Vegetal cover estimated by digital photographs related to biomass in a grassland site in northern Mexico

A regression model was used to determine the relationship between aerial herbaceous biomass and vegetation coverage estimated by digital images. Four samplings (n=36 each date) of vegetation cover and herbaceous biomass were performed during the growing season in 2011 in a grassland dominated by Bouteloua gracilis in La Cieneguilla, Municipality of Villa Hidalgo, Durango. Average production of dry biomass was 37.36 ± 9.66 g/m², and mean vegetation cover 30.02%. Dry biomass data were tested for normality using the test of Kolmogorov Smirnov, finding a lack of fit. The data were subjected to a logarithmic transformation and the model Ln(y) = 1.637926 + 0.08501X - 0.000586X² with an adjusted R² = 0.89 was found. In order to validate this model, another five samplings were carried out in 2013 at the same site during summer and autumn, using the same sampling size for each date as in 2011. Data collected in 2013 were analyzed with the model Ln (y) = β₀ + β₁X + β₂X². A comparison of regression coefficients was carried out between the 2011 and 2013 models with t (180+144-9-11-2=302, p<0.05) = 1.967. The results indicated that it is possible to use the 2011 regression model to estimate herbaceous aerial biomass from vegetation cover measurements with aerial photographs in La Cieneguilla site during summer and fall.     

A novel scheme to assess factors involved in the reproducibility of DNA-microarray data

Background  

In research laboratories using DNA-microarrays, usually a number of researchers perform experiments, each generating possible sources of error. There is a need for a quick and robust method to assess data quality and sources of errors in DNA-microarray experiments. To this end, a novel and cost-effective validation scheme was devised, implemented, and employed.     

Expression of ATP6V1C1 during oral carcinogenesis

We investigated the gene and protein expressions of V-type ATPase protein subunit C1 (ATP6V1C1) in cases of oral squamous cell carcinoma (OSCC) and contralateral normal mucosa in smokers, nonsmokers and former smokers. Subjects were separated into five groups of 15: group 1, smokers with OSCC; group 2, normal contralateral mucosa of OSCC patients; group 3, chronic smokers; group 4, former smokers who had stopped smoking 1 year earlier; group 5, individuals who had never smoked. Exfoliative cytology specimens from oral mucosa of smokers, former smokers and nonsmokers showed normal gene and protein expression. We found significantly greater gene expression in the OSCC group than in the nonsmoker groups. No difference in gene expression was observed between normal contralateral mucosa and nonsmoker groups, smoker and nonsmoker groups or former smoker and nonsmoker groups. We observed intense immunostaining for ATP6V1C1 protein in all cases of OSCC and weak or no staining in smoker, former smoker and nonsmoker groups. Significantly greater expression of ATP6V1C1 protein was observed in the OSCC group compared to the other groups, which supports the role of ATP6V1C1 in effecting changes associated with oral cancer. Analysis of the mucosae of chronic smokers, former smokers and the normal contralateral mucosa of patients with OSCC showed unaltered ATP6V1C1 gene and protein expression. Early stages of carcinogenesis, represented by altered epithelium of chronic smokers, had neither gene nor protein alterations as seen in OSCC. Therefore, we infer that the changes in ATP6V1C1 occur during later stages of carcinogenesis. Our preliminary study provides a basis for future studies of using ATP6V1C1 levels for detecting early stage OSCC.     

Chromosome phylogeny of the subfamily Pitheciinae (Platyrrhini,Primates) by classic cytogenetics and chromosome painting

Background  

The New World monkey (Platyrrhini) subfamily Pitheciinae is represented by the genera Pithecia, Chiropotes and Cacajao. In this work we studied the karyotypes of Pithecia irrorata (2n = 48) and Cacajao calvus rubicundus (2n = 45 in males and 2n = 46 in females) by G- and C-banding, NOR staining and chromosome painting using human and Saguinus oedipus whole chromosome probes. The karyotypes of both species were compared with each other and with Chiropotes utahicki (2n = 54) from the literature.     

Effects of age,replicative lifespan and growth rate of human nucleus pulposus cells on selecting age range for cell-based biological therapies for degenerative disc diseases

Autologous disc cell implantation, growth factors and gene therapy appear to be promising therapies for disc regeneration. Unfortunately, the replicative lifespan and growth kinetics of human nucleus pulposus (NP) cells related to host age are unclear. We investigated the potential relations among age, replicative lifespan and growth rate of NP cells, and determined the age range that is suitable for cell-based biological therapies for degenerative disc diseases. We used NP tissues classified by decade into five age groups: 30s, 40s, 50s, 60s and 70s. The mean cumulative population doubling level (PDL) and population doubling rate (PDR) of NP cells were assessed by decade. We also investigated correlations between cumulative PDL and age, and between PDR and age. The mean cumulative PDL and PDR decreased significantly in patients in their 60s. The mean cumulative PDL and PDR in the younger groups (30s, 40s and 50s) were significantly higher than those in the older groups (60s and 70s). There also were significant negative correlations between cumulative PDL and age, and between PDR and age. We found that the replicative lifespan and growth rate of human NP cells decreased with age. The replicative potential of NP cells decreased significantly in patients 60 years old and older. Young individuals less than 60 years old may be suitable candidates for NP cell-based biological therapies for treating degenerative disc diseases.     

Prevalence of nontuberculous mycobacteria in water supplies of hemodialysis centers

Infection of hemodialysis patients with nontuberculous mycobacteria (NTM) has been associated with water used in reprocessing hemodialyzers. This study was conducted to determine the prevalence of NTM and other bacteria in water samples collected over a 13-week period from 115 randomly selected dialysis centers in the United States. Total viable counts were determined by membrane filter assays; increased recovery of NTM was obtained by dosing a portion of each water sample with 1% formaldehyde (HCHO) before filtering. NTM were widely distributed and occurred with a high frequency in water supplies in dialysis centers. NTM were detected in water from 95 centers (83%), and 50% of all samples examined contained NTM. The results of this study support recommendations to use 4% HCHO or a chemical germicidal equivalent for disinfecting dialyzers that are to be reused.     

Abdominal grooming in the cockroach: Development of an adult behavior

Chemical or tactile irritants delivered to the dorsomedial region of the abdomen of the cockroach Periplaneta americana. evoke a complex grooming response. In larvae the response consitsts of extension of all six legs and arching of the abdomen which is rubbed against any solid surface presented. In adults, leg extension and arching are accompanied by side to side wagging of the abdomen and rapid scissoring of the wings.In some decapitated late instar larvae, abdominal wagging behavior can be evoked by chemical or tactile stimulation of the dorso-medial region of the abdomen. The form of the wag is somewhat different in these animals than in the adults, and it occurs at a lower frequency.Neuronal circuitry underlying the rhythmic wagging response of the adult may therefore be laid down or made functional in the mid- to late-larval stages. The wagging behavior is not normally expressed until the final ecdysis.A population of sensory setae is found on the abdomen at all stages of development, and some of these are presumed to trigger the grooming behavior when stimulated. The morphology and distribution of some of the adult receptors differs from some of the larval receptors.All larvae, including those late-instar individuals which show an adult-like response (wagging) have identical receptors on the abdomen in terms of morphology, distribution, and general responsiveness. Thus, no obvious changes in abdominal sensory receptors are correlated with the emergence of the wagging behavior. Anatomical and/or functional changes within the central nervous system are most likely responsible for the emergence of adult wagging behavior.     

External biliary fistula.

External biliary fistulas, once common, are now rare: before the present report of 4 cases only 27 cases have been reported in the English literature since 1900. Review of the records of four patients with external biliary fistula confirmed its occurrence in patients over 50 years of age and the variable site for operning of the fistulous tract. Cholecystectomy provided successful treatment in three of the four patients but the fourth was too ill to undergo an operation; in general, definitive treatment is cholecystectomy, together with excision of the fistulous tract if this takes a direct path through the abdominal wall from the gallbladder, or curettage if the course is devious.