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Biomedical subjects

Y Silva

Publications and source records attributed to Y Silva.

At least 19 recordsLinked to original sources
PubMed2004

Early neurologic deterioration in intracerebral hemorrhage: predictors and associated factors.

OBJECTIVE: To identify potential predictors of and factors associated with early neurologic deterioration (END) in primary intracerebral hemorrhage (ICH). METHODS: Two hundred sixty-six patients with spontaneous supratentorial ICH admitted within 12 hours of stroke onset were investigated in a multicenter, prospective study. Sixty-one clinical, biochemical, and neuroimaging variables were registered on admission, and 37 clinical and neuroimaging variables were registered at 48 hours. The volumes of the ICH and peripheral edema on admission and at 48 hours were measured on CT scan. Stroke severity and functional outcome were evaluated with the Canadian Stroke Scale (CSS) and modified Rankin Scale. END was diagnosed when the CSS score decreased > or =1 points between admission and 48 hours. With use of logistic regression analyses, baseline variables that predicted END and factors measured after the early acute phase and associated with END were investigated. RESULTS: END occurred in 61 (22.9%) patients. Body temperature of >37.5 degrees C (odds ratio [OR] 24.5; 95% CI 4.8 to 125), neutrophil count (by 1,000-unit increase; OR 2.1; 95% CI 1.6 to 2.6), and serum fibrinogen levels of >523 mg/dL (OR 5.6; 95% CI 1.9 to 16.2) on admission were independent predictors of END. Among the factors recorded at 48 hours, early ICH growth (OR 4.3; 95% CI 1.3 to 14.5), intraventricular bleeding (OR 2.6; 95% CI 1.4 to 5.0), and highest systolic blood pressure (by 10-unit increase; OR 1.17; 95% CI 1.02 to 1.32) were associated with END in multivariate analyses. CONCLUSIONS: Clinical and biologic markers of the inflammatory reaction on admission are predictors of subsequent END, whereas early ICH growth, intraventricular bleeding, and high systolic blood pressure within 48 hours are factors associated with END in patients with spontaneous ICH.

Aged↗
PubMed2004

The clinical-DWI mismatch: a new diagnostic approach to the brain tissue at risk of infarction.

OBJECTIVE: To evaluate the usefulness of a mismatch between the severity of acute clinical manifestations and the diffusion-weighted imaging (DWI) lesion in predicting early stroke outcome and infarct volume. METHODS: One hundred sixty-six patients with a hemispheric ischemic stroke of <12 hours' duration were studied. The NIH Stroke Scale (NIHSS) score and the volume of DWI lesion were measured on admission and at 72 +/- 12 hours. Infarct volume was measured on T2-weighted or fluid-attenuated inversion recovery images at day 30. Early neurologic deterioration (END) was defined as an increase of > or =4 points between the two NIHSS evaluations. Thirty-eight patients received IV thrombolysis or abciximab. Clinical-DWI mismatch (CDM) was defined as NIHSS score of > or =8 and ischemic volume on DWI of < or =25 mL on admission. The adjusted influence of CDM on END, DWI lesion enlargement at 72 hours, and infarct growth at day 30 was evaluated by logistic regression analysis and generalized linear models. RESULTS: CDM was found in 87 patients (52.4%). Patients with CDM had a higher risk of END than patients without CDM because NIHSS < 8 (odds ratio [OR], 9.0; 95% CI,1.9 to 42) or DWI lesion > 25 mL (OR, 2.0; 95% CI, 0.8 to 4.9). CDM was associated with an increase of 46 to 68 mL in the mean volume of DWI lesion enlargement and infarct growth in comparison with non-CDM. All the effects were even greater and significant in patients not treated with reperfusion therapies. CONCLUSIONS: Acute stroke patients with an NIHSS score of > or =8 and DWI volume of < or =25 mL have a higher probability of infarct growth and early neurologic deterioration. The new concept of CDM may identify patients with tissue at risk of infarction for thrombolytic or neuroprotective drugs.

Aged↗
PubMed2003

Production and characterization of monoclonal antibodies to E1 Tor toxin co-regulated pilus of Vibrio cholerae.

Murine monoclonal antibodies (MAbs) against Vibrio cholerae toxin co-regulated pilus (TCP) were generated using conventional hybridoma procedures. Four hybridomas were obtained and two characterized. Hybridomas 10E10E1 and 4D6F9 secreted antibodies of the IgG2a and IgG1 isotypes, respectively, that reacted with a 24-kDa antigen corresponding to the product of the El Tor tcpA gene fused to a six Histidine tail. Additionally, MAbs produced by 4D6F9 selectively recognized the major pilin subunit (TcpA) of El Tor and O139 vibrios in western immunoblot, while MAbs from 10E10E1 also cross-reacted with classical TcpA. Furthermore, vibrios expressing TCP on their surface selectively inhibited binding of the antibodies secreted by both hybridomas to TcpA-coated microtiter plates. Thus, the MAbs reported in this work detected the structural subunit of the pilus either denatured or assembled on the bacterial surface.

Animals↗
PubMed2002

Molecular signatures of brain injury after intracerebral hemorrhage.

BACKGROUND: The mechanisms of cellular death in the tissue surrounding an intracerebral hemorrhage (ICH) are not defined. OBJECTIVE: To investigate the relationship of markers of excitotoxicity and inflammation to brain injury after ICH. METHODS: A total of 124 consecutive patients with spontaneous ICH admitted within 24 hours of stroke onset were prospectively investigated. The volumes of the initial ICH, peripheral edema on days 3 to 4, and the residual cavity at 3 months were measured on CT scan. Glutamate, cytokines, and adhesion molecules were measured in blood samples obtained on admission. Stroke severity and neurologic outcome were evaluated with the Canadian Stroke Scale. RESULTS: Poor neurologic outcome at 3 months (Canadian Stroke Scale < 7) was observed in 53 patients (43%). Stroke severity and glutamate concentrations (by each increment of 10 micromol/L, odds ratio 1.23; 95% CI 1.09 to 1.41), but not the initial volume of ICH, were independent predictors of poor outcome. In the multiple linear regression analyses, tumor necrosis factor-alpha concentration was correlated (r = 0.83, p < 0.0001) with the volume of perihematoma edema, and glutamate concentrations were correlated (r = 0.78, p < 0.0001) with the volume of the residual cavity. These same results were observed when lobar (n = 58) and deep (n = 66) ICH were analyzed separately. CONCLUSIONS: High plasma levels of proinflammatory molecules within 24 hours of intracerebral hemorrhage onset are correlated with the magnitude of the subsequent perihematoma brain edema, whereas poor neurologic outcome and the volume of the residual cavity are related to increased plasma glutamate concentrations.

Aged↗
PubMed2002

[Status cataplecticus induced by abrupt withdrawal of clomipramine].

INTRODUCTION: Cataplexy is one of the main narcoleptic symptoms and is characterized by sudden loss of muscle tone triggered by emotional stimuli while consciousness is mantained. Clomipramine is an effective treatment of cataplexy. Cataplexy that occurs repeatedly for hours or days is referred to as status cataplecticus. PATIENTS: We report three adults with narcolepsy in whom cataplexy was chronically and effectively treated with clomipramine (75-150 mg/day). For diverse reasons, these three patients had an abrupt withdrawal of clomipramine, and after 2-9 days patients showed an invalidant status cataplecticus characterized by a marked increase of the frequency, duration and severity of their cataplectic attacks that were now elicited by mild emotional stimuli. After introduction of anticataplectic agents (clomipramine in two patients and fluoxetine in one patient), status cataplecticus was resolved in less than a week. CONCLUSION: In patients with narcolepsy, abrupt withdrawal of chronic treatment with clomipramine may be associated with status cataplecticus. This condition may be resolved with the reintroduction of anticataplectic agents.

English Abstract↗
PubMed2001

Atherosclerotic aortic arch plaques in cryptogenic stroke: a microembolic signal monitoring study.

BACKGROUND AND PURPOSE: To find out the prevalence of relevant atherosclerotic plaques in the aortic arch and their potential role as a source of embolism in cryptogenic stroke. METHODS: We performed a transoesophageal echocardiography (TEE) on 49 patients with cryptogenic stroke from a total series of 212 non-selected patients with acute ischaemic stroke studied prospectively by cranial computed tomography (CT), colour-duplex and transcranial Doppler (TCD) sonography with micro-embolic signal (MES) monitoring. Cryptogenic stroke was diagnosed in those patients without carotid or intracranial stenosis > 50%, nor lacunar or cardio-embolic strokes. We defined relevant plaques as those > or = 4 mm thick located in the ascending aorta or proximal arch. RESULTS: Twenty-three patients (46.9%) had atherosclerotic aortic plaques (AAP): 3 in the ascending aorta (in 1 > or = 4 mm), 11 in the proximal aortic arch (in 4 > or = 4 mm) and 9 in the descending aorta (in 5 > or = 4 mm). Hence, 5 patients (10.2%) had relevant plaques. Aortic plaques were significantly related to older age (p < 0.001) and male gender (p = 0.042). A carotid artery stenosis < 50% was found in 39% of patients with AAP and in 8% of those without AAP (p = 0.009). MES were detected in 3 patients with plaques > or = 4 mm thick, but not in those without AAP or with AAP < 4 mm thick (p = 0.006). CONCLUSION: Although few patients with cryptogenic stroke had relevant plaques in our non-selected population, our results support the hypothesis that relevant aortic plaques have embolic potential.

Aged↗
PubMed2000

In-flight continuous vital signs telemetry via the Internet.

BACKGROUND: Current methods available to assess a passenger's life threatening medical condition during in-flight emergencies are inadequate. Critical communication channels between the airplane and ground control rely only on voice communication via a two-way radio. The purpose of this study was to test the efficacy of cellular telephone technology via the Internet as a cost-effective way to obtain the "linking" pathway from an aircraft to a ground medical facility by conducting a simulated on line triage. METHODS: On July 31, 1997, we transmitted vital signs from a Boeing 757, flying from Chicago to Los Angeles, simultaneously to: The Saddle Back Memorial, in Laguna Hills, CA; Hospital Santojanni in Buenos Aires, Argentina; and the Medical Department of American Airlines in Dallas/Fort Worth, TX. Three lead EKG, heart rate, BP, arterial oxygen saturation, end tidal CO2, respiratory rate body temperature and real time video images were collected from a passenger and transmitted to each facility from the aircraft via the Internet. Access to the Internet was gained via the cellular phone aboard the aircraft. RESULTS: A total of 20 different simulated scenarios of an medical emergency condition were successfully transmitted, simultaneously, to all health care facilities. All data was received without any corruption with an average delay time of 1 s. CONCLUSIONS: Close monitoring of the patient can lead to a better understanding and assessment of a medical condition, improve in-flight patient care, accelerate the decision making process by making an early diagnosis, and correct a life-threatening condition before the patient arrives at the destination.

Aerospace Medicine↗
PubMed1998

Live interactive broadcast of laparoscopic surgery via the Internet.

BACKGROUND: For the first time in the history of communications, we conducted live interactive broadcasts through the Internet (on August 29, and September 3, 1996). METHODS: Successful transmissions were performed from Pontiac, Michigan, to Laguna Hills, California, and Buenos Aires, Argentina, and participants actively interacted in audio and video formats in real time. RESULTS: Video images were transmitted at a rate of 1-2 frame/s and displayed in a 320 x 240 window at the remote sites. The loss of audio packets averaged 17% with a delay of 0.5-2 s. The broadcasting computer station was also able to receive real-time video and sound from the distant computers, allowing complete interaction between both parties over the duration of each transmission session. Average broadcast time was 1. 5 h +/- 30 min, and the cost of each transmission was equal to that of a regular local phone call. CONCLUSIONS: Videoconferencing via the Internet is a viable method for transmitting information in real time allowing surgeons worldwide to work together during surgical procedures.

Computer Communication Networks↗
PubMed1998

Videoconferencing as a medical educational tool: first experience in Argentinean public hospital.

Authors present their experience with first medical videoconferencing program developed in a public Argentinean hospital. Both modalities--room and desktop videoconferencing--were used. The program was exclusively used for educational purposes. A total of twelfth videoconferencing were successfully made using all resources. They included surgical procedures, magisterial lessons, grand rounds, etc. The project proved that videoconferencing is a cost-effective medical education tool, even in developing countries.

Argentina↗
PubMed1997

Laparoscopic appendectomy: a viable alternative approach.

Laparoscopic appendectomy (LA) is relatively a new technique and requires comparison to open appendectomy (OA) to determine the more favorable approach in the surgical management of acute appendicitis. We designed this study to compare the course and postoperative complications between LA and OA. We reviewed the charts of both groups of patients and followed their course in the hospital. Seventy-seven patients who underwent LA with one conversion to the open technique (1.3%) were compared to 84 patients who underwent OA. There was no difference in age and sex distribution. The mean hospital stay was shorter in the LA (32.5+/-10 vs 74.2+/-24 h, p < 0.0001). Parenteral analgesia requirement was higher in the OA group (4.7+/-1.4 vs 2.6+/-2, p < 0.0001). The total cost was higher in the OA group ($11,260+/-4000 vs 7,090+/-3500, p < 0.05). There was no significant difference in the OR time, duration of the procedure, and surgery costs between both groups. Normal appendices removed were similar in both OA and LA groups (23.8 vs 28.9%). There was no difference in the rates of postoperative complications between both groups. We conclude that LA is a viable alternative to OA. It is safe, cost effective, and less invasive than the OA with less pain and shorter hospital stay.

Acute Disease↗
PubMed1997

Arteriovenous fistula combined with basal external penile compression: a new cure for male impotence.

We describe here a new procedure designed to enable reproducible sustained erection in a canine model. In 10 dogs, an end-to-side arteriovenous fistula was created between the inferior epigastric artery and deep dorsal vein. A chronic skin tunnel was created at the penile base. Blood flow, intracavernosal pressure and intraspongiosal pressure and blood gases were measured initially and 3 months later. Cuff application for 30 minutes was used daily. At 3 months, animals were sacrificed and biopsies obtained. Physiologic and histological parameters of erectile structures remained unchanged. Intracavernosal and intraspongiosal pressures increased to 33.7 +/- 6.7 mm Hg and 25.3 +/- 12.2 mm Hg (from 8.0 +/- 2.9 and 6.0 +/- 3.6 mm Hg) after cuff application. We conclude that sustained erections are feasible. This procedure appears safe for human trials.

Anastomosis, Surgical↗
PubMed1996

Evaluation of SPf66 malaria vaccine during a 22-month follow-up field trial in the Pacific coast of Colombia.

A double-blind randomized placebo-controlled field trial with the SPf66 malaria vaccine was carried out in an endemic area consisting of 14 small villages with exclusive fluvial access, in a rain forest area along the Rosario River, Colombia. A total of 1257 subjects completed the full three dose vaccination schedule on days 0, 30 and 180 (643 vaccinated group/623 placebo group) and were followed-up by passive and active surveillance over a period of 22 months. One hundred and thirty-four Plasmodium falciparum malaria episodes were detected (53 in vaccinated group/81 in placebo group), yielding an attack rate of 5.47 cases/100 person years of follow-up (pyears) in the vaccine group and 8.44/100 pyears in the placebo group. The estimated vaccine protective efficacy was 35.2% (95% CI 8.4-54.2%, P = 0.01). This result supports earlier findings that the SPf66 malaria vaccine diminishes the risk of infection by P. falciparum in endemic areas of South America.

Adolescent↗
PubMed1995

Tumor necrosis factor-alpha: a marker for peritoneal adhesion formation.

This study investigates the possible correlation between higher levels of tumor necrosis factor-alpha (TNF-alpha) and higher rates of adhesion formation following standard bowel injury. Forty-five Sprague-Dawley rats were divided into three equal groups. Blood was obtained from all rats preoperatively. All rats were subjected to a laparotomy. In group 1 the peritoneal cavity was irrigated with normal saline. In group 2 the cecal serosa was abraded, while rats in group 3 had 2 cm of their small bowel resected. A peritoneal catheter was placed in all rats prior to closure. Blood samples were obtained at 30, 90, and 180 min following injury. Peritoneal exudate (PE) was collected and the catheter removed in 3 hr. Blood samples and peritoneal exudate were processed and levels of TNF-alpha were determined. The severity of adhesions was graded 3 weeks postoperatively using a score of 0 (absent) to III (extensive, dense). Histological evaluation for collagen deposition and fibroblasts was carried out. Rats in group 1 had significantly lower adhesion grades when compared to groups 2 and 3 (grade 0; P < 0.0001). Postoperatively, groups 2 and 3 had higher serum and PE TNF-alpha levels when compared with group 1 (P < 0.01). There was a significant correlation between higher grades of adhesions and higher levels of serum and PE at 30, 90, and 180 min following operation (P < 0.01 and < 0.05, respectively). TNF-alpha, a proinflammatory cytokine, appears to be a good biological marker for postoperative intraabdominal adhesion formation.

Animals↗
PubMed1994

SPf66, a chemically synthesized subunit malaria vaccine, is safe and immunogenic in Tanzanians exposed to intense malaria transmission.

As part of the first trial of the SPf66 malaria vaccine in Africa, three randomized double-blind placebo-controlled studies of SPf66 have been conducted in a highly endemic area of Tanzania. The objectives were to confirm that the product is immunogenic and safe in highly exposed individuals. Results from ten male adult expatriates indicated that the product used in Tanzania is at least as immunogenic as that used in Colombia. No major side-effects were observed in indigenous SPf66 recipients (18 adults, and 25 children aged 1-4 years). Anti-SPf66 antibody titres in all groups showed clear responses to three doses of the vaccine.

Adolescent↗
PubMed1994

Characterization of SPf(66)n: a chimeric molecule used as a malaria vaccine.

SPf66 is a chemically synthesized 45 amino acid peptide derived from fractions of four different proteins of Plasmodium falciparum (83, 55 and 35 kDa and CS, the circumsporozoite protein) that elicits a protective immune response against malaria. In this paper we show the characterization of the SPf(66)n in batch 9 to be used in a field trial in young children at Ifakara in Tanzania. The analysis of SPf(66)n indicates that it is highly soluble in water and that the amino acid composition and sequence corresponds to that designed for the synthesis of the polypeptide. The packed product has a molecular weight ranging from 10 to 25 kDa. It is pure, free of metallic contaminants, atoxic and stable at 4 degrees C. The antibodies raised against this product in rabbits recognize the individual antigenic determinants of the molecule and the native epitopes of merozoites.

Amino Acid Sequence↗
PubMed1991

Genetic control of the immune response to a synthetic vaccine against Plasmodium falciparum.

Two independent vaccination trials using a hybrid synthetic polypeptide containing epitopes from four proteins of Plasmodium falciparum were performed. In the first trial 63 and in the second 122 volunteers were vaccinated, using different immunization schedules. The analysis of the humoral response to the vaccine, measured by IgG antibody titres to the polypeptide showed a bimodal distribution in both cases suggesting genetic control of the immune response to this protein. There was a small group of low or non-responders and a large group of good responders. HLA phenotyping of the two groups disclosed an association of the low responders to HLA-DR4 antigens with chi-square P value of 0.00039 when compared with the good responders group. These findings provide evidence for the genetic control of the immune response to the synthetic vaccine by the association of this response with particular alleles of the HLA class II antigens; such findings may lead to an explanation of the mechanism involved in disease susceptibility and need to be used in the design of a totally effective vaccine.

Adolescent↗