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Biomedical subjects

H S Xu

Publications and source records attributed to H S Xu.

At least 19 recordsLinked to original sources
PubMed2004

Isospin diffusion and the nuclear symmetry energy in heavy ion reactions.

Using symmetric 112Sn+112Sn, 124Sn+124Sn collisions as references, we probe isospin diffusion in peripheral asymmetric 112Sn+124Sn, 124Sn+112Sn systems at an incident energy of E/A=50 MeV. Isoscaling analyses imply that the quasiprojectile and quasitarget in these collisions do not achieve isospin equilibrium, permitting an assessment of isospin transport rates. We find that comparisons between isospin sensitive experimental and theoretical observables, using suitably chosen scaled ratios, permit investigation of the density dependence of the asymmetry term of the nuclear equation of state.

Journal Article↗
PubMed2001

Isotopic scaling in nuclear reactions.

A three parameter scaling relationship between isotopic distributions for elements with Z< or =8 has been observed. This allows a simple description of the dependence of such distributions on the overall isospin of the system. This scaling law (termed isoscaling) applies for a variety of reaction mechanisms that are dominated by phase space, including evaporation, multifragmentation, and deeply inelastic scattering. The origins of this scaling behavior for the various reaction mechanisms are explained. For multifragmentation processes, the systematics is influenced by the density dependence of the asymmetry term of the equation of state.

Journal Article↗
PubMed2001

In situ hybridization detection of calcitonin mRNA in routinely fixed, paraffin-embedded tissue sections: a comparison of different types of probes combined with tyramide signal amplification.

In situ hybridization (ISH) is a powerful molecular tool used to visualize nucleic acids in tissues and cells. However, its use is limited by the relative lack of sensitivity in detecting low copy numbers of nucleic acids. Several strategies have been developed to improve the threshold levels of in situ detection of nucleic acid by amplification of either target nucleic acid sequences before ISH (such as in situ polymerase chain reaction) or after the hybridization procedure (such as tyramide signal amplification [TSA]). The authors compared the use of different types of probes to detect calcitonin mRNA in 10 cases of formalin-fixed, paraffin-embedded medullary thyroid carcinoma with and without TSA. In addition, dot blot hybridization was used to compare the signal amplification by TSA with oligonucleotide. cDNA, and cRNA probes. These results show that cRNA probes are the most sensitive types of probes for detecting mRNA molecules in formalin-fixed, paraffin-embedded tissue sections and that tyramide amplification can increase the sensitivity for detection of calcitonin mRNA in formalin-fixed, paraffin-embedded tissue sections at least 2- to 4-fold with cRNA probes.

Base Sequence↗
PubMed2000

N-Propionyl-1,2-benzisoselenazol-3(2H)-one.

The title compound, C(10)H(9)NO(2)Se, crystallizes as flat molecules linked by selenium-oxygen interactions [Se.O = 3.189 (4) A] into a linear chain along the a axis of the triclinic cell. The bond dimensions that are derived from ab initio geometry optimization calculations are similar to those determined from the diffraction measurements.

Journal Article↗
PubMed1998

In situ hybridization detection of low copy nucleic acid sequences using catalyzed reporter deposition and its usefulness in clinical human papillomavirus typing.

In situ hybridization (ISH) detection of low copy DNA and RNA sequences using nonisotopic probes has been difficult in the past because of a lack of sensitivity. Several techniques, such as ISH with radioisotopic-labeled probes, in situ polymerase chain reaction, in situ reverse transcription polymerase chain reaction, self-sustained sequence replication, and chemiluminescence, have allowed increased sensitivity but have required specialized and often expensive equipment, lengthy protocols, and in the case of radioactive probes, there has been an associated increased health risk. Catalyzed reporter deposition (CARD) combined with ISH (CARD-ISH) increases the signal-generating potential of labeled hybridized probes and allows the detection of low copy sequences of nucleic acids in formalin-fixed, paraffin-embedded tissue sections. To determine the sensitivity of CARD-ISH to detect nucleic acids in routinely processed specimens, we analyzed the detection of HPV 16 and 18 infection in formalin-fixed, paraffin-embedded sections of cultured cell lines, including CaSki cells with 400-600 copies of HPV 16, HeLa 229 cells with 10-50 copies of HPV 18, and SiHa cells with 1-2 copies of HPV 16 using a conventional ISH method and by CARD-ISH. In addition, 20 cases of clinical specimens previously analyzed for HPV 6, 11, 16, 18, 31, 33, and 51 with the Enzo PathoGene kit (Enzo Diagnostics, Inc., Farmingdale, NY, U.S.A.) were reexamined with the CARD-ISH method. The CARD-ISH system detected one to two copies of HPV 16 in the SiHa cells whereas the conventional ISH method did not. Both methods detected HPV 16 and 18 in CaSki and HeLa 229 cells, respectively. Three clinical cases that were previously negative and two weakly positive cases of HPV infection were all strongly positive with the CARD-ISH system, a 25% increase in the detection of positive cases by CARD-ISH. We also showed for the first time that a cocktail of six biotinylated oligonucleotide probes was capable of detecting one to two copies of HPV 16 in SiHa cells. These results show that the CARD-ISH method increases the sensitivity of nonisotopic ISH to the level of detecting one to two copies of HPV DNA in formalin-fixed, paraffin-embedded tissue sections using biotinylated cDNA or oligonucleotide probes.

3,3'-Diaminobenzidine↗
PubMed1996

Donor lazaroid pretreatment improves viability of livers harvested from non-heart-beating rats.

BACKGROUND: Lazaroids are potent inhibitors of lipid peroxidation. Whether the compounds can benefit the liver procured from non-heart-beating donors (NHBDs) is unknown. METHODS: Donor rats were pretreated with lazaroid U74006F (4.5 mg/kg) 1 hour before cardiac arrest, and transplantation was performed in the rats with donor cardiac arrest from 0 to 60, 100, 120, 140, and 160 minutes as lazaroid pretreated groups. The same number of liver transplantations were done in each paired control group without donor lazaroid pretreatment. Recipient survival rates, bile secretion, serum enzymes, and a lidocaine metabolism test were analyzed. RESULTS: Donor lazaroid pretreatment significantly increased recipient 3-day survival rates in groups with 60, 100, and 120 minutes of warm ischemia and 7-day survival with 60 minutes of warm ischemia. Also, the pretreatment increased bile secretion and reduced serum aspartate aminotransferase and lactate dehydrogenase levels in the lazaroid-pretreated groups. CONCLUSIONS: Donor U74006F pretreatment improves viability of livers procured from NHBDs.

Animals↗
PubMed1995

Study of rat liver transplantation from non-heartbeating cadaver donors.

BACKGROUND: The aim of this study was to determine if livers could tolerate prolonged warm ischemia and to determine optimum timing of intervention in the cadaver donor to preserve liver viability. Livers harvested from non-heartbeating donors (NHBDs) would greatly expand the donor pool for transplantation. However, sensitivity of the donor liver to warm ischemia is a major obstacle for successful use of livers from NHBDs. The limit of non-heartbeating time in the donor remains unknown. STUDY DESIGN: Hepatic transplantation was performed in ten groups of rats with stepwise increase of cardiac arrest time in the donor from zero to 180 minutes with 20-minute intervals. The cardiac arrest time was counted from ligation of the base of the donor's heart to the beginning of cold flushing of the liver. Bile flow, bile acid outputs, hepatic functions, and rat survival rates in each group were compared. RESULTS: Survival rates from groups 1 to 10 were 83.3, 100, 83.3, 50, 66.7, 50, 16.7, 16.7, zero, and zero percent, respectively. The stepwise increase of non-heartbeating time significantly reduced recipient survival rates after 100 minutes. In addition, the increase caused a stepwise decrease of bile flow rates and bile salt outputs and an increase of serum aspartate aminotransferase and lactate dehydrogenase activities. CONCLUSIONS: The liver is less sensitive to warm ischemia than formerly believed. Rat livers can be used for transplantation after cardiac arrest up to 140 minutes with a chance of survival.

Animals↗
PubMed1995

In vivo cholesterol kinetics in apolipoprotein E-deficient and control mice.

The in vivo total body cholesterol transport of homozygous apoE-deficient (-/-) and control (+/+) mice was evaluated by compartmental analysis of plasma cholesterol decay. Body cholesterol fractional catabolic rates of chow fed mutants were less (-/-, 0.17 +/- 0.02; +/+, 0.51 +/- 0.06 day-1) and body cholesterol contents greater (-/-, 68 +/- 5; +/+, 48 +/- 5 mumol) than controls. The body cholesterol expansion of the chow-fed mutant was extracellular with at least half in plasma. Cholesterol transport, i.e., the mass entering, moving through, and exiting the body each day, was similar (-/-, 6.9 +/- 0.7; +/+, 8.5 +/- 0.9 mumol/day) for homozygotes and controls on chow, and both tripled with cholesterol feeding. Differing from controls, however, mutants had considerable expansions of plasma and body cholesterol (-/-, 166 +/- 21; +/+, 59 +/- 11 mumol) with increments in peripheral tissue cholesterol contents. Cholesterol feeding increased control hepatic cholesterol without a change in plasma, whereas mutants had large increments in plasma cholesterol with no change in liver. Consistent with impaired hepatic uptake of cholesterol, mutants had much slower plasma clearance of lipoprotein cholesterol, as well as slower transfer to catabolic pools than normals. Treatment of homozygotes with lovastatin doubled both plasma cholesterol concentration and body cholesterol transport indicating the importance of apoE-dependent cell cholesterol transfer in synthetic down-regulation with this agent. These data indicate that mice lacking apoE have lower affinity hepatic uptake of plasma remnant cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Study of donor-recipient liver size match for transplantation.

OBJECTIVE: This animal experiment investigated the donor-recipient liver size match for safe liver transplantation. BACKGROUND: In spite of refinements in surgical techniques in reduced liver transplantation, the liver size disparity remains one of the most common complications in pediatric patients. Optimal size matching remains unknown. METHODS: The experiment compared eight groups of liver-transplanted rats with designated ratios of donor and recipient liver weights. Donor livers harvested from rats weighing 420-520 g were reduced to the designated size by liver lobectomy and implanted in rats weighing 170-240 g. Bile secretion and serum aspartate aminotransferase (AST) activities in groups 2, 4, and 6 were studied after surgery. RESULTS: Stepwise increase of the ratio of donor and recipient liver weights from 1.04:1 in group 4 to 1.26:1 in group 3, 1.56:1 in group 2, and 2.04:1 in group 1 caused stepwise decrease of survival rates from 83.3% to 66.7%, 16.7%, and 0%, respectively. Stepwise decrease of the ratio from 1.04:1 in group 4 to 0.79:1 in group 5, 0.53:1 in group 6, 0.35:1 in group 7, and 0.24:1 in group 8 also caused stepwise reduction of survival rates from 83.3% to 66.7%, 50%, 0%, and 0% in each group. CONCLUSION: The range of ratios of donor and recipient liver weights for successful rat liver transplantation is from 0.53:1 to 1.26:1. Increase and decrease of ratios of donor-recipient liver weights from equal size do not increase the recipient survival rates. Recipients of reduced donor liver weights tend to have a higher survival rate than recipients of increased donor liver weights.

Animals↗
PubMed1994

Prostaglandin E1 increases survival with extended anhepatic phase during liver transplantation.

OBJECTIVE: The authors investigated the intraoperative treatment effects of Prostaglandin E1 (PGE1) for extension of the anhepatic phase and improvement of survival in a rat liver transplant model. BACKGROUND: Cross-clamping the inferior vena cava and the portal vein during liver transplantation causes severe pathophysiologic changes during surgery. The time of the anhepatic phase is strictly limited and results in a very tenuous period during the liver transplant operation. METHODS: Prostaglandin E1 was infused at 0.5 microgram/kg/min into five subgroups of rats with 20, 30, 40, 60, and 80 minutes of anhepatic phase during transplantation. Bile secretion, serum aspartate transaminase (AST), lactic dehydrogenase (LDH), and blood gas analysis were studied in the 30-minute subgroup. The results were compared with the sham-operated and control groups. RESULTS: Intraoperative treatment with PGE1 extended the maximal anhepatic phase from 30 minutes in the sham-operated group up to 80 minutes, and increased survival. Significant changes in the PGE1 treated rats in the 30-minute subgroup included an increase of bile flow and bile salt output and decrease of AST and LDH activities after surgery. Blood gas analysis showed a decrease in acidosis and hypercarbia at the end of the anhepatic phase. CONCLUSIONS: The PGE1 treatment increased survival with extended anhepatic phase during rat liver transplantation. The beneficial effects can be attributed to its biologic activities.

Alprostadil↗
PubMed1994

Conservative management of spontaneous ruptured hepatocellular carcinoma.

Because most emergent surgical operations for patients with spontaneous ruptured hepatocellular carcinoma (HCC) achieved hemostasis only, a conservative approach was chosen for management of initial bleeding in our institute. Elective surgery was performed in selected patients to attempt resection of the HCC after stabilization of the hemorrhage. From 1971, 68 of 87 patients with ruptured HCC received the conservative treatment, and 19 were treated by emergent surgery during the same period. Overall, one week and one month mortality rates were 26.5 per cent, 48.5 per cent in the conservative group, and 31.6 per cent, 47.4 per cent in the emergent operative group, respectively. Two patients in the emergent operative group underwent partial hepatectomy for a resectability of 10.5 per cent. Fifteen patients in the conservative group received elective laparotomy 1-3 weeks after control of the initial bleeding. Six underwent partial hepatectomy with a resectability of 40.0 per cent. In conclusion, conservative management is an effective approach for control of intraperitoneal hemorrhage in patients with ruptured HCC. Elective surgery on selected patients after hemostasis will increase the cancer resection rate in patients who undergo laparotomy and will give a better life expectancy than emergent laparotomy in patients with ruptured HCC.

Adult↗
PubMed1993

Physiologic study of bile salt and lipid secretion in rats after liver transplantation.

OBJECTIVE: This experiment determined the effects of liver transplantation on bile salt kinetics and biliary lipid secretion. SUMMARY BACKGROUND DATA: Depression of bile secretion in the three main components and bile cholesterol supersaturation with a high incidence of cholesterol stone formation have been documented in patients with end stage liver diseases after transplantation. However, physiologic changes of bile salt and lipid secretion in recipients remain unclear. METHODS: The study was done using a rat liver transplant model with 1 and 6 hours of donor liver cold preservation in saline. A chronic common bile duct fistula and a duodenal cannula were established for bile collection and the sample biochemical study for 6 days. RESULTS: Altered bile salt kinetics in liver grafted rats included depressed bile flow for 1-3 hours after the revascularization, decreased bile salt concentration and outputs, reduced bile salt basal synthesis rate, and reduced bile salt pool size during the early postoperative period. Phospholipid concentration and secretion rate depressed for 1-3 days without altered cholesterol level. The uncoupling change of the cholesterol and the other bile components resulted in an increased lithogenic indices in bile on days 2 and 3. CONCLUSION: Alterations of bile composition and bile salt kinetics occur in liver transplanted rats. The changes may result from injuries of the liver microcirculation and parenchymal cells caused by cold preservation. The study of bile secretion is helpful for evaluation of the initial graft function. The changed ratio of three bile components may be important for cholesterol stone formation in the liver transplant recipient.

Animals↗
PubMed1993

Bile secretion and liver regeneration in partially hepatectomized rats.

OBJECTIVE: The purpose of this research was to study the correlation between bile secretion and the liver regeneration in the partially hepatectomized rat. SUMMARY BACKGROUND DATA: Significant alteration in bile formation and secretion is expected in the liver after hepatectomy. There is scant literature, however, about the effects of liver regeneration in bile secretion. METHODS: The work was done in rats with 50% hepatectomy, 75% hepatectomy, and sham operation as the control. A chronic common bile duct fistula and a duodenal cannula were established for bile collection and the sample analysis on days 1, 3, 5, 7, and 9. RESULTS: With size reduced in the liver after 50% and 75% hepatectomy, the total bile volume decreased 45.9% and 51.5%, bile salt independent flow decreased 59.3% and 64.9%, bile salt secretion rate decreased 36.1% and 43.4%, bile salt basal synthesis rate decreased 52.3% and 56.4%, phospholipid secretion rate decreased 52.6% and 68.0%, and cholesterol secretion rate decreased 54.3% and 72.4% from control on day 1, respectively. All changes returned to the control level in 3 to 9 days with accompanying increasing liver size during regeneration. CONCLUSION: Alterations of total bile flow, bile salt independent flow, bile salt secretion rate, bile salt basal synthesis rate, and biliary lipid secretion after partial hepatectomy correlate with the liver regeneration rate in rats. Partial hepatectomy reduces the bile salt independent fraction calculated as per 100 g body weight rather than the dependent fraction. The study of bile salt and biliary lipid secretion is a useful method for monitoring synthetic function in liver regeneration in vivo.

Animals↗
PubMed1992

Beneficial effects of prewarming the donor liver for rat liver transplantation.

Cold preservation of donor liver can injure the microcirculation enough to impair the function and survival of the transplanted liver. In this study, prewarming the donor liver to 10 degrees C to 12 degrees C after cold storage prior to implantation significantly increased survival rates in rats 1 week after surgery. Following 6, 8, or 9 hours of cold storage in chilled normal saline, prewarming increased survival rates from 40% to 78.6%, from 0% to 35.7%, and from 0% to 14.3%, respectively. The results suggest that pretreatment of the donor liver with warmth following cold storage and before implantation will improve the survival rate of liver transplanted rats.

Animals↗
PubMed1992

A simple method for bile duct anastomosis and interval bile collection in the liver-transplanted rat.

A mini T-tube is introduced for the bile duct anastomosis of rat liver transplantation as well as interval bile collection. The validity of the T-tube was evaluated in 14 liver-transplanted rats and compared to 14 rats using traditional stent for bile duct anastomosis. Changes of biliary tree after the T-tube anastomosis were examined by T-tube cholangiography on sample rats at 4 days and at 4 months after liver grafting. Additionally, bile volumes and rates of bile salt secretion were compared in the continuously flowing cannula and the chronic T-tube fistula in normal rats. The results show that the mini T-tube facilitates bile duct anastomosis and study of bile secretion after liver transplantation in rats without increase in surgical difficulty or interference of biliary enterohepatic circulation.

Anastomosis, Surgical↗
PubMed1991

[Ileostomy--stabilization by stapler technique].

In order to prevent nipple-sliding of the everted small bowel, conventional Brooke ileostomies in 26 patients were stabilized on both sides of the mesentery by longitudinal rows of staples. There were no early complications. With respect to historical controls with unstapled ileostomies, late complications (retraction, prolapse) could be reduced from about 16 to 0% in a median observation time of 2 years. The ileostomies were stable in size and form and therefore appliances were facilitated.

Crohn Disease↗
PubMed1991

Viable but nonculturable bacteria in drinking water.

Klebsiella pneumoniae, Enterobacter aerogenes, Agrobacterium tumefaciens, Streptococcus faecalis, Micrococcus flavus, Bacillus subtilis, and Pseudomonas strains L2 and 719 were tested for the ability to grow and maintain viability in drinking water. Microcosms were employed in the study to monitor growth and survival by plate counts, acridine orange direct counts (AODC), and direct viable counts (DVC). Plate counts dropped below the detection limit within 7 days for all strains except those of Bacillus and Pseudomonas. In all cases, the AODC did not change. The DVC also did not change except that the DVC, on average, were ca. 10-fold lower than the AODC.

Bacteria↗