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Biomedical subjects

R Siddiqi

Publications and source records attributed to R Siddiqi.

10 recordsLinked to original sources
PubMed2006

Does use of isotretinoin rule out a career in flying?

AIM: To evaluate whether previous isotretinoin use induces permanent, measurable, and clinically significant abnormalities in night vision such that flying is precluded, and whether potential military and civilian commercial aviators should be screened routinely. METHODS: A retrospective, non-interventional, consecutive case series of 47 individuals with a confirmed history of oral isotretinoin use were compared to 20 age and sex matched controls. RESULTS: 47 individuals (44 males and three females), age range 17-33, underwent Goldmann-Weekers dark adaptation (DA) and standard electroretinogram (ERG) according to ISCEV protocols. 34 patients showed no abnormality in any parameters. Two patients had abnormal DA and ERGs. The mean scotopic ERG b wave amplitude of the isotretinoin group was 496.5 microV (SD 51.3 microV) compared with 501.7 microV (62.3.1 microV) among the controls. The group mean a:b ratio was 0.55 (0.04) compared to 0.69 (0.08) in the controls. CONCLUSION: Previous use of isotretinoin may have caused retinal toxicity in two subjects and laboratory evidence of night blindness in 11 further subjects. One subject had subclinical changes remaining in the ERG 96 months after cessation of isotretinoin. This may justify the directed use of electrophysiological screening in professions that are night vision critical.

Adolescent↗
PubMed2003

Chromosome 5.

Explore the source record for details and available documents.

Chromosome Mapping↗
PubMed1993

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.

Culture Media↗
PubMed1989

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.

Amino Acids↗
PubMed1988

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.

Adrenergic beta-Antagonists↗
PubMed1987

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)

Adult↗
PubMed1982

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.

4-Aminobenzoic Acid↗
PubMed1977

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.

ABO Blood-Group System↗