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Biomedical subjects

Christopher M Zahn

Publications and source records attributed to Christopher M Zahn.

At least 19 recordsLinked to original sources
PubMed2005

Use of the placental perfusion model to evaluate transplacental passage of Trypanosoma cruzi.

OBJECTIVE: To determine whether Trypanosoma cruzi could be identified in placental cells in vitro and in placental tissue using a human ex vivo perfusion model. STUDY DESIGN: A placental cell line was incubated with trypomastigotes for progressive time periods. Trypomastigotes were also infused as a bolus into the maternal circulation of a placental perfusion model. Maternal and fetal perfusates, and placental tissue, were analyzed for parasitic DNA using polymerase chain reaction; perfused specimens were also examined histologically. RESULTS: Intracytoplasmic amastigotes were identified in trophoblast of the incubated cell line by 24-48 hours. Following placental perfusion, T cruzi DNA was identified in all postinoculation maternal perfusate samples and postinoculation placental tissue specimens; preinoculation controls were negative. CONCLUSION: This is the first description of the use of the human placental perfusion model to study congenital Chagas' disease, including the presence and time course of early parasitic invasion of the placenta.

Animals↗
PubMed2005

Creating an ideal objective structured clinical exam for an obstetrics and gynecology medical student clerkship.

OBJECTIVE: The objective of the study was to describe our experience with the Objective Structured Clinical Exam during the third-year obstetrics/gynecology clerkship. STUDY DESIGN: Our 8-station Objective Structured Clinical Exam is described in detail. We analyzed grades from the Objective Structured Clinical Exam for overall distribution, comparing among and between groups by year and among exam sites and correlating with the National Board of Medical Examiners subject exam and the final clerkship grades. RESULTS: The Objective Structured Clinical Exam is provided at 3 sites, 1 at a technically advanced simulation center. Most students (54.6%) received a grade of A; however, the mean grade from the Objective Structured Clinical Exam at the simulation center (3.41 on a 4-point grade-point average scale) was lower than that at the clinic sites (3.60, P = .005; 3.73, P < .001). Effect of rotation order was identified only in the first year. Grades from the Objective Structured Clinical Exam were positively but weakly correlated with National Board of Medical Examiners subject exam and final clerkship grades. CONCLUSION: An Objective Structured Clinical Exam in the obstetrics/gynecology clerkship can be administered with limited resources and provides a valuable assessment method.

Clinical Clerkship↗
PubMed2005

Reflex high-risk human papillomavirus testing for women with atypical squamous cells of undetermined significance in cytologic smears: effects since implementation in a large clinical practice.

Reflex high-risk human papillomavirus (HPV) testing often is used in the management of women with atypical squamous cells of undetermined significance identified in cervicovaginal screening. Following implementation of reflex testing, our laboratory processed 8,022 specimens during a 20-month period; sufficient material was available for testing in 7,334 specimens. High-risk HPV was detected in 34.10% of these specimens. Detection rates varied with age, with positive rates as high as 58.46% in women 20 years old or younger, decreasing to 14.58% in women older than 35 years. The detection rate, categorized in 5-year age increments, showed a significant decrease until after 35 years, when the rate remained fairly constant (P < .0001). The detection rate decreased over the time of the study. These results demonstrate that high-risk HPV detection might vary according to the age mix of the population tested and the interval after implementation of testing.

Adult↗
PubMed2004

Incorporating problem-based learning into an obstetrics/gynecology clerkship: impact on student satisfaction and grades.

OBJECTIVE: The purpose of this study was to describe the effect of the problem-based learning method on student grade and on student and faculty satisfaction. STUDY DESIGN: The problem-based learning method was instituted at 2 of 5 obstetrics/gynecology clerkship sites. Students and faculty were surveyed, with the use of a Likert scale, regarding aspects of satisfaction with the clerkship. Responses were compared according to problem-based learning usage. Student performance was also assessed according to problem-based learning usage, with a comparison of several grade components. Statistical analysis involved t-tests and Kendall's tau-C. RESULTS: For the year that was assessed, 54 of 156 students used the problem-based learning method. Mean student satisfaction responses were significantly higher for students who used the problem-based learning method. Faculty satisfaction was also significantly higher for the problem-based learning method, compared with other teaching methods. Mean scores on the National Board of Medical Examiners subject examination were higher for problem-based learning but did not reach statistical significance. Grade distribution was not significantly different for the groups. CONCLUSION: The problem-based learning method was associated with improved student and faculty satisfaction and did not affect student grades negatively.

Adult↗
PubMed2004

Variation in medical student grading criteria: a survey of clerkships in obstetrics and gynecology.

OBJECTIVE: Our purpose was to assess how obstetrics/gynecology clerkships incorporate methods of student assessment into grades. STUDY DESIGN: A survey that included a broad range of assessment methods was distributed to obstetrics/gynecology clerkship directors registered with the Association of Professors of Gynecology and Obstetrics. Respondents were asked to indicate the methods used for assessment and to indicate the weight assigned to these methods in determining a student grade. RESULTS: Of the 146 surveys distributed, there were 53 respondents (36.4%). The most common methods of subjective assessment included evaluation of patient presentation skills and performance on ward rounds. The 2 most commonly used objective methods, general assessment of cognitive knowledge and the National Board of Medical Examiners Subject Examination in Obstetrics and Gynecology, generally accounted for 75% of the final grade, although these same 2 components also had the widest range of assigned weights reported. CONCLUSION: Assessment methods and incorporation into a final grade vary widely across obstetrics/gynecology clerkships.

Adult↗
PubMed2004

Vaginal metastasis and thrombocytopenia from renal cell carcinoma.

BACKGROUND: Vaginal cancer represents approximately 1-2% of genital tract malignancies. Most cases represent metastasis from the cervix, endometrium, or colon. Metastasis of renal cell carcinoma to the vagina is extremely rare. CASE: A 58-year-old female presented with a bleeding vaginal lesion. Laboratory studies revealed severe thrombocytopenia, and radiological studies revealed a left renal mass; excision was consistent with metastatic renal cell carcinoma. A subsequent nephrectomy confirmed renal cell carcinoma. Postoperatively, the patient underwent immunotherapy and the thrombocytopenia resolved. CONCLUSION: We report the first case of metastatic renal cell carcinoma presenting as a vaginal metastasis with thrombocytopenia as a paraneoplastic manifestation. Renal cell carcinoma must be in the differential diagnosis of a clear cell neoplasm in a postmenopausal woman, particularly with systemic symptoms suggestive of a paraneoplastic syndrome.

Carcinoma, Renal Cell↗
PubMed2004

Retroperitoneal müllerian carcinosarcoma associated with endometriosis: a case report.

BACKGROUND: Mixed müllerian tumors are rare malignancies of the female genital tract and extremely uncommon in extragenital sites. CASE: A 71-year-old woman presented with a 3-month history of left-sided pelvic pain. Significant history included total abdominal hysterectomy and bilateral adnexectomy performed 19 years earlier for benign indications; she had no history of endometriosis. Bimanual exam and pelvic ultrasonography demonstrated a 6 x 5 x 6 cm complex mass in the left pelvis. Exploratory laparotomy revealed a retroperitoneal mass encasing the left ureter. The mass was debulked, necessitating resection of the distal ureter and ureteroneocystotomy. Histopathology demonstrated carcinosarcoma associated with endometriosis. CONCLUSION: Extragenital carcinosarcoma is a rare malignancy, with only one well-documented case associated with peritoneal endometriosis. We report a case of an extragenital retroperitoneal carcinosarcoma associated with endometriosis.

Aged↗
PubMed2003

Low-dose oral contraceptive effects on thromboelastogram criteria and relationship to hypercoagulability.

OBJECTIVE: The study was undertaken to assess hypercoagulability, by using thromboelastography, in women who use low-dose oral contraceptives (OCs). STUDY DESIGN: Forty-three women using low-dose OCs (<or=35 microg ethinyl estradiol) underwent thromboelastography before starting OCs and again during the third month of OC use. Prior and 3-month mean values of four thromboelastogram parameters (maximum amplitude [MA], K time, alpha angle, and R time) were compared by using paired t tests. Comparison according to progestin type was also performed with unpaired t tests. RESULTS: Prior versus 3-month values for MA, alpha, and K were not significantly different (P values-K: 0.8; alpha:.34; MA: 0.49); power was adequate to detect small differences. The 3-month R time was decreased compared with pre-OC values (P =.025), although the magnitude of this change was not characteristic of hypercoagulability. Comparison according to progestin type demonstrated no difference. CONCLUSION: We found no significant trend toward hypercoagulability in women who used low-dose OCs and who otherwise had no known thromboembolic risks.

Adolescent↗