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C N Mariash

Publications and source records attributed to C N Mariash.

At least 37 records · Page 2Linked to original sources
PubMed1993

Location of a glucose-dependent response region in the rat S14 promoter.

The rat S14 gene provides an excellent model to examine the DNA sequences associated with carbohydrate regulation of hepatic gene transcription. We constructed internal deletions within 5 kilobases of the 5'-up-stream region and ligated these to a luciferase reporter gene. The constructs were transfected into primary hepatocytes and pancreatic HIT cells. In hepatocytes, an increase in the medium glucose concentration led to a parallel increase in endogenous mRNA S14 content and transfected luciferase reporter activity driven by 5 kilobases of the S14 promoter. Internal deletions of several sequences from -2706 to -285 each led to a decrease in glucose-stimulated activity, suggesting that multiple elements are necessary for the transcriptional response to glucose. Deletion from -1583 to -1069 nearly abolished the glucose effect in both cell types and delineated the carbohydrate response element (CHORE). The CHORE deletion was specific for glucose, because it did not alter the response to thyroid hormone, another known regulator of this gene. Although the CHORE sequence did not confer glucose activation to either a heterologous promoter or the basal S14 promoter (bases -285 to +19), a 5-fold enhanced response was observed when two copies of the CHORE were ligated to the first 2110 basepairs of the S14 promoter. The results suggest that the CHORE contains a carbohydrate regulatory element and operates as an enhancer in concert with other sequences within the S14 gene.

Animals↗
PubMed1992

Levothyroxine dose requirements for thyrotropin suppression in the treatment of differentiated thyroid cancer.

We have compared the dose of levothyroxine (L-T4) required to suppress serum TSH to given levels in two clinical groups: 1) 44 patients with thyroid cancer whose thyroid glands had been ablated by surgical thyroidectomy and 131I treatment, and 2) 113 patients with thyroidal failure due either to spontaneous primary hypothyroidism (31 patients) or after 131I treatment for Graves' hyperthyroidism (82 patients). The dose of L-T4 needed to attain serum TSH levels in the euthyroid range (0.5-6.2 microU/mL) was significantly greater (P less than 0.01) in patients with thyroid cancer (2.11 micrograms/kg.day) than in the patients with primary hypothyroidism associated with nonmalignant disease (1.63 micrograms/kg.day). Similarly, patients with thyroid cancer required a higher dose of L-T4 to suppress serum TSH to a given subnormal level. These findings suggest that the secretion of hormone from residual thyroid tissue in patients who have not been subjected to near-total thyroid ablation contributes substantially to the circulating levels of serum T4 and T3. We, therefore, infer that residual thyroidal secretion in the patients with hypothyroidism due to benign causes is relatively independent of TSH stimulation. Further subdivision of patients with benign hypothyroidism revealed that patients with Graves' who developed hypothyroidism after 131I treatment showed a lower mean dose requirement than patients with spontaneous hypothyroidism. This raises the possibility that continued secretion of thyroid-stimulating immunoglobulin in such patients might account for the lower dose requirement in the combined group with hypothyroidism. Our studies also have allowed us to make serial observations in 4 patients with thyroid cancer who exhibited elevated levels of serum thyroglobulin. In this limited series, maximal suppression of serum thyroglobulin was produced by doses of L-T4, which reduced circulating TSH to 0.4 mU/L.

Adult↗
PubMed1992

Cell-specific carbohydrate metabolism regulates S14 gene transcription.

Carbohydrate administration rapidly regulates hepatic mRNA-S14 content. Both sucrose and fructose but not glucose increase the transcription of hepatic mRNA-S14 in vivo. In primary hepatocyte cultures, mRNA-S14 transcription responds to either fructose or glucose. To test the hypothesis that the difference in hexose response is due to differences in cellular metabolism, we studied the regulation of this gene with a transient transfection assay system in Chinese hamster ovary (CHO) cells, hamster pancreatic beta-cells (HIT), and primary hepatocytes. In HIT cells, glucose stimulation of the expression vector pS14CAT (5 kilobases [kb]) containing 4.9 kb of 5'-flanking DNA was threefold greater than fructose. Glucose also gave a fourfold greater response at 27.5 mM than at 2.2 mM. In CHO cells, pS14CAT (5 kb) showed a twofold greater response to fructose than to glucose. The differential response to the hexoses in the two cell lines is a result of cell-specific metabolism. Without glucose in the media, both CHO and HIT cells used pyruvate for energy. However, glucose addition to CHO cells enhances glycolysis and hexose shunt pathway activity while inhibiting pyruvate oxidation and S14 gene transcription. In contrast, addition of glucose to HIT cells leads to enhanced tricarboxylic acid cycle activity to oxidize pyruvate and an associated stimulation of S14 transcription. We confirmed these conclusions in primary hepatocyte cultures. Addition of 27.5 mM glucose led to a twofold increase in endogenous mRNA-S14 accumulation, a twofold increase in transfected pS14LUC (5 kb) activity, and a parallel twofold increase in pyruvate oxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Loading and transfer control for Northern hybridization.

We report a simple and inexpensive method to quantitate loading and transfer of RNA and to examine RNA integrity for use with Northern hybridization. This technique involves quantitation by computer-assisted video densitometry of a negative photograph of 28S and 18S rRNA from ethidium bromide-stained RNA fixed to nylon membranes. This method eliminates the issue of variability of expression of "housekeeping" genes and the need for a second round of hybridization to quantitate control probes.

Animals↗
PubMed1991

Dietary sucrose enhances processing of mRNA-S14 nuclear precursor.

The rapid response of rat hepatic mRNA-S14 to hormonal or dietary manipulation makes it an excellent model to study the control of lipogenic enzyme mRNA. The mechanism of regulation of this mRNA by triiodothyronine (T3) or sucrose remains controversial. Although initial studies suggested that T3 stabilized the nuclear precursor, subsequent studies suggest that T3 acts by increasing the transcriptional rate of this gene. More recently, the induction of mRNA-S14 by sucrose administration was shown to be associated with an increase in transcriptional "run-on" activity. Because T3 and carbohydrate feeding synergistically regulate this mRNA, we studied the response to short and long term high carbohydrate feeding in hypothyroid and euthyroid rats. We found the response to the lipogenic diet was rapid in hypothyroid rats, with maximal levels of mRNA-S14 attained by 4 h (2.2 +/- 0.6 chow fed versus 13.5 +/- 2.5 pg/micrograms RNA on lipogenic diet). The rapid induction by the lipogenic diet contrasts with the diminished response to sucrose by gastric gavage (4.6 +/- 1.2 pg/micrograms RNA) over the same time interval. Despite the large increase in the mature mRNA induced by the lipogenic diet, the rise in the nuclear precursor was small and not different from that observed after sucrose gavage (0.14 +/- 0.01 chow, 0.26 +/- 0.03 sucrose gavage, 0.25 +/- 0.04 pg/micrograms RNA lipogenic diet). The molar ratio of the mature to precursor mRNA-S14 showed progressive increases with the smallest level in the fasting rat, an intermediate level in the chow-fed and sucrose gavaged rats, and the highest level in the animals fed a lipogenic diet (2.1, 16.5, 16.3, 62.7, respectively). Based on the previously reported half-life for the mature mRNA-S14, these data show that feeding sucrose by gavage or by a lipogenic diet leads to enhanced fractional conversion of precursor to mature mRNA-S14 with a simultaneous stabilization of the precursor mRNA-S14.

Animals↗
PubMed1991

Local reactions to radioiodine in the treatment of thyroid cancer.

PURPOSE: To compare the rate of local complications resulting from radioiodine ablation of thyroid cancer in patients with a residual intact thyroid lobe to that in patients who had more extensive surgical treatment prior to radioiodine administration. PATIENTS AND METHODS: We retrospectively studied 59 patients who had received 131I between 1979 and 1989. The patients were divided into two groups, depending on the extent of their previous surgical thyroid excision. Group 1 comprised 10 patients with a lobectomy or hemithyroidectomy before the ablative radioiodine dose, and Group 2 comprised 49 patients with more extensive thyroid excision (near-total or subtotal thyroidectomy) before the radioiodine treatment. RESULTS: Sixty percent of the 10 patients in Group 1 experienced some degree of neck pain or tenderness following radioiodine ablation of their residual thyroid. In one case, the local reaction was very severe and accompanied by the development of transient hyperthyroidism. There was only a 6% local complication rate in the patients who had undergone more extensive thyroid excision before ablative therapy (p less than 0.001), and none had a severe reaction. CONCLUSIONS: Patients with only unilateral surgical excision before radioiodine therapy have a higher rate of local complications than do patients treated with more extensive surgery prior to radioiodine ablation. If radioiodine is to be employed in such patients, they should be informed of this possible complication. Since evidence supports a dose effect in the pathogenesis of the complications, we recommend using a dose of less than 30 mCi for the initial ablation in these patients even though it may be necessary to repeat this dose to complete thyroid ablation.

Adult↗
PubMed1990

American Thyroid Association guidelines for use of laboratory tests in thyroid disorders.

Selection of appropriate laboratory determinations will enable the clinician to diagnose thyroid dysfunction readily in the majority of patients. At the present time, estimation of free thyroxine and a "sensitive" thyrotropin assay are recommended as the principal laboratory tests for thyroid disease. A decrease in serum free thyroxine estimate and a raised level of serum thyrotropin confirm the diagnosis of hypothyroidism caused by thyroid gland failure. An increase in free thyroxine estimate combined with a serum sensitive thyrotropin level suppressed to less than 0.1 mU/L establishes the diagnosis of thyrotoxicosis. In sick patients, a normal or raised serum free thyroxine estimate together with a normal level of serum thyrotropin suggests that the patient has neither hypothyroidism nor thyrotoxicosis. Patients with severe illnesses, generally in the intensive care unit, and those treated with certain drugs, as well as individuals with unusual thyroid disorders, may present with confusing laboratory findings. An understanding of the regulation of the thyroid hormone system and/or judicious consultation with an endocrinologist should enable the clinician to diagnose thyroid disease, if present, in such patients.

Female↗
PubMed1990

Quantitation of cytomegalovirus DNA by blot hybridization in blood leukocytes of viremic patients.

We describe a technique for quantitation of viral DNA in blood leukocytes during viremic infection with human cytomegalovirus (CMV). Using a cloned subgenomic DNA probe and a blot hybridization assay, small amounts of viral DNA within samples of leukocyte DNA could be quantitated reproducibly using a videodensitometer. Critical components of the assay were: (1) a direct relationship between optical density and known amounts of viral DNA diluted in cellular DNA as positive standard samples and, (2) determination of the proper duration of autoradiographic exposure. The technique was sufficiently sensitive to detect 10 picograms of CMV DNA in the presence of microgram quantities of host cell DNA. In addition, samples containing minute amounts of CMV DNA could reliably be distinguished from samples that were negative. We have used the technique to characterize the pathogenesis of CMV viremia and to monitor the effects of antiviral chemotherapy. This procedure could easily be applied to pathogenetic studies of a variety of other infectious agents.

Cytomegalovirus↗
PubMed1990

Binding of 3,5,3'-triiodothyronine (T3) and its analogs to the in vitro translational products of c-erbA protooncogenes: differences in the affinity of the alpha- and beta-forms for the acetic acid analog and failure of the human testis and kidney alpha-2 products to bind T3.

We have compared the affinities for T3 and the T3 analog binding characteristics of the in vitro translational products of seven c-erbA cDNAs (chicken c-erbA alpha; human placental c-erbA beta; rat c-erbA beta-1; rat c-erbA alpha-1; rat c-erbA alpha-2; human testis c-erbA alpha-2; and human kidney c-erbA alpha-2). Four of these (chicken c-erbA alpha, human placental c-erbA beta, rat c-erbA beta-1, rat c-erbA alpha-1) bound T3 with high affinity as previously described. When compared under identical conditions of synthesis and [125I]T3 binding, there was no significant difference between the affinity of the chicken c-erb A alpha-1 and the human c-erbA beta but in a more limited series the affinity of rat c-erbA beta-1 for T3 was 4.6-fold higher than that of the rat c-erbA alpha-1. In vitro translational products of the beta-probes showed a characteristic 2.2-fold higher triiodothyroacetic acid/T3 ratio than did the products of the alpha-probes, regardless of the species of origin of the probe. As previously established, the rat c-erbA alpha-2 product did not bind T3. However, in contrast to two published reports, the human testis and kidney alpha-2 probe products also failed to bind T3. These findings indicate that highly conserved C-terminal 37-40 residues are important for high affinity T3 binding by proteins encoded by the c-erb A family of genes.

Amino Acid Sequence↗
PubMed1989

Interaction between fructose and glucose on the regulation of the nuclear precursor for mRNA-S14.

We have examined the mechanism of the carbohydrate induction of rat hepatic mRNA-S14 to the intragastric administration of sucrose and its constituent hexoses, fructose and glucose. A maximal sucrose response (26-fold) was obtained with 2 ml of 60% sucrose/100 g of body weight, yet equimolar concentrations of fructose and glucose were not able to reproduce the response. Fructose yielded less than one-third the response observed with sucrose, whereas glucose administration was ineffective. On the other hand, the simultaneous administration of both hexoses restored the full response observed with sucrose. The synergism between fructose and glucose was not due to the administration of extra calories or enhanced insulin release but was correlated with altered carbohydrate metabolism as reflected by the hepatic pyruvate content (0.058 +/- 0.003 mumol/g fasting, 0.067 +/- 0.009 glucose treated, 0.218 +/- 0.030 fructose treated, 0.292 +/- 0.015 sucrose treated). The time course of induction of mRNA-S14 nuclear precursor in response to fructose, glucose, or sucrose correlated with the mature mRNA-S14 values. In addition, enhanced transcriptional activity of the S14 gene was observed after sucrose feeding (from 25 +/- 8 ppm baseline to 108 +/- 40 ppm at 4 h) and fructose feeding (40 +/- 21 ppm at 4 h). These studies demonstrate that the carbohydrate regulation of mRNA-S14 is due to a synergistic interaction between fructose and glucose reflected in the hepatic pyruvate content and leading to the induction of the nuclear precursor with an associated increase in transcriptional activity of the S14 gene.

Animals↗
PubMed1989

Kinetics of induction by thyroid hormone of the two hepatic mRNAs coding for cytosolic malic enzyme in the hypothyroid and euthyroid states. Evidence against an obligatory role of S14 protein in malic enzyme gene expression.

In rat liver, triiodothyronine (T3) and dietary carbohydrate induce the expression of the genes coding for malic enzyme (ME) (EC 1.1.1.40) and S14 protein. The mRNAs for both ME and S14 are elevated under circumstances associated with augmented lipogenesis. Since the lag time in the induction of mRNA coding for S14 is short (20 min) and the lag time in the induction of the mRNA for ME is relatively long (2-6 h), the possibility arose that the induction of the ME gene by T3 was mediated by S14 protein. To test this hypothesis we examined the temporal relationship between the accumulation of the hepatic S14 protein and the mRNAs coding for ME. In confirmation of previous reports, we found that two mRNAs coded for ME, one 27 S and the other 21 S in size. The level of enzyme activity generated appeared to be determined by both mRNA species. Sequencing of the 27 S fragment established that this mRNA is generated as a consequence of the use of an alternate polyadenylation site downstream to that used in the 21 S mRNA. Unanticipated from the earlier descriptions was the finding of a markedly asynchronous response of these mRNAs to T3 in hypothyroid animals. The lag time following T3 administration was 90 min for the 27 S and fully 8-12 h for the smaller 21 S sequence. Despite the rapid rise of mRNA S14, the S14 protein could not be detected for approximately 12 h after T3 administration. This ruled out the possibility that S14 is an obligate mediator in the induction of the ME gene. A contrasting pattern was observed in the euthyroid state where both ME mRNAs had indistinguishable lag times of 2-3 h, and the S14 protein rose within the same time frame. The delayed response of the 21 S mRNA for malic enzyme in hypothyroid animals thus appears to be due to a reversible defect in the transcription of the ME gene.

Animals↗
PubMed1989

A novel hepatic nucleotide is correlated with the carbohydrate induction of messenger ribonucleic acid-S14.

To determine whether the rapid response of hepatic mRNA-S14 to carbohydrate feeding was associated with an alteration in a specific hepatic nucleotide, acid extracts of liver tissue were analyzed by ion-paired reverse phase HPLC. A nucleotide present in nanomoles per g quantity correlated with the induction of this mRNA by sucrose. Four hours after sucrose feeding the content of this compound was 7 times greater than that in fasted rats. Furthermore, the response was rapid, attaining maximal levels 30 min after feeding, and remaining elevated for at least 4 h. The content of this nucleotide also correlated with the content of mRNA-S14 in the steady state, with the lowest levels of both mRNA-S14 and this nucleotide in fasted rats, intermediate levels in rats maintained on a regular chow diet, and the highest levels in rats fed a 60% sucrose diet for 4 days. Lastly, while the response of mRNA-S14 to thyroid hormone and sucrose is synergistic, the thyroidal state does not influence the response of this compound to sucrose. Thus, the interaction of thyroid hormone and sucrose on mRNA-S14 is distal to the generation of this compound. Based on the UV spectrum, HPLC retention, and [3H]adenosine labeling, this compound contains adenine. However, it is not any of the common adenine-containing mono- or oligonucleotides. These data indicate that a novel hepatic nucleotide is induced by sucrose and raise the possibility that this nucleotide is responsible for the induction of carbohydrate-responsive mRNAs.

Adenine Nucleotides↗
PubMed1988

Triiodothyronine rapidly reverses inhibition of S14 gene transcription by glucagon.

The rapid response of hepatic mRNA-S14 to T3 has made this sequence an important model for studying the mechanism of hormonal induction of gene expression. In previous studies we showed, in the intact rat, that glucagon administration during the peak of the mRNA S14 diurnal rhythm causes a monoexponential fall in the level of mRNA-S14, and that T3 reverses this effect. We have now defined more precisely the mechanism governing this interaction. Measurement of in vitro nuclear transcriptional rates shows that T3 can reverse the glucagon-induced reduction of mRNA-S14 transcription. Reversal can be demonstrated within 5 min after the iv injection of T3. Further, the reversal appears to be related to the occupation of specific nuclear receptors, as inferred from the calculated nuclear occupancy and the effects of various iodothyronine analogs of T3. These results suggest that the effects of T3 are mediated by varying rates of production of the nuclear precursor and not by its stabilization, as previously proposed. Ancillary evidence supporting this conclusion came from the demonstration that the apparent t1/2 of the 4.5-kilobase precursor was not prolonged by T3.

Animals↗
PubMed1988

Hypercortisolism due to an autonomously functioning pituitary adenoma: limitations in diagnostic test procedures.

We report a patient with pituitary-dependent Cushing's syndrome in whom standard biochemical testing procedures failed to define the pituitary as the source of autonomous hormone secretion. Anomalous findings included: 1) wide variations of urinary steroid excretion during a 4-day dexamethasone suppression test, 2) a rise of the serum cortisol after the single dose (8 mg) overnight dexamethasone suppression test, 3) a diminished serum 11-deoxycortisol response to the metyrapone test, and 4) an absent plasma ACTH response to CRH. While the results of these studies were most consistent with an ectopic source of ACTH production, magnetic resonance imaging suggested that Cushing's syndrome was due to a pituitary adenoma. The adenoma was removed by transphenoidal surgery. However, serum and urinary steroid levels remained measurable for 2 weeks because of the perioperative use of im cortisone acetate. Subsequent im administration of 200 mg cortisone acetate again led to prolonged serum and urinary steroid responses to this compound, thus emphasizing the pitfalls that may accompany the perioperative use of cortisone acetate. This patient demonstrates the importance of performing multiple tests, including magnetic resonance image scanning, in evaluation Cushing's syndrome, since standard biochemical testing may not indicate pituitary ACTH hypersecretion as the cause.

Adenoma↗
PubMed1988

Human lymphocyte messenger RNA activity profiles in type I and type II diabetes: a tool for classification of metabolic disease.

We have previously used rat hepatic messenger ribonucleic acid (mRNA) activity profiles to categorize various pathophysiologic states. To test the hypothesis that similar techniques can be used to categorize disease states in humans, we examined the mRNA activity profiles by using in vitro translational assays of Ficoll-Hypaque-separated mononuclear cells obtained from six normal volunteers, six patients with type I diabetes, and five patients with type II diabetes as example of different disease states. Translated proteins were labeled with sulfur 35-labeled methionine, separated by two-dimensional gel electrophoresis, and quantitated by videodensitometry of autoradiographs derived from the two-dimensional gels. Of approximately 160 quantitated mRNAs, the levels of 12 were found to be altered in one of the diabetic states. The values of nine were changed in patients with type I diabetes and the values of 11 were altered in patients with type II diabetes. Although the values of most mRNAs increased, significant decreases were also observed. Moreover, four spots showed significant differences in response between the two diabetic states. Discriminant analysis allowed the separation of all three states. Finally, several mRNAs also displayed an age-related correlation. We have demonstrated that unstimulated mononuclear cell mRNAs can be used to study the effects of pathophysiologic states on gene expression in humans. Furthermore, our results support the potential use of this issue to study the effect of a wide variety of disease states on gene expression.

Adult↗
PubMed1988

Hyperprolactinemia, infertility, and hypothyroidism. A case report and literature review.

A 30-year-old woman presented with infertility, hyperprolactinemia, and pituitary enlargement. Although relatively asymptomatic, she was found to have primary hypothyroidism. She became pregnant within a month following institution of levothyroxine replacement, and the pituitary enlargement resolved within one year. We discuss the relationship between hypothyroidism, hyperprolactinemia, and pituitary enlargement. This case emphasizes the need for thyroidal status evaluation in patients with presumptive prolactin-producing pituitary tumors before initiation of therapy for the hyperprolactinemia.

Adenoma↗