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Biomedical subjects

F Ramos

Publications and source records attributed to F Ramos.

At least 91 records · Page 5Linked to original sources
PubMed1995

[Selection and maintenance of lung donors].

Lung transplantation is a relatively modern procedure that can afford improvement in quality of life to certain terminal patients with irreversible respiratory failure. Selection of the donor and the recipient must be both strict and flexible, as we apply criteria that are constantly being revised and extended. The care afforded the donor must include certain elements: exhaustive monitorization that serves to guide the intravenous replacement of fluids and maintenance of hemodynamic stability; assisted ventilation with PEEP, FiO2 under 0.4 and adequate flow volumes; prevention and treatment of neurogenic pulmonary edema; and prevention of infections through careful airways management involving appropriate antibiotic prophylaxis. The same protocol must be maintained while the organ is being extracted and the organ itself must be properly preserved until implanted. The anesthesiologist is fully involved in optimum management of the lung donor. We consider that such care is essential for achieving more and better quality lung donations.

Female↗
PubMed1994

Repression of the genes for lysine biosynthesis in Saccharomyces cerevisiae is caused by limitation of Lys14-dependent transcriptional activation.

The product of the LYS14 gene of Saccharomyces cerevisiae activates the transcription of at least four genes involved in lysine biosynthesis. Physiological and genetic studies indicate that this activation is dependent on the inducer alpha-aminoadipate semialdehyde, an intermediate of the pathway. The gene LYS14 was sequenced and, from its nucleotide sequence, predicted to encode a 790-amino-acid protein carrying a cysteine-rich DNA-binding motif of the Zn(II)2Cys6 type in its N-terminal portion. Deletion of this N-terminal portion including the cysteine-rich domain resulted in the loss of LYS14 function. To test the function of Lys14 as a transcriptional activator, this protein without its DNA-binding motif was fused to the DNA-binding domain of the Escherichia coli LexA protein. The resulting LexA-Lys14 hybrid protein was capable of activating transcription from a promoter containing a lexA operator, thus confirming the transcriptional activation function of Lys14. Furthermore, evidence that this function, which is dependent on the presence of alpha-aminoadipate semialdehyde, is antagonized by lysine was obtained. Such findings suggest that activation by alpha-aminoadipate semialdehyde and the apparent repression by lysine are related mechanisms. Lysine possibly acts by limiting the supply of the coinducer, alpha-aminoadipate semialdehyde.

2-Aminoadipic Acid↗
PubMed1994

[Analysis of antihypertensive effectiveness by means of ambulatory blood pressure monitoring. Usefulness of the Discrete Fourier Transform Model].

In order to assess the usefulness of the Discrete Fourier Transform Model (DFT) to evaluate time-course drug effects on hypertensive patients studied with Ambulatory Blood Pressure Monitoring (ABPM) a number of experiments were carried out. A total of 10 mild to moderate hypertensive patients were evaluated under placebo and after 8 weeks of active treatment with Enalapril 20 mg per day using ABPM. Systolic and Diastolic blood pressure (SBP and DBP) were registered every 15 minutes during daytime and every 30 minutes at night. Pressure profiles of each patient were initially smoothed by hourly means. DFT was then applied to these profiles. The minimum number of harmonics necessary to generate a statistically significant fitting of the blood pressure profile, were obtained by residuals analysis (run test and analysis of variance of the mean sum of residual squares with each new harmonic incorporated to the model). A profile of the blood pressure differences (treatment-placebo) with the rough data of each patient was smoothed by hourly means. DFT was applied again on these substraction profiles. To estimate peak and trough drug effects for the blood pressure decrease function, maximum, minimum and inflexion points were calculated defining the following parameters: T peak: time from drug administration to maximum pressure decrease; T late response: time from drug administration to the inflexion point following the last minimum previous to the next dose; BP peak: the maximum blood pressure decrease amplitude; and the slope BP peak/T peak. The stability of the individual circadian rhythm was confirmed for both ABPM controls comparing times of maximum and minimum on the DFT smoothed profiles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Entamoeba histolytica: antibody response to recent and past invasive events.

Sero-epidemiological data from endemic amoebiasis areas are difficult to evaluate because the serology of individuals affected by an active process of Entamoeba histolytica tissue invasion is, at present, almost impossible to distinguish from that of individuals who have had an invasive event in the past. The present study compares serum antigenic recognition frequencies among three groups of individuals with different infective conditions: amoebic liver abscess patients; asymptomatic cyst passers; and individuals who have had amoebic liver abscess from one to three years before the study. Control groups consisted of Mexican and Canadian healthy adults. Western blots of E. histolytica membrane extract antigen were reacted with sera from the studied individuals, recognition frequency values were calculated and immunoplots of frequency differences were constructed. The results obtained suggest that the identification and purification of antigenic fractions, which are frequently recognized by sera of amoebic liver abscess patients (136, 132, 93, 70 and 62 kDa), or preferentially associated with past invasive events (144, 140 and 49 kDa), or related to the E. histolytica cyst passer condition (62 and 136 kDa), are important improvements in the use of serology for diagnosis and epidemiological studies in endemic areas of amoebiasis.

Adult↗
PubMed1993

Identification of an operon involved in the assimilatory nitrate-reducing system of Azotobacter vinelandii.

A number of mutants lacking nitrate reductase (Nas-) or nitrite reductase (Nis-) activities have been isolated and characterized. An operon including two new genes (nasA and nasB) has been defined and cloned from an Azotobacter vinelandii gene bank. nasA encodes for nitrite reductase apoenzyme, whereas nasB is specific for nitrate reductase activity. Nitrate reductase exerts a regulatory effect on nasAB.

Amino Acid Sequence↗
PubMed1993

An RFLP map for 2q33-q37 from multicase mycobacterial and leishmanial disease families: no evidence for an Lsh/Ity/Bcg gene homologue influencing susceptibility to leprosy.

The mycobacterial diseases leprosy and tuberculosis (TB) and the leishmaniases are characterized by a wide spectrum of disease phenotypes, and by the fact that the majority of individuals exposed to the causative organisms Mycobacterium leprae, M. tuberculosis and Leishmania sp. become infected but do not present with clinical disease. In order to determine whether a human homologue to the murine macrophage resistance gene Lsh/Ity/Bcg influences susceptibility to human disease, multicase families for all three diseases have been collected, and linkage analysis performed using a panel of markers in the region of human chromosome 2q33-q37 known to be conserved with the Lsh/Ity/Bcg-containing region of murine chromosome 1. Because of the paucity of available polymorphic markers/linkage information for 2q33-q37, data from 35 multicase leprosy, TB and visceral leishmaniasis families (310 individuals) were first pooled to produce a detailed RFLP map of the region. Peak LOD scores well in excess of 3 were observed for linkage between adjacent pairs of a more proximal (2q33-q35) set of markers CRYGP1, MAP2, FN1, TNP1, VIL1 and DES, and between adjacent pairs of a more distal (2q35-q37) set COL6A3, D2S55 and D2S3. These peak LOD scores and the corresponding values for theta were used in the MAP92 program to generate a multiple two-point map with gene order/map intervals (cM) of: CRYGP1-4.65-MAP2-3.45-FN1-5.95-TNP1-3.41-VIL1-3. 01- DES-20.14-COL6A-10.91-D2S55-3.67-D2S3. Although local support for the placement of loci in this order was weak (LOD < 2, except for DES-COL6A3 where LOD = 6.02), the map is consistent with the gene order for those loci (Cryg, Fn-1, Tp-1, Vil, Des, Col6a3) previously mapped in the mouse. Data from 17 multicase leprosy families (149 individuals) were further analysed for linkage between a putative disease susceptibility locus (DSL) controlling susceptibility to leprosy per se and each of the marker loci. Assuming 100% penetrance for the susceptibility allele, no positive LOD score was obtained for linkage between the DSL and any of the marker genes. Instead, the data provide convincing evidence (LOD scores < -2) that a DSL does not fall within 10-20 cM of CRYGP1, MAP2, TNP1, VIL1, DES or D2S55, or within 5-10 cM of FN1, COL6A3 or D2S3. This effectively excludes a putative DSL controlling susceptibility to leprosy per se from the entire region 2q33-q37.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Bronchial fistula to the mediastinum in a heart-lung transplant patient.

We present a case of heart-lung transplantation complicated by bronchial perforation as the cause or consequence of prolonged lung infection. Periodic bronchoscopic and radiological follow-up showed resolution of the condition following adequate antibiotic and physiotherapeutic treatment.

Adult↗
PubMed1992

Local and systemic antibody response in Balb/c mice immunized with Entamoeba histolytica trophozoites.

Several immunization schedules with E. histolytica trophozoites were tested on Balb/c mice in order to induce antibody responses, both in intestinal secretions and in serum. Mice were immunized either orally, systemically, or using one of two combined schedules: the oral route followed by the systemic route (footpad), or vice versa. Each of the immunization schedules used in this project induced an anti-E. histolytica antibody response and there appears to be a correlation between the immunization route employed and the immunoglobulin isotype induced in the gut. Secretory IgA production is favored by the oral administration of trophozoites, whereas mucosal IgG appears to be enhanced by the systemic immunization route. Both schedules are effective in the induction of secretory IgA in the gut, yet higher and earlier levels of IgA appear in orally immunized mice. When systemic immunization is employed, the increase in antibody levels in the intestinal fluid is slower, and IgG is the predominant class. The combined oral/systemic routes of immunization appear to be comparably effective for the induction of local and systemic IgA and IgM antibody production. However, mice immunized first systemically and then locally produce more IgG in both compartments. Combined schedules modify the isotype pattern of antibody responses in serum and in intestinal secretions when compared with single (i.e., oral or systemic) schedules, but they do not appear to favor a secretory IgA immune response.

Administration, Oral↗
PubMed1992

Inhibition of adhesion process mediated by anti-Entamoeba histolytica specific monoclonal IgA antibodies.

Adhesion of trophozoites to target cells in the host intestine is the first of three consecutive steps (adherence, cytolytic effect and phagocytosis) involved in the invasion of colonic tissue by E. histolytica. To investigate the possible participation of the local secretory immune response in the interference with this early host-parasite relationship, we produced IgA monoclonal anti-E. histolytica antibodies to test their capacity for blocking the adhesion process in vitro (MDCK and HT-29 cell lines) and in situ (colonic mucosa from Balb/c mice and gerbils). Results demonstrate that the monoclonal antibodies tested inhibited trophozoite adherence both in vitro and in situ. This suggests that the local antibody response may play an important role in protection against the invasive process in intestinal amebiasis.

Adenocarcinoma↗
PubMed1992

Prognostic value of S-phase white blood cell count in B-cell chronic lymphocytic leukemia.

Eighty previously untreated patients with B-cell chronic lymphocytic leukemia (B-CLL) were analyzed to study the proliferation rate of their peripheral blood (PB) leukocytes to determine its relationship with the extension of the disease and its value in discriminating among patients with similar tumor cell mass. The 80 B-CLL patients were distributed into two different groups according to the absolute count of PB S-phase leukocytes: a low proliferative group (less than 1 x 10(9)/I) of 48 patients and a high proliferative group (greater than or equal to 1 x 10(9)/I) of 32 patients. The high proliferative group displayed a higher incidence of splenomegaly (p less than 0.005), hepatomegaly (p less than 0.08), anemia (p less than 0.02) and thrombocytopenia (p less than 0.03) as well as a higher lymphocytic infiltration both in PB (p less than 0.0004) and in bone marrow (BM) (p less than 0.003). These patients also showed a higher incidence of a diffuse pattern of BM involvement (p less than 0.04), advanced clinical stages [stage III/IV (p less than 0.03) and group C (p less than 0.04)] and infections (p less than 0.0008) together with significantly lower IgG (p less than 0.03) and IgM (p less than 0.03) serum levels. Regarding the immunophenotype, there was a greater percentage of either CD19+ (p less than 0.06) and CD19+ CD5+ (p less than 0.05) B-cells, together with a greater reactivity for both the CD25 (p less than 0.04) and CD9 (p less than 0.08) antigens in the high proliferative group. According to the prognostic value of the PB S-phase leukocyte count it was seen that patients with low S-phase white blood cell (WBC) numbers displayed a significantly higher survival (p less than 0.03). In addition, multivariate analysis revealed that the S-phase WBC count, although partially related to other clinical and biological prognostic factors, displayed an important independent value in predicting early deaths in patients with B-CLL.

Aged↗
PubMed1991

Genotypic analyses of Richter's syndrome.

The authors report the immunogenotype of two cases of Richter's syndrome. The immunoglobulin gene rearrangement pattern obtained on Southern Blot analysis was found in both cases to be the same in leukemic blood cells and in the tissue involved by the lymphoma. The beta chain and gamma chain T-cell receptor gene rearrangement pattern exhibited a germ-line configuration in the peripheral blood cells and in the lymph node in Case 2, whereas in Case 1 the lymph node had a gene rearrangement in the beta chain, as well as in the gamma chain T-cell receptor, and the leukemic cells from bone marrow were found to be in a germ-line configuration for T-cell receptors (beta and gamma chains).

Aged↗
PubMed1991

Detection of Epstein-Barr virus sequences in primary brain lymphoma without immunodeficiency.

We searched for Epstein-Barr virus (EBV) sequences by enzymatic DNA amplification in nine primary brain lymphomas from patients without immunodeficiency. We used seven nonlymphoma brain tumors as negative controls, and the Raji cell line as a positive control. We detected EBV DNA, using ethidium bromide-stained-agarose minigel electrophoresis and dot blot hybridization, in the positive control and in only one brain lymphoma tumor; we did not detect EBV DNA in the other tumors. The EBV-positive patient had a second B-cell monoclonal population in the peripheral blood without detectable EBV DNA, suggesting a direct role for EBV in the development of the brain lymphoma.

Brain Neoplasms↗
PubMed1990

Clonotypic heterogeneity in cutaneous T-cell lymphomas.

The antigen receptor genes studied (immunoglobulin gene for B-cells, and T-cell receptor -beta or -gamma gene for T-cells) represent the most powerful tools for diagnosing the clonality of a lymphoid lineage. We have clonotyped 23 cutaneous T-cell lymphomas and 5 were found to be clonotypically all heterogeneous. Analysis of each patient was performed either from serial skin biopsies taken several months apart or from different tumor samples. In these cases, T-cell lymphoma clonotypic heterogeneity was demonstrated and was especially evident when examining different tumor sites. Moreover, in one case, a biogenotypic population (immunoglobulin and T-cell receptor-rearranged) was found. This unexpected high frequency of T-cell clonal heterogeneity (22%) could be explained either by the evolution of subclones from a single undifferentiated malignant cell or by the independent transformation to cancer of 2 or more lymphocytes, though the latter seems less likely. Clonotypic heterogeneity seems to be as frequent in T-cell lymphomas with cutaneous lesions as in B-cell leukemias.

Gene Rearrangement↗
PubMed1990

Inversion of the normal interatrial septum convexity in acute myocardial infarction: incidence, clinical relevance and prognostic significance.

Inversion of the normal interatrial septum convexity has been described in patients with right atrial pressure or volume overload, but there is no reference to this abnormality in acute myocardial infarction. A group of 576 consecutive patients with acute infarction and serial echocardiographic studies were prospectively evaluated during a mean follow-up period of 406 days. Inverted interatrial septum convexity was found in 30 patients (5.2%); 29 of the 30 presented with inferior infarction with right ventricular involvement (29 [24.4%] of 119) and the remaining presented with cardiac tamponade secondary to heart rupture. The incidence of inverted interatrial septum convexity rapidly decreased, and after 3 months it was present in only five patients. All patients with inverted interatrial septum convexity had a right atrial pressure greater than or equal to pulmonary capillary pressure, a relation found in only 2 of 43 patients with right ventricular involvement and normal septal convexity. In patients with right ventricular infarction, right atrial pressure was higher in the presence of inverted septal convexity (15.9 +/- 4.1 versus 10.5 +/- 4.1 mm Hg, p less than 0.0001) and the incidence of hypotension (10 [34.4%] of 29 versus 15 [17.4%] of 90, p = 0.04) and third degree atrioventricular block (10 [34.4%] of 29 versus 11 [12.2%] of 90, p = 0.006) as well as the mortality rate after 3 months (9 [31%] of 29 versus 11 [12.2%] of 90, p = 0.04) were higher in the presence of inverted convexity than in patients with normal septal convexity.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography↗
PubMed1990

Dual genotype in cutaneous T-cell lymphomas and pseudolymphomas.

Genomic DNA digests of skin biopsies from 20 patients with cutaneous T-cell lymphomas and pseudolymphomas were studied by hybridization, using probes for the constant region of the T-cell receptor beta chain and the joining region of the immunoglobin heavy chain gene. Skin biopsies from all 20 patients contained a monoclonal T-cell population. In addition, DNA from 5 patients contained an immunoglobulin gene rearrangement. These results demonstrate that cutaneous T-cell lymphomas are clonal T-cell malignancies that frequently express a dual genotype, which may sometimes reflect the clonotypic heterogeneity of these disorders.

Gene Rearrangement, beta-Chain T-Cell Antigen Rece↗
PubMed1990

A chromosomal linkage map of Azotobacter vinelandii.

A chromosomal map of Azotobacter vinelandii strain UW was constructed. The map was based on measures of cotransfer of various markers mediated by plasmids R68.45 and pJB3JI, on results obtained from conjugal experiments with R-primes, and on recombinants obtained by chromosomal transfer mediated by RP4/Tn5-Mob.

Azotobacter↗