bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dietary magnesium supplements improve B-cell response to glucose and arginine in elderly non-insulin dependent diabetic subjects
Authors: Paolisso G. , Passariello N. , Pizza G. , Marrazzo G. , Giunta R. , Sgambato S. , Varricchio M. , D'Onofrio F. 
Published: December 2008

Abstract.
Hypomagnesemia and low erythrocyte magnesium content are both common findings in non-insulin-dependent diabetic subjects. Moreover, intracellular magnesium may play a crucial role in modulating B-cell response to glucose by interfering with potassium permeability. Eight elderly, moderately obese, non-insulin-dependent diabetic subjects were treated with either magnesium supplementation (3 g/day) to the diet or placebo. Both treatment schemes lasted 4 weeks and were separated by a 'wash-out' of 3 weeks. At the end of each treatment period, an iv glucose tolerance test (0.33 g/kg for 3 min) and an iv arginine (5 g) test were performed to determine the B- and A-cell responses. Dietary magnesium supplementation vs placebo produced a slight but significant decrease in basal plasma glucose (8.6 ± 0.3 vs 8.0 ± 0.1 mmol/l, p < 0.05) and an increase in acute insulin response after iv glucose (37.1 ± 2.3 vs −14.7 ±0.9 pmol · 1−1 · (10 min)−1, p < 0.01) and after iv arginine (151 ± 22 vs 81 ± 15 pmol · 1−1 · (10 min)−1, p < 0.01), respectively. Plasma glucagon levels were unaffected by chronic dietary magnesium supplementation as well under basal conditions as in response to arginine. Net increase in acute insulin response after iv glucose and after iv arginine was significantly correlated to the net increase in erythrocyte magnesium content after dietary magnesium supplementation. We conclude that magnesium administration may be a useful adjuvant to the classic hypoglycemic agents in the treatment of non-insulin-dependent diabetic subjects.
Serum levels of vitamin D metabolites in the elderly
Authors: Aksnes Lage , Rødland Ole , Ødegaard Ole R. , Bakke Kåre J. , Aarskog Dagfinn 
Published: December 2008

Abstract.
The serum concentrations of 25-dihydroxyvitamin D, 1,25-dihydroxyvitamin D, 24,25-dihydroxyvitamin D, vitamin D-binding protein, PTH and calcitonin were measured in three groups of elderly Norwegian subjects (age 70–96 years): active elderly living at home, warded geriatric patients not supplemented with vitamin D, and warded geriatric patients supplemented with a daily dose of 400 IU vitamin D2. The results were compared with the concentrations of vitamin D metabolites found in a group of young and middle-aged adults (age 22–59 years). Decreased serum concentrations of 25-dihydroxyvitamin D3 were found in all groups of elderly compared with younger adults. Active elderly living at home had higher concentrations of 25-dihydroxyvitamin D3 than geriatric ward patients. Supplementation of geriatric ward patients with 400 IU vitamin D2 resulted in an increase in the median serum 25-dihydroxyvitamin D concentration by about 30 nmol/l. Decreased median concentration of 1,25-dihydroxyvitamin D was found in geriatric ward patients not supplemented with vitamin D, indicating that this group is at risk of vitamin D deficiency. The active elderly living at home and the warded geriatric patients receiving vitamin D supplementation had normal median concentrations of 1,25-dihydroxyvitamin D, indicating that nephrogenous synthesis of 1,25-dihydroxyvitamin D is not generally impaired in the elderly, and that a moderate vitamin D supplementation may correct low 1,25-dihydroxyvitamin D levels owing to vitamin D deficiency. However, the serum concentrations of 1,25-dihydroxyvitamin D showed great individual variations. No significant differences were observed for vitamin D-binding protein, 'free-1,25-dihydroxyvitamin D' or PTH between the groups. The median serum concentrations of 24,25-dihydroxyvitamin D were significantly lower in all three groups of elderly compared with the younger adults.
Aggravation of hypoglycemia in insulinoma patients by the long-acting somatostatin analogue octreotide (Sandostatin®)
Authors: Stehouwer C. D. A. , Lems W. F. , Fischer H. R. A. , Hackeng W. H. L. , Naafs M. A. B. 
Published: December 2008

Abstract.
Recently somatostatin analogues were successfully used to control insulin-induced hypoglycemia in patients with insulinoma. We observed a transient decrease in glucose levels and symptomatic hypoglycemia after administration of the long-acting somatostatin analogue octreotide (Sandostatin®) in two insulinoma patients. We studied the acute effects of octreotide (administered before breakfast) on blood glucose and glucoregulatory hormones in these patients. In one patient, we studied the effects of glucagon replacement and changing the time of breakfast (relative to octreotide administration) on octreotide-associated changes in blood glucose and glucoregulatory hormones. Compared with control levels, octreotide therapy reduced insulin levels. During hypoglycemia glucagon and growth hormone levels were suppressed, but cortisol levels appropriately increased. The increase in catecholamine levels was normal in one patient, but markedly attenuated in the other. A transient decrease in serum glucose after octreotide was absent after glucagon replacement, but present when breakfast was taken before administration of octreotide. We conclude that in patients with insulinoma, octreotide therapy may be associated with clinically important hypoglycemia, during which counterregulatory hormone secretion may be attenuated.
Human serum LH inhibitor(s): behaviour and contribution to in vitro bioassay of LH using dispersed mouse Leydig cells
Authors: Ding Ying-Qing , Huhtaniemi Ilpo 
Published: December 2008

Abstract.
The present study aimed at investigating the nature and causes of non-parallelism in testosterone responses to serial dilutions of peripheral serum and standard LH preparations in the mouse Leydig cell in vitro bioassay of LH. Immunoadsorption with monoclonal antibody to the β-subunit of LH was used to obtain LH-free serum; the procedure removed more than 98% of the immunoassayable LH. When a constant amount of the LH-free serum was added to standard dilutions, the bioassay dose-response curves to serum dilutions and standards became parallel, i.e. the well-known source of error of this assay system was eliminated. When standard curves prepared in medium and LH-free serum (final concentration 10%) were compared, no effect of the serum was found on basal cAMP and testosterone production. However, the LH-stimulated testosterone and cAMP production were suppressed by serum by a rather constant factor of 40%. Mild heating (60°C, 15 min) or treatment with dextran-coated charcoal, but not ether extraction, was able to eliminate the inhibitory activity of the LH-free serum. Binding studies demonstrated that [125I]hCG interaction with mouse Leydig cell homogenates was inhibited by LH-free serum in a fashion indicative of reduced LH receptor number, but not of reduced binding affinity. In conclusion, these data show that human serum contains LH inhibitor(s) which affect the LH-receptor interaction and LH stimulated testosterone production in mouse Leydig cell in vitro. The effect is marked in serum concentration over 1.5% and it shows only minor variation between individual sera. This source of error can be effectively removed from the LH in vitro bioassay by using LH-free serum for preparation of dilutions of LH standards.
Human antral fluid IGF-I and oocyte maturity: effect of stimulation therapy
Authors: Roussie M. , Royère D. , Guillonueau M. , Lansac J. , Muh J. P. 
Published: December 2008

Abstract.
Studies in animals have highlighted a possible role for growth factors, particularly IGF-I on cellular replication and cytodifferentiation in the ovary. At this time, few studies have been performed about IGF-I in the human ovary. From 38 women undergoing in Vitro Fertilization 293 antral fluids were collected and assessed for steroids (estradiol and progesterone), FSH and IGF-I. Two induction treatments were compared: clomiphene citrate/hMG (group A, N = 15), triptoreline/hMG (group B, N = 23). We also studied relationships between quantitative parameters and oocyte collection or oocyte corona cumulus complex maturity. In group B, the highest antral estradiol levels were found in follicles yielding an oocyte (p <0.05). Concerning antral progesterone, higher levels were observed in follicles collected from group A than in follicles collected from group B (p < 0.05); for this parameter, the highest levels were observed when an oocyte was harvested, whatever the treatment (p <0.05). Highest antral FSH levels were observed in group B (p <0.05). IGF-I levels were higher in follicles collected from group B than in follicles collected from group A (p <0.05) and antral IGF-I levels differed between mature and immature oocyte corona cumulus complex in group B (p <0.05). These results, which are in keeping with studies about biological action of IGF-I in animal or human follicles or granulosa cells, led us to hypothesize a role for IGF-I in human follicular recruitment and maturation, a role that possibly is enhanced during GnRH analogue and gonadotropin therapy.
Effects of thyroid hormones on cartilage sulphation in sex-linked dwarf chickens
Authors: Hoshino S. , Wakita M. , Kobayashi Y. , Kakegawa T. , Suzuki M. 
Published: December 2008

Abstract.
The present investigation was undertaken to see if exogenous thyroid hormone could stimulate cartilage sulphation in vivo and in vitro in sex-linked dwarf chickens. L-thyroxine or L-3,5,3'-triiodothyronine injection for 7 consecutive days stimulated in vivo 35SO2−4 incorporation into trachea cartilages of the dwarf chicken. Both thyroid hormones added to the incubation medium with or without 2.5% dwarf chicken serum also stimulated in vitro 35SO2−4 incorporation into pelvic rudiment from 11-day chick embryos. These data demonstrate that thyroid hormones, like insulin-like growth factor I, might be responsible for the reduced growth rate of dwarf chickens.
Does prolonged dopaminergic blockade alter the LH pulsatile secretion in normal cycling and postmenopausal women?
Authors: Rossmanith Winfried G. , Wirth Ulrike , Yen Samuel S. C. 
Published: December 2008

Abstract.
To investigate effects of prolonged dopaminergic antagonism on LH pulsatile secretion, 22 normal cycling women (10 in the early follicular phase (days 3 and 4), 6 in the late follicular phase (days 10 to 13), 6 in the midluteal phase (days 6 to 8 after ovulations)) and 8 postmenopausal women were studied before and during 8-h dopamine receptor blockade imposed by metoclopramide. Sequential 8-h infusions of either saline (50 ml/h) or metoclopramide (30 μg · kg−1 · h−1) were conducted on two consecutive days. LH pulsatile activity was assessed in blood samples obtained at 15 min intervals during these 8-h infusion periods. Basal estradiol and progesterone concentrations were lowest (p <0.001) in postmenopausal and highest (p <0.001) in the midluteal phase women, 8-h metoclopramide infusions evoked prompt (within 90 min, p <0.001) and sustained (> 70 μg/1, p < 0.001) increases of PRL, similar (p = 0.78)) in magnitude for normal cycling and postmenopausal women. Metoclopramide infusions failed to significantly modify the LH pulsatile acitivity during the menstrual cycles and in hypogonadal women. These observations suggest that even in the presence of high circulating estradiol and progesterone concentrations the dopaminergic inhibition may not be operating. However, any possible stimulatory effect on LH secretion by dopamine receptor blockade may be confounded by the concomitant metoclopramide-induced hyperprolactinemia.
Serum thyroglobulin during the menstrual cycle, during pregnancy, and post partum
Authors: Rasmussen Nini G. , Hornnes Peter J. , Hegedüs Laszlo , Feldt-Rasmussen Ulla 
Published: December 2008

Abstract.
Serum thyroglobulin, TSH, thyroid hormones and thyroid volume were investigated during the menstrual cycle in 10 healthy females (day 2, 9, 16, 23 and day 2 of next cycle), during pregnancy (week 18, 24, 30 and 36) and post partum (1, 2, 3, 6 and 12 months) in 20 healthy females. During the menstrual cycle median serum thyroglobulin increased from 27 (day 2) to 32 μg/l (day 23, p < 0.01 ). Serum TSH and thyroid volume demonstrated a similar increase with a positive correlation between serum thyroglobulin and thyroid volume (r = 0.65, p < 0.02). Median serum thyroglobulin was significantly increased during the whole pregnancy (week 36, 73 μg/l) compared with post partum (1 month post partum, 22 μg/l, p < 0.01), as was thyroid volume. Serum TSH was unaltered and free thyroid hormone indices decreased during pregnancy compared with post partum. No relation between changes in serum thyroglobulin and thyroid volume, TSH or thyroid hormones could be demonstrated. Serum thyroglobulin alterations thus were related to alterations in TSH and thyroid volume during the menstrual cycle. However, the increase in serum thyroglobulin and thyroid volume during pregnancy were unrelated to changes in serum TSH, indicating other mechanisms of regulation than TSH. When interpreting serum thyroglobulin levels in women, the co-existence of pregnancy and time of menstrual cycle should be taken into account in order to avoid misinterpretation of results.
A single dose of lithium carbonate acutely elevates intact parathyroid hormone levels in humans
Authors: Seely Ellen W. , Moore Thomas J. , LeBoff Meryl S. , Brown Edward M. 
Published: December 2008

Abstract.
Hyperparathyroidism has been reported in patients receiving lithium therapy, and lithium alters calcium-regulated PTH release in vitro. Previous studies in vivo have used assays which measure fragments of PTH as well as the intact hormone. To determine if lithium acutely elevates intact PTH levels, we studied 9 subjects who received a single oral dose of lithium carbonate (600 mg). Serum levels of intact PTH, ionized calcium, and lithium were measured before, 2 and 14 h after the dose of lithium. PTH levels rose significantly 2 h following the dose of lithium (before 22 ± 5.0, post 32 ± 7.3 ng/l, p < 0.02). PTH levels had returned to baseline at 14 h (22 ± 3.8 ng/l). There were no significant changes in ionized calcium levels. Therefore, a single oral dose of lithium carbonate acutely elevates intact PTH values in human subjects.
In vitro effects of ketoconazole on corticotrope cell morphology and ACTH secretion of two pituitary adenomas removed from patients with Nelson's syndrome
Authors: Reina L.Jimenez , Leal-Cerro A. , Garcia J. , Garcia-Luna P.P. , Astorga R. , Bernal G. 
Published: December 2008

Abstract.
The direct effects of ketoconazole on the secretion of ACTH by human pituitary adenoma cells from 2 patients with Nelson's syndrome were studied in vitro. Stereologically quantified, intracellular changes affect the surface density of the endoplasmic reticulum (it decreased by 73%), the volume density of the secretion granules (it decreased by 49%), and the volume density of lysosomes (it decreased by 67%). The hormone released in the culture medium decreased depending on the doses of ketoconazole used; 10 μmol/l decreased ACTH levels by 31%. These data show that ketoconazole induce marked changes on corticotrope morphology and ACTH secretion in pituitary cells obtained from patients with Nelson's syndrome.
A sensitive and practical bioassay for thyrotropin using cultured FRTL-5 cells: assessment of bioactivity for serum TSH in patients with chronic renal failure
Authors: Horimoto Masateru , Nishikawa Mitsushige , Yoshikawa Norio , Inada Mitsuo 
Published: December 2008

Abstract.
A sensitive bioassay for TSH employing a practical extraction method was developed, and the bioactivities in patients with chronic renal failure receiving hemodialysis were compared with those in normal subjects. Serum samples were obtained from 12 normal subjects and 12 patients with chronic renal failure receiving hemodialysis. TSH was extracted from the serum using anti-human TSH monoclonal antibody coated tubes, followed by elution with 2.0 mol/l guanidine-HCl solution (pH 3.2). After the eluate had been dialyzed against phosphate buffered saline (pH 7.4) and again against TRIS-HCl solution (pH 7.4) and then lyophilized, it was reconstituted with hypotonic Hanks' solution. Bioassay for TSH was performed by measuring the levels of cAMP released into the medium from cultured FRTL-5 cells incubated with the extract. The mean immunoreactive recovery rates of TSH from the serum in normal subjects and patients with chronic renal failure were about 42% (± 6) and 40% (± 2), respectively. The present bioassay was sufficiently sensitive to detect a serum TSH level of 1.0 mU/l when 3.0 ml of serum was used. Extracts from standard sera at concentrations ranging from 1.0 to 10 mU/l added to the culture medium caused significant linear increases in cAMP production. Based on analysis of covariance the regression line between the immunoreactivities and bioactivities of serum TSH in patients with chronic renal failure (y = 0.90x + 0.3, r = 0.92) was not significantly different from that in normal subjects (y = 1.04x + 0.1, r = 0.93). These results suggest that the present bioassay for TSH is sensitive and practical, and that the bioactivity of TSH in patients with chronic renal failure is similar to that in normal subjects.
Inhibition of insulin degradation by insulin-like growth factors I and II in human hepatoma (HepG2) cells
Authors: Keller Susanne , Schmid Christoph , Zapf Jürgen , Froesch E. Rudolf 
Published: December 2008

Abstract.
IGF-I infused at pharmacological doses in healthy men markedly decreases C-peptide levels, whereas insulin levels remain within the normal range. One possible explanation is decreased insulin removal. As the liver is the major site of insulin degradation, we studied insulin degradation by HepG2 cells in the presence of IGF. We found that IGF-I at a concentration of 130 nmol/l inhibits insulin degradation by HepG2 cells when the initial insulin concentration is 0.34 nmol/l. The effect of IGF-I on insulin degradation is dose-dependent and the rate of insulin degradation is dependent on the insulin concentration. IGF-II is 6 to 10 times more potent than IGF-I in inhibiting 125I-insulin binding to HepG2 cells and in protecting insulin from being degraded. Thus, IGF-I and IGF-II inhibit insulin degradation most likely by competing for binding at insulin binding sites of liver cells.
Determination of prolactin, growth hormone, β-endorphin, and cortisol in both maternal plasma and amniotic fluid during human gestation
Authors: Kubota Toshiro , Tsuzuki Hiroo , Saito Motoi 
Published: December 2008

Abstract.
This study focuses on PRL, GH, β-endorphin and cortisol in maternal blood and amniotic fluid during human pregnancy. Maternal blood and amniotic fluid samples were obtained from 18 normal pregnant women in the second trimester, 12 full-term gravidas having spontaneous delivery, and 10 full-term gravidas having elective cesarean section. Two gravidas bearing anencephalic fetuses in the third trimester were also studied. In the second trimester women, levels of PRL (3215.9 ± 458.9 μg/l), GH (19.1 ± 1.7 μg/l) and β-endorphin (11.1 ± 0.9 pmol/l) were significantly higher in the amniotic fluid than in maternal plasma. In addition, PRL was significantly correlated with β-endorphin (r = 0.670) and with GH (r = 0.547) in the amniotic fluid. However, amniotic fluid cortisol levels (0.27 ± 0.18 nmol/l) were significantly lower than plasma cortisol levels. The amniotic fluid of the women with anencephalic fetuses had normal levels of PRL, GH and β-endorphin. In full-term gravidas, plasma PRL levels were significantly lower in women with vaginal delivery than in those with elective cesarean section, and there was a significant negative correlation between plasma PRL and β-endorphin, and between plasma PRL and cortisol levels. Plasma GH levels in women with vaginal delivery showed no signficant difference from those in women with cesarean section. Examination of amniotic fluid yielded no significant differences in the levels of PRL, β-endorphin and GH between these two groups. The authors conclude that the hormone releasing system in amniotic fluid seems to be independent of that in maternal plasma during pregnancy, and that the stress of labour has a significant effect on plasma PRL, β-endorphin and cortisol levels in maternal plasma but not on those in amniotic fluid.
Increased activity of ovarian thecal cytochrome P45017α in the hamster induced by endogenous LH
Authors: Johnson Donald C. , Sen Mitra 
Published: December 2008

Abstract.
The in vivo regulatory action of LH on the ovarian androgen synthesizing enzyme cytochrome P45017α (17α-hydroxylase/C17, 20-lyase) was studied in cyclic golden hamsters. Immunohistochemical studies using anti-porcine testicular cytochrome P45017α antibody indicated that the enzyme was limited to thecal cells. Transient removal of the negative feedback action of endogenous steroids by use of aminoglutethimide phosphate produced an increase in endogenous gonadotropins. A single dose (30 mg) of aminoglutethimide on days 1, 2 or 3 of the estrous cycle (day 1 = estrus), increased serum levels of LH, but only for about 12 h. Increases in enzyme activities, which persisted for at least 24 h, followed. Two doses of aminoglutethimide, 12 h apart, maintained elevated levels of serum LH for about 36 h, and enzyme activites for at least 48 h. However, when the drug was given after the pre-ovulatory surge of LH on proestrus, and again on the morning of estrus, neither serum LH nor enzyme activity levels increased within 24 h. Induced increases in enzyme activity had no effect upon ovulation rate, as determined by the number of oviductal eggs present on the morning of estrus. The results demonstrate clearly a close correlation between serum concentrations of LH and ovarian androgen synthesizing enzyme activity.
Direct administration of testosterone increases rat tibial epiphyseal growth plate width
Authors: Ren Song Guang , Malozowski Saul , Sanchez Prosper , Sweet Donald E. , Loriaux D. Lynn , Cassorla Fernando 
Published: December 2008

Abstract.
Local injection of hormones into the tibial epiphyseal growth plate offers a possible model to answer whether sex steroids can affect bone growth directly. To answer this question, we injected different doses of testosterone enanthate (4, 40, 120 and 400 μg/100 g of rat weight) once into the tibial epiphyseal growth plate of castrated 35-day-old male rats. The contralateral tibia was injected with sesame oil and served as control. All animals were sacrificed at age 42 days. Tibias were removed for measurement of epiphyseal growth plate width and blood was collected for measurement of serum IGF-I and testosterone. The lower doses of testosterone enanthate (4, 40 and 120 μg/100 g) did not produce any significant change in epiphyseal growth plate width. Testosterone at the largest dose tested (400 μg/100 g) increased epiphyseal growth plate width by about 15% compared to control (p < 0.01). At this dose, serum testosterone was not increased, suggesting that the effect on epiphyseal growth plate width was not due to higher systemic testosterone concentrations. No differences in IGF-I levels were observed among the groups. We conclude that direct administration of testosterone enanthate at a dose of 400 μg/100 g into the rat tibial epiphyseal growth plate can increase epiphyseal growth plate width.