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Biomedical subjects

A Martinez

Publications and source records attributed to A Martinez.

At least 289 records · Page 16Linked to original sources
PubMed1993

External beam and intraoperative electron irradiation for locally advanced soft tissue sarcomas.

PURPOSE: Intraoperative irradiation with electrons was used in conjunction with external beam irradiation and maximal surgical resection in 20 patients with locally advanced soft tissue sarcomas or desmoids. This manuscript presents results with regard to tolerance of treatment and its impact on tumor control and survival. METHODS AND MATERIALS: Ten patients presented with previously untreated primary sarcomas and 10 at the time of local recurrence (two had recurrent desmoid tumors). Tumor location was retroperitoneal in 19 and in the low anterior neck in one. A partial or gross total resection was performed prior to the external beam or intraoperative component of irradiation in every patient, but all had positive resection margins. Patients received 4500-6000 cGy of fractionated, external beam irradiation and an IORT dose of 1000-2000 cGy. Chemotherapy was given only at the time of disease progression. RESULTS: Fourteen of 20 patients (70%) were alive; 11 (55%) were free of disease (4/10 primary, 7/10 recurrent), but 1 required hemipelvectomy for salvage. Progression within the intraoperative irradiation field was documented in only 1 patient (5%) and within the external beam field in 3/20 (15%). Blood born distant metastasis occurred in 5 patients (25%) and peritoneal seeding in 1 (5%). The distant failure incidence by grade was 1/8 (13%) for Grades 1, 2 and 5/12 (42%) for Grades 3, 4. Only 1 patient (5%) developed a > or = severe neuropathy, and small bowel obstruction requiring exploration also occurred in a single patient. CONCLUSION: In view of acceptable tolerance and the high current rate of local tumor control, in spite of incomplete surgical resections, further evaluation of intraoperative irradiation as a component of treatment is indicated for locally advanced primary and recurrent soft tissue sarcomas.

Adult↗
PubMed1993

Multiple genes encode the major surface glycoprotein of Pneumocystis carinii.

The major surface antigen of Pneumocystis carinii, a life-threatening opportunistic pathogen in human immunodeficiency virus-infected patients, is an abundant glycoprotein that functions in host-organism interactions. A monoclonal antibody to this antigen is protective in animals, and thus this antigen is a good candidate for development as a vaccine to prevent or control P. carinii infection. We have cloned and sequenced seven related but unique genes encoding the major surface glycoprotein of rat P. carinii. Partial amino acid sequencing confirmed the identity of these genes. Based on Southern blot studies using chromosomal or restricted DNA, the major surface glycoproteins are the products of a multicopy family of genes. The predicted protein has an M(r) of approximately 123,000, is relatively rich in cysteine residues (5.5%) that are very strongly conserved, and contains a well conserved hydrophobic region at the carboxyl terminus. The presence of multiple related msg genes encoding the major surface glycoprotein of P. carinii suggests that antigenic variation is a possible mechanism for evading host defenses. Further characterization of this family of genes should allow the development of novel approaches to the control of this pathogen.

Amino Acid Sequence↗
PubMed1993

Protein blot assays specific for the discrimination of the centromere autoantigen, CENP-A, from human cells.

The Western or protein blot has proven to be a valuable resource in detecting discrete, immunoreactive antigen targets associated with a variety of autoimmune diseases. As the roster of autoantigens has expanded, it has become increasingly common to tailor specific gel or blot conditions to a particular polypeptide antigen. Two such assays are reported here as applied to the fractionation and visualization of human centromere protein (CENP-A), a centromere autoantigen associated with the rheumatic disease, systemic sclerosis. The centromere antigens are effectively solubilized in the presence of 1 M MgCl2 to allow for further purification. CENP-A copurifies with the histone proteins, primarily H3 and H4. The two CENP-A-specific protein blot assays separate CENP-A from the histone proteins and enhance CENP-A immunoreactivity. The first assay is based on the use of acid-urea gels with a Triton X-100 concentration chosen to maximize separation of CENP-A from all the histones. The second assay is based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis to differentiate two very basic proteins of similar molecular weight, namely CENP-A and histone H3. For each gel system, a selective choice of associated immunoblot parameters allows for the reproducible discrimination of the CENP-A antigen.

Autoantigens↗
PubMed1993

Cis-regulatory sequences leading to female-specific expression of yolk protein genes 1 and 2 in the fat body of Drosophila melanogaster.

The three yolk protein genes (yp) of Drosophila melanogaster are transcribed in a sex- and tissue-limited fashion. We have searched for cis-regulatory sequences in regions flanking yp1 and yp2 to identify the elements that confer female-specific expression in the fat body. One such 127 bp element has previously been identified in this region. We show here the existence of two additional regions which confer female fat body-specific expression on an Adh reporter gene and on the native yp2 gene, respectively. This suggests some redundancy in the regulation of expression of the yp genes. Computer searches for putative binding sites for the DSX protein, which regulates sex-specific expression of the yp genes, revealed several such sites in our constructs. However, the significance of these is unclear since many such sites also occur in genes which one would not expect to be regulated in a sex-specific manner (e.g. Adh, Actin 5C). We suggest that DSX acts in concert with other proteins to mediate sex- and tissue-specific expression of the yp genes.

Alcohol Dehydrogenase↗
PubMed1993

Chandelier cell axons identified by parvalbumin-immunoreactivity in the normal human temporal cortex and in Alzheimer's disease.

Parvalbumin is a calcium-binding protein which is thought to play a role in neuronal excitability. In the cerebral cortex parvalbumin is largely found in two subsets of GABAergic neurons, the chandelier and basket cells. A distinguishing characteristic of the chandelier cell is that the terminal portions of its axon form short vertical strings of boutons resembling candlesticks, which embrace the initial segment of pyramidal cell axon. In the present study, the terminals of chandelier cells in the human temporal cortex were immunostained with an antibody against parvalbumin. These terminals were found more abundantly in layers II and VI, less frequently in layers III and V, were hardly identified in layer IV, and absent in layer I. The relationship of parvalbumin-immunoreactive terminals and axon initial segments was further evidenced by re-sectioning identified rows of boutons into semithin sections. Electron microscopy of both temporal cortex and the somatosensory region of a biopsy sample revealed that these parvalbumin-positive boutons indeed form symmetric synaptic contacts on the axon initial segments of pyramidal cells. As part of an enquiry into the possibility that these specialized interneurons may be involved in degenerative neurological diseases, the temporal lobes from seven patients with Alzheimer's disease were immunostained for parvalbumin. As in the control brains, the specific terminal portions of chandelier cells were recognized and identified in the temporal cortex by parvalbumin-immunocytochemistry. No major difference from normal brains was found, excepting for a lower density of candlesticks (30-35%) in layer II-III. Since we showed in a previous study [Ferrer et al. (1991) J. neurol. Sci. 106, 135-141] that the number of parvalbumin-immunoreactive somata in the same Alzheimer's disease cases was not decreased, the observed reduction of terminals in layer II suggest that only the terminals of chandelier cells, but not the parent neurons, are decreased in Alzheimer's disease.

Aged↗
PubMed1993

Conversion rates of induced versus spontaneous ventricular tachycardia by a third generation cardioverter defibrillator. The VENTAK PRx Phase I Investigators.

Seventy consecutive patients received the first VENTAK PRx pulse generators (Cardiac Pacemakers, Inc.) implanted in the United States. This multiprogrammable device has therapeutic options that include: (1) antitachycardia pacing; (2) low energy cardioversion; (3) defibrillation shocks; and (4) bradycardia pacing. There were 60 males and 10 females with a mean age of 65.3 +/- 9.4 years. The anatomical diagnoses were coronary artery disease in 55 patients, cardiomyopathy in 7 patients, congenital heart disease in 2 patients, and miscellaneous disease in the remaining 6 patients. Thirty-six percent had a history of sudden cardiac death and 90% had documented monomorphic ventricular tachycardia. The mean ejection fraction was 32.7% +/- 12.2%. Thirty-three (49.3%) had an ejection fraction < or = 30%. Electrophysiological testing was done preimplant, predischarge, and 1 to 2 months postimplant to define a specific electrical therapy and evaluate the efficacy of the device. Two hundred ninety-three of 367 (80%) episodes of induced ventricular tachycardia were successfully terminated by the VENTAK PRx programmed for antitachycardia pacing. There were 1,794 total therapy episodes for spontaneous ventricular tachycardia; 91% (1,641 episodes) were terminated by antitachycardia pacing and 153 episodes were converted by shocks during a minimal 6-month follow-up per patient. We conclude that documentation of a successful antitachycardia pacing modality in the electrophysiology laboratory predicts conversion of spontaneous episodes of ventricular tachycardia. Furthermore, antitachycardia pacing by the VENTAK PRx can terminate the majority of episodes of ventricular tachycardia.

Aged↗
PubMed1993

Development and characterization of a rapid screening assay for identifying antipneumocystis agents.

We developed a rapid assay for screening of compounds with potential antipneumocystis activity on the basis of incorporation of [35S]methionine into proteins newly synthesized by Pneumocystis carinii. Unambiguous evidence that P. carinii synthesizes proteins in vitro was provided by immunoprecipitation studies demonstrating the incorporation of [35S]methionine into the major surface glycoprotein. Treatment with two clinically active antipneumocystis agents, atovaquone (10(-4) M) or pentamidine (10(-4) M), prevented this incorporation. Total [35S]methionine incorporation paralleled incorporation into the major surface glycoprotein, permitting rapid assessment of anti-P. carinii activity by scintillation counting. Treatment with pentamidine (1 x 10(-4) M), atovaquone, trimethoprim (1 x 10(-4) M)-sulfamethoxazole (7.9 x 10(-4) M), piritrexim (1 x 10(-7) M), RO11-8958 (1 x 10(-4) M), and amphotericin B (1 microgram/ml) resulted in a greater than 67% inhibition (P < 0.05) of [35S]methionine incorporation. No decrease in [35S]methionine incorporation was seen with dapsone (10(-5) M), trimethoprim (10(-4) M), recombinant mouse tumor necrosis factor (500 ng/ml), or gamma interferon. This rapid in vitro assay should be a useful adjunct in the development of new antipneumocystis agents.

Amphotericin B↗
PubMed1993

Functional characterization of the L-type pyruvate kinase gene glucose response complex.

L-type pyruvate kinase (L-PK) gene expression is modulated by hormonal and nutritional conditions. We have previously shown that the glucose/insulin response element (GlRE) of the L-PK gene is built around two noncanonical E boxes (element L4) that cooperate closely with a contiguous binding site (element L3). We present in this report the identification of proteins that interact with both elements. The L3 site binds hepatocyte nuclear factor 4 (HNF4)- and COUP/TF-related proteins. In fibroblasts, the overexpression of HNF4 transactivates the L-PK promoter. On the contrary, COUP/TF strongly inhibits the active promoter in hepatocytes. The L4 site binds the major late transcription factor (MLTF) in vitro and ex vivo; mutations that suppress this binding activity also inactivated the GlRE function. Mutations transforming one or two noncanonical E boxes of element L4 into consensus MLTF/USF binding sites strongly increase the affinity for MLTF/USF and do not impair the glucose responsiveness. However, merely the ability to bind MLTF/USF does not seem to be sufficient to confer a GlRE activity: those elements in which one E box has been destroyed and the other has been transformed into a consensus MLTF/USF sequence bind MLTF/USF efficiently but do not confer a high glucose responsiveness on the L-PK gene promoter. Consequently, the full activity of the L-PK GlRE seems to require the cooperation between two putative MLTF/USF binding sites located in the vicinity of an HNF4 binding site.

Animals↗
PubMed1993

Volume-activated Rb+ transport in astrocytes in culture.

The involvement of K+ on the volume regulatory process in astrocytes was investigated by characterizing the hyposmolarity-induced efflux of K+ using 86Rb as a tracer. About 70 and 30% of the intracellular content of 86Rb was released after reductions in osmolarity from 320 to 160 or 220 mosM, respectively, during the time in which cells exhibit a volume regulatory response subsequent to swelling. No significant increase in 86Rb efflux was observed with lower reductions in osmolarity. The 86Rb efflux was Ca2+ independent and insensitive to temperature. It was inhibited by furosemide but not by bumetanide and was unaffected when nitrate, but not gluconate, replaced intracellular Cl-. The efflux was markedly inhibited by quinidine and by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. Quinidine also prevented the volume regulatory decrease of cells, and this effect was overcome when a large cation permeability was imposed by gramicidin. In isosmotic conditions 86Rb efflux was not activated by N-ethylmaleimide, but this drug strongly inhibited the hyposmolarity-activated release. These findings suggest that 86Rb efflux from astrocytes associated to cell swelling is not mediated by an electroneutral cotransporter and rather favor the implication of a conductive exit pathway that may be a Ca(2+)-independent K+ channel.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1993

Characterization and localization of endothelial nitric oxide synthase using specific monoclonal antibodies.

We have produced specific monoclonal antibodies (MAb) against particulate bovine aortic endothelial nitric oxide synthase. In Western blots, native and cultured bovine aortic endothelial cells as well as cultured bovine microvascular endothelial cells possess immunoreactive NO synthase. In dot blots, MAb H210 and H32 detect 1 ng and 100 pg of purified endothelial NO synthase, respectively. Both antibodies are specific to the endothelial NO synthase and do not cross-react with other known isoforms of NO synthase, namely from the brain, from cytokine/endotoxin-induced macrophages, or from cytokine/endotoxin-induced vascular smooth muscle cells. Immunohistochemical studies demonstrated the specificity of endothelial NO synthase for endothelial cells in various bovine and human tissues. Many types of endothelial cells, macrovascular, microvascular, arterial, and venous were found to possess this specific isoform of NO synthase. Electron microscopy showed the enzyme to be associated with the plasma membrane, membranes of cytoplasmic vesicles, and in the cytoplasm in human umbilical vein endothelial cells. The results demonstrate that particulate endothelial NO synthase is present in a site to act rapidly to produce NO for release into the blood or toward the smooth muscle in many vascular beds.

Amino Acid Oxidoreductases↗
PubMed1993

Effects of corticosteroids in preterm sheep on adaptation and sympathoadrenal mechanisms at birth.

This study investigates the effects of prenatal corticosteroid administration on newborn sympathoadrenal mechanisms involved in postnatal adaptation. Randomly assigned preterm (122-125 days) fetal sheep were treated with hydrocortisone or saline for 60 h and delivered by cesarean section. We examined postnatal physiological adaptation, sympathoadrenal responses, cardiac beta-receptor density, and the receptor-cyclase system. We observed increased ventilatory, cardiovascular, and metabolic responses function in the corticosteroid-treated animals despite a marked attenuation in the anticipated surge of plasma catecholamine concentrations and a decrease in epinephrine secretion rate, which is normally seen at birth. Myocardial beta-adrenergic receptor density and affinity states were comparable in both groups. Basal and agonist-mediated adenylyl cyclase activity in myocardial tissue was increased in the corticosteroid-treated animals. We speculate that the increase in myocardial adenylyl cyclase activity may be accompanied by similar changes in other organ systems and that this could account for the augmentation in respiratory, cardiovascular, and metabolic responses in the corticosteroid-treated animals.

Acclimatization↗
PubMed1993

Plasma epinephrine appearance and clearance rates in fetal and newborn sheep.

Newborn plasma catecholamine levels are elevated compared to fetal life. Whether this reflects increased catecholamine secretion after birth or decreased clearance is not known. To determine the plasma appearance and clearance rates for catecholamines during the transition to postnatal life, we compared plasma epinephrine appearance and clearance rates in fetal sheep before birth and in newborns after delivery. Plasma epinephrine appearance and clearance rates were measured by radiotracer analysis in eight fetuses at 127 +/- 1 days of gestation and, after cesarean delivery, at 130 +/- 1 days of gestation. There was no difference in plasma epinephrine appearance rate during the fetal (26 +/- 4 ng.kg-1 x min-1) or newborn studies (31 +/- 5 ng.kg-1 x min-1). The fetal plasma epinephrine clearance rate (131 +/- 13 ml.kg-1 x min-1) was significantly higher than newborn plasma epinephrine clearance rate (40 +/- 3 ml.kg-1 x min-1). Thus fetal plasma epinephrine appearance rate is not different from appearance rate in the immediate newborn period when catecholamine levels are higher than during most other physiological circumstances. The increase in circulating catecholamine levels at birth is due in part to a significant decrease in clearance rate. It is likely that removal of the placental contribution to whole body clearance accounts for much of the difference observed in fetal and newborn clearance rates.

Animals↗
PubMed1993

Precursor cells of mouse endocrine pancreas coexpress insulin, glucagon and the neuronal proteins tyrosine hydroxylase and neuropeptide Y, but not pancreatic polypeptide.

The early progenitor cells to the pancreatic islets in the mouse have been characterized so as to re-examine their possible lineage relationships to the four islet cell types found in mature islets. Insulin and glucagon were both first expressed at embryonic day 9.5, and many cells coexpressed these two markers, as shown by light and electron microscopic analysis using double-label immunohistochemistry. Incubation of embryonic pancreas with 1% glutaraldehyde, a fixative commonly used by electron microscopists, abolished this reactivity, thereby explaining reported difficulties in detecting these precursor cells. Using antisera specific for neuropeptide Y (NPY) a peptide with considerable homology to pancreatic polypeptide (PP), we show that NPY first appears with insulin and glucagon immunoreactivity at E9.5, and is co-expressed with glucagon in a majority of adult alpha cells. As we have previously reported, PP itself is first detectable immunocytochemically at postnatal day 1 with PP-specific antibodies. However, antibodies raised against bovine PP are shown by dot blotting to recognize NPY with comparable avidity, indicating that a recent report of islet progenitor cells containing PP at E9.5 (Herrera, P. L., Huarte, J., Sanvito, F., Meda, P., Orci, L. and Vassalli, J. D. (1991) Development 113, 1257-1265), actually represents cross-reactivity to NPY. The data support a model in which early precursor cells to the endocrine pancreas co-activate and co-express a set of islet cell hormone and neural genes, whose expression is both selectively increased and extinguished as development proceeds, concomitant with a restriction to the patterns of expression characteristic of mature islet cell types.

Animals↗
PubMed1993

Radioimmunoassay of mouse vas deferens protein: developmental profile and hormonal regulation.

This study investigated the hormonal regulation of the developmental pattern of a major protein of the mouse vas deferens (MVDP) which represents 10% of the vas deferens protein content. Using a specific radioimmunoassay, MVDP was first detected in 10-day-old males and its concentration increased sharply between 10 and 30 days, reaching adult levels at 40 days. In adult males, MVDP disappeared after castration, and testosterone treatment for 15 days was necessary to reverse the effect of castration completely. In 10-day-old mice castrated at birth, MVDP levels were similar to those measured in controls of the same age. Testosterone administration from 1 to 10 days of age did not induce precocious accumulation of MVDP. These results suggested that the neonatal expression of MVDP is independent of androgens. From 10 to 30 days, the increase in MVDP levels was androgen-dependent as shown by the castration and injection experiments. In males castrated at birth, the androgen-induced accumulation of MVDP was greatly reduced in adulthood. This suggested that neonatal androgens are necessary to obtain full expression of the MVDP gene in adults.

Aging↗
PubMed1992

Effects of disease stage and zidovudine therapy on the detection of human immunodeficiency virus type 1 in semen.

OBJECTIVE: To determine the prevalence and temporal expression of infectious human immunodeficiency virus type 1 (HIV-1) in the semen of HIV-1 seropositive men and to determine whether the detection of HIV-1 in semen is associated with disease stage, zidovudine treatment status, or other clinical factors. DESIGN: A microculture technique was used to detect infectious HIV-1 in semen from a cohort of 95 seropositive men. In addition, semen cultures were performed monthly for at least 6 months for 14 of the men. Information was obtained by interview and extracted from medical records to identify clinical variables associated with HIV-1 in semen. PATIENTS: Sixty HIV-1 seropositive homosexual men participating in clinical studies at the Fenway Community Health Center, Boston, Mass, and 35 HIV seropositive bisexual or heterosexual men participating in the California Partner Study of the University of California, San Francisco. MAIN OUTCOME MEASURES: Semen HIV-1 culture results, seminal leukocyte counts, Centers for Disease Control (CDC) disease stage, peripheral CD4+ cell counts, zidovudine therapy, HIV risk category. RESULTS: In the cross-sectional study, HIV-1 was cultured from the semen of nine (9%) of 95 men. Factors associated with detection of HIV-1 in semen were peripheral CD4+ cell counts of 0.20 x 10(9)/L (200/microL) or less (adjusted odds ratio [OR], 23.33; 95% confidence interval [Cl], 2.89 to 175.63); symptomatic (CDC class IV) disease (adjusted OR, 6.56; 95% Cl, 1.02 to 66.76); and seminal leukocytosis (greater than 1 x 10(9) white blood cells per liter of semen) (adjusted OR, 7.02; 95% Cl, 1.28 to 39.29). Zidovudine therapy was associated with decreased detection of HIV-1 in semen (adjusted OR, 0.04; 95% Cl, 0.00 to 0.63). In the longitudinal study of 14 men who had neither peripheral CD4+ cells counts of 0.20 x 10(9)/L or less nor seminal leukocytosis, seminal HIV-1 was detected in at least one sample from six men (43%). CONCLUSION: HIV-1 is more commonly found in semen from men with advanced HIV-1 infection and seminal leukocytosis but can also be cultured from semen of men with neither of these conditions. Zidovudine therapy may decrease the prevalence and/or titer of seminal HIV-1. However, all HIV-1-infected persons should continue to assume that they are potentially infectious through sexual contact.

CD4-Positive T-Lymphocytes↗