Comparison of bone and total alkaline phosphatase and bone mineral density in postmenopausal osteoporotic women treated with alendronate.

Alendronate therapy in osteoporotic women decreases bone turnover and increases bone mineral density (BMD). Optimal patient management should include verification that each patient is responding to therapy. Markers of bone turnover and BMD have both been proposed for this purpose. We have investigated changes resulting from alendronate therapy with an enzyme immunoassay for bone alkaline phosphatase (BAP) and compared it with total alkaline phosphatase (TAP) and BMD of the lumbar spine, hip, and total body. Subjects were drawn from a multicenter randomized, placebo-controlled trial of alendronate in postmenopausal women with osteoporosis. BAP and TAP levels were measured at baseline and following 3, 6 and 12 months of therapy with either placebo (n = 180) or alendronate 10 mg/day (n = 134). All subjects also received 500 mg/day supplemental calcium. BMD was measured at baseline and following 3, 6, 12, 18, 24 and 36 months of therapy. To compare BAP, TAP and BMD at each site for identifying women that experienced a skeletal effect of alendronate, we calculated least significant change (LSC) values from the long-term intraindividual variability in each placebo-treated woman. Median levels of BAP decreased by 34%, 44% and 43% at 3, 6 and 12 months, respectively, in alendronate-treated women (p < 0.0001 compared with baseline and with placebo). These changes were significantly greater (p < 0.0001) than changes observed for TAP. Following 6 months of alendronate therapy, 90% of the women had experienced a decrease in BAP exceeding the LSC compared with only 71% for TAP. The greatest number of women similarly identified with BMD at any site (i.e. a gain in BMD exceeding the LSC) was 81% for spinal BMD at 36 months. All other sites were less than 70% at 36 months. Short-term changes in BAP and TAP were modestly associated with subsequent changes in BMD at all sites (Spearman's rho -0.22 to -0.52, p < 0.05). Compared with TAP and BMD, BAP testing rapidly and sensitively identified skeletal effects of alendronate thus enabling appropriate drug monitoring of osteoporotic women. Though BAP and TAP changes were modestly predictive of BMD changes, the value of the bone marker tests is their ability to detect rapidly a skeletal effect of therapy.

Selective effects of preeclamptic sera on human endothelial cell procoagulant protein expression.

Current concepts of preeclampsia suggest that dysfunction of maternal vascular endothelium in vivo is a central pathogenetic feature of this syndrome. This hypothesis is suggested by the activation of the coagulation cascade associated with preeclampsia and evidence for a role of endothelium in maintaining thromboresistance. Previous in vitro studies with monolayers of human umbilical vein endothelial cells demonstrated direct cytotoxic effects of sera from preeclamptic parturients. In the current studies, we have examined the in vitro expression of three procoagulant protein activities regulated by endothelial cells: cellular fibronectin, an important mediator of platelet aggregation known to be elevated in preeclamptic women in vivo; tissue factor, the most potent endogenous procoagulant activity; and von Willebrand factor, a major component of coagulation factor VIII. Monolayer cultures of human umbilical vein endothelial cells were incubated with pregnancy sera for 24 hours before these proteins and activities were quantified. Exposure of identical endothelial cell cultures to predelivery preeclamptic sera caused significantly greater release of cellular fibronectin than postdelivery preeclamptic or predelivery or postdelivery normal pregnancy sera (p less than 0.05). However, neither tissue factor activity nor von Willebrand factor expression appeared to be increased preferentially by preeclamptic sera. The data indicate that sera from women with preeclampsia induce a selective, but not a generalized, activation of endothelial cell procoagulant protein production.

High plasma cellular fibronectin levels correlate with biochemical and clinical features of preeclampsia but cannot be attributed to hypertension alone.

Current concepts of the pathogenesis of preeclampsia involve the generalized dysfunction of maternal vascular endothelial cells. We measured the endothelial isoform of fibronectin as a marker of endothelial cell injury throughout pregnancy in a prospective, case-control study. Nineteen women met strict criteria for the diagnosis of preeclampsia. Nineteen normal pregnant women, and 19 women with gestational hypertension but without other stigmata of preeclampsia (transient hypertension) were selected from the same cohort and matched according to race, age, nulliparity, and gestational age at delivery. Plasma levels of cellular fibronectin were significantly elevated in women meeting strict clinical and biochemical criteria for preeclampsia but not in women with normal pregnancies or transient hypertension. Moderate but significant elevations in mean levels were found in the second trimester in women destined to have preeclampsia, as compared with matched normal and transient hypertension groups (p less than 0.05). The results indicate that elevated plasma levels of cellular fibronectin are not simply the result of increased blood pressure but reflect a maternal insult specific to the syndrome of preeclampsia. Elevation of the mean concentration during the midtrimester is consistent with the hypothesis that endothelial cell injury is a specific lesion that occurs early in the course of preeclampsia, before clinical signs and symptoms.

Professional ice hockey players: physiologic, anthropometric, and musculoskeletal characteristics.

Twenty-seven players from a National Hockey League (NHL) team were evaluated for maximal aerobic power, body composition, and muscle strength and flexibility upon reporting to training camp. Aerobic power was determined with a maximal treadmill exercise test. Body composition was determined by underwater weighing. Muscle strength of the internal and external shoulder rotator muscles and the knee flexors and extensors were determined isokinetically at 30 degrees/sec. Strength of the hip adductors was determined isometrically. The average (+/- standard error) maximal oxygen consumption (VO2max) for all players was 53.4 +/- 0.8 ml x kg-1 x min-1. When players were grouped by their usual playing positions (Goalies = G, n = 4; Forwards = F, n = 15; and Defensemen = D, n = 8) there were no differences in VO2 max, resting or maximal heart rate, and exercise test duration. Although G (77.7 +/- 3.2 kg) were significantly lighter than D (88.5 +/- 1.9 kg) and F (86.1 +/- 1.9 kg), there were no significant differences between player positions in height or percentage of body fat (9.2 +/- 0.9%). Measures of absolute muscle strength and muscle strength adjusted for body weight were similar for G, F, and D. Goalies, however, had significantly more flexibility in the hip and groin musculature than F and D. Although team averages for muscle strength and flexibility were normal and symmetric, ten players (37%) exhibited significant musculoskeletal strength and flexibility deficits.

Skeletal muscle creatine kinase MB alterations in women marathon runners.

Total creatine kinase (CK) and CK MB activities were determined in gastrocnemius muscle and serum obtained from 14 female marathon runners. The level of CK MB in muscle increased significantly (p less than 0.05) after chronic exercise training from 5.3% to 10.5% of the total CK activity, but not after acute exercise (post-marathon 8.9%). No significant differences in total CK activities were detected. However, the total CK activity in the muscles were significantly (p less than 0.05) less than those previously reported from the muscle of men runners (1800 U/g, 3000 U/g respectively). No significant correlation existed between fiber type and muscle CK MB activity. Additionally, trace amounts of mitochondrial CK and CK BB were present in muscle homogenates. A significant correlation was observed in the increase in mean serum total CK (597 UL-1) and CK MB (23 UL-1) activities 24 h after the race (r = 0.97, p less than 0.05). These results suggest that gastrocnemius muscle in women adapts to training with increased CK MB activities and imply that skeletal muscle is the major source of elevated serum CK MB activities in women marathon runners.

Conservation of the low density lipoprotein receptor-binding domain of apoprotein B. Demonstration by a new monoclonal antibody, MB47.

The fact that low density lipoprotein (LDL) from multiple animal species binds to the human LDL receptor suggested that the LDL-receptor binding domain of apoprotein (apo)B must be evolutionarily conserved. To determine if a common receptor domain epitope existed on apo B, we generated a monoclonal antibody that was specific for the LDL-receptor domain of apo B. This was accomplished by using a screening procedure that selected for a hybridoma supernatant that could block specific cellular uptake and degradation of LDL. Western blots showed that this antibody, termed MB47, was specific for apo B-100. Fluid phase assays indicated a high binding affinity (Ka = 4 X 10(9) M-1) and demonstrated that all human LDL particles expressed the MB47 epitope. Scatchard analysis indicated that a maximum of one MB47 molecule bound to each LDL particle. In solid phase assays, antibody MB47 bound to plasma or LDL of multiple mammalian species, including guinea pig, rabbit, pig, dog, cat, seal, whale, bear, and lion, but it did not bind to mouse or rat LDL. In contrast, a rabbit antiserum to LDL and two other anti-apo B monoclonal antibodies, MB3 and MB19, which do not bind to the receptor domain, were specific only for human LDL. LDL from multiple species, including mouse LDL, competed effectively with 125I-human LDL for binding to human fibroblasts. MB47 effectively inhibited uptake and degradation of labeled human, guinea pig, and rabbit LDL by both human and guinea pig fibroblasts. We conclude that antibody MB47 binds to a single receptor domain on LDL and identifies a vital region conserved through mammalian evolution.

Monoclonal antibody MB19 detects genetic polymorphism in human apolipoprotein B.

Using a specific monoclonal antibody (MB19) against human apolipoprotein B (apo B), we have detected a genetic polymorphism in human low density lipoprotein (LDL). MB19 bound to LDL from different individuals in one of three distinct patterns of immunoreactivity: strong, weak, and intermediate. Scatchard analysis revealed that LDLs with strong and with weak binding patterns differed 10-fold in their affinity for MB19, but both bound the same total amount of antibody (about one mole of MB19 per mole of apo B). LDL showing the intermediate binding pattern yielded a curvilinear Scatchard plot that could be resolved into two distinct components with affinities similar to those of LDLs exhibiting only the high- or only the low-affinity binding of MB19. LDL chemical composition was similar for all three MB19 binding patterns, and the polymorphism remained after removal of LDL lipid or carbohydrate. Analysis of plasmas from 77 unrelated individuals indicated that 40% of them bound MB19 with low affinity, 23% with high affinity, and 36% with intermediate or "hybrid" affinity. Family studies showed that the three MB19 binding patterns result from codominant transmission of two common apo B alleles, each coding for an allotype with different affinity for MB19, conditionally designated here MB19(1) (high affinity) and MB19(2) (low affinity).

Psychological effects of exercise: a randomized cross-over trial.

We tested the effect of beginning an exercise program on the mood of sedentary men who were free of psychopathology. Fourteen men were randomly assigned to either an exercise program or a control period for 12 weeks and then switched to the converse condition. The exercise was nonsocial and of moderate intensity. Exercise did not improve anger, tension, confusion, depression, fatigue, vigor, or total mood disturbance more than a control period. We conclude that beginning an exercise program, in itself, produces minimal psychological benefits. We hypothesize that other conditions, e.g. the presence of emotional problems, socialization along with exercise, or a training effect must be present for exercise to produce psychological benefits.

Creatine kinase-MB isoenzyme adaptations in stressed human skeletal muscle of marathon runners.

The creatine kinase (CK) isoenzyme composition was determined in serial gastrocnemius muscle biopsies obtained from 12 male marathon runners. The mean muscle CK-MB composition significantly increased after chronic exercise (training) from 5.3% (pretraining) to 7.7% (premarathon) as well as after acute exercise (postmarathon) to 10.5% of the total CK activity (P less than 0.05). However, no significant differences in total CK activities were detected. Additionally, mitochondrial CK and CK-BB isoenzymes were present in muscle homogenates. A significant correlation was observed in the increase in mean serum total CK (3,322 U/l) and CK-MB (174 U/l) activities 24 h after the race (r = 0.98, P less than 0.05). These results show that gastrocnemius muscle adapts to long-distance training and racing with increased CK-MB activities and imply that skeletal muscle is the major source of elevated serum CK-MB activities in marathon runners.

Failure of caffeine to affect substrate utilization during prolonged running.

Nine sub-3-h male marathoners performed three 45-min monitored treadmill runs at approximately 75% of VO2max during a 2-wk period. The men were assigned in a random, double-blind fashion following the control run to receive either 350 ml of decaffeinated coffee or 350 ml of decaffeinated coffee with 400 mg of caffeine added 1 h before the second run with crossover to the other beverage for the third run. Venous blood was analyzed for free fatty acids, triglycerides, glucose, and lactic acid before beverage consumption and before and after each run. Oxygen consumption (VO2), carbon dioxide production (VCO2), respiratory exchange ratio (R), ventilation (VE), and perceived exertion were measured at 15, 30, and 45 min of each run. Of the blood parameters, free fatty acid and lactic acid concentration increased following caffeine ingestion. There was no difference in VO2, VCO2, or R between the three runs. Perceived exertion showed a significant decrease (P less than 0.05) at each time point in caffeine added and decaffeinated compared to control. Triglycerides, glucose, and lactic acid increased similarly in all three runs. In these well-trained marathoners, although plasma free fatty acids were elevated significantly prior to exercise after caffeine ingestion, there was no indirect evidence of altered substrate utilization during subsequent treadmill running.