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D S Lu

Publications and source records attributed to D S Lu.

54 records · Page 3Linked to original sources
PubMed1993

In vitro evaluation of gallstone dissolution with methyl-tert-butyl ether and ultrasound energy.

Given the large number of cholecystectomies performed annually, a nonsurgical approach to gallstone therapy is of great interest. A laboratory ultrasound system has been developed to study enhancement of methyl-tert-butyl ether (MTBE) dissolution of human gallstones in vitro. A mathematical model that quantitatively characterizes the dissolution process via a rate constant has been developed. Using this model, the kinetics of 15 gallstones from a single patient were evaluated for three dissolution methods: 1) unstirred MTBE, 2) aspirated MTBE, and 3) ultrasonically enhanced MTBE. The results showed excellent fits between the model and measured dissolution rates. 195 kHz continuous-wave (CW) ultrasonically enhanced dissolution rates exhibited a 6.2 fold gain over the manually aspirated MTBE and a 49.5 fold gain over static MTBE dissolution. Investigation of 50% duty cycle pulsed mode ultrasound revealed that total power appears to be the determinant of the observed dissolution rates. Gallstone calcification showed a strong correlation with dissolution rates measured by the model.

Cholelithiasis↗
PubMed1993

Percutaneous management of hilar biliary malignancies with metallic endoprostheses: results, technical problems, and causes of failure.

Malignant obstruction at the biliary hilum is a challenging problem for percutaneous management because of the anatomy of the biliary hilum, which facilitates spread of tumor into multiple biliary radicles. Metallic self-expanding stents were used in 22 patients with hilar malignancies. Sixteen patients had focal common hepatic duct strictures, and six had multisegmental disease. Stents were placed in the biliary system with a single transhepatic approach in 16 patients with common hepatic duct strictures; stent placement in the right and left biliary ducts was performed with a bilateral transhepatic approach in five patients and with a single transhepatic approach in one patient. Metal stent occlusion occurred in six patients (27%) at a mean of 2.5 months after initial insertion. Stent occlusion was due to inspissated debris in two of these patients and to tumor overgrowth in four. The key to successful long-term treatment is to "overstent" to ensure adequate purchase above hilar tumors and insertion in a balanced position. Thus, the prevalence of tumor overgrowth is decreased.

Bile Duct Neoplasms↗
PubMed1993

Gastrostomy conversion to transgastric jejunostomy: technical problems, causes of failure, and proposed solutions in 63 patients.

Sixty-three radiologically guided conversions of gastrostomy to transgastric jejunostomy performed over a 4-year period were reviewed. Conversions succeeded in 31 of 38 surgically placed gastrostomies (82%), in 14 of 18 endoscopically placed gastrostomies (78%), and in seven of seven radiologically placed gastrostomies, for an overall success rate of 83%. Almost all failures (10 of 11 gastrostomies) were primarily the result of unfavorable fundal angulation of the surgical or endoscopic tract; unfavorable angulation was also the most common technical problem encountered in the successful conversions. Of the 52 successful conversions, 23 (44%) necessitated tube replacement: eight for spontaneous proximal migration of the tube, 11 for accidental tube dislodgment, and four for tube blockage. While most gastrostomy to transgastric jejunostomy conversions are simple to perform, in many cases the unfavorable angle of the original transcutaneous tract precludes jejunal intubation and may be a cause for early recoil of a successfully placed jejunal catheter back into the stomach. With early recognition of an unfavorable tract, a fresh transgastric jejunostomy through a new, properly angled puncture may be the preferred approach.

Adolescent↗
PubMed1992

Accelerated gallstone dissolution in methyl tert-butyl ether by sonication. An in vitro study.

OBJECTIVES: The authors tested the effect of 195 KHz therapeutic ultrasound energy on gallstone dissolution in concert with methyl tert-butyl ether (MTBE) in vitro. METHODS: Sixteen sets of three gallstones matched for weight and appearance were selected from 16 surgically resected human gallbladders. One stone from each set was analyzed for its density pattern by computed tomography (CT) and biochemically for cholesterol content. Based on CT appearance, the stones were classified into eight noncalcified, four partially calcified, and four heavily calcified sets. The three stones were subjected to dissolution with MTBE: one with simultaneous sonication via an experimental ultrasound unit, one with manual stirring, and one acted as control without added treatment. RESULTS: Sonication reduced the dissolution time of noncalcified stones by 96% (range, 94%-98%; standard deviation [SD], 2%) relative to controls, and it was three to four times more effective than manual stirring. It was similarly effective in helping to dissolve partially calcified stones, but not heavily calcified stones. CONCLUSIONS: This study demonstrates the positive effect of sonication in accelerating gallstone dissolution with MTBE in vitro for stones without heavy calcification.

Cholelithiasis↗
PubMed1991

Percutaneous transhepatic biliary drainage for malignant biliary obstruction: a report of two cases with five year survival.

We report two cases of malignant biliary obstruction in whom percutaneous transhepatic biliary drainage has contributed to patient survival of more than 5 years. To our knowledge, this represents the first such case report in the literature. Both patients suffered biliary obstruction from poorly differentiated adenocarcinoma, in all likelihood from the head of the pancreas. Morbidity has been low with only two episodes of significant sepsis and one episode of GI haemorrhage in one patient and both patients were able to enjoy an excellent quality of life. These cases demonstrate that percutaneous biliary drainage has a place not only in the short term palliation of patients with malignant biliary obstruction, but in the long term as well.

Adenocarcinoma↗
PubMed1990

Gallstone dissolution in methyl tert-butyl ether after mechanical fragmentation: in vitro study.

Twenty sets of three gallstones matched for weight and appearance were selected from 20 surgically resected human gallbladders to test the effect of intracorporeal mechanical fragmentation on gallstone dissolution with methyl tert-butyl ether in vitro. One stone from each set was fragmented by a mechanical lithotriptor and then treated with methyl tert-butyl ether, and one was used as control and was treated intact. The third stone was analyzed for its density pattern on CT and biochemically for its cholesterol and calcium content. On the basis of CT appearance, the stones were classified as noncalcified, partially calcified, or heavily calcified. Mechanical fragmentation reduced dissolution time by 25-69% (mean +/- SD, 44 +/- 16%) for the noncalcified stones and by 20-42% (mean +/- SD, 30 +/- 8%) for the partially calcified stones. No significant reduction was observed for the heavily calcified stones. The degree of reduction was inversely related to maximal stone density (r = -.72) and was independent of its pattern of calcification. This study shows that mechanical fragmentation is effective in accelerating gallstone chemolysis by methyl tert-butyl ether for noncalcified and partially calcified but not for heavily calcified stones.

Calcium↗
PubMed1989

[A sarcoma-static new species of Pseudomonas, Pseudomonas jinanensis sp. nov].

A strain of Gram negative bacteria was isolated from the surface soil of Wuying Hill at Jinan, Shandong province with Gause's medium in 1973. It is a strain of antagonistic bacteria for hysterocervicoma, hepatoma and melanoma of mice screened from 2100 strains of bacteria. It is also antagonistic to Staphylococcus aureus, Bacillus subtilis and Micrococcus. It is a Gram negative bacterium with lophotrichous polar flagella. Straight rods in shape or with a little slightly curved rods, 0.5-0.6 X 1-2 microns, randomly arranged, poly-beta-hydroxybutyrate granules are accumulated in cells after 2-5 days cultivation. Water green soluble pigment and green fluorescent pigment are produced. Respiratory metabolism, chemoorganotroph, many carbon-containing organic compounds can be used as carbon sources, such as glucose, trehalose, ethanol, cellulobiose, fucose, arginine and betaine, but propionic acid or tartaric acid is not utilized. Inorganic nitrogen containing compounds can be used ae the sole source of nitrogen. No growth factor is necessary for growth. Gelatin is hydrolyzed. Starch and cellulose are not hydrolyzed. Nitrate is not reduced. Arginine dihydrolase is produced. Levan is produced from sucrose. Growth occurs from 7 degrees C to 37 degrees C and from pH 5.65-8.40. No growth occurs at 40 degrees C and at pH value below 4.86. It can not grow autotrophically with hydrogen. Its G + C contents in DNA is 58.1 mol%. DNA-DNA hybridization experiments reveals a relatedness value of 58.6% between this strain and Ps. fluorescens. The above evidence shows that this strain differs from all species known in Pseudomonas, such as Pseudomonas fluorescens group. Pseudomonas caryophylli, Pseudomonas cepacia, Pseudomonas marginata, Pseudomonas acidovorans, Pseudomonas testosteroni and Pseudomonas delafieldii.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Survey of Campylobacter jejuni/coli infection and risk factors in children].

From March to May 1987, 798 children under 7 years of the outpatients in Chengdu district were examined and their stool samples cultured for Campylobacter jejuni/coli. C. jejuni/coli was isolated from 31 (9.51%) of 326 children with diarrhea and 22 (4.66%) of 472 children with non-diarrhea. The difference was significant (P less than 0.05). This result indicated that C. jejuni/coli is an important pathogen of children diarrhea in Chengdu district. Meanwhile, by inquiry we investigated risk factors related with C. jejuni/coli infections. Case group was consisted of 53 children with C. jejuni/coli positive. For each case, 3 controls were chosen from 745 children with C. jejuni/coli negative and matched according to age (less than 6 month), sex, living place (city or countryside), way of feeding, and whether to have diarrhea or not. The results has shown that contact with animals a week before being ill and habit of intake of food with hands are risk factors of C. jejuni/coli infection of childhood in Chengdu, with an odd ratio of 2.97 and 2.71 respectively. This provides valuable information about the prevention of C. jejuni/coli infection.

Campylobacter Infections↗
PubMed1985

Mechanism of depressed immunity in chronic renal failure: effect of cyclophosphamide pretreatment on delayed-type hypersensitivity skin reaction.

An imbalance in immunoregulatory mechanisms resulting in a relative increase in suppressor cell activity has been implicated in the development of the immunological deficit observed in chronic uremia. The present study was designed to assess whether cyclophosphamide pretreatment would preferentially enhance immune responses of chronically uremic animals. Delayed-type hypersensitivity (DTH) skin responses to oxazolone were found significantly decreased in chronically uremic mice as compared with sham-operated and normal controls. The administration of a single high dose (250 mg/kg) of cyclophosphamide 3 days prior to skin sensitization with oxazolone resulted in enhancement of DTH responses in all mice groups. Maximal increases in DTH responses following cyclophosphamide treatment was 61.6% in chronically uremic mice, and 100.5 and 86.2% in sham-operated and normal controls, respectively. The levels of active metabolites of cyclophosphamide, as estimated indirectly by the degree of myelosuppression achieved, were comparable across the 3 mice groups. These results thus fail to provide evidence for excessive numbers of cyclophosphamide-sensitive suppressor cells in chronic experimental uremia.

Animals↗
PubMedDate not supplied

IR and Raman spectroscopic studies on coulombic interaction between water-soluble porphyrins and nucleic acids.

We have shown previously that the N-methylpyridyl group vibrations of water-soluble porphyrins, M(TMpy-P4), are shifted to lower frequencies (0.5-2.6 cm-1) as a result of coulombic interaction between the N(+)-CH3 group of M(TMpy-P4) and the PO2 group of a nucleic acid. We have now turned over our attention to the effect of this coulombic interaction on the PO2 group vibrations of nucleic acids. Using Fourier transform ir and Raman spectroscopy, we found that the va(PO2) at 1221 cm-1 is shifted 12 approximately 17 cm-1 to higher frequencies, whereas the vs(PO2) at 1087 cm-1 is shifted 18 approximately 26 cm-1 to lower frequencies, when DNA is mixed with M(TMpy-P4). These results indicate that the N(+)-CH3 group of M(TMpy-P4) interacts preferentially with one of the two oxygen atoms of the PO2 group of the DNA duplex.

DNA↗
PubMedDate not supplied

MR-guided percutaneous ethanol ablation of liver tissue in a .2-T open MR system: preliminary study in porcine model.

The purpose of this study was to test the feasibility of MR-guided percutaneous ethanol ablation of liver tissue on a .2-T open MR scanner. Needles were placed by MR guidance first into an ex vivo sheep liver and then into livers of three anesthetized pigs, and injection of 10 ml of 96% alcohol was performed. T1 fast low-angle shot (FLASH), T2 turbo spin echo (TSE), and T1 spin echo (SE) images were obtained after incremental volumes of injection. In one pig, simultaneous injection of saline into normal liver was also performed with subsequent pathological correlation. Ethanol-infiltrated liver was hypointense to liver on all sequences, whereas saline caused no tissue signal changes on T1 SE and either isointense or hyperintense changes on T2 TSE images. Pathological examination confirmed ethanol-induced acute liver changes as compared with the control. MR guidance of needle placement and monitoring of ethanol effects on liver tissue is feasible. This may have implications for potential MR-guided hepatic tumor ablation.

Animals↗
PubMedDate not supplied

MR-guided procedures using contemporaneous imaging frameless stereotaxis in an open-configuration system.

Frameless MR-guided procedures have had limited application using conventional closed magnets, due largely to the technical difficulties involved. As a result of in-room MR image-monitoring capabilities, new open-design magnets now allow frameless stereotaxis using contemporaneous imaging to guide more invasive procedures. We evaluate our clinical experience with this new technique. An open-design 0.2 T magnet (Siemens OPEN) combined with an in-room monitor was used for 33 frameless MR-guided procedures (aspiration cytology, biopsy, and/or treatment) in a variety of locations in the head, neck, spine, brain, pelvis, and abdomen. Success of the procedure was based on the ability to accurately position the instrument in the target region to allow biopsy and/or treatment. The open-design magnet allowed the physician to directly access the patient for frameless stereotaxis as the procedure was performed. The in-room monitor provided contemporaneous imaging feedback during the procedure for successful placement of the instrument in the target region. Twenty-eight biopsy and five treatment procedures were performed. In all cases the technique resulted in successful placement of the instrument within the target tissue to complete the procedure. MR-guided procedures using contemporaneous imaging frameless stereotaxis are possible in an open-design magnet with in-room image monitoring and offer exciting possibilities for further development.

Adolescent↗
PubMedDate not supplied

Hepatic metastases from breast carcinoma: comparison of noncontrast, arterial-dominant, and portal-dominant phase spiral CT.

PURPOSE: The purpose of this work was to determine the relative value of noncontrast (NC), arterial-dominant (AD), and portal-dominant (PD) phase images in spiral CT of the liver for breast cancer metastases. METHOD: Forty-four spiral CT scans in 18 patients with hepatic metastases from breast cancer were retrospectively reviewed by three radiologists. Subjective evaluations of overall lesion conspicuity and margination were graded on a 5 point scale for NC, AD, and PD phase images, and the three phases were also ranked for demonstration of overall tumor volume. Those scans with hypervascular lesions were separately analyzed, resulting in three groups (all, hypervascular, hypovascular). RESULTS: For lesion conspicuity and margination for the entire study group, AD phase images showed the lowest grades (1.97 and 1.83), whereas the PD phase showed the highest grade (3.34 and 3.14; p < 0.0001) followed by NC (2.36 and 2.42; p < 0.0001). For the hypervascular subgroup, the AD phase also showed the lowest grades (2.39 and 2.24). In no case did the AD phase show more lesions than the combination of NC and PD phases. For depiction of overall tumor volume, the AD phase had the lowest ranking (2.51) compared with the NC and PD phases (1.71 and 1.78; p < 0.001). For the hypervascular subgroup, the AD phase had the lowest ranking (2.33) compared with the NC and PD phases (1.39 and 2.27; p < 0.0001). CONCLUSION: The AD phase is not required for lesion detection in spiral CT for hepatic metastases from breast carcinoma. The NC phase depicts the maximal tumor volume.

Adult↗