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Biomedical subjects

M M Khan

Publications and source records attributed to M M Khan.

At least 163 records · Page 9Linked to original sources
PubMed1984

Group C streptococcal endocarditis associated with intubation-induced tracheal stenosis.

We describe a 44-year-old woman with Group C haemolytic streptococcal endocarditis who developed tracheal stenosis as a result of endotracheal intubation. She recovered fully following valve replacement for continuing left ventricular failure due to mitral and aortic incompetence and subsequent resection of the stenosed tracheal segment with reanastomosis of the trachea.

Adult↗
PubMed1981

Management of recurrent ventricular tachyarrhythmias associated with Q-T prolongation.

Eleven patients with acquired prolongation of the Q-Tc interval and recurrent ventricular tachyarrhythmias were studied. Five patients required 5 to 44 direct current shocks to correct prolonged ventricular tachyarrhythmias, and five were given at least two antiarrhythmic agents in an attempt to control the arrhythmias. In 4 of the 11 patients, when thioridazine, diuretic drugs and antiarrhythmic agents were withdrawn and hypokalemia or hypocalcemia corrected, ventricular tachyarrhythmias did not recur. The Q-Tc interval normalized in 2 to 3 days. Ventricular tachyarrhythmias were recurrent in the remaining seven patients, despite withdrawal of the drugs that caused the Q-Tc prolongation, attempted correction of hypokalemia when present and the administration of antiarrhythmic agents to four of the seven. All antiarrhythmic agents were then withdrawn in this group. Immediately on the establishment of overdrive ventricular or atrioventricular sequential pacing in these patients, ventricular tachyarrhythmias were abolished. No breakthrough ventricular tachyarrhythmias occurred during temporary pacing. Temporary pacing was required for an average of 10 days and the Q-Tc interval normalized an average of 5 days from the onset of pacing. Three patients required a permanent pacemaker, one because of chronic complete heart block, one because of the sick sinus syndrome, and one because of frequent ventricular ectopic complexes complicating ischemic heart disease. All 11 patients survived their period of hospitalization.

Adult↗
PubMed1981

Discrete subaortic stenosis.

Data concerning 17 consecutive patients with discrete subaortic stenosis are recorded. Twelve patients underwent operative resection of the obstructing lesion. Of these all except one were symptomatic and all had electrocardiographic evidence of left ventricular hypertrophy or left ventricular hypertrophy with strain. They had a peak resting systolic left ventricular outflow tract gradient of greater than 50 mmHg as predicted from the combined cuff measurement of systolic blood pressure and the echocardiographically estimated left ventricular systolic pressure and/or as determined by cardiac catheterisation. The outflow tract gradient as predicted from M-mode echocardiography and peak systolic pressure showed close correlation with that measured at cardiac catheterisation or operation. During the postoperative follow-up from one month to 11 years, of 11 patients, one patient required a further operation for recurrence of the obstruction four years after the initial operation. All patients are now asymptomatic. Five patients have not had an operation. The left ventricular outflow tract gradient as assessed at the time of cardiac catheterisation was greater than 50 mmHg. One patient has been lost to follow-up. The remaining four have been followed from four to eight years and have remained asymptomatic and the electrocardiograms have remained unchanged. Careful follow-up of all patients is essential with continuing clinical assessment, electrocardiograms, M-mode and two-dimensional echocardiograms, and if necessary cardiac catheterisation. Prophylaxis against bacterial endocarditis is also essential.

Adolescent↗
PubMed1980

Actinomycin D binds with highest affinity to nonribosomal DNA.

Based on previous evidence (T.J. Lindell (1976) Nature 263, 347-350 and T.J. Lindell, A.F. O'Malley, and B. Puglisi (1978) Biochemistry 17, 1154-1160) it was anticipated that actinomycin D in a low concentration would bind to DNA which is involved in the regulation of rRNA transcription in eukaryotes. This was examined by digestion of rat (liver) DNA with EcoRI, adding [3H]actinomycin D (0.004 microgram/ml) and resolution of the restriction fragments by RPC-5 chromatography. Labeled actinomycin D was found to bind with highest affinity to a single fraction consistently eluting at 0.63 M KCl. A similar digestion and fractionation of nucleolar DNA, which is enriched in rDNA sequences, did not reveal a similar high affinity binding of actinomycin D. This fraction of DNA which binds actinomycin D with highest affinity did not contain any rDNA as evidenced by hybridization with [32P]rRNA. Therefore, at the concentration of 0.004 microgram/ml, actinomycin D does not selectively bind to rDNA as evidenced by two independent criteria. Whether this high affinity actinomycin D-binding DNA has any function in the regulation of rRNA transcription remains to be determined.

Animals↗
PubMed1980

Management of ventricular septal rupture in acute myocardial infarction.

Four patients with rupture of the interventricular septum after myocardial infarction are described. This condition carries a grave prognosis. Surgical repair of the septum is almost always urgently required if the left-to-right shunt is large (QP/WS > 3). Results are better if surgery can be deferred for six weeks to allow the infarcted area to heal and the tissues to be come firmer. This delay may be achieved by using a combination of agents to reduce afterload and to exert a positive inotropic effect. The timing of surgical intervention was an important factor in the survival of three of the four patients.

Female↗
PubMed1980

Amiodarone-induced ventricular fibrillation.

Amiodarone, 600 mg orally daily, was used in an attempt to control supraventricular tachyarrhythmias in a patient with the sick sinus syndrome. Twenty days from the onset of therapy the Q-T interval lengthened. Episodes of ventricular flutter, ventricular fibrillation and self-terminating ventricular tachyarrhythmia (torsade de pointes) developed on the 28th day of amiodarone therapy. Temporary cardiac pacing prevented further episodes of ventricular fibrillation. Despite the suggestion that this drug may be given in large doses for long periods of time since it has a wide safety margin, we feel that the risk of lethal arrhythmias is such that caution is required in its use.

Amiodarone↗