Role of poorly differentiated cluster in gastric cancer: is it a new prognosis factor?

BACKGROUND: Poorly differentiated Clusters (PDCs) of tumor cells composed of more than five elements have been recently described in gastrointestinal cancers and correlate with a worse prognosis. Our study aims to investigate PDC occurrence in a series of patients with gastric cancer and correlate it with lymph node status and clinical outcome. MATERIAL AND METHODS: 50 patients were included in the study; PDCs count was graduated as G1, G2, and G3 according to Ueno classification (PDCs count at 20× <5, 5-9 and ≥10 respectively). We collected several clinicopathologic variables such as tumor location, pTNM stage, vascular or perineural invasion, and lymph-node ratio for each case. RESULTS: The presence of PDCs was related to vascular invasion (p < .013) and recurrence event (p < .027). When the population was categorized according to the number of PDCs, a significant correlation was found with the presence of lymph node metastasis (p < .000), the Lymph Node Ratio (p < .002), WHO stage at the diagnosis (p < .000) and vascular invasion (p < .001). At the univariate and multivariate analysis, PDCs were found as an independent risk factor for recurrence (HR 1.94; CI 95% 1.209-3.121; p < .006 and HR 0.401; CI 95% 0.187-0.862; p < .017 respectively). The Kaplan-Meier curves for OS and DFS showed a significant association between PDCs and shorter time to recurrence or survival. CONCLUSION: PDC is a strong prognostic factor in gastric cancer, easily detectable, and feasible. As far as we know, this is the first report in Literature of a strong correlation between PDC and survival in patients with operated gastric cancer.

Establishment and Morphological Characterization of Patient-Derived Organoids from Breast Cancer.

BACKGROUND: Patient-derived organoids (PDO) technology represents an emerging tool for the study of tumor biology and drug responsiveness, thus being useful to design personalized medicine approaches. Despite several studies and clinical trials are ongoing using PDO from colorectal and pancreatic cancer, only few research papers have been published exploiting PDO from breast cancer. Here, we have developed a new protocol to establish PDO from surgical and biopsy samples. Furthermore, we have set up also the methodologies adopted for culture and morphological evaluations. RESULTS: Surgical and core biopsy specimens collected from 33 patients with diagnosis of breast cancer have been processed using the protocols here described obtaining PDO from cancerous and healthy mammary tissue (when available) in a quick and easy way with good yields. The more critical aspects influencing the yield were the characteristic of the tissue of origin (healthy vs tumor tissue) and the amount of material obtained after enzymatic digestion process. Success rate from healthy samples was about 20,83%, while this percentage was higher in samples from cancer tissue (i.e. 87,5%). Also the morphological characterization of breast cancer PDO by brightfield and transmission electron microscopy has been reported. CONCLUSIONS: Despite obtaining some organoids from a surgical or biopsy specimen is not a difficult procedure, the establishment of a stable organoid line able to grow and replicate, suitable for long-term biobank storage, is not so obvious. A novel, simple and quick procedure to obtain PDO from surgical and biopsy samples is here proposed to achieve high success rate .

Prognostic factors in gastric cancer patients: a 10-year mono-institutional experience.

Introduction: Gastric cancer (GC) is one of the main causes of death from cancer globally. Long-term survival, especially in Western countries, remains dismal, with no significant improvements in recent years. Therefore, precise identification of clinical and pathological risk factors is crucial for prognosis, as it allows a better selection of patients suitable for oncologically radical treatments and contributes to longer survivals. Methods: We devised a retrospective observational longitudinal study over 10 years of experience with GC patients operated with curative intent. Results: Several factors were thoroughly investigated in a multivariate analysis to look for significance as independent risk factors for disease-free survival. Our results showed that only BMI, pTNM, and lymph node ratio expressed hazard ratios with implications for survival in our series of patients. Discussion: Although limited by the retrospective nature of the study, this is one of the few cancer reports from Northern Italy showing results over 10 years, which may in our view, have an impact on decision-making processes for multidisciplinary teams dedicated to the care of gastric cancer patients.

Prognostic value of specific KRAS mutations in patients with colorectal peritoneal metastases.

BACKGROUND: There is little evidence on KRAS mutational profiles in colorectal cancer (CRC) peritoneal metastases (PM). This study aims to determine the prevalence of specific KRAS mutations and their prognostic value in a homogeneous cohort of patients with isolated CRC PM treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. MATERIALS AND METHODS: Data were collected from 13 Italian centers, gathered in a collaborative group of the Italian Society of Surgical Oncology. KRAS mutation subtypes have been correlated with clinical and pathological characteristics and survival [overall survival (OS), local (peritoneal) disease-free survival (LDFS) and disease-free survival (DFS)]. RESULTS: KRAS mutations occurred in 172 patients (47.5%) out of the 362 analyzed. Two different prognostic groups of KRAS mutation subtypes were identified: KRASMUT1 (G12R, G13A, G13C, G13V, Q61H, K117N, A146V), median OS > 120 months and KRASMUT2 (G12A, G12C, G12D, G12S, G12V, G13D, A59E, A59V, A146T), OS: 31.2 months. KRASMUT2 mutations mainly occurred in the P-loop region (P < 0.001) with decreased guanosine triphosphate (GTP) hydrolysis activity (P < 0.001) and were more frequently related to size (P < 0.001) and polarity change (P < 0.001) of the substituted amino acid (AA). When KRASMUT1 and KRASMUT2 were combined with other known prognostic factors (peritoneal cancer index, completeness of cytoreduction score, grading, signet ring cell, N status) in multivariate analysis, KRASMUT1 showed a similar survival rate to KRASWT patients, whereas KRASMUT2 was independently associated with poorer prognosis (hazard ratios: OS 2.1, P < 0.001; DFS 1.9, P < 0.001; LDFS 2.5, P < 0.0001). CONCLUSIONS: In patients with CRC PM, different KRAS mutation subgroups can be determined according to specific codon substitution, with some mutations (KRASMUT1) that could have a similar prognosis to wild-type patients. These findings should be further investigated in larger series.

Genetic diversity and its impact on disease severity in respiratory syncytial virus subtype-A and -B bronchiolitis before and after pandemic restrictions in Rome.

OBJECTIVES: To scrutinize whether the high circulation of respiratory syncytial virus (RSV) observed in 2021-2022 and 2022-2023 was due to viral diversity, we characterized RSV-A and -B strains causing bronchiolitis in Rome, before and after the COVID-19 pandemic. METHODS: RSV-positive samples, prospectively collected from infants hospitalized for bronchiolitis from 2017-2018 to 2022-2023, were sequenced in the G gene; phylogenetic results and amino acid substitutions were analyzed. Subtype-specific data were compared among seasons. RESULTS: Predominance of RSV-A and -B alternated in the pre-pandemic seasons; RSV-A dominated in 2021-2022 whereas RSV-B was predominant in 2022-2023. RSV-A sequences were ON1 genotype but quite distant from the ancestor; two divergent clades included sequences from pre- and post-pandemic seasons. Nearly all RSV-B were BA10 genotype; a divergent clade included only strains from 2021-2022 to 2022-2023. RSV-A cases had lower need of O2 therapy and of intensive care during 2021-2022 with respect to all other seasons. RSV-B infected infants were more frequently admitted to intensive care units and needed O2 in 2022-2023. CONCLUSIONS: The intense RSV peak in 2021-2022, driven by RSV-A phylogenetically related to pre-pandemic strains is attributable to the immune debt created by pandemic restrictions. The RSV-B genetic divergence observed in post-pandemic strains may have increased the RSV-B specific immune debt, being a possible contributor to bronchiolitis severity in 2022-2023.

Preliminary results of a program for the implementation of laparoscopic colorectal surgery in an Italian comprehensive cancer center during the COVID-19 pandemic.

Despite operative benefit and oncological non-inferiority, videolaparoscopic (VLS) colorectal surgery is still relatively underutilized. This study analyzes the results of a program for the implementation of VLS colorectal surgery started in an Italian comprehensive cancer center shortly before COVID-19 outbreak. A prospective database was reviewed. The study period was divided in four phases: Phase-1 (Open surgery), Phase-2 (Discretional phase), Phase-3 (VLS implementation phase), and Phase-4 (VLS consolidation phase). Formal surgical and perioperative protocols were adopted from Phase-3. Postoperative complications were scored by the Clavien-Dindo classification. 414 surgical procedures were performed during Phase-1, 348 during Phase-2, 360 during Phase-3, and 325 during Phase-4. In the four phases, VLS primary colorectal resections increased from 11/214 (5.1%), to 55/163 (33.7%), 85/151 (57.0%), and 109/147 (74.1%), respectively. The difference was statistically significant (P < 0.001). All-type VLS procedures were 16 (3.5%), 61 (16.2%), 103 (27.0%), and 126 (38.6%) (P < 0.001). Conversions to open surgery of attempted laparoscopic colorectal resections were 17/278 in the overall series (6.1%), and 12/207 during Phase-3 and Phase-4 (4.3%). Severe (grades IIIb-to-V) postoperative complications of VLS colorectal resections were 9.1% in Phase-1, 12.7% in Phase-2, 12.8% in Phase-3, and 5.3% in Phase-4 (P = 0.677), with no significant differences with open resections in each of the four phases: 9.4% (P = 0.976), 11.1% (P = 0.799), 13.8% (P = 1.000), and 8.3% (P = 0.729). Despite the difficulties deriving from the COVID-19 outbreak, our experience suggests that volume of laparoscopic colorectal surgery can be significantly and safely increased in a specialized surgical unit by means of strict operative protocols.

Strong impact of sarcopenia as a risk factor of survival in resected gastric cancer patients: first Italian report of a Bicentric study.

Gastric cancer (GC) accounts for 4% of all cancers in Europe. Sarcopenia is a complex syndrome characterized by a loss of muscle mass and function associated with age, often present in neoplastic patients. Recently, several studies have shown a significant association between sarcopenia and poor prognosis in various pathological conditions. The current observational retrospective study investigates the association between sarcopenia and overall survival (OS) and recurrence-free survival (RFS) in patients with GC undergoing up-front surgery with curative intent. Resected GC patients' clinical records and CT images were retrospectively assessed. The preoperative CT calculation of the skeletal muscle index (SMI) at L3 level allowed us to categorize patients as sarcopenic or not. Kaplan-Meyer and univariate and multivariate Cox regression analyses were performed to determine the difference in survival and presence of independent prognostic factors. Fifty-five patients, 28 male and 27 female, out of 298 studied for gastric cancer were enrolled in the current study from two cancer referral centers in Italy. The preoperative CT calculation of the SMI at L3 level allowed us to identify 39 patients with and 16 without sarcopenia. A statistically significant difference between the sarcopenic and non-sarcopenic groups was observed in both OS and RFS (p < 0.023; p < 0.006). Moreover, sarcopenia was strongly correlated to a higher risk of recurrence in univariate and multivariate analysis (p < 0.02). Sarcopenia can be considered a critical risk factor for survival in patients with resectable GC treated with up-front surgery. Identifying sarcopenic patients at the time of diagnosis would direct selection of patients who could benefit from early nutritional and/or physical treatments able to increase their muscle mass and possibly improve the prognosis. More extensive multicenter studies are needed to address this issue.

Thrombin functions as an inflammatory mediator through activation of its receptor.

A rat model of inflammation was used to investigate the biological effects of thrombin. The thrombin-specific inhibitor Hirulog markedly attentuated the carrageenin-induced edema of the paw of the rat. Injection of thrombin into the paw also produced edema. The effect of thrombin was due to activation of its receptor; a thrombin receptor activating peptide (TRAP) reproduced the effects of thrombin in causing edema. TRAP also increased vascular permeability as demonstrated by extravasation of Evans blue and 125I-labeled serum albumin. The release of bioactive amines played an important role in mediating the TRAP-induced edema; the serotonin/histamine antagonist cryproheptadine and the histamine H2 receptor antagonist cimetidine reduced significantly the edema caused by TRAP. Treatment of rats with the mast cell degranulator 48/80 to deplete these cells of their stores of histamine and serotonin abolished completely the ability of TRAP to produce edema. Histochemical examination confirmed that TRAP treatment led to mast cell degranulation. Thus, it has been possible to demonstrate that thrombin acts as an inflammatory mediator in vivo by activating its receptor, which in turn leads to release of vasoactive amines from mast cells.

[Manual handling of loads in the hotel trade: the experience of the ASL (Local Health Unit) Milan]. / La movimentazione manuale dei carichi nel comparto alberghiero: l'esperienza della ASL di Milano.

UNLABELLED: There are over 400 hotels in Milan with a guest capacity of about 62,000 and employing more than 10,000 workers. In 2008/09 the Occupational Health and Safety Service of A.S.L. Milano (Local Health Unit) carried out research into the hotel trade to ascertain the development of this commercial sector, also in view of EXPO 2015. OBJECTIVES: The aim of the project was to improve hygiene and safety conditions and carry out preventive measures. A specific purpose was to study manual handling of loads and repetitive movements risk. METHOD: The study covered 30 hotels and 7 temporary staff cooperatives. We acquired the Risk Evaluation Document, the Health Surveillance Programme and Registers of Labour Accidents to analyze manual handling of loads and repetitive movements. In the investigations and assessments on hotels we used currently available scientific tools--NIOSH Lifting Index, Push and Pulling Analysis, OC.R.A. Check-List--to study risks related to handling loads and upper limb mechanical overload, which revealed a specific occupational risk that requires a fresh approach to prevention and safety in the entire sector. RESULTS: Chambermaid: LI (Range): 0.57-2.75; Push and Pulling Actions: Fi 0.66-Fm 1.5 and Fi 0.76-Fm 1.33 respectively; OC.R.A. Check-List: 21. Porter: LI (Range): 0.77-3.75. Maintenance staff LI (Range): 0.57-2.75. CONCLUSIONS: The study highlighted the presence of risk due to manual handling of loads and repetitive movements in porters, maintenance personnel and particularly in chambermaids that up to now have been poorly assessed by safety experts. Analysis of the information contained in the registers of labour accidents suggests that a significant number of accidents can be related to muscular-skeletal disorders that affect especially cleaning, portering and kitchen staff

Co-administration of H-ferritin-doxorubicin and Trastuzumab in neoadjuvant setting improves efficacy and prevents cardiotoxicity in HER2 + murine breast cancer model.

Neoadjuvant chemotherapy has been established as the standard of care for HER2-positive breast cancer since it allows cancer down-staging, up to pathological complete response. The standard of care in the neoadjuvant setting for HER2-positive breast cancer is a combination of highly cytotoxic drugs such as anthracyclines and the anti-HER2 monoclonal antibody. Despite this cocktail allows a pathological complete response in up to 50%, their co-administration is strongly limited by intrinsic cardiotoxicity. Therefore, only a sequential administration of anthracyclines and the anti-HER2 treatment is allowed. Here, we propose the anthracycline formulation in H-Ferritin nanocages as promising candidate to solve this unmet clinical need, thanks to its capability to increase anthracyclines efficacy while reducing their cardiotoxicity. Treating a murine model of HER2-positive breast cancer with co-administration of Trastuzumab and H-Ferritin anthracycline nanoformulation, we demonstrate an improved tumor penetration of drugs, leading to increased anticancer efficacy and reduced of cardiotoxicity.

Factor Xa as an interface between coagulation and inflammation. Molecular mimicry of factor Xa association with effector cell protease receptor-1 induces acute inflammation in vivo.

Coagulation proteases were tested in a rat model of acute inflammation. Subplantar injection of Factor Xa (10-30 microg) produced a time- and dose-dependent edema in the rat paw, and potentiated carrageenin-induced edema. In contrast, the homologous protease Factor IXa was ineffective. This inflammatory response was recapitulated by the Factor Xa sequence L83FTRKL88(G), which mediates ligand binding to effector cell protease receptor-1 (EPR-1), while a control scrambled peptide did not induce edema in vivo. Conversely, injection of the EPR-1-derived peptide S123PGKPGNQNSKNEPP137 (corresponding to the receptor binding site for Factor Xa) inhibited carrageenin-induced rat paw edema, while the adjacent EPR-1 sequence P136PKKRERERSSHCYP150 was without effect. EPR-1-Factor Xa-induced inflammation was characterized by fast onset and prominent perivascular accumulation of activated and degranulated mast cells, was inhibited by the histamine/serotonin antagonists cyproheptadine and methysergide, but was unaffected by the thrombin-specific inhibitor, Hirulog. These findings suggest that through its interaction with EPR-1, Factor Xa may function as a mediator of acute inflammation in vivo. This pathway may amplify both coagulation and inflammatory cascades, thus contributing to the pathogenesis of tissue injury in vivo.

H-Ferritin-nanocaged olaparib: a promising choice for both BRCA-mutated and sporadic triple negative breast cancer.

Poly(ADP-ribose) polymerase (PARP) inhibitors represent a promising strategy toward the treatment of triple-negative breast cancer (TNBC), which is often associated to genomic instability and/or BRCA mutations. However, clinical outcome is controversial and no benefits have been demonstrated in wild type BRCA cancers, possibly due to poor drug bioavailability and low nuclear delivery. In the attempt to overcome these limitations, we have developed H-Ferritin nanoformulated olaparib (HOla) and assessed its anticancer efficacy on both BRCA-mutated and non-mutated TNBC cells. We exploited the natural tumor targeting of H-Ferritin, which is mediated by the transferrin receptor-1 (TfR1), and its physiological tropism toward cell nucleus. TNBC cell lines over-expressing TfR-1 were successfully recognized by H-Ferritin, displaying a fast internalization into the cells. HOla induced remarkable cytotoxic effect in cancer cells, exhibiting 1000-fold higher anticancer activity compared to free olaparib (Ola). Accordingly, HOla treatment enhanced PARP-1 cleavage, DNA double strand breaks and Ola delivery into the nuclear compartment. Our findings suggest that H-Ferritin nanoformulation strongly enhances cytotoxic efficacy of Ola as a stand-alone therapy in both BRCA-mutated and wild type TNBC cells, by promoting targeted nuclear delivery.

[Postpartum hemorrhage]. / L'emorragia del postpartum.

Postpartum hemorrhage, frequently due to uterine atony, is an important cause of maternal death and morbidity. The knowledge of causes, of antenatal and intrapartum risk factors and of physiopathological changes in hemodynamics and coagulation during pregnancy are essential for the management of the condition. At the present time, many efforts are made to organize a multidisciplinary approach to this complication of delivery involving clinical and laboratory staffs, since the rapid correction of hypovolemia, the diagnosis and treatment of defective coagulation, the surgical and pharmacological control of bleeding are mandatory. Several medical options have been developed and the surgical management includes traditional and newer conservative procedures with variable success rates. The developments in the treatment of postpartum hemorrhage may reduce hysterectomy that is to be considered the last resort to resolve the hemorrhage in some cases. In the modern management of postpartum hemorrhage protocols and guidelines should be available in every delivery room.

Síndrome autoinmune inducido por inyección cosmética de ácido hialurónico / Autoimmune syndrome induced by cosmetic injection of hyaluronic acid

El síndrome autoinmune/inflamatorio inducido por adyuvantes (ASIA) es una condición en la cual la exposición a un adyuvante lleva a una respuesta inmune aberrante dando como resultado signos y síntomas de enfermedades autoinmunes. Se presenta el caso de una paciente con artritis y púrpura palpable luego de inyección labial de ácido hialurónico.

Autoimmune/inflammatory syndrome induced by adjuvant (ASIA) is a condition in which exposure to an adjuvant leads to an aberrant immune response resulting in signs and symptoms of autoimmune diseases. We present the case of a patient with arthritis and palpable purpura after hyaluronic acid lip injection.

Synthesis and pharmacological activity of deltorphin and dermorphin-related glycopeptides.

The solid phase procedure, based on the Fmoc chemistry, was used to prepare some opioid deltorphin (H-Tyr-D-Ala-Phe-Asp-Val-Val-Gly-NH2, DEL C) and dermorphin (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2, DER) analogues in which a D-glucopyranosyl moiety is beta-O-glycosidically linked to a Thr4 or Thr7 side chain. Their activities were determined in binding studies based on displacement of mu- and delta-receptor selective radiolabels from rat brain membrane synaptosomes, in guinea pig ileum and rabbit jejenum bioassays, and, in vivo, by a mouse tail-flick test after intracerebroventricular (icv) and subcutaneous (sc) administrations. The glyco analogues modified at position 4 displayed low opioid properties, while Thr7-glycosylated peptides retained high delta- or mu-selectivity and remarkable activity in vivo. In particular, as systemic antinociceptive agents, the latter glucoside-bearing compounds were more potent than the parent unglycosylated peptide counterparts, showing a high blood to brain rate of influx which may be due to the glucose transporter GLUT-1.

Differential influence of D1 and D2 dopamine receptors on acute opiate withdrawal in guinea-pig isolated ileum.

1. The effects exerted by D1 and D2 dopamine agonists and antagonists on the acute opiate withdrawal induced by mu- and kappa-receptor agonists were investigated in vitro. 2. Following a 4 min in vitro exposure to morphine (moderately selective mu-agonist), [D-Ala2, Me-Phe4, Gly-ol5]enkephalin (DAMGO, highly selective mu-agonist) or U-50488H (highly selective kappa-agonist) the guinea-pig isolated ileum exhibited a strong contracture after the addition of naloxone. 3. The non-selective dopamine receptor antagonist haloperidol when added before or after the opioid agonists, was able dose-dependently to prevent or to reverse the naloxone-induced contracture after exposure to mu- (morphine and DAMGO) and kappa- (U-50488H) opioid agonists. The non-selective dopamine receptor agonist, apomorphine, was able to exert the same effects only at the highest concentration used. 4. The selective D2 dopamine receptor antagonist, sulpiride, was also able to reduce dose-dependently both mu- and kappa-opioid withdrawal, whereas the D1-receptor selective antagonist SCH 23390 did not affect either mu- or kappa-opioid withdrawal. 5. Bromocriptine, a D2 selective dopamine receptor agonist was able to increase significantly, and in a concentration-dependent manner, the naloxone-induced contracture by mu- and kappa-opioid agonists, whereas SKF 38393, a D1 selective dopamine receptor agonist, increased only the withdrawal after morphine or U50-488H. 6. Our data indicate that both D1 and D2 dopamine agonists and antagonists are able to influence opiate withdrawal in vitro, suggesting an important functional interaction between the dopaminergic system and opioid withdrawal at both the mu- and kappa-receptor level. 7. Furthermore, the ability of sulpiride to block strongly opiate withdrawal when compared to SCH 23390, as well as the effect of bromocriptine to increase opiate withdrawal suggest that D2 dopamine receptors may be primarily involved in the control of opiate withdrawal.

Some pharmacodynamic properties of carrageenin in the rat.

1. Carrageenin oedema is suppressed by pre-treating the rats with cellulose sulphate, a kininogen depleting agent. This inhibition is closely related to the dose of cellulose sulphate and to the time course of kininogen depletion.2. Oedema induced by egg white or by dextran, in which the mediators are histamine and 5-hydroxytryptamine, is quite unaffected by cellulose sulphate treatment.3. Carrageenin injected intravenously lowers the arterial blood pressure of rats. This hypotensive effect is unaffected by histamine antagonists and is abolished by protease inhibitors and thus seems to be due to kinin release from plasma substrates.4. Like cellulose sulphate, carrageenin enhances the esterolytic activity of the blood from treated rats when incubated with benzoyl-arginine ethyl ester.5. The ability of carrageenin to activate the kinin-forming system could account for both its inflammatory and hypotensive effects.

Involvement of ATP-sensitive potassium channels in a model of a delayed vascular hyporeactivity induced by lipopolysaccharide in rats.

We have investigated the role of ATP-sensitive potassium (K(ATP)) channels in an experimental model of a delayed phase of vascular hyporeactivity induced by lipopolysaccharide (LPS) in rats. After 24 h, from LPS treatment, in anaesthetized rats the bolus injection of phenylephrine (PE) produced an increase in mean arterial pressure (MAP) significantly (P<0.05) reduced in LPS-treated rats compared to the vehicle-treated rats. This reduction was prevented by pre-treatment of rats with glibenclamide (GLB), a selective inhibitor of K(ATP) channels. GLB administration did not affect the MAP in vehicle-treated rats but produced an increase of MAP in rats treated with LPS. Cromakalim (CRK), a selective K(ATP) channel opener, produced a reduction of MAP that was significantly (P<0.05) higher in LPS- than in vehicle-treated rats. In contrast, the hypotension induced by glyceryl trinitrate (GTN) in LPS-treated rats was not distinguishable from that produced in vehicle-treated rats. Experiments in vitro were conducted on aorta rings collected from rats treated with vehicle or LPS 24 h before sacrifice. The concentration-dependent curve to PE was statistically (P<0.005) reduced in aorta rings collected from LPS- compared to vehicle-treated rats. This difference was totally abolished by tetraethylammonium (TEA), a non-selective inhibitor of K+ channels. CRK produced a relaxation of PE precontracted aorta rings higher in rings from LPS- than in vehicle-treated rats. GLB inhibited CRK-induced relaxation in both tissues, abolishing the observed differences. In conclusion, our results indicate an involvement of K(ATP) channels to the hyporesponsiveness of vascular tissue after 24 h from a single injection of LPS in rats. We can presume an increase in the activity of K(ATP) channels on vascular smooth muscle cells but we cannot exclude an increase of K(ATP) channel number probably due to the gene expression activation.

Dexamethasone-induced selective inhibition of the central mu opioid receptor: functional in vivo and in vitro evidence in rodents.

1. Endogenous corticosteroids and opioids are involved in many functions of the organism, including analgesia, cerebral excitability, stress and others. Therefore, we considered it important to gain information on the functional interaction between corticosteroids and specific opioid receptor subpopulations. 2. We have found that systemic administration (i.p.) of the potent synthetic corticosteroid, dexamethasone, reduced the antinociception induced by the highly selective mu agonist, DAMGO or by less selective mu agonists morphine and beta-endorphin administered i.c.v.. On the contrary dexamethasone exerted little or no influence on the antinociception induced by a delta 1 agonist, DPDPE and a delta 2 agonist deltorphin II. Dexamethasone potentiated the antinociception induced by the kappa agonist, U50,488. 3. In experiments performed in an in vitro model of cerebral excitability in the rat hippocampal slice, dexamethasone strongly prevented both the increase of the duration of the field potential recorded in CA1, and the appearance and number of additional population spikes induced by mu receptor agonists. 4. In both models pretreatment with cycloheximide, a protein synthesis inhibitor, prevented the antagonism by dexamethasone of responses to the mu opioid agonists. 5. Our data indicate that in the rodent brain there is an important functional interaction between the corticosteroid and the opioid systems at least at the mu receptor level, while delta and kappa receptors are modulated in different ways.