Search PubMed⌕ Search

Biomedical subjects

R J Irwin

Publications and source records attributed to R J Irwin.

At least 19 recordsLinked to original sources
PubMed2005

Follicular fluid steroid levels and subsequent sex of bovine embryos.

On the basis of evidence suggesting a maternal involvement in the determination of the sex of the offspring, we took ova at the point of ovulation from crossbred heifers, fertilised them, and established the sex of the embryos. At the same time we took individual-matched samples of follicular fluid from each follicle of origin, and measured the levels of testosterone and oestradiol, blind to the sex of the embryo. We found no effect of oestradiol on sex in either primary or subordinate follicles. But bovine ova from subordinate follicles that had follicular fluid with a high concentration of testosterone (in vivo) were later more likely to be fertilised by a Y-chromosome-bearing spermatozoon (in vitro). These, along with similar results from other researchers, suggest that further study of the relationship between mammalian follicular hormones at the time of conception and subsequent sex of offspring, may help resolve some of the problems associated with theories of adaptive control of the sex ratio in mammals.

Animals↗
PubMed2002

Chemo-ablation of the prostate with dehydrated alcohol for the treatment of prostatic obstruction.

PURPOSE: We confirmed clinically whether chemo-ablation of the prostate with absolute ethanol may be an innovative transurethral approach for the relief of obstructive benign prostatic hyperplasia. METHODS: Using the InjecTx endoscopic device (Injectx Inc., San Jose, California) an initial cohort of 15 patients, including 13 who have now been followed more than 1 year, underwent elective transurethral chemo-ablation of the prostate. RESULTS: Preoperative and postoperative comparisons of the American Urological Association symptom score, maximum urine flow rate and prostatic volume reveal significant improvement with minimal discomfort and no major complication. CONCLUSIONS: The InjecTx technique proved encouragingly successful in this initial small-scale clinical trial.

Aged↗
PubMed2001

IL-6 signaling by STAT3 participates in the change from hyperplasia to neoplasia in NRP-152 and NRP-154 rat prostatic epithelial cells.

BACKGROUND: STAT3 phosphorylation is associated with the neoplastic state in many types of cancer, including prostate cancer. We investigated the role of IL-6 signaling and phosphorylation of STAT3 in 2 rat prostatic epithelial lines. NRP-152 and NRP-154 cells were derived from the same rat prostate, yet the NRP-152 cells are not tumorigenic while the NRP-154 cells are tumorigenic. These lines are believed to represent 2 of the stages in the development of prostate cancer, hyperplasia and neoplasia. Differences in signaling pathways should play a role in the 2 phenotypes, hyperplastic and neoplastic. METHODS: We looked at the phosphorylation state of STAT3 by intracellular flow cytometry, using phospho-specific antibodies to STAT3. We used the same method to examine IL-6 production by the cell lines. We also measured apoptosis by binding of fluorescent annexin V to the cells. RESULTS: Although both cells lines made IL-6 constitutively, phosphorylated-STAT3 was present in untreated NRP-154 cells, but not in NRP-152 cells. Treatment with dexamethasone inhibited the IL-6 production of NRP-152 cells, but enhanced that of NRP-154 cells. Treatment with the JAK2 inhibitor AG490 induced apoptosis in NRP-152, but not NRP-154 cells. CONCLUSIONS: We conclude from these experiments that STAT3 activity plays a role in the phenotype of NRP-154 cell, but not NRP-152 cells. The significance of alternative IL-6 signaling pathways in the different phenotypes of the 2 cell lines is discussed.

Animals↗
PubMed2001

Reservoir herniation as a complication of three-piece penile prosthesis insertion.

OBJECTIVES: To obtain data concerning the incidence and management of reservoir herniation in inflatable penile prosthesis surgery in a clinical investigation. Reservoir herniation after scrotal placement of inflatable penile prosthesis is an unusual complication, and a review of the published medical reports reveals only anecdotal reports and no definitive articles. METHODS: A multi-item self-addressed questionnaire was mailed to the members of the Society for the Study of Impotence questioning the occurrence of reservoir migration from the prevesical space to the inguinal canal or scrotum. In addition, the database of one of us was reviewed to determine the incidence of reservoir migration in a large series of 1206 three-piece penile prostheses. RESULTS: The response rate was 38%. A minority of respondents (28%) were familiar with the problem. Of those who had experienced this complication, the occurrence was very rare and usually appeared in the immediate postoperative period, often in association with vigorous coughing spells or vomiting. The responders also indicated that imperfect surgical technique might have been implicated in some cases. Management usually consisted of reservoir replacement or repositioning through an inguinal incision with repair of the defect. Alternatively, several surgeons used the existing scrotal incision if the patient presented in the immediate postoperative period. The incidence of reservoir herniation was 0.7%. CONCLUSIONS: Reservoir herniation is a rare complication of inflatable penile prosthesis surgery that occurs almost exclusively in penoscrotally placed prostheses. Familiarity with various approaches to the management of this complication is clinically useful to urologists performing penile prosthesis surgery.

Foreign-Body Migration↗
PubMed2001

Are we ordering too many PSA tests? Prostate cancer diagnosis and PSA screening patterns for a single Veterans Affairs Medical Center.

BACKGROUND: Limits on the frequency of PSA testing and an endpoint for the age of the screened population have not been established. The numbers of performed serum PSA tests, cost evolution, and utilization patterns by various subspecialties in one medical center were analyzed to gain insight into trends in screening for early detection of prostate cancer and gather information about the appropriate use of PSA testing. METHOD: Computerized records were reviewed for numbers of PSA tests obtained, prostate biopsies performed, and prostate cancer cases diagnosed in the VA NJ-Health Care System from 1996 to 1998. In addition, PSA tests performed during two representative weeks in 1996 and 1997 were analyzed to evaluate a smaller cohort of patients with regard to age, consequences of the test results in their management, and subspecialties ordering the tests. RESULTS: PSA testing increased steadily between 1992 and 1998, with the most significant change (152% increase) between 1997 (9,410 tests) and 1998 (23,684). Prostate cancer diagnoses by biopsy were 164/434 (37.8%) in 1997 and 195/507 (38.5%) in 1998. For the 14,274 additional PSA tests obtained in 1998, 31 more prostate cancers were diagnosed. Prostate cancer diagnoses per PSA tests were 164/9,410 (1.8%) in 1997 and 195/23,684 (0.8%) in 1998. Primary care providers ordered 61% of the PSA tests. CONCLUSIONS: Most PSA tests at this institution were ordered by general practitioners, and the number of PSA tests ordered for men over 75 was high. The dramatic increase between 1997 and 1998 was not accompanied by a similar rise in the diagnosis of prostate cancer, raising the possibility of indiscriminate PSA testing or unnecessary repetition of testing. Guidelines for prostate cancer screening and continued PSA testing in the geriatric population may need further clarification.

Aged↗
PubMed2001

Indices of response bias in the same-different experiment.

The same-different experiment is popular for assessing perceptual performance, including the performance of people with neuropsychological deficits. Although the measurement of accuracy with this experiment is now well understood, the measurement of response bias remains problematic. Reformulating the decision space for the experiment can yield new bias indices that are analogous to, but numerically different from, those of the more familiar yes-no experiment. Isobias curves that show how hit rate covaries with false alarm rate for constant bias but varying accuracy are presented for eight indices, and best-fitting parameters of the isobias functions are determined for a set of experimental data. The theoretical status of the bias indices and their relation to other formulations are reviewed.

Adult↗
PubMed2001

The decision to eject: a receiver operating characteristic analysis.

BACKGROUND: Although the technology of ejection-seat systems is highly developed and automated, the decision about whether to eject still rests with the pilot. One factor thought to affect that decision is the height at which the decision must be made. For this reason the Royal New Zealand Air Force considered lowering its designated ejection decision height of 10,000 ft above ground level so that pilots had more time to make a correct decision. HYPOTHESIS: Lowering the ejection decision height will increase the accuracy of ejection decisions. METHODS: Thirty male Strike pilots each flew twenty simulated sorties. Half the sorties involved scenarios that required ejection and half did not. The pilots were divided into three equal groups which were randomly assigned to an ejection decision height of 10,000, 6,000, or 3,000 ft above ground level. After a sortie ended or was terminated by ejection, each pilot rated his confidence on a six-point scale that the scenario did or did not require ejection. RESULTS: Receiver operating characteristic analysis showed that the ejection decision height did not influence the accuracy of the decision to eject, but did affect the bias for ejecting. The bias in favor of ejecting increased as the height was lowered. Experienced pilots were more decisive in making their judgments than less experienced pilots. CONCLUSIONS: Lowering the ejection decision height did not affect the accuracy with which pilots could discriminate between flight scenarios that required ejection and ones that did not, but it did increase their bias to eject.

Aviation↗
PubMed2000

Compliance of Victorian dairy farmers with current calf rearing recommendations for control of Johne's disease.

Questionnaires were posted to 800 randomly selected registered Victorian dairy farmers in 1996. Five hundred and thirty-four responses were received and analysed. Johne's disease (JD) had been diagnosed on the farm of 13.2% of respondents in the last 5 years. JD was rated second only to neonatal diarrhoea in importance as a disease of calves, even though other diseases occurred more frequently. However, there was a low level of compliance with JD control recommendations by the respondents. There was no significant difference in the number of JD control recommendations adopted by farmers between the three major Victorian regions. There was a significant difference in compliance between farms having had a diagnosed case of JD and those that had not. Although there is awareness among dairy farmers of the importance of JD, there appears to be a poor implementation of measures by farmers to prevent the spread of the disease. Current JD control recommendations and the method of information transfer to Victorian dairy farms should be reassessed to ensure that dairy heifers are reared with minimal risk of transmission of JD.

Animals↗
PubMed2000

Internal carotid artery pseudoaneurysm related to pregnancy.

Arterial rupture is a common cause of maternal death. The increased tendency of true and false aneurysms to develop or rupture with advancing gestational age suggests that hemodynamic, hormonal, or other physiologic changes of pregnancy may play a role in their formation. To our knowledge, pseudoaneurysm formation from a carotid dissection or a ruptured true aneurysm related to pregnancy has not been previously reported. We report the successful repair of a large extracranial internal carotid artery pseudoaneurysm related to pregnancy. The clinical presentation, diagnostic modalities, surgical exposure, and treatment options for high internal carotid artery aneurysms will be discussed.

Adult↗
PubMed2000

Endourologic management of benign ureteral strictures with and without compromised vascular supply.

OBJECTIVES: To retrospectively assess the efficacy of balloon dilation, endopyelotomy/ureterotomy, and stenting alone in the management of benign ureteral strictures with intact or compromised vascular supply. METHODS: One hundred fourteen patients with benign ureteral strictures were assessed after at least a 2-year follow-up (range 2 to 16 years, mean 6.3). Balloon dilation was performed in 81, endopyelotomy/ureterotomy with temporary stenting in 27, and ureteral stenting alone in 6 patients. Ureteral strictures were divided into strictures with intact or with compromised vascular supply. RESULTS: Balloon dilation was successful in short ureteral strictures with intact vascular supply in 33 of 37 (89.2%), but only in 3 of 8 (37.5%) long ureteral strictures and in 1 of 2 (50%) recurrent ureteropelvic junction strictures. Balloon dilation was less successful when the vascular supply was compromised in 2 (40%) of 5 short strictures, 1 (16.7%) of 6 long strictures, and 2 (33.3%) of 6 recurrent ureteropelvic junction strictures. Endopyelotomy/ureterotomy was successful in 17 (89.5%) of 19 strictures with compromised vascular supply. CONCLUSIONS: Balloon dilation is recommended for management of short strictures with intact vascular supply. Endoureterotomy with stenting is recommended for all long ureteral strictures, for ureteropelvic junction stenoses, and for short ureteral strictures with compromised vascular supply and benign underlying etiology.

Adult↗
PubMed2000

Accuracy of diagnosis by guided biopsy of renal mass lesions classified indeterminate by imaging studies.

OBJECTIVES: To define the accuracy, safety, and impact of percutaneous biopsies of indeterminate mass lesions as an additional diagnostic tool. The vast majority of renal mass lesions are routinely diagnosed by radiographic features alone. However, with the increased use of computed tomography scanning and ultrasound, many smaller renal masses, which are "indeterminate" (refractory to categorization on the basis of imaging alone), are now being discovered. METHODS: We retrospectively reviewed 583 patients (364 male and 219 female) with indeterminate renal mass lesions diagnosed by imaging studies that were further investigated by percutaneous biopsy. Patients were followed up for at least 5 years if the biopsy result demonstrated a benign lesion, or they underwent surgical exploration if the biopsy result demonstrated a malignancy. Biopsy or aspiration material was assessed by histopathologic and cytologic evaluation and, when appropriate, with biochemistry, Gram stain, culture, and sensitivity. The biopsy site was localized by computed tomography, ultrasound, or fluoroscopy. RESULTS: Five hundred eighty-three patients with indeterminate renal mass lesions (representing 7.2% of all renal masses diagnosed from 1967 through 1996) were diagnosed by imaging studies complemented by guided biopsy. Sixty-six patients were lost to follow-up, leaving 517 patients who were analyzed. In 393 cases (76%), the imaging-guided biopsy provided a definitive diagnosis. The incidence of false diagnoses was 1.2% (7 biopsies). In 124 of the cases (21%), imaging-guided biopsy was unable to determine the etiology of the lesion with acceptable confidence; of these, 21 biopsies did not provide enough material to establish the diagnosis (16.9%). CONCLUSIONS: Overall, percutaneous biopsy of the kidney has proved to be a safe and accurate diagnostic procedure, with impact on the management of cystic or solid renal lesions.

Adolescent↗
PubMed2000

Arteriovenous fistulae complicating cardiac pacemaker lead extraction: recognition, evaluation, and management.

Transvenous pacemaker lead extraction has become a commonly performed procedure that is associated with a small but significant risk. We report two cases where lead extraction was complicated by arteriovenous fistulae between branches of the aortic arch and the left brachiocephalic vein. Presenting signs and symptoms included severe chest or back pain, persistent or copious bleeding from the venous puncture site, unexplained hypotension or anemia, superior vena cava syndrome, and signs of central venous hypertension or acute heart failure. One patient whose injury was not recognized immediately and who did not undergo repair died rapidly, whereas the other patient who was diagnosed quickly underwent successful repair. Immediate diagnosis with arteriography and rapid intervention with surgery or percutaneous techniques are indicated and may prevent mortality.

Aged↗
PubMed2000

Endourologic management of malignant ureteral strictures.

PURPOSE: This retrospective analysis assessed the efficacy of balloon dilatation, endoureterotomy, percutaneous ureteroneocystostomy with stenting, and insertion of Wallstents in the management of malignant ureteral strictures with an intact or compromised vascular supply. PATIENTS AND METHODS: A series of 127 patients with ureteral strictures secondary to malignancies were assessed after at least 2-year follow-up (range 2-5 years; mean 3.5 years). Balloon dilation (antegrade approach) was applied in 46 patients, endoureterotomy with temporary stenting in 37, percutaneous ureteroneocystostomy with stenting in 34, bougie and stents in 13, and Wallstents in 31. RESULTS: Balloon dilatation was successful in only two of four malignant midureteral stenoses with intact vascular supplies and was even less successful (10%) in midureteral strictures with a compromised vascular supply. Endoureterotomy failed in all cases to prevent ureteral obstruction. Percutaneous ureteroneocystostomy achieved patency in 11 of 34 patients (33%) having a compromised ureteral vascular supply. Wallstents were successful in 18 of 31 patients (58%) with stenoses of the pelvic ureter. CONCLUSIONS: Percutaneous ureteroneocystostomy with stenting meets the requirement for palliation in patients with obstruction secondary to pelvic neoplasms. Wallstents proved to be most successful when used in the pelvic ureter.

Adult↗
PubMed1999

Retinoid and androgen regulation of cell growth, epidermal growth factor and retinoic acid receptors in normal and carcinoma rat prostate cells.

Recent in vivo and in vitro studies suggest that retinoic acid receptor (RAR)-mediated processes may be involved in androgen regulation of prostate cells in a manner that may be altered during prostatic carcinogenesis. We tested this hypothesis in the newly established carcinoma and non-carcinoma rat prostate epithelial cell lines, NRP-154 and NRP-152, respectively. In DMEM/F-12 medium supplemented with 10% charcoal stripped fetal calf serum (cFCS), the number of both NRP-152 and NRP-154 cells were stimulated by testosterone (T), with a 4-fold greater effect in NRP-152 than in NRP-154 cells. Retinoic acid (RA) alone also stimulated the growth of NRP-152 cells, but failed to induce cell growth of NRP-154 cells. Importantly, the level of RAR alpha mRNA was elevated whereas the levels of RAR gamma and androgen receptor (AR) mRNA were lower in NRP-154 cells compared to those in NRP-152 cells. Treatment of NRP-152 cells with increasing doses of T resulted in a dose-dependent decrease and rebound of the level of RAR alpha and gamma mRNA in NRP-152 cells; these effects were not apparent, if not reversed, in NRP-154 cells. Both ligand binding and Western blot analyses revealed that epidermal growth factor receptor (EGF-R) was stimulated by 20 nM T but was suppressed by 0.1 microM RA, which also attenuated the stimulating effects of T on EGF-R in NRP-152 and to a lesser extent in NRP-154 cells. The differences in the level and androgen regulation of RAR mRNAs and reciprocal regulation of EGF-R expression by T and RA between NRP-154 and NRP-152 cells suggest that variations in the EGF-R and RAR signal events may contribute to differences in growth rate between these two cell lines.

Animals↗
PubMed1999

Percutaneous nephrostomy as adjunct management in advanced upper urinary tract infection.

OBJECTIVES: To determine by retrospective review of 315 percutaneous nephrostomies, performed for pyonephrosis, whether this intervention has major clinical advantages. METHODS: From 1977 to 1996, under the direct supervision of the senior author of this report (E.K.L.), at seven hospital sites, 315 patients (181 males, 134 females; 17 to 88 years of age) were treated with percutaneous nephrostomy and antibiotic therapy for infected hydronephrosis. RESULTS: Additional or disparate pathogens were identified in 116 (36.8%) of 315 patients, leading to a clinically significant change in, or addition of, antibiotics and/or antifungal agents in 84 (73%) of 116. Most notably, we often found a clinically important disparity between the results of cultures obtained from the nephrostomy and those obtained from bladder-urine specimens. CONCLUSIONS: This retrospective review confirms previously reported advantages of percutaneous upper urinary tract drainage as a potentially life-saving adjunct in the treatment of pyonephrosis. Several case studies highlight the advantage of this maneuver in difficult cases involving obstruction due to extensive fungus or debris. In particular, our review focuses attention on the clinically important insight that urine cultures from percutaneous nephrostomy drainage often identify pathogens that differ from those detected in concurrent bladder cultures.

Humans↗
PubMed1999

Shock after blast wave injury is caused by a vagally mediated reflex.

OBJECTIVE: Bomb blast survivors occasionally suffer from profound shock and hypoxemia without signs of external injury. We hypothesize that a vagally mediated reflex such as the pulmonary defensive reflex is the cause of shock from blast wave injury. This study was a prospectively randomized, controlled animal study. METHODS: By using a previously described model of blast wave injury, we randomized rats to one of four groups: control, blast-only, bilateral cervical vagotomy plus atropine 200 microg/kg i.p. only, and bilateral cervical vagotomy plus atropine 200 microg/kg i.p. before blast injury. Cardiopulmonary parameters were recorded for 90 minutes after the blast or until death. RESULTS: Bradycardia, hypotension, and absence of compensatory peripheral vasoconstriction, typically seen in animals subjected to a blast pressure injury, were prevented by bilateral cervical vagotomy and intraperitoneal injection of atropine methyl-bromide. Hypoxia and lung injury were not statistically significant between the blasted groups, suggesting equivalent injury. CONCLUSION: Our data implicate a vagally mediated reflex such as the pulmonary defensive reflex as the cause of shock seen immediately after a blast pressure wave injury.

Animals↗
PubMed1999

An area theorem for the same-different experiment.

If observers in a same-different experiment base their decisions on the absolute difference between observations on a trial, the area under the receiver operating characteristic equals the maximum proportion of correct decisions that an unbiased independent-observations observer could attain. Even though the differencing strategy is suboptimal, the area measure yields an index of optimal performance.

Data Interpretation, Statistical↗