Biomedical subjects

Bobby Shayegan

Publications and source records attributed to Bobby Shayegan.

4 recordsLinked to original sources

PubMed2026

Standardized visual overlays enhance laparoscopic instruction: A mixed-methods evaluation.

Effective communication during laparoscopic procedures is frequently undermined by spatial disorientation and inconsistent terminology between instructors and trainees. This study examined whether standardized visual overlays on endoscopic monitors could enhance communication and learning. We conducted a three-phase mixed-methods study: qualitative observation of 20 laparoscopic teaching cases; a randomized trial of 63 second-year medical students assigned to control, clock, or alphanumeric grid (AG) overlays during three trials of a standardized transfer task; and intraoperative implementation in 44 cases (30 AG, 14 clock) with post-case surveys and qualitative feedback. In simulation, the clock overlay produced the fastest completion times, whereas the AG yielded the lowest error scores, and both overlays outperformed the control. Intraoperatively, the AG was rated higher than the clock for communication clarity, spatial orientation, perceived operative efficiency, and trainee confidence. Standardized visual overlays, particularly the AG, appear to support intraoperative teaching by providing a shared spatial frame of reference.

Laparoscopy↗

PubMed2007

The anterior layer of Denonvilliers' fascia: a common misconception in the laparoscopic prostatectomy literature.

PURPOSE: Incision of the anterior layer of Denonvilliers' fascia is commonly cited as a key step in successful dissection of the vasa deferentia and seminal vesicles from the posterior bladder neck during laparoscopic radical prostatectomy. However, anatomical descriptions do not support the presence of Denonvilliers' fascia anterior to the seminal vesicles. To address this inconsistency we performed a detailed anatomical study of tissue planes encountered during laparoscopic dissection of the posterior bladder neck. MATERIALS AND METHODS: To grossly characterize the tissue planes encountered during laparoscopic posterior bladder neck dissection, ex vivo dissections were performed on 4 separate cystoprostatectomy specimens. Biopsies of the representative areas were obtained from 20 consecutive laparoscopic radical prostatectomy specimens by 2 dedicated uropathologists. RESULTS: Following incision into the posterior bladder neck mucosa, longitudinally oriented fibers were readily visualized, extending from bladder neck to prostate base. Histologically this anatomical landmark represents the fusion of 2 separate tissue layers, that is an inner lamella composed of longitudinally disposed smooth muscle fibers in continuation with the longitudinal fascia of the bladder detrusor (medial fascicle of the detrusor running in between the ureters) and an outer lamella composed of fibroadipose tissue in continuation with the bladder adventitia. CONCLUSIONS: Our anatomical and histological analysis refutes the prevailing belief in the laparoscopic literature that the longitudinal muscle fibers identified during dissection of the posterior bladder neck represent the anterior layer of Denonvilliers' fascia. They correspond to the posterior longitudinal fascia of the detrusor muscle that is externally upholstered by the bladder adventitia.

Fascia↗

PubMed2006

Predicting teratoma in the retroperitoneum in men undergoing post-chemotherapy retroperitoneal lymph node dissection.

PURPOSE: The biological potential of teratoma remains unpredictable, therefore identifying its presence in the retroperitoneum remains important. We evaluated patients undergoing post-chemotherapy retroperitoneal lymph node dissection for nonseminomatous germ cell tumors to determine predictors of teratomatous elements in the retroperitoneum. MATERIALS AND METHODS: We identified 532 patients from 1989 to 2003 who underwent retroperitoneal lymph node dissection following chemotherapy for nonseminomatous germ cell tumors at our institution. Multiple clinical and pathological variables were reviewed from our prospective retroperitoneal lymph node dissection database. A logistic regression model was designed based on preoperative variables to predict the presence of teratomatous elements in the retroperitoneal lymph node dissection specimen. RESULTS: Of the 532 patients in our series 450 (85%) received only induction chemotherapy and 82 (15%) required salvage chemotherapy. Teratomatous elements were identified in the orchiectomy specimen in 42% of patients. Retroperitoneal nodal pathology revealed teratomatous elements in 235 (44%) patients and only teratoma in 210 (40%) patients. By multivariate analysis testicular yolk sac tumor (p = 0.046), teratoma in the orchiectomy specimen (p <0.005), relative change in nodal size before and after chemotherapy (p <0.005), and no requirement for salvage chemotherapy (p = 0.03) were independent predictors for the presence of teratoma in the retroperitoneum. CONCLUSIONS: Teratoma remains a common histological finding in the retroperitoneal lymph nodes following chemotherapy. We have identified several pre-retroperitoneal lymph node dissection variables that predict the finding of teratoma in the retroperitoneum for men treated with chemotherapy for metastatic nonseminomatous germ cell tumors.

Antineoplastic Agents↗

PubMed2002

Prevalence of abnormal sperm DNA denaturation in fertile and infertile men.

OBJECTIVES: To examine the prevalence of abnormal sperm DNA denaturation (DD), a marker of sperm DNA integrity, in a group of fertile and infertile men. METHODS: Eighty-eight nonazoospermic, infertile men and 13 fertile men underwent standard semen analysis and acridine orange sperm DNA integrity studies. Standard semen parameters (sperm concentration, motility, and morphology) and sperm DNA integrity (expressed as the percentage of spermatozoa with DD) were measured. RESULTS: Of the 88 infertile men, 13 had completely normal semen parameters and the remaining 75 had at least one abnormal semen parameter. The mean (+/-SE) sperm DD level was significantly lower in the population of infertile men with normal semen parameters compared with those having abnormal parameters (11.1% +/- 3.7% versus 23.1% +/- 1.8%, respectively, P <0.001). Only 1 (8%) of the 13 men with normal semen parameters had elevated sperm DD (greater than 30%, verified on two separate analyses) compared with 13 (17%) of the 75 infertile men with abnormal semen parameters (P >0.05). None of the fertile controls had elevated sperm DD. We observed significant inverse correlations between the sperm DD and sperm motility, morphology, and concentration (P <0.001). CONCLUSIONS: Our data show that sperm DD negatively correlates with standard semen parameters and that an isolated abnormality of sperm DD, a marker of sperm DNA integrity, is uncommon in infertile men. Additional studies are needed to support the notion that isolated abnormalities of sperm DNA integrity may represent a new diagnosis for men with unexplained infertility.

Confidence Intervals↗