposed to filtered air or sulfur dioxide at 1-5 ppm for 30-60 min. Although there was no increase in cell lysis as measured by chromium-51 release, SO2 exposure significantly inhibited [3H]leucine incorporation compared to air exposure. This effect was dependent on both SO2 concentration and exposure duration. Control experiments revealed that these SO2 effects were not caused by the [H+] load produced by SO2 exposure. Electron microscopy of cells exposed to air or SO2 did not show any significant morphological differences.
Abnormal antibody responses in patients with persistent generalized lymphadenopathy.
Persistent, generalized lymphadenopathy (PGL) is a recognized component of human immunodeficiency virus (HIV) infection. We conducted longitudinal studies of B and T cell function in seven homosexual men with HIV infection and PGL. All seven had abnormal antibody-mediated immunity as studied by sequential assessment of in vivo antibody responses after immunization with the T-dependent neoantigens bacteriophage phi X 174 and keyhole limpet hemocyanin (KLH), the T-independent tetradecavalent pneumococcal polysaccharide vaccine, and the recall antigens diphtheria and tetanus toxoid. Compared to HIV-negative heterosexual controls, PGL patients responded with lower antibody titers and, following immunization with phage, failed to develop immunologic memory and to switch from IgM- to IgG-isotype antibody. In vitro antigen-induced antibody production was markedly diminished; and some patients showed depressed mitogen responses. There was a correlation between the degree of compromised immunity and the clinical condition; those with the most severe symptoms showed the most extensive immune deficiency. Yet despite obvious immunologic impairment five of the seven men have remained clinically stable over a 3-year follow-up period.