Bound vitamin B12 absorption in patients with low serum B12 levels.

In many patients with low serum levels of vitamin B12, the absorption of the free vitamin has been normal. The present study, using a total body counter 57CoB12 absorption method that clearly separated those with intrinsic factor deficiency from controls, found that of 94 patients with low B12 levels and intact stomachs in whom the absorption of free and bound B12 was determined, 44 (47%) had normal absorption of both. However, 20 of the 94 (21%) with normal absorption of free B12 had low absorption of bound B12. The remainder (32%) had low absorption of both free and bound B12. All patients with high serum gastrin levels had low bound B12 absorption, but so did 21% of those patients with normal serum gastrin levels.

Further studies on the use of serum gastrin levels in assessing the significance of low serum B12 levels.

The reported incidence of low serum vitamin B12 levels in patients ranges from 4% to 8%. In only a small percentage can this be ascribed to readily diagnosed pernicious anemia, malabsorption syndrome, or to gastrointestinal surgery. This leaves a number of patients in whom the meaning of the low serum B12 is not immediately apparent. In 71 patients with intact gastrointestinal tracts, hematological indices did not adequately separate patients with decreased absorption of unbound B12 from those with normal absorption. A low absorption of B12, either unbound or food-bound, was found, however, when the level of serum gastrin was elevated. In contrast, a normal absorption of unbound B12 was likely (95% of 44 patients) when the serum gastrin was normal.

Measurement of total-body cobalt-57 vitamin B12 absorption with a gamma camera.

Previously described techniques for the measurement of the absorption of [57Co]vitamin B12 by total-body counting have required an iron room equipped with scanning or multiple detectors. The present study uses simplifying modifications which make the technique more available and include the use of static geometry, the measurement of body thickness to correct for attenuation, a simple formula to convert the capsule-in-air count to a 100% absorption count, and finally the use of an adequately shielded gamma camera obviating the need of an iron room.

Effects of dieting and exercise on lean body mass, oxygen uptake, and strength.

The effects of exercise on lean body mass (LBM), fat mass (FM), maximal oxygen uptake (VO2max), and quadriceps (QD) strength were studied in 72 male, mildly obese (X = 38% fat) subjects (X age, 43.5 yr) randomly assigned to one of eight treatments arranged in a 2 X 4 factorial plan with exercise (EX) and non-exercise (NE) and four diets as the two factors. Exercise consisted of a 3 d/wk, 8-wk aerobics program (70-85% maximum heart rate) accompanied by a calisthenics program. LBM was determined by whole body potassium (40K), FM by subtracting LBM from total body weight, VO2max using the Wilmore-Costill method, and QD strength with the Cybex II system. Weight loss of the combined EX (11.8 +/- 0.6 kg) (X +/- SE) and NE (9.2 +/- 0.3 kg) groups was not statistically different. LBM of the EX group was unchanged (from 63.1 +/- 1.9 to 62.5 +/- 2.1 kg), whereas in the NE group it was reduced from 62.6 +/- 1.1 to 59.3 +/- 1.2 kg (P less than 0.001) accounting for 36% of total weight loss. FM loss was greater for the EX group (11.2 +/- 1.5 kg) when compared to the NE (5.2 +/- 1.6 kg) group (P less than 0.001). The EX group exhibited an increase in VO2max from 2.9 +/- 0.3 to 3.4 +/- 0.2 1 X min-1 (P less than 0.001), whereas the NE group was unchanged (3.0 +/- 0.3 to 2.9 +/- 0.4 1 X min-1 (NS].(ABSTRACT TRUNCATED AT 250 WORDS)

The utility of serum gastrin levels in assessing the significance of low serum B12 levels.

Elevated levels of serum gastrin as a consequence of gastric achlorhydria are characteristic of clinical pernicious anemia. In a largely male hospitalized population with an average age of 64 years, 7.7% had low levels of serum B12 (less than 170 pg/mL); only 2.5% of these had frank pernicious anemia. In an attempt to separate a subgroup with low levels of serum B12 in whom pernicious anemia may later develop, their serum gastrin levels were determined. Twenty-two percent had high values and, of these, 70% had low B12 absorptions. In patients with low serum B12 levels, serum gastrin assays may be useful in determining those in whom clinical pernicious anemia seems likely to develop.

Relationships between computed tomography tissue areas, thicknesses and total body composition.

Computed tomography (CT) scanning was evaluated for its potential application to body-composition research. Three cross-sections (upper leg, abdomen, chest including upper arms) were scanned in 41 healthy men (mean age 57.6 years). Subcutaneous fat thicknesses measured at specific sites on the CT scans were correlated with the total area of fat from the same scans. For the chest and leg cross-sections, correlations were highly significant. Subcutaneous fat thicknesses at the abdomen were relatively poorer correlates of total abdomen fat area, because they were unrelated to intra-abdominal fat. Correlation analyses were performed between fat areas of each cross-section and total fat weight (by 40K counting), and the abdomen yielded the highest correlations. Multiple regression was used to predict abdomen fat area from external anthropometry, and abdomen circumference plus one skinfold provided excellent prediction of total abdomen fat area (R2 = 0.79). Subcutaneous or intra-abdominal fat areas separately were not predicted as well by external measurements. When lean body weight was predicted by multiple regression, leg lean area was the best predictor of any anatomical cross-section.

Correction of attenuation in whole-body determination of Co-57 B12 absorption: concise communication.

The use of Co-57-labeled B12 for whole-body measurement of B12 uptake in humans has the advantage over Co-58 of easy commercial availability and lower cumulative radiation to the liver, but the disadvantage of significant attenuation. Methods devised to correct for the attenuation have used inaccurate early 100% counts. A method is described here that uses a liver phantom, containing a dissolved Co-57 B12 capsule, in a water tank. The ratios of upper to lower detector counts is related to total counts; it varies at different depths in the tank, and with the overall tank depth that is selected to accord with measured body habitus. The ratio of detector counts in the final patient count is used to read off the appropriate 100% total count. With this technique there is a clear discrimination between normal patients and those with pernicious anemia.

Comparison of ultrasound and skinfold measurements in assessment of subcutaneous and total fatness.

Ultrasound (A-scan mode) and skinfold methods were evaluated in the measurement of subcutaneous fat thickness and prediction of total fat weight (by whole body potassium counting). Based on intraobserver correlations on 39 men at 15 body sites, skinfold caliper measurements were more reproducible than ones obtained by ultrasound. Measurements made with the two techniques at the same site typically produced different mean estimates of fat thickness. However, scores were often highly correlated with each other, indicating similar relative rankings of subjects by each technique. Skinfolds were more highly correlated with total fat weight than were ultrasound measurements, but body weight. Anthropometric measurements were highly correlated with fatness because of their association with body weight, and when this relationship was statistically controlled for, they typically lost their predictive effectiveness. Multiple regression analyses revealed that the best predictors of fat weight were body weight along with skinfold and ultrasound measurements. These results suggest that skinfolds are a more effective means of assessing subcutaneous fat than ultrasound, especially when the large difference in cost of equipment is considered.

The medical effects of radioactive fall-out: role of stable end-products?

To summarize, from preliminary observations on the possible effects of radioactive fall-out, it may be inferred that in addition to the secondary products of ionizing irradiation per se, the stable end-products of the transmutation of certain radionuclides may adversely influence cellular metabolism, including mutagenesis. The discussion of the possible role of intracellular barium as an end-product of 137Cs decay is offered as an example of an unpredictable number of broad ecological, as well as the more limited medical, effects that may be of both clinical and climatological significance.

Long-term antithyroid treatment in hyperthyroidism.

The major drawback to treatment of hyperthyroidism with antithyroid compounds is the reported low rate of remission. Eighty patients have been given long-term (at least one year; average, 4.4 years; range, one to 14 years) continuous treatment with a remission rate of 76% and an average follow-up of 7.8 years (one to 21 years). The prognostic test of suppressed uptake by the thyroid of less than 20% was about 75% accurate in predicting continuing remission when treatment was stopped. Of those in remission, 14 (23%) were treated for one year, 35 (57%) for one to five years, and 12 (20%) for more than five years. Mild reactions occurred in five (6%), hypothyroidism in two (3%). An antithyroid drug is safe and effective therapy for hyperthyroidism.

Sensitivity and specificity of radioisotope renography in renovascular hypertension.

Effective drug therapy for hypertension modifies the urgency of establishing a diagnosis of renal arterial stenosis. The cost of establishing a diagnosis must be considered with other factors in determining the usefulness of renography in renovascular hypertension. Recently published studies estimate the cost effectiveness of this procedure based on some data from a cooperative study of renal vascular hypertension. The small but costly incidence of false positives contributes significantly to the total cost of patient screening. Careful attention to technical details that are presented here could reduce false positives without sacrificing the true positives. However, even with increased specificity economic considerations would indicate limiting a screening program to younger patients or those in whom a drug regimen is unsuccessful.

Measures of clinical efficacy. Cost-effectiveness calculations in the diagnosis and treatment of hypertensive renovascular disease.

The sensitivity and specificity of the hypertensive intravenous pyelogram and the iodohippuran renogram have been determined for the diagnosis of renovascular disease, and cost-effectiveness calculations have been made for the diagnosis and surgical treatment of patients with renovascular hypertension. When the intravenous pyelogram alone is used to screen representative hypertensive population, 78 per cent of patients with renovascular disease are located, but at the same time an equal number of patients without renovascular diasease have abnormal pyelograms. The renogram, on the other hand, is associated with varying true-positive and false-positive ratios. These data can be plotted in the form of a receiver-operating-characteristic curve. The cost of finding a patient with renovascular disease is about $2,000, and that of a surgical cure is about $20,000. The number of deaths for 100 surgical cures is approximately 15. The dollar cost of screening and treating the total American renovascular hypertensive population is of the order of 10 to 13 billion dollars.