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P K Manasco

Publications and source records attributed to P K Manasco.

15 recordsLinked to original sources
PubMed2001

Single-nucleotide polymorphism alleles in the insulin receptor gene are associated with typical migraine.

We have identified a migraine locus on chromosome 19p13.3/2 using linkage and association analysis. We isolated 48 single-nucleotide polymorphisms within the locus, of which we genotyped 24 in a Caucasian population comprising 827 unrelated cases and 765 controls. Five single-nucleotide polymorphisms within the insulin receptor gene showed significant association with migraine. This association was independently replicated in a case-control population collected separately. We used experiments with insulin receptor RNA and protein to investigate functionality for the migraine-associated single-nucleotide polymorphisms. We suggest possible functions for the insulin receptor in migraine pathogenesis.

Alleles↗
PubMed1997

Ontogeny of gonadotrophin and inhibin secretion in normal girls through puberty based on overnight serial sampling and a comparison with normal boys.

We measured luteinizing hormone (LH) and follicle stimulating hormone (FSH) by immunofluorometric assays and alpha-inhibin by radioimmunoassay in serum sampled every 10 min throughout the night (2100-0500 h) from 44 normal girls. Mean overnight LH values rose log-linearly from a mean of 0.2 IU/l in prepubertal girls to 3.0 IU/l in late pubertal girls. Log2 mean overnight FSH rose rapidly through early puberty and then remained constant; mean FSH rose from 1.0 IU/l in prepubertal girls to approximately 2.8 IU/l in Tanner III-V girls. Mean overnight inhibin increased through puberty, rising from 151 ng/l in prepubertal girls to 432 ng/l in fully pubescent girls. Within each of the first three Tanner stages, LH differed approximately 100-fold between the smallest and largest mean concentrations but differed <10-fold within stages IV or V. Such within-pubertal stage variability was less pronounced for FSH, which differed approximately 16-fold among Tanner I subjects and 4-10-fold at later stages, and for inhibin, which varied approximately 4-fold within each Tanner stage. The frequency of LH pulses during overnight sampling increased significantly during puberty, but the frequency of FSH and inhibin pulses remained constant. We compared the results from girls to those from 50 normal boys [Manasco et al. (1995) J. Clin. Endocrinol. Metab., 80, 20462052]. At each pubertal stage, girls had approximately the same mean overnight LH values as boys; girls had higher mean overnight FSH, particularly during Tanner stages II-IV; and boys had mean overnight alpha-inhibin immunoreactivity approximately 1.5 times that of girls at each pubertal stage. Still, hormone concentrations for individuals of both sexes intergraded at each pubertal stage.

Adolescent↗
PubMed1995

Ontogeny of gonadotropin, testosterone, and inhibin secretion in normal boys through puberty based on overnight serial sampling.

To investigate hormonal changes occurring in male puberty, we measured LH, FSH, testosterone, and alpha-inhibin immunoactivity in serum samples drawn every 10 min for 8 h (2100-0500 h) from each of 50 normal prepubertal and pubertal boys, aged 8.4-18.8 yr. We measured gonadotropins with ultrasensitive immunofluorometric assays, and testosterone and alpha-inhibin with RIAs. Unlike previous studies, which indexed pubertal development with Tanner stages, we used testicular volume, a more finely graduated indicator of development, to reveal patterns that were obscured when subjects were grouped by Tanner stage. The overnight mean concentration of each hormone increased with testis volume, but the rate of increase on a logarithmic scale slowed as testes grew. Log LH rose precipitously in the late prepubertal and early pubertal periods and plateaued during mid- and late puberty. Based on fitted regression curves, LH increased about 20-fold (from 0.11 IU/L) between testis volumes of 1 and 10 mL, but only an additional 1.5-fold by 30 mL. The developmental trajectory of log testosterone was like that of log LH, but rose less steeply early in puberty. From 0.14 micrograms/L at a testis volume of 1 mL, testosterone increased about 8.5-fold by 10 mL and an additional 3-fold by 30 mL. In contrast, logarithms of overnight mean FSH and alpha-inhibin concentrations rose at a more nearly constant rate throughout puberty. From 0.62 IU/L at a testis volume of 1 mL, the FSH concentration doubled by 10 mL and increased an additional 1.7-fold by 30 mL. From 270 ng/L at a testis volume of 1 mL, inhibin increased 1.5-fold by 10 mL and an additional 1.3-fold by 30 mL. Overnight pulse amplitudes exhibited developmental trajectories similar to those of the corresponding overnight mean concentrations. The number of LH and testosterone pulses during the sampling period averaged 2.2 and 2.1, respectively, at Tanner stage 1 and increased to 4.5 and 3.2, respectively, at Tanner stage 5. The number of FSH and inhibin pulses remained constant throughout puberty, averaging 3.3 and 3.5, respectively. Pairwise correlations among hormone concentrations were strong, reflecting common increasing trends through puberty; however, after accounting for developmental trends, FSH, LH, and testosterone concentrations remained correlated, whereas inhibin was uncorrelated with each of the other three hormones. Measuring gonadotropins with ultrasensitive assays and analyzing the results on a logarithmic scale as a function of testis volume made clear the dramatic hormonal changes that begin before the clinical changes of puberty.

Activity Cycles↗
PubMed1993

Multiple hormone deficiencies in children with hemochromatosis.

Patients with thalassemia major require multiple blood transfusions leading to hemochromatosis. These patients often have pubertal delay and growth failure, the etiology of which has not been fully elucidated. We performed an extensive endocrine evaluation which included measurements of spontaneous and stimulated levels of gonadotropins, GH, thyroid hormone, and adrenal hormones in 17 patients between the ages of 12 and 18 yr with hemochromatosis receiving desferoxamine therapy. All of the 17 patients had at least one endocrine abnormality, and 12 had more than one abnormality. Abnormalities of the hypothalamic-pituitary-gonadal axis were the most common. Six patients had clinical evidence of delayed puberty with spontaneous and stimulated gonadotropin and sex steroid levels appropriate for their delayed pubertal stage. All 14 children in puberty LH pulsatility index below the mean for pubertal stage compared to normal children. Six of the 14 had LH pulsatility index more than 2 SD below the mean for pubertal stage. This may be an indicator of abnormal pituitary function. Six patients failed either the provocative GH tests (peak GH < 7 micrograms/L) or had a mean spontaneous GH less than 1 microgram/L. The 4 patients who failed provocative tests had growth velocities more than 2 SD below the mean for bone age. Three patients had evidence of primary hypothyroidism. We conclude that all patients with hemochromatosis need periodic careful endocrine evaluations because the incidence of endocrine dysfunction is substantial and they may benefit from hormonal therapy.

Adolescent↗
PubMed1991

A novel testis-stimulating factor in familial male precocious puberty.

BACKGROUND: Familial male precocious puberty is a gonadotropin-independent form of precocious puberty that occurs only in males. The cause of the disorder is unknown. To examine the hypothesis that the plasma of boys with familial male precocious puberty contains a novel stimulator of testicular testosterone production, we developed a bioassay using adult male cynomolgus monkeys. METHODS: We collected plasma from 12 boys with familial male precocious puberty, 7 normal prepubertal boys of similar ages and with similar plasma gonadotropin levels, and 1 boy with hypogonadotropic hypogonadism and infused it into the testicular artery of adult male cynomolgus monkeys that had been pretreated with gonadotropin-releasing-hormone antagonist to inhibit the endogenous secretion of gonadotropins. Testicular venous effluent was collected at 15-minute intervals for 3 or 5 hours for the measurement of testosterone. RESULTS: The mean (+/- SE) peak testosterone response, as compared with base line, was significantly greater in the monkeys infused with plasma from the 12 boys with familial male precocious puberty than in the monkeys infused with plasma from the 7 normal prepubertal boys and the boy with hypogonadotropic hypogonadism (385 +/- 51 vs. 184 +/- 25 percent, P less than 0.005) in the three-hour studies. Plasma from 92 percent of the boys with familial male precocious puberty and 12.5 percent of the normal prepubertal boys stimulated a response greater than 195 percent of base-line values. In the animals studied for five hours after receiving a second dose of antagonist, the mean peak testosterone response, as compared with base line, was significantly greater in the monkeys infused with plasma from three boys with familial male precocious puberty than in the monkeys infused with plasma from three normal prepubertal boys (363 +/- 81 vs. 115 +/- 6 percent, P less than 0.01). The mean area under the testosterone-response curve was significantly larger in the monkeys infused with plasma from the boys with familial male precocious puberty in the five-hour studies (154 +/- 34 vs. -58 +/- 10 percent, P less than 0.005), but not in the three-hour studies. CONCLUSIONS: These findings support the presence of a circulating testis-stimulating factor in the plasma of boys with familial male precocious puberty. The production of such a factor would explain the biologic nature of the disorder.

Animals↗
PubMed1991

Low growth hormone levels are related to increased body mass index and do not reflect impaired growth in luteinizing hormone-releasing hormone agonist-treated children with precocious puberty.

To test the hypothesis that GH deficiency might explain the low growth velocity of some LHRH agonist (LHRHa)-treated children with central precocious puberty, we measured stimulated (n = 81) and spontaneous (n = 32) GH levels during or after LHRHa treatment. GH stimulation tests in the children who were receiving LHRHa treatment were performed after 2 days of ethinyl estradiol administration. Thirty-one of 81 children (38%) who underwent GH stimulation tests had subnormal responses (less than or equal to 7 micrograms/L) to all tests administered (at least 2 stimuli), including 22 of 67 (33%) who had precocious puberty that was idiopathic or associated with hypothalamic hamartoma. Eleven of 32 children (34%) who underwent measurement of the mean nighttime spontaneous GH level had levels below the normal range for prepubertal children (less than 1.2 microgram/L). Despite the high incidence of subnormal GH levels, there appeared to be no relationship between the GH levels of these children and their growth characteristics. The height, growth velocity, bone maturation rate, predicted height, and insulin-like growth factor-I levels were not different between the children with low GH levels and the children with normal GH levels. Conversely, the GH levels were not different between the children with subnormal growth rates and the children with normal growth rates. Thus, variation in the growth rates of these LHRHa-treated children with central precocious puberty could not be explained by variation in the stimulated or spontaneous secretion of GH. In attempting to understand the high incidence of low GH levels in children with precocious puberty, we examined the relationship between GH level and body mass index (BMI). Both the stimulated (r = -0.33; P less than 0.002) and the spontaneous (r = -0.61; P less than 0.0002) GH levels were inversely related to BMI. Moreover, the children with precocious puberty as a group had significantly elevated BMI [1.2 +/- 0.1 (+/- SE) SD units] compared to normal children of the same age (P less than 0.0001). Thus, increased body mass may explain the high incidence of subnormal GH levels in these patients, and normative GH levels adjusted for body mass are needed before it can be concluded that the apparently subnormal GH levels in LHRHa-treated children with precocious puberty are in fact low.

Adolescent↗
PubMed1991

Luteinizing hormone-releasing hormone (LHRH)-independent precocious puberty unresponsive to LHRH agonist therapy in two girls lacking features of the McCune-Albright syndrome.

Two girls with precocious puberty (chronological age, 1 and 4 yr; bone age, 3 and 6 yr, respectively) were initially given the diagnosis of idiopathic, central precocious puberty and treated with the LHRH agonist deslorelin (D-Trp6-Pro9-NEt-LHRH) for 5 yr. Unlike other girls with central precocious puberty, both had persistently elevated rates of growth and bone maturation, and both menstruated during therapy. One girl had episodic ovarian enlargement and markedly elevated serum estradiol levels due to recurrent unilateral ovarian cysts. Although the bone and skin manifestations of McCune-Albright syndrome were absent, we hypothesize that the underlying defect of McCune-Albright syndrome was expressed in the ovaries, but not in the skin or bones, of these two girls. One of these girls appeared to benefit from the aromatase inhibitor testolactone, which is effective in suppressing precocious puberty in girls with the McCune-Albright syndrome.

Child Development↗
PubMed1990

Hypothyroidism and deficiency of the nocturnal thyrotropin surge in children with hypothalamic-pituitary disorders.

The circadian pattern of serum TSH in normal children, aged 5-18 yr, is characterized by a nocturnal surge and is presumably related in some way to a biological clock within the central nervous system. To look for patients deficient in the nocturnal TSH surge, we studied 52 children with hypothalamic-pituitary disorders. Thirteen of the children were hypothyroid, as judged by subnormal serum free T4 (FT4). The hypothyroid patients had a mean nocturnal TSH surge of 22% (range, -30% to +114%), significantly less than that of normal controls (mean, 124%; 95% confidence limits, 47-300%; n = 96; P less than 0.01). Only 1 of the hypothyroid children had a value for the nocturnal TSH surge (114%) that was within the normal range. Nineteen of the 52 patients with hypothalamic-pituitary disorders had subnormal nocturnal TSH surges; their mean iodothyronine values were significantly less than those of the 33 patients with normal surges [total T4, 73 +/- 4 (mean +/- SE) vs. 109 +/- 3 nmol/L (P less than 0.01); FT4, 13 +/- 1.0 vs. 19 +/- 0.5 pmol/L (P less than 0.01)]. These data demonstrate a clear association of a deficient nocturnal TSH surge and low iodothyronine concentration in children with hypothalamic-pituitary disorders. We performed both TRH tests and nocturnal TSH surge tests in 11 of the children with central hypothyroidism; TRH was abnormal in only 2, while the nocturnal surge test was abnormal in 10 of the 11. We suggest that the nocturnal surge of TSH is important for maintenance of thyroid function and conclude that the nocturnal TSH surge is a much more sensitive test than the TSH response to TRH for the diagnosis of central hypothyroidism.

Adolescent↗
PubMed1988

Resumption of puberty after long term luteinizing hormone-releasing hormone agonist treatment of central precocious puberty.

To determine whether puberty resumes normally after long term LHRH agonist (LHRHa) treatment, we studied 16 children with central precocious puberty treated with LHRHa (D-Trp6,Pro9,NEt-LHRH) for 1-4 yr (mean, 3.3 yr). Treatment was discontinued at a mean age of 11.6 +/- 1.3 (+/- SD) yr. Plasma hormone levels, growth velocity, rate of bone maturation, and pubertal stage were assessed at the end of treatment and 3 and 12 months later. Basal plasma sex steroid and basal and LHRH-stimulated gonadotropin levels returned to near-pretreatment levels 3 months after discontinuation of therapy and were fully restored to pretreatment levels at 12 months. Growth velocity, which had been 7.8 cm/yr before treatment, was stable after discontinuation of treatment at approximately 2.6 cm/yr. The predicted height, which had increased during treatment (P less than 0.01), remained stable at approximately 5 cm above the pretreatment predicted height. The rate of bone age advancement (delta bone age/delta chronological age) increased gradually from 0.4 at the end of treatment to the normal value of 0.9 12 months posttreatment. Breast and pubic hair pubertal stages, which were stable throughout treatment and were 4.0 +/- 0.8 (+/- SD) and 3.6 +/- 1.0 at the end of treatment, increased to 4.9 +/- 0.2 and 4.5 +/- 1.0. This approximated the normal rate of 1 stage/yr. Menses occurred in 8 of 12 girls within 1 yr after treatment and in an additional 3 by 20 months after treatment. Six of the girls had menstruated before treatment, and all of these menstruated within 14 months after discontinuing therapy. We conclude that gonadotropin and sex steroid secretion and the clinical progression through puberty appear to resume normally after discontinuation of long term LHRHa treatment of central precocious puberty. Long term follow-up will be required, however, to determine whether the improvement in predicted height of these patients will be achieved, and whether adult reproductive function will be normal.

Body Height↗
PubMed1987

Long-term hyperalgesia induced by neonatal beta-endorphin and morphiceptin is blocked by neonatal Tyr-MIF-1.

Male rats were injected s.c. once daily during the first week of life with beta-endorphin (BE), morphiceptin, the antiopiate Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2), or one of the two opiate peptides in combination Tyr-MIF-1. Pups treated with neonatal BE removed their tails from a series of increasingly hot water baths significantly faster than controls on day 9, confirming our earlier studies. In addition, we found that Tyr-MIF-1 blocked this effect of BE. At 4.5 months, latency to lick a hindpaw in the hot-plate test was significantly faster in groups given BE alone, morphiceptin alone, or the control vehicle than in any of the 3 groups given Tyr-MIF-1. At 6 months the two groups given opiate peptides alone showed faster tail-flick latencies than the controls and the groups given Tyr-MIF-1. These results indicated that the long-term nociceptive changes induced by the opiate peptides were opposite to those induced by Tyr-MIF-1. Mean tail-flick latencies of the groups on day 9 correlated well with hot-plate and tail-flick scores in adulthood, indicating that the effects of the peptides were persistent. The neonatal peptide treatments did not differentially affect the analgesia induced by the stress of footshock or warm-water swim. Rats given either of the opiate peptides alone tended to fall off a rotorod faster than those in the other groups. These results support the role of Tyr-MIF-1 as an antiopiate and further illustrate the long-term effects of neonatally administered peptides.

Animals↗
PubMed1981

Curriculum evaluation: a crucial component of dietetic programs.

The Nominal Group Technique was used to evaluate the existing CUP curriculum at Louisiana Tech University. Forty-five persons involved in the program participated in one of three workshops. The nominal group process successfully generated ranked and weighed "problem" statements to be addressed in program revision. The NGT allowed input from all individuals, leading to the clinical practitioners "owning" the crucial clinical experience component of the coordinated undergraduate program.

Curriculum↗