Biomedical subjects

D Schoenfeld

Publications and source records attributed to D Schoenfeld.

At least 19 recordsLinked to original sources

PubMed1992

An antispasticity effect of threonine in multiple sclerosis.

To determine whether the naturally occurring amino acid threonine, a potential precursor for glycine biosynthesis in the spinal cord, has an effect on spasticity in multiple sclerosis, 26 ambulatory patients were entered into a randomized crossover trial. Threonine administered at a total daily dose of 7.5 g reduced signs of spasticity on clinical examination, although no symptomatic improvement could be detected by the examining physician or the patient. In contrast to the side effects of sedation and increased motor weakness associated with antispasticity drugs commonly used for the treatment of multiple sclerosis, no side effects or toxic effects of threonine were identified. Levels of threonine were elevated in serum and cerebrospinal fluid during treatment, but glycine levels did not change. Enhancement by threonine of glycinergic postsynaptic inhibition of the motor reflex arc in the spinal cord may represent a non-sedating, nontoxic approach to the management of spasticity in multiple sclerosis.

Adult↗

PubMed1992

Ovulation and menstrual function of adolescent girls with central precocious puberty after therapy with gonadotropin-releasing hormone agonists.

Chronic GmRH agonist (GnRHa) administration has been shown to suppress pituitary-gonadal function in children with central precocious puberty (CPP), but long term data after the reactivation of gonadarche posttherapy are not yet available. This study evaluated the menstrual function of 46 girls with CPP who had been treated for at least 2 yr with GnRHa (deslorelin or histrelin, sc, daily) and were up to 7 yr posttreatment, including 21 postmenarcheal girls who collected weekly overnight urine samples for 12 consecutive weeks to assess rates of ovulation by urinary pregnanediol-3 beta-glucuronide measurements. Menarche occurred at age 12.1 +/- 1.0 yr (mean +/- SD), on the average 1.2 +/- 0.8 yr posttherapy (range, 0.1-4.3 yr). Menstrual cycle lengths became increasingly regular, with cycles of 25- to 35-day duration reported by 41% of the girls in the first year postmenarche and 65% of the girls studied 3 or more years postmenarche. Ovulation was demonstrated in 50% of the girls studied within 1 yr of menarche and in 90% of the girls studied 2 yr or more postmenarche, including 5 girls who reported pregnancies. The development of regular ovulatory menstrual function in these girls with CPP is in accord with previously documented patterns in normal adolescents. While these data provide further evidence supporting the safety of long term GnRHa therapy, continued studies will be necessary to characterize fully the reproductive function in CPP patients through adolescence and adulthood.

Child↗

PubMed1991

Asymptomatic primary hyperparathyroidism.

Of 118 consecutive white patients referred for asymptomatic primary hyperparathyroidism, the diagnosis was clinically confirmed in 100, of whom 85 adults had a serum calcium less than 3.0 mM (12 mg/dl) and no skeletal, rheumatic, or significant neuropsychiatric symptoms, azotemia, or other significant illnesses. Among these 85, 68 had both asymptomatic and medically uncomplicated hyperparathyroidism, whereas 17 had historical, radiographic, or ultrasonic evidence of renal stone disease. The 20% with past or present renal calculi concentrated their urine significantly better than the 68 others (p = 0.05), but these two groups were otherwise not distinguished by the tests we performed, so all 85 patients were analyzed together. Systolic and diastolic blood pressures were normal, but premature osteopenia and/or impaired renal function were present in 29-36% of the patients. Micrometer measurements of metacarpal radiographs and 125I photon absorptiometry at the shaft of the radius revealed cortical osteopenia. Osteopenia was equally significant in the distal radius (cortical plus trabecular bone). These quantitative measurements were superior to routine bone radiography, and ROC analysis showed that 125I absorptiometry at either site was superior (p less than 0.01) to metacarpal cortex measurements for detecting premature osteopenia, which was present in more than a third of these patients. Creatinine clearances (24 h) and maximum urine concentrating capacity (overnight dehydration plus the synthetic vasopressin analog DDAVP) were each significantly reduced, despite all patients' normal BUN and serum creatinine levels. Sequential performance of a 24 h creatinine clearance and a urine concentration test revealed abnormalities in the renal function of 27 of 74 patients (36%), with a specificity of 95% and a higher sensitivity than either test alone (27-29%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1991

Idazoxan treatment in progressive supranuclear palsy.

To confirm the preliminary report that increases in norepinephrine neurotransmission improve motor performance, we administered the investigational drug idazoxan (IDA) to nine patients with progressive supranuclear palsy (PSP) according to a double-blind crossover protocol. There were seven women and two men, whose mean age was 70 years and mean duration of illness 4 years. All had an advanced parkinsonian syndrome, supranuclear ocular motor palsies, and poor responses to dopaminergic drugs. During administration of 40 mg tid of IDA, the total score and the motor subscale score of the United Parkinson's Disease Rating Scale significantly decreased. Features that improved most included mobility, balance, gait, and measures of digital dexterity. There were no significant changes in any measure during placebo administration. Corticobulbar manifestations and eye movements were not significantly improved during treatment. Side effects of IDA included transient hypertension, tachycardia, action tremor, flushing, and sweating, but none was so severe that any patient withdrew from the study. Among the few attempted treatments of PSP, IDA is the first medication shown in a double-blind study to improve aspects of motor function.

Adrenergic alpha-Antagonists↗

PubMed1991

T-lymphocyte changes linked to autoantibodies. Association of insulin autoantibodies with CD4+CD45R+ lymphocyte subpopulation in prediabetic subjects.

The onset of insulin-dependent (type I) diabetes is predictable before hyperglycemia by the presence of islet cell autoantibodies (ICAs) and competitive insulin autoantibodies (CIAAs). CIAA+ICA+ first-degree relatives of individuals with type I diabetes have increased numbers of CD4 cells bearing the CD45R antigen and reciprocal depressions of the CD4 cells bearing the CD29 determinant. In addition, depressed CD4/CD8 ratios are present. In this study, we investigated the correlation between autoantibody levels and T-lymphocyte changes in the prediabetic state. The data demonstrate a clear linear relationship between rising CIAA levels, a marker of disease rate, and rising elevations in the CD4+CD45R+/CD4+CD29+ ratio in 37 CIAA+ICA+ and CIAA+ICA- relatives (r = 0.93). In marked contrast, the degree of CD4/CD8 depression found in individuals with prediabetes or long-term diabetes failed to correlate with either CIAA (r = 0.32) or ICA (r = 0.29) levels. The investigation of T-lymphocyte changes in siblings of individuals with type I diabetes with different stable autoantibody patterns (CIAAs and/or ICAs), and thus varying risks for diabetes, revealed differences in the prediabetic groups. Fifteen CIAA+ICA- relatives with high CIAA levels (greater than 80 nU/ml) had high CD4+CD45R+/CD4+CD29+ ratios (P = 0.03) and depressed CD4/CD8 ratios (P = 0.008). In contrast, CIAA+ICA- relatives with low CIAA levels (39-80 nU/ml), and thus low risk of diabetes, had no alteration in their CD4/CD8 ratio (P = 0.75) or CD4+CD45R+/CD4+CD29+ ratio (P = 0.33). Nineteen CIAA-ICA+ siblings with a predicted intermediate risk for diabetes showed heterogeneity in the presence of T-lymphocyte abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, CD↗

PubMed1991

Osteopenia in women with hypothalamic amenorrhea: a prospective study.

Hypothalamic amenorrhea, a common disorder associated with abnormalities in gonadotropin pulsatility and subsequent estrogen deficiency, is usually transient, and treatment indications are unclear unless fertility is desired. To determine whether this disorder is associated with progressive bone loss, we studied 24 women with primary or secondary amenorrhea related to stress or simple weight loss, compared with 31 normal women of the same age. Amenorrheic women had significantly lower (P = .01) body fat (26.4 +/- 7.3 versus 30.6 +/- 4.7%) and higher (P = .0001) urine free cortisol levels (250 +/- 100 versus 140 +/- 50 nmol/day) than normals. Trabecular bone density in women with hypothalamic amenorrhea as assessed by spinal computed tomography was significantly (P = .001) lower than in normals (140.2 +/- 27.3 versus 175.1 +/- 24.6 mg K2HPO4/mL, respectively). Twenty of the 24 amenorrheic women had initial spinal bone density below the mean in normals, and in eight it was 2 standard deviations or more below the normal mean. Initial bone density correlated negatively with duration of amenorrhea (r = -0.489, P = .02) and positively with serum free testosterone levels (r = 0.517, P = .02). Prospective evaluation showed a decline in spinal bone density in those who were amenorrheic for fewer than 5 years. The slope of change in bone density correlated with initial weight, percent ideal body weight, and percent body fat (R2 = 0.597, P = .0003; R2 = 0.549, P = .0007; and R2 = 0.618, P = .0002, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Tyrosine for depression: a double-blind trial.

We treated 65 outpatients with RDC major depression in a randomized, prospective, double-blind comparison of oral L-tyrosine, 100 mg/kg/day, imipramine, 2.5 mg/kg/day, or placebo for 4 weeks. Tyrosine increased and imipramine decreased 3-methoxy-4-hydroxyphenylglycol (MHPG) excretion significantly, but there was no evidence that tyrosine had antidepressant activity. The only side effect to achieve statistical significance was greater dry mouth with imipramine. MHPG excretion and plasma amino acid concentrations failed to predict or correlate with clinical improvement.

Adult↗

PubMed1990

Issues in the design of drug trials for AIDS.

Although the fundamental principles that drive the design, conduct, and analysis of clinical trials are as applicable to AIDS as to other diseases, there is no question that we have been confronted with unusually difficult challenges in studying therapeutic approaches in this disease area. Treatments are being developed that show great promise, but when investigated further some may be seen to offer no clinical benefit and others may do active harm through toxicity. A group of biostatisticians, meeting in association with the AIDS Clinical Trials Group (ACTG), has discussed and written a report on a number of issues, primarily related to principles of study design, with the goal of stimulating thought on new study designs and the timely implementation of well-designed trials to identify effective treatment strategies for HIV-infected populations. These issues include (1) progression of clinical trials through phases, (2) choices of outcomes, (3) breadth and complexity of clinical trials (eligibility criteria and "low-tech" trials, (4) alternative designs to be used in randomized trials, and (5) the concept of randomized clinical trials as a desirable option, both for patients and for science. The current HIV epidemic makes the requirements of obtaining valid scientific comparisons more important, not less so, but the challenge is to expedite this process.

Acquired Immunodeficiency Syndrome↗

PubMed1989

Phase II trial of spirogermanium and vindesine in malignant glioma.

Fifty-four adults with recurrent malignant glioma were treated on an Eastern Cooperative Oncology Group (ECOG) trial. All had previous radiation therapy, and 70% had previous chemotherapy. They were assigned to either vindesine 3 mg/m2 weekly or spirogermanium 80 mg/m2 three times weekly with escalation to 120 mg/m2. The response was 4% to vindesine, and 8% to spirogermanium. The duration of response was 53 days for a patient who had clinical improvement only, but greater than 151 days and greater than 1066 days for two patients who had achieved a greater than 50% reduction in tumor size by computed tomography (CT). The toxicities were hematologic for vindesine and neurologic for spirogermanium. Neither agent seems to have sufficient efficacy to warrant further trials in previously treated glioma patients.

Adult↗

PubMed1989

Combined antibody and ganciclovir treatment of murine cytomegalovirus-infected normal and immunosuppressed BALB/c mice.

The efficacy of treatment with ganciclovir (DHPG) and antibody activity-containing ascitic fluid (AF) separately and in combination was studied in normal and immunosuppressed BALB/c mice challenged intraperitoneally with a lethal dose (10(6) PFU) of murine cytomegalovirus (CMV). With combination therapy, lower doses of both DHPG and AF were often as effective as a higher dose of either agent given singly. For instance, the survival rate of murine CMV-challenged immunosuppressed mice was doubled when 4 mg of DHPG per kg and a 1:16 dilution of AF were both administered in contrast to when each was used alone. In both groups of animals, combination therapy was shown to be more effective than either therapy individually, even when initiation of therapy was delayed as long as 48 h. Such an approach holds promise for decreasing the expense associated with antibody use and the dose-related toxicity associated with DHPG use while maintaining or possibly increasing the efficacy of prophylaxis and therapy of serious CMV disease in humans.

Animals↗

PubMed1988

Early natural history of regional left ventricular dysfunction after experimental myocardial infarction.

Existing studies provide conflicting information concerning the natural history of regional dysfunction after subacute myocardial infarction. The purpose of this study was to use quantitative computer-assisted two-dimensional echocardiography to define the natural history of abnormal wall motion in a subacute canine infarct model within individual short-axis echocardiographic planes, and in the entire ventricle as well. Serial short-axis echocardiograms were obtained from 10 closed-chest dogs before occlusion and at 0.5, 6, 24, 48, and 72 hours after ligation of the circumflex (six dogs) or left anterior descending (four dogs) coronary artery. The circumferential extent of abnormal wall motion was quantified by two different computer-assisted methods: the first, a derived correlation method, examined wall motion throughout the systolic contraction sequence; the second method examined the fractional radial change in endocardial ray length from end-diastole to end-systole. The study shows that for individual planes there is a slight but not statistically significant increase in the circumferential extent of abnormal wall motion from 0.5 to 72 hours after coronary artery occlusion; however, when the total extent of left ventricular asynergy was used to define a global functional infarct size, we observed a small (3.6% to 5.4%) but significant increase in the circumferential extent of abnormal wall motion.

Analysis of Variance↗

PubMed1988

Neuroendocrine-gonadal axis in men: frequent sampling of LH, FSH, and testosterone.

Previous studies of episodic hormone secretion of the hypothalamic-pituitary-gonadal axis in normal men have produced conflicting results due to examinations of small cohorts of subjects or to limited sampling techniques. We evaluated gonadotropin and testosterone (T) secretory patterns in 20 normal men by sampling blood at 10-min intervals for luteinizing hormone (LH) and follicle-stimulating hormone (FSH). T concentrations were also analyzed at 20-min intervals in 10 subjects. A previously unappreciated spectrum of gonadotropin and T secretory patterns was observed in normal men. Both mean LH concentrations and mean LH pulse amplitudes varied fourfold between individuals. LH interpulse intervals varied from 30 to 480 min (mean 119 +/- 32). Results also suggested a relative refractory period at the level of the hypothalamus or pituitary. In three subjects, a striking nighttime accentuation of LH pulsations was noted. Through use of Fourier analysis, a diurnal variation in LH was observed in the population (P less than 0.02). Mean FSH levels showed marked variation between individual subjects, with discrete pulses rarely observed. No diurnal variation in FSH secretion was noted. Serum T concentrations determined at 6-h intervals ranged from 105 to 1,316 ng/dl between subjects. When T was measured at 20-min intervals, marked intermittent declines in the T concentrations to levels well below the normal range were observed in 3 of 10 subjects. T secretion was found to lag behind LH secretion by approximately 40 min (P less than 0.02).

Adult↗

PubMed1988

Evidence of differential control of FSH and LH secretion by gonadotropin-releasing hormone (GnRH) from the use of a GnRH antagonist.

The differential regulation of immunoactive FSH and LH secretion by endogenous GnRH was studied using a GnRH antagonist, [Ac-D2Nal1,D4FPhe2,DTrp3,DArg6]GnRH (the NAL-ARG antagonist), in normal women in the early follicular phase of the menstrual cycle, and their responses were compared to those in two groups of control women. Pulsatile LH secretion was examined as an index of the completeness of blockade of endogenous GnRH secretion. There was a dose-dependent decrease in both the frequency and amplitude of LH pulses. At the highest dose, LH pulses were completely abolished within 20 min after sc administration of the GnRH antagonist and for a minimum of 8 h in all women. The mean plasma LH levels were reduced within the first 4 h after antagonist administration at all doses (P less than 0.001). The duration of LH suppression was influenced by antagonist dose, with a continued effect 24 h after administration of the 500 micrograms/kg dose only. The maximum degree of LH suppression was 40% after 50 micrograms/kg (n = 6), 60% after 150 micrograms/kg (n = 6), and 59% after 500 micrograms/kg (n = 5). In contrast, plasma immunoreactive FSH levels did not change after these doses of the NAL-ARG GnRH antagonist. The maximum degree of FSH suppression was 16%, and the changes in plasma FSH concentrations were not dose dependent. Serum antagonist concentrations rose within 30 min after its administration to mean peak levels of 7.5 +/- 2.1 (+/- SE), 20.4 +/- 6.1, and 151 +/- 21 ng/mL after the 50, 150, and 500 micrograms/kg doses, respectively. The half-time of the disappearance of the NAL-ARG GnRH antagonist from plasma was 8.8 +/- 1.5 h. While there were no effects of antagonist administration on hematological, hepatic, or renal function, three women developed urticaria distant from the site of injection when administered the highest dose. We conclude that blockade of GnRH receptors by a GnRH antagonist 1) effectively antagonizes the action of GnRH, as assessed by its ability to block pulsatile LH secretion and reduce mean plasma LH levels; and 2) inhibits LH release to a considerably greater degree than FSH release, providing further evidence of possible GnRH-independent FSH secretion.

Adult↗

PubMed1988

Combined modality approach to treatment of malignant gliomas--re-evaluation of RTOG 7401/ECOG 1374 with long-term follow-up: a joint study of the Radiation Therapy Oncology Group and the Eastern Cooperative Oncology Group.

The Radiation Therapy Oncology Group (RTOG) and the Eastern Cooperative Oncology Group (ECOG) conducted a phase III trial in patients with malignant gliomas to evaluate 4 treatment arms: 1) 60 Gy to the whole brain; 2) 60 Gy plus 10-Gy boost; 3) 60 Gy plus carmustine (BCNU); and 4) 60 Gy plus semustine plus dacarbazine. Between September 1974 and March 1979, 626 patients with malignant gliomas were treated on protocol RTOG 7401/ECOG 1374. Each institution chose a subset of the treatments to which the patients would be randomized. Patients were stratified according to subset and randomized to the 4 treatment arms. There were no differences in survival among treatment arms. For patients greater than 60 years of age, the addition of chemotherapy to radiation therapy did not improve survival. For patients aged 40-60 years, there was a statistically significant increase in overall survival when BCNU was added to 60 Gy (P less than .01), with an increase in 2-year survival from 8% to 23%. This beneficial effect of BCNU is apparent in both histological groups (astrocytoma with atypical or anaplastic foci and glioblastoma multiforme). Although few confirmatory autopsies are available, long-term survival in patients with astrocytomas with atypical and anaplastic foci who were treated with 60 Gy plus BCNU (5-yr survival, 22%) suggests no significant late CNS toxicity, compared to 60 Gy alone (5-yr survival, 15%). This is confirmed by comparable neurological function in long-term survivors.

Adult↗

PubMed1986

A randomized comparison of misonidazole sensitized radiotherapy plus BCNU and radiotherapy plus BCNU for treatment of malignant glioma after surgery: final report of an RTOG study.

This randomized RTOG study evaluated misonidazole radiosensitized radiation therapy in the treatment of malignant glioma. One hundred and forty-six evaluable patients were treated with conventional radiation therapy to 60.00 Gy in 6-7 weeks plus BCNU 80 mg/m2/d for 3 days every 8 weeks (XRT + BCNU). One hundred and forty-seven evaluable patients were treated with misonidazole 2.5 gm/m2 once a week for 6 weeks, radiation therapy to 60 Gy and BCNU (MISO + XRT + BCNU). Patients were stratified according to the prognostic factors of age, performance status, and histology. Distribution of these characteristics was comparable among the treatment groups. The median survival for XRT + BCNU was 55.0 weeks, and for MISO + XRT + BCNU 46.0 weeks (p = 0.35). With patients on a minimum dose of dexamethasone of 3 mg/d, misonidazole neurotoxicity included 8.8% peripheral neuropathy, 2.7% CNS toxicity, and a 0.68% ototoxicity. BCNU pulmonary toxicity occurred in 9.3% of patients who received 902-2062 mg/m2 of BCNU.

Adult↗

PubMed1986

High-dose combination alkylating agents with autologous bone marrow support: a Phase 1 trial.

Twenty-nine patients were treated with 31 courses of high-dose combination cyclophosphamide, cisplatin, and carmustine (BCNU) with and without melphalan with autologous bone marrow support. Toxicity was dose related. The maximum tolerated dose for cyclophosphamide, cisplatin, and BCNU in this combination in mg/m2 was 5,625, 165, and 600, respectively. Further dose escalation was precluded by the development of multiple organ toxicity, including venoocclusive disease, refractory thrombocytopenia, and hypertension. Melphalan added to the three-drug combination produced excessive renal and gastrointestinal toxicity. Objective tumor regression occurred in 21 of 25 evaluable cases. The results suggest that selected alkylating agents can be combined in full or nearly full doses before nonmyelosuppressive dose-limiting toxicity precludes further escalation.

Adult↗

PubMed1986

Pulsatile secretion of thyrotropin in man.

To examine pulsatile TSH secretion, serum TSH was determined every 10 min for 24 h in 6 normal subjects and every 15 min in 10 euthyroid patients with underlying thyroid disease. Serum T4, T3, and PRL were simultaneously measured in the 10 patients. Pulsatile TSH secretion was identified in all individuals. There was a highly significant correlation between the mean 24-h TSH concentration and pulse amplitude (P less than 0.001). There was a highly significant inverse correlation between the mean 24-h TSH concentration and pulse frequency (P = 0.002) and between the pulse amplitude and frequency (P = 0.002). The mean serum TSH level at night (1800-0600 h) was significantly higher than that during the day (P less than 0.001) and was associated with increases in pulse amplitude (P = 0.008) and frequency (P = 0.007). TSH pulses did not correlate with serum T4 or T3, but did correlate with serum PRL (P = 0.03) in patients with thyroid disease. We conclude that TSH pulsations can be identified in normal subjects and patients with thyroid disease; elevations in serum TSH levels correlate with an increase in pulse amplitude and a decrease in pulse frequency; the nocturnal rise in serum TSH is associated with increases in both pulse amplitude and frequency; and peripheral serum T4 or T3 concentrations are not closely associated with pulsatile TSH secretion.

Adult↗

PubMed1986

Single-chamber and dual-chamber cardiac pacemakers. A formal cost comparison.

Dual-chamber pacemakers, more sophisticated and costly than single-chamber pacemakers, are being used with increasing frequency, often with unclear indications. Proponents of dual-chamber devices have focused on initial differences in cost without considering additional induced costs. We examined the incremental cost of dual-versus single-chamber pacemakers over the expected lifetime of a pacemaker recipient. In addition to initial costs, we included the costs of pacemaker malfunction, reimplantation, generator replacement, and follow-up. Expected differences in cumulative costs per patient were calculated over a 12-year period. Dual-chamber pacing is $2500 more costly at implantation. The difference in cumulative cost increases to $5100 by year 12, reflecting shorter functional life for dual-chamber pacemaker generators and increased cost of follow-up. The incremental cost of dual-chamber pacemaking is neither short-term nor trivial. Dual-chamber pacemakers should be reserved for those who clearly benefit from its advanced technology.

Costs and Cost Analysis↗