Seventh Hour Research Articles

Coupling thin layer chromatography with mass spectrometry for detection and identification of sertraline and its metabolite in the urine

The aim of the study was to detect sertraline and its metabolites in urine under standardized thin layer chromatography (TLC) screening conditions and identify the metabolites using the mass spectrometry method. Materials and methods. Urine samples, collected within 30 hours in portions of 20–50 mL, commenced from the seventh hour after the administration of a single therapeutic dose of the drug. The sample preparation process involved dilute acid hydrolysis, followed by the extraction of the native compound and metabolites with chloroform at a pH of 8–9. Thin layer chromatography studies of the extracts were conducted using four unified TLC systems recommended by The International Association of Forensic Toxicologists for general drug screening. Chromatograms were subjected to color reactions with a variety of chromogenic reagents. For the analysis of eluates from chromatograms, a Varian 1200 L mass spectrometer (Netherlands) equipped with a dual quadrupole mass analyzer was employed. Identification was performed through direct sample introduction into the ion chamber, electron-impact ionization (70 eV), and full ion scanning mode. Results. The spot of the native drug on the chromatogram was identified by the Rf, value. Metabolite of sertraline was identified as N-desmethyltrihydroxysertraline by the molecular ion peak in the mass spectrum. Conclusions. The study demonstrated the ability of TLC to detect sertraline and its metabolite, N-desmethyltrihydroxysertraline, in urine after the administration of a single therapeutic dose of the drug. The chromatographic mobility of the native compound and N-desmethyltrihydroxysertraline in the unified TLC screening systems, along with the results of their visualization using chromogenic reagents for toxicological drug screening, was determined. Furthermore, the potential of coupling TLC with mass spectrometry for the separation, detection, and confirmatory identification of sertraline and its metabolic products in urine was established.

Emergence and Reproductive Rhythm of Clostera anastomosis (Lepidoptera: Notodontidae)

Abstract Clostera anastomosis L. (Lepidoptera: Notodontidae) is a serious defoliator of poplar, Populus spp., trees in China. To establish a baseline of information for possible ecological management of this pest, we studied its emergence, courtship, mating, and oviposition behaviors in the laboratory at 27 ± 1°C and 60 ± 10% relative humidity under a 14:10-h (light:dark) photoperiod. Under these conditions, peak emergence of female adults occurred in the sixth day after pupation, and peak emergence of males was in the seventh day after pupation. Emergence for both sexes occurred throughout the day. Courtship behavior began at the sixth hour of scotophase, reaching peak activity between the 10th hour of scotophase and the first hour of photophase. The courtship and mating success rate were highest for 1-d-old females, and then gradually decreased with age until no mating was observed after females were 4 d old. With 1-d-old females, mating was only observed from the seventh hour of scotophase to the first hour of photophase, with peak activity at 0.5 h after the onset of photophase. Oviposition primarily occurred within 3 d after mating, with 49.8% of the eggs being deposited during the first day after mating. These results demonstrate that there are distinct circadian rhythms in adult emergence and subsequent reproductive behavior of C. anastomosis, thus providing a basis for development of monitoring and management strategies of this pest.

Desorption of nutrients and flavor compounds formation during the cooking of bone soup

In order to identify the effects of varying cooking time on the quality of bone soup, the diversification of nutrient profiles and flavor compounds in bone soup prepared within 10 h' cooking was studied. The Kjeldahl method, inductively coupled plasma mass spectrometry (ICP-MS), automatic amino acid analyzer (AAA analyzer), high performance liquid chromatography (HPLC), solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) were applied to determine the changes o f crude protein, minerals, free amino acids (FAAs), 5′-nucleotides, and volatile compounds in the soup, respectively. During the 10 h cooking, the concentration of nutrients and flavor compounds reached their maximum and then decreased, except for minerals, which continued to increase in concentration. 18 FAAs were identified in all samples, which were related with I-collagen hydrolysis. Taste FAAs contributed little to the flavor of soup. Bitter amino acids increased significantly (P < 0.05) and IMP + GMP reached maximum concentration at the seventh hour of cooking. The main flavor compounds of bone soup were aldehydes, which increased significantly (P < 0.05) during boiling. Samples taken at the fourth and fifth hours contained the richest profile of volatile flavor compounds. In general, for high-quality bone soup, cooking time should be limited to achieve an appropriate balance between nutrient dissolution and flavor formation. • Crude protein and FAAs had dissolution equilibrium within atmospheric cooking. • Minerals increased with the extension of cooking time. • IMP + GMP may enhance the aroma of soup to the utmost extent at 7th hour. • Long-time heating destroyed the diversity of flavor and taste compounds and led to the loss of volatile flavor compounds. • Content of nutrients and flavor compounds was low in pure bone soup.

Electrospun Aspirin/Eudragit/Lipid Hybrid Nanofibers for Colon-targeted Delivery Using an Energy-saving Process.

Both electrospinning apparatus and their commercial products are extending their applications in a wide variety of fields. However, very limited reports can be found about how to implement an energy-saving process and in turn to reduce the production cost. In this paper, a brand-new type of coaxial spinneret with a solid core and its electrospinning methods are developed. A novel sort of medicated Eudragit/lipid hybrid nanofibers are generated for providing a colon-targeted sustained release of aspirin. A series of characterizations demonstrates that the as-prepared hybrid nanofibers have a fine linear morphology with the aspirin/lipid separated from the matrix Eudragit to form many tiny islands. In vitro dissolution tests exhibit that the hybrid nanofibers are able to effectively prevent the release of aspirin under an acid condition (8.7%±3.4% for the first two hours), whereas prolong the drug release time period under a neutral condition(99.7±4.2% at the seventh hour). The energy-saving mechanism is discussed in detail. The prepared aspirin-loaded hybrid nanofibers can be further transferred into an oral dosage form for potential application in countering COVID-19 in the future.

A Study on Radiation Cooling Effect on Asphalt Concrete Pavement Using Basic Oxygen Furnace Slag to Replace Partial Aggregates

In this study, aggregates in asphalt concrete were partially replaced by basic oxygen furnace slag (BOFS) in proportions of 45 wt.%, 55 wt.%, and 75 wt.%. The thermal performances of the specimens are discussed based on the thermal conductivity, emissivity, and the indoor and outdoor temperature measurements. Consequently, 75 wt.% of the specimen’s aggregates were replaced by BOFS, which had a high emissivity of 0.86 across the sky window. In the indoor and outdoor tests, the temperature change was recorded to estimate the thermal performance of specimens. According to the quantitative calculation, when the substitution of BOFS was higher than 55 wt.%, the specimens had a better radiation cooling ability. Among these specimens, the specimen with the BOFS substitution of 75 wt.% absorbed the most heat inside the body, contributing to less heat remaining in the environment. Furthermore, because Newton’s cooling energy accounted for about 90% of the stored energy within 7 h, the heat dissipation after the seventh hour was primarily radiation cooling, corresponding to the emission across the urban boundary layer. As for the mechanical properties, the stability value, indirect tensile strength, and British pendulum number (BPN) were in line with the specifications under the proper BOFS substitution. In conclusion, BOFS has great applicability in pavements due to its thermal performance and mechanical properties. It not only achieves the goal of urban heat island mitigation by radiation cooling, but also reflects the concept of resource sustainability.

Ultrasound-Guided Ilioinguinal/Iliohypogastric Nerve Block versus Ultrasound Guided Transversus Abdominis Plane Block for Lower Abdominal Surgeries: A comparative Clinical Study

Background: Effective pain relief is of utmost importance to anyone undergoing surgery. Postoperative pain relief increases patient comfort and satisfaction. This is best accomplished with a multi-modal approach. Recent trends in minimally invasive surgery and improved recovery protocols have addressed pain treatment in light of these goals. Aim of the work: Comparison between ultrasound-guided Ilioinguinal and Iliohypogastric nerve block with ultrasound-guided transversus abdominis plane block regarding postoperative analgesia in patients scheduled for lower abdominal surgeries. Patients and methods: Seventy patients of ASA I or II, aged 21-50 years, who planned for elective open lower abdominal surgeries were included. They signed an informed consent and were randomly classified into two groups: [Group I] scheduled for Ilioinguinal and Iliohypogastric nerve block, and [Group II] scheduled for transversus abdominis plane block guided by ultrasound. Postoperative pain assessment was conducted by numerical rating score. Results:In inguinal hernia repair, pain score at rest was significantly reduced in the TAP group when compared to Group-I at 30 minutes till the seventh hour postoperatively and at 12 up to 15 hours postoperatively. Also, in the CS group, the pain score was significantly decreased in TAP block when compared to nerve block at 90, 105 minutes, and from 4 up to seventh postoperative hours. With movement, pain scores were significantly lower at the 4, 5, 6, 7, 8, 9, 10, and 11 -hours in group II in inguinal hernia. It was significantly decreased at the 90 minutes to 2 -hours in group II in the CS subgroup. The total analgesic requirements were significantly lower in group II. Conclusion: Ultrasound-guided TAP block tended to be more effective than Ultrasound-guided II/IH nerve block in lowering postoperative pain scores and decreasing the need for rescue analgesia in lower abdominal surgeries.

Eternity and Time in the Gospel of John

The relationship between eternity and time has been a perennial issue in Johannine studies. Consider that the pre-existent Word of God enters in time and within concrete human history, thus bridging eternity and time. The evangelist describes both Jesus’ divinity as the Logos, existing in an eternal, timeless “beginning” (1:1), and Jesus’ true humanity as the historical person who was made “flesh” (1:14), taking on the human condition in all its fragility, in its temporality, suffering and death. His earthly mission was fulfilled “in time” – in a concrete “hour”. Reading the Fourth Gospel in this light may help us appreciate the Johannine understanding of eternity and time. This survey presents the various interpretations of the expression “in the beginning” and also of the time-related noun “hour”, used by the evangelist on certain occasions with detailed precision: “it was about the tenth hour” (1:39); “it was about the sixth hour” (4:6; 19:14); and “at the seventh hour” (4:52), referring always to a particular chronological point in time. However, this article does not place undue emphasis on the numbers recounting the particular hour, but rather tries to identify the links of each hour with the accompanying words and deeds of Jesus.

Hourly Rainfall Distribution Pattern in the Northern Coast of Bolaang Mongondow

The data for this research is compiled from the records of hourly rainfall between 1993 to 2014 which was generated from several. Automatic Rainfall Stations namely; Ayong-Bumbung Climatology Station, Sangkub-Huntuk climatology station, and Sangkub-Pangkusa Climatology Station. The data was then analyzed using statistical methods. Rainfall distribution pattern is based on heavy rainfall recorded by automatic rainfall measuring device. The rainfall data used here are the ones with rainfall depth of more than 50mm. All the data are then analyzed to obtain the frequency of occurrence of each of the rainfall duration. From the result of frequency analysis, it is then determined that certain rainfall duration represents the general rainfall condition in the research area. Research will show that rainfall pattern on the Northern Coast of Bolaang Mongondow, for heavy storm have a tendency of 7 hour duration, with 22% distribution for the first hour, 28% distribution for the second hour, 19% distribution for the third hour, 15% for the fourth hour, 7% for the fifth hour, 6% for the sixth hour, and 3% for the seventh hour.

Amduat-Exemplare von Thutmosis I.: Weitere Fundstücke im Grab KV 38

Summary This article deals with the further exploration in tomb KV 38 in the Valley of Kings. In the course of this exploration in early 2018 I discovered more small mud-plaster fragments of the Amduat book. These different Amduat fragments can be identified as a part of the fourth, sixth, seventh, eighth and tenth hour of the book of Amduat. Therefore, these Amduat fragments prove that possibly the cliff walls of the tomb of king Thutmose I were originally encased and decorated with a complete corpus of the book of Amduat (long version). After an examination of the displayed scenes and their comparison with similar sections of the Amduat from tomb KV 34 it turned out that both specimens show clear differences and that both tombs have manifold artistic variations. Therefore, both specimen are originate from different reigns and were not made by the same king.

Environmental and occupational particulate matter exposures and ectopic heart beats in welders

ObjectivesLinks between arrhythmias and particulate matter exposures have been found among sensitive populations. We examined the relationship between personal particulate matter ≤2.5 µm aerodynamic diameter (PM2.5) exposures and ectopy in...

Design and statistical optimization of an effervescent floating drug delivery system of theophylline using response surface methodology.

The aim of this research was to formulate effervescent floating drug delivery systems of theophylline using different release retarding polymers such as ethyl cellulose, Eudragit® L100, xanthan gum and polyethylene oxide (PEO) N12K. Sodium bicarbonate was used as a gas generating agent. Direct compression was used to formulate floating tablets and the tablets were evaluated for their physicochemical and dissolution characteristics. PEO based formulations produced better drug release properties than other formulations. Hence, it was further optimized by central composite design. Further subjects of research were the effect of formulation variables on floating lag time and the percentage of drug released at the seventh hour (D7h). The optimum quantities of PEO and sodium bicarbonate, which had the highest desirability close to 1.0, were chosen as the statistically optimized formulation. No interaction was found between theophylline and PEO by Fourier Transformation Infrared spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) studies.

Differences between the effects of EDTA and citrate anticoagulants on platelet count and mean platelet volume

Platelet counts on whole blood samples collected into tripotassium salt of EDTA, trisodium citrate (Na3 citr), citrate phosphate dextrose adenine formula 1 (CPDA-1) and acid citrate dextrose formula A (ACD-A), all showed a statistically significant drop (P less than 0.01) after 1 h standing at room temperature (RT) as compared with the immediate (within 30 min) counts. After 1 h the enumeration became stable in the EDTA samples but the drop continued up to 4-6 h in those samples taken into citrate. The decreases in citrate were significant (18-30%, P less than 0.001). The addition of EDTA (1.5 mg/ml) to the citrated samples after the sixth hour count created a significant rise (6-22%, P less than 0.01) in the counts between the sixth and the seventh hour. Our observations show that platelet counts in citrated blood samples are lower than those in EDTA and highlight the necessity to present citrated samples mixed wtih dried EDTA when characterization or quality control of blood and blood components is required. Analysis of the mean platelet volume (MPV) showed significantly lower values (6-13%, P less than 0.05) in the citrated samples as compared to the same samples in EDTA, and a significant increase (4-6%, P less than 0.01) on the addition of EDTA to the citrated samples after the sixth hour analysis.

Pupal Period Affects Calling Behavior of the Wheat Moth, Pseudaletia sequax (Lepidoptera: Noctuidae)

AbstractThe effects of pupal period and age on calling behavior of virgin females of Pseudaletia sequax were determined. Calling behavior of groups of females of similar age of pupation was observed every 10 min for six calling days. Females were considered calling when they assumed a characteristic position: wings and abdomen elevated, displaying the ovipositor and presumably releasing pheromone. Calling behavior was discontinuous. Females with a shorter pupal period took more time to start calling than females with a longer pupal period and called for a longer period. On the first day of calling, females took more time to initiate calling, on average during the seventh hour of the scotophase, whereas on the second day of calling, most females initiated calling during the fifth hour of the scotophase. On subsequent days of calling, the average time to initiate calling changed to the fourth hour of the scotophase. The mean time of calling per day decreased significantly with the number of days since first calling, and the mean number of calling bouts increased with days since first calling.

A proteomic study on postdiapaused embryonic development of brine shrimp (Artemia franciscana)

Encysted gastrula of brine shrimp (Artemia, Crustacea, and Anostraca) provides an excellent model for studying molecular processes of diapause. We report a proteomic study on early molecular responses of Artemia's postdiapaused cysts and found that dehydrated cysts actually store more proteins, in both kind and amount, than developing cysts. We identified 75 differentially expressed proteins over a course of cyst development, and also exploited PTMs of dehydrate cysts. We further surveyed gene expression of postdiapaused cysts in early developmental phases in a 0.5 h interval up to the seventh hour, and discovered that the activation of cellular activities is ignited as early as 0.5 h after rehydration. We traced nine differentially expressed proteins (COXI, COXIII, heat shock proteins (HSP26, HSP60, and HSP70), CDC48, late embryogenesis abundant (LEA), GS1-like protein, and cathepsin L-associated protein (CLAP)) for quantitative transcriptional changes, monitored by real-time PCR, and found these proteins exhibiting distinct expression patterns that suggest complex gene regulations for cyst reactivation after diapause breakage. Future experiments should be designed to focus on early activation concerning signal transduction, energy generation, and PTMs.

Thermoregulatory role of inducible nitric oxide synthase in lipopolysaccharide-induced hypothermia

We have tested the hypothesis that nitric oxide (NO) arising from inducible nitric oxide synthase (iNOS) plays a role in hypothermia during endotoxemia by regulating vasopressin (AVP) release. Wild-type (WT) and iNOS knockout mice (KO) were intraperitoneally injected with either saline or Escherichia coli lipopolysaccharide (LPS) 10.0 mg/kg in a final volume of 0.02 mL. Body temperature was measured continuously by biotelemetry during 24 h after injection. Three hours after LPS administration, we observed a significant drop in body temperature (hypothermic response) in WT mice, which remained until the seventh hour, returning then close to the basal level. In iNOS KO mice, we found a significant fall in body temperature after the fourth hour of LPS administration; however, the hypothermic response persisted until the end of the 24 h of the experiment. The pre-treatment with β-mercapto-β,β-cyclopentamethylenepropionyl 1, O-Et-Tyr 2, Val 4, Arg 8-Vasopressin, an AVP V 1 receptor antagonist (10 μg/kg) administered intraperitoneally, abolished the persistent hypothermia induced by LPS in iNOS KO mice, suggesting the regulation of iNOS under the vasopressin release in this experimental model. In conclusion, our data suggest that the iNOS isoform plays a role in LPS-induced hypothermia, apparently through the regulation of AVP release.

Pulmonary edema develops after recurrent obstructive apneas.

There are anecdotal reports of pulmonary edema after a night of recurrent obstructive apneas (OAs) in humans, but no data on lung water, gas exchange, filling pressure, or cardiac output (Q) exist in these patients. By clamping the endotracheal tube of eight intubated, anesthesized dogs, we created repetitive OAs of 45-s duration at 30-s intervals, for 8 h. Five additional dogs without apneas, but identically instrumented, were studied simultaneously, serving as nonapneic controls. Sa (O(2)) was measured by intraarterial catheter, pulmonary capillary wedge pressure (Pcw), continuous cardiac output (Q), and mixed venous oxygen saturation (Sv(O(2))) were measured by flotation catheter. Basal and hourly hemodynamics and blood gases (arterial and venous) under steady state respiration were measured. Venous admixture (Q S/Q T) was calculated by standard equations. Pa(O(2)) from the beginning to the end of the experiment fell from 89.6 to 82.8 mm Hg in apneic animals and from 92.2 to 85.5 mm Hg in controls. The Q S/Q T increased in both groups but more so in the apnea group (3.3 to 19.4%) than in nonapneic controls (3.1 to 7.9%). Neither Q nor Pcw changed significantly in either group. Lung wet/dry weight was 5.40 +/- 0.93 in apneic animals and 5.00 +/- 0.67 in controls. Light microscopy showed gross alveolar fluid in three apneic dogs, and electron microscopy showed interstitial fluid in two additional apneic dogs. One of the lung edema dogs expired of acute heart failure in the seventh hour of the experiment. Worsening of gas exchange and histology suggest that lung edema can result from recurrent OAs.

Evidence for an altered luteinizing hormone sensitivity to naloxone in pathological hyperprolactinaemia

The underlying mechanisms involved in the pathogenesis of amenorrhoea in hyperprolactinaemic states still remain unclear. Conflicting information exists on the role of endogenous opiates on gonadotrophin disturbances in this pathological condition. In this study we have undertaken a detailed investigation of LH and PRL secretion before and during administration of naloxone, an opioid receptor blocker, in hyperprolactinaemic women with or without ovarian function in order to assess the role of ovarian steroids upon naloxone induced LH and PRL release. Five anovulatory and six ovulatory subjects with hyperprolactinaemia were studied before and during naloxone infusion. Five normo-prolactinaemic ovulatory subjects were included as controls. All ovulatory subjects were studied during the luteal phase of a menstrual cycle. Blood was sampled every 10-20 minutes over a 16-hour period on two alternate days. On study day 1 (control day), subjects received two sets of saline infusion every 6 hours and one saline bolus at the beginning of the seventh hour; on study day 3 (naloxone day), they received a saline infusion during the first 6 hours, an intravenous bolus of naloxone (20 mg) at the beginning of the seventh hour and then a continuous naloxone infusion (1.6 mg/hour) during the ensuing 6 hours. Pituitary LH responsiveness and reserve were assessed on both study days by the subsequent administration of 5 and 95 micrograms of GnRH 4 hours before the completion of each sampling period. Serum concentrations of LH, PRL, oestradiol and progesterone were determined by radioimmunoassay. LH and PRL pulse detection and characteristics were analysed by the Cluster program. Serum PRL levels in hyperprolactinaemic anovulatory and ovulatory subjects were significantly elevated above the normal range. Oestradiol and progesterone serum levels during the luteal phase in women with hyperprolactinaemia and regular menses were similar to those in control ovulatory subjects. Mean LH concentrations increased during naloxone infusion (P < 0.05) in ovulatory hyperprolactinaemia and controls, whereas PRL increased (P < 0.05) only in the group of control subjects. LH pulse amplitude and pulse interval were increased by naloxone (P < 0.05) in all the ovulatory subjects, with no significant changes in anovulatory hyperprolactinaemic women. PRL pulse characteristics were modified significantly by naloxone only in the control group. On day 1, GnRH administration increased LH in all groups, whereas a consistently lower pituitary LH response was observed after naloxone (day 3). Serum PRL levels significantly increased after GnRH administration on day 1 only in normal women, whilst on day 3 this GnRH-dependent PRL releasing effect was significantly attenuated. The absence of stimulatory effects of naloxone on LH in anovulatory hyperprolactinaemia implies that endogenous opiates do not play a significant role in the mechanisms governing hypothalamic amenorrhoea in this syndrome. The results in subjects with ovulatory hyperprolactinaemia suggest the existence of an active role of ovarian steroids on naloxone induced LH release. These data, along with those previously reported in normal women throughout the menstrual cycle, are consistent with the concept that sex steroid hormones contribute to the underlying mechanisms involved in the opioidergic control of LH and PRL release. Whether PRL by itself or through other non-opioid neuroendocrine pathways alters the hypothalamic-gonadotroph unit still requires further investigation.

Pemoline Effects on Children with ADHD: A Time-Response by Dose-Response Analysis on Classroom Measures

To evaluate the dose-response by time-response characteristics of pemoline (Cylert) on dependent measures of behavior and academic performance in a laboratory classroom. After a 2-week baseline, a double-blind crossover design was used to compare placebo, 18.75 mg, 37.5 mg, 75 mg, and 112.5 mg of pemoline, q.a.m., with each dose administered for 1 week. Medication was given at 9:00 A.M., and performance was measured beginning immediately and beginning 2, 4, and 6 hours after ingestion. The dependent measures included number of math problems completed correctly, teacher-recorded rates of on-task behavior and noncompliance, and teacher ratings on an Abbreviated Conners Teacher Rating Scale. There were linear effects of medication, with pemoline doses greater than 18.75 mg having an effect beginning 2 hours after ingestion and lasting through the seventh hour after ingestion. Results are contrasted with widespread misbeliefs regarding pemoline's time course and efficacy.

Caffeine reduces low-frequency delta activity in the human sleep EEG

In view of the hypothesis that adenosine is involved in sleep regulation, the effects of the adenosine antagonist caffeine on sleep and sleep EEG were investigated in eight young males. Compared to the placebo condition, caffeine (100 mg) administered at bedtime prolonged sleep latency and reduced sleep efficiency and stage 4 of non-rapid eye movement sleep (NREMS). Electroencephalographic slow-wave activity (SWA, spectral power density in the 1.75-4.5-Hz band) was reduced, whereas power density in the spindle frequency range was slightly enhanced. The suppression of SWA was limited to the first NREMS episode. Caffeine reduced the power density mainly in the lowest delta band, in contrast to the changes during physiological sleep that encompass both the delta and theta bands. Caffeine levels in saliva, assessed in a separate experiment, decreased from 7.5 mumol/l in the first hour of sleep to 3.5 mumol/l in the seventh hour. In the night following caffeine administration, stage 4 sleep had reverted to the baseline level, but sleep latency was still increased, and stage 2 sleep, as well as SWA in the first NREMS episode, were reduced. The data show that even a low dose of caffeine affects the sleep EEG. However, the effects of caffeine did not completely mimic the spectral changes observed during physiological sleep.

The effects of opioid blockade and GnRH administration upon luteinizing hormone secretion in patients with anorexia nervosa during the stages of weight loss and weight recovery.

We examined the functional status of the hypothalamic-opioid system involved in LH secretion and the pituitary LH sensitivity and reserve in patients with anorexia nervosa were studied during body weight loss and weight recovery. We measured the temporal relationship between weight recovery, expression of hypothalamic-opioid activity and pituitary GnRH responsiveness, and resumption of ovulatory cycles. Five patients with anorexia nervosa were prospectively studied during weight loss and amenorrhoea, subsequently when they reached their ideal body weight but still remained amenorrhoeic and thereafter every 6 months until resumption of ovulatory cycles; one patient was studied only during weight loss, two during ideal body weight and amenorrhoea and one during ideal body weight and ovulatory cycles. Blood was sampled every 10 minutes over a 16-hour period on two alternate days. On study day 1 (control day), patients received two sets of saline infusion every 6 hours and one saline bolus at the beginning of the seventh hour; on study day 3 (experimental day), they received a saline infusion during the first 6 hours, an intravenous bolus of naloxone (20 mg) at the beginning of the seventh hour and then a continuous naloxone infusion (1.6 mg per hour) during the ensuing 6 hours. Pituitary LH sensitivity and reserve were assessed on both study days by the subsequent administration of 5 and 95 micrograms of GnRH 4 hours before the completion of each sampling period. Patients in ideal body weight and ovulatory cycles as well as five normal menstruating women included in the study for comparative purposes, were studied during the midluteal phase of a cycle. LH, oestradiol and progesterone were determined by radioimmunoassay. Areas under the LH curve were calculated by the trapezoid method; LH pulse detection was carried out by the program Cluster. Naloxone administration to patients with anorexia nervosa in the weight loss phase, did not significantly modify their serum LH levels nor the characteristics of its pulsatile secretion. Administration of the opioid blocker induced a significant increase in serum LH concentrations only in those patients in ideal body weight and amenorrhoea who resumed ovulatory cycles within the 6 months following the last study as well as in patients with an ideal body weight and ovulatory cycles and in normal controls. All patients and subjects who responded to naloxone administration exhibited significant increases in the area under the LH curve, mean LH pulse amplitude and peak area. Patients in ideal body weight and amenorrhoea who did not resume ovulatory cycles within the 6 months following the study days, did not respond to naloxone administration. There were no significant correlations between the magnitude of LH response to naloxone administration and the baseline levels of serum oestradiol and progesterone. All patients exhibited significant pituitary LH responses to both GnRH doses, regardless of the stage of the disease; however, the pituitary responsiveness shown by patients in ideal body weight was significantly higher than that presented by patients in weight loss. There were no significant differences between the responses to GnRH exhibited by patients in ideal body weight and amenorrhoea who responded to naloxone administration and those shown by patients in the same clinical condition but who were insensitive to opioid blockade. The re-establishment of hypothalamic-opioid inhibitory activity involved in LH secretion in patients with anorexia nervosa during the phase of weight gain predicts imminent restoration of ovulatory cycles. Pituitary LH response to exogenous GnRH during weight recovery does not accurately predict the outcome of the disease regarding reinitiation of menstrual cycles; however, it might be an indicator that the normal function of the hypothalamic-pituitary axis is being restored.