Individual growth in stature: a comparison of four growth studies in the U.S.A

Patterns of growth in stature of subjects from the four major U.S. longitudinal growth studies are compared by means of a two-component model for individual growth. Problems inherent in the comparison of data from independent growth studies, such as those arising from different methods of sampling subjects and scheduling measurements and the occurrence of atypical subjects, are considered and solutions are offered. Statistical tests of the individual growth parameters revealed significant, but small, differences among the samples in the magnitude of the contributions of prepubertal and adolescent growth to mature stature and in the velocity of growth. No differences between samples in the timing of the adolescent component were detected.     

In situ morphologies of deep-sea and sediment bacteria

Deep-sea and sediment bacteria at the bottom of an approximately 1200-m water column were sampled by means of pressure vessels attached to a remote underwater manipulator. Cells were immediately fixed in situ with glutaraldehyde, and after processing in the laboratory their morphologies were observed with the scanning electron microscope. Most bacteria were coccoid or rod-lide and less than 0.4 mum in diameter or width. Few filamentous bacteria were observed. Bacteria were in aggregates or free-living. It is concluded that morphologies of deep-sea bacteria collected and fixed at the hydrostatic pressure of their environment are, in general, similar to the observed morphologies of deep-sea bacteria determined at 1 atm pressure after collection and decompression during ascent through the water column.     

Effects of short-and long-term administration of tricyclic antidepressants and lithium on norepinephrine turnover in brain

The findings summarized in this paper show that norepinephrine turnover in brain is decreased after acute administration of imipramine or desmethylimipramine but tends to increase during chronic administration of these tricyclic antidepressants. Similarly, it appears that there also may be important differences between the effects of acute and chronic administration of lithium salts on norepinephrine turnover in the central nervous system. Such changes in norepinephrine turnover that develop gradually over the course of long-term drug administration may help to explain the need for chronic administration of tricyclic antidepressants or lithium salts in the treatment of patients with affective disorders.     

Low density lipoprotein apheresis improves regional myocardial perfusion in patients with hypercholesterolemia and extensive coronary artery disease. LDL-Apheresis Atherosclerosis Regression Study (LAARS)

OBJECTIVES: In a randomized study we evaluated the effect of biweekly low density lipoprotein (LDL) apheresis plus simvastatin versus medication alone on regional myocardial perfusion. BACKGROUND: In patients with severe hypercholesterolemia, diet and lipid-lowering drugs are often insufficient to achieve optimal LDL cholesterol values. Low density lipoprotein apheresis is a very effective lipid-lowering therapy. Assessment of regional myocardial perfusion enables evaluation of the functional state of the coronary circulation. METHODS: We studied 42 patients with severe hypercholesterolemia and extensive coronary artery disease who were randomized to diet and simvastatin with or without biweekly LDL apheresis. Regional myocardial perfusion was assessed by digital subtraction angiography with videodensitometric calculation of hyperemic mean transit time (HMTT) of contrast medium at baseline and after 2 years of therapy. RESULTS: Low density lipoprotein cholesterol decreased by 63% (to 3.0 mmol/liter) in the LDL apheresis group and by 47% (to 4.1 mmol/liter) in the medication group. Paired HMTT measurements were assessed in 43 regions in the LDL apheresis group and 35 regions in the medication group. In the LDL apheresis group, regional HMTT decreased over 2 years from 3.35 +/- 1.18 (mean +/- SD) to 2.87 +/- 0.82 s (-14%, p = 0.001), whereas no change in the medication group was observed: 2.95 +/- 1.06 to 2.96 +/- 0.90 s (p = NS). In the patient-based comparison, the mean change in HMTT was -0.45 s (-14%, p = 0.01) in the LDL apheresis group and -0.05 s (-2%, p = NS) in the medication group, respectively. Only exercise-induced ischemia improved in the LDL apheresis group. CONCLUSIONS: Biweekly LDL apheresis plus simvastatin decreased time-averaged LDL cholesterol levels by an additional 31% (1.1 mmol/liter) compared with medication alone. After 2 years of therapy, regional myocardial perfusion improved in the LDL apheresis group and remained unchanged in the medication group. Thus, aggressive reduction of LDL cholesterol has a favorable effect on regional myocardial perfusion and alleviates ischemia.     

Decreased resistance against in vitro oxidation of LDL from patients with familial defective apolipoprotein B-100

Familial defective apolipoprotein B-100 (FDB) is caused by a mutation in the receptor-binding region of apolipoprotein B-100, the structural protein of the low-density lipoprotein (LDL) particle. We studied the effect of this mutation on the composition and susceptibility to oxidative modification of LDL in patients with FDB. Twenty Dutch carriers of the mutation identified in a family study were matched with 20 unaffected siblings of similar age and sex. The mean concentration of LDL cholesterol was 5.19 +/- 0.94 versus 2.9 +/- 0.5 mmol/L in control subjects (P < .0001). Measurement of LDL oxidizability in vitro by continuously monitoring conjugated-diene absorbance showed that LDL from FDB patients was significantly less resistant against oxidation (lag time, 90 +/- 22 minutes versus 108 +/- 21 minutes; P < .05); furthermore, the maximal rate of diene production and total diene production were also significantly increased. Analysis of the chemical composition revealed an increased relative content of cholesteryl esters and reduced content of protein in the LDL of FDB patients (cholesterol-to-protein ratio, 1.54 +/- 0.24 versus 1.25 +/- 0.23; P < .01). The relative amount of arachidonic acid in LDL was increased and that of stearic acid was decreased. The vitamin E (alpha-tocopherol) content per gram of LDL protein was similar to that in control subjects. The relative amount of cholesteryl esters and protein in LDL as well as the fatty acid composition were significantly correlated with LDL oxidizability. Thus, compositional factors in LDL resulting in increased susceptibility to oxidative modification may contribute to the increased risk of premature vascular disease in FDB.