Comparative Evaluation of Rate Modulated Dual Chamber and VVIR Pacing

JUTZY, R.V., ET AL.: Comparative Evaluation of Rate Modulated Dual Chamber and VVIR Pacing. While dual chamber pacing is considered superior to VVI pacing at rest, there is a continuing debate as to the relative benefit of AV synchrony versus rate increase with exercise. To evaluate this question and to correlate different methods of evaluation, 14 patients with DDDR pacemakers were studied using serial treadmill exercise test with a CAEP protocol. Patients were exercised in DDD, DDDR, and VVIR modes. Echo-Doppler cardiac outputs were determined and pulmonary gas exchange was measured during exercise. There was a significant improvement in cardiac output with exercise in the DDDR versus VVIR modes, and in DDDR versus DDD modes in patients with chronotropic incompetence. There were small increases in exercise duration in DDDR versus VVIR modes, and small but consistent increases in VO, at all levels of exercise, though not statistically significant. In this group of patients, DDDR pacing was superior to VVIR pacing, and superior to DDD pacing when chronotropic incompetence was present.     

Evidence for α2-Adrenoceptor Agonist Activity of Minoxidil*

The present investigation was undertaken to study the mechanism of action of minoxidil using various smooth muscle preparations. Minoxidil (4.7 × 10^?6 m to 4.7 × 10^?4 m ) produced a concentration-dependent inhibition of field stimulation-evoked responses in rat anococcygeus muscle and vas deferens. The inhibition produced by minoxidil was antagonized by yohimbine (2.5 × 10^?7 m ). Minoxidil (1.4 × 10^?5 m to 4.7 × 10^?4 m ) also produced a concentration-dependent relaxation in oestrogen-primed potassium chloride-depolarized rat uterus. These responses were blocked not only by yohimbine but also by glibenclamide (202 × 10^?8 m ). Our results suggest that minoxidil possesses α₂-adrenoceptor agonist activity in addition to potassium-channel-opening activity.     

Giant nerve abscesses in leprosy

Two leprosy patients with neuritis caused by giant abscesses involving almost the entire ulnar nerve are described. One patient, who also had skin lesions, was diagnosed histopathologically as having borderline tuberculoid leprosy both on skin and nerve biopsy, and the other, with only nerve involvement, belonged to the pure neuritic group. The lepromin test was strongly positive (with a vesicular reaction in one patient) and lymphocyte transformation to Mycobacterium leprae antigen was raised. These lesions can be easily mistaken for a peripheral nerve tumour in places where leprosy is uncommon. A brief account of the management of nerve abscess in leprosy is given.     

1H n.m.r. studies of insulin

¹H n.m.r. studies at 270 MHz were made of the transformation of 2 Zn insulin hexamer to 4 Zn hexamer produced by the addition of anions (thiocyanate ion). Four separate H2 histidine resonances were observed for the B5 and B10 histidines in 2 Zn hexamer at pH 7 and 9 and four separate resonances also occurred in the 4 Zn hexamer. The observation of these resonances and others from phenylalanine, tyrosine and leucine residues showed that the 2 Zn to 4 Zn transformation probably occurred in solution in a similar manner to that observed in the crystal. Furthermore as occurred in the crystal, it was found that in solution the transformation was reversible (on removal of thiocyanate) and that 2 Cd insulin was unable to undergo the transformation. Des-Phe-B1-insulin did not undergo the transformation. Addition of SCN? to Zn-free insulin (mainly dimer) produced only a small transformation, consistent with the idea that Zn^{2 +} promotes formation of hexamer from dimer but probably does not otherwise affect the transformation.     

Endoscopic sclerotherapy in children

Thirty-eight children, aged 1-15 years, with portal hypertension and recent variceal bleeding, were treated with repeated endoscopic sclerotherapy. Thirty-six of them had extrahepatic portal venous obstruction. Obliteration of varices was achieved in 35 (92%) patients requiring an average of 5.3 sessions per patient. Major complications occurred in seven patients, three of whom had oesophageal perforations and four had oesophageal stricture. Sclerotherapy significantly reduced the rate of rebleeding after the start of sclerotherapy and more so after variceal obliteration.     

Prevalence of hepatitis C virus antibodies in chronic liver disease and hepatocellular carcinoma patients in India

The prevalence of antibodies to hepatitis C virus (HCV) was investigated in 129 patients with chronic liver disease (85 with chronic active hepatitis and 44 with cirrhosis) and 53 patients with hepatocellular carcinoma. The commercially available second generation anti-HCV enzyme immunoassay kit was used. Antibodies to hepatitis C virus were detected in 16.2% of the patients with chronic liver disease and in 15.1% with hepatocellular carcinoma. Of the HCV positive patients in all groups 51.7% were positive for hepatitis B virus (HBV) markers indicating present or past infection. Prevalence of HBV markers in all the three groups (CAH, cirrhosis and HCC) was higher as compared with anti-HCV prevalence. These results suggest that HCV infection may not be a major cause of chronic liver disease and hepatocellular carcinoma in India and indicate the presence of other aetiological agents.     

Alleviation of Nickel-Induced Biochemical Alterations by Chelating Agents

Alleviation of Nickel-Induced Biochemical Alterations by ChelatingAgents. Misra, M., Athar, M., Hasan, S. K., and Srivastava,R. C. (1988). Fundam. Appl. Toxicol 11, 285–292. The effectof 1,4,8,11-tetraazacyclotetradecane (Cyclam), triethylenetetramine(TETA), reduced glutathione (GSH), ethylenediamine tetraaceticacid (EDTA), cyclohexanediamine tet-raacetic acid (CDTA), diethylenetriamine pentaacetic acid (DTPA), and hydroxyethylenedia-minetriacetic acid (HEDTA) on the alleviation of nickel-inducedbiochemical and trace-metal alterations in serum, liver, andkidney of nickel-treated rats was studied. The lipophilic chelatingagents Cyclam and TETA exhibited a higher order of effectivenessin alleviating nickel-induced alterations compared to EDTA,CDTA, DTPA, and HEDTA, the hydrophilic chelating agents. Thehigher efficacy of lipophilic agents may be due to their abilityto bind to nickel present in extracellular fluid as well asin intracellular fluid, while the hydrophilic agents may bindonly to nickel present in extracellular fluid. Our data alsosuggest that the efficacy of Cyclam to ameliorate nickel-inducedalterations is exceptionally high.     

Geographic variations in structure and composition of gallstones and their correlation with brittleness

Abstract Cholesterol gallstones obtained from different geographic regions have been reported to show significant differences in their minor chemical constituents. We undertook the present study with two objectives: (i) to investigate the possible physicochemical and radiological differences beween cholesterol gallstones obtained from Indian and German patients; and (ii) to compare the brittleness of the two stone groups. Forty Indian and 36 German gallstones (matched in size and shape) were subjected to assessment of physical characteristics, in vitro computed tomography (CT) and chemical analysis. German stones more often had a stone density distribution index of ≥50 Hounsfield units (HU) (26 vs 14; P <0.01), peripheral calcification (18 vs 9; P <0.02), maximum CT density ≥ 90 HU (17 vs 9; P <0.05) and significant calcium carbonate (9 vs 5; P <0.05), compared to Indian stones. The in vitro lithotripsy performed with the Siemens Lithostar Plus machine at a constant energy level showed the German stones to be more brittle (easy to fragment), more often requiring <1000 shocks for fragmentation (25/36; 69%) compared to Indian stones (18/40; 45%, P <0.05). Gallstones from different geographic regions may show significant variations in their physicochemical characteristics that may explain the differences in their brittleness to lithotripsy.