Biomedical subjects

Donal Downey

Publications and source records attributed to Donal Downey.

10 recordsLinked to original sources

PubMed2006

3D prostate model formation from non-parallel 2D ultrasound biopsy images.

Biopsy of the prostate using 2D transrectal ultrasound (TRUS) guidance is the current gold standard for diagnosis of prostate cancer; however, the current procedure is limited by using 2D biopsy tools to target 3D biopsy locations. We propose a technique for patient-specific 3D prostate model reconstruction from a sparse collection of non-parallel 2D TRUS biopsy images. Our method conforms to the restrictions of current TRUS biopsy equipment and could be efficiently incorporated into current clinical biopsy procedures for needle guidance without the need for expensive hardware additions. In this paper, the model reconstruction technique is evaluated using simulated biopsy images from 3D TRUS prostate images of 10 biopsy patients. All reconstructed models are compared to their corresponding 3D manually segmented prostate models for evaluation of prostate volume accuracy and surface errors (both regional and global). The number of 2D TRUS biopsy images used for prostate modeling was varied to determine the optimal number of images necessary for accurate prostate surface estimation.

Adenocarcinoma↗

PubMed2006

Intraoperative laparoscopic renal ultrasonography: use in advanced laparoscopic renal surgery.

OBJECTIVES: To highlight the use of intraoperative laparoscopic ultrasonography (ILUS) in complex renal surgery, as well its impact on management. ILUS has been used to facilitate advanced laparoscopic surgery, but only limited descriptions of the indications for its use have been published. METHODS: All patients undergoing laparoscopic renal procedures requiring ILUS from October 2001 to March 2005 were reviewed. A total of 50 cases, including 35 partial nephrectomies, cryoablation of 6 renal tumors, 6 radical nephrectomies, 2 perinephric explorations, and 1 resection of a renal artery aneurysm were assessed by ILUS. RESULTS: The average tumor size in the patients undergoing laparoscopic partial nephrectomy was 3.1 cm (range 1.4 to 8.0), and all margins were negative. Also, a previously unidentified satellite lesion was found in 1 patient. ILUS was essential in assessing iceball formation during laparoscopic renal cryotherapy. ILUS also proved useful in defining the anatomy during laparoscopic perinephric exploration, assessing renal vein thrombi during laparoscopic nephrectomy, and evaluating renal perfusion during laparoscopic renal artery aneurysm repair. CONCLUSIONS: ILUS can be extremely useful in advanced laparoscopic renal surgery. In a number of situations, it is an essential surgical tool. With expanding indications for laparoscopic surgery, the indications for ILUS continue to grow.

Adult↗

PubMed2005

3D TRUS guided robot assisted prostate brachytherapy.

This paper describes a system for dynamic intraoperative prostate brachytherapy using 3D ultrasound guidance with robot assistance. The system consists of 3D transrectal ultrasound (TRUS) imaging, a robot and software for prostate segmentation, 3D dose planning, oblique needle segmentation and tracking, seed segmentation, and dynamic re-planning and verification. The needle targeting accuracy of the system was 0.79 mm +/- 0.32 mm in a phantom study.

Algorithms↗

PubMed2005

Do all patients with high-grade prostatic intraepithelial neoplasia on initial prostatic biopsy eventually progress to clinical prostate cancer?

OBJECTIVE: To assess the clinical outcome of patients with a diagnosis of high-grade prostatic intraepithelial neoplasia (PIN) on initial prostatic biopsy, with a minimum of 5 years of follow-up, as such patients are at greater risk of having prostate cancer on subsequent biopsy. PATIENTS AND METHODS: Between November 1992 and October 1998, 21 patients were identified as having PIN on their initial transrectal ultrasonography-guided prostate biopsy. None of these patients had a focus of cancer on the initial biopsy. Their medical data were reviewed retrospectively to determine the natural history of PIN in these patients. Patients who were not identified as having cancer were followed every 6-12 months with prostate-specific antigen (PSA) testing and digital rectal examinations (DRE). RESULTS: A mean (range) of 7 (2-8) cores were taken at initial biopsy; the mean age of the patients was 63 (53-77) years and mean PSA level 9.1 (4.9-17.6) ng/mL. Six patients had an abnormal DRE at presentation. A mean of 8 (7-10) cores were obtained on the second biopsy; six patients were diagnosed with cancer, with a mean Gleason score of 6 (5-7), while three were diagnosed with persistent PIN. These three patients had a third prostate biopsy which showed cancer of Gleason score 6 in one and benign prostatic hyperplasia in two. After a mean follow-up of 72.2 (60-84) months, none of the remaining 12 patients was diagnosed with clinically significant cancer. Five of these patients went on to a third prostate biopsy, with no evidence of cancer. One patient died from unrelated causes during this period. CONCLUSION: This study affirms our current practice of following patients with PIN conservatively if a second or third subsequent prostate biopsy is negative. Whether PIN is a premalignant lesion or merely a lesion associated with cancer needs to be addressed in multicentre studies with a follow-up of > 10 years.

Aged↗

PubMed2004

Prospective evaluation of the role of quantitative Doppler ultrasound surveillance in liver transplantation.

Doppler ultrasound (DUS) is able to measure parameters of blood flow within vessels of transplanted organs, and vascular complications are associated with abnormal values. We analyzed the findings of 51 consecutive patients who underwent DUS on 2 occasions in the first postoperative week following liver transplantation for cirrhosis to determine the range of values in patients following liver transplantation. Three patients developed early vascular thromboses that were detected by the absence of a Doppler signal. In patients making an uneventful recovery, the arterial velocity tended to increase and the resistive index (RI) to decrease during the first postoperative week. All recipients were shown to have high-velocity segments within the hepatic artery, without an increase in flow resistance. Assessment of the portal vein revealed narrowing at the anastomosis, associated with a segmental doubling of flow velocity, and the mean portal venous flow decreased by approximately 20% in the first postoperative week. In conclusion, a wide range of abnormalities occurs in the vessels of liver transplant recipients, which were not associated with the development of vascular complications or affect patient management.

Blood Flow Velocity↗

PubMed2004

Vascular endothelial growth factor in diabetes induced early retinal abnormalities.

Increased vascular permeability and blood flow alterations are characteristic features of diabetic retinal microangiopathy. The present study investigated vascular endothelial growth factor (VEGF) and its interactions with endothelin (ET) 1 and 3, endothelial, and inducible nitric oxide synthase (eNOS, iNOS) in mediating diabetes induced retinal vascular dysfunction. Male Sprague Dawley rats with streptozotocin (STZ) induced diabetes, with or without VEGF receptor signal inhibitor SU5416 treatment (high or low dose) were investigated after 4 weeks of follow-up. Colour Doppler ultrasound of the ophthalmic/central retinal artery, retinal tissue analysis with competitive RT-PCR and microvascular permeability were studied. Diabetes caused increased microvascular permeability along with increased VEGF mRNA expression. Increased vascular permeability was prevented by SU5416 treatment. Diabetic animals showed higher resistivity index (RI), indicative of vasoconstriction with increased ET-1 and ET-3 mRNA expression, whereas eNOS and iNOS mRNA expressions were un-affected. SU5416 treatment corrected increased RI via increased iNOS in spite of increased ET-1, ET-3 and VEGF mRNA expression. Cell culture (HUVEC) studies indicate that in part, an SU5416 induced iNOS upregulation may be mediated though a MAP kinase signalling pathway. The present data suggest VEGF is important in mediating both vasoconstriction and permeability in the retina in early diabetes.

Animals↗

PubMed2004

Robot-assisted 3D-TRUS guided prostate brachytherapy: system integration and validation.

Current transperineal prostate brachytherapy uses transrectal ultrasound (TRUS) guidance and a template at a fixed position to guide needles along parallel trajectories. However, pubic arch interference (PAI) with the implant path obstructs part of the prostate from being targeted by the brachytherapy needles along parallel trajectories. To solve the PAI problem, some investigators have explored other insertion trajectories than parallel, i.e., oblique. However, parallel trajectory constraints in current brachytherapy procedure do not allow oblique insertion. In this paper, we describe a robot-assisted, three-dimensional (3D) TRUS guided approach to solve this problem. Our prototype consists of a commercial robot, and a 3D TRUS imaging system including an ultrasound machine, image acquisition apparatus and 3D TRUS image reconstruction, and display software. In our approach, we use the robot as a movable needle guide, i.e., the robot positions the needle before insertion, but the physician inserts the needle into the patient's prostate. In a later phase of our work, we will include robot insertion. By unifying the robot, ultrasound transducer, and the 3D TRUS image coordinate systems, the position of the template hole can be accurately related to 3D TRUS image coordinate system, allowing accurate and consistent insertion of the needle via the template hole into the targeted position in the prostate. The unification of the various coordinate systems includes two steps, i.e., 3D image calibration and robot calibration. Our testing of the system showed that the needle placement accuracy of the robot system at the "patient's" skin position was 0.15 mm+/-0.06 mm, and the mean needle angulation error was 0.07 degrees. The fiducial localization error (FLE) in localizing the intersections of the nylon strings for image calibration was 0.13 mm, and the FLE in localizing the divots for robot calibration was 0.37 mm. The fiducial registration error for image calibration was 0.12 mm and 0.52 mm for robot calibration. The target registration error for image calibration was 0.23 mm, and 0.68 mm for robot calibration. Evaluation of the complete system showed that needles can be used to target positions in agar phantoms with a mean error of 0.79 mm+/-0.32 mm.

Automation↗

PubMed2003

Heme oxygenase in the retina in diabetes.

INTRODUCTION: Heme oxygenase (HO) isoforms, HO-1, and HO-2, are responsible for heme breakdown to iron and carbon monoxide (CO). HO may respond to oxidative stress and may modulate the expression of vasoactive factors like nitric oxide (NO). Since diabetes induced oxidative stress may change HO, the present study examined whether diabetes is associated with HO alterations, its relationship with NO, endothelin-1(ET-1) and the functional significance. MATERIALS AND METHODS: Male SD rats with Streptozotocin induced diabetes were investigated after six-weeks. Poorly controlled diabetic animals were randomized to one of three treatment groups (n = 6 each group); a) untreated, b) HO-1 inhibitor SnPP-IX (50 micromol/kgIP/day), c) NO donor molsidomine (120 mg/L PO/day) and were compared with age and sex matched non diabetic control animals with or without SnPP-IX treatment. Color Doppler ultrasound analysis was used to determine retinal resistivity index (RI). mRNA for HO-1, HO-2, ET-1, eNOS and iNOS were analyzed with competitive RT-PCR. HO distribution in the retina was investigated by immunocytochemistry. RESULTS: Diabetic animals expressed lower body weight, higher blood glucose and increased glycated hemoglobin levels. HO-1 and HO-2 immuno-reactivity were identified in the retina. Diabetes induced increased RI was associated with up-regulation of both ET-1 and HO-1 mRNA expression but not eNOS or iNOS mRNA. Both SnPP-IX and molsidomine treatments prevented a diabetes increase of RI, in spite of increased ET-1 expression and were associated with increased iNOS mRNA. CONCLUSIONS: The present data suggests that the HO system is up-regulated in short term diabetes leading to HO and NO interactions which may modulate vascular function in the retina.

Animals↗

PubMedDate not supplied

Contributions of endothelin-1 and sodium hydrogen exchanger-1 in the diabetic myocardium.

BACKGROUND: Endothelin-1 (ET-1) and sodium hydrogen exchanger-1 (NHE-1) are important mediators of several disease processes affecting the heart, especially relating to myocardial ischemia. There is evidence that their actions may be interrelated. Their contributions to diabetic heart disease have not been extensively documented. Accordingly, the aim of this study was to investigate the interactive roles of ET-1 and NHE-1 in the pathogenesis of diabetic cardiomyopathy, a significant cause of morbidity in diabetic patients. METHODS: Streptozotocin-induced diabetic Sprague Dawley rats were treated with NHE-1 blocker cariporide or dual ET(A)/ET(B) blocker bosentan and were subsequently studied one, three and six months after induction of diabetes. These animals were compared with nondiabetic rats as well as with diabetic rats on poor blood glucose control. RESULTS: Diabetes leads to hyperglycemia, reduced body weight gain and increased glycated hemoglobin levels. These animals exhibited focal myocardial fibrosis and increased ejection fraction, in association with a tendency to increased left ventricular wall thickness and heart weight, after six months of follow-up, both bosentan and cariporide prevented these responses. Diabetes also caused significant increases in ET-1 mRNA and protein expression in the heart at all time points, which was further augmented by cariporide treatment for three months. Diabetes did not affect either mRNA or protein expression of NHE-1, although these did decrease in hearts of diabetic animals treated with bosentan for six months. CONCLUSIONS: These results indicate an important contribution of both ET-1 and NHE-1 in the pathogenesis of diabetic cardiomyopathy. These data suggest that NHE-1 may act as a downstream mediator in the production of ET-induced functional and structural changes in the myocardium in diabetes.

Animals↗

PubMedDate not supplied

The role of the sodium hydrogen exchanger-1 in mediating diabetes-induced changes in the retina.

BACKGROUND: The sodium hydrogen exchanger (NHE) is a transmembrane protein responsible for alkalinization and control of intracellular acidosis by the removal of hydrogen and the subsequent influx of sodium. Our investigation attempts to determine the role of NHE-1 in the pathogenesis of early retinal microangiopathy due to diabetes. METHODS: Diabetes was induced in male Sprague-Dawley rats with a single intravenous streptozotocin injection (65 mg/kg). To examine the duration-dependent changes in NHE-1 expression, retinas from 1-, 6- and 12-week diabetic animals were analyzed. To examine the functional consequences of NHE-1 inhibition in comparison with good blood glucose control, diabetic rats were randomly assigned to poorly controlled diabetic, well-controlled diabetic, poorly controlled diabetic with cariporide groups and were compared with nondiabetic controls after six weeks. Cariporide is an orally active inhibitor of NHE-1 (6000 ppm in rat chow). At the end of the treatment period, color Doppler ultrasound was used to determine the resistivity index (RI) of the central retinal artery. The mRNA expression of endothelin (ET) isoforms 1 and 3, inducible and endothelial nitric oxide synthase (iNOS and eNOS respectively) and NHE-1 were examined. NHE-1 distribution was localized with immunohistochemistry. RESULTS: All diabetic animals showed hyperglycemia, increased glycated hemoglobin and lower body weight gain compared to nondiabetic controls. Diabetes caused an increased RI, indicative of retinal vasoconstriction, which was corrected by both cariporide treatment and good glucose control. NHE-1 was localized in the endothelium of the retinal microvasculature and the neuronal and glial components. NHE-1 mRNA expression was unchanged after 1 week and increased after 6 and 12 weeks of diabetes. Furthermore, a diabetes-induced upregulation of ET-1 and ET-3 mRNA expression after six weeks was corrected with cariporide treatment. NHE-1 inhibition of diabetic animals upregulated iNOS mRNA levels, although expression of eNOS and iNOS mRNA were not altered in poorly controlled diabetes. Improved blood glucose control with higher doses of insulin also corrected diabetes-induced increased RI by upregulating eNOS and iNOS mRNA expression. CONCLUSIONS: The results of the study suggest that NHE-1 may be involved in the regulation of several vasoactive modulators that contribute to functional alterations in diabetic retinal microangiopathy.

Animals↗