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Biomedical subjects

J F Ward

Publications and source records attributed to J F Ward.

At least 19 recordsLinked to original sources
PubMed2004

Radioprotection of plasmid DNA by oligolysines.

PURPOSE: To define ionic conditions under which oligolysines condense DNA as assayed by radioprotection of a plasmid substrate. And to compare these conditions with those required by the well-characterized ligands spermidine and hexammine cobalt (III). This will enable a reversible compaction model for plasmid DNA to be devised that models more closely mammalian chromatin than those based on polyamines. MATERIALS AND METHODS: Aqueous solutions containing plasmid DNA, sodium perchlorate and one of the five ligands trilysine, tetralysine, pentalysine, spermidine, or hexammine cobalt (III) were subjected to gamma-irradiation. The yields of the resulting single-strand breaks were quantified by gel electrophoresis. The effects of tetralysine and pentalysine were also examined by light scattering. RESULTS: The combination of low concentrations of the ligand and high concentrations of sodium perchlorate produced a relatively high yield of single-strand breaks. In contrast, the combination of high concentrations of the ligand and low concentrations of sodium perchlorate resulted in an approximately 25-fold lower single-strand break yield. The transition between these two break yields took place over very narrow concentration ranges of the ligand. A large change in light scattering occurred at the same concentration. The radioprotective ability of the ligands decreased in the order pentalysine > tetralysine > hexammine cobalt (III) > spermidine > trilysine. CONCLUSIONS: The effect of the oligolysines is qualitatively very similar to the previously reported radioprotection produced under similar conditions by the polyamines spermidine and spermine. It is caused by condensation of the DNA into a highly compacted form. As peptides, oligolysines are structurally more closely related than other ligands to naturally occurring DNA condensing agents such as histone proteins. Therefore, they may form the basis of a model system suitable for studying DNA damage produced by the direct effect of ionizing radiation (ionization of the DNA itself).

DNA Damage↗
PubMed2003

Repair of oxidative DNA damage by amino acids.

Guanyl radicals, the product of the removal of a single electron from guanine, are produced in DNA by the direct effect of ionizing radiation. We have produced guanyl radicals in DNA by using the single electron oxidizing agent (SCN)2-, itself derived from the indirect effect of ionizing radiation via thiocyanate scavenging of OH. We have examined the reactivity of guanyl radicals in plasmid DNA with the six most easily oxidized amino acids cysteine, cystine, histidine, methionine, tryptophan and tyrosine and also simple ester and amide derivatives of them. Cystine and histidine derivatives are unreactive. Cysteine, methionine, tyrosine and particularly tryptophan derivatives react to repair guanyl radicals in plasmid DNA with rate constants in the region of approximately 10(5), 10(5), 10(6) and 10(7) dm3 mol(-1) s(-1), respectively. The implication is that amino acid residues in DNA binding proteins such as histones might be able to repair by an electron transfer reaction the DNA damage produced by the direct effect of ionizing radiation or by other oxidative insults.

Amino Acids↗
PubMed2002

One-electron oxidation of plasmid DNA by selenium(V) species.

PURPOSE: To employ the gamma-radiation-generated selenium(V) one-electron-oxidizing agent SeO3*- for the preparation of guanyl radicals in plasmid DNA, and to compare the behaviour of this reagent with that of other similarly reactive oxidant species. MATERIALS AND METHODS: Plasmid DNA in aerobic aqueous solution was irradiated with 137Cs gamma-rays (662 keV). The solutions also contained up to 4x10(-2) mol x dm(-3) sodium selenate (Na2SeO4) and/or up to 10(-1) mol x dm(-3) sodium biselenite (NaHSeO3), as well as auxiliary scavengers such as DMSO or glycerol. In some cases, reducing agents such as ferrocyanide were also present. After irradiation, the plasmid was incubated with the Escherichia coli base excision-repair endonuclease formamidopyrimidine-DNA N-glycosylase (FPG). These treatments produced strand breaks in the plasmid. The yields of these strand breaks were quantified by agarose gel electrophoresis. RESULTS: In general, gamma-irradiation produced single-strand breaks (SSB) in plasmid DNA. Subsequent incubation with the endonuclease FPG increased the SSB yield by a factor of 2-100-fold. The smallest effects of FPG were observed when only DMSO or glycerol were present during irradiation. FPG incubation produced significantly larger increases in the SSB yield after gamma-irradiation in the additional presence of selenate and/or biselenite. The largest effect of FPG was observed after gamma-irradiation in the presence of 10(-2) mol x dm(-3) sodium selenate and 10(-1) mol x dm(-3) glycerol. This was indicative of extensive oxidative damage to the plasmid under these conditions and provided evidence for guanine oxidation mediated by SeO3*-. The large effect of FPG was strongly attenuated by the addition of reducing agents such as ferrocyanide. The observations suggest that these reducing agents exert their effects through the reduction of an intermediate guanyl radical. CONCLUSION: By comparing the yields of breaks produced after gamma-irradiation under a range of conditions, it is possible to formulate a reaction scheme that describes the chemical reactions responsible for the formation of strand breaks and FPG-sensitive sites. By applying this scheme to the data, we can quantify rate constants for the reduction of DNA guanyl radicals by reducing agents. This reaction is of particular interest to radiation biology because it is the equivalent of the repair of DNA damage by the direct effect of ionizing radiation.

Binding Sites↗
PubMed2002

Modification of ionizing radiation clustered damage: estimate of the migration distance of holes through DNA via guanyl radicals under physiological conditions.

PURPOSE: Guanyl radicals are produced in DNA when it is subjected to oxidation or ionizing radiation. The sites at which stable products can be identified can be located dozens of base pairs away from the initial site of the electron loss. This migration will modify the spatial distribution of damage and tends to mitigate the clustering of initial damage generally associated with ionizing radiation. The migration distance is presumably a function of the lifetime of the intermediate guanyl radical, and we wished to quantify the relationship between them. MATERIALS AND METHODS: Aqueous solutions containing plasmid DNA and thiocyanate ions were treated with gamma-irradiation. These conditions result in the very efficient production of guanyl radicals in the plasmid. We quantified the formation of stable guanine oxidation products in the plasmid as strand breaks by using the E. coli base excision repair endonuclease formamidopyrimidine-DNA N-glycosylase (FPG). The effect of two additives on the yield of guanine oxidation, nitrite ions and the DNA binding ligand doxorubicin (adriamycin), were examined. RESULTS: The presence during irradiation of the DNA-binding ligand doxorubicin attenuated the yields of stable oxidized guanine products formed. The additional presence of nitrite decreased this effect of doxorubicin. CONCLUSION: Because doxorubicin binds strongly to DNA, its ability to attenuate guanine oxidation can be interpreted in terms of the migration distance of the intermediate guanyl radical. Because nitrite repairs these intermediate guanyl radicals by electron transfer, its presence during irradiation decreases their lifetime. Therefore, we derived an estimate of the migration distance of guanyl radicals as a function of their lifetime. The presence in cells of antioxidants such as glutathione sets an upper limit to the likely lifetime and, therefore, the migration distance of guanyl radicals. It was concluded that the migration of guanyl radicals may not decrease the clustering of DNA damage in vivo to a great extent.

Antineoplastic Agents↗
PubMed2001

Ureteral stenting after ureteroscopy for distal ureteral calculi: a multi-institutional prospective randomized controlled study assessing pain, outcomes and complications.

PURPOSE: We compare postoperative pain, stone-free rates and complications after ureteroscopic treatment of distal ureteral calculi with or without the use of ureteral stents. MATERIALS AND METHODS: A total of 113 patients with distal ureteral calculi amenable to ureteroscopic treatment were prospectively randomized into stented (53) and unstented (60) groups. Stones were managed with semirigid ureteroscopes with or without distal ureteral dilation and/or intracorporeal lithotripsy. Preoperative and postoperative pain questionnaires were obtained from each patient. Patients with stents had them removed 3 to 10 days postoperatively. Radiographic followup was performed postoperatively to assess stone-free rates and evidence of obstruction. RESULTS: Six patients randomized to the unstented group were withdrawn from the study after significant intraoperative ureteral trauma was recognized, including 3 ureteral perforations, that required ureteral stent placement, leaving 53 with stents and 54 without for analysis. Patients with stents had statistically significantly more postoperative flank pain (p = 0.005), bladder pain (p <0.001), urinary symptoms (p = 0.002), overall pain (p <0.001) and total narcotic use (p <0.001) compared to the unstented group. Intraoperative ureteral dilation or intracorporeal lithotripsy did not statistically significantly affect postoperative pain or narcotic use in either group (p >0.05 in all cases). Overall mean stone size in our study was 6.6 mm. There were 4 (7.4%) patients without stents who required postoperative readmission to the hospital secondary to flank pain. All patients (85%) who underwent imaging postoperatively were without evidence of obstruction or ureteral stricture on followup imaging (mean followup plus or minus standard deviation 1.8 +/- 1.5 months), and the stone-free rate was 99.1%. CONCLUSIONS: Uncomplicated ureteroscopy for distal ureteral calculi with or without intraoperative ureteral dilation can safely be performed without placement of a ureteral stent. Patients without stents had significantly less pain, fewer urinary symptoms and decreased narcotic use postoperatively.

Humans↗
PubMed2001

Expanding the differential diagnosis of the acute scrotum: ventriculoperitoneal shunt herniation.

An 18-month-old boy presented to the emergency department after 4 hours of inconsolability and acute scrotal swelling. The physical examination revealed a new scrotal hydrocele with migration of a ventriculoperitoneal shunt into the right hemiscrotum. The presence of a ventriculoperitoneal shunt has been associated with increased patency of the processus vaginalis and scrotal hydroceles. The presentation of an acute scrotum in a child with a ventriculoperitoneal shunt should be recognized as a possible shunt complication. Migration of the shunt through the processus vaginalis is an extremely uncommon event.

Acute Disease↗
PubMed2001

Relationship between obesity and race in predicting adverse pathologic variables in patients undergoing radical prostatectomy.

OBJECTIVES: To determine whether obesity is associated with more advanced prostate cancer (PCa) in radical prostatectomy patients and to explore the ethnic variability in body mass index (BMI) as a potential explanation for racial differences in PCa risk. METHODS: A multi-institutional retrospective analysis of the clinical and pathologic parameters was performed on data from 860 patients with PCa undergoing radical prostatectomy between 1992 and 1998. Patient height and weight was used to calculate the BMI, which categorized patients into obese (BMI 30 kg/m(2) or greater), overweight (BMI 25 to 30 kg/m(2)), and normal (BMI 25 kg/m(2) or less) groups. Age, serum prostate-specific antigen level, pathologic stage, and Gleason score for each group were compared. The distribution of the BMI in each of four ethnic groups was also determined. RESULTS: Of 860 patients, 171 (20%) were obese, 425 (49%) overweight, and 264 (31%) normal. The obese patients presented at a younger mean age (62 years, P = 0.001), had higher mean Gleason scores (6.7, P = 0.002), had a higher likelihood of Gleason score 7 or greater cancer (71%, P = 0.003), and had a lower chance of organ-confined cancer (46%, P = 0.050). The BMI was highest in blacks, followed by whites and Asians, and blacks had significantly higher grade cancers (P = 0.045). In multiple logistic regression analysis of the BMI and race, only BMI remained an independent predictor of Gleason grade. CONCLUSIONS: Obese patients with PCa present for radical prostatectomy at a younger age with higher grade and more pathologically advanced cancers. Blacks have higher grade cancers than other ethnic groups and, at the same time, have significantly higher BMIs. These findings suggest that obesity may in part account for the racial variability in PCa risk.

Age Factors↗
PubMed2001

Redox reactivity of guanyl radicals in plasmid DNA.

PURPOSE: It has been previously argued that gamma-irradiation of plasmid DNA in the presence of thiocyanate ions produces products recognized by the E. coli base excision-repair endonuclease formamidopyrimidine-DNA N-glycosylase (FPG), and there that derive from an intermediate guanyl radical species. The wish was to characterize the reactivity of this intermediate with reducing agents. MATERIALS AND METHODS: Aqueous solutions of plasmid DNA containing either bromide or thiocyanate (10(-3) to 10(-1) mol dm(-3)) and also one of six other additives (azide, ferrocyanide, iodide, nitrite, promethazine, tryptophan, 10(-7) to 10(-3) mol dm(-3)) were subjected to 137Cs gamma-irradiation (662 keV). After irradiation, the plasmid was incubated with FPG. Strand break yields before and after incubation were determined by agarose gel electrophoresis under neutral conditions. RESULTS: The very high yields of FPG-sensitive sites in the presence of SCN- or Br- decreased significantly with increasing concentrations of all of the six additives, with promethazine and tryptophan being the most efficient additives, and azide and iodide the least. CONCLUSIONS: From the results it is possible to estimate values of the rate constants for the reduction of the DNA guanyl radical (5 x 10(5), 2 x 10(5), 10(7) and 10(7) dm3 mol(-1) s(-1) for ferrocyanide, nitrite, promethazine and tryptophan respectively).

Bromides↗
PubMed2001

DNA strand break yields after post-high LET irradiation incubation with endonuclease-III and evidence for hydroxyl radical clustering.

PURPOSE: To determine the increase in single- (SSB) and double-strand break (DSB) yields after post-high LET irradiation incubation of plasmid DNA with the endonuclease-III (endo-III) of Escherichia coli. MATERIALS AND METHODS: Plasmid DNA in aerobic aqueous solution was irradiated with one of five radiation types: 137Cs gamma-rays (LET approximately 0.3keV microm(-1)), 244Cm alpha-particles (140-190 keV microm(-1)), 4He ions (97 keV microm(-1)), 56Fe ions (143 keV microm(-1)) or 197Au ions (1,440 keV microm(-1)). The irradiated samples were then incubated with endo-III. SSB and DSB yields were quantified by agarose gel electrophoresis. RESULTS: Endo-III incubation produced an increase in the SSB and DSB yields. The increases were in general lower after the high LET irradiation than after gamma-irradiation. This may reflect inhibition of the activity of endo-III by the nearby DNA damage expected from high LET radiation. It can be shown that even if the activity of endo remains unchanged, significantly lower increases in SSB and DSB yields would still be expected. CONCLUSION: The results provide evidence for clustered DNA damage after high LET irradiation.

Cesium Radioisotopes↗
PubMed2001

Reaction of guanyl radicals in plasmid DNA with biological reductants: chemical repair of DNA damage produced by the direct effect of ionizing radiation.

PURPOSE: It has been previously argued that the use of the one-electron oxidants (SCN)2(*-) and Br2(*-) with plasmid DNA leads to the formation of DNA guanyl radicals. These guanyl radical species are intermediates in the DNA damage produced by processes such as photo-ionization and ionizing irradiation. The present paper evaluates the use of thallium(II) ions (Tl(II)OH(+)) as the one-electron oxidant, and also determines rate constants for the reduction (repair) of guanyl radicals in plasmid DNA by a variety of reducing agents including the biologically important compounds ascorbate and glutathione. MATERIALS AND METHODS: Aqueous solutions of plasmid DNA containing 10(-3) mol dm(-3) thiocyanate or thallous ions and a reducing agent (azide, nitrite, ferrocyanide, hexachloroiridate(III), iodide, ascorbate, glutathione, glutathione disulphide, methionine, tyrosine, 5-hydroxyindole-3-acetic acid, 10(-7)-10(-4) mol dm(-3)) were irradiated with 137Cs gamma-rays (662 keV). After irradiation, the plasmid was incubated with the E. coli base excision repair endonuclease formamidopyrimidine-DNA N-glycosylase (FPG). Strand break yields after incubation were quantified by means of agarose gel electrophoresis. RESULTS: High yields of FPG-sensitive sites produced by the oxidants (SCN)2(*-) and Tl(II)OH(+) were strongly attenuated by the presence of the reducing agents. CONCLUSIONS: From the results, it is possible to arrive at estimates of the rate constants for the reduction of the DNA guanyl radical by the reducing agents. Values lie in the range 10(4)-10(7) dm(3) mol(-1) s(-1). Using the values for ascorbate and glutathione, it is possible to estimate an upper limit on the order of milliseconds for the lifetime of DNA guanyl radicals under cellular conditions. The implication is that there may well be a significant chemical repair of DNA base damage by the direct effect of ionizing radiation.

DNA↗
PubMed2001

Redox equilibrium between guanyl radicals and thiocyanate influences base damage yields in gamma irradiated plasmid DNA. Estimation of the reduction potential of guanyl radicals in plasmid DNA in aqueous solution at physiological ionic strength.

PURPOSE: Gamma irradiation of an aqueous solution containing thiocyanate ions produces the strongly oxidizing intermediate (SCN)2*-. Reaction of this species with plasmid DNA produces damage that is revealed as strand breaks after incubation with the Escherichia coli base excision repair endonuclease formamidopyrimidine-DNA N-glycosylase (FPG). It has been previously reported that the yield of damage is highly sensitive to the experimental conditions, leading to the suspicion that electron transfer between DNA and (SCN)2*- is reversible. In principle this makes it possible to determine the oxidation potential for plasmid DNA (more formally the reduction potential of one-electron oxidized plasmid DNA), a fundamental parameter describing the reactivity of DNA towards electron transfer reactions. MATERIALS AND METHODS: Aqueous solutions of plasmid DNA and thiocyanate ions were subjected to 137Cs gamma-irradiation. After irradiation, the plasmid was incubated with the E. coli base excision repair endonuclease formamidopyrimidine-DNA N-glycosylase (FPG). The yield of this damage was quantified by using agarose gel electrophoresis to identify the fraction of the plasmid population that contains strand breaks. RESULTS: The yield of FPG-sensitive sites decreases with increasing thiocyanate concentration, decreasing DNA concentration, and increasing dose rate. By making some simple assumptions about the chemical reactions that produce DNA damage, it is possible to derive a quantitative mathematical model for the yield of FPG-sensitive sites. A good agreement was found between this model and the experimental observations over a wide range of conditions (thiocyanate concentrations, DNA concentrations, and dose rates that vary by 20-, 40-, and 150-fold respectively). CONCLUSIONS: It was possible to assign a value to the equilibrium constant for the one electron transfer reaction between the two radical species (SCN)2*- and DNA-G*+. This leads to an estimate of the reduction potential at pH 7 for the couple DNA G*+/DNA of E7 = +1.39+/-0.01V.

DNA↗
PubMed2001

Malignant cytological washings from prostate specimens: an independent predictor of biochemical progression after radical prostatectomy.

PURPOSE: Malignant cells have previously been identified in the cytological washings of prostate specimens obtained at radical prostatectomy for clinically localized prostate cancer. We investigated whether malignant cells in the cytological washings of radical prostatectomy specimens predict biochemical progression. The affect of total androgen blockade on cytological washings was also examined. MATERIALS AND METHODS: Cytological washings were obtained from radical prostatectomy specimens in 147 consecutive patients undergoing the procedure for clinically localized prostate cancer between November 1993 and April 1998. Of the 147 patients 54 were randomly selected to receive 1 month of total androgen blockade immediately before prostatectomy. To obtain the cytological specimen the extirpated prostate was subjected to a normal saline bath, as previously described. The cytology specimen was examined by a single cytopathologist blinded to preoperative and pathological findings. Biochemical progression, defined as prostate specific antigen 0.15 ng./ml. or greater, was determined using the Kaplan-Meier method. We also performed multivariate analysis of factors related to progression, including prostate specific antigen, pathological stage, margin status, Gleason grade and cytology status. Median followup was 37 months (range 13 to 66). RESULTS: Followup was available in 146 of 147 cases. Cytological washings were malignant in 14 of 92 patients (15%) who did not receive total androgen blockade preoperatively. In this group without androgen blockade the biochemical progression rate was significantly higher in those with positive cytology (p < 0.001). Positive cytology was an independent predictor of progression on multivariate analysis and a stronger predictor of progression than Gleason grade. No malignant cells were observed in cases of preoperative total androgen blockade (p < 0.001). However, biochemical progression was similar in the groups with and without androgen blockade (p = 0.355). CONCLUSIONS: Malignant cells may be identified in the cytological washings of radical prostatectomy specimens and they are an independent predictor of biochemical progression. One month of total androgen blockade preoperatively significantly decreases the rate of positive cytology but does not appear to change the rate of early biochemical failure.

Disease Progression↗
PubMed2000

Mechanism of DNA damage by thiocyanate radicals.

PURPOSE: It was previously shown that gamma-irradiation of aqueous solutions of plasmid DNA in the presence of millimolar concentrations of thiocyanate ions leads to the formation in very high yields of sites recognized by the base excision repair endonuclease formamido-pyrimidine-DNA N-glycosylase (FPG). The authors wished to characterize the mechanism responsible for the production of these FPG-sensitive sites. MATERIALS AND METHODS: An aqueous solution of plasmid DNA containing thiocyanate ions was irradiated with 137Cs gamma-rays. After irradiation, aliquots were treated with FPG. Break yields were determined using neutral agarose gel electrophoresis. RESULTS: The yield of FPG-sensitive sites decreased with decreasing enzyme activity, increasing thiocyanate concentration, increasing dose-rate, increasing ionic strength, increasing nitrite or iodide concentration, and decreasing oxygen concentration. CONCLUSION: The observations suggest that the monomeric thiocyanate radical SCN* is an intermediate in the reaction, and that the yields of FPG-sensitive sites are determined by competition between the disproportionation of the dimeric radical anion (SCN)*2- and the fate of a one-electron oxidized guanine species in DNA. The latter can react with oxygen to produce an FPG-sensitive site or can be reduced without producing an FPG-sensitive site. The results help to clarify the mechanisms responsible for DNA damage by the direct effect of ionizing radiation.

DNA↗
PubMed2000

DNA strand-break yields after post-irradiation incubation with base excision repair endonucleases implicate hydroxyl radical pairs in double-strand break formation.

PURPOSE: To determine the increases in SSB and DSB yields after post gamma-irradiation incubation of plasmid DNA with the Escherichia coli base excision repair endonucleases formamidopyrimidine-DNA N-glycosylase (FPG) and endonuclease III (endo III). MATERIALS AND METHODS: Aqueous solutions of plasmid DNA were irradiated with 137Cs gamma-rays in the presence of 10(-4) - 10(-1) mol dm(-3) formate. After irradiation, aliquots were treated with FPG and/or endo III. SSB and DSB yields were then determined using gel electrophoresis. RESULTS: Both SSB and DSB yields were found to increase after enzyme incubation, with the increase in the DSB yield being approximately equal to the square of the increase in the SSB yield. The correlation between the increases in the SSB and DSB yields was unaffected by the scavenger concentration during irradiation. CONCLUSION: Under the conditions used, the majority of DSB appear to be formed from two hydroxyl radical attacks.

DNA↗
PubMed2000

The ultrasonic description of postpubertal testicles in men who have undergone prepubertal orchiopexy for cryptorchidism.

PURPOSE: We provide a sonographic description of postpubertal testicles in patients who have undergone prepubertal orchiopexy with placement of a suture through the tunica albuginea. MATERIALS AND METHODS: Testicular ultrasound was performed in men who had undergone prepubertal testicular fixation for cryptorchidism using a suture passed through the tunica albuginea. Comparison was made to the sonographic appearance of cryptorchid testicles not secured with a fixating suture through the tunica albuginea. The operative report for each patient was reviewed with specific attention to use and type of suture material, and age at orchiopexy. RESULTS: Ultrasonography was performed on 22 men in whom a tunica albuginea fixating suture was placed during orchiopexy for cryptorchidism. Average patient age at orchiopexy was 5.6 years and median time from orchiopexy to this examination was 14.8 years. Right cryptorchidism existed in 64% of the men. No significant difference was noted in size between the 2 testicles in any patient. Ultrasonography did not identify any parenchymal abnormalities. A tunica albuginea calcification with posterior shadowing on the side of fixation was noted in 32% of patients, of whom 3 had calcified areas evident on physical examination. An area of subtunical hypoechogenicity was noted in 14% of patients. All tunical abnormalities were associated with the use of chromic suture. The remaining 12 patients (54%) had normal sonographic and physical examinations. The control group comprised 6 men who underwent orchiopexy without a fixating suture through the tunica albuginea. These men were examined identically and no sonographic abnormalities were noted in the tunica albuginea or testicular parenchyma. At a median of 16 months no patient had been diagnosed with testicular cancer or had a change in testicular self-examination. CONCLUSIONS: Tunica albuginea calcifications and hypoechogenic cysts are common ultrasonic findings in men who have undergone orchiopexy using a suture passed through the tunica albuginea. Parenchymal lesions should not be considered secondary to this procedure and must be treated as de novo abnormalities. These changes seem to be induced by the use of a fixating suture through the tunica albuginea.

Adolescent↗
PubMed2000

Transcatheter therapeutic embolization of genitourinary pathology.

With the advent of smaller vascular catheters and improved imaging techniques, percutaneous transcatheter embolization has become a valuable adjunct for the treatment of patients with various genitourinary pathologic conditions. Multiple embolic agents are now employed in an array of situations to devascularize organs, stop bleeding, and occlude passageways.

Journal Article↗
PubMed1999

Free-to-total prostate-specific antigen ratios 18-24 months following external beam radiation for adenocarcinoma of the prostate.

BACKGROUND AND OBJECTIVES: The purpose of this study was to evaluate free-to-total prostate-specific antigen (PSA) ratios after definitive external beam radiation therapy for men with adenocarcinoma of the prostate (CaP). METHODS: A prospective evaluation of percent free PSA in men following definitive external beam radiation therapy for CaP was compared to men with untreated CaP and men at very low risk for CaP. Statistical comparison of clinical and pathologic parameters was performed. RESULTS: There was no statistically significant difference in free-to-total PSA ratios for men with newly diagnosed CaP and men with detectable PSA who were treated with external beam radiation therapy. CONCLUSIONS: Free-to-total PSA ratios after definitive external beam radiation therapy for CaP are consistent with percent free PSA in patients with newly diagnosed CaP. This supports the theory that PSA from in situ prostate tissue following external beam radiation therapy is produced by malignant cells.

Adenocarcinoma↗