Role of cholesterol in regulating apolipoprotein B secretion by the liver

The review examines the evidence that the supply of cholesterol available for incorporation into nascent lipoprotein particles exerts a regulatory influence on apolipoprotein (apo) B secretion by the liver. Support for this hypothesis comes both from in vitro experiments and from recent observations in normal subjects and patients with dyslipidemia associated with familial hypercholesterolemia, obesity, noninsulin dependent diabetes mellitus, growth hormone deficiency and cholesteryl ester storage disease. The findings do not negate a role for triglyceride synthesis in determining apoB secretion in very low density lipoprotein, but the inhibitory effects on the latter process of pharmacological blockade of cholesterol synthesis or esterification suggest that it is conditional upon an adequate supply of cholesteryl ester.     

Silicon carbide-toughened zirconia ceramics

Tetragonal zirconia polycrystalline (TZP) ceramics containing SiC reinforcement in the form of fine particles (nano-scale), particles (micro-scale), whiskers and platelets were synthesized by hot-pressing. The effects of morphology and grain size of SiC reinforcement on the strength and fracture toughness at room temperature were investigated. The addition of SiC (in whatever form) caused decreases in strength and toughness at room temperature with the exception of whisker-reinforced materials. Toughness fell off with increasing temperature, but nevertheless retained about one-half of the room-temperature value for that particular SiC reinforcement. However, the whisker- and particle-reinforced materials had higher K _lc values at high temperature than fine particle- or platelet-reinforced materials, with values in excess of 7 MPa m^1/2 at 1000 °C. The microstructure was examined for SiC whisker-reinforced/TZP materials by TEM and HREM, to examine the nature of the whisker/zirconia interface.     

Performance evaluation of the Golay code pulse compression technique

The Center for NDE, Iowa State University, has developed a laboratory prototype Golay code pulse compression system and tested it on a variety of materials. The performance of the system was evaluated in terms of signal-to-noise ratio enhancement (SNRE), resolution, and computation speed. The system's error sources also were discussed. The Golay code pulse compression was simulated on a computer and demonstrated the effective noise suppression. In addition, an equivalent pulse of the Golay code (delta-like pulse) was derived theoretically using a simple ultrasonic inspection model, which demonstrated its equivalence on the output correlated signal. Overall, the pulse compression technique extended the detection range for a given peak power and considerably reduced the system'swhite noise, hence providing enhanced signal-to-noise ratios (SNRs). An average of 30 dB improvement in SNR was obtained from highly energy-absorbent materials such as rubber, plastics, corks (insulation materials), and thick composites using the Golay codes of up to 512 bits. However, the technique did not effectively reduce coherent scattering noises from the coarse grain boundaries in cast stainless steels, Inconel weld metal, and material lay-ups in thin composites. Furthermore, it was found that, depending upon the system's hardware capabilities, the overall performance could be degraded considerably.     

Permanent neuronal cell loss in the inferior olive of adult rats exposed to alcohol during the brain growth spurt: a stereological investigation

The purpose of this study was to examine whether exposure of rat pups to alcohol postnatally over a period of brain development similar to that of the human 3rd trimester results in a permanent loss of cells in the inferior olivary nucleus. It was hypothesized that a deficit of neurons in the inferior olive, the sole source of climbing fibers, may contribute to the cerebellar dysfunction observed following exposure to alcohol during development. Sprague-Dawley rat pups were artificially reared and administered alcohol over postnatal days 4-9. One artificially reared group received a daily alcohol dose of 4.5 g/kg, administered as a 10.2% solution in 2 of 12 daily feedings (10.2% group). This pattern of alcohol administration resulted in high peak blood alcohol concentrations with near total clearance. The other artificially reared group was fed a diet made isocaloric to the alcohol-containing diet (gastrostomy control group). Pups were allowed to grow to adulthood and killed on postnatal day 115. The total number of neurons in the inferior olivary nucleus was estimated using unbiased stereological methods. Exposure to alcohol resulted in a significant deficit in the number of neurons in the inferior olive at 115 days of age. The total number of neurons in the alcohol-exposed group was 40.12 +/- 8.7 x 10(3), compared with 53.37 +/- 3.7 x 10(3) in the artificially reared controls. These results indicate that there is a permanent deficit of neurons in the inferior olive after postnatal exposure to alcohol.(ABSTRACT TRUNCATED AT 250 WORDS)     

Knowledge, attitude and behavior among patients with Chlamydia. Perspectives for prevention

Patients with chlamydial infections (Ct) attending the outpatient Venereal Disease Clinic of Copenhagen from July 1-November 30 1995 were asked to fill in a questionnaire focusing upon knowledge, attitude and behaviour related to sexually transmitted diseases (STDs) in order to strengthen the future prevention of Ct. The questionnaire was answered by 37 men and 35 women with a median age of 27 and 21 years and a median number of three and two sexual partners within the last six months, respectively. Half of the patients had previously had an STD, and 92% had been tested for HIV, of whom one homosexual man was known HIV-positive. Notification about exposure from a partner was the reason for attending for 24%. All but one were in favour of partner notification, but only 6% wanted provider referral. During last intercourse condoms had neither been used with a steady partner by 75% especially by the young and women, who thought themselves safe, nor with a casual partner by 52% especially among the young and men, mainly because of thoughtlessness or perception of low risk. Before the actual STD diagnosis only 49% were able to name one symptom and 35% one complication related to Ct. A majority (79%) stated, that fear of catching another Ct would lead to better protection, and 70% found that more information would have a preventive effect. Future Ct prevention programs in Denmark should include intensified chlamydial screening and partner notification together with centrally produced mass media information supplemented by individual counselling.     

Treatment with alendronate prevents fractures in women at highest risk: results from the Fracture Intervention Trial

BACKGROUND: The efficacy of antiresorptive therapy in preventing fractures in women at highest fracture risk, such as very elderly women or those with severe osteoporosis, is uncertain. PARTICIPANTS AND METHODS: Using data from a double-blind, randomized, placebo-controlled clinical trial that enrolled 2027 postmenopausal women aged 55 to 81 years with low femoral neck bone mineral density (BMD) and existing vertebral fractures, we examined the consistency of the effect of treatment with alendronate sodium in preventing fractures within a priori-specified risk subgroups defined at baseline by age, bone density, number of preexisting vertebral fractures, and history of postmenopausal fracture. The women were randomized to oral administration of alendronate or placebo and followed up for an average of 2.9 years. The initial dose of alendronate sodium was 5 mg/d; the dosage was increased from 5 to 10 mg/d at 24 months. New vertebral fractures, the primary end point of this arm of the trial, were defined by morphometry as a decrease of 20% and at least 4 mm in any vertebral height between baseline and a follow-up radiograph at 36 months. Incident clinical fractures, the secondary end point, included nonspine and clinical (symptomatic) vertebral fractures. All clinical fractures were confirmed with x-ray film reports or, in the case of clinical vertebral fractures, x-ray films. RESULTS: Overall, there was a 47% significant reduction in risk of new vertebral fractures in the alendronate group compared with the placebo group. The reduction in risk of new vertebral fracture was consistent across fracture risk categories including age (relative risk [RR], 0.49 in women < 75 years compared with 0.62 in those > or = 75 years), BMD (RR, 0.54 in women with a femoral neck BMD < 0.59 g/cm2 [median] compared with 0.53 in those with a BMD > or = 0.59 g/cm2), and number of preexisting vertebral fractures (RR, 0.58 in women with 1 vertebral fracture compared with 0.52 in those with > or = 2). The overall significant 28% reduction in risk of incident clinical fractures in the alendronate group compared with the placebo group was also observed within these subgroups. Compared with the number of lower-risk women, a similar or smaller number of high-risk women needed to be treated to prevent 1 fracture. For example, 8 women aged 75 years or older compared with 9 women younger than 75 years, or 4 women with 2 or more existing vertebral fractures compared with 16 women with 1 existing vertebral fracture, needed to be treated with alendronate for 5 years to prevent 1 new vertebral fracture. CONCLUSIONS: Alendronate effectively reduces fracture risk in postmenopausal women with vertebral fractures and low BMD, including those women at highest risk because of advanced age or severe osteoporosis. Since the risk reductions observed with alendronate treatment were consistent within fracture risk categories, more fractures were prevented by treating women at highest risk.