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Biomedical subjects

K L Jones

Publications and source records attributed to K L Jones.

At least 181 records · Page 10Linked to original sources
PubMed1990

Terminal deletions of the long arm of chromosome 7: five new cases.

Twenty-two cases of terminal deletions of the long arm of chromosome 7 have been reported. We present 5 new cases, 3 of which were ascertained due to fetal holoprosencephaly, one due to anencephaly, and one due to multiple structural defects in a 15-year-old boy. The presence of holoprosencephaly in 3 of the 5 cases reported herein and in 2 previously reported cases suggests that this manifestation may be commonly observed in individuals with deletion 7q.

Abnormalities, Multiple↗
PubMed1990

Williams syndrome: an historical perspective of its evolution, natural history, and etiology.

This review examines the Williams syndrome (WS) from an historical perspective, beginning with the early descriptions of idiopathic infantile hypercalcemia (IIH) and ending with some speculative ideas about a possible causative function of a recently discovered neuropeptide. The earliest reports of WS individuals are probably those which describe a "severe" subgroup of IIH and separate it from the epidemic of milder IIH reported in Post-WWII Great Britain and Europe. Most of these latter cases apparently resulted from hypervitaminosis D produced by excessive supplementation of government-supplied infant foods. With more extensive recognition and reporting of this "severe" subgroup, the diagnostic constellation of IIH, mental deficiency, elfin face, and supravalvular aortic stenosis (SVAS) evolved as WS. More of these reports emphasized the physical and behavioral manifestations as the key diagnostic features, and the frequency of occurrence and relative importance of SVAS and IIH in WS decreased. Despite the diminished consequence of hypercalcemia, calcium and vitamin D have continued to dominate the investigation of the cause of infantile hypercalcemia and led to the proposal and confirmation of deficient calcitonin secretion in individuals with WS. Though calcitonin is probably pertinent only to infantile hypercalcemia, its alternative gene product, calcitonin-gene-related product, is an important neuropeptide with physiological effects in the central nervous system and cardiovascular systems which raise the possibility that it may be responsible for some of the manifestations of WS.

Abnormalities, Multiple↗
PubMed1990

Prenatal diagnosis of a craniopharyngioma using ultrasonography and magnetic resonance imaging.

We report an infant with a craniopharyngioma which was detected in utero. Maternal uterine ultrasonography, done at 27 weeks because of polyhydramnios, revealed a 4 cm midline mass near the base of the fetal skull. At 31 weeks, magnetic resonance imaging of the maternal abdomen confirmed the presence of a mass in the region of the third ventricle and revealed hydrocephalus. Two days post-partum a computed tomography (CT)-guided needle biopsy of the mass was performed and recovered tissue which was histologically consistent with a craniopharyngioma. The infant's postnatal period was complicated by seizures, which were treated with phenobarbital, and by progressive hydrocephalus, necessitating placement of a ventriculo-peritoneal shunt. He also received therapy for central hypothyroidism and diabetes insipidus. The infant's parents refused permission for attempted resection of the tumour and he died at 8 weeks of age. This represents the second reported case of an antenatally detected craniopharyngioma. Four other cases of different intracranial tumours have been detected in utero using ultrasound, with no reported survivors past 3 days of age. There is a uniformly poor prognosis of such infants, but earlier diagnosis and intervention may change this result.

Craniopharyngioma↗
PubMed1990

Oligohydramnios sequence and renal tubular malformation associated with maternal enalapril use.

We present the case of a child who died of pulmonary hypoplasia as a result of the oligohydramnios sequence. The mother was taking enalapril, as well as propranolol and hydrochlorothiazide, for treatment of hypertension associated with systemic lupus erythematosus. Autopsy examination revealed severe renal tubular malformation. Correlation of animal data with previous case reports of neonatal anuria in association with maternal angiotensin converting enzyme inhibitors suggests that these agents may have a deleterious effect on fetal renal development and general well-being.

Amniotic Fluid↗
PubMed1990

Patterns of malformation in children with congenital diaphragmatic defects.

The medical records of 102 live-born children with a congenital diaphragmatic defect were reviewed to determine the frequency and nature of underlying chromosomal, genetic, and nongenetic patterns of malformation. Overall, 40 children (39%) had a major nonpulmonary malformation, and 14 of these children (14%) had a previously recognized pattern of malformation. A group of 18 children (18%) with cardiac anomalies had an increased mortality rate in comparison with those children without cardiac defects (72% vs 38%). The frequency and severity of nonpulmonary abnormalities in children with congenital diaphragmatic defects suggest that examination of affected children should include cardiac evaluation, a karyotype when the defect is one feature of a broader pattern of altered development, and a careful evaluation for minor anomalies, which may provide clues to an overall diagnosis.

Abnormalities, Multiple↗
PubMed1990

The Cushing syndromes.

The 10 years since this journal's last review of CS have seen extraordinary advances in our understanding of many aspects of its causes, diagnosis, and treatment. The spectrum of what are now called the Cushing syndromes has expanded considerably to include CD, multiple sources of ectopic ACTH secretion, and an apparent autoimmune cause. Improved assays of ACTH and the availability of CRF have provided new insight into the physiology and pathophysiology of the HPA axis and new tools for diagnosis of CS, especially in combination with selective catheterization and sampling. New imaging technology has improved our visualization of pituitary adenomas and has provided powerful methods for identifying tumors ectopically secreting ACTH and primary adrenal tumors. Finally, the refinement of transsphenoidal surgery and its success in treating CD have provided a safe and effective therapy for this disease. For those occasional patients who require medical therapy, drugs are available that decrease steroid biosynthesis. We now have a much better understanding of a fascinating disease process and are able to diagnose and treat it more correctly. One is impatient to see which new pieces of this puzzle will fall into place over the next ten years.

Adolescent↗
PubMed1990

Glucocorticoids: potent inhibitors and stimulators of growth hormone secretion.

Excessive glucocorticoid concentrations are well recognized inhibitors of linear growth, due in part to their suppression of GH secretion. The mechanism of this inhibition has been unclear, especially since glucocorticoids enhance the in vitro GH response of pituitary cells to GH-releasing hormone (GHRH). We investigated the possibility that hypothalamic somatostatin might be mediating these dichotomous observations by using passive immunization techniques. The GH response to GHRH was significantly blunted in rats pretreated with the synthetic glucocorticoid, dexamethasone, compared to that in normal animals. In marked contrast, the immunoneutralization of somatostatin resulted in a significantly enhanced GH response to GHRH in dexamethasone-treated animals. These results suggest that the previously described inhibitory action of glucocorticoids on GH secretion in vivo are mediated via altered hypothalamic somatostatin tone.

Animals↗
PubMed1990

The synthesis and accumulation of fibronectin by human articular cartilage.

Fibronectin was extracted from cartilage under denaturing conditions at concentrations of 1.5 and 15 micrograms/g wet weight for normal and osteoarthritic cartilage, respectively (i.e., there was a 10-fold increase in osteoarthritic cartilage). Heterogeneity on ion exchange and gelatin affinity chromatography and on agarose electrophoresis was consistent with the suggestion that it interacts strongly with elements of proteoglycans. Aggregation of cartilage proteoglycan by addition of hyaluronic acid also aggregated the endogenous fibronectin. Synthesis of fibronectin was identified in explants of normal cartilage by immunoprecipitation and electrophoresis. We conclude that cartilage fibronectin is a normal component of human cartilage and a normal product of mature chondrocytes.

Adolescent↗
PubMed1990

Fryns syndrome: an autosomal recessive disorder associated with craniofacial anomalies, diaphragmatic hernia, and distal digital hypoplasia.

Fryns syndrome is an autosomal recessive, genetically determined condition with variable expression, which includes abnormal facial features, diaphragmatic hernia, distal limb abnormalities, and malformations of the cardiovascular, gastrointestinal, genitourinary, and central nervous systems. Five cases of children with Fryns syndrome, including an example of familial recurrence and a case of long-term survival, are described. This report brings to 25 the number of cases reported in the literature and further serves to illustrate the clinical variability of this disorder.

Abnormalities, Multiple↗
PubMed1990

Prenatal cocaine exposure and fetal vascular disruption.

The question of the potential teratogenicity of cocaine has been raised by the increasing frequency of its abuse in the United States. In previous studies, an increased incidence has been documented of spontaneous abortion, placental abruption, prematurity, intrauterine growth retardation, and neurologic deficits in the infants of women who abused cocaine. More recently, it has been suggested in studies that fetal vascular disruption accompanying maternal cocaine abuse may lead to cavitary central nervous system lesions and genitourinary anomalies. In this article, 10 children born of women who abused cocaine are described, 9 of whom have congenital limb reduction defects and/or intestinal atresia or infarction. The spectrum of anomalies associated with embryonic and fetal vascular disruption accompanying maternal cocaine abuse is thus enlarged. The specific risk for congenital anomalies accompanying maternal cocaine abuse during an individual pregnancy is unknown. However, data from these patients and the available literature suggest that counseling pregnant women concerning cocaine use should incorporate warnings about the possibility of associated embryonic or fetal vascular disruption.

Abnormalities, Drug-Induced↗
PubMed1989

Pattern of malformations in the children of women treated with carbamazepine during pregnancy.

In an attempt to determine whether and to what extent carbamazepine is teratogenic, we evaluated eight children whom we identified retrospectively as having had prenatal exposure to carbamazepine alone or in combination with a variety of anticonvulsants other than phenytoin. In addition, in a prospective study, we documented the outcome of the pregnancies of 72 women who contacted us early in pregnancy because they were concerned about the potential teratogenicity of carbamazepine. A pattern of malformation, the principal features of which are minor craniofacial defects and fingernail hypoplasia, and of developmental delay was identified in the eight children retrospectively ascertained to have been exposed to carbamazepine in utero; this pattern was subsequently confirmed through the evaluation of 48 children born alive to the women in the prospective study. That carbamazepine itself is teratogenic is indicated by the incidence of craniofacial defects (11 percent), fingernail hypoplasia (26 percent), and developmental delay (20 percent) in the 35 live-born children of the women in the prospective study who were exposed prenatally to carbamazepine alone. The similarity between the children exposed prenatally to carbamazepine and those with the fetal hydantoin syndrome is probably related to the fact that both drugs are metabolized through the arene oxide pathway and raises the possibility that it is the epoxide intermediate rather than the specific drug itself that is the teratogenic agent.

Abnormalities, Drug-Induced↗
PubMed1989

Chromosome 10qter deletion syndrome: a review and report of three new cases.

We report on three patients with terminal deletions of chromosome 10q and compare them to 15 previously reported patients. A similar facial appearance with a prominent beaked nose, large and/or malformed ears, and a pattern of major abnormalities including severe mental retardation, cardiac anomalies, and anogenital anomalies are reviewed. We feel the manifestations of del 10qter are sufficiently distinct to suggest this diagnosis on clinical examination.

Abnormalities, Multiple↗
PubMed1989

Occurrence of male phenotype in genotypic females with congenital virilizing adrenal hyperplasia.

We report on two genotypic females with complete masculinization of the external genitalia secondary to congenital adrenal hyperplasia resulting from 21-hydroxylase deficiency. One patient had the salt-losing variant, and the other had the simple virilizing or nonsalt-losing variant. One was evaluated neonatally during an adrenal crisis and misidentified as male; the second was unrecognized. Both were being reared as males when the true genotype was recognized during evaluation for cryptorchidism. The female internal genitalia were subsequently removed and testicular implants placed. These cases demonstrate the need to exclude congenital virilizing adrenal hyperplasia in any phenotypic male infant with bilateral cryptorchidism. When this condition is diagnosed, early and genotypically appropriate sex assignment is important if reproductive function is to be preserved and subsequent emotional and social complications avoided.

Adrenal Hyperplasia, Congenital↗
PubMed1989

Cyclosporine induces abnormal facial bone growth in children: a preliminary study.

Using cephalometric radiography, facial bony structure of a group of pediatric renal transplant recipients immunosuppressed with cyclosporine (CsA) and prednisone was studied and compared with a control group of children. A pattern of abnormal facial growth was demonstrated on cephalometry in eight of nine transplant recipients receiving CsA. The abnormalities included shortening of posterior facial height and increased anterior facial height with a deep mandibular plane angle. There was also an absolute shortening in the mandibular body and mandibular retrognathia. These findings may be consistent with inhibition of mandibular condylar growth inhibiting the anteroinferior growth of the mandible. Similar changes were present in two children with end-stage renal disease and none of the remaining nine control patients (P less than 0.01, chi-squared analysis). The affected area appears to be the lower third of the face. The role of CsA in affecting facial bony growth in children needs to be evaluated further.

Adolescent↗
PubMed1989

Nocturnal melatonin levels are unaltered by ovarian suppression in girls with central precocious puberty.

Girls with central precocious puberty were utilized as a model in which to study the melatonin secretory response to ovarian suppression. Eight girls with central precocious puberty documented by clinical and endocrine characteristics, including sleep-entrained augmentation of luteinizing hormone (LH) pulsatility, were investigated. Nocturnal (6:00 P.M. to 9:00 A.M.) plasma melatonin levels were measured hourly by a sensitive and specific radioimmunoassay before and after gonadotropin-ovarian downregulation with gonadotropin-releasing hormone (GnRH)-agonist. Although nocturnal melatonin elevations varied widely between girls, patterns within the same individual were remarkably reproducible and unaltered before and after treatment. Although estrogens have been shown to modulate melatonin synthesis and secretion, in this model, reduction of estrogen levels was not associated with alterations in plasma melatonin concentrations.

Child↗
PubMed1989

Theca function in polycystic ovaries of a patient with virilizing congenital adrenal hyperplasia.

The steroidogenic activity of purified theca interstitial cells (TIC) from polycystic ovaries of a patient with virilizing congenital adrenal hyperplasia due to 21-hydroxylase deficiency was studied in serum-free medium. The results show that CVAH TIC have high intrinsic basal androgen secretory activity that is dramatically stimulated by hCG, insulin, and lipoproteins, particularly HDL. Accordingly, the results support the hypothesis that TIC may contribute to the development of polycystic ovaries in CVAH patients, perhaps by mechanisms independent of the adrenal glands.

Adrenal Hyperplasia, Congenital↗