Sputum tumour necrosis factor-alpha and leukotriene concentrations in cystic fibrosis

It is postulated that a vigorous host inflammatory response in the cystic fibrosis lung contributes to lung injury. Tumour necrosis factor-alpha (TNF-alpha) may play a part in that process and in the generation of leukotrienes. Therefore, the relationships between sputum TNF-alpha, leukotriene concentration, and lung function abnormalities in 16 children with cystic fibrosis were investigated. Each subject provided sputum samples and performed spirometry. TNF-alpha was measured by enzyme linked immunosorbent assay; individual leukotrienes were separated using high performance liquid chromatography and quantified by radioimmunoassay. The geometric mean concentration of TNF-alpha was 129.7 pg/ml and 95% confidence interval 48.2 to 348.3. Mean (SEM) leukotriene B4 (LTB4) was 97.8 (22.9) pmol/g and total cysteinyl leukotrienes were 60.9 (14.8) pmol/g. Mean (SD) forced expiratory volume in one second (FEV1) of the group was 53 (15)% of predicted and forced vital capacity (FVC) was 65 (14)% of predicted. There was a significant positive correlation between TNF-alpha and both LTB4 and the total cysteinyl leukotriene sputum content. An inverse relationship existed between TNF-alpha and FEV1 and FVC. Moreover, a negative correlation was observed between sputum LTB4 and FEV1 and FVC. These results suggest that TNF-alpha and the leukotrienes may participate in the airways inflammation and airflow obstruction observed in cystic fibrosis subjects and support the hypothesis that TNF-alpha upregulates the 5-lipoxygenase pathway in vivo.     

Interleukin-1 alpha, soluble interleukin-2 receptor, and IgG concentrations in cystic fibrosis treated with prednisolone

The cytokines interleukin-1 and interleukin-2 participate in the inflammatory response, and may contribute to hypergammaglobulinaemia G and the development of lung injury in cystic fibrosis. Anti-inflammatory treatment with corticosteroids may attenuate this response. The effect of a 12 week course of oral prednisolone on spirometry and serum concentrations of interleukin-1 alpha (IL-1 alpha), soluble interleukin-2 receptor (sIL-2R), and IgG was investigated in 24 children with cystic fibrosis. Prednisolone was administered, in a double blind and placebo controlled manner, at an initial dose of 2 mg/kg daily for 14 days and tapered to 1 mg/kg on alternate days for 10 weeks. The treated group (n = 12) experienced an increase in forced expiratory volume in one second and forced vital capacity at 14 days, however, these changes were smaller at 12 weeks. In the treated group, change in pulmonary function was associated with decreased serum IgG and cytokine concentrations. Prednisolone suppresses serum concentrations of these cytokines, which may participate in the inflammatory response, the excessive synthesis of IgG, and airflow obstruction observed in cystic fibrosis patients.     

Loudness discrimination of speech signals spectrally shaped by a simulated hearing aid.

A discrimination task was used to assess changes in the loudness of speech that accompanied changes in the spectral tilt of a simulated hearing aid's frequency response. Band-limited (0.25-4 kHz) spondaic words were spectrally shaped at comparison tilt-factor values of -6, 0, and +6 dB per octave and delivered monaurally via insert earphone to each of 10 listeners with normal hearing (NH) and 15 listeners with mild-to-moderate sensorineural hearing impairment (HI). Results for the NH listeners indicated that loudness differences among the tilt factors were generally perceptible and that loudness judgments were highly transitive across different tilt-factor comparisons. Loudness differences were also perceptible to many of the HI listeners when they switched among tilt factors. The HI listeners' data showed some evidence of transitivity, but not so much as was shown by the NH listeners. Intersubject variability in the loudness judgments was found to be comparable for the two subject groups. Results of the study are discussed with regard to their implications for hearing aid fitting, with particular emphasis on the "parameter adjustment and selection" fitting procedure (J. Punch & R. Robb, 1992).     

Repair of retinitis-related retinal detachments with silicone oil in patients with acquired immunodeficiency syndrome.

To provide prompt visual rehabilitation and to reduce the need for repeated operations, we performed vitrectomy with silicone oil tamponade in 16 consecutive eyes with retinal detachments related to cytomegalovirus retinitis and acute retinal necrosis in 13 patients with acquired immunodeficiency syndrome. In all 16 eyes (100%), retinas were reattached with one operation. Preservation of ambulatory vision was achieved in six of eight eyes (75%; mean follow-up, 14.6 weeks). No patient with hand motion visual acuity or worse preoperatively recovered ambulatory vision. Visual acuity recovery was limited by optic nerve disease in five eyes (31%). Silicone oil-related side effects did not adversely affect visual outcome in any eye. Six patients (46%) have since died (mean, 4.4 months postoperatively). These data indicated that successful surgical repair of these detachments can be consistently achieved with this approach. The prognosis for ambulatory vision is strongly related to preoperative visual acuity.     

Peripheral α2-adrenoceptor-mediated sympathoinhibitory effects of mivazerol

Summary— Mivazerol is a new compound that could potentially reduce perioperative cardiovascular morbidity and mortality in patients with or at risk of coronary disease and submitted to surgery. This action of mivazerol depends on a well documented centrally mediated reduction in sympathetic nerve activity, but a direct peripheral decrease in sympathetic neurotransmitter release induced by activation of prejunctional α₂-adrenoceptors located on sympathetic nerve endings could also contribute. To investigate this issue, the effects of mivazerol on the pressor, systemic and regional hemodynamic (pulsed Doppler technique) as well as on the cardiac responses to electrical stimulation of the spinal cord (SCS) were measured in pithed rats in the absence and in the presence of mivazerol. Mivazerol exerted strong sympathoinhibitory effects: SCS-induced increases in blood pressure, total peripheral resistance and heart rate were dose-dependently reduced by mivazerol, but among the regional vascular beds investigated, only the hindlimb vasoconstrictor responses were significantly drug-affected. All these sympathoinhibitory effects of mivazerol were abolished by prior yohimbine administration. Simultaneously, mivazerol did not induce any postjunctional adrenoceptor blockade as it did not affect noradrenaline cardiac and hemodynamic effects. On the contrary, through postjunctional α₂-adrenoceptor stimulation, mivazerol, in this pithed preparation, dose-dependently increased blood pressure, total peripheral and hindlimb vascular resistances, but heart rate was not affected. We conclude that, in the pithed rat, mivazerol exerts strong peripheral sympathoinhibitory effects. The mechanism involved is prejunctional α₂-adrenoceptor activation as i) mivazerol does not display any postsynaptic α-adrenoceptor blocking effect — it even behaves as a postsynaptic α₂-adrenoceptor agonist — and ii) yohimbine abolishes mivazerol's sympathoinhibitory effects. Thus, direct peripheral together with central mechanisms contribute to mivazerol's sympathoinhibitory effects and ultimately to its cardioprotective action.     

Presynaptic monoaminergic vesicles in Parkinson's disease and normal aging

We present development and human application of a method for determining the regional cerebral density of the type 2 vesicular monoamine transporter (VMAT2) using positron emission tomography (PET) and [¹¹C]dihydrotetrabenazine (DTBZ). Previous animal studies indicate striatal VMAT2 density is linearly related to the integrity of substantia nigra dopamine neurons and is not subject to drug-or lesion-compensatory regulation. In the present studies, kinetic compartmental modeling was employed to estimate blood-brain [¹¹C]DTBZ transport (K₁,) and VMAT2 binding site density (tissue-to-plasma DTBZ distribution volume, DV)from the cerebral and plasma DTBZ time courses her intravenous tracer injection. In controls, we found reductions of putamen DTBZ DV with advancing age, corresponding to losses of 0.77% per year in specific VMAT2 binding. Parkinson's disease (PD) patients had reduction in specific DTBZ DV in the putamen (?61%) and in the caudate nucleus (?43%). There was no overlap of lowest specific putamen DTBZ DV between individual elderly controls and PD patients. The present results indicate the suitability of [¹¹C]DTBZ PET for objective quantification of nigrostriatal integrity, including evaluation of PD progression and its possible therapeutic modification.     

Immature thymocytes isolated using a sialic acidspecific lectin are unresponsive to concanavalin A

Mouse thymocytes, which are approximately 90% immature cortical cells, are low in surface sialic acid when compared with more mature cortisone-resistant, presumably medullary, thymocytes and peripheral T lymphocytes. Thus, medullary thymocytes bind and are agglutinated by the N-acetylneuraminic acid-specific lectin, lobster agglutinin 1 (LAg1), whereas cortical thymocytes are not agglutinated by this lectin. It is demonstrated herein that mouse cortical thymocytes, purified using LAg1, do not respond to the mitogenic effects of concanavalin A (Con A). The lack of response to this lectin is not due to depletion of macrophages, since addition of macrophages does not restore the response. Populations of LAg1-negative thymocytes can be made to respond weakly to Con A by the addition of interleukin 2, but this response appears to be due to the presence of a few contaminating LAg1-binding thymocytes since it is abolished by treatment of the cells with rabbit anti-LAg1 serum plus complement. Therefore highly purified cortical thymocytes not only cannot respond to Con A, but also they cannot be induced to respond by the addition of the T cell growth factor, interleukin 2. Thymocytes isolated by a single criterion, that is by virtue of their low amount of surface sialic acid, appear to be a truly immature population of thymocytes.