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Biomedical subjects

S Martinez

Publications and source records attributed to S Martinez.

At least 145 records · Page 8Linked to original sources
PubMed1987

Streptococcus pneumoniae polA gene is expressed in Escherichia coli and can functionally substitute for the E. coli polA gene.

The Streptococcus pneumoniae polA+ gene was introduced into Escherichia coli on the recombinant plasmid pSM31, which is based on the pSC101 replicon. Extracts of E. coli polA5 mutants containing pSM31 showed DNA polymerase activity, indicating that the pneumococcal DNA polymerase I was expressed in the heterospecific host. Complete complementation of the E. coli polA5 mutation by the pneumococcal polA+ gene was detected in excision repair of DNA damage.

Cloning, Molecular↗
PubMed1987

What is the clinical significance of bone loss in primary hyperparathyroidism?

To help determine the clinical significance of the bone loss associated with primary hyperparathyroidism, we studied the prevalence of vertebral fractures in a group of patients with this disorder. From a registry of parathyroidectomies, 206 cases were reviewed, and lateral chest roentgenograms were studied for the presence of fractures. All roentgenograms were interpreted by two of the investigators who were "blinded" to diagnoses. Comparisons of readings were made that assured interrater agreement. A group of patients who underwent cholecystectomy served as controls. Studied in a logistic regression analysis model, controlling for the effects of age, sex, and race, primary hyperparathyroidism was found to be significantly associated with vertebral fractures. Subgroup analyses performed on the patients with hyperparathyroidism failed to identify specific biochemical or clinical markers associated with fractures. Our results suggest that the bone loss of primary hyperparathyroidism is clinically significant, leading not only to decreased bone densities but also to an increased prevalence of fractures.

Adult↗
PubMed1987

31P nuclear magnetic resonance study of variations in intra-erythrocytic ATP concentration and pH induced by surgical trauma.

Variations in intracellular pH and ATP concentrations in erythrocytes were studied in patients undergoing a mild surgical intervention. Intra-erythrocytic pH was decreased at the end of the operation; ATP concentrations concomitantly increased, but not highly significantly. These variables returned to their initial values by 20 h after the end of surgery.

Adenosine Triphosphate↗
PubMed1986

Occult carpal pathology: tomographic evaluation.

Pluridirectional tomography in coronal and sagittal planes has been used to identify occult carpal pathology in 23 patients with chronic wrist pain following recent or remote trauma. The tomographic studies have detected or further defined the carpal pathology in 22 of the 23 patients studied adding useful information concerning their clinical management.

Adolescent↗
PubMed1986

Cloning of a gene encoding a DNA polymerase-exonuclease of Streptococcus pneumoniae.

A procedure was developed for cloning and characterizing genes that encode proteins with nuclease activity in the Streptococcus pneumoniae [pLS1] host/vector system. Clones are screened for nuclease activity by a DNase colony assay and the nucleases that they produce are characterized by detection of enzyme activity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The method was used to clone the gene encoding a DNA polymerase (Pol)-exonuclease of S. pneumoniae. The activity of this enzyme, the predominant DNA Pol of S. pneumoniae, is tenfold greater in cells carrying the multicopy recombinant plasmid than in cells without the plasmid. The enzyme corresponds to a 100-kDa polypeptide, and its properties are similar to PolI of Escherichia coli. A restriction map of the pSM22 plasmid containing the pneumococcal polA gene was obtained. The gene was transferred into Bacillus subtilis and E. coli, and it was expressed in both species. Its direction of transcription was determined by placement of the gene in both orientations in an E. coli hyperexpression plasmid. In one of the orientations the pneumococcal PolI enzyme was produced at a level 50-fold greater than normally found in S. pneumoniae, and it comprised 5% of the total protein.

Bacillus subtilis↗
PubMed1986

Growth of Leishmania donovani amastigotes in the continuous human macrophage cell line U937: studies of drug efficacy and metabolism.

We have developed a simple and reproducible system for infecting a human macrophage cell line (U937) with stationary-phase Leishmania donovani promastigotes. Four days after infection, greater than 90% of the promastigotes had transformed to amastigotes. The antileishmanial agents allopurinol riboside, formycin B, 9-deazainosine, and sodium stibogluconate effectively inhibited the growth of L. donovani amastigotes in this cell line. To study the capability of amastigotes in the U937 cell line to carry out biochemical reactions that could be monitored experimentally, we incubated the cells with radiolabeled 9-deazainosine. This purine analogue underwent metabolism in the amastigote phase similar to that occurring in the promastigote phase. This cell line should be useful for studies of parasite maturation and differentiation, parasite-human interactions, and antiparasitic drugs.

Allopurinol↗
PubMed1986

Osteoarthritis of the sternoclavicular joint. Radiographic features and pathologic correlation.

Osteoarthritis (OA) of the sternoclavicular (SC) joint has been extensively characterized in the pathology literature, but the radiographic appearance of this entity has received comparatively little attention. To define the radiographic patterns of OA at this joint, we used high resolution PA radiographs (industrial grade film) to examine 55 SC joints obtained by block resection at autopsy. Ten of these also were selected for coronal complex motion tomography. Fifty cases were histologically correlated. Radiographic and pathologic material was evaluated by four criteria characteristic of OA: joint-space narrowing, osteophytes, sclerosis, and cysts. Each criterion was independently assessed for severity and distribution. Moderate or severe radiographic changes of OA were uncommon in specimens younger than age 40, but present in 53% older than age 60. Changes were typically bilateral, although a mild degree of asymmetry was common. OA was most severe along the inferior portion of the clavicular head, which comprises its articulating margin with the sternum. Complex motion tomography was generally more accurate than plain radiography for assessing OA in the ten specimens in which comparison was performed.

Adolescent↗
PubMed1986

Digital subtraction arthrography of the prosthetic hip.

Digital subtraction techniques are easily adapted to the evaluation of loosening in total hip prostheses, allowing real time review of injection dynamics and data manipulation after the study. We have successfully used both standard radiographic and digital imaging techniques in the evaluation of 15 prosthetic hip joints. The digital results are comparable to and often better than those of standard radiographic techniques for the evaluation of loosening in total hip prostheses.

Arthrography↗
PubMed1986

Computerized tomographic analysis of acute calcaneal fractures.

Computerized tomography (CT) of the hindfoot is introduced as an effective technique in the evaluation of acute, intra-articular calcaneal fractures. Thirty-two fractures in 30 patients have been reviewed, and common fracture characteristics identified. These included the presence of a sustentacular fragment, displacement and comminution of the lateral weightbearing surface, and lateral spread with loss of calcaneal height. Based on the improved understanding of fracture anatomy provided by the CT scan, treatment often can be determined more accurately.

Adult↗
PubMed1986

Computerized tomography of talocalcaneal tarsal coalition: a clinical and anatomic study.

Consistently accurate radiographic diagnosis of talocalcaneal tarsal coalitions is difficult because of the complex anatomy of the subtalar articulations. Standard techniques that include special radiographic views and plain tomography are useful but often inconclusive. In this study, computerized tomography (CT) was used to evaluate suspected talocalcaneal coalitions in patients with the clinical diagnosis of peroneal spastic flatfoot. CT demonstrated bony and nonbony coalitions in 14 of 22 patients studied. In the remaining eight patients, CT effectively ruled out the diagnosis of subtalar coalitions. If the coalition is obvious, CT will confirm it; if the clinical syndrome exists but standard radiographic procedures do not document the lesion, CT scan will be helpful in establishing a diagnosis. Anatomic studies of fresh cadaver feet compared CT, plain tomography, and plain radiographs for efficacy in visualizing the three subtalar facet joints. CT was superior to the other modalities for clearly identifying all aspects of the subtalar joint and talocalcaneal coalitions in patients and cadavers.

Adolescent↗
PubMed1986

[Indices of collective immunity to the hepatitis A virus in different geographical regions].

Antibodies to hepatitis A virus were determined in the sera of healthy population by enzyme immunoassay techniques. The distribution of antibodies in different age groups was compared, taking into account the proportion of persons with high, moderate and low titers. Among the surveyed regions, the highest proportion of nonimmune persons was detected in Moscow (45 %) and the lowest proportion, in Aralsk (7%) and Mongolia (3%). In some regions (Moscow, Vilnius) the characteristic feature of the immune structure of the population was the gradual increase of the occurrence of antibodies and their levels with age, while in other regions (Aralsk, Mongolia) the intensive acquisition of antibodies occurred at younger ages with a subsequent decline in antibody levels. Some of the possible mechanisms of the formation of population immunity to hepatitis A are discussed.

Adolescent↗