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Biomedical subjects

B R Lee

Publications and source records attributed to B R Lee.

At least 19 recordsLinked to original sources
PubMed2005

Laparoscopic bowel injury in an animal model: monocyte migration and apoptosis.

BACKGROUND: Unrecognized laparoscopic bowel injury has a delayed and covert presentation. Differences in monocyte migration and apoptosis between laparoscopic and open bowel injury were determined. METHODS: For this study, 24 rabbits were divided into laparoscopic (n = 9) and open surgical (n = 9) bowel injury groups and a control group (n = 6) without bowel injury. Bowel injury was created using monopolar electrocautery. The animals were killed 1 day, 1 week, and 2 weeks after surgery. Monocyte migration assay was performed across a modified Boyden chamber. Apoptosis was assessed by DNA fluorescent stain H-33342. RESULTS: In laparoscopy, monocyte apoptosis was decreased (p < 0.001), and migration was increased (p < 0.05), as compared with the open group. Apoptosis increased over time in both study groups, and was higher than in the control group (p < 0.001). Migration was decreased in both study groups as compared with the control group (p < 0.05) CONCLUSIONS: These results suggest decreased immune system priming with laparoscopic bowel injury, which may contribute to the masking of relevant signs and symptoms of peritonitis.

Animals↗
PubMed2005

Analysis of testis-specific transcripts in the chicken.

Sequences of candidate chicken testis-specific genes were analysed in order to develop a resource for functional genomic studies of the testis and male germ cells. Tentative consensus sequences (TC) containing expressed sequence tags expressed in testis libraries were selected from the TIGR Gallus gallus Gene Index, resulting in 292 TC. The transcriptional expression of these genes were evaluated in several chicken tissues, including testis and ovary. One hundred ten of the 292 TC were expressed in a testis-specific manner. Annotation of the TC using the Gene Ontology database terms showed that the proportion of testis-specific TC that were classified as having catalytic activity (within the molecular function branch) was higher than the proportion of total chicken TC classified in the same way. Our results may facilitate the investigation of testis-specific genes and their functional analysis in the chicken, as well as in other avian species.

Animals↗
PubMed2004

Effect of Endo-GIA vascular staple size on laparoscopic vessel sealing in a porcine model.

BACKGROUND: Two sizes of endoscopic gastrointestinal anastomosis (Endo-GIA) staples are currently available for vascular control. The purpose of this study was to compare the Endo-GIA 30-2.0 mm with the Endo-GIA 30-2.5 mm vascular staple. METHODS: The renal blood vessels, aorta, and vena cava were divided laparoscopically using the Endo-GIA 30-2.0 and 30-2.5 mm in four pigs, respectively. The arterial and venous segments were harvested en bloc for ex vivo burst pressure studies. RESULTS: Both 2.0-mm and 2.5-mm staples achieved vessel sealing at supraphysiologic mean burst pressures (> or =310 mmHg). There were no statistical differences between mean burst pressures of vessels stapled by 2.0-mm compared to 2.5-mm staples. Both staples sealed arteries up to 17 mm and veins up to 22 mm in diameter. CONCLUSION: Endo-GIA 30-2.0 mm and 30-2.5 mm vascular staples are equivalent in sealing vessels at supraphysiologic mean burst pressures.

Anastomosis, Surgical↗
PubMed2004

No panacea for drainage after percutaneous nephrolithotomy.

BACKGROUND AND PURPOSE: The optimal postoperative drainage system for patients undergoing percutaneous nephrolithotomy (PCNL) has not yet been determined. Each of the different tubes available has theoretical advantages and disadvantages. The objective of this study was to determine if any one system of post-PCNL drainage has any significant advantage over the others. PATIENTS AND METHODS: Sixty patients were randomized to either a 24F Re-entry tube (Group 1), an 8F pigtail catheter (Group 2), or a double-J stent (Group 3) (N = 20 for all groups). The double-J stent patients also had an 18F Councill catheter as a nephrostomy tube, which was removed on the morning of postoperative day 1. The three groups were well-matched for age, stone size, operative time, and mean number of percutaneous tracts (P > 0.05 for all). Data collected included intraoperative findings, postoperative analog pain scores and narcotic usage, presence of extravasation on postoperative nephrostogram, presence of perinephric fluid on postoperative ultrasound scans, length of stay, and whether leakage from the nephrostomy site persisted more than 48 hours after tube removal. RESULTS: There were no statistically significant differences among the three groups in terms of change in hematocrit or number of patients requiring blood transfusion; in the incidence of tube blockage, extravasation, or presence of perinephritic fluid; or in complication rates, length of hospital stay, or persistent leakage after tube removal. There was a strong trend to less postoperative leakage with the 8F pigtail than the Reentry tube (P = 0.05). Postoperative analog pain scores and narcotic usage were equivalent for all three groups. Patients Groups 1 and 2 were free of all tubes sooner than patients in Group 3 (P < 0.001). CONCLUSIONS: This study did not demonstrate an overwhelming advantage of any one drainage system over the others. All three systems were equally tolerated by patients. There may be less chance of prolonged nephrostomy-site leakage with an 8F pigtail catheter.

Catheterization↗
PubMed2004

Are new-generation flexible ureteroscopes better than their predecessors?

OBJECTIVE: To compare two newly designed flexible ureteroscopes with their respective predecessors, to determine whether design advances have overcome the limitation of tip deflection, which may interfere with diagnosis and treatment of lower pole renal pathology. MATERIALS AND METHODS: Two new-generation flexible ureteroscopes, the DUR-8 Elite (ACMI, Southborough, MA, USA) and 11278AU (Karl Storz Endoscopy, Culver City, CA, USA) were compared with their previous models, the ACMI DUR-8 and the Storz 11274AAU. Active tip deflection and irrigation flow rates with and without various endoscopic tools were assessed. Specifications, purchase prices and repair costs were obtained from each manufacturer. The field of view and screen image size of each ureteroscope were also compared. RESULTS: The ACMI DUR-8 Elite and the Storz 11278AU had improvements of 79 degrees and 144 degrees, respectively, from their respective older models. Although the tip deflection of all ureteroscopes was compromised by inserting different endoscopic tools, these new instruments were less affected. With a 3 F basket inside the working channel, the ACMI DUR-8 Elite and the Storz 11278AU had only 0.7% and 2.8% loss of upward tip deflection, compared with their older models, at 9.6% and 5.0%, respectively. However, the flow rates of these new instruments were decreased. CONCLUSION: The new flexible ureteroscopes have significantly better active tip deflection than previous models, both with and without endoscopic instrumentation inserted. However, improved flexibility is at the expense of decreased flow rates and higher purchase costs.

Equipment Design↗
PubMed2001

Molecular cloning and functional expression of bovine brain GABA transaminase.

We isolated a cDNA that encodes the bovine brain gamma-aminobutyrate transaminase (GABA-T; EC 2.6.1.19) from the lambda gt 11 cDNA library, which showed a high degree of sequence similarity to the corresponding enzymes from various sources. Northern blot analysis revealed two differentially expressed GABA-T transcripts of approximately 2.0 and 6.0 kb in the bovine tissues. Southern blot analysis indicates that the two GABA-T transcripts are encoded in a greater-than 10-kb, single-copy gene. Bovine GABA-T cDNA was expressed in E. coli using the pGEX bacterial- expression vector system. The overexpressed GABA-T was enzymatically active after purification, and it had very similar kinetic parameters when compared with those of other mammalian GABA-Ts.

4-Aminobutyrate Transaminase↗
PubMed2001

NF-kappa B mediates the adaptation of human U937 cells to hydrogen peroxide.

Low doses of oxidative stress can induce cellular resistance to subsequent higher doses of the same stress. By using human U937 leukemia cells, we previously demonstrated that H(2)O(2) can induce such an adaptive response without elevating the cellular capacity to degrade H(2)O(2), and were able to confer the cells a cross-resistance to an H(2)O(2)-independent lethal stimulus, C(2)-ceramide. In this study, it was found that the adaptation is accompanied by the translocation of cytoplasmic NF-kappa B to the nuclei. This event was promoted or abolished when either IKK alpha or a dominant negative mutant of I kappa B, respectively, was overexpressed. The overexpression of IKK alpha also resulted in the suppression of H(2)O(2)-induced cell death and DNA fragmentation, whereas these events were accelerated by the expression of the I kappa B mutant. The protective effect of IKK alpha was accompanied neither by an elevation of protein levels of various antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase, nor by an increase in the cellular capacity to consume H(2)O(2). Moreover, the overexpression of IKK alpha resulted in an enhancement of H(2)O(2)-induced resistance to C(2)-ceramide. The overall data suggest that NF-kappa B mediates the H(2)O(2) adaptation induced in a manner independent of H(2)O(2)-degrading activity.

Adaptation, Physiological↗
PubMed2001

Brain succinic semialdehyde dehydrogenase: identification of reactive lysyl residues labeled with pyridoxal-5'-phosphate.

An NAD+ dependent succinic semialdehyde dehydrogenase from bovine brain was inactivated by pyridoxal-5'- phosphate. Spectral evidence is presented to indicate that the inactivation proceeds through formation of a Schiff's base with amino groups of the enzyme. After NaBH(4) reduction of the pyridoxal-5'-phosphate inactivated enzyme, it was observed that 3.8 mol phosphopyridoxyl residues were incorporated/enzyme tetramer. The coenzyme, NAD+, protected the enzyme against inactivation by pyridoxal-5'-phosphate. The absorption spectrum of the reduced and dialyzed pyridoxal-5'-phosphate-inactivated enzyme showed a characteristic peak at 325 nm, which was absent in the spectrum of the native enzyme. The fluorescence spectrum of the pyridoxyl enzyme differs completely from that of the native enzyme. After tryptic digestion of the enzyme modified with pyridoxal-5'-phosphate followed by [3H]NaBH4 reduction, a radioactive peptide absorbing at 210 nm was isolated by reverse-phase HPLC. The sequences of the peptide containing the phosphopyridoxyllysine were clearly identical to sequences of other mammalian succinic semialdehyde dehydrogenase brain species including human. It is suggested that the catalytic function of succinic semialdehyde dehydrogenase is modulated by binding of pyridoxal-5'-phosphate to specific Lys(347) residue at or near the coenzyme-binding site of the protein.

Aldehyde Oxidoreductases↗
PubMed2001

Management of malignant extrinsic compression of the ureter by simultaneous placement of two ipsilateral ureteral stents.

BACKGROUND AND PURPOSE: Extrinsic ureteral obstruction caused by various malignancies often necessitates urinary diversion. The use of single ureteral stents as a form of urinary diversion results in a high failure rate, while the use of two ipsilateral stents has shown promising results. We report our experience using the latter technique. PATIENTS AND METHODS: Between 1996 and 2001, four male and three female patients with a mean age of 65 years (range 37-95 years) who had extrinsic compression of the ureters underwent single stent management to relieve obstruction. Ureteral obstruction was secondary to prostate cancer (N = 3), cervical cancer (2), non-Hodgkin's lymphoma (1), and transitional-cell cancer of the bladder and ureter (1). After failure of such management, two 7F stents or a combination of 8F/6F double-J ureteral stents were placed. The stents were changed every 4 to 6 months. Follow-up included serial renal ultrasound scans and serum creatinine measurements. RESULTS: Ureteral stricture length ranged from 2 to 4 cm. Insertion of two double-J ureteral stents in a single ureter was successful in all cases. During the mean follow-up of 16 months (range 1-38 months), the ureteral stents were tolerated by all patients, without significant discomfort. Marked improvement of hydronephrosis and alleviation of flank pain was noted in all patients. Three patients have died at 1 to 3 months. Renal function improved, with a mean decline in the serum creatinine concentration from 3.2 mg/dL to 1.48 mg/dL in the five patients tested. CONCLUSION: Simultaneous placement of two double-J ureteral stents for the management of ureteral obstruction secondary to a malignancy is a safe and effective technique.

Adult↗
PubMed2001

Management of ureteral stricture disease during laparoscopic ureteroneocystostomy.

BACKGROUND AND PURPOSE: Laparoscopic surgery has many applications in urology. The surgical management of obliterative ureteral stricture disease using laparoscopy has not been widely reported. We recently implemented this technique in an adult patient with an obliterative ureteral stricture. METHODS: A transperitoneal refluxing right ureteral reimplantation was performed using the Endostitch device. Placement of the new ureteral orifice in the bladder was monitored by simultaneous cystoscopy and laparoscopy. The anastomosis was performed without tension, torsion, or angulation and was stented for 4 weeks. RESULTS: The operative time was 233 minutes. The blood loss was minimal. There were no intraoperative complications, and the postoperative hospital course was uneventful. CONCLUSION: Laparoscopic ureteral reimplantation is a safe and feasible technique. Cystoscopic determination of the neoureteral orifice is helpful. The Endostitch device is a useful adjunct in this procedure.

Adult↗
PubMed2001

Retroperitoneoscopic radiofrequency ablation of a solid renal mass.

PURPOSE: To report a new technique for radiofrequency (RF) ablation of a solid renal mass. PATIENT AND METHODS: An 83-year-old man with a history of chronic renal insufficiency was found to have solid mass in the right kidney. Retroperitoneoscopic localization of the renal mass was accomplished using intraoperative ultrasonography. The lesion was treated with a 14-gauge RITA Starburst XL probe (Rita Medical Systems, Inc., Mountain View, CA). RESULTS: The total treatment time included two cycles of 5.5 minutes. There were no intraoperative complications. Tissue desiccation was noted during treatment. A CT scan 48 hours after ablation showed a decrease in the density of the lesion suggestive of coagulation necrosis. The postoperative hospital course was uneventful. CONCLUSION: The retroperitoneal laparoscopic technique is a feasible approach to performing RF ablation of a solid renal mass. It facilitates direct insertion of the RF probe, allows viewing and avoidance of adjacent structures such as bowel, and permits better staging by enabling biopsy of perirenal fatty tissue.

Aged↗
PubMed2001

Remote percutaneous renal access using a new automated telesurgical robotic system.

Previous clinical application of remote telesurgery has been the use of a novel system of video teleconferencing equipment along with remote control of a laparoscopic camera at distances over 11,000 miles. Recently, a robotic system has been developed to assist with percutaneous renal surgery. This robot has been incorporated into the telesurgical system to allow remote needle placement into the renal collecting system under radiological guidance. The main component of the telesurgical system is a low degree of freedom robot called "PAKY" (percutaneous access of the kidney). It is custom designed for fluoroscopic guided percutaneous needle insertion into the renal collecting system. The robot is a six-degrees of freedom device. However, when the skin entry site is fixed and held in position, only two degrees of freedom are required to orient the needle in the correct plane for accurate insertion. Remote control of the robot was accomplished over a plain old telephone system (POTS) line. On June 17, 1998, the first remote telerobotic percutaneous renal access procedure was performed between the Johns Hopkins Hospital, Baltimore, Maryland, and Tor Vergata University, Rome, Italy. This new telesurgical robot was successful in term of obtaining percutaneous access within 20 min, with two attempts to obtain entry into the collecting system. This robot represents the first system for performing remote telesurgical interventions in the kidney and demonstrates the feasibility and safety of assisting accurate and rapid needle access to the kidney during percutaneous procedures.

Aged↗
PubMed2001

Three-dimensional structures of protein-protein complexes in the E. coli PTS.

The bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) includes a collection of proteins that accomplish phosphoryl transfer from phosphoenolpyruvate (PEP) to a sugar in the course of transport. The soluble proteins of the glucose transport pathway also function as regulators of diverse systems. The mechanism of interaction of the phosphoryl carrier proteins with each other as well as with their regulation targets has been amenable to study by nuclear magnetic resonance (NMR) spectroscopy. The three-dimensional solution structures of the complexes between the N-terminal domain of enzyme I and HPr and between HPr and enzyme IIA(Glc) have been elucidated. An analysis of the binding interfaces of HPr with enzyme I, IIA(Glc) and glycogen phosphorylase revealed that a common surface on HPr is involved in all these interactions. Similarly, a common surface on IIA(Glc) interacts with HPr, IIB(Glc) and glycerol kinase. Thus, there is a common motif for the protein-protein interactions characteristic of the PTS.

Amino Acid Sequence↗
PubMed2000

Identification of copper ligands in Aspergillus oryzae tyrosinase by site-directed mutagenesis.

Copper ligands of the recombinant tyrosinase from the fungus Aspergillus oryzae expressed in Saccharomyces cerevisiae or Escherichia coli were identified by site-directed mutagenesis. The recombinant protyrosinases expressed in S. cerevisiae were assayed for catalytic activities of mono-oxygenase and L-dopa oxidase at pH 5.5 after acid shock at pH 3.0. Replacements of His-63, His-84, His-93, His-290, His-294, His-332 or His-333 with asparagine resulted in mutant enzymes exhibiting no activities. The site-directed mutant Cys82Ala showed that Cys-82 was also an essential residue for the activity. We obtained homogeneous preparations of activated tyrosinases from mutated thioredoxin fusion gene products expressed in E. coli by acid shock. The copper contents of engineered mutants and wild-type enzyme expressed in E. coli were determined by atomic absorption spectrophotometry. The wild-type enzyme contained 2 g-atoms of copper/mol of the subunit. The His63Asn, His84Asn, His93Asn, His290Asn, His294Asn, His332Asn, His333Asn or Cys82Ala substitution decreased copper binding by approx. 50%, indicating that the mutants contain only approx. 1 g-atom of copper/mol of the subunit. The five mutants His63Asn, His93Asn, His290Asn, His294Asn and Cys82Ala contain only one copper ion, which is fully detectable by EPR. From the correlation of g( parallel) and (Cu)A( parallel), we deduced that the nitrogen or sulphur donors in the copper ligands should be in a square or a distorted tetrahedral geometric environment. In further atomic absorption spectrophotometry experiments, no copper atom was observed in the seven double mutants His63Asn/His290Asn, His63Asn/His294Asn, His63Asn/His332Asn, His63Asn/His333Asn, Cys82Ala/His290Asn, His84Asn/His333Asn and His93Asn/His290Asn. We propose a new structure of active sites of tyrosinase from A. oryzae: the most likely binding sites of tyrosinase for Cu(A) are His-63, His-84 and His-93, with the remaining conserved Cys-82 providing the fourth ligand. Cu(B) liganded by four histidine residues, His-290, His-294, His-332 and His-333, is identified as new binding motif of Cu(B).

Alanine↗
PubMed2000

International telementoring: a feasible method of instruction.

Since the advent of improved telecommunication technology, greater bandwidth capability, medical robotics, and digital video technology, telemedicine has evolved. Telesurgical telementoring is an advanced form of telemedicine. An experienced surgeon can conduct, guide and mentor a second surgeon from a remote location. The historical method of teaching surgeons new operative techniques is exemplified in residency training: having individuals work with experienced teachers. Unfortunately, it is impractical for these specialized minimally invasive surgeons to travel and proctor generally trained surgeons each time a new surgical technique is developed. Telesurgical telementoring may represent a method to teach and mentor remote surgeons, as well as allow educational opportunities.

Education, Medical↗
PubMed2000

Feasibility of ablating normal renal parenchyma by interstitial photon radiation energy: study in a canine model.

BACKGROUND AND PURPOSE: A miniature photon radiosurgery system (PRS) has been described as an alternative to surgical resection and external-beam radiation for tumors and may now offer an alternative for ablation of renal lesions. We evaluated the feasibility of ablation by PRS in a normal parenchyma canine model. MATERIALS AND METHODS: Twelve mongrel dogs were used in this survival study. In the left and right kidneys of each animal, a peripheral lesion and central-hilar lesion, respectively, were induced with PRS. The probes were placed in the renal parenchyma, and local radiation of 15 Gy at a radius of 1.3 cm was delivered over 10 minutes. Serum electrolytes were measured serially. Computed tomography scans were obtained, and the animals were sacrificed for pathologic correlation. In a separate study, the liver received three additional treatments of 10 to 20 minutes of radiation. RESULTS: Eleven dogs survived this 6-month study and were sacrificed as scheduled. One animal expired after 2 weeks from radiation-induced fulminant hepatic failure with normal renal function. No other complications were observed. The average lesion size was 2.5 cm in diameter. Histologic analysis confirmed coagulative necrosis with sharp demarcation from the surrounding parenchyma. CONCLUSION: Preliminary studies demonstrate the feasibility of PRS ablation of the renal parenchyma. Further tumor model testing will be important to determine the ultimate efficacy of local photon radiation energy.

Animals↗