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Biomedical subjects

W H Heaton

Publications and source records attributed to W H Heaton.

5 recordsLinked to original sources

Familial apolipoprotein A-I and C-III deficiency, variant II.

The biochemical, clinical, and genetic features were examined in the proband (homozygote) and heterozygotes (n = 17) affected with familial apolipoprotein A-I and C-III deficiency, variant II (previously described as apolipoprotein A-I absence). The proband was a 45-year-old white female with mild corneal opacification and significant three-vessel coronary artery disease (CAD), who died shortly after bypass surgery. Autopsy findings included significant atherosclerosis in the coronary and pulmonary arteries and the abdominal aorta as well as extracellular stromal lipid deposition in the cornea. No reticuloendothelial lipid deposits in the liver, bone marrow, or spleen were noted (unlike Tangier disease). Laboratory features included marked high density lipoprotein (HDL) deficiency and undetectable plasma apolipoproteins (apo) A-I and C-III. The percentage of plasma cholesterol in the unesterified form was normal at 30%. The activity and mass of lecithin:cholesterol acyltransferase (LCAT) were 42% and 36% of normal, respectively, and the cholesterol esterification rate was 43% of normal. Deficiencies of plasma vitamin E and essential fatty acid (linoleic, C18:2) were also noted. Evaluation of plasma lipoproteins and apolipoproteins in 37 kindred members revealed 17 heterozygotes with HDL cholesterol values below the 10th percentile of normal. Of these, all had apoA-I levels more than one standard deviation below the normal mean, and 37.5% had a similar decrease in apoC-III values. Mean (+/- SD) plasma HDL cholesterol, apoA-I, and apoC-III values (mg/dl) in heterozygotes were 54.0%, 62.4%, and 79.2% of normal, respectively. No evidence of CAD was observed in 10 heterozygotes 40 years of age or less; however, CAD was detected in 3 of 7 heterozygotes over 40 years of age, one of whom died at age 56 years of complications of myocardial infarction and stroke. The inheritance pattern in this kindred was autosomal codominant. ApoA-I isolated from a heterozygote had an isoelectric focusing pattern and amino acid composition similar to normal. Utilizing DNA isolated from two obligate heterozygotes, no abnormalities in the apoA-I or apoC-III genes were detected by Southern blot analysis utilizing specific probes following restriction enzyme digestion. The data indicate that familial apolipoprotein A-I and C-III deficiency, variant II, is similar to variant I (described by Norum et al. 1982. N. Engl. J. Med. 306: 1513-1519), but differs at the clinical level (lack of xanthomas), the biochemical level (lack of detectable apoA-I, lower apoA-II level), and at the gene level.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

Beneficial effect of physical training on blood flow to myocardium perfused by chronic collaterals in the exercising dog.

To determine the effect of physical training on collateral blood flow, we measured regional myocardial blood flow (MBF) by injecting 15 mu radioactive microspheres at rest and during exercise in 14 dogs with chronic coronary occlusive lesions. Seven dogs subsequently trained for 6 weeks while the other seven remained in kennels. Training effect was documented by decrease in heart rate during exercise that averaged 35 beats/min. MBF studies were repeated after 6 weeks. Myocardial samples were obtained from normally perfused zones (NZ) and from regions supplied via collaterals (collateral dependent zones or CZ). Initially, endocardial blood flow in CZ averaged 1.110 ml/min/g (83% of NZ, P less than 0.05) at rest and 1.36 ml/min/g (69% of NZ, P less than 0.05) during exercise, indicating relative underperfusion. Epicardial blood flow was equal in NZ and CZ. After 6 weeks MBF was not significantly changed in control animals. After training, however, MBF to underperfused endocardium of CZ during exercise was 39% greater than it had been prior to training. The epicardial portion of CZ (not exhibiting underperfusion) showed no change in MBF during exercise after training. Our data suggest that beneficial effects of training in coronary disease may include improvement in MBF to underperfused collateral-dependent portions of myocardium.

Animals↗

Plasma apolipoprotein A-1 absence associated with a marked reduction of high density lipoproteins and premature coronary artery disease.

A 45-year-old woman with corneal opacification and severe coronary artery disease was noted to have the following plasma lipid levels (mg/dl, +/- SD): total cholesterol 111 +/- 13, triglyceride 62 +/- 6, very low density lipoprotein cholesterol 4 +/- 1, low density lipoprotein cholesterol 106 +/- 14, and high density lipoprotein (HDL) cholesterol 1 +/- 1 (normal, 50 +/- 14). Her two offspring and one brother were found to have HDL cholesterol values (mg/dl) of 23, 20, and 20, respectively. The percentage of cholesterol in the esterified form in the patient's plasma was normal at 70%. Lipoprotein electrophoresis showed no alpha lipoprotein band, and no HDL was detectable when plasma was subjected to analytic ultracentrifugation. Only trace amounts of lipids were noted within the HDL density region following preparative ultracentrifugation. Mean plasma apolipoprotein (apo) A-ll, apo B, and apo C-ll plasma levels were 13.8%, 130.6% and 26.6% of normal, respectively. The ratio of apo B to cholesterol within LDL was elevated. Apo A-l, the major HDL protein constituent, was immunologically undetectable in this patient's plasma. A decreased HDL cholesterol concentration has been associated with premature coronary artery disease. These data indicate that plasma apo A-l absence results in a striking reduction in HDL, is associated with premature coronary artery disease, and represents a new distinct disease entity.

Apolipoprotein A-I↗

An overview of OSHA regulations.

While it is true that chances of an OSHA survey are low, OSHA representatives are placing top priority on employee complaints by investigating every one they receive. Author W.H. Heaton has learned from OSHA that employee complaints from medical practices are on the rise and describes in his article how to minimize group risk in this area.

Blood↗