Vertebral bone density in children: effect of puberty

To determine changes in bone density during growth, trabecular vertebral density and an index of spinal cortical bone were measured with quantitative computed tomography in 101 children. The children were divided by age into three groups: prepubertal, indeterminate, and pubertal. Compared with prepubertal children, pubertal adolescents had significantly higher trabecular bone density and more compact bone in the spine (P less than .001). After controlling for puberty, vertebral bone density failed to correlate significantly with age, sex, weight, height, surface area, and body mass index. The results indicate that bone density increases markedly during puberty.

Peak trabecular vertebral density: a comparison of adolescent and adult females

To determine when spinal bone density reaches its peak, the trabecular vertebral density was assessed, via quantitative computed tomography, among females from two age groups: (1) adolescents (aged 14-19 years; N = 24); and (2) young adults (aged 25-35 years; n =24). The adolescent girls had a higher mean trabecular vertebral density (P less than 0.01), suggesting that spinal density reaches its peak around the time of cessation of longitudinal growth and epiphyseal closure.

Osteoporosis in cystic fibrosis

To determine if osteoporosis is prevalent among patients with cystic fibrosis, we compared the vertebral bone density measured by quantitative computed tomography in 57 such patients (29 male, 28 female, aged 3 to 21 years) with those of an age-, race-, and sex-matched control group of 57 healthy subjects. Patients with cystic fibrosis had significantly lower bone density (10% lower, p less than 0.001) than in controls. The decrease in bone density in patients with cystic fibrosis was unrelated to age. Shwachman clinical evaluation scores (based on case history, pulmonary physical findings, growth, and x-ray findings) correlated positively with age-standardized bone density values (p less than 0.01). Male patients had substantially lower bone density than did female patients (p less than 0.02), but bone density differences related to gender were not significant when effects of disease severity were controlled for. Decreased bone density was more common in patients with poor nutritional status as determined by anthropometric measurements (p less than 0.05). We conclude that osteoporosis is a frequent complication in children with cystic fibrosis regardless of their age and is more prevalent in patients with greater disease severity.

Reteplase in the treatment of peripheral arterial and venous occlusions: a pilot study

PURPOSE

Reteplase, a truncated mutant of tissue plasminogen activator, has been used successfully in the treatment of acute coronary occlusion, but, heretofore, it has not been investigated in the setting of peripheral vascular occlusion. Reteplase is a potential recombinant thrombolytic agent that may offer an appropriate alternative to currently employed plasminogen activators.

MATERIALS AND METHODS

Over a 6-month period reteplase was used to treat peripheral vascular occlusions at five centers in the United States. The agent was used in peripheral arterial occlusion (n = 26, 70.3%) or venous occlusion (n = 11, 29.7%), in doses ranging from 0.5 to 2.0 U/h, infused directly into the thrombus. A lacing dose (4.3 +/- 0.9 U) was employed in 17 patients (45.9%), and 25 patients (67.6%) received concurrent heparin therapy in a subtherapeutic dose (n = 14, 37.8%) or as full therapeutic anticoagulation (n = 11, 29.7%).

RESULTS

The 26 patients with arterial occlusions received a total dose of reteplase that averaged 20.5 U +/- 5.3 (mean +/- SEM), ranging from 3.5 to 82 U. The duration of infusion was 19.3 hours +/- 2.4 with a range of 0.2-36 hours. Complete dissolution of the occluding thrombus was achieved in 23 patients (88.5%). Hemorrhagic complications developed in eight patients (30.8%) and were major in five patients (19.2%). No patient experienced intracranial bleeding. Although there was no association between the dose regimen and thrombolytic efficacy, bleeding complications appeared to be more frequent as the dose was increased from 0.5 to 2.0 U/h. The 11 patients treated for deep venous thrombi received an average of 32.6 U +/- 7.4 of reteplase, ranging from 6 to 75 U over a mean length of time of 31.1 hours +/- 7.3 (range, 4-84 hours). Complete dissolution of thrombus occurred in eight patients (72.7%). Hemorrhagic complications developed in three patients (27.3%) and one of the episodes was major (9.1%). No patient experienced intracranial hemorrhage.

CONCLUSIONS

Reteplase appears to be an acceptable alternative thrombolytic agent with a satisfactory safety and efficacy profile in the setting of peripheral arterial and venous occlusion. As such, it may provide an attractive alternative for the treatment of peripheral arterial and venous thrombotic occlusions. However, definitive conclusions must await the results of controlled comparisons of reteplase to other thrombolytic agents.

Effect of sex steroids on peak bone density of growing rabbits

To determine the effect of sex hormones on bone density (BD) during growth, longitudinal quantitative computed tomography (QCT) measurements were obtained in growing, castrated New Zealand White rabbits following administration of normal saline, testosterone, or estrogen from 6 wk of age until the time of skeletal maturity. Vertebral QCT densities increased during growth, were highest at the time of epiphyseal closure, and were significantly greater (P less than 0.001) in hormone-treated animals. In vivo QCT measurements in 12 vertebraes correlated strongly (r = 0.92) with percentage of calcium per weight assessed in vitro by neutron activation analysis.

Contemporary treatment of thrombosed hemodialysis grafts

Maintaining hemodialysis grafts remains a difficult problem. Before the early 1990s, graft declotting was usually performed in the surgical suite. Percutaneous declotting has been evolving since the mid-1980s. Initially, a low-dose thrombolytic infusion of streptokinase through a single catheter was used. Crossing catheters with a higher-dose infusion of urokinase was then introduced. This technique was modified with the adjunctive use of pharmacomechanical techniques with the use of compliant balloons and the adjunctive use of heparin. The advent of the "lyse-and-wait" technique provided a simpler and quicker way to declot thrombosed grafts by using urokinase, with similar outcomes. Since the removal of urokinase from the market, multiple mechanical devices have been used with similar success. Recent reports concerning the use of newer-generation thrombolytic agents report similar outcomes, with a reduction in total cost.

May spina bifida result from an X-linked defect in a selective abortion mechanism?

It is suggested that the major genetic factor in determining the birth of children with neural tube defects may be a single X-linked gene. It acts as an X-linked dominant, not by producing neural tube defects, but by enabling the affected fetus to survive selective spontaneous abortion. This mechanism, mediated at the deciduoplacental junction, may be under the control of both maternal and fetal genes. With more mutant alleles, survival would become more likely, reaching a maximum in the homozygous affected female fetus of a homozygous affected mother. The female excess in anancephaly is greater than that in spina bifida because of its prenatal severity, thus requiring relatively more mutant alleles for survival.

Spinal cord transection in utero

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The effect of limping on vertebral bone density: a study of children with tarsal coalition

To determine whether limping is associated with decreased bone mineralization, the trabecular and integral bone densities (BDs) of 18 Caucasian children exhibiting computed tomographic evidence of tarsal coalition (14 boys, 4 girls, aged 9 years, 5 months to 16 years, 3 months) were compared with those of an age- and sex-matched control group. Patients with tarsal coalition had significantly lower trabecular (p less than 0.05) and integral (p less than 0.05) BD than controls. Trabecular spinal density was approximately 17% lower on the average in patients with tarsal coalition. Among the limping patients, neither the duration of symptoms nor bilaterality was associated with decreased BD. The findings suggest that painful tarsal coalition may decrease vertebral bone mass and predispose to spinal osteoporosis.

Methods of ovulation induction

The results of ovulation induction in patients with ovulatory dysfunction were reviewed for a one year period. Eighty-six women were assigned to four groups: secondary amenorrhea, anovulation, oligo-ovulation, and luteal phase defect/short luteal phase (LPD). All patients were monitored with basal body temperature (BBT) graph, postcoital testing, and ultrasonic scanning of ovarian follicles. All patients received therapy with clomiphene citrate (CC) for a minimum of four cycles and 13 patients conceived. Fifty patients were offered additional therapy with human menopausal gonadotropins (HMG-HCG). Seventeen completed a minimum of four cycles, and 13 conceived. The number of CC-treated patients with poor mucus quality in the face of adequate follicular development was 24, or 48%. The overwhelming problem with ovulation induction when CC failed was the large number of patients who dropped out of therapy, 48%. In summary, close monitoring during ovulation induction to confirm ovulation, and assess mucus quality and luteal function allow detection and correction of inadequate response. Induction of ovulation can be highly successful if patients can follow through and complete protocols of therapy.

Vertebral bone density in Scheuermann disease

The densities of the trabecular bone of two or three lumbar vertebral bodies in twenty adolescents, twelve to eighteen years old, who had Scheuermann disease were measured by quantitative computed tomography. These densities were then compared with those for the same vertebrae of twenty age, sex, and race-matched adolescents who were examined by computed tomography because of trauma. The same scanner and phantom were used in all examinations. Both the adolescents who had Scheuermann disease and the control patients were in good health before the quantitative computed-tomography examination and had not been taking any medications. The density of the trabecular bone density in the patients who had Scheuermann disease was not significantly different (p = 0.28) from that in the controls. There also were no significant differences between the patients and the controls with regard to height, weight, surface area, or body-mass index.