Effect of habitat disturbance on pollination biology of the columnar cactus Stenocereus quevedonis at landscape-level in central Mexico.

Stenocereus quevedonis ('pitire') is a columnar cactus endemic to central Mexico, grown for its edible fruit. Phenology, pollination biology and behaviour of flower visitors of this species were compared in six conserved and disturbed sites, hypothesising that: (i) pitire pollination is self-incompatible, requiring animal vectors; (ii) higher incidence of radiation on plants in cleared forest may lead to a higher number of flowers per pitire plant and longer blooming season, and disturbing and differential spatial availability of flower resources may determine differential attraction of pollinators to conserved and disturbed areas; (iii) if pitire pollination system is specialised, reproductive success would decrease with pollinator scarcity, or other species may substitute for main pollinators. In all sites, pitire reproduction started in January, flowering peak occurring in April, anthesis duration was 15 h and predominantly nocturnal (9 h), pollen was released at 23:00 h, nectar was produced throughout anthesis, and breeding system was self-incompatible. Flower production per plant was similar in disturbed and conserved sites, but flower availability was higher (because of higher tree density) and longer in disturbed sites. Pollination is nocturnal, the most frequent legitimate pollinator being the bat Leptonycteris yerbabuenae; diurnal pollination is rare but possible, carried out by bee species. Fruit and seed set in control and nocturnal pollination treatments at disturbed sites were higher than in conserved sites. Frequency of L. yerbabuenae visits was similar among site types, but more visits of complementary nocturnal and diurnal pollinators were recorded in disturbed sites, which could explain differences in reproductive success.

Molecular characterization of the human immunodeficiency virus type 1 among children in Lima, Peru.

In Peru, there is a lack of information on molecular analysis in pediatric human immunodeficiency virus (HIV) infection. At present, the mother-to-child transmission rate is estimated at approximately 2-4%. The objective of this study was to assess the molecular epidemiology of HIV-1 in infected children. Children with suspected or confirmed pulmonary tuberculosis were evaluated at two public hospitals between 2002 and 2007. Whole blood samples were obtained from 90 HIV-positive children, who were confirmed to be positive by enzyme-linked immunosorbent assay and Western blot. The specimens were subjected to envelope heteroduplex mobility assay (env HMA) followed by gag and pol gene region sequence analysis. Subtype B was found in 88 (98%) of 90 children and 2 (2%) children were subtype BF recombinants. This is the first report of recombinant HIV strains in HIV-infected children in Peru. Understanding the origin, diversity, and spread of HIV strains worldwide will be necessary for the development of an effective vaccine that targets pediatric populations throughout the world.

Microbiological assessment of house and imported bottled water by comparison of bacterial endotoxin concentration, heterotrophic plate count, and fecal coliform count

Consumers increasingly use bottled water and home water treatment systems to avoid direct tap water. According to the International Bottled Water Association (IBWA), an industry trade group, 5 billion gallons of bottled water were consumed by North Americans in 2001. The principal aim of this study was to assess the microbial quality of in-house and imported bottled water for human consumption, by measurement and comparison of the concentration of bacterial endotoxin and standard cultivable methods of indicator microorganisms, specifically, heterotrophic and fecal coliform plate counts. A total of 21 brands of commercial bottled water, consisting of 10 imported and 11 in-house brands, selected at random from 96 brands that are consumed in Puerto Rico, were tested at three different time intervals. The Standard Limulus Amebocyte Lysate test, gel clot method, was used to measure the endotoxin concentrations. The minimum endotoxin concentration in 63 water samples was less than 0.0625 EU/mL, while the maximum was 32 EU/mL. The minimum bacterial count showed no growth, while the maximum was 7,500 CFU/mL. Bacterial isolates like P. fluorescens, Corynebacterium sp. J-K, S. paucimobilis, P. versicularis, A. baumannii, P. chlororaphis, F. indologenes, A. faecalis and P. cepacia were identified. Repeated measures analysis of variance demonstrated that endotoxin concentration did not change over time, while there was a statistically significant (p < 0.05) decrease in bacterial count over time. In addition, multiple linear regression analysis demonstrated that a unit change in the concentration of endotoxin across time was associated with a significant (p < 0.05) reduction in the bacteriological cell count. This analysis evidenced a significant time effect in the average log bacteriological cell count. Although bacterial growth was not detected in some water samples, endotoxin was present. Measurement of Gram-negative bacterial endotoxins is one of the methods that have...

Canine visceral leishmaniasis on Margarita Island (Nueva Esparta, Venezuela).

The frequency of American visceral leishmaniasis affecting humans on Margarita Island, Venezuela, has increased in recent years, and infected dogs appear to constitute the principal source of infection. ELISA tests with Leishmania donovani promastigotes and rK39 antigen from L. chagasi in serum from 541 dogs were positive in 33.1% and 21.6% of the samples, respectively. A second blood sample taken from 50 animals after 8-10 months revealed an increase from 24% to 40% of ELISA positivity to both antigens, suggesting high susceptibility and transmission in the canine population. Among 42 serologically positive dogs, 33% of which showed clinical signs of disease, 79% were positive in polymerase chain reactions using primers specific for the L. donovani complex. Control measures including epidemiological hypersurveillance, the humane sacrifice of infected dogs, and rapid diagnosis and treatment of human cases have been initiated.

Colorectal carcinoma in young patients: CT detection of an atypical pattern of recurrence.

Colonic adenocarcinoma is an uncommon but aggressive neoplasm in patients under the age of 40. The goals of this study were to evaluate the utility of computed tomography (CT) in preoperative staging and detection of postoperative recurrences in young patients with colon cancer and to evaluate the pattern of recurrent disease. We reviewed 51 cases of adenocarcinoma in patients aged 40 years and younger. CT preoperatively staged 21 (72%) of 29 patients correctly and had a 100% positive predictive value for metastatic disease. Recurrent disease occurred in 23 (76%) of 30 nonstage D patients with at least 2 years of disease-free follow-up. CT accurately detected 21 (91%) of 23 cases of recurrent disease. Local recurrences were detected in 20 (87%) of 23 patients. Isolated local disease was the most frequent pattern of recurrence, seen in 17 (74%) of 23 patients. Hepatic metastases were rare and occurred in nine (13%) of 51 patients. Young patients with colon cancer have an increased prevalence of isolated local recurrences and decreased rate of hepatic metastases than the older population. In order to detect early, and therefore resectable recurrent disease, CT examinations should be obtained early and often in the postoperative period.