Search PubMed⌕ Search

Biomedical subjects

E Rivera

Publications and source records attributed to E Rivera.

At least 19 recordsLinked to original sources
PubMed2002

H1 and H2 histamine receptors mediate the production of inositol phosphates but not cAMP in human breast epithelial cells.

OBJECTIVE: In the present work we studied the H1 and H2 histamine receptor expression and function in HBL-100 and MCF-10A cells, derived from non-tumorigenic human breast epithelia, and in MCF-10T, the H-ras-transfected MCF-10A counterpart. The signal transduction pathways associated with these receptors, and the expression of proto-oncogenes c-fos, c-myc and c-jun at the mRNA and protein levels, were examined. RESULTS: Saturation analysis using intact cells, showed two binding sites for [3H]tiotidine and [3H]mepyramine. Pretreatment of purified membrane with guanosine 5'-ythiotriphosphate resulted in the loss of the low affinity component for [3H]tiotidine binding, and of the high affinity component for [3H]mepyramine. In both cases, there was no modification in the total number of sites for both ligands. Neither H1 nor H2 agonists stimulated cyclic AMP production, though this pathway is functional in these cells. On the other hand, both H1 and H2 agonists enhanced phosphoinositide turnover in a dose-dependent fashion, and this induction is pertussis toxin-insensitive. H1 and H2 agonists did not influence the expression of c-myc or c-fos mRNA, nor their encoded proteins. CONCLUSIONS: These results indicate that the three cell lines examined showed functional H1 and H2 histamine receptors, which are involved in the metabolic turnover of inositol phosphates but are ineffective in the modulation of the cyclic AMP response. The fact that H2 receptors have lost their ability to stimulate cyclic AMP production would imply the loss of a regulatory mechanism of cell growth.

Breast↗
PubMed2001

AT1 receptor is present in glioma cells; its blockage reduces the growth of rat glioma.

Malignancy of neoplasms is partly dependent on angiogenesis. Angiotensin II mediates angiogenesis and transcription of growth-related factors through stimulation of the AT1 receptor (AT1R). Losartan, a drug used mostly for treatment of hypertension, binds strongly to this receptor. We found the presence of AT1 receptor on C6 glioma cells and studied the effect of Losartan on the growth and angiogenesis of C6 rat glioma; Losartan in dose of 80 mg/kg induced 79% reduction of tumoural volume with a significant decrease of vascular density, mitotic index and cell proliferation. Our results demonstrate the conspicuous presence of AT1R in malignant glial cells and a favourable therapeutic response in experimental glioma by selective blockage of the AT1 receptor.

Angiotensin II↗
PubMed2001

Paclitaxel in the multimodality treatment for inflammatory breast carcinoma.

BACKGROUND: Inflammatory breast carcinoma (IBC) is a rare but aggressive form of breast carcinoma. Anthracycline-based regimens represent the standard of treatment for IBC. Reports of significant clinical activity of paclitaxel in metastatic breast carcinoma led the authors to investigate the role of this drug in the management of IBC. METHODS: Forty-four patients with IBC were enrolled between February 1994 and January 1998. The treatment plan consisted of induction chemotherapy (IC), mastectomy, adjuvant chemotherapy, and radiotherapy. Forty-two patients received IC with four cycles of fluorouracil, doxorubicin, and cyclophosphamide. If the clinical response was less than partial, patients were "crossed over" to paclitaxel before mastectomy. All patients received adjuvant paclitaxel. Patients unresectable after paclitaxel were offered high-dose chemotherapy with autologous peripheral blood progenitor cell support. RESULTS: Thirty-four patients (81%) achieved an objective clinical remission; 3 patients (7%) achieved a clinical complete remission, 31 (74%) a partial remission. Six patients (14%) achieved pathologic complete remission. Sixteen patients were treated with paclitaxel, 7 of them (44%) were able to undergo mastectomy. Median time to progression (TTP) was 22 months. Median overall survival (OS) was 46 months. Concordance between clinical and pathologic response was documented in only 8 patients (24%). No differences in TTP and OS compared with a historical group of 178 IBC patients treated with anthracycline-based regimens. CONCLUSIONS: Paclitaxel improves tumor resectability in anthracycline-refractory IBC. The impact of paclitaxel on the prognosis of IBC needs to be better evaluated in future trials using more dose-intensive schedules of administration. New imaging modalities may contribute to improve assessment of response to IC.

Adenocarcinoma↗
PubMed2001

A fatigue clinic in a comprehensive cancer center: design and experiences.

Cancer-related fatigue is now the most prevalent symptom of cancer, occurring in 60-90% of patients. Fatigue has been identified by cancer patients as a factor influencing functionality and quality of life. Our objectives in developing a fatigue specialty clinic at The University of Texas M. D. Anderson Cancer Center were to improve our patients' quality of life by decreasing fatigue; educate health care providers, patients, and patients' families about cancer-related fatigue; develop an appropriate clinical and diagnostic evaluation for this symptom; correlate objective measures of fatigue with its clinical evaluation; and develop innovative treatment plans for cancer-related fatigue. This article describes the general clinic design and operations and the preliminary analysis of the first 40 patients evaluated in the fatigue clinic.

Adult↗
PubMed2001

Biosynthesis of D-alanyl-lipoteichoic acid: the tertiary structure of apo-D-alanyl carrier protein.

The D-alanylation of lipoteichoic acid (LTA) allows the Gram-positive organism to modulate its surface charge, regulate ligand binding, and control the electromechanical properties of the cell wall. The incorporation of D-alanine into LTA requires the D-alanine:D-alanyl carrier protein ligase (AMP-forming) (Dcl) and the carrier protein (Dcp). The high-resolution solution structure of the 81-residue (8.9 kDa) Dcp has been determined by multidimensional heteronuclear NMR. An ensemble of 30 structures was calculated using the torsion angle dynamics approach of DYANA. These calculations utilized 3288 NOEs containing 1582 unique nontrivial NOE distance constraints. Superposition of residues 4-81 on the mean structure yields average atomic rmsd values of 0.43 +/- 0.08 and 0.86 +/- 0.09 A for backbone and non-hydrogen atoms, respectively. The solution structure is composed of three alpha-helices in a bundle with additional short 3(10)- and alpha-helices in intervening loops. Comparisons of the three-dimensional structure with the acyl carrier proteins involved in fatty acid, polyketide, and nonribosomal peptide syntheses support the conclusion that Dcp is a homologue in this family. While there is conservation of the three-helix bundle fold, Dcp has a higher enthalpy of unfolding and no apparent divalent metal binding site(s), features that distinguish it from the fatty acid synthase acyl carrier protein of Escherichia coli. This three-dimensional structure also provides insights into the D-alanine ligation site recognized by Dcl, as well as the site which may bind the poly(glycerophosphate) acceptor moiety of membrane-associated LTA.

Acyl Carrier Protein↗
PubMed2001

Weekly trastuzumab and paclitaxel therapy for metastatic breast cancer with analysis of efficacy by HER2 immunophenotype and gene amplification.

PURPOSE: This phase II study evaluated weekly trastuzumab and paclitaxel therapy in women with HER2-normal and HER2-overexpressing metastatic breast cancer. Efficacy was correlated with immunohistochemical and fluorescent in situ hybridization (FISH) assay results. PATIENTS AND METHODS: Eligible patients had bidimensionally measurable metastatic breast cancer. Up to three prior chemotherapy regimens, including prior anthracycline and taxane therapy, were allowed. Trastuzumab 4 mg/kg and paclitaxel 90 mg/m2 were administered on week 1, with trastuzumab 2 mg/kg and paclitaxel 90 mg/m2 administered on subsequent weeks. HER2 status was evaluated using four different immunohistochemical assays and FISH. RESULTS: Patients received a median of 25 weekly infusions (range, one to 85 infusions). Median delivered paclitaxel dose-intensity was 82 mg/m2/wk (range, 52 to 90 mg/m2/wk). The intent-to-treat response rate for all 95 patients enrolled was 56.8% (95% confidence interval, 47% to 67%). A response rate of 61.4% (4.5% complete response, 56.8% partial response) was observed in 88 fully assessable patients. In patients with HER2-overexpressing tumors, overall response rates ranged from 67% to 81% compared with 41% to 46% in patients with HER2-normal expression (ranges reflect the different assay methods used to assess HER2 status). Differences in response rates between patients with HER2-overexpressing tumors and those with normal HER2 expression were statistically significant for all assay methods, with CB11 and TAB250 antibodies and FISH having the strongest significance. Therapy was generally well tolerated, although three patients had serious cardiac complications. CONCLUSION: Weekly trastuzumab and paclitaxel therapy is active in women with metastatic breast cancer. Therapy was relatively well tolerated; however, attention to cardiac function is necessary.

Adult↗
PubMed2001

Spectrometric evidence for the flavin-1-phenylcyclopropylamine inactivator adduct with monoamine oxidase N.

1-Phenylcyclopropylamine (1-PCPA) is shown to be an inactivator of the fungal flavoenzyme monoamine oxidase (MAO) N. Inactivation results in an increase in absorbance at 410 nm and is accompanied by the concomitant loss of the flavin absorption band at 458 nm. The spectral properties of the covalent adduct formed between the flavin cofactor of MAO N and 1-PCPA are similar to those reported for the irreversible inactivation product formed with 1-PCPA and mammalian mitochondrial monoamine oxidase B [Silverman, R. B., and Zieske, P. A. (1985) Biochemistry 24, 2128-2138]. There is a hypsochromic shift of the 410 nm band upon lowering the pH to 2, indicating that an N(5)-flavin adduct formed upon inactivation. Use of the fungal enzyme, MAO N, which lacks the covalent attachment to the flavin adenine dinucleotide (FAD) cofactor present in the mammalian forms MAO A and MAO B, has allowed for the isolation and further structural identification of the flavin-inactivator adduct. The incorporation of two (13)C labels into the inactivator, [2,3-(13)C(2)]-1-PCPA, followed by analysis using on-line liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy, provided a means to explore the structure of the flavin-inactivator adduct of MAO N. The spectral evidence supports covalent attachment of the 1-PCPA inactivator to the cofactor as N(5)-3-oxo-3-phenylpropyl-FAD.

Aspergillus niger↗
PubMed2001

Phase I study of stealth liposomal doxorubicin in combination with gemcitabine in the treatment of patients with metastatic breast cancer.

PURPOSE: We conducted a single-institution phase I clinical trial to determine the maximum-tolerated dose (MTD) and define the toxic effects of stealth liposomal doxorubicin in combination with gemcitabine in patients with metastatic breast cancer. PATIENTS AND METHODS: Patients were eligible if they had disease progression with no limit on prior number of chemotherapy regimens. Prior treatment with liposomal doxorubicin and/or gemcitabine was not allowed. The starting dose of liposomal doxorubicin was 20 mg/m(2) on day 1 only with a 20% dose escalation of the previous mg/m(2) dose until MTD was reached. Gemcitabine was given as a fixed dose of 800 mg/m(2) on days 1 and 8 every 3 weeks. RESULTS: We treated 27 patients of whom six had never received chemotherapy for their disease. Most had had visceral involvement as their dominant site of disease. The dose-limiting toxicity was myelosuppression, which included neutropenia and thrombocytopenia. However, neither neutropenic fever nor episodes of bleeding were major occurrences. Significant antitumor activity was also observed with a total of two complete and seven partial responses. The recommended phase II dose is liposomal doxorubicin 24 mg/m(2) on day 1 and gemcitabine 800 mg/m(2) on days 1 and 8 every 21 days. CONCLUSION: The combination of liposomal doxorubicin and gemcitabine is an active and well tolerated regimen when administered on a 21-day schedule. Myelosuppression limited further dose escalation, however, it did not increase the incidence of neutropenic fever. Significant antitumor activity seen in heavily and minimally pretreated patients warrants further evaluation of this combination.

Adult↗
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↗