Search PubMed⌕ Search

Biomedical subjects

J Pollack

Publications and source records attributed to J Pollack.

At least 19 recordsLinked to original sources
PubMed1999

Silicone-covered metal stents: an in vitro evaluation for biofilm formation and patency.

Self-expanding metal stents are being used more commonly to prevent biliary tract obstruction. Silicone-covered self-expanding metal stents (Wallstent, Schneider, Inc.) have been developed to prevent tumor ingrowth. Biofilm formation and occlusion material in silicone-covered self-expanding metal stents compared to standard polyethylene stents were examined in an in vitro model. Matched pairs of polyethylene and silicone-covered metal stents were perfused with infected bile for 8, 12, and 16 weeks at a rate of 0.5 cc/min at 37 degrees C. Two reservoirs fitted with silicone-covered metal stents had ampicillin/sulbactam added and were perfused for 16 weeks. The stents were then analyzed by scanning electron microscopy and light microscopy for biofilm formation and presence of occlusion material. The two ampicillin/sulbactam-treated stents showed no biofilm formation. Biofilm was seen on all of the remaining stents. There was a difference in occlusion thickness between the 8- and 16-week polyethylene stents, and no difference between the biofilm thickness at 8, 12, or 16 weeks in the silicone-covered metal stents. Silicone-covered self-expanding metal stents will likely extend patency rates in malignant obstructive jaundice by providing a larger lumen for bile flow and allowing cyclical antibiotics to prevent bacterial biofilm formation.

Ampicillin↗
PubMed1998

Use of single percutaneous endoscopic gastrostomy in management of gastric volvulus in three patients.

Gastric volvulus is a rare condition that occurs when the stomach twists either in an organoaxial or mesenteroaxial direction. In patients with recurrent episodes of volvulus, standard therapy is surgical correction. Many patients, however, are not candidates for surgical therapy because of comorbid conditions or advanced age. Our aim was to determine if the insertion of a single percutaneous gastrostomy tube placement would assist in management of gastric volvulus in patients not able to undergo surgical therapy. The alpha-loop maneuver was used to reduce gastric volvulus in three elderly patients. A percutaneous endoscopic gastrostomy tube was then inserted to prevent recurrent volvulus. Single percutaneous gastrostomy tube placement was successful in managing volvulus in these three patients. Single percutaneous endoscopic gastrostomy tube placement is a useful treatment alternative to surgery in patients requiring therapy of gastric volvulus.

Aged↗
PubMed1998

Comparison of RapID yeast plus system with API 20C system for identification of common, new, and emerging yeast pathogens.

The ability to identify yeast isolates by the new enzymatic RapID Yeast Plus System was compared to the ability to identify yeast isolates by the API 20C system. A total of 447 yeast isolates representing Blastoschizomyces capitatus, 17 Candida spp., 5 Cryptococcus spp., Geotrichum spp., 2 Hanseniaspora spp., Hansenula anomala, Hansenula wingei, 3 Rhodotorula spp., Saccharomyces cerevisiae, Sporobolomyces salmonicolor, Trichosporon beigelii, and 2 Prototheca spp. were evaluated. Also, five quality control strains (Candida spp. and Cryptococcus laurentii) with well-documented reactivities by the RapID Yeast Plus System were used. Each isolate was evaluated by both methods with a 48-h culture grown at 30 degrees C on Sabouraud dextrose agar (Emmons modification) by following the recommendations of the manufacturers. The RapID Yeast Plus System enzymatic reactions were read after 4 h of incubation, and the API 20C carbohydrate assimilation identification profiles were obtained after 72 h of incubation. There was good (95.7%) agreement between the identifications obtained by the two methods with the eight common Candida spp. and with Cryptococcus neoformans. The agreement was lower when the emerging Candida spp. and other yeast-like pathogens were tested (79.1 and 75.2%, respectively). These preliminary data suggest the potential utility of the RapID Yeast Plus System for use in the clinical laboratory for the rapid identification of common yeast pathogens as well as certain new and emerging species.

Yeasts↗
PubMed1998

Evolutionary body building: adaptive physical designs for robots.

Creating artificial life forms through evolutionary robotics faces a "chicken and egg" problem: Learning to control a complex body is dominated by problems specific to its sensors and effectors, while building a body that is controllable assumes the pre-existence of a brain. The idea of coevolution of bodies and brains is becoming popular, but little work has been done in evolution of physical structure because of the lack of a general framework for doing it. Evolution of creatures in simulation has usually resulted in virtual entities that are not buildable, while embodied evolution in actual robotics is constrained by the slow pace of real time. The work we present takes a step in addressing the problem of body evolution by applying evolutionary techniques to the design of structures assembled out of elementary components that stick together. Evolution takes place in a simulator that computes forces and stresses and predicts stability of three-dimensional brick structures. The final printout of our program is a schematic assembly, which is then built physically. We demonstrate the functionality of this approach to robot body building with many evolved artifacts.

Biological Evolution↗
PubMed1997

Inhibition of biliary endoprostheses occlusion by ampicillin-sulbactam in an in vitro model.

An important first step in stent occlusion is the formation of a bacterial biofilm. This is followed by deposition of granules similar to that found in brown pigment stones. Previous in vitro models for studying occlusion have used synthetic biles without bilirubin or pooled human bile, which is limited in supply. Our aim was to develop a new in vitro model of stent occlusion with porcine gallbladder bile and then, with the model, assess whether ampicillin-sulbactam can prevent biofilm formation and thus occlusion. Sterile porcine gallbladder bile was contaminated with Escherichia coli then divided into eight reservoirs, four of which then received ampicillin-sulbactam. The bile was then circulated through 10F polyethylene stents. Bile was changed weekly for 8 weeks. In the stents that were untreated, biofilm and sludge were seen in all four, whereas the four ampicillin-sulbactam-treated stents had no biofilm when viewed by electron microscopy. Furthermore, the levels of calcium, cholesterol, and bilirubin in the reservoirs decreased significantly in the untreated bile as compared with the treated bile (p < 0.05). In this in vitro model, the losses of calcium, cholesterol, and bilirubin are likely caused by deposition of granules into the biofilm matrix. Ampicillin-sulbactam can prevent biofilm formation if used continuously.

Ampicillin↗
PubMed1997

Use of oral GoLytely solution in relief of refractory fecal impaction.

Constipation and fecal impaction are common disorders with multiple treatment options. We describe the use of GoLytely oral solution in 10 patients admitted to a community hospital and referred to a single gastroenterologist for fecal impaction refractory to conventional medical treatment. Seven women and three men received enemas, bisacodyl suppositories, and digital fragmentation either solely or in combination prior to the administration of GoLytely oral solution. The patients had no clinical and radiological evidence of bowel obstruction. All had underlying cardiovascular problems. Their mean age was 78.1 years (range 49-100 years). GoLytely oral solution (Braintree Laboratories, Inc.) was administered at a rate of 100 ml/hr per orem to three patients, via nasogastric tube in six patients, and via gastrostomy tube in one patient. All 10 patients were able to regularly pass feces and show radiographical colorectal clearing within 6.0 to 57.25 hr (mean 23.60 hr). No significant complications were observed. Eight patients were discharged from the hospital within 24 hr of termination of treatment while two patients remained for unrelated medical conditions. GoLytely oral solution effectively relieved fecal impaction in 10 patients refractory to conventional medical treatment.

Administration, Oral↗
PubMed1997

Volvulus of the small bowel: an uncommon complication after laparoscopic cholecystectomy.

We report here two patients with volvulus of the small bowel after laparoscopic cholecystectomy (LC). There has been only one case report of a similar condition after LC in the English literature; the patient had malrotation of the midgut. Both patients we are reporting had previous pelvic surgery resulting in intraabdominal adhesions. Volvulus had occurred along an axis between the mesenteric attachment and the adhesion to the parietal peritoneum of the involved loop of small bowel. The creation of pneumoperitoneum could conceivably allow rotation to occur. One patient presented with signs of peritonitis from a gangrenous segment of small bowel. The other presented with continued abdominal pain after surgery. Definitive diagnosis was made only at laparotomy. Previous surgery is considered a relative contraindication to LC, although the incidence of morbidity and conversion to open procedure appear not to be influenced by previous surgery. Surgeons should be aware of volvulus as a complication after LC in patients who had previous abdominal surgery.

Adult↗
PubMed1995

Erythrocyte thiolmethyltransferase: another failed marker for Alzheimer's and Parkinson's diseases.

There are reports that patients with Parkinson's disease (PD) and Alzheimer's disease (AD) have reduced levels of thiolmethyltransferase (TMT) in erythrocyte membranes. TMT methylates thiols and thiocarbamates, thereby reducing their toxicity. We examined TMT levels in erythrocytes from patients with PD and AD and from age-matched controls. Specific activities of TMT were 564 +/- 199 U/mg protein in PD (n = 32), 513 +/- 118 in AD (n = 13), and 565 +/- 183 in controls (n = 35). There was no difference between any of the groups (p = 0.64). We failed to confirm TMT as a marker for neurodegenerative diseases or for this metabolic defect predisposing to susceptibility to neurotoxins.

Aged↗
PubMed1994

Mongolian gerbils (Meriones unguiculatus) absorb beta-carotene intact from a test meal.

Because a yellow color has been observed in the fat pads of Mongolian gerbils fed a nonpurified diet, we designed the current study to determine whether adult male gerbils would absorb beta-carotene intact from a test meal. Thirty-five gerbils (80-90 g) were adapted to the laboratory and fed a standard purified diet free of beta-carotene for 16-19 d. Gerbils were then fed a test meal consisting of 279 nmol of beta-carotene as 10% water-soluble beadlets suspended in 0.5 mL of Ensure. Gerbils (n = 5) were killed at 0, 2, 4, 6, 12, 24 or 72 h after the test meal, blood was obtained by cardiac puncture, and tissues were taken for beta-carotene analysis. No beta-carotene was detected in serum at 0 or 72 h, whereas beta-carotene was present at all other sampling times. Serum beta-carotene peaked at 4 h, at a level of 88 nmol/L. beta-Carotene was detected in the liver of all groups; however, the concentration increased from -34 pmol/g to a maximum concentration of 926 pmol/g at 24 h after the test meal. Other tissues also contained beta-carotene. The results demonstrate that Mongolian gerbils, like ferrets and preruminant calves, absorb beta-carotene intact when beta-carotene is provided at a physiological level in a test meal. This species may be particularly useful for evaluation of the role of antioxidants, such as beta-carotene, in LDL oxidation.

Administration, Oral↗
PubMed1994

Short-term psychotherapy of personality disorders.

OBJECTIVE: The efficacy of short-term psychotherapy has become an area of increasing interest. The primary objective of this study was to assess the results of two forms of short-term psychotherapy in patients with personality disorders. METHOD: Eighty-one patients with personality disorders were randomly assigned to brief adaptive psychotherapy, short-term dynamic psychotherapy, or a waiting list for therapy. Outcome at termination of therapy for the treatment groups and at the end of the waiting period for the waiting list group was evaluated by means of ratings of target complaints and scores on the SCL-90 and the Social Adjustment Scale. In addition, for 38 of the treated patients, target complaints were reevaluated an average of 1.5 years after treatment ended. RESULTS: Patients in the two therapy conditions improved significantly on all measures in comparison with the patients on the waiting list. There was no significant difference between the results in the two therapy conditions. The waiting list period averaged approximately 15 weeks; treatment averaged 40 weeks. At follow-up, after an average of 1.5 years, target complaint ratings were not significantly different from those at the termination of therapy. CONCLUSIONS: These data indicate that brief adaptive psychotherapy and short-term dynamic psychotherapy are effective for patients with certain types of personality disorder and that the two therapy approaches do not differ in overall outcome.

Adult↗
PubMed1994

Percutaneous hepatic vein isolation and high-dose hepatic arterial infusion chemotherapy for unresectable liver tumors.

PURPOSE: This prospective, nonrandomized trial evaluated a percutaneous isolated chemotherapy perfusion approach for treating advanced primary and metastatic liver tumors. Chemotherapy was administered via hepatic artery catheter and hepatic venous blood isolated by a novel percutaneous double-balloon inferior vena cava (IVC) catheter was passed through a detoxification/filtration cartridge in a venovenous bypass circuit. PATIENTS AND METHODS: Among 23 patients enrolled onto the study, 58 procedures were performed on 21 patients. Twelve patients received dose escalations of fluorouracil (5-FU) (1,000 mg/m2 to 5,000 mg/m2), and nine received dose escalations of doxorubicin (50 mg/m2 to 120 mg/m2). Pharmacokinetic studies included drug accumulation in the liver, extraction by detoxification filters, systemic exposure, and alterations of half-life. Each patient received two treatments at 3-week intervals. Those showing stabilization or response received additional treatments. RESULTS: There was a direct relationship between dose and peak concentration of drug entering the hepatic veins. The system functioned efficiently throughout the dose range, with extraction efficiencies ranging from 64% to 91% (P < .001). The hepatic vein drug levels showed a sixfold increase in 5-FU with dose escalation from 1,000 to 5,000 mg/m2, and a twofold increase in dox with dose escalation from 50 to 120 mg/m2 (P < .001, filter-mediated drug extraction). The treatments were accomplished with only an overnight hospital stay and no mortality. The common procedure-related toxicity was transient hypotension (grade I to II), due to catecholamine depletion by the filter. Dose-limiting toxicity (leukopenia) was observed in patients receiving 5-FU at a dose of 5,000 mg/m2 and doxorubicin at a dose of 120 mg/m2. Significant tumor response (> 95% reduction) was obtained in two patients receiving doxorubicin at 90 mg/m2 and 120 mg/m2. CONCLUSION: The use of a double-balloon catheter to isolate and detoxify hepatic venous blood during intraarterial therapy is technically feasible, safe, and allows administration of large doses of intrahepatic chemotherapy at short intervals. This approach should allow new dose-intensification strategies to increase tumor responses in primary and metastatic liver tumors.

Adenoma, Bile Duct↗
PubMed1992

"PCL" a new automatic fast reader suitable for in vivo dosimetry.

The authors present a new automatic TLD reader specially designed for medical dosimetric applications, which allow considerable time-saving. The "PCL" reader is based on an isothermal heating kinetics and can be used with TL material of any nature and any shape (powder, microrods, pellets). Doses from 1 microGy to 10 Gy can be measured, or higher doses by interposing an optical absorber in front of the PM. The readout system is controlled by an IBM compatible personal computer. Results can be printed under the form defined by the users and then can be straightly stored in a patient sheet or an experience book. Tests performed with LiF chips TLD 100 and 700 (HARSHAW), Li2B4O7:Mn discs LiB (ALNOR), LiF powder PTL 717 (DESMARQUET) and Li2B4O7:Cu powder (CEN-FAR) are presented. They show a good reproducibility and interesting dosimetric properties.

Humans↗
PubMed1991

Ventilatory threshold and maximal oxygen uptake during cycling and running in female triathletes.

Maximal oxygen uptake (VO2max) and the ventilatory threshold (Tvent) were measured during cycle ergometry (CE) and treadmill running (TR) in a group of 10 highly trained female triathletes. Tvent was defined as the VO2 at which the ventilatory equivalent for oxygen increased without a marked rise in the ventilatory equivalent for carbon dioxide. Female triathletes achieved a significantly higher mean (+/- SE) relative VO2max for running (63.6 +/- 1.2 ml.kg-1.min-1) than for cycling (59.9 +/- 1.3 ml.kg-1.min-1). When oxygen uptake measured at the ventilatory threshold was expressed as a percent of VO2max, the mean value obtained for TR (74.0 +/- 2.0% of VO2max) was significantly greater than the value obtained for CE (62.7 +/- 2.1% of VO2max). This occurred even though the total training time and intensity were similar for the two modes of exercise. Female triathletes had average running and cycling VO2max values that compared favorably with maximal oxygen uptake values previously reported for elite female runners and cyclists, respectively. However, mean running and cycling Tvent values (VO2 Tvent as%VO2max) were lower than recently reported values for single-sport athletes. The physiological variability between the triathletes studied and single-sport athletes may be attributed in part to differences in training distance or intensity, and/or to variations in the number of years of intense training in a specific mode of exercise. It was concluded that these triathletes were well-trained in both running and cycling, but not to the same extent as female athletes who only train and compete in running or cycling.

Adult↗
PubMed1991

Brief psychotherapy of personality disorders.

Thirty-two patients with personality disorder diagnoses were randomly assigned to two treatment conditions that vary on several techniques of brief dynamic psychotherapy. Seventeen patients constituted a waiting list control group. The two brief psychotherapies showed significant improvement on target complaints, SCL-90, and Social Adjustment Scale-SR compared with the control subjects. The two therapy groups were similar in overall outcome but showed interesting differences on several subscale measures. Process measurements of videotaped sessions revealed significant variations in frequencies of therapist interventions across the two treatment conditions, which validated planned differences in the treatment techniques.

Cognitive Behavioral Therapy↗
PubMed1990

Change in patient affect/defense ratio from early to late sessions in brief psychotherapy.

The current study examined changes in the ratio of patients' affective and defensive behaviors during the course of brief psychodynamic psychotherapy. Treatments of 16 patients were videotaped. For each patient, four sessions were evaluated with a minute-by-minute coding system of process variables. When patients were grouped according to outcome scores, significant differences between the high outcome and the average-to-low outcome groups emerged. During the early phase of treatment, patients in both groups showed an average of one affective response per five defensive responses. By the late phase of treatment, the high outcome patients showed a marked shift to one affective response per two defensive responses, while the low outcome patients remained the same. An incidental finding was a negative correlation between good outcome and the ratio of defensive behavior to total patient activity.

Affect↗
PubMed1990

Identification of calcium-calmodulin multifunctional protein kinase II in rabbit kidney.

Recent studies have demonstrated that calcium/calmodulin-dependent multifunctional protein kinase II (CaM-KII) inhibits the reconstituted Na(+)-H+ exchanger from the brush border membrane of proximal convoluted tubule of the rabbit kidney. The present studies were undertaken to evaluate the physiological relevance of this finding by establishing the presence of CaM-KII in rabbit kidney and proximal convoluted tubule cells by Northern RNA hybridization analysis to demonstrate the messenger RNA (mRNA) for CaM-KII and by a selective enzymatic assay of CaM-KII using a synthetic peptide substrate. A single 4.9 Kb mRNA was observed on hybridization of total RNA from rabbit kidney cortex and medulla and from an enriched suspension of rabbit kidney proximal convoluted tubules with a cDNA for rat brain CaM-KII. An enzyme assay using a synthetic peptide substrate representing the site phosphorylated by CaM-KII on glycogen synthase demonstrated calcium-calmodulin dependent protein kinase activity in both rabbit kidney cortex (specific activity of 662 +/- 127 nmol.min-1.mg protein-1) and proximal tubule cells (546 +/- 77 nmol.min-1.mg protein-1). These data establish the presence of CaM-KII in the rabbit kidney, and suggest a role for this enzyme in the control of renal electrolyte transport.

Animals↗