A novel multivariate approach using science-based calibration for direct coating thickness determination in real-time NIR process monitoring.

This study demonstrates an approach, using science-based calibration (SBC), for direct coating thickness determination on heart-shaped tablets in real-time. Near-Infrared (NIR) spectra were collected during four full industrial pan coating operations. The tablets were coated with a thin hydroxypropyl methylcellulose (HPMC) film up to a film thickness of 28 µm. The application of SBC permits the calibration of the NIR spectral data without using costly determined reference values. This is due to the fact that SBC combines classical methods to estimate the coating signal and statistical methods for the noise estimation. The approach enabled the use of NIR for the measurement of the film thickness increase from around 8 to 28 µm of four independent batches in real-time. The developed model provided a spectroscopic limit of detection for the coating thickness of 0.64 ± 0.03 µm root-mean square (RMS). In the commonly used statistical methods for calibration, such as Partial Least Squares (PLS), sufficiently varying reference values are needed for calibration. For thin non-functional coatings this is a challenge because the quality of the model depends on the accuracy of the selected calibration standards. The obvious and simple approach of SBC eliminates many of the problems associated with the conventional statistical methods and offers an alternative for multivariate calibration.

A novel in-line NIR spectroscopy application for the monitoring of tablet film coating in an industrial scale process.

Film coating of tablets is a multivariate pharmaceutical unit operation. In this study an innovative in-line Fourier-Transform Near-Infrared Spectroscopy (FT-NIRS) application is described which enables real-time monitoring of a full industrial scale pan coating process of heart-shaped tablets. The tablets were coated with a thin hydroxypropyl methylcellulose (HPMC) film of up to approx. 28 µm on the tablet face as determined by SEM, corresponding to a weight gain of 2.26%. For a better understanding of the aqueous coating process the NIR probe was positioned inside the rotating tablet bed. Five full scale experimental runs have been performed to evaluate the impact of process variables such as pan rotation, exhaust air temperature, spray rate and pan load and elaborate robust and selective quantitative calibration models for the real-time determination of both coating growth and tablet moisture content. Principal Component (PC) score plots allowed each coating step, namely preheating, spraying and drying to be distinguished and the dominating factors and their spectral effects to be identified (e.g. temperature, moisture, coating growth, change of tablet bed density, and core/coat interactions). The distinct separation of HPMC coating growth and tablet moisture in different PCs enabled a real-time in-line monitoring of both attributes. A PLS calibration model based on Karl Fischer reference values allowed the tablet moisture trajectory to be determined throughout the entire coating process. A 1-latent variable iPLS weight gain calibration model with calibration samples from process stages dominated by the coating growth (i.e. ≥ 30% of the theoretically applied amount of coating) was sufficiently selective and accurate to predict the progress of the thin HPMC coating layer. At-line NIR Chemical Imaging (NIR-CI) in combination with PLS Discriminant Analysis (PLSDA) verified the HPMC coating growth and physical changes at the core/coat interface during the initial stages of the coating process. In addition, inter- and intra-tablet coating variability throughout the process could be assessed. These results clearly demonstrate that in-line NIRS and at-line NIR-CI can be applied as complimentary PAT tools to monitor a challenging pan coating process.

A multivariate approach for the statistical evaluation of near-infrared chemical images using Symmetry Parameter Image Analysis (SPIA).

Near-Infrared Chemical Imaging (NIR-CI) is rapidly gaining importance for the analysis of complex intermediate and final drug products. The availability of both spectral information from the sample and spatial information on the distribution of individual components offers access to greater understanding of manufacturing processes in many stages of pharmaceutical production. One major aspect in terms of chemical imaging is data analysis, since each measurement (image) generates a data cube containing several thousands of spectra (i.e., one spectrum per image pixel). The visual interpretation of component distribution (e.g., homogeneity) is an important issue but subjective. Chemometric methods are therefore required to extract qualitative and quantitative information from each image and enable comparison of several images. In this work, we describe a novel approach for the statistical evaluation of NIR-CI in terms of a multivariate treatment of univariate statistical descriptors characterizing image pixel (e.g., skewness and kurtosis). This technique was called by the authors "Symmetry Parameter Image Analysis" (SPIA), since it enables assessing the symmetry of pixel distributions in terms of different sample attributes. That approach is an innovative way of reporting results with a straightforward relation with attributes such as homogeneity, thus providing the basis for setting up acceptance criteria for good processing conditions or sample homogeneity. Furthermore, this procedure is applicable to determine product variability for large data sets without the need for explicit consideration of each image as its main attributes have been captured by the pixel distributions and their univariate descriptors. The approach is described by means of data obtained by NIR-CI on a powder blend case study (process application). Additionally, SPIA was used for the qualitative classification of tablets (sample application), showing that the approach can be generalized to set up criteria for sample-to-sample similarity and be useful in establishing criteria for e.g., counterfeiting.

A new PAT/QbD approach for the determination of blend homogeneity: combination of on-line NIRS analysis with PC Scores Distance Analysis (PC-SDA).

A novel and straightforward multivariate analytical tool for the qualitative determination of powder blend uniformity using on-line Near-Infrared Spectroscopy (NIRS) is presented. The approach combines current chemometric methods, e.g. spectral pre-processing and Principal Component Analysis (PCA), with (1) a new approach of data analysis to determine the end-point of the blending process, (2) building a design space (DS) for blend homogeneity and (3) developing a solid statistical rationale to stop blending according to Quality-by-Design (QbD) principles of FDA's Process Analytical Technology (PAT) initiative. The new approach comprises calculation of Euclidean distances between PCA scores in a multidimensional space and determination of Moving Block Standard Deviations (MBSDs) of successive Principal Component (PC) scores distances to estimate a time-window during blending where spectral variability decreases to a preset minimum. Hotelling's T(2) statistics is then used to monitor and report blend homogeneity. This technique is called "Principal Component Scores Distance Analysis" (PC-SDA). A Central Composite Design resulting in 10 batches mixed in a bin-blender (same composition, different blender fill level, different number of revolutions) was executed. NIR Chemical Imaging (NIR-CI) in combination with Symmetry Parameter Image Analysis (SPIA) was used to verify the NIRS analyzer response and assess homogeneity of all NIR-active components.

Near-infrared chemical imaging (NIR-CI) for counterfeit drug identification--a four-stage concept with a novel approach of data processing (Linear Image Signature).

A new stage concept was developed to reliably identify counterfeit tablets which are very similar to the genuine drug product. This concept combines single-point near-infrared spectroscopy (NIRS) and near-infrared chemical imaging (NIR-CI) with statistical variance analysis. The advantage of NIR-CI over NIRS is the potential to determine not only the amount, but also the spatial distribution of ingredients within a single tablet. Previously published NIR-CI studies used homogeneity as a key indicator for the identification of counterfeits. The state of the art approach for estimating homogeneity is to record the average and % standard deviation of predicted classification scores (i.e. concentrations) for a given component within a specimen. A disadvantage of this approach is the partial loss of spatial information. In view of this, we developed a new method using much more of the spatial information for the estimation of homogeneity. The method is based on (1) summation and unfolding of multidimensional predicted classification scores, which results in a Linear Image Signature (LIS) and (2) multivariate LIS data analysis (LIS-MVA). It could be demonstrated that this kind of NIR-CI data analysis represents an innovative approach for the identification of counterfeit tablets. Moreover, this procedure is applicable to determine the product variability, i.e. process signature of a given product thus being a valuable tool within the Quality by Design (QbD) approach of the ICH Q8 guideline.

[Stress-associated hypertension in the work place: results of the STARLET project]. / Stressassoziierte Hypertonie am Arbeitsplatz--Ergebnisse des STARLET-Projekts.

BACKGROUND AND OBJECTIVE: To assess the influence of work stress and initial blood pressure on the prognosis of hypertension. SUBJECTS AND METHODS: In a prospective, controlled, multicentre, observational study, ambulatory 24-hour blood pressure measurements (ABPM) of employees from different work places were recorded at the work place on working days. Recurrent ABPM were performed for up to 5 years on 3448 subjects (mean age 44.6 years) who gave consent for follow-up. Subjects with hypertension were told to consult their family doctor so that they could receive antihypertensive treatment (the angiotensin receptor blocker eprosartan, an ACE-inhibitor or a beta-blocker were recommended for initial treatment). Subjects were classified as being in mental strain (stress-positive [stress+]/ stress-negative [stress-]), using standardized questionnaires. RESULTS: Only 1242 (36.0%) of the 3448 employees (69.% males) were normotensives. Only 166 (7.5%) of the 2206 hypertensives had normal ABPMs (<135/85 mmHg) and received antihypertensive treatment at the time of inclusion into the trial. During follow-up 57.8% of patients were treated with eprosartan or ACE-inhibitors, 34.6% with beta-blockers. By the time of the final visit 80.5% of hypertensives had achieved improvement of systolic and/or diastolic blood pressures (29.1% normotensive). Patients with hypertensive ABPM at baseline had more cardiovascular events than normotensives (normotensives 3.0%; grade 1 7.8%, grade 2-3 9.8%). Hypertensive ABPMs at the last follow up or an increase in blood pressure grade were associated with higher event rates than normotensives (stable normotensives 1.8% events vs. stable hypertensives 7.9%, vs. worsening or grade 2-3: 9.1%) More hypertensives were classified as stress+ than normotensives. Persons classified as stress- (or changing to stress-) had fewer events (6.2%) than those regarded as stress+ or changing to stress+ (7.1%). Persons regarded as stable stress- had lower mean blood pressures than those who were stable stress+. Change to another stress group was associated with an increase or decrease of mean blood pressure. CONCLUSIONS: Many employed people are hypertensive at work and are not treated adequately. ABPM control and antihypertensive treatment based on eprosartan, ACE-inhibitors or beta-blockers resulted in a significant increase in the number of patients with lower blood-pressure levels and a reduction in cardiovascular events. Patients under mental strain were more likely to be hypertensive. Mental strain was associated with changes in blood pressure.

Family representations in relationship episodes of patients with a diagnosis of bulimia nervosa.

The influence of the family on the development and the maintenance of bulimia nervosa can be seen both biologically and psychosocially. Genetic influences are discussed, but their effects do not explain the aetiology exclusively. Clinical observations and research findings support the role of family dynamics, family environment, and family functioning. In particular, a low level of cohesion, a lower degree of expressiveness, and more conflicts seem to characterize the family of patients with a diagnosis of bulimia nervosa. The present study addresses the question of how patients suffering from bulimia differ from other patients in psychotherapy and from non-clinical control subjects in the way they perceive their ongoing and their past family relationships. The Core Conflictual Relationship Theme method is applied to narrative material from patients belonging to these three groups. Results show expected differences between patients and normal control subjects and virtually no differences between the group of patients with a diagnosis of bulimia nervosa and the group of patients with diagnoses different from bulimia.

Outcome analysis of 189 consecutive cancer patients referred to the intensive care unit as emergencies during a 2-year period.

The referral of critically ill cancer patients to an intensive care unit (ICU) is a matter of controversial debate. This study was conducted by an interdisciplinary clinical group to evaluate the outcome of ICU treatment in cancer patients according to their characteristics at the time of referral. A retrospective analysis was used to identify relevant subgroups among 189 consecutive cancer patients referred as emergencies to one of four ICUs during a 2-year period. Reasons for ICU referral were pneumonia (29.6%), sepsis (27.0%), fungal infection (11.1%), another infection (9.5%), gastrointestinal emergency (16.9%), treatment-related organ toxicity (6.9%), or other, non-infectious complications (43.9%). Vasopressor support was required in 50.3%, mechanical ventilation in 49.7%, and haemodialysis/-filtration in 26.5% of the patients. Overall, 41.3% died during ICU treatment, 12.2% died after transfer from ICU to a non-ICU ward, and 35.4% were discharged alive. Sepsis, mechanical ventilation, vasopressor support, renal replacement therapy and neutropenia were independent risk factors for fatal outcome, but no single risk factor unequivocally predicted death. All patients with fungal infection who required vasopressor support and either had sepsis (n=13) or needed mechanical ventilation (n=14) died during ICU treatment, while all non-septic patients. who did not require mechanical ventilation, were younger than 74 years of age and had a non-infectious underlying complication (n=29), survived. This analysis may help to early identify relevant subgroups of cancer patients with different prognoses under ICU treatment. A prospective study to confirm the predictive usefulness of this approach is needed. Cancer patients should not be excluded from referral to the intensive care unit in an emergency solely due to their underlying malignant disease or a single unfavourable prognostic factor.

Influence of postoperative complementary treatment with lectin-standardized mistletoe extract on breast cancer patients. A controlled epidemiological multicentric retrolective cohort study.

This epidemiological study was performed to evaluate the influence of postoperative complementary treatment with lectin-standardized mistletoe extract (sME) on breast cancer patients. The design (retrolective cohort analysis with parallel groups) and conduct of the study were in agreement with current standards for prospectively randomized clinical trials. A cohort of 1,248 breast cancer patients on postoperative chemo-, radio-, hormone-therapy were studied in 27 randomized centers. Patients with complementary medications other than sME were excluded from the evaluation and the final analysis was performed on data of 689 patients. From this cohort 219 patients received a complementary treatment exclusively with sME (therapy group), while 470 patients were without complementary treatment (control group). The median follow-up time was 284 days (therapy group) and 285 days (control group). The primary end-point of the study was to determine the impact of complementary sME treatment on disease- or therapy-induced adverse reactions in breast cancer patients. Imbalances for causal effects (covariates) were adjusted by propensity scores. Final evaluation was performed by estimating the linear regression between change in symptom score and propensity score with all data and using the regression line to calculate the change in symptom score expected for each patient. Tumor-associated events were evaluated by number and time until event. The safety of sME treatment was analysed in terms of number, severity, duration and outcome of adverse reactions. As compared to breast cancer patients without complementary treatment (control group), the administration of sME (therapy group) resulted in a significant reduction of adverse reactions induced by the tumor-destructive therapies (e.g. nausea, gastro-intestinal tract symptoms, depression, fatigue, mental symptoms) and prolonged relapse-free intervals, most pronounced for UICC stages IIa and IIb. The rate of sME-associated adverse reactions was 12.8%. All side-effects were mild to moderate, predominantly local skin reactions and self-limiting without therapeutic intervention. Complementary treatment of breast cancer patients with lectin-standardized mistletoe extract (sME) proved to be a well tolerated optimization of standard tumor-destructive therapies, mainly improving quality of life and relapse-free intervals in defined UICC stages.

Infectious complications after high-dose chemotherapy and autologous stem cell transplantation: comparison between patients with lymphoma or multiple myeloma and patients with solid tumors.

From November 1994 to May 1998, 117 patients (66 with solid tumor, 36 with lymphoma, 14 with multiple myeloma, one with acute leukemia) underwent 178 cycles of high-dose chemotherapy and autologous stem cell transplantation (ASCT) at our institution. We retrospectively analyzed the infectious complications that occurred after ASCT. Median duration of neutropenia (granulocyte count <0.5 x 10(9)/l ) was 8 days, the overall incidence of fever requiring antimicrobial treatment was 63%. 35.4% of patients had fever of unknown orign (FUO), whereas primary bacteremia occurred in 21.3%, pneumonia in 3.4% and severe skin infection in 1.1% of patients. Invasive fungal infections occurred in three, and enterocolitis in one patient. Infection was fatal in three patients (2.6%), in each case due to septic shock. The most frequently isolated pathogens were Gram-positive cocci. Median time to defervescence with antimicrobial therapy was 4 days (6 days in patients with bacteremia or other severe infection, and 3 days in patients with FUO). First-line antimicrobial therapy was successful in 65% of patients with FUO and 30.6% of patients with documented infections. With respect to the incidence, type and clinical course of infection, no significant differences between patients with lymphoma or multiple myeloma and those with solid tumors were detected.

Four patients with AL amyloidosis treated with high-dose chemotherapy and autologous stem cell transplantation.

Four patients with AL amyloidosis underwent high-dose chemotherapy and autologous stem cell transplantation at our institutions. Here, we report the clinical courses and outcomes in these patients. Two patients with multi-organ amyloid deposits including cardiac involvement died within 12 days after high-dose chemotherapy. However, in the other two patients, one of whom was suffering from amyloid-related cardiac failure, a significant improvement of organ function was achieved.

Granulocyte/macrophage-colony-stimulating-factor plus interleukin-2 plus interferon alpha in the treatment of metastatic renal cell carcinoma: a pilot study.

Granulocyte/macrophage-colony-stimulating factor (GM-CSF) plays a central role in the differentiation and function of dendritic cells, which are crucial for the elicitation of MHC-restricted T cell responses. Preclinical and the first clinical data provide a rationale for the application of GM-CSF in immunotherapy of cancer. Ten patients with renal cell carcinoma stage IV (Holland/ Robson) were treated in this pilot study. Therapy was started with GM-CSF alone (2 weeks). Interleukin (IL-2) and interferon alpha (IFNalpha) were added sequentially (3 weeks GM-CSF plus IL-2 or IFNalpha, 3 weeks GM-CSF plus IL-2 plus IFNalpha). Therapy was performed on an outpatient basis. The cytokine regimen was evaluated for toxicity, clinical response and immunomodulatory effects [fluorescence-activated cell sorting analysis of peripheral blood mononuclear cells (PBMC), mixed-lymphocyte reaction and cytotoxicity of PBMC]. GM-CSF treatment caused a significant increase in the number of PBMC expressing costimulatory molecules. Addition of IL-2 and IFNalpha led to an increase in CD3 , CD4+, CD8+ and CD56+ PBMC in week 9. In an autologous mixed-lymphocyte reaction a 2.1-fold increase in T cell proliferation was observed after 2 weeks of GM-CSF treatment, and cytotoxicity assays showed changes in natural-killer-(NK)- and non-NK-mediated cytotoxicity in some patients. Two patients achieved partial remission, one patient had a mixed response. The toxicity of the regimen was mild to moderate with fever, flu-like symptoms and nausea being observed in most patients. Severe organ toxicity was not observed. We conclude that GM-CSF might be useful for immunotherapy of renal cell carcinoma, especially in combination with T-cell-active cytokines. Further studies are warranted.

[Interpersonal relation pattern in families with a bulimic member- interaction analysis]. / Interpersonale Beziehungsmuster in Familien mit einem bulimischen Mitglied--eine Interaktionsanalyse.

Basic hypotheses concerning the interaction in families of bulimic patients are tested. Family therapy sessions of 20 female patients of an outpatient therapy unit for eating-disorders were coded with a micro-analytic instrument (Göttinger Familieninteraktions-Skalen) and analysed. The siblings relationships were systematically included in the study. The parental dyad turned out to be significantly more conflictual than the other dyads were. In the relationship between the patient and the parents a relatively stable pattern of interactional behaviour was found. The relationship between mother and bulimic daughter was more conflictual than that between father and daughter. The father-sibling-dyad was not significantly more conflictual than the father-patient-dyad. Especially the impact of sibling relationships on the family interaction of bulimic patients needs further elucidation.

The spirit of healing. Treating the whole patient.

Whether providing solace to a grieving family, giving council to a frightened cancer patient, or administering spiritual healing advice to nursing staff, the clergy who roam hospital halls are highly skilled and educated professionals who provide a very real service to patients.

Calcium regulation of cyclic nucleotide signaling in lobster olfactory receptor neurons.

An elevated free Ca2+ concentration reduces odor-stimulated production of cyclic AMP (cAMP) in the outer dendritic membranes of lobster olfactory receptor neurons in vitro. This effect can occur within 50 ms of odor stimulation. The effect is concentration-dependent at submicromolar concentrations of free Ca2+. An elevated free Ca2+ concentration also reduces basal and forskolin-stimulated cAMP levels in a concentration-dependent manner, suggesting that Ca2+ is not targeting the activation of the odor receptor/G protein complex. The degradation of synthetic cAMP by phosphodiesterases is not enhanced by an increased free Ca2+ concentration, suggesting that Ca2+ acts by down-regulating the olfactory adenylyl cyclase. Western blot analysis of the lobster olfactory sensilla that contain the outer dendrites reveals a protein in the transduction zone with a molecular mass of approximately 138 kDa that is immunoreactive to an antiserum against adenylyl cyclase type III. Given earlier evidence that Ca2+ potentially enters the receptor cell through odor-activated inositol 1,4,5-trisphosphate-gated channels, our results suggest a possible route for cross talk between the cyclic nucleotide and the inositol phospholipid signaling pathways in lobster olfactory receptor neurons.

Determination of Cu, Fe, Mn, and Zn in blood fractions by SEC-HPLC-ICP-AES coupling.

The binding of Cu, Fe, Mn, and Zn to proteins in blood and in blood fractions was investigated, since their interactions in free radical metabolism in humans is of great interest. An HPLC-ICP-AES technique was developed allowing adequate separation of metalloproteins and of inorganic and organic metal species. For the separation of metalloproteins in erythrocytes and blood plasma a Merck Superformance Fractogel EMD BioSEC 650 (S) column was used. Size exclusion chromatography (SEC)-HPLC was hyphenated to ICP-AES both on-line and off-line for the detection of trace elements in the fractions resulting from HPLC separations. HPLC parameters, pH, temperature, flow rate and salt concentration were optimized for the protein separation and the optimal conditions were applied for the hyphenation to the ICP-AES detector. The separation column was calibrated with five standard proteins. For the element determination by ICP-AES a line selection with respect to the sensitivity was performed. Three different methods were used for the determination of trace elements in blood: direct determinations, on-line and off-line SEC-HPLC-ICP-AES measurements. For the optimizing experiments blood samples of one female subject were used. The direct determination by ICP-AES of the elements was performed in blood and blood fractions of ten different subjects to obtain the average concentration ranges. From the results the identification of the protein Cu/Zn superoxide dismutase in erythrocytes was possible. The LOD were 0.03 microgram mL-1 for Cu, 0.026 microgram mL-1 for Fe, 0.8 ng mL-1 for Mn, and 0.09 microgram mL-1 for Zn in a synthetic blood matrix.

Ultrasound-induced degradation of PLA and PLGA during microsphere processing: influence of formulation variables.

The effect of probe sonication during microsphere processing on the stability of various aliphatic polyesters based on lactic acid (PLA) and lactic/glycolic acid (PLGA) was investigated. The weight average molecular weight (Mw) of the polymers dissolved in dichloromethane (DCM) generally decreased with an increase in duration and/or intensity of the sonication process. The extent of the Mw-reduction was more pronounced with polymers of high initial Mw and high GA content. Polydispersity indices (PD=Mw/Mn) were nearly unchanged indicating that random chain cleavage is the likely degradation mechanism. From the observation that ultrasound-induced polymer degradation slightly increased in the presence of suspended drug particles acting as cavitation nuclei, it can be concluded that the mechanical stress induced by the implosive collapse of cavitation bubbles is at least partly responsible for the observed effects in PLA/ PLGA solutions. The use of ultrasound for the preparation of W/O, O/W and W/O/W emulsions exhibited different effects depending on the formulation and the type of emulsion. The preparation of W/O emulsions generally lead to Mw-changes comparable to those observed for the corresponding polymer solutions. Fatty acid free bovine serum albumin (BSAff) was found to protect PLA and PLGA against ultrasound-induced degradation in W/O-emulsions due to the formation of a semisolid interfacial film. A tremendous effect not only on the polymer Mw, but also on its PD could be observed, when ultrasound was used to emulsify an organic polymer solution or W/O-emulsion in an external aqueous phase. As this last finding was found to have rather important implications on the drug loading efficiency, the hydration, the degradation and the initial release characteristics of the resulting microspheres, it can be concluded that probe sonication can be a rather critical process step during the preparation of microspheres.

Oocyte sensitivity to serotonergic regulation during the follicular cycle of the teleost Fundulus heteroclitus.

In the teleost Fundulus heteroclitus, serotonin (5-HT) reversibly inhibits oocyte maturation induced in vitro by the maturation-inducing steroid (MIS) 17,20beta-dihydroxy-4-pregnen-3-one (17,20betaP). The 5-HT inhibition of 17,20betaP-induced meiotic maturation was examined in ovarian follicles at different developmental stages or isolated at different times during the follicular cycle. Steroid treatment of late vitellogenic and early maturing follicles (1.2- to 1.7-mm diameter) promoted oocyte maturation in a size-dependent manner, and this maturation was inhibited by 5-HT in follicles of < 1.6- to 1.7-mm diameter. Thus, the 5-HT inhibition progressively decreased as follicles developed the ability to mature in the absence of 17,20betaP. The effectiveness of 5-HT to increase follicular cAMP remained similar within the same developmental stages, indicating that the reduction of 5-HT inhibitory action was not related to the competence of 5-HT to activate inhibitory signals in the oocyte. During the follicular cycle, fully grown follicles (1.3- to 1.4-mm diameter) showed a decreased maturational competence in response to gonadotropin or MIS stimulation after the follicular recruitment into maturation and spawning occurred, which coincided with an increase of the effectiveness of 5-HT at inhibiting 17,20betaP-induced maturation. In further experiments, preincubation of follicles with hCG was found to reduce 5-HT inhibitory action, but when follicles were incubated with either hCG in the presence of a steroidogenesis inhibitor or estradiol-17beta (E2), the 5-HT inhibition was unaffected. These findings suggest that 5-HT inhibition of the MIS-induced meiotic maturation is not under direct gonadotropin or E2 regulation but that it might be regulated in vivo by changes in the competence of the oocytes to undergo oocyte maturation after MIS stimulation.

Serotonin inhibition of steroid-induced meiotic maturation in the teleost Fundulus heteroclitus: role of cyclic AMP and protein kinases.

The transduction of the serotonin (5-HT) signal in Fundulus heteroclitus ovarian follicles leading to the inhibition of oocyte meiosis reinitiation (oocyte maturation) in vitro induced by the naturally occurring maturation-inducing steroid 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17,20 beta P) was investigated. Steroid-induced oocyte maturation was inhibited by 5-HT in a dose-dependent manner; maximum inhibition (90%) was observed with 10(-4) M 5-HT. Groups of follicle-enclosed oocytes were cultured in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) and treated with increasing doses of 5-HT. Serotonin was found to slightly increase the levels of follicular 3',5'-cyclic adenosine monophosphate (cAMP) in a dose-dependent manner; 10(-4) M 5-HT induced approximately a 3-fold increase in cAMP with respect to the controls. The changes in cAMP were then evaluated in follicles treated with 17,20 beta P in IBMX-free culture media in the presence or absence of 10(-4) M 5-HT. The exposure of follicles to 17,20 beta P alone produced a small and transient reduction in cAMP (40%) within 1-3 hr of steroid stimulation, and these early changes in cAMP appeared associated with a high incidence of germinal vesicle breakdown (80% GVBD) by 24 hr of incubation. Under these conditions, treatment of follicles with 5-HT also increased significantly the production of cAMP, and when 5-HT was combined with 17,20 beta P, the steroid-mediated reduction in cAMP was prevented and the levels of GVBD inhibited by 95%. Meiosis also was reinitiated with either the protein kinase A (PKA) inhibitor H8 or the protein kinase C (PKC) activator PMA, and the 5-HT inhibitory action on GVBD was found to be 100-fold reduced or completely ineffective, respectively. Preincubation of follicles with the PKC inhibitor GF109203x abolished PMA-induced GVBD in a dose-dependent manner, whereas this inhibitor had no effect on 17,20 beta P-triggered meiotic maturation, indicating that activation of PKC is apparently sufficient but not necessary to reinitiate meiosis. Taken together, these findings suggest that 5-HT may inhibit 17,20 beta P-induced meiotic reinitiation through the activation of a cAMP-PKA transduction pathway and that PKC possibly induces oocyte maturation by a different pathway than the steroid and thus is not affected by 5-HT.

Protein phosphorylation in snail cardiocytes stimulated with molluscan peptide SCPb.

Dissociated muscle cells prepared from hearts of the pulmonate snail Helix aspersa were used to study signal transduction induced by molluscan cardioactive peptides. The effects of SCPb on the cAMP levels of whole hearts and the cell preparation were compared. The cells responded to SCPb with a dose-dependent increase in cAMP that had the same structure-activity relations as seen in the intact tissue. SCPb increased the phosphorylation of a 53 kDa protein in a dose dependent manner; threshold was 10(-9) M. The SCPb-induced phosphorylation was mimicked by forskolin and 8-CPT-cAMP. FMRFamide stimulation had no effect on the phosphorylation of this protein.