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Biomedical subjects

B R Davidson

Publications and source records attributed to B R Davidson.

At least 19 recordsLinked to original sources
PubMed1999

Prolonged lactic acidosis after extended hepatectomy under in situ hypothermic perfusion.

A 46-year-old woman underwent right extended hepatectomy under total vascular occlusion with in situ hypothermic perfusion for colorectal metastasis. Immediately after surgery, she developed severe lactic acidosis, which required correction with sodium bicarbonate solution and ventilatory support for 36 hours. After 2 days, her lactate normalized, and the acidosis was corrected. She made an uneventful recovery. Persistent lactic acidosis after major hepatic resection under in situ hypothermic perfusion is a rare but reversible problem.

Acidosis, Lactic↗
PubMed1999

Prospective randomized trial of end-to-end versus side-to-side biliary reconstruction after orthotopic liver transplantation.

BACKGROUND: Biliary reconstruction is the Achilles heel of liver transplantation. Side-to-side anastomosis of donor and recipient bile duct has been claimed to be superior to end-to-end anastomosis in uncontrolled studies. METHODS: A total of 100 consecutive patients undergoing orthotopic liver transplantation were randomized after commencement of the transplant procedure to end-to-end or side-to-side anastomosis. No T tube drainage was employed. Endoscopic retrograde cholangiography was performed 2 weeks after transplantation and findings were reported by an experienced endoscopist as normal, leak or stricture. Median follow-up was 53 (range 35-63) months. RESULTS: Patient age, sex, the graft preservation time and indication for transplantation were similar in both groups. Sixty patients received end-to-end and 40 side-to-side anastomosis. Ten patients randomized to side-to-side anastomosis had an end-to-end procedure. The total number of biliary complications was similar in both groups (end-to-end 32 per cent versus side-to-side 30 per cent) as were the number of leaks (17 versus 18 per cent) and biliary strictures (15 versus 12 per cent). There was no difference in the number of biliary complications that required interventional treatment (22 per cent in both groups). CONCLUSION: Side-to-side and end-to-end biliary anastomosis at liver transplantation are equally effective.

Adolescent↗
PubMed1999

Hepatic and splanchnic nitric oxide activity in patients with cirrhosis.

BACKGROUND: In animal models of cirrhosis, altered activity of nitric oxide (NO) has been implicated in the pathogenesis of increased intrahepatic portal vascular resistance and abnormal mesenteric vasodilatation. AIMS: To investigate NO activity in the liver and splanchnic vascular bed of patients with cirrhosis. METHODS: Activity of the calcium dependent constitutive and calcium independent inducible isoforms of NO synthase (cNOS and iNOS, respectively) was assayed biochemically in biopsy specimens of liver and a vascular portion of the greater omentum (representative of mesenteric vasculature) obtained from patients with cirrhosis undergoing liver transplantation (n=14) and non-cirrhotic control patients undergoing liver resection for metastases (n=9). The concentration of NO metabolites (NO2 + NO3) in portal and peripheral venous plasma was measured. RESULTS: The activity of cNOS was lower in cirrhotic compared with non-cirrhotic subjects for both liver and omentum. Hepatic and omental iNOS activities did not differ significantly between the two groups. Portal (NO2 + NO3) was threefold higher in cirrhotic than non-cirrhotic patients, but no differences were observed in systemic venous samples from the two groups. CONCLUSIONS: The activity of cNOS is diminished in the cirrhotic human liver. The resultant decrease in constitutive NO release may promote an increase in the intrahepatic portal vascular resistance. Elevated portal venous (NO2 + NO3) indicates enhanced splanchnic vascular release of NO in cirrhotic patients, but the absence of increased NOS activity in the mesenteric vasculature suggests differential regulation of NO synthesis within the splanchnic vascular bed.

Adult↗
PubMed1998

In vivo demonstration of impaired microcirculation in steatotic human liver grafts.

The perfusion of human donor livers was studied during organ retrieval using laser Doppler flowmetry to assess the microcirculatory alteration caused by fatty infiltration (steatosis). Using a multichannel laser Doppler flowmeter, we measured the hepatic perfusion as flux units in 21 liver donors, eight of which were macroscopically fatty. Perfusion was recorded continuously for 2 minutes from two sites on each lobe at the beginning of organ retrieval, after the vascular dissection, and during sequential occlusion of the hepatic artery and portal vein. Mean flux value and SEM were calculated, and paired Student's t test was used for comparison between stages of perfusion. Multiple ANOVA was used to determine whether factors other than the normal or fatty parenchyma influenced the perfusion measurements. Mobilization of the graft did not affect parenchymal perfusion. Perfusion was significantly (P < 0.001) and rapidly reduced with hepatic artery or portal vein occlusion in both groups. Macroscopically steatotic livers (n = 8) had diminished microcirculation compared with normal livers (n = 13) (125 +/- 18 v 252 +/- 24 flux units; P = 0.002). Donors receiving inotropes (n = 10) had a lower mean perfusion rate (150 +/- 20 v 252 +/- 29 flux units; P = 0.026), but this effect was found in both the normal and steatotic groups with no interaction (ANOVA; P = 0.658). Steatosis diminishes the tissue perfusion in human liver grafts. Laser Doppler flowmetry may help identify grafts with a compromised microcirculation.

Adolescent↗
PubMed1998

Multidisciplinary approach to biliary complications of laparoscopic cholecystectomy.

BACKGROUND: Bile leaks and bile duct strictures are major complications of cholecystectomy which increased in incidence after the introduction of laparoscopic surgery. The management and outcome of these complications following the introduction of laparoscopic cholecystectomy was reviewed. METHODS: Eighteen patients of median age 45 (range 22-70) years were treated between January 1992 and December 1995. Six patients had a common hepatic duct (CHD) stricture, four following a failed previous repair. Nine patients had bile leaks from bile duct transection (four), cystic stump (four) or segment V duct (one). Two patients had partial bile duct damage with primary sutured repair at time of cholecystectomy. One patient had recurrent haemobilia from a hepatic artery pseudoaneurysm. RESULTS: Cystic stump or segment V leaks were treated successfully by endoscopic stenting (median follow-up 42 months). Roux loop biliary reconstruction was carried out in nine patients: two CHD strictures, three of the four failed primary CHD repairs and four bile duct transections. All had normal liver function test results at median follow-up of 30 months. The two patients with partial duct injuries repaired at initial surgery required no further intervention. The right hepatic artery aneurysm was successfully embolized. There have been no deaths or major complications of endoscopic, radiological or surgical intervention. CONCLUSION: Endoscopic stenting successfully treats cystic stump and segment V duct leaks. Duct strictures, including failed initial repairs and transections, have a good outcome with Roux-en-Y loop reconstruction.

Adult↗
PubMed1998

In vivo and in vitro hepatic phosphorus-31 magnetic resonance spectroscopy and electron microscopy in chronic ductopenic rejection of human liver allografts.

BACKGROUND: In vivo hepatic phosphorus-31 magnetic resonance spectroscopy (MRS) provides non-invasive information about phospholipid metabolism. AIMS: To delineate MRS abnormalities in patients with chronic ductopenic rejection (CDR) and to characterise spectral changes by in vitro MRS and electron microscopy. PATIENTS AND METHODS: Sixteen liver transplant recipients (four with CDR; 12 with good graft function) and 29 controls (23 healthy volunteers; six patients with biliary duct strictures) were studied with in vivo 31P MRS. Peak area ratios of phosphomonoesters (PME) and phosphodiesters (PDE), relative to nucleotide triphosphates (NTP) were measured. In vitro MRS and electron microscopy were performed on biopsy specimens from five patients with CDR, freeze clamped at retransplantation. Phosphoethanolamine (PE), phosphocholine (PC), glycerophosphorylethanolamine (GPE), and glycerophosphorylcholine (GPC) concentrations were measured. RESULTS: The 12 patients with good graft function displayed no spectral abnormalities in vivo; the four patients with CDR showed significantly elevated PME:NTP (p < 0.01) and PDE:NTP ratios (p < 0.005). Patients with biliary strictures had significant differences in PME:NTP (p < 0.01) from patients with CDR, but not in mean PDE:NTP. In vitro spectra from CDR patients showed elevated PE and PC, mirroring the in vivo changes in PME, but reduced GPE and GPC concentrations were observed, at variance with the in vivo PDE findings. On electron microscopy, there was no proliferation in hepatocyte endoplasmic reticulum. CONCLUSIONS: The increase in PME:NTP reflects altered phospholipid metabolism in patients with CDR, while the increase in PDE:NTP may represent a significant contribution from bile phospholipid.

Adult↗
PubMed1998

Primary squamous carcinoma of liver: presentation as liver abscess.

Primary keratinizing squamous carcinoma of the liver has been reported as arising in a hepatic cyst, in association with prolonged cholestasis or chronic biliary sepsis. We describe the occurrence of such a tumor without predisposing factors, with presentation similar to that of hepatic abscess.

Aged↗
PubMed1997

Changes in adipose tissue composition in malnourished patients before and after liver transplantation: a carbon-13 magnetic resonance spectroscopy and gas-liquid chromatography study.

We investigated adipose tissue fatty acid composition in 22 moderately to severely malnourished patients with cirrhosis and in 22 healthy volunteers by in vivo carbon-13 magnetic resonance spectroscopy (MRS). Gas-liquid chromatography (GLC) of adipose tissue samples was also performed in 11 of the patients and in 4 volunteers. In vivo 13C magnetic resonance spectra were obtained from the subcutaneous adipose tissue before and after eight weeks following orthotopic liver transplantation (OLT). Adipose tissue biopsy samples were obtained for GLC analysis at the time of transplantation in the patients and at inguinal hernia repair in the 4 volunteers. No significant differences were found in the subcutaneous adipose tissue total-saturated, -polyunsaturated or -monounsaturated fatty acid composition between patients and healthy volunteers by in vivo 13C MRS. GLC analysis of adipose tissue samples confirmed that total levels of saturated, poly-, and monounsaturated fatty acids remained the same but revealed significant differences in levels of individual fatty acids, particularly n-3 fatty acids (total n-3, cirrhotics: .84% +/- .07% vs. controls: 1.36% +/- .13%, P < .01). Eight weeks following transplantation, recipients showed a considerable increase in body mass (pretransplantation: 59.3 +/- 3.2 vs. posttransplantation: 63.2 +/- 3 kg, P < .01). 13C MRS revealed a significant increase in saturated fatty acids (pretransplantation: 21.6 +/- 2.8 vs. posttransplantation: 25.5% +/- 1.2%, P < .05) and a significant decrease in unsaturated fatty acids. The application of noninvasive MRS techniques may be important to identify the differential uptake of fats, examining both specific fatty acids and different body fat compartments. In the future, this may be useful in optimizing the dietary management of severely malnourished patients with chronic liver disease before liver transplantation.

Adipose Tissue↗
PubMed1997

Liver transplantation: current and potential applications of magnetic resonance spectroscopy.

Magnetic resonance spectroscopy (MRS) allows the noninvasive measurement of whole organ metabolism due to the presence of the MR-sensitive nucleus phosphorus 31 in adenosine triphosphate (ATP), its precursors, and break-down products. In small animal liver transplant studies it has been used to analyze the metabolic effects of cold and warm ischemia, hypothermic reperfusion, and the relative efficacy of different organ preservation solutions. In recent large animal studies MRS has been developed to provide continuous dynamic information on ATP metabolism during graft reperfusion and the bioenergetic consequences of altering preservation solutions. These basic experimental data need to be critically evaluated in human liver transplantation. Encouraging preliminary data on many possible clinical applications have already been obtained, such as the assessment of human donor liver viability and posttransplant graft function. At present, the cost and technically demanding nature of MRS may restrict its application to research units.

Animals↗
PubMed1997

Assessment of quantitative artificial neural network analysis in a metabolically dynamic ex vivo 31P NMR pig liver study.

Quantitative artificial neural network analysis for 1550 ex vivo 31P nuclear magnetic resonance spectra from hypothermically reperfused pig livers was assessed. These spectra show wide ranges of metabolite concentrations and have been analyzed using metabolite prior knowledge based lineshape fitting analysis which had proved robust in its biochemical interpretation. This finding provided a good opportunity to assess the performance of artificial neural network analysis in a biochemically complex situation. The results showed high correlations (0.865 < or = R < or = 0.992) between the lineshape fitting and artificial neural network analysis for the metabolite values, and the artificial neural network analysis was able to fully represent the trends in the metabolic fluctuations during the experiments.

Animals↗
PubMed1997

Non-invasive assessment of ATP regeneration potential of the preserved donor liver. A 31P MRS study in pig liver.

We have developed a quick, non-invasive method for measuring the ability of an isolated preserved liver to regenerate high energy phosphate nucleotides without the need for biopsy. Using 31P MRS we have monitored the hepatic energetics of intact cold preserved pig liver using standard clinical harvesting and storage techniques. Following cold storage for 2 h the livers were hypothermically reperfused with oxygenated modified University of Wisconsin preservation fluid. Prior to reperfusion MRS detectable adenosine diphosphate plus adenosine triphosphate was negligible; however, the spectrum showed intense resonances from phosphomonoesters and inorganic phosphate, as a consequence of adenosine triphosphate hydrolysis during cold preservation. Following a 10-min period of hypothermic reperfusion, regeneration of adenosine triphosphate occurred with a concurrent decline in inorganic phosphate and phosphomonoester, both of which are associated with adenosine triphosphate synthesis. The capacity of the liver to regenerate adenosine triphosphate following a 24-h period of cold storage was reduced by approximately 40% (p < 0.01) of the total amount achieved following the shorter cold storage time. Adenosine triphosphate regeneration rates were biphasic and were decreased upon prolonged storage, with the initial rate being reduced from 40.6 x 10(-2).min-1 (standard deviation (sd) 2.70 x 10(-2).min-1) to 14.8 x 10(-2).min-1 (sd; 2.4 x 10(-2).min-1) and the secondary rate from 1.77 x 10(-2).min-1 (sd; 0.18 x 10(-2).min-1) to 0.84 x 10(-2).min-1 (sd; 0.45 x 10(-2).min-1). MR images of the liver during the period of hypothermic reperfusion were also performed providing an assessment for the degree of hepatic vascular perfusion. This non-invasive, 31P MRS assessment of hepatic energetics in a clinically relevant animal model has great potential for the understanding of graft preservation injury.

Adenosine Diphosphate↗