Quantitation of myelination and demyelination by the measurement of myelin basic protein by ELISA

Utilizing a competitive inhibition enzyme-linked immunosorbent assay (ELISA) we measured the amount of myelin basic protein (MBP) in brain, liver, and kidney of newborn mouse and compared these values with myelinated cerebellar explant cultures under various conditions. Explant cultures demyelinated with anti-myelin serum showed a 90% decrease in MBP when compared with controls. These results correlated with myelination and demyelination as observed by light microscopy. Newborn tissues including brain showed only negligible activity for MBP. This technique provides a sensitive and objective method for quantitating in-vitro demyelination.

Rhodopsin's amino terminus is a principal antigenic site

Antisera and monoclonal antibodies to rhodopsin were examined for their binding specificity to rhodopsin by using peptides from the rhodopsin sequence as competitors for antibody binding to rhodopsin in an enzyme-linked immunoassay. Monoclonal antibodies tested were raised in mice against bovine and rat rhodopsin. Antisera tested were raised in sheep against bovine rhodopsin and in rabbits against human rhodopsin. Peptides were synthesized from the bovine rhodopsin sequences 2-32, 1-12, 13-23, 24-34, 5-11, 231-252 and 331-348 for use as competitors in the immunoassay. A mixture of soluble CNBr peptides, and the purified CNBr peptide representing the sequence 2-39 were also employed. The monoclonal antibodies were all anti-amino-terminal in their binding specificity, although each recognized slightly different regions of the amino terminus. Each of the three antisera was predominantly directed against rhodopsin's amino terminus. We conclude that the amino-terminal 30 or more amino acids, and particularly the amino-terminal 15 amino acids, represent a principal antigenic region of the rhodopsin molecule.

Serum insulin and blood pressure in an obese population

Serum insulin has been implicated as a determinant of blood pressure (BP) level in obese hypertensive individuals. We examined the relationships among fasting insulin, mean arterial pressure (MAP), body composition, and fat distribution in 204 subjects unselected for glucose tolerance. All met the criteria of taking no oral hypoglycemic agents, insulin or antihypertensive medications. 95 percent were considered obese and 78 percent were female. Mean age was 39 years (range 15-71), percent ideal body weight (IBW) 171 percent (109-332), BP 125/81 mmHg (80-181/50-110) and fasting insulin 44 microU/ml (4-196). Lean body mass (LBM) and body fat were measured by tritium dilution. The correlation coefficient between insulin and MAP was 0.32 (P less than 0.0001). Both insulin and MAP correlated highly with percentage IBW, percentage body fat, fat mass, LBM, body build and upper fat pattern. Controlling for these variables simultaneously eliminated the association between insulin and BP. By contrast, the correlations between MAP and measures of body composition and fat distribution retained significance after controlling for insulin level. These findings suggest that measures of body composition and fat distribution have a relationship with BP that is not entirely accounted for by serum insulin level, and the relationship between serum insulin and BP is indirect and largely accounted for by their mutual association with measures of body composition and fat distribution.

Body composition studies in patients with the acquired immunodeficiency syndrome

Body composition studies were performed in 33 patients suffering from the acquired immunodeficiency syndrome (AIDS). Studies included measurements of total body potassium, fat, and total body and extracellular water volumes plus serum retinol binding protein concentration, iron binding capacity, and albumin concentration. AIDS patients were underweight (p less than 0.001) and were depleted of potassium (p less than 0.001) with the lowest values occurring in patients close to death at the time of study. Body fat contents also were reduced. Intracellular water volumes were decreased in the AIDS patients (p less than 0.001) with a relative increase in extracellular water volume (p less than 0.001). Serum protein concentrations were decreased in the AIDS patients. Longitudinal studies did not demonstrate tissue repletion in patients with AIDS, despite apparent clinical stability. These studies demonstrate that severe, progressive malnutrition occurs in patients with AIDS. If malnutrition can be shown to have a deleterious effect upon the disease course, therapy of malnutrition may play an important role in the treatment of this disorder.

The relative contribution of body fat and fat pattern to blood pressure level

Although the association between body weight and blood pressure is irrefutable, body fat mass and blood pressure level may not necessarily be directly related. To clarify the relative contribution of fat mass to blood pressure level, we analyzed data on 399 adults consecutively entering a weight control program. Although most subjects were notably overweight (mean ideal body weight 177%), the population represented a wide spectrum of body weights and blood pressure levels. Study parameters included body fat mass (by total body water, 40K, and Steinkamp formula), lean body mass, body build (chest to height ratio), fat cell number and size from bilateral buttock biopsy specimens, upper fat pattern by arm to thigh circumference ratio, and central fat pattern by subscapular to triceps skinfold ratio. Our results concurred with previously noted correlations between obesity and blood pressure (as mean arterial pressure): weight (r = 0.44), percentage of body fat (r = 0.19), and absolute fat mass (r = 0.38; all p less than 0.01); however, lean body mass, age, and body build correlated highly with both fat mass and mean arterial pressure, thereby confounding this relationship. Multivariate analysis was performed to evaluate the relative contribution of fat mass to mean arterial pressure in the presence of these and other potentially confounding variables. Lean body mass, age, body build, and an upper body fat pattern were found to contribute significantly to the variation in mean arterial pressure (p less than 0.01). In their presence, percentage of body fat, absolute fat mass, central fat pattern, fat cell characteristics, and age of onset of obesity did not significantly improve the predictability of mean arterial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Transformation of Erwinia chrysanthemi by Escherichia coli plasmids DNA

We have demonstrated in this study that CaCl2-MnCl2 treatment is effective in the preparation of competent cells of Erwinia chrysanthemi for transformation. Plasmids pMB9 and pBR322, which are of Escherichia coli origins, were transformed into E. chrysanthemi at frequencies of 1.5 X 10(-7) and 4.5 X 10(-7) per recipient, respectively. The frequencies were 60- to 80-fold lower than those in the well established rec- E. coli; however, the procedure is practically useful in transformation experiments. The plasmids were maintained rather stable in the cells if antibiotics were included in the media. When transformed by pECl and pEC6, which were chimeric plasmids consisting of pBR322 and an E. chrysanthemi chromosomal DNA fragment of 2.4 and 3.5 Mdal, respectively, the transformation frequencies of E. chrysanthemi were at the same range of that by pBR322. Neither colony morphology nor the polypectate degradation ability was changed after transformation by the plasmids. In conclusion, we have established a system of molecular cloning in E. chrysanthemi SR120A exploiting pBR322 as a vector.

Estimation of human body composition by electrical impedance methods: a comparative study

This study 1) further validated the relationship between total body electrical conductivity (TOBEC) and densitometrically determined lean body mass (LBMd) and 2) compared with existing body composition techniques (densitometry, total body water, total body potassium, and anthropometry) two new electrical methods for the estimation of LBM: TOBEC, a uniform current induction method, and bioelectrical impedance analysis (BIA), a localized current injection method. In a sample of 75 male and female subjects ranging from 4.9 to 54.9% body fat the correlation between LBMd and LBM predicted from TOBEC by use of a previously developed regression equation was extremely strong (r = 0.962), thus confirming the validity of the TOBEC method. LBM predicted from BIA by use of prediction equations provided with the instrument also correlated with LBMd (r = 0.912) but overestimated LBM compared with LBMd in obese subjects. However, no such systematic error was apparent when new prediction equations derived from this heterogeneous sample of subjects were applied. Thus the TOBEC and BIA methods, which are based on the differing electrical properties of lean tissue and fat and which are convenient, rapid, and safe, correlate well with more cumbersome human body composition techniques.