Role of H1- and H2-receptors in airway reactions to histamine in conscious sheep

We investigated the role of histamine H1- and H2-receptors in the control of airway function in six conscious sheep. In five of these, inhalation of histamine (combined H1- and H2-receptor stimulation) caused an increase in pulmonary resistance (RL) and functional residual capacity and had a variable effect on distribution of ventilation as measured by N2-clearance delay. Pretreatment with the H1-antagonist, chlorpheniramine, prevented these functional effects of histamine challenge, whereas pretreatment with the H2-antagonist, metiamide, potentiated the effects of histamine on RL and caused a uniform increase in N2-clearance delay. Pretreatment with both chlorpheniramine and metiamide prevented the effects of histamine on all parameters indicating effective blockade of H1- and H2-receptors at the dosages used. In one sheep, an increase in RL and N2-clearance delay in response to histamine was only observed after metiamide pretreatment. With or without pretreatment, histamine failed to alter the static pressure-volume curve of the lung. We conclude that in conscious sheep a) inhalation of histamine produces bronchoconstriction and pulmonary hyperinflation without changing lung elastic recoil, b) the observed effects of histamine are mediated by H1-receptors, and H2-receptors have a modulating role, and c) variable effects of histamine on RL and distribution of ventilation may be related to differences in the distribution of H1- and H2-receptors in central and peripheral airways.

Peripheral airway function in antigen-induced bronchoconstriction

The density dependence of the maximum expiratory flow-volume curve, functional residual capacity (FRC) and specific airway conductance (SGaw) were studied in 16 asymptomatic subjects with ragweed hypersensitivity and a history of bronchial asthma, before and during bronchial provocation with ragweed extract (dose-response curve), and following inhalation of isoetharine. In ten of these subjects (seven "reactors" and three "non-reactors"), the baseline volume of isoflow (VisoV) was found to be greater than 20% of forced vital capacity. During antigen challenge, VisoV increased in all subjects; ten of these showed a greater than 35% decrease in SGaw (mean 45%) while the remaining six showed a decrease in SGaw of less than 20% (mean 9%), suggesting central and peripheral airway constriction in the former ("reactors") and primarily peripheral airway constriction in the latter ("non-reactors"). The beta-adrenergic agonist isoetharine increased SGaw and decreased VisoV, suggesting dilation of both central and peripheral airways. We conclude that in asymptomatic subjects with asthma and ragweed hypersensitivity a) peripheral airway dysfunction is frequently present, b) during antigen challenge VisoV may be a more sensitive indicator of airway response than SGaw, and c) the beta-adrenergic agonist isoetharine exhibits its bronchodilator effect in both central and peripheral airways following antigen challenge.

Comparison of vector competence for West Nile virus of colonized populations of Culex tritaeniorhynchus from southern Asia and the Far East

Seven colonized stocks of Cx. tritaeniorhynchus from different geographic areas of Southern Asia and the Far East were assayed for susceptibility to WN virus infection by membrane feeding and by intrathoracic inoculation. Infected females also were tested for their ability to transmit virus to baby mice. No geographic pattern of differential susceptibility to WN virus infection was apparent from the experiments; however, the per os ID50 of one strain from Khulna, Bangladesh was over 10-fold greater than the ID50's of stocks from Karachi, Pakistan and Sendai, Japan. No difference in susceptibility was found by parenteral inoculation of virus. Likewise, greater than or equal to 90% of infected females from all the colonies were able to transmit virus.

Determination of pulmonary blood flow by the rebreathing technique in airflow obstruction

To test the hypothesis that the effect of nonuniform gas distribution on the uptake of inhaled soluble gases in the lung is minimized by rebreathing, we measured pulmonary blood flow by the thermodilution technique, and pulmonary capillary blood flow, combined pulmonary tissue and capillary blood volume, diffusing capacity of the lung for CO, and alveolar volume by a rebreathing technique in conscious sheep before and immediately after inhalation of a histamine aerosol (4% solution). We also measured pulmonary resistance, distribution of ventilation by multiple-breath N2 washout, and arterial blood gases to monitor airway responses. Histamine inhalation produced a mean pulmonary resistance increase to 621% of baseline accompanied by uneven distribution of ventilation and a decrease in arterial Po2. Despite these alterations in airway function, there were no concomitant changes in pulmonary capillary blood flow, combined pulmonary tissue and capillary blood volume, diffusing capacity of the lung for CO, alveolar volume, or the ratio of diffusing capacity for CO to alveolar volume. Mean pulmonary capillary blood flow and pulmonary blood flow did not differ from each other before and after histamine inhalation. We conclude that the rebreathing technique for noninvasive measurement of pulmonary hemodynamics is satisfactory in the presence of airflow obstruction.

Effect of local radioactivity on trachael mucous velocity of sheep

The effects of local isotope radiation and x-ray radiation on mucociliary transport of sheep were investigated. X-ray radiation from fluoroscopy equivalent to that used to determine tracheal mucous velocity in intact animals (approximately 3 min) did not alter transport of teflon discs in an isolated sheep trachael preparation. In conscious sheep, 2 ml of a solution containing 8 mCi of macroaggregates of albumin labeled with technetium-99m (99mTc) and 99mTc-pyrophosphate were instilled under direct vision into the trachea via a fiberoptic bronchoscope, providing an actual deposition on the tracheal epithelium of 1.8 to 2 mCi. Physiologic saline and unlabeled macroaggregates of albumin were instilled as control solutions. Tracheal mucous velocity measured by movement of teflon discs increased by 93.2 per cent with 99mTc-labeled macroaggregated albumin and 86.7 per cent with 99mTc-pyrophosphate (P less than 0.01), but no significant increase occurred after saline or unlabeled macroaggregates of albumin. Discrepancies in the values of trachael mucous velocity determined using inert particles and radioactive tracer solution or aerosols might be related in part to the local effects of the tracer radiation.

Clinical experience with the Lillehei-Kaster valve prosthesis

The Lillehei-Kaster valve was used in 215 patients over a 7-year period. The aortic valve was replaced in 81 of them. Hospital mortality was 21% (17 patients). Ten patients were lost to follow-up and long-term mortality was 5% (3 patients). The incidence of thromboembolism was 2.6 per 100 patient-years, and actuarial survival was 96% at 5 and 87% at 7 years. Mitral valve replacement was performed in 108 patients. Hospital mortality was 20% (22 patients), 24 patients were lost to follow-up, and long-term mortality was 13% (11 patients). The combined incidence of thromboembolism was 5.0 per 100 patient-years, and actuarial survival was 81% at 5 years and 75% at 7 years. In both groups, the majority of patients improved clinically. Fifteen patients had double-valve replacement, and 11 had coronary revascularization in addition to valve replacement.

Effect of chlorinated hydrocarbons on reproductive performance of adult White Leghorn male chickens

Two experiments of 20 and 40 weeks duration were conducted to determine the effects of feeding dieldrin or PCB (Aroclor 1254) on the reproductive performance of adult White Leghorn males. Dieldrin at the levels used (0, 25, and 50 ppm) produced no significant changes in semen volume, semen concentration, fertility, and hatchability of fertile eggs. Mortality increased with increased levels of dieldrin and appeared related to duration of exposure to the pesticide. A significant reduction (P less than .05) in feed consumption was observed at the 25 ppm level. No significant differences in body weights were observed except shortly before death when marked reductions in both feed consumption and body weight were noted. PCB at the levels used (0, 10, 20, and 40 ppm) produced no differences in fertiluty, hatchability of fertile eggs, body weights, feed consumption, or mortality. However, over a period of 40 weeks, PCB significantly (P less than .05) reduced semen volume, semen concentrations, and testes weights,

Carpal tunnel syndrome with polymyalgia rheumatica

Association of carpal tunnel syndrome with systemic diseases is well established. Carpal tunnel syndrome preceded or existed simultaneously in 5 patients with polymyalgia rheumatica. It is probably related to tenosynovitis resulting in increase in the volume of the contents of the tunnel.

Clinical evaluation in tinidazole in amoebiasis in children

Forty children with symptomatic intestinal amoebiasis were treated with tinidazole in a single dose of 50 mg/kg for 3 consecutive days. A cure rate of 97% was obtained. Tinidazole was tolerated well in children and proved to be a valuable new amoebicidal drug.

Comparison of pyrantel pamoate with other anthelmintic drugs

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