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Biomedical subjects

T Alexander

Publications and source records attributed to T Alexander.

At least 37 records · Page 2Linked to original sources
PubMed1993

Pseudohypertension in a child with Williams syndrome.

Pseudohypertension has often been reported in elderly subjects, but is an unusual phenomenon in children. We report the case of a 5-year-old child who presented with features of Williams syndrome (characterized by elfin facies, supravalvar aortic stenosis, and peripheral pulmonary artery stenosis). Repeated blood pressure recordings made with appropriately sized blood pressure cuffs were very high, while simultaneous intraarterial blood pressure was normal, confirming the presence of pseudohypertension. This was shown to be caused by excessively thickened arterial vessels.

Aortic Valve Stenosis↗
PubMed1992

Effect of three antibacterial drugs in lowering blood & stool ammonia production in hepatic encephalopathy.

Neomycin (700 mg/8 h), ampicillin (500/6 h) and metronidazole (400 mg/8 h), were compared for their effect, on oral administration for 4 days, in reducing blood ammonia in 27 patients with stable chronic liver disease. It was found that there was 38.2, 38.5 and 8.7 m mol/litre mean reduction in blood ammonia in the neomycin, ampicillin and metronidazole treated groups respectively. The difference in blood ammonia was statistically significant for both neomycin (P = 0.01) and ampicillin (P = 0.03) but there was no significant change after metronidazole treatment (P = 0.6). The total stool enzyme activity at optimum pH was maximally reduced by ampicillin and minimally with metronidazole. The reduction was noted to be 3.51 m mol/1 (P = 0.01), 3.87 m mol/1 (P = 0.08) and 2.8 m mol/1 (P = 0.02) of NH3/g dry weight of stool for neomycin, ampicillin and metronidazole respectively. The main bacterial gut enzymes responsible for ammonia production, urease and protease, were found to be very sensitive to stool pH. At pH 6 their activity was around 20 per cent of what was found in optimum pH of 7.4 and at pH 5 it is only about 8 per cent of optimum activity. None of the three antibacterial agents changed the stool pH significantly. It can be concluded that oral neomycin and ampicillin are superior to oral metronidazole in lowering blood ammonia.

Administration, Oral↗
PubMed1992

Foregut ischemia and odynophagia in a patient with a type III aortic dissection.

We report a case of ischemia of the distal esophagus with secondary odynophagia that occurred as a result of a type III aortic dissection. A 56-yr-old hypertensive male presented with acute chest pain radiating to his back. A dissection of the descending aorta was found to begin just distal to the left subclavian artery and end in the region of the iliac arteries. The patient was treated medically and remained stable, but then developed odynophagia to solids. Upper endoscopy showed erythematous friable esophageal mucosa, and biopsies were consistent with ischemia. Aortography and barium fluoroscopy provided further evidence of foregut ischemia. The patient recovered on oral omeprazole with no residual symptoms. Ischemic compromise of the esophagus secondary to aortic dissection has not been previously described, nor have the associated endoscopic findings. Knowledge of this rare condition may help in the recognition and management of esophageal mucosal ischemia.

Aortic Dissection↗
PubMed1991

Anti-streptokinase levels in Indian patients.

Levels of anti-streptokinase antibodies were measured in 75 Indian patients who were divided into three groups. The first group consisted of 25 healthy blood donors; the second group of 25 patients with ischaemic heart disease with stable angina; and the third group of 25 patients with acute myocardial infarction. The mean level of anti-streptokinase for the entire group was 0.37 SD 0.20 million international units (IU) (range 0.09 to 1.15 million IU). There was no significant difference in the anti-streptokinase levels among the three groups. In order to neutralise the anti-streptokinase levels in 90% of the study population, 0.57 million IU of streptokinase was necessary. These levels are more than twice the current Western levels. In the light of this study, it may be necessary to reconsider the adequacy of the conventional dosage of streptokinase while treating acute infarctions in India and, possibly, other tropical countries where prevalence of prior streptococcal infection is high.

Adult↗
PubMed1991

Association between cigarette smoking and coronary arterial disease in patients in India: how quantitative is it? An assessment by selective coronary arteriography.

With a view to study the association between smoking and coronary arterial disease, and to identify any quantitative relationship, we undertook a cross sectional analysis of 1105 consecutive male patients investigated by selective coronary arteriography to confirm or exclude coronary arterial disease. Pattern and distribution of disease were evaluated in 3 groups of patients who never smoked; who smoked less than 5 cigarettes per day; and who smoked 6 to 60 or more cigarettes per day. Suitable statistical tests, including adjusting for confounders, were carried out. The prevalence of disease was higher amongst smokers even after adjustment for confounders. The number of cigarettes smoked, and whether the smokers had quit, made no difference to the angiographic appearance or extent of disease. There was no difference in the distribution and severity of disease amongst smokers and non-smokers. Rate ratio of disease amongst smokers in India was higher in those patients between 26 and 45 years of age than in other age groups. Smoking could be identified as a risk marker/risk factor that accelerated the disease process in those prone to develop the disease. It may be advantageous to initiate public health and preventive measures directed specifically at the group aged between 26 to 45 years, and later to address all others who smoke.

Adult↗
PubMed1990

Stability of phenytoin in blood collected in vacuum blood collection tubes.

The stability of phenytoin in blood collected in plain and serum separator tubes (SSTs) was investigated under simulated storage and transport conditions. The drug was generally more stable in plain collection tubes than in SSTs. No degradation occurred in plain red-top tubes or in refrigerated SSTs, but clinically significant degradation was present in SSTs stored at room temperature (25 degrees C) and at elevated temperature (32 degrees C) 24 h after collection. The mean loss was 17.9% at 25 degrees C and 25.9% at 32 degrees C. It is recommended that if blood is to be transported or stored in SSTs, the samples be refrigerated unless assay can be performed within 8 h.

Drug Packaging↗
PubMed1989

Social contingency effects on subsequent perceptual-cognitive tasks in young infants.

3 experiments with 3-month-old infants compared the effects of contingent and noncontingent adult-infant social interactions on subsequent infant-controlled habituation and choice tasks. Infants who experienced a prior noncontingent social interaction tended to adopt response strategies that reduced the density of stimulation during these subsequent nonsocial tasks. The results are discussed in terms of their generality and the types of mechanisms that might mediate these transfer effects from social to nonsocial procedures.

Arousal↗
PubMed1985

Oral nifedipine in hypertensive emergencies.

A study was carried out to evaluate the efficacy and tolerance of oral nifedipine in hypertensive emergencies. Eleven consecutive patients with very high blood pressure requiring emergency reduction were included in the study. Nifedipine (10 mg) was given orally at 6-hourly intervals and blood pressure, pulse, serum electrolytes, urea, creatinine and uric acid were monitored. A reduction in blood pressure was noted within 10 minutes, with a significant reduction occurring within 30 minutes (reduction of systolic blood pressure by 8.11% and diastolic blood pressure by 9.38%). The maximum reduction in blood pressure occurred within 90 minutes (reduction of systolic blood pressure by 20.78% and diastolic blood pressure by 21.74%) and remained at this level for 4 hours, after which a mild increase in blood pressure was noted. At 6 hours, the reduction in blood pressure was 15.41% and diastolic reduction was 17.94%. The reduction in blood pressure was found to be directly correlated with the pre-treatment blood pressure. There was no significant alteration in the pulse rate or blood chemistry. No side-effects were noted during the study. It is suggested that oral nifedipine is a simple, effective and well-tolerated alternative to parenteral therapy in the management of hypertensive emergencies.

Adolescent↗
PubMed1981

High-performance liquid chromatographic determination of components of bleomycin preparations.

A fast and sensitive method was developed for the quantitative determination of at least 10 components of pharmaceutical bleomycin sulfate preparations. The method is based on the reversed-phase high-performance liquid chromatographic (HPLC) separation of the components on a muBondapak C18 column with a mobile phase having a linear gradient of 10--40% methanol in aqueous 0.005 M 1-pentanesulfonic acid at pH 4.3. With this assay, the average standard deviations for components A2 and B2 are 0.92 and 0.87, respectively, for a 7.5--22.5 x 10(-3)-mg sample. Regulatory agencies presently use the official Code of Federal Regulations (CFR) method, which is based on CM-Sephadex column chromatography. It was demonstrated that this CFR method does not separate the bleomycin A2 component from some other minor bleomycin components. After elution from the CM-Sephadex column, the "A2 component" was separated into five components by the HPLC method. Bleomycin A2 is stable under these HPLC conditions.

Bleomycin↗
PubMed1980

Suppressor cell defect in SLE: relationship to native DNA binding.

Recent evidence suggests the presence of a suppressor T cell defect in systemic lupus erythematosus. We confirm the presence of such a defect and find a strong quantitative correlation between the loss of suppressor T cell function and the activity of SLE as measured by the presence of antibodies to native DNA. In addition, the serum of patients with active SLE contains a soluble factor which when incubated with normal peripheral blood lymphocytes induces a suppressor T cell defect. These data are consistent with the suppressor cell defect being involved in the propagation and possible the pathogenesis of SLE, and suggests a positive feedback mechanism whereby a suppressor cell defect results in autoantibodies including antibody to suppressor cells.

Adult↗
PubMed1979

It's roundup time for the runaway regulators.

Alexander reviews some of the problems caused by governmental regulation of business practices and considers some of the current moves to decrease regulatory intervention. According to the author, this is the first time in 15 years Congress has acknowledged that regulation is a matter of serious concern. The trigger was a 1978 proposal of the Federal Trade Commission (FTC) to extend its control over the voluntary product standards established by industry. Prior to that action, the author states, the FTC was condemned for listless enforcement. Economists blame excessive regulation for low productivity, lack of innovation, inflation, unemployment, and shortages. The author points out that the stringent rules of the Federal Drug Administration (FDA) have brought about a steep decline in the number of new drugs introduced--drugs which presumably could have prevented considerable suffering and quite a few deaths. The author thinks that the gold medal earned by the FDA for its refusal to approve Thalidomide has fostered a siege mentality--"We only get into trouble by approving something." The stringent regulations have caused voter dissatisfaction, as evidenced by the attempt of the FDA to bar the use of saccharine. In an effort to restore political accountability, Congress is considering strengthening the oversight of agencies by elected officials. The House of Representatives favor the wider use of the "legislative veto." This would make any new rule an agency writes subject to nullification by either House of Congress for a 60-day period. The Senate prefers a "sunset" approach, which would require that regulations, spending programs, and even entire agencies undergo periodic reapproval. A study carried out by the American Bar Association (ABA) singles out the congressional sin of needlessly enlarging the burden of regulation by creating a new agency every time it perceives a problem, eventually resulting in sharply increased regulatory compliance costs. The same ABA study recommends that each agency be required to prepare an analysis of the likely costs and benefits of their proposed rulings and of recommended regulations in light of established national priorities. Alexander concludes that the ABA recommendation for increased reliance upon the competitive market is an essential step in encouraging regulatory reform.

Commerce↗