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Biomedical subjects

R David

Publications and source records attributed to R David.

At least 91 records · Page 5Linked to original sources
PubMed1994

Altered sensitivity to low dose dexamethasone in a subset of patients with premature adrenarche.

During adrenarche, levels of adrenal androgens increase. Although the regulatory mechanisms of adrenarche and premature adrenarche (PA) are not fully understood, it has been suggested that, unlike the cortisol (F) response to glucocorticoid suppression, which is not age dependent, before adrenarche the major adrenal androgen, dehydroepiandrosterone sulfate, is not suppressible by glucocorticoid. As these studies were performed using long term, high dose glucocorticoids, we sought to evaluate the F and adrenal androgen or androgen precursor suppression in response to low dose glucocorticoids [a single evening dose of dexamethasone (DEX), 0.3 mg/m2]. Twenty-four children (aged 1.3-8.75 yr; 4 males and 20 females) known to have PA, as determined by their response to ACTH-(1-24) (Cortrosyn; 0.25 mg, given by iv bolus), were studied. The children with PA could be divided into two groups, as defined by their morning F level after DEX administration: group I (n = 12), F levels below 5 micrograms/dL; and group II (n = 12), F levels of 5 micrograms/dL or more. Although the mean baseline values of F, testosterone, dehydroepiandrosterone, delta 4-androstenedione, 17-hydroxyprogesterone, and delta 5-17-hydroxypregnenolone did not differ between groups I and II, the mean levels in group I vs. group II of dehydroepiandrosterone, delta 4-androstenedione, and delta 5-17-hydroxypregnenolone were significantly greater in response to ACTH and lower in response to DEX (P < 0.05). Although no clinical difference was noted between the 2 groups, the mean SD for bone age adjusted for chronological age was greater and approached significance in group I, suggesting a greater degree of biological maturity in this group. These results suggest an increased sensitivity of the hypothalamic-pituitary-adrenal axis to changes in ACTH secretion in this subgroup of patients with PA.

Adrenal Glands↗
PubMed1994

Monitoring of girls undergoing medical therapy for isosexual precocious puberty.

We evaluated the use of sonography in monitoring the efficacy of suppressive therapy with a gonadotropin releasing hormone analogue in girls being treated for isosexual precocious puberty. Ten girls 5 to 9 years of age underwent serial sonography and hormonal stimulation tests on the same day. Sonographic trends of decreasing ovarian volume and uterine length indicated early suppression even when absolute values were above threshold. Changes in ovarian volume were the most sensitive predictor of pituitary-gonadal suppression. Sonography is a sensitive and accurate method of monitoring medical therapy; ovarian volume and analysis of interval change are the most sensitive barometers of change.

Child↗
PubMed1994

Altered cortisol response and hippocampal atrophy in pediatric HIV disease.

The hippocampus is a major center for the regulation of the hypothalamic-pituitary-adrenal axis. There is experimental evidence that chronic exposure to high levels of glucocorticoids may be toxic to the hippocampus. We observed elevated mean basal and 60-min cortisol (F) levels in response to adrenocorticotropin stimulation (0.25 mg cortrosyn, i.v. bolus infusion) in 15 children with HIV infection. Furthermore, in eight of the children for whom data was available, in addition to high peripheral cortisol levels, neurologic dysfunction and hippocampal atrophy were noted on CT scan. These preliminary data suggest that in HIV-infected children an altered cortisol secretion may be associated with specific central nervous system damage.

Adolescent↗
PubMed1993

Brimonidine in the prevention of intraocular pressure elevation following argon laser trabeculoplasty.

OBJECTIVE: To evaluate the efficacy of 0.5% brimonidine tartrate, an alpha 2-adrenergic agonist, in preventing intraocular pressure (IOP) elevation following argon laser trabeculoplasty. DESIGN: In a multicenter, double-masked, randomized study, 248 patients (248 eyes) who underwent argon laser trabeculoplasty were allocated to four treatment groups: (1) brimonidine administered before and after the procedure; (2) brimonidine administered before the procedure; (3) brimonidine administered after the procedure; and (4) a vehicle administered before and after the procedure. RESULTS: In the first 3 hours after argon laser trabeculoplasty, only one (0.54%) of the 183 brimonidine-treated patients had a postlaser IOP increase of 10 mm Hg or more, while increases of this magnitude occurred in 13 (23%) of the 56 patients who received only the vehicle (P < .001). The three brimonidine-treatment groups demonstrated significant mean reductions in IOP from the pretrabeculoplasty level (-4 to -8 mm Hg), whereas the vehicle-treated group showed an increase in mean IOP (4 mm Hg). Side effects associated with brimonidine treatment included conjunctival blanching (40.9%), lid retraction (7.6%), and a slight lowering of the systolic blood pressure. CONCLUSIONS: One drop of 0.5% brimonidine administered either before or after surgery was found to be efficacious and safe in preventing posttrabeculoplasty elevations in IOP.

Adrenergic alpha-Agonists↗
PubMed1993

Prolactin-secreting macroadenomas in adolescents. Response to bromocriptine therapy.

OBJECTIVE: To report five cases of prolactin (PRL)-secreting macroadenomas in adolescents, including their presentations and responses to bromocriptine mesylate treatment. PATIENTS: Five adolescents (three females and two males) aged between 12.5 and 17 years were diagnosed as having PRL-secreting macroadenomas at the pediatric endocrine service at New York University Medical Center between 1987 and 1989. Presenting complaints included visual field deficits, gynecomastia, and amenorrhea, both primary and secondary. All patients demonstrated some feature of hypogonadism or pubertal arrest. Diagnostic criteria included an elevated serum PRL level (mean, 1670 micrograms/L; range, 610 to 3700 micrograms/L) and visualization of a pituitary tumor that measured greater than 1 cm by either a computed tomographic scan or magnetic resonance imaging (mean size, 2.7 cm; range, 1.4 to 4 cm). INTERVENTIONS: Each patient was treated with bromocriptine mesylate at an oral dose of 7.5 mg/d. The patients continued with that treatment for the duration of the study period. MEASUREMENTS AND RESULTS: Anterior pituitary function was evaluated in four of five patients before treatment. All four were growth hormone deficient. Three patients were also gonadotropin deficient. Thyrotropin (thyroid-stimulating hormone) and corticotropin (adrenocorticotropic hormone) deficiencies were demonstrated in three patients who had multiple pituitary deficits. Follow-up testing included serial PRL measurements and radiographic imaging of tumor size. All patients demonstrated a marked decrease in PRL levels, as well as in tumor size (mean shrinkage, 70%). The three patients who initially had visual field deficits showed significant improvement of vision with bromocriptine therapy. Follow-up study of anterior pituitary function showed significant improvement with bromocriptine treatment in three patients. CONCLUSIONS: Bromocriptine was quite effective in the shrinkage of PRL-secreting macroadenomas in all our patients. It is a noninvasive treatment that can preserve and restore vision, as well as pituitary function, which is integral to continued growth and sexual maturation of the adolescent. Bromocriptine is preferable to surgery or radiation in the treatment of PRL-secreting macroadenomas in the adolescent.

Adolescent↗
PubMed1992

Juvenile autoimmune thyroiditis and mitral valve prolapse.

An increased incidence of mitral valve prolapse (MVP) has been reported in adult patients with autoimmune thyroid disease. The aim of this study was to assess the incidence of MVP in children and adolescents with juvenile autoimmune thyroiditis (JAT). Cardiac echo studies using M-mode, 2D, and Doppler examinations were performed on 23 patients (21 females, 2 males). The patients were studied at a median age of 12 years (range 5-20 years). Only one patient was found to have evidence suggestive of MVP, an incidence (4.3%) similar to that seen in the normal pediatric population. We, therefore, conclude that the incidence of MVP in children and adolescence with JAT is not increased.

Adolescent↗
PubMed1992

Small cell carcinoma of the ovary: an immunohistochemical and ultrastructural study with a review of the literature.

This is an immunohistochemical and ultrastructural study of two small cell carcinomas of the ovary with a review of the literature. These cases showed a dimorphic population of small and large cells sharply demarcated from each other. Cytokeratin 18 and vimentin were mainly expressed in the large tumour cells, some of which also stained for alpha-smooth muscle actin. Periodic-acid-Schiff-positive, alpha-1-antitrypsin-positive hyaline globules were present in one case. Ultrastructural findings included filamentous nucleolonema as well as evidence of smooth muscle differentiation. Some of these observations have not been previously reported. Certain of the above features seem to support a germ cell origin of small cell carcinoma, but they cannot be considered specific for germ cell neoplasms. Thus, small cell carcinoma of the ovary cannot be classified into one of the known categories of ovarian tumours at the present time.

Actins↗
PubMed1992

Acute colitis associated with prolonged administration of neuroleptics.

We describe a 29-year-old patient who developed acute colitis limited to the sigmoid and left colon with features mimicking ischemic injury after a prolonged administration of trifluoroperazine and levomepromazine, two phenothiazines in association with haloperidol, another neuroleptic, and biperidene, an anticholinergic compound. The discontinuation of these drugs was followed by a prompt and complete recovery, and no other cause of acute colitis was found. The subsequent administration of sultopride, a neuroleptic from the benzamide family and then the readministration of haloperidol were well tolerated. No colonic disorder occurred for the following months. This case strongly supports the view that neuroleptic agents, in particular phenothiazines, may induce acute colitis and that haloperidol, a butyrophenone derivative, or sultopride, a benzamide-related neuroleptic, can be administered thereafter without recurrence of the disease.

Adult↗
PubMed1992

Diurnal intraocular pressure variations: an analysis of 690 diurnal curves.

Out of a total of 2272 diurnal curves (DC) of intraocular pressure (IOP) obtained from 1178 patients 690 first curves of the right eye of all patients were analysed. For each DC there were 4-6 IOP readings taken between 8 am and 6.30 pm of the same day. The patients' diagnosis, age, sex, type of IOP lowering medication, diabetes, and the calendar month of the year were recorded. In 40% of cases the highest IOP was found at the earliest morning measurement with some 65% of peaks occurring before noon. The lowest IOP measurement showed no specific predilection for any particular time of the day. These findings were true for all diagnosis groups. The mean range of IOP fluctuation during the DC was 5.0 mm Hg in normals, 5.8 mm Hg in patients with open angle glaucoma (OAG), and 6.8 mm Hg in patients with ocular hypertension (OHT). Patients treated with timolol had a lower mean IOP fluctuation range than those on other types of IOP lowering treatment. No association was found between all other parameters examined and the diurnal IOP distribution.

Adrenergic beta-Antagonists↗
PubMed1992

Hyperparathyroidism with normal albumin-corrected total calcium in patients with multiple endocrine neoplasia type 1.

In the largest reported family of patients with multiple endocrine neoplasia type 1 (MEN 1), hyperparathyroidism was expressed at first screening in 33 patients by elevation of ionized calcium (IC) (30 cases) or parathyroid hormone (three cases) without elevation of albumin-corrected total calcium (ACTC). Three of these 33 patients have shown a progressive rise in IC and later an elevation of ACTC. However, the age distribution suggests that in others the level of IC may remain stable at a minimally elevated level throughout life with ACTC remaining normal except for transient rises at the times of intercurrent illness or surgical operation. Even when ACTC is normal preoperatively, patients with an elevation of IC require radical subtotal parathyroidectomy or total parathyroidectomy and forearm implantation to restore IC to a normal level. Institutions that rely on ACTC as a screening test for hyperparathyroidism in MEN 1 will miss the diagnosis in nearly half of patients under the age of 30. The greatest deficiency in using ACTC occurs in the follow-up of patients who have undergone parathyroidectomy for MEN 1. Only three of 11 recurrences were evidenced by this measurement.

Adolescent↗
PubMed1992

Spontaneous hyphema: an unusual complication of uveitis associated with ankylosing spondylitis.

Two patients with ankylosing spondylitis (AS) and recurrent uveitis had rubeosis iridis each with an episode of spontaneous hyphema. Rubeosis iridis has been reported to occur in some cases of uveitis, but it has not been seen in those associated with AS. We suggest that AS be included among the conditions that can lead to the development of rubeosis iridis, with consequent silent hyphema.

Adult↗
PubMed1991

Identification of a major human immunodeficiency virus-1 reverse transcriptase epitope recognized by mouse CD4+ T lymphocytes.

Delineation of major T helper cell recognition sites of human immunodeficiency virus (HIV-1) proteins represents one important step in the design of an efficient acquired immune deficiency syndrome (AIDS) vaccine. Towards this end, we have explored the immunogenicity of HIV-1BRU proteins in the mouse model. Preliminary experiments revealed that inbred mice primed with whole inactivated HIV-1 developed strong CD4+ T cell proliferative responses to a variety of recombinant viral proteins including reverse transcriptase (RT). To characterize further the mouse T cell responses to this protein, several Ad- or Ed-restricted T hybridoma cells (THC) were established from BALB/c or DBA/2 mice. These THC were tested for their capacity to recognize a series of 15-mer synthetic overlapping peptides spanning three segments of HIV-1 RT that had been preselected on the basis of either alpha-helicity, amphipaticity, and/or for containing rare amino acid sequence patterns. Peptides corresponding to a C-terminal region (residues 528-560) of RT were recognized by several of the THC established from RT-primed mice. Furthermore, a non-alpha-helical peptide from this region (A3, 528-543) was capable of priming mice with different H-2 haplotypes for both peptide A3 and native RT CD4+ T cell recognition. In addition to the recently identified RT determinant 203-219 capable of triggering both mouse and human CD8+ CTL, the present results identify a good candidate for an immunodominant RT epitope capable of eliciting RT-specific T helper cell responses.

Animals↗
PubMed1991

The calcaneus: normal and abnormal.

The calcaneus is the largest tarsal bone. Many congenital and acquired disorders affect the bone. Primary disorders arise in the calcaneus itself, whereas secondary disorders arising in the neighboring soft tissues extend into and affect the calcaneus indirectly. Among the primary lesions, congenital, traumatic, infectious, hematologic, neoplastic, and other miscellaneous disorders constitute the majority, whereas various arthritides and soft-tissue neoplasms that arise adjacent to the bone constitute the important secondary calcaneal disorders. Radiographic features of many disorders of the calcaneus are disease-specific and thus diagnostic. This article describes a wide spectrum of calcaneal disorders and illustrates their salient radiographic features. This knowledge should facilitate radiographic diagnosis of various calcaneal disorders encountered in clinical practice.

Bone Diseases↗
PubMed1991

Suppression of the pituitary-gonadal axis in children with central precocious puberty: effects on growth, growth hormone, insulin-like growth factor-I, and prolactin secretion.

To assess further the relationship between gonadal sex steroids and PRL, GH, and insulin-like growth factor-I (IGF-I) secretion and to help clarify the mechanism underlying the pubertal growth spurt, we studied 11 children (10 girls) with central precocious puberty before and during gonadal suppression with the GnRH agonist (GnRH-a) leuprolide acetate. Nocturnal sampling for plasma levels of GH and PRL, GH response to GH-releasing factor-(1-44), and plasma IGF-I levels were determined before and 3-6 months after pituitary-gonadal suppression. Treatment caused a significant decrease in the LH and FSH responses to GnRH (P less than 0.01) and the plasma concentration of estradiol (P less than 0.05). The patients' mean height velocity SD score for chronological age, initially 3.8 +/- 1.9, decreased significantly to 0.9 +/- 0.9 with treatment (P less than 0.005). Nocturnal GH secretion (mean GH concentration, sum of GH pulse areas, sum of GH pulse amplitudes, and GH pulse frequency) and mean IGF-I levels (1.38 +/- 0.6 vs. 1.72 +/- 0.34 U/mL) were not significantly altered by treatment. However, the mean peak GH response to GH-releasing factor-(1-44) was 29.2 +/- 6.8 micrograms/L before treatment and declined significantly to 17.7 +/- 3.4 micrograms/L after gonadal suppression (P less than 0.05). PRL secretion was similar before and after GnRH-a-induced suppression. These results indicate that the decrease in height velocity noted during GnRH-a treatment occurred independently of changes in nocturnal GH secretion and IGF-I levels. These data are consistent with the premise that sex steroids can modulate growth by a direct action on skeletal growth.

Antineoplastic Agents↗
PubMed1990

Platelet aggregating IgG antibody to platelet surface glycoproteins associated with thrombosis and thrombocytopenia.

Previously described platelet-aggregating antibodies associated with thrombosis and thrombocytopenia required heparin for their in vivo and in vitro expression. We have observed a patient with thrombosis who became thrombocytopenic during heparin treatment, but who suffered further thrombotic events and continued thrombocytopenia for 3 months after heparin withdrawal. The patient's plasma contained a potent platelet aggregating factor reactive with both his own and normal platelets in the absence of heparin. It also caused [14C]serotonin secretion from labelled platelets from normal donors and patients with either Glanzmann's thrombasthenia or Bernard-Soulier syndrome. This factor was an IgG and was neutralized by antibody specific for IgG lambda light chains. While the patient was thrombocytopenic an IgG paraprotein with lambda light chains was detected by isoelectrofocussing. After corticosteroid treatment it disappeared and the patient recovered. The active, but not the recovery serum contained IgG which immunoprecipitated a glycoprotein with characteristics of Glycoprotein IV from platelets labelled with Na[3H]BH4/periodate. Thus platelet-aggregating IgG antibodies with direct specificity for platelet surface glycoproteins may be associated with thrombosis/thrombocytopenia.

Humans↗