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Biomedical subjects

J B Prystowsky

Publications and source records attributed to J B Prystowsky.

At least 19 recordsLinked to original sources

A virtual reality module for intravenous catheter placement.

BACKGROUND: Virtual reality (VR) is a potential tool for technical skills training. We tested the validity and instructional effectiveness of a prototype VR module for learning intravenous (i.v.) catheter placement. METHODS: First-year medical students (n = 37), third-year medical students (n = 14), and surgical residents (n = 9) attempted two pretest i.v.s into each other, used the VR module for 12 minutes, and subsequently attempted two posttest i.v.s. Success or failure were recorded for each attempt. For each successful attempt, time and global rating of i.v. insertion were also recorded. RESULTS: The pretest success rate was significantly different between groups (chi square = 28.71, P <0.01). VR success rate was not significantly different between groups (F(2,57) = 1.47, ns). Although there was improvement in all groups during VR training (F(2,114) = 44.16, P <0.01), this did not result in improvement in posttest performance. CONCLUSIONS: Significant differences between groups were observed in performance of i.v. insertion in physical reality. However, no significant difference was observed in performance in VR. Thus, performance in VR demonstrated neither construct nor concurrent validity. While performance improved in VR, transfer of skill from VR to physical reality was not observed. Additional development and testing of VR as a training tool is warranted before its widespread use can be recommended.

Catheterization

Inflammation and a thickened mucus layer in mice with cholesterol gallstones.

BACKGROUND: Based on previous work which suggested that biliary crystals may induce inflammation in the gallbladder wall and that inflammation is an early event during the formation of pigment gallstones in the dog, studies were performed examining mucus layer thickness, myeloperoxidase activity, and interleukin-1 (IL-1) activity in the wall of mouse gallbladder during formation and growth of cholesterol gallstones. METHODS AND MATERIALS: The inflammatory effects of cholesterol gallstones at 2 and 4 weeks were studied in BalB/C mice fed a crushed standard mouse chow with added cholesterol (1.0%) and cholic acid (0.5%). Results were compared to those of normal mice fed standard mouse chow. The presence or absence of crystals and stones was determined by gross and microscopic examination of bile. Myeloperoxidase and IL-1 activity in the gallbladder wall was measured using well-established bioassays. Mucus layer thickness was measured by darkfield microscopy. RESULTS: All mice fed a lithogenic, 1.0% cholesterol/0.5% cholic acid diet developed cholesterol crystals and gallstones at 2 and 6 weeks. No control mice developed either crystals or gallstones. Myeloperoxidase and IL-1 activities, markers of an inflammatory response, increased significantly in the gallbladder of mice with crystals at 2 weeks. Myeloperoxidase activity increased two- to three-fold, and IL-1 activity sevenfold, by 6 weeks. Mucus layer thickness also progressively increased during the 6-week period. CONCLUSIONS: It is concluded that inflammation is an early event associated with the appearance of crystals and gallstones in bile.

Animals

The inflammatory effects of crystalline cholesterol monohydrate in the guinea pig gallbladder in vivo.

BACKGROUND: The etiologic role of crystalline material in inflammatory arthritis is well established. The role of crystals in cholecystitis is unclear. We hypothesized that crystalline cholesterol monohydrate stimulates guinea pig gallbladder inflammation in vivo. METHODS: Crystalline cholesterol monohydrate, lipopolysaccharide (LPS), lysolecithin, polystyrene latex spheres (noninflammatory particles), and saline were instilled into guinea pig gallbladders for 24 to 72 hours after cystic duct ligation. Water transport across gallbladder mucosa was measured. Gallbladder tissue was analyzed for mucus layer thickness, myeloperoxidase, prostaglandin E2 (PGE2) prostaglandin F-1 alpha (PGF-1 alpha), and interleukin-1. Luminal fluid was also examined for PGE2 and PGF-1 alpha. Values for each test were compared with saline controls by using Student's test (p < 0.05). RESULTS: Crystalline cholesterol, LPS, and lysolecithin caused significant reduction in mucus layer thickness, reversed water absorption to secretion across the gallbladder mucosa, caused significant increases in myeloperoxidase and interleukin-1 in gallbladder tissue, and caused significant increases in PGE2 and PGF-1 alpha in luminal fluid. These effects were generally dose- but not time-dependent. Polystyrene latex particles caused no difference in outcomes compared with saline controls. CONCLUSIONS: Crystalline cholesterol monohydrate has dose-dependent inflammatory effects in the guinea pig gallbladder in vivo that are not simply-due to mechanical irritation of the gallbladder wall by crystalline particles. Crystals in the gallbladder may have an etiologic role in cholecystitis.

Animals

Neurogenic inflammation in cholecystitis.

Neurogenic inflammation implies stimulation of nerves with resultant inflammation in tissue surrounding the nerve terminals. We hypothesized that neurogenic inflammation has a role in cholecystitis. Capsaicin (stimulant of afferent, nociceptive neurons), 6-hydroxydopamine (stimulates release of peptides from sympathetic nerve terminals), bradykinin, lipopolysaccharide, and saline were instilled into guinea pig gallbladders for 24 hr (N = 5 in each group). In parallel, test agents were instilled with 1% Iidocaine. Water transport across gallbladder mucosa, myeloperoxidase and interluekin-1 release from gallbladder tissue, and prostaglandin E2 in luminal fluid were measured. Capsaicin caused water secretion and significant release of myeloperoxidase, interleukin-1, and prostaglandin-E2, effects that were blocked by Iidocaine. 6-Hydroxydopamine did not affect water transport or prostaglandin E2, but did cause myeloperoxidase and interleukin-1 release. Bradykinin- and lipopolysaccharide-induced inflammation were partially inhibited by lidocaine. Taken together, these results suggest that neurogenic inflammation has a role in the pathophysiology of cholecystitis.

Animals

Interleukin-1 mediates guinea pig gallbladder inflammation in vivo.

Interleukin-1 (IL-1) is a cytokine with multiple immunologic and inflammatory properties. We previously demonstrated that lipopolysaccharide (LPS) stimulates release of IL-1, and IL-1 stimulates inflammation in guinea pig gallbladder in vivo. We hypothesized that IL-1 mediates LPS-induced guinea pig gallbladder inflammation in vivo. LPS and IL-1 were instilled into guinea pig gallbladder lumen alone (with cystic duct ligation) and with IL-1 ra and indomethacin, respectively (n = 4). Water transport across gallbladder mucosa, myeloperoxidase and IL-1 release from gallbladder tissue, and prostaglandin E2 (PGE2) in lumenal fluid were measured. Values for test agents and inhibitory agents were compared to saline controls using Student's t test (P < 0.05). Intralumenal LPS and IL-1 both stimulated gallbladder inflammation. LPS-induced and IL-1-induced inflammation were inhibited by both IL-1 ra and indomethacin. LPS stimulated IL-1 release and IL-1 itself caused gallbladder inflammation. LPS stimulated gallbladder inflammation as manifest by increased myeloperoxidase and PGE2 release, and water secretion into the gallbladder lumen. The inflammatory effects of LPS were inhibited by IL-1 ra. Taken together, these findings indicate that IL-1 is a mediator of LPS-induced guinea pig gallbladder inflammation in vivo.

Animals

Inflammatory properties of bile from dogs with pigment gallstones.

BACKGROUND: Gallbladder inflammation and mucus hypersecretion are prominent features of cholesterol and pigment gallstones in humans and animals. The factors leading to inflammation and mucus hypersecretion are poorly understood. These studies examine the inflammatory potential of bile from dogs with pigment gallstones. METHODS: Dogs fed a methionine-deficient diet that produces pigment gallstones by 6 weeks were compared to normal dogs. Mucus layer thickness, myeloperoxidase activity, and interleukin-1-like activities were measured in canine gallbladder. The inflammatory potential of canine bile was determined by measuring mucus layer thickness, sodium absorption, myeloperoxidase activity and interleukin-1-like activity in guinea pig gallbladders exposed to normal and lithogenic canine bile for 4 hours. RESULTS: Mean mucus layer thickness, myeloperoxidase, and interleukin-1 activity were significantly greater in canine gallbladders containing pigment gallstones. Bile from dogs with pigment gallstones markedly increased mucus layer thickness, myeloperoxidase activity, and interleukin-1 activity and decreased sodium absorption in normal guinea pig gallbladder. These effects were not eliminated by centrifuging bile to remove crystals and gallstones. CONCLUSIONS: Canine bile from dogs with pigment gallstones contains soluble factors capable of causing inflammation in the gallbladder wall.

Animals

Use of notebook computers for third-year surgical students.

BACKGROUND: Computer-aided instruction has become increasingly popular in medical education. Notebook computers (NCs) are attractive, convenient microcomputers. We hypothesized that use of NCs by third-year surgical students would enhance their performance of educational activities. METHODS: During the 1994-1995 academic year 25 student volunteers used NCs during the surgery clerkship. NC software included questions for self-examination, anatomy self-instruction program, word processing and electronic mail (e-mail) for recording and sending history and physicals (H & Ps) to faculty for review, and MEDLINE search software. Identical software was available to all students at on-campus computer centers. All students were asked to record the number of hours that they used the self-examination and anatomy programs, number of H & Ps performed and reviewed by faculty, and number of literature searches performed. NC users were interviewed regarding the value of NC use and their rating of software programs. RESULTS: NC users (n = 25) used the self-examination and anatomy programs more often, performed more literature searches, and had a greater percentage of their H & Ps reviewed by faculty compared with non-NC users (n = 143) (p < 0.05 for all outcomes). Most NC users agreed that NC use was enjoyable and valuable, and they believed that all students should have NCs during the surgery clerkship. Students rated software in order of preference: e-mail > self-examination > MEDLINE search > anatomy program. CONCLUSIONS: NC use enhanced performance of educational activities in the surgery clerkship. Effort toward developing educational software for surgical students is warranted because students are likely to use such programs.

Anatomy

Gastrointestinal tract complications after acute spine injury.

OBJECTIVES: To determine the incidence, risk factors, and mortality rate of gastrointestinal complications in patients with acute spine injury and to derive methods by which mortality can be reduced. DESIGN: Case series. SETTING: Regional tertiary care center. PATIENTS: Consecutive sample of 1952 patients with acute spine injury with complete medical records who were admitted from 1981 through 1990. MAIN OUTCOME MEASURES: Gastrointestinal tract complications, age, sex, time from injury to admission, cause of injury, level of spine injury, neurologic deficit, head injury, injury to other organ systems, incidence of surgical intervention for spine injury, length of hospital stay, and mortality rate. RESULTS: The incidence of gastrointestinal complications was 1.9%. Gastrointestinal hemorrhage was the most frequent complication. Risk factors for gastrointestinal complications were increasing age (P < .02), male sex (P < .01), injury to other organ systems (P < .02), head injury (P < .02), cervical spine injury (P < .02), and neurologic deficit (P < .005). The mortality rate was 19% in patients with gastrointestinal complications, significantly greater (P < .005) than the 2.9% rate in patients without gastrointestinal complications. CONCLUSIONS: Gastrointestinal complications after acute spine injury are uncommon but frequently lethal. Prophylaxis against hemorrhage and earlier diagnosis and surgical intervention are recommended.

Adolescent

Human polymorphonuclear leukocyte phagocytosis of crystalline cholesterol, bilirubin, and calcium hydroxyapatite in vitro.

We tested the hypothesis that human polymorphonuclear leukocytes (PMNs) phagocytize crystalline cholesterol, bilirubin, or calcium hydroxyapatite in vitro and in the process release oxygen metabolites and enzymes involved in the inflammatory process. Chemiluminescence (CL), elicited by the respiratory burst (release and activation of oxygen metabolites and enzymes) of PMNs during phagocytosis of a target particle, was used to quantitate PMN phagocytosis of each crystal. Significant CL (P < 0.05) was observed with cholesterol concentrations of 1.3-5.3 mg/ml and the dose-response was linear (r > or = 0.95). With bilirubin, significant CL was observed with concentrations of 0.07-0.33 mg/ml. The response to calcium hydroxyapatite was variable. Human PMNs phagocytize cholesterol, bilirubin, and to a lesser extent, calcium hydroxyapatite. PMN chemiluminescence was associated with phagocytosis, indicating that inflammatory substances are being released in the process. These results support the concept that crystals that occur in the gallbladder may initiate gallbladder inflammation.

Bilirubin

Er:YAG laser ablation of prairie dog gallbladder epithelium for the prevention of gallstones.

We hypothesized that laser ablation of gallbladder epithelium would prevent gallstone formation in prairie dogs. An Er:YAG laser (lambda = 2.94 microns) was used to ablate the gallbladder epithelium of 24 prairie dogs; 20 sham-irradiated and 12 non-operated prairie dogs served as controls. Prairie dogs were sacrificed at time periods of 4 days, 2 weeks, and 8-12 weeks and evaluated for the presence of gallstones and cholesterol crystals. Laser-irradiated gallbladders demonstrated a lower rate of gallstone formation at 8-12 weeks than the sham-irradiated gallbladders (39% vs. 79%: P < .02). Crystal formation, however, was not different between laser-irradiated (88%) and sham-irradiated (100%) animals. The laser-irradiated group had less epithelium than the non-operated group at all time periods (P < or = .002) and compared to the sham-irradiated group at 4 days and 8-12 weeks (P < or = .001). These data suggest that laser ablation of gallbladder epithelium can reduce the rate of gallstone formation although this effect may be temporary.

Aluminum Silicates

Laparoscopic inguinal hernia repair. A preliminary experience.

OBJECTIVE: To evaluate the safety and efficacy of laparoscopic inguinal hernia repair. DESIGN: Nonrandomized trial. SETTING: Veterans Affairs hospital and a large university hospital. PATIENTS: The study included 38 patients (36 male and two female) who had an acceptable risk for general anesthesia, presented electively, and gave informed consent; patients were excluded for whom general anesthesia had a high risk or who had incarcerated or strangulated hernias. INTERVENTION: Laparoscopic inguinal hernia repair was performed with general anesthesia through bilateral, lower-abdominal, 12-mm lateral rectus sheath ports with an umbilical 30 degrees viewing laparoscope. After the peritoneum was incised and flaps were raised, an onlay patch of polypropylene mesh, secured with staples, covered both indirect and direct hernia regions in each patient. Small hernia sacs were usually reduced or excised. RESULTS: From December 1991 through October 1992, 40 inguinal hernias were repaired; two patients had bilateral hernias. There were 22 indirect and 17 direct inguinal hernias and one femoral hernia. Nine of the hernias repaired were recurrent, and five were sliding hernias. Complications occurred in nine patients, but there were no recurrences during a median follow-up of 26 weeks. All but one patient resumed preoperative activities by 7 days after the operation. CONCLUSIONS: Laparoscopic inguinal hernia repair is an effective operation with low morbidity. Long-term follow-up is needed to determine the durability of the repair.

Adolescent

Spontaneous bilateral pneumothorax--complication of laparoscopic cholecystectomy.

Pneumothorax is a rare complication of pneumoperitoneum. We report a case of spontaneous bilateral pneumothorax during laparoscopic cholecystectomy. The history, pathogenesis, and therapeutic options of this unusual occurrence are discussed. Because laparoscopic operations have become increasingly popular in recent years, we call attention to this rare but potentially life-threatening complication.

Adult

The effects of ultrasound-guided shock waves during early pregnancy in Sprague-Dawley rats.

Pregnancy is a contraindication to extracorporeal shock wave lithotripsy (ESWL) because of its possible harm to the embryo or fetus caused by shock waves or ionizing radiation. In this study timed-pregnant rats were subjected to shock waves early in gestation using a lithotriptor having ultrasound imaging. In a pilot group undergoing immediate laparotomy, it was determined to what extent the pelvic structures were effected. Then a test group was exposed to shock waves and carried to near term pregnancy along with an identical group of pregnant, sham procedure rats. A laparotomy all were inspected for fetal viability, fetal abnormalities, and maternal organ damage. Fetuses located nearest the focal area of maximum shock wave energy showed lower mean weight than controls. There was no recognizable gross or microscopic fetal damage.

Animals

A performance analysis of an extracorporeal shock wave lithotripter: spatial pressure distribution and the effects of lithotripter voltage, electrode life, and tissue attenuation.

The Dornier MPL-9000 lithotripter was analyzed as a function of lithotripter voltage, electrode efficiency, and bovine muscle attenuation. The maximum pressure at 20 kV measured 65 +/- 4 MPa (mean +/- SD). The region containing 50% of the maximum pressure was a cylindrical volume with a diameter of 2.5 cm and a height of 7 cm. Pressure varied in a linear fashion with lithotripter voltage (r = 0.996). The average pressure produced by an electrode throughout the course of 2,200 shock waves was 78% of its maximum pressure. Shock wave pressure was reduced from 65 +/- 4 MPa to 49 +/- MPa, 44 +/- 3 MPa, and 44 +/- 1 MPa with 1-, 2-, and 3-cm thickness of intervening bovine muscle, respectively. There was a statistically significant decrease in pressure when muscle was interposed, but there was no significant difference in reduction of pressure between 1, 2, and 3 cm of muscle (ANOVA, Newman-Keuls, alpha = 0.01). Frequency spectral analysis revealed the major contribution to the shock wave comes from 0-200 kHz with a peak near 50 kHz. Major frequency intensities were reduced with a decrease in lithotripter voltage, attenuating tissue, and distance away from the center of the focal zone.

Animals

Acute diverticulitis. A complicated problem in the immunocompromised patient.

We reviewed the records of 209 patients with acute diverticulitis treated from 1984 through 1989 to determine if immunocompromised patients have a worse prognosis than nonimmunocompromised patients. Forty immunocompromised patients and 169 nonimmunocompromised patients with acute diverticulitis were identified. Free perforation into the peritoneal cavity occurred in 43% (17/40) of immunocompromised patients and 14% (24/169) of nonimmunocompromised patients. Operations were performed in 58% (23/40) of immunocompromised patients and 33% (55/169) of nonimmunocompromised patients. Postoperative morbidity was 65% (15/23) in immunocompromised patients and 24% (13/55) in nonimmunocompromised patients; postoperative mortality was 39% (9/23) and 2% (1/55), respectively. We conclude that acute diverticulitis in the immunocompromised patient is a complicated problem; there is a greater risk of free perforation and need for surgery than in the nonimmunocompromised patient. Furthermore, the prognosis for immunocompromised patients who undergo surgery is worse than that for nonimmunocompromised patients.

Acute Disease

Extracorporeal shock wave lithotripsy for biliary stones.

Extracorporeal shock wave lithotripsy is a noninvasive technique for treatment of patients with gallbladder and bile duct stones. Selected patients with gallbladder stones can be treated on an outpatient basis without general anesthesia and may return to full activity within 1 or 2 days. Stone-free rates of 40% to 60% at 6 months have been achieved in most reported series with minimal morbidity. Bile duct stone lithotripsy has achieved stone clearance in 80% of patients in whom conventional methods were unsuccessful and therefore constitutes a valuable second-line treatment for these patients.

Bile Duct Diseases