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R Vega

Publications and source records attributed to R Vega.

At least 73 records · Page 4Linked to original sources
PubMed1985

Synergistic effect of 4-hydroperoxycyclophosphamide and etoposide on a human promyelocytic leukemia cell line (HL-60) demonstrated by computer analysis.

Autologous stem cell transplantation using cryopreserved bone marrow offers the opportunity to rescue patients from hematopoietic toxicity caused by intensive chemotherapy. This approach is potentially useful for high-risk leukemias as well as for other cancers. The development of suitable methods for purging malignant cells from the bone marrow will offer a better chance of success for autologous stem cell transplantation. In this paper, we describe our efforts at purging myeloid cells. HL-60, a promyelocytic leukemia cell line, was used as a model. 4-Hydroperoxycyclophosphamide (4-HC) and VP-16-213 (VP-16) (either alone or in combination) were used to treat HL-60 cells and normal bone marrow. The cytotoxic effect of 4-HC (29.2 micrograms/ml; 100 microM) upon the HL-60 cell line was 99.8 +/- 0.12% (SE), and the colony-forming units-granulocyte, macrophage (CFU-cs) of normal bone marrow was inhibited by 82.5%. VP-16, at a concentration of 25 micrograms/ml (42.5 microM), can kill 99% of HL-60 cells and inhibit 72.7% of the CFU-cs. A drug mixture containing 4-HC (29.2 micrograms/ml) and VP-16 (10 micrograms/ml) (combination ratio, 1:0.342) reduces HL-60 cells to an undetectable number, and the CFU-cs were inhibited by 87.2%. The laboratory data were further analyzed for the synergistic effect of these two drugs by quantitative determination of the median effect plot and the multiple drug equation recently described by Chou and Talalay (Adv. Enz. Regul., 22: 27-55, 1984). Interactions of two drugs at different effect levels and at different combination ratios were then determined by computer simulation. At high effect levels, 4-HC and VP-16 in combination gave a synergistic cytocidal effect on HL-60 leukemic cells and gave an antagonistic inhibitory effect on normal bone marrow CFU-cs. This combination greatly increases the safety margin. Computer simulation of a dose effect relationship has also shown that the 4-HC:VP-16 combination ratio of 1:0.342 yields a better selective effect than a ratio of 1:0.856. This quantitative analysis suggests that the combination of these two drugs at the selected dose level offers a good method for purging nonlymphoblastic leukemia cells.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1982

Platelet monoamine oxidase activity in relatives of alcoholics. Preliminary study with matched control subjects.

Platelet monoamine oxidase (MAO) activity levels were determined before and 180 minutes after ingestion of ethyl alcohol in 30 healthy men aged 21 to 25 years. The subjects included 15 men with alcoholic first-degree relatives who were matched by demography, height-weight ratio, and drinking history with 15 control subjects who had no family history of alcoholism. There was a nonsignificant trend toward lower platelet MAO activities at baseline and after ethyl alcohol ingestion in the group with alcoholic relatives when compared with the control subjects who had no family history of alcoholism. With an arbitrary MAO cutoff of 5.24 nmole/mg of protein per hour, eight of the 15 subjects with alcoholic relatives and 12 of the 15 without alcoholic relatives were correctly identified. However, because of the number of false-positive and false-negative findings, the results have limited clinical usefulness.

Adolescent↗
PubMed1981

Dopamine-beta-hydroxylase activity levels in men at high risk for alcoholism and controls.

Plasma DBH activity levels were determined for 22 nonalcoholic young men with alcoholic close relatives (the FHP or family history positive group) and results compared to family history negative (FHN) controls matched on demography, height/weight ratio, and drinking history. These enzyme levels were then correlated with the usual drinking history over the prior 6 months and with the intensity of intoxication achieved after drinking 0.75 ml of ethanol/kg body weight. The FHP men demonstrated a 20% lower level of DBH (p greater than 0.1) indicating no significant difference between the groups. Base-line DBH activities correlated significantly with the level of intoxication for the FHN group (r = 0.44, p less than 0.025) with a trend for an inverse correlation with the average drinking history. FHP men, on the other hand, demonstrated only a nonsignificant association between peak intoxication level and base-line DBH and a positive correlation (r = 0.37, p less than 0.05) with the average number of drinks/drinking day. These results are not consistent with the probability that a premorbid DBH assay could be used as one indicator of propensity towards alcoholism. The differences between FHP and FHN groups on correlations between DBH and peak intoxication or usual drinking history raise speculations that the "normal" (FHN) relationship between alcohol intake and plasma DBH activity may be impaired in individuals at high risk (FHP) for the future development of alcoholism.

Adult↗
PubMed1976

Mechanisms of ampicillin resistance in Haemophilus influenzae type B.

The genetic mechanisms associated with ampicillin resistance in strains of Haemophilus influenzae type b were investigated. In experiments concerned with transfer of total deoxyribonucleic acid in vitro, expression of resistance by wild-type strains occurred at a frequency of about 10%. The minimum inhibitory concentration of ampicillin for the transformed strains was similar to that of the resistant donor strains, and resistance in transformants was associated with acquisition of the ability to produce beta-lactamase. Exposure to 39 mug of acridine per ml for 18 h cured resistance at a frequency of 80%, and there was spontaneous loss of resistance after repeated subculture of some strains. Analysis by cesium chloride-ethidium bromide density gradient centrifugation demonstrated the presence of extrachromosomal deoxyribonucleic acid in the resistant strains, providing further evidence that the resistance factor is plasmid mediated.

Acridines↗
PubMedDate not supplied

Neuroblastoma.

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Adolescent↗
PubMedDate not supplied

Non-Hodgkin's lymphoma.

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Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

The role of acculturation in the substance abuse behavior of African-American and Latino adolescents: advances, issues, and recommendations.

This article provides a review of the literature on the acculturation of Latino and African-American adolescents to traditional European-American cultural values, and the effect on their substance abusing behaviors. The review includes a critical analysis of studies that examine the effects of acculturation on the mental health and well-being of Latino adolescents. Recent findings documenting the association between acculturation and substance abuse among Latino adolescents are discussed. The article also examines the dearth of research on the role of acculturation in the substance-abusing behaviors of African-American adolescents. The authors assert that understanding the effects of acculturation on these behaviors could begin to explain why African-American adolescent substance abuse rates have been historically lower than those of European-American and Latino adolescents. Also included is an examination of research on the role of acculturation in treatment outcomes of Latino and African-American adolescents.

Adolescent↗
PubMedDate not supplied

Effective adjuvant chemotherapy for advanced nasopharyngeal carcinoma in children: a final update of a long-term prospective study in a single institution.

PURPOSE: The purpose of this study was to determine the efficacy and toxicity of a doxorubicin/cyclophosphamide-based chemotherapy and local radiation therapy in children with locally advanced or metastatic nasopharyngeal carcinoma (NPC). PATIENTS AND METHODS: Twelve patients aged 6 to 20 years old were treated with a chemotherapy regimen comprised of vincristine (1.5 mg/m2) and doxorubicin (45 mg/m2) on day 1 and cyclophosphamide (210 mg/m2) and 5-fluorouracil (240 mg/m2) on days 1 to 5. Chemotherapy was administered every 3 weeks for 1 to 2 years. Radiotherapy to the primary site (59 to 68 Gy) and to the neck (59 to 66 Gy) was given before or after 2 to 4 courses of chemotherapy. RESULTS: All patients achieved a complete response 4 to 16 months from the start of therapy (median 7 months). Nine patients have remained tumor free from 2 to 21 years (median 11 years) from diagnosis. One child was lost to follow-up and one died of tuberculosis; both were disease-free. One child developed a secondary osteosarcoma in the left mandible. Chemotherapy caused grade 4 neutropenia and thrombocytopenia in four patients. There were no therapy-related deaths and the most common late effect of therapy was neck fibrosis, which was observed in all patients. We conclude that the chemotherapy and radiotherapy regimen used in this study is highly effective for children and adolescents with locally advanced NPC and is associated with tolerable toxicity.

Adolescent↗
PubMedDate not supplied

Giving birth: Guatemalan women's voices.

OBJECTIVE: To gain an understanding of the cultural meanings of giving birth for Guatemalan women. DESIGN: Ethnographic, focusing on the birth stories of Guatemalan women and their perceptions of the sociocultural context of childbearing. PARTICIPANTS AND SETTING: Thirty Guatemalan women (15 primiparae and 15 multiparae) of mixed Mayan and Ladino heritage who had given birth to healthy full-term infants were interviewed during the early postpartum weeks. These women lived in small villages in the Sacatepéquez District of Guatemala. These audiotaped interviews were conducted in the Nacional Pedro de Bethancourt Hospital, in clinics, in the homes of the women, or in central plazas. RESULTS: The sociocultural context of giving birth in Guatemala is described, including common beliefs about pregnancy and childbirth and the meaning and significance of having children. The predominant themes found were the sacred nature of childbirth; the need for reliance on God during pregnancy, childbirth, and childrearing; and the bittersweet paradox of giving birth. CONCLUSION: With increasing numbers of Central American refugees and immigrants of childbearing age entering the United States, it is important for nurses to recognize, acknowledge, and respect specific cultural practices related to childbearing.

Adolescent↗
PubMedDate not supplied

Isolation of human fungi from soil and identification of two endemic areas of Cryptococcus neoformans and Coccidioides immitis.

The present study was carried out in two different areas of Province of Cordoba, Argentina, where there was a suspicious of endemic mycosis. The previous data were the presence of a clinical case of pulmonary cryptococcosis in one area (Alta Gracia) and the previous findings of a high incidence of coccidioidin and cryptococcin reactors in the population of the second one (Villa Dolores). In both areas soil samples for fungi were studied and Cryptococcus neoformans was found in 2/25 samples from Alta Gracia. In Villa Dolores Coccidioides immitis was isolated in 2/40 samples, and C. neoformans in 1/40 samples. Delayed hypersensitivity test with cryptococcin was determined in the population from Alta Gracia and it was found to be 5.3%. Positive cutaneous tests with coccidioidin (33.8%) and cryptococcin (31.9%) in Villa Dolores were obtained. With these findings two endemic areas of systemic mycoses in Cordoba, Argentina were delimited.

Adolescent↗
PubMedDate not supplied

[Brain vasculitis associated with drugs].

INTRODUCTION: Vasculitis or angiitis is the term used to define the inflammation of the vessels, either blood or lymphatic, which causes may be primary related to immunological disorders, or secondary, with great variety of causal factors. CASE REPORT: We present a very uncommon case of a 36 year old man with brain vasculitis associated with drugs with very peculiar characteristics in the imaging studies and with definite diagnosis through histopathology obtained by biopsy, which differs from the few reports in the literature until our days. CONCLUSIONS: Our report is an uncommon case of cerebral vasculitis whose clinical features were confusing with impressing neuroimaging studies that showed possible lesions due to vasculitis that was confirmed through a cerebral biopsy and considering that the immunological tests were negative for a primary vasculitic process, we concluded that it was a vasculitis secondary to drug abuse which represents a special interest in view of the few existing reports in literature with definite diagnostic methods, such as cerebral biopsy or autopsy.

Adult↗
PubMedDate not supplied

[Ion channels that are sensitive to the extracellular concentration of protons: their structure, function, pharmacology and pathophysiology].

AIM: Acid sensing ion channels (ASIC) members of the ENaC degenerine channel family, have been shown to participate in various sensorial pathways including nociception, also they have been shown to participate in synaptic transmission, learning and memory processes and in the physiopathology of the ischemic stroke. DEVELOPMENT: The proton concentration in the organism is strictly regulated by distinct buffer systems. Drastic changes of pH are generated only by pathological conditions as is the ischemia; however, some physiological processes may produce local changes in the extracellular pH. Recently, a new family of proton receptors known as ASIC has been cloned. These are ionic channels inactivated at physiological pH (7.4) and activated with a pH fall (increase in H+ concentration). ASICs are permeable to sodium ions and in a lesser degree to calcium ions, activation of these channels leads to an increase in cell excitability. The ASICs are distributed widely in the central and peripheral nervous system, and in specialized epithelia. In the past few years they have become a focus of interest due to its role in nociception, taste perception, long term potentation and the physiopathology of ischemic stroke. CONCLUSIONS: In this review we address the most relevant molecular, physiological and pharmacological aspects of the ASICs, its participation in some pathological process, and the perspectives of basic and clinic investigation in this arising research field.

Acid Sensing Ion Channels↗