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Biomedical subjects

N Martinez

Publications and source records attributed to N Martinez.

35 records · Page 2Linked to original sources
PubMed1991

DNA sequences 3' of the Ig H chain cluster rearrange in mouse B cell lines.

A mouse myeloma cell line MPC11 (IgG2b, kappa) and variants derived from it have been used to study DNA rearrangements that occur at the Ig H chain locus. One variant, F5.5, has acquired both VH gene and C epsilon gene rearrangements. Through genomic Southern blot analysis initially directed to mapping the C epsilon gene rearrangement, we observed that the VH region rearrangement was linked, through an inversion event, to sequences that originate 3' of the CH cluster, i.e., 3' of the C alpha gene. Subsequent studies have shown that DNA rearrangements within the region 3' of the C alpha gene are detected in several other mouse myeloma and hybridoma cell lines and are not associated with the expression of specific isotypes.

Animals↗
PubMed1988

Mechanism of class switching.

We have documented the action of unequal sister chromatid exchange on antibody genes, and our studies provide the first molecular description of an unequal sister chromatid exchange event. We delineated the sequences that mediate class switch recombination in normal B cells through genomic Southern analysis of five IgG2-producing hybridomas. Successive subclass switching was documented in two of eight maps and may possibly account for interposed DNA in three additional maps, implying that subclass switching may be a relatively frequent occurrence in normal B cells. As in most other myelomas and hybridomas, the 5' breakpoint of switch recombination in our panel of hybridomas falls 5' to Cmu-associated tandem repeats, whereas the 3' breakpoint falls within C gamma-associated tandem repeats. We consider various hypotheses in the text, the most interesting of which is that deletion of Cmu-associated tandem repeats is a necessary first step before class switch recombination in mature B cells. This hypothesis suggests that Cmu-associated tandem repeats may be a separately regulated DNA element.

Animals↗
PubMed1982

Computerized rapid analysis of pulmonary function test: use of a least mean squares correlation for interpretation of data.

Although systems for automated calculation and interpretation of screening pulmonary function tests (PFT) have been discussed by previous investigators, these systems are often unavailable to other users, require large or hybrid computers, or are difficult to modify. The use of a branching decision tree for PFT interpretation may also limit the number of correlations possible and make revision of the program difficult because changes in the proximal branches of the tree require a rewriting of the entire distal program. We have developed a system based on a minicomputer which uses a least mean squares analysis for rapidly analyzing the patient's PFT data. This program considers the following types of PFT data singly and in combination: percentage predicted total lung capacity and/or alveolar volume, forced expiratory volume in one second to forced vital capacity ratio (before and after bronchodilator or 80% helium challenge), and percentage predicted single breath diffusing capacity for carbon monoxide. The interpretation program (IP) then selects the 'best interpretation' for the patient by computing the variance between the patient's data and data from a menu of over 120 interpretation statements. During the past two years we have used this system for screening over 3000 patients. In about 90% of patients the computer selected interpretation statements which were acceptable to a sub-specialty pulmonary physician. The use of this IP for screening purposes has facilitated the efficient use of laboratory personnel and equipment.

Diagnosis, Computer-Assisted↗
PubMed1981

Geriatric hypochondriasis: situational factors.

The hypochondriacal attitudes of 53 aged community residents were studied. No significant correlations were found with situational stress, sex, or ethnicity (English-speaking vs Spanish-speaking). The levels of hypochondriasis appeared to be inversely related to self-evaluation of memory ability. There was no indication of an inherent iatrogenic effect. It was concluded that hypochondriacal behavior is chiefly a function of the underlying personality, which may influence the perception of events as stressful.

Aged↗
PubMed1981

'Rhabdoid' Wilms' tumor: an ultrastructural study.

We studied a 5-week-old infant who had a "rhabdoid" Wilms' tumor. Ultrastructural studies disclosed aggregates of cytoplasmic filaments that seemed to correspond with the eosinophilic cytoplasmic bodies seen by light microscopy, but did not uncover evidence of rhabdomyoblastic differentiation. The histogenesis of this subtype was not established, but origin from the metanephric blastema could not be ruled out.

Humans↗
PubMed1980

Ten year evaluation of posterior fundoplasty in the treatment of gastroesophageal reflux: long-term and comparative study of 135 patients.

Results over a 5 to 10 year period in 135 patients with hiatal hernia treated surgically by posterior fundoplasty were compared with results in a similar group of 40 patients undergoing Nissen fundoplication. The final results demonstrate the effectiveness of both procedures to relieve gastroesophageal reflux. However, the collateral effects with posterior fundoplasty are considerably less than those with the Nissen fundoplication. The lower esophageal sphincter was longer with fundoplasty than with the Nissen procedure.

Deglutition Disorders↗
PubMed1977

Cystadenoma of the pancreas. An ultrastructural study.

A case of cystadenoma of the pancreas was studied at the light (LM) and the ultrastructural (EM) levels. The observation made under LM that the flattened epithelial cells lining the cystic spaces were similar to the centroacinar cells of a normal pancreas was supported by EM findings. Numerous glycogen granules were demonstrated in the cells, a feature characteristic of fetal but not adult centroacinar cells. A few epithelial cells contained occasional membrane bound dense granules of unknown nature. This observation and the finding of normally appearing islets of Langerhans raise the possibility that this may be an example of a mixed insular-duct cystadenoma. However, if the islets of Langerhans were considered entrapped structures, this tumor should be labelled as a simple serous cystadenoma.

Aged↗
PubMedDate not supplied

[Comparative efficacy of intradermal and intramuscular active immunization against hepatitis B with a recombinant vaccine. Preliminary results].

Preliminary results of a prospective, comparative and randomized study on 119 sero-negative volunteers with increased risk to acquire hepatitis B, aimed to evaluate the comparative efficacy of a recombinant vaccine administered either intramuscularly or intradermally, are discussed. A short vaccination schedule of three consecutive doses given on months 0, 1 and 2 was used. Distribution by sex and age for both groups was similar. Seroconversion and seroprotection rates were comparable (96% and 96% Vs. 98% and 93%, respectively). The geometric mean titre of anti-HBsAg in individuals immunized via I.M. (155 IU/L) was significantly higher to that of the I.D. group (71 IU/L). On the other hand, the rate of good response (> 100 IU/L) was also higher in the I.M. group (67% Vs. 39%). The percentage of good responder in women was consistently higher than in men for both groups (75% Vs. 13%, respectively). In 68 vaccinees, samples were obtained one year later. The levels of anti-HBsAg and the anamnesic response after a booster of the vaccine are currently being assayed.

Adult↗