Prevalence and spatial distribution of bovine brucellosis in San Luis and La Pampa, Argentina.

BACKGROUND: Bovine brucellosis (BB) is a zoonotic disease caused by Brucella abortus. BB is endemic in Argentina, where vaccination with Brucella abortus strain 19 is compulsory for 3-to-8 month-old heifers. The objectives of this study were to quantify the prevalence of BB and to identify factors associated with its occurrence, along with the spatial distribution of the disease, in the provinces of La Pampa and San Luis. A two-stage random sampling design was used to sample 8,965 cows (3,513 in La Pampa and 5,452 in San Luis) from 451 farms (187 in La Pampa and 264 in San Luis). RESULTS: Cow and herd prevalence were 1.8 % (95 % CI: 1.3-2.2; n = 157) and 19.7 % (95 % CI: 17.0-22.4; n = 89), respectively. Both cow-level and herd-level prevalence in La Pampa (2.4 and 26.0 %, respectively) were significantly higher than in San Luis (1.4 and 15.5 %, respectively). There were not differences between the proportions of reactive cattle compared to that obtained in a survey conducted in 2005. However, herd prevalence in La Pampa was significantly (P < 0.05) higher compared to that study. Disease was found to be spatially clustered in west La Pampa. The lower the bovine density and the calf/cow ratio, the higher odds of belonging to the cluster. CONCLUSIONS: The increase of farm prevalence in the last five years suggests that the disease is spreading and that control measures should be applied in the region. The cluster of infected farms was located in the west region of La Pampa. There, farms have lower animal densities and smaller cow/calf indices compared to the rest of the province. Although western La Pampa has more infected herds, within-farm prevalence was not higher, which suggests that the control program has been relatively successful in controlling the disease at the farm level, and/or that low animal density inherently results in low disease prevalence. Our results provide baseline information on the epidemiology of BB and its potential pattern of transmission in Argentina, which will ultimately help to improve BB control programs in the country.

Pathology of enteric infections induced by the acanthocephalan Profilicollis chasmagnathi in Olrog's gull, Larus atlanticus, from Argentina.

Acanthocephalans can be pathogenic helminths of marine birds. Every year during the breeding season, there is variable mortality among prefledged chicks from the largest known Olrog's gull (Larus atlanticus) colony. Mortality has been associated with infection by the acanthocephalan Profilicollis chasmagnathi. Our aim was to study the role of chicks' size as a risk factor for intensity of infection and severe pathology, and to expand upon previous pathological findings reported in acanthocephalan-infected chicks. Size of the chick was associated with intensity of infection and number of intestinal perforations, which increased by 6.9% and 4.1%, respectively, for each millimetre increment in chick size. Infection was associated with inflammatory enteritis and granulomatous peritonitis. Complete intestinal perforations were observed in 85% and 97.3% of the studied chicks in 2005 and 2006, respectively, and they were observed very early during the post-hatching period. Our results show: (1) the presence of advanced pathology associated with acanthocephalan infections in chicks, beginning very early in the post-hatching period; and (2) significant increases in the intensity of infection and the associated pathology as a function of size of chicks, in dead chicks during this period.

Epidemiology of acanthocephalan infections in crabs from the Bahía Blanca Estuary, Argentina.

This study was conducted in two populations of crabs, Cyrtograpsus angulatus and Neohelice granulata from the Bahía Blanca Estuary, in Argentina, to identify risk factors for infection by the acanthocephalan Profilicollis chasmagnathi and to assess the association between infection and mortality of these hosts. Cyrtograpsus angulatus and N. granulata crabs were sampled seasonally over the course of a year, and spring sampling included collection of dead crabs predated by Olrog's gulls in a nearby breeding colony. Potential risk factors for infection were assessed and the number of cystacanth larvae per crab was counted. In C. angulatus, the odds of infection increased by 7% for each millimetre increase in carapace length, and were nearly 17 times greater in crabs sampled from the Olrog's gull feeding area compared with those sampled from nests in the breeding colony. For every millimetre increase in carapace length in N. granulata, the odds of infection increased by 13% in crabs from the breeding colony, and by 32% in crabs from the feeding area. Mean intensity of infection in N. granulata increased by 16.5% for each additional millimetre of carapace width. The level of parasite aggregation was lowest in the largest C. angulatus and highest in N. granulata predated by Olrog's gull. The results show that host size is the most important factor influencing infection prevalence in both crab species and intensity of infection in N. granulata, and suggest the presence of parasite-induced mortality in the populations studied.

New insights on the mechanism of oxidation of D-galacturonic acid by hypervalent chromium.

The pollutant Cr(VI) is known to be very carcinogenic. In conditions of excess of Cr(VI), oxidation of D-galacturonic acid (Galur), the major metabolite of pectin, yields d-galactaric acid (Galar) and Cr(III). The redox reaction takes place through a multistep mechanism involving formation of intermediate Cr(II/IV) and Cr(V) species. The mechanism combines one- and two-electron pathways for the reduction of Cr(IV) by the organic substrate: Cr(VI)→ Cr(IV)→ Cr(II) and Cr(VI)→ Cr(IV)→ Cr(III). This is supported by the observation of the optical absorption spectra of Cr(VI) esters, free radicals, CrO(2)(2+) (superoxoCr(III) ion) and oxo-Cr(V) complexes. Cr(IV) cannot be directly detected; however, formation of CrO(2)(2+) provides indirect evidence for the intermediacy of Cr(II/IV). Cr(IV) reacts with Galur much faster than Cr(V) and Cr(VI) do. The analysis of the reaction kinetics via optical absorption spectroscopy shows that the Cr(IV)-Galur reaction rate inversely depends on [H(+)]. Nevertheless, high [H(+)] still does not facilitate accumulation of Cr(IV) in the Cr(VI)-Galur mixture. Cr(VI) and the intermediate Cr(V) react with Galur at comparable rates; therefore the build-up and decay of Cr(V) accompany the decay of Cr(VI). The complete rate laws for the Cr(VI), Cr(V) and Cr(IV)-Galur redox reaction are here derived in detail. Furthermore, the nature of the five-co-ordinated oxo-Cr(V) bischelate complexes formed in Cr(VI)-Galur mixtures at pH 1-5 is investigated using continuous-wave and pulsed electron paramagnetic resonance (EPR) and density functional theory (DFT).

Antibody response against three widespread bovine viruses is not impaired in Holstein cattle carrying bovine leukocyte antigen DRB3.2 alleles associated with bovine leukemia virus resistance.

Due to the wide dissemination of bovine leukemia virus (BLV) infection among dairy cattle, control and eradication programs based on serological detection of infected cattle and subsequent culling face a major economic task. In Argentina, genetic selection of cattle carrying alleles of the bovine leukocyte antigen (BoLA) DRB3.2 gene associated with BLV-infection resistance, like *0902, emerges as the best additional tool toward controlling virus spread. A potential risk in expanding or segregating BoLA selected populations of cattle is that it might increase susceptibility to other common viruses. Special concern raises the strong association found between low proviral load and low antibody titer against major BLV structural proteins. This phenomenon might depend on host genetic factors influencing other viruses requiring, unlike BLV, strong and long-lasting humoral immune response to prevent infection. In this study, we demonstrate that there is no association among neutralizing antibody titers against foot and mouth disease virus, bovine viral diarrhea virus, or bovine herpesvirus type 1 and polymorphism of the BoLA DRB3.2 gene. Conversely, there is strong association between BoLA DRB3.2*0902 and low antibody titers against 2 BLV structural proteins--env gp51 and gag p24--to date, the best BLV resistance marker. There is also significant association between low antibody titers against gp51 and p24 and BoLA DRB3.2*1701 and low antibody titers against p24 and BoLA DRB3.2*1101 or 02. Our data suggest that increasing BoLA-selected BLV-resistant cattle or segregating BoLA-associated alleles to BLV susceptibility would not affect the resistance or the predisposition to bovine viral diarrhea virus, bovine herpesvirus type 1, or foot and mouth disease virus infection.

Association of BLV infection profiles with alleles of the BoLA-DRB3.2 gene.

Bovine leukaemia virus (BLV) causes lymphosarcoma and persistent lymphocytosis (PL). Some MHC class II gene polymorphisms have been associated with resistance and susceptibility to the development of lymphosarcoma and PL, as well as with a reduced number of circulating BLV-infected lymphocytes. Previously, 230 BLV-infected Holstein cattle were classified into two infection profiles characterized by low and high proviral loads (LPL and HPL respectively). Here, the influence of the polymorphism at the BoLA-DRB3.2* gene of these animals was examined. After genotyping, the association between the BoLA-DRB3.2* alleles and the BLV infection profile was determined as the odds ratio (OR). Two subtypes of allele *11 were identified (ISAG*0901 and *0902). Allele ISAG*0902 showed a stronger association with the LPL profile (OR = 8.24; P < 0.0001) than allele *11 itself (OR = 5.82; P < 0.0001). Allele ISAG*1701 (*12) also showed significant association with the LPL profile (OR = 3.46; P < 0.0055). Only one allele, ISAG*1501 or 03 (*16), showed significant association with HPL (OR = 0.36; P < 0.0005). The DRB3.2* alleles were assigned to three categories: resistant (R), susceptible (S) and neutral (N). Based on their DRB3 genotypes, cattle were classified as homozygous or heterozygous. The RR and RN genotypes were associated with the LPL profile, while the SS and NS genotypes were associated with the HPL profile. The RS genotype could not be associated with any particular profile. Our results show that allele ISAG*0902 appears to be the best BLV resistance marker in Holstein cattle.

Predictability of reef fish recruitment in a highly variable nursery habitat.

There has been a lengthy debate on whether the abundance of adult reef fishes depends on prerecruitment or postrecruitment processes; however, we still do not have the ability to predict the magnitude of local fish recruitment. Here we show that the success of the leopard grouper (Mycteroperca rosacea) recruitment in the Gulf of California, Mexico, is determined by the availability of nursery habitat, which in turn is strongly correlated to climate conditions. Observational and experimental studies showed that leopard grouper larvae recruit preferentially on shallow rocky bottoms with brown algal (Sargassum spp.) beds, and that abundance of recruits is determined by the availability of Sargassum. The biomass of Sargassum decreases linearly with an increase in the Multivariate El Niño Southern Oscillation (ENSO) Index (MEI; an index positively correlated with water temperature and negatively correlated with nutrient availability). We analyzed the relationship between the interannual variation of MEI and the recruitment of the leopard grouper using field estimates of abundance of juvenile groupers. Our results show that there is a nonlinear relationship between recruitment and the oceanographic climate, in that the density of recruits decreases exponentially with increasing MEI. The predictability of leopard grouper recruitment has important implications for fisheries management, since it could allow adaptive management without expensive stock assessment programs.

Distribution of CCR5-Delta 32 and CCR2-64I alleles in an Argentine Amerindian population.

In order to evaluate the frequency distributions of CCR5-Delta 32 and CCR2-64I polymorphisms in an Amerindian population, we tested a total of 42 Chiriguanos individuals that are aboriginal inhabitants of the north west of Argentina. Only one carried the CCR5-Delta 32 allele (0.0238), while 17 out of 35 carried the CCR2-64I mutation, including one homozygous for the mutated allele (0.2571). Although the cohort studied is considered highly endogamic, the HLA genotyping revealed that 8 out of 42 subjects had a gene flow from Caucasian populations. The only heterozygous CCR5+/Delta 32 found and three heterozygous CCR2+/64I belonged to the admix group. In conclusion, the protective deletion CCR5-Delta 32 is practically absent in Chiriguanos whereas the CCR2-64I allele is highly frequent.

Linfoma primario de próstata: nuevo caso clínico / Primary lymphoma of the prostate gland: a mew clinic case

Presentamos un nuevo caso de Linfoma Primario de Próstata. Hasta la fecha, se han comunicado aproximadamente 100 casos en la literatura mundial. Nuestro caso, se trata de un paciente de 73 años, que consultó por prostatismo. La anatomía patológica, obtenida por punción-biopsia transrectal informó linfoma tipo B, asociado con HBP. Los estudios complementarios de extensión de la enfermedad fueron todos negativos.. El paciente fue tratado mediante RTU, por uropatía obstructiva infravesical, más 6 ciclos de quimioterapia (CHOP). que debió completarse con radioterapia (5.940 cGy) para obtener la remisión completa. A la fecha, y con un seguimiento de 30 meses, el paciente se encuentra asintomático y libre de enfermedad

Linfoma primario de próstata: nuevo caso clínico / Primary lymphoma of the prostate gland: a mew clinic case

Presentamos un nuevo caso de Linfoma Primario de Próstata. Hasta la fecha, se han comunicado aproximadamente 100 casos en la literatura mundial. Nuestro caso, se trata de un paciente de 73 años, que consultó por prostatismo. La anatomía patológica, obtenida por punción-biopsia transrectal informó linfoma tipo B, asociado con HBP. Los estudios complementarios de extensión de la enfermedad fueron todos negativos.. El paciente fue tratado mediante RTU, por uropatía obstructiva infravesical, más 6 ciclos de quimioterapia (CHOP). que debió completarse con radioterapia (5.940 cGy) para obtener la remisión completa. A la fecha, y con un seguimiento de 30 meses, el paciente se encuentra asintomático y libre de enfermedad(AU)

Protracted, but not acute, hepatitis A virus infection is strongly associated with HLA-DRB*1301, a marker for pediatric autoimmune hepatitis.

HLA alleles are known to be associated with susceptibility to develop autoimmune hepatitis (AH), and hepatitis A virus (HAV) infection is postulated as a putative trigger for AH. We investigated whether HLA may influence the outcome of the HAV infection by studying 67 children with self-limited and 39 children with protracted forms of this infection. HLA typing of the uncomplicated forms showed no significant increase of any HLA class I or II alleles. In contrast, DRB1*1301 was present in 46.1% of the children with protracted forms (vs. 9.8% in healthy controls; relative risk [RR]: 7.6; chi(2) = 33.3; P = 2 x 10(-9)). In uncomplicated hepatitis, 45% developed anti-smooth muscle antibody (SMA)/actin antibodies, but only 1 child had detectable antibodies after 3 months of infection onset. In contrast, after 1 year, 69% of the patients suffering protracted forms had titers of anti-SMA/actin antibodies that ranged between 1:40 and 1:160. Within their follow-up, 2 patients developed a Hashimoto's thyroiditis, but the remaining patients showed no signs of developing autoimmune hepatitis. We conclude that the DRB1*1301 haplotype is strongly associated with the protracted forms of HAV infection and suggest that the infection allows a sustained release of liver self-antigens. However, other still-unknown susceptibility genes are required for the full development of pediatric AH.

Novel HLA allele, HLA-B*4013, identified from a potential bone marrow recipient. Putative gene conversion events with donor sequence.

A new B40 allele was identified in a leukemic Caucasian patient. This allele, designated B*4013, differs in alpha 1 domain from B*4002 at six amino acidic positions: 67, 77, 80, 81, 82 and 83. Most of this substitutions could alter the antigen binding site of the HLA-B molecule. B*4013 may have originated by gene conversion or reciprocal recombination involving B*4002 as the recipient allele of sequence donated by B*4406. The new allele was serologically typed as a "blank" associated with the Bw4 epitope.

The reduction of CrVI to CrIII by the alpha and beta anomers of D-glucose in dimethyl sulfoxide. A comparative kinetic and mechanistic study.

The reduction of CrVI by alpha-D-glucose and beta-D-glucose was studied in dimethyl sulfoxide in the presence of pyridinium p-toluensulfonate, a medium where mutarotation is slower than the redox reaction. The two anomers reduce CrVI by formation of an intermediate CrVI ester precursor of the slow redox step. The equilibrium constant for the formation of the intermediate chromic ester and the rate of the redox steps are different for each anomer. alpha-D-Glucose forms the CrVI-Glc ester with a higher equilibrium constant than beta-D-glucose, but the electron transfer within this complex is slower than for the beta anomer. The difference is attributed to the better chelating ability of the 1,2-cis-diolate moiety of the alpha anomer. The CrV species, generated in the reaction mixture, reacts with the two anomers at a rate comparable with that of CrVI. The EPR spectra show that the alpha anomer forms several linkage isomers of the five-coordinate CrV bis-chelate, while beta-D-glucose affords a mixture of six-coordinate CrV monochelate and five-coordinate CrV bis-chelate. The conversion of the CrV mono- to bis-chelate is discussed in terms of the ability of the 1,2-cis- versus 1,2-trans-diolate moieties of the glucose anomers to bind CrV.

Accesos vasculares centrales: análisis de 100 casos / Central vascular access: analysis of 100 cases

Con el objeto de conocer las indicaciones, complicaciones, control y evolución de los accesos venosos centrales, se confeccionó un protocolo de trabajo prospectivo para el análisis de los mismos. Del total de las vías efectuadas se escogió una muestra de 100 casos. La relación hombre: mujer fué de 1,17: 1; el promedio de edad de 52,8 años (max. 91, min. 15). Del total de vías centrales 68 fueron por punción (67,6 por ciento yugular interna por vía media, 20,5 por ciento por vía posterior, 8,8 por ciento por subclavia infraclavicular y 2,9 por ciento por otras vías. Por disección se utilizaron la vena basílica en el 93 por ciento de los casos, la cefálica y la safena en 3,1 por ciento respectivamente. Treita y dos casos fueron controlados radiológicamente luego del procedimiento, pudiendo detectarse 4 neumotórax, que junto a 3 hematomas, fueron las complicaciones inherentes a la función. Un hematoma 2 infecciones de la herida y una trombosis de la vena ilíaca, fueron secundarias al acceso por disección en 2 pacientes. Las complicaciones secundarias al cateter fueron: sepsis en 2 casos y dolor torácico en 1 caso. Se observó que las complicaciones se vieron con una frecuencia mayor pero no significativa (p: 0,68) en aquellos operadores con menor experiencia. Cuarenta y un cateteres fueron enviados a cultivos luego de su extracción, 16 fueron positivos, el 50 por ciento a estafilococo aureus. Concluímos que salvo contraindicación absoluta los accesos vasculares centrales deben realizarse por punción, el control radiológico se realizará ante sospecha de lesión pleural o disfunción del cateter y, como todo acto quirúrgico, debe ir precedido de una correcta antisepsia:

Accesos vasculares centrales: análisis de 100 casos / Central vascular access: analysis of 100 cases

Con el objeto de conocer las indicaciones, complicaciones, control y evolución de los accesos venosos centrales, se confeccionó un protocolo de trabajo prospectivo para el análisis de los mismos. Del total de las vías efectuadas se escogió una muestra de 100 casos. La relación hombre: mujer fué de 1,17: 1; el promedio de edad de 52,8 años (max. 91, min. 15). Del total de vías centrales 68 fueron por punción (67,6 por ciento yugular interna por vía media, 20,5 por ciento por vía posterior, 8,8 por ciento por subclavia infraclavicular y 2,9 por ciento por otras vías. Por disección se utilizaron la vena basílica en el 93 por ciento de los casos, la cefálica y la safena en 3,1 por ciento respectivamente. Treita y dos casos fueron controlados radiológicamente luego del procedimiento, pudiendo detectarse 4 neumotórax, que junto a 3 hematomas, fueron las complicaciones inherentes a la función. Un hematoma 2 infecciones de la herida y una trombosis de la vena ilíaca, fueron secundarias al acceso por disección en 2 pacientes. Las complicaciones secundarias al cateter fueron: sepsis en 2 casos y dolor torácico en 1 caso. Se observó que las complicaciones se vieron con una frecuencia mayor pero no significativa (p: 0,68) en aquellos operadores con menor experiencia. Cuarenta y un cateteres fueron enviados a cultivos luego de su extracción, 16 fueron positivos, el 50 por ciento a estafilococo aureus. Concluímos que salvo contraindicación absoluta los accesos vasculares centrales deben realizarse por punción, el control radiológico se realizará ante sospecha de lesión pleural o disfunción del cateter y, como todo acto quirúrgico, debe ir precedido de una correcta antisepsia: (AU)