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PubMed2004

Salt supplementation improves orthostatic cerebral and peripheral vascular control in patients with syncope.

Salt supplementation improves orthostatic tolerance in many patients with posturally related syncope (PRS). This study aimed to examine whether in those patients who responded to salt loading there was also evidence of improved cerebral autoregulation and more powerful peripheral vasoconstriction during orthostasis. Eleven PRS patients were studied before and after ingestion of 100 mmol/d slow sodium for 2 months. Subjects underwent an orthostatic stress test of combined head-up tilting and lower body suction. We continuously monitored heart rate (ECG), blood pressure (Finapres), forearm and cerebral blood flow velocities (Doppler ultrasound), and end-tidal carbon dioxide (CO2). Forearm vascular resistance was calculated from pressure divided by velocity. Cerebral autoregulation was assessed from the correlation coefficient of the relationship between cerebral blood pressure and velocity. Salt loading had no effect on resting heart rate or blood pressure. Symptoms and orthostatic tolerance significantly improved in 10 of the patients. This was associated with a significant increase in the maximal forearm vasoconstriction from 64.4%+/-13.7% (SEM) to 135.2%+/-23.9% (P<0.005). The relationship between cerebral velocity and pressure was less strong (before salt: r=0.74+/-0.8; after salt: r=0.41+/-0.1; P<0.02), indicating improved autoregulation. End-tidal CO2 levels were not different between the 2 tests. Salt loading in PRS patients increases orthostatic tolerance and improves cerebrovascular and peripheral vascular control without affecting blood pressures. These changes are likely to contribute to the beneficial effects of salt loading in these patients.

Adult↗

PubMedDate not supplied

Bilateral Parry-Romberg syndrome associated with retinal vasculitis.

PURPOSE: To describe an unusual case of bilateral progressive facial hemiatrophy (Parry-Romberg syndrome (PRS)) associated with retinal vasculitis. METHODS: In a 37-year-old man with bilateral PRS, retinal vasculitis of the right eye was evident on fundus examination and fluorescein angiography. Right temporalis muscle biopsy and needle electromyography of the masseter muscles were performed. The patient underwent immunosuppressive therapy and retinal laser photocoagulation. RESULTS: Biopsy specimens showed large fibrosis with focal lymphohistiocytic infiltration of the muscle fibers. Electromyographic findings are consistent with a primary muscle disease. Visual acuity improved from 20/25 to 20/20 in the right eye with a follow-up of one year. CONCLUSIONS: The evidence of retinal vasculitis and the histologic findings of facial changes observed in this PRS case could support the pathogenetic model of a chronic inflammatory process as a plausible explanation for progressive facial hemiatrophy.

Adult↗

PubMed2005

Biofeedback therapy after perineal rectosigmoidectomy or J pouch procedure.

The aim of this study was to determine the outcome and to identify possible predictors of success for biofeedback therapy after perineal rectosigmoidectomy (PRS) or coloanal or ileoanal J pouch. A retrospective chart review of all patients with electromyography-based biofeedback therapy due to fecal incontinence after PRS or a J pouch procedure was undertaken. Follow-up was obtained by telephone survey. Fourteen patients (4 men and 10 women) were included in this study. In the 9 patients after PRS, the frequency of daily bowel movements was 3.6+/-2.8 preoperatively, 4.1+/-3.2 prebiofeedback, and 2.2+/-1.3 postbiofeedback (P<.05). The frequency of daily incontinent episodes was reduced from 2.4+/-2.2 preoperatively and 2.0+/-1.9 prebiofeedback to 0.26+/-0.3 postbiofeedback (P<.05). The incontinence scores decreased from 17+/-3.1 preoperatively to 16+/-2.1 prebiofeedback and to 8.2+/-5 postbiofeedback (P<.001). At a follow-up of 15.8+/-7.1 months, 5 patients after the J pouch had decreased daily bowel frequency from 6.6+/-4.2 prebiofeedback to 3.3+/-2 postbiofeedback and 3.1+/-2 at follow-up (P<.05). The frequency of daily incontinent episodes was reduced from 1.9+/-1.3 prebiofeedback to 0.9+/-0.7 postbiofeedback to 0.7+/-0.8 at follow-up (P<.05). The incontinence scores decreased from 13.4+/-2.7 prebiofeedback to 8.8+/-5.1 postbiofeedback to 6.8+/-5.5 at follow-up (P<0.05). In both groups, the postbiofeedback incontinence score correlated with the prebiofeedback incontinence score. Furthermore, there was no correlation between outcome and age, interval between surgery and biofeedback therapy, frequency of biofeedback sessions, or manometry results in either group. Biofeedback therapy is an effective option for patients with fecal incontinence after perineal rectosigmoidectomy or colonic or ileal J pouch.

Adult↗

PubMed1998

Single-breath method for assessing the viscoelastic properties of the respiratory system.

In order to explain the time dependency of resistance and elastance of the respiratory system, a linear viscoelastic model (Maxwell body) has been proposed. In this model the maximal viscoelastic pressure (Pvisc.max) developed within the tissues of the lung and chest wall at the end of a constant-flow (V') inflation of a given time (tI) is given by: Pvisc,max = R2V'(1-e(-tI/tau2), where R2 and tau2 are, respectively, the resistance and time constant of the Maxwell body. After rapid airway occlusion at t1, tracheal pressure (Ptr) decays according to the following function: Ptr(t) = Pvisc(t) + Prs,st = Pvisc,max(etocc/tau2)+ Prs,st, where tocc/is time after occlusion and Prs,st is static re-coil pressure of the respiratory system. By fitting Ptr after occlusion to this equation, tau2 and Pvisc,max are obtained. Using these values, together with the V' and tI pertaining to the constant-flow inflation preceding the occlusion, R2 can be calculated from the former equation. Thus, from a single breath, the constants tau2, R2 and E2 (R2/tau2) can be obtained. This method was used in 10 normal anaesthetized, paralysed, mechanically ventilated subjects and six patients with acute lung injury. The results were reproducible in repeated tests and similar to those obtained from the same subjects and patients with the time-consuming isoflow, multiple-breath method described previously.

Adult↗

PubMed2026

Assessing the comorbidity between asthma and depression through polygenic risk scoring and time-to-event models.

BACKGROUND: Patients with asthma have an increased risk of developing depression, affecting their quality of life. To date, the processes contributing to this comorbidity remain unclear. METHODS: We integrated two large genome-wide association studies (88,486 patients with asthma and 447,859 controls; 412,024 patients with depression and 1,587,577 controls) with cross-sectional and longitudinal information available from the All of Us Research Program (N = 87,167) through polygenic risk scoring (PRS), Cox proportional-hazards models, one-sample Mendelian randomization (MR), and gene-set and drug-repurposing analyses. RESULTS: We observed that depression PRS was associated with increased asthma risk (hazard ratio, HR = 1.13, 95% CI = 1.09-1.17), also when accounting for comorbidity status (HR = 1.08, 95% CI = 1.04-1.12). Conversely, the effect of asthma PRS was null after accounting for comorbidity status. One-sample MR analysis showed an effect of depression genetic liability on asthma, ranging from beta = 0.36 ± 0.03 when considering a linear relationship to beta = 3.21 ± 0.31 when considering possible nonlinear relationships. Conversely, the effect of asthma genetic risk on depression was null after accounting for potential confounders. The gene-set analyses showed that asthma and depression polygenic risks share biological processes, molecular functions, and cellular components related to the immune system and the lung-brain axis. CONCLUSIONS: Genetic predisposition contributes to asthma-depression comorbidity through direct effects and shared pathogenic processes. These findings highlight the potential to develop targeted interventions to prevent and treat the co-occurrence of respiratory and neuropsychiatric disorders.

Comorbidity↗

PubMed2026

Large-scale multi-omics enhance risk prediction for type 2 diabetes.

BACKGROUND: Polygenic risk scores (PRS), metabolomics, and proteomics have each shown promise in improving type 2 diabetes risk prediction, but their combined utility beyond established clinical models remains unclear. We aimed to evaluate whether integrating multi-omics biomarkers enhances 10-year type 2 diabetes risk prediction beyond single-omics extensions and the clinical Cambridge Diabetes Risk Score (CDRS), which includes HbA1c measurements. METHODS: We analysed data from 42,840 UK Biobank participants without diagnosed diabetes at baseline. The study population was split into a derivation set (Phase 1 metabolomics release, N = 23,108) to fit models and an independent validation set (Phase 2 release, N = 19,732) to evaluate performance. Data for a PRS for type 2 diabetes, 11 metabolites, and 15 proteins were added to the CDRS to develop multi-omics prediction models. Model performance was evaluated using Harrell's C-index and the net reclassification index (NRI). RESULTS: During 10 years of follow-up, 1090 participants developed incident type 2 diabetes. Among individual omics layers, proteomics contributed the greatest improvement in predictive performance, increasing the C-index from 0.862 (clinical CDRS) to 0.884 (ΔC-index; + 0.022; P < 0.001), with a continuous NRI of 42.0%. The full multi-omics model further significantly increased the C-index compared to a model combining the clinical CDRS with proteomics data (C-index, 0.891; ΔC-index; + 0.007; P < 0.001). CONCLUSION: Integrating proteomics, metabolomics, and a diabetes-PRS into a clinical model substantially improves type 2 diabetes risk prediction beyond single-omics extensions. Several of the selected proteins and metabolites are on cardiovascular disease pathways, highlighting the link between diabetes and cardiovascular risk. However, the C-index difference between the proteomics extended and full multi-omics extended models is small, and the clinical models extended with proteomics data would be easier to translate into routine care because it needs only the measurement of 15 proteins. External validation and cost-effectiveness analyses are needed to support clinical adoption.

Humans↗

PubMed1987

WR-2721 and high-dose cisplatin: an active combination in the treatment of metastatic melanoma.

Cisplatin, alone or in combination with other chemotherapeutic agents, is relatively inactive against metastatic melanoma. Prior trials have demonstrated partial response (PR) rates of less than 10% with cisplatin alone. WR-2721 is an organic thiophosphate compound, which in the animal model, selectively protects normal tissues against the toxicity of cisplatin chemotherapy. During the course of a phase I trial of WR-2721 and cisplatin, objective PRs were noted in patients with far advanced metastatic melanoma. These observations led us to perform a phase II trial of WR-2721 and cisplatin. Thirty-six patients received 128 courses of WR-2721 before cisplatin (60 to 150 mg/m2). All patients had progressive disease before treatment. Objective PRs were observed in 19 of 36 evaluable patients (53%). Three additional patients had minor responses (MRs). PRs occurred in 53% of patients with prior chemotherapy (ten of 19). Sites of responding metastases were subcutaneous disease (15 of 19 patients), lymph nodes (16 of 21 patients), lung (four of ten patients), and liver (eight of 17 patients). The median duration of response was 4 months, with a mean of 4.5 months (range, 1 to 8 months). Transient nephrotoxicity was observed in less than 5% of courses. In all cases, renal function returned to normal within 1 to 2 weeks. Hematologic toxicity was mild and infrequent. Nine patients developed peripheral neuropathy following a median cisplatin dose of 670 mg/m2. Twenty patients experienced mild clinical hearing loss. These data suggest that WR-2721 may potentiate the antitumor activity of cisplatin in metastatic melanoma.

Adult↗

PubMed1990

An early phase II study of CPT-11: a new derivative of camptothecin, for the treatment of leukemia and lymphoma.

An early phase II study of a new camptothecin analog and an inhibitor of topoisomerase I, CPT-11, was conducted in 62 patients with refractory leukemia and lymphoma by four different treatment schedules in a multiinstitutional cooperative study. CPT-11 therapy resulted in four complete remissions (CRs) and three partial remissions (PRs) in 29 assessable non-Hodgkin's lymphoma (NHL) patients, one PR in three Hodgkin's disease (HD), one CR and one PR in 11 acute lymphoblastic leukemia (ALL), and one PR in 15 acute myelogenous leukemia (AML) patients. Single infusion of 200 mg/m2 every 3 to 4 weeks produced no response in both leukemia and lymphoma patients. Sixty-minute infusions of 40 mg/m2/d for 5 days every 3 to 4 weeks or for 3 days weekly produced four CRs (17%) and four PRs (17%) in 24 patients with malignant lymphoma. Sixty-minute infusions of 20 mg/m2 twice a day for 7 days every 3 to 4 weeks resulted in one CR and two PRs in 12 patients with acute leukemia. No response was seen in an acute leukemia patient by another treatment schedule. CPT-11 was effective in two (15%) of 13 primarily refractory leukemia and lymphoma cases, in two of four relapsed cases, and in seven (17%) of 41 relapsed and refractory cases. Major side effects were leukopenia (91%) and gastrointestinal (GI) (76%). CPT-11 was shown to be effective against refractory leukemia and lymphoma, and thus deserves further clinical study; the novel antitumor activity mode of this drug predicts no cross-resistance to presently available antitumor drugs.

Adolescent↗

PubMed1990

Phase II study of cytarabine and etoposide in children with refractory or relapsed non-Hodgkin's lymphoma: a study of the French Society of Pediatric Oncology.

Twenty-five children or adolescents with relapsed or refractory non-Hodgkin's lymphoma (NHL) were included in this phase II study of the combination of cytarabine (ARA-C) 50 mg/m2/d by 12 hours continuous infusion day 1 to day 5, ARA-C 3 g/m2/d in 3 hours day 1 to day 4, and etoposide (VP 16) 200 mg/m2 daily from day 1 to day 4. Twelve patients had B-cell, 12 T-cell, and one non-T, non-B-cell lymphoma; according to Murphy's staging system, 15 had stage III and nine stage IV disease with bone marrow involvement at diagnosis. All had previously received ARA-C by push or continuous infusion. Two patients had received epipodophyllotoxins. At the time of the study, three children had initial refractory disease, 18 were in first relapse (14 on therapy), two in first refractory relapse, and two in second relapse (on therapy). The overall response rate (RR) was 60%: eight complete responses (CRs), seven partial responses (PRs) (two became CRs after a second course). The RR was 66% (four CRs plus four PRs) in B-cell and 54% (four CRs, three PRs) in non-B-cell NHL. It was 20% (one PR per five patients) in initial or relapsed refractory disease. In four patients with measurable CNS disease, there were three CRs. Duration of response was nonassessable since all the responding patients received high-dose polychemotherapy followed by autologous bone marrow transplantation (ABMT) (five are alive with long follow-up [FU]). Toxicity was marked mostly by pancytopenia for 2 weeks, and half the patients encountered a grade-3 infection. One severe diarrhea was observed. In conclusion, high-dose ARA-C (HD-ARA-C) and VP 16 are an effective regimen in relapsed NHL, especially with CNS disease, and its toxicity is acceptable with regards to the prognosis of the disease.

Adolescent↗

PubMed1996

Phase II trial of paclitaxel and cisplatin in women with advanced breast cancer: an active regimen with limiting neurotoxicity.

PURPOSE: A phase II study of paclitaxel and cisplatin in patients with advanced breast cancer was performed to determine the objective response rate and make further observations about the toxicity of this regimen. PATIENTS AND METHODS: Patients were required to have histologically proven adenocarcinoma of the breast with no more than one chemotherapeutic treatment for advanced disease. Treatment consisted of paclitaxel 200 mg/m2 administered as a 24-hour intravenous (i.v.) infusion followed by cisplatin 75 mg/m2 i.v. Patients received granulocyte colony-stimulating factor (G-CSF) 5 micrograms/kg subcutaneously on day 3 until WBC recovery. Cycles were repeated every 21 days. Patients continued to receive therapy until disease progression or unacceptable toxicity. RESULTS: Forty-four patients entered the trial. Forty-two patients were assessable for response. Nineteen patients (43%) had no prior chemotherapy and 41 had no chemotherapy for metastatic disease. The median number of cycles administered per patient was five (range, one to seven). There were five complete responses (CRs) (11.9%) and 17 partial responses (PRs) (40.5%), with an overall response rate of 52.4% (95% confidence interval [CI], 36.4% to 68.0%). Nine patients had stage III disease. The response rate for this group was 66.7% (95% CI, 33.0% to 92.5%), with three CRs and three PRs. Among 35 patients with stage IV disease, there were two CRs and 14 PRs, with an overall response rate of 48.5% (95% CI, 30.8% to 66.5%). Overall, the median response duration was 10.6 months. Thirty patients (68%) developed transient grade 4 neutropenia. Cumulative neuropathy was the major dose-limiting toxicity. After five cycles of chemotherapy, 96% of patients had at least grade 1 neurotoxicity and 52% had at least grade 2 neurotoxicity. One patient had a toxic death after cycle 1 of therapy. CONCLUSION: The combination of paclitaxel and cisplatin as first-line chemotherapy for women with advanced breast cancer is an active regimen. However, the cumulative neurotoxicity was significant and dose-limiting in the majority of patients.

Adenocarcinoma↗

PubMed1997

Megestrol acetate and aminoglutethimide/hydrocortisone in sequence or in combination as second-line endocrine therapy of estrogen receptor-positive metastatic breast cancer: a Southwest Oncology Group phase III trial.

PURPOSE: A phase III randomized trial was performed to determine whether combination hormonal therapy with aminoglutethimide (AG) and hydrocortisone (HC) plus megestrol acetate (MA) improved response rates, response duration, or increased survival over the sequential use of each hormone in women with estrogen receptor-positive metastatic breast cancer (MBC) who had maintained stable disease for at least 6 months or responded to tamoxifen. PATIENTS AND METHODS: Two hundred eighty-eight postmenopausal women with progressive estrogen receptor-positive MBC were randomly selected to receive MA 40 mg four times daily (arm I), AG 250 mg four times daily with HC 40 mg daily in divided doses (arm II), versus the combination of MA plus AG given at the same dosages (arm III). Patients on arms I and II who progressed after an adequate trial were crossed over to the other treatment arm. RESULTS: Two hundred thirty-five eligible patients were evaluated for response, time to treatment failure, and survival. Response was only reported for patients with measurable disease and was not statistically different among the three arms. There were two partial responses (PRs) on MA (6%), four complete responses (CRs) and six PRs on AG (24%), and eight PRs and three CRs on MA plus AG (23%) in 32, 42, and 48 measurable patients, respectively. Median times to treatment failure were also similar at 5, 4, and 7 months. Survival was also not statistically different among the three arms at 26, 27, and 26 months for arms I, II, and III, respectively. Toxicity was greater in the two AG arms with respect to fatigue, nausea and vomiting, and rash. CONCLUSION: With the exception of toxicity, there is no response, time to treatment failure, or survival benefit for any one group when comparing MA, AG, or the combination at their stated doses in women with estrogen receptor-positive MBC who had previously responded to or stabilized with tamoxifen.

Adult↗

PubMed1998

Phase I/II study of the CAPABLE regimen for patients with poorly differentiated carcinoma of the nasopharynx.

PURPOSE: To evaluate the role of aggressive combination chemotherapy in patients with poorly differentiated carcinoma of the nasopharynx (NPC). PATIENTS AND METHODS: In a prospective phase I/II study, 90 chemotherapy-naive patients with NPC (21 with very advanced locoregional disease, 18 with locoregional persistent and/or recurrent disease postradiotherapy, and 51 with metastatic disease) were treated with cyclophosphamide, doxorubicin, cisplatin, methotrexate, and bleomycin (CAPABLE). Two schedules of this regimen were used over a 9-year period, with the second schedule being a modification of the first in an attempt to minimize treatment-related toxicity. RESULTS: Of 21 patients with very advanced local disease, one had a complete response (CR) and 17 had partial responses (PRs) (response rate, 86%). Seventeen of these 21 patients had subsequent radiotherapy. Of 17 patients with measurable locoregional disease either persistent and/or recurrent postradiotherapy, there were four CRs and three PRs (response rate, 41%). Of 44 patients with measurable metastatic disease, there were three CRs and 32 PRs (response rate, 80%). The median survival durations for these three groups of patients were 47, 16, and 14 months, respectively. The two chemotherapy schedules had similar received dose-intensities (RDIs) and produced similar response rates and survival. Toxicity was severe with frequent mucositis and myelosuppression. Overall, 37 patients required at least one hospital admission for management of toxic side effects and there were seven drug-related deaths. Three of the deaths were due to fulminant hepatitis, likely from reactivation of hepatitis B. CONCLUSION: This aggressive regimen provides a high rate of tumor response, but limited palliation for most patients with recurrent or metastatic NPC. The results with chemotherapy followed by radiotherapy for patients with very advanced local disease are encouraging, but proof of benefit would require evaluation in a randomized trial.

Adult↗

PubMed2002

Preoperative chemotherapy followed by surgery compared with primary surgery in resectable stage I (except T1N0), II, and IIIa non-small-cell lung cancer.

PURPOSE: To evaluate whether preoperative chemotherapy (PCT) could improve survival in resectable stage I (except T1N0), II, and IIIA non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: A randomized trial compared PCT to primary surgery (PRS). PCT consisted of two cycles of mitomycin (6 mg/m(2), day 1), ifosfamide (1.5 g/m(2), days 1 to 3) and cisplatin (30 mg/m(2), days 1 to 3), and two additional postoperative cycles for responding patients. In both arms, patients with pT3 or pN2 disease received thoracic radiotherapy. RESULTS: Three hundred fifty-five eligible patients were randomized. Overall response to PCT was 64%. There were two preoperative toxic deaths. Postoperative mortality was 6.7% in the PCT arm and 4.5% in the PRS arm (P =.38). Median survival was 37 months (95% confidence interval [CI], 26.7 to 48.3) for PCT and 26.0 months (95% CI, 19.8 to 33.6) for PRS (P =.15). Survival differences between both arms increased from 3.8% (95% CI, 1.3% to 25.1%) at 1 year to 8.6% (95% CI, 2.64% to 24.4%) at 4 years. A quantitative interaction between N status and treatment was observed, with benefit confined to N0 to N1 disease (relative risk [RR], 0.68; 95% CI, 0.49 to 0.96; P =.027). After a nonsignificant excess of deaths during treatment, the effect of PCT was significantly favorable on survival (RR, 0.74; 95% CI, 0.56 to 0.99; P =.044). Disease-free survival time was significantly longer in the PCT arm (P =.033). CONCLUSION: Although impressive differences in median, 3-year, and 4-year survival were observed, they were not statistically significant, except for stage I and II disease.

Adult↗

PubMed1997

Diagnosing ADHD (predominantly inattentive and combined type subtypes): discriminant validity of the behavior assessment system for children and the achenbach parent and teacher rating scales.

Compared the effectiveness of discriminating attention deficit/hyperactivity disorder (ADHD) subtypes using the Parent Rating Scale (PRS) and Teacher Rating Scale (TRS) of the Behavior Assessment System for Children (BASC) and the Parent Report Form and Teacher Report Form (TRF) of the Achenbach Child Behavior Checklist (CBCL). To determine the extent to which these scales measured similar behaviors, Pearson Product-Moment Correlations were computed for the parent scales (PRS and CBCL) and for the teacher scales (TRS and TRF). Results indicated that correlations were significant for a number of scales. Discriminant analysis does not suggest a strong advantage of either measure in differentiating children with ADHD from those who do not meet criteria for ADHD, except for the BASC TRS which has better predictive ability for children who do not meet ADHD criteria. For subtypes of ADHD, and specifically the ADHD: Predominantly Inattentive subtype, however, results would favor the use of the BASC PRS and TRS.

Aggression↗

PubMed1984

Effects of chronic administration of amiodarone on kinetics of metabolism of iodothyronines.

Treatment with amiodarone, an iodinated anti-arrhythmic drug, is associated with increases in serum rT3 and serum L-T4 with a mild variable decrease in T3. We have examined the metabolic basis for these changes by studying the kinetics of metabolism of 125I-labeled iodothyronines in rabbits given amiodarone (20 mg/kg BW) for 3 weeks. The mean +/- SE MCR of rT3 was significantly (P less than 0.05) lower in amiodarone-treated rabbits (1.88 +/- 0.14 liters/day) than that in the control animals (2.72 +/- 0.25 liters/day), with no appreciable changes in the MCR of T3. The mean MCR of T4 was also significantly lower in amiodarone-treated animals than in controls (0.23 +/- 0.03 vs. 0.37 +/- 0.04 liters/day; P less than 0.05). Amiodarone had no significant effect on daily production rates (PRs) of rT3 or T3, but the PR of T4 showed an increase which was significant (P less than 0.05) when expressed per unit BW. The mean +/- SE molar ratio of daily PRs of T3 and T4 was reduced significantly (P less than 0.05) from 0.75 +/- 0.12 in controls to 0.35 +/- 0.06 in drug-treated rabbits. Amiodarone treatment was also associated with a moderate reduction in the ratio of the PRs of rT3 and T4, but the change was not statistically significant. The overall data suggest that amiodarone administration is associated with a reduction in the MCRs of rT3 and T4 and a reduction in monodeiodination of T4 in the outer ring; monodeiodination of T4 in the inner ring either remains unaffected or decreases moderately.

Amiodarone↗

PubMed2000

Stimulation of gonadotropin-releasing hormone surges by estrogen. II. Role of cyclic adenosine 3'5'-monophosphate.

Release of GnRH surges in female rats is directed by a daily neural signal and occurs only after exposure of the hypothalamus to sustained, elevated estrogen (E2) levels in serum. We have proposed that preovulatory E2 couples the daily neural signal to the circuitry governing GnRH release by a two-step process, which includes stimulation of neuronal progesterone receptors (PRs) by E2 and subsequent activation of PRs by the daily neural signal. In the preceding report we documented that PR activation is obligatory for the stimulation of GnRH surges by E2. In these studies we assess the validity of a second essential feature of this model, that neural signals can activate PRs and thereby prompt the release of GnRH and LH surges. Our efforts specifically focused on the role of cAMP in mediating neural PR trans-activation leading to GnRH surges. To assess whether cAMP may function as a daily neural signal, cAMP levels were examined via a competitive binding assay in anteroventral periventricular nucleus (AVPV) homogenates obtained at 0900, 1200, 1500, 1800, and 2100 h on all days of the estrous cycle. A significant rise in cAMP concentrations was observed at 1500 h on all estrous cycle days. A similar rise at the same time was observed in AVPV tissues of ovariectomized (OVX) rats regardless of steroid treatment. No significant increase in cAMP levels was observed at any time point in homogenates of ventromedial nucleus or cerebral cortex. In a second experiment, female rats were OVX on the afternoon of diestrous day 2 and simultaneously administered 30 microg estradiol benzoate or oil vehicle. On the following day of presumptive proestrus, rats received intracerebroventricular infusions of the cAMP analog, 8-bromo-cAMP, or saline vehicle at 0900 h. Rats treated with 8-bromo-cAMP exhibited LH surges that were advanced by 3 h compared with those in saline-treated controls. This advance did not occur in 8-bromo-cAMP-treated rats not primed with E2, or in E2-treated rats given the antiprogestin RU486. In a third experiment, OVX, estradiol benzoate-primed rats received intracerebroventricular infusions of saline vehicle or the adenylyl cyclase inhibitor SQ22536; although saline-treated rats exhibited normal LH surges, no surges were observed in the rats receiving SQ22536. In additional SQ22536-treated animals, however, LH surge release was rescued and greatly augmented by a pharmacological dose of progesterone. These results demonstrate that 1) cAMP levels in the AVPV are significantly elevated at 1500 h on a daily basis; 2) cAMP elevations in the AVPV can prematurely evoke LH surges by a mechanism that requires PR activation; 3) inhibition of adenylyl cyclase activity in the AVPV blocks LH surges, an action that can be reversed by progesterone; and 4) cAMP generation leads to PR transactivation in the AVPV. Our observations thus provide support for the hypothesis that an increase in intracellular cAMP in the AVPV acts as a component of the daily neural signal required to initiate GnRH and subsequent LH surges, and that transmission of this signal is mediated by cAMP-induced PR trans-activation in the AVPV.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed2000

Stimulation of gonadotropin-releasing hormone surges by estrogen. I. Role of hypothalamic progesterone receptors.

Estrogen (E2) stimulates GnRH surges by coupling a daily neural signal to neuronal circuitries governing GnRH release. We have hypothesized that E2 promotes this coupling process by inducing expression of neuronal transcription factors, which are subsequently activated by neurotransmitter-mediated mechanisms representing the daily neural signal. These experiments tested the specific hypothesis that the progesterone receptor (PR) functions in this manner, viz. as an E2-induced factor whose activation is necessary for the stimulation of GnRH surges. Two complimentary experiments were performed to determine whether activation of hypothalamic PRs is obligatory for the stimulation of GnRH surges by E2. In the first, the effects of a PR antagonist on GnRH and LH surges were assessed in ovariectomized (OVX), E2-primed rats. Rats were OVX on diestrous day 2, treated with 30 microg estradiol benzoate or oil vehicle, sc, and then administered either oil vehicle or the type I antiprogestin, ZK98299 at 0900 h on proestrus. GnRH release rates and plasma LH levels were determined in each animal by microdialysis of median eminence and atrial blood sampling, respectively. Estrogen, but not oil vehicle, treatment evoked robust and contemporaneous GnRH and LH surges in animals that received no PR antagonist on proestrus. Additional treatment with ZK98299, however, completely blocked both GnRH and LH surges. In a second experiment, specific involvement of anteroventral periventricular (AVPV) PRs in E2-induced GnRH surges was assessed. Additional groups of OVX, E2-primed rats were fitted with intracerebroventricular cannulas, and PR antisense oligonucleotides were infused into the third ventricle adjacent to the AVPV to prevent expression of PR in this periventricular region. Animals infused with PR antisense oligos did not exhibit any LH surges, whereas surges were observed in saline-, missense-, and sense oligo-treated controls. Immunohistochemistry confirmed the effectiveness of PR antisense oligonucleotides in blocking PR expression. These findings provide direct support for the hypothesis that activation of PRs, specifically those in hypothalamic regions including the AVPV, is an obligatory event in the stimulation of GnRH surges by E2.

Animals↗

PubMed2000

Regulation of hypothalamic neuropeptide Y Y1 receptor gene expression during the estrous cycle: role of progesterone receptors.

Neuropeptide Y (NPY) stimulates the release of GnRH in an estrogen (E2)-dependent manner, which is important in generating preovulatory GnRH surges. We tested the hypothesis that E2 up-regulates NPY's actions by stimulating NPY Y1 receptor (Y1r) gene expression through a mechanism mediated by E2's ability to induce progesterone (P) receptors (PRs). In initial experiments, a specific Y1r antagonist BIBP3226 was used to confirm the involvement of Y1r in the stimulatory effects of NPY on in vivo GnRH release. Hypothalamic Y1r messenger RNA (mRNA) levels were then measured using competitive RT-PCR and were found to be significantly increased at 1000, 1200, and 1400 h on proestrus compared with other times of the day or cycle stage. Ovariectomy eliminated these increases, and E2 treatment restored them. Additional P treatment produced even larger increases in Y1r mRNA levels. To assess the role of PRs in stimulating Y1r expression, proestrous rats were treated with PR antagonist or oil vehicle and killed at 1200 h. Treatment with PR antagonist completely blocked the proestrous rise in Y1r gene expression. In parallel experiments, the same in vivo PR antagonist treatments also blocked NPY stimulation of GnRH release in vitro. Together our findings reveal that 1) Y1r mRNA levels are increased during the late morning and afternoon of proestrus; 2) Y1r mRNA levels are similarly increased by E2, and to an even greater extent by additional P; and 3) PR antagonism blocks both increased Y1r mRNA and induction of GnRH responsiveness to NPY. These observations support the idea that E2 up-regulates GnRH neuronal responses to NPY through stimulation of Y1r gene expression, and that E2's actions are mediated by the induction and subsequent activation of PRs.

Animals↗