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Biomedical subjects

J F Walker

Publications and source records attributed to J F Walker.

At least 55 records · Page 3Linked to original sources
PubMed1991

Respiratory failure associated with myasthenia gravis.

Dysphagia and respiratory muscle weakness are the two most potentially dangerous findings in patients with neuromuscular disease because they predispose to aspiration pneumonia and respiratory failure. Myasthenia gravis is unique among the neuromuscular disorders for the variety of exacerbating factors that may lead to such clinical deterioration. While the major cause of ventilatory failure remains intensification of the underlying autoimmune process, well intentioned therapy may also lead to situations that necessitate ventilatory support. This report describes a patient with myasthenia gravis and respiratory failure and reviews the various etiologies of pulmonary dysfunction that are associated with the natural course of this disease and its treatment.

Adult↗
PubMed1990

Hydroxymethylglutaryl coenzyme A reductase inhibitors as monotherapy in the treatment of hypercholesterolemia.

A variety of double-blind studies have compared the efficacy of hydroxymethylglutaryl coenzyme A reductase inhibitors (lovastatin and simvastatin) with that of control agents (cholestyramine, fibrates and probucol) in patients with type IIA or IIB primary hypercholesterolemia. Results have shown that both lovastatin and simvastatin are more effective than the standard therapies with regard to reducing total and low-density lipoprotein cholesterol. Decreases in triglycerides and increases in high-density lipoprotein cholesterol were generally greater with fibrates. Ongoing studies are assessing the benefits of lovastatin and simvastatin in reducing the incidence of mortality from coronary artery disease, as well as causing regression of coronary atheroma.

Bezafibrate↗
PubMed1990

The relationship of the internal security system to group level organization in Miller's living systems theory.

It has been suggested that a 20th subsystem, the internal security subsystem, should be added to Miller's 19 matter-energy and information processes that are critical to living systems (Bosserman, 1982). This subsystem protects all levels of living systems from error and disruption resulting from internal and external sources. Yet many characteristics of the proposed security subsystem already are found in existing ones, that is, the reproducer, channel and net, and distributor. Therefore, a discrete internal security subsystem is not justified. There are, however, dormant aspects of the security system that are not described within the existing taxonomy that perhaps best fit as a mirror system across the organizational levels.

Animals↗
PubMed1989

Simvastatin: the clinical profile.

Simvastatin is the second in the class of compounds known as hydroxy-methylglutaryl-coenzyme A reductase inhibitors to be extensively studied in humans. The drug has now been given to over 1,800 patients with primary hypercholesterolemia for periods of up to two years. In the range of dosage from 10 to 40 mg once daily, therapy is associated with reductions of up to 30 percent in total cholesterol and 40 percent in low-density lipoprotein cholesterol levels, as well as with increases of approximately 10 percent in high-density lipoprotein cholesterol levels. The most common clinical adverse experiences are mild gastrointestinal effects and headache, which seldom require discontinuation of therapy. Elevations of creatine kinase (skeletal muscle isoenzyme) levels to more than three times the upper limit of the normal range have been seen in about 3 percent of patients, but also have seldom required discontinuation of therapy. Conversely, elevations of hepatic transaminase levels to more than three times the upper limit of the laboratory normal range have been seen in about 1.5 percent of patients and have caused discontinuation of therapy in 0.6 percent of patients treated. Simvastatin appears to be an effective and well-tolerated agent for the treatment of primary hypercholesterolemia and, as further study confirms long-term safety and efficacy, it should become a useful addition to the therapeutic armamentarium.

Aged↗
PubMed1989

Comparison of low-dose simvastatin and gemfibrozil in the treatment of elevated plasma cholesterol. A multicenter study. The Simvastatin Study Group.

A 12-week, randomized, double-blind, multicenter study was undertaken to compare the efficacy, tolerability, and safety of simvastatin and gemfibrozil in 290 patients with primary hypercholesterolemia. Patients in stratum I (initial low-density lipoprotein cholesterol level less than 195 mg/dl) received simvastatin 5 to 10 mg once every afternoon; patients in stratum II (initial low-density lipoprotein cholesterol level at least 195 mg/dl) received 10 to 20 mg once every afternoon. Gemfibrozil was given in a constant dosage of 600 mg twice daily in both strata. Simvastatin reduced low-density lipoprotein cholesterol levels by 26 and 34 percent in strata I and II, respectively. The corresponding reductions brought about by gemfibrozil were 18 and 17 percent. High-density lipoprotein cholesterol was increased by 7 and 9 percent by simvastatin and by 17 and 16 percent by gemfibrozil in strata I and II, respectively. Ratios of low-density to high-density lipoprotein cholesterol were reduced by approximately 25 percent by simvastatin 5 to 10 mg once every afternoon and gemfibrozil 600 mg twice daily, but were reduced by 37 percent by simvastatin 10 to 20 mg once every afternoon. Both drugs reduced plasma triglyceride levels, but gemfibrozil was much more effective. The short-term tolerability and safety of both drugs appeared to be good during the 12-week study. The results suggest that both drugs have useful but distinctly different lipid-modifying properties.

Anticholesteremic Agents↗
PubMed1989

Resting gas exchange in nonsmoking bituminous-coal miners with simple pneumoconiosis.

Gas exchange at rest under normoxic conditions was studied in 2,297 nonsmoking bituminous-coal miners with and without simple coal workers' pneumoconiosis (CWP). Measurements of arterial oxygen tension (Pao2) and arterial carbon dioxide tension (Paco2) from blood gas samples obtained at rest in the seated position were used to calculate the alveolar-arterial oxygen tension difference, (A-a)Do2, using the classic alveolar-air equation. We then recalculated the (A-a)Do2 using the age-predicted Pao2 for each miner. The difference between the actual and the predicted (A-a)Do2 was measured and the mean difference for each category of simple CWP was analyzed. We found no evidence that the resting gas exchange differs significantly from the age-predicted (A-a)Do2 in the nonsmoking bituminous-coal minor with simple CWP. Likewise, there is no significant change in (A-a)Do2 with change in the category of simple CWP.

Age Factors↗
PubMed1989

Perceptions and utilization of hyperbaric oxygen therapy for carbon monoxide poisoning in an academic setting.

The routine use of hyperbaric oxygen as therapy for carbon monoxide intoxication is being critically reexamined nationally. There are no controlled prospective clinical studies that show this modality to clearly be superior to the more traditional use of high concentrations of supplemental oxygen. Proponents of hyperbaric therapy often claim that such studies would now be unethical, would violate the accepted standard of care for this medical emergency, and would place the treating physician in an indefensible medical-legal position. In an attempt to determine the status of hyperbaric oxygen in our community as treatment for significant carbon monoxide exposure, we surveyed physicians practicing at the university regional trauma center to determine their perception of the indications for hyperbaric oxygen therapy for carbon monoxide poisoning. We then audited the medical records of all patients treated during a four-year period with the diagnosis of carbon monoxide poisoning or smoke inhalation to determine the actual utilization of this therapeutic modality. The results of our study indicate that hyperbaric referral is not the standard treatment for significant carbon monoxide intoxication in this academic setting.

Academic Medical Centers↗