RESUMO
Cytoskeletal F-actin associated with synaptic vesicles and granules plays an important role during Ca(2+)-mediated exocytosis. In the present work, we have used amperometry and confocal fluorescence to study the role of internal Ca(2+) in the rearrangement of F-actin (visualised with phalloidin-Alexa 546) during exocytosis in rat mast cells. The F-actin-depolymerising drug, latrunculin A, and the ryanodine receptor agonists ryanodine and caffeine that, per se did not induce exocytosis, enhanced the exocytotic responses elicited by compound 48/80 (C48/80). They also induced cortical actin depolymerisation in the presence or absence of external Ca(2+). Degranulation induced by C48/80 was accompanied by the formation of a cytoplasmic F-actin network. Depletion of internal Ca(2+) with cyclopiazonic acid inhibited latrunculin potentiation of C48/80-stimulated exocytosis and completely blocked the formation of the cytoplasmic F-actin network. This indicates that the mobilisation of Ca(2+) from ryanodine-sensitive intracellular stores plays an important role in the depolymerisation of the cortical F-actin barrier and possibly in the formation of the internal F-actin network during exocytotic activation of peritoneal mast cells.
Assuntos
Citoesqueleto de Actina/fisiologia , Cálcio/metabolismo , Exocitose/fisiologia , Mastócitos/metabolismo , Polímeros/metabolismo , Rianodina/farmacologia , Citoesqueleto de Actina/metabolismo , Actinas/efeitos dos fármacos , Actinas/metabolismo , Animais , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Cafeína/farmacologia , Degranulação Celular , Citoplasma/metabolismo , Exocitose/efeitos dos fármacos , Membranas Intracelulares/efeitos dos fármacos , Membranas Intracelulares/metabolismo , Masculino , Mastócitos/efeitos dos fármacos , Mastócitos/fisiologia , Peritônio/citologia , Ratos , Ratos Sprague-Dawley , Tiazolidinas/farmacologia , p-Metoxi-N-metilfenetilamina/farmacologiaRESUMO
Mast cells exocytotically release histamine/serotonin in response to different secretagogues. We have used substance P and compound 48/80 to study the Ca++ dependency of serotonin exocytosis from peritoneal mast cells using carbon fiber amperometric techniques. The exocytotic release pattern consists of a burst of events superimposed on a slow, transient, amperometric current baseline increase. Cellular re lease parameters (number, frequency and total charge of amperometric events) and individual event characteristics (charge integral, half width and peak amplitude) were similar for the two secretagogues used. Zero Ca++ conditions greatly reduced, without completely abolishing,cellular release parameters. Cyclopiazonic acid, an inhibitor of the endoplasmatic Ca++ ATPase, reduced the cellular exocytotic capacity and diminished the amplitude of individual exocytotic events more effectively than the 0 Ca++ condition. The cyclopiazonic acid effects occurred in the presence of external Ca++, indicating that this condition is not sufficient for maintaining full exocytotic capacity. The results confirm the importance of intracellular Ca++ for exocytotic activation. For the first time evidence is presented that the integrity of intracellular Ca++ pools determines the amplitude and frequency of individual exocytotic events. Saponin, a non-specific detergent, also induced quantal release similar to that obtained with substance P and compound 48/80. This release was not dependent on extracellular Ca++, but cyclopiazonic acid significantly reduced individual exocytotic release.
Assuntos
Cálcio/fisiologia , Exocitose/fisiologia , Mastócitos/fisiologia , Animais , Células Cultivadas , Transporte de Íons/fisiologia , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
Glutamate stimulated release of [3H]GABA was studied, during receptor desensitization block and its modulation by voltage gated Ca2+ channels, internal Ca2+ mobilization and GABA transport inhibitors from olfactory bulb slices. Under control conditions, glutamate and agonists induced release was strongly inhibited by Mg/0 Ca2+ Krebs and Cd2+ and partially inhibited by Ni2+ and nifedipine. Cyclothiazide, which blocks desensitization of glutamate receptors, potentiated glutamate, kainate, AMPA and quisqualate induced release. This effect was less dependent of entry of external Ca2+, but was inhibited by trifluoperazine and thapsigargin, inhibitors of Ca2+-calmodulin and endoplasmatic Ca2+ ATPase respectively. Nipecotic acid and NO-711, inhibitors of the GABA transporter, were also able to reduce cyclothiazide potentiated release induced by the 4 secretagogues. Under control conditions, glutamate stimulates the release of GABA in cooperation with VDCC. However, during receptor desensitization block, glutamate stimulated GABA release is mainly modulated through mechanisms dependent on internal Ca2+ mobilization and reversal of the GABA transporter.
Assuntos
Ácido Glutâmico/farmacologia , Neurônios/fisiologia , Bulbo Olfatório/fisiologia , Receptores de Glutamato/fisiologia , Ácido gama-Aminobutírico/metabolismo , Animais , Cálcio/farmacologia , Técnicas In Vitro , Cinética , Masculino , N-Metilaspartato/farmacologia , Neurônios/citologia , Neurônios/efeitos dos fármacos , Bulbo Olfatório/citologia , Cloreto de Potássio/farmacologia , Ácido Quisquálico/farmacologia , Ratos , Ratos Sprague-Dawley , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/farmacologiaRESUMO
Adult T-cell leukemia/lymphoma (ATL), a rare outcome of infection with human T-lymphotropic virus (HTLV-I), is endemic in central Brooklyn, which has a large Caribbean migrant population. Previous studies have suggested that HTLV-I prevalence in central Brooklyn may be similar to that recorded in the Caribbean islands. We established a pilot 1-year surveillance program to identify cases of ATL in 7 of 10 hospitals serving the residents of 18 zip codes of central Brooklyn with a combined population of 1,184,670. Of the 6,198 in-patient beds in the catchment area, approximately 83% were covered. Twelve incident cases of ATL were ascertained, all among persons of Afro-Caribbean descent, indicating an annual incidence in African-Americans in this community of approximately 3.2/100,000 person-years. Unexplained hypercalcemia was the most useful screening method, identifying 3 of 5 patients not referred for possible ATL by a local hematologist. The female:male ratio was 3:1. The age pattern was different from that reported in the Caribbean Basin and closer to the pattern seen in Japan. Our study supports evidence that HTLV-I infection and ATL are endemic in central Brooklyn and suggests that a more intensive surveillance program for this disease coupled with intervention efforts to reduce HTLV-I transmission are warranted.
Assuntos
Leucemia-Linfoma de Células T do Adulto/epidemiologia , Adulto , Idoso , Demografia , Feminino , Anticorpos Anti-HTLV-I/sangue , Humanos , Incidência , Jamaica/etnologia , Leucemia-Linfoma de Células T do Adulto/sangue , Leucemia-Linfoma de Células T do Adulto/imunologia , Masculino , Pessoa de Meia-Idade , Cidade de Nova Iorque/epidemiologia , Projetos Piloto , Vigilância da População , Fatores de Risco , Trinidad e Tobago/etnologiaRESUMO
Much evidence points to a significant involvement of the classical neurotransmitters 5-HT and DA in affective disorders with possible changes in different structures of the CNS and also at different levels of the signal transduction chain, i.e., receptor, synthesis, uptake or release. We have used chronic isolated housing as an animal model of depression. These isolated rats enabled the study of KCl-induced release of 5-HT and DA from nucleus accumbens, prefrontal cortex and hippocampal slices. The following questions were addressed: first, if there is a change in the depolarization dependent release of DA and 5-HT from these CNS structures, and second, if the release is through the classical exocytotic mechanism. A significant increase in KCl stimulated release of 5-HT was observed in chronically isolated animals when compared to controls. 5-HT release was completely abolished from controls or isolated animals, when slices were incubated with Krebs containing zero Ca2+/10 mM Mg2+, the inorganic Ca2+ channel blockers, Cd2+ or Ni2+ and the calmodulin inhibitor, trifluoperazine. The organic Ca2+ channel blockers nifedipine and D-600 were less effective in inhibiting the stimulated 5-HT release. KCl stimulated DA release was only significantly increased from hippocampus slices, of isolated, but not control animals. This release was also highly Ca2+-dependent. The basal release of DA and 5-HT was similar in control and isolated animals and was not affected by the Ca2+ channel antagonists. The results suggest that extracellular Ca2+-dependent release of 5-HT and, to a lesser degree, of DA, is increased in this chronic animal model of depression in several CNS structures.
Assuntos
Cálcio/metabolismo , Sistema Nervoso Central/metabolismo , Dopamina/metabolismo , Serotonina/metabolismo , Isolamento Social , Animais , Cálcio/farmacologia , Sistema Nervoso Central/efeitos dos fármacos , Depressão/metabolismo , Exocitose , Hipocampo/efeitos dos fármacos , Hipocampo/fisiologia , Masculino , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Núcleo Accumbens/efeitos dos fármacos , Núcleo Accumbens/fisiologia , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/fisiologia , Ratos , Ratos Sprague-DawleyRESUMO
Nasal T-lymphocyte/natural killer cell lymphomas (nT/NKLs) are a distinct group of neoplasms highly associated with Epstein-Barr virus (EBV), with a high prevalence in Asia but rare in Western countries. Recent studies indicate that these neoplasms are of cytotoxic T- or NK-cell derivation. Previous studies identifying a characteristic 30-base pair deletion within the 3' end of latent membrane protein-1 (del-LMP-1) in other EBV-associated lymphomas suggested a pathogenetic role for del-LMP-1 in those neoplasms. We examined 23 cases of nT/NKL from Mexico for expression of the cytolytic granular proteins TIA-1 and perforin (PRF), and for the presence of EBV by in situ hybridization (ISH). Polymerase chain reaction was performed to identify the EBV (EBNA-2) strain type and the status of the LMP-1 gene (del-LMP-1). Controls consisted of 11 sinonasal B-cell lymphomas (nBLs) and 30 reactive tonsils (RTs) from healthy Mexican individuals. The nT/NKLs expressed TIA-1 in 21 (91%) of 23 cases and PRF in 15 (65%) of 23 cases. In contrast, all of the nBLs were negative for TIA-1 and PRF. Twenty-two (96%) of 23 nT/NKLs were positive for EBV by ISH. In contrast, only 2 (18%) of 11 nBLs were positive for EBV by ISH. EBV strain Type A was identified in 21 (91%) of 23 cases, whereas strain Type B was present in 2 (9%) of the 23 nT/NKLs. A similar percentage (80%) of Type A was noted in 12 of the 15 RTs. del-LMP-1 was detected in 6 (26%) of 23 nT/NKLs, comprising 4 cases of Type A and 2 of Type B. del-LMP-1 was detected in 9 (45%) of 20 RTs. Our results indicated that TIA-1 and PRF were sensitive markers of nT/NKL. The presence of del-LMP-1 in comparable frequencies in the RTs and nT/NKLs suggested to us that this genotype was common in the Mexican population and argued against a definite pathogenetic role for del-LMP-1 in nT/NKL.
Assuntos
Deleção de Genes , Herpesvirus Humano 4/genética , Linfoma de Células T/metabolismo , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana/metabolismo , Neoplasias Nasais/metabolismo , Proteínas , Proteínas de Ligação a RNA/metabolismo , Proteínas da Matriz Viral/genética , Adolescente , Adulto , Idoso , Feminino , Humanos , Imuno-Histoquímica , Hibridização In Situ , Células Matadoras Naturais/patologia , Linfoma de Células T/genética , Linfoma de Células T/patologia , Linfoma de Células T/virologia , Masculino , México , Pessoa de Meia-Idade , Neoplasias Nasais/genética , Neoplasias Nasais/virologia , Perforina , Proteínas de Ligação a Poli(A) , Reação em Cadeia da Polimerase , Proteínas Citotóxicas Formadoras de Poros , Antígeno-1 Intracelular de Células TRESUMO
BACKGROUND: To clarify which types of cancer result from AIDS, we compared the cancer experiences of people with AIDS with those of the general population by matching population-based cancer and AIDS registries in the USA and Puerto Rico. METHODS: We used a probabilistic matching algorithm to compare names, birth dates, and, where available, social-security numbers of 98,336 people with AIDS and 1,125,098 people with cancer aged less than 70 years. We defined AIDS-related cancers as those with both significantly raised incidence post-AIDS and increasing prevalence from 5 years pre-AIDS to 2 years post-AIDS. FINDINGS: Among people with AIDS, we found 7028 cases of Kaposi's sarcoma (KS), 1793 of non-Hodgkin lymphoma (NHL), and 712 other cases of histologically defined cancer. Incidence rates among people with AIDS were increased 310-fold for KS, 113-fold for NHL, and 1.9-fold (95% CI 1.5-2.3) for other cancers. Of 38 malignant disorders other than KS and NHL, only angiosarcoma (36.7-fold), Hodgkin's disease (7.6-fold), multiple myeloma (4.5-fold), brain cancer (3.5-fold), and seminoma (2.9-fold) were raised and increasing significantly (p<0.02) from the pre-AIDS to the post-AIDS period. INTERPRETATION: Interpretation is complicated by screening and shared risk factors, such as sexual behaviour and cigarette smoking. However, our data indicate that AIDS leads to a significantly increased risk of Hodgkin's disease, multiple myeloma, brain cancer, and seminoma. Immunological failure to control herpes or other viral infections may contribute to these malignant diseases.
Assuntos
Síndrome da Imunodeficiência Adquirida/complicações , Linfoma não Hodgkin/epidemiologia , Neoplasias/epidemiologia , Sarcoma de Kaposi/epidemiologia , Adulto , Algoritmos , Feminino , Humanos , Incidência , Linfoma não Hodgkin/virologia , Masculino , Pessoa de Meia-Idade , Neoplasias/virologia , Vigilância da População , Prevalência , Porto Rico/epidemiologia , Sistema de Registros , Risco , Fatores de Risco , Sarcoma de Kaposi/virologia , Estados Unidos/epidemiologiaRESUMO
Plasma free amino acids were determined in the plasma of severely malnourished children under two years of age. A total of thirty-one patients and eleven controls were evaluated: seventeen cases of kwashiorkor, eight cases of marasmus, and six cases of marasmic-kwashiorkor. Fasting plasma samples were taken in the morning on the day of admission. Fasting plasma samples were also taken from nine patients at discharge after two months in the hospital where they received a balanced diet as treatment. A partial reversal of the signs of malnutrition was observed at discharge. In the whole group of patients ad admission, lower concentrations of tyrosine, methionine, tryptophan, and leucine and higher concentrations of aspartate, glutamate, and taurine were observed compared to controls. Taurine continued to be elevated in the malnourished group at the time of discharge. Marasmic children, as compared to controls, had high aspartate and low tryptophan levels, but taurine levels were not significantly different from controls. Kwashiorkor patients had low tyrosine, methionine, tryptophan, and lysine, and significantly higher taurine plasma levels. The elevated concentration of taurine might be the result of a redistribution of this amino acid to provide specific tissues with the required amount for development.
Assuntos
Kwashiorkor/sangue , Distúrbios Nutricionais/sangue , Taurina/sangue , Aminoácidos/sangue , Feminino , Humanos , Lactente , MasculinoRESUMO
There are many reports documenting modifications of different plasma components in undenutrition, including the protein-calorie (marasmus) or the protein deficiency (kwashiorkor) subtypes. However, there is no detailed study on the effect of undernutrition on plasma amino acid pattern during the first two years of life, a critical period of biological development in humans. The plasma concentrations of 19 amino acids were analysed in 32 children under two years of age presenting severe undernutrition: marasmus, kwashiorkor or mixed picture. The subjects were admitted to the hospital as inpatients and received a balanced diet as the only treatment. Samples of venous blood were taken from nine patients at discharge and plasma amino acid profile was compared with the preadmission profile. A healthy control group included 11 children visiting the hospital for regular pediatric examination. At the time of admission the amino acid levels of tyrosine, tryptophan and leucine were significantly lower in the undernourished group of children compared to controls. On the other hand, levels of aspartate were higher in the children with malnutrition. These changes in amino acids were not present at the time of discharge from hospital after diet therapy. Taurine concentration was higher in undernourished children and remained high at the time of discharge. Compared with the control group, marasmic children showed increases in plasma aspartic acid and serine, and decrease in trypthophan. Kwashiorkor children had lower levels of tyrosine, trypthophan and leucine, but higher levels of taurine. The elevation of taurine was not corrected by diet therapy.
RESUMO
The effect of L-cysteine sulfinic acid (CSA) and L-homocysteic acid (HCA) on the release of tritiated gamma-amino butyric acid ([3H]GABA), from the external plexiform layer (EPL) of the rat olfactory bulb, was compared with that of glutamate. These amino acids induced release of GABA was strongly inhibited by the glutamate uptake blocker, pyrrolidine-2,4-dicarboxylate (2,4,PDC) (50 microM), while it was not inhibited by the specific GABA uptake blockers nipecotic acid (0.5 mM) or NO-711 (5 microM). Only the HCA induced GABA release was 60% inhibited by beta-alanine (0.5 mM), a glial GABA uptake blocker and 78% by the NMDA receptor antagonist 2-amino-5-phosphonopentanoic acid (AP-5) (100 microM). The non-NMDA receptor antagonists 6-cyano-2,3-dihydroxy-7-nitro-quinoxaline (CNQX) up to 500 microM had no effect on HCA or CSA stimulated GABA release. These results bring evidence for an excitatory role of HCA and CSA together with glutamate on GABAergic neuronal or glial elements, in the olfactory bulb. This role could be mediated through the reversal of the glutamate or/and the glial GABA transporter and through the activation of a NMDA type receptor.