Showing papers by "Robert L. Reid published in 1997"

The Effect of 20 ??g Ethinyl Estradiol/1 mg Norethindrone Acetate (MinestrinTM), a Low-Dose Oral Contraceptive, on Vaginal Bleeding Patterns, Hot Flashes, and Quality of Life in Symptomatic Perimenopausal Women

Abstract: One hundred and thirty two perimenopausal women with climacteric symptoms participated in a placebo-controlled, double-blind, randomized, parallel group study of the oral contraceptive Minestrin™ containing 20 μg ethinyl estradiol/1 mg norethindrone acetate (EE 20 μg/NA 1 mg). Bleeding patterns, hot flashes, quality of life, and safety were assessed over a 24-week (6 cycle) interval. There was no difference in the average duration of bleeding episodes between the treatment groups, but EE 20 μg/NA 1 mg therapy shortened menstrual cycle duration (p < 0.05), decreased its variability, and markedly lowered bleeding severity (p < 0.01). The incidence and duration of clots/flooding were reduced in the EE 20 μg/NA 1 mg group for the last 3 cycles (p < 0.05). The frequency of inter-menstrual bleeding was higher in the oral contraceptive users during the first 12 weeks (p < 0.05), but no difference was observed between the two groups after 3 months of treatment. The frequency and severity of hot flashes were decreased in the treated group, but statistical significance was not reached due to large variability. Quality of life assessments indicated significant improvements in the oral contraceptive treatment group. Adverse events were similar in occurrence and type in treated and control groups; however, normalization of hematologic parameters and beneficial effects on endometrium were noted more often in the active treatment group. Compared with placebo, EE 20 μg/NA 1 mg improved cycle control, decreased bleeding severity, and improved quality of life while offering a similar safety profile.

Hypoglycemia-induced inhibition of LH and stimulation of ACTH secretion in the rhesus monkey is blocked by alprazolam.

Abstract: Insulin-induced hypoglycemia inhibits luteinizing hormone (LH) secretion and has been used as a model to study stress-induced inhibition of reproductive function. Endogenous opioid peptides have been implicated in mediating the inhibitory effect of hypoglycemia on LH secretion in sheep and rat. The objective of the present study was to determine if corticotropin-releasing hormone (CRH) and endogenous opiates are involved in the LH response to hypoglycemia in the nonhuman primate. Blood samples were collected at 15-min intervals for 6 h from ovariectomized rhesus monkeys (n = 6). Hypoglycemia was induced by injecting insulin 1 h after initiating blood collection. Animals were pretreated 15 min prior to insulin with either saline (n = 6), naloxone, a nonselective opiate receptor antagonist (n = 4), or alprazolam (n = 6), a potent benzodiazepine which has been shown to inhibit CRH. The LH, glucose, adrenocorticotropin (ACTH), and cortisol responses to insulin were determined. Insulin-induced hypoglycemia significantly inhibited LH secretion and increased ACTH and cortisol concentrations. Alprazolam prevented hypoglycemia-induced inhibition of LH independent of an effect on glucose concentrations. The mean (+/- SEM) LH pulse interval in response to hypoglycemia was decreased in the alprazolam pretreated group compared to the saline pretreated group (77.4 +/- 6.0 vs. 130.0 +/- 18.4 min), while LH pulse amplitude and mean LH levels were significantly increased (56.2 +/- 7.1 vs. 28.3 +/- 5.5 ng/ml, and 105.6 +/- 14.4 vs. 60.9 +/- 12.1 ng/ml respectively). In contrast, naloxone did not prevent hypoglycemia-induced LH inhibition. The mean LH pulse interval, LH pulse amplitude, and LH concentration in the naloxone pretreated monkeys were 152.1 +/- 33.4 min, 37.1 +/- 8.9 ng/ml, and 63.7 +/- 9.1 ng/ml respectively. Alprazolam pretreatment also markedly attenuated the ACTH response to hypoglycemia whereas the cortisol response was only moderately affected. We conclude that insulin-induced hypoglycemia in the monkey inhibits LH secretion through a mechanism involving CRH but not endogenous opiates.

Luteinizing hormone secretion and corticotropin-releasing factor gene expression in the paraventricular nucleus of rhesus monkeys following cortisol synthesis inhibition.

Abstract: Corticotropin-releasing Factor (CRF) is an important inhibitory neuromodulator of GnRH/LH secretion, and mediates in part the inhibitory effects of stress on the hypothalamic-pituitary-gonadal axis. The purpose of the present study was to further investigate CRF's role in regulating LH secretion in primates. This was accomplished by examining LH secretion in ovariectomized rhesus monkeys (n = 7) following cortisol synthesis inhibition with metyrapone. Infusion of metyrapone (5 mg/kg per h) for 4 h decreased cortisol levels to less than 20% of controls while increasing ACTH approximately 10-fold. LH concentrations were not affected by this acute activation of the hypothalamic-corticotroph axis. In a second experiment, metyrapone was infused for 10 h before collecting serial blood samples every 15 min for 6 h. Although this protocol produced a sustained increase in ACTH, no apparent effect on pulsatile LH secretion compared with saline controls was observed. Mean LH (+/- SEM) levels calculated for consecutive 2-h increments were 87.6 +/- 9.2 (0-2 h) 82.1 +/- 5.5 (2-4 h), and 80.7 +/- 4.8 (4-6 h) ng/ml in saline pretreated animals compared with 83.6 +/- 4.9, 79.8 +/- 5.8, and 72.5 +/- 6.2 ng/ml, respectively, in metyrapone pretreated monkeys. The same regimen of metyrapone infusion increased CRF messenger RNA levels in the paraventricular nucleus by approximately 33% (P < 0.0002). In a final experiment designed to examine the potential synergy between CRF and cortisol, the LH response to insulin-induced hypoglycemia was contrasted in saline and metyrapone pretreated monkeys. LH concentrations were reduced to approximately 40% of basal levels following insulin in both metyrapone and saline pretreated monkeys. Therefore, even though inhibition of cortisol synthesis leads to an increase in CRF messenger RNA in the paraventricular nucleus and a robust increase in ACTH secretion in rhesus monkeys, presumably due in part to increased neuroendocrine CRF secretion, LH secretion was not inhibited during either the acute or more chronic phase of corticotroph activation. Absence of LH inhibition was not due to low cortisol concentrations resulting from metyrapone because metyrapone did not prevent hypoglycemia-induced suppression of LH secretion. We conclude that increased neuroendocrine CRF secretion following metyrapone does not inhibit LH secretion under these conditions. Several explanations for this result are discussed.

Effect of 5-aminolevulinic acid dose and estrogen on protoporphyrin IX concentrations in the rat uterus.

Abstract: OBJECTIVES To determine the in vivo dose-response relation between administered 5-aminolevulinic acid (ALA) and the concentration of protoporphyrin IX (PpIX) produced in rat uterine tissue, to determine the effect of estrogen on ALA-induced PpIX production in the rat endometrium and myometrium, and to determine the selectivity of ALA-induced PpIX production in uterine tissue. METHODS Ovary-intact female rats (n = 53) received a subcutaneous estradiol-17 beta (E2) implant. Three days later, ALA dissolved in saline (0, 1, 2.5, 10, 25, or 50 mg/100 microL) was injected into one uterine horn. Three hours after ALA administration, the uterus was removed and the endometrium was scraped from the myometrium. In a second study, rats (n = 35) were ovariectomized and 8 days later given either an E2 or sham implant. After 3 days of hormonal or sham priming, ALA (10 or 25 mg) was injected into the uterine horn 3 hours before hysterectomy. In both studies, PpIX was extracted in a methanol/ perchloric acid (1:1) solution and quantified spectrofluorometrically. RESULTS Five-aminolevulinic acid increased PpIX concentrations in the endometrium and myometrium in a dose-dependent fashion. Twenty-five milligrams of ALA produced maximum PpIX concentrations in both the endometrium and myometrium. In the second study, sham-implanted ovariectomized rats had endometrial PpIX concentrations approximately two times higher than those in the estrogen-primed rats after doses of either 10 or 25 mg ALA. In the third study, the endometrium had two to three times higher PpIX concentrations than the myometrium at 1, 10, 25, and 50 mg of ALA. CONCLUSIONS An in vivo dose-response relation was demonstrated between ALA and uterine production of PpIX, with maximum PpIX concentrations occurring after 25 mg of intrauterine ALA. Because estrogen was not required to convert ALA to PpIX, complete endometrial ablation may best be achieved with an unstimulated endometrium.

Effect of continuous and multiple doses of 5-aminolevulinic acid on protoporphyrin IX concentrations in the rat uterus

Abstract: The objective of the present study was to determine if the concentration of protoporphyrin IX (PpIX) in the rat endometrium could be increased by administering 5-aminolevulinic acid (ALA) in multiple doses or by continuous infusion. The effect of pH, temperature and time in solution on the stability of ALA were also investigated. Estrogen-filled silastic capsules were implanted subcutaneously into ovary intact female rats (200–225 g) (n = 66). On the third day of hormonal priming, ALA (10 mg or 25 mg) dissolved in saline and adjusted to a pH of 5–5.5 was administered intrauterine either as a single bolus or as two injections 3 hours apart (n = 10). A fifth group of rats was infused with 25 mg ALA over a 12 hour period using an osmotic minipump (n = 6). In a second experiment, ALA (25 mg) was injected immediately after being dissolved in saline (pH 2) (n = 16) or after incubation at 37°C for 12 hour (pH 2) (n = 7). PpIX was then extracted from the endometrium and myometrium using a 1:1 methanol/perchloric acid solution and quantified spectrofluorometrically. A dose-response relationship was observed between 10 and 25 mg of ALA and endometrial PpIX concentrations. However, no differences in endometrial PpIX concentrations were detected between rats administered ALA either as a single bolus or as two doses. Continuous infusion of 25 mg of ALA resulted in statistically lower endometrial PpIX concentrations compared to 25 mg ALA injected either as a single bolus or as two injections. Neither pH, temperature, nor time in solution affected ALA-induced PpIX accumulation. We conclude that the simplest way of achieving the highest PpIX concentration in the rat endometrium in vivo is to administer a bolus injection of 25 mg of ALA.

New directions in ALA-PDT

Abstract: Certain types of cells may accumulate relatively high concentrations of protoporphyrin IX (PpIX) when exposed to 5- aminolevulinic acid or certain of its derivatives. PpIX is a photosensitizing agent which can be photoactivated in vivo by ultraviolet and/or visible light, thereby initiating a photodynamic reaction that may lead to the destruction of cells and tissues containing high concentrations of PpIX. This process is referred to as ALA-induced PpIX photodynamic therapy (ALA-PDT), a rapidly growing field of research. ALA is effective when administered topically, orally, by intravenous, subcutaneous, or intradermal injection, or by infusion into accessible body cavities. PpIX is the main photosensitizer produced under most conditions, although others may be present also especially during split dose therapy. Multiple wavelength excitation sources are required to produce and subsequently activate the far red absorbing chlorin type photoproducts that are produced under certain conditions.