Effects of methacholine and uridine 5'-triphosphate on tracheal mucus rheology in mice

We compared the action of methacholine (MCh) and uridine 5'-triphosphate (UTP) with and without pretreatment with the chloride channel blocker 4,4'-diisothiocyano-2,2'-stilbenedisulfonate (DIDS) on the transepithelial potential difference (PD), the mucus collection rate (MCR), and tracheal mucus rheology using anesthetized C57BL/6 mice. The cystic fibrosis transmembrane conductance regulator (CFTR) blocker 5-nitro-2-(3-phenylpropylamino)benzoate (NPPB) was also used as a pretreatment for MCh. After collecting baseline mucus for 1.5 h, mucus secretion was stimulated by instilling 5 microl of 10(-2) M MCh or UTP around the upper trachea. There was a significant increase in PD after MCh or UTP stimulation (-21.3+/-2.0 mV MCh versus -14.1+/-1.6 mV control; -25.4+/-2.5 mV UTP versus -19.2+/-1.9 mV control). When UTP administration was preceded by DIDS, PD shifted from -15.2+/-2.9 to -12.0+/-2.2 mV. When MCh was preceded by DIDS or by NPPB, there was no change in PD. There was a significant decrease in mucus rigidity index, logG*, with MCh (2.54+/-0.09 versus 2.99+/-0.14 for control), similar to that previously reported in other species. With UTP, 14 of 16 mice responded in terms of PD becoming more negative, and of these, there was a significant difference in logG* after UTP administration (2.29 +/-0.10 versus 2.57+/-0.10 for control), whereas there was no change in logG* with DIDS administration before UTP. When DIDS administration preceded MCh, there was a diminished but still significant decrease in logG* from control, whereas there was no change in logG* when NPPB was preadministered. The control mucus collection rate was 0.19+/-0.09 mg/h, whereas after MCh stimulation, it increased to 2.83+/-0.78 mg/h. No significant difference was measured in the MCR after either UTP or DIDS+UTP stimulation. DIDS+MCh and NPPB+MCh both resulted in significant increases in MCR, but of a much smaller magnitude than that for MCh alone. We conclude that hypersecretion owing to UTP in C57BL/6 mice is less vigorous than with MCh, reflecting the limited population of Ca(2+)-dependent Cl(-) channels stimulated by UTP P(2) receptors. The action of MCh on tracheal mucus secretion in mice appears to involve both CFTR- and non-CFTR-dependent chloride channels.     

Knowledge of HIV infection and AIDS, and attitudes to testing and counselling among general practitioners in Northern Ireland.

All 922 general practitioners in Northern Ireland were sent a questionnaire on human immunodeficiency virus (HIV) infection and the acquired immune deficiency syndrome (AIDS). Five hundred and ninety four general practitioners (64.4%) returned the questionnaire. Thirty eight respondents (6.4%) knew of an HIV positive patient in their practice and 93.3% felt they should be informed if one of their patients was found to be HIV positive at a genitourinary medicine clinic, even without the patient's consent. Of the respondents, 76.8% were willing to be involved in the management of AIDS patients in their practice in cooperation with hospital colleagues but only 37.5% felt confident to provide AIDS counselling and advice. Of the 368 general practitioners who did not feel confident to provide AIDS counselling and advice, 41.3% felt that they had insufficient knowledge and 79.6% felt uncertain of their counselling skills. The information gathered on the administration of injections, taking blood samples and disposal of needles indicated that further education for general practitioners is required to ensure safety at work.     

Individual and cultural-diversity competency: focus on the therapist

The Competencies Conference: Future Directions in Education and Credentialing in Professional Psychology was held in Arizona in November 2002. One of the workshops, Individual and Cultural Differences (ICD), focused on racism, homophobia, and ageism. The consensus was that self-awareness and knowledge about the three "isms" are critical components in the education and training of psychologists. This article, authored by four of the workshop attendees, is a review of the current research and theoretical literature. Implications that address both content and context in graduate programs and training sites are presented. This is one of a series of articles published in this issue of the Journal of Clinical Psychology. Several other articles that resulted from the Competencies Conference will appear in Professional Psychology: Research and Practice and The Counseling Psychologist.     

Control of dynamic and static nuclear bag fibres and nuclear chain fibres by gamma and beta axons in isolated cat muscle spindels.

1. The behaviour of nuclear bag and nuclear chain intrafusal fibres in isolated cat muscle spindles with a blood supply, during stimulation of dynamic gamma axons, dynamic beta axons, or static gamma axons in ventral root filaments was observed and recorded on still and moving film. 2. Most spindles were controlled by one dynamic gamma axon (sometimes a beta axon) and three static gamma axons, one of which was often non-selective in distribution. A large majority of fusimotor axons controlled one pole of the spindle only. 3. Dynamic gamma and beta axons produced focal contraction in only one of the two nuclear bag fibres in any spindle and this fibre was never activated by static gamma axons. Maximal tetanic contraction was attained slowly and the primary sensory spiral on this fibre was stretched by a small amount only. This fibre has been named the 'dynamic nuclear bag fibre'. 4. Static gamma axons produced either: (a) focal contraction in the second of the two nuclear bag fibres only; (b) local contraction in the bundle of nuclear chain fibres only; or (c) contraction in one nuclear bag fibre and the nuclear chain fibres together. Maximum tetanic contraction of this nuclear bag fibre stretched its primary sensory spiral considerably and the time to plateau was relatively short. This fibre has been named the 'static nuclear bag fibre'. 5. 'Driving' of the Ia afferent discharge could always be produced by non-selective static gamma axons, frequently by static gamma axons controlling nuclear chain fibres alone, and was probably due to mechanical oscillation in nuclear chain fibres. It was never produced by dynamic gamma axons and on one occasion only by a static gamma axon controlling a nuclear bag fibre alone. 6. The conduction velocities of dynamic gamma and static gamma axons overlapped extensively, though dynamic gamma axons were absent from the lower end, and static gamma axons innervating nuclear chain fibres only were absent from the upper end, of the range of velocities. 7. The observations are correlated with spindle structure and histochemistry. Dynamic and static nuclear bag fibres are shown to correspond with 'bag1 fibres' and 'bag2 fibres', respectively (Ovalle & Smith, 1972). 8. The possible origin of the dynamic and static actions of fusimotor axons and the role of the dynamic and static intrafusal systems in motor control are discussed.     

Antibody response to dengue-2 vaccine measured by two different radioimmunoassay methods

Two different radioimmunoassays were used to detect virus-specific antibodies in sera from human volunteers inoculated with an attenuated dengue type 2 (DEN-2) vaccine (PR-159/S-1). An indirect radioimmunoassay required purified DEN-2 virions for optimal reactivity but was 10 to 500 times more sensitive than neutralization or hemagglutination inhibition tests. An antibody capture radioimmunoassay was able to utilize crude antigens from either DEN-infected mouse brains or Aedes albopictus cell culture supernatants. When the two radioimmunoassay techniques were compared, the indirect method appeared to be the best assay for immunoglobulin G (IgG), whereas the antibody capture method was more sensitive for IgM detection. Selected human sera were examined for IgG, IgM, and IgA responses by using both techniques at various intervals after immunization. Although there were differences in magnitude, yellow fever immune as well as flavivirus nonimmune volunteers responded to DEN-2 vaccination by demonstrating IgG, IgM, and IgA antibody responses. In the nonimmune group, the most prevalent immunoglobulin detected was IgM, whereas in the yellow fever immune group, the predominant post-DEN-2 vaccine immunoglobulin was IgG. The preponderance of DEN-2-specific neutralizing antibodies were associated with either IgM or IgG according to the immune status of the volunteer. All classes of immunoglobulins attained maximum levels between 21 and 60 days postvaccination. In the majority of volunteers, IgM responses were relatively transient and could not be detected 6 months after immunization, whereas IgG and IgA antibodies were still detectable after this period.     

Skin testing and extrinsic allergic alveolitis

Skin testing with six common allergens, tuberculin and a sterile avian antigen preparation from pigeon serum was performed on 102 pigeon fanciers. The incidence of positive prick tests to common allergens was no different for subjects with extrinsic allergic alveolitis. EAA, caused by avian exposure than the whole group. Positive immediate weal and flare reactions following skin prick testing with avian antigen occurred in 22 subjects and was closely correlated with atopy. However, when the same antigen was administered intradermally, 69 subjects developed an immediate (15 min) weal and flare reaction which did not correlate with atopy, instead, the weal diameter correlated significantly with the serum IgG antibody titre against pigeon serum gamma-globulin antigen, and furthermore, the higher grades of reaction were highly selective for subjects with EAA. Ten subjects, all with strong early intradermal skin reactions, developed a late (4-6 h) skin reaction; this was again highly selective for EAA. The subjects with cutaneous anergy to tuberculin had markedly higher IgG antibody titres to avian antigens, and these included the majority of the subjects with alveolitis.     

Reciprocal translocation, 4q-; 21p+, giving rise to Down''s syndrome.

A reciprocal translocation is described, t(4;21)(q27;p11), which occurs in a balanced carrier mother and her Down's syndrome child, 47,XX,t(4q-;21p+),+21. A review is presented of Down's syndrome associated with reciprocal translations involving chromosome No. 21.     

Fetal hydrops.

Seventy-two fetuses or neonates with non-immune hydrops were examined between 1983 and 1988. The commonest association was chromosome abnormality; 11 fetuses had a 45,X karyotype and 11 autosomal trisomy. Chromosome abnormality was suspected in a further 20 on necropsy findings but chromosome culture was not possible or unsuccessful. In 11 cases there was histological evidence of infection; seven babies had major structural anomalies and six affected fetuses were twins. In six (8%) the cause of hydrops was not determined compared with eight (16%) of cases examined between 1976 and 1982. Hydrops was diagnosed more frequently while the fetus was alive, before 20 weeks' gestation, and associated with chromosome anomaly than found previously.     

Identification and properties of pathways for K+ transport in guinea-pig and rat alveolar epithelial type II cells.

86Rb+ was used to study potassium uptake and efflux in type II pneumocytes freshly isolated from adult guinea-pig and rat lung. Both species exhibited a substantial ouabain-sensitive component of potassium influx. In rats, most of the ouabain-resistant influx was abolished by bumetanide and removal of extracellular chloride elicited no further effect. In contrast, only a proportion of the ouabain-insensitive uptake was inhibitable by bumetanide in guinea-pigs and this species showed an additional component of influx, which was chloride dependent and which was reduced by either the K(+)-H(+)-ATPase inhibitor, omeprazole, or by the stilbene derivative, 4,4'-diisothiocyanostilbene-2,2'-disulphonate (DIDS). The chloride-dependent component was also apparent in efflux experiments in guinea-pigs, but was absent in rats. Ouabain-insensitive ATPase activity was assayed in highly purified apical membranes from guinea-pig type II pneumocytes. This activity was inhibitable by omeprazole (apparent inhibition constant, Ki, was approximately 40 microM), was potassium dependent (apparent activation constant, Ka, was approximately 200 microM) and was doubled by the addition of nigericin. While potassium transport in rat type II cells is adequately accounted for by Na(+)-K(+)-ATPase and Na(+)-K(+)-2Cl- cotransport, our data suggest the additional presence of K(+)-Cl- cotransport and K(+)-H(+)-ATPase in guinea-pig type II pneumocytes. A model of how alveolar subphase acidification may occur is proposed.     

Glomerular basement membrane expansion in passive Heymann nephritis. Absence of increased synthesis of type IV collagen, laminin, or fibronectin.

The distribution and synthetic rate of glomerular basement membrane components was examined in the Passive Heymann Nephritis model of experimental membranous nephropathy. The extensive tissue injury that developed included subepithelial electron-dense deposits, podocyte foot process effacement, and expansion of the glomerular basement membrane. Levels of mRNA for type IV collagen, laminin, and fibronectin from isolated glomeruli was quantitated by slot-blot analysis and showed no change in experimental animals as compared to controls at either 1 week, 3 weeks, or 3 months after disease induction. Immunoelectron microscopy with gold-labeled anti-laminin IgG revealed no difference in the number of particles bound to the glomerular basement membrane of experimental animals and controls. Immunofluorescence with both type IV collagen antisera and anti-laminin antibody showed no difference in the intensity or pattern of staining. Despite extensive glomerular damage and glomerular basement membrane thickening, no evidence was found for either an increase in the synthetic rate of type IV collagen, laminin, or fibronectin or for an accumulation of basement membrane laminin within the damaged glomeruli. Alternate processes, such as diminished density of matrix components or accumulation of other unmeasured matrix constituents, presumably account for the expansion of the glomerular basement membrane seen in experimental membranous nephropathy.