A model of the Drosophila melanogaster glycerol-3-phosphate oxidase-encoding gene

We have sequenced the Drosophila melanogaster gene encoding the mitochondrial (mt) enzyme glycerol-3-phosphate oxidase (GPO; EC 1.1.99.5) that is involved in flight and alcohol metabolism. Available data suggests a simple model for this gene that includes four exons. Exon I contains a mt import signal, exon II, a transmembrane segment and an FAD-binding site, and exon IV, an iron-sulfur centre.

EVA design: lessons learned

Extravehicular Activities (EVAs) are very demanding and specialized space flight activities. There are many aspects to consider in the design of hardware, tools, and procedures to be used on an EVA mission. To help minimize costs and optimize the EVA productivity, experience shows that astronauts should become involved early in the design process.

Correlated evolution of the cis-acting regulatory elements and developmental expression of the Drosophila Gld gene in seven species from the subgroup melanogaster

The tissue-specific expression patterns of glucose dehydrogenase (GLD) exhibit a high degree of interspecific variation in the adult reproductive tract among the species in the genus Drosophila. We chose to focus on the evolution of GLD expression and the evolution of the Gld promoter in seven closely related species in the melanogaster subgroup as a means of elucidating the relationship of changes in cis-acting regulatory elements in the Gld promoter region with changes in tissue-specific expression. Although little variation in tissue-specific patterns of GLD was found in nonreproductive tissues during development, a surprisingly high level of variation was observed in the expression of GLD in both developing and mature reproductive organs. In some cases this variation is correlated with changes in sequence elements in the Gld promoter which were previously shown to direct tissue-specific expression in the reproductive tract. In particular D. teissieri adult males do not express GLD in their ejaculatory ducts, atypical of the melanogaster subgroup species. The Gld promoter region of D. teissieri specifically lacks all three of the TTAGA regulatory elements present in D. melanogaster. The TTAGA elements were previously shown to direct reporter gene expression to the ejaculatory duct. Together these data suggest the absence or presence of the TTAGA elements may be responsible for variation in the absence or presence of GLD in the ejaculatory duct among species.

Altered brain development in Turner's syndrome: an event-related potential study

We compared event-related brain potentials (ERPs) and reaction time (RT) measures from untreated young (prepubertal and peripubertal; ages 9 to 14) and old (postpubertal; ages 15 to 20) Turner's syndrome (TS) subjects with those from normal age-matched controls. Comparisons among groups permitted the assessment of the relative roles of congenital and maturational brain alterations as possible bases of the cognitive deficits in TS. All subjects were presented with series of auditory stimuli, and they either counted one of the two stimuli or made rapid discriminative button presses to both. The results indicated that, whereas the ERPs in young TS females were essentially the same as those in their age-matched controls, the ERPs in old TS females more closely resembled those in both young groups than those in their age-matched controls. Specifically, a late (400 to 900 msec) frontal negative slow wave (Nc) in the old TS subjects failed to show the normal maturational course in which the amplitude and duration of this component steadily decreases with age. Except for slightly greater amounts of N1 amplitude in the young TS group, the latencies, amplitudes, and scalp distributions of the other ERP components (N1, P2, N2, P300) were all the same at all ages in the TS subjects and their controls. Behaviorally, both TS groups had longer RTs than their controls but, consistent with the ERP results, they did not make more errors.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurocognitive function and brain imaging in Turner syndrome--preliminary results

Girls with Turner syndrome were investigated in order to determine the anatomical differences in their brains compared with those of normal age-matched female controls, and to relate these differences to deficits in neurocognitive function with a view to understanding the abnormal brain development in Turner syndrome. During the 2-year study period, it is planned to evaluate 50 girls with Turner syndrome and 50 age-matched controls. A wide range of authentic neurocognitive tests will be applied to establish the neurocognitive profile, and brain anatomy will be studied by magnetic resonance imaging (MRI). Ten patients with Turner syndrome have been evaluated by neurocognitive testing to date, and 8 girls with Turner syndrome and 13 controls have had MRI scans performed. There is preliminary evidence of both specific and generalized processes affecting brain development and cognitive function in Turner syndrome. The evidence of a role for sex hormones in socio-behavioural and cognitive abilities in Turner syndrome is discussed.

Estrogen therapy in Turner's syndrome

Girls with Turner's syndrome are born short, grow slowly, and usually fail to enter puberty spontaneously and to undergo a pubertal growth spurt. The goal of estrogen therapy is to correct estrogen deficiency in a manner that optimizes height potential, permits attainment of normal bone mass, and provides appropriate feminization with minimal risk of adverse effects. The issues to be resolved include the age at which treatment should be begun, the preparation, route of administration, and dosage to be given, the effect on concurrent growth hormone administration, the rate of dose increase during treatment, the timing and nature of progestin administration, and the total duration of treatment. The available data suggest that treatment should be initiated between the ages of 12 and 14 years. The dose-response relationship between growth rate and estrogen dose is biphasic. Optimal growth stimulation for ethinyl estradiol occurs at approximately 100 ng/kg body weight per day, which is below the dose that produces full feminization. Although suboptimal doses of estrogen and growth hormone appear to have additive effects, estrogen causes only a minor increase in the short-term growth response to an optimal dose of growth hormone. The long-term effects of estrogen combined with growth hormone are unknown. In the absence of data concerning the outcome of different dose schedules, we treated for 2 years at 100 ng/kg/day of ethinyl estradiol, then double the dose annually until menstruation, at which time cyclic monthly progestin therapy is added (medroxyprogesterone acetate 10 mg daily from days 16 to 25). The importance of estrogen in maintaining normal bone mass suggests that treatment should be lifelong. Current research in our clinic is assessing the long-term effect on adult height of ultra-low-dose treatment (25 to 50 ng/kg/day of ethinyl estradiol) during the childhood years (ages 5 to 11), alone or in conjunction with supplemental growth hormone.

Toxic epidermal necrolysis associated with flea dips

A 5-y-old intact female Himalayan cat was dipped with an organophosphate-based compound for flea infestation. The animal subsequently died of organophosphate intoxication. Skin lesions present at necropsy were diagnosed microscopically as toxic epidermal necrolysis. A 5-y-old spayed female Corgi dog was dipped with a d-limonene-based compound for flea infestation. The dog subsequently developed a bullous skin disorder which rapidly progressed to severe coalescing necrotizing dermatitis with large areas of skin sloughing. The dog was treated for a tentative diagnosis of toxic epidermal necrolysis with a short course of corticosteroids and extensive supportive care and recovered completely. Flea dip preparations have the potential to induce severe immune-mediated dermatopathies such as toxic epidermal necrolysis.

Spontaneous growth hormone secretion increases during puberty in normal girls and boys

To test the hypothesis that GH secretion increases during puberty, we measured GH levels in samples obtained every 20 min for 24 h from 132 normal children and adolescents. In both girls and boys, GH levels increased during puberty. The increase in mean levels was earlier in girls than boys, was most evident at night, and was due to increased pulse amplitude rather than a change in pulse frequency. The mean nighttime GH level in girls with bone ages (BA) greater than 12 to 14 yr were significantly greater than the mean level in girls with BA less than 8 yr (7.3 +/- 3.0 vs. 3.4 +/- 1.7 micrograms/L; P less than 0.01) and were greatest at breast stage 3 (7.9 +/- 2.5 micrograms/L). GH pulse amplitude increased significantly before pubertal onset in girls and was significantly greater at BA greater than 12 to 14 yr than at BA of 8 yr or less (13.9 +/- 6.0 vs. 7.9 +/- 4.8 micrograms/L; P less than 0.01) and greatest at breast stage 3 (15.0 +/- 6.3 micrograms/L). The pubertal increase in GH secretion was delayed in boys compared to girls, with the lowest mean 24-h GH and mean nighttime GH values in boys with BA greater than 8 to 11 yr. The mean nighttime GH level at BA greater than 11 to 13 yr in boys was significantly greater than that in the boys with BA greater than 8 to 11 yr (5.8 +/- 2.9 vs. 3.5 +/- 2.1 micrograms/L; P less than 0.05) and was greatest at a testicular volume of more than 10 to 15 mL (6.5 +/- 2.0 micrograms/L). The mean nighttime GH pulse amplitude in boys was significantly greater at BA greater than 11 to 13 yr than at BA greater than 8 to 11 yr (13.9 +/- 5.7vs. 7.3 + 2.6 micrograms/L, P less than 0.05) and was greatest at a testicular volume greater than 20 mL (15.8 +/- 12.0 micrograms/L). The mean nighttime GH levels correlated inversely with body mass index in both sexes, although the correlation achieved statistical significance only for the girls, being stronger in breast stage 3 to 5 girls (r = -0.57 P = 0.0007; n = 32) than in stage 1 and 2 girls (r = -0.38; P = 0.03; n = 32). These observations in normal adolescents emphasize the importance of interpreting spontaneous GH levels in short children in relation to normative data appropriate for sex, body mass, and bone age or pubertal stage.

Normal bone density of the wrist and spine and increased wrist fractures in girls with Turner's syndrome

Turner's syndrome is associated with multiple skeletal abnormalities, including osteoporosis. We evaluated the hypothesis that girls with Turner's syndrome may have deficient bone density before the expected age of pubertal onset (9-13 yr) by comparing the bone mineral content of the wrist and lumbar spine in 78 girls with Turner's syndrome (4-13 yr old) and 28 normal prepubertal girls who were matched for age, bone age, body mass index, or height age. The bone mineral content of the wrist and spine was measured by single photon absorptiometry (SPA) and dual photon absorptiometry (DPA), respectively. SPA values for girls with Turner's syndrome vs. normal subjects (4-6.9, 7-9.9, and 10-12.9 yr old) were (mean +/- SD) 0.27 +/- 0.05 vs. 0.36 +/- 0.05, 0.35 +/- 0.06 vs. 0.41 +/- 0.06, and 0.41 +/- 0.05 vs. 0.45 +/- 0.03 g/cm2, respectively. SPA values in the Turner's syndrome girls were decreased compared to those in normal prepubertal girls, matched for age (P less than 0.0001), bone age, (P less than 0.001), and body mass index (BMI; P less than 0.0001), but not for height age. DPA values for girls with Turner's syndrome vs. normal girls in the same age categories were 0.65 +/- 0.06 vs. 0.70 +/- 0.09, 0.77 +/- 0.08 vs. 0.79 +/- 0.09, and 0.83 +/- 0.12 vs. 0.78 +/- 0.07 g/cm2. DPA values in Turner's syndrome girls (as a group) were decreased compared to those in normal prepubertal girls matched for age (P less than 0.05) and BMI (P less than 0.02), but not for bone age or height age. The annual incidence rate of wrist fractures in Turner's syndrome girls (9.1 of 1000) was significantly increased compared to the reported annual incidence rate in normal children (3.5 of 1000; P less than 0.003). We conclude that prepubertal-aged girls with Turner's syndrome (less than 13 yr old) have normal bone density for height age, but significantly decreased bone density of the wrist for chronological age, bone age, and BMI. They also have significantly more wrist fractures than normal girls, but it is not clear that this is related to their bone density.

Solitary polyclonal autonomous thyroid nodule: a rare cause of childhood hyperthyroidism

Solitary autonomous thyroid tumors are an unusual cause of hyperthyroidism, particularly in childhood. We describe the youngest individual so far reported with this condition, a 22 month child with a large hyperfunctioning thyroid nodule who became overtly hyperthyroid after iodinated contrast administration. The histology of the nodule was compatible with follicular cell hyperplasia. These tumors are often called toxic adenomas, although there is no solid evidence that they are true neoplasms. We examined the clonal composition of the child's thyroid tumor by X-chromosome inactivation analysis, taking advantage of a polymorphism in the X-chromosome gene phosphoglycerate kinase. The tumor consisted of an even mixture of cells containing activated paternal and maternal PGK alleles, indicating that the tumor was polyclonal. Furthermore, the nodule had no structural rearrangements or activating point mutations of ras oncogenes, which are found in up to 50% of solitary monoclonal follicular adenomas. Solitary hot nodules may at least in some cases be secondary to hyperplasia, and not to clonal expansion of an abnormal, mutated cell. This may also explain the relatively low frequency of malignant transformation observed in hyperfunctioning thyroid tumors.

Micro-spatial population differentiation in activity of glycerol-3-phosphate oxidase (GPO) from mitochondria of Drosophila melanogaster

Replicate mass-bred laboratory populations of D. melanogaster were derived from females collected in the Tahbilk winery cellar and from females collected outside but from within two kilometers of the cellar. When mitochondrial extracts from larvae were assayed for specific activity of glycerol-3-phosphate oxidase the cellar populations had levels only 50% of those from the outside area, confirming an earlier report of such a difference among isofemale lines derived from these same areas. This micro-spatial differentiation occurred when larvae were raised on a medium supplemented with both sucrose (5% w/v) and ethanol (4% v/v), known to effect high GPO activity, but was not detected when the larvae were raised on unsupplemented medium. A heritable basis for larval GPO activity variation was confirmed in a set of 32 isogenic second chromosome substitution lines and measured in a subset of 4 of these lines about 25 generations later. A reciprocal cross using two isogenic substitution lines with the highest and lowest activities suggested the difference was attributable to genes acting additively and that there were no maternal or paternal effects. The detection of a collection site difference in GPO enzyme activity in the isogenic lines suggests that polymorphic variation on the second chromosome is responsible for the differentiation at the winery. Variation in adult GPO activity did not show a dependence on the winery location from where the isogenic lines were derived nor was there an effect of line. Adult GPO activity was significantly higher than that detected in larval tissues and did not show a dependence on the sugar/ethanol level in the growth medium.

Controversial issues in psychodynamic and symptom-focused treatment

The choice between psychodynamic and symptom-focused treatment tends to polarize clinicians. Unfortunately, practitioners often take sides, universally applying one or the other treatment rather than choosing the approach best suited to each patient's needs. Discussion between the adherents of each treatment may generate more heat than light. To facilitate a more objective discussion of this division, the authors describe some of the major differences between the two viewpoints and discuss their implications. Their purpose is not primarily to choose sides or resolve the dilemmas but rather to clarify the issues involved.

The effect of short term treatment with growth hormone and ethinyl estradiol on lower leg growth rate in girls with Turner's syndrome

An important consequence of Turner's syndrome is short stature. We previously reported that the optimal doses of ethinyl estradiol (EE2) and GH for the stimulation of short term growth in such patients were 100 ng/kg.day and 0.15 U/kg (administered sc three times weekly), respectively. The aim of this study was to determine whether the combination of low dose estrogen and GH would stimulate short term growth more than either agent administered alone. Thirty-nine girls with Turner's syndrome (aged 5-15 yr) underwent one to three 6-month cycles, each consisting of a 2-month baseline period, a 2-month treatment period, and a subsequent 2-month washout period. During the first 2 yr of the study, the girls were assigned to receive the three treatments in random order. The treatments were EE2 (100 ng/kg.day, orally), GH (0.15 U/kg, sc, three times weekly), or the combination of EE2 and GH. Subsequently, some of the girls were treated with reduced doses of EE2 (50 ng/kg.day) and GH [0.09 U/kg, three times weekly (tid)] according to the same protocol. Lower leg length was measured every 2 months throughout the study. EE2 increased lower leg growth rate significantly at the dose of 100 ng/kg.day, but not at the dose of 50 ng/kg.day. Similarly, the higher dose of GH (0.15 U/kg, tiw) increased lower leg growth rate significantly, whereas the lower dose (0.09 U/kg, tiw) did not. However, combined treatment with the lower doses of EE2 (50 ng/kg.day) and GH (0.09 U/kg, tiw) stimulated lower leg growth rate significantly and to a similar degree as the higher dose of GH (0.15 U/kg, tiw). This higher dose of GH appeared to cause a maximal increase in lower leg growth rate, which was not further increased by combined administration with the higher dose (100 ng/kg.day) of estrogen. Thus, addition of low dose EE2 to an optimal dose of GH did not cause any apparent increase in short term lower leg growth rate in girls with Turner's syndrome. Whether the long term outcome of GH treatment would be altered by concurrent administration of low dose estrogen will require long term clinical trials.

Memory and awareness in a patient with multiple personality disorder

We studied an individual with multiple personality disorder in whom each of several personalities claimed to have no direct awareness of the others and to be unable to consciously remember the experiences of other personalities. A broad selection of implicit and explicit memory tests was used to determine the extent to which one personality had access to knowledge acquired by another and the circumstances in which that knowledge would be expressed. The implicit assessment of memory was a necessary but not sufficient condition for demonstrating interpersonality access. The degree of compartmentalization of knowledge in this patient depended largely on whether the interpretation of presented information was likely to differ across personalities.

The advantage of measuring stimulated as compared with spontaneous growth hormone levels in the diagnosis of growth hormone deficiency

To clarify the relative usefulness of measuring stimulated as compared with spontaneous growth hormone levels in the diagnosis of growth hormone deficiency, we studied 54 short prepubertal children--23 with growth hormone deficiency identified by stimulation tests and 31 with idiopathic short stature who had normal responses to growth hormone stimulation. Growth hormone levels were measured in plasma samples obtained every 20 minutes for either 12 or 24 hours. The results were compared with those in 46 normal prepubertal children. Children with growth hormone deficiency had significantly lower mean 24-hour growth hormone levels (1.0 microgram per liter; range, 0.5 to 1.8) than normal children (2.8 micrograms per liter; range, 0.8 to 5.8; P less than 0.001). However, the diagnostic usefulness of the spontaneous growth hormone test was inferior to that of the stimulation tests, since it identified only 57 percent of the children with growth hormone deficiency identified by the stimulation tests. In the remaining children with growth hormone deficiency, spontaneous growth hormone levels were within the normal range. Children with idiopathic short stature had a normal mean 24-hour level of growth hormone (3.0 micrograms per liter; range, 1.1 to 6.7). No child in this group had low levels of spontaneous growth hormone secretion. We conclude that the measurement of the spontaneous secretion of growth hormone in prepubertal short children had lower sensitivity and offered no diagnostic advantage over stimulation tests. Our data do not support the routine measurement of spontaneous growth hormone secretion in the diagnosis of growth hormone deficiency.

Systems analysis and guidelines for behavioral scientists in family medicine

A recurrent theme among behavioral scientists is the difficulty of being a nonphysician in a medical setting. Differences in training and in work roles can create misunderstanding between physicians and behavioral scientists; and being a minority in terms of profession can be isolating and demoralizing. To date, analyses have focused on the individual differences between the two groups and not on the context--the larger system--in which the two work. This article examines these systemic problems, particularly problems specific to family medicine. Coping methods which can be used by behavioral scientists are proposed to help them reduce the work stress they experience.

Abnormal growth hormone secretory dynamics in children with familial hypercholesterolemia

Growth hormone secretory dynamics and plasma somatomedin C concentrations were assessed in four prepubertal patients with defects in the low-density lipoprotein (LDL) receptor pathway before and after 2 months of treatment with mevinolin, an HMG-CoA reductase inhibitor that reduces intracellular cholesterol. Pre- and posttreatment mean 24-hour growth hormone levels and pulse amplitude were similar and tended to be higher than in age-matched prepubertal controls. Pre- and posttreatment somatomedin C levels were also similar and lower than in age-matched prepubertal controls. All patients responded to growth hormone provocative testing with a peak response of greater than 7 ng/ml, independent of treatment status. Growth velocity was not significantly altered in any patient following 2 months of treatment with mevinolin, and was within the normal range for age. Thus, children with defects in the LDL receptor pathway express abnormalities in growth hormone secretion and somatomedin C generation comparable to those seen in other chronic diseases. Treatment with mevinolin has no apparent effect on these biochemical abnormalities, suggesting that it may not have long-term effects on growth. Regardless of mevinolin therapy, children with defects in the LDL receptor pathway may manifest a degree of growth retardation and, hence, growth rate and skeletal maturation should be closely monitored.

Research and Social Security policy in the United States

This article is adapted from a paper presented at a conference that investigated the role of policy research in shaping public policy. The conference focused on how studies of economic and social forces and their relationship with public problems and programs affect the decisions of public policymakers. The author contends that research has the potential to inform policy-making in any of its five stages: problem identification, option development, passage of new laws or development of new procedures, implementation, and evaluation. She notes that different players in the policy-making process use research differently, from the senior government official who needs a quick review of what is known relating to a "hot" issue to the interest group lobbyist who wants access to raw data. The article concludes that research can best achieve its potential when (1) it anticipates policymakers' information needs, (2) it is disseminated in an accessible form understandable to nonresearchers, and (3) the policy analyst is willing to engage in the policy process as an advocate for efficiency.

Growth hormone secretory dynamics in children with precocious puberty

We investigated whether an increase in growth hormone secretion contributed to the growth spurt in children with precocious puberty by measuring the 24-hour profile of serum growth hormone in 51 patients with central precocious puberty. Girls with central precocious puberty had significantly greater mean 24-hour levels of growth hormone in comparison with normal prepubertal girls (5.1 +/- 0.5 SEM vs 3.4 +/- 0.3 ng/mL, P less than 0.005). Mean 24-hour growth hormone levels did not differ significantly between boys with central precocious puberty and normal prepubertal boys (4.4 +/- 1.2 vs 3.0 +/- 0.4 ng/mL). Serum somatomedin C levels were significantly correlated with mean 24-hour growth hormone levels in the girls only. Height age advancement (expressed as height age/chronologic age) was significantly correlated with mean 24-hour growth hormone levels in both boys and girls with central precocious puberty. We conclude that spontaneous 24-hour growth hormone secretion in girls with precocious puberty is greater than that of normal prepubertal girls and may mediate at least in part the increased growth rate in this disorder.

Effect of low doses of estradiol on 6-month growth rates and predicted height in patients with Turner syndrome

We randomly assigned 16 girls with Turner syndrome, age 5 to 15 years, to receive treatment with 100 ng/kg/day ethinyl estradiol or placebo for 6 months, with crossover after a 2-month interim period. We assessed growth by measurement of the 4-week lower leg growth rate and by height velocity. Bone age was determined at the beginning and end of treatment. Growth rate during ethinyl estradiol treatment was approximately 70% greater than during placebo (P less than 0.001), without any bone age advancement relative to that with placebo. The change in predicted height was significantly greater after 6 months treatment with ethinyl estradiol than after treatment with placebo (mean +/- SEM, +0.35 +/- 0.38 cm vs. -0.85 +/- 0.32 cm, P less than 0.03). Breast budding occurred in six patients. We conclude that it may be feasible to begin low-dose estrogen therapy to promote growth at an earlier age than would be conventionally used to induce pubertal development. These data are still relatively short term, however; until long-term data are available, it would be premature to make definitive recommendations regarding the dose and timing of estrogen treatment in Turner syndrome.

Growth response relationship between growth hormone dose and short term growth in patients with Turner's syndrome

Short stature is a common feature of Turner's syndrome. We studied the dose-response relationship between short term linear growth and GH dose using the lower leg-measuring device. Three doses of GH (0.05, 0.15, and 0.45 U/kg, three times weekly) were given sc for 1-month treatment periods. Lower leg growth rate increased significantly during treatment with the 0.15 and 0.45 U/kg doses [1.8 +/- 0.2 (+/- SEM) and 1.7 +/- 0.3 mm/4 weeks). The higher dose of 0.45 U/kg was no more effective than the 0.15 U/kg dose. Serum somatomedin-C levels increased after treatment with each of the three doses of GH, but did not differ in any of the three dosage groups. We conclude that 0.15 U/kg GH, three times weekly, stimulates short term growth in patients with Turner's syndrome. Longer term studies are required to determine if this increased growth rate is sustained.