α-Bungarotoxin blocks the nicotinic receptor mediated increase in cell number in a neuroendocrine cell line

Exposure of H69 small cell lung carcinoma cells to nicotinic agonists resulted in a significant increase (up to 100%) in cell number after 6 to 12 days. The effect of nicotine (10⁻⁸ M to 10⁻⁴ M) was both dose and time dependent as was that of another nicotinic agonist cytisine (10⁻⁶ M to 10⁻⁴ M). Interstingly, both the nicotine and cytisine induced increases in H69 cell number were blocked by α-bungarotoxin, as well as d-tubocurarine a nicotinic blocker which appears to interact with most nicotinic receptors. These results suggest that the nicotine induced increase in cell number is mediated through an interaction at the nicotinic α-bungarotoxin receptor. This idea is further supported by experiments which show (1) that H69 cells possess high affinity α-bungarotoxin sites (K_d = 25 nM, B_max = 10.4 fmol/10⁶ cells) with the characteristics of a nicotinic α-bungarotoxin receptor and (2) that the potencies of nicotinic receptor ligands in the α-bungarotoxin binding assay were similar to those observed in the functional studies. Northern analysis showed that mRNA for α7, a putative nicotinic α-bungarotoxin binding subunit, and for α5 were present in H69 cells. The present data provide further evidence that nicotine increases cell number in small cell lung carcinoma and are the first to show that this effect is mediated through an interaction at the nicotinic α-bungarotoxin receptor population. These results suggest that the α-bungarotoxin site may be involved in modulating proliferative responses in neuroendocrine derived SCLC cells.     

Systemic effects of inflammation in bronchiectasis

A group of bronchiectatic subjects in the clinically stable state were studied for systemic evidence of inflammation. The following parameters were evaluated: body weight, serum albumin, serum globulin, serum alpha 1-antitrypsin (alpha 1 AT) and peripheral white cell count. For serum albumin and globulin, comparison was made between subjects with bronchiectasis and control subjects with no known pulmonary disease matched for sex and age, and for serum alpha 1 AT and peripheral white cell count, matched for smoking habit as well. The bronchiectatic subjects showed systemic effects of inflammation as indicated by lower body weight and serum albumin (P less than 0.01), higher serum globulin (P less than 0.001), serum alpha 1 AT (P less than 0.05) and total leucocyte count (P less than 0.05). Differential white cell count showed that the elevation was distributed in most cell types. Correlation matrix was done for the above systemic parameters and indices of airway inflammation including sputum volume, purulence, and polymorph count and FEV1. There was an inverse correlation between total peripheral WBC count and FEV1 in percentage of predicted (P less than 0.01), and a positive correlation between sputum purulence and sputum polymorph score (P less than 0.05). This suggests that host peripheral leucocyte response may be a factor in the determination of lung function.     

Plasma Histamine After Methacholine, Allergen, and Aspirin Challenges

Plasma histamine levels were measured by radio-enzymatic technique in seven patients following 10 challenges: five methacholine challenge tests, four antigen inhalation challenge tests, and one oral aspirin challenge test. Baseline plasma histamine was the same in all patients except in the aspirin-challenged patient, who had a higher baseline histamine level. There was no statistical change in the level of histamine throughout the test in either the methacholine-challenged or the antigen-challenged patients, whereas there was a marked increase in histamine levels in the aspirin challenged patient. A possible explanation is that methacholine and antigen are inhaled and therefore have primarily local effects on the lung, whereas oral aspirin has a systemic effect with consequently systemic changes in histamine which are detectable as changes in plasma level.     

Hepatitis B infection in prostitutes

The prevalence of HBV markers in prostitutes is known to be higher than that of the normal population of similar age range in previous studies. This study showed a significant correlation between the duration of prostitution and the prevalence of HBV antibodies amongst the prostitutes. The prevalence of HBV antibodies doubled after the first year of prostitution. A two-year follow-up study of these prostitutes showed that 37% of HBsAg positive prostitutes lost the HBsAg. The seroconversion rate of HBsAg negative prostitutes was 10% during this two-year period. Early immunization against HBV infection should be considered in this high risk group in view of these findings.     

Electrophysiological properties of neurons in the rostral ventrolateral medulla of normotensive and spontaneously hypertensive rats

Single unit activities were recorded from the rostral ventrolateral medulla (RVL) of pentobarbital-anesthetized normotensive Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Throughout the recording period, arterial blood pressures of WKY (mean arterial pressure, MAP = 103.1 mm Hg) and SHR (MAP = 159.2 mm Hg) remained stable at the respective basal levels. The units recorded in this study were all spontaneously active and cardiac-locked. Two types of discharge patterns, namely single and double discharges, were identified. These single and double discharge units were found to distribute randomly in RVL. In WKY, 92.6% of RVL neurons exhibited single discharges whereas in SHR, the majority (57%) of RVL neurons exhibited double discharges. The mean firing rate of single discharge units in RVL of SHR was significantly higher than that of WKY, whereas the mean firing rate of double discharge units in WKY was similar to that of SHR. About half of the units studied were also tested for antidromic collision; all units tested could be antidromically activated from the intermediolateral column (IML) of the thoracic spinal cord and the lowest threshold sites were consistently localized within IML. In both groups of rats, the axonal conduction velocity of RVL neurons showed a bimodal distribution viz. the fast and slow conducting axons. The mean conduction velocities of each of these two groups of neurons in WKY and SHR were similar. Most of the double discharge units in WKY and SHR belonged to the fast conducting type.(ABSTRACT TRUNCATED AT 250 WORDS)     

Direct detection of Epstein-Barr virus in peripheral blood and comparison of Epstein-Barr virus genotypes present in direct specimens and lymphoblastoid cell lines established from nasopharyngeal carcinoma patients and healthy carriers in Hong Kong.

By means of a PCR assay, EBV was demonstrated directly in peripheral blood of previously infected individuals. The virus was detected in approximately 80% of specimens from EBV-seropositive individuals, but not in cord-blood lymphocytes by this method. When virus present in peripheral blood was compared to that observed directly in NPC biopsies or throat washings, it was distinct from that seen in biopsies in 4/15 cases (27%) and from that seen in throat washes in 1/22 cases (5%). The throat-wash virus differed from the biopsy virus in 3/20 cases (15%). The prototype F virus was found in 7/10 LCLs (70%) established from NPC patients' peripheral blood, but was only detected in 2/9 specimens (22%) directly analyzed by the PCR assay. This finding suggests selective isolation of prototype F EBV in spontaneous LCLs established from NPC patients.     

Hyperinsulinaemia and Na+, K+ -ATPase activity in thyrotoxic periodic paralysis

OBJECTIVE Thyrotoxic periodic paralysis (TPP) usually follows a heavy carbohydrate meal and this may be explained by hyperinsulinaemia stimulating Na⁺, K⁺ -ATPase activity. To clarify this the effect of glucose load on serum insulin concentration and platelet Na⁺, K⁺ -ATPase activity In thyrotoxic periodic paralysis (TPP) was examined. DESIGN In all subjects a standard 75-g glucose tolerance test was done and blood samples were taken at 0, 1 and 2 hours. SUBJECTS Twenty-five healthy controls (8 M and 17 F), 17 uncomplicated thyrotoxic patients (7M and 10 F), 15 TPP patients who presented with paralysis and 4 TPP patients after treatment with antithyrold drugs. MEASUREMENTS Plasma glucose was measured by the glucose oxidase method, serum insulin by radioimmunoassay and platelet Na⁺, K⁺ -ATPase by the release of phosphate from ATP. RESULTS TPP patients showed glucose intolerance (area under the curve (AUC) 16·5 ± 4·4 (mean ± SD) In TPP compared to 12·9 ± 4·5 In controls (P < 0·01) and hyperinsulinaemia (AUC 189·6 ±100·6 vs 98·5 ±53·4, P < 0·001). In uncomplicated thyrotoxicosis the results were similar to that in healthy controls. Platelet Na⁺, K⁺ -ATPase were significantly higher in thyrotoxic patients compared to controls and In TPP patients were even higher. Ingestion of glucose increased platelet Na⁺, K⁺ -ATPase in all groups. AUC for platelet Na⁺, K⁺ -ATPase in TPP patients were significantly higher than in uncomplicated thyrotoxicosis (601 ±99·3 vs 482 ± 109·4, P < 0·01) or healthy controls (320 ± 107·3). In the 4 TPP patients studied after antithyroid treatment the results were similar to healthy controls. CONCLUSION Patients with thyrotoxic periodic paralysis have hyperinsulinaemia and this is accompanied by higher Na⁺, K⁺-ATPase activity.     

Intracapsular tonsillar reduction (partial tonsillectomy): reviving a historical procedure for obstructive sleep disordered breathing in children.

OBJECTIVE: We sought to reintroduce a historical procedure-intracapsular tonsillar reduction (partial tonsillectomy or tonsillotomy)-for tonsillar hypertrophy causing obstructive sleep disordered breathing (OSDB) in children, as well as to determine whether partial tonsillectomy, compared with conventional (total) tonsillectomy when performed by more than one surgeon, is equally effective for the relief of OSDB while resulting in less pain and more rapid recovery. STUDY DESIGN: We conducted a retrospective case series at a tertiary children's hospital. The charts of children who underwent partial tonsillectomy and total tonsillectomy (1998 through 2002) for postoperative complications were reviewed. The caregivers were surveyed to assess postoperative pain, rapidity of recovery, and effectiveness of surgery for relieving symptoms of OSDB. RESULTS: Two hundred forty-three children underwent partial tonsillectomy and 107 children underwent total tonsillectomy. There were no significant differences in immediate and delayed complications between the groups. Both operations were equally effective in relieving OSDB. Children who had partial tonsillectomy had significantly less postoperative pain and significantly more rapid recovery. CONCLUSION: Intracapsular tonsillar reduction with an endoscopic microdebrider relieves OSDB as effectively as conventional tonsillectomy, but results in less postoperative pain and a more rapid recovery.