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Biomedical subjects

H Gómez

Publications and source records attributed to H Gómez.

At least 19 recordsLinked to original sources
PubMed2001

Transition state spectroscopy of the I + HI reaction in clusters: photoelectron spectroscopy of IHI-.Arn (n = 1-15).

We have investigated effects of solvation on the transition state spectroscopy and dynamics of the I + HI reaction by measuring the anion photoelectron (PE) spectra of the clusters IHI-.Arn (n = 1-5). Argon clustering results in a successive shift of the PE spectra to lower electron kinetic energies with increasing cluster size. It also leads to significant vibrational cooling in the PE spectra and facilitates the observation of features associated with symmetric stretch vibrations and hindered rotational motions of the transition state complex IHI. The shifts in electron binding energy suggest that the first six argon atoms form a ring around the waist of the IHI- anion, just as in I2-.Arn. The spacing of the antisymmetric stretch features evolves with cluster size and is attributed at least in part to perturbation of the IHI- geometry in larger argon clusters. Intensities of features due to hindered rotation are enhanced for larger clusters, possibly due to solvent perturbation of the neutral transition state region.

Journal Article↗
PubMed2000

Increased cytogenetic damage in outdoor painters.

Painters are exposed to an extensive variety of hazardous substances such as organic solvents, lead-containing pigments and residual plastic monomers. In this particular case, workers used commercially available exterior paints and occasionally gasoline or thinner as solvents. The application or removal of paints was performed without protection (masks or gloves). To determine occupational exposure risk, a monitoring study was designed. Group selection was made after a questionnaire administration, which included questions about lifestyle and medical history to exclude exposure to other potential sources of genotoxics. Smoking and drinking habits were also considered. Blood and buccal cell samples were obtained from 25 public building male painters and from a similar number of age- and gender-matched controls. Lead levels were measured in paint samples and in individuals' blood. Organic solvents and/or its metabolites were also determined in blood. Chromosomal aberrations (CA) and sister chromatid exchanges (SCE) were determined in peripheral blood lymphocyte cultures. Also, the frequency of micronuclei (MN) in buccal cells was investigated. Painters had higher lead levels in blood (p<0.05); CA and SCE in lymphocytes and MN in epithelial cells were also elevated (p<0.05). Cytogenetic damage was significantly associated with occupational exposure time but not with the levels of lead found in blood.

Adolescent↗
PubMed1998

A phase II study of a novel gemcitabine plus cisplatin regimen administered every three weeks for advanced non-small-cell lung cancer.

BACKGROUND: The aim of this study was to determine the clinical activity and toxicity of a novel chemotherapy combination regimen of gemcitabine plus cisplatin, administered every three weeks, in patients with advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Twenty-six previously untreated stages III (14) and IV (12) patients were included. Gemcitabine was administered on days 1 and 8 at a dose of 1250 mg/m2 and cisplatin was administered at a dose of 100 mg/m2 on day 1, every 21 days. RESULTS: Twenty-five patients were evaluable for response. One patient achieved a complete response, and 16 patients partial responses. The overall response rate was 65.3% (95% CI: 45%-82%). The main toxicity was hematological: neutropenia NCIC-CTC grade 3-4 in 54% of the patients, and thrombocytopenia grade 3-4 in 23%. The non-hematological toxicity was mild and tolerable. Only 13% of gemcitabine injections were dose-reduced or omitted due to toxicity. The actual dose-intensity of gemcitabine was 715 mg/m2/week, and 31 mg/m2/week for cisplatin. These figures represent the 86% and 93% of the theoretical dose intensity of both drugs, respectively. With a median follow-up of 10 months (range 7-13), 17 patients are still alive and nine have died. The median overall survival is 12 months. CONCLUSION: This novel combination of gemcitabine and cisplatin administered every three weeks is well tolerated and induces a remarkably high response rate. The regimen proves more interesting than the four-week schedules, particularly regarding patients who are candidates for local therapy.

Adult↗
PubMed1998

Risk factors for treatment-related death in elderly patients with aggressive non-Hodgkin's lymphoma: results of a multivariate analysis.

PURPOSE: It has been suggested that age is associated with chemotherapy-related death in patients with non-Hodgkin's lymphoma (NHL) treated with doxorubicin-containing chemotherapy. The purpose of this study was to evaluate the relative influence of increasing age and other clinical parameters on the occurrence of treatment-related death in elderly patients with intermediate- or high-grade NHL treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy. METHODS: A retrospective study of patients 60 years of age or older with intermediate- or high-grade NHL treated with CHOP chemotherapy in a single cancer center. The following variables were recorded: age (60 to 69, 70 to 79, and 80 to 94 years), histology (Working Formulation [WF] D, E, F, G, and H), Ann Arbor stage, B symptoms, extranodal involvement, bulky disease (> 7 cm), performance status (Eastern Cooperative Oncology Group [ECOG] scale), International Prognostic Index (IPI score), serum lactate dehydrogenase (LDH) level and doxorubicin relative dose-intensity (RDI). The relationship between these features and treatment-related death was assessed in univariate and multivariate logistic regression analysis. RESULTS: From 1982 to 1991, 267 consecutive patients were treated. Median age was 70 years (range, 60 to 94 years). There were 35 toxic deaths. Sixty-three percent of the deaths occurred after the first cycle. Infection accounted for 82% of the toxic deaths. In the univariate analysis, the features associated with an increased risk of toxic death were ECOG performance status 2 to 4 (relative risk [RR], 7.82), B symptoms (RR, 3.38), diffuse large-cell histology (RR, 3.06), bulky disease (RR, 2.58), serum levels of LDH (RR, 2.53), and IPI score (RR, 2.46). The age groups did not show significance. In the regression model, performance status 2 to 4 was the only independent predictor of treatment-related death (RR, 3.52; 95% confidence interval [CI], 2.98 to 4.06). CONCLUSION: Our results show that in elderly patients with NHL treated with doxorubicin-based chemotherapy the risk for treatment-related death is associated with poor performance status rather than with increasing chronologic age.

Age Factors↗
PubMed1998

Elderly patients with aggressive non-Hodgkin's lymphoma treated with CHOP chemotherapy plus granulocyte-macrophage colony-stimulating factor: identification of two age subgroups with differing hematologic toxicity.

PURPOSE: Standard cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy repeated at 3-week intervals is difficult to deliver in elderly patients with non-Hodgkin's lymphoma (NHL). The use of hemopoietic growth factors may decrease the hematologic toxicity of chemotherapy and allow the delivery of full-dose CHOP. PATIENTS AND METHODS: We conducted a phase II trial with the addition of granulocyte-macrophage colony-stimulating factor (GM-CSF) to CHOP chemotherapy in NHL patients older than 60 years of age. Twenty-six previously untreated patients were assessable; median age was 67 years (range, 61 to 84 years). CHOP included cyclophosphamide 750 mg/m2 intravenously day 1; doxorubicin 50 mg/m2 intravenously day 1; vincristine 1.4 mg/m2 (2 mg total dose) intravenously day 1; and prednisone 100 mg orally days 1 through 5. GM-CSF 5 microg/kg was administered subcutaneously on days 4 through 13. Cycles were repeated every 21 days for six cycles. Results were analyzed for the total group and for two age subgroups: 61 to 69 years (n = 15) and 70 years or older (n = 11). RESULTS: Sixteen patients (62%) achieved a complete response (CR), four patients (15%) achieved a partial response (PR), and six patients (23%) did not respond to therapy. After a median follow-up of 41 months, the median progression-free and overall survival were 19 and 30 months, respectively. Twenty patients completed six cycles. One hundred thirty-eight of the 156 planned cycles were delivered (88%). The relative dose-intensity was 95%. The chemotherapy-induced toxicity was important. Absolute neutrophil count was less than 500/mL in 43% of the cycles, platelet nadir was less than 20,000/mL in 19%, and febrile neutropenia occurred in 21%. There were no grades 3 to 4 mucositis. Treatment-related death occurred in two patients, and was associated with neutropenic septic shock. The toxicity related to GM-CSF was mild hypotension after the cytokine was administered in 7% of cycles. When the results of the study were analyzed by age subgroups, we observed that whereas response and median survival were similar in patients aged 61 to 69 years or 70 years or older, there were significant differences in dose delivery and toxicity. Chemotherapy was delivered in 86 of 90 planned cycles in patients aged 61 to 69 years, but in only 52 of 72 planned cycles in patients aged 70 to 84 years (P = .00008). Absolute neutrophil count was less than 500/mL in 24% of cycles in patients aged 61 to 69 years and 73% of cycles in patients aged 70 years or older (P = .00001). The platelet nadir of less than 20,000/mL occurred in 5% of patients aged 61 to 69 years and in 42% of patients aged 70 years or older (P < .0001). Fever and neutropenia occurred in 8% of patients aged 61 to 69 years and in 42% of patients aged 70 years or older (P < .0001). Mucositis (grades 1 to 2) occurred in 21% of patients aged 61 to 69 years and in 42% of patients aged 70 years or older (P = .006). CONCLUSION: CHOP chemotherapy plus GM-CSF is an active regimen in elderly patients with NHL. Despite cytokine support, the toxicity of the regimen is elevated. We have identified two age subgroups (61 to 69 and > or = 70 years) that do not differ in treatment efficacy but show large differences in treatment-related toxicity.

Age Factors↗
PubMed1997

Ifosfamide plus cisplatin as primary chemotherapy of advanced ovarian cancer.

We have performed a phase II study to evaluate the activity and toxicity of ifosfamide and cisplatin as first-line treatment for advanced ovarian cancer. Patients were treated with cisplatin 100 mg/m2 on day 1 and ifosfamide 5 g/m2 in 18-hr continuous infusion on day 1 or 1.5 g/m2 bolus on days 1-5. Between August 1988 and March 1990, 30 women were entered in the trial, 26 of them with measurable disease. The overall clinical response rate was 69% (95% CI: 48-85%), including 34.6% complete responses (95% CI:17-55%). Reassessment laparotomy was performed in 12 cases, and 4 (33%) exhibited a pathologic complete response. For all patients, the median duration of progression-free survival was 14 months, and the median overall survival was 25 months. There were no major differences in the response rate or survival between the two ifosfamide administration modalities. Relevant toxicities were grade IV hematologic toxicity in 11/30 patients and grade IV renal toxicity in 2/30 patients. A patient with grade IV encephalopathy developed a trauma-related cerebral hemorrhage and died 2 months later. The combination of ifosfamide and cisplatin is active in first-line therapy in advanced ovarian cancer, although it does not seem to improve the efficacy or toxicity profile of conventional combinations.

Adult↗
PubMed1997

Patient selection in high-dose chemotherapy trials: relevance in high-risk breast cancer.

PURPOSE: To evaluate the impact of the selection criteria that are used in current high-dose consolidation chemotherapy (HDCT) trials on the outcome of high-risk breast cancer patients treated with conventional adjuvant chemotherapy. PATIENTS AND METHODS: From 1975 to 1995, 265 breast cancer patients at our institution showed involvement of ten or more positive axillary lymph nodes. Of these, 171 received standard adjuvant combination chemotherapy, but not HDCT consolidation, and were the subjects of our study. One hundred twenty-eight patients met the standard selection criteria for HDCT with hematological support (< 60 years, no significant concomitant disease, and no progression during adjuvant treatment), whereas 43 did not. Clinical outcome was analyzed by using disease-free survival (DFS) and overall survival (OS) as endpoints. To provide an assessment of the short-term efficacy of HDCT, we also evaluated the outcome in a cohort of 39 patients from the last 4 years who met the criteria for, and were actually treated with, HDCT after adjuvant chemotherapy. RESULTS: With a median follow-up of 4.4 years (range, 0.7 to 17.2 years), 112 of the 171 patients have had a relapse, and 87 have died. The estimated 5-year DFS was 32.3%, and OS was 49.4%. DFS was significantly higher for patients who met the HDCT criteria (36.6% at 5 years) than for those who did not (15.8% at 5 years; P < .05). OS was also significantly more favorable in patients meeting HDCT criteria (55.4% at 5 years) than in patients not meeting HDCT criteria (22.7% at 5 years; P < .01). We performed a multivariate analysis to adjust for other potential prognostic factors and found that meeting the HDCT criteria and having undergone locoregional radiotherapy were the only significant independent predictors for DFS and OS. Finally, we compared the outcome of the 128 patients who met the HDCT criteria and were treated with conventional adjuvant chemotherapy only with that of the 39 patients who met the criteria and who actually underwent HDCT, and we did not observe significant differences in the DFS or OS between these groups. CONCLUSIONS: Meeting HDCT inclusion criteria is an independent indicator of favorable prognosis in high-risk breast cancer patients. The selection of patients by these criteria may explain, at least in part, the promising short-term results of nonrandomized adjuvant HDCT trials in high-risk breast cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Acute toxicological effects in rats treated with a mixture of commercially formulated products containing methyl parathion and permethrin.

The study examined the interactions between a commercial formulation of methyl parathion (CF-MP) and a commercially formulated product of permethrin (CF-PMT) in male rats. The acute toxicity (LD50 values) and brain cholinesterase activity were investigated as toxicological endpoints. Results indicated that CF-MP modified the acute toxicity of CF-PMT. When animals were treated with a mixture, the addition of 380 mg/kg of CF-MP reduced the LD50 of CF-PMT by only 9.0%; however, when rats received CF-MP at 464 mg/kg, the LD50 of CF-PMT was reduced by 37% (P < 0.001). Also, CF-PMT decreased the CF-MP-induced inhibition of cholinesterase activity by 50% (P < 0.05). It was interesting to observe that xylene, which is the most abundant component in the vehicle of both formulations, had no effect on the CF-MP-induced inhibition of the cholinesterase activity. There was no relation between lethality and the inhibition of the brain cholinesterase activity in rats treated with mixtures containing CF-MP+CF-PMT or with either commercially formulated product alone. Considering the increased toxicity observed in rats treated with CF-PMT+CF-MP, it would be advisable to investigate further the interactions between both pesticides.

Animals↗
PubMed1995

Genotoxic monitoring of workers at a hazardous waste disposal site in Mexico.

Chromosomal aberration and sister chromatid exchange (SCE) frequencies were determined in lymphocytes cultured from 12 high-risk individuals working at a landfill for hazardous waste disposal. Cell proliferation kinetics (CPK) was also determined. Compared with 7 control individuals, no effects were observed with respect to SCE nor on CPK. However, the workers exhibited significantly higher frequencies of chromatid and chromosomal deletions, the magnitude of which was related with exposure time. This study suggests that when high-risk exposure is suspected, determining biomarkers of genotoxic damage (e.g., chromosomal aberrations), is useful for risk assessments.

Cell Division↗
PubMed1992

Ceftibuten and trimethoprim-sulfamethoxazole for treatment of Shigella and enteroinvasive Escherichia coli disease.

In a prospective randomized study at two clinical sites, ceftibuten was compared with trimethoprim-sulfamethoxazole (TMP-SMX), both given orally for a period of 5 days, for the treatment of dysentery. Twenty-two children were found to have bacillary dysentery caused by Shigella and/or enteroinvasive Escherichia coli. All organisms isolated were susceptible to ceftibuten; 6 of 20 Shigella strains and 4 of 5 enteroinvasive E. coli were resistant to TMP-SMX. The diarrhea persisted for a mean (+/- SD) period of 2.4 +/- 1.4 days in the ceftibuten-treated patients vs. 3.4 +/- 1.7 days in the TMP-SMX-treated patients. The duration of fever was similar for both treatment groups. Patients treated with ceftibuten or TMP-SMX had equivalent clinical responses unless the pathogen was found to be TMP-SMX-resistant. Those who were randomized to receive TMP-SMX but who were eventually found to have TMP-SMX-resistant organisms had significantly more stools at days 3, 4 and 5 (P less than 0.02 to less than 0.00006) with more watery consistency for these days (P less than 0.02 to less than 0.005) compared to patients treated with ceftibuten. No clinical relapses were reported and no drug-related side effects were observed. We conclude that ceftibuten is at least as effective as TMP-SMX in the treatment of diarrhea caused by Shigella and enteroinvasive E. coli in children.

Adolescent↗
PubMed1991

Bone mineral density in patients with cervical and trochanteric fractures of the proximal femur.

The bone mineral density (BMD) of the proximal femur, spine and radius shaft was determined in 75 women with atraumatic fractures of the proximal femur (FXf) (average age: 70.1 +/- 9.6 years) and 51 controls of similar age. Fractures were classified as either cervical (n = 36) or trochanteric (n = 39) on the basis of radiographic and surgical finding. The BMD of spine and proximal femur was determined by dual-photon absorptiometry (Lunar DP3) and the BMD of the radius shaft by single photon absorptiometry. The BMD of patients with FXf was significantly decreased over all skeletal sites compared to controls of similar age. No significant correlation was found between age and the BMD of the femoral neck in patients with FXf. Patients with trochanteric FXf were older and thinner (average: age, 72.9 +/- 9.4 years; weight, 53.1 +/- 7.8 kg) compared with patients with cervical fractures (age, 67.2 +/- 8.9 years; weight, 59.3 +/- 8.3 kg). Likewise the BMD of trochanteric FXf was lower at all measured sites: femoral neck, 0.548 +/- 0.066 g/cm2 vs 0.624 +/- 0.055 g/cm2 (P less than 0.001); L2-L4, 0.799 +/- 0.115 g/cm2 vs 0.925 +/- 0.106 g/cm2 (P less than 0.001); radius shaft, 0.454 +/- 0.057 g/cm2 vs 0.502 +/- 0.083 g/cm2 (P less than 0.05). Of the patients with trochanteric fractures 66% had concomitant vertebral fractures, while this occurred in only 28% of the patients with cervical fractures (P (Fisher) = 0.0007). In summary, females with trochanteric FXf are older, thinner, have less bone mass in all measured sites and suffer with a significantly greater frequency of vertebral fractures.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1985

Assessment of Venezuelan health services from a social development perspective.

This paper evaluates four health programs housed in the Venezuelan Ministry of Health and Social Assistance: malaria eradication, infant paralysis, highrisk pregnancy and child birth and community participation. For each of the programs the study (a) identifies key management features relating to structure and strategy; (b) examines program performance to assess its consistency with the declared objective of promoting social development; and (c) evaluates what structure and strategy features may have contributed to the social development of the target community. Also, the information mechanisms which link planners, executors and the 'clients', were examined. Lastly, the extent to which target population involved in the decisions made with respect to each program, was reviewed.

Community Health Services↗
PubMed1982

Distribution of ABO blood groups and other genetic markers in mothers of infants with congenital malformations.

The distribution of ABO and Rh (antigen D) blood groups and of serum albumin, haptoglobin and transferrin variants, in a group of mothers of malformed newborns was investigated. In the first phase of the study, the results showed borderline statistical differences in the distribution of the transferrin types between the study group and a suitable control population. The second phase of the research, where only transferrin phenotypes were studied, showed the same trend as in the first one, but the results were not statistically significant. We conclude that probably there are no true distribution differences, but that it would be desirable to study this problem in a different ethnic group.

ABO Blood-Group System↗