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Biomedical subjects

D Diaz

Publications and source records attributed to D Diaz.

At least 19 recordsLinked to original sources
PubMed2001

Abolished angiogenicity and tumorigenicity of rat glioma by 1-naphthalenemonosulfonate.

Suramins and suradistas, an important group of potential anti-cancer agents, inhibit fibroblast growth factor (FGF) mitogenic activity. It has been shown that naphthalenesulfonates, with a common chemical function to the family of suramins and suradistas, mimic their inhibitory activity, abolishing FGF-induced angiogenesis in vivo, and inducing apoptosis of C6 glioma cells in culture. In the present report, we show that intratumoral administration of 1-naphthalenemonosulfonate induces a considerable regression of gliomas in rats, significantly enhances apoptosis, and attenuates tumor angiogenesis. These findings may lead to new approaches for the treatment of glioblastoma, a most common primary malignant brain tumor of very poor prognosis, as well as of other angiogenesis-dependent malignancies.

Angiogenesis Inhibitors↗
PubMed2001

Merosin-positive congenital muscular dystrophy with mental retardation, microcephaly and central nervous system abnormalities unlinked to the Fukuyama muscular dystrophy and muscular-eye-brain loci: report of three siblings.

Classical merosin (2 laminin)-positive congenital muscular dystrophy is a heterogeneous subgroup of disorders; a few cases characterized by severe mental retardation, brain involvement and no ocular abnormalities were called Fukuyama-like congenital muscular dystrophy. We report a family of healthy non-consanguineous parents, with four affected siblings, of which one died at the age of 7 months due to an intercurrent illness, who presented congenital hypotonia, severe mental retardation, microcephaly, delayed psychomotor development, generalized muscular wasting and weakness with mild facial involvement, calf pseudohypertrophy, joint contractures and areflexia. Muscle biopsy disclosed severe muscular dystrophy. Immunostaining for laminin 2 80 kDa and clone Mer3/22B2 monoclonal antibodies, 1 and 1 chain was preserved. Magnetic resonance imaging findings were consistent with pontocerebellar hypoplasia, bilateral opercular abnormalities and focal cortical dysplasia as well as minute periventricular white matter changes. Clusters of small T2-weighted focal hyperintensities in both cerebellar hemispheres consistent with cysts were observed in two of the three siblings studied with magnetic resonance imaging. Ophthalmologic and cardiologic examination was normal. Haplotype analysis using microsatellite markers excluded the Fukuyama congenital muscular dystrophy, LAMA2 and muscle-eye-brain disease loci. Thus, a wider spectrum of phenotypes, gene defects and protein deficiencies might be involved in congenital muscular dystrophy with brain abnormalities.

Biopsy↗
PubMed2000

Enantiocontrolled synthesis of trialkyl-substituted stereogenic carbons. A general route to cis-3,5-dialkyl gamma-lactones

[reaction: see text] Lewis acid treatment of tertiary Co2(CO)6-propargylic alcohols having a stereochemically defined benzyloxy group at the gamma-benzyl position yielded after cobalt demetalation sec-dialkyl bishomopropargylic alcohols in good yields. The reaction is highly stereoselective and predictable, providing pure stereoisomers. The use of benzyl-alpha,alpha'-d2 ethers permitted the stereoselective d-labeling of methines and methylenes. Very simple chemical manipulations provided a general methodology to obtain the enantiomers of 3,5-dialkyl-gamma-lactones.

Journal Article↗
PubMed2000

A new method for the simultaneous analysis of growth and death of immunophenotypically defined cells in culture.

BACKGROUND: Internal standards have been used in flow cytometry methods to enumerate lymphoid subsets and hemopoietic progenitor cells ex vivo. However, the currently available methods cannot be readily applied to the analysis of cultured cells because of the frequent occurrence of cell death during in vitro assays. METHODS: This paper reports a new method for the enumeration of both viable and nonviable cells in culture. Cells were counted with the aid of an internal reference standard of microbeads, and live versus dead cell discrimination was performed using 7-amino-actinomycin D which allows the double staining of surface antigens. RESULTS: The method is more precise, accurate and sensitive than either conventional light microscopy-based or automated cell counting. Additionally, it may be used to accurately measure the number of apoptotic cells in a culture. RESULTS: Through the enumeration of surviving cells it is demonstrated that, when applied to the study of mitogen-activated T lymphocytes, current flow cytometry techniques (which do not use internal standards) for the study of the viability and apoptosis overestimate the fraction of viable cells and underestimate both the fraction of dead and apoptotic cells. CONCLUSIONS: The new method overcomes these limitations and is of use in the in vitro study of cell growth and apoptosis.

Apoptosis↗
PubMed2000

Sequence and diversity of MHC DQA and DQB genes of the owl monkey Aotus nancymaae.

The New World primate Aotus nancymaae has been recommended by the World Health Organization (WHO) as a model for evaluation of malaria vaccine candidates, given its susceptibility to experimental infection with the human malaria parasites Plasmodium falciparum and Plasmodium vivax. We present here the nucleotide sequences of the complete cDNA of MHC-DQA1 and of the polymorphic exon 2 segments of MHC-DQB1/DQB2. In a group of three nonrelated animals captured in the wild, five alleles of MHC-DQA1 could be identified. They all belong to one lineage, namely Aona-DQA1*27. This lineage has not been described in any other New World monkey species studied. In a group of 19 unrelated animals, 14 Aona-DQB1 alleles could be identified which are grouped into the two lineages Aona-DQB1*22 and Aona-DQB1*23. These lineages have been described previously in the common marmoset and cotton-top tamarin. In addition, two Aona-DQB2 sequences could be identified which are highly similar to HLA-DQB2 sequences. Essential amino acid residues contributing to MHC DQ peptide binding pockets number 1 and 4 are conserved or semi-conserved between HLA-DQ and Aona-DQ molecules, indicating a capacity to bind similar peptide repertoires. These results fully support the use of Aotus monkeys as an animal model for evaluation of future subunit vaccine candidates.

Alleles↗
PubMed1999

Apoptosis of glioma cells induced by the fibroblast growth factor inhibitor 1,3,6-naphthalenetrisulfonate.

Fibroblast growth factors (FGFs) are powerful angiogenic polypeptides that are involved in the autocrine growth stimulation of gliomas. We report here that addition to glioma cell cultures of 1,3,6-naphthalenetrisulfonate (NTS), an inhibitor of the mitogenic activity of FGFs, significantly enhanced apoptosis, as assessed by terminal deoxynucleotidyl transferase (TdT) assay. The pro-apoptotic effect of NTS was time-dependent. These findings suggest that FGF may play a pivotal role in the survival of glioma cells, and support a clinical interest of NTS as a leading compound for the development of new antitumorals.

Animals↗
PubMed1999

The role of glutathione in chronic adaptation to oxidative stress: studies in a normal rat kidney epithelial (NRK52E) cell model of sustained upregulation of glutathione biosynthesis.

Reduced glutathione (GSH) is considered to play a central role in protection of cells from oxidant injury. However, the question remains as to whether sustained elevation of intracellular GSH levels, as compared with the ability to rapidly upregulate GSH synthesis, is more important with respect to protection of cell constituents from oxidative stress. To address this question, we conducted studies to evaluate the direct influence of chronically increased endogenous GSH content on chemically induced intracellular free radical formation and oxidative stress using a kidney epithelial cell model adapted to sustain intracellular GSH concentrations in excess of eightfold that observed in unadapted parent kidney cells. Elevated GSH levels in adapted cells were found to be attributable, at least in part, to coordinately increased amounts of both the regulatory and catalytic subunits of gamma-glutamylcysteine synthetase (GCS), the rate-limiting enzyme in GSH synthesis. Studies using electron spin resonance (ESR) spectroscopy and scanning laser cytometry demonstrated that cells having sustained elevation of GSH levels did not attenuate free radical formation and associated oxidative stress compared with parent cells when treated with the prooxidant chemicals, menadione or potassium dichromate. In contrast, nonadapted kidney parent cells treated 18 h after initial prooxidant challenge displayed significantly attenuated free radical signals. Additionally, cells adapted to sustain excess GSH were somewhat more sensitive than parent cells in terms of resistance to prooxidant (chromate) toxicity, as determined by cell viability assays. These findings suggest that the capacity of cells to rapidly upregulate GSH synthesis, rather the ability to chronically sustain elevated intracellular GSH levels, may play a more important role in terms of protection from cytotoxicity associated with prooxidant chemical exposures.

Adaptation, Physiological↗
PubMed1999

Induction of glutamate-cysteine ligase (gamma-glutamylcysteine synthetase) in the brains of adult female mice subchronically exposed to methylmercury.

Methylmercury (MeHg) is widely known for its potent neurotoxic properties. One proposed mechanism of action of MeHg relates to its high affinity for sulfhydryl groups, especially those found on glutathione (GSH) and proteins. Previous studies have shown that acute MeHg exposure results in an increase in the mRNA for the rate-limiting enzyme in GSH synthesis, glutamate-cysteine ligase (GLCL) (also known as gamma-glutamylcysteine synthetase). In this study, we evaluated the effects of subchronic (12-week) MeHg exposure at 0, 3 or 10 ppm in the drinking water on GSH levels, GLCL catalytic (GLCLC) and regulatory subunit mRNA and protein levels, and GLCL activity in brain, liver and kidney tissue of C57B1/6 female mice. Contrary to previous findings in rats, there were no changes in GSH concentration in any of the tissues examined. However, there was an increase in GLCLC protein in the brain, which was accompanied by a 30% increase in GLCL activity. We conclude that up-regulation of GSH synthetic capacity in the brains of mice is a sensitive biomarker of subchronic MeHg exposure.

Animals↗
PubMed1999

Glutathione redox potential in response to differentiation and enzyme inducers.

The reduced glutathione (GSH)/oxidized glutathione (GSSG) redox state is thought to function in signaling of detoxification gene expression, but also appears to be tightly regulated in cells under normal conditions. Thus it is not clear that the magnitude of change in response to physiologic stimuli is sufficient for a role in redox signaling under nontoxicologic conditions. The purpose of this study was to determine the change in 2GSH/GSSG redox during signaling of differentiation and increased detoxification enzyme activity in HT29 cells. We measured GSH, GSSG, cell volume, and cell pH, and we used the Nernst equation to determine the changes in redox potential Eh of the 2GSH/GSSG pool in response to the differentiating agent, sodium butyrate, and the detoxification enzyme inducer, benzyl isothiocyanate. Sodium butyrate caused a 60-mV oxidation (from -260 to -200 mV), an oxidation sufficient for a 100-fold change in protein dithiols:disulfide ratio. Benzyl isothiocyanate caused a 16-mV oxidation in control cells but a 40-mV oxidation (to -160 mV) in differentiated cells. Changes in GSH and mRNA for glutamate:cysteine ligase did not correlate with Eh; however, correlations were seen between Eh and glutathione S-transferase (GST) and nicotinamide adenine dinucleotide phosphate (NADPH):quinone reductase activities (N:QR). These results show that 2GSH/GSSG redox changes in response to physiologic stimuli such as differentiation and enzyme inducers are of a sufficient magnitude to control the activity of redox-sensitive proteins. This suggests that physiologic modulation of the 2GSH/GSSG redox poise could provide a fundamental parameter for the control of cell phenotype.

Adenocarcinoma↗
PubMed1999

Abnormal functional behavior of peripheral blood mononuclear cells from Hashimoto's disease patients. Immunomodulatory effects of cyclosporin A.

In vitro studies of activation and proliferation induced by mitogens in the presence of Cyclosporin A (CsA) and or cytokines were carried out to determine the effects of CsA and cytokines on mitogen activated peripheral blood mononuclear cells (PBMC) from thirteen Hashimoto's disease patients (HP) and ten healthy controls. The proliferative response (PR) of PBMC from HP to mitogens at 7 days of culture was higher than in controls. Interleukin 2 (IL-2) addition significantly increased the PR in phytohemagglutinin-stimulated PBMC from HP, but not in controls. CsA inhibited in a dose dependent manner the PR, as well as the expression of activation antigens induced by mitogens in both groups of subjects, but PBMC from HP were sensitive to CsA at lower doses than those that were effective on PBMC from controls. Both IL-2 or IL-4 overcame the inhibitory effect of CsA on PBMC from HP and controls. Conversely, IL-10 or IFN-alpha addition increases the inhibitory effect of CsA on the PR of PBMC from both HP and controls. We conclude that PBMC from Hashimoto's disease patients shown an abnormal pattern of PR that is associated to increased PR to mitogens and higher sensitivity to immunomodulatory effects of IL-2 and CsA.

Adjuvants, Immunologic↗
PubMed1999

Effect of dietary inducer dimethylfumarate on glutathione in cultured human retinal pigment epithelial cells.

PURPOSE: To determine the effect of dimethylfumarate (DMF), an inducer of glutathione (GSH)-dependent detoxification, on intracellular GSH levels in cultured human retinal pigment epithelium (hRPE) cells, its mechanism of action, and its effect on hRPE cells subjected to oxidative injury. METHODS: Established hRPE cell lines were treated with DMF and assayed by high-pressure liquid chromatography for intracellular and extracellular GSH levels. Quantification of gamma-glutamylcysteine synthetase (GLCL) was determined through northern and western blot analyses, and activity was measured. Effects of pretreatment with DMF on GSH redox status of hRPE cells was determined. Sensitivity of hRPE cells to oxidative stress was determined using tert-butylhydroperoxide as the oxidative agent. RESULTS: Dimethylfumarate caused a transient decrease followed by a significant increase in intracellular GSH. Glutathione increased maximally at 24 hours with 100 to 200 microM DMF. The initial decrease could be accounted for by the formation of a DMF-GSH conjugate. Dimethylfumarate treatment increased the steady state mRNA expression of the regulatory subunit of GLCL, but no increase was seen for the catalytic subunit. However, protein levels were increased for both, and the catalytic activity of GLCL was also increased. Whereas the initial decrease in GSH made hRPE cells more susceptible to oxidative damage, pretreatment with DMF under conditions that increased intracellular GSH protected hRPE cells against oxidative damage. CONCLUSIONS: These results suggest a means by which the antioxidant capability of hRPE may be augmented without direct antioxidant supplementation. Specifically, a dietary compound that conjugates with GSH can induce GSH synthesis, increase GSH concentration, and improve protection by GSH-dependent detoxification pathways in hRPE. However, the early depletion of GSH before stimulated synthesis necessitates caution in prevention strategies using dietary inducers.

Aminoacyltransferases↗
PubMed1998

Reduced amide pseudopeptide analogues of a malaria peptide possess secondary structural elements responsible for induction of functional antibodies which react with native proteins expressed in Plasmodium falciparum erythrocyte stages.

A psi[CH2NH] isoster bond was introduced by replacing one peptide bond at a time within the 1513 malaria peptide KEKMV motif to obtain a set of five pseudopeptides. The motif belongs to a Plasmodium falciparum malarial peptide coded 1513, derived from the MSP-1 protein. This high-binding motif included in the 1513 peptide is involved in the attachment of the malarial parasite to human erythrocytes. The novel malaria 1513 psi[CH2NH] surrogates were analyzed using RP-HPLC and MALDI-TOF mass spectrometry techniques. Nuclear magnetic resonance experiments allowed definition of the five pseudopeptide analogues' secondary structural features. Such structures are present in only a very few molecules in the 1513 parent peptide. A molecular model demonstrating the solution of the three-dimensional structure of the 1 513 peptide Pse-437 analogue was constructed on the basis of 1H-NMR spectral parameters. Monoclonal antibodies were generated to the five 1513 malaria peptide pseudopeptide analogues. These antibodies not only recognize the native MSP-1 (195 kDa) and its 83 kDa and 42 kDa proteolytic processing proteins but also different SPf(66)n malaria vaccine batches containing the native sequence. In addition, the mAbs were able to modify the kinetics of Plasmodium falciparum parasites' intraerythrocytic development and their ability to invade new RBCs. The presented evidence suggests that peptide bond-modified peptides could reproduce a transient state in 1513's native sequence and represent useful candidates in the development of a second generation of effective malarial vaccines.

Amides↗
PubMed1997

A quantitative assessment of standard vs. customized midline shield construction for invasive cervical carcinoma.

PURPOSE: An individualized midline shield (MLS) has been advocated for delivering homogeneous radiotherapy for patients with invasive cervical carcinoma. Yet, many radiation oncologists continue to employ a standard block. In the latter instance, any deviation of the cranial-caudal central axis of he tandem from the patient's midline could result in dose inhomogeneity to tumor. A retrospective review of a single university medical center's experience with constructing the MLS was initiated to determine the outcome of using a standard block vs. a customized block that conforms to the "Point A" isodose line. In addition, participating radiation oncologists associated with the Gynecologic Oncology Group (GOG) were polled to assess if there exists a consensus regarding midline block utilization in the management of cervical cancer patients which could be compared to the institutional study. METHODS AND MATERIALS: From January 1, 1990 through December 31, 1992, 32 patients with invasive cervical carcinoma who underwent low dose rate brachytherapy at a single institution were identified. Patients were grouped as having a standard block (18 cases), customized block (5 cases), or no block (9 cases). The "Point A" isodose distribution from the implant was superimposed onto the whole pelvic simulation film and quantitatively compared to the actual or a hypothetical standard block outlined on the same radiograph. In September of 1995, 56 member and affiliated institutions in the GOG were surveyed concerning their use of a MLS, and the results were tabulated in December of 1995. RESULTS: Approximately 72% of all cases (23 out of 32) at the single institution had tandem deviation ranging from 0-230 with a median of 50. This translated into a median percent overdosage to "Point A" Right of 15% and "Point A" Left of 12.5%. Although overall survival and incidence of chronic complications have not been affected by type of shielding, patient follow-up is limited with a median of 17.7 months (range: 4.2-58.9 months). Of the 56 surveyed radiation facilities in the GOG, 34 (61%) responded. One center was subsequently excluded as it performs only high dose rate brachytherapy. Of the evaluable respondents, 88% (29 out of 33) utilize a MLS in treating their patients with invasive cervical carcinoma. Of the latter group, 76% (22 out of 29), 21% (6 out of 29), and 3% (1 out of 29) employ a standard block, customized block, and a "step-wedge," respectively. For those using a standard block, 77% (17 out of 22) align the central cranial-caudal axis of the MLS along the corresponding midplane of the patient's pelvis on an anteroposterior radiograph rather than along the superior-inferior central axis of the tandem. CONCLUSIONS: This study suggests that the use of a standard midline shield could result in potential tumor dose inhomogeneity and should be avoided. A national survey of major academic centers further suggests that the majority of these facilities also utilize a rectangular central block that is not positioned with respect to possible tandem deviation. Further investigation concerning the techniques of midline shield construction should be considered.

Adult↗
PubMed1997

Diagnostic and therapeutic aspects of endoscopic retrograde cholangiography in papillomatosis of the bile ducts: analysis of five cases.

BACKGROUND: Biliary papillomatosis is an uncommon disease, the definitive diagnosis and treatment of which generally require surgery. In the present study, we described the diagnostic and therapeutic aspects of endoscopic retrograde cholangiography in five such patients. METHODS: Since 1982, five patients with biliary papillomatosis have been admitted to our unit. All these patients underwent endoscopic retrograde cholangiography. RESULTS: Endoscopic examination of the ampulla of Vater showed a dilated papillary orifice with mucin discharge in all five patients. Biliary papillomatosis was diagnosed from the following features: multiple filling defects in the lumen of the biliary system in four patients and several supple stenoses in one patient. Histologic examination of biliary specimens taken after endoscopic sphincterotomy showed typical lesions of papillomatosis in the five patients. Palliative endoscopic treatment was performed in three patients. CONCLUSION: This case series reports the typical endoscopic retrograde cholangiography and endoscopic biopsy findings in biliary papillomatosis. For inoperable patients, endoscopic palliative evacuation of mucus and debris and/or stent placement are of benefit.

Adenocarcinoma↗
PubMed1997

Group A streptococcal bacteremia. A 10-year prospective study.

In this paper we present a prospective evaluation of 100 patients with Group A Streptococcal (GAS) bacteremia evaluated in our hospital over a 10-year period. Sixty-two patients were intravenous drug users (IVDU); all but 1 of these had an obvious cutaneous portal of entry related to the injection of illicit drugs. Twenty-seven patients had infectious metastasis, and the presence of septic pulmonary embolism was associated with suppurative phlebitis. Four of these patients had endocarditis. In the non-IVDU group, 24 patients had an underlying disease, and 12 were immunosuppressed. In 14 cases the infection was of hospital acquisition; in 35% infection was related to medical manipulations. Comparing the IVDU and non-IVDU groups, GAS bacteremia in IVDU patients is associated with a more benign outcome, a longer time of evolution before diagnosis, and a lower frequency of septic shock and mortality than in non-IVDU patients. Although in the univariate analysis GAS bacteremia was associated with several variables, in the multivariate analysis only the presence of shock and nosocomial acquisition of the infection were independently associated with a fatal outcome. Fifty-two patients were infected with human immunodeficiency virus (HIV); 5 of these were in the non-IVDU group. During the last 5 years of study, GAS bacteremia in our hospital was 39 times more frequent in HIV-infected patients than in patients without HIV. Nine patients presented clinical criteria corresponding to Streptococcal toxic shock syndrome (STSS), although its incidence was lower in the IVDU group. In the non-IVDU group, STSS was more frequent in patients with a necrotizing portal of entry, an age between 20 and 40 years, women, and when the origin of the infection was the skin or soft tissue. Six patients with STSS died, and death was associated with the presence of necrotizing lesions and lower counts of white cells, platelets, or hemoglobin.

Adolescent↗
PubMed1996

Analysis of the blood-retinal barrier: its relation to clinical and metabolic factors and progression to retinopathy in juvenile diabetics. A 4-year follow-up study.

BACKGROUND: The study was carried out to evaluate the correlation between blood-retinal barrier (BRB) permeability and the development of diabetic retinopathy (DR) and to assess the metabolic and clinical factors related to DR over a 4-year period by means of vitreous fluorophotometry (VF). METHODS: Thirty-five type I diabetics with no retinopathy, age 7-21 years (mean 14.32 +/- 2.1 years) were enrolled in this longitudinal study. Two visits included standard ophthalmological examination, fluorescein angiography and VF were performed, on entry into the study and 4 years later. The following risk factors in DR were analyzed: age, duration of diabetes, blood pressure, cholesterol, triglycerides, fasting blood glucose levels, glycosylated hemoglobin (HbA1c), insulin dose/kg body weight (IDBW), fructosamine and albuminuria. To estimate the BRB permeability we adopted the vitreous penetration ratio transmittance (VPRt) value. RESULTS: At 4-year follow-up the mean VPRt had significantly increased. During that time 13 patients developed DR and their final mean VPRt was significantly higher than that in non-DR patients. Additionally, the initial mean VPRt was higher but not significantly so, in patients that later developed DR than in non-DR subjects. A constant linear correlation was found between VPRt and duration of diabetes, HbA1c and microalbuminuria. CONCLUSION: VF is a quantitative method that could measure and predict the breakdown of the BRB before angiographic retinopathy in type I diabetics. The major clinical and metabolic factors related to alterations in the BRB are duration of diabetes, HbA1c and microalbuminuria.

Adolescent↗