Quantitative distribution of Salmonella spp. and Escherichia coli on beef carcasses and raw beef at retail establishments.

Salmonella is a foodborne pathogen that commonly inhabits the gastrointestinal tract of a healthy feedlot cattle and can be transferred to the carcass surface during hide removal and evisceration procedures. Numerous investigations on Salmonella prevalence throughout different stages of the beef chain have been conducted. In contrast, limited studies are available on quantitative determinations of Salmonella at different steps in raw meat production. Quantitative data, particularly for pathogenic bacteria such as Salmonella are important for quantitative risk assessment. Salmonella spp. and Escherichia coli populations were enumerated on beef carcass samples collected at abattoirs and also in beef chunks and ground beef samples collected from butcher's shops at retail in Jalisco State, Mexico. Sponge samples from beef carcass sides (n=142) were collected immediately after final water wash and before chilling at three non-federally inspected abattoirs following USDA-FSIS sampling protocols. Beef chunks (n=84) and ground beef (n=65) samples were obtained from 86 butcher's shops. Salmonella enumeration was conducted by the Most Probable Number method and E. coli counts were determined using Petrifilm plates. Salmonella was isolated from 18% of beef carcasses, 39% of beef chunks and 71% of ground beef samples. Salmonella mean counts were 1.3±0.9 Log MPN/300 cm(2) on beef carcasses, 1.9±0.9 and 2.3±1.1 Log MPN/25 g in beef chunks and ground beef samples, respectively. Twenty-six Salmonella serotypes and 11 serogroups were identified among 432 isolates recovered. Salmonella typhimurium (14%), Salmonella sinstorf (12%) and S. Group E1 monophasic (10%) were the most frequent. Escherichia coli was present on 97, 84 and 100% of beef carcasses, beef chunks and ground beef samples, respectively. Escherichia coli mean counts were 3.2±0.7 Log CFU/300 cm(2), 3.9±1.1 and 4.5±1.2 Log CFU/25 g on beef carcasses, beef chunks and ground beef, respectively. Salmonella prevalence and mean counts found in raw beef were higher than previously reported in studies from other countries. The data collected in this study show a trend in the prevalence of Salmonella to be higher as meat processing is extended at retail. This, together with the diversity of serotypes found, indicates that raw meat is exposed to multiple contamination sources during slaughter and retail processing and highlights the necessity to implement Sanitation Standard Operating Procedures for those establishments. Finally, this study provides quantitative information for future risk assessments associated with the risk of human salmonellosis.

Age at menopause, motives for consultation and symptoms reported by 40-59-year-old Mexican women.

OBJECTIVES: To assess the mean age at natural menopause, primary initial motives for consultation, symptoms and factors related to a more severe symptom profile using the Menopause Rating Scale (MRS) in a nationwide sample of middle-aged women in gynecological clinics in Mexico. METHODS: A total of 4548 women, 40-59 years old were surveyed in gynecological clinics throughout all regions in Mexico. RESULTS: The mean age at natural menopause was 47.9 ± 3.82 years. The primary initial motive for consultation was a preventive examination (40.3%). Significant differences (p values by ANOVA) were observed for the mean total and subscale MRS scores, with the exception of urogenital symptoms, between women in the sub-samples from different Mexican regions. The highest mean MRS total scores were observed for women living in the South (9.08 ± 8.20) and the Center-East (8.55 ± 6.74) regions. The national mean MRS total score was 8.19 ± 6.82. An MRS total score ≥ 17, which is considered severe, was observed for 5.2% of women with a regular cycle, 10.5% with more than 7 days of irregularity, 22.6% with more than two absent cycles, 13.1% that had undergone natural menopause, 16% with a hysterectomy, and 21.2% with a bilateral oophorectomy. The five most frequently reported symptoms were: physical and mental exhaustion (61%), irritability (54.2%), depressive mood (54.2%), sleeping problems (53.3%), joint and muscular discomfort (52.8%). CONCLUSIONS: Differences in the prevalence and severity of MRS symptoms were observed for women from different Mexican regions. MRS symptoms were more frequent and severe in women who had undergone a bilateral oophorectomy or with more than two absent cycles.

Pre-synaptic histamine H3 receptors modulate glutamatergic transmission in rat globus pallidus.

The globus pallidus, a neuronal nucleus involved in the control of motor behavior, expresses high levels of histamine H(3) receptors (H(3)Rs) most likely located on the synaptic afferents to the nucleus. In this work we studied the effect of the activation of rat pallidal H(3)Rs on depolarization-evoked neurotransmitter release from slices, neuronal firing rate in vivo and turning behavior. Perfusion of globus pallidus slices with the selective H(3)R agonist immepip had no effect on the release of [(3)H]-GABA ([(3)H]-γ-aminobutyric acid) or [(3)H]-dopamine evoked by depolarization with high (20 mM) K(+), but significantly reduced [(3)H]-d-aspartate release (-44.8 ± 2.6% and -63.7 ± 6.2% at 30 and 100 nM, respectively). The effect of 30 nM immepip was blocked by 10 µM of the selective H(3)R antagonist A-331440 (4'-[3-[(3(R)-dimethylamino-1-pyrrolidinyl]propoxy]-[1,1-biphenyl]-4'-carbonitrile). Intra-pallidal injection of immepip (0.1 µl, 100 µM) decreased spontaneous neuronal firing rate in anaesthetized rats (peak inhibition 68.8±10.3%), and this effect was reversed in a partial and transitory manner by A-331440 (0.1 µl, 1 mM). In free-moving rats the infusion of immepip (0.5 µl; 10, 50 and 100 µM) into the globus pallidus induced dose-related ipsilateral turning following systemic apomorphine (0.5 mg/kg, s.c.). Turning behavior induced by immepip (0.5 µl, 50 µM) and apomorphine was partially prevented by the local injection of A-331440 (0.5 µl, 1 mM) and was not additive to the turning evoked by the intra-pallidal injection of antagonists at ionotropic glutamate receptors (0.5 µl, 1 mM each of AP-5, dl-2-amino-5-phosphonovaleric acid, and CNQX, 6-nitro-7-sulphamoylbenzo[f]quinoxaline-2,3-dione). These results indicate that pre-synaptic H(3)Rs modulate glutamatergic transmission in rat globus pallidus and thus participate in the control of movement by basal ganglia.

Differential localization of Acid-sensing ion channels 1 and 2 in human cutaneus pacinian corpuscles.

Acid-sensing ion channels (ASICs) are the members of the degenerin/epithelial sodium channel (Deg/ENaC) superfamily which mediate different sensory modalities including mechanosensation. ASICs have been detected in mechanosensory neurons as well as in peripheral mechanoreceptors. We now investigated the distribution of ASIC1, ASIC2, and ASIC3 proteins in human cutaneous Pacinian corpuscles using immunohistochemistry and laser confocal-scanner microscopy. We detected different patterns of expression of these proteins within Pacinian corpuscles. ASIC1 was detected in the central axon co-expressed with RT-97 protein, ASIC2 was expressed by the lamellar cells of the inner core co-localized with S100 protein, and ASIC3 was absent. These results demonstrate for the first time the differential distribution of ASIC1 and ASIC2 in human rapidly adapting low-threshold mechanoreceptors, and suggest specific roles of both proteins in mechanotransduction.

The expression of ENa(+)C and ASIC2 proteins in Pacinian corpuscles is differently regulated by TrkB and its ligands BDNF and NT-4.

Pacinian corpuscles are innervated by large myelinated Aalpha-beta axons from the large- and intermediate-sized sensory neurons of dorsal root ganglia. These neurons express different members of the degenerin/epithelial Na(+) channel (DEG/ENa(+)C) superfamily of proteins with putative mechanosensory properties, whose expression is regulated by the TrkB-BDNF system. Thus, we hypothesized that BDNF and/or NT-4 signalling through activation of TrkB may regulate the expression of molecules supposed to be necessary for the mechanosensory function of Pacinian corpuscles. To test this hypothesis we analyzed the expression and distribution of ENa(+)C subunits and acid-sensing ion channel 2 (ASIC2) in Pacinian corpuscles from 25 days old mice deficient in TrkB, BDNF and NT-4. Pacinian corpuscles in these animals are normal in number, structure, and expression of several immunohistochemical markers. Using immunohistochemistry we observed that the beta-ENa(+)C and gamma-ENa(+)C subunits, but not the alpha-ENa(+)C subunit, were expressed in wild-type animals, and they were always found in the central axon. ASIC2 immunoreactivity was found in both the central axon and the inner core cells. The absence of TrkB or BDNF abolished expression of beta-ENa(+)C and ASIC2, whereas expression of gamma-ENa(+)C did not change. Expression of beta-ENa(+)C and gamma-ENa(+)C subunits in NT-4 deficient mice was found in the axons but also in the inner core cells whereas levels of expression of ASIC2 were increased in these animals. This study suggests that expression in Pacianian corpuscles of some potential mechanosensory proteins is regulated by BDNF, NT-4 and TrkB.

Myelin basic protein-positive nerve fibres in human Meissner corpuscles.

Myelinated nerve fibres forming sensory corpuscles become amyelinic before entering the corpuscle. Interestingly, in Meissner corpuscles from monkey myelin basic protein (MBP), a specific component of myelin sheath co-localized with neuronal markers. To investigate whether or not this also occurs in human digital Meissner corpuscles, we used single and double immunohistochemistry to detect MBP associated with axonic (protein gene product (PGP) 9.5) or Schwann and Schwann-related cell (S100 protein) markers. We also studied these markers in Pacinian corpuscles. Nerve fibres immunoreactive for MBP were detected in about 25% of the Meissner corpuscles examined; however, MBP never co-localized with PGP 9.5 and MBP occasionally co-localized with S100 protein. MBP-immunoreactive fibres associated with Meissner corpuscles were observed at the periphery of the lamellar cells or within the corpuscle between the lamellar cells. These results describe the distribution of myelinated nerve fibres expressing MBP in human Meissner corpuscles, which is important when studying Meissner corpuscles in cutaneous biopsies used for the diagnosis of peripheral and degenerative neuropathies.

Dopamine D(1) receptor facilitation of depolarization-induced release of gamma-amino-butyric acid in rat striatum is mediated by the cAMP/PKA pathway and involves P/Q-type calcium channels.

Transmission in the "direct" pathway through the basal ganglia, which has an important role in the control of motor movement, is markedly facilitated by the concurrent activation of dopamine D(1) receptors. Consistent with this, Ca(2+)-dependent, depolarization-induced release of [(3)H]-GABA from striatal slices from rats pretreated with reserpine was greatly increased in the presence of 1 microM SKF 38393, a dopamine D(1)-like receptor agonist. The effect of SKF 38393 was mimicked by 1 mM 8-bromo-cyclic AMP (Br-cAMP) and inhibited by the protein kinase A (PKA) inhibitor H-89, mean inhibition 92% +/- 4% with 10 microM H-89 (n = 3). The effects of SKF 38393 and Br-cAMP were not additive. The stimulatory effects of SKF 38393 and Br-cAMP were practically abolished in the presence of the histamine H(3) receptor agonist immepip (1 microM). The depolarization-induced release of [(3)H]-GABA in the presence of SKF 38393 was not significantly inhibited by 5 microM nimodipine, an L-type Ca(2+) channel blocker, or by 0.3 microM omega-conotoxin MVIIA, a selective blocker of N-type channels. However, preincubation of the slices with 0.95 microM omega-agatoxin TK, a P/Q-type channel blocker, followed by washing before changing to a depolarizing medium containing SKF 38393, resulted in a marked inhibition of the stimulated release of [(3)H]-GABA, mean 68% +/- 4% (n = 3). These observations provide evidence that dopamine D(1) agonist facilitation of the depolarization-induced release of GABA from striatal terminals is mediated by the cAMP/PKA pathway and involves mainly P/Q-type Ca(2+) channels.

[Prognostic value of E-cadherina, beta catenin, Ki-67 antigen and p53 protein in the superficial bladder tumors]. / Cadherina E, catenina beta, antígeno Ki-67 y proteína p53 en el pronóstico de la recidiva tumoral en los tumores superficiales de vejiga T1.

INTRODUCTION: The natural history of the superficial carcinoma of bladder is characterized by his high rate of recurrence and by the aptitude to progress to higher stages. We are going to investigate the capacity of prediction for tumor recurrence of protein p53, antigen Ki-67, E Cadherin and Beta Catenin MATERIAL AND METHOD: 88 T1 tumors with a median of free time of disease of 36 months. 58% of the serie has received prophylactic treatment with BCG 81 mg. weekly for six weeks. Cut-oof level for For P53 and Ki-67 is 10 % of stained cells. For E Cadherin and Beta Catenin we have established two groups: one with the values 0-4 (negative), and other one with the values 5-8 (positive). RESULTS: Recurrence rate 31%, stage progression 3%. Ki-67 expression is correlated with grade (p .002) and lymphatic permeation (p .028). Multiplicity is correlated with lack( of Cadherin and Catenin's expression. Only Ki-67 expression (p .049) and lack of Beta Catenin expression (p .039) reach statistical significance. In multivariant study only lack of Beta Catenin's expression shows independent recurrence value (p .049; O.R: 2,4-6,9) CONCLUSIONS: The most useful prognmostic markers are Ki-67 and Catenina Beta Only Beta Catenin Beta shows independent value for tumour recurrence. Tumors wich lack expression for Catenin B or Cadherin E have lower recurrence free time.

Cadherina E, Catenina Beta, Antígeno Ki-67 y proteína p53 en el pronóstico de la recidiva tumoral en los tumores superficiales de vejiga T1 / Prognostic value of E-Cadherina, Beta Catenin, K1, Ki-67 antigen and p53 protein in the superficial bladder tumors

Introducción: La historia natural del carcinoma superficial de vejiga (CSV) se caracteriza por su alta tasa de recidivas y por la capacidad de progresar a estadios infiltrantes. Vamos a investigar la capacidad de predicción de recidiva tumoral de la proteína p53, el antígeno Ki-67 y las moléculas de adhesión celular Cadherina E y Catenina Beta Material y método: 88 tumores T1 con una mediana de tiempo libre de enfermedad de 36 meses. Han recibido tratamiento profiláctico con BCG 81 mg. semanal durante seis semanas el 58% de la serie. Para p53 y Ki-67 se estableció el nivel de 10% de células teñidas para considerar positivo el tumor. Para Cadherina E y Catenina se han establecido dos grupos: uno con los valores 0-4 (negativo), y otro con los valores 5-8 (positivo). Resultados: Han recidivado el 31% de los tumores y progresado a estadio infiltrante el 3% La expresión de Ki-67 se correlaciona con grado (p ,002) y permeación linfática (p ,028). La multiplicidad tumoral con la falta de expresión de Cadherina E y Catenina Beta. Sólo la expresión de Ki-67 (p .049) y la de Catenina Beta (p .039) alcanzan significación estadística. En el estudio multivariante sólo la falta de expresión de Catenina Beta muestra tener valor pronóstico independiente para recidiva (p .049; O.R : 2,4-6,9) Conclusiones: Los marcadores más útiles son Ki-67 y Catenina Beta. Sólo la Catenina Beta muestra un valor independiente para recidiva tumoral. Los tumores que no expresan Catenina Beta o Cadherina E tienen un menor tiempo libre de recidiva

Introduction: The natural history of the superficial carcinoma of bladder is characterized by his high rate of recurrence and by the aptitude to progress to higher stages. We are going to investigate the capacity of prediction for tumor recurrence of protein p53, antigen Ki-67, E Cadherin and Beta Catenin Material and method: 88 T1 tumors with a median of free time of disease of 36 months. 58% of the serie has received prophylactic treatment with BCG 81 mg. weekly for six weeks. Cut-oof level for For P53 and Ki-67 is 10 % of stained cells. For E Cadherin and Beta Catenin we have established two groups: one with the values 0-4 (negative), and other one with the values 5-8 (positive). Results: Recurrence rate 31 %, stage progression 3 %. Ki-67 expression is correlated with grade (p .002) and lymphatic permeation (p .028). Multiplicity is correlated with lack( of Cadherin and Catenin´s expression. Only Ki-67 expression (p .049) and lack of Beta Catenin expression (p .039) reach statistical significance. In multivariant study only lack of Beta Catenin’s expression shows independent recurrence value (p .049; O.R: 2,4-6,9) Conclusions: The most useful prognmostic markers are Ki-67 and Catenina Beta Only Beta Catenin Beta shows independent value for tumour recurrence. Tumors wich lack expression for Catenin B or Cadherin E have lower recurrence free time

Gamma-aminobutyric acid transporter (BGT-1) expressed in human astrocytoma U373 MG cells: pharmacological and molecular characterization and phorbol ester-induced inhibition.

The properties of a transport system specific for gamma-aminobutyric acid (GABA) expressed in human U373 MG astrocytoma cells were examined. The uptake of [(3)H]GABA was dependent on both extracellular Na(+) and Cl(-) ions and was inhibited by (+/-)-nipecotic acid, guvacine, and beta-alanine, with a pharmacological profile corresponding to that reported for the human homologue of the GABA/betaine transporter (BGT-1). Accordingly, [(3)H]GABA uptake was also inhibited by betaine, and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of total RNA from U373 MG cells with specific BGT-1 primers resulted in the amplification of a 440 bp fragment that was further characterized by restriction analysis and sequencing. In addition, Western blot analysis with anti-BGT-1 antiserum revealed the presence of a characteristic 60 kDa band. The primary structure of the human BGT-1 protein predicts two putative phosphorylation sites for the Ca(2+)/diacylglicerol-dependent protein kinase (PKC), and treatment of U373 MG cells with the PKC activator phorbol 12-myristate-13-acetate (TPA) led to a concentration- and time-dependent decrease in [(3)H]GABA uptake. The maximal effect was detected at 2 hr of incubation, to disappear after 4 hr. TPA-induced reduction in [(3)H]GABA uptake was reversed by preincubation with staurosporine. Taken together, these results indicate that U373 MG cells express a GABA transporter of the BGT-1 subtype whose function is regulated by phosphorylation events through PKC.

The initial inositol 1,4,5-trisphosphate response induced by histamine is strongly amplified by Ca(2+) release from internal stores in smooth muscle.

We have studied the Ca(2+)-dependence and wortmannin-sensitivity of the initial inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)) response induced by activation of either histamine or muscarinic receptors in smooth muscle from guinea pig urinary bladder. Activation of H(1) receptors with histamine (100 microM) produced a significant elevation in Ins(1,4,5)P(3) levels with only 5s stimulation and in the presence of external Ca(2+). However, this response was abolished fully by either the prolonged absence of external Ca(2+) or the depletion of internal Ca(2+) stores with thapsigargin (100nM) or ryanodine (10 microM). In contrast, the same conditions only slightly reduced the initial Ins(1,4,5)P(3) response induced by carbachol. The prolonged incubation of smooth muscle in 10 microM wortmannin to inhibit type III PI 4-kinase abolished both the early histamine-evoked Ins(1,4,5)P(3) and Ca(2+) responses. Conversely, wortmannin did not alter Ca(2+) release induced by carbachol, despite a partial reduction of its Ins(1,4,5)P(3) response. Collectively, these data indicate that the detectable histamine-induced increase in Ins(1,4,5)P(3) is more the consequence of Ca(2+) release from internal stores than a direct activation of phospholipase C by H(1) receptors. In addition, the effect of wortmannin implies the existence of a Ca(2+)-dependent amplification loop for the histamine-induced Ins(1,4,5)P(3) response in smooth muscle.

Hippocampal hyperexcitability induced by GABA withdrawal is due to down-regulation of GABA(A) receptors.

The sudden interruption of an intracortical instillation of exogenous gamma-aminobutyric acid (GABA) generates an epileptic focus in mammals. Seizures elicited by GABA withdrawal (GW) last for weeks. A similar withdrawal-induced hyperexcitability is also produced by several GABA(A) receptor agonists. This work reports a quantitative analysis of GW-induced hyperexcitability produced in the hippocampus in vitro. GW produced a left-ward displacement of the input/output (I/O) function, suggesting that the postsynaptic component is predominant to explain the hyperexcitability. A decrease in the inhibitory efficacy of the GABA(A) receptor agonist, muscimol, confirmed that inhibition was impaired. Binding saturation experiments demonstrated a decrease in [(3)H]-muscimol binding after GABA withdrawal showing a close correlation with the development of hyperexcitability. All these modifications coursed without changes in receptor affinity (K(D)) for muscimol or bicuculline as demonstrated by both binding studies and Schild analysis. It is concluded that, in the CA1 region of the hippocampus, it is the number of functional GABA(A) receptors, and not the affinity of the receptor, what is decreased during GW-induced hyperexcitability.

Glutamate activates PP125(FAK) through AMPA/kainate receptors in Bergmann glia.

Glial glutamate receptors are likely to play a role in plasticity, learning, and memory and in a number of neuropathologies. An enhanced glutamate-dependent tyrosine phosphorylation has been detected in such processes. Using primary cultures of chick Bergmann glia cells and chick cerebellar slices, we addressed whether glial glutamate receptors can activate the nonreceptor tyrosine kinase pp125 focal adhesion kinase (pp125(FAK)). A dose- and time-dependent tyrosine phosphorylation of pp125(FAK) was found in both preparations upon glutamate treatment. This effect was mediated through alpha-amino-3-hydroxy-5-methyl-4-isoaxazolepropionate (AMPA)/kainate (KA) receptors, as shown by its inhibition by the specific antagonists 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7- sulfonamide (NBQX) and 6,7-dinitroquinoxaline-2,3-dione (DNQX) and the lack of effect of metabotropic agonists. FAK tyrosine phosphorylation was dependent on phosphatidylinositol 3-kinase activity. As expected, an increase in pp125(FAK) catalytic activity was found upon glutamate treatment. Immunprecipitation experiments demonstrated that FAK associates with ionotropic glutamate receptors. Taken together, these results suggest a role for glial glutamate receptors in cytoskeletal rearrengments and focal adhesion contact formation and provide new insight into the signaling transactions elicited by this neurotransmitter in glial cells.

Histamine H3 receptor activation inhibits glutamate release from rat striatal synaptosomes.

The release of glutamate from striatal synaptosomes induced by depolarisation with 4-aminopyridine (4-AP) was studied by a method based on the fluorescent properties of the NAPDH formed by the metabolism of the neurotransmitter by glutamate dehydrogenase.Ca(2+)-dependent, depolarisation-induced glutamate release was inhibited in a concentration-dependent manner by the selective histamine H(3) agonist immepip. Best-fit estimates were: maximum inhibition 60+/-10% and IC(50) 68+/-10 nM. The effect of 300 nM immepip on depolarisation-evoked glutamate release was reversed by the selective H(3) antagonist thioperamide in a concentration-dependent manner (EC(50) 23 nM, K(i) 4 nM). In fura-2-loaded synaptosomes, the increase in the intracellular concentration of Ca(2+) ([Ca(2+)](i)) evoked by 4-AP-induced depolarisation (resting level 167+/-14 nM; Delta[Ca(2+)](i) 88+/-15 nM) was modestly, but significantly reduced (29+/-5% inhibition) by 300 nM immepip. The action of the H(3) agonist on depolarisation-induced changes in [Ca(2+)](i) was reversed by 100 nM thioperamide. Taken together, our results indicate that histamine modulates the release of glutamate from corticostriatal nerve terminals. Inhibition of depolarisation-induced Ca(2+) entry through voltage-dependent Ca(2+) channels appears to account for the effect of H(3) receptor activation on neurotransmitter release. Modulation of glutamatergic transmission in rat striatum may have important consequences for the function of basal ganglia and therefore for the control of motor behaviour.

Histamine H(1) receptor activation inhibits the proliferation of human prostatic adenocarcinoma DU-145 cells.

BACKGROUND: Histamine stimulates cell proliferation in some tumor cell lines through the activation of H(1) receptors coupled to phosphoinositide hydrolysis. We therefore set out to study the presence of H(1) receptors in the prostate cancer cell line DU-145 and the effect of their stimulation on cell growth. METHODS: The presence of histamine receptors was studied by radioligand binding. Phosphoinositide hydrolysis was assessed by measuring [(1)H]-inositol phosphate ([(1)H]-IPs) accumulation and changes in the intracellular concentration of free Ca(2+) ([Ca(2+)](i)). Proliferation was assessed by cell counting and by [(1)H]-thymidine incorporation. RESULTS: DU-145 cells express H(1) receptors (110+/-14 fmol/mg of protein) whose stimulation results in [(1)H]-IPs accumulation (602+/-23% of basal, EC(50) 2.2+/-0.4 microM) and calcium mobilization (resting level 96+/-5 nM, Delta[Ca(2+)](i) 517+/-32 nM, EC(50) 6.2+/-0.1 microM). Incubation with histamine (100 microM, 24 hr) resulted in a decrease in both cell number and [(1)H]-thymidine incorporation, blocked by the H(1) antagonist mepyramine (1 microM). CONCLUSIONS: Histamine inhibits the proliferation of DU-145 cells through the activation of H(1) receptors coupled to phosphoinositide hydrolysis.

Histamine H(3) receptor-mediated inhibition of depolarization-induced, dopamine D(1) receptor-dependent release of [(3)H]-gamma-aminobutryic acid from rat striatal slices.

1. A study was made of the regulation of [(3)H]-gamma-aminobutyric acid ([(3)H]-GABA) release from slices of rat striatum by endogenous dopamine and exogenous histamine and a histamine H(3)-agonist. Depolarization-induced release of [(3)H]-GABA was Ca(2+)-dependent and was increased in the presence of the dopamine D(2) receptor family antagonist, sulpiride (10 microM). The sulpiride-potentiated release of [(3)H]-GABA was strongly inhibited by the dopamine D(1) receptor family antagonist, SCH 23390 (1 microM). Neither antagonist altered basal release. 2. The 15 mM K(+)-induced release of [(3)H]-GABA in the presence of sulpiride was inhibited by 100 microM histamine (mean inhibition 78+/-3%) and by the histamine H(3) receptor-selective agonist, immepip, 1 microM (mean inhibition 81+/-5%). The IC(50) values for histamine and immepip were 1.3+/-0.2 microM and 16+/-2 nM, respectively. The inhibitory effects of histamine and immepip were reversed by the H(3) receptor antagonist, thioperamide, 1 microM. 3. The inhibition of 15 mM K(+)-induced [(3)H]-GABA release by immepip was reversed by the H(3) receptor antagonist, clobenpropit, K(d) 0.11+/-0.04 nM. Clobenpropit alone had no effect on basal or stimulated release of [(3)H]-GABA. 4. Elevated K(+) caused little release of [(3)H]-GABA from striatal slices from reserpinized rats, unless the D(1) partial agonist, R(+)-SKF 38393, 1 microM, was also present. The stimulated release in the presence of SKF 38393 was reduced by 1 microM immepip to the level obtained in the absence of SKF 38393. 5. These observations demonstrate that histamine H(3) receptor activation strongly inhibits the dopamine D(1) receptor-dependent release of [(3)H]-GABA from rat striatum; primarily through an interaction at the terminals of GABA neurones.

Histamine H1 receptor activation stimulates mitogenesis in human astrocytoma U373 MG cells.

In human astrocytoma U373 MG cells that express histamine H1 receptors (180 +/- 6 fmol/mg protein) but not H2 or H3 receptors, histamine stimulated mitogenesis as assessed by [3H]-thymidine incorporation (173 +/- 2% of basal; EC50, 2.5 +/- 0.4 microM). The effect of 100 microM histamine was fully blocked by the selective H1 antagonist mepyramine (1 microM) and was markedly reduced (93 +/- 4% inhibition) by the phospholipase C inhibitor U73122 (10 microM). The activator of protein kinase C (PKC) phorbol 12-tetradecanoyl-13-acetate (TPA, 100nM) stimulated [3H]-thymidine incorporation (270 +/- 8% of basal), and this response was not additive with that to 100 microM histamine. The incorporation of [3H]-thymidine induced by 100 microM histamine was partially reduced by the PKC inhibitor Ro 31-8220 (57 +/- 7% inhibition at 300 nM) and by the compound PD 098,059 (30 microM, 62 +/- 14% inhibition), an inhibitor of the mitogen-activated kinase (MAPK) kinases MEK1/MEK2. These results show that histamine H1 receptor activation stimulates the proliferation of human astrocytoma U373 MG cells. The action of histamine appears to be partially mediated by PKC stimulation and MAPK activation.

Survival of Vibrio cholerae O1 in ceviche and its reduction by heat pretreatment of raw ingredients.

The survival of Vibrio cholerae O1 serotypes Inaba and Ogawa was determined in ceviche prepared from inoculated ground fish. Ground mackerel purchased from a seafood distribution center was inoculated with V. cholerae and stored at 8 or 20 degrees C. Counts of V. cholerae decreased in 2.6 to 2.7 log10 CFU/g during 96 h of storage at 8 degrees C or 2.5 to 2.6 log10 CFU/g during 24 h at 20 degrees C. Survival studies indicated that serotype Inaba decreased its number following a linear or retarded trend, whereas serotype Ogawa followed an accelerated death trend. No effect of the initial level of inoculum was observed. Odor scores of ceviche indicated that this food became marginally acceptable within as little as 48 h of storage at 8 degrees C or 3 h at 20 degrees C and were related to total volatile nitrogen values but not to aerobic plate counts, pH, or coliform counts. A heat pretreatment that consisted of stirring 100 g of inoculated ground fish into 40 ml of boiling water produced an 8-log reduction of V. cholerae within 3 min without affecting the color, odor, or flavor of ceviche prepared with such pretreated fish. According to this study, V. cholerae present in contaminated ceviche will likely survive longer than the shelf life of this food. Preheating the ground raw fish used for preparing ceviche for 3 min should effectively eliminate V. cholerae O1, providing science-based conditions for implementing a critical control point if a hazard analysis critical control point plan were to be developed for preparation of ceviche.

L-type calcium channel activity regulates sodium channel levels in rat pituitary GH3 cells.

1. The effects of chronic pharmacological modulation of L-type Ca2+ channel activity on the cell surface expression of Na+ channels were examined in GH3 cells. 2. Prolonged inhibition (4-5 days) of L-channels with nimodipine caused a 50-60 % decrease in the peak amplitude of whole-cell Na+ currents recorded with the patch-clamp technique. On the contrary, prolonged exposure to the L-channel agonist Bay K 8644 induced an approximately 2.5-fold increase in peak Na+ current. In both cases, there were only minor changes in cell capacitance and no significant changes in Na+ channel gating properties. 3. Measurements of the specific binding of radiolabelled saxitoxin to intact cells showed that nimodipine treatment reduced the number of cell surface Na+ channels, whereas treatment with Bay K 8664 produced the opposite effect. The dual regulation of Na+ channel abundance explained the mentioned changes in Na+ current amplitude. 4. Plasma membrane Na+ channels had a half-life of approximately 17 h both in control cells and in cells treated with Bay K 8644, as estimated from the rate of decay of peak Na+ current after inhibition of protein synthesis with cycloheximide. Actinomycin D, an inhibitor of gene transcription, and also cycloheximide, occluded the stimulatory effect of Bay K 8644 on Na+ current density when measured over a 24 h period. 5. These findings indicate that the entry of Ca2+ through L-type channels influences in a positive way the number of functional Na+ channels in GH3 cells, and suggest that Ca2+ influx stimulates either Na+ channel gene expression or the expression of a regulatory protein that promotes translocation of pre-assembled Na+ channels into the plasma membrane.