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Biomedical subjects

M López

Publications and source records attributed to M López.

At least 91 records · Page 5Linked to original sources
PubMed2000

Distant metastases in head and neck cancer patients who achieved loco-regional control.

BACKGROUND: One of the reasons for failure in patients with head and neck carcinoma who achieve locoregional control with treatment is the appearance of distant metastases. The objective of this study was to evaluate the frequency of distant metastases in this group of patients and to determine the relative role of several prognostic factors in the subsequent development of distant metastases. DESIGN: Retrospective study from a database that collects the information prospectively in a cohort of patients with head and neck carcinoma. Patients and Methods The study was carried out in 1244 patients with oral cavity, pharyngeal, or laryngeal carcinoma who achieved locoregional control. We evaluated the frequency of distant metastases and the influence of different variables in their appearance. RESULTS: Five percent of patients with locoregional control had distant metastases. In the univariate study, the variables that influenced the appearance of distant metastases were tumor site, T stage, N stage, and histologic differentiation. On multivariate analysis, the variables that increased the risk of distant metastases were N stage, T stage, and the location of the tumor at the hypopharynx and the supraglottis. CONCLUSIONS: Five percent of patients with oral cavity, pharyngeal, or laryngeal carcinomas who achieved locoregional control died as a consequence of the development of distant metastases. The factors that significantly increased the risk of distant metastases in this group of patients were the advanced local and regional extension of the tumor and the location at the hypopharynx or supraglottis.

Aged↗
PubMed2000

Synthesis of (Z)-2-(2-formamido-4-thiazolyl)-2-(substituted alkoxyimino) acetic acids.

(Z)-2-(2-formamido-4-thiazolyl)-2-(substituted alkoxyimino) acetic acids were synthesized by a new method based on the following sequence of reactions: treatment of the tert-butyl acetoacetate with sodium nitrite, alkylation of the oxime formed with an appropriate alkyl halide, halogenation of methyl alpha-keto group and simultaneous cleavage of tert-butyl ester with sulfuryl chloride, protection of the obtained acid function with diphenyldiazomethane, formation of the 2-aminothiazole ring by the Hantzsch method with thiourea, formylation of the amino group and selective final cleavage of the diphenylmethyl ester by treatment with trifluoroacetic acid and anisol. The developed procedure allows the synthesis of (Z)-2-(2-formamido-4-thiazolyl)-2-(substituted alkoxyimino) acetic acids, with an ester function in the alkoxyimino group employing a simple method and obtaining higher yields in comparison with the habitually used classic method.

Acetates↗
PubMed2000

[Analysis of biologic changes in PSA blood concentration and free PSA percentage in patients with normal rectal digital examination].

OBJECTIVE: To study intra-individual variations in serum PSA and percent free PSA in patients with normal digital rectal examination. MATERIAL AND METHODS: Analysis of changes in serum PSA levels and percent free PSA in two blood measurements conducted in 107 non-consecutive patients prior to prostate biopsy, over a period of time ranging from 23 to 60 days. Both total and free PSA were measured with two dual monoclonal antibody assays, Tandem-E and Tandem-R, Hybritech. Diagnosis was benign hyperplasia in 63 patients and cancer in 44. RESULTS: PSA variations ranged between -6.8 and +3.2 ng/ml in BPH patients, and between -2.8 and +9.0 when cancer was detected. The median coefficient of variation was 15.4 and 15.7, respectively. Variations in percent free PSA ranged between -30.7 and +40.9 in the BPH group and between -17.9 and +15.8 in the cancer group. The median coefficient of variation was 32.2 and 32.3%, respectively. Should prostate biopsy had been indicated when percent free PSA was equal to or lower than 25 in the 4 to 10 ng/ml PSA range, 15% patients would have exhibited discrepancies. Sensitivity would have ranged between 100 and 94.4%, with a reduction rate in negative biopsies between 16.6 and 19.4%. CONCLUSIONS: Intra-individual variations in serum PSA levels and percent free PSA may condition the decision of whether to perform a prostate biopsy.

Aged↗
PubMed2000

Catheter ablation of repetitive monomorphic ventricular tachycardia from left ventricular outflow tract guided by unipolar mapping.

Repetitive monomorphic ventricular tachycardia from the left ventricular outflow tract is an uncommon arrhythmia. Successful catheter ablation has been previously reported in a few cases, but a large number of applications were usually needed when an approach based on either activation mapping or pace mapping was used. In our patient, the selection of the target point for application was based exclusively on unipolar mapping criteria of the ectopic beats, resulting in a short procedure with successful outcome.

Aged↗
PubMed2000

Effect of high-grade prostatic intraepithelial neoplasia on total and percent free serum prostatic-specific antigen.

OBJECTIVE: To analyze the influence of high-grade prostatic intraepithelial neoplasia (HGPIN) on total serum prostatic-specific antigen (PSA) and percent free PSA. METHODS: Total and free serum PSA were determined in 81 consecutive patients with clinical T1c prostate cancer who underwent radical prostatectomy. HGPIN was detected in 62 specimens (76.5%). RESULTS: Median total PSA was 9.2 ng/ml when there was not HGPIN and 8.1 ng/ml when it existed, p>0.05. Median percent free PSA was 11.7 and 9.1%, respectively, p<0.03. However, a multiple linear regression analysis demonstrated there was no effect of HGPIN on total PSA nor on percent free PSA. Percent free serum PSA was significantly influenced by total PSA and the pathological tumor stage. CONCLUSION: HGPIN does not seem to contribute significantly on serum total PSA and percent free PSA.

Adult↗
PubMed2000

Prediction of prostate volume based on total and free serum prostate-specific antigen: is it reliable?

OBJECTIVE: To analyze the utility of total/free prostate-specific antigen (PSA) and age as predictors of the prostate volume in men with symptomatic benign prostatic hyperplasia (BPH) and no evidence of prostate cancer. PATIENTS AND METHODS: Total and free serum PSA were determined in 681 patients with normal digital rectal examination and symptomatic BPH using the Hybritech method. Prostate volume was measured by transrectal ultrasound (TRUS). TRUS-guided biopsy was performed in 459 (67.4%) of the patients with a serum PSA >4.0 ng/ml. RESULTS: The relationship with prostate volume was best described in a log linear fashion by free PSA (R(2) = 0.367), total PSA (R(2) = 0.264) and age (R(2) = 0.017). Multiple linear regression demonstrates no significant influence of age. Free PSA was able to predict the individual TRUS prostate volume +/-10% in 67% of the patients and +/-20% in 91.2% and total PSA in 63 and 90. 9%, respectively. CONCLUSION: Prostate volume is strongly related with free and total PSA. Both determinations would be able to predict the TRUS prostate volume +/-20% in more than 90% of the patients.

Adult↗
PubMed2000

A mutation in the 5' non-high mobility group box region of the SRY gene in patients with Turner syndrome and Y mosaicism.

In Ullrich-Turner syndrome (UTS) patients, the presence of a Y-chromosome or Y-derived material has been documented in frequencies ranging from 4-61%. Mutations of SRY (testis-determining gene) constitute the cause of XY sex reversal in approximately 10-15% of females with pure gonadal dysgenesis. Most of these mutations have been described in the HMG (high mobility group) box of the gene, which is the region responsible for DNA binding and bending; however, various mutations outside the HMG box have been reported. We carried out molecular studies of the SRY gene in three patients with a UTS phenotype and bilateral streaks; two presented a 45,X/46,XY mosaic, and the third a Y marker chromosome. In two patients a missense mutation, S18N, was identified in the 5' non-HMG box region in DNA from blood and both streaks; this mutation was not identified in 75 normal males. Sequencing of the DNA region of interest was normal in the father and older brother of patient 1, demonstrating that in this patient the mutation was de novo. A previous report of a 46,XY patient with partial gonadal dysgenesis who presented the same mutation as our patients indicates the probable existence of a hot spot in this region of the SRY gene and strengthens the possibility that all gonadal dysgeneses constitute part of a spectrum of the same disorder. It also demonstrates that a single genetic abnormality can result in a wide range of phenotypic expression.

Adolescent↗
PubMed1999

Thermal inactivation of Bacillus cereus spores affected by the solutes used to control water activity of the heating medium.

The heat resistance of B. cereus spores (ATCC 7004, 4342 and 9818) over a wide temperature range (92-125 degrees C) in aqueous solutions of NaCl, LiCl, sucrose and glycerol at different water activities (1.00-0.71) was investigated. Sodium chloride in the heating medium tended to protect the spores of B. cereus against heat. The z-values increased significantly (P < 0.05) at and above a concentration of 4.0 M. The effects of LiCl were lower than those caused by the NaCl at the same a(w) values. An increase in z-values was observed. but the differences were only statistically significant (P<0.05) at the highest concentration tested (5.0 M). A concentration of sucrose 0.87 M caused in all cases a reduction in D-values, which was most pronounced for strains 4342 and 9818. With increasing concentration of sucrose ( > 0.87 M), the D-values showed an increase, although only those obtained for strain 4342 in sucrose solutions 2.22 M were higher than those found in pure water. The z-values were significantly higher (P < 0.05) when sucrose was added at concentrations above 1.42 M, except for strain 4342. When a(w) was lowered from 0.96 to 0.71 with glycerol, D-values obtained gradually increased, about 30, 50 and 60 fold for 4342, 7004 and 9818 strains, respectively. No significant effect on z-values were detected.

Bacillus cereus↗
PubMed1999

Thermal inactivation of Bacillus cereus spores formed at different temperatures.

The effects of the sporulation temperature in the range 20-45 degrees C on the D and z values of three isolates of Bacillus cereus (ATCC 4342, 7004 and 9818) were investigated. The strains were found to differ in their response. Higher D100 values (around 10-fold) were obtained with isolates 4342 and 9818 when the sporulation temperature increased from 20 to 45 degrees C. With isolate 7004 (the least heat resistant of the three strains), however, the most thermal tolerant spores were obtained at 35 degrees C. The z values were not significantly modified (P > 0.05) by the sporulation temperature. Mean z values of 7.46+/-0.22 degrees C for isolate 4342, 7.80+/-0.40 degrees C for 7004 and 8.09+/-0.33 degrees C for 9818 were obtained.

Bacillaceae Infections↗
PubMed1999

[Chronic prescription of drugs for geriatric patients at an urban health center].

OBJECTIVE: To find the chronic prescription of medication in older people, associated variables and its quality. DESIGN: Observation, descriptive-crossover study. SETTING: Urban health district. PATIENTS: Sample stratified in age and sex groups of 385 people of 65 and over registered at the health centre and not in institutions. MEASUREMENTS AND MAIN RESULTS: Social and demographic data, self-perception of health and functional capacity were obtained through interview; and pathology and medication records, from the clinical records and authorized medication cards. 349 people, average age 73 (SD +/- 6.5), were interviewed. There were 210 women and 139 men. 12% perceived their health as bad/very bad. Barthel's index and the Lawton scale were disturbed in 13.8% and 30.4%, respectively. 93% suffered some chronic pathology (average 2.7). 81.4% habitually took medication (average 3.1). The most commonly consumed drugs belonged to the cardiovascular (32%), nervous system (21%) and digestive apparatus and metabolism (17%) groups. For the first group, the main drugs were ACEIs and diuretics; for the second, analgesics and neuroleptics; for the third, antacid and antiulcer drugs. 86% had high intrinsic value, the most prescribed drugs of those with low intrinsic value belonged to the antivaricose, cerebral and peripheral vasotherapy, and urological drugs groups. Multiple medications was related significantly to having more than two chronic pathologies (OR = 7.89, 95% CI 4.40-14.15) and self-perception of worse health (OR = 2.51, 95% CI 1.13-5.59). CONCLUSION: The elderly persons with a greater number of pathologies and perception of worse health took more medication. We thought that our quality of prescription was acceptable, although we should review the indications for neuroleptics and reduce prescription for medication of low therapeutic value.

Age Factors↗
PubMed1999

Scant XYqh- testicular cells with normal SRY was enough to differentiate bilateral testes in a 45,X/46,XYqh- patient.

OBJECTIVE: It has been established that in 45,X/46,XY individuals predominance of XY or XO gonadal cells determines gonadal differentiation. However, in some cases there is no concordance between the predominance of XY cells and testis differentiation. Here we describe the SRY findings in a patient bearing a 45,X/46,XYqh- karyotype. STUDY DESIGN: The patient presented two small testes (one with spermatogenesis), a male phenotype, and a predominant 45,X karyotype in leukocytes and gonadal cells. PCRs of SRY, ZFY and Yqh were performed on DNA from leukocytes and from left gonadal tissue. SRY-PCR products were purified and sequenced. RESULTS: A normal SRY sequence was found in both tissues. CONCLUSIONS: Despite the predominance of 45,X cells in gonads, some patients in whom SRY is normal can develop testes, probably due to the presence of alternative mechanisms involved in testicular differentiation; however, further gonadal development could be impaired.

Animals↗
PubMed1999

Value of routine transition zone biopsies in patients undergoing ultrasound-guided sextant biopsies for the first time.

OBJECTIVE: To analyze the efficacy of routine transition zone biopsies in patients undergoing ultrasound-guided sextant biopsies for the first time because of a suspicious digital rectal examination (DRE) or an elevated serum prostate-specific antigen (PSA) level. PATIENTS AND METHODS: During sextant prostatic biopsy two additional transition zone biopsies were performed in 164 consecutive patients: in 98 because of a serum PSA of >4.0 ng/ml, and in 66 because of a suspicious DRE. RESULTS: The overall cancer detection rate was 46.9% (77/164). In 28 patients (36.4%) cancer was only detected in the peripheral zone, in 2 (2.6%) only in the transition zone and in 47 (61%) in both zones. CONCLUSION: Routine transition zone biopsies performed at the time of a first sextant biopsy seem to have low efficacy.

Aged↗
PubMed1999

Intraindividual variations of total and percent free serum prostatic-specific antigen levels in patients with normal digital rectal examination.

PURPOSE: To analyze intraindividual variations of total and percent free serum prostate-specific antigen (PSA) in patients with normal digital rectal examination. MATERIAL AND METHODS: Total and free serum PSA were determined in two blood samples corresponding to 107 nonconsecutive patients. The period between both determinations ranged from 23 to 60 days. Prostatic biopsy was done after both determinations in all except 17 patients because the two serum PSA concentrations were <4 ng/ml. Total and free PSA were determined using double monoclonal antibody immunoassay Tandem and Tandem free (Hybritech Inc.). The diagnosis was benign prostatic hyperplasia (BPH) in 63 patients and prostate cancer (PCA) in 44. RESULTS: The variations of PSA ranged between -6.8 and +3.2 ng/ml in BPH patients and between -2.8 and +9.0 in patients with PCA. The median coefficients of variation were 15.4 and 15.7% respectively. The variations in the percent free PSA were between -30.7 and +40.9 in the BPH group and between -17.9 and +15.8 in the PCA group. The median coefficients of variation were 32.2 and 32.3% respectively. If prostatic biopsy had been indicated when percent free PSA had been </=25 in the PSA range of 4.1-10 ng/ml, we would have found discrepancies in 15% of all the patients. The sensitivity for the first determination would have been 100 and 94.4% for the second. The rate of negative biopsies would have been reduced by 16.6 and 19. 4% respectively. CONCLUSIONS: Intraindividual variations in serum PSA concentration and percent free PSA could have clinical implications in the decision to perform prostatic biopsy.

Aged↗
PubMed1999

Orexin receptors are expressed in the adrenal medulla of the rat.

Two recently discovered hypothalamic peptides, orexin-A and orexin-B, play a role as mediators in the central mechanisms that regulate feeding behavior and sleep control. These peptides bind and activate two orexins receptors that belong to the G-protein coupled receptor superfamily. Morphological studies have detected mRNA expression of orexin receptors exclusively in the rat central nervous system. In this paper we demonstrate a strong level of expression of orexin receptor 1 and 2 in the adrenal medulla of the rat by RT-PCR and immunohistochemistry. The results of the present study provide the first evidence showing that the adrenal medulla expresses orexin receptors, and thus appears to be a target tissue for orexins. This could open a new loop in which the central and autonomous nervous system may be involved in body weight homeostasis and sleep control.

Adrenal Medulla↗
PubMed1999

Computer-assisted comparison of the structural and electronic dispositions of ebastine and terfenadine.

OBJECTIVE: Ebastine and terfenadine are both marketed nonsedating H1 histamine receptor antagonists. Although apparently similar in chemical structure, the compounds have different pharmacological profiles, particularly with respect to cardiac effects. These effects are consistently observed in a wide range of experimental models with terfenadine, but not with ebastine, despite the fact that the latter is more potent as an antihistamine. The objective of this study was to provide a structural basis to explain such differences. DESIGN: A complete computer-assisted conformational and electronic characterisation was made for both drugs. RESULTS: The preferred 3-dimensional spatial orientations were found to be different, as were the molecular locations of the highest occupied and lowest unoccupied molecular orbitals. Furthermore, for terfenadine, additional points of interaction as a hydrogen bond donor were found, which were not evident in ebastine or other noncardiotoxic antihistamines. These extra points of interaction were also found in other compounds that have shown cardiac effects similar to those of terfenadine.

Butyrophenones↗
PubMed1999

Heat resistance of Bacillus cereus spores: effects of milk constituents and stabilizing additives.

Heat resistance of Bacillus cereus spores (ATCC 7004, 4342, and 9818) heated in different types of milk (skim, whole, and concentrated skim milk), skim milk containing stabilizing additives (sodium citrate, monopotassium phosphate, or disodium phosphate, 0.1%), and cream was investigated. Thermal resistance experiments were performed at temperatures within the range of 92 to 115 degrees C under continuous monitoring of pH. For strain 4342 no significant differences (P < 0.05) in D values were detected in any case. For strains 7004 and 9818 higher D values of about 20% were obtained in whole and concentrated skim milk than those calculated in skim milk. From all stabilizing additives tested, only sodium citrate and sodium phosphate increased the heat resistance for strain 9818. However, when the menstruum pH was measured at the treatment temperature, different pH values were found between the heating media. The differences in heat resistance observed could be due to a pH effect rather than to the difference in the substrates in which spores were heated. In contrast, when cream (fat content 20%) was used, lower D values were obtained, especially for strains 7004 and 9818. z values were not significantly modified by the milk composition, with an average z value of 7.95+/-0.20 degrees C for strain 7004, 7.88+/-0.10 degrees C for strain 4342, and 9.13+/-0.16 degrees C for strain 9818.

Animals↗