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J F Ward

Publications and source records attributed to J F Ward.

At least 37 records · Page 2Linked to original sources
PubMed1999

Yield of DNA strand breaks after base oxidation of plasmid DNA.

We have irradiated aerobic aqueous solutions of plasmid DNA with 137Cs gamma rays in the presence of inorganic radical scavengers including nitrite, iodide, azide, thiocyanate and bromide. These scavengers react with the strongly oxidizing hydroxyl radical (*OH) to produce less powerful oxidants. Of these scavengers, only thiocyanate and bromide result in the formation of oxidizing species [(SCN)2*- and Br2*-, respectively] which are capable of reacting with the bases in DNA. The oxidized bases were detected after incubation of the irradiated plasmid with the two E. coli DNA base excision repair endonucleases, formamidopyrimidine-DNA N-glycosylase and endonuclease III. Depending on the experimental conditions, the intermediate base radicals may ultimately form stable oxidized bases in very high yields (within an order of magnitude of the *OH yield), and possibly also single-strand breaks (SSBs) in much lower yield (between 0.1 and 1% of the total yield of base damage). By competing for (SCN)2*- with an additional species (nitrite), it was possible to estimate the second-order rate constant for the reaction of (SCN)2*- with DNA as 1.6 x 10(4) dm3 mol(-1) s(-1), and also to demonstrate a correlation between the large yield of damaged bases and the much smaller increase in the yield of SSBs over background levels due to *OH. The efficiency of transfer of damage from oxidized base to sugar is estimated as about 0.5% or 5%, depending on whether purine or pyrimidine base radicals are responsible for the base to sugar damage transfer.

DNA Damage↗
PubMed1999

Critical target and dose and dose-rate responses for the induction of chromosomal instability by ionizing radiation.

To investigate the critical target, dose response and dose-rate response for the induction of chromosomal instability by ionizing radiation, bromodeoxyuridine (BrdU)-substituted and unsubstituted GM10115 cells were exposed to a range of doses (0.1-10 Gy) and different dose rates (0.092-17.45 Gy min(-1)). The status of chromosomal stability was determined by fluorescence in situ hybridization approximately 20 generations after irradiation in clonal populations derived from single progenitor cells surviving acute exposure. Overall, nearly 700 individual clones representing over 140,000 metaphases were analyzed. In cells unsubstituted with BrdU, a dose response was found, where the probability of observing delayed chromosomal instability in any given clone was 3% per gray of X rays. For cells substituted with 25-66% BrdU, however, a dose response was observed only at low doses (<1.0 Gy); at higher doses (>1.0 Gy), the incidence of chromosomal instability leveled off. There was an increase in the frequency and complexity of chromosomal instability per unit dose compared to cells unsubstituted with BrdU. The frequency of chromosomal instability appeared to saturate around approximately 30%, an effect which occurred at much lower doses in the presence of BrdU. Changing the gamma-ray dose rate by a factor of 190 (0.092 to 17.45 Gy min(-1)) produced no significant differences in the frequency of chromosomal instability. The enhancement of chromosomal instability promoted by the presence of the BrdU argues that DNA comprises at least one of the critical targets important for the induction of this end point of genomic instability.

Animals↗
PubMed1999

Immediate and postoperative complications of transurethral prostatectomy in the 1990s.

PURPOSE: We compare the morbidity, mortality, hospitalization and urethral catheter time of contemporary transurethral prostatectomy to historical series, and evaluate recent trends in hospitalization and urethral catheter time during the last 8 years. MATERIALS AND METHODS: A retrospective chart review of 520 consecutive patients who underwent transurethral prostatectomy between 1991 and 1998 at a single institution for symptomatic benign prostatic hyperplasia was performed. Inpatient and outpatient charts, clinic records, operative reports and discharge summaries were reviewed. For each patient 43 data points were collected. Telephone followup was performed when data were lacking. All retrieved data were compiled in a computer database. Perioperative and late postoperative morbidity and mortality, hospitalization and urethral catheter time were analyzed. RESULTS: A total of 520 patients were identified with an average age of 67 years (range 44 to 89). Significant co-morbidity (2 or more co-morbid disease processes) was identified preoperatively in 30.3% of the patients. The most common indications for transurethral prostatectomy were lower urinary tract symptoms (80.9%) and urinary retention (15.2%). Average preoperative International Prostate Symptom Score was 23.8. Average weight of resected tissue was 18.8 gm. There was no perioperative patient mortality. Blood transfusion rate was 0.4%. The rate of intraoperative and immediate postoperative complications was 2.5% and 10.8%, respectively. Average hospital stay was 2.4 days, and 1.1 from 1997 through 1998. The rate of late postoperative complication was 8.5% and the average postoperative symptom score was 6.4 with an average followup of 42 months (range 6 to 84). CONCLUSIONS: Contemporary perioperative and postoperative complications of transurethral prostatectomy are significantly lower than rates in historical series. The average hospital stay and urethral catheter time have steadily decreased during the last 8 years.

Adult↗
PubMed1998

Induction of chromosome aberrations and delayed genomic instability by photochemical processes.

Exponentially growing cells cultured in medium containing bromodeoxyuridine, then exposed to UVA light in the presence of the dye Hoechst 33258, show significant levels of DNA strand breaks and base damage. This dye-bromodeoxyuridine-UVA photolysis treatment is markedly cytotoxic. We now demonstrate that exposure of cells to the agents used in photolysis leads directly to the formation of chromosome aberrations. Furthermore, we demonstrate that this photochemical treatment induces delayed chromosomal instability in clonal populations derived from single progenitor cells surviving photolysis. These results suggest that photolysis-induced DNA damage leads to chromosome rearrangements that could account for the observed cytotoxicity. Furthermore, in those cells surviving photolysis, the delayed effects of this treatment can be observed several generations after exposure and are manifested as compromised genomic integrity.

Animals↗
PubMed1998

The limits to radioprotection of Chinese hamster V79 cells by WR-1065 under aerobic conditions.

Clonogenic survival and drug content for Chinese hamster V79-171 cells incubated in suspension with WR-1065 prior to gamma irradiation have been determined. Factors that might influence the radioprotection by WR-1065 were investigated in control studies. Intracellular drug levels studied ranged between 0-36 nmol per 10(6) cells. In control studies, it was established that extracellular drug toxicity was not significant for cells in suspension at 10(6) per milliliter over short periods but was important when residual drug was present above 2 microM in the final plating of cells. Accumulation of intracellular drug above 30 nmol per 10(6) cells produced significant cytotoxicity in unirradiated cells. Irradiation with doses as high as 150 Gy produced no significant change in the total drug level or the thiol/disulfide ratio, either for the drug in the cells or for the drug in the medium. Preirradiation with 8 Gy did not change the ability of cells to import the drug but did appear to increase the cytotoxicity of the intracellular drug at levels above 25 nmol per 10(6) cells. There was no qualitative difference in the ability of WR-1065 to protect viable cells preirradiated with 8 Gy compared with protection of unirradiated cells. For a given gamma-ray dose from 2 to 40 Gy, there is a limiting value for surviving fraction which cannot be increased by further elevation of the intracellular drug level in V79-171 cells. Such limiting radioprotection was demonstrated for HT-29/SP-ld, HeLa, Me-180-VCII and OV-2008-VI human tumor cells.

Aerobiosis↗
PubMed1998

Refined microscopic urinalysis for red blood cell morphology in the evaluation of asymptomatic microscopic hematuria in a pediatric population.

PURPOSE: The use of refined microscopic urinalysis for the presence of dysmorphic red blood cells (RBCs) has been evaluated in children and adults with a known source of hematuria. We examined the clinical usefulness of this study in a pediatric population with an unknown source of hematuria. MATERIALS AND METHODS: Children 12 years old or younger referred for evaluation of asymptomatic microscopic hematuria exhibiting 4 or more RBCs per high power field were enrolled in this study. Patients provided a first morning urine sample subjected to refined urinalysis for RBC morphology. Standard evaluation of patients was performed until a final diagnosis of the hematuria source was identified. RESULTS: A total of 44 patients completed the study. Refined urinalysis revealed pure dysmorphic RBCs in 22 patients, pure isomorphic RBCs in 8 and mixed isomorphic/dysmorphic RBCs in 14. The presence of dysmorphic RBCs correctly predicted a glomerulotubular source of hematuria in 29 of 36 patients (sensitivity 83%, specificity 81%), while the presence of isomorphic RBCs predicted a uroepithelial source of hematuria in 2 of 8 patients (sensitivity 25%, specificity 22%). Hematuria and 2+ proteinuria (100 mg./dl.) were more sensitive (100%) and specific (83%) than the presence of dysmorphic RBCs in predicting glomerulotubular hematuria. CONCLUSIONS: We believe that this is a costly test offering little additional information to the evaluation of microscopic hematuria in children. A thoughtful history and physical examination with microscopic urinalysis and dipstick for proteinuria provide an equal amount of diagnostic information. We do not recommend its routine use in the evaluation of microscopic hematuria in children.

Child↗
PubMed1998

Children and adolescents with diabetes mellitus.

Nurse practitioners play a vital role in the care of children and adolescents who live with diabetes mellitus. Because of their expertise in combining patient education with patient care, nurse practitioners can provide excellent care both in the primary care setting or as part of a multidisciplinary team. This article is focused on nurse practitioners in the primary care setting and provides up-to-date information on the basics of diabetes care. It provides readers with the many aspects of diabetes care including insulin, blood glucose monitoring, and nutrition.

Adolescent↗
PubMed1997

Protease inhibitor-induced urolithiasis.

OBJECTIVES: To describe protease inhibitor-induced urinary stone disease in patients with human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) who are taking indinavir sulfate (Crixivan), a protease inhibitor, for the treatment of AIDS. METHODS: Patients with HIV/AIDS and symptomatic renal colic temporally related to the initiation of indinavir sulfate therapy were prospectively identified. Seven patients (mean age 42 years; all men) with HIV and renal colic who were taking indinavir were identified. Retrospective chart reviews and patient interviews were performed. RESULTS: Indinavir therapy averaged 5.7 months prior to presentation with renal colic. All patients had microscopic hematuria. One patient presented with acute azotemia from bilateral urinary obstruction. Six patients had no history of urinary stones prior to initiating indinavir. The median number of symptomatic urinary stone episodes after initiating indinavir was two stones per patient. All patients had moderate- to high-grade urinary obstruction from radiolucent calculi. Abdominal computed tomography (CT) demonstrated hydronephrosis without urinary calcifications. Three patients spontaneously passed stones and 4 required intervention. Yellow debris and/or brown matrix-like material was seen endoscopically. Stone analysis revealed pure protease inhibitor. Six patients (86%) eventually discontinued protease inhibitor therapy. CONCLUSIONS: Protease inhibitor-induced urinary stones are radiolucent and can cause high-grade ureteral obstruction. Protease inhibitor-induced urinary stones were not identified on unenhanced abdominal CT scans. The radiolucent gelatinous nature of such stones makes lithotripsy a poor choice of treatment. Ureteral stenting may allow spontaneous stone passage if symptomatic obstruction occurs. Urologists may encounter a greater number of patients with symptomatic protease inhibitor-induced urinary calculi as these medications become more popular.

Adult↗
PubMed1997

Photochemical production of uracil quantified in bromodeoxyuridine-substituted SV40 DNA by uracil DNA glycosylase and a lysyl-tyrosyl-lysine tripeptide.

Exposure to UVA radiation of SV40 DNA substituted with bromodeoxyuridine (BrdU) in the presence of Hoechst dye 33258 results in the production of uracil. The yield of uracil was determined by measuring the increase in the single-strand break (SSB) yield after incubation of the photolyzed DNA with uracil-DNA glycosylase (UDG) in the presence of the tripeptide lysyl-tyrosyl-lysine (KYK). UDG removes uracil to leave an abasic site which is then cleaved to a SSB by KYK. The SSB yield was quantified by digital video imaging of ethidium fluorescence after separation of the I, II and III forms of SV40 DNA by agarose gel electrophoresis. Uracil is not detected when photolysis is carried out in the absence of the dye nor when unsubstituted DNA is used as the substrate. Without UDG or KYK treatment, the F0 for the loss of form I DNA is 100 J/m2. This falls to 13 J/m2 after incubation with UDG and KYK, indicating that uracil formation is approximately 5-fold more efficient than SSB formation. Formation of uracil suggests a mechanism for the high cellular toxicity of the dye-BrdU-UVA treatment.

Bromodeoxyuridine↗
PubMed1997

Effect of polyamine-induced compaction and aggregation of DNA on the formation of radiation-induced strand breaks: quantitative models for cellular radiation damage.

The yield of DNA single-strand breaks, G(SSB), upon gamma irradiation of SV40 DNA and SV40 minichromosomes in aqueous solution under aerobic conditions was determined at physiological ionic strength in the presence of various potential radioprotective agents. Putrescine (PUT), spermidine (SPD), glutathione, trans-4,5-dihydroxy-1,2-dithiane, 2-mercaptoethyl disulfide and cystamine, all at 0.1-10 mM, spermine (SPM, 0.1-1 mM) and WR-33278 (WRSSWR, 0.1-2 mM) lowered G(SSB) of SV40 DNA. These results were expected from the ability of these agents to scavenge OH radical in the bulk solution. However, SPD, above 10 mM, and SPM and WRSSWR, each above 2 mM, produced dramatic radioprotection attributed to polyamine-induced compaction and aggregation of the DNA (PICA effect). The DNA of SV40 minichromosomes was inherently less radiosensitive and was subject to a PICA effect at lower polyamine concentrations, i.e. approximately 5 mM SPD, approximately 0.6 mM SPM and approximately 0.5 mM WRSSWR. The PICA effect decreased G(SSB) for SV40 DNA and minichromosomes by one to two orders of magnitude, depending upon the scavenging capacity of the medium. The final yields were similar for SV40 DNA and minichromosomes and were comparable to the corresponding yield determined for cells. Results for the yield of double-strand breaks indicated that the yield of double-strand breaks, G(DSB), for DNA and minichromosomes is subject to a PICA effect by SPM and SPD comparable to that measured for G(SSB). Values of G(SSB) for SV40 DNA and minichromosomes subjected to the PICA effect were well approximated by calculations based upon a 30-nm cylinder assumed to model their condensed states. The results indicate that a major fraction of the formation of SSBs in condensed DNA and minichromosomes results from nonscavengeable radical intermediates. Minichromosomes subjected to the PICA effect of 2 mM SPM were protected against formation of radiation-induced SSBs 1.5-fold by 20 mM DTT but 5-fold by 10 mM DTT plus 10 mM WR-1065 relative to 2 mM SPM alone. Thus WR-1065 is capable of providing marked protection of compacted and aggregated minichromosomes, a protection ascribed to the chemical repair of DNA radicals by WR-1065.

Cystamine↗
PubMed1997

Effect of hydroxyl radical scavenging capacity on clustering of DNA damage.

We have shown previously that the thiol N-(2'-mercaptoethyl)-1,3-diaminopropane (WR-1065) can attenuate the formation of strand breaks associated with ionizing radiation. The mechanism of this protection is predominantly the reduction of DNA radical species which otherwise would attenuate the chemical repair of DNA radical species which are strand break precursors. We had observed that the presence of a hydroxyl radical scavenger during irradiation resulted in a decrease in the ability of WR-1065 to attenuate the formation of strand breaks. Since ionic compounds are known to affect the binding of the dicationic WR-1065 with the polyanion DNA, the effect of the scavenger was initially attributed to its polar nature having a similar effect on the interaction of WR-1065 with DNA, and not as a consequence of its ability to scavenge hydroxyl radicals. After examining additional scavengers, we now conclude that an increased hydroxyl radical scavenging capacity does attenuate the repair of strand break precursors to some extent. The probable explanation for this observation is that an increased scavenging capacity results in a greater degree of radical clustering on the DNA, and that these clusters of multiple radicals are repaired more slowly than are single radical species.

DNA Damage↗
PubMed1996

Malignant cytological washings from radical prostatectomy specimens: a possible mechanism for local recurrence of prostate cancer following surgical treatment of organ confined disease.

PURPOSE: Local recurrence of prostate cancer following complete and successful resection of organ confined disease has been variably reported in men. We hypothesized that observed secretions from the cut distal urethra during radical prostatectomy may contain malignant prostatic epithelial cells and contribute to this problem. MATERIALS AND METHODS: A prospective study was done of prostate cytology specimens from 50 consecutive men with clinically organ confined adenocarcinoma of the prostate undergoing radical retropubic or radical perineal prostatectomy. Direct cytological evaluation by 1 examiner was used to identify malignant or benign cells in these washings. RESULTS: Of 33 radical perineal and 17 radical retropubic prostatectomy specimens organ confinement was confirmed in 58%. Malignant prostatic epithelial cells were observed in 24% of all cytology specimens. Of cytological washings from prostates with pathologically confirmed organ confined cancers 17% showed malignant cells. While perineural invasion was noted in a majority of tumors with positive washings, only Gleason grade was a statistically significant predictor of recurrence (p = 0.009). Surgical approach did not alter the rate of positive cytology. CONCLUSIONS: Malignant prostatic epithelial cells can be identified in the prostatic washings from men with pathologically organ confined prostate cancer. Surgical approach did not change the cytological findings. Gleason grade is a statistically significant predictor of cytological malignancy. These cells may represent a mechanism of failure following successful radical prostatectomy.

Adenocarcinoma↗
PubMed1996

Physiological response of the European hedgehog to predator and nonpredator odour.

A respiratory chamber was used to investigate physiological responses of hedgehogs to predator and nonpredator odour cues, introduced by passing air through different faecal suspensions. Five recently caught hedgehogs showed a significant increase in oxygen consumption (29% +/- 18% at 95% c.i.) when treated with badger (predator) faecal suspension, and 10 hedgehogs held in captivity for ca. 2 years showed no significant response. The responses of recently caught hedgehogs to odour from badger (predator) and roe deer (non-predator) faecal suspensions were then investigated, over a range of concentrations spanning 3 orders of magnitude. Five hedgehogs were tested with badger odour; of these, 3 were also tested with roe deer odour. The mean rise in oxygen consumption was significantly greater in response to badger than to roe deer faecal suspension, but there was no significant variation in strength of response over the range of concentrations tested, and increased oxygen consumption was not associated with any increase in levels of visible activity. The responses are interpreted as an increase in arousal in response to a potential predatory threat. Lack of response in the captive-held animals raises questions about the welfare of such animals following release. Energy costs and foraging inefficiency associated with arousal may be significant factors of foraging decisions involving predation risk, but more naturalistic measurements would be required for any quantitative analysis.

Animals↗
PubMed1996

The difference that linear energy transfer makes to precursors of DNA strand breaks.

Using agarose gel electrophoresis, we have measured the yields of DN A single- and double-strand breaks (SSBs and DSBs) for plasmid DNA irradiated in aerobic aqueous solution with either 137Cs gamma rays or 4He ions with a mean LET of 94 or 150 keV micron-1. The presence of dimethyl sulfoxide (DMSO) resulted in a decrease in the yields of both SSBs and DSBs, with a greater decrease being apparent for gamma irradiation than for 4He-ion irradiation. Irradiation by 4He ions in the presence of N-(2-thioethyl)- 1,3-diaminopropane (WR-1065) resulted in a decrease in the yield of SSBs and a slightly larger decrease in the yield of DSBs. Together with results obtained previously, these observations suggest a substantial contribution to the formation of SSBs and DSBs by 4He ions by species containing at least two radicals and more than two radicals, respectively.

DNA Damage↗
PubMed1996

Radiobiology of ultrasoft X rays. V. Modification of cell inactivation by dimethyl sulfoxide.

The effects of the radioprotector dimethyl sulfoxide (DMSO) were investigated for carbon-K (0.28 keV) and aluminum-K (1.47 keV) X rays compared with 60Co gamma rays for inactivation of mouse C3H 10T1/2 cells. The protection factor for 2 M DMSO was found to be 2.8 for both of the ultrasoft X-ray energies, which is not significantly different from the protection factor of 2.6 found for gamma rays. The results indicate that the proportion of scavengeable lethal damage from gamma and X rays does not depend on the proportion of the total energy that is deposited by low-energy electrons of relatively high ionization density.

Animals↗