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T Brady

Publications and source records attributed to T Brady.

At least 19 recordsLinked to original sources
PubMed2001

Mechanisms of nitric oxide-induced cytotoxicity in normal human hepatocytes.

Chronic exposure of hepatocytes to reactive nitrogen species (RNS) following liver injury and inflammation leads not only to functional and morphological alterations in the liver but also to degenerative liver diseases and hepatocellular carcinoma. Previously, we showed that S-nitroso-N-acetylpenicillamine-amine (SNAP), which generates nitric oxide, and 3-morpholinosydnonimine (Sin-1), which generates equal molar concentrations of superoxide and nitric oxide resulting in peroxynitrite production, exhibited different levels of cytotoxicity to normal human hepatocytes in culture. The aim of the present study was to elucidate some of the molecular and cellular pathways leading to hepatocyte cell death induced by RNS. Following treatment of the hepatocytes with SNAP or Sin-1, gene-specific DNA damage was measured in mtDNA and a hprt gene fragment using a quantitative Southern blot analysis. Both agents induced dose-dependent increases in DNA damage that was alkaline labile, but not sensitive to both formamidopyrimidine-DNA glycosylase (fpg) and endonuclease III, which recognize 8-oxoguanine, thymine glycol, and other oxidized pyrimidines. DNA damage was two- to fivefold greater in mtDNA than in the hprt gene fragment. There was a persistent and marked increase in DNA damage posttreatment that appeared to arise from the disruption of electron transport in the mitochondria, generating reactive species that saturated the repair system. DNA damage induced by Sin-1 and SNAP led to cell-cycle arrest in the S-phase, growth inhibition, and apoptosis. The data support the hypothesis that the functional and morphological changes observed in liver following chronic exposure to RNS are, in part, the result of persistent mitochondrial and nuclear DNA damage.

Adult↗
PubMed2001

Malignant lymphoepithelial lesion of the parotid gland: a case report and review of the literature.

Malignant lymphoepithelial lesions are rare tumors of the major salivary glands. They most often occur in Asians and Greenland Eskimos and are strongly associated with Epstein-Barr virus infection. We report a case of a malignant lymphoepithelial lesion of the parotid gland that developed in an Italian-American woman whose serology was positive for Epstein-Barr virus antibody. The patient underwent a left total parotidectomy and upper neck dissection, followed by radiation therapy. At the 2-year follow-up, she remained free of disease.

Carcinoma, Squamous Cell↗
PubMed1997

Sensitivity of human hepatocytes in culture to reactive nitrogen intermediates.

The cytotoxic effects of 3-morpholinosydnonimine (Sin-1) and S-nitroso-N-acetylpenicillamine-amine (SNAP) on replicatively active human hepatocyte cells in culture was determined as a function of oxidant type. Both Sin-1 which yields nitric oxide and peroxynitrite following the generation of superoxide anion plus nitric oxide, and SNAP which generates nitric oxide, induced dose dependent decreases in the colony forming capabilities of the human hepatocytes. Sin-1 was much more cytotoxic (LD50 = 400 microM) than SNAP (LD50 = 1250 microM). Comparatively, both compounds were much less cytotoxic than H2O2 (LD50 = 96 microM). Sin-1 induced 4-fold higher levels of cellular nitrite than that generated by the chemical in cell free medium. Nitrotyrosine, a marker of peroxynitrite formation in cells, was immunohistochemically detected in hepatocytes treated with both Sin-1 and SNAP. The formation of 3-nitrotyrosine by hepatocytes incubated with SNAP, suggests that hepatocytes generate intracellular superoxide which reacts with the exogenous nitric oxide derived from SNAP to produce intracellular peroxynitrite, resulting in the SNAP cytotoxicity. The enhanced levels of Sin-1 cytotoxicity on the hepatocytes is suggested to be due both to the chemical generation of peroxynitrite and superoxide anion by Sin-1. These data indicate that peroxynitrite is formed in cultured human hepatocytes inhibiting their replication, and that peroxynitirite may play a significant role in the pathogenesis of liver disease.

Cells, Cultured↗
PubMed1997

Molecular characterization of mutations in the hprt gene of normal human skin keratinocytes treated with N-ethyl-N-nitrosourea: influence of O6-alkylguanine alkyltransferase.

O6-Alkylguanine-DNA alkyltransferase (AGT) is responsible for repairing the O6-alkylguanine lesion in DNA. There is wide variation in the levels of AGT between organ and cell types, which appears to correlate with cell and tissue type sensitivity to the mutagenic and carcinogenic effects of alkylating agents. In order to investigate the role of AGT in modulating the frequency and types of mutations induced in one type of normal human parenchymal cells, we examined the types and frequency of mutations in the hypoxanthine (guanine) phosphoribosyltransferase (hprt gene in 116 mutants derived from two N-ethyl-N-nitrosourea (ENU)-treated normal human skin keratinocyte cell lines. O6-Benzylguanine (O6-BZ; 5 microM x 2 hours) was used to specifically inhibit AGT activity before ENU treatment (0 to 5 mM x 1 hour). O6-BZ increased both the cytotoxic and mutagenic effects of ENU by 1.8- and 3- to 5-fold, respectively. In both treatment groups, most of the mutations were base substitutions (72%). The proportion of GC to AT transitions in the O6-BZ group (14/31) was twice that in the group treated with ENU alone, consistent with the loss of AGT activity in these cells. There was no strand specificity of GC to AT and AT to GC transitions in both groups. Base transversions accounted for 28% of total base substitutions. A lower than expected proportion of AT to TA transversions were observed in both cell lines, which decreased in the O6-BZ pretreated group. A strand bias was observed for GC to TA and AT to TA transversions. Most of the G to A and G to T base substitutions had one or more purines flanking 3' to the mutated deoxyguanosines. There were more deletion mutants with the deletion of exon 1, 4, 6, and 8 in the BZ group than in the control group. These data, characterizing the mutational spectra of ENU in normal human keratinocytes treated in vitro, indicate that GC to AT and AT to GC transition mutations predominate in these cells depleted or not depleted of AGT.

Cell Line↗
PubMed1995

Primary gastric T-cell lymphoma with cutaneous involvement. A case report and review of the literature.

Primary gastric T-cell lymphomas are extremely rare. We report a Ki-1 negative primary gastric T-cell lymphoma of the anaplastic large cell type associated with extensive involvement of the skin, gastrointestinal tract, and other organ involvement in a patient not known to be immunocompromized. Biopsy of the stomach and distal esophagus showed infiltration of gastric mucosa and the squamous epithelium by nests of large atypical cells with vacuolated or clear cytoplasm, consistent with large cell lymphoma. Immunohistochemical staining of these specimens revealed neoplastic cells bearing LCA (CD45) and T-cell markers (UCHL1/CD45R0 and CD3). This represents the only case so far with synchronous presentation of gastric, esophageal, and cutaneous involvement without evidence of regional lymph node involvement. There was no association with HTLV-1 or HIV infection. The patient had a fulminant course and a poor response to chemotherapy.

Aged↗
PubMed1995

Identification and isolation of human epithelial cell colonies that express specific gene products.

A new and simple method for the identification and isolation of human cell clones expressing specific gene products is presented. This technique is analogous to the colony blotting techniques described for prokaryotes. In this technique, human epithelial cells are grown in tissue-culture dishes, and cells from the colonies on the dish are transferred in situ to a high-density cationized quaternary amine-charged nylon membrane. The membrane can then be processed multiple times, using antibody and/or nucleic acid probes, for the identification of those cells producing the desired protein, mRNA or DNA sequence. Once identified, the desired cell colony is isolated for expansion, direct DNA sequencing and/or cell function. We demonstrate the potential of the technique by identifying and isolating colonies of replicating normal human liver hepatocytes producing albumin and keratin.

Albumins↗
PubMed1993

AUR Memorial Award 1993. A drug system (PDH) for interventional radiology. Synthesis, properties, and efficacy.

RATIONALE AND OBJECTIVES: The authors synthesized and tested a novel hydrogel system proposed for use in extra- and intravascular radiologic interventions, such as chemoembolizations and embolizations, and as a vehicle for sustained drug release. MATERIALS: The material was specifically designed to meet the prerequisites of biodegradation, biocompatibility, low immunogenicity, low toxicity, and easy use. The material consists of a protein backbone cross-linked with activated bifunctional polyethyleneglycol (PEG) derivatives (PEG-derivatized hydrogel, [PDH]) to which are attached therapeutic (e.g., doxorubicin, a chemotherapeutic agent = PDH-dx) or diagnostic labels (e.g. Gd-DTPA). RESULTS: PDH-dx effectively reduced the risk of local tumor recurrence in a rat model when implanted locally after surgical tumor removal. After administration, PDH is degraded by proteases release from macrophages; implantations of 1 mL samples into paraspinal muscles of rats were completely absorbed within 4 weeks and its constituents were metabolized. Antibody titers (total Ig response) against the PDH were not detectable 1 week after implantation, whereas protein control substances elicited a strong response. CONCLUSIONS: PDH and its derivatives are relatively nontoxic, biodegradable materials for use in radiologic interventions and as a vehicle for sustained drug release.

Animals↗
PubMed1991

Prostatic urethroplasty with balloon catheter as a nonsurgical alternative for benign prostatic hyperplasia.

Prostatic urethroplasty with a balloon catheter is an easy procedure to perform, but certain guidelines must be followed to avoid complications. This procedure will reduce the overall treatment cost of benign prostatic hyperplasia significantly. Preliminary results range from 70% to 85% symptomatic improvement or resolution of the prostatism symptoms. Its recurrence rate is still not known, but a small one is expected. Nevertheless, because of the noninvasiveness, low cost, and simplicity of the procedure, it potentially could be repeated, if necessary. This procedure is one that when it is done in combination with another specialist, in this case a urologist, the patient will benefit by the use of the expertise of both the urologist's knowledge of the disease of the urinary system and the interventional radiologist's skills with catheters and guide wires.

Catheterization↗
PubMed1990

Spontaneous regression of giant arteriovenous fistulae during the perinatal period. Case report.

A unique case of spontaneous regression of giant arteriovenous fistulae during infancy is described in this report. A female infant, the product of normal labor and delivery, demonstrated severe ventriculomegaly and an intracranial hemorrhage at birth. Cerebral angiography at 5 days of age revealed several large fistulae fed by the anterior and middle cerebral arteries draining into the deep venous system through a dilated internal cerebral vein and ectatic vein of Galen. Two days following the angiogram, a second intracranial hemorrhage occurred. Active hydrocephalus developed over the next 6 months and was treated with ventriculoperitoneal shunting. When the child was 8 months of age, angiography failed to demonstrate the fistulae. It was postulated that pressure effects from the intracranial hematoma and long-standing intracranial hypertension as well as stenosis in the anomalous venous outflow resulted in vascular stasis, venous thrombosis, and selective arterial occlusion. Hydrocephalus was a result of the compression of the intraventricular foramina by dilated embryonic vessels. This anomaly, predominantly involving the anterior circulation, may be homologous to the vein of Galen aneurysm in the posterior circulation.

Arteriovenous Fistula↗
PubMed1988

Successful pregnancy in an ovulating recipient following the transfer of two frozen-thawed embryos obtained from anonymously donated oocytes.

A fertile woman suffering from mild dystrophia myotonica had undergone sterilization because of the 50% genetic risk of this disease developing in her offspring. In her second treatment cycle on the donor oocyte program, four anonymously donated oocytes were inseminated with frozen-thawed sperm of her husband. Three embryos were obtained and two surviving embryos were deep-frozen at the eight-cell stage and kept in storage for 9 months. These embryos were successfully thawed and transferred to the recipient 97 hr after the onset of her luteinizing hormone surge. A normal singleton pregnancy developed and a healthy male infant was delivered by cesarean section at 36 weeks of gestation.

Adult↗
PubMed1988

The effects of cooling human oocytes.

Preovulatory human oocytes were cooled to 0 degrees C at 1 degree C/min, with or without the cryoprotectant dimethyl sulphoxide (DMSO), to assess the effects of cooling on the meiotic spindles and on oocyte structure. Batches of oocytes, cultured for 3-9 h, were held at 0 degrees C for 20 or 60 min and then fixed for transmission electron microscopy (TEM) either at 0 or 8 degrees C. Control oocytes were not cooled and were fixed at 22 or 37 degrees C for comparison. TEM revealed that 80% of the oocytes were at metaphase II, while 20% were at metaphase I and most had resumed meiosis recently. Control oocytes had more or less barrel-shaped meiotic spindles composed of microtubules (MT), some associated with chromosomes at kinetochores. Both metaphase I and II spindles were disassembled when cooled and fixed at 0 degrees C, with or without DMSO, due to extensive depolymerization of MT. The few MT that survived were found at the poles or were bundled together or were associated with chromosomes. Kinetochores were not prominent. Some oocytes cooled with DMSO and fixed at 0 or 8 degrees C showed evidence of MT, but the spindles were still disorganized and were abnormal in structure. Chromosomes tended to clump together or were dislocated in the cortical ooplasm in cooled oocytes, but widespread scattering was not observed. This was particularly evident in the absence of DMSO. Elements of the endoplasmic reticulum, Golgi, mitochondria and the cytosol were also adversely affected in some of the cooled oocytes and their surrounding cumulus cells. The results show that meiotic spindles are very sensitive to simple cooling and that DMSO does not provide substantial stabilization of the meiotic spindle even at 0 degrees C. The findings are discussed with reference to recent work on frozen human and mouse oocytes.

Cold Temperature↗
PubMed1988

Double labeling of SIgG+ cells harboring a lymphotropic herpesvirus by avidin-biotin complex immunoperoxidase and immunogold-silver staining techniques.

By reversing the usual order of double-staining procedures, we obtained optimal conditions for simultaneous detection of guinea pig lymphotropic herpesvirus (GPHLV) and surface immunoglobulin G-positive (SIgG+) cells in paraffin-embedded tissue sections. Of the different fixatives tested, Bouin's solution gave the best preservation of morphology and cell surface IgG. Double immunolabeling was best achieved when avidin-biotin complex immunoperoxidase (ABC-IP) staining was performed first for detection of intracellular viral antigen, followed by immunogold-silver staining (IGSS) for localization of cell surface IgG.

Animals↗
PubMed1987

Size dependent changes in tumor phosphate metabolism after radiation therapy as detected by 31P NMR spectroscopy.

In Vivo 31P NMR spectroscopy was used to study changes in phosphate metabolism that occur after irradiation of the C3H fibrosarcoma, FSaII. Previously, we have shown that small FSaII tumors (less than 250 mm3) have a greater phosphocreatinine/inorganic phosphate (PCr/Pi) ratio and a lower hypoxic cell fraction (HCF) than large FSaII tumors (greater than 250 mm3). Six small tumors (113 +/- 26 mm3) were treated with radiation doses chosen to induce local control in greater than 50% of animals, (70-100 Gy, single fraction). Minimal changes in the tumor 31P NMR spectrum were seen over eight days of monitoring. During this interval, tumor regression began a minimum of 36 hours after radiation. This contrasted with large tumors (650-1000 mm3) wherein a significant increase in the Pcr/Pi ratio was seen 44 hr after irradiation. In tumors of this size range, a tumor growth delay of 4 to 7 days is obtained after a single 70 Gy fraction of radiation. Since small FSaII tumors have a minimal HCF (approximately equal to 4%), radiation induced reoxygenation would not be expected to have a large effect on their average cellular metabolism. Large tumors of this histology have a high HCF (greater than or equal to 40%), and may therefore be expected to have a significant average change in tumor cell metabolism with reoxygenation. The 31P NMR observations of small and large tumors after irradiation are compatible with radiation induced reoxygenation in the larger tumors.

Animals↗
PubMed1987

Chest pain, dyspnea on exertion, and exercise induced asthma in children and adolescents.

UNLABELLED: The contribution of maximal exercise tests to the evaluation of 180 patients with chest pain associated with exercise (n = 147) or dyspnea on exertion (DOE, n = 33) was examined. The ages ranged from 5 to 22 (mean 13.2) years, and 68 patients were females. All patients had a normal cardiovascular examination, electrocardiogram, chest x-ray, and 2D-echocardiogram. Maximal exercise tests were performed on a treadmill or bicycle ergometer, and flow volume loops were performed before and after exercise (n = 65). Exercise tests did not reveal any cardiovascular abnormalities, but 14 patients with chest pain (9.5%) and seven patients with DOE (21.2%) developed exercise-induced asthma. Postexercise decrease in peak expiratory flow rate was 26.2 +/- 3.7 percent in patients with chest pain and 39.4 +/- 8.9 percent in those with DOE. Only five patients had a personal history and four others had a family history of asthma. Seven patients had a personal or family history of allergies. IMPLICATIONS: exercise-induced asthma should be considered in pediatric patients with symptoms of chest pain or dyspnea on exertion; when exercise tests are performed, flow volume loops should be included before and after exercise; maximal exercise tests are unlikely to unmask any cardiovascular abnormalities in such patients.

Adolescent↗