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S V Lynch

Publications and source records attributed to S V Lynch.

At least 37 records · Page 2Linked to original sources
PubMed2000

Simultaneous quantification of tacrolimus and sirolimus, in human blood, by high-performance liquid chromatography-tandem mass spectrometry.

In this paper the authors present a validated method for the simultaneous analysis of tacrolimus and sirolimus in human blood by high-performance liquid chromatography-electrospray tandem mass spectrometry. Blood samples (500 microL) were prepared by C18 solid-phase extraction. Mass spectrometric detection was by selected reaction monitoring. The assay was linear for both compounds over the range 0.25-100 microg/L (r2 > 0.996, n = 7). At the limit of quantification (0.25 microg/L), for both sirolimus and tacrolimus, the interday imprecision was < 3% and the analytical recovery was between 97.0% and 102%, respectively. The interbatch and intrabatch coefficients of variation of the method for both analytes, at the three quality control concentrations (0.5, 20, and 80 microg/L), were < 16% and < 10%, respectively. The analytical recovery, at the three control concentrations, ranged from 99.2% to 104% of the nominal concentration. The mean absolute recovery (+/- standard deviation) of tacrolimus, sirolimus, and internal standard was 82 +/- 7%, 89 +/- 12%, and 77 +/- 8%, respectively (n = 12). In conclusion, the method presented can be used for simultaneous determination of tacrolimus and sirolimus and will aid in pharmacokinetic studies and therapeutic drug monitoring of these drugs. Furthermore, this method has economic benefits in the clinical setting where these drugs are coadministered.

Chromatography, High Pressure Liquid↗
PubMed1999

Role of donor leukocyte chimerism in establishing the etiology of neutropenia after liver transplantation.

BACKGROUND: The quantitation of donor leukocyte chimerism may aid in establishing the etiology of neutropenia after liver transplantation. METHODS: The incidence and clinical and laboratory characteristics of severe neutropenia were studied in adults who have undergone liver transplantation at our institution over the last 4 years. RESULTS: Severe neutropenia developed in 5 of 156 patients (3%). The clinical and pathological features were nonspecific. In two patients with a delayed diagnosis of graft-versus-host disease (GVHD), donor leukocytes comprised > or = 50% of the circulating peripheral blood mononuclear cells. In a third patient, an earlier diagnosis of GVHD was suspected on the basis of a donor leukocyte count of 3-10% in the peripheral blood. In contrast, donor leukocyte chimerism was < or = 0.01% in two patients with probable drug-induced neutropenia CONCLUSIONS: The determination of donor leukocyte chimerism has an important role in the investigation of neutropenia after liver transplantation, allowing early diagnosis and treatment of GVHD.

Adult↗
PubMed1999

Clinicopathologic findings of recurrent primary sclerosing cholangitis after orthotopic liver transplantation.

Whether primary sclerosing cholangitis (PSC) occurs after orthotopic liver transplantation is controversial, largely because the pre-transplant diagnosis of PSC is based on nonspecific radiological and histological findings. We reviewed clinical, radiological, and histological records of 53 patients who underwent liver transplantation for PSC between 1985 and 1998. Three patients with patent hepatic arteries and no evidence of chronic rejection had radiological and histological findings that may have been due to recurrent PSC. Bile duct stricturing in these patients proved permanent and progressive and affected both the quality of life and graft survival. The first patient, who is 110 months after transplantation, has had repeated episodes of cholangitis for the last year. The second patient underwent excision of a strictured hepatic duct 45 months after transplantation and was ultimately retransplanted 95 months after initial transplantation. The third patient underwent left hemihepatectomy of an atrophied lobe 50 months after transplantation. Although the patient population assessed in this study is limited, putative recurrent PSC in the allografts has led either to graft loss or to clinically significant hepatobiliary complications of the graft.

Adolescent↗
PubMed1999

The effects of circulating interleukin-8 and adhesion molecules on pulmonary dysfunction in pediatric orthotopic liver transplantation.

We investigated the effects of circulating inflammatory cytokines and adhesion molecules induced by ortho-topic liver transplantation (OLT) on pulmonary function. Although the plasma interleukin-8 (IL-8) levels increased gradually, peaking at the end of the operation, these increases were considered minimal. The baseline endothelial adhesion molecule (E-selectin) level was several times higher than the normal value, but after reperfusion of the new transplanted liver, the plasma E-selectin concentrations decreased to within the normal range and remained almost normal during the postoperative period. Similar changes were observed in the plasma levels of other types of adhesion molecules. Although PaO(2)/FIO(2) showed a significant inversed correlation with the peak IL-8 concentration, after the exclusion of two patients, one of whom died and one of whom rejected the transplanted liver, no correlation was able to be found between the PaO(2)/FIO(2) ratio and the maximum IL-8 concentration. Furthermore, there was no correlation between the adhesion moleclues and PaO(2)/FIO(2). These results suggest that IL-8 exerts only a slight effect on respiratory function following successful pediatric liver transplantation, and that circulating adhesion molecules do not affect perioperative lung function.

Adolescent↗
PubMed1999

Liver transplantation in Japanese and Australian/New Zealand children with biliary atresia: a 10-year comparative study.

OBJECTIVE: To compare Japanese with Australian/New Zealand (ANZ) children with biliary atresia who were treated by liver transplantation, and evaluate the indications for and timing of transplantation. DESIGN: Retrospective study. SETTING: Queensland Liver Transplant Service (QLTS), Australia. SUBJECTS: 43 Japanese and 30 ANZ children with biliary atresia who required transplantation between 1985 and 1992. INTERVENTIONS: The 43 Japanese children had 52 transplants, and the 30 ANZ children had 33. MAIN OUTCOME MEASURES: Morbidity, mortality, and long term survival. RESULTS: The Japanese children had significantly lower serum albumin concentrations than the ANZ children preoperatively (mean (SD) 32 (7) g/L compared with 37 (5), p<0.05). The actuarial survival at 7 years of the ANZ children was significantly higher than that of the Japanese children (79% compared with 49%, p<0.05). There were 24 deaths (17 Japanese, 40%, and 7 ANZ, 23%); 2 of the ANZ and 7 of the Japanese children died more than a year after transplantation. All 26 children who were well-nourished at the time of transplantation defined as a Z-score (weight or height minus mean weight or height for age, sex, and race, divided by the SD) of -1 or more were alive at 1 month compared with 11 of the 47 poorly-nourished children (Z-score <-1). Survival among the Japanese declined after 1 year, and there was no association with Z-scores. Overall, Z-scores for weight improved significantly after transplantation, whereas those for height improved a little, but not significantly so. Japanese children were significantly shorter than ANZ children, and their Z-scores for height did not improve after transplantation. CONCLUSION: liver transplantation should be done as soon as possible for children with biliary atresia to maximise survival and growth.

Adolescent↗
PubMed1998

Microscale high-performance liquid chromatography-electrospray tandem mass spectrometry assay for cyclosporin A in blood.

To facilitate quantitative analysis of cyclosporin A in low volume blood samples we developed a sensitive and specific microscale reversed-phase HPLC-electrospray tandem mass spectrometry assay. Blood samples (100 microl) were prepared by acetonitrile precipitation and C18 solid-phase extraction. Detection was by multiple-reactant monitoring. The method was linear over the range 5-1000 microg/l (r> or =0.997) with accuracy between 95.4 and 102.0% over this range. Total imprecision was 11.1% at 10 microg/l and 2.8% at 800 microg/l. Absolute recovery of cyclosporin A and internal standard was 72.5 and 73.3%, respectively. When this method was evaluated against a conventional HPLC with UV detection, in patient samples, they were interchangeable (y=0.988x + 10.0, r=0.996). This HPLC-ESI-MS-MS method will be applicable to therapeutic monitoring in paediatric transplant patients and multiple point pharmacokinetic studies in animals and humans.

Chromatography, High Pressure Liquid↗
PubMed1998

Additional techniques adopted for major vascular anastomoses during orthotopic liver transplantation.

Of 372 patients who underwent liver transplants between January 1985 and March 1995, 7 required variations in vascular anastomoses due to discrepancies in the size-match of the donor and recipient vessels, the presence of a thrombosed hepatic artery or portal vein, or complete absence of the portal vein. The techniques described herein enabled us to perform successful transplantation in all patients. Although rethrombosis of the portal vein developed in one patient after a third transplant, this patient remains clinically well. The use of an operating microscope and the harvesting of an extended length of donor superior mesenteric vein or vascular grafts of the donor iliac or saphenous vessels, for potentially difficult transplants, are invaluable techniques.

Adult↗
PubMed1998

A transient increase in endogeneous erythropoietin levels after paediatric liver transplantation.

We investigated whether liver transplantation affects endogeneous erythropoietin (EPO) synthesis. Serum EPO levels were measured before transplantation and during the peri-transplant period in ten consecutive paediatric patients who had received a liver allograft without recombinant EPO therapy. All patients were anaemic on post-operative day 1 (POD 1); however, the haemoglobin levels of three patients gradually increased and required phlebotomy on POD 5-9. The serum levels of EPO in all patients were within the normal range before surgery, but six of the ten patients had a transient increased level of EPO at 1248 h after transplantation. A transient increase of endogeneous EPO following paediatric liver transplantation may be associated with extramedullary erythropoiesis in human liver grafts.

Child↗
PubMed1998

Anatomic resection for severe liver trauma.

BACKGROUND: Most publications during the past decade have condemned the use of anatomic resection for liver trauma and advocated a conservative surgical approach when operative intervention was required. This policy has been supported by the high mortality rate reported by most authorities. The purpose of this study was to assess the results of anatomic hepatic resection for liver trauma in an institution in which the hepatobiliary surgeons are responsible for the management of severe liver injuries. METHODS: During the period 1983 to 1996, 287 patients with liver injuries were admitted to the hospital and 37 patients with severe liver trauma underwent anatomic resection. Demographic, clinical, operative, and postoperative data were collected and analyzed. The resections performed included right hemihepatectomy (n = 27), left hemihepatectomy (n = 1), left lateral segment resection (n = 5), and segmental resection (n = 4). RESULTS: There were three postoperative deaths after right hemihepatectomy (11.1%) and an overall mortality rate of 8.1%. There were no intraoperative deaths. Postoperative complications occurred in 22 patients (60%) and were most frequent in patients with concomitant injuries to other systems. Liver-related morbidity occurred in seven patients (19%). The median postoperative stay was 20 days. CONCLUSIONS: Anatomic hepatic resection for trauma is associated with low mortality and liver-related morbidity rates when performed by experienced hepatobiliary surgeons, and its role in the management of severe hepatic trauma should be reevaluated.

Female↗
PubMed1998

Evaluation of the tacrolimus II microparticle enzyme immunoassay (MEIA II) in liver and renal transplant recipients.

We evaluated the MEIA II with blood samples with added tacrolimus (3.0, 5.0, 11.0, and 22.0 microg/L). The assay had acceptable recoveries (99-103%) and intraday imprecision (<16.0%) across the range of concentrations studied, except for the recoveries at 3.0 microg/L (86.3%) and 5.0 microg/L (80.7%). Comparison of liver (n = 116) and renal (n = 113) patient samples measured by MEIA II against HPLC-tandem mass spectrometry (HPLC-MS/MS) found a mean overestimation of 15.6%. From these comparison data it can be calculated that at values of 5 and 20 microLg/L in liver or renal transplant patient samples, measured by HPLC-MS/MS, MEIA II will have the corresponding range estimates of 3.6-7.9 microg/L and 20.9-25.4 microg/L, respectively. No clinically significant difference in results, in terms of overestimation or correlation, was observed between the two transplant groups studied. The MEIA II is an improvement on the previous MEIA I and is suitable for the therapeutic drug monitoring of tacrolimus where HPLC-MS/MS is unavailable.

Chromatography, High Pressure Liquid↗
PubMed1997

Peripheral blood chimerism following human liver transplantation.

The aim of this study was to prospectively investigate the peak levels and kinetics of donor leucocyte chimerism in human recipients following liver transplantation. The peak levels of chimerism were observed within the first 48 hours following transplantation and ranged from 0.15% to 20% of total peripheral blood mononuclear cells. In all but one patient, who developed graft versus host disease, there was an early peak level of chimerism that declined over time such that donor leukocytes were only intermittently detectable after 3 to 4 weeks. In 8 patients who had no episodes of graft rejection, the peak level of donor leukocyte chimerism ranged from 1.3% to 20% (mean +/- SEM; 5.5% +/- 2.1%). In 3 patients who were treated for episodes of acute graft rejection during the first four postoperative weeks, the peak level of donor leukocyte chimerism ranged from 0.15% to 0.2% (0.18 +/- 0.02, P = .012). The results demonstrate a marked variation in the total number of donor leukocytes detectable in the peripheral blood early after liver transplantation and also, that lower levels of chimerism may be associated with lower rates of initial graft acceptance and a higher incidence of acute rejection.

Adult↗
PubMed1997

Human liver transplant perfusate: an abundant source of donor liver-associated leukocytes.

In vitro studies designed to examine the mechanisms of immune tolerance after liver transplantation in humans have been hampered by the difficulty in obtaining sufficient numbers of donor liver-associated leukocytes (LALs). We have investigated whether the ex vivo perfusion of donor livers releases a population of LALs that can be readily retrieved from the waste fluid. The mean number of cells recovered after Ficoll-Hypaque density-gradient separation was 2.6 +/- 0.5 x 10(8) cells, with a viability of 94% +/- 2%. The perfusate lymphocytes comprised mainly T cells (39% +/- 2%) with a very low CD4/CD8 ratio and natural killer (NK) cells (56% +/- 6%) with an increase in the proportion of the CD3-CD56+CD16- subset. The activation marker CD69 was present on the majority of the perfusate lymphocytes. These are the phenotypic characteristics that have been previously reported for lymphocytes isolated from hepatic sinusoids. In mixed lymphocyte reactions, the perfusate cells showed a marked increase in the ability to stimulate allogeneic responder cells, resulting in 353% +/- 78% (P = .003) greater incorporation of [3H]thymidine in responder cells when compared with stimulation by donor peripheral blood mononuclear cells. The results show that large numbers of viable donor lymphocytes can be readily isolated from the liver perfusate solution. These cells have the characteristics of liver-associated lymphocytes with a predominance of activated NK and CD8+ T cells. This population can now be used in in vitro assays to elucidate the influence of donor leukocytes on the development of graft acceptance.

Humans↗
PubMed1997

Differences in the rate of donor leucocyte migration between natural and drug-assisted tolerance following rat liver transplantation.

The number involved in and the rate of migration of donor leucocytes into the following recipient organs (spleen, thymus, bone marrow, lung and mesenteric lymph nodes) were measured in two rat models of orthotopic liver transplantation (OLT) using donor-specific MHC class I antibodies. The first OLT model is one that does not require immunosuppression in order to achieve tolerance and involved the transplantation of DA (MHC haplotype, RT1a) livers into PVG (RT1c) recipients. The second model was one that required a 7-day (10 mg/kg) treatment with cyclosporin A (CsA) to achieve tolerance and used DA donors into Lewis (RT1(1)) recipients. Recipient organs were biopsied on days 3, 20 and 87 following OLT and donor leucocyte migration was quantified by immunohistochemistry and computer densitometry of immunoblots of detergent-solublized tissues in order to resolve both membrane-bound and soluble donor MHC class I antigen. In a separate experiment, spleen biopsies were taken following OLT on days 3 and 15 from the naturally tolerizing OLT model (DA into PVG), treated with and without CsA for 7 days and compared with the (DA into Lewis) model. The initial rate of leucocyte migration between days 3 and 21 following OLT was found to be the most rapid into the spleen, followed by the bone marrow and mesenteric lymph nodes in the naturally tolerant (DA into PVG) model when compared with the (DA into Lewis) model. The number of donor leucocytes in the spleen and mesenteric lymph nodes in both models was, however, approximately the same by 87 days. No real difference in the rate of leucocyte migration was seen in the thymus or the lung for both transplant models over the time course assayed. CsA was found to lower the rate of donor leucocyte migration only over the period it was administered. The rate of donor leucocyte migration into the spleen was still much lower 15 days after OLT in the (DA into Lewis) model compared with the (DA into PVG) model treated with and without CsA. Thus the differences in the rate of donor leucocyte migration into the spleen, bone marrow and mesenteric lymph nodes immediately following OLT may offer an explanation as to why the (DA into PVG) combination is able to accept a transplanted liver without immunosuppressive therapy.

Animals↗
PubMed1997

High-performance liquid chromatography-tandem mass spectrometry as a reference for analysis of tacrolimus to assess two immunoassays in patients with liver and renal transplants.

The accuracy and imprecision of three assays used for therapeutic monitoring of tacrolimus were tested using blood-containing weighed-in amounts of the drug, an enzyme-linked immunosorbent assay (ELISA), a microparticle enzyme immunoassay (MEIA I), and a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS2) assay. Accuracy was acceptable for the HPLC-MS2 assay at all concentrations tested (< 10% deviation) and for the ELISA at 1.0 and 4.0 microg/l. Accuracy was not acceptable for the ELISA at 15.0 and 50.0 microg/l or for the MEIA I at all concentrations tested. Imprecision was acceptable for the HPLC-MS2 assay at all concentrations tested (coefficient of variation < 10%), for the ELISA at 15.0 and 50.0 microg/l, and for the MEIA I at 15.0 and 50.0 microg/l. Imprecision was not acceptable for the ELISA at 1.0 and 4.0 microg/l or for the MEIA I at 1.0 and 4.0 microg/l. This assessment with weighed-in amounts of tacrolimus verified the HPLC-MS2 assay as a reference method. The performance of the two immunoassays with HPLC-MS2 was then compared in the clinical setting using blood from patients with liver (n = 30) and renal (n = 37) transplants. In the liver transplant group (127 samples), the range of tacrolimus concentrations measured by HPLC-MS2, ELISA, and MEIA I was 1.9 to 31.8, 2.1 to 35.0, and less than 0.1 to 36.5 mg/l, respectively. In the renal transplant group (129 samples), the ranges were 1.7 to 26.1, 1.9 to 24.4, and 0.9 to 28.5 microg/l, respectively. Compared with the HPLC-MS2, the ELISA had minimal bias (0.1 to 0.2 microg/l) but unacceptable variability in values (SD > 13%). The MEIA I had unacceptable bias (1.7-1.8 microg/l) and variability (SD > 23%). These data indicated that neither the ELISA nor MEIA I is interchangeable with HPLC-MS2. Moreover, in view of the current trend to reduce the therapeutic dose of tacrolimus, quantitative results using the MEIA I would not be obtainable during therapeutic drug monitoring in some patients in whom effective therapeutic concentrations can be less than 5.0 microg/l.

Chromatography, High Pressure Liquid↗
PubMed1997

Potential for bilateral nephrectomy to reduce oxalate release after combined liver and kidney transplantation for primary hyperoxaluria type 1.

Primary hyperoxaluria type 1 (PH-1) is frequently associated with end stage renal failure due to urinary calculi, obstructive uropathy and interstitial deposits of calcium oxalate. The currently accepted treatment for PH-1 is liver transplantation to replace the deficient enzyme peroxisomal alanine glycoxylate aminotransferase (AGT) and a simultaneous renal transplant to restore renal function. The transplanted kidney may become significantly impaired or fail when systemic calcium oxalate is eliminated by renal excretion. The native kidneys are a major source of this oxalate. This study was undertaken to determine whether there is a difference in oxalate clearance following combined liver-kidney transplant in patients with PH-1 by comparing the effect of native kidney nephrectomy at the time of transplantation against leaving the native kidneys in situ. Regression analysis was used to compare daily urinary oxalate excretion corrected for body surface area. There was a significant reduction in urinary oxalate excretion (P < 0.05) in the patient who had undergone bilateral nephrectomy compared to the patient whose native kidneys remained in situ for the first 100 d following combined liver and kidney transplantation. No difference was observed in the serum oxalate levels between patients over the same period or in the renal function assessed by creatinine clearance corrected for body surface area. Total body oxalate load was not determined in this study. A larger study should be undertaken to examine the benefits of nephrectomy in reducing oxalate deposition in recently inserted allografts for patients with PH-1.

Adult↗