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Biomedical subjects

J T Bennett

Publications and source records attributed to J T Bennett.

30 records · Page 2Linked to original sources
PubMed1978

Modification of pulmonary vascular responses to arachidonic acid by alterations in physiologic state.

The effects of bolus injections of arachidonic acid and prostaglandins (PG) E2 and F2a on the pulmonary vascular bed were compared under resting conditions and after alteration in the physiologic state of the lung. Studies were carried out in the vascularly isolated lung lobe of the intact, anesthetized dog under conditions of controlled blood flow. Arachidonic acid, PGE2 and PGF2a increased pulmonary vascular resistance by constricting intrapulmonary veins and arteries in a dose-related manner, as did an analog of the endoperoxide, PGH2, whereas PGI2 dilated the pulmonary vascular bed. The response to arachidonate was associated with a 2- to 3-fold increase in levels of PGE- and PGF-like substances in pulmonary venous blood and was blocked by indomethacin. The effects of arachidonic acid, but not the PGs, were greatly enhanced during perfusion with either dextran or saline and the enhanced response in saline was associated with a 15 to 20-fold increase in levels of PG-like substances in the pulmonary effluent. Responses to arachidonate were not dependent upon the presence of formed elements in blood but were related to perfusate protein concentration. Alveolar hypoxia decreased responses to the precursor while those to PGE2 and PGF2a were enhanced. Responses to the PGs, but not those to arachidonate, were affected by changes in blood pH. Sublethal doses of Escherichic coli endotoxin increased the response to arachidonic acid, but not those to PGE2 and PGF2a. Results of the present study indicate that the effects of bolus injection of arachidonic acid on the pulmonary vascular bed are due mainly to formation of constrictor metabolites which may overshadow the actions of any dilator (PGI2) formed and suggest that metabolism of the precursor is altered by changes in physiologic state.

Animals↗
PubMedDate not supplied

Epidemiological perspective on prophylactic pinning in patients with unilateral slipped capital femoral epiphysis.

The purpose of this review was to determine whether the literature supports in situ prophylactic pinning of the hip contralateral to a hip with a slipped capital femoral epiphysis (SCFE). Three hundred twenty-five articles on SCFE between 1931 and 1998 were reviewed. Two hundred six studies were used to establish normative data. Patients with a unilateral SCFE were 2,335 times more likely to develop a SCFE in the contralateral hip when compared to children in the general population experiencing an initial SCFE. Because a majority of these sequential SCFEs were detected and treated early, we concluded that close follow-up and not prophylactic pinning was most supported by the literature.

Bone Nails↗
PubMedDate not supplied

Rotational osteotomy of the distal tibia and fibula.

A surgical technique for distal transverse osteotomy of the tibia and fibula to correct torsional malalignment of the leg is described. Thirty-two derotation osteotomies have been performed on 19 patients, whose average age at the time of surgery was 12 years; average follow-up was 2 years. Average torsional change following surgery was 38 degrees. Ninety-four percent of the patients available for follow-up (16 or 17) had a successful outcome. The two small incisions required in this procedure are cosmetically acceptable, and the location of the osteotomy in metaphyseal bone provides stability. We conclude that this osteotomy is a simple, safe, and effective procedure for correction of torsional malalignment in carefully selected patients.

Adolescent↗
PubMedDate not supplied

Association of bone mineral density and pediatric fractures.

Bone mineral density in the lumbar spine and the left femoral neck was measured for a group of 17 children, 3-14 years of age, who had sustained traumatic fractures. Children with any signs of metabolic bone disease were excluded from the study. Identical measurements were made on an age- and sex-matched control population using dual photon absorptiometry. Analysis of bone mineral measurements revealed that there were no statistically significant differences between the lumbar and femoral neck densities of the two groups. The results indicate that reduced bone density is unlikely to play a significant role in acute traumatic pediatric fractures.

Adolescent↗
PubMedDate not supplied

Effects of anticonvulsant drug therapy on bone mineral density in a pediatric population.

Twenty epileptic outpatients, aged 5-20 years and taking either phenobarbital or phenytoin for anticonvulsant therapy, were evaluated for femoral neck area bone mineral content and bone mineral density using dual photon absorptiometry. Duration of treatment averaged 51.4 months (range, 9-124 months). A group of 20 normal children who were matched for age, sex, and race served as controls. There were no statistically significant differences between the femoral neck area bone mineral densities of the epileptic patients as compared to the controls. There were also no correlations between duration of anticonvulsant therapy and bone mineral density, nor any differences in bone mineral density values when comparing epileptic patients taking phenobarbital with those patients taking phenytoin.

Adolescent↗
PubMedDate not supplied

Stickler syndrome.

Stickler syndrome is an autosomal-dominant disorder of connective tissue characterized by skeletal, orofacial, and ocular abnormalities. The most common specific roentgenographic findings include coxa valga and widening of the femoral neck. Acetabular protrusio, chondrolysis, avascular necrosis, and vertebral changes have also been described. Premature arthritic changes are to be expected. Congenital myopia and micrognathia are the most common nonskeletal findings. This syndrome should be considered when patients have unexplained coxa valga, especially with concomitant acetabular protrusio.

Adolescent↗
PubMedDate not supplied

Femoral neck and lumbar spine bone mineral densities in a normal population 3-20 years of age.

Dual-photon absorptiometry (DPA) with a 153gadolinium radionuclide source was used to measure bone mineral in the lumbar spine of 109 subjects and the femoral neck of 100 subjects 3-20 years of age. From the scan data collected, multiple linear regression models were developed to predict the measured bone mineral density values as a function of age, height, and weight; male and female data were evaluated separately. From the table of predicted values, a particular subject's bone mineral measurements can be readily compared with that of normal subjects in the same way "growth charts" are commonly used to assess development.

Absorptiometry, Photon↗
PubMedDate not supplied

Lumbar spine and femoral neck bone mineral density in idiopathic scoliosis: a follow-up study.

A follow-up study of the bone mineral densities (BMD) of 22 female subjects with idiopathic scoliosis was performed using dual-photon absorptiometry at an average follow-up period of 30.8 months. Compared to the initial scans, statistically significant increases in lumbar spine and femoral neck BMD were observed. When compared to normal subjects, approximately half of the scoliotic subjects were markedly osteoporotic, having BMD measurements at least two standard deviations below the expected value. Scoliotic curvature data could not be correlated with the BMD data. The observed osteoporosis is not transient and appears characteristic of idiopathic scoliosis.

Absorptiometry, Photon↗
PubMedDate not supplied

Syringomyelia and developmental scoliosis.

We attempted to characterize the signs and symptoms of patients presenting with scoliosis as a manifestation of occult syringomyelia, and to determine the effect of syrinx decompression on the deformity and neurologic deficits. This study represented 21 patients treated from 1981 through 1991 at the authors' institution. All patients with occult syringomyelia and no other central nervous system lesions underwent decompression of the syrinx, with improvement in neurologic signs and symptoms. Three of the four with scoliosis that were not treated by arthrodesis showed improvement of their deformity at an average follow-up of 35 months. Three of five patients with myelodysplasia, occult syringomyelia, and scoliosis not previously treated with spinal arthrodesis showed stabilization or improvement of their deformity at an average follow-up of 21 months. We conclude that syringomyelia is associated with a high incidence of developmental scoliosis, and that decompression of the syrinx leads to improvement in, or stabilization of, the majority of scoliotic curves, or postpones the need for fusion.

Adolescent↗
PubMedDate not supplied

Tarsal coalition presenting as a pes cavo-varus deformity: report of three cases and review of the literature.

The diagnosis of idiopathic pes cavo-varus is one of exclusion. Typically a neuropathic etiology is sought. Equally well known is the association of rigid flatfoot deformity with calcaneonavicular and subtalar coalition. Less well known is the association of pes cavo-varus with tarsal coalition. This is a report of three patients who presented with cavo-varus deformities without underlying neurologic abnormalities, one with a calcaneonavicular coalition and two with subtalar coalitions, the latter an entity not previously described in association with pes cavo-varus, to our knowledge.

Adolescent↗