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J Schaffer

Publications and source records attributed to J Schaffer.

16 recordsLinked to original sources
PubMed2002

Incidence, risk factors and morbidity of unintended bladder or ureter injury during hysterectomy.

To determine the incidence, risk factors and morbidity of unintended operative injury to the bladder or ureter during hysterectomy, a retrospective case-control study of women with these injuries from 1 January 1993 to 1 January 1998 was performed. The incidence of bladder and ureter injury, respectively, was 0.58% and 0.35% for abdominal hysterectomy, 1.86% and 0% for vaginal hysterectomy, and 5.13% and 1.71% for hysterectomies performed for obstetric indications. Women with injury during abdominal hysterectomy were found to have greater blood loss, longer operative times, longer postoperative stays, more febrile morbidity, and more frequent transfusions. Similar trends were seen for other hysterectomy types. The incidence of operative bladder or ureter injury is relatively low. However, even when recognized, these individuals experience greater operative and postoperative morbidity. This highlights the importance of surgical technique directed toward minimization of these injuries, and careful intra- and postoperative surveillance aimed at early detection.

Adult↗
PubMed2001

An experimental comparison of the maximum likelihood estimation and nonlinear least-squares fluorescence lifetime analysis of single molecules.

Two procedures based on the weighted least-squares (LS) and the maximum likelihood estimation (MLE) method to confidently analyze single-molecule (SM) fluorescence decays with a total number (N) of 2,500-60,000 counts have been elucidated and experimentally compared by analyzing measured bulk and SM decays. The key observation of this comparison is that the LS systematically underestimates the fluorescence lifetimes by approximately 5%, for the range of 1,000-20,000 events, whereas the MLE method gives stable results over the whole intensity range, even at counts N less than 1,000, where the LS analysis delivers unreasonable values. This difference can be attributed to the different statistics approaches and results from improper weighting of the LS method. As expected from theory, the results of both methods become equivalent above a certain threshold of N detected photons per decay, which is here experimentally determined to be approximately 20,000. In contrast to the bulk lifetime distributions, the SM fluorescence lifetime distributions exhibit standard deviations that are sizably larger than the statistically expected values. This comparison proves the strong influence of the inhomogenuous microenvironment on the photophysical behavior of single molecules embedded in a 10-30-nm thin polymer layer.

Journal Article↗
PubMed2001

Data registration and selective single-molecule analysis using multi-parameter fluorescence detection.

A general strategy to identify and quantify sample molecules in dilute solution employing a new spectroscopic method for data registration and specific burst analysis denoted as multi-parameter fluorescence detection (MFD) was recently developed. While keeping the experimental advantage of monitoring single molecules diffusing through the microscopic open volume element of a confocal epi-illuminated set-up as in experiments of fluorescence correlation spectroscopy, MFD uses pulsed excitation and time-correlated single-photon counting to simultaneously monitor the evolution of the four-dimensional fluorescence information (intensity, F; lifetime, tau; anisotropy, r; and spectral range, lambda(r)) in real time and allows for exclusion of extraneous events for subsequent analysis. In this review, the versatility of this technique in confocal fluorescence spectroscopy will be presented by identifying freely diffusing single dyes via their characteristic fluorescence properties in homogenous assays, resulting in significantly reduced misclassification probabilities. Major improvements in background suppression are demonstrated by time-gated autocorrelation analysis of fluorescence intensity traces extracted from MFD data. Finally, applications of MFD to real-time conformational dynamics studies of fluorescence labeled oligonucleotides will be presented.

Fluorescent Dyes↗
PubMed2000

Urinary incontinence and pelvic organ prolapse in women with Marfan or Ehlers Danlos syndrome.

OBJECTIVE: This study was undertaken to determine the prevalence of urinary incontinence and pelvic organ prolapse in a cohort of women with either Marfan syndrome or Ehlers-Danlos syndrome. STUDY DESIGN: Female patients with either Marfan syndrome or Ehlers-Danlos syndrome were identified through a medical records search at two urban hospitals. Each patient's medical record was reviewed, and the history of pelvic organ prolapse and urinary incontinence was obtained through telephone interview. RESULTS: Twelve women with Marfan syndrome were identified. Among these women 5 (42%) reported a history of urinary incontinence and 4 (33%) reported a history of pelvic organ prolapse. Eight women with Ehlers-Danlos syndrome were identified. Among these women 4 (50%) reported a history of urinary incontinence and 6 (75%) reported a history of pelvic organ prolapse. CONCLUSIONS: Women with Marfan or Ehlers-Danlos syndrome have high rates of urinary incontinence and pelvic organ prolapse. This finding supports the hypothesized etiologic role of connective tissue disorders as a factor in the pathogenesis of these conditions.

Adult↗
PubMed2000

Comparison of mailed vs. Internet applications of the Delphi technique in clinical informatics research.

The Delphi technique provides a means of assessing the judgments of groups of experts without the necessity of having these experts meet together. The technique has been used in health care since the mid-1970s, and has just recently become more common in clinical informatics research. As informatics develops as a specialty, it is logical to consider information technology solutions to research as well as clinical practice problems. The overall purpose of this methodology presentation is to compare a mailed vs. Internet application of the Delphi technique for clinical informatics research. Specifically, this presentation will provide: 1) an overview of the Delphi technique, and 2) a methodological comparison of two research applications of the Delphi technique. Results of the studies will be presented elsewhere.

Computer Communication Networks↗
PubMed1997

Arthroscopic microdiscectomy: comparison of preoperative and postoperative imaging studies.

Forty-three patients with symptomatic lumbar disc herniations underwent paralumbar arthroscopic disc extraction by a uniportal or biportal approach and postoperative imaging studies. Thirty-one patients were subjected to immediate postoperative computed tomography (CT) at the operative site. The other 12 underwent magnetic resonance imaging (MRI at varying times postoperatively. Images obtained before and after surgery were magnified; the herniation area (H) and the spinal canal area (C) were measured by computerized digitization. The H/C ratio was calculated, and the percentage of canal clearance was obtained in each case. Immediate postoperative CT imaging in 16 of 18 patients with subligamentous and extraligamentous nonmigrated herniation showed a significant change in the external geometry of the annulus and canal clearance (75% to 100% canal clearance). Less compelling change in the postoperative CT images was unexpectedly seen with extraforaminal and foraminal herniations. This result may be attributable to limitations in our study methodology and not to inadequate decompression. Follow-up MRI on these patients within 8 weeks postoperatively did eventually show significant change in two cases that were initially not significant. This study confirms that the arthroscopic microdiscectomy technique effectively extracts herniated disc fragments and alters posterior annular contour, including removal of sequestered pieces.

Adult↗
PubMed1997

No evidence of KSHV/HHV-8 in mycosis fungoides or associated disorders.

The recently discovered human virus known as Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus-8 (HHV-8) has been associated with body-cavity-based lymphomas in AIDS patients. It is most closely related to two other herpesviruses, the Epstein-Barr virus and herpesvirus saimiri, which are known to be associated with lymphomas in humans and nonhuman primates, respectively. To determine whether KSHV/HHV-8 is involved in the pathogenesis of mycosis fungoides (MF) and related disorders, we used a genomic PCR assay followed by confirmatory Southern blot analysis with a nested oligonucleotide probe to analyze cases for the presence of this virus. The specimens studied included fresh-frozen lesional tissues obtained from 16 patients with MF, seven with lymphomatoid papulosis, seven with primary cutaneous CD30+ large cell lymphoma of T-cell lineage, and five with Hodgkin's disease. Two T-cell tumor lines were also studied: MT4 (derived from a patient with adult T-cell leukemia/lymphoma) and Jurkat (derived from a patient with T-cell acute lymphoblastic leukemia). All cases were uniformly negative for KSHV/HHV-8, whereas Kaposi's sarcoma-positive controls and human beta-globin DNA integrity controls were appropriately positive. These findings provide strong evidence against a role for KSHV/HHV-8 in the pathogenesis of MF or associated lymphoproliferative disorders.

Adult↗
PubMed1996

Evidence against a role for human T-cell lymphotrophic virus type I (HTLV-I) in the pathogenesis of American cutaneous T-cell lymphoma.

We used a standard polymerase chain reaction (PCR)/Southern blot assay (sensitivity > 10(-5)) to detect human T-cell lymphotrophic virus type I (HTLV-I) proviral pX, pol, and env genes in the lesional skin of 42 American patients with cutaneous T-cell lymphoma (CTCL). As in some prior reports using similar methods, a variable proportion of PCR tests were positive (seven of 42 for pX, three of 42 for pol, and two of 37 for env), resulting in an overall positive test rate of 12 of 121 (10%). To determine the significance of these positive test results, we performed several additional studies. D1S80 polymorphism analysis of CTCL cases and HTLV-I PCR analysis of non-CTCL dermatosis controls showed no evidence that positive PCR tests resulted from sample mislabeling, gross HTLV-I contamination, or human endogenous retroviruses. We then modified the standard PCR assay to incorporate ultraviolet (UV) light to destroy low-level PCR contamination. With this modified assay (sensitivity > 10(-5)), only three of 12 previously positive cases were still positive, suggesting that the earlier positives were due to trace contamination of PCR reagents or trace contamination of sample DNA. This interpretation was also supported by: (i) a match between pX and pol sequences cloned from one PCR-positive specimen and the MT4-positive control, (ii) our inability to confirm HTLV-I in any PCR-positive case using genomic dot blotting (sensitivity > 10(-2)), and (iii) negative PCR results when new samples from two of the remaining positive cases were analyzed. Finally, we used our modified UV/ PCR/Southern blot assay to test an additional 28 cases of American CTCL for pX. All of them were negative. Although these studies of 70 cases of American CTCL do not exclude the possibility that another virus is involved in the pathogenesis of this disease, they provide strong evidence against a role for HTLV-I. Furthermore, they emphasize the need for special strategies to control for false-positive PCR tests that can result from even trace levels of contamination with viral DNA. As a consequence, associations between diseases and viruses should be viewed skeptically if they are based primarily on conventional PCR data.

Base Sequence↗