PubMed Health⌕ Search

Biomedical subjects

J Ferrer

Publications and source records attributed to J Ferrer.

At least 73 records · Page 4Linked to original sources
PubMed2000

Vaginal candidosis: epidemiological and etiological factors.

A review is presented of the emerging problem of candidal colonization regarding epidemiological and etiological factors. In recent years a change in epidemiological trends has been observed. Vaginal candidosis seems to show a higher frequency to recur and a significant increase in infections caused by non albicans species of candidas has been stated. The three stage mechanisms of adhesion, blastopore germination and epithelium invasion are emphasized. There is a balance between candidal organisms and vaginal defense factors (lactobacilli, cellular and humoral immunity) controlling and limiting fungal growth. Vaginitis appears because of an increased number or an enhanced virulence of candidas. In some other patients, a decreased vaginal defense mechanism is a determinant factor. There are still a number of factors involved in clinical candidal vulvovaginitis that need to be clarified.

Candida↗
PubMed2000

2-Hydroxyacid dehydrogenase from Haloferax mediterranei, a D-isomer-specific member of the 2-hydroxyacid dehydrogenase family.

An NAD-dependent D-2-hydroxyacid dehydrogenase (EC 1.1.1.) was isolated and characterized from the halophilic Archaeon Haloferax mediterranei. The enzyme is a dimer with a molecular mass of 101.4 +/- 3.3 kDa. It is strictly NAD-dependent and exhibits its highest activity in 4 M NaCl. The enzyme is characterized by a broad substrate specificity 2-ketoisocaproate and 2-ketobutyrate being the substrates with the higher Vmax/Km. When pyruvate and 2-ketobutyrate were the substrates the optimal pH was acidic (pH 5) meanwhile for 2-ketoisocaproate maximum activity was achieved at basic pH between 7.5 and 8.5. The optimum temperature was 52 degrees C and at 65 degrees C there was a pronounced activity decrease. This new enzyme can be used for the production of D-2-hydroxycarboxylic acid.

Alcohol Oxidoreductases↗
PubMed2000

Clinical management of the patient with pleural effusion.

Pleural effusion is a frequent medical problem with a wide span of different causes. We wish to highlight the clinical management of the patient with pleural effusions but anatomic, physiologic and diagnostic management of the main pleural diseases will also be considered.

Collagen Diseases↗
PubMed2000

Structural control of polyketide formation in plant-specific polyketide synthases.

BACKGROUND: Polyketide synthases (PKSs) generate molecular diversity by utilizing different starter molecules and by controlling the final length of the polyketide. Although exploitation of this mechanistic variability has produced novel polyketides, the structural foundation of this versatility is unclear. Plant-specific PKSs are essential for the biosynthesis of anti-microbial phytoalexins, anthocyanin floral pigments, and inducers of Rhizobium nodulation genes. 2-Pyrone synthase (2-PS) and chalcone synthase (CHS) are plant-specific PKSs that share 74% amino acid sequence identity. 2-PS forms the triketide methylpyrone from an acetyl-CoA starter molecule and two malonyl-CoAs. CHS uses a p-coumaroyl-CoA starter molecule and three malonyl-CoAs to produce the tetraketide chalcone. Our goal was to elucidate the molecular basis of starter molecule selectivity and control of polyketide length in this class of PKS. RESULTS: The 2.05 A resolution crystal structure of 2-PS complexed with the reaction intermediate acetoacetyl-CoA was determined by molecular replacement. 2-PS and CHS share a common three-dimensional fold, a set of conserved catalytic residues, and similar CoA binding sites. However, the active site cavity of 2-PS is smaller than the cavity in CHS. Of the 28 residues lining the 2-PS initiation/elongation cavity, four positions vary in CHS. Point mutations at three of these positions in CHS (T197L, G256L, and S338I) altered product formation. Combining these mutations in a CHS triple mutant (T197L/G256L/S338I) yielded an enzyme that was functionally identical to 2-PS. CONCLUSIONS: Structural and functional characterization of 2-PS together with generation of a CHS mutant with an initiation/elongation cavity analogous to 2-PS demonstrates that cavity volume influences the choice of starter molecule and controls the final length of the polyketide. These results provide a structural basis for control of polyketide length in other PKSs, and suggest strategies for further increasing the scope of polyketide biosynthetic diversity.

Acyl Coenzyme A↗
PubMed2000

Lack of BLV and PTLV DNA sequences in the majority of patients with large granular lymphocyte leukaemia.

The primate T-cell lymphoma/leukaemia viruses (PTLV) and bovine leukaemia virus (BLV) comprise a unique genus of retroviruses, infection with which induces seroreactivity in the host against conserved epitopes in their p24 gag and gp21 env cognate proteins. Herein, we have confirmed this serocrossreactivity. Patients with large granular lymphocyte (LGL) leukaemia have frequent seroreactivity to the p24 and gp21 env proteins of human T-cell lymphoma/leukaemia virus I (HTLV-I), one of the species in the genus. However, only a small minority of patients are actually infected with prototypic HTLV-I or HTLV-II, another species within the group. In an attempt to determine whether LGL leukaemia might be associated with other members of the PTLV/BLV genus, we examined the peripheral blood mononuclear cell DNA of 22 HTLV p24 and/or gp21 seropositive LGL leukaemia patients via PCR using degenerate and specific primer pair/probe systems capable of detecting all known members of the PTLV/BLV genus. None of the samples was positive. These data indicate that although HTLV-II may be associated with some cases of LGL leukaemia most patients are not infected with a PTLV or BLV virus.

Autoradiography↗
PubMed2000

Comparative performances of an HTLV-I/II EIA and other serologic and PCR assays on samples from persons at risk for HTLV-II infection.

BACKGROUND: HTLV-I and HTLV-II are related exogenous pathogenic human retroviruses. Until recently, ELISAs based on HTLV-I antigens have been used to screen for the presence of HTLV-I or -II antibodies. The HTLV-I-based assays have not been as sensitive in detecting antibodies to HTLV-II as in detecting antibodies to HTLV-I. The Abbott HTLV-I/HTLV-II ELISA uses a combination of HTLV-I and HTLV-II antigens to detect antibodies to the whole HTLV group. The performance of this ELISA was compared to that of several HTLV-I-based serologic assays and an HTLV-II PCR assay in cohorts of South American Indians and New York City IV drug users (IVDUs) in whom HTLV-II is endemic. STUDY DESIGN AND METHODS: Sera from 429 South American Indians and New York City IVDUs were evaluated for HTLV antibodies by the use of three ELISAs (rgp21-enhanced HTLV-I/II, Cambridge Biotech; Vironostika HTLV-I/II, Organon Teknika; and HTLV-I/HTLV-II, Abbott), and a Western blot (WB) assay. Peripheral blood leukocyte DNA from each person was analyzed for HTLV-I and HTLV-II pol DNA via PCR. The HTLV-II PCR-positive samples were further subtyped via cloning and sequencing and/or oligomer restriction. RESULTS: Two hundred four samples (48%) were positive for HTLV-II by serologic and/or PCR assays. All of the positive samples from the Indians and approximately one-third of the positive samples from the IVDUs were of the HTLV-IIB subtype. Comparative analyses indicate that the sensitivity and specificity of the various assays were: PCR, 98 and 100 percent; Abbott HTLV-I/HTLV-II, 78 and 95 percent; Cambridge Biotech HTLV-I/II, 76 and 96 percent; Vironostika HTLV-I/II, 71 and 98 percent; and WB, 73 and 100 percent, respectively. CONCLUSION: There were no significant differences among the sensitivities and specificities of the HTLV-I/II ELISAs (p values, 0.056-0.438). The WB and PCR assays were much more specific than the other serologic assays (p</=0.03). However, the PCR assay is significantly (p<0.001) more sensitive than any of the serologic assays in the detection of HTLV-II infection. Thus, optimal detection of HTLV-II infection would seem to require both serologic and DNA PCR assays.

Enzyme-Linked Immunosorbent Assay↗
PubMed2000

Clear cell syringoid carcinoma: an ultrastructural and immunohistochemical study.

Syringoid carcinoma (syringoid "eccrine" carcinoma or eccrine epithelioma) is a rare cutaneous tumor with some controversy regarding its correct definition. It may also be difficult to differentiate from its benign counterpart (syringoma), other adnexal carcinomas, and cutaneous metastasis from adenocarcinomas. We present a case of a syringoid carcinoma of the clear cell variant complemented with an immunohistochemical and ultrastructural study, the latter revealing cytoplasmic accumulation of glycogen and presence of intercellular and intracellular lumina in clear tumor cells, as well as diverse hallmarks of malignancy (i.e., perineural invasion, tumor necrosis, and deep invasion). Clear tumor cells showed cytoplasmic and membranous immunoreactivity to epithelial membrane antigen, carcinoembryonic antigen, keratins, and S-100. Our ultrastructural and immunohistochemical results support the ductal differentiation of the glycogen-filled clear cell tumor population.

Aged↗
PubMed2000

[Renal cell carcinoma associated with renal angiomyolipoma and renal cortical adenoma].

OBJECTIVE: To report a case of renal cell carcinoma associated with renal angiomyolipoma and renal cortical adenoma and discuss the possibility of a hereditary etiology. METHODS: A 64-year-old patient with a tumor in the right kidney underwent right renal nephrectomy. The pathological findings revealed a clear cell renal carcinoma, two cortical angiomyolipoma and a renal cortical adenoma. The literature on these three coincident renal tumors is reviewed. RESULTS: The association of these three renal tumors is rare and is usually seen in patients with tuberous sclerosis. CONCLUSIONS: Renal angiomyolipoma is a benign tumor frequently associated with Bourneville's disease or tuberous sclerosis, a disorder of autosomal dominant transmission. Familial evidence of renal cell carcinoma has been previously reported, as in von Hippel-Lindau disease. It has been suggested that heredity may play an important role in the association of renal cell carcinoma and other renal tumors.

Adrenal Cortex Neoplasms↗
PubMed1999

Diagnostic utility of CYFRA 21-1, carcinoembryonic antigen, CA 125, neuron specific enolase, and squamous cell antigen level determinations in the serum and pleural fluid of patients with pleural effusions.

BACKGROUND: To the authors' knowledge the role of tumor marker determination in the differential diagnosis of pleural effusions has not been established definitively. The current article reports the results of a study of CYFRA 21-1, carcinoembryonic antigen (CEA), cancer antigen 125 (CA 125), squamous cell antigen (SCC), and neuron specific enolase (NSE) in the serum and pleural fluid of patients with pleural effusions of diverse etiologies. METHODS: One hundred forty-six patients with pleural effusions (43 malignant, 47 tuberculous, 32 miscellaneous benign, and 24 paramalignant) were studied prospectively. Levels of CYFRA 21-1, CA 125, CEA, NSE, and SCC were measured by radioimmunoassay in the pleural fluid in all patients and in the serum in 118 patients. RESULTS: There were no significant differences between the serum and pleural fluid levels of tumor markers with the exception of CA 125, which was higher in the pleural fluid. With maximum specificity, the highest sensitivity in the diagnosis of pleural malignancy was obtained with a combination of CYFRA 21-1 (with a cutoff value of 150 U/L), CEA (with a cutoff value of 40 ng/mL), and CA 125 (with a cutoff value of 1000 ng/mL) in pleural fluid. NSE and SCC added no diagnostic value. The simultaneous use of tumor markers and cytology in pleural fluid increased the sensitivity from 55.8% to 81%. CONCLUSIONS: These findings suggest that a combination of CYFRA 21-1, CEA, and CA 125 in the pleural fluid can be a useful addition to pleural cytology in the diagnosis of malignant pleural effusion.

Adult↗
PubMed1999

[Respiratory pasteurellosis. Description of a first series in Spain].

OBJECTIVE: To know the clinical and microbiological characteristics of a first series of 8 patients in whom Pasteurella multocida was detected in samples from low respiratory airways. PATIENTS AND METHODS: Patients with respiratory disease who had positive cultures for P. multocida in several biologic samples between 1986 and 1998 were studied. Patient's data were obtained from clinical files; microbiological study included microscopic examination, qualitative culture in all samples and quantitative culture in low respiratory airway samples. RESULTS: P. multocida was detected in 7 males and one female, with a mean age of 63 years (range: 6-71). All but one had a previous bronchial disease: 5 had chronic obstructive bronchial disease, 2 had bronchiectasis and one had relapsing acute bronchitis. Three patients referred a previous contact with pets. The main diagnosis, at the time P. multocida was detected, was exacerbated bronchitis in 4 patients, pneumonia in 2 (one with sepsis and positive blood culture to P. multocida) and another one with empyema. In the only paediatric patient P. multocida was a casual finding. Two patients died, both having a severe immunosuppression. The percentage of P. multocida detection compared to all low respiratory airway isolates along the study period was 0.02%. All samples were purulent and more than 10(7) P. multocida colony-forming units/millilitre were detected. All strains were penicillin-sensitive. CONCLUSIONS: Pasteurella multocida respiratory infection is rare, although it is probably underestimated owing to the fact that it is difficult to identify when coexisting with oropharingeal flora. Characteristically, in affects old males with bronchial disease are involved and can be life threatening in severely immunosuppressed patients.

Aged↗
PubMed1999

CHOP/GADD153 and methionyl-tRNA synthetase (MetRS) genes overlap in a conserved region that controls mRNA stability.

The transcription factor CHOP is involved in the regulation of the cell division cycle and the control of programmed cell death in response to cellular stress. CHOP expression has been linked with several forms of cancer. A reciprocal translocation between the CHOP and TLS RNA-binding protein gene results in myxoid liposarcoma and amplifications of the CHOP gene are associated with solid tumors including several types of sarcomas. Here we report the mapping of the methionyl tRNA synthetase (MetRS) gene to the identical 12q13 locus where the CHOP gene had previously been mapped. PCR analysis demonstrates a tail-to-tail overlap of both genes over a 55-bp region. As a result the two mRNAs share a 3' UTR complementary sequence allowing an in vivo interaction between the two mRNAs. An AU-rich regulatory element (ARE) known to control mRNA stability resides in the overlapping sequence. To test for functional significance of the ARE a luciferase reporter plasmid containing the 3'UTR of CHOP was constructed. Transfection experiments in NIH-3T3 cells show that CHOP 3'UTR confers a significantly lower activity than a control reporter or a reporter in which the region overlapping the MetRS mRNA is deleted. The conservation of this overlapping of the CHOP and MetRS genes and the role of their complementary sequence in the control of mRNA stability suggest the existence of a functional link between the expression of these two genes.

3' Untranslated Regions↗
PubMed1999

Characterization of the mouse sulfonylurea receptor 1 promoter and its regulation.

The ATP-sensitive potassium channels (K+ATP channels) are heteromultimeric structures formed by a member of the sulfonylurea receptor (SUR) family and a member of the inwardly rectifying potassium channel family (Kir6.x). The K+ATP channels play an essential role in nutrient-induced insulin secretion from the pancreatic beta-cell. We have cloned and characterized the promoter region of the mouse SUR1 gene, and have shown that it lacks CAAT and TATA boxes or an initiator element. Studies of transcription initiation in several tissues showed that there is a common SUR1 promoter in brain, heart, and pancreas and in the pancreatic beta-cell line, betaTC3. The SUR1 gene uses multiple transcription start sites with the major site located 54 base pairs 5'-upstream of the translation initiation site. Transient transfection experiments in pancreatic beta-cell lines showed that the proximal promoter fragment -84/+54 is sufficient for significant transcriptional activity. The proximal promoter region contains multiple SP1-binding sites, and cotransfection experiments of the SUR1 promoter-luciferase vector with SP1 expression vector in Drosophila SL2 cells demonstrated a stimulatory effect of SP1 on SUR1 transcriptional activity. The mobility shift assays confirmed the interaction of the SP1 transcription factor with the proximal promoter region of the SUR1 gene. Together, these results indicate that SP1 may mediate transcription initiation of the SUR1 gene. In addition, we have described the coordinate regulation of the gene expression of both K+ATP channel subunits by glucocorticoids. SUR1 and Kir6.2 mRNA levels are down-regulated by approximately 40-50% in response to glucocorticoid treatment. Interestingly, the extent of the inhibitory effect as well as the kinetics and sensitivity are very similar for both mRNAs. Studies of mRNA turnover demonstrate that glucocorticoids most likely decrease the transcriptional activity of both SUR1 and Kir6.2 genes since glucocorticoids failed to affect the stability of each mRNA. Likewise, the reduction in mRNA levels was correlated with a decrease in SUR1 and Kir6.2 protein levels.

ATP-Binding Cassette Transporters↗
PubMed1999

Amino acid residues involved in the catalytic mechanism of NAD-dependent glutamate dehydrogenase from Halobacterium salinarum.

The pH dependence of kinetic parameters for a competitive inhibitor (glutarate) was determined in order to obtain information on the chemical mechanism for NAD-dependent glutamate dehydrogenase from Halobacterium salinarum. The maximum velocity is pH dependent, decreasing at low pHs giving a pK value of 7.19+/-0.13, while the V/K for l-glutamate at 30 degrees C decreases at low and high pHs, yielding pK values of 7.9+/-0.2 and 9.8+/-0.2, respectively. The glutarate pKis profile decreases at high pHs, yielding a pK of 9. 59+/-0.09 at 30 degrees C. The values of ionization heat calculated from the change in pK with temperature are: 1.19 x 10(4), 5.7 x 10(3), 7 x 10(3), 6.6 x 10(3) cal mol-1, for the residues involved. All these data suggest that the groups required for catalysis and/or binding are lysine, histidine and tyrosine. The enzyme shows a time-dependent loss in glutamate oxidation activity when incubated with diethyl pyrocarbonate (DEPC). Inactivation follows pseudo-first-order kinetics with a second-order rate constant of 53 M-1min-1. The pKa of the titratable group was pK1=6.6+/-0.6. Inactivation with ethyl acetimidate also shows pseudo-first-order kinetics as well as inactivation with TNM yielding second-order constants of 1.2 M-1min-1 and 2.8 M-1min-1, and pKas of 8.36 and 9.0, respectively. The proposed mechanism involves hydrogen binding of each of the two carboxylic groups to tyrosyl residues; histidine interacts with one of the N-hydrogens of the l-glutamate amino group. We also corroborate the presence of a conservative lysine that has a remarkable ability to coordinate a water molecule that would act as general base.

Amino Acids↗
PubMed1999

Hepatoid adenocarcinoma of the urinary bladder. An unusual neoplasm.

A new case of hepatoid adenocarcinoma was diagnosed in fragments obtained at transurethral resection (TUR) from a 71-year-old man who had complained of haematuria. The tumour was composed of trabeculae and small solid nests of polygonal atypical cells simulating hepatocarcinoma, together with glandular areas of an otherwise typical adenocarcinoma. Immunohistochemistry showed cytoplasmic reactivity to AFP, AAT, albumin and CAM 5.2. Membrane reactivity was seen in EMA immunostaining, and there was also positivity to polyclonal CEA following a canalicular pattern. Immunoperoxidase studies of hepatocyte growth factor (HGF) and its receptor, c-met, were positive. Their expression may be related to the aggressive behaviour of this tumour.

Adenocarcinoma↗
PubMed1999

Expression of neurotrophins and their receptors in human bone marrow.

The expression of neurotrophins and their receptors, the low-affinity nerve growth factor receptor (p75LNGFR) and the Trk receptors (TrkA, TrkB, and TrkC), was investigated in human bone marrow from 16 weeks fetal age to adulthood. Using reverse transcription-polymerase chain reaction, all transcripts encoding for catalytic and truncated human TrkB or TrkC receptors were detected together with trkAI transcripts, whereas trkAII transcripts were found only in control nerve tissues. Transcripts for the homologue of the rat truncated TrkC(ic113) receptor were identified for the first time in human tissue. Stromal adventitial reticular cells were found immunoreactive for all neutrophin receptors. In contrast, hematopoietic cell types were not immunoreactive for p75LNGFR but showed immunoreactivity for one or several Trk receptors. TrkA immunoreactivity was found in immature erythroblasts. Catalytic TrkB immunoreactivity was observed in eosinophilic metamyelocytes and polymorphonuclear cells. Truncated TrkB immunoreactivity was found in erythroblasts and megacaryocytes. Immunoreactivity for both catalytic and truncated TrkC receptor was observed in promyelocytes, myelocytes, some polymorphonuclear cells and megacaryocytes. Neutrophin transcript levels appeared higher at fetal than at adult stages, no variation in Trk family transcript levels was observed. The local expression of neurotrophin genes suggests a wide range of paracrine and/or autocrine mode of action through their corresponding receptors within the bone marrow.

Adult↗
PubMed1999

Nonlinear control of an activated sludge aeration process: use of fuzzy techniques for tuning PID controllers.

In this paper, several tuning algorithms, specifically ITAE, IMC and Cohen and Coon, were applied in order to tune an activated sludge aeration PID controller. Performance results of these controllers were compared by simulation with those obtained by using a nonlinear fuzzy PID controller. In order to design this controller, a trial and error procedure was used to determine, as a function of error at current time and at a previous time, sets of parameters (including controller gain, integral time and derivative time) which achieve satisfactory response of a PID controller actuating over the aeration process. Once these sets of data were obtained, neural networks were used to obtain fuzzy membership functions and fuzzy rules of the fuzzy PID controller.

Algorithms↗