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21.
María Esther Diupotex-Chong Néstor J Cazzaniga Alejandra Hernández-Santoyo José Miguel Betancourt-Rule 《Biocell》2004,28(3):279-285
Mitotic chromosomes of the freshwater snail Pomacea patula catemacensis (Baker 1922) were analyzed on gill tissue of specimens from the type locality (Lake Catemaco, Mexico). The diploid number of chromosomes is 2n = 26, including nine metacentric and four submetacentric pairs; therefore, the fundamental number is FN = 52, No sex chromosomes could be identified. The same chromosome number and morphology were already reported for P. flagellata, i.e., the other species of the genus living in Mexico. The basic haploid number for family Ampullariidae was reported to be n = 14 in the literature; so, its reduction to n = 13 is probably an apomorphy of the Mexican Pomacea snails. Lanistes bolteni, from Egypt, also shows n = 13, but its karyotype is much more asymmetrical, and seems to have evolved independently from P. flagellata and P. patula catemacensis. The nominotypical subspecies, P. patula patula (Reeve 1856), is a poorly known taxon, whose original locality is unknown. A taxonomical account is presented here, and a Mexican origin postulated as the most parsimonious hypothesis. 相似文献
22.
P Uribe-Zú?iga G Hernández-Tepichín C del Río-Chiriboga V Ortiz 《Canadian Metallurgical Quarterly》1995,37(6):592-601
Since 1987 The National AIDS Council in Mexico (CONASIDA), has conducted research projects among female commercial sex workers (CSW), who are seen at the AIDS Information Centers. Through these studies, we have been able to find out how different issues influence commercial sex work in Mexico City. Since the beginning of our own studies in 1989, HIV prevalence in this particular group has remained low (0.04%-0.2%). Factors found to be associated with condom use were: educational level, not having children, more experience in sex work and younger age. Condom use was reported by 88% of the women; however, qualitative information and high STD prevalence rates suggest a much lower condom use. Mandatory HIV testing is not useful as a preventive measure among sex workers. Persuasive and structural interventions must be implemented in accordance with local and legal situations. 相似文献
23.
Laboratory studies indicate that capsaicin, the hot-tasting component of chili peppers, may be carcinogenic. A population-based case-control study was conducted in Mexico City during 1989-1990 to evaluate the relation between chili pepper consumption and gastric cancer risk. The study included 220 incident cases and 752 controls randomly selected from the general population. Information was collected by interview. Chili pepper consumers were at high risk for gastric cancer compared with nonconsumers (age- and sex-adjusted odds ratio = 5.49, 95% confidence interval (CI) 2.72-11.06). Among consumers, there was a highly significant trend of increasing risk with increasing self-rated level of consumption (low, medium, and high) (p = 2 x 10(-7). The odds ratio for high-level consumers compared with nonconsumers was 17.11 (95% CI 7.78-37.59). However, when consumption was measured as frequency per day, a significant trend among consumers was not observed. Multivariable adjustment increased the magnitude of the chili pepper-gastric cancer association, but a significant trend among consumers (measured as frequency per day) was still not observed. Chili pepper consumption may be a strong risk factor for gastric cancer, but further studies are needed to test this hypothesis. 相似文献
24.
25.
Characterisation of greywater was conducted in two different greywater streams in the Netherlands (Groningen and Sneek). The concentrations of macropollutants and nutrients measured were very different in both streams; in particular the COD was 425 mg/L in Groningen's water whereas in Sneek it was 1,583 mg/L. The aerobic treatment of greywater in a fed-batch reactor led to a 90% removal of COD at different organic loading rates. Anaerobically, the removal reached 40% COD removal on average, the possible reason being the high amount of surfactants present in the influent. 相似文献
26.
OE Santana Rodríguez ML Malé Gil JF HernándezSantana JM Limi?ana Ca?al AM Martín Sánchez 《Canadian Metallurgical Quarterly》1998,14(6):555-561
Von Hippel-Lindau disease (VHL) is an autosomal dominant tumour syndrome caused by germline mutations of the VHL tumour suppressor gene located on chromosome 3p25-26. In VHL tumours may occur in 14 different target organs, including the eye. Retinal angiomas are considered the first manifestation of VHL disease in 43% of cases, and the cumulative probability of developing a retinal angioma in one or both eyes rises during each decade of life, reaching 80% for patients over 80 years old. Since 1976 patients with VHL at the University Hospital of Utrecht and their at-risk relatives have been screened periodically by a multidisciplinary team. Long-term follow-up ophthalmological data were analysed with special attention to natural course and results of treatment. In addition, we looked for a genotype-phenotype correlation. Retinal angiomas were found in all families. In one large family with a missense mutation (V170D) of the VHL gene, in which the complete spectrum of visceral- and central nervous system (CNS) features of VHL is present, macular, parapapillary, optic disc and ora serrata angiomas were also found. In general, however, a clear-cut genotype-phenotype correlation could not be found. Only early detection and treatment of peripheral retinal angiomas can be expected to decrease the percentage of patients with decreased visual acuity. Therefore, early detection and treatment of these tumours is of paramount importance. Ophthalmological screening of patients and persons at risk should start as early as possible. In patients with apparently sporadic retinal angiomas it is advisable to perform germline DNA analysis, since the risk of developing VHL is high, especially if the angiomas are bilateral, or unilateral and multifocal, if the patient is young, or if there is a family history suggestive of VHL. 相似文献
27.
M Hernández González MV Oropeza MA Guevara M Cervantes G Moralí 《Canadian Metallurgical Quarterly》1994,25(4):419-425
The effects of the intrathecal perispinal administration of adrenergic agonists on the characteristics of frequency, duration, and vigor of pelvic thrusting displayed by male rats during copulation was assessed by an accelerometric technique. A different dose of one drug (noradrenaline, clonidine or isoproterenol) and saline as control was administered at the lumbosacral level of the spinal cord to sexually active male rats in tests of sexual behavior performed at weekly intervals. The intrathecal administration of noradrenaline (alpha-adrenoceptor agonist) increased the frequency of pelvic thrusting in mount and intromission responses, whereas both the alpha 2-adrenoceptor agonist clonidine (25 micrograms) and the beta-adrenoceptor agonist isoproterenol (40 micrograms) reduced the frequency of pelvic thrusting in these responses as compared to values obtained under the intrathecal administration of saline. On the other hand, the duration of the thrusting trains and the potency or vigor of pelvic thrusting in mounts and intromissions did not differ from values obtained under saline treatment. These findings indicate a possible participation of noradrenaline in the modulation of the spinal mechanisms involved in the generation of rhythmic pelvic thrusting performed by the male rat during copulation. 相似文献
28.
L Bravo RJ Monté V Alfonso N Cabrera M Gómez R Hernández B García 《Canadian Metallurgical Quarterly》1995,47(3):215-216
One hundred and fifty-five strains of Aeromonas isolated in the stools of children under 5 years presenting with acute diarrheal disease were studied. Using the Aerokey II system for the identification of species, 47 strains were identified as Aeromonas caviae, 58 as Aeromonas hydrophila, 23 as Aeromonas veronii biovar sobria, 14 as Aeromonas trota, 9 as Aeromonas veronii biovar veronii, 2 as Aeromonas jandaei and 2 as Aeromonas shubertii, Emphasis is placed on the advantages of this method which allowed for the classification of new species not identified previously in our country. 相似文献
29.
Stefan K. Gehrig Hernán Badino Uwe Franke 《Computer Vision and Image Understanding》2012,116(1):16-24
Dense stereo algorithms are able to estimate disparities at all pixels including untextured regions. Typically these disparities are evaluated at integer disparity steps. A subsequent sub-pixel interpolation often fails to propagate smoothness constraints on a sub-pixel level.We propose to increase the sub-pixel accuracy in low-textured regions in four possible ways: First, we present an analysis that shows the benefit of evaluating the disparity space at fractional disparities. Second, we introduce a new disparity smoothing algorithm that preserves depth discontinuities and enforces smoothness on a sub-pixel level. Third, we present a novel stereo constraint (gravitational constraint) that assumes sorted disparity values in vertical direction and guides global algorithms to reduce false matches, especially in low-textured regions. Finally, we show how image sequence analysis improves stereo accuracy without explicitly performing tracking. Our goal in this work is to obtain an accurate 3D reconstruction. Large-scale 3D reconstruction will benefit heavily from these sub-pixel refinements.Results based on semi-global matching, obtained with the above mentioned algorithmic extensions are shown for the Middlebury stereo ground truth data sets. The presented improvements, called ImproveSubPix, turn out to be one of the top-performing algorithms when evaluating the set on a sub-pixel level while being computationally efficient. Additional results are presented for urban scenes. The four improvements are independent of the underlying type of stereo algorithm. 相似文献
30.
Aintzane Rueda-Martínez Aiara Garitazelaia Ariadna Cilleros-Portet Sergi Marí Rebeca Arauzo Jokin de Miguel Brbara P. Gonzlez-García Nora Fernandez-Jimenez Jose Ramon Bilbao Iraia García-Santisteban 《International journal of molecular sciences》2021,22(11)
Endometriosis is a common gynecological disorder that has been associated with endometrial, breast and epithelial ovarian cancers in epidemiological studies. Since complex diseases are a result of multiple environmental and genetic factors, we hypothesized that the biological mechanism underlying their comorbidity might be explained, at least in part, by shared genetics. To assess their potential genetic relationship, we performed a two-sample mendelian randomization (2SMR) analysis on results from public genome-wide association studies (GWAS). This analysis confirmed previously reported genetic pleiotropy between endometriosis and endometrial cancer. We present robust evidence supporting a causal genetic association between endometriosis and ovarian cancer, particularly with the clear cell and endometrioid subtypes. Our study also identified genetic variants that could explain those associations, opening the door to further functional experiments. Overall, this work demonstrates the value of genomic analyses to support epidemiological data, and to identify targets of relevance in multiple disorders. 相似文献