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Biomedical subjects

A Jimenez

Publications and source records attributed to A Jimenez.

At least 73 records · Page 4Linked to original sources
PubMed1993

Detection of Epstein-Barr virus by polymerase chain reaction in transbronchial biopsies of lung transplant recipients: evidence of infection?

Thirty-nine paraffin-embedded transbronchial biopsies from ten lung transplant recipients were evaluated by the polymerase chain reaction for the presence of Epstein-Barr virus (EBV). Six of these patients had positive EBV serology. Nine biopsies from nine non-transplant patients with nonspecific interstitial pneumonitis were studied as a control group. Eight biopsies from four of the ten transplant patients (40%) were positive for EBV by polymerase chain reaction, utilizing 40 cycles and two sets of primers (501/502) complementary to sequences within the Bam H1 W region of the viral genome. Five of these eight positive biopsies had been diagnosed as mild acute cellular rejection based on clinicopathologic criteria. Three of the four EBV-positive patients showed clinical improvement with antiviral agents prescribed for concomitant cytomegalovirus infection. Our data demonstrate the potential of polymerase chain reaction to detect small quantities of EBV in transbronchial biopsies from lung transplant recipients. Such findings should be interpreted cautiously in the evaluation of lung transplant recipients, since EBV can be detected in the absence of a lymphoproliferative disorder or an active pneumonitis caused by this virus.

Adult↗
PubMed1992

Effects on platelet aggregation and fibrinolytic activity during upright posture and exercise in healthy men.

The circadian variation of acute myocardial infarction suggests that daily activities such as assuming the upright posture and performing different daily activities may trigger the onset of coronary thrombosis. Such triggering may result from unfavorable alterations in the balance between the prothrombotic and antithrombotic properties of the blood. The present study compares the effects of 2 common daily activities, assuming the upright posture and exercise, on platelet aggregation and fibrinolytic activity. In healthy male subjects, assuming the upright posture in the morning significantly increased platelet aggregation and produced only a moderate increase in fibrinolytic activity within 10 minutes. These changes were still present after 90 minutes in the upright posture. Supine posture for 45 minutes resulted in levels of fibrinolytic activity and platelet aggregation comparable to that observed before initially assuming the upright posture in the morning. Return to the supine posture for 45 minutes resulted in levels of fibrinolytic activity and platelet aggregation comparable to that observed before the initial assumption of upright posture. The changes recurred when upright posture was taken later in the day. Exercise did not increase platelet aggregation to levels beyond that produced by the upright posture, but was associated with a marked increase in fibrinolytic activity. Thus, exercise and upright posture produce distinctive alterations in the thrombogenic potential of the blood that may influence the timing of clinical vascular events.

Adult↗
PubMed1992

Viability of Echinococcus granulosus cysts in mice following cultivation in vitro.

The viability of hydatid cysts developed in vitro for 90 days was assessed by implantation into mice. Cysts removed from mice at 270 days post-infection (p.i.) increased their size 13.5-fold and contained several brood capsules containing protoscoleces. Thus, cysts remain viable after prolonged in vitro culture. The implantation in mice of 15 cysts developed in vitro yielded an average of 10 cysts per mouse, which is indicative of a high survival rate in these experimental infections. The ultrastructural study of cysts recovered from mice 270 days p.i. showed that the germinal membrane was more compact than before implantation and several layers of tegumental cells had developed. Observations of cysts removed from mice indicated that the plasma membrane surrounding microtriches had prolongations opening into the laminated layer.

Animals↗
PubMed1991

The role of the endoscopic biopsy in the diagnosis of gastric lymphoma: a morphologic and immunohistochemical reappraisal.

Forty-three endoscopic biopsies from 29 patients with confirmed gastric lymphoma (GL) were analyzed retrospectively to establish the morphologic criteria of greatest diagnostic significance. An average of 10 tissue samples was obtained at each endoscopy. In 44% of the cases, lymphoma was discovered in only one or two of the tissue portions. Eighteen lymphomas were primary, six were probably primary, and five were generalized. The diagnosis of lymphoma was originally suspected or established in 46% of the biopsies. However, a review of the histologic sections indicated that the changes, either diagnostic of or compatible with lymphoma, were present in 75% and 18% of the sections, respectively. Most diagnostic errors consisted of confusion with diffuse lymphoid infiltrates in chronic gastritis and/or peptic ulcer, and less frequently with poorly differentiated carcinoma. In those cases confused with chronic gastritis or peptic ulcer, biopsies showed centrocyte-like cells of the standard type or small lymphocytes which produced: (1) a marked increase in density of the lymphoid infiltrate in the gastric mucosa, (2) massive substitution of gastric glands by lymphoid infiltration, and (3) a collection of lymphocytes infiltrating and partially destroying isolated glands (lymphoepithelial lesion). From 48 biopsies having intense benign lymphoid infiltrates, three were interpreted (by means of a blinded study) as compatible with GL. In poorly differentiated neoplasms (blastic and pleomorphic types), cytologic features were sufficient to diagnose GL or malignant neoplasms; immunohistochemical techniques were useful to define their lymphoid nature. It is concluded that many GLs can be suspected or correctly diagnosed by routine endoscopic biopsy.

Adult↗
PubMed1991

Ureteral triplication and ureterocele: report of 3 cases and review of the literature.

We report 3 cases of ureterocele associated with ureteral triplication and review the literature. Ureteral triplication was type I in 2 patients and type II in 1. Diagnosis was established preoperatively in 2 cases and intraoperatively in 1. All patients were initially treated by upper pole partial nephrectomy and aspiration of the ureterocele, leaving the ureteral stump open in the retroperitoneum. Subsequent excision of the ureterocele and ureteral reimplantation for persistent ipsilateral vesicoureteral reflux and recurrent urinary tract infections were required in 2 cases.

Child, Preschool↗
PubMed1990

Characterization of Saccharomyces cerevisiae strains displaying high-level or low-level resistance to trichothecene antibiotics.

Biochemical and genetic analyses have been carried out on Saccharomyces cerevisiae strains characterized in vivo as sensitive, low-level-resistant or high-level-resistant to trichothecene antibiotics. Levels of drug resistance in vitro were determined for each strain and for suitable diploids derived from them. Ribosome biogenesis was also studied in selected haploids. It is suggested that resistance in all cases results from a mutation in the gene encoding ribosomal protein L3. If this is indeed the situation, then different mutations in this same gene not only can cause low-level or high-level resistance to trichothecene antibiotics but also can affect the maturation of either 40 S or 60 S ribosomal subunits.

Drug Resistance, Microbial↗
PubMed1990

Ischemic reperfusion injury in rabbit spinal cord: protective effect of superoxide dismutase on neurological recovery and spinal infarction.

The potential role of superoxide dismutase (SOD), a specific superoxide anion radical scavenger, in treating spinal cord ischemia was investigated in rabbits subjected to aortic occlusion for 20 min. SOD treatment, targeted to the early reperfusion period, reduced both motor dysfunction and incidence of spinal infarcts at 7 days after ischemia. Present results suggest that oxygen-derived free radicals play a role in the pathogenesis of infarcts developing in the spinal cord after ischemia and reperfusion injuries.

Animals↗
PubMed1990

[Barodontology: current status. Dental aspects].

We present a comprehensive review of barodontalgia, with reference to the several pathogenetic hypotheses, and insisting on the consideration of barodontalgia in the differential diagnosis of toothache. The odontologists approach to this increasing clinical problem is also discussed.

Aerospace Medicine↗
PubMed1990

In vitro effect of plasma during phenylhydrazine-induced erythrocyte oxidative damage.

Erythrocytes were incubated for 60 min either in plasma or phosphate-buffered saline containing 10 mM phenylhydrazine hydrochloride. Plasma prevented the decrease in membrane fluidity observed in saline-phenylhydrazine incubated erythrocytes but these cells showed decreases in both filterability and active extrusion of Na+ that were nearly 100% lower than those found in erythrocytes incubated in plasma-phenyl-hydrazine. Also erythrocyte lipid peroxidation, as measured as thiobarbituric acid reactive products, was 100% higher in the presence of plasma. These results suggest that plasma could play "in vivo" an active role during oxidant-induced erythrocyte damage, contributing significantly to the hemolytic effects of oxidation.

Animals↗
PubMed1989

Latissimus dorsi free flap for restoration of facial contour defects.

The treatment of facial asymmetries presents an aesthetic component of great importance. To correct facial contour defects, there are many therapeutic possibilities available, such as autologous tissue grafts and inorganic implants. The arrival of microsurgical techniques has improved the outlook for facial contour restoration. Among the tissues used are groin, escapular, and omentum flaps. This article introduces our experience with the latissimus dorsi free flap for the restoration of facial contour defects. Our experience is based on 7 patients affected with hemifacial microsomia and Romberg's disease. Operative planning, surgical procedure, and results are described. The use of the latissimus dorsi free flap is our procedure of choice for its greater adaptability in conforming to the shape of the defect, its long vascular pedicle, the abundance of available tissue, and minimal tendency to ptotic changes. At present we recommend this technique for replacement of soft tissue in severe defects of the face.

Adult↗
PubMed1989

Annual changes in the number, testosterone content and ultrastructure of glandular tissue cells of the testis in the marbled newt Triturus marmoratus.

The testes of 8 specimens of Triturus marmoratus were collected during each month of 1987 and processed for electron microscopy and light microscopy demonstration of testosterone (T) following the ABC (avidin-biotin peroxidase complex) method. According to their staining affinity for anti-T antibodies, the glandular tissue cells were classified as T-, T+, T++, and T and the annual changes in the numbers of these cell populations, as well as in the volume occupied by the glandular tissue, were calculated. The volume occupied by the glandular tissue increases from September to December; it begins to decrease in April and disappears from June to August. The glandular tissue is formed from the interstitial cells that surround the lobules containing differentiating germ cells. During the spermatogenic process, the interstitial cells do not show staining affinity for anti-T antibodies. In August-September, the interstitial cells around the lobules that have completed spermatogenesis become positively stained (T+) and form the glandular tissue when the spermatozoa leave the testis. The numbers of intensely stained cells in the glandular tissue (T++ and T ) increase from September to November; begin to decrease in December; disappear in January-February; increase again in March and decrease again in April until they disappear in June-September. The interstitial cells, before their transformation in glandular tissue, are ultrastructurally similar to fibroblasts. After their transformation these cells increase in size and develop abundant smooth endoplasmic reticulum, mitochondria with tubular cristae and lipid droplets. This morphological pattern is maintained in the glandular tissue from September to April in spite of the changes in staining affinity during this period.

Animals↗
PubMed1986

Premature centromere division dominantly inherited in a subfertile family.

An increased frequency of mitoses showing premature centromere division (PCD) in every chromosome was found in lymphocyte cultures from four members of a subfertile family. These cells were observed in both the presence and absence of colchicine. Cultured fibroblasts from the proband showed only normal diploid metaphases. PCD cells seemed to have a shorter cell cycle. The anomaly was transmitted in a way compatible with autosomal dominant inheritance in this family.

Cells, Cultured↗
PubMed1985

Biosynthesis of puromycin by Streptomyces alboniger: characterization of puromycin N-acetyltransferase.

Puromycin N-acetyltransferase from Streptomyces alboniger inactivates puromycin by acetylating the amino position of its tyrosinyl moiety. This enzyme has been partially purified by column chromatography through DEAE-cellulose and Affigel Blue and characterized. It has an Mr of 23 000, as determined by gel filtration. In addition to puromycin, the enzyme N-acetylates O-demethylpuromycin, a toxic precursor of the antibiotic, and chryscandin, a puromycin analogue antibiotic. The Km values for puromycin and O-demethylpuromycin are 1.7 and 4.6 microM, respectively. The O-demethylpuromycin O-methyltransferase from S. alboniger, which apparently catalyzes the last step in the biosynthesis of puromycin [Rao, M. M., Rebello, P. F., & Pogell, B. M. (1969) J. Biol. Chem. 244, 112-118], also O-methylates N-acetyl-O-demethylpuromycin. The Km values of the methylating enzyme for O-demethylpuromycin and N-acetyl-O-demethylpuromycin are 260 and 2.3 microM, respectively. These findings suggest that O-demethylpuromycin, if present in S. alboniger, would be N-acetylated and then O-methylated to be converted into N-acetylpuromycin. It might even be possible that N-acetylation of the puromycin backbone takes place at an earlier precursor.

Acetylation↗