Search PubMed⌕ Search

Biomedical subjects

E Rivera

Publications and source records attributed to E Rivera.

At least 37 records · Page 2Linked to original sources
PubMed2001

A diagnostic and therapeutic approach to paragangliomas of the larynx.

BACKGROUND: Differentiating paragangliomas from moderately differentiated neuroendocrine carcinoma in the larynx is a difficult management problem. As the biological behavior of these 2 entities is different, we developed an algorithm for the preoperative diagnosis and treatment of this disease. DESIGN: The sample case from which the algorithm was developed consisted of a 69-year-old man who was transferred to us after tracheostomy and an attempt at biopsy for airway obstruction secondary to a vascular mass. Biopsy resulted in substantial bleeding. Flexible laryngoscopy showed a vascular mass of the supraglottis. A computed tomographic scan showed 2 vascular masses at the carotid bifurcation and in the larynx. An arteriogram confirmed synchronous vascular tumors. RESULTS: The arteriogram showed the superior thyroid artery to be the major feeder vessel to this mass, a situation commonly seen in paragangliomas but not other neuroendocrine tumors. The presence of synchronous lesions and a vascular mass based on the superior thyroid artery helped differentiate paraganglioma from the other neuroendocrine tumors. As the biological behavior of paragangliomas is relatively benign, we performed a conservative supraglottic laryngectomy and excision of the carotid body tumor. Histologic diagnosis and immunohistochemical analysis confirmed the diagnosis of paraganglioma. CONCLUSIONS: The vascular nature of neuroendocrine tumors prevents preoperative pathological diagnosis. Radiologic features demonstrating a vascular mass with a dominant feeder vessel by the superior or inferior thyroid artery may help in the clinical diagnosis of paragangliomas of the larynx. Since paragangliomas are rarely malignant, a conservative surgical procedure should suffice.

Aged↗
PubMed2001

Persistent primitive trigeminal artery associated with posterior communicating artery aneurysm and hypoplastic vertebral artery.

We report a patient who presented with headache due to diffuse subarachnoid hemorrhage. A four-vessel angiogram revealed a left posterior communicating artery aneurysm with fetal origin, persistent primitive trigeminal artery and hypoplastic vertebral artery on the same side. This association was considered coincidental and co-existence of a saccular aneurysm with an anatomical variation of intracranial vasculature is briefly discussed.

Female↗
PubMed2001

Paradoxical effect of aspirin on the growth of C6 rat glioma and on time of development of ENU-induced tumors of the nervous system.

PURPOSE: Administration of acetylsalicylic acid (ASA), an inhibitor of the synthesis of prostaglandins and thrombzoxanes, decreases the incidence of colorectal cancer and other neoplasms and inhibits in vitro some tumor growth. We studied the effect of various doses of ASA on the growth of C6 glioma implanted in rats as well as the effect of chronic administration of ASA on time of development and incidence of tumors of the central nervous system (CNS) induced by prenatal exposure to ethylnitrosourea (ENU). METHODS: In a controlled study, various doses of ASA, 12.5, 25, 50, 100, 200, 300, and 400 mg/kg per day, were administered to Wistar rats in whom a subcutaneous C6 glioma had been transplanted. Changes in tumor size, histologic characteristics, mitotic index, cell proliferation, and vascular density were studied. In a parallel experiment, we administered ASA (70 mg/kg per day) to rats who were prenatally exposed to ENU; treatment started on day 50 of age, and continued until the end of the experiment at day 400. The time of tumor development as well as incidence, localization, and histological diagnosis were compared with matched controls. RESULTS: A paradoxical effect of ASA administration was observed on the dynamics of cell proliferation of C6 glioma. When high ASA doses were administered (200 or 400 mg/kg per day), tumor volume, cell proliferation, vascular density, and mitotic index increased. In contrast, when low doses were administered (12.5 or 25 mg/kg per day) the tumor size diminished. In the second experiment, localization and incidence of CNS tumors induced by ENU were similar in animals treated with ASA and in controls; however, in rats treated with ASA the time of tumor development was shortened. CONCLUSIONS: The growth-promoting effects of high doses of ASA found in the present study in both transplanted and chemically-induced brain tumors, might be due to the blockage of autocrine inhibitory factors dependent on the cyclooxygenase pathway or by increased vascular permeability and blood supply to the tumor due to inhibition of platelet aggregation. In contrast, the inhibition of tumor growth obtained with low ASA doses in transplanted glioma might be due to different mechanisms such as the induction of apoptosis.

Alkylating Agents↗
PubMed2001

Suppression of melanoma cell proliferation by histidine decarboxylase specific antisense oligonucleotides.

Histidine decarboxylase (HDC) is expressed by the cells of melanoma, in which the histamine content tends to be relatively high. This study shows that elevated expression of HDC was found by western blot analysis of primary and metastatic melanoma tissue using a polyclonal HDC specific antibody. The specificity of anti-HDC antibody was confirmed by inhibition of HDC translation (i.e., immunopositivity) in melanoma cells by HDC-specific antisense oligonucleotide. Moreover, the decrease in proliferation caused by HDC antisense oligonucleotides indicates considerable functional relevance of histamine synthesis in melanoma growth and suggests a possible in situ application of specific antisense oligonucleotides for HDC in melanoma therapy.

Adult↗
PubMed2001

Retaining hard-to-reach women in HIV prevention and vaccine trials: Project ACHIEVE.

Project ACHIEVE, which conducts HIV prevention research studies, maintains a women's site in the South Bronx in NewYork City. Owing to a focused retention effort at the South Bronx site, high retention rates were achieved in a vaccine preparedness study for women at high risk of HIV infection. Comparable retention rates have been achieved in HIV vaccine trials with similar cohorts of women at this site. These results suggest that concerns about retaining hard-to-reach populations should not cause these populations to be excluded from HIV vaccine and prevention trials.

AIDS Serodiagnosis↗
PubMed2000

Phase II study of paclitaxel in patients with metastatic breast carcinoma refractory to standard chemotherapy.

BACKGROUND: The authors conducted a single institution Phase II clinical trial to determine whether paclitaxel had antitumor activity in patients with metastatic breast carcinoma that was refractory to standard chemotherapy. METHODS: Patients with metastatic breast carcinoma were eligible for the study if they had disease progression after at least 2 prior chemotherapy regimens. Patients who had received three prior regimens were treated in a separate cohort. All patients were required to have received doxorubicin in the past and were not eligible if they had received prior therapy with paclitaxel. The starting dose of paclitaxel for low risk patients was 175 mg/m2, administered as a 24-hour continuous infusion; the starting dose of paclitaxel was 150 mg/m2 for patients who had received > or = 3 prior regimens. Therapy was given every 3 weeks and continued for at least 2 courses unless there was evidence of rapidly progressing disease, for at least 3 courses if there was no change in disease and Grade 3 or 4 (based on National Cancer Institute toxicity criteria) toxicity was not noted, and for 6 courses beyond the maximum response in patients who demonstrated complete or partial responses and showed no evidence of disease progression. RESULTS: Sixty-eight of 69 patients entered in the study were evaluable for response: 35 patients who had received 2 prior chemotherapy regimens for Stage IV disease and 33 patients who had received > or =3 prior regimens. A partial response was observed in 7 patients who had received 2 prior regimens, for an objective response rate of 20% (95% confidence interval [95% CI], 14-26%). In the group who had received > or = 3 prior regimens, a total of 6 partial responses were observed, for an objective response rate of 18% (95% CI, 12-23%). The median response duration was 8.2 months (range, 2.7-10.1 months) for the group who had received 2 prior regimens and 5.8 months (range, 2.1-9.5 months) for patients who received > or = 3 prior regimens. Responses were noted in patients with anthracycline-resistant tumors. CONCLUSIONS: Paclitaxel was active in heavily pretreated patients with metastatic breast carcinoma, including anthracycline-resistant breast carcinoma.

Adult↗
PubMed2000

Apatite growth on calcium adsorbed surface of wet flocculated silica particles immersed in a modified simulated body fluid.

An alternative method for the calcium phosphate apatite formation onto the surface of flocculated pure silica particles is reported, in an attempt to understand the possible mechanism for the apatite formation. A stable silica sol was flocculated by adding calcium ions in aqueous solution. The wet flocks were resuspended in a basic aqueous solution containing a calcium salt, trying to allow the absorption of calcium ions onto the silica surface through a hydrogen ion exchange. The as-prepared materials were immersed in a modified simulated body fluid at different temperatures (37 and 90 degrees C) and silica concentrations. It was found that these factors have a strong influence on the apatite formation. The apatite formation was confirmed by (31)P MAS-NMR, FT-Raman, XRD, and TEM.

Adsorption↗
PubMed2000

Cardiovascular function in Omani children with sickle cell anaemia.

Systolic murmurs were detected in 22 (61%) of the 36 children with sickle cell anaemia (SCA) who completed the study. Cardiomegaly was detected in 14 (39%). Mean values of left and right ventricular dimensions were higher in SCA than in controls (p < 0.05). Left atrial chambers and aortic root dimensions followed the same pattern. The dilated cardiac chambers in SCA were not associated with any abnormality in systolic or diastolic left ventricular function nor with significant pulmonary hypertension.

Adolescent↗
PubMed2000

Using behavior modification to promote wound healing.

Successfully caring for patients with wounds under PPS demands that current practice approaches must change. Instead of focusing on dressings and techniques alone, this article describes how first addressing patients' psychological readiness for change can move them quickly to self-care and enhance wound healing, which results in cost savings and better outcomes.

Attitude to Health↗
PubMed2000

Severity of illness, outcomes, and resource use in elderly cancer patients with deep venous thrombosis.

Low-molecular-weight heparins provide new options for outpatient management of deep venous thrombosis. Because elderly patients with cancer are at increased risk of developing deep venous thrombosis, outpatient therapy for treatment of deep venous thrombosis may be important in this population. We compared the severity of illness, outcomes, and cost of deep venous thrombosis in elderly patients with cancer to those seen in younger patients with cancer. We examined all 766 episodes of deep venous thrombosis treated at the University of Texas M.D. Anderson Cancer Center between January 1, 1994 and December 31, 1996. Severity of illness level and predicted risks of mortality and readmission were obtained from a commercially available disease staging system (Inforum System). Observed outcomes and cost were based on data collected from the 766 episodes of deep venous thrombosis at our institution. One hundred nineteen (16%) episodes of deep venous thrombosis occurred in patients 70 years of age or older. The severity of illness scale (1-5, least-most severe) were identical (3.7) in the 3 groups studied (< 70 years, 70-79, years and > or = 80 years). The predicted risk of death during hospitalization (6%, 9%, 8%, respectively, by group, P = 0.12) and readmission in 30 days (5%, 4%, 3%, respectively, P = 0.04) were similar among the groups. The observed death rates during hospitalization were 5%, 6%, and 6%, respectively (P = 0.91), and the rates of hospitalization for deep venous thrombosis recurrence were 22%, 16%, and 28%, respectively (P = 0.27). The similarities in outcomes and resource use between elderly and younger patients suggest that elderly patients with cancer are not at greater risk of serious clinical outcomes or a prolonged clinical course. There is significant potential for outpatient management of these patients.

Aged↗
PubMed2000

Carotid stenting: a technology in evolution.

Interest in stenting lesions involving the carotid artery bifurcation has grown during the past 10 years. Techniques first utilized by Theron and Mathias in Europe and Roubin and colleagues in the United States have evolved to where the technique has been extensively refined and its safety and efficacy firmly established. The only prospective randomized study comparing carotid stenting with carotid endarterectomy, CAVATAS (Carotid and Vertebral Artery Transluminal Angioplasty Stenting), showed similar safety profiles and long-term results for both techniques. A large scale NIH-sponsored trial is now in progress, CREST (Carotid Revascularization Endarterectomy versus Stent Trial), but the results are 5-6 years away. In the interim, one approach toward instituting a carotid stent program is described.

Angioplasty↗
PubMed2000

Renovascular hypertension: screening and therapeutic options.

Renovascular hypertension is part of the spectrum of hypertensive disease. Although uncommon (1% to 5% of the cases) in comparison to essential hypertension, it is a potentially curable form of the disease. We review the different tools available for the evaluation and treatment of this condition.

Female↗
PubMed1999

Protective effect of pentoxifylline plus thalidomide against septic shock in mice.

Mortality caused by septic shock in experimental animals is reduced by thalidomide, an inhibitor of tumour necrosis factor alpha. Another drug that could act on the pathophysiological mechanisms of septic shock is pentoxifylline, an inhibitor of platelet aggregation that increases the flexibility of the erythrocyte membrane and has fibrinolytic activity. We studied the effect of pentoxifylline alone and combined with thalidomide in septic shock; 97 NIH mice were injected with lipopolysaccharides of Salmonella abortus equi and D galactosamine. Animals were separated in 4 groups; group A (n = 20) was used as control, group B (n = 15) received thalidomide 50 mg/kg, group C (n = 20) received pentoxifylline 40 mg/kg, and group D (n = 15) received thalidomide plus pentoxifylline. Mortality was recorded every hour. Additionally, 5 animals from each group were sacrificed 8 h after the induction of septic shock for histological analysis of heart, lung, brain, kidney, small intestine, adrenal glands and liver. Microscopic findings were rated as absent, mild, moderate and severe damage. In control animals histological analysis showed intense haemorrhage and necrosis in all organs studied. When compared with controls, treatment with pentoxifylline plus thalidomide reduced mortality (P < 0.03). The tissue damage was less severe in animals from the groups that received pentoxifylline or pentoxifylline plus thalidomide (P < 0.05). Pentoxifylline seems to potentiate the beneficial effects of thalidomide, reducing mortality and attenuating the pathological changes produced by septic shock.

Animals↗