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Biomedical subjects

A Silva

Publications and source records attributed to A Silva.

At least 73 records · Page 4Linked to original sources
PubMed1998

Overexpression of a mutant B subunit in toxigenic Vibrio cholerae diminishes production of active cholera toxin in vivo.

A mutant cholera toxin B subunit containing a G33E substitution was constructed and expressed in V. cholerae. The G33E amino acid substitution did not affect the amount of recombinant CTB secreted to the culture medium. The overexpression of the mutant B subunits in wild-type toxigenic cholera vibrios led to an 80% decrease in production of active cholera toxin in vitro and in vivo. Overexpression of BG33E subunits could be instrumental in the increase of the biosafety of live attenuated cholera candidate vaccine strains.

Amino Acid Substitution↗
PubMed1998

Glutathione S-transferase of goat lens: evidence for expression of only class mu isoenzymes.

PURPOSE: It has been suggested that glutathione S-transferases (GSTs) of the mammalian ocular lens detoxify various toxicants and cataractogens; therefore, it provides protection against cataractogenesis. In this study the GST isoenzymes of goat lens have been purified and characterized. METHODS: The goat lens homogenate was subjected to affinity chromatography over GSH-linked epoxy activated Sepharose 6B. The isoenzymes of the GST were separated by chromatofocusing on a Mono-P column using FPLC. RESULTS: Two GST isoenzymes, GST 7.2 and GST 6.6, were purified to apparent homogeneity from goat lens. GST 7.2 appeared to be a heterodimer of Mr. 26,500 and Mr. 25,000 subunits, the GST 6.6 showed a homodimeric subunit structure of Mr. 25,000. Western blotting and the N-terminal region amino acid sequence analysis indicated that both isoenzymes of goat lens belong to the mu-class GST. CONCLUSION: Although they share varying degrees of structural correlation, the two isoenzymes of goat lens seem to be the products of two distinct genes. The isoenzyme expression pattern of GST in goat lens is similar to bovine lens, which also contains two isoenzymes belonging only to GST mu.

Animals↗
PubMed1998

Production and characterization of a monoclonal antibody against mannose-sensitive hemagglutinin of Vibrio cholerae.

We have generated murine monoclonal antibodies (MAb) against Vibrio cholerae mannose-sensitive hemagglutinin (MSHA) using conventional hybridoma procedures. Seven hybridomas were obtained and one characterized. Hybridoma 2F12/F1 secreted an antibody of the IgG3 type that reacted with a 17-kDa antigen corresponding to the product of the mshA gene. This MAb inhibited mannose-sensitive agglutination of chicken erythrocytes by EL tor and O139 vibrios. Vibrios expressing MSHA activity inhibited binding of the antibody secreted by 2F12/F1 to MSHA-coated microtiter plates.

Animals↗
PubMed1998

[Organization of a central supply unit].

This study presents the central supply unit in the hospital taking into consideration organizing aspects related to its dimension, areas, material and human resources.

Central Supply, Hospital↗
PubMed1998

[The blue rubber bleb nevus syndrome or Bean's syndrome. A rare cause of digestive hemorrhage].

A 71-year-old male who had previously suffered from chronic alcoholism was admitted to the Internal Medicine Service of Coimbra Hospital Center in January 1996 due to asthenia, loss of weight, icterus and abdominal pain, clinical features that had begun six months before admittance to hospital. A physical examination revealed that, in addition to icterus, the patient presented multiple hemangiomas of 1 to 5 cm in diameter, located in the oral cavity, neck, breast and left axilla. These lesions were bluish, elevated and with a rubber-nipple consistency, and had been developing for about 15 years. Subsequent examination revealed normocytic normochromic anemia, cholestatic icterus and the existence of a gastrointestinal hemangioma located in the esophagus. Excisional biopsy of an element proved that it was cavernous hemangioma. A subsequent angio-scintigraphy indicated other aspects suggestive of deep hemangiomas located in the legs, face and cervical region. The authors had the opportunity of examining other members of the patient's family, who apparently did not exhibit similar lesions. They concluded that it was a case of blue rubber bleb nevus syndrome (BRBNS), probably in its sporadic form. Treatment was essentially conservative and the patient is well.

Aged↗
PubMed1998

[Cutaneous reconstruction at the leg and foot level. Experience in 277 clinical cases].

The authors present their clinical experience of leg and foot reconstruction with 227 clinical cases. Based on these cases the authors analyse the use of 18 musculocutaneous, 53 axial, 72 septocutaneous and 84 free flaps, totalling 29 different kinds of flaps performed. Although no definitive conclusions can be drawn about which are the best flaps for foot and leg reconstruction, the preferential options are pointed out.

Adolescent↗
PubMed1998

[Revascularization and reimplantation of the upper extremity. 15-year-experience with 114 cases].

Progress in micro or macro replantation has resulted in higher survival rates of formerly amputated parts. More amputated digits or limbs survive because the time of ischemia can be exceeded by using cold storage or perfusion. Homo or heterodigital vessel transposition, expanded indications for vein graft interposition, as well as heterotopic transplantation allow for extremity preservation even in crush injuries, and in disastrous multiple amputations combined with contusion or avulsion. Secondary reconstruction with regard to bone defects, tendon repair, and eventual nerve grafting have to be aspired, finally leading to an improvement of functional results in daily and leisure activities as well as in early professional readaptation. A total of 114 microvascular extremity replantations/revascularizations with a survival rate of 77.2% were followed for an average of 15 years.

Accidents, Occupational↗
PubMed1998

A longitudinal analysis of nursing home outcomes.

OBJECTIVE: To investigate resident and facility attributes associated with long-term care health outcomes in nursing homes. DATA SOURCES: Quarterly Management Minutes Questionnaire (MMQ) survey data for Medicaid case-mix reimbursement of nursing homes in Massachusetts from 1991 to 1994, for specification of outcomes and resident attributes. Facility attributes are specified from cost report data. STUDY DESIGN: Multivariate logistic and "state-dependence" regression models are estimated for survival, ADL functional status, incontinence status, and mental status outcomes from longitudinal residence histories of Medicaid residents spanning 3 to 36 months in length. Outcomes are specified to be a function of resident demographic and diagnostic attributes and facility-level operating and nurse staffing attributes. PRINCIPAL FINDINGS: The estimated parameters for resident demographic and diagnostic attributes showed a great deal of construct validity with respect to clinical expectations regarding risk factors for adverse outcomes. Few facility attributes were associated with outcomes generally, and none was significantly associated with all four outcomes. CONCLUSIONS: The absence of uniform associations between facility attributes and the various long-term care health outcomes studied suggests that strong facility performance on one health outcome may coexist with much weaker performance on other outcomes. This has implications for the aggregation of individual facility performance measures on multiple outcomes and the development of overall outcome performance measures.

Activities of Daily Living↗
PubMed1998

[Revascularization in patients with prior coronary bypass surgery].

UNLABELLED: Increasingly over the past several years, patients have returned after coronary surgery for reintervention procedures. This reflects immediate postsurgical complications and the relentless progression of coronary artery disease in the native circulation and in the bypass grafts. Although there are randomized comparative data for coronary bypass surgery (CABG) versus percutaneous transluminal coronary angioplasty (PTCA) and medical therapy, these trials have always excluded patients with previous (GABG). OBJECTIVES: We attempted to compare the risks and benefits of percutaneous transluminal coronary angioplasty (PTCA) and repeat coronary artery bypass grafting (re-CABG) in patients with previous coronary bypass surgery (CABG). METHODS AND RESULTS: This study examines follow up data (15.4 +/- 11.0 months) from 130 patients with previous CABG, who required either PTCA (Group A, n = 73) or re-CABG (Group B; n = 57) at a single center from 1994 to 1997. Follow up data were obtained from subsequent office visits and telephone calls. The PTCA and re-CABG groups were similar with respect to gender (86% vs 94% males), mean age (62 +/- 9 vs 59 +/- 10 years), angina CCS classes 3 and 4 (73% vs 69%), diminished left ventricular function (23% vs 26%), risk factors such as diabetes (19% vs 17%), hypercolesterolemia (49% vs 45%) and smoking (48% vs 39%) and three-vessel native coronary artery disease (67% vs 72%). The symptomatic status prior to the revascularization procedure was similar in both groups. Complete and functional revascularization was achieved in 85% of the PTCA group and in 92% of those with re-CABG (p = NS). During the hospital stay the complication rates were lower in the PTCA group. Actuarial survival was different at follow up (p = 0.04). Both PTCA and re-CABG groups resulted in equivalent event-free survival (freedom from death, myocardial infarction, unstable angina and urgent revascularization). The need for repeat revascularization at follow up was significantly higher in the PTCA group (PTCA 28% vs re-CABG 10%, p < 0.01). CONCLUSIONS: In this non-randomized study of patients with previous CABG requiring revascularization procedures, PTCA resulted in lower procedural morbidity and mortality risks. At follow up, both PTCA or CABG were similar for event-free survival; PTCA offered lower overall mortality, although it is associated to a greater need for subsequent revascularization procedures.

Aged↗
PubMed1997

DNA immunization: induction of higher avidity antibody and effect of route on T cell cytotoxicity.

Immunizations of mice with plasmid DNAs encoding ovalbumin (OVA), human Ig, and hen egg lysozyme were compared with doses of soluble protein (without adjuvant) that induced similar IgG responses. The route of immunization influenced the magnitude of the antibody (Ab) response in that intradermal (i.d.) injection elicited higher IgG Ab levels than i.m. injection in both DNA- and protein-immunized mice. Although total IgG levels were similar to soluble protein controls, the avidity of the anti-OVA Abs generated by DNA immunization were 100- and 1,000-fold higher via the i.m. or i.d. route, respectively. However, despite the generation of high-avidity Ab in DNA-immunized mice, germinal centers could not be detected in either DNA- or protein-immunized mice. Examination of the IgG subclass response showed that IgG2a was induced by i.m. DNA immunization, coinciding with elevated interferon gamma production, whereas a dominant and elevated IgG1 response, coinciding with detectable interleukin 4 production, was generated after i.d. immunization with DNA or soluble OVA and hen egg lysozyme but not human Ig protein. As expected, cytotoxic T cell (CTL) responses could be detected only after DNA immunization. I.d. immunization produced the strongest CTL responses early (2 weeks) but was similar to i.m. later. Therefore, DNA immunization can differ from protein immunization by its ability to induce rapid CTL responses and higher avidity Ab, both of which are advantageous for vaccination.

Animals↗
PubMed1997

p53 is not required for regulation of apoptosis or radioprotection by interleukin-3.

Primary interleukin-3 (IL-3)-dependent mast cell cultures from bone marrow of p53-null mice and littermate controls were established. Both p53-null and wild-type cells entered apoptosis on IL-3 removal, showing that p53 is not required for entry into apoptosis after factor deprivation. After X-irradiation, a lower proportion of the p53-null than wild-type cells underwent G2 arrest, but their radiosensitivity was similar. An IL-3-dependent cell line expressing wild-type p53 was used to show that cells die at a fixed time after X-irradiation rather than from a specific cell cycle point.

Animals↗
PubMed1997

Age-dependent decrease of synaptic plasticity in the neocortex of alphaCaMKII mutant mice.

Synaptic long-term potentiation (LTP) and long-term depression (LTD) were studied in the visual cortex of mutant mice lacking alpha-calcium/calmodulin-dependent protein kinase II (alphaCaMKII). In adult mutants, little LTD or LTP could be elicited using standard conditioning protocols. However, substantial LTD and LTP were induced in 4- to 5-week-old mutants. Thus, the reduction in cortical plasticity in alphaCaMKII (-/-) mice is conditional, with the relevant condition being postnatal age.

Aging↗
PubMed1997

IL-2 signaling controls actin organization through Rho-like protein family, phosphatidylinositol 3-kinase, and protein kinase C-zeta.

IL-2 and IL-4 induce proliferation of TS1 alpha beta cells. Activation of the zeta isoform of protein kinase C is an important step in IL-2-, but not IL-4-mediated proliferation. In addition, protein kinase C-zeta is implicated in IL-2-mediated actin organization. Given the established involvement of the Rho family of small guanine nucleotide-binding proteins in organization of actin structures, we analyze the possible relationships between Rho and protein kinase C-zeta. Using the Rho-like protein family-specific toxin B from Clostridium difficile, we report in this work that IL-2, but not IL-4, induces a Rho-dependent activation of protein kinase C-zeta. This signaling event is mediated by the activation of phosphatidylinositol 3-kinase. In contrast, IL-4 induces a Rho-independent, phosphatidylinositol 3-kinase-mediated activation of protein kinase C-zeta, but this pathway has no implications in cytoskeleton organization.

Actins↗
PubMed1997

Reverse dorsal metacarpal osteocutaneous flap.

There are a number of possibilities for local and vascularized bone transfer when a small amount of cortico-cancellous bone is required in the hand and fingers. The authors describe the dissection technique and a clinical application of a reverse dorsal metacarpal osteocutaneous flap to reconstruct the proximal phalanx of a fifth finger. They emphasise the bone vascularisation, studied 48 hours postoperatively with a bone scan and confirmed with bone healing 4 weeks later. The advantages are: it is a compound flap, easy to dissect under tourniquet in one operation, it can be done in an emergency care situation and it does not require ligation of an important vascular axis. The essential precaution is to visualise the patency of the fourth dorsal metacarpal artery before flap dissection, acknowledging that in only 63% of cases is there a vascular pattern that allows flap dissection with a long arc of rotation.

Bone Transplantation↗