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Biomedical subjects

R Rosenthal

Publications and source records attributed to R Rosenthal.

At least 19 recordsLinked to original sources
PubMed2006

Can skills assessment on a virtual reality trainer predict a surgical trainee's talent in laparoscopic surgery?

BACKGROUND: A number of studies have investigated several aspects of feasibility and validity of performance assessments with virtual reality surgical simulators. However, the validity of performance assessments is limited by the reliability of such measurements, and some issues of reliability still need to be addressed. This study aimed to evaluate the hypothesis that test subjects show logarithmic performance curves on repetitive trials for a component task of laparoscopic cholecystectomy on a virtual reality simulator, and that interindividual differences in performance after considerable training are significant. According to kinesiologic theory, logarithmic performance curves are expected and an individual's learning capacity for a specific task can be extrapolated, allowing quantification of a person's innate ability to develop task-specific skills. METHODS: In this study, 20 medical students at the University of Basel Medical School performed five trials of a standardized task on the LS 500 virtual reality simulator for laparoscopic surgery. Task completion time, number of errors, economy of instrument movements, and maximum speed of instrument movements were measured. RESULTS: The hypothesis was confirmed by the fact that the performance curves for some of the simulator measurements were very close to logarithmic curves, and there were significant interindividual differences in performance at the end of the repetitive trials. CONCLUSIONS: Assessment of perceptual motor skills and the innate ability of an individual with no prior experience in laparoscopic surgery to develop such skills using the LS 500 VR surgical simulator is feasible and reliable.

Adult↗
PubMed2005

[Function of bestrophin].

Clarification of the function of bestrophin, the gene product of VMD2, establishes a basis for the understanding of the pathomechanisms leading to Best's vitelliform macular degeneration. Studies of heterologously expressed bestrophin showed that bestrophin can function as a Cl(-) channel. All four known bestrophins were found to display Cl(-) channel activity. A loss in Cl(-) channel function would elegantly explain the development of the leading symptom for Best's disease, the reduction of the light peak amplitude in the patient's electro-oculogram. However, there are still gaps in the chain of evidence demonstrating that bestrophin is a Cl(-) channel, and this hypothesis is inconsistent with newly published follow-up observations. In an alternative hypothesis bestrophin appears as a regulator of voltage-dependent Ca(2+) channels assuming an indirect involvement of bestrophin in the generation of the light peak. Further studies on either bestrophin-deficient mice or transgenic mice will show that either one of the hypotheses is right or maybe both will be proven correct, showing bestrophin as a Cl(-) channel and Ca(2+) channel regulator.

Bestrophins↗
PubMed2005

Extraanatomic lateral reconstruction to the popliteal vessels.

OBJECTIVES: To describe the lateral approach to the popliteal artery in reconstructions after soft tissue sarcoma resection in the thigh. DESIGN: Case reports. Subjects Four patients with soft tissue sarcoma. METHODS: Extraanatomic reconstruction of the resected artery and vein in the medial part of the thigh was performed. Vessel reconstruction was performed before tumor resection to avoid leg ischemia. RESULTS: In all four patients the artery was replaced by using the contralateral saphenous vein, while the femoral vein was replaced in two cases using e-PTFE. Post-operative complications included one large lymphatic collection and a deep wound infection. Arterial primary graft patency was 100% after 1-7 years. Patency of the e-PTFE-venous graft was 0% without further consequences. CONCLUSIONS: The extraanatomic lateral replacement of the vessels in the thigh is an elegant method in difficult vascular reconstructions after soft tissue sarcoma resection or debridement for deep vascular infections.

Adult↗
PubMed2004

Effects of colonoscopy on intracranial pressure: observation in a large animal model.

BACKGROUND AND STUDY AIMS: Increased intra-abdominal pressure has been associated with increased intracranial pressure. Bowel insufflation during colonoscopy may increase the intra-abdominal pressure. It was hypothesized that colonoscopy may be associated with intracranial pressure elevation subsequent to an elevation in intra-abdominal pressure. MATERIALS AND METHODS: Colonoscopy was carried out in seven anesthetized pigs, and the colonoscope was advanced up to 60 cm from the anal verge. Insufflation was used to allow safe advancement of the colonoscope and to allow visualization of the colon, in the same way as in the procedure performed in humans. Intra-abdominal pressure was measured by determining the hydrostatic pressure in the urinary bladder. A subarachnoid screw was used to monitor intracranial pressure. The mean arterial blood pressure and intra-abdominal venous pressure were directly monitored via the femoral vessel access; all parameters were recorded before and during colonoscopy. RESULTS: A statistically significant elevation in intracranial pressure was demonstrated during colonoscopy. The average increase in intracranial pressure was 3.1 mm Hg. The intra-abdominal pressure and intra-abdominal venous pressure were also significantly elevated during the procedure. CONCLUSIONS: Colonoscopy may increase intracranial pressure due to an increase in intra-abdominal pressure. This may have clinical implications when colonoscopy is conducted in patients with brain pathology associated with high intracranial pressure.

Anesthesia, General↗
PubMed2003

Technical considerations in laparoscopic resection of gastric neoplasms.

BACKGROUND: The purpose of this study was to determine the use of different laparoscopic approaches in the management of gastric neoplasms based on tumor type and location. METHODS: We retrospectively reviewed the records of seven patients (3 men and 4 women) with 11 gastric lesions who were referred to our facility between March 2000 and October 2001 for laparoscopic excision of gastric neoplasms. RESULTS: Two patients had gastrointestinal stromal lesions (3 lesions); two patients had hyperplastic polyps (3 lesions); one patient had carcinoid tumor (2 lesions); one patient had a carcinoma in situ and an adenoma; and one patient had an ectopic pancreas. Extraluminal laparoscopic wedge resection was used in four patients with lesions at the anterior gastric wall or along the lesser or greater curvature. Intragastric excision was used in two patients with small posterior wall lesions, and a transgastrotomy approach was used in one patient with a posterior wall lesion that could not be removed by the intragastric approach. All the lesions were completely excised with clear margins. The median hospital stay was 3 days. Complications developed in two patients. One patient presented with a perforated ulcer 2 weeks after surgery, and a second patient had postoperative pyloric edema that resolved with conservative treatment. CONCLUSIONS: The use of different laparoscopic approaches based on gastric neoplasm type and location facilitates tumor access and resection.

Adenoma↗
PubMed2003

Peritoneal mesothelioma after environmental asbestos exposure.

Mesothelioma are primary malignant neoplasms of the serous membranes. They usually involve the pleura and rarely the pericardium, the peritoneum and the tunica vaginalis testis. About 90% are associated with exposure to asbestos. The exposure is generally occupational, an environmental inhalation of asbestos and asbestiform fibers in areas in Turkey has been observed and presents a major health problem. This report of a patient from Anatolia with peritoneal mesothelioma after environmental exposure outlines the importance of considering this pathology in the differential diagnosis of a Turkish patient presenting with ascites.

Adult↗
PubMed2003

Determination of hemoglobin levels in the finger using near infrared spectroscopy.

We previously demonstrated that near-infrared spectroscopy can be used to measure blood flow. The spectrum of blood is dominated by hemoglobin. Therefore, it should be possible to determine the concentration of hemoglobin in tissue using near-infrared transmittance. We attempted to do this in the finger using a unique handheld multiple wavelength spectrophotometer. We took samples from 73 subjects and performed repeat measurements in several subjects. Hemoglobin level was determined at the time of near-infrared measurement. We performed correlation analysis between the hemoglobin values and the absorbance values. There was a strong correlation between hemoglobin levels and the 14 wavelengths (r = 0.738, n = 121, SEE = 1.7). We categorized the patients by hemoglobin level as either normal (12-16 g/dl), mildly anemic (10-12 g/dl), or moderately anemic (<10 g/dl). There were 21 patients in the low hemoglobin group, 29 in the middle range, and 23 in the normal range. The mean hemoglobin levels were 8.4 +/- 0.3 g/dl for the low group, 10.9 +/- 0.1 g/dl for the mildly anemic group, and 13.8 +/- 0.3 g/dl for the group with normal hemoglobin. There was a clear separation of absorbance values among the three groups. The major differences seen were in the midrange of the spectrum. It is encouraging that this first study of hemoglobin measurement yielded data permitting a discrimination of hemoglobin levels. It is hoped that future refinements will lead eventually to a non-invasive technique for the measurement of blood hemoglobin concentration.

Anemia↗
PubMed2002

Laparoscopic total mesorectal excision.

After total mesorectal excision for rectal cancer was introduced in 1982, local recurrence rates decreased to 5%. These results were found to be reproducible; therefore, the technique became standard for the treatment of rectal cancer. Laparoscopic surgery for curable colorectal malignancy is still considered investigational. Indeed, the United States National Cancer Institute (NCI) trial excludes rectal carcinoma. The application of laparoscopy to rectal carcinoma must compete with total mesorectal excision, which has obtained favorable results in the last decade. In this review, we assess the adequacy of laparoscopic total mesorectal excision, describe the techniques (both anterior resection and abdominoperineal resection), and discuss their potential advantages.

Abdomen↗
PubMed2002

Intestinal ischemia after bushmaster (Lachesis muta) snakebite--a case report.

After a snakebite by the Costa Rican bushmaster Lachesis stenophrys, a 64-year-old patient developed cardiovascular shock and coagulopathy. After intensive care and antivenom treatment, he was discharged after 4 days but had to be hospitalised again 3 days later because of abdominal pain and bowel obstruction. An emergency laparotomy revealed a necrotic ileum and caecum, and an obstruction of the superior mesenteric artery. Until now, this type of intestinal ischemic complication after a snakebite has not been reported in the literature. The effects of bushmaster venom are discussed.

Animals↗
PubMed2002

[Laparoscopic and conventional cholecystectomy. Didactic concept for training and introduction of laparoscopic cholecystectomy and preventing complications].

AIM: This study has assessed the suitability of an educational concept for the introduction and training of laparoscopic cholecystectomy, a newly established operational procedure, within an university teaching hospital with a large number of surgeons. PATIENTS AND METHODOLOGY: Since introduction of the first laparoscopic cholecystectomy all cholecystectomies were prospectively assessed over a period of two years (from May 1990 till May 1992). The educational concept applied was such that a given surgeon would first receive training from an instructor for 15 procedures and then assume responsibility for instruction of a subsequent trainee. RESULTS: In two years 355 patients underwent cholecystectomy. 60% of the operations were performed laparoscopically and 40% of the operations performed openly. During the two year period 13 surgeons were trained in the new technique, with an average of 16 operations per surgeon. Throughout the introductory phase there were no serious complications, and in particular no damage to the bile duct. DISCUSSION: The advantage of this introductory training phase has repeatedly been subject of discussion in the literature. In the meanwhile guidelines from specialist bodies and national institutions exist for regulating the education of new surgical techniques. In the past few years introduction to new techniques has gradually shifted toward training on the skill-stations and virtual reality trainers. CONCLUSION: The described educational concept for the introduction and training of laparoscopic cholecystectomy has been well approved and accepted since the early 90's.

Cholecystectomy↗
PubMed2001

The relationship of depression and stressors to immunological assays: a meta-analytic review.

This is a broad meta-analysis of the relations of both depression and stressors to immunological assays. The number of study samples (greater than 180) and measures (greater than 40) is much more extensive than any so far. Analyses are done by both fixed and random effects. By a fixed-effects analysis, both major depression and naturally occurring acute stressors are associated with (1) an overall leukocytosis, (2) mild reductions in absolute NK-cell counts and relative T-cell proportions, (3) marginal increases in CD4/CD8 ratios, and (4) moderate decreases in T- and NK-cell function. However, the degree of heterogeneity of the studies' results raises questions about their robustness. Therefore, we also did the first random effects analysis to estimate what is likely to appear in future studies. For depression, the analysis showed the immunological correlates included (1) an overall leukocytosis, manifesting as a relative neutrophilia and lymphoenia; (2) increased CD4/CD8 ratios; (3) increased circulating haptoglobin, PGE(2), and IL-6 levels; (4) reduced NK-cell cytotoxicity; and (5) reduced lymphocyte proliferative response to mitogen. For stressors, the random effects analysis showed that future studies are likely to find the following effects: (1) an overall leukocytosis, manifesting as an absolute lymphocytosis; (2) alterations in cytotoxic lymphocyte levels, CD4/CD8 ratios, and natural killer cell cytotoxicity with the direction of change depending on the chronicity of the stressor; (3) a relative reduction of T-cell levels; (3) increased EBV antibody titers; (4) reduced lymphocyte proliferative response and proportion of IL-2r bearing cells following mitogenic stimulation; and (5) increased leukocyte adhesiveness. The random-effects analysis revealed that for both major depression and naturally occurring stressors the following effects are shared: leukocytosis, increased CD4/CD8 ratios, reduced proliferative response to mitogen, and reduced NK cell cytotoxicity. The implications for these findings for disease susceptibility and the pathophysiology of these conditions is discussed.

Biomarkers↗
PubMed2001

A prospective randomized trial of different laparoscopic gastric banding techniques for morbid obesity.

BACKGROUND: Slippage of the stomach is the most common postoperative complication after laparoscopic adjustable silicone gastric banding (LASGB) for morbid obesity. Retrogastric placement (RGP) of the band through the lesser sac can cause posterior slippage Incomplete suturing often is responsible for anterior slippage. A randomized prospective study was constructed to determine whether laparoscopic esophagogastric placement (EGP) is associated with a lower incidence of postoperative slippage and pouch dilation than RGP. METHODS: Morbid obese patients presenting for LASGB were randomized to undergo either an EGP (n = 50) or an RGP (n = 51). Patients were blinded to which procedure they underwent, and follow-up date were obtained by a blinded independent investigator. Standardized clinical and radiologic controls were used to assess pouch enlargement and slippage. RESULTS: Operating time was similar for the two procedures (54.5 min for EGP vs 58 min for RGP). There was no significant difference in postoperative weight loss (34 kg after EGP vs 37 kg after RGP within 12 months), esophagus dilation, or postoperative quality of life. There were two postoperative slippages and one pouch dilation in the RGP group and no postoperative complication in the EGP group. CONCLUSIONS: The placement of a LAP-BAND adjustable gastric banding system by the EGP technique is safe and results in a lower frequency of postoperative complications than its placement by the RGP technique. Clear anatomic landmarks are a benefit to education and to the learning curve for LASGB.

Adolescent↗
PubMed2001

[Video-laparoscopic placement of adjustable gastric banding (lap-band) in the treatment of morbid obesity. Preliminary results after 407 interventions].

INTRODUCTION: Morbid obesity is the most frequent nutritional disorder in developed countries. Bariatric surgery is one option for the definitive treatment of this disorder. We present 407 patients who underwent implantation of adjustable silicone gastric banding. Ninety-four percent of the patients were satisfied with the procedure and its results. MATERIAL AND METHOD: We performed a retrospective study in the Surgery Department of the Nordwestkrankenhaus teaching hospital of the University of Frankfurt. From April 1996 to January 2000 we performed laparoscopic placement of adjustable silicone gastric banding in 407 patients, using Kuzmak's technique. Mean body mass index was 49.1 and mean weight was 139.2 kg. We describe the patient selection method and provide a detailed description of the technique and its possible problems. RESULTS: There was no operative or postoperative mortality. None of the patients required conventional surgery. Mean operating time was 62 minutes (including operating times during the learning period). Mean hospital stay was 5 days. We performed 24 (5,89%) reinterventions: 11 for displacement, 2 for erosion, 4 for infection of the reservoir, 2 due to review of the reservoir to prevent penetration and 4 due to dilatations of the pouch (changing the banding from a retrogastric to a retroesophageal position); one patient requested removal of the banding. Follow-up was performed at months 1, 6, 9 and 12. Mean weight loss was 28 kg at 6 months and 54 kg at 1 year. Mean weight loss in patients followed-up for 2 years was 58 kg. A total of 94.9% of the patients were satisfied with the procedure. CONCLUSIONS: Laparoscopic implantation of adjustable gastric banding (Lap-Band) combines the aims of conventional gastroplasty with the advantages of laparoscopic surgery in terms of postoperative morbidity and minimal invasiveness.

Adult↗
PubMed2001

[Post-traumatic pancreatic pseudocyst in a child].

Pancreatic pseudocysts are rare in children. Traumatic injury accounts for 80% of the cases. We present the case of a pancreatic injury with pseudocyst formation in a child and discuss the initial management of pancreatic injury as well as the treatment of pseudocyst formation in children.

Abdominal Injuries↗
PubMed2001

Meta-analytic methods, the Rorschach, and the MMPI.

In response to concerns described by H. N. Garb, J. M. Wood, M. T. Nezworski, W. M. Grove, and W. J. Stejskal (2001), the authors present the weighted and unweighted means and medians of the effect sizes obtained by J. B. Hiller, R. Rosenthal, R. F. Bornstein, D. T. R. Berry, and S. Brunell-Neuleib (1999). These indices of central tendency are presented separately for Minnesota Multiphasic Personality Inventory (MMPI) and Rorschach effect sizes, both for all the studies in the meta-analysis and for a 10% trimmed sample designed to obtain more robust estimates of central tendency. The variability of these 4 indices is noticeably greater for the MMPI than for the Rorschach. Meta-analysts must compute, compare, and evaluate a variety of indices of central tendency, and they must examine the effects of moderator variables. The authors also comment briefly on the use of phi versus kappa, combining correlated effect sizes and possible hindsight biases.

Humans↗
PubMed2001

Why introverts can't always tell who likes them: multitasking and nonverbal decoding.

Despite personality theories suggesting that extraversion correlates with social skill, most studies have not found a positive correlation between extraversion and nonverbal decoding. The authors propose that introverts are less able to multitask and thus are poorer at nonverbal decoding, but only when it is a secondary task. Prior research has uniformly extracted the nonverbal decoding from its multitasking context and, consequently, never tested this hypothesis. In Studies 1-3, introverts exhibited a nonverbal decoding deficit, relative to extraverts, but only when decoding was a secondary rather than a primary task within a multitasking context. In Study 4, extraversion was found to correlate with central executive efficiency (r = .42) but not with storage capacity (r = .04). These results are discussed in terms of arousal theories of extraversion and the role of catecholamines (dopamine and norepinephrine) in prefrontal function.

Arousal↗
PubMed2001

Athletes with lower limb ischaemia.

The case of a young healthy sportsman and acute exacerbation of chronic infragenicular pain is presented. Further investigation revealed an obstruction of the tibiofibular trunk due to an osteochondroma, arising from the fibula, which was immediately resected. Osteochondroma is observed in 1-2% of the population and may present with vascular complications. In young patients and athletes, leg pain may be of vascular origin due to an entrapment or compression and should always be considered.

Adult↗