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Biomedical subjects

M Rosen

Publications and source records attributed to M Rosen.

At least 19 recordsLinked to original sources
PubMed2006

Constraints on cosmic neutrino fluxes from the Antarctic Impulsive Transient Antenna experiment.

We report new limits on cosmic neutrino fluxes from the test flight of the Antarctic Impulsive Transient Antenna (ANITA) experiment, which completed an 18.4 day flight of a prototype long-duration balloon payload, called ANITA-lite, in early 2004. We search for impulsive events that could be associated with ultrahigh energy neutrino interactions in the ice and derive limits that constrain several models for ultrahigh energy neutrino fluxes and rule out the long-standing -burst model.

Journal Article↗
PubMed2005

Measurement of dental restorative material topography.

INTRODUCTION: The tracing of peaks and valleys produced during surface profiling of dental materials are read against a mean line which can be modified in the form of a line or arc. Roughness (R) is commonly used to measure the topography of restorative materials, but the profile (P) value is also generated during the tracing and includes both roughness and waviness of the surface. AIMS AND OBJECTIVES: The purpose of this study was to determine if line and arc modified tracings and R and P surface topography measurements give similar results. METHODS: Thirty six cavities (5 x 1.5mm) were prepared in Perspex discs, restored with Fuji IX, a high strength glass ionomer cement, following the Atraumatic Restorative Treatment (ART) technique and the surface of six cavities were each treated as follows: press finger with vaseline (Va); press finger with polyacrylic acid (Aa); carving (Ca); burnishing (Bu); Mylar strip (My); polishing (Po). Topography was assessed using a profilometer which ran three equidistant tracings (3.6mm) on each surface giving a total of 18 readings for each treatment (n=6). The results of Ra, Rv, Rp, R, and Pa, Pv, Pp, P, for all 6 surface treatments were compared and analysed using ANOVA and Tukey's studentised range test with significance set at P<0.05. RESULTS: Within R + line, R + arc, P + line and P + arc, significant differences were apparent between treatments. Pairwise comparisons showed fewer instances of significant differences between surface treatments when R + line (1 instance of significant difference) was compared to R + arc (2). P + line showed 12 instances of significant differences between surface treatments while P + arc showed no difference. CONCLUSION: Both line and arc tracings gave similar results for R and either may be used in assessing surface roughness. The total deviation of the profile P showed more significant differences between treatments with line than with arc and may be a more sensitive tool when dealing with small sample numbers or subtle differences between surface treatments.

Analysis of Variance↗
PubMed2004

Scientific surface roughness values for resin based materials.

INTRODUCTION: Surface roughness of dental restorative materials is most often established with the Ra value obtained using profilometry or by assessing surface topography with the scanning electron microscope (SEM). Both methods should validate each other in confirming surface roughness. AIMS AND OBJECTIVES: The purpose of this study was to compare surface roughness values obtained with a profilometer to the SEM appearance of 6 resin-based restorative materials and assess whether Ra was appropriate as a sole surface roughness measure. Methods Six 5mm diameter specimen discs of Prodigy (Pr); Z100 (Z); Compoglass F (C); Hytac Aplitip (H); Photac-Fil (Pf) and Vitremer (V) were prepared against Mylar strips and stored in distilled water for 14 days. One side of each disc was sequentially polished with Soflex discs to super fine state, the other side remained unpolished. Three surface roughness measurements were made on each surface (n=18) recording Ra, Rv, Rp and Rt values, this data was subjected to a four way ANOVA and Tukey's Studentised Range Test (p=0.05). Two unpolished and two polished discs per material were prepared for SEM, evaluated and visually grouped for surface roughness. RESULTS: Approximate ascending order of roughness was Z, Pr, H, C, V, Pf for Ra, Rv, Rp and Rt and un/polished treatment. Polishing increases surimens into a "bland" (Pr, H, Z, C) and "textured" group (Pf and V). The polished specimens gave four groups: (Pr), (Z and C), (H) and (V and Pf) of increasing surface complexity. Polishing caused surface scratching, removed the matrix, reduced or removed filler particles and exposed voids within the material. CONCLUSIONS: This study emphasises the importance of using more than one technique to assess surface roughness. Rv and Rp values should be utilised to better understand polish induced surface feature changes. Rv maximum is a better measure to identify surface defects which could affect restoration longevity.

Analysis of Variance↗
PubMed2003

Laparoscopic resection of a periampullary villous adenoma.

BACKGROUND: Adenomas of the duodenal papilla are rare lesions. Because of their malignant potential, resection is mandatory. Options for resection include endoscopic resection, transduodenal local excision, and pancreaticoduodenectomy. This report details a case of periampullary villous adenoma diagnosed endoscopically and resected laparoscopically via a transduodenal approach. CASE REPORT: A healthy 75-year-old woman with heartburn underwent an upper endoscopy for vague right upper abdominal pain. A periampullary tumor was diagnosed. Endoscopic biopsy results were consistent with a villous adenoma, and endoscopic ultrasound showed distal bile duct involvement. The patient underwent laparoscopic transduodenal local excision of the tumor with biliary reconstruction. CONCLUSIONS: Laparoscopic transduodenal resection of periampullary lesions provides advantages similar to those of an endoscopic resection by removal of the tumor using minimally invasive techniques. In addition, laparoscopic surgery maintains the surgical tenents of open transduodenal resection with en bloc tumor resection including the adjacent duodenal wall and ductal structures as necessary. As noted in this case, laparoscopic techniques resect ampullary lesions involving the ductal structures as well. Laparoscopic transduodenal ampullectomy is a valuable treatment option for benign and selected premalignant ampullary lesions.

Adenoma, Villous↗
PubMed2003

Anterior gastropexy may reduce the recurrence rate after laparoscopic paraesophageal hernia repair.

BACKGROUND: Although laparoscopic repair of type 3 paraesophageal hernias is safe and results in symptomatic relief, recent data have questioned the anatomic integrity of the laparoscopic approach. The reports document an asymptomatic recurrence rate as high as 42% with radiologic follow-up evaluation for type 3 paraesophageal hernias repaired laparoscopically. This disturbingly high recurrence rate has prompted the addition of an anterior gastropexy to our standard laparoscopic paraesophageal hernia repair. METHODS: A prospective series of 28 patients underwent laparoscopic repair of large type 3 hiatal hernias between July 2000 and January 2002 at the Cleveland Clinic Foundation by one surgeon. All the patients underwent reduction of the hernia, sac excision, crural repair, antireflux procedure, and anterior gastropexy. They all had a video esophagram 24 h after surgery, then at 3-, 6-, and 12-month follow-up visits and annually thereafter. Symptomatic outcomes were assessed with a standard questionnaire at each follow-up visit. RESULTS: In this study, 21 women and 7 men with a mean age of 67 years (range, 35-82 years) underwent successful laparoscopic paraesophageal hernia repair. The mean operative time was 146 min (range, 101-186 min), and the average blood loss was 71 ml (range, 10-200 ml). One intraoperative complication occurred: A small esophageal mucosal tear occurred during esophageal dissection and was repaired laparoscopically. At 24 h, upper gastrointestinal examination identified no leaks. At this writing, all the patients have undergone video esophagram at a 3-month follow-up visit. All were asymptomatic and all examinations were normal. Of the 28 patients, 27 have undergone follow-up assessment at 6 months. At this writing, all the patients have undergone video esophagram at 3, 6, and 12 months follow up visits. All were asymptomatic and all examinations were normal. Ten patients have completed 2 year follow up barium swallows with no recurrences. CONCLUSIONS: With up to 2 years of follow-up evaluation, the addition of an anterior gastropexy to the laparoscopic repair of type 3 hiatal hernias resulted in no recurrences. These encouraging results necessitate further follow-up evaluation to document the long-term effects of anterior gastropexy in reducing postoperative recurrence after laparoscopic repair of paraesophageal hernias.

Adult↗
PubMed2003

Postpartum hemorrhagic shock resulting in thrombotic thrombocytopenic purpura-hemolytic uremic syndrome.

Thrombotic microangiopathies may be initiated by a number of antecedent events. When presented with postpartum hemorrhage and unexplained thrombocytopenia, it is prudent to consider microangiopathic hemolytic anemia in the differential diagnosis. A 25-year-old woman, gravida 2, para 1, had an uncomplicated repeat Cesarean delivery at 38 weeks' gestation. She subsequently had an exploratory laparotomy for hemoperitoneum resulting from a left uterine artery laceration. On postoperative day 3, she developed thrombotic chrombocytopenic purpura-hemolytic uremic syndrome and was treated with plasma exchange therapy and dialysis. It is critical that clinicians consider this potentially fatal disease in the differential diagnosis when hemorrhagic shock is associated with unexplained thrombocytopenia, so that appropriate and early treatment may lead to a favorable outcome.

Adult↗
PubMed2002

Recurrence after laparoscopic ventral hernia repair.

BACKGROUND: Although the early results of laparoscopic ventral hernia repair have shown a low recurrence rate, there is a paucity of long-term data. This study reviews a single institution's experience with laparoscopic ventral hernia repair (LVHR). METHODS: We carried out a retrospective analysis of all LVHR performed at the Cleveland Clinic Foundation from January 1996 to March 2001. Recurrence rates were determined by physical exam or telephone follow-up. Factors predictive of recurrence were determined using Cox regression. RESULTS: Of 100 ventral hernias completed laparoscopically, 96 were available for long-term follow-up (average, 30 months; range 4-65). There were no deaths and major morbidity occurred in seven patients. Recurrences were identified in 17 patients. Nine recurrences occurred in the 1st postoperative year; however, hernia recurrence continued throughout the period of follow-up. Multivariate analysis showed that a prior failed hernia repair was associated with a more likely chance of another recurrence (65% vs 35%, odds ratio (OR) 3.6; p = 0.05) and that an increased estimated blood loss (106 cc vs 51 cc, OR 1.03; p = 0.005) predicted recurrence. Other variables, including body mass index (BMI) (32 vs 31 kg/m2, p = 0.38), defect size (115 cm2 vs 91 cm2; p = 0.23), size of mesh (468 cm2 vs 334 cm2, p = 0.19), type of mesh (p = 0.62), and mesh fixation (p = 0.99), did not predict recurrence. An additional 14 cases required conversion to an open operation, and seven of these cases (50%) had recurrence on long-term follow-up. CONCLUSION: Although LVHR remains the preferred method of hernia repair at our institution, this study documents a higher recurrence rate than many other short-term series. There results underscore the importance of long-term follow-up in assessing hernia surgery outcome.

Adult↗
PubMed2002

The economic impact of flexible endoscopy in a large academic surgical department.

BACKGROUND: There has been considerable controversy concerning the value added to a general surgery practice when flexible gastrointestinal endoscopy is incorporated. The purpose of this study was to assess the economic impact of flexible endoscopy performed by general surgeons in a large academic practice. METHODS: A retrospective review of gross billing charges for a group practice of 11 surgeons over the fiscal year 1999 was performed at the Cleveland Clinic Foundation. The total billing for clinic visits and outpatient and inpatient surgical procedures was compiled, and the percentage attributable to flexible endoscopy was determined. Of the 11 surgeons, three had incorporated flexible endoscopy into their practice. RESULTS: The three endosurgeons generated 33% of the total gross billing for the Department of General Surgery. Flexible endoscopy alone accounted for 12.2% of the total percentage of gross billings for the department. Meanwhile, this revenue was generated from only 8% of the workweek when performing flexible endoscopic procedures were performed. CONCLUSION: Flexible endoscopy can contribute significantly to the financial productivity of the general surgeon.

Academic Medical Centers↗
PubMed2001

Planned totally extraperitoneal laparoscopic Spigelian hernia repair.

A Spigelian hernia is a congenital defect in the tranversus aponeurosis fascia. Traditionally, an open anterior hernioplasty was used to repair these defects. Recently, laparoscopic approaches have been described. This report describes the first application of the totally extraperitoneal laparoscopic approach to a planned repair of a Spigelian hernia. The patient was a 62-year-old white female with a reducible left lower quadrant anterior abdominal wall bulge consistent with a Spigelian hernia. At the time of surgery, we exposed the posterior rectus fascia and modified our extraperitoneal inguinal hernia technique by passing the balloon dissector in a more lateral orientation. This created a unilateral preperitoneal space with adequate room for dissection and mesh fixation. The Spigelian defect was easily identified. Its preperitoneal fat contents were reduced, and a 5-mm laparoscopic tacking device was used to secure a piece of prolene mesh. The patient was discharged home with no complications. Placement of the mesh in the preperitoneal space avoids direct interaction of the mesh prosthesis and the intraperitoneal viscera. In conclusion, we find that a laparoscopic totally extraperitoneal approach is technically feasible and advantageous when a Spigelian hernia is diagnosed preoperatively.

Adult↗
PubMed2001

Laparoscopic lateral L4-L5 disc exposure.

BACKGROUND: The anterior laparoscopic approach requires precarious dissection around the iliac vessels to expose the L4-L5 level. Furthermore, a retroperitoneal endoscopic approach to the L4-L5 level requires a technically demanding dissection to access the L5-S1 disc space. A unique lateral laparoscopic approach to the L4-L5 disc space allows concurrent access to the L5-S1 space while avoiding major dissection around the iliac vessels. This article describes this novel lateral approach and reviews the initial clinical outcomes. METHODS: Between January 1999 and April 2000, five patients underwent laparoscopic lateral L4-L5 disc exposure at the Cleveland Clinic Foundation. All charts were reviewed retrospectively. Mean values +/- standard deviation were determined for patient demographics and operative characteristics. A standard five-port laparoscopic technique was used. The sigmoid colon was retracted medially with an endoloop. The retroperitoneum was entered and the ureter and left iliac artery were retracted medially, whereas the psoas was retracted laterally. Fluoroscopy delineated the L4-L5 disc space allowing discectomy and cage insertion. Postoperatively, subjective patient satisfaction was obtained and radiologic evidence of fusion was assessed. RESULTS: All five patients were males, with a mean age of 47.4 +/- 7 years and a body mass index of 30 +/- 6 kg/m2. Four patients had an L4-L5 and L5-S1 fusion and one patient had an L4-L5 and L3-L4 fusion. Mean operative time was 349 +/- 32 min, with a mean blood loss of 210 +/- 74 cc. There were no intraoperative complications and no conversions, and postoperatively all patients were started on a clear liquid diet on postoperative day 1. The mean length of stay was 3.4 +/- 0.9 days. Patients returned to work in a mean of 12 +/- 7 weeks. All patients had evidence of fusion on their radiologic follow-up. Four patients were pain free, whereas one patient required intermittent narcotics at 1-year follow-up. CONCLUSIONS: For multilevel fusions including the L4-L5 disc space, the lateral laparoscopic exposure is a safe and efficacious procedure allowing simultaneous access to multiple disc spaces while avoiding the sympathetic chain, ureter, and major vascular structures. The lateral approach affords excellent exposure for accurate deployment of the appropriate orthopedic hardware.

Adult↗
PubMed2001

Outcome of laparoscopic splenectomy based on hematologic indication.

BACKGROUND: Laparoscopic splenectomy is the procedure of choice for elective splenectomy at the Cleveland Clinic Foundation. Although the literature clearly documents the technical feasibility and safety of laparoscopic splenectomy, little data exists concerning the results of this procedure based on the hematologic indication for splenectomy. We sought to examine the clinical experience with laparoscopic splenectomy in a single institution, with particular attention to morbidity and clinical outcomes based on hematologic disease process. METHODS: This study retrospectively reviewed a consecutive series of laparoscopic splenectomies performed for nontraumatic, splenic pathology at the Cleveland Clinic Foundation from August 1995 to January 2001. Patient demographics, operative indications, morbidity, mortality, and clinical outcome were evaluated. Hematologic diagnostic groups were compared using Fisher's exact tests and Wilcoxon rank-sum tests. RESULTS: A total of 147 laparoscopic splenectomies were performed. Seven patients (5%) required conversion to open splenectomy. Indications for splenectomy included idiopathic thrombocytopenic purpura (ITP) in 65 patients, hematologic malignancy in 43 patients, autoimmune hemolytic anemia (AIHA) in 9 patients, thrombotic thrombocytopenic purpura (TTP) in 9 patients, splenomegaly in 5 patients, splenic cyst in 4 patients, splenic abscess in 3 patients, hereditary spherocytosis in 2 patients, splenic artery aneurysm in 2 patients, Felty's syndrome in 1 patient, myelofibrosis in 1 patient, and other in 3 patients. Accessory spleens were identified in 20 patients (14%). Postoperative complications occurred in 23 (16%) patients. Patients with ITP had significantly shorter operation times (134 vs 163 min; p = 0.001), decreased estimated blood loss (126 vs 307 ml; p = 0.001), decreased length of hospital stay (2.8 vs 4.6 days; p < 0.001), and less chance of conversion (0 vs 7; p = 0.02) than patients with any other diagnosis. A mean follow-up period of 20 +/- 14 months showed an 85% rate of remission for ITP, 89% for TTP, and 89% for AIHA. Patients with malignant disease had significantly larger spleens (822 vs 313 g; p < 0.001), more estimated blood loss (380 vs 168 ml; p = 0.04), and longer operative times (170 vs 142 min; p = 0.009), as compared patients treated for benign disease. However, the length of hospital stay (4.3 vs 3.6 days; p = 0.06) and complication rates (19% vs 14%; p = 0.08) were not significantly different between the two groups. CONCLUSIONS: When performed for ITP, laparoscopic splenectomy resulted in shorter operations, minimal blood loss, earlier discharge, no conversions, and excellent remission rates, as compared with other hematologic indications. Despite larger spleens, more blood loss, and longer operations in patients with hematologic malignancies, morbidity and length of hospital stay still were similar to those associated with benign indications for laparoscopic splenectomy. In conclusion, laparoscopic splenectomy is safe and efficacious for a multitude of benign and malignant hematologic indications, and our data compares favorably to those for open series.

Adolescent↗
PubMed2001

Paramagnetic ion-doped nanocrystal as a voltage-controlled spin filter.

A theory of spin injection from a ferromagnetic source into a semiconductor through a paramagnetic ion-doped nanocrystal is developed. Spin-polarized current from the source polarizes the ion; the polarized ion, in turn, controls the spin polarization of the current flowing through the nanocrystal. Depending on voltage, the ion can either enhance the injection coefficient by several times or suppress it. Large ion spins produce stronger enhancement of spin injection.

Journal Article↗
PubMed2001

Electron and nuclear spin interactions in the optical spectra of single GaAs quantum dots.

Fine and hyperfine splittings arising from electron, hole, and nuclear spin interactions in the magneto-optical spectra of individual localized excitons are studied. We explain the magnetic field dependence of the energy splitting through competition between Zeeman, exchange, and hyperfine interactions. An unexpectedly small hyperfine contribution to the splitting close to zero applied field is described well by the interplay between fluctuations of the hyperfine field experienced by the nuclear spin and nuclear dipole/dipole interactions.

Journal Article↗
PubMed2001

Evolution of action potential propagation and repolarization in cultured neonatal rat ventricular myocytes.

INTRODUCTION: Cultured neonatal rat ventricular myocytes (NRVM) reestablish gap junctions as they form synchronously and spontaneously beating monolayers, thus providing a useful model for studying activation and repolarization. METHODS AND RESULTS: We used the multielectrode array data acquisition system with 60 unipolar electrodes to investigate the functional organization of cultured NRVM, by determining propagation and repolarization patterns. Activation maps were constructed from the local activation times at each electrode. During days 3 to 8 in culture, QRS amplitude and dV/dt(max) increased with age. Concomitantly, with the culture maturation, QT interval (representing action potential duration) decreased, and T wave amplitude and slopes of the T wave ascending and descending limbs progressively increased. The changes in conduction velocity were different than those of the electrogram properties, slightly increasing during the first 3 to 5 days and gradually declining toward day 8 in culture. CONCLUSION: Establishment of uniform activation patterns in spontaneously firing or driven myocytes in monolayer cultures is accompanied by organization of activation and repolarization whose evolution appears in concert with that of a mature connexin43 staining pattern. The experimental techniques developed in this study provide useful tools to investigate the complex relations among gap junctions, conduction velocity, and propagation patterns, as well as a means to learn how gap junctional remodeling under pathophysiologic conditions predisposes the myocardium to arrhythmias.

Action Potentials↗
PubMed2001

Minimally invasive surgery.

In 1987, Mouret performed the first laparoscopic cholecystectomy - dramatically changing the history of surgical practice. No other aspect of surgery has developed with such vigor as laparoscopy. Previously, surgeons had attempted to define the maximum level of surgical intervention a patient could withstand - but as laparoscopic surgery developed, this paradigm was turned on its head. Minimally invasive surgeons are continuing to determine and redefine how much can be accomplished through smaller incisions and with minimal surgical stress. Laparoscopy is still only in its infancy. This article reviews current aspects of laparoscopic surgery in 1999-2000 in relation to gallbladder, gastric, colorectal, and splenic disease, as well as reviewing the current role of laparoscopic surgery in the treatment of abdominal wall hernias.

Cholangiopancreatography, Endoscopic Retrograde↗