Biomedical subjects

R Sanchez

Publications and source records attributed to R Sanchez.

At least 37 records · Page 2Linked to original sources

PubMed2001

Cloning and expression of a sorghum gene with homology to maize vp1. Its potential involvement in pre-harvest sprouting resistance.

Pre-harvest sprouting (PHS) in sorghum is related to the lack of a normal dormancy level during seed development and maturation. Based on previous evidence that seed dormancy in maize is controlled by the vp1 gene, we used a PCR-based approach to isolate two Sorghum bicolor genomic and cDNA clones from two genotypes exhibiting different PHS behaviour and sensitivity to abscisic acid (ABA). The two 699 amino acid predicted protein sequences differ in two residues at positions 341 (Gly or Cys within the repression domain) and 448 (Pro or Ser) and show over 80, 70 and 60% homology to maize, rice and oat VP1 proteins respectively. Expression analysis of the sorghum vp1 gene in the two lines shows a slightly higher level of vp1 mRNA in the embryos susceptible to PHS than in those resistant to PHS during embryogenesis. However, timing of expression was different between these genotypes during this developmental process. Whereas for the former the main peak of expression was observed at 20 days after pollination (DAP), the peak in the latter was found at later developmental stages when seed maturation was almost complete. Under favourable germination conditions and in the presence of fluridone (an inhibitor of ABA biosynthesis), sorghum vp1 mRNA showed to be consistently correlated with sensitivity to ABA but not with ABA content and dormancy.

Abscisic Acid↗

PubMed2001

Antioxidant properties of alpha-crystallin.

alpha-Crystallin is a major chaperone lens protein to which has been ascribed antioxidant functions. In the present work we have evaluated the antioxidant and free radical scavenging properties of bovine alpha-crystallin in a series of in vitro models: zimosan-induced, luminol-enhanced chemiluminescence response of polymorphonuclear leukocytes, the autoxidation of brain homogenate, bleaching of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)-derived radical cations, trapping of peroxyl radicals, and reactivity toward hypochloric acid. In all these systems, the reactivity of alpha-crystallin is higher than or similar to that of bovine serum albumin. It is concluded that, given the high concentrations of ol-crystallin in the lenses, its capacity to interact with free radicals and to remove hypochlorous acid could contribute to the maintenance of the lens functionality.

Animals↗

PubMed2001

Homology-based annotation yields 1,042 new candidate genes in the Drosophila melanogaster genome.

The approach to annotating a genome critically affects the number and accuracy of genes identified in the genome sequence. Genome annotation based on stringent gene identification is prone to underestimate the complement of genes encoded in a genome. In contrast, over-prediction of putative genes followed by exhaustive computational sequence, motif and structural homology search will find rarely expressed, possibly unique, new genes at the risk of including non-functional genes. We developed a two-stage approach that combines the merits of stringent genome annotation with the benefits of over-prediction. First we identify plausible genes regardless of matches with EST, cDNA or protein sequences from the organism (stage 1). In the second stage, proteins predicted from the plausible genes are compared at the protein level with EST, cDNA and protein sequences, and protein structures from other organisms (stage 2). Remote but biologically meaningful protein sequence or structure homologies provide supporting evidence for genuine genes. The method, applied to the Drosophila melanogaster genome, validated 1,042 novel candidate genes after filtering 19,410 plausible genes, of which 12,124 matched the original 13,601 annotated genes. This annotation strategy is applicable to genomes of all organisms, including human.

Animals↗

PubMed2001

Experimental evolution of enzyme temperature activity profile: selection in vivo and characterization of low-temperature-adapted mutants of Pyrococcus furiosus ornithine carbamoyltransferase.

We have obtained mutants of Pyrococcus furiosus ornithine carbamoyltransferase active at low temperatures by selecting for complementation of an appropriate yeast mutant after in vivo mutagenesis. The mutants were double ones, still complementing at 15 degrees C, a temperature already in the psychrophilic range. Their kinetic analysis is reported.

Adaptation, Biological↗

PubMed2001

Diabetes and diabetic retinopathy in a Mexican-American population: Proyecto VER.

OBJECTIVES: The prevalence rate of diabetes is probably higher in Hispanics than in Caucasians, although there is controversy about differences in the risk of diabetic retinopathy. The purpose of the study is to determine the prevalence rates of diabetes and diabetic retinopathy in a population-based study of Hispanics aged > or = 40 years. RESEARCH DESIGN AND METHODS: Proyecto VER is a random sample of Hispanic populations aged > or = 40 years in Arizona. A total of 4,774 individuals (71.6% of the eligible sample) completed the examinations. Diabetes was defined as self-report of a physician diagnosis or HbA(1c) value of > or = 7.0%. Diabetic retinopathy was assessed on stereo fundus photographs of fields 1, 2, and 4. RESULTS: The prevalence rate of diabetes in the Hispanic community (individuals > or = 40 years of age) was 22%. The prevalence rate of diabetic retinopathy (DR) was 48%; 32% had moderate to severe nonproliferative and proliferative retinopathy. DR increased with increasing duration of diabetes and increasing level of HbA(1c). The prevalence rate of DR-like changes in the sample of individuals without diabetic retinopathy was 15% and was not associated with hypertension, systolic blood pressure, or diastolic blood pressure. CONCLUSIONS: The prevalence rate of diabetes in this population of Hispanics is high, almost twice that of Caucasians. The prevalence rate of DR is high but similar to reports in a Caucasian population. The prevalence rate of 9% moderate to severe retinopathy in the newly diagnosed group suggests that efforts to improve detection and treatment of diabetes in Hispanics may be warranted.

Adult↗

PubMed2001

Psychometric properties of the 25-item NEI-VFQ in a Hispanic population: Proyecto VER.

PURPOSE: To assess the psychometric properties of the NEI-VFQ-25 in a population-based study of older Hispanic persons living in the United States, explore other demographic factors that affect participant response, and observe the comparability of the Spanish and English versions of the instrument. METHODS: A sample of randomly selected block groups in Tucson and Nogales, Arizona, were selected for study. Participants were interviewed at home; a majority of the interviews were conducted in Spanish. The home interview included questions from the NEI-VFQ-25 and HHANES: Presenting acuity was done using ETDRS methodology, followed by a standardized eye examination by an ophthalmologist. The authors analyzed the internal consistency of the NEI-VFQ-25 responses using Cronbach's alpha coefficient and the construct validity by assessing the relationship between presenting acuity and scale scores, adjusting for age and gender. A second model was also explored to determine whether other demographic variables affected scale scores; differences in reporting between the Spanish and English versions was observed in this model, used in a subset of the population that minimized interviewer effect. RESULTS: Of the 4774 participants in the study, 99.7% had completed questionnaires, not completed by proxy. The highest nonresponse rate occurred in the Driving scale, with 25% of participants not driving for reasons other than problems with vision. Internal consistency was high, with Cronbach alpha ranging between 0.65 and 0.86 for scales with multiple items. Adjusting for age and gender, those with presenting acuity worse than 20/40 scored significantly lower than those with presenting acuity 20/40 or better, for all scales. The demographic variables with the most consistent association across the NEI-VFQ-25 scales were presenting acuity, income, and gender. No significant differences in reporting were found between the Spanish and English versions of the questionnaire in the subset of the population. CONCLUSIONS: In this study of Hispanic people age 40 years or older, the NEI-VFQ-25 was sensitive to presenting acuity and other demographic variables, such as age, gender, and income. The findings from this psychometric analysis provide evidence of the reliability and validity of some of the scales in the 25-item NEI-VFQ when used among people with a range of visual acuity level, providing other explanatory variables are also considered.

Activities of Daily Living↗

PubMed2000

[Postoperative mortality a university Department of General Surgery: incidence of cardiac-related deaths].

OBJECTIVES: To evaluate the incidence of cardiac deaths following noncardiac nonvascular surgery. STUDY DESIGN: Retrospective survey. PATIENTS: All patients undergoing mainly endocrinous and digestive surgery in a University department of general surgery between 1991 and 1996. METHODS: Analysis of all deaths occurring intra- and postoperatively, until discharge of the patients. Demographic and medical data, including patent myocardial ischaemia and risk factors for coronary artery disease, were recorded and compared with a control group including all patients undergoing surgery from January to September 1996. RESULTS: In the 8,700 patients who underwent mainly endocrine neck surgery (66%), or intra-abdominal surgery (31%), the mortality rate (n = 96) was 1.1% (95% confidence interval [95% CI] = 0.9-1.3%). Patent myocardial ischaemia or high risk factors for coronary artery disease were existing in 24% of patients with neck surgery, 31% of those with intra-abdominal surgery, and in 60% of the deceased patients (P < 0.01 vs control group). Those who died were older, were in a higher ASA physical class, and had undergone an emergency procedure more often than patients of the control group (P < 0.002 for each parameter). Two cardiac deaths, in patients with a patent cardiopathy, were recorded (cardiac mortality: 0.02%; 95% CI = 0.003-0.08%). The main cause of death was infection (n = 46), followed by haemorrhage (n = 12). Seven deaths remained unexplained. CONCLUSION: This study suggests that cardiac morbidity is a rare cause of death after noncardiac nonvascular surgery.

Adult↗

PubMed2000

Investigation and control of aspergillosis and other filamentous fungal infections in solid organ transplant recipients.

Filamentous fungal infections are associated with high morbidity and mortality in solid organ transplant patients, and prevention is warranted whenever possible. An increase in invasive aspergillosis was detected among solid organ transplant recipients in our institution during 1991-92. Rates of Aspergillus infection (18.2%) and infection or colonization (42%) were particularly high among lung transplant recipients. Epidemiologic investigation revealed cases to be both nosocomial and community-acquired, and preventative efforts were directed at both sources. Environmental controls were implemented in the hospital, and itraconazole prophylaxis was given in the early period after lung transplantation. The rate of Aspergillus infection in solid organ transplant recipients decreased from 9.4% to 1.5%, and mortality associated with this disease decreased from 8.2% to 1.8%. The rate of Aspergillus infection or colonization among lung transplant recipients decreased from 42% to 22.5%; nosocomial Aspergillus infection decreased from 9% to 3.2%. Cases of aspergillosis in lung transplant recipients were more likely to be early infections in the pre-intervention period. Early mortality in lung transplant recipients decreased from 15% to 3.2%. Two cases of dematiaceous fungal infection were detected, and no further cases occurred after environmental controls. The use of environmental measures that resulted in a decrease in airborne fungal spores, as well as antifungal prophylaxis, was associated with a decrease in aspergillosis and associated mortality in these patients. Ongoing surveillance and continuing intervention is needed for prevention of infection in high-risk solid organ transplant patients.

Aspergillosis↗

PubMed2000

Organization and expression of a Thermus thermophilus arginine cluster: presence of unidentified open reading frames and absence of a Shine-Dalgarno sequence.

A group of genes regulated by arginine was found clustered in the order argF-ORF1-argC-argJ-ORF4 between other, as yet uncharacterized, open reading frames (ORFs). Transcription starts were identified immediately upstream from argF and ORF4. Arginine repressed transcription that was initiated at argF but induced transcription of ORF4. The functions of ORF1 and ORF4 are unknown, but analysis of the sequence of ORF4 suggests that it is a membrane protein, possibly involved in transport of arginine or a related metabolite. Mobility shift and DNase I footprinting have revealed specific binding of pure Escherichia coli ArgR to the promoter region of Thermus thermophilus argF. These results suggest that argF transcription is controlled by a repressor homologous to those characterized in enteric bacteria and bacilli. Thermus argF mRNA is devoid of Shine-Dalgarno (SD) sequences. However, downstream from the ATG start codon of argF and many other Thermus genes (with or without an SD box), sequences were found to be complementary to nucleotides 1392 to 1409 of Thermus 16S rRNA, suggesting that an mRNA-rRNA base pairing in this region is important for correct translation initiation.

Amino Acid Sequence↗

PubMed2000

Isolation and expression of PASK, a serine/threonine kinase, during rat embryonic development, with special emphasis on the pancreas.

We report the isolation and characterization of a serine/threonine kinase expressed during rat pancreas development. This kinase was cloned as part of a general screen using degenerate oligonucleotides to map expression of kinases and receptors during the course of pancreatic development. Sequence analysis showed it to be a member of the ste20-like serine/threonine kinase family. Northern blotting analysis against both fetal and adult tissues showed two transcripts, one of 2 kb and the other of 4 kb. The ratio of transcript expression varied with the tissue. In situ hybridization analysis showed that this gene is expressed in the early gut and pancreatic epithelium. By embryonic Day 15, the transcript is localized to cells that will eventually become exocrine in nature. In situ hybridization analysis also demonstrated high levels of expression in the choroid plexus, the developing myocardium, kidney, CNS, dorsal root ganglia, and testes. In addition, a search of the EST database revealed a related human kinase not previously described.

Amino Acid Sequence↗

PubMed2000

CarboMedics and Monostrut valves: clinical and hemodynamic outcomes in a randomized study.

BACKGROUND AND AIM OF THE STUDY: Our aim was to compare the CarboMedics (CM) and Monostrut (M) mechanical heart valve prostheses in the aortic position. These prostheses have been studied extensively in the past, both have well-defined characteristics, and have not been modified for many years. METHODS: This randomized, prospective study included 200 consecutive patients; 100 received the CM prosthesis and 100 the M prosthesis. Both groups were statistically similar in terms of age, aortic valve lesion, and preoperative clinical and surgical characteristics. Mean follow up was 5.58 years (range: 2 months to 11 years); total follow up was 1095 patient-years (pt-yr) (CM 5.33 years, 528 pt-yr; M 5.85 years, 567 pt-yr). RESULTS: Early mortality rates were 1% in the CM group and 3% in the M group. Late mortality rates were 7% and 9%, respectively. Mean (+/- SD) survival rates at 11 years were 80.51 +/- 7.36% for the CM group and 79.62 +/- 5.59% for the M group. There were no cases of mechanical valve failure in either group. The linearized rates of major thromboembolism were 1.03% and 0.20% per pt-yr for the CM and M groups, respectively; the rates of major bleeding-events were 0.71% and 0.61% per pt-yr, respectively. The rate of paravalvular leak was 0.35% and 0% per pt-yr in the CM and M groups, respectively. Postoperative NYHA class was I-II in 95.83% of CM patients, and in 94.37% of M patients. CONCLUSION: Clinical results with CarboMedics and Monostrut prostheses are highly satisfactory, but no superiority of one valve over the other can be identified.

Adult↗

PubMed1999

The evolutionary history of carbamoyltransferases: A complex set of paralogous genes was already present in the last universal common ancestor.

Forty-four sequences of ornithine carbamoyltransferases (OTCases) and 33 sequences of aspartate carbamoyltransferases (ATCases) representing the three domains of life were multiply aligned and a phylogenetic tree was inferred from this multiple alignment. The global topology of the composite rooted tree (each enzyme family being used as an outgroup to root the other one) suggests that present-day genes are derived from paralogous ancestral genes which were already of the same size and argues against a mechanism of fusion of independent modules. A closer observation of the detailed topology shows that this tree could not be used to assess the actual order of organismal descent. Indeed, this tree displays a complex topology for many prokaryotic sequences, with polyphyly for Bacteria in both enzyme trees and for the Archaea in the OTCase tree. Moreover, representatives of the two prokaryotic Domains are found to be interspersed in various combinations in both enzyme trees. This complexity may be explained by assuming the occurrence of two subfamilies in the OTCase tree (OTC alpha and OTC beta) and two other ones in the ATCase tree (ATC I and ATC II). These subfamilies could have arisen from duplication and selective losses of some differentiated copies during the successive speciations. We suggest that Archaea and Eukaryotes share a common ancestor in which the ancestral copies giving the present-day ATC II/OTC beta combinations were present, whereas Bacteria comprise two classes: one containing the ATC II/OTC alpha combination and the other harboring the ATC I/OTC beta combination. Moreover, multiple horizontal gene transfers could have occurred rather recently amongst prokaryotes. Whichever the actual history of carbamoyltransferases, our data suggest that the last common ancestor to all extant life possessed differentiated copies of genes coding for both carbamoyltransferases, indicating it as a rather sophisticated organism.

Amino Acid Sequence↗

PubMed1999

Correlation between planned prosthetic and residual bone trajectories in dental implants.

STATEMENT OF PROBLEM: The success of dental implant treatment relies on a well-developed treatment plan approach. Historically, implant placement was guided mainly by residual bone height and width, at times compromising prosthetic needs. PURPOSE: This study analyzed the amount of deviation between planned prosthetic trajectory and residual bone trajectory in different areas of the maxillary and mandibular dental arches, by using a tomographic survey in conjunction with imaging/surgical guides. METHODS AND MATERIAL: Ninety-two patients with a total of 235 implant sites were selected for the study. An imaging and surgical guide with a radiopaque indicator was constructed to determine the planned prosthetic trajectory. Cross-sectional tomograms were taken through the indicator at each implant site. The outlines of the available bone, planned prosthetic trajectory, and residual bone trajectory were traced, and the difference in the trajectory between the 2 trajectories was determined. RESULTS: Discrepancies between the planned prosthetic and the residual bone trajectories were greater in the mandibular molar area. This site was statistically different from other site groups at P =.05 (Tukey method). Statistically, all other site groups were not significantly different.

Analysis of Variance↗

PubMed1999

The use of non-immune plasma powder in the prophylaxis of neonatal Escherichia coli diarrhoea in calves.

The protective use of plasma powder from cattle and swine against experimentally induced neonatal E. coli diarrhoea in colostrum-deprived calves was examined. Diarrhoea was induced with a strain expressing F5+ fimbriae and a strain expressing F17+ fimbriae. In all groups supplemented with bovine plasma powder, diarrhoea and fever were less severe than in the control groups. For the groups infected with the F5+ E. coli strain, a reduction in excretion of the challenge strain by 2-4 orders of magnitude and by 1-2 orders of magnitude was seen when supplemented with bovine plasma powder at a dose of 25 g/l milk and 10 g/l milk, respectively. The bovine plasma powder showed also beneficial effects in the F17+ infected groups. No mortality, no septicaemia and no severe clinical signs were observed. Concerning the excretion of the E. coli F17+ strain in the faeces, no significant difference with the control group was found. Swine plasma powder showed little beneficial effect on E. coli diarrhoea in calves in this study.

Animals↗

PubMed1999

Inhibiteur de rejet de greffe alpha2-macroglobulin in burn injury: a suppressive activity on complement.

A subform of alpha2-macroglobulin, (inhibiteur de rejet de greffe (IRG), present at a low rate in healthy rat, increased with rate-related suppressive activity on complement during inflammatory processes. In human serum, a molecule with such properties was described. Serum and blister IRG from burn patients belonging to a selected population was purified under gentle conditions. Serum IRG increased quickly within the first day after hospitalization and continued to increase until day 6. Although absent in whole serum, the rate-related activity of IRG varied according to the surface area and the degree of burns. A rate-related activity was also revealed in whole blister fluid and in purified blister IRG. We report a new site and a new suppressive activity of IRG in its native form from serum and blister fluid during inflammatory processes of burned patients. The suppressive activity of IRG on complement is discussed, and it appears to play a role in the development of inflammatory processes.

Adolescent↗

PubMed1999

Formation of bone around titanium implants placed into zero wall defects: pilot project using reinforced e-PTFE membrane and autogenous bone grafts.

BACKGROUND: Guided bone regeneration (GBR) frequently is used to augment implants with various types of bone defects. The defects often are grafted with different materials, yet there is insufficient evidence that these materials enhance bone-to-implant contacts. PURPOSE: The purpose of this pilot project was to test the principle of GBR to promote bone formation adjacent to commercially pure titanium implants placed within zero-wall defects. Histologic and histomorphometric measurements were used to evaluate new bone formation. MATERIALS AND METHODS: Under appropriate anesthesia, deep, wide defects were created within the mandibles of two large dogs. Buccolingual bone was removed to the depth of the defects leaving only the mesial and distal walls. Of the eight implants placed, three were augmented with titanium-reinforced expanded polytetrafluoroethylene (e-PTFE) barriers and autogenous bone chips. Three sites were augmented with barrier membranes only, and two sites were not augmented or grafted and served as controls. Seven months after surgery the dogs were sacrificed and block sections were taken for histologic evaluation. RESULTS: Histologic and histomorphometric measurements were used to evaluate new bone formation. Results from this evaluation revealed bone formation at the membrane-only sites and the membrane-plus-bone grafted sites. The bone grafts were completely incorporated by the newly formed marginal compact bone. For all treated sites, there was poor bone-to-implant contact. Histomorphometric measurements showed a trend toward greater bone formation at membrane-treated sites compared with control sites. However, autogenous bone grafting did not seem to affect the amount of newly regenerated bone. CONCLUSIONS: Within the limits of this pilot project, findings show trends toward bone healing, indicating constant and enhanced bone regeneration over the exposed implant. Bone contact to the implant surface generally was poor.

Animals↗

PubMed1999

Two Xenopus proteins that bind the 3' end of histone mRNA: implications for translational control of histone synthesis during oogenesis.

Translationally inactive histone mRNA is stored in frog oocytes, and translation is activated at oocyte maturation. The replication-dependent histone mRNAs are not polyadenylated and end in a conserved stem-loop structure. There are two proteins (SLBPs) which bind the 3' end of histone mRNA in frog oocytes. SLBP1 participates in pre-mRNA processing in the nucleus. SLBP2 is oocyte specific, is present in the cytoplasm, and does not support pre-mRNA processing in vivo or in vitro. The stored histone mRNA is bound to SLBP2. As oocytes mature, SLBP2 is degraded and a larger fraction of the histone mRNA is bound to SLBP1. The mechanism of activation of translation of histone mRNAs may involve exchange of SLBPs associated with the 3' end of histone mRNA.

Amino Acid Sequence↗

PubMed1999

Stem-loop binding protein facilitates 3'-end formation by stabilizing U7 snRNP binding to histone pre-mRNA.

The 3' end of histone mRNA is formed by an endonucleolytic cleavage of the primary transcript after a conserved stem-loop sequence. The cleavage reaction requires at least two trans-acting factors: the stem-loop binding protein (SLBP), which binds the stem-loop sequence, and the U7 snRNP that interacts with a sequence downstream from the cleavage site. Removal of SLBP from a nuclear extract abolishes 3'-end processing, and the addition of recombinant SLBP restores processing activity of the depleted extract. To determine the regions of human SLBP necessary for 3' processing, various deletion mutants of the protein were tested for their ability to complement the SLBP-depleted extract. The entire N-terminal domain and the majority of the C-terminal domain of human SLBP are dispensable for processing. The minimal protein that efficiently supports cleavage of histone pre-mRNA consists of 93 amino acids containing the 73-amino-acid RNA-binding domain and 20 amino acids located immediately next to its C terminus. Replacement of these 20 residues with an unrelated sequence in the context of the full-length SLBP reduces processing >90%. Coimmunoprecipitation experiments with the anti-SLBP antibody demonstrated that SLBP and U7 snRNP form a stable complex only in the presence of pre-mRNA substrates containing a properly positioned U7 snRNP binding site. One role of SLBP is to stabilize the interaction of the histone pre-mRNA with U7 snRNP.

Animals↗