PubMed Health⌕ Search

Biomedical subjects

S Mendoza

Publications and source records attributed to S Mendoza.

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

Simian virus 40 is present in human lymphomas and normal blood.

Many independent studies have demonstrated Simian virus 40 (SV40) in normal and neoplastic human tissues. Clonal integration of virus in the DNA of several thyroid and bone tumors suggests a direct role for SV40 in some cancers. However, in most cases the role of SV40 remains unclear. This study determined the presence of SV40, by amplification followed by hybridization, in 266 normal and neoplastic blood and lymphoid samples. Amplification detected SV40 in 14% of non-autoimmune deficiency syndrome (AIDS) lymphomas, 28% of AIDS related lymphoma and 16% of peripheral blood lymphocytes from non-cancerous patients. No SV40 was detected in leukemia samples. Direct Southern blotting of SV40+ samples detected no virus, consistent with less than one viral genome in ten cells. Sequence analysis of SV40 in blood and lymphoid samples found sequences distinct from laboratory strains of SV40. The presence of limited quantities of SV40 in a small proportion of both normal and neoplastic tissues is suggestive of an adventitious presence with no apparent direct role in blood and lymphoid cancers.

Antigens, Polyomavirus Transforming↗
PubMed2001

The effect of vaccination with the PAV-250 strain classical swine fever (CSF) virus on the airborne transmission of CSF virus.

The airborne transmission of Classical Swine Fever (CSF) virus to susceptible pigs, as well as the effect of vaccination with the CSF virus PAV-250 strain was investigated on this mode of transmission. Experiment I: four pigs were inoculated with the ALD CSFV strain (10(4.3) 50% TCID) by the intramuscular route, and at the onset of fever, they were introduced into an enclosed chamber. At the end of the experiment surviving pigs were sedated, anesthetized and euthanatized. Experiment II: four pigs were previously vaccinated with the CSF virus PAV-250 strain, and at 14 days post-vaccination they were challenged with the CSF virus ALD strain. In both experiments, four susceptible pigs were exposed to infectious aerosols by placing them in a chamber connected by a duct to the adjacent pen containing the infected animals and were kept there for 86 hs. In Experiment I, pigs exposed to contaminated air died as a result of infection with CSF virus on days 14, 21 and 28 post-inhalation. These four pigs seroconverted from day 12 post-inhalation. CSF virus was isolated from these animals, and the fluorescent antibody test on tonsils was positive. In Experiment II, a vaccinated pig exposed to contaminated air did not seroconvert, nor was CSF virus isolated from lymphoid tissues. However, mild fluorescence in tonsil sections from these pigs was observed. In conclusion, CSF virus was shown to be transmitted by air at a distance of 1 m to susceptible pigs. Vaccination with the PAV-250 CSF virus strain protected the pigs from clinical disease under the same conditions.

Air Microbiology↗
PubMed2000

Postprandial triglyceride response in patients with polycystic ovary syndrome: relationship with waist-to-hip ratio and insulin.

OBJECTIVE: To examine the postprandial triglyceride response to a high-fat meal in women with polycystic ovary syndrome (PCOS) compared with a matched control group. DESIGN: Controlled clinical study. SETTING: Department of Endocrinology and Pathophysiology, School of Medicine, Universidad de Los Andes. PATIENT(S): 18 Hispanic women with PCOS (nine overweight and nine nonobese) and 9 healthy control women. INTERVENTION(S): Biometric measures and blood sample collection. MAIN OUTCOME MEASURE(S): Insulin and glucose levels during a standard oral glucose tolerance test. Plasma triglyceride, cholesterol, and high-density lipoprotein cholesterol levels were measured at baseline and at 4, 5, and 6 h after a high-fat meal. RESULT(S): Both obese and nonobese PCOS women had higher waist-to-hip ratios than controls. PCOS women had higher levels of fasting and postglucose insulin and fasting triglyceride and postprandial triglyceride response and had lower levels of postprandial high-density lipoprotein cholesterol response, but no significant differences within PCOS groups were observed. CONCLUSION(S): An expanded postprandial hypertriglyceridemia in PCOS women is related to a higher waist-to-hip ratio and insulin resistance, regardless of obesity, and contributes to increase the risk for coronary artery disease.

Adult↗
PubMed2000

The effect of intercourse on pregnancy rates during assisted human reproduction.

Intercourse during an IVF cycle has the potential to improve pregnancy rates since exposure to semen is reported to promote embryo development and implantation in animals. Conversely, coitus-induced uterine contractions or introduction of infection may have a detrimental effect. A multicentre prospective randomized control trial was conducted to determine if intercourse during the peri-transfer period of an IVF cycle has any influence on pregnancy success. Participants undergoing thawed embryo transfer (Australian centre) or fresh embryo transfers (Spanish centres) were randomized either to abstain or to engage in vaginal intercourse around the time of embryo transfer. The transfer of 1343 embryos during 478 cycles of IVF resulted in 107 pregnancies (22.4%), with 125 viable embryos remaining by 6-8 weeks gestation. There was no significant difference between the intercourse and abstain groups in relation to the pregnancy rate (23.6 and 21.2% respectively), but the proportion of transferred embryos that were viable at 6-8 weeks was significantly higher in women exposed to semen compared to those who abstained (11.01 versus 7.69 viable embryos per 100 transferred embryos, P = 0.036, odds ratio 1.48, 95% confidence interval 1.01-2.19). Hence exposure to semen around the time of embryo transfer increases the likelihood of successful early embryo implantation and development.

Coitus↗
PubMed1999

Rb independent inhibition of cell growth by p15(INK4B).

The INK4 cyclin dependent kinase inhibitors (CDKI), such as p15(INK4B) and p16(INK4A), block cell cycle progression from G to S phase. This is mediated by inhibition of phosphorylation of proteins, including the retinoblastoma susceptibility protein (Rb), by cyclin dependent kinases. Ectopic over-expression of the p16(INK4A) CDKI can inhibit growth of cell lines depending on Rb status. Cell lines lacking Rb, with few exceptions, are resistant to growth inhibition by p16(INK4A). The effects of ectopic over-expression of p15(INK4B) in cell lines with and without wild type Rb were examined by measuring cell recovery. Proliferation was inhibited in cells lacking Rb as well as in cells with wild type Rb expression. Experiments analyzing the effectiveness of chimeric p15(INK4B)/p16(INK4A) proteins indicated that the Rb independent growth inhibition required N-terminal residues of p15(INK4B). Linker insertion mutation of p15(INK4B) showed that the inhibition was dependent on intact ankyrin structures. Double staining flow cytometry found that the growth inhibition correlated with a decrease in cells in G2/M phases of the cell cycle. These findings are consistent with Rb independent inhibition of the progression from G1 to S caused by overexpression of p15(INK4B).

Carrier Proteins↗
PubMed1999

Phase I trial of escalating doses of paclitaxel plus doxorubicin and dexrazoxane in patients with advanced breast cancer.

PURPOSE: To determine the maximum-tolerable dose (MTD) of paclitaxel given as a 3-hour intravenous (IV) infusion that could be used in conjunction with doxorubicin and dexrazoxane, and to determine the effect of dexrazoxane on the pharmacokinetics of paclitaxel and doxorubicin. PATIENTS AND METHODS: Twenty-five patients with advanced breast cancer received dexrazoxane (600 mg/m2 by IV infusion over 15 minutes), followed 15 minutes later by doxorubicin (60 mg/m2 IV), followed 15 minutes later by paclitaxel (150 or 175 mg/m2 by IV infusion over 3 hours) in cohorts of three to six patients using a standard phase I design without (group A) and with (group B) granulocyte colony-stimulating factor (G-CSF). Treatment continued until there was a substantial decrease in the left ventricular ejection fraction (LVEF), congestive heart failure, progressive disease, or physician discretion to discontinue. RESULTS: The MTD of paclitaxel was 150 mg/m2, and adjunctive therapy with G-CSF was required to prevent febrile neutropenia. Dexrazoxane had no significant effect on the pharmacokinetics of paclitaxel or doxorubicin. After a median cumulative doxorubicin dose of 360 mg/m2 (range, 60 to 870 mg/m2), no patient developed congestive heart failure or had a decrease in LVEF below normal. An objective response occurred in all five patients with locally advanced breast cancer and in eight of 20 patients (40%; 95% confidence interval, 19% to 61%) with metastatic breast cancer. CONCLUSION: When combined with doxorubicin (60 mg/m2) and dexrazoxane (600 mg/m2), paclitaxel given as a 3-hour infusion had an MTD of 150 mg/m2, and G-CSF was required to prevent febrile neutropenia. Dexrazoxane had no effect on the pharmacokinetics of paclitaxel or doxorubicin. No patient in this trial had a decrease in the LVEF below normal, compared with about 20% to 50% of patients treated with doxorubicin and paclitaxel without dexrazoxane in other trials.

Adolescent↗
PubMed1998

Nonsteroidal anti-inflammatory drug use in adolescence.

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been recently released as over-the-counter drugs making them more widely available to the general public. We present five cases of adolescents with complications, including acute and chronic renal failure, related to the use of NSAIDs. Risk factors for NSAID nephrotoxicity include chronic illness, dehydration, ethanol and use of other medications. Adolescents should be educated about the risks and prevention of NSAID toxicity.

Acute Kidney Injury↗
PubMed1998

MMPI-2 and MMPI-A research with U.S. Latinos: a bibliography.

This bibliography presents a comprehensive listing of all research conducted on U.S. Latinos, including Puerto Ricans, with the MMPI-2 and MMPI-A beginning in 1989. A total of 52 studies and 6 additional resources are listed. Researchers and clinicians could use this bibliography for the culturally appropriate application of the MMPI-2/MMPI-A with this growing population.

Hispanic or Latino↗
PubMed1998

Effect of policosanol on platelet aggregation in type II hypercholesterolemic patients.

Policosanol is a cholesterol-lowering drug with concomitant antiplatelet effects proved in experimental models and healthy volunteers. This study reports the results of a 4-week, randomized, double-blind, placebo-controlled trial investigating the effects of policosanol on platelet aggregation in type II hypercholesterolemic patients. Patients started or continued on a step-one cholesterol-lowering therapy for 4 weeks and those with total cholesterol > 5.0 mmol/L despite dietary conditions were randomized to receive under double-blind conditions placebo or policosanol (10 mg/day) for 30 days. Both groups were similar at randomization. Effects of policosanol on platelet aggregation induced by arachidonic acid (3.2 mM), collagen (0.5-1 microgram/ml) and ADP (0.5-1 uM) were determined at baseline and after 30 days of treatment. Policosanol significantly reduced platelet aggregation induced by arachidonic acid and collagen, meanwhile it only inhibited significantly the platelet aggregation induced by the lowest doses of ADP (0.5 uM). No adverse events occurred during the trial. Only one patient (placebo) discontinued from the study because of arthralgia.

Adenosine Diphosphate↗
PubMed1997

The p19INK4D cyclin dependent kinase inhibitor gene is altered in osteosarcoma.

Inhibition of cyclin dependent kinases (CDK) by cyclin dependent kinase inhibitors (CDKI) blocks cell cycle progression and inhibits cellular proliferation. The archetypical member of the INK4 CDKI family, p16INK4A (also called CDKN2), is a tumor suppressor frequently deleted or mutated in certain neoplasms and many cell lines. Because p19INK4D has strong structural and functional similarity to p16INK4A, we have assessed its role as a tumor suppressor. This was accomplished by screening the p19INK4D coding region for mutations, deletions and rearrangements in sarcomas and non-small cell lung cancers. Alterations of the p19INK4D gene were found in samples from five of 67 (7%) patients with osteosarcomas and none were found in other types of sarcomas or in lung cancers. Five osteosarcoma samples had Southern blot patterns consistent with gene rearrangement. These samples included a primary and recurrent osteosarcoma from the same patient; both with the same rearrangement. Four samples had SSCP patterns consistent with sequence alterations, sequencing determined that three were due to silent base changes and apparently polymorphisms. Sequencing the fourth shifted band revealed a one base insertion causing a frameshift beginning with codon 27. In summary, these studies found alterations affecting the p19INK4D gene in a small but significant number of osteosarcomas. Presumably, abnormalities of this gene contribute to the development of cancer of bone cells.

Carrier Proteins↗
PubMed1997

Integrity of the 1,25-dihydroxyvitamin D3 receptor in bone, lung, and other cancers.

Differentiation and proliferation can be regulated in diverse cell types by 1,25-dihydroxyvitamin D3. These effects derive from modulation of gene expression mediated by the interaction of 1,25-dihydroxyvitamin D3 with the vitamin D receptor (VDR). The VDR is one of the nuclear hormone receptors. Because these transcription factors play a key role in growth control, some nuclear hormone receptors, such as the retinoic acid receptor alpha, can be disrupted in cancer. With these alterations in mind, we looked for alterations of the VDR gene in a variety of cancers, including 68 osteosarcomas, 23 other sarcomas, 34 non-small cell lung cancers, and 44 cell lines representing many tumor types. Gross integrity of the VDR gene was examined on Southern blots probed with the coding region of the VDR cDNA. The presence of point mutations targeting VDR exons 2-7 was assessed by polymerase chain reaction-single-strand conformation polymorphism analysis and direct DNA sequencing. Two alterations were detected; direct DNA sequencing of these samples revealed one silent mutation in codon 79 and a base change in intron 3. These results suggest that mutations and rearrangement of the VDR do not play a role in the cancers studied.

Blotting, Southern↗
PubMed1995

Vasoactive effects of aqueous extracts from five Mexican medicinal plants on isolated rat aorta.

The present investigation describes the effects of aqueous extracts from Chiranthodendron pentadactylon flowers, Galphimia glauca leaves and flowers, Ipomoea stans roots, Juglans regia leaves and Taxodium mucronatum aerial parts on isolated rat thoracic aorta precontracted by noradrenaline (NA). In all cases, the aqueous extracts (0.5-12 mg/ml) significantly inhibited, in a concentration-dependent manner, the maximal contractile response induced by NA in rat aorta. The most active extract was that of G. glauca flowers. These findings indicate that the active principle(s) present in the crude extracts can exert a vasorelaxant effect.

Animals↗
PubMed1994

Metformin therapy in polycystic ovary syndrome reduces hyperinsulinemia, insulin resistance, hyperandrogenemia, and systolic blood pressure, while facilitating normal menses and pregnancy.

Using polycystic ovary syndrome (PCOS) as a model of insulin resistance and hyperandrogenism, our specific aim was to assess the effect of Metformin on lipoproteins, sex hormones, gonadotropins, and blood pressure in 26 women with PCOS who were studied at baseline, received Metformin 1.5 g/d for 8 weeks, and were then restudied. None of the women had normal menstrual cycles, 100% had multiple subcapsular follicules by pelvic ultrasound, 90% were hirsute, and 85% had high free testosterone. Comparing post-Metformin versus baseline levels, the Quetelet Index (QI) decreased 1.5% (P = .04) and the waist to hip ratio (WHR) decreased 2.8% (P = .003). After covariance adjusting for changes in the QI and WHR, on Metformin the area under the insulin curve (IA) during oral glucose tolerance testing decreased 35% (P = .04), and the insulin area to glucose area ratio decreased 31% (P = .03). On Metformin, covariance-adjusted systolic blood pressure (SBP) decreased (P = .04) and apo A-1 increased (P = .05). On Metformin, with improvement in insulin sensitivity, there were sharp reductions in covariance-adjusted luteinizing hormone ([LH] P = .0007), total testosterone ([T] P = .0004), free T (P = .0001), androstenedione (P = .002), dehydroepiandrosterone sulfate ([DHEAS] P = .006), and the free androgen index ([FAI] P = .0005), with increments in follicle-stimulating hormone ([FSH] P = .04) and sex hormone-binding globulin ([SHBG] P = .04).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Role of nitric oxide in renal hemodynamic abnormalities of cyclosporin nephrotoxicity.

To evaluate the participation of nitric oxide (NO) in chronic cyclosporin A (CsA) nephrotoxicity, the glomerular hemodynamic response to NO inhibition with N-nitro-L-arginine-methyl-ester (NAME) and stimulation of NO production with L-arginine was studied in uninephrectomized rats. Chronic CsA administration produced renal vasoconstriction, characterized by increased afferent (AR) and efferent (ER) resistances, decrease of glomerular plasma flow (QA) and ultrafiltration coefficient (Kf) that resulted in a 53% fall of single-nephron glomerular filtration rate (SNGFR). NAME infusion in vehicle group (V) elevated mean arterial pressure (MAP), AR and ER, reduced qA and Kf, and increased glomerular capillary pressure (PGC), resulting in a 28.9% fall of SNGFR. In the CsA group, NAME also increased MAP, but renal vasoconstriction was more intense; a greater rise of AR lowered PGC (P < 0.05 vs. V) further decreasing SNGFR by 38.9%. In control rats, L-arginine infusion induced a vasodilatory response of AR and ER, and elevation of QA and Kf, which resulted in a 72.6% increase in SNGFR. In the CsA group, greater vasodilation was observed and SNGFR rose by 114.9%. NO2-/NO3- urinary excretion was similar in CsA and V groups, and it was not modified by NAME in either group, but it increased five- to sixfold during L-arginine infusion in both groups. In conclusion, in CsA nephrotoxicity NO production seems to be normal and the ability of the renal endothelium to produce NO is maintained. Therefore renal vasoconstriction associated with CsA is not mediated by NO deficiency, although NO appears to attenuate it.

Animals↗