Search PubMed⌕ Search

Biomedical subjects

F Costa

Publications and source records attributed to F Costa.

At least 55 records · Page 3Linked to original sources
PubMed2000

Stability of Le Fort I osteotomy in maxillary inferior repositioning: review of the literature.

Inferior repositioning of the maxilla to correct vertical maxillary deficiency has been one of the more unstable orthognathic procedures performed. This kind of maxillary movement is the logical correction of short face syndrome due to maxillary vertical deficiency, but in spite of the esthetic improvement that it produces, a great tendency to relapse was observed. Unfortunately, the procedure is relatively rare, and this is reflected in the small sample of the studies. The literature concerning the stability of Le Fort I osteotomy in maxillary inferior repositioning was reviewed to analyze and discuss the stability of the surgical techniques proposed.

Animals↗
PubMed1999

Abnormal norepinephrine clearance and adrenergic receptor sensitivity in idiopathic orthostatic intolerance.

BACKGROUND: Chronic orthostatic intolerance (OI) is characterized by symptoms of inadequate cerebral perfusion with standing, in the absence of significant orthostatic hypotension. A heart rate increase of >/=30 bpm is typical. Possible underlying pathophysiologies include hypovolemia, partial dysautonomia, or a primary hyperadrenergic state. We tested the hypothesis that patients with OI have functional abnormalities in autonomic neurons regulating cardiovascular responses. METHODS AND RESULTS: Thirteen patients with chronic OI and 10 control subjects underwent a battery of autonomic tests. Systemic norepinephrine (NE) kinetics were determined with the patients supine and standing before and after tyramine administration. In addition, baroreflex sensitivity, hemodynamic responses to bolus injections of adrenergic agonists, and intrinsic heart rate were determined. Resting supine NE spillover and clearance were similar in both groups. With standing, patients had a greater decrease in NE clearance than control subjects (55+/-5% versus 30+/-7%, P<0.02). After tyramine, NE spillover did not change significantly in patients but increased 50+/-10% in control subjects (P<0.001). The dose of isoproterenol required to increase heart rate 25 bpm was lower in patients than in control subjects (0.5+/-0.05 versus 1.0+/-0.1 microg, P<0.005), and the dose of phenylephrine required to increase systolic blood pressure 25 mm Hg was lower in patients than control subjects (105+/-11 versus 210+/-12 microg, P<0.001). Baroreflex sensitivity was lower in patients (12+/-1 versus 18+/-2 ms/mm Hg, P<0.02), but the intrinsic heart rate was similar in both groups. CONCLUSIONS: The decreased NE clearance with standing, resistance to the NE-releasing effect of tyramine, and increased sensitivity to adrenergic agonists demonstrate dramatically disordered sympathetic cardiovascular regulation in patients with chronic OI.

Adult↗
PubMed1999

Impaired T-cell regulation of B-cell growth in Helicobacter pylori--related gastric low-grade MALT lymphoma.

BACKGROUND & AIMS: Neoplastic B cells of the Helicobacter pylori-related low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma are responsive to T helper cells and sensitive to withdrawal of H. pylori-induced T-cell help. METHODS: The clonal progeny of T cells from the gastric mucosa of 5 patients with MALT lymphoma was compared with that of T-cell clones obtained from 5 H. pylori-infected patients with chronic gastritis. RESULTS: T-cell clones were assessed for specificity to H. pylori, cytokine profile, help for B-cell proliferation, and perforin- or Fas-mediated cytotoxic regulation of B-cell growth. Twenty-eight of 165 CD4(+) gastric clones from MALT lymphoma and 33 of 178 CD4(+) clones from chronic gastritis recognized H. pylori antigens. Cytokine production was similar in the 2 series of clones. All MALT lymphoma-derived clones dose-dependently increased their B-cell help, whereas clones from chronic gastritis lost helper activity at T-to-B-cell ratios greater than 1 because of concomitant cytolytic killing of B cells. T-cell clones from MALT lymphoma had both reduced perforin-mediated cytotoxicity and poor ability to induce Fas-mediated apoptosis. These defects were limited to gastric T cells. CONCLUSIONS: H. pylori-induced T cell-dependent B-cell activation and deficient cytotoxic control of B-cell growth may link H. pylori infection, local T-cell response, and genesis of low-grade gastric MALT lymphoma.

Aged↗
PubMed1999

Helicobacter pylori stool antigen test: clinical evaluation and cost analysis of a new enzyme immunoassay.

Noninvasive tests for Helicobacter pylori are increasingly used. Recently, an enzyme immunoassay for H. pylori detection in feces has been put on the market. Aim of this multicenter study was to evaluate the usefulness of this novel test as a predictor of H. pylori status in the pretreatment setting. Three hundred consecutive patients were enrolled. None of the patients had received any eradicating treatment in the last 12 months, and all underwent gastroscopy with biopsies of the antrum and body for histology (H) and rapid urease test (RUT). H. pylori status was defined positive (or negative) if both H and RUT were positive (or negative). When H and RUT gave conflicting results, the patients were classified as H. pylori-indeterminate. A stool specimen was collected for each patient and tested by using a novel enzyme immunoassay for H. pylori detection (HpSAT). Sensitivity, specificity, and diagnostic accuracy of the test were calculated, as was the cost of each assay. H. pylori status was positive in 159 patients, negative in 131, and indeterminate in 10. HpSAT gave evaluable results (positive or negative) in 293 patients, and doubtful results in 7 (2.3%). Sensitivity, specificity, and diagnostic accuracy of HpSAT were 96.8%, 89.7%, and 93.6% respectively. Considering the H. pylori-indeterminate patients as positive, the percentages were 95.8%, 98.7%, and 93.2% respectively. The cost for each assay was about US $27. These results suggest that HpSAT is a noninvasive, simple, reliable, fast, and cheap method for evaluating H. pylori status in the pretreatment setting.

Antigens, Bacterial↗
PubMed1999

Comparison of antibody and protective immune responses against Trypanosoma cruzi infection elicited by immunization with a parasite antigen delivered as naked DNA or recombinant protein.

Immunization with naked DNA represents an attractive strategy for development of vaccines against a variety of infections including those caused by protozoan parasites. Recently, we have described that immunization with a plasmid containing the trans-sialidase (TS) gene induced protective immunity against Trypanosoma cruzi infection in BALB/c mice. The present study was aimed at examining and comparing the effectiveness of immunization using either plasmid or recombinant delivered antigens in a mouse strain highly susceptible to infection (A/Sn). Two plasmids were generated containing the coding region for the catalytic domain of TS. TS gene was inserted into pcDNA3 vector with or without the coding region for TS signal peptide. These two plasmids were found to be equally immunogenic at inducing antibodies to TS or inhibition of T. cruzi infection. A third plasmid, in which the TS gene was inserted into the vector VR1012, was as immunogenic as the two others. Immunization with a TS recombinant protein in alum generated a significantly higher antibody response as measured by ELISA or inhibition of TS enzymatic activity. Most relevant, this immunization reduced the mortality due to acute infection.

Animals↗
PubMed1999

Predominance of CD4 Th1 and CD8 Tc1 cells revealed by characterization of the cellular immune response generated by immunization with a DNA vaccine containing a Trypanosoma cruzi gene.

Immunization with a plasmid DNA containing the gene encoding the catalytic domain of trans-sialidase (TS) elicits protective immune responses against experimental Trypanosoma cruzi infection. As several studies provided strong evidence that during infection CD4 Th1 and CD8 T cytotoxic type 1 (Tc1) cells are important factors in host resistance, the present study was designed to evaluate which T-cell types were activated in DNA-vaccinated BALB/c mice. We found that bulk cells from DNA-immunized mice had CD4 and CD8 T cells that produced gamma interferon (IFN-gamma) but not interleukin-4 (IL-4) or IL-10. To characterize the TS-specific T cells at the clonal level, we generated CD4 and CD8 clones. We obtained cytotoxic CD4 clones of the Th1 type that secreted large amounts of IFN-gamma but not IL-4 or IL-10. Unexpectedly, we obtained other CD4 clones with a Th2 phenotype, secreting IL-4 and IL-10 but not IFN-gamma. All CD8 clones were cytotoxic and produced IFN-gamma. IL-4 and IL-10 were not secreted by these cells. Using synthetic peptides, we determined a CD8 epitope recognized by several clones as being represented by amino acids IYNVGQVSI. The antiparasitic activity of a CD4 Th1 and a CD8 Tc1 clone was assessed in vitro. CD4 or CD8 T cells significantly inhibited T. cruzi development in infected macrophages or fibroblasts, respectively. We concluded that DNA vaccine efficiently generates potentially protective CD4 Th1 and CD8 Tc1 cells specific for a T. cruzi antigen, therefore reinforcing the possibility of using this strategy for developing a preventive or therapeutic vaccine against Chagas' disease.

3T3 Cells↗
PubMed1999

Intravascular source of adenosine during forearm ischemia in humans: implications for reactive hyperemia.

It is believed that adenosine is released in ischemic tissues and contributes to reactive hyperemia. We tested this hypothesis in the human forearm using microdialysis to estimate interstitial and intravascular levels of adenosine and caffeine withdrawal to potentiate endogenous adenosine and determine its effect on reactive hyperemia. Forearm blood flow response to ischemia was measured by air plethysmography before and 60 hours after the last dose of caffeine (250 mg TID for 7 days, n=6). Forearm blood flow increased by 274+/-66% and 467+/-97% after 3 minutes of forearm ischemia, before and during caffeine withdrawal, respectively (P<0.05). Thus, caffeine withdrawal enhances reactive hyperemia. To determine the source of adenosine, we measured interstitial adenosine with the use of a microdialysis probe inserted into the flexor digitorum superficialis muscle of the forearm, and we measured intravascular adenosine with the use of a microdialysis probe inserted retrogradely into the medial cubital vein. Dialysate samples were collected at 15-minute intervals during resting, forearm ischemia, and recovery periods. Forearm ischemia failed to increase muscle dialysate concentrations of adenosine but did increase intravascular dialysate adenosine 2.1-fold, from 0.61+/-0.12 to 1.28+/-0.39 micromol/L (P<0.01, n=8). Intravascular dialysate concentrations of thromboxane B2 did not increase during ischemia, ruling out platelet aggregation as a source of adenosine. These results support the hypothesis that endogenous adenosine contributes to reactive hyperemia and indicate that the major source of adenosine in the human forearm is intravascular. We speculate that endothelial cells are the source of intravascular adenosine during ischemia.

Adenosine↗
PubMed1999

Trans-sialidase delivered as a naked DNA vaccine elicits an immunological response similar to a Trypanosoma cruzi infection.

Trypanosoma cruzi. the protozoan parasite that causes Chagas' disease, does not synthesize sialic acid, but expresses a trans-sialidase (TS) that catalyzes the transfer of sialic acid from host glycoconjugates to the parasite surface. Here, we review studies that characterize the immune response to the catalytic domain of the enzyme in humans during Chagas' disease or in mice following immunization with the TS gene. In both cases, there are antibodies that strongly inhibit the enzymatic activity and generation of interferon-gamma-producing T cells.

Animals↗
PubMed1999

Stability of Le Fort I osteotomy in maxillary advancement: review of the literature.

Stability of the skeletal segments repositioned during orthognathic surgery is still a concern in maxillofacial surgery. In an attempt to establish a consensus about one of the most frequently performed repositioning surgeries, the literature from 1985 to 1999 concerning stability of Le Fort I osteotomy in maxillary advancement was reviewed. There have been many problems in interpreting the results of the analysis because of differences in the design of the studies and the multifactorial nature of the disorder. For this reason each problem that emerged in the literature is analyzed and discussed.

Humans↗
PubMed1998

Immune response to an epitope of the NS4 protein of hepatitis C virus in HCV-related disorders.

NS4, a nonstructural protein of HCV, is a frequent target of antibodies in infected subjects. According to recent data, the antibodies frequently recognize the sequence 1921-40 of the NS4 protein. The aim of this work was to analyze antibody reactivity with the sequence 1921-40 in different HCV-related disorders. Although this sequence is located in a relatively invariant region of viral genome, two strain-specific sequences are described. Thus, three NS4 1921-1940 peptides were synthesized: the BK shared by most viral strains, the J6 (strain 2a), and the J8 (strain 2b). The peptides were used as antigens in the solid phase for measuring serum IgG antibodies in an ELISA assay. Antibodies reactive with the 1921-40 BK peptide were detected in 64% of sera from patients with autoimmune hepatitis (AIH), 51% from chronic hepatitis C (CHC), and 22% from mixed cryoglobulinemia (MC). The frequency of positive sera in MC was significatively lower than in AIH (P < 0.0001) or CHC (P < 0.0021). Similar results were obtained with the J6 and J8 peptides. All sera that did not react with the BK peptide were negative on J6 and J8 and conversely most sera reacting with the BK peptide also bound the J6 and the J8 peptides. No correlation was found between the genotype of the infecting virus and the presence of antibodies to any of the NS4 peptides. These results indicate that many HCV-infected subjects produce antibodies to the NS4 sequence 1921-40. The immune response to this sequence is not strain specific and varies with the different disorders associated with HCV infection.

Amino Acid Sequence↗
PubMed1998

Immunization with a plasmid DNA containing the gene of trans-sialidase reduces Trypanosoma cruzi infection in mice.

Trypanosoma cruzi, the protozoan parasite that causes Chagas' disease, does not synthesize sialic acid, but expresses a trans-sialidase that catalyses the transfer of sialic acid from host glycoconjugates to the parasite surface. Several lines of evidence suggest that this enzyme is a virulence factor implicated in the establishment of infection. Here we studied whether immunization with a plasmid DNA containing a gene encoding for the catalytic domain of the enzyme could elicit protective immunity against T. cruzi infection in mice. We observed that immunization with this plasmid DNA generated antibody and T-cell mediated immune responses. Antibodies recognized the native enzyme and inhibited its activity in vitro. Upon challenge with bloodstream trypomastigotes, immunized animals displayed reduced parasitemia and mortality.

Animals↗
PubMed1998

Truncal anaesthesia of the maxillary nerve for outpatient surgically assisted rapid maxillary expansion.

We present our experience of transcutaneous truncal anaesthesia of the maxillary nerve in association with transmucosal anaesthesia of the sphenopalatine ganglion in surgically assisted rapid maxillary expansion. Twelve patients with a skeletal transverse discrepancy of the maxilla were treated in our department from 1994 to 1995. Maxillary transcutaneous nerve block was done with a Quincke 8 cm spinal needle together with transmucosal anaesthesia of the sphenopalatine ganglion. Mepivacaine without adrenaline and sodium bicarbonate 1/10 was used for truncal anaesthesia and lidocaine-prilocaine cream for transmucosal anaesthesia. A Le Fort I osteotomy, lateral nasal wall osteotomy, pterygomaxillary osteotomy, and a palatal osteotomy were done for all patients before the maxillary expansion. Total anaesthesia of the maxillary area facilitated the operations and appreciably reduced the amount of postoperative pain. The ease of achieving effective anaesthesia before and after operation and the absence of side-effects make this form of anaesthetic particularly useful in surgically assisted rapid maxillary expansion.

Adolescent↗
PubMed1998

Simultaneous malaroplasty with porous polyethylene implants and orthognathic surgery for correction of malar deficiency.

PURPOSE: Patients with skeletal malrelationships caused by maxillary anteroposterior defect and midface hypoplasia may present with an alteration of cheekbone contour. High osteotomies, segmental osteotomies of the zygomatic complex, and malar expansion with alloplastic materials can be performed to improve facial aesthetics. This article describes the restoration of cheekbone-nasal base-lip contour by performing a malaroplasty using an alloplastic implant in addition to orthognathic surgery. PATIENTS AND METHODS: From 1995 to 1996, 17 patients with maxillomandibular malrelationships and deficient cheekbone contour were tested by malar augmentation with porous high-density polyethylene in association with maxillary advancement and mandibular setback. The diagnosis of cheekbone contour alteration was made after observing the patient from a lateral, frontal, and oblique point of view. The position of the implant was determined by using Mladick's point, with lateral or medial extension in relation to the depressed area. RESULTS: By the restoration of normal cheekbone-nasal base-upper lip contour produced excellent aesthetic results in all patients. CONCLUSIONS: Malaroplasty in association with bimaxillary orthognathic surgery seems to be an effective procedure for treating midface skeletal deficiencies.

Biocompatible Materials↗
PubMed1998

Gastric mucosal distribution and clinical efficacy of azithromycin in patients with Helicobacter pylori related gastritis.

The gastric mucosal distribution of azithromycin, the prototype of a new class of macrolide antibiotics named azalides, was studied in patients with duodenal ulcer and Helicobacter pylori-related gastritis. The time course of ulcer healing, H. pylori infection, and gastritis activity was also evaluated. Twenty patients (median age 50 years) received the following treatment for 1 month: three cycles of azithromycin (500 mg/day for 3 consecutive days) on days 1-3, 11-13 and 21-23 plus omeprazole (40 mg/day) for 30 consecutive days. Endoscopic biopsy specimens of gastric mucosa and blood samples were collected on days 0, 4, 7, 10, 20 and 30. An additional follow-up endoscopy was carried out on day 60. H. pylori infection was determined by both histology and rapid urease test. Azithromycin concentrations in both plasma and gastric mucosa were measured by a microbiological plate assay, using Micrococcus luteus NCTC 8440 as the reference organism. Azithromycin concentrations in plasma ranged between 0.17 mg/L (95% CI: 0.08-0.26; n = 5) and 0.32 mg/L (95% CI: 0.21-0.43; n = 5) throughout the treatment period. In addition, azithromycin concentrations in gastric mucosa were significantly higher than plasma concentrations at all times examined and ranged from 18.5 mg/kg (95% CI: 15-20; n = 20) to 24.6 mg/kg (95% CI: 16.8-32.4; n = 5), Indicating that the drug was highly retained in the target tissue. Accordingly, the ratio of azithromycin mucosal level to plasma concentration varied between 77.9 (95% CI: 56.5-99.3; n = 5) and 112.7 (95% CI: 100.2-125.2; n = 5). At the end of treatment (day 30) H. pylori was no longer detected in 16 of 20 patients (80%), and this finding was consistent with a marked decrease in the grading of gastritis activity. At the follow-up endoscopy (day 60) the infection was eradicated in only four patients (20%). These data indicate a favourable distribution of azithromycin into gastric mucosa of patients with H. pylori infection and suggest that this new macrolide antibiotic represents a valuable option for treatment regimens against H. pylori. However, the low eradication rate achieved with azithromycin plus omeprazole is a source of concern and requires further investigation.

Adult↗