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Biomedical subjects

A Romero

Publications and source records attributed to A Romero.

At least 163 records · Page 9Linked to original sources
PubMed1991

Initiation of translation at AUC, AUA and AUU codons in Escherichia coli.

A truncated form of the HBL murein hydrolase, encoded by the temperate bacteriophage HB-3, was cloned in a pUC-derivative and translated in Escherichia coli using AUC as start codon, as confirmed by biochemical, immunological, and N-terminal analyses. Using site-directed mutagenesis, we have changed this AUC codon into AUA, AUU and AUG codons. The relative translation efficiencies for these triplets were about 5% for AUC and AUU and 7.5% for AUA compared to that of AUG codon. In the same gene arrangement E. coli beta-galactosidase was also translated at moderate efficiency using AUC as initiator.

Amino Acid Sequence↗
PubMed1991

Presenting features and prognosis of chronic lymphocytic leukemia in younger adults.

We have analyzed 117 younger patients with chronic lymphocytic leukemia (CLL) (mean age, 44.5 years; SD, 4.8; range, 19 to 49; male/female ratio, 2.08) with three main objectives: (1) to see whether these patients have distinctive presenting clinical features; (2) to investigate the impact of the disease on survival; and (3) to analyze whether already well-known prognostic factors are also useful when applied to these patients. As compared with an older age population (greater than or equal to 50 years), there were no major differences in presenting features except for an increased proportion of males (2.08 v 1.21; P less than .025) and a higher hemoglobin level (13.47 +/- 2.70 g/dL v 12.84 +/- 2.77 g/dL; P less than .05) in the younger group. Median survival is 12.3 years (expected median from a control group, 31.2 years). Clinical stages, bone marrow patterns, blood lymphocyte counts, and its doubling time are all useful to separate different risk groups of patients. Whereas patients with favorable prognostic factors have a survival probability of about 80% 14 years after diagnosis, those with poor prognostic features have a median survival of less than 3 years. It is concluded that CLL in younger adults has no major distinctive presenting features and that known prognostic factors are useful to separate different risk groups of patients. These results should be of help in planning therapy for younger persons with CLL.

Adult↗
PubMed1991

Characterization of voltage-gated and calcium-activated potassium currents in toadfish saccular hair cells.

Patch clamp methods were used to study calcium activated (IKCa) and voltage-gated (IK) potassium currents in enzymatically disassociated hair cells from the saccule of the toadfish Opsanus tau. In one population of hair cells, tetraethylammonium bromide (TEA) blocked all outward current, leaving only an inward calcium current (ICa). This current blocked by TEA was also blocked by barium (5 mM) and cadmium (0.2 mM) but only partially blocked by zero external calcium. In the majority of the cells, after TEA (25 mM) was used to block IKCa, a second outward current remained. This current was resistant to block by apamin, barium (5 mM) and cadmium (0.2 mM). Its kinetics of activation and deactivation were considerably slower than those of IKCa. Because of the current/voltage characteristics, its resistance to block by the above agents and voltage-gated activation, this current was termed IK. Study of the rates of activation and deactivation of the two currents in hair cells exhibiting either fast or slow total outward current activation showed that these two kinetic parameters were linked in a cell, i.e., cells with fast IKCa kinetics exhibit faster IKCa kinetics than cells with slower IKCa kinetics. Cell attached and inside out recordings showed a high conductance channel with short open times and a lower conductance channel with longer open times active over the same voltage ranges as those seen in whole cell recordings. Since these two currents with quite different but linked kinetics are active over the same voltage range, their co-existence may be of some importance to sensory coding in the hair cells.

4-Aminopyridine↗
PubMed1991

Cell proliferation and tumour promotion by ethinyl estradiol in rat hepatocarcinogenesis.

A two-stage model of hepatocarcinogenesis is used to study the effect of exposure time to ethinyl estradiol (EE) on promotion of preneoplastic lesions in rat liver induced by diethylnitrosamine (DEN). Young male and female Sprague-Dawley rats initiated by a single dose of DEN (100 mg/kg) were subjected to different times of EE administration incorporated into the diet at 10 p.p.m. (0.5 mg/kg x day). Animals were killed 1 year after initiation. Whereas macroscopic tumours were rarely seen in animals with short exposure (3 or 4 months) or in only-initiated controls, all the animals under a long period of administration (8 months) showed macroscopic tumours. Morphometric studies on glutathione-S-transferase (GST) positive preneoplastic lesions revealed an increase in the mean size of foci and nodules corresponding to 8 months of treatment, whereas no changes were observed between animals with short exposure and only-initiated controls. No differences were seen in the incidence of these lesions between any of the protocols. In addition to an acute hyperplastic effect on non-initiated liver described earlier, our preliminary results suggest cytotoxicity and an enhancement of the liver cell turnover after several months of continuous EE administration. These results taken together suggest that promotion of hepatocarcinogenesis by EE largely depends on the time of exposure to the compound and that chronic effects on the liver cell turnover may play an important role in its ability to promote hepatocarcinogenesis.

Animals↗
PubMed1991

Circadian variations in the superoxide production, enzyme release and neutrophil aggregation in patients with rheumatoid arthritis and controls.

Patients with rheumatoid arthritis (RA) experience fluctuations of symptoms throughout the day. These could be due to mechanical changes or modification of the inflammatory mechanisms. In the present paper we studied fluctuations of superoxide production (O2), enzyme release (beta-glucuronidase and lysozyme) and neutrophil aggregation in the peripheral blood of eight healthy volunteers and eight patients with RA. Although enzyme release was greater in patients with RA, no significant difference was found throughout the day, neither in control nor in patients. Similar results were obtained when studying neutrophil aggregation. On the contrary, the superoxide production, determined at 8:00, 14:00, and 20:00 h, was 6.3 +/- 0.5, 4.40 +/- 0.4 and 6.26 +/- 0.3, respectively, in patients with RA and 6.65 +/- 0.7, 4.7 +/- 0.7 and 7.27 +/- 0.4 in the controls. The values obtained at 14:00 h were significantly lower (alpha = 0.01). There were no differences in the curve form between patients and controls.

Arthritis, Rheumatoid↗
PubMed1991

Assessment of anomalous systemic and pulmonary venous connections by transoesophageal echocardiography in infants and children.

OBJECTIVE: To assess the value of transoesophageal echocardiography in the preoperative definition of systemic and pulmonary venous connections. DESIGN: Transoesophageal echocardiographic studies were performed prospectively under general anaesthesia in 76 consecutive unoperated children. Results were compared with those obtained by earlier transthoracic ultrasound studies (n = 76), cardiac catheterisation (n = 62), and subsequent surgical inspection (n = 58). SETTING: Two tertiary referral centres. PATIENTS: 76 unoperated infants and children (age 0.2-14.8 years, mean age 4.1 years) with congenital heart disease. MAIN OUTCOME MEASURE: Identification of anomalous systemic and pulmonary venous connections. RESULTS: Transoesophageal studies showed anomalous venous connections in 14 patients. Two had both anomalous systemic and pulmonary venous connections. Transoesophageal studies showed 12 anomalous systemic venous connections in nine patients. In eight patients these were confirmed at operation or catheterisation: one patient is awaiting operation. Six anomalous systemic venous connections were missed during earlier transthoracic studies. Anomalous pulmonary venous connections (one mixed total, six partial) were shown in seven patients. These were confirmed at operation in six and by cardiac catheterisation in one. Four of these patients were missed during earlier transthoracic ultrasound studies. No patient defined as having normal venous connections by the transoesophageal study was subsequently shown to have anomalous venous connections at operation or angiography. CONCLUSIONS: Transoesophageal echocardiography is a highly sensitive tool for the preoperative definition of systemic and pulmonary venous connections. In this series it was better than transthoracic ultrasound and complemented cardiac catheterisation and angiocardiography.

Adolescent↗
PubMed1991

[A comparison between three questionnaires and laboratory tests for the detection of alcoholism in general practice].

By means of a case/control study, an attempt was made to identify the different questionnaires and biological tests which might be used in the General Practice consulting room for the detection of alcoholic patients. A comparison was made between the CABE, MALT, and Skinner questionnaires, and the MCV, AST, ALT, GGT triglyceride, cholesterol, uric acid, bilirubin and glycemia biological tests. Sensitivity, specificity, predictive value and diagnostic efficiency were studied in a group of 37 confirmed alcoholics and 25 controls making up a population with a high prevalence of alcoholism. Later we analysed the changes which affect the values of the different tests when applied to a population with a low prevalence of alcoholism, in other words, the utility of the tests in general practice was evaluated. The study concludes that the diagnostic performance of the questionnaires together with case history is higher than that of biological tests in general practice, and that the routine application tests in general practice, and that the routine application of the CAGE questionnaire and to a lesser extent of the Skinner questionnaire make it possible to identify those patients suspected of alcoholism and to improve the predictive value of the biological tests applied thereafter. Nevertheless further study is necessary to confirm the diagnostic effectiveness of these questionnaires in the general population of health centre patients.

Adult↗
PubMed1991

Advanced colorectal carcinoma. A prospective randomized trial of sequential methotrexate, 5-fluorouracil, and leucovorin versus 5-fluorouracil alone.

One hundred and twenty-five previously untreated patients bearing metastatic or advanced recurrent (inoperable) colorectal carcinoma and measurable disease were prospectively randomized. Those in arm A received 5-fluorouracil (5-FU), 1,200 mg/m2 i.v. infusion over 2 h, while those in arm B received methotrexate (MTX), 200 mg/m2 i.v. (push injection), followed 20 h later by 5-FU, 1,200 mg/m2 i.v. infusion over 2 h, plus calcium leucovorin (LV), 25 mg i.m. every 6 h for eight doses beginning 24 h after MTX administration. Cycles were repeated every 15 days. All patients receiving treatment were evaluable for toxicity and survival, and 118 patients were evaluable for response. The objective regression rate (complete plus partial response) was 12% (7 of 58) in arm A and 28% (17 of 60) in arm B (p = 0.049). No change was observed in 24% (14 of 58) in arm A and in 35% (21 of 60) in arm B (p = 0.28), while progressive disease was registered in 64% (37 of 58) and 37% (22 of 60) in arms A and B, respectively (p = 0.006). Median duration of response was 3 months in arm A and 5 months in arm B (p = 0.39). The median survival was 8.3 months in arm A and 11.2 months in arm B (p = 0.25). No statistically significant differences were found when objective regression and survival were related to site of primary tumor, performance status, and number of involved organs. There were two drug-related deaths in arm B due to severe myelosuppression followed by mucositis and sepsis. Of nonhematologic toxicities, diarrhea was more frequently observed in arm B, as were mucositis and infectious complications. Our results indicate that the sequential schedule MTX-5-FU-LV with 20-h intervals between MTX and 5-FU is superior in terms of objective regression to 5-FU alone given at the dose and schedule used in the present study. However, MTX-5-FU-LV did not have a significant impact on survival.

Adult↗
PubMed1990

Phase II trial of cytarabine, cisplatin and vindesine for advanced non-small cell lung cancer.

Thirty-two patients with advanced non-small cell lung cancer (NSCLC) were entered in this study to evaluate the efficacy and toxicity of a chemotherapy schedule including cisplatin (C) 40 mg/m2 intravenously (i.v.) on days 1-3; vindesine (V) 3 mg/m2 i.v. on day 1, and cytarabine (ara-C) 15 mg/m2 subcutaneously every 12 hours on days 1-3 (total dose: 90 mg/m2). Cisplatin was administered simultaneously with one dose of ara-C. Cycles were repeated every 28 days. Five patients out of 28 (18%) fully evaluable for response presented partial remissions. No complete response was observed. Median survival was 8 months and median duration of response was 4 months. Hematologic toxicity was severe in 3 patients. There were no toxicity-related deaths. Other adverse reactions included nausea and vomiting, alopecia and peripheral neuropathy. We conclude that this chemotherapy combination is marginally effective against NSCLC showing in this group of patients a low number of responses of short duration without a significant impact on survival.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

The assessment of juxtaposed atrial appendages by transoesophageal echocardiography.

As part of a prospective study into the diagnostic role of transoesophageal echocardiography in children with complex congenital heart disease, the atrial morphology was assessed in 62 children. Using the direct visualization of atrial appendage morphology, 58 were shown to have usual atrial arrangement, two were documented to have isomerism of the right and two isomerism of the left appendages. Of those with usual arrangement, four children were demonstrated to have left juxtaposition of the atrial appendages. Only two of these patients were identified during praecordial echocardiographic re-evaluation, and three on angiocardiographic examination. Surgical confirmation was obtained in three, and juxtaposition was excluded in the remaining cases. The transoesophageal cross-sectional imaging features of left juxtaposition of the atrial appendages are unique and readily diagnostic of this entity. They include, first, a lateral deviation of the acid-portion of the atrial septum and, second, a frontal orientation of the antero-superior portion forming the floor and the posterior wall of the junction of the right-sided atrial appendage with the venous component of the atrial cavity. The knowledge of these morphologic characteristics is important, as, otherwise, this malformation may be misinterpreted as representing an atrial septal defect. The results suggest that transoesophageal echocardiography will be the most sensitive preoperative diagnostic technique in detecting or excluding juxtaposed atrial appendages.

Adolescent↗
PubMed1990

Toadfish saccular hair cell bundle has a preferred orientation in the otolithic membrane.

The macula of the saccule of the toadfish, Opsanus tau, is covered by an otolithic membrane containing sockets into which the stereocilia and kinocilia of the hair cells project. We have found that the hair cell bundle has a distinct eccentric orientation within this space of the otolithic socket. Although the sockets of the otolithic membrane are irregular in shape, all kinocilia are located closet to the same border of the sockets. Since the socket is a fluid or gel filled space through which the hair cell bundle moves, this orientation may have some significance for transduction since it leaves a larger space in the on direction for stereociliary movement.

Animals↗
PubMed1990

Bone-only versus visceral-only metastatic pattern in breast cancer: analysis of 150 patients. A GOCS study. Grupo Oncológico Cooperativo del Sur.

The medical records of 510 patients with metastatic breast cancer were retrospectively reviewed. Seventy-seven patients with metastases confined to skeleton and 73 patients bearing visceral-only disease were identified. All patients had a disease-free interval greater than or equal to 6 months and received systemic therapy with any of the following modalities: chemotherapy, hormonotherapy, or chemohormonotherapy. The clinical features, response to treatment, and survival were analyzed and compared for both groups. Median survival of patients with osseous metastases was 28 months, while it was 13 months for those patients with a visceral pattern (p less than 0.001). Response rates to first and second line systemic therapy for both metastatic patterns showed no significant differences, suggesting a similar degree of sensitivity or resistance in both groups. Objective regression to first therapy was 45% in the group with bony disease and 41% among patients with visceral involvement; median duration of response was 16 months and 13 months, respectively. In both groups progressive disease conserved the original metastatic pattern in most patients. We conclude that although a superiority in survival was evident for the osseous metastatic pattern, for these patients efforts should be made to select the least aggressive therapy in order to avoid excessive toxicity. Further studies are needed to confirm our findings.

Adenocarcinoma↗
PubMed1990

Sequence of the Streptococcus pneumoniae bacteriophage HB-3 amidase reveals high homology with the major host autolysin.

We have sequenced a DNA fragment containing the pneumococcal bacteriophage HB-3 hbl gene, which codes for the phage lytic amidase. A remarkable nucleotide similarity (87.1%) between the lytA gene, coding for the pneumococcal amidase, the major autolysin of Streptococcus pneumoniae, and the hbl gene was found. This similarity completely disappeared outside the open reading frames coding for both amidases. The hbl gene transformed amidase-deficient strains of S. pneumoniae to the wild-type phenotype, and Southern blotting experiments provided evidence for recombination between donor and recipient genes. A comprehensive evaluation of these and previous results on the peptidoglycan hydrolases of S. pneumoniae and its bacteriophages suggested that recombination mechanisms participate in the evolution of the genes coding for these enzymes.

Amidohydrolases↗
PubMed1990

Characterization of the pneumococcal bacteriophage HB-3 amidase: cloning and expression in Escherichia coli.

HB-3, a temperate bacteriophage of Streptococcus pneumoniae, synthesizes its own murein hydrolase activity when multiplying on cultures of pneumococcus. The enzyme (HBL) was purified and biochemically characterized as an N-acetylmuramoyl-L-alanine amidase of 36,000 daltons, and a 2.1-kilobase DraI fragment containing the lysin gene (hbl) was cloned and expressed in Escherichia coli. Our results demonstrated that the primary product of the hbl gene is a form with low enzyme activity that can be converted to a more active form under conditions similar to those previously described for the major pneumococcal autolysin (E. García, J.L. García, C. Ronda, P. García, and R. López, Mol. Gen. Genet. 201:225-230, 1985). The phage-encoded amidase requires the presence of choline in the teichoic acids of the pneumococcal cell walls for in vivo and in vitro activity. Comparative biochemical and immunological tests of the phage-encoded and host amidases revealed a remarkable similarity between these enzymes, although analyses of their N-terminal amino acid sequences allowed us to conclude that the amidases are similar but not identical. This appears to be the first description of the cloning of a phage-encoded amidase in gram-positive bacteria.

Amidohydrolases↗
PubMed1990

Temperate bacteriophages of Streptococcus pneumoniae that contain protein covalently linked to the 5' ends of their DNA.

We have characterized three temperate bacteriophages of pneumococcus (HB-3, HB-623, and HB-746). Although all the phages belong to the same family, the polypeptide composition of the virions and the DNA restriction endonuclease analysis of their DNAs revealed differences among the three phages. The genomes of these bacteriophages have been isolated as DNA-protein complexes. The protein is specifically associated with the two 5' termini of the DNA as shown by experiments carried out with exonucleases. The protein bound to the DNA in the three phages studied, iodinated in vitro with 125I, has a molecular weight of 23,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Treatment of the complexes with chaotropic agents suggested that the protein is covalently bound to the 5' termini of the DNA. Comparative pulsed-field gel electrophoresis analysis and Southern hybridization of the SmaI restriction fragments of DNAs from one lysogenic bacteria and its parental strain revealed that the prophage genome was integrated in the host chromosome.

Bacteriophages↗
PubMed1990

The amputation level: noninvasive methods and clinical criteria.

Before undergoing amputation of a lower limb, one hundred and forty-six patients suffering from arteriosclerosis were studied with the purpose of finding prognostic indicators of success at the most distal level. The best results were obtained when skin perfusion pressure was above 60 mmHg in diabetics and above 40 mmHg in non-diabetics. Lower limb systolic blood pressure and skin thermometry also proved to be useful. The method proposed might be helpful to the surgeon in choosing the best treatment for the patient. It is a nonivasive procedure which can be easily performed and does not require sophisticated or expensive equipment.

Amputation, Surgical↗
PubMed1990

[Hemoglobin Setif (alpha 94 (G1) Asp----Tyr) in a Spanish family].

A family was studied who carried a slow mobility haemoglobin on cellulose acetate electrophoresis at pH 8.6. The structural analysis of the anomalous globin chain showed substitution of residual aspartic acid in position 94 of the alpha chain by tyrosine (Hb Setif). This mutation induces low oxygen affinity in the haemoglobin molecule plus instability of the tetramer in the oxy conformation. Such haemoglobin has been found in North-African populations, and the case presented here is the first one reported in Spain.

Africa, Northern↗