Biomedical subjects

L Girton

Publications and source records attributed to L Girton.

9 recordsLinked to original sources

PubMed1992

The suppressor of forked locus in Drosophila melanogaster: genetic and molecular analyses.

The suppressor of forked, su(f) locus is one of a class of loci in Drosophila whose mutant alleles are trans-acting allele-specific modifiers of transposable element-insertion mutations at other loci. Mutations of su(f) suppress gypsy insert alleles of forked and enhance the copia insert allele white apricot. Our investigations of su(f) include genetic and molecular analyses of 19 alleles to determine the numbers and types of genetic functions present at the locus. Our results suggest the su(f) locus contains multiple genetic functions. There are two distinct modifier functions and two vital functions. One modifier function is specific for enhancement and the other for suppression. One vital function is required for normal ecdysterone production in the third larval instar, the other is not. We present a restriction map of the su(f) genomic region and the results of an RFLP analysis of several su(f) alleles.

Alleles↗

PubMed1992

Hypothalamic-pituitary-thyroidal function in eumenorrheic and amenorrheic athletes.

The impact of chronic high volume athletic training on thyroid hormone economy has not been defined. We investigated the status of the hypothalamic-pituitary-thyroid axis (H-P-T) in women athletes with regular menstrual cycles (CA) and with amenorrhea (AA). Their data were compared with each other and with those derived from cyclic sedentary women (CS) matched for a variety of confounding factors including the intensity of exercise, caloric intake, and body weight. Alterations of the H-P-T axis were observed in women athletes compared to CS. While serum levels of T4, T3, free T4, free T3 and rT3 were substantially reduced (P less than 0.01) in AA, only serum T4 levels were significantly decreased in CA. Further, remarkable differences were found between CA and AA in that serum levels of free T4 (P less than 0.01), free T3 (P less than 0.01), and rT3 (P less than 0.05) were significantly lower in AA than in CA. Thyroid binding globulin and sex-hormone binding globulin concentrations were within their normal ranges for all groups of subjects. Both 24-h mean TSH levels and the circadian rhythm of TSH secretion were also comparable. However, the TSH response to TRH stimulation was blunted (P less than 0.01) in AA when compared to CA, but not to CS. Whereas the underlying mechanism(s) to account for the "global" reduction of circulating thyroid hormone in the face of normal TSH levels in AA is presently unknown, these observations provide information of clinical significance: 1) chronic high volume athletic training in women athletes with menstrual cyclicity is accompanied by an isolated T4 reduction; 2) an impaired H-P-T axis occurs selectively in athletic women in whom chronic high volume athletic training is associated with compromised hypothalamic-pituitary-ovarian function and amenorrhea.

Adult↗

PubMed1991

Successful treatment of severe premenstrual syndrome by combined use of gonadotropin-releasing hormone agonist and estrogen/progestin.

Although abolishment of ovarian cyclicity by the use of a long-acting GnRH agonist (GnRH-a) provides effective treatment for premenstrual syndrome (PMS), its use is limited by sequellae of the resultant hypoestrogenism. In this study the effects of estrogen/progestin replacement on the symptomatic improvement afforded by GnRH-a were evaluated in eight women with severe PMS. The 8-month study design included 2 months of control, 2 months of GnRH-a alone, and 4 further months in which the exogenous steroids were replaced in randomized, double blind, placebo-controlled cross-over fashion using 1 month each of 1) conjugated equine estrogen (CEE) on days 1-25, 2) 10 mg medroxyprogesterone acetate (MPA) on days 16-25, 3) CEE (days 1-25) plus MPA (days 16-25), and 4) placebo alone. Mood and physical symptoms were measured daily on a valid and reliable instrument, the Calendar of Premenstrual Experiences. As expected, administration of GnRH-a alone resulted in a 75% improvement in luteal phase symptom scores (17.8 +/- 4.8 vs. 4.2 +/- 1.6; P less than 0.01). Combined sequential administration of CEE and MPA in addition to GnRH-a was effective in maintaining the reduced symptom scores seen after GnRH-a alone and was superior to the addition of CEE alone, MPA alone, or placebo. This combination of CEE and MPA resulted in a 60% improvement (P less than 0.05) compared to the luteal phase of control months in both behavioral (14.1 +/- 3.9 vs. 4.2 +/- 0.8) and total (17.8 +/- 4.8 vs. 6.5 +/- 1.8) symptoms. We conclude that the undesirable consequence of ovarian steroid deficiency in the treatment of PMS by GnRH-a can be overcome by the addition of sequential estrogen and progestogen replacements without significantly reducing the effectiveness of GnRH-a in this disorder.

Adult↗

PubMed1990

Diagnosis of premenstrual syndrome by a simple, prospective, and reliable instrument: the calendar of premenstrual experiences.

To establish a quantitative method for the diagnosis of premenstrual syndrome (PMS), a simple prospective inventory, the calendar of premenstrual experiences, was constructed. The validity and reliability of this instrument were assessed by administering it throughout two consecutive ovulatory cycles to 36 rigidly screened women with PMS and to 18 controls. To establish concurrent validity, scores on behavioral items were correlated with simultaneously obtained scores on lengthier, well-validated psychiatric inventories designed to measure depression rather than PMS, the Beck Depression Inventory and the Profile of Mood States. The results showed that the calendar of premenstrual experiences luteal phase score distinguished PMS women from controls correctly in 104 of 108 cycles, with a 2.8% false-negative rate and no false positives when used for two consecutive cycles. An upper limit follicular phase score was observed beneath which all PMS and normal control subjects fell, suggesting that a higher score is not consistent with PMS. Correlation coefficients of calendar item scores with Profile of Mood States scale scores were 0.58 for tension, 0.51 for depression, 0.46 for anger, 0.61 for fatigue, and 0.57 for confusion (P less than .0001 for all correlations). The correlation of the calendar depression item with the Beck Depression Inventory score was 0.56 (P less than .0001). The test-retest reliability of the calendar given in the same phase of two consecutive menstrual cycles was high (r = 0.78, P less than .0001). We conclude that this instrument is a valid, reliable, and practical PMS inventory, applicable to clinical and some research settings.

Adult↗

PubMed1989

Depressive episodes in premenstrual syndrome.

Episodic depression, a prominent but poorly defined symptom of premenstrual syndrome, was quantitated in 24-hour cortisol secretory episodes (determined by sampling at 20-minute intervals) as biochemical markers, as well as the Beck Depression Inventory and Profile of Mood States as psychometric measures. Results of 16 patients with premenstrual syndrome were compared with six age-matched women with endogenous depression and 16 control women. On both the Profile of Mood States and Beck Depression Inventory, women with premenstrual syndrome showed a marked worsening of scores (p less than 0.01) during the luteal phase compared with either their own follicular phase scores or the scores of controls in either cycle phase. However, Beck Depression Inventory scores were threefold higher (p less than 0.005) in women with depression than in those with luteal phase premenstrual syndrome (3.37 +/- 3.6 vs. 11.9 +/- 2.5). The Profile of Mood States depression scale was also higher (p less than 0.05) in women with depression than in those with premenstrual syndrome, while scores on other Profile of Mood States scales were similar. The numbers of cortisol secretory pulses identified by the cluster algorithm were similar (5 to 6 per 24 hours) in all groups, and the time of circadian nadirs as determined by cosinor rhythmometry were comparable. While the mean amplitude and duration of the cortisol pulses were also similar in women with premenstrual syndrome and controls, both were significantly higher (p less than 0.05) in women with depression. This resulted in markedly enhanced (p less than 0.005) cortisol secretion during a given secretory episode in women with depression and in higher 24-hour transverse mean cortisol values in women with depression (87.8 +/- 5.8 ng/ml) than in either those with premenstrual syndrome (66.7 +/- 3.3 ng/ml) or controls (58.9 +/- 3.3 ng/ml). These data affirm the clinical impression that depressive episodes occurring selectively in the luteal phase of the cycle in women with premenstrual syndrome are not present in controls and demonstrate, for the first time, that these episodes are distinct from endogenous depression as measured by both cortisol secretory parameters and psychological indices.

Adult↗

PubMed1989

Neuroendocrine aberrations in women with functional hypothalamic amenorrhea.

To further elucidate the neuroendocrine regulation of anterior pituitary function in women with functional hypothalamic amenorrhea (FHA), we measured serum LH, FSH, cortisol, GH, PRL, TSH concentrations simultaneously at frequent intervals for 24 h in 10 women with FHA and in 10 normal women in the early follicular phase (NC). Using the same data, we separately analyzed the cortisol-PRL responses to meals in these women. In addition, the pituitary responses to the simultaneous administration of GnRH, CRH, GHRH, and TRH were assessed in 6 FHA and 6 normal women. The 24-h secretory pattern of each hormone except TSH was altered in the women with FHA. Compared to normal women, the women with FHA had a 53% reduction in LH pulse frequency (P less than 0.0001) and an increase in the mean LH interpulse interval (P less than 0.01); LH pulse amplitude was similar. The 24-h integrated LH and FSH concentrations were reduced 30% (P = 0.01) and 19% (P less than 0.05), respectively. The mean cortisol pulse frequency, amplitude, interpulse interval, and duration were similar in the two groups, but integrated 24-h cortisol secretion was 17% higher in the women with FHA (P less than 0.05). This increase was greatest from 0800-1600 h, but also was present from 2400-0800 h. Cortisol levels were similar in the two groups from 1600-2400 h, resulting in an amplified circadian excursion. In contrast, the 24-h serum PRL levels were markedly lower at all times (P less than 0.0001), the sleep-associated nocturnal elevation of PRL was proportionately greater (P less than 0.05), and serum GH levels were increased at night in the women with FHA (P less than 0.05). Although 24-h serum TSH levels were similar at all times, T3 (P less than 0.05) and T4 (P less than 0.01) levels were lower in the FHA women. The responses of serum cortisol to lunch (P less than 0.01) and dinner (P less than 0.05) and those of serum PRL to lunch (P less than 0.05) and dinner (P = 0.08) were blunted in the women with FHA. Pituitary hormone increments in response to the simultaneous iv administration of GnRH, CRH, GHRH, and TRH were similar in the two groups, except for a blunted PRL response to TRH in the women with FHA (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Alterations in the hypothalamic-pituitary-ovarian and the hypothalamic-pituitary-adrenal axes in athletic women.

The functional integrity of the hypothalamic-pituitary-ovarian and hypothalamic-pituitary-adrenal axes was assessed by determining pulsatile LH, ACTH, and cortisol secretion during the early follicular phase in athletic women with regular menstrual cycles (CA; n = 9), athletic women with amenorrhea (AA; n = 9), and regularly cyclic sedentary women (CS; n = 8). The CA and AA women were not significantly different in body composition, exercise training, psychometric tests, or dietary consumption. The CA women had shorter luteal phases (P less than 0.05) and lower urinary excretion of pregnanediol glucuronide than the CS women. In the AA women, urinary estrone glucuronide, pregnanediol glucuronide, and LH excretion were low throughout a 30-day period. The CA women had a 24-h pattern of pulsatile LH secretion characterized by reduced frequency (P less than 0.05) and increased amplitude (P less than 0.05), yielding an overall increased 24-h mean level (P less than 0.05), but interpulse intervals similar to those in the CS women. During sleep, LH pulse frequency slowed in the CS and CA women, while pulse amplitude increased and the mean serum LH level decreased in both groups. The AA women had even fewer pulses (P less than 0.05) of normal amplitude occurring at much more variable (P less than 0.01) interpulse intervals. Sleep-associated changes in LH pulsatility were absent. Responses to a 10-microgram bolus GnRH dose revealed blunted (P less than 0.05) FSH release in CA and augmented (P less than 0.05) LH release in AA women. The groups did not differ in any 24-h ACTH pulse pattern parameter or in cortisol pulse frequencies. Yet, early morning (0200-0800 h) serum cortisol levels were higher (P less than 0.05) in both groups of athletes, and this elevation was extended through the day (0800-2000 h; P less than 0.001) and evening (2000-0200 h; P less than 0.05) in the AA women. The plasma ACTH and serum cortisol responses to bolus human CRH administration were blunted in the CA and AA women [change from baseline (delta) in ACTH, P less than 0.05 and P less than 0.01; delta cortisol, P less than 0.01 and P less than 0.01, respectively], but adrenal sensitivity (delta cortisol/delta ACTH ratio) was increased (P less than 0.05). The plasma ACTH and serum cortisol responses to meals also were blunted in the athletic groups (P less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenocorticotropic Hormone↗

PubMed1986

Infection of a Chlorella-like alga with the virus PBCV-1: transcriptional studies.

Infection of the unicellular, eukaryotic Chlorella-like green alga NC64A by the large dsDNA containing virus PBCV-1 immediately reduced host RNA synthesis. Chloroplast rRNAs, but not cytosolic rRNAs, were degraded following viral infection. Northern blot analysis utilizing four cloned fragments of PBCV-1 DNA as probes, which represent about 12% of the viral genome, revealed several properties of PBCV-1 transcription: A few viral transcripts were detected within 5 min after infection. Each PBCV-1 DNA clone hybridized to both early and late transcripts which implies that early and late genes are dispersed throughout the viral genome. The transition from early to late transcription occurred between 40 and 60 min after infection coincident with the onset of viral DNA synthesis. Three of the four DNA clones hybridized to transcripts which additively were larger than the corresponding DNA probe. This could reflect RNA processing, presence of overlapping genes, or transcription from both DNA strands. A few, but not all, early transcripts were synthesized in the presence of cycloheximide. This suggests that the virus either carries in its own RNA polymerase or uses a host RNA polymerase for very early viral transcription and that synthesis of additional, later transcripts depends on translation of an early gene product(s).

Chlorella↗

PubMed1985

DNA methylation of viruses infecting a eukaryotic Chlorella-like green alga.

The genomic DNAs of the eukaryotic Chlorella-like green alga, strain NC64A, and eleven of its viruses all contain significant levels of 5-methyldeoxycytidine. In addition, the host DNA as well as six of the viral DNAs also contain N6-methyldeoxyadenosine. At least some of the methylated bases in the host reside in different base sequences than the methylated bases in the viruses as shown by differential susceptibility to restriction endonuclease enzymes. This suggests that the viruses encode for DNA methyltransferases with sequence specificities different from that of the host enzyme.

Base Composition↗