Assuntos

Assuntos

RESUMO

Episodes of acute otitis media are commonly associated with viral upper respiratory tract infections. Rhinoviruses account for approximately 40% of these infections, and were previously shown to alter eustachian tube function and middle ear pressures. However, progression to otitis media has not been prospectively documented. In the present study, changes in tympanometric pressures and otoscopic findings resulting from experimental intranasal rhinovirus type-39 inoculation were documented in 60 adult volunteers. Fifty-seven (95%) subjects became infected and 34 (60%) of these had a clinical cold. Prior to viral inoculation, 3 (5%) subjects had middle ear pressures of less than -100 mm H2O and two of these subjects developed middle ear effusions following infection. In all, 22 (39%) subjects developed middle ear pressures of less than -100 mm H2O. No subject with normal middle ear pressures prior to infection developed evidence of effusion. This study extends the otologic manifestations of rhinovirus infection to include otitis media. Furthermore, these results support the hypothesized relationship between upper respiratory tract infections, eustachian tube dysfunction, and otitis media.

Assuntos

RESUMO

To determine whether a viral upper respiratory tract infection can alter the responsiveness of the nasal mucosa, paired intranasal histamine and cold air challenge sessions were performed before and after (8 to 13 days) experimental rhinovirus infection in 18 nonallergic subjects and 20 subjects with seasonal allergic rhinitis. The nasal response to the challenges was measured as symptom scores for rhinorrhea and congestion, counts for sneezing, weight for expelled secretions, and inspiratory conductance for nasal patency. For both sessions, a greater response was observed in allergic subjects for sneezing, symptoms of rhinorrhea and congestion, secretion weights provoked by histamine challenge, and secretion weights provoked by cold air challenge when compared with the nonallergic subjects. A comparison of the responses to the paired challenge sessions showed greater responses for sneezing, secretion weight and rhinorrhea to histamine and for secretion weight to cold air challenges performed after rhinovirus infection. No differences were observed between allergic and nonallergic subjects with respect to the degree of enhanced responsiveness secondary to viral infection. These results document an increased responsiveness of the nose to these stimuli during the postsymptomatic period of a rhinovirus infection in both allergic and nonallergic subjects.

Assuntos

RESUMO

Patients with allergic rhinitis (AR), compared with nonallergic persons, have been reported to respond differently to a variety of stimuli, some of which are immunologic in nature. This study compared the systemic cellular immune responses to experimental rhinovirus (RV) 39 challenge in RV-39-seronegative AR (n = 20) and nonallergic (n = 18) subjects. Peripheral blood was obtained before, 4 or 7 days after, and 23 days after RV-39 intranasal challenge and assayed for the number and function of various white blood cells. All subjects were infected, as manifested by viral shedding in nasal secretions or seroconversion. RV-39 induced marked changes from baseline values in both immune cell number and functions. Compared with nonallergic subjects, AR subjects manifested different responses for the following parameters: (1) numbers of total white blood cells and lymphocytes (smaller increases on day 4), (2) helper/suppressor T cell ratio (absence of an increase on day 7 and presence of an increase on day 23), (3) number of IL-2 receptor-positive suppressor T cells (presence of a decrease on day 7), (4) natural killer (NK) cell numbers (absence of an increase on day 4 and presence of increases on days 7 and 23), (5) NK/T cell ratio (absence of an increase on day 4 and a decrease on day 7), (6) NK cell activity (a blunted decrease on day 7 and absence of a decrease on day 23), and (7) RV-39-induced lymphocyte proliferation (exaggerated increase on day 4). The results show that intranasal challenge with RV-39 induced RV-39-specific and nonspecific systemic cellular immune responses and a unique immunologic response pattern in AR subjects.

Assuntos

RESUMO

To determine if individuals with allergic rhinitis are hyperresponsive to upper respiratory tract viral infections, 20 allergic and 18 nonallergic, susceptible, adult volunteers were challenged and infected with rhinovirus type 39 before the pollen seasons. Before challenge and on each of 6 days of cloister, all volunteers were interviewed for symptoms and completed a test battery consisting of evaluations of secretion production by weighed tissues, nasal patency by active posterior rhinomanometry, nasal clearance by the dyed saccharin technique, pulmonary function by spirometry, eustachian tube function by sonotubometry, and middle ear status by tympanometry. The symptomatology and pathophysiology resulting from the rhinovirus infection were consistent with those reported in previous studies with this challenge system. Between-group comparisons revealed no differences in symptom presentation, nasal secretion production, or overall pathophysiologic response. However, for decreased mucociliary clearance rate, increased nasal congestion, eustachian tube dysfunction, and symptoms of sneezing, the allergic group demonstrated an earlier onset compared with that of the nonallergic group. The biologic significance of the differences in onset of dysfunction is tempered by the observation that the temporal pattern of responses in the allergic group was similar with that of nonallergic subjects in previous studies. The results of the present study do not support the hypothesis of a physiologic hyperresponsiveness to rhinovirus type 39 infection in allergic subjects during nonallergy seasons.

Assuntos

RESUMO

Previous investigations have documented a reduced activity of the sodium-potassium-stimulated adenosine triphosphatase enzyme (Na+,K+ ATPase) in platelet membranes of allergic subjects. The purpose of this study was to determine if the reduced Na+,K+ ATPase activity was due to an enzyme inhibitor. Na+,K+ ATPase activity of a particulate fraction of sonicated platelets was determined by spectrophotometry in asymptomatic adults with and without allergy. The Na+,K+ ATPase level (mean, nanomoles per microgram of protein per minute; +/- STD) of allergic subjects (0.9 +/- 1.3) was lower (p less than 0.001) than that of nonallergic subjects (3.9 +/- 1.6). In contrast, when the same platelet fractions were frozen before assay, Na+,K+ ATPase was higher (p less than 0.005) in allergic subjects (6.0 +/- 1.4) than in nonallergic subjects (3.6 +/- 2.0). An inhibitor of canine kidney Na+,K+ ATPase was detected in the buffer in which these platelet fractions were frozen, allergic subjects (0.5% +/- 0.4% inhibition per microgram of protein) compared to nonallergic subjects (0.04% +/- 0.08%; p less than 0.005). The level of inhibition correlated positively with the postfreezing increase in platelet membrane Na+,K+ ATPase, suggesting a freezing-induced displacement of an inhibitor from the membrane. Plasma from these same subjects inhibited Na+,K+ ATPase activity of normal platelets, allergic subjects (70% +/- 31% inhibition) compared to nonallergic subjects (13% +/- 16%; p less than 0.001). These data suggest that the transport-enzyme defect observed in platelets from allergic subjects was due to a circulating Na+,K+ ATPase inhibitor. In vivo Na+,K+ ATPase inhibition in allergy could have profound effects on intracellular cation concentrations and broad implications for pathogenesis.

Assuntos

RESUMO

A pathogenic role and abnormal function have both been ascribed to the blood platelet in allergy, but the explanation for these observations is unknown. This study compared the cation-stimulated adenosine triphosphatase enzyme (ATPase) activities of platelets from allergic (n = 18), potentially allergic (asymptomatic, positive skin test, n = 5) and normal patients (n = 10), all of whom were without symptoms at the time of the study. Platelets were separated by centrifugation, were sonicated, and were assayed for cation-dependent ATPase activity by spectrophotometry. The mean Na+,K(+)-ATPase activity (in nanomoles per microgram protein per minute) of allergic subjects (0.94 +/- 1.28) was significantly lower than that of normal subjects (3.93 +/- 1.58). No Na+,K(+)-ATPase activity was detectable in platelets from eight of the allergic subjects. The Na+,K(+)-ATPase activity of potentially allergic subjects was intermediate between those of the allergic and normal subjects. A significant negative correlation (p less than 0.01) was observed between serum IgE levels and platelet Na+,K(+)-ATPase values, thus suggesting a relationship between the reduced platelet Na+,K(+)-ATPase and IgE immunoglobulin. No such differences were observed for the Ca+(+)- and Mg+(+)-stimulated ATPases. In vivo dysfunction of the plasma membrane Na+,K(+)-ATPase enzyme in allergic subjects could have profound effects on levels of intracellular cations and thus platelet activation and function.

Assuntos

Assuntos