Cognitive performance in aged rats is associated with differences in distinctive neuronal populations in the ventral tegmental area and altered synaptic plasticity in the hippocampus.

Introduction: Deterioration of cognitive functions is commonly associated with aging, although there is wide variation in the onset and manifestation. Albeit heterogeneity in age-related cognitive decline has been studied at the cellular and molecular level, there is poor evidence for electrophysiological correlates. The aim of the current study was to address the electrophysiological basis of heterogeneity of cognitive functions in cognitively Inferior and Superior old (19-20 months) rats in the ventral tegmental area (VTA) and the hippocampus, having Young (12 weeks) rats as a control. The midbrain VTA operates as a hub amidst affective and cognitive facets, processing sensory inputs related to motivated behaviours and hippocampal memory. Increasing evidence shows direct dopaminergic and non-dopaminergic input from the VTA to the hippocampus. Methods: Aged Superior and Inferior male rats were selected from a cohort of 88 animals based on their performance in a spatial learning and memory task. Using in vivo single-cell recording in the VTA, we examined the electrical activity of different neuronal populations (putative dopaminergic, glutamatergic and GABAergic neurons). In the same animals, basal synaptic transmission and synaptic plasticity were examined in hippocampal slices. Results: Electrophysiological recordings from the VTA and hippocampus showed alterations associated with aging per se, together with differences specifically linked to the cognitive status of aged animals. In particular, the bursting activity of dopamine neurons was lower, while the firing frequency of glutamatergic neurons was higher in VTA of Inferior old rats. The response to high-frequency stimulation in hippocampal slices also discriminated between Superior and Inferior aged animals. Discussion: This study provides new insight into electrophysiological information underlying compromised cerebral ageing. Further understanding of brain senescence, possibly related to neurocognitive decline, will help develop new strategies towards the preservation of a high quality of life.

Generation and Characterization of a Human Neuronal In Vitro Model for Rett Syndrome Using a Direct Reprogramming Method.

Rett Syndrome (RTT) is a severe neurodevelopmental disorder, afflicting 1 in 10,000 female births. It is caused by mutations in the X-linked methyl-CpG-binding protein gene (MECP2), which encodes for the global transcriptional regulator methyl CpG binding protein 2 (MeCP2). As human brain samples of RTT patients are scarce and cannot be used for downstream studies, there is a pressing need for in vitro modeling of pathological neuronal changes. In this study, we use a direct reprogramming method for the generation of neuronal cells from MeCP2-deficient and wild-type human dermal fibroblasts using two episomal plasmids encoding the transcription factors SOX2 and PAX6. We demonstrated that the obtained neurons exhibit a typical neuronal morphology and express the appropriate marker proteins. RNA-sequencing confirmed neuronal identity of the obtained MeCP2-deficient and wild-type neurons. Furthermore, these MeCP2-deficient neurons reflect the pathophysiology of RTT in vitro, with diminished dendritic arborization and hyperacetylation of histone H3 and H4. Treatment with MeCP2, tethered to the cell penetrating peptide TAT, ameliorated hyperacetylation of H4K16 in MeCP2-deficient neurons, which strengthens the RTT relevance of this cell model. We generated a neuronal model based on direct reprogramming derived from patient fibroblasts, providing a powerful tool to study disease mechanisms and investigating novel treatment options for RTT.

Enhancement of Radiation Sensitivity by Cathepsin L Suppression in Colon Carcinoma Cells.

Cancer is one of the main causes of death globally. Radiotherapy/Radiation therapy (RT) is one of the most common and effective cancer treatments. RT utilizes high-energy radiation to damage the DNA of cancer cells, leading to their death or impairing their proliferation. However, radiation resistance remains a significant challenge in cancer treatment, limiting its efficacy. Emerging evidence suggests that cathepsin L (cath L) contributes to radiation resistance through multiple mechanisms. In this study, we investigated the role of cath L, a member of the cysteine cathepsins (caths) in radiation sensitivity, and the potential reduction in radiation resistance by using the specific cath L inhibitor (Z-FY(tBu)DMK) or by knocking out cath L with CRISPR/Cas9 in colon carcinoma cells (caco-2). Cells were treated with different doses of radiation (2, 4, 6, 8, and 10), dose rate 3 Gy/min. In addition, the study conducted protein expression analysis by western blot and immunofluorescence assay, cytotoxicity MTT, and apoptosis assays. The results demonstrated that cath L was upregulated in response to radiation treatment, compared to non-irradiated cells. In addition, inhibiting or knocking out cath L led to increased radiosensitivity in contrast to the negative control group. This may indicate a reduced ability of cancer cells to recover from radiation-induced DNA damage, resulting in enhanced cell death. These findings highlight the possibility of targeting cath L as a therapeutic strategy to enhance the effectiveness of RT. Further studies are needed to elucidate the underlying molecular mechanisms and to assess the translational implications of cath L knockout in clinical settings. Ultimately, these findings may contribute to the development of novel treatment approaches for improving outcomes of RT in cancer patients.

Proteolytic Activation of the Epithelial Sodium Channel (ENaC): Its Mechanisms and Implications.

Epithelial sodium channel (ENaC) are integral to maintaining salt and water homeostasis in various biological tissues, including the kidney, lung, and colon. They enable the selective reabsorption of sodium ions, which is a process critical for controlling blood pressure, electrolyte balance, and overall fluid volume. ENaC activity is finely controlled through proteolytic activation, a process wherein specific enzymes, or proteases, cleave ENaC subunits, resulting in channel activation and increased sodium reabsorption. This regulatory mechanism plays a pivotal role in adapting sodium transport to different physiological conditions. In this review article, we provide an in-depth exploration of the role of proteolytic activation in regulating ENaC activity. We elucidate the involvement of various proteases, including furin-like convertases, cysteine, and serine proteases, and detail the precise cleavage sites and regulatory mechanisms underlying ENaC activation by these proteases. We also discuss the physiological implications of proteolytic ENaC activation, focusing on its involvement in blood pressure regulation, pulmonary function, and intestinal sodium absorption. Understanding the mechanisms and consequences of ENaC proteolytic activation provides valuable insights into the pathophysiology of various diseases, including hypertension, pulmonary disorders, and various gastrointestinal conditions. Moreover, we discuss the potential therapeutic avenues that emerge from understanding these mechanisms, offering new possibilities for managing diseases associated with ENaC dysfunction. In summary, this review provides a comprehensive discussion of the intricate interplay between proteases and ENaC, emphasizing the significance of proteolytic activation in maintaining sodium and fluid balance in both health and disease.

Dose-dependent anti-hyperglycemic & anti-dyslipidemic potential of aqueous leaves extract of Typha elephantina in-vivo and in-vitro.

Diabetes mellitus is among the fundamental causes of illness and millions of deaths around the globe are directly attributed to it each year. Current antidiabetic medications often lack sustained glycemic control and carry significant risks of side effects. As a result, the use of plant-based treatments has gained popularity. In this experimental study, we evaluated the aqueous extracts (LQE) of Typha elephantina (also known as Elephant grass) leaves collected from freshwater marshes, for their potential anti-hyperglycemic and anti-hyperlipidemic antioxidant effects in healthy streptozotocin caused diabetic-mice. We employed glucose adsorption tests at different glucose levels and glucose diffusion tests to assess the in-vitro antidiabetic action of plant extract. For the in-vivo trail, we measured fasting blood glucose (FBG), glucose tolerance (GTT), as well as long-term anti-diabetic, anti-hyperlipidemic, and antioxidant activities. Our results from the glucose diffusion test indicated that the extract was highly effective at both low glucose concentrations (5 mmol L) and high glucose concentrations (100 mmol L). However, the glucose-diffusion ability reached its peaked at an excessively high dosage of the aqueous extract, suggesting a dose-related effect. Similarly, we observed that high doses of TEL.AQ extracts (400 mg/kg body weight) significantly reduced blood glucose levels in healthy mice during the glucose tolerance test (GTT) at 3 h and fasting blood glucose studies (FBG) at 6 h. Furthermore, the high-dose TEL.AQ extract effectively reduced liver-related serum markers and blood-glucose concentration (BGC) in severely chronic diabetic rats. The extract dosage also influenced lipid profile, conjugate and unconjugated bilirubin levels, cholesterol, triglycerides, HDL, and total bilirubin levels. Additionally, after administering a high extract dose, we observed considerable improvement in the liver homogenate markers CAT, POD, and SOD. In contrast, the extract at a low dosage (100 mg/kg), showed minimal, while a moderate dose (200 mg/kg), yielded promising results.

The Significance of Cathepsin B in Mediating Radiation Resistance in Colon Carcinoma Cell Line (Caco-2).

Cathepsins (Caths) are lysosomal proteases that participate in various physiological and pathological processes. Accumulating evidence suggests that caths play a multifaceted role in cancer progression and radiotherapy resistance responses. Their proteolytic activity influences the tumor's response to radiation by affecting oxygenation, nutrient availability, and immune cell infiltration within the tumor microenvironment. Cathepsin-mediated DNA repair mechanisms can promote radioresistance in cancer cells, limiting the efficacy of radiotherapy. Additionally, caths have been associated with the activation of prosurvival signaling pathways, such as PI3K/Akt and NF-κB, which can confer resistance to radiation-induced cell death. However, the effectiveness of radiotherapy can be limited by intrinsic or acquired resistance mechanisms in cancer cells. In this study, the regulation and expression of cathepsin B (cath B) in the colon carcinoma cell line (caco-2) before and after exposure to radiation were investigated. Cells were exposed to escalating ionizing radiation doses (2 Gy, 4 Gy, 6 Gy, 8 Gy, and 10 Gy). Analysis of protein expression, in vitro labeling using activity-based probes DCG04, and cath B pull-down revealed a radiation-induced up-regulation of cathepsin B in a dose-independent manner. Proteolytic inhibition of cathepsin B by cathepsin B specific inhibitor CA074 has increased the cytotoxic effect and cell death due to ionizing irradiation treatment in caco-2 cells. Similar results were also obtained after cathepsin B knockout by CRISPR CAS9. Furthermore, upon exposure to radiation treatment, the inhibition of cath B led to a significant upregulation in the expression of the proapoptotic protein BAX, while it induced a significant reduction in the expression of the antiapoptotic protein BCL-2. These results showed that cathepsin B could contribute to ionizing radiation resistance, and the abolishment of cathepsin B, either by inhibition of its proteolytic activity or expression, has increased the caco-2 cells susceptibility to ionizing irradiation.

A pan-cancer analysis of HAVCR1 with a focus on diagnostic, prognostic and immunological roles in human cancers.

OBJECTIVES: Cancer is one of the most prominent causes of death world wide. Identification of novel cancer biomarkers woud help with cancer diagnosis and possible treatment. METHODS: In this study, we comprehensively studied the diagnostic, prognostic, and therapeutic values of the hepatitis A virus cellular receptor 1 (HAVCR1) gene across multiple cancers from a pan-cancer point of view via a detailed in silico approach. RESULTS: HAVCR1 expression was up-regulated in a variety of malignancies. The up-regulated HAVCR1 was closely related to the poor prognosis in patients with esophageal carcinoma (ESCA), lung adenocarcinoma (LUAD), and stomach adenocarcinoma (STAD). Moreover, DAVID analysis showed that HAVCR1, along with different other associated genes, was involved in numerous cancer-associated signaling pathways across ESCA, STAD, and LUAD. Furthermore, in these cancers, HAVCR1 was also found closely associated with some other parameters such as promoter methylation, tumor purity, level of CD8+ T immune cells, genomic alterations, and chemotherapeutic drugs. CONCLUSION: HAVCR1 was overexpressed in multiple tumors. However, the up-regulated HAVCR1 is a valuable diagnostic and prognostic biomarker as well as a therapeutic target in only ESCA, STAD, and LUAD patients.

Characterizing the oncogenic importance and exploring gene-immune cells correlation of ACTB in human cancers.

After cardiovascular diseases, cancer is the second deadliest malignancy in the world. The current study was launched to investigate the diagnostic and prognostic landscape of Beta-actin (ACTB) via a multi-layered bioinformatics approach. ACTB expression was analyzed and validated via UALCAN, TIMER, GENT2, GEPIA, and HPA. ACTB promoter methylation was evaluated via MREXPRES. Furthermore, ACTB prognostic values and their correlation with cancer metastasis were explored through the KM plotter and TNMplot, respectively. Then, cBioPortal, CancerSEA, Enrichr, TIMER, MuTarget, and CDT were used to analyze ACTB-related genetic alterations, transcription factors (TFS), MicroRNAs (miRNAs), chemotherapeutic drugs, and the correlation between its expression, immune cells, and different other parameters. We found that ACTB expression was remarkably higher in 24 major human cancer tissues than the normal samples. Additionally, elevated ACTB expression was associated with poorer survival and metastasis in only liver hepatocellular carcinoma (LIHC), head and neck squamous cancer (HNSC), and lung adenocarcinoma (LUAD). This implies that ACTB plays a significant role in the development and progression of LIHC, HNSC, and LUAD. Furthermore, enrichment analysis showed that ACTB-associated genes regulate different Biological Processes (BP), Molecular Functions (MF), and Kyoto Encyclopedia of Genes and Genomes (KEGG) terms. Moreover, ACTB up-regulation had interesting correlations with immune infiltration of CD4+ T, and CD8+ T, tumor purity, mutant genes, and a few other important parameters. At last, via this study, we also explored ACTB-associated clinically important expression regulators, including TFS, miRNAs, and different chemotherapeutic drugs. The results of the present study suggested that ACTB might be a potential candidate biomarker in LIHC, HNSC, and LUAD.

Impact of Enniatin B and Beauvericin on Lysosomal Cathepsin B Secretion and Apoptosis Induction.

Enniatin B (ENN B) and Beauvericin (BEA) are cyclohexadepsipeptides that can be isolated from Fusarium and Beauveria bassiana, respectively. Both compounds are cytotoxic and ionophoric. In the present study, the mechanism of cell death induced by these compounds was investigated. Epidermal carcinoma-derived cell line KB-3-1 cells were treated with different concentrations of these compounds. The extracellular secretion of cathepsin B increased in a concentration-dependent manner, and the lysosomal staining by lysotracker red was reduced upon the treatment with any of the compounds. However, the extracellular secretion of cathepsin L and cathepsin D were not affected. Inhibition of cathepsin B with specific inhibitor CA074 significantly reduced the cytotoxic effect of both compounds, while inhibition of cathepsin D or cathepsin L did not influence the cytotoxic activities of both compounds. In vitro labelling of lysosomal cysteine cathepsins with Ethyl (2S, 3S)-epoxysuccinate-Leu-Tyr-Acp-Lys (Biotin)-NH2 (DCG04) was not affected in case of cathepsin L upon the treatment with both compounds, while it was significantly reduced in case of cathepsin B. In conclusion, ENN B and BEA increase lysosomal Ph, which inhibits delivery of cathepsin B from Golgi to lysosomes, thereby inducing cathepsin B release in cytosol, which activates caspases and hence the apoptotic pathway.

Novel insight on chemo-specific detection of toxic environmental chromium residues existing as recalcitrant Cr(III)-carboxyl complexes using plasmonic silver nanoplatform bi-functionalized with citrate and PVP.

Chromium (Cr) is a toxic environmental pollutant that majorly exists in trivalent and hexavalent forms. Though Cr(VI) is more dangerous than Cr(III), the trivalent Cr forms complexes with environmentally-available organic molecules. This makes them potentially harmful and difficult to detect. In this study, we have designed an ultrasensitive plasmonic nanosensor using citrate and PVP functionalized Ag nanoparticles (Ag-citrate-PVPNPs) for the detection of trivalent chromium organic complexes such as Cr(III)-EDTA (Cr-E), Cr(III)-acetate (Cr-A), Cr(III)-citrate (Cr-C) and Cr(III)-tartrate (Cr-T). The nanoparticles (NPs) were structurally characterized by XRD, SEM, HRTEM, SAED, EDX and elemental mapping. The citrate and PVP molecules played a vital role in the detection mechanism and stability of the sensor. Upon detection, the yellow-colored Ag-citrate-PVP NPs turned into different shades of brown depending on the type of the Cr complex and concentration. It was accompanied by diminishing and/or shifting UV-Visible absorbance peaks due to the aggregation of Ag-citrate-PVP NPs. Further, a linear relationship was observed between absorbance reduction and analyte concentration. The selectivity tests showed that the sensor was non-functional to other metal ions and inorganic anions. The sensor was optimized using pH and temperature studies. The mechanism of detection was elucidated with the help of characterization techniques such as Raman spectroscopy, FTIR, XPS and UV-visible spectrophotometer. The limit of detection (LOD) was found to be 3.29, 4.87, 1.76 and 1.79 nM for Cr-E, Cr-A, Cr-C and Cr-T complexes respectively. This study provides a rapid and sensitive approach for the detection of multiple Cr(III)-organic complexes present in an aqueous solution.

Decoding signal transducer and activator of transcription 1 across various cancers through data mining and integrative analysis.

OBJECTIVES: Using different online available databases and Bioinformatics tools, we extensively studied the role STAT1 across different cancers. METHODS: STAT1 mRNA, protein expression, and promoter methylation were analyzed and validated using UALCAN, GENT2, Human Protein Atlas (HPA), and MEXPRESS. Furthermore, the potential prognostic values were evaluated through KM plotter. Then, cBioPortal was utilized to examine the STAT1-related genetic mutations, while pathway enrichment analysis was performed using DAVID. To identify STAT1 targeted microRNAs (miRNAs) and transcription factors (TFs) we used Enricher. Moreover, a correlational analysis between STAT1 expression tumor purity and CD8+ T immune cells and a gene-drug interaction network analysis was performed using TIMER, CTD, and Cytoscape. RESULTS: In 23 major human cancers, STAT1 expression was notably up-regulated relative to corresponding controls. As well, the elevated expression of STAT1 was exclusively found to be associated with the reduced overall survival (OS) of Esophageal Carcinoma (ESCA), Kidney Renal Clear Cell Carcinoma (KIRC), and Lung adenocarcinoma (LUAD) patients. This implies that STAT1 plays a significant role in the development and progression of these three cancers. Further pathway analysis indicated that STAT1 enriched genes were involved in six critical pathways, while a few interesting correlations were also documented between STAT1 expression and promoter methylation level, tumor purity, CD8+ T immune cells infiltration, and genetic alteration. In addition, we have also predicted a few miRNAs, TFs, and chemotherapeutic drugs that could regulate the STAT1 expression. CONCLUSION: The current study revealed the shared oncogenic, diagnostic, and prognostic role of STAT1 in ESCA, KIRC, and LUAD.

Green synthesis of two-electron centre based ZnO/NiCo2S4 QDs-OVs using Punica granatum fruit peel extract for an exceptional visible light photocatalytic degradation of doxycycline and ciprofloxacin.

Biosynthesis of nanomaterials using plant extract makes them attractive in the field of photocatalysis as they are environmental friendly. The current study focused on the biosynthesis of ZnO/NiCo2S4 QDs (NCs) using Punica granatum fruit peel extract as the reducing agent. The nanomaterials were characterized with XRD, FTIR, Raman, SEM, TEM, UV-vis DRS, BET, PL, EIS, and ESR analysis and were used for photocatalytic degradation of doxycycline (DOX) and ciprofloxacin (CIP). The bandgap of ZnO is 3.2 eV, and the decoration of NiCo2S4 QDs aids in narrowing the bandgap (2.8 eV), making the NCs visible light active. The fabricated NCs achieved 99 and 89% degradation of DOX and CIP respectively. The photocatalytic efficiency of ZnO/NiCo2S4 QDs was much higher compared to individual ZnO and NiCo2S4 QDs. The half-life period of DOX and CIP were evaluated to be 58 and 152 min respectively. The percentage of TOC removal in the photodegraded product of DOX and CIP was estimated to be 99 and 89% respectively, indicating the mineralization of the compounds. The enhanced photocatalytic efficiency of the NCs was attributed to the narrowed visible light active bandgap, synergistic charge transfer across the interface, and lower charge recombination. The intermediates formed during the photocatalytic degradation of DOX and CIP were analyzed using GC-MS/MS analysis, and the photodegradation pathway was elucidated. Also, the toxicity of the intermediates was computationally analyzed using ECOSAR software. The fabricated ZnO/NiCo2S4 QDs have excellent stability and reusability, confirmed by XRD and XPS analysis. The reusable efficiency of the NCs for the photocatalytic degradation of DOX and CIP were 98.93, and 99.4% respectively. Thus, the biologically fabricated NCs are shown to be an excellent photocatalyst and have wide applications in environmental remediation.

Discovery of small molecules with vasodilating characteristics and adjustable hydrolytic behavior.

In this contribution the development of a new class of vasodilating compounds obtained by lead structure optimization is described. Three groups of compounds were synthesized and tested for their activity on various smooth muscle preparations of the guinea pig. Beside the lead compound 3a, the most interesting derivative was 1H-imidazole-1-carbothioic acid O-cyclohexyl ester hydrochloride (5b) with a good selective vasodilating potential on aorta and pulmonary artery rings (EC50 14 µM and 24 µM, respectively). Due to the properties of small molecules the hydrolysis behavior of the compounds can be easily adapted hence opening a new route in terms of duration of the agent's effect. With the aid of structure-activity relationship studies, structural motifs influencing the biological activity on isolated smooth muscle cell preparations of the synthesized compounds were proposed. The presented compounds offer good tools in identifying promising molecules as emergency therapy in myocardial infarction.

A journey from benzanilides to dithiobenzanilides: Synthesis of selective spasmolytic compounds.

A series of dithiobenzanilide derivatives was synthesized and each compound was evaluated for its ability to reduce KCl-induced contractions of smooth muscle preparations of the guinea pig. Starting from a recent publication describing benzanilide derivatives as antispasmodic agents, structure-activity guided synthesis was performed to obtain compounds with improved spasmolytic activity. First, compounds with two amide bonds were designed and second, both amide oxygens were replaced by two sp² sulfur atoms resulting in dithiobenzanilide derivatives. The most potent antispasmodic dithiobenzanilide 19 showed improved activity with an IC50 value of 0.4 µM. Moreover, the study also demonstrated that these active compounds were able to antagonize the effect of spasmogens like acetylcholine and phenylephrine and that the activity is not mediated by activation of ATP-dependent potassium channels (K(ATP)-channels) or inhibition of endothelial nitric oxide synthase (eNOS).

Benzanilides with spasmolytic activity: chemistry, pharmacology, and SAR.

The following study describes the synthesis of new benzanilide derivatives and their pharmacological investigation on smooth muscle preparations of guinea pigs. All compounds were synthesized in good yields and showed a spasmolytic activity without significant effect on vascular smooth muscles and heart muscle preparations. Moreover, further pharmacological investigations as well as in silico studies were performed to elucidate the mechanism of action. Compound 3 showed the most potent spasmolytic activity with an IC(50) of 3.25microM.

Synthesis and biological activity of thienodiltiazem in isolated heart muscle preparations of guinea pigs.

The new compound thienodiltiazem was synthesized and investigated regarding structure-activity relations and calcium antagonistic properties. Isometric contraction force was measured in guinea-pig papillary muscles and chronotropic activity was studied in right atria of guinea pigs. Compared to the parent drug diltiazem (CAS 42399-41-7) the thieno derivative had a more potent negative chronotropic effect on spontaneously beating right atria and a more potent inotropic effect on papillary muscles. The negative inotropic action was reversed by increasing the extracellular calcium concentration.

Studies on the chemistry of thienoanellated O,N- and S,N-containing heterocycles. Part 30: synthesis and pharmacological properties of thieno[2,3-b][1,4]thiazines with potential vasopressin receptor antagonistic activity.

A series of new nonpeptide vasopressin antagonists with a 6-ethyl-thieno[2,3-b][1,4]thiazine or 6-benzyl-thieno[2,3-b][1,4]thiazine skeleton and structural modifications of the aryl side chain were synthesized in this study. The effects on guinea pig heart and smooth muscle preparations were investigated. In the presence of AVP the compounds showed an antagonistic effect. The compounds did not change spontaneous rate in right atria and exerted a slight but not significant negative inotropic effect in papillary muscles. The relaxing effect on vascular smooth muscle and terminal ileum was far more pronounced. Generally the relaxing effect on terminal ilea was more potent maybe due to difference in V1a receptor density. Our results demonstrate that compounds with an ethyl group in position six on the thienothiazine ring (14, 16, 18 and 22) exerted the most potent relaxing activity in terminal ilea, whereas compounds with a phenyl ring in position six reduced this effect.

Synthesis and pharmacological profile of non-peptide vasopressin antagonists.

Recently we presented a series of 6-ethyl and 6-benzylthieno[2,3-b][1,4]thiazine derivatives with relaxing effects on vascular smooth muscle and terminal ileum. In this report the synthesis of further thieno[2,3-b][1,4]thiazine derivatives and related compounds with a thieno[2,3-b][1,4]thiazepine or thieno[3,2-b][1,4]thiazine ring system is described. The pharmacological effect of the agents was tested in isolated smooth (terminal ileum, pulmonary artery, aortic rings, myometrial strips) and heart (papillary muscle, spontaneously beating right atrium) muscle preparations of the guinea pig. Contractions were measured isometrically, and smooth muscle preparations were either precontracted with high K+ (60 or 90 mM KCl containing nutrient solution) or with agonists, while papillary muscles were electrically stimulated (1 Hz). The vasopressin antagonistic activity of the test compounds was tested in isolated papillary muscles in which the V1A-receptor subtype is located. The biphasic response to vasopressin was antagonized, dependent on the chemical structure of the test compound. Thieno[3,2-b][1,4]thiazines were more potent than thieno[2,3-b][1,4]thiazine and thieno[2,3-b][1,4]thiazepine compounds. In addition, substitution of a methyl substituted terminal benzyl ring instead of a phenyl- or dichlorobenzoyl moiety attenuated the vasopressin antagonistic effect.

Novel screening test to assess the potential environmental toxicity of waste water samples.

Biological effects of waste water samples were investigated using the method for isometric contraction measurements that is widely employed in the medical field for studying the effects of various drugs on heart and smooth muscle preparations. Raw waste water samples from a municipal treatment plant were extracted with chloroform and diluted in dimethylsulfoxide. Some samples were also digested with NaOH or microwave. Our results show that the test is sensitive for the investigation of waste water samples. The liquid part of the samples exerted a more potent relaxing effect on terminal ilea than the solids. Alkaline (NaOH) or microwave treated samples showed similar effects as untreated samples. Therefore we conclude that the major part of the reactive agent might be located in the liquid phase. We also demonstrate with this study that the used method enables the screening of waste water samples and their effect on terminal ilea. This method might be a tool to assess the environmental relevance of complex environmental samples.

Investigation of the electrophysiological properties of enniatins.

Enniatins are cyclohexadepsipeptides produced by various species of the genus Fusarium, and are known to have ionophoric, antibiotic, and in vitro hypolipidaemic properties. With the patch clamp technique in the inside-out mode it could be shown that enniatin easily incorporates into the cell membrane in which it forms cation-selective pores. This feature is characterized by unitary transitions to conductance levels typical for channels, ion selectivity, rectification, conductivity in the pS range, and block. A model of vertically stacked enniatin molecules that form sandwich complexes is suggested. Like gramicidin enniatin is a passive channel. Single channel properties for the isomers enniatin A1, B, and B1 differed from each other. This implies an influence of the substituted moieties on the complexation of cations. Electrical activity was followed by changes in intracellular ion concentrations, which are consistent with depolarization of the membrane resting potential, shortening of action potential duration, and reduced contractility.