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Biomedical subjects

L Oliveira

Publications and source records attributed to L Oliveira.

At least 55 records · Page 3Linked to original sources
PubMed1997

Are interpretations of video defecographies reliable and reproducible?

Video defecography is a dynamic investigation which can influence surgical decision making in constipated patients. A study was therefore undertaken to assess the inter and intraobserver variability in video defecography. Specifically, we sought to assess the interpretation of video defecographies by a group of observers with the same training, guidelines and standards. To determine interobserver variation, four independent observers, two blinded to the patient's history, reviewed 100 randomly sequenced video defecographies performed in constipated patients. The presence or absence of sigmoidocele, rectocele, intussusception or prolapse was noted. Adequate or improper function of the puborectalis, anal canal opening, anorectal angle (ARA) and grade of emptying of the rectum were also assessed. Two weeks after the initial assessment, intraobserver variation was determined by a repeat blinded review of unlabelled randomly sequenced studies. The results of interobserver accuracy for sigmoidoceles, rectoceles, intussusception, rectal prolapse, rectal emptying, opening of the anal canal, puborectalis contraction and straightening of the ARA and rectal emptying were 89.5%, 46.0%, 87.5%, 97.5%, 86.5%, 88.5%, 83.0%, and 80.0%, respectively. The intraobserver variations were 88.5%, 83.8%, 80.5%, 94.5%, 77.0%, 84.8%, 80.5% and 85.5%, respectively. Prior knowledge of the patient's history did not significantly influence the outcome. In summery, video defecography has an overall accuracy of 83.3% and as such is a valid tool in assessing constipated patients.

Adolescent↗
PubMed1997

Laparoscopic creation of stomas.

BACKGROUND: Some indications for laparoscopic bowel surgery are still controversial. However, the use of laparoscopic techniques for the treatment of benign disorders is less often challenged. Moreover, the morbidity of nonresectional procedures is less than that encountered with resectional cases. Therefore, stoma creation seems ideally suited to laparoscopy. The aim of our study was to assess the outcome of laparoscopic stoma creation. METHODS: All patients who underwent laparoscopic intestinal diversion were evaluated; parameters included age, gender, indication for the procedure, history of previous surgery, operative time, length of hospitalization, recovery of bowel function, and postoperative complications. RESULTS: Between March 1993 and January 1996, 32 patients of a mean age of 42.2 (range 19-72) years (14 males, 18 females) underwent elective laparoscopic fecal diversion (25 loop ileostomy, four loop colostomy, three end colostomy). Indications for fecal diversion were fecal incontinence (n = 11), Crohn's disease (n = 6), unresectable rectal cancer (n = 4), pouch vaginal fistula (n = 3), rectovaginal fistula (n = 2), colonic inertia (n = 2), radiation proctitis (n = 1), anal stenosis (n = 1), Kaposi's sarcoma of the rectum (n = 1), and tuberculous fistula (n = 1). Conversion was required in five patients (15.6%) due to the presence of adhesions (three), enterotomy (one), or colotomy (one). All of these five patients had undergone previous abdominal surgery and were operated on early in our experience. Major postoperative complications occurred in two patients (6%) and in both cases consisted of stoma outlet obstruction after construction of a loop ileostomy. One of the two patients had undergone prior surgery. This patient required reoperation, at which time a rotation of the terminal ileum at the stoma site was found. The other patient had a narrow fascial opening which was successfully managed with 2 weeks of self-intubation of the stoma. The mean operative time was 76 (range 30-210) min; mean length of hospitalization was 6.2 (range 2-13) days; stoma function started after a mean of 3.1 (range 1-6) days. Patients with previous abdominal surgery had a longer mean operative time (14/32; 117 min) compared to patients who had no previous surgery (18/32; 55 min) (p < 0.0002). These longer operative times and hospital stay were attributable to extensive enterolysis, which was required in some cases. CONCLUSION: In conclusion, laparoscopic creation of intestinal stomas is safe, feasible, and effective. Although the length of the procedure is longer in patients who have had prior surgery, previous surgery is not a contraindication, and even in these cases, a laparotomy can be avoided in the majority of patients. Lastly, care must be taken to ensure adequate fascial opening and correct limb orientation.

Adolescent↗
PubMed1997

Anomalies of the CD8+ T cell pool in haemochromatosis: HLA-A3-linked expansions of CD8+CD28- T cells.

The present study consists of a phenotypic and functional characterization of peripheral blood T lymphocytes in a group of 21 patients with hereditary haemochromatosis (HH), an MHC class I-linked genetic disease resulting in iron overload, and a group of 30 healthy individuals, both HLA-phenotyped. The HH patients studied showed an increased percentage of CD8+ CD28- T cells with a corresponding reduction in the percentage of CD8+ CD28+ T cells in peripheral blood relative to healthy blood donors. No anomalies of CD28 expression were found in the CD4+ subset. The presence of the HLA-A3 antigen but not age accounted for these imbalances. Thus, an apparent failure of the CD8+ CD28+ T cell population 'to expand', coinciding with an 'expansion' of CD8+ CD28- T cells in peripheral blood of HLA-A3+ but not HLA-A3- HH patients was observed when compared with the respective HLA-A3-matched control group. A significantly higher percentage of HLA-DR+ but not CD45RO+ cells was also found within the peripheral CD8+ T cell subset in HH patients relative to controls. Phytohaemagglutinin (PHA) stimulation of peripheral blood mononuclear cells (PBMC) for 5 days showed: (i) that CD8+ CD28+ T cells both in controls and HH were able to expand in vitro; (ii) that CD8+ CD28- T cells decreased markedly after activation in controls but not in HH patients. Moreover, functional studies showed that CD8+ cytotoxic T lymphocytes (CTL) from HH patients exhibited a diminished cytotoxic activity (approx. two-fold) in standard 51Cr-release assays when compared with CD8+ CTL from healthy controls. The present results provide additional evidence for the existence of phenotypic and functional anomalies of the peripheral CD8+ T cell pool that may underlie the clinical heterogeneity of this iron overload disease. They are of particular relevance given the recent discovery of a novel mutated MHC class I-like gene in HH.

Adult↗
PubMed1997

Identification of class-determining residues in G protein-coupled receptors by sequence analysis.

G protein-coupled receptors (GPCRs) form a large superfamily of receptors that are characterised by a seven transmembrane helical motif. The functions they perform, such as binding ligands and G proteins, are related to the presence of certain amino acids in critical positions. We have developed a computational sequence pattern correlation technique for the recognition of such function-determining residues. The method searches for residues that are conserved in one class of proteins with a certain function but are different in other classes. The basic idea is that such residues are probably involved in this particular function. This technique was used to find residues that play a role in the binding of endogenous as well as exogenous ligands to various receptors. Many of the residues that were detected have been experimentally determined as important for ligand binding. More importantly, however, we also detected residues that are interesting targets for future mutation studies aimed at elucidating the sequence-function relationship in GPCRs. The information obtained may help improve three-dimensional GPCR models and can be useful for the study of receptor-ligand interactions.

Amino Acid Sequence↗
PubMed1996

Gene structure and chromosome localization to 7q21.3 of the human rod photoreceptor transducin gamma-subunit gene (GNGT1).

The transducin gamma-subunit gene (GNGT1) encodes a member (gamma1) of the family of heterotrimeric G-protein gamma-subunits that is specific to rod photoreceptors. In this report we have determined the complete structure of the GNGT1 gene and have localized it to human chromosome 7q21.3 using somatic cell hybrid and yeast artificial chromosome analysis.

Amino Acid Sequence↗
PubMed1996

The beta subunit of human rod photoreceptor cGMP-gated cation channel is generated from a complex transcription unit.

Human and bovine rod photoreceptor cGMP-gated cation channel consists of two subunits: alpha (63 kDa) and beta (240 kDa). The human beta subunit was shown to consist partly of sequence encoded by the cDNA clone hRCNC2b. Here we present the complete sequence of the human beta subunit and demonstrate that the previously reported human GAR1 gene encoding a glutamate-rich protein (hGARP) encodes its N-terminal portion. Using PCR, RNA blot and genomic DNA analysis, we provide evidence that the beta subunit is produced from a complex locus on chromosome 16 which is also capable of generating independent transcripts corresponding to GAR1 and the C-terminal two-thirds of the beta subunit. The results indicate that the beta subunit of the cGMP-gated cation channel is produced from an unusual locus consisting of more than one transcription unit.

Alternative Splicing↗
PubMed1996

Physiological and clinical outcome of anterior sphincteroplasty.

A total of 55 women underwent sphincteroplasty for the treatment of faecal incontinence related to anterior defects. Patients were followed prospectively for a mean of 29 months to evaluate the outcome overall and according to age. All patients were evaluated clinically by means of a questionnaire and graded using an incontinence scoring system ranging from 0 (perfect continence) to 20 (complete incontinence). Some 52 patients (95 per cent) had had a previous vaginal delivery and 30 (55 per cent) had a history of previous anal sphincter repair. Physiological and functional parameters in patients with a successful outcome (n = 39) were compared with those in patients with a poor outcome (n = 16). The results were also compared in patients under (n = 39) and over (n = 16) 60 years of age. Overall, patients with a successful outcome had a significant change in mean and maximal resting and squeeze pressures. These changes correlated well with the increase in the high-pressure zone (HPZ) length from 1.0-2.2 cm (P = 0.0002) and with functional outcome (change in incontinence score from 15.3 to 5.8; P < 0.0001). In patients over 60 years of age, a significant change in mean squeeze pressure (P = 0.03) and HPZ length (P = 0.01) was noted and correlated with functional outcome (change in incontinence score from 14.3 to 6.4; P < 0.0001). A successful outcome after anterior sphincteroplasty is related to improvement in sphincter function even in an older population. These results demonstrate that age itself does not seem to be a predictor of poor outcome. Patients should not be denied a repair exclusively on grounds of age.

Adult↗
PubMed1996

Pulmonary function after laparoscopic cholecystectomy in the elderly.

The results of laparoscopic cholecystectomy in a group of 52 patients older than 69 years (group 1) were compared with the results of the same operation in a group of 338 younger patients (group 2). In group 1, 23 per cent of patients had acute cholecystitis and 13 per cent were operated on after an episode of acute pancreatitis. In group 2, 8 per cent of patients had acute cholecystitis and 4 per cent were operated on after acute pancreatitis. Pulmonary function was assessed prospectively before operation, 24 h after surgery and on the seventh day after operation, in 20 patients in group 1 and 30 in group 2. In group 1 there was one death (2 per cent); the morbidity rate was 14 per cent and conversion to laparotomy was required in 15 per cent. In group 2 there were no deaths, the morbidity rate was 11 per cent and the conversion rate 4 per cent. No significant differences were found between the two groups in mortality and morbidity rates. Preoperative values of forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were significantly lower in group 1 than in group 2 (P < 0.05); the values of FVC, FEV1 and forced expiratory flow at 50 per cent 24 h after surgery were less depressed in group 1 (P < 0.01) and also recovered more quickly in these patients 7 days after operation. Laparoscopic cholecystectomy gives excellent results in geriatric patients and can be recommended as the treatment of choice for symptomatic cholelithiasis in the elderly.

Aged↗
PubMed1996

Role of monocytes in the up-regulation of the early activation marker CD69 on B and T murine lymphocytes induced by microbial mitogens.

CD69 is an early marker of lymphoid cell activation. The authors report on an up-regulation of CD69 in splenic B and T cells of C57Bl/6 mice after administration of lipopolysaccharide (LPS) or microbial immunosuppressive/mitogenic (ISM) proteins produced by C. albicans (p43) and African Swine Fever Virus (p36). This up-regulation of CD69 was observed 6 and 24 h after mitogenic treatments. The same pattern of increased CD69 expression was observed in the lymph nodes of mice treated with p43 or LPS, whereas p36 treatment failed to induce increased CD69 expression in this organ. Intracellular calcium mobilization was induced in splenic B and T lymphocytes after incubation of total spleen cells with LPS, p43 or p36. This increase was higher in B than in T cells. Increased calcium mobilization was also seen in lymph node B cells after incubation with p43 or p36 and in lymph node T cells after p43 stimulation. Up-regulation of CD69 expression on B and T cells was also observed after in vitro stimulation of spleen cells with the three mitogens used. Similar results were obtained with culture supernatants of macrophage/monocyte (M phi) cells activated with LPS (LPS/M phi CS). Stimulation of M phi cells with LPS or with the ISM proteins is demonstrated by the increased production of nitrites by these cells. The increased in vitro expression of CD69 was, however, not abolished by monoclonal antibodies to M phi cytokines such as IL-6, IL-10 or TNF alpha. No increased expression of CD69 was found in vitro on purified B or T cells, even when mixed upon stimulation with p43, p36, LPS or with LPS/M phi CS. However, an increase in the expression of CD69 was observed on B cells co-cultured with M phi cells after treatment with LPS or p36. All three mitogens failed to induce increased CD69 expression on cultured T cells mixed with M phi cells.

African Swine Fever Virus↗
PubMed1996

Laparoscopically assisted sigmoid colectomy in human immunodeficiency virus (HIV) patients: a good indication for laparoscopic surgery.

Laparoscopic colorectal procedures have been accepted for a variety of conditions. We present two cases of HIV-positive who underwent laparoscopic sigmoid colectomy and creation of a stoma for the treatment of sigmoid cancer and disseminated colorectal kaposi sarcoma, respectively. Laparoscopy may be a good option in selected HIV-positive patients.

Adenocarcinoma↗
PubMed1995

cDNA, gene structure, and chromosomal localization of human GAR1 (CNCG3L), a homolog of the third subunit of bovine photoreceptor cGMP-gated channel.

A unique glutamic acid-rich protein was previously identified in bovine rod photoreceptors (Sugimoto et al., 1991, Proc. Natl. Acad. Sci. USA 88: 3116-3119) and later suggested to be a third subunit (gamma) of the rod cGMP-gated cation channel (Chen et al., 1994, Proc. Natl. Acad. Sci. USA 91: 11757-11761). Here, we report on the characterization of the GAR1 gene encoding a human homolog of bovine gamma. Sequence analysis of cDNA clones encoding human gamma revealed an open reading frame predicting a protein of 299 amino acids (approximately 32 kDa), half the size of the bovine gamma subunit. Comparison of the N-terminal half of bovine gamma with the predicted human gamma sequence revealed 90% identity within the first 31 amino acids, and only 60% homology was found throughout the remainder of the protein sequence. As in bovine gamma, the predicted isoelectric point of the human protein is very acidic despite the absence of the bovine C-terminal glutamic acid-rich domain. The integrity of the cDNA sequence was confirmed by analysis of several overlapping genomic clones that span the GAR1 gene. The protein coding region of the gene consists of 12 exons spanning approximately 11 kb with exon sequence identical to that of the cDNA clones. PCR of somatic cell hybrid DNA with primer pairs that amplify a portion of the GAR1 gene (locus designation CNCG3L) demonstrate localization to chromosome 16. The location of the gene was further delimited by fluorescence in situ hybridization placing the gene at 16q13.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Fate in humans of dietary intake of cyanogenic glycosides from roots of sweet cassava consumed in Cuba.

We studied if consumption of boiled fresh roots from sweet cassava varieties grown in Cuba resulted in exposure to cyanogenic glycosides and their final breakdown product, cyanide. When adult, nonsmoking subjects consumed 1-4 kg cassava over 2 days, their urinary levels of the main cyanide metabolite, thiocyanate, only increased from a mean +/- SEM of 12 +/- 2 to 22 +/- 2 mumol/l, indicating a negligible cyanide exposure. Their mean urinary linamarin, the main cyanogenic glucoside in cassava, increased from 2 +/- 1 to 68 +/- 16 mumol/l. In a second experiment 5 subjects consumed one meal of 0.5 kg boiled cassava that contained 105 mumol linamarin and 8 mumol hydrogen cyanide (HCN). Quantitative urine collections prior to and after intake showed that 28% of linamarin was excreted during the following 24 hours, whereas a modest increase of urinary thiocyanate (SCN) only corresponded to the small amount of free HCN ingested. These results indicate that the dominant cyanogen in boiled cassava is glycosides that pass through the human body without causing cyanide exposure. It remains to be studied whether humans occasionally possess intestinal or tissue beta-glucosidases that can hydrolyse cyanogenic glycosides from cassava.

Adult↗
PubMed1995

Autosomal recessive retinitis pigmentosa caused by mutations in the alpha subunit of rod cGMP phosphodiesterase.

Retinitis pigmentosa (RP) constitutes a group of genetically heterogeneous progressive photoreceptor degenerations leading to blindness and affecting 50,000-100,000 people in the U.S. alone. Over 20 different RP loci have been mapped, of which six have been identified. Three of these encode members of the rod photoreceptor visual transduction cascade: rhodopsin, the rod cGMP-gated cation channel alpha subunit, and the beta subunit of cGMP-phosphodiesterase (PDEB). As null mutations in PDEB cause some cases of RP and since both alpha and beta subunits are required for full phosphodiesterase activity, we examined the gene encoding the alpha subunit of cGMP phosphodiesterase (PDEA) in 340 unrelated patients with RP. We found three point mutations in PDEA in affected members of two pedigrees with recessive RP. Each mutation alters an essential functional domain of the encoded protein and likely disrupts its catalytic function. PDEA is the seventh RP gene identified, highlighting the extensive genetic heterogeneity of the disorder and encouraging further investigation into the role of other members of the phototransduction cascade in RP.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1995

Potential ligand-binding residues in rat olfactory receptors identified by correlated mutation analysis.

A family of G-protein-coupled receptors is believed to mediate the recognition of odor molecules. In order to identify potential ligand-binding residues, we have applied correlated mutation analysis to receptor sequences from the rat. This method identifies pairs of sequence positions where residues remain conserved or mutate in tandem, thereby suggesting structural or functional importance. The analysis supported molecular modeling studies in suggesting several residues in positions that were consistent with ligand-binding function. Two of these positions, dominated by histidine residues, may play important roles in ligand binding and could confer broad specificity to mammalian odor receptors. The presence of positive (overdominant) selection at some of the identified positions provides additional evidence for roles in ligand binding. Higher-order groups of correlated residues were also observed. Each group may interact with an individual ligand determinant, and combinations of these groups may provide a multi-dimensional mechanism for receptor diversity.

Amino Acid Sequence↗
PubMed1994

Human retinal guanylate cyclase (GUC2D) maps to chromosome 17p13.1.

3',5'-Cyclic guanosine monophosphate is the intracellular second messenger regulating phototransduction in mammals. The level of cGMP in photoreceptor cells is controlled by the cGMP-hydrolyzing enzyme cGMP phosphodiesterase and the cGMP-producing enzyme guanylate cyclase. Identification of a photoreceptor-specific guanylate cyclase (retGC) that may function in visual transduction was recently reported. As an initial step in assessing the potential for defects in the retGC (GUC2D) gene to be causal of hereditary retinal disease, we have determined its chromosome location. A 720-bp region of the human GUC2D locus was amplified with exon-specific primers. The amplified product contains three introns, two intact exons, and part of two additional exons, suggesting a high degree of structural complexity. PCR analysis of human-rodent somatic cell hybrids was used to map the GUC2D locus to chromosome 17. This assignment was confirmed and a more precise localization to 17p13.1 was obtained by fluorescence in situ hybridization.

Animals↗