PubMed Health⌕ Search

Biomedical subjects

M E Geffner

Publications and source records attributed to M E Geffner.

At least 55 records · Page 3Linked to original sources
PubMed1992

Insulin and insulin-like growth factor-I responsiveness in polycystic ovarian syndrome.

OBJECTIVE: To assess insulin and insulin-like growth factor I (IGF-I) action in women with polycystic ovarian syndrome (PCOS). DESIGN: Hyperinsulinemia was determined by measuring the insulin responses during a 2-hour oral glucose tolerance test (OGTT). Quantification of in vivo insulin action was determined by a frequently sampled intravenous (IV) OGTT with minimal modeling analysis. In vitro sensitivity to insulin at physiological and supraphysiological concentrations and to IGF-I was assessed by examining colony formation of two hematopoietic cell populations, burst-forming units of the erythroid line (BFU-E) and human leukemia virus immortalized T-cell lines. (The proliferative responses of BFU-E, a primary tissue explant, are presumably conditioned by factors in the immediate blood-borne environment, whereas proliferative responses of T-cell lines are presumed to reflect intrinsic target-cell hormone sensitivity.) SETTING: Tertiary care research institution. PATIENTS: Eight patients (4 obese and 4 nonobese) with PCOS and three healthy women for reference controls. RESULTS: Nonobese (P less than 0.04) and obese patients with PCOS (P less than 0.01) both demonstrated significant hyperinsulinemia after OGTT. In vivo insulin resistance was observed in both nonobese (P less than 0.03) and obese PCOS subjects (P less than 0.01) using frequently sampled IV OGTT. Both nonobese (P less than 0.03) and obese patients with PCOS (P less than 0.01) had blunted in vitro clonal responses of BFU-E, with normal T-cell line clonal responsiveness to physiological levels of insulin and normal BFU-E and T-cell line clonal responses to IGF-I. CONCLUSIONS: These findings demonstrate the following in both nonobese and obese patients with PCOS: (1) there is in vivo hyperinsulinemia and resistance to insulin action on glucose disposal; (2) with BFU-E, there is in vitro resistance to the mitogenic action of insulin but normal responsiveness to IGF-I; and (3) there is normal in vitro mitogenic responsiveness of T-cell lines to both insulin and IGF-I. The intrinsically normal mitogenic responsiveness to insulin and, especially to IGF-I, whether or not under the influence of the bloodborne milieu, provides a mechanism whereby hyperinsulinemia could directly contribute to the ovarian abnormalities that characterize PCOS.

Adult↗
PubMed1991

Pediatric germ cell and human chorionic gonadotropin-producing tumors. Clinical and laboratory features.

Germ cell tumors may cause various aberrations in pubertal development. In prepubertal boys, these tumors may secrete human chorionic gonadotropin, resulting in precocious puberty. Human chorionic gonadotropin and alpha-fetoprotein are both useful as germ cell tumor markers in the diagnosis and detection of recurrence. Pregnancy-specific beta 1-glycoprotein, another oncoplacental antigen, has been used as a tumor marker for trophoblastic neoplasms, but not previously for human chorionic gonadotropin-producing tumors associated with precocious puberty. Patients with germ cell tumors may also have abnormal karyotypes. Herein, we describe six male pediatric patients with germ cell tumors and pubertal derangements seen during an 8-year period. We confirm the high incidence of associated sexual precocity, the usefulness of alpha-fetoprotein, human chorionic gonadotropin, and pregnancy-specific beta 1-glycoprotein as tumor markers in the diagnosis and follow-up of these patients, and the occurrence of sex chromosomal abnormalities.

Adolescent↗
PubMed1991

Use of in vitro clonogenic assays to differentiate acquired from genetic causes of insulin resistance.

Insulin resistance may be due directly to genetically programmed disorders of insulin action or acquired defects in which environmental factors influence insulin action. To address the issue of this distinction, we studied the ability of insulin to stimulate colony formation in primary cultures of erythroid progenitors (assumed to retain environmental influences) and immortalized T lymphocytes (presumed to reflect only genetic influences). Four patients with hyperinsulinemia and disturbed glucose metabolism were studied (2 patients with acanthosis nigricans, 1 of whom had circulating anti-insulin-receptor antibodies, 1 with partial lipodystrophy, and 1 with Cushing's syndrome). The mean colony-forming ability of their erythroid progenitor cells in response to insulin stimulation (less than or equal to 1.6 pM) was significantly blunted compared with control cells (P less than 0.05). The mean responsiveness of their immortalized T-lymphoblast cell lines to similar insulin concentrations was no different than that of control T-lymphocyte lines, consistent with an acquired cause for the observed insulin resistance in each case. A T-lymphocyte line from a patient with leprechaunism, however, showed no stimulation in response to physiological concentrations of insulin. With these same in vitro methodologies, there was normal T-lymphocyte line responsiveness to insulinlike growth factor I (IGF-I) or insulin concentrations greater than 8.6 pM; both of these responses could be completely blocked by preincubation with an antibody to the IGF-I receptor. These findings suggest that, despite resistance to physiological levels of insulin, the high circulating insulin concentrations present in the serum of these patients could mediate unwanted tissue-specific growth through an intact IGF-I receptor-effector mechanism.

Acanthosis Nigricans↗
PubMed1990

T-lymphoblast cell lines from Laron dwarfs augment basal colony formation in response to extremely high concentrations of growth hormone.

The clinical entity of Laron dwarfism is characterized by resistance to both endogenous and exogenous GH and may be due to a deficiency or absence of functional GH receptors. We previously showed that two types of hematopoietic cells derived from these patients are resistant to the in vitro growth-promoting action of GH at concentrations below 500 micrograms/L. In the current study we found that Laron T-cell lines had a mean peak augmentation of basal colony formation of 22 +/- 3.4% above baseline in response to a GH concentration of 10,000 micrograms/L. Since cloned cDNAs for human and rabbit GH receptors and rat PRL receptors show a high degree of sequence homology, we undertook studies of PRL action in cells from patients with Laron dwarfism to determine if the Laron defect was also associated with PRL unresponsiveness. Quantitating the augmentation of colony formation by T-lymphoblast cell lines established from three Laron dwarfs, we found normal responsiveness to PRL at concentrations of 25-10,000 micrograms/L. It is, thus, possible that the responsiveness of Laron T-cell lines to very high concentrations of GH could be mediated through an intact PRL (or other lactogenic) receptor based on the known affinity of GH for these receptors in other systems. These data suggest that cells from patients with Laron dwarfism have normal in vitro responsiveness to PRL and that the defect in Laron dwarfism appears to be specific to the GH receptor-effector pathway. It remains to be determined whether intact alternative lactogenic receptor mechanisms subserve any clinical effects of GH in patients with Laron dwarfism.

Cell Line↗
PubMed1990

Growth hormone mediates the growth of T-lymphoblast cell lines via locally generated insulin-like growth factor-I.

It has become evident that locally produced insulin-like growth factors-I and -II (IGF-I and IGF-II) play an important role in the medication of GH action upon tissues. To explore this concept with respect to immunocompetent cells, we analyzed IGF production and clonogenic responsiveness of immortalized human T-cell lines established from seven normal controls and four Laron dwarfs. While the normal T-cell lines showed significant augmentation of basal colony formation in response to both IGF-I and GH, little increase in clonogenesis in response to GH was seen with the Laron T-cell lines. Assay of basal and GH-stimulated conditioned media demonstrated low, but measurable, levels of IGF-I and IGF-II from both normal and Laron T-cells. Under serum-free incubation conditions, GH stimulation of normal T-cell lines failed to generate significant increases in mean IGF-I or IGF-II concentration and no increase in the mean IGF-II concentration in conditioned medium were observed after GH stimulation of Laron T-cell lines. Nevertheless, the increased cloning efficiency of the normal T-cell lines in response to either GH or IGF-I was nearly completely abrogated by preincubation of cells with antibodies to either IGF-I or the type I IGF receptor. These studies, thus, support a role for locally generated IGF-I in the mediation of GH action on T-lymphocytes and indicate that this effect is mediated via the type I IGF receptor.

Cell Division↗
PubMed1990

Surgical management of islet cell dysmaturation syndrome in young children.

Islet cell dysmaturation syndrome (ICDS) encompasses the causes of infantile hyperinsulinemic hypoglycemia histologically described as islet cell hyperplasia, pancreatic adenomatosis and nesidioblastosis. Eleven infants underwent 14 pancreatic resections for ICDS from 1965 to 1990 at the University of California at Los Angeles Medical Center for severe hypoglycemia unresponsive to medical therapy. Seizures were the presenting symptoms of hypoglycemia in eight infants. Six patients had nesidioblastosis, four had islet cell hyperplasia and one patient had an adenoma with histologically normal pancreatic islet cells. Four neonates underwent 80 per cent pancreatic resection; three with nesidioblastosis required reoperation (90 to 95 per cent resection). Four older infants underwent 80 per cent pancreatic resection but required diazoxide for less than six months postoperatively. Three infants underwent 90 to 95 per cent pancreatic resection. None have required reoperation or postoperative medications. All infants are normoglycemic without pancreatic exocrine insufficiency and none had postoperative complications. Five infants had preoperative neurologic impairment, with three having severe retardation; all showed some improvement postoperatively, but only one infant now has normal findings on neurologic examination. Early diagnosis and aggressive surgical resection should minimize neurologic complications of the ICDS.

Adenoma↗
PubMed1989

Absence of nonclassical congenital adrenal hyperplasia in patients with precocious adrenarche.

We studied 31 patients (28 girls and 3 boys), ranging in age from 3.2-7.9 yr, with precocious adrenarche defined by the presence of early sexual hair development, no signs of virilization, and bone age within +3 SD of the mean for chronological age. To determine if this symptom complex stemmed from any form of nonclassical (late-onset) congenital adrenal hyperplasia, an ACTH stimulation test was performed on each patient using a standard 0.25-mg dose of Cortrosyn, given as an iv bolus. Twelve pubertal children (7 girls and 5 boys) and 18 prepubertal children (11 girls and 7 boys) served as normal controls. Baseline and stimulated 17-hydroxypregnenolone (17-OHPreg), 17-hydroxyprogesterone, (17-OHP), 11-deoxycortisol, dehydroepiandrosterone, androstenedione, testosterone, and cortisol levels were measured. Using published nomogram standards for serum 17-OHP response to ACTH, no child with precocious adrenarche was diagnosed as having nonclassical 21-hydroxylase deficiency. Eight girls, however, had a stimulated 17-OHP value that exceeded the mean response for pubertal and prepubertal controls by more than +2 SD [range, 295-670 ng/dL (8.94-20.3 nmol/L)]. Stimulated 11-deoxycortisol values [less than 400 ng/dL (11.6 nmol/L)] ruled out any cases of nonclassical 11 beta-hydroxylase deficiency. No patient had nonclassical 3 beta-hydroxysteroid dehydrogenase deficiency, as defined by both the stimulated 17-OHPreg and the 17-OHPreg/17-OHP ratio to be more than +2 SD above the mean for pubertal children [1354 ng/dL (41.0 nmol/L) and 10.4, respectively]. In conclusion, we could not provide any biochemical evidence for nonclassical congenital adrenal hyperplasia in a large group of children with precocious adrenarche.

17-alpha-Hydroxypregnenolone↗
PubMed1988

Selective insulin action on skin, ovary, and heart in insulin-resistant states.

States of hyperinsulinemia with resistance to insulin action on glucose disposal are frequently associated with proliferative tissue abnormalities of the skin (acanthosis nigricans), ovary, and heart. That insulin may be involved in the pathogenesis of these growth-related abnormalities despite resistance to its metabolic effects mediated through the insulin receptor is suggested by the known ability of high concentrations of insulin to stimulate DNA synthesis and cell proliferation in vitro through the insulin-like growth factor I (IGF-I) receptor. IGF-I receptors are present in skin keratinocytes, some ovarian tissue compartments, and in the heart. Furthermore, ovarian tissue from hyperinsulinemic insulin-resistant women responds to supraphysiologic insulin concentrations in vitro by enhanced steroidogenesis. Cultured, transformed T-lymphocytes from an infant with leprechaunism fail to augment basal-colony formation in response to physiologic insulin concentrations in vitro (compared to a doubling seen in normal subjects), but respond normally to supraphysiologic insulin concentrations, the effect of which is competitively inhibited by a monoclonal antibody to the IGF-I receptor. Thus, insulin action mediated through the IGF-I receptor may initiate growth-promoting tissue effects in the face of limited insulin effect on glucose metabolism. Such spillover actions may add to the morbidity associated with states of clinical insulin resistance.

Acanthosis Nigricans↗
PubMed1988

Renal malformations in patients with Turner syndrome: imaging in 141 patients.

Turner syndrome occurs in 1/2,000 to 1/5,000 live female births. The presence of renal malformations was evaluated in 141 patients with Turner syndrome and abnormalities were found in 47 (33%). Prior to 1980, IVP was the radiologic method used for initial screening, and subsequently, ultrasonography has been used as the initial imaging technique. With both methods, major malformations can be detected. Ten patients had a horseshoe kidney, 11 had double collecting systems, four had complete absence of one kidney, three had crossed ectopia, and one had a pelvic kidney. Three patients had ureteropelvic junction obstruction; two of these were asymptomatic and the obstructions were detected only because of the routine imaging. Two patients had ureterovesicular junction obstruction, with one studied as part of a routine evaluation for short stature. Four of these five patients required surgery. Ultrasonography should be used as the initial renal imaging study for all patients at the time the diagnosis of Turner syndrome is made.

Female↗
PubMed1987

Leprechaunism: in vitro insulin action despite genetic insulin resistance.

We recently identified a female leprechaun infant with marked hyperinsulinemia [as high as 10,975 microU/ml (78,746 pmol/liter)], presumably secondary to insulin resistance. She had two physical findings suggestive of possible insulin action: cystic ovarian enlargement with gonadotropin-independent steroid secretion and persistent, severe myocardial hypertrophy. To examine the pathophysiology of this disorder we measured the in vitro sensitivity to insulin and other growth factors of erythroid progenitors and a T-lymphoblast cell line derived from her peripheral blood. Resistance to insulin was demonstrated by failure of her circulating erythroid progenitor cells to augment proliferation in response to physiologic concentrations of insulin (1-10 ng/ml). An immortalized T lymphoblast cell line was established by transforming the cells with the human retrovirus human T cell leukemia virus II. This cell line showed little or no response to physiologic concentrations of insulin contrary to consistently observed stimulation of colony formation by cell lines similarly derived from normals. The patient's T lymphoblasts, however, showed normal sensitivity to insulin-like growth factor I. In response to supraphysiologic insulin concentrations (25-1000 ng/ml), leprechaun T lymphoblasts showed significant augmentation of colony formation (peak 189% above baseline at 50 ng/ml); normal T lymphoblasts also showed responsiveness at these high insulin concentrations. Preincubation with a monoclonal antibody against the insulin-like growth factor I receptor (alpha IR-3 at 5000 ng/ml) blocked the in vitro effect of physiologic concentrations of insulin-like growth factor and supraphysiologic concentrations of insulin on leprechaun and control T lymphoblast colony formation, but had no clear effect upon the response to physiologic insulin concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Tissues of the Laron dwarf are sensitive to insulin-like growth factor I but not to growth hormone.

Tissues from patients with Laron dwarfism are resistant to the actions of endogenous or exogenous GH. As a result, insulin-like growth factor I (IGF-I) levels are low, possibly contributing to the severe growth deficiency that occurs in patients with this syndrome. In this study, we found that erythroid progenitor cells and permanently transformed T-cell lines from two patients with Laron dwarfism responded in vitro to added IGF-I in concentrations ranging between 1-10 ng/mL despite no stimulatory response to added GH in concentrations of up to 500 ng/mL. Normal or near-normal responsiveness to insulin was also demonstrated. The persistence of GH resistance in the cultured T-cell lines confirms the primary genetic nature of the defect in Laron dwarfism. The preservation of in vitro growth responsiveness to IGF-I in hematopoietic tissue from the Laron dwarfs suggests that affected individuals are sensitive to this factor and may respond to it in vivo.

Adolescent↗
PubMed1987

The role of immunotherapy in type I diabetes mellitus.

Type I diabetes mellitus appears to result from an insidious immunologic destruction of pancreatic beta-cells in genetically susceptible persons exposed to one or a series of environmental insults. This genetic susceptibility is related to alleles located on the sixth chromosome in the HLA-DR or an adjacent region. With superimposition of a viral or other environmental triggering event, cell-and antibody-mediated events are activated that lead to the specific autorejection of beta-cells and consequent insulin deficiency. Immunosuppressive strategies to impede or halt complete destruction of beta-cells, using cyclosporine, have already been initiated in both animals and humans with diabetes mellitus. Because of the potential toxicity of all current immunosuppressive regimens, such therapies cannot, at this time, be considered for wide-scale use in persons with type I diabetes. Reported inductions, however, of insulin independence in patients with newly diagnosed type I diabetes using cyclosporine or other agents underscore the role of the immune system in the pathogenesis of the disease and highlight the need to develop safer, more specific immunomodulation designed to avoid complete beta-cell destruction.

Animals↗
PubMed1986

Growth without growth hormone: evidence for a potent circulating human growth factor.

A potent growth factor was detected in the serum of a child with growth hormone (GH) deficiency and early growth delay whose growth velocity spontaneously increased to supranormal levels despite persistent GH deficiency by both radioimmunoassay (RIA) and radioreceptor assay. Thyroid function, prolactin, insulin response to oral glucose, glucose response to intravenous insulin, and computerised tomography of the head were all normal. Whilst somatomedin-C levels measured by RIA were low or low-normal, in vitro somatomedin bioactivity measured by bioassay was normal, suggesting the presence of a growth factor other than somatomedin-C. By way of confirmation, the patient's serum was incubated with erythroid progenitor cells from peripheral blood of a normal individual and a Laron dwarf. In this system, proliferation of normal erythroid progenitors was almost double that obtained with physiological concentrations of GH or control sera, and Laron erythroid progenitors, which were completely resistant to added GH, also responded strongly to the patient's serum. The patient's growth is therefore independent of GH and other known growth factors.

Child↗