PubMed Health⌕ Search

Biomedical subjects

H J Hirsch

Publications and source records attributed to H J Hirsch.

At least 19 recordsLinked to original sources
PubMed2001

Single and double overexpression of C(4)-cycle genes had differential effects on the pattern of endogenous enzymes, attenuation of photorespiration and on contents of UV protectants in transgenic potato and tobacco plants.

To improve the efficiency of CO(2) fixation in C(3) photosynthesis, C(4)-cycle genes were overexpressed in potato and tobacco plants either individually or in combination. Overexpression of the phosphoenolpyruvate carboxylase (PEPC) gene (ppc) from Corynebacterium glutamicum (cppc) or from potato (stppc, deprived of the phosphorylation site) in potato resulted in a 3-6-fold induction of endogenous cytosolic NADP malic enzyme (ME) and an increase in the activities of NAD-ME (3-fold), NADP isocitrate dehydrogenase (ICDH), pyruvate kinase (PK), NADP glycerate-3-P dehydrogenase (NADP-GAPDH), and PEP phosphatase (PEPP). In double transformants overexpressing cppc and chloroplastic NADP-ME from Flaveria pringlei (fpMe1), cytosolic NADP-ME was less induced and pleiotropic effects were diminished. There were no changes in enzyme pattern in single fpMe1 overexpressors. In cppc overexpressors of tobacco, the increase in endogenous cytosolic NADP-ME activity was small and changes in other enzymes were less pronounced. Determinations of the CO(2) compensation point (Gamma*) as well as temperature and oxygen effects on photosynthesis produced variational data suggesting that the desired decline in photorespiration occurred only under certain experimental conditions. Double transformants of potato (cppc/fpMe1) exhibited the most consistent attenuating effect on photorespiration. In contrast, photorespiration in tobacco plants appeared to be diminished most in single cppc overexpressors rather than in double transformants (cppc/fpMe1). In tobacco, introduction of the PEP carboxykinase (PEPCK) gene from the bacterium Sinorhizobium meliloti (pck) had little effect on photosynthetic parameters in single (pck) and double transformants (cppc/pck). In transgenic potato plants, increased PEPC activities resulted in a decline in UV protectants (flavonoids) in single cppc or stppc transformants, but not in double transformants (cppc/fpMe1). PEP provision to the shikimate pathway inside the plastids, from which flavonoids derive, might be restricted only in single PEPC overexpressors.

Asteraceae↗
PubMed1998

Parathyroid adenoma after radiation in an 8-year-old boy.

We describe an 8-year-old boy who had asymptomatic hypercalcemia 4 years after radiotherapy involving the left orbit and lungs. A right parathyroid adenoma was diagnosed, and normocalcemia was achieved after its removal. Routine monitoring of serum calcium and phosphate levels is recommended for children after head and neck irradiation.

Adenoma↗
PubMed1996

Effects of altered phosphoenolpyruvate carboxylase activities on transgenic C3 plant Solanum tuberosum.

Phosphoenolpyruvate carboxylase (PEPC) genes from Corynebacterium glutamicum (cppc), Escherichia coli (eppc) or Flaveria trinervia (fppc) were transferred to Solanum tuberosum. Plant regenerants producing foreign PEPC were identified by Western blot analysis. Maximum PEPC activities measured in eppc and fppc plants grown in the greenhouse were doubled compared to control plants. For cppc a transgenic plant line could be selected which exhibited a fourfold increase in PEPC activity. In the presence of acetyl-CoA, a known activator of the procaryotic PEPC, a sixfold higher activity level was observed. In cppc plants grown in axenic culture PEPC activities were even higher. There was a 6-fold or 12-fold increase in the PEPC activities compared to the controls measured in the absence or presence of acetyl-CoA, respectively. Comparable results were obtained by transient expression in Nicotiana tabacum protoplasts. PEPC of C. glutamicum (PEPC C.g.) in S. tuberosum leaf extracts displays its characteristic K(m) (PEP) value. Plant growth was examined with plants showing high expression of PEPC and, moreover, with a plant cell line expressing an antisense S. tuberosum (anti-sppc) gene. In axenic culture the growth rate of a cppc plant cell line was appreciably diminished, whereas growth rates of an anti-sppc line were similar or slightly higher than in controls. Malate levels were increased in cppc plants and decreased in antisense plants. There were no significant differences in photosynthetic electron transport or steady state CO2 assimilation between control plants and transformants overexpressing PEPC C.g. or anti-sppc plants. However, a prolonged dark treatment resulted in a delayed induction of photosynthetic electron transport in plants with less PEPC. Rates of CO2 release in the dark determined after a 45 min illumination period at a high proton flux density were considerably enhanced in cppc plants and slightly diminished in anti-sppc plants. When CO2 assimilation rates were corrected for estimated rates of mitochondrial respiration in the light, the electron requirement for CO2 assimilation determined in low CO2 was slightly lower in transformants with higher PEPC, whereas transformants with decreased PEPC exhibited an appreciably elevated electron requirement. The CO2 compensation point remained unchanged in plants (cppc) with high PEPC activity, but might be increased in an antisense plant cell line. Stomatal opening was delayed in antisense plants, but was accelerated in plants overexpressing PEPC C.g. compared to the controls.

Amino Acids↗
PubMed1996

Adrenal suppression among asthmatic children receiving chronic therapy with inhaled corticosteroid with and without spacer device.

BACKGROUND: Inhaled corticosteroids have become a first-line treatment for chronic asthma. It has been shown that inhaled corticosteroids can have a measurable effect on the hypothalamic-pituitary-adrenal axis in asthmatic children. OBJECTIVE: To investigate the prevalence of adrenal suppression among asthmatic children receiving chronic therapy with low to moderate doses (up to 1000 micrograms) of inhaled beclomethasone dipropionate via a metered dose inhaler (MDI) and via MDI attached to a spacer device (MDI-spacer). METHODS: The study included 39 asthmatic children currently undergoing therapy; 24 received beclomethasone dipropionate by MDI attached to a spacer, and 15 directly by MDI. All the patients had been treated for at least 4 months. Another 21 children were normal controls. The 24-hour urinary free cortisol excretion was measured to evaluate hypothalamic-pituitary-adrenal axis function. RESULTS: Seven of 15 (47%) patients from the MDI group had reduced 24 hour-urinary free cortisol excretion and 2 of 24 (8%) in the MDI-spacer group (P = .006). The mean 24-hour urinary free cortisol excretion of the MDI group was 0.0185 +/- 0.0089 microgram/gram creatinine, and the MDI-spacer and the control groups were, 0.0290 +/- 0.0138 microgram/gram creatinine and 0.0270 +/- 0.0118 microgram/gram creatinine, respectively, (P = 0.37, f = 3.51 ANOVA). CONCLUSION: Chronic inhalation of low to moderate doses of corticosteroids is associated with adrenal suppression in some asthmatic children. This side effect is more common among patients inhaling directly from the MDI and is less frequent when a large volume spacer is attached to the MDI.

Administration, Inhalation↗
PubMed1993

Cloning, sequence analysis and expression of a cDNA encoding active phosphoenolpyruvate carboxylase of the C3 plant Solanum tuberosum.

A cDNA coding for phosphoenolpyruvate carboxylase (PEPC) was isolated from a cDNA library from Solanum tuberosum and the sequence of the cDNA was determined. It was inserted into a bacterial expression vector and a PEPC- Escherichia coli mutant could be complemented by the cDNA construct. A functional fusion protein could be synthesized in E. coli. The properties of this PEPC protein clearly resembled those of typical C3 plant enzymes.

Amino Acid Sequence↗
PubMed1993

Persistent hyperinsulinemic hypoglycemia of infancy: long-term octreotide treatment without pancreatectomy.

Eight patients with persistent hyperinsulinemic hypoglycemia of infancy who were treated with octreotide without pancreatectomy are described. All had severe, early-onset disease that would have required partial pancreatectomy had octreotide not been available. Along with octreotide, frequent feedings and raw cornstarch at night were required by all. Octreotide was given in three or four daily subcutaneous injections in four patients and in a continuous subcutaneous infusion with an insulin infusion pump in four. All had mild, transient gastrointestinal symptoms (vomiting, abdominal distention, steatorrhea) after the start of therapy. Asymptomatic gallstones were found in 1 patient after 1 year of treatment. No other long-term untoward effects were noted, including no detrimental effect on psychomotor development. Growth was not affected in five of six patients treated for more than 6 months. In five patients, octreotide was discontinued after 9 months to 5 1/2 years; patients were given diazoxide instead, two required percutaneous gastrostomy, and one 5 1/2-year-old child required no further treatment. The remaining three patients (aged 5 to 9 months) are still being treated with octreotide. We conclude that, with the use of octreotide, pancreatectomy can be avoided in some patients. Particularly in light of our findings of a high incidence of diabetes years after partial pancreatectomy, and clinical improvement after months to years of octreotide treatment, we believe that aggressive medical therapy, when effective, is preferable to partial pancreatectomy.

Diazoxide↗
PubMed1992

Cloning and nucleotide sequence of the Escherichia coli K-12 ppsA gene, encoding PEP synthase.

We have cloned and sequenced the Escherichia coli K-12 ppsA gene. The ppsA gene codes for PEP synthase, which converts pyruvate into phosphoenolpyruvate (PEP), an essential step in gluconeogenesis when pyruvate or lactate are used as a carbon source. The open reading frame consists of 792 amino acids and shows homology with other phosphohistidine-containing enzymes that catalyze the conversion between pyruvate and PEP. These enzymes include pyruvate, orthophosphate dikinases from plants and Bacteroides symbiosus and Enzyme I of the bacterial PEP:carbohydrate phosphotransferase system.

Amino Acid Sequence↗
PubMed1990

Compensated hypothyroidism presenting with galactorrhoea.

Compensated hypothyroidism was diagnosed in a 36-year-old female who presented with breast tenderness and mild galactorrhoea. T4 was 5.8 mcg dl-1 and T3RU was 22.5%, while TSH and prolactin were very mildly elevated (6.5 mU ml-1 and 26.1 ng ml-1, respectively). The TRH test showed an exaggerated response. TSH increased to 43 mU ml-1, and prolactin levels reached 161 ng ml-1. Treatment with T4 decreased the TSH and prolactin levels to within the normal range, and prevented the galactorrhoea. The case presented here demonstrates that galactorrhoea can be present even with mild hypothyroidism.

Adult↗
PubMed1986

Evolution of hypothyroidism in familial goitre due to deiodinase deficiency: report of a family and review of the literature.

We studied two sisters who developed large non-toxic goitres in adolescence. Deiodinase deficiency was diagnosed by a rapid thyroid uptake of radioactive iodine (RAI) at 2 hours associated with a marked fall in thyroidal 131I by 24 hours. Serial RAI scans in the second patient documented evolution of the iodine-deficient state. Conservation of intra-thyroidal iodine stores was maintained by avid iodine uptake and failure to release organified 131I. With progressive loss of inorganic iodine, hypothyroidism developed, associated with a rise in serum TSH which further exacerbated the loss of iodine. Treatment with L-thyroxine resulted in an improvement of thyroid function, but normalization was achieved only after small doses of Lugol's iodine were administered. These studies illustrate the variable nature and late onset of an inborn error of thyroid metabolism. This family supports an autosomal recessive mode of inheritance for deiodinase deficiency. We have documented progression from a euthyroid to hypothyroid state resulting from decompensation of iodine conservation mechanisms.

Adult↗
PubMed1986

Iodine-induced hyperthyroidism in a patient with a normal thyroid gland.

Iodine-induced hyperthyroidism can develop even in the presence of an otherwise normal gland. One of the less common sources of iodine is tablets of seaweed, sold over the counter without prescription. We report the case of a 72 year old female who developed clinical and laboratory evidence of hyperthyroidism while ingesting sea-kelp (Vitalia) tablets. Six months after stopping the tablets, the symptoms and laboratory evidence of hyperthyroidism had disappeared. No evidence of pre-existing thyroid disease was found.

Aged↗
PubMed1984

TSH secretion in thalassemia.

Thyroid function has been evaluated in 6 prepubertal male and 9 female thalassemic patients. Four of the latter were sexually immature (Group I), with very low estradiol levels and the remainder had more advanced sexual development (Group II). Subjects were challenged with TRH and the response compared to adult controls and a group of 15 males aged 13-18 years with constitutional delayed adolescence. All patient groups and controls had normal levels of T4, T3 and T3 resin uptake. When compared to adult controls or males with constitutional delayed adolescence, the male thalassemic patients had increased basal TSH levels with an exaggerated response to TRH. Long term testosterone enanthate led to a decrease in integrated TSH secretion, showing that androgens may decrease the TSH response to TRH. The more sexually mature females of Group II also had increased basal and stimulated TSH levels; however, the sexually immature females of Group I had basal TSH and TSH responses to TRH equivalent to female controls. In Group I patients there were, moreover, no changes in TSH response during administration of estradiol valearate for 3 months and conjugated estrogens for 8 months. The high basal and stimulated TSH levels in the males and Group II females are most likely due to subclinical primary hypothyroidism. This has been previously described in thalassemia. On the other hand, failure of estrogens to increase the TSH response to TRH in Group I females is evidence of pituitary involvement, which is also well documented in this clinical condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Hormonal profile after insulin-induced hypoglycemia in chronic calcific pancreatitis. Pancreatic, pituitary and adrenal responses.

The present investigation defined the pattern of pancreatic, pituitary and adrenal responses after insulin-induced hypoglycemia in chronic calcific pancreatitis (CCP) related to alcohol abuse, and assessed the role of some of these hormones in the counterregulation of blood glucose. We studied 6 Black men with recently diagnosed CCP, all showing radiological evidence of pancreatic calcification and normal glucose tolerance, as well as 7 matched nonobese male controls. After a standard iv insulin tolerance test inducing marked hypoglycemia, patients with CCP showed significantly impaired mean plasma pancreatic glucagon and pancreatic polypeptide responses compared to the controls. Mean basal plasma somatostatin levels tended to be higher in chronic pancreatitis and remained so throughout the test without altering consistently; in the controls somatostatin peaked significantly at 30 min. Concerning extrapancreatic hormonal changes, plasma growth hormone, prolactin and total catecholamines responded normally in CCP, but plasma cortisol rose to significantly higher levels than controls at 60 and 120 min after the injection of insulin. This, coupled with the brisk output of catecholamines, may have prevented the heightened sensitivity to insulin anticipated because of their hypoglucagonemia. We conclude that patients with CCP show impaired pancreatic hormone release after insulin hypoglycemia with the exception of somatostatin; there is also an excessive rise in plasma cortisol, possibly related to the long standing abuse of alcohol in the past.

Adrenal Glands↗
PubMed1984

Hyperthyroidism due to inappropriate TSH secretion with associated hyperprolactinaemia--a case report and review of the literature.

A patient with inappropriate thyrotrophin (TSH) secretion is described. She initially presented with classical hyperthyroidism during pregnancy, responded to propylthiouracil and, subsequently, had a normal delivery. Hyperthyroidism persisted and 7.5 months later a subtotal thyroidectomy was performed. After a further 16 months, mild symptoms of hyperthyroidism recurred. She again responded to propylthiouracil, but developed galactorrhoea. At that stage, it was noted that she had persistently elevated circulating TSH in the presence of elevated T4 and T3 levels. Her symptomatology was mild, although objective indices of thyroid activity, including pulse rate, BMR, sex hormone binding globulin and cholesterol, were indicative of hyperthyroidism. CT scan and tomography of the sella were normal. She had a markedly exaggerated TSH response to thyrotrophin releasing hormone (TRH). Basal TSH and responsiveness to TRH was suppressed by high dose dexamethasone. The TSH response to TRH was partially suppressed by exogenous T3, but there was no effect on basal TSH levels. TSH also decreased slightly with L-dopa and bromocriptine. Circulating TSH rose markedly during methimazole administration. TSH alpha and beta subunits were elevated and appropriate for the high TSH. In addition, both subunits increased following TRH. The patient had basal hyperprolactinaemia with an impaired prolactin (PRL) response to TRH and metoclopramide. PRL suppressed with L-dopa and bromocriptine. The remaining anterior pituitary function was intact. Most of the laboratory findings argue against the presence of a TSH producing pituitary tumour and the most likely cause for inappropriate TSH secretion in this patient is selective resistance of the thyrotroph to thyroid hormones. A mild element of peripheral resistance might also be present. The hyperprolactinaemia could be related to lactotroph resistance to thyroid hormone. The complexities of treatment in this patient are stressed. Therapy was initially attempted with low dose dexamethasone, but this had no effect. T3 treatment produced an exacerbation of her symptomatology and did not influence basal TSH, thyroid hormones, or 131I uptake. Bromocriptine administration for 11 months partially suppressed basal TSH without influencing T3 and there was an increase in T4. Methimazole did decrease her T4 and T3, but TSH and PRL rose to even greater levels. Her hyperthyroidism was eventually controlled with an ablative dose of 131I. Thyroid hormone will be given in an attempt to suppress her TSH.

Adult↗
PubMed1984

Weaver-Smith syndrome. A case study with long-term follow-up.

We studied a 6-year-old-boy who was followed up from infancy and who had Weaver-Smith syndrome (WSS), a syndrome characterized by excessive growth, dysmorphic facies, psychomotor retardation, and specific radiologic features. The child's height and bone age were far greater than his chronological age and he demonstrated hypothyroidism at the age of 6 years, but had no endocrinologic abnormalities when he was examined at 11 months of age and again at 4 years of age. We compared the clinical and laboratory features of this child with all other reported cases of WSS.

Age Determination by Skeleton↗