Metástase de seminoma em região orbital em cão - relato de caso / Metastatic seminoma in the orbital region in a dog - case report

O seminoma é uma neoformação testicular originária de células germinativas de ocorrência comum em cães, com maior prevalência em animais senis. Em geral, o comportamento biológico do seminoma canino é benigno. Relata-se neste trabalho um caso de seminoma com metástase em região orbital em um cão com 14 anos de idade. O animal foi atendido com queixa de aumento de volume em órbita esquerda, com posterior detecção de nódulo testicular. A punção aspirativa por agulha fina da massa orbital sugeriu tratar-se de linfoma de alto grau, contudo o diagnóstico definitivo de seminoma difuso foi estabelecido pela avaliação histopatológica, a qual revelou tratar-se de neoplasia maligna pouco diferenciada, sendo o diagnóstico de seminoma difuso confirmado pelo exame imunoistoquímico. Relatos de seminomas metastáticos em cães são incomuns. Objetivou-se com este trabalho relatar um caso de seminoma anaplásico difuso em cão cujo foco principal de metástase ocorreu em região orbital, além de descrever e discutir as dificuldades diagnósticas encontradas.(AU)

Seminoma is a testicular neoformation originating from germ cells, commonly occurring in dogs. With higher prevalence in senile animals, the biological behavior of canine seminomas generally benign. This case reports seminoma with mestastasis in the orbital region in a 14-year-old dog. The animal was treated with a complaint of increased volume in the left orbit, and later a nodule in the testicle was discovered. Fine-needle aspiration of the orbit mass initially indicated a high-grade lymphoma. The definitive diagnosis of diffused seminoma was established by histopathological examination, resulting in poorly differentiated malignant neoplasia. Finally, the diagnosis was confirmed through immunohistochemistry, being the result compatible with diffused seminoma. Metastatic seminomas reported in dogs are quite uncommon. In this work we report a case of diffused anaplastic seminoma in dogs, where the main focus of metastasis was observed in the orbital region, and we also describe and discuss the difficulties encountered in the diagnostic.(AU)

MODERN APPROACHES IN MANAGEMENT OF CHILDREN WITH CHRONIC HEPATITIS B IN REMISSION OF ACUTE LYMPHOBLASTIC LEUKEMIA.

The aim of the study is to assess the effectivity of the drug «Betargin¼ in complex management of patients with chronic hepatitis B (CHB) in remission of acute lymphoblastic leukemia (ALL). The research had shown the results of treatment of 41 children with CHB in remission of ALL aged from 3 to 17 years old, who were on dispensary observation in Vinnytsia Regional Children's Clinical Infectious Diseases Hospital during 2013-2017 years. Patients were devided into the following groups: the comparison group (group A), which included 18 children with CHB in remission of ALL, who received basis therapy; the main group (group B) which consisted of 23 patients with CHB in remission of ALL, who got betaine arginine complex («Betargin¼) in addition to basis therapy. The control group was formed out of 30 healthy children. Determination of effectivity of the proposed treatment regimen was performed by studying the indicators of cholestasis, cytolysis, hepatocellular insufficiency, and lipid metabolism. To assess the liver's fibrosis level and necroinflammatory activity we used the determination of the level of plasma osteopontin in the serum using the enzyme-linked immunosorbent assay (ELISA) method: Human Osteopontin Quantikine (RDD systems, Dos Too, Minneapolis, MS, USA). The verification of the diagnosis of CHB was based on the detection of specific markers of HBV-infection in blood using ELISA and PCR analysis. During our scientific research we established that using betaine arginine complex in management of CHB in remission of ALL led to considerable improvement of children's general condition, namely due to reducing (p<0,05) the incidence of asthenovegetative (8.6% against 33.3% in the comparison group), dyspeptic (13.1% against 38.8%) as well as pain syndromes (4.3% against 11%) and hepatomegaly (13.1% against 38.8%). The activity of ALT in the main group was in 1.6 times less (p<0,05) than in comparison group at the end of the course of treatment. «Betargin¼ has an antifibrotic effect which is confirmed by a decrease in the level of plasma osteopontin up to 104,92 ng/ml against 178,15 ng/ml in the comparison group (p<0,05).

PREDICTIVE VALUE OF SERUM IL-17A AND IP-10 FOR EVALUATION OF LIVER FIBROSIS PROGRESSION IN PATIENTS WITH HBV/HIV CO-INFECTION.

The problem of HBV and HCV infections in addition to the HIV-infection in sub-Saharan African countries remains important due to the high prevalence and mortality after fast progressing fibrogenesis and development of hepatocellular carcinoma. Despite of the large number of investigations on diagnostics and prediction of the disease course, the exact role of the proinflammatory influence of IP-10 and IL-17A on the fibrogenesis during HIV/HBV-co-infection is still unknown. The aim of the study was to investigate IP-10 and IL-17A concentration in blood serum among HIV/HBV patients to consider their potential role in improvement of diagnostics of liver fibrosis progression. 53 HIV/HBV patients of Lewanika General Hospital (West Zambia) and 21 healthy blood donors were checked for serological markers, liver biopsy and IP-10, IL-17A in blood serum. The obtained results were analyzed by statistical package SPSS 12.0. Mean IP-10 was 753,6 pg/ml among HIV/HBV co-infected patients with F3-4 and it was reliably higher than in F1-2 patients and healthy responders (р=0,005). This group had also higher level of IL-17A (37,54 pg/ml) than comparison groups (р=0,032). We found out strong correlation between increasing IP-10 (r=0,6), IL-17A (r=0,52) and fibrotic severity (р<0,05). High IP-10, IL-17A amount increases the risk of F3-4 formation in HIV/HBV patients.

Dichotomy of Local Th1- and Systemic Th2/Th3-Dependent Types of Immune Response in Rheumatoid Arthritis.

Biomarkers of activity of rheumatoid arthritis were analyzed in the blood serum and synovial fluid of affected joints in 84 patients. Significant differences between the serum and synovial fluid levels were revealed for 10 of 17 analyzed biomarkers; the levels of IgM and proinflammatory cytokines TNFα, IL-1ß, IFNγ, and IL-6 were higher in the synovial fluid. The concentration of IL-10 in the synovial fluid was also elevated. In the peripheral blood, the content of antinuclear antibodies, circulating immune complexes, and cytokines IL-4 and TGF-ß was elevated. These findings attest to the development of local Th1 type immune response in affected joints paralleled by compensatory elevation of immunosuppressive cytokine IL-10 and systemic Th2/Th3 type immune response (judging from peripheral blood parameters) in patients with rheumatoid arthritis.

[PECULIARITIES OF THE PREVALENCE OF POLYMORPHISM (C-589T) OF THE IL-4 GENE AND ITS RELATIONSHIP WITH SERUM IL-4 LEVEL IN PATIENTS WITH ACUTE BRUCELLOSIS IN THE REPUBLIC OF AZERBAIJAN].

The aim of the study was to determine the frequency of polymorphism of IL-4 (C-589T) in patients with acute brucellosis in the Republic of Azerbaijan and to establish its correlation with serum IL-4 levels. One hundred seventy eight patients with clinical symptoms of brucellosis were examined. According to the criteria for inclusion in a study of 178 patients, only 120 persons- (the main group) - fully met all criteria. The control group consisted of 30 practically healthy persons. Also, all patients in both groups were tested for IL-4 (C-589T) polymorphism and level of interleukin-4 (IL-4). It has been established that carriers of the allele T of the polymorphic (C-589T) IL-4 gene are at increased risk for brucellosis (OR=4.26, 95% CI [2.01-9.05]], whereas in the case of carrier allele C, on the contrary, is a reduced risk of developing brucellosis. The combination of genotypes C/T + T/T among patients with brucellosis was determined 3.1 times more than in practically healthy individuals (OR=10.31, 95% CI [1.55-19.18], χ2=29.21, p<0.0001). It was found that among the carriers of the C/C genotype, IL-4 level was 1.44 higher in brucellosis than in T/T genotype carriers and 1.2 times higher in comparison with the C/T genotype. Among carriers of the C/T genotype, there is a significantly increased risk of brucellosis (χ2=29.73; p=4.0E-7; OR=9.63; 95% CI [3.43-27.03] while cariousness of the homozygous genotype C/С, on the contrary, has a protective effect on the development of brucellosis (OR=0.10, 95% CI 0.04-0.25).

Seasonal exposure of carbon dioxide ice on the nucleus of comet 67P/Churyumov-Gerasimenko.

Carbon dioxide (CO2) is one of the most abundant species in cometary nuclei, but because of its high volatility, CO2 ice is generally only found beneath the surface. We report the infrared spectroscopic identification of a CO2 ice-rich surface area located in the Anhur region of comet 67P/Churyumov-Gerasimenko. Spectral modeling shows that about 0.1% of the 80- by 60-meter area is CO2 ice. This exposed ice was observed a short time after the comet exited local winter; following the increased illumination, the CO2 ice completely disappeared over about 3 weeks. We estimate the mass of the sublimated CO2 ice and the depth of the eroded surface layer. We interpret the presence of CO2 ice as the result of the extreme seasonal changes induced by the rotation and orbit of the comet.

Exposed water ice on the nucleus of comet 67P/Churyumov-Gerasimenko.

Although water vapour is the main species observed in the coma of comet 67P/Churyumov-Gerasimenko and water is the major constituent of cometary nuclei, limited evidence for exposed water-ice regions on the surface of the nucleus has been found so far. The absence of large regions of exposed water ice seems a common finding on the surfaces of many of the comets observed so far. The nucleus of 67P/Churyumov-Gerasimenko appears to be fairly uniformly coated with dark, dehydrated, refractory and organic-rich material. Here we report the identification at infrared wavelengths of water ice on two debris falls in the Imhotep region of the nucleus. The ice has been exposed on the walls of elevated structures and at the base of the walls. A quantitative derivation of the abundance of ice in these regions indicates the presence of millimetre-sized pure water-ice grains, considerably larger than in all previous observations. Although micrometre-sized water-ice grains are the usual result of vapour recondensation in ice-free layers, the occurrence of millimetre-sized grains of pure ice as observed in the Imhotep debris falls is best explained by grain growth by vapour diffusion in ice-rich layers, or by sintering. As a consequence of these processes, the nucleus can develop an extended and complex coating in which the outer dehydrated crust is superimposed on layers enriched in water ice. The stratigraphy observed on 67P/Churyumov-Gerasimenko is therefore the result of evolutionary processes affecting the uppermost metres of the nucleus and does not necessarily require a global layering to have occurred at the time of the comet's formation.

Hospital variation in maternal complications following caesarean delivery in the United States: 2006-2012.

OBJECTIVE: To assess hospital variability in and patient and hospital factors associated with caesarean delivery (CD) complications. STUDY DESIGN: Population-based cohort. SETTING: United States delivery admissions. POPULATION: Women who underwent a CD between 2006 and 2012. METHODS: Hospital-specific random-effects log-linear regression models were developed to account for patient, obstetric, and hospital risk factors related to a composite complication outcome including infection, haemorrhage, surgical complications and prolonged hospital stay. Between-hospital variability in rates of CD complications was also estimated. MAIN OUTCOME MEASURE: Composite complication rate. RESULTS: Among 1 339 397 women who underwent CD in 457 hospitals, 6.4% (n = 85 838) experienced a complication. The most frequent complications were haemorrhage, transfusion, length of stay >7 days, and endometritis. Complications were strongly associated with the presence of obstetric factors and pre-existing medical conditions. Complication rates were 54% higher among black (8.8%) than white (5.7%) women (P < 0.001), and were more common in teaching (8.1%) than non-teaching (5.4%) hospitals (P < 0.001). In an adjusted model, the mean complication rate was 6.7%. A small proportion of hospitals (4.8%) had a complication rate greater than twice the mean (≥13.4%). Complications were strongly associated with the presence of obstetrical factors and pre-existing medical conditions. CONCLUSIONS: CD complication rates are strongly associated with patient and obstetric factors. While CD complication rates may be a quality metric of limited utility given the low rate of complications across most hospitals, a small number of hospitals demonstrate particularly high rates of complications. Review of CD complication rates may be an important aspect of quality assurance processes for these centres. TWEETABLE ABSTRACT: A small number of hospitals demonstrate particularly high rates of caesarean complications.

IFNL4 polymorphism as a predictor of chronic hepatitis C treatment efficiency in Ukrainian patients.

The aim of this study was to examine association between IFNL4 gene ss469415590 and treatment efficiency in group of Ukrainian PEG-interferon/ribavirin-treated chronic hepatitis C patients. Study group consisted of 92 unrelated hepatitis C virus genotype 1 mono-infected patients: case group - 29 patients with late or absent virological response; control group - 63 patients with sustained virological response. Study material was genomic DNA. Genotyping was performed using amplification-refractory mutation system PCR. Statistical analysis was performed using GenePop and OpenEpi statistical packages. Obtained results show that ss469415590 ΔG/ΔG genotype is associated with poor virological response (OR = 3.62; CI 95%: 1.12-11.67) in PEG-interferon/ribavirin-treated chronic hepatitis C patients from Ukraine.

IFNL4 polymorphism as a predictor of chronic hepatitis C treatment efficiency in Ukrainian patients.

The aim of this study was to examine association between IFNL4 gene ss469415590 and treatment efficiency in group of Ukrainian PEG-interferon/ribavirin-treated chronic hepatitis C patients. Study group consisted of 92 unrelated hepatitis C virus genotype 1 mono-infected patients: case group-29 patients with late or absent virological response; control group-63 patients with sustained virological response. Study material was genomic DNA. Genotyping was performed using amplification-refractory mutation system PCR. Statistical analysis was performed using GenePop and OpenEpi statistical packages. Obtained results show that ss469415590 ΔG/ΔG genotype is associated with poor virological response (OR = 3.62; CI 95%: 1.12-11.67) in PEG-interferon/ribavirin-treated chronic hepatitis C patients from Ukraine.

ITPA gene variant may protect against anemia induced during pegylated interferon alfa and ribavirin combination treatment in Ukrainian patients with chronic hepatitis C.

The aim of this study was to clarify the association between the inosine triphosphate pyrophosphatase (ITPA) gene variants and PEG-IFNalpha/RBV combination treatment induced anemia in chronic hepatitis C (CHC) Ukrainian patients. The data were collected from 80 CHC patients with HCV genotype 1 infection. All study participants received standard doses of PEG-IFNalpha and RBV According to the Hb level changes patients were distributed into: case group--42 patients with combination treatment induced anemia, and control group--38 patients with no signs of anemia. Genotyping for ITPA gene rs1127354 and rs7270101 variants was performed using PCR followed by RFLP assay. Fisher's exact test was used to estimate the difference in genotype and allelic distribution. Distribution of rs 7270101 genotypes was not significantly different between groups of CHC patients with RB Vinduced anemia and without it. The frequency of rs1127354 A allele carriers was significantly higher (P < < 0,05) in group of CHC patients without anemia (23.7%) comparing to the group ofpatients with anemia (7.3%). The respective allele frequency in control group (13.2%) was almost 3-fold higher (P < 0,05) comparing to the case group (4.9%). Significant association of ITPA gene rs1127354 with protection against RB V-induced hemolytic anemia was found in Ukrainian patients with CHC infection. Rs1127354 variant may assist as a pharmacogenetic marker in HCV antiviral therapy correction for side effect avoidance..

Molecular Evidence for Convergence and Parallelism in Evolution of Complex Brains of Cephalopod Molluscs: Insights from Visual Systems.

Coleoid cephalopods show remarkable evolutionary convergence with vertebrates in their neural organization, including (1) eyes and visual system with optic lobes, (2) specialized parts of the brain controlling learning and memory, such as vertical lobes, and (3) unique vasculature supporting such complexity of the central nervous system. We performed deep sequencing of eye transcriptomes of pygmy squids (Idiosepius paradoxus) and chambered nautiluses (Nautilus pompilius) to decipher the molecular basis of convergent evolution in cephalopods. RNA-seq was complemented by in situ hybridization to localize the expression of selected genes. We found three types of genomic innovations in the evolution of complex brains: (1) recruitment of novel genes into morphogenetic pathways, (2) recombination of various coding and regulatory regions of different genes, often called "evolutionary tinkering" or "co-option", and (3) duplication and divergence of genes. Massive recruitment of novel genes occurred in the evolution of the "camera" eye from nautilus' "pinhole" eye. We also showed that the type-2 co-option of transcription factors played important roles in the evolution of the lens and visual neurons. In summary, the cephalopod convergent morphological evolution of the camera eyes was driven by a mosaic of all types of gene recruitments. In addition, our analysis revealed unexpected variations of squids' opsins, retinochromes, and arrestins, providing more detailed information, valuable for further research on intra-ocular and extra-ocular photoreception of the cephalopods.

Cometary science. The organic-rich surface of comet 67P/Churyumov-Gerasimenko as seen by VIRTIS/Rosetta.

The VIRTIS (Visible, Infrared and Thermal Imaging Spectrometer) instrument on board the Rosetta spacecraft has provided evidence of carbon-bearing compounds on the nucleus of the comet 67P/Churyumov-Gerasimenko. The very low reflectance of the nucleus (normal albedo of 0.060 ± 0.003 at 0.55 micrometers), the spectral slopes in visible and infrared ranges (5 to 25 and 1.5 to 5% kÅ(-1)), and the broad absorption feature in the 2.9-to-3.6-micrometer range present across the entire illuminated surface are compatible with opaque minerals associated with nonvolatile organic macromolecular materials: a complex mixture of various types of carbon-hydrogen and/or oxygen-hydrogen chemical groups, with little contribution of nitrogen-hydrogen groups. In active areas, the changes in spectral slope and absorption feature width may suggest small amounts of water-ice. However, no ice-rich patches are observed, indicating a generally dehydrated nature for the surface currently illuminated by the Sun.

Estudo retrospectivo de exames citológicos realizados em um Hospital Veterinário Escola em um período de cinco anos / Retrospective study on the cytological exams in a Veterinary Technic Hospital in a five year period

Avaliaram-se os resultados de exames citológicos realizados em seis anos e determinou-se o tipo de distúrbio (inflamatório, infeccioso, proliferativo) mais comum. Aspectos epidemiológicos, como espécie, raça, sexo e idade, foram levados em consideração. Foram realizadas 270 avaliações citológicas e destas a prevalência foi de neoplasmas (53%). A espécie canina foi a mais ocorrente, com 92% dos casos. As fêmeas somaram 53% do total. A idade variou de um a 17 anos, sendo o intervalo de seis a 10 anos mais ocorrente (40% dos casos). As neoplasias de células redondas foram as mais prevalentes, seguidas das neoformações mamárias.

The cytological exam is a practical diagnostic aplication which allows the detection of inflammatory, proliferative and infectious disturbances. In the present study, the results of cytological exams during six years were evaluated, determining the most common type of disorder (inflammatory, infectious, proliferative). Epidemiological aspects such as species, breed, sex and age were taken into account. 270 reviews were evaluated and the prevalence was neoplasms (53%). The canine specie was the most observed, with 92% of cases. Females totaled 53%. The age ranged from one to 17 years and the interval of six to 10 years was most observed (40% of cases). The round cell neoplasms were the most prevalent, followed by breast neoformations.

Phylogenomics meets neuroscience: how many times might complex brains have evolved?

The origin of complex centralized brains is one of the major evolutionary transitions in the history of animals. Monophyly (i.e. presence of a centralized nervous system in urbilateria) vs polyphyly (i.e. multiple origins by parallel centralization of nervous systems within several lineages) are two historically conflicting scenarios to explain such transitions. However, recent phylogenomic and cladistic analysis suggests that complex brains may have independently evolved at least 9 times within different animal lineages. Indeed, even within the phylum Mollusca cephalization might have occurred at least 5 times. Emerging molecular data further suggest that at the genomic level such transitions might have been achieved by changes in expression of just a few transcriptional factors - not surprising since such events might happen multiple times over 700 million years of animal evolution. Both cladistic and genomic analyses also imply that neurons themselves evolved more than once. Ancestral polarized secretory cells were likely involved in coordination of ciliated locomotion in early animals, and these cells can be considered as evolutionary precursors of neurons within different lineages. Under this scenario, the origins of neurons can be linked to adaptations to stress/injury factors in the form of integrated regeneration-type cellular response with secretory signaling peptides as early neurotransmitters. To further reconstruct the parallel evolution of nervous systems genomic approaches are essential to probe enigmatic neurons of basal metazoans, selected lophotrochozoans (e.g. phoronids, brachiopods) and deuterostomes.

Controlled release recombinant human interferon-α2b for treating patients with chronic hepatitis C genotype 1: a phase 2a clinical trial.

Better convenience and tolerability and sustained therapeutic concentrations might improve interferon (IFN) treatment for chronic hepatitis C virus (HCV) infection. In an open-label, randomized study, controlled release free (chemically unmodified) recombinant human IFN-α(2b) in poly(ether-ester) microspheres (CR-rhIFN-α(2b)), was injected at doses of 160, 320, 480 or 640 µg every 2 weeks for 12 weeks with concomitant weight-based oral ribavirin in 32 treatment-naïve patients with chronic HCV genotype 1. Treatment was well tolerated, with 31 patients (97%) successfully completing the study. Full doses of CR-rhIFN-α(2b) were administered on 96% of scheduled occasions. Flu-like symptoms were generally mild and brief. Injection site reactions developed in 13 patients (41%), and neutropenia occurred in six of eight patients receiving 640 µg. In the 320, 480 and 640 µg groups, 62-75% of patients achieved a ≥2 log(10) HCV RNA reduction by 4 weeks and 88-100% by 12 weeks. For those groups, the pooled median time to ≥2 log(10) reduction was 11 days (95% confidence interval, 7-35 days). In those groups, viral reduction below the limit of detection was accomplished in 25% of patients by 4 weeks and in 62% by 12 weeks. The 160-µg dose was less potent. After CR-rhIFN-α(2b) injection, stable plateau levels of serum IFN-α(2b) were generally reached within 72 h. Treatment-emergent neutralizing antibodies to IFN-α(2b) were observed in one patient. No antibodies to host plant proteins were detected. CR-rhIFN-α(2b) with ribavirin cotherapy was well tolerated and displayed potent early antiviral activity in patients with chronic HCV genotype 1.

5-HT and 5-HT-SO4, but not tryptophan or 5-HIAA levels in single feeding neurons track animal hunger state.

Serotonin (5-HT) is an intrinsic modulator of neural network excitation states in gastropod molluscs. 5-HT and related indole metabolites were measured in single, well-characterized serotonergic neurons of the feeding motor network of the predatory sea-slug Pleurobranchaea californica. Indole amounts were compared between paired hungry and satiated animals. Levels of 5-HT and its metabolite 5-HT-SO4 in the metacerebral giant neurons were observed in amounts approximately four-fold and two-fold, respectively, below unfed partners 24 h after a satiating meal. Intracellular levels of 5-hydroxyindole acetic acid and of free tryptophan did not differ significantly with hunger state. These data demonstrate that neurotransmitter levels and their metabolites can vary in goal-directed neural networks in a manner that follows internal state.

Titanium elastic nailing of fractures of the femur in children. Predictors of complications and poor outcome.

Between 1996 and 2003 six institutions in the United States and France contributed a consecutive series of 234 fractures of the femur in 229 children which were treated by titanium elastic nailing. Minor or major complications occurred in 80 fractures. Full information was available concerning 230 fractures, of which the outcome was excellent in 150 (65%), satisfactory in 57 (25%), and poor in 23 (10%). Poor outcomes were due to leg-length discrepancy in five fractures, unacceptable angulation in 17, and failure of fixation in one. There was a statistically significant relationship (p = 0.003) between age and outcome, and the odds ratio for poor outcome was 3.86 for children aged 11 years and older compared with those below this age. The difference between the weight of children with a poor outcome and those with an excellent or satisfactory outcome was statistically significant (54 kg vs 39 kg; p = 0.003). A poor outcome was five times more likely in children who weighed more than 49 kg.

Modulatory action of RFamide-related peptides on acid-sensing ionic channels is pH dependent: the role of arginine.

Acid-sensing ionic channels (ASICs) are involved in such functions of the sensory nervous system as mechanoreception, nociception and perception of acid taste. Phe-Met-Arg-Phe amide-related (FMRFa-related) peptides in micro m concentrations slow down the rate of ASICs desensitization. Here we report that this effect is strongly pH dependent: the lower the pH used to activate ASICs, the larger is the modulatory effect of Arg-Phe amide-related (RFa-related) peptides. Pre-application of the peptides results in a change to the desensitization kinetics of the ASICs-operated current from monoexponential to biexponential: the fast component retains the control kinetics, whereas the slow one is induced by the peptide. The lower the pH, the larger is the slow component, whereas there is practically no modulation at pH 6.6. Phe-Met-Val-Phe amide (FMVFa), which has neutral valine instead of arginine, similarly modulates the kinetics of ASICs, but does not reveal pH dependence of this action. Thus, positively charged arginine regulates the access of the RFa-related peptides to the modulatory site. We suggest that the pH dependence of the modulatory action of RFa-related peptides can be associated with the interaction of a positively charged arginine with histidine residues in the molecule of ASIC.

Alkalinization by chloride/bicarbonate pathway in larval mosquito midgut.

The midgut of mosquito larvae maintains a specific lumen alkalinization profile with large longitudinal gradients (pH approximately 3 units*mm(-1)) in which an extremely alkaline (pH approximately 11) anterior midgut lies between near-neutral posterior midgut and gastric cecum (pH 7-8). A plasma membrane H(+) V-ATPase energizes this alkalinization but the ion carriers involved are unknown. Capillary zone electrophoresis of body samples with outlet conductivity detection showed a specific transepithelial distribution of chloride and bicarbonate/carbonate ions, with high concentrations of both anions in the midgut tissue: 68.3 +/- 5.64 and 50.8 +/- 4.21 mM, respectively. Chloride was higher in the hemolymph, 57.6 +/- 7.84, than in the lumen, 3.51 +/- 2.58, whereas bicarbonate was higher in the lumen, 58.1 +/- 7.34, than the hemolymph, 3.96 +/- 2.89. Time-lapse video assays of pH profiles in vivo revealed that ingestion of the carbonic anhydrase inhibitor acetazolamide and the ion exchange inhibitor DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid), at 10(-4) M eliminates lumen alkalinization. Basal application of these inhibitors in situ also reduced gradients recorded with self-referencing pH-sensitive microelectrodes near the basal membrane by approximately 65% and 85% respectively. Self-referencing chloride-selective microelectrodes revealed a specific spatial profile of transepithelial chloride transport with an efflux maximum in anterior midgut. Both acetazolamide and DIDS reduced chloride effluxes. These data suggest that an H(+) V-ATPase-energized anion exchange occurs across the apical membrane of the epithelial cells and implicate an electrophoretic Cl(-)/HCO(3)(-) exchanger and carbonic anhydrase as crucial components of the steady-state alkalinization in anterior midgut of mosquito larvae.