Growth response of Listeria monocytogenes NCTC 7973 in two different media at four incubation temperatures

Listeria monocytogenes NCTC 7973 was cultivated in tryptose phosphate broth (TPB) and tryptone soya broth (TSB) at four different temperatures: 4 degrees, 20 degrees, 30 degrees and 37 degrees C. Cells grown in TSB at 20 degrees C displayed maximum absorbance over cells grown in TPB at the same temperature. Moreover, this observation was further confirmed by dry mass determination and viable count. We determined that cells grown in TSB at 20 degrees C exhibited significant enhanced growth as compared to cells grown in TPB at the same temperature, hence TSB was found to be the medium of choice for maximum biomass production.

Amino acid requirement of six strains of Listeria monocytogenes

Different serovars of Listeria monocytogenes grew well in a chemically defined medium. Sixteen amino acids were tested for the growth of L. monocytogenes. Most strains required cystine, valine, isoleucine, and leucine. Phenylalanine was a stimulatory growth factor for all six strains of Listeria. Whilst tryptophan was essentially required by NCTC 7973, LM and C-286 and stimulatory for 4155 and C-294, none of the strains did exhibit requirements of asparagine, glutamine, proline, histidine and tyrosine as essential/stimulatory growth factor.

Beta-blocker therapy in patients with ventricular tachyarrhythmias in the setting of left ventricular dysfunction

Although several studies suggest beta blockers (BB) are effective in suppressing ventricular arrhythmias, less is known about their role in the treatment of patients with ventricular tachyarrhythmias associated with impaired left ventricular function. To assess the tolerance and efficacy of these agents, 32 patients presenting with either ventricular fibrillation (18) or sustained ventricular tachycardia (14) were studied during BB therapy. Left ventricular dysfunction (mean ejection fraction 29%) was present as a consequence of coronary artery disease (26) or cardiomyopathy (6). Baseline arrhythmia assessment revealed recurrent ventricular tachycardia in all patients. Antiarrhythmic drug therapy including BB was guided by programmed stimulation (10), exercise testing (8), ambulatory monitoring (12), or was given empirically (2). Beta blockers were well tolerated, as measured by exercise duration, which improved significantly, and by long-term maintenance, which continued in 23 of 32 (72%) patients. Over a mean follow-up of 668 days, patients treated with BB had a relatively low incidence of both sudden (3%) and nonsudden (9%) death. Thus, BB can be effective and well tolerated adjunct therapy in patients with a history of ventricular tachyarrhythmias in the setting of impaired left ventricular function.

Proarrhythmic effects of antiarrhythmic drugs during programmed ventricular stimulation in patients without ventricular tachycardia

The proarrhythmic effects of class IA antiarrhythmic drugs were prospectively evaluated during programmed ventricular stimulation in 24 consecutive patients with frequent ventricular premature beats whose baseline study, performed while no antiarrhythmic drugs were being taken, showed no inducible sustained ventricular arrhythmias. No patient had nonsustained (greater than 5 beats) or sustained ventricular tachycardia by history or baseline 24 hour ambulatory electrocardiographic monitoring. Sequential stimulation studies using up to three extra-stimuli were performed after administration of procainamide, quinidine and disopyramide on different days. Proarrhythmic response was defined as induction of one or more of the following: sustained monomorphic ventricular tachycardia; sustained polymorphic ventricular tachycardia; ventricular fibrillation; reproducibly inducible nonsustained monomorphic ventricular tachycardia. During 55 antiarrhythmic drug trials (24 of procainamide, 21 of quinidine, 10 of disopyramide) in the 24 patients, 6 patients had a proarrhythmic response: sustained monomorphic ventricular tachycardia in 3, ventricular fibrillation in 2, nonsustained monomorphic ventricular tachycardia in 1. Thus, 11% of drug trials resulted in a proarrhythmic response and 25% of patients had a proarrhythmic response to one of the drugs tested. A proarrhythmic response to one drug did not predict a similar response to another drug of the same class. The 6 patients with a proarrhythmic response did not differ significantly from the other 18 patients with regard to underlying heart disease, electrocardiographic or baseline 24 hour ambulatory electrocardiographic characteristics; however, they did have a higher incidence of digoxin usage (p less than 0.02), a shorter baseline right ventricular effective refractory period (p less than 0.01) and a smaller increment in effective refractory period during antiarrhythmic drug testing (p = 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamin and nitrogen base requirements for Listeria monocytogenes and haemolysin production

A complete chemically defined medium is described for the growth of different serovars of Listeria monocytogenes. The medium supported rapid, luxuriant and transferable growth. At the same time haemolysin production was induced to the same extent as in tryptose phosphate broth. Riboflavin and calcium-pantothenate were essential for the growth of all six strains tested. Biotin, pyridoxal-hydrochloride and p-aminobenzoic acid were either essential or stimulatory to all strains. Most strains did not require folic acid, thiamin, nicotinic acid and inositol, but they were stimulatory for some strains. Adenine was essential for two strains (NCTC 7973, 5214 m) while cytosine exhibited an inhibitory effect on the growth of all the strains.

A survey of blood groups

A survey was conducted to investigate into the frequency of different blood groups in Punjab. A total of 1415 persons were included in this survey. The slide method was used for determination of ABO and AB blood groups as well as Rh factor. The frequency of blood group A was 21.20%; B, 36.16%; AB, 9.05% and O, 34.14%. Distribution of blood groups among various castes revealed the incidence of blood group A, 13.57% to 30%; B, 28.125% to 50%; O, 16.67% to 40%; and AB, zero to 25%. Only 2.76% cases were found to be Rh negative. Rh negative frequency was much higher in Baluchs, Awans and Gujjars than Rajputs, Jats and Arains.