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Biomedical subjects

M López

Publications and source records attributed to M López.

At least 109 records · Page 6Linked to original sources
PubMed1999

[Influence of prostatic intraepithelial neoplasia on blood levels of PSA and free PSA percentage].

OBJECTIVE: To analyze the influence of prostatic intra-epithelial neoplasia (PIN) on serum total PSA levels and free PSA percentage. MATERIAL AND METHODS: Total and free PSA concentrations (IRMA Tandem and Tandem free PSA, Hybritech Inc) were determined in 349 patients with normal DRE and PSA greater than 4 ng/ml, undergoing prostatic biopsy by sextant and in 81 patients with prostate cancer in clinical stage T1c N0 M0 undergoing radical prostatectomy. In the group of patients undergoing prostatic biopsy, benign hyperplasia was diagnosed in 284 (81.6%) patients, 234 (82.4%) were PIN free, 41 (14.4%) with low grade PIN and 9 (3.2%) with high grade PIN. Cancer was diagnosed in 65 patients (18.6%), 30 of whom (46.2%) had associated high grade PIN. High grade PIN was detected in 62 (76.5%) patients in the group undergoing radical prostatectomy. RESULTS: No statistically significant differences were detected among total PSA and free PSA percentage serum concentrations relative to the detection of associated PIN, regardless of its degree, in patients undergoing prostatic biopsy. Cancer detection was the single most significant contributing variable. In patients undergoing radical prostatectomy, high degree PIN did not influence significantly. The greatest contribution in this group was the pathological stage. CONCLUSIONS: PSA serum concentration and PSA percentage are not influenced by the existence of PIN. High degree PIN is strongly associated to cancer. Accordingly, repeat biopsies are warranted in any patient presenting such lesions.

Adult↗
PubMed1999

Teleradiology as a seed of the regional health care Intranet in a rural region in Spain.

Castilla y León is a rural region with a very sparse population of about 2,560,000 habitants. Special health care challenges appear due to this region's very aged population and large dimensions. A theoretical model of services of Telemedicine is proposed and an experimental teleradiology trial is carried out between a rural Health Care Centre and its Reference Hospital to make easier the planning of future projects. The total number of studies was increased due to availability of specialised support and higher skills of physicians, but the percentage of studies consulted to specialists diminished. Continuing education through physicians communication was highly improved.

Computer Communication Networks↗
PubMed1998

Design, synthesis, and biological activities of new thieno[3,2-d] pyrimidines as selective type 4 phosphodiesterase inhibitors.

A common pharmacophore for compounds structurally related to nitraquazone has been derived. Using this pharmacophore, new structures have been designed, synthesized, and evaluated for their inhibitory potencies against cyclic adenosine 5'-monophosphate (cAMP) specific phosphodiesterase (PDE 4). From these compounds, 4-benzylamino-2-butylthieno[3,2-d]pyrimidine (4) was selected for optimization. The effects of changes to the lipophilic groups and the amino linkage on the PDE 4 activity have been investigated. As a result, some potent PDE 4 inhibitors, selective with respect to PDE 3, have been identified. A selected group of compounds have been further evaluated for their ability to displace [3H]rolipram from its binding site and also to potentiate isoprenaline-induced cAMP accumulation in isolated guinea pig eosinophils. Of these, 2-butyl-4-cyclohexylaminothieno[3,2-d]pyrimidine (33) has an interesting profile, with an important improvement in PDE 4/[3H]rolipram ratio with respect to reference drugs, and good activity in cAMP potentiation, consistent with efficient cell penetration.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1998

Singlet molecular oxygen-mediated photo-oxidation of tetracyclines: kinetics, mechanism and microbiological implications.

Members of the biologically active series tetracyclines (TCs) suffer visible light-promoted photodynamic degradation to different extents, depending on their respective chemical structures and reaction conditions (solvent polarity and pH). The photo-oxidation is accompanied by a partial loss of the antimicrobial power. The photodamage is very fast in the alkaline pH range and less aggressive. although not negligible in kinetic terms, in the physiological pH region. Photo-oxidation quantum efficiencies, evaluated for eight TC derivatives, through singlet molecular oxygen [O2(1Delta(g))] phosphorescence detection, spectrophotometric and polarographic methods, range from 0.12 to 0.65 as upper limits in alkaline medium. The photo-oxidation essentially proceeds via a O2(1Delta(g)) mediated process, with rose bengal or eosine as dye-sensitizers, Nevertheless, as a minor reactive pathway,the excited triplet state of the dye sensitizers interacts with TCS in a competitive process with O2(1Delta(g) generation. The O2(1Delta(g)-mediated photo-oxidation of TCs appears to be a plausible mechanism to account for their phototransformations in biological media, in the presence of visible-absorbing pigments. In both highly and moderately polar media, the quenching of the excited oxygen species is mainly represented by a reactive interaction. It is exerted by the TC molecule through a cooperative effect from the different contributions of several nuclear and extranuclear O2(1Delta(g)-sensitive substituents, as discussed in detail in this paper. The TC lower than 0.03 in the most favourable cases. Nevertheless, the TC photoproduct, formed through direct irradiation, efficiently generates O2(1Delta(g) with Phi(Delta)=0.24. This important finding constitutes the first direct evidence of Type II sensitization by TC photoproducts, and could contribute to the elucidation of the mechanism of TC phototoxicity.

Kinetics↗
PubMed1998

Frequency of Y chromosomal material in Mexican patients with Ullrich-Turner syndrome.

Cytogenetic studies have shown that 40-60% of patients with Ullrich-Turner syndrome (UTS) are 45,X, whereas the rest have structural aberrations of the X chromosome or mosaicism with a second cell line containing a structurally normal or abnormal X or Y chromosome. However, molecular analysis has demonstrated a higher proportion of mosaicism, and studies in different populations have shown an extremely variable frequency of Y mosaicism of 0-61%. We used Southern blot analysis and polymerase chain reaction (PCR) to detect the presence of Ycen, ZFY, SRY, and Yqh in 50 Mexican patients with UTS and different karyotypes to determine the origin of marker chromosomes and the presence of Y sequences. Our results indicated the origin of the marker chromosome in 1 patient and detected the presence of Y sequences in 4 45,X patients. Taken together, we found a 12% incidence of Y sequences in individuals with UTS. The amount of Y-derived material was variable, making the correlation between phenotype and molecular data difficult. Only 1 patient had a gonadoblastoma. We discuss the presence of Y chromosomes or Y sequences in patients with UTS and compare our frequency with that previously reported.

Adolescent↗
PubMed1998

Genotoxicity of an extract of Calendula officinalis L.

A fluid extract of Calendula officinalis L. displayed genotoxic properties when assayed for mitotic segregation in the heterozygous diploid D-30 of Aspergillus nidulans. The extract of Calendula exhibited dose-dependent toxicity and genotoxicity (both mitotic crossing-over and chromosome malsegregation being observed) to Aspergillus in the range of five plate concentrations from 0.1 to 1.0 mg of solids/ml assayed. Mutagenicity testing with the Salmonella/microsome assay in strains TA 1535, TA 1537, TA 98 and TA 100 was negative in a plate incorporation protocol, with concentrations ranging from 50 to 5000 microg/plate (+/- S9). The mouse bone marrow micronucleus test, where the extract was dosed orally up to 1 g/kg for 2 days, was also negative.

Animals↗
PubMed1998

[Fragile X syndrome. Clinical analysis of 300 Chilean patients with unspecific mental retardation].

BACKGROUND: Fragile X syndrome is the most important cause of sex linked mental retardation and the second of chromosomal origin, after Down syndrome. AIM: To apply the modified Hagerman score to patients with mental retardation and to relate clinical findings with cytogenetic and molecular diagnosis. PATIENTS AND METHODS: The modified Hagerman score was applied to 214 male and 86 female patients with mental retardation. The clinical variables in non fragile X and fragile X cases, determined by molecular and cytogenetic methods, were compared. RESULTS: The score in 210 non fragile X males was 10.5 + 3.7 (range 3-23), compared to 21.4 + 2.1 (range 19 to 23) in the four fragile X patients. All fragile X patients had mental retardation, attention deficits, hyperactivity disorders, hand biting and poor visual contact. Hand biting, flapping and perserving speech were observed in a significantly higher number of fragile X males. Only one of 86 females had fragile X syndrome: Her most relevant findings were a long face and high forehead, an attention deficit, hyperactivity and poor visual contact. No clinical differences with other mentally retarded females were found. CONCLUSIONS: Approximately 5% of institutionalized males with mental retardation have a fragile X syndrome.

Adolescent↗
PubMed1998

Single dose study of the bioequivalence of two sustained-release theophylline formulations.

The relative bioavailability of theophylline (CAS 58-55-9) was evaluated after a single dose administration of two sustained-release theophylline tablet formulations: Controfilina-200 as test preparation (test) and a commonly used reference preparation (reference). The design of the study was crossover in twelve healthy volunteers, with a series of two experimental sessions. The two sessions were carried out at weekly intervals. Theophylline concentrations were measured by HPLC (high performance liquid chromatography). The bioavailability was compared using the parameters: AUC0-infinity (area under the concentration-time curve), Cmax (maximal theophylline concentration), tmax (time after drug intake at which the maximal concentration is reached) and Cmax/AUC0-infinity. The results of this study indicated that the new generic sustained-release tablet and the reference are bioequivalent when the same dosage is administered.

Adult↗
PubMed1998

[Interleukin-8 levels in gastric biopsies of children colonized by Helicobacter pylori].

BACKGROUND: Helicobacter pylori produces a gastric mucosal inflammation characterized by neutrophil infiltration, due to the liberation of interleukin-8. AIM: To measure interleukin-8 levels in gastric mucosa samples from children colonized by H. pylori. PATIENTS AND METHODS: Thirty one children that required an upper gastrointestinal endoscopy for diagnostic purpose were studied. Antral biopsies were obtained for pathological study, H. pylori detection using CLO-test and interleukin-8 determination by ELISA. RESULTS: Nine children were not infected with H. pylori. Of these, six had a pathologically normal gastric mucosa and three had a mild chronic gastritis. Twenty two children were infected by H. pylori and all had a chronic gastritis with activity signs in 13. Mucosal interleukin-8 was higher in infected than in non infected children (59.7 (range 6.1-379.7) and 15.8 (range 3.9-104.1) pg/mg respectively p = 0.029). Colonized children with an active chronic gastritis had higher interleukin-8 levels than those with inactive gastritis (84.4 (range 33.3-379.0) and 26.8 (range 6.1-372.6) pg/ml respectively p = 0.04). CONCLUSIONS: Stomach colonization by H. pylori is associated with higher mucosal levels of interleukin-8. This phenomenon probably plays a role in the genesis and intensity of gastric mucosal inflammation in children.

Adolescent↗
PubMed1998

[Clinical and molecular screening for fragile X syndrome in 300 patients with non-specific mental retardation].

BACKGROUND: Fragile X syndrome is the most frequent cause of mental retardation linked to the X chromosome. In the majority of cases, the mutation responsible for the syndrome is an expansion of the trinucleotide repeat (CGG)n, present in the 5' region of exon 1 of the gene for mental retardation associated with fragile X syndrome (FMR-1). AIM: To report the results of a fragile X screening in patients with mental retardation. PATIENTS AND METHODS: Fragile X screening using polymerase chain reaction methods was done in 386 X chromosomes from 300 patients (214 male), aged 4 to 26 years old. The modified Hagerman test was applied to male patients. Hybridization techniques were applied in a subgroup of 51 patients. RESULTS: (CGG)n 30 was the allele found with the highest frequency in 50.2% of patients. (CGG)n 29 was found in 29% of patients. One subject had an allele with 46 CGG repeats, which corresponds to the gray zone. Hybridization studies were highly concordant with PCR, detecting four males with fragile X syndrome and a carrier female. The average clinical score of mental retardation not due to fragile X syndrome was 10.3 +/- 3.4 (range 3 to 23), and 97% of males had a score below 19. The concordance between scores over 20 and molecular genotype was 98%. CONCLUSIONS: The distribution of (CGG)n repeats, observed in this study, was significantly different to that previously reported for a normal Chilean population. The dispersion of molecular status and clinical score was lower than previously described using cytogenetic techniques.

Adolescent↗
PubMed1998

[Differential features of transglottic carcinoma].

A study was made of the differential features of transglottic laryngeal carcinomas. We made a retrospective study of patients with laryngeal carcinoma diagnosed in our center from 1985 to 1996. In this period, 1212 laryngeal carcinomas were diagnosed, of which 99 (8%) were considered transglottic. In relation to factors such as sex, toxic habits, level of histological differentiation or affected nodes, patients with transglottic carcinomas had characteristics that were intermediate between patients with glottic and supraglottic carcinomas. An analysis was made of the treatments and the results obtained in patients treated with radical intention and a minimum follow-up of 3 years. The treatment most frequently used in patients with transglottic carcinoma was surgery (total laryngectomy) and complementary radiotherapy. The 5-year actuarial adjusted survival rate jor patients with transglottic carcinoma was 78%, which was intermediate between the survival rates of patients with glottic (90%) or supraglottic (69%) carcinoma.

Aged↗
PubMed1998

[Interleukin-6 and interferon-gamma release from blood mononuclear cells and colonic mucosa from patients with ulcerative colitis].

BACKGROUND: Cytokines are involved in the pathogenesis of inflammatory bowel diseases such as ulcerative colitis and Crohn disease. AIM: To measure cytokine release by mononuclear cells of patients with ulcerative colitis. PATIENTS AND METHODS: Twelve patients subjected to a diagnostic colonoscopy were studied. Six had an ulcerative colitis and six did not have inflammatory changes in the colonic mucosa and were considered as control. Mononuclear cells were isolated from biopsies of colonic mucosa and from peripheral blood cultivated during 48 hours with pokeweed mitogen, and Interleukin 6 and interferon-gamma were measured in their supernatants. RESULTS: In patients with ulcerative colitis, interleukin 6 secretion by peripheral blood mononuclear cells was higher than in control subjects in the basal period (2212 +/- 424 and 443 +/- 174 pg/ml respectively p = 0.03) and after stimulation with pokeweed mitogen (16,328 +/- 1275 and 5462 +/- 322 pg/ml respectively p = 0.03). No differences in interleukin 6 secretion by colonic mucosa mononuclear cells were observed. Unstimulated cells did not liberate interferon-gamma. The secretion of this lymphokine by stimulated colonic mucosa cells was lower in patients with ulcerative colitis than in controls (1571 +/- 216 and 7953 +/- 389 pg/ml respectively p = 0.03). CONCLUSIONS: Local and systemic changes in interleukin 6 and interferon-gamma secretion occur in patients with ulcerative colitis. These changes could be related to the development of the disease.

Adult↗
PubMed1997

[Socioeconomic determinants and utilization of emergency hospital services].

BACKGROUND: Socioeconomic level is a key determinant for health status. It may also influence on the utilization of hospital emergency services, although the factor responsible for that is not known. The main objective of the present report is to assess whether patients using frequently hospital emergency services have one or more variables related to low socioeconomic level. PATIENTS AND METHODS: A standardized questionnaire was applied to 800 patients randomly selected from those attending the emergency services of a provincial reference hospital. It was gathered information on: income, education level, employment, loneliness, domestic violence, occupational accidents, and life style. Odds ratios (OR) and their 95% confidence intervals (CI) were estimated. Stepwise logistic regression analysis was used to ascertain the independent predictors for attending for than once to the emergency services. RESULTS: In crude analysis, low income and low educational level were significantly related to the use of emergency services (both chi 2 for a trend < 0.05). Alcoholism (OR = 2.3, 95% CI = 1.2-4.7) and domestic violence (OR = 2.6, 95% CI = 0.9-8.1) were also related. Stepwise logistic regression analysis selected income (OR for intermediate level = 1.6, 95% CI = 1.0-2.7, and OR for low level = 2.3, 95% CI = 1.4-3.7) and alcoholism (OR = 2.9, 95% CI = 1.3-6.4) as independent predictors. CONCLUSIONS: Patients with low income and/or alcoholism use emergency hospital services more frequently.

Adult↗
PubMed1997

Two SRY-negative XX male brothers without genital ambiguity.

We report a Mexican family in which two sibs were identified as "classic" XX males without genital ambiguities. Molecular studies revealed that both patients were negative for several Y sequences, including SRY. A review of familial cases disclosed that this is the first family where a complete male phenotype was observed in Y-negative XX male non-twin brothers. These data suggest that an inherited loss-of-function mutation, in a gene participating in the sex-determining cascade, can induce normal male sexual differentiation in the absence of SRY.

Adult↗
PubMed1997

Effects of sporulation pH on the heat resistance and the sporulation of Bacillus cereus.

Spores of Bacillus cereus ATCC 7004, 4342 and 9818 were obtained in nutrient agar at several pH from 5.9 to 8.3. The optimum pH for sporulation was around 7, but good production of spores was obtained in the range 6.5-8.3. With all three strains, D-values clearly dropped with sporulation pH, decreasing by about 65% per pH unit. z-Values were not significantly modified (P > 0.05) by this factor. Mean z-values of 7.13 degrees C +/- 0.16 for strain 7004, 7.67 degrees C +/- 0.04 for 4342 and 8.80 degrees C +/- 0.64 for 9818 were obtained.

Bacillus cereus↗
PubMed1997

[Correlation between computed axial tomography and ileum obturating lymphadenectomy in localized adenocarcinoma of the prostate].

OBJECTIVE: To correlate the findings of CT and ileoobturator lymphadenectomy in patients with localized adenocarcinoma of the prostate. METHODS: 94 patients with adenocarcinoma of the prostate were evaluated. Ileoobturator lymphadenectomy and brachytherapy were performed in 61.1%, radical prostatectomy in 22.5% and lymphadenectomy with prostatic labeling for subsequent external radiation therapy in 5%. Lymph node CT and pathology findings were correlated. RESULTS: Of 92 patients with a normal CT scan, 18 had positive nodes and 19.1% were understaged. Two patients with a CT scan suggestive of metastatic adenopathy had negative pathology findings. Seventy-two of the 92 patients with normal CT scans had negative nodes, accounting for a specificity of 76.6%. CONCLUSION: Pelvic lymph node involvement changes the prognosis of prostate cancer. However, the ability of CT to detect lymph node metastasis is limited. It is therefore not a reliable method and raises the costs of staging unnecessarily.

Adenocarcinoma↗
PubMed1997

[Conservative treatment with chemotherapy and radiotherapy in bladder cancer invading the muscle: preliminary results of a prospective study].

OBJECTIVE: To analyze the possibility and safety of conservative treatment of muscle-invasive bladder cancer and to identify the prognostic factors for survival. METHODS: A total of 33 patients with invasive bladder cancer, clinical stages T2-4NxM0, were treated with aggressive transurethral resection (TUR) followed by three cycles of neoadjuvant methotrexate, cisplatin and vinblastine (MCV) chemotherapy and radiotherapy (60 Gy to the bladder). Cystectomy was recommended to patients without complete response to TUR and MCV chemotherapy. RESULTS: 31 of the 33 patients included in the study completed the protocol and were evaluable. The clinical complete response rate to TUR and MCV chemotherapy was 68% (21/31 Pts.). With a median follow-up of 39 months (range 12-78), 25/31 patients (81%) are alive and 24 (77%) have functioning preserved bladders. Four out of 31 patients (13%) developed distant metastases. The 5-year overall survival and disease free interval was 74.6% and 53.5%, respectively. By multivariate analysis response after TUR and chemotherapy (p = 0.022) was the more important risk factor associated with survival. CONCLUSION: These results indicate that MCV chemotherapy followed by radiotherapy may be effective in preserving bladder function in a high number of patients, with a survival rate comparable to that reported after cystectomy. The true efficacy of neoadjuvant chemotherapy remains to be proven by ongoing randomized trials.

Aged↗