Future directions. Collagen-based prostheses for meniscal regeneration

Prosthetic meniscal replacement offers the ability to stabilize the meniscectomized knee and provide prophylaxis against early degenerative arthritis. Since prosthetic meniscal replacement may be performed in the setting of normal articular cartilage, a prosthesis will be required to match the exact joint configuration, induce the same lubricity, produce the same coefficient of friction, and absorb and dampen the same joint forces (without incurring significant creep or abrasion) as does the normal meniscus. This feat is currently beyond the capabilities of artificial materials alone. Alternatively, collagen-based prostheses acting as resorbable regeneration templates offer the possibility of inducing regrowth of new menisci. This paper presents a summary of hypotheses, considerations, and laboratory evidence for the use of collagen-based, resorbable matrices as regeneration templates.     

Cardiovascular reactivity to stress: an examination of familial trends

Mental stress elicits changes in cardiovascular functioning such as increases in blood pressure and heart rate and leads to biochemical changes which may facilitate the development of cardiovascular disease. This study examined the correlations between levels of cardiovascular change seen in healthy fathers and their sons who underwent stress testing (cold pressor test and mental arithmetic). No correlation between fathers' and sons' levels of reactivity were found. Certain personality traits such as hostility and anger directed inward have previously been shown to correlate with both reactivity and presence of arterial disease. In this study, hostility levels and assertiveness levels were measured and were found to correlate modestly with reactivity in the fathers but not in the sons. Sons showed less assertiveness and greater hostility overall; thus, restriction of the range of these variables may limit potential correlations with physiological measures in this group. Finally, although no family trends were observed, several of the adolescents did show extreme changes under stress, suggesting reactivity is a trait which is expressed early in life.     

Effects of Sediment Homogenization on Interstitial Water PCB Geochemistry

Sediment homogenization is a common practice in many contaminated sediment toxicity testing and chemical analysis protocols. A primary goal of sediment homogenization is to reduce inter-replicate variability. In this study, the geochemical effects of sediment homogenization were evaluated by measuring the concentration and distribution of polychlorinated biphenyls (PCBs) in environmentally contaminated marine sediment interstitial waters. Sediment homogenization, prior to isolation of interstitial waters, was found to significantly increase the concentration of PCBs in the dissolved and colloidal phases—generally by a factor of two. Long-term storage (i.e., several months) of sediments following mixing appeared to allow interstitial water distributions of PCBs to return to “normal,” although a storage artifact may also be present. This study indicates that homogenization results in significant changes in the concentration of PCBs in environmentally contaminated sediment interstitial waters. Consequences of these changes on inferences made based on toxicity tests or chemical analyses using homogenized sediments need to be considered and studied further. Received: 12 December 1996/Revised: 24 February 1997     

Early amniocentesis for prenatal cytogenetic evaluation

Early amniocentesis at 11-14 weeks gestation was evaluated in 100 consecutive patients to see how this technique compares with later amniocentesis. There were no complications as a consequence of the procedure or related pregnancy losses of chromosomally normal fetuses. Samples obtained from three (3%) patients showed insufficient cell growth; two of these patients elected a repeat procedure, which yielded a normal karyotype in each case. There were five abnormal karyotypes, one of which was a culture artifact; in the latter case, repeat amniocentesis at 15 weeks yielded a normal result. Of the 95 pregnancies with normal karyotypes, 94 were progressing normally at follow-up, and one patient elected pregnancy termination because of maternal indications. It appears that early amniocentesis may be an attractive alternative to traditional amniocentesis, in that it provides results at an earlier gestational age and may avoid certain disadvantages of chorionic villus sampling.     

Obesity in black adolescent girls: a controlled clinical trial of treatment by diet, behavior modification, and parental support

Recent findings indicate that nearly 50% of black American women are obese and that adolescence is a critical period for the development of their obesity. This study investigated the efficacy of a behavioral weight control program in 36 black female adolescents with a mean age of 14.0 years, weight of 95.0 kg, and height of 163.2 cm. All subjects participated in the same 16-week program but had different levels of parent participation: (1) child alone with no parent participation; (2) mother and child treated in the same session; and (3) mother and child treated in separate but concurrent session. At the end of the 16-week program, children in the three conditions lost 1.6, 3.7, and 3.1 kg, respectively. Differences among conditions were not statistically significant; however, a secondary analysis revealed that the greater the number of sessions attended by mothers, the greater their daughters' weight losses. Weight reduction was associated with significant improvements in body composition, serum total cholesterol concentrations, and psychological status. Results are discussed in terms of the need to improve the maintenance of weight loss in adolescents and to explore possible differences between black and white females in their preferred body types.