Airway surface pH in subjects with cystic fibrosis.

The cystic fibrosis (CF) transmembrane conductance regulator protein can transport bicarbonate and may therefore regulate airway surface (AS) pH. Disturbances of AS pH could contribute to the pathophysiology of CF lung disease. Five studies were carried out including the following: study 1) nasal pH measurements were made in 25 CF and 10 non-CF adults using an antimony pH probe. Mean nasal pH was significantly lower in the CF group. Nasal potential difference may have been a confounding factor; study 2) in a fresh cohort of CF and non-CF subjects, no significant difference was found between the two groups using a gold pH probe; study 3) simultaneous nasal pH measurements were made in 15 CF and 15 non-CF adults using both probes. In the CF group, there was a trend for the antimony probe to read lower than the gold probe. In the non-CF group, the antimony probe read higher. The pH difference noted in study 1 related to technical factors; study 4) the effect of acute changes in serum acid/base balance on nasal pH was assessed in five non-CF adults. Nasal pH was not altered by either acute respiratory acidosis or alkalosis; study 5) nasal and lower airway pH was measured in five CF and six non-CF children. No difference was found between the groups. There was a correlation between nasal and lower airway pH. The authors conclude that airway surface pH does not differ between cystic fibrosis and noncystic fibrosis subjects and therefore, cystic fibrosis transmembrane conductance regulator may not play a major role in airway surface pH in vivo.     

Effects of intrathecal and intraperitoneal morphine on gastrointestinal motility in the rat.

A method has been developed to compare gastrointestinal (GI) transit time after intrathecal (i.t.) drug injection in the rat. Each animal had a catheter implanted in the i.t. space. Eight rats, on three separate occasions, had either i.t. morphine 16 micrograms kg-1 (in 50 microliters) or intraperitoneal (i.p.) morphine (0.1%) 7.5 mg kg-1 or i.t. saline (50 microliters). The dose of morphine was the ED50 for analgesia by each route. After halothane and oxygen anaesthesia, 10 steel balls and 1 ml of contrast medium were placed into the stomach, the whole procedure being completed within 5 min. Radiographs were taken at 5 min, 3, 6 and 24 h, and the number of balls in the stomach, small and large intestine were counted. The inhibitory effect of i.t. or i.p. morphine on gut motility caused an equally significant delay at 6 h. In a separate series of eight rats the delay by i.t. morphine could be completely antagonized by i.p. naloxone 1 mg kg-1. Thus, i.t. morphine in an analgesic dose even though smaller than the i.p. dose has a similar inhibitory effect on GI tract motility in the rat. This method would enable comparisons on GI transit to be made between a variety of intrathecally administered drugs.     

Assessment of body composition in the prader-willi syndrome using bioelectrical impedance

The accurate assessment of body composition is of importance in the Prader-Willi syndrome. Many techniques are not applicable due to ethical or practical reasons. However, the bioelectrical impedance technique is a rapid, painless, noninvasive method of estimating total body water and hence, fat-free mass in obese children and adolescents. We have compared estimates of total body water derived from bioelectrical impedance with actual measurements taken, using H₂¹⁸O dilution, in 14 children with Prader-Willi syndrome. Existing equations for predicting total body water from impedance showed a bias to underestimate actual measures of body water. There were positive correlations between the degree of underestimation with age and body fatness. It is possible that changes in body shapes influence bioelectrical impedance measurements in obese individuals, and that a prediction equation based upon a normal population will not be applicable to obese individuals. © 1992 Wiley-Liss, Inc.     

Marked Q-T prolongation due to encainide therapy

Summary Encainide is a type Ic antiarrhythmie agent. During encainide therapy, mild Q-T interval prolongation can be seen, usually associated with prolongation of the Q-R-S interval. The present case report describes an unusual and marked prolongation of the Q-T interval with no Q-R-S interval prolongation in a patient who was treated with encainide for atrioventricular nodal reentrant tachycardia. The drug metabolite profile in this patient's serum indicated an unusual elevation of the 3-methoxy-O-demethyl encainide metabolite, versus O-demethyl encainide. This elevated metabolite level suggests that 3-methoxy-O-demethyl encainide has a significant effect on prolongation of repolarization. An abnormal metabolism of encainide may be the underlying mechanism by which some patients would manifest an unusual prolongation of Q-T interval during encainide therapy.     

Reduced tumorigenicity of rodent tumour cells and tumour explants following infection with wild type and mutant herpes simplex virus, bovine mammillitis virus and encephalomyocarditis virus

The tumorigenicity of neoplastic hamster and mouse cell lines and tumour explants was reduced by infection with herpes simplex virus (HSV-1), a thymidine-kinaseless mutant of herpes simplex virus, namely 'MDK', encephalomyocarditis virus (EMC) and bovine mammillitis virus (BMV). There was an approximate relationship between duration of virus infection in vitro and reduction in incidence and/or rate of tumour development. The rate of tumour development was also reduced by 'site inoculation' of virus (HSV-1) at various time intervals following inoculation of tumorigenic BHK 21 cells indicating that virus was capable of reducing the rate of tumour development in a situation where the neoplastic cells were already transplanted into the susceptible host species. It is suggested that the therapeutic role of wild type, mutant or recombinant viruses merits further exploration towards prevention and treatment of human cancer.     

Criteria for diagnosis of familial amyotrophic lateral sclerosis. European FALS Collaborative Group.

Clinical criteria for the diagnosis of motor neuron disease, agreed at the inaugural meeting of the European Familial Amyotrophic Lateral Sclerosis Collaborative Group, are described. The criteria are derived from those developed for the study of sporadic amyotrophic lateral sclerosis, and allow the inclusion of certain recognized clinical sub-types of familial amyotrophic lateral sclerosis. They will require testing for consistency and sensitivity.