Rationale for coronary artery radiation therapy

Within the past decade, focus on radiation to prevent restenosis has moved from a concept developed in the animal laboratory to a clinical treatment. The initial evaluation of coronary artery radiation therapy focused on changes in the function of the artery or lesion formation following overstretch balloon injury in pigs. A number of concepts emerged from this work: (1) radiation inhibits neointima formation in a dose-dependent fashion, (2) radiation prevents negative remodeling, (3) radiation does not reverse established injury, (4) low dose irradiation in an injured area may be injurious, (5) radiation is a useful adjunct to stenting, (6) benefits of radiation in animal models at 6 months are less pronounced than at 1 month, (7) radiation delays healing, (8) permanent stents and radiation delivered from external sources may have very different effects on restenosis, and (9) radiation interferes with vessel wall function. More recent studies of irradiation have looked at the molecular biological effects of radiation in hopes of understanding how this therapy works, and how it may be improved. This article attempts to summarize the known animal and cellular work on radiation in preventing restenosis.

Cytoprotection of pancreatic islets before and early after transplantation using gene therapy

Pancreatic islet transplantation (PIT) is an attractive alternative to insulin-dependent diabetes treatment but is not yet a clinical reality. The first few days after PIT are characterized by substantial pancreatic islet dysfunction and death. Apoptosis has been documented in PI after extracellular matrix removal, during culture time, after exposure to proinflammatory cytokines, hypoxic conditions before islet revascularization, and rejection. Targeting the apoptosis pathway by adenoviral-mediated gene transfer of the anti-apoptotic Bcl-2 gene exerts a major cytoprotective effect on isolated macaque pancreatic islets. Bcl-2 transfection ex vivo protects islets from apoptosis induced by disruption of the islet extracellular matrix during pancreatic digestion. Additionally, over-expression of Bcl-2 confers long-term, stable protection and maintenance of functional islet mass after transplantation into diabetic SCID mice. Genetic modification of PI also reduced the islet mass required to achieve stable euglycemia. Ex vivo gene transfer of anti-apoptotic genes has potential as a therapeutic approach to both minimize loss of functional islet mass post-transplant and reduce the high islet requirement currently needed for successful stable reversal of insulin-dependent diabetes [1, 2].

X-rays modulate extracellular matrix in vivo

X-rays have an antiangiogenic effect in the chicken embryo chorioallantoic membrane (CAM) model of in vivo angiogenesis. Our study demonstrates that X-rays induce an early apoptosis of CAM cells, modulate the synthesis and deposition of extracellular matrix (ECM) proteins involved in regulating angiogenesis and affect angiogenesis induced by tumour cells implanted onto the CAM. Apoptosis was evident within 1-2 hr, but not later than 6 hr after irradiation. Fibronectin, laminin, collagen type I, integrin alpha(v)beta3 and MMP-2 protein amounts were all decreased 6 hr after irradiation. In contrast, collagen type IV, which is restricted to basement membrane, was not affected by irradiation of the CAM. There was a similar decrease of gene expression for fibronectin, laminin, collagen type I and MMP-2, 6 hr after irradiation. The levels of mRNA for integrin alpha(v)beta3 and collagen type IV were unaffected up to 24 hr after irradiation. The decrease in both protein and mRNA levels was reversed at later time points and 48 hr after irradiation, there was a significant increase in the expression of all the genes studied. When C6 glioma tumour cells were implanted on irradiated CAMs, there was a significant increase in the angiogenesis induced by tumour cells, compared to that in non-irradiated CAMs. Therefore, although X-rays have an initial inhibitory effect on angiogenesis, their action on the ECM enhances new vessel formation induced by glioma cells implanted on the tissue.

Laparoscopy-assisted distal gastrectomy for gastric malignant lymphoma

Although the best treatment for gastric malignant lymphoma remains a controversial matter, surgery is the first choice for localized malignant lymphoma without lymph node metastasis and invasion to the adjacent organ. We report a case of gastric malignant lymphoma that was managed with laparoscopy-assisted distal gastrectomy. A 47-year-old man was referred to our department for management of gastric lymphoma. After preoperative examination revealed a tumor confined to the gastric wall but no lymph node metastasis, we performed laparoscopy-assisted Billroth I gastrectomy. Histopathologic examination confirmed that the tumor was follicular center lymphoma limited to the submucosa with no lymph node metastasis. The postoperative course was good. This is the first reported case of laparoscopic gastrectomy-treated gastric malignant lymphoma. Because it involves minimal access and invasiveness, this procedure may be an effective method of treatment of localized malignant lymphoma of the stomach.

Guidelines on antimicrobial chemotherapy for prevention and treatment of infections in the intensive care unit

Severe infections (SIs) in Intensive Care Units (ICUs) constitute difficult therapeutic problems confronting clinicians who deal with severely ill patients. Some SIs are opportunistic infections acquired either in the community or in hospitals, particularly in immunodepressed patients. The great majority of ICU infections are of nosocomial origin. Resistant organisms have led to changing antibiotic therapy in ICU infections. Before microbiology is available, empiric therapy is based on: (i) proper identification of bacterial risks in each infection site; (ii) local surveillance of frequent nosocomial organisms/susceptibility patterns in the ICU; (iii) identification of environmental risk factors and the patient's underlying condition. In documented infection, antibiotic therapy must take into account gram-positive vs gram-negative bacteria or mixed infections, pharmacokinetics/pharmacodynamic parameters of chosen antibiotic(s) and concentrations at the infection site, in order to prevent selection of resistant mutants and to provide the most efficient antibiotic therapy. With increasingly sophisticated intensive care measures, invasive exploratory procedures, and surgical procedures, evolving profiles of hospital infections require updated Guidelines for treatment of severe infections in ICUs. Preventive and therapeutic strategies include control of antibiotic use, and suitable antibacterial treatments which result in shortened hospital stay, improved outcome of hospital infections and significant cost savings.

Suprahepatic venacavaplasty (cavaplasty) with retrohepatic cava extension in liver transplantation: experience with first 115 cases

BACKGROUND

We first introduced the orthotopic liver transplantation utilizing cavaplasty technique in 1994. This paper describes the surgical technique and assesses the outcome of the cavaplasty OLT.

METHODS

The cavaplasty procedure was used in 115 consecutive orthotopic liver transplantations, including six left lateral and two right lobe transplantations, between November 1994 and September 2000. Fifty-three (66.3%) transplantations required femoro-axillary veno-venous bypass in the initial 4 years, whereas only eight (22.9%) needed VB in the subsequent 2 years. Conversion to piggyback or standard technique was not necessary in any patient.

RESULTS

Median results are as follows: operative time 4.5 hr, warm ischemia time 25 min, and blood transfused (packed red blood cells) 6 units. These findings did not differ between first transplantation and retransplantation. There were no perioperative deaths related to the cavaplasty technique. No hepatic venous outflow obstruction was observed, including living-related OLTs. No patient required postoperative hemodialysis for acute renal failure. The median intensive care and hospital stays were 2 days and 10 days, respectively.

CONCLUSIONS

The cavaplasty technique requires no retrocaval, hepatic vein, or short hepatic vein dissection, and the inferior vena cava can be preserved, which provides advantages for hepatectomy and easy hemostasis, especially during retransplantation. The wide-open triangular caval anastomosis is easy to perform, allowing short implantation time and size matching and avoiding outflow obstruction. The short implantation time reduces the need for veno-venous bypass. Our experience indicates that the cavaplasty technique can be applied to all patients and is justified by minimal technical complications.

Vitamin C prevents radiation-induced endothelium-dependent vasomotor dysfunction and de-endothelialization by inhibiting oxidative damage in the rat

1. The present study was undertaken to determine whether endothelial function or morphology was altered in aortic rings of rats after irradiation, to investigate the mechanism of radiation effects on the endothelium and to examine the effect of vitamin C treatment against radiation-induced damage of the endothelium. 2. Female Sprague-Dawley rats were randomized into four groups (control, radiation, radiation + vitamin C, radiation + vitamin C + NG-nitro-L-arginine methyl ester (L-NAME); n = 10 for each group and n = 7 for the control group) and were irradiated with 10 Gy of 137Cs as a radiation source. Segments of the thoracic aorta were obtained and isometric tension, levels of 8-hydroxydeoxyguanosine (OH-dG) and immunohistochemical staining were measured. 3. Irradiation significantly impaired the acetylcholine-induced vasodilation of aortic segments, an effect that could be prevented by pretreatment with vitamin C (500 mg/kg per day). This beneficial effect of vitamin C was abolished by the addition of L-NAME (100 microg/kg per day), an inhibitor of nitric oxide (NO) synthesis. Irradiation significantly increased the level of OH-dG in the aorta (1.02 +/- 0.27 vs 2.61 +/- 0.78 OH-dG/105 deoxyguanosine (dG) for control and irradiated tissues, respectively; P < 0.01), an increase that was prevented by vitamin C treatment (1.59 +/- 0.23 OH-dG/105 dG; P < 0.01). Irradiation caused significant de-endothelialization (von Willebrand factor (vWF) staining was 93 +/- 7 vs 100% in irradiated and control tissues, respectively; P < 0.05) and this was prevented by vitamin C treatment (vWF staining 98 +/- 3%; P < 0.05). 4. Radiation caused endothelial damage and impaired NO production through oxidative injury, resulting in a selective impairment of endothelial-dependent vasodilation that could be prevented by vitamin C, partly through anti-oxidant mechanisms.

Gene transfer of the Bcl-2 gene confers cytoprotection to isolated adult porcine pancreatic islets exposed to xenoreactive antibodies and complement

BACKGROUND

Exposing adult porcine pancreatic islets (PI) to xenoreactive natural antibodies (XNA) induces brisk inflammatory injury that involves activation of the complement system. Gene transfer of Bcl-2 has been shown to protect PI from apoptosis and necrosis in several models. In this study, we investigated the effect of Bcl-2 gene transfer on protection of PI from primate XNA and complement-mediated injury.

METHODS

The PI were isolated from adult female sows. Only islet preparations that exhibited >90% viability and purity were used. Fresh rhesus monkey serum served as the XNA source. Gene transfer of Bcl-2 was achieved with an adenoviral vector (AdBcl-2) at 500 particle forming units (pfu)/cell. The Bcl-2 expression was confirmed by Western blot technique. Untransfected and transfected PI were incubated in 50% fresh complete serum (CS) or heat-inactivated (HI) rhesus serum for 24 hours. The PI viability was analyzed with acridine orange and ethidium bromide staining. Antibody and complement-mediated cytotoxicity were tested by intracellular lactate dehydrogenase (LDH) release. The PI function was assessed in vitro by static incubation studies and in vivo after intraportal transplantation in diabetic severe combined immunodeficiency (SCID) mice.

RESULTS

The AdBcl-2 gene transfer resulted in Bcl-2 gene expression in >90% of PI cells. Following exposure to XNA, <15% of the untransfected cells were viable. Similar results were obtained in PI transfected with a similar recombinant adenovirus encoding the reporter gene E coli beta-galactosidase (AdLacZ), an irrelevant gene. A significant increase in LDH release was observed in control PI after exposure to CS compared with PI that overexpressed Bcl-2 (82.89% +/- 7.78% vs 34.31% +/- 5.4%, P <.005). Higher insulin release was observed in vitro in PI transfected with Bcl-2 compared with untransfected PI or islets transfected with AdLacZ (stimulation index of 0.9 +/- 0.31, 0.9 +/- 0.3 vs 2.67 +/- 0.4, respectively). Only PI treated with AdBcl-2 were able to achieve euglycemia after exposure to XNA and complement after transplantation.

CONCLUSIONS

Transfer of the antiapoptotic and antinecrotic Bcl-2 gene into PI can reduce primate XNA and complement-mediated lysis. Cytoprotection of PI with Bcl-2 has potential to improve survival of PI xenotransplants.

A 10-year experience of liver transplantation for hepatitis C: analysis of factors determining outcome in over 500 patients

OBJECTIVE

To determine the factors affecting the outcome of orthotopic liver transplantation (OLT) for end-stage liver disease caused by hepatitis C virus (HCV) and to identify models that predict patient and graft survival.

SUMMARY BACKGROUND DATA

The national epidemic of HCV infection has become the leading cause of hepatic failure that requires OLT. Rapidly increasing demands for OLT and depleted donor organ pools mandate appropriate selection of patients and donors. Such selection should be guided by a better understanding of the factors that influence the outcome of OLT.

METHODS

The authors conducted a retrospective review of 510 patients who underwent OLT for HCV during the past decade. Seven donor, 10 recipient, and 2 operative variables that may affect outcome were dichotomized at the median for univariate screening. Factors that achieved a probability value less than 0.2 or that were thought to be relevant were entered into a stepdown Cox proportional hazard regression model.

RESULTS

Overall patient and graft survival rates at 1, 5, and 10 years were 84%, 68%, and 60% and 73%, 56%, and 49%, respectively. Overall median time to HCV recurrence was 34 months after transplantation. Neither HCV recurrence nor HCV-positive donor status significantly decreased patient and graft survival rates by Kaplan-Meier analysis. However, use of HCV-positive donors reduced the median time of recurrence to 22.9 months compared with 35.7 months after transplantation of HCV-negative livers. Stratification of patients into five subgroups, based on time of recurrence, revealed that early HCV recurrence was associated with significantly increased rates of patient death and graft loss. Donor, recipient, and operative variables that may affect OLT outcome were analyzed. On univariate analysis, recipient age, serum creatinine, donor length of hospital stay, donor female gender, United Network for Organ Sharing (UNOS) status of recipient, and presence of hepatocellular cancer affected the outcome of OLT. Elevation of pretransplant HCV RNA was associated with an increased risk of graft loss. Of 15 variables considered by multivariate Cox regression analysis, recipient age, UNOS status, donor gender, and log creatinine were simultaneous significant predictors for patient survival. Simultaneously significant factors for graft failure included log creatinine, log alanine transaminase, log aspartate transaminase, UNOS status, donor gender, and warm ischemia time. These variables were therefore entered into prognostic models for patient and graft survival.

CONCLUSION

The earlier the recurrence of HCV, the greater the impact on patient and graft survival. The use of HCV-positive donors may accelerate HCV recurrence, and they should be used judiciously. Patient survival at the time of transplantation is predicted by donor gender, UNOS status, serum creatinine, and recipient age. Graft survival is affected by donor gender, warm ischemia time, and pretransplant patient condition. The authors' current survival prognostic models require further multicenter validation.

Gene transfer of the Bcl-2 gene confers cytoprotection to isolated adult porcine pancreatic islets exposed to xenoreactive antibodies and complement

BACKGROUND

Exposing adult porcine pancreatic islets (PI) to xenoreactive natural antibodies (XNA) induces brisk inflammatory injury that involves activation of the complement system. Gene transfer of Bcl-2 has been shown to protect PI from apoptosis and necrosis in several models. In this study, we investigated the effect of Bcl-2 gene transfer on protection of PI from primate XNA and complement-mediated injury.

METHODS

The PI were isolated from adult female sows. Only islet preparations that exhibited >90% viability and purity were used. Fresh rhesus monkey serum served as the XNA source. Gene transfer of Bcl-2 was achieved with an adenoviral vector (AdBcl-2) at 500 particle forming units (pfu)/cell. The Bcl-2 expression was confirmed by Western blot technique. Untransfected and transfected PI were incubated in 50% fresh complete serum (CS) or heat-inactivated (HI) rhesus serum for 24 hours. The PI viability was analyzed with acridine orange and ethidium bromide staining. Antibody and complement-mediated cytotoxicity were tested by intracellular lactate dehydrogenase (LDH) release. The PI function was assessed in vitro by static incubation studies and in vivo after intraportal transplantation in diabetic severe combined immunodeficiency (SCID) mice.

RESULTS

The AdBcl-2 gene transfer resulted in Bcl-2 gene expression in >90% of PI cells. Following exposure to XNA, <15% of the untransfected cells were viable. Similar results were obtained in PI transfected with a similar recombinant adenovirus encoding the reporter gene E coli beta-galactosidase (AdLacZ), an irrelevant gene. A significant increase in LDH release was observed in control PI after exposure to CS compared with PI that overexpressed Bcl-2 (82.89% +/- 7.78% vs 34.31% +/- 5.4%, P <.005). Higher insulin release was observed in vitro in PI transfected with Bcl-2 compared with untransfected PI or islets transfected with AdLacZ (stimulation index of 0.9 +/- 0.31, 0.9 +/- 0.3 vs 2.67 +/- 0.4, respectively). Only PI treated with AdBcl-2 were able to achieve euglycemia after exposure to XNA and complement after transplantation.

CONCLUSIONS

Transfer of the antiapoptotic and antinecrotic Bcl-2 gene into PI can reduce primate XNA and complement-mediated lysis. Cytoprotection of PI with Bcl-2 has potential to improve survival of PI xenotransplants.

Desmopressin impairs microcirculation in donor pancreas and early graft function after experimental pancreas transplantation

BACKGROUND

Protective effects of desmopressin in brain dead organ donors oppose reports on a hypercoagulatory potential and an increased leukocyte-endothelial interaction (LEI) after application of the drug. The aim was to evaluate the effect of desmopressin on organ donor's pancreas and early graft function.

METHODS

Donor microcirculation was evaluated via intra-vital microscopy (IVM) in 24 BR (di/di) rats with central diabetes insipidus, randomly assigned to groups I (control without desmopressin application), II (single i.v. application, no pretreatment) or group III (single i.v. desmopressin application, s.c. pretreatment for 3 days). Microcirculation in recipients was evaluated 1 hr and 6 hr after syngenic pancreas transplantation. Groups III and I served as organ donors. After IVM specimens were taken for histology and immunohistochemistry.

RESULTS

Desmopressin in II vs. I led to temporarily (30') increased LEI (Sticker 274.3+/-87.7 vs. 76.5+/-31.1/mm2 endothelial surface; P<0.01) and impaired microcirculation (MCEV 0.43+/-0.07 vs. 0.99+/-0.06 mm/s; P<0.01). Repeated application reduced MCEV and increased LEI for up to 12 hr. Histology in I vs. III showed increased inflammation (n.s.), necrosis (P<0.05) and vacuolization (P<0.01). Immunohistochemistry revealed increased endothelial P-selectin 20' after application. 6 hr after reperfusion organs from III showed reduced MCEV and increased LEI (P<0.01).

CONCLUSION

Repeated application of desmopressin impairs graft microcirculation. Perfusion of the pancreas is significantly reduced at the beginning of organ tissue conservation as well as after reperfusion. These disturbances might partly be due to observed endothelial P-selectin expression. Application of desmopressin up to 12 hr prior to organ explantation may impact graft quality.

The effect of ionizing irradiation on vasomotor reactivity in the rat thoracic aorta in vitro

PURPOSE

Ionizing irradiation inhibits restenosis in animal models and human. Vasomotor tone preservation during and after radiation therapy is of clinical importance. We therefore investigated vascular reactivity following radiation therapy.

METHODS AND MATERIALS

Wistar Sabra rats were treated with a single dose of 1000 cGy external X-ray irradiation. Vascular reactivity of 192 segments of rat thoracic aorta was studied in vitro in four groups (12 rats in each group, four segments from each aorta). Immediately after in vivo irradiation, immediately after ex vivo irradiation, 1 month after irradiation, and no irradiation (control).

RESULTS

Vasoconstriction to phenylephrine (PE) 10(-9)-10(-5) M or KCl 118.0 mM in all the irradiated groups was similar to controls. Endothelium-dependent vasorelaxation to acetylcholine (ACh) 10(-9)-10(-5) M in segments studied immediately after in vivo irradiation was increased compared to controls at all concentrations (109.7+/-35. and 90.0+/-40.0%, respectively, at 10(-5) M, P=.006). Endothelium-independent relaxation to nitroglycerin 10(-9)-10(-5) M in all irradiated groups was similar to controls.

CONCLUSIONS

External-ionizing irradiation with 1000 cGy in the rat aortic model induces acute and transient increase in endothelium-dependent relaxation to ACh, and does not alter vasoconstriction and endothelium-independent relaxation.

The impact of donor age on liver transplantation: influence of donor age on early liver function and on subsequent patient and graft survival

BACKGROUND

The urgent need to increase the organ donor pool has led to the expansion of criteria for donor selection. The aim of this study was to analyze the influence of donor age on early graft function, subsequent graft loss, and mortality after liver transplantation (LT).

METHODS

Data on LT were evaluated retrospectively in a population-based cohort of 400 LTs in 348 patients. Of these, 21 (5%) were from donors >70 years old. Pretransplantation donor and recipient characteristics and the evolution of recipients were analyzed. The influence of donor age as a risk factor was assessed using univariate and multivariate analyses.

RESULTS

Actuarial graft survival was 89% at 1 month after LT, 81% after 6 months, and 59% after 60 months. Multivariate analysis demonstrated that only donor age (>70 years old) was associated with a higher risk of long-term graft loss (relative risk [RR]=1.4, 95% confidence interval [CI]=1-1.9; P=0.03) and mortality (RR=1.7, 95% CI=1.2-2.3; P=0.01). Graft survival of septuagenarian livers was 80% at 1 month after LT, 56% after 6 months, and 25% after 54 months. Actuarial survival analysis (Kaplan-Meier curves) also demonstrated worse evolution in recipients of livers from old donors (log-rank test, P<0.001).

CONCLUSIONS

Advanced donor age is associated with lower graft and recipient survival.

Effects of radiation therapy on vascular responsiveness

The use of radiation therapy to inhibit vascular proliferative diseases has produced encouraging results in several clinical trials. However, little is known about the possible side effects of radiation on vascular responsiveness. Our goal was to study the in vitro vascular responses of the rabbit aorta to various agonists immediately after several regimens of radiation therapy administered at doses prescribed in clinical protocols and at two different dose rates. High-dose-rate radiation was administered either by brachytherapy, using a gamma source, iridium 192, or an external electron beam producing beta radiation. Low-dose-rate radiation was administered by brachytherapy using a liquid-filled balloon with the beta emitter 32P. Vascular reactivity after the various regimens of irradiation was determined using the organ bath pharmacology assay. Various agonists were applied to the rabbit aorta to produce full cumulative concentration-response curves. Radiation, administered using an external electron beam, did not alter endothelium-dependent relaxation of the aorta induced by acetylcholine. However, the use of a catheter-based system to deliver radiation disrupted the endothelial cell lining of the vessel, causing a lack of relaxation by acetylcholine. Therefore, to compare all modalities of radiation therapy on vascular responsiveness, the agonists used in this study are known to act directly on the smooth muscle. Radiation therapy had no effect on the contractile responses induced by the following agonists: phenylephrine and potassium chloride. Vascular dilatation induced by nitroglycerin, a nitric oxide donor, was unaffected by radiation therapy. The contractile response induced by des-Arg9-bradykinin, a kinin B1 receptor agonist, was significantly increased twofold to threefold by all types of irradiation under study. This enhanced response is attributable to an increase of mRNA levels coding for this receptor. In all cases, radiation therapy did not alter the effective concentration producing 50% of maximal responsiveness (EC50) and did not reduce the vascular responsiveness induced by agonists. Taken together, we conclude that radiation therapy does not hinder endothelium-independent vascular responsiveness and increases the kinin B1 receptor-mediated vasoconstriction.

Immediate neurocognitive effects of methylphenidate on learning-impaired survivors of childhood cancer

PURPOSE

To test if methylphenidate (MPH) has an objective beneficial effect on immediate performance on tests of neurocognitive functions among learning-impaired survivors of childhood acute lymphoblastic leukemia (ALL) and malignant brain tumors (BT).

PATIENTS AND METHODS

From July 1, 1997 through December 31, 1998, 104 long-term survivors of childhood ALL or a malignant BT completed neurocognitive screening for learning impairments and concurrent problems with sustained attention. Eligibility criteria for the MPH trial included an estimated intelligence quotient greater than 50, academic achievement in the 16(th) percentile or lower for age in reading, math, or spelling, and an ability to sustain attention on a computerized version of the Conners' Continuous Performance Test (CPT) in the 16(th) percentile or lower for age and sex. Of the 104, 32 (BT, n = 25; ALL, n = 7) were eligible on the basis of these a priori criteria for a randomized, double-blinded, placebo-controlled trial of MPH. The patients ingested a placebo (lactose) or MPH (0.6 mg/kg; 20 mg maximum) and repeated selected portions of the screening battery 90 minutes later.

RESULTS

Compared to the 17 patients randomized to the placebo group, the 15 patients randomized to the MPH group had a significantly greater improvement on the CPT for sustained attention (errors of omission, P =.015) and overall index (P =.008) but not for errors of commission (indicative of impulsiveness) nor reaction times. A trend for greater improvement in the MPH group on a measure of verbal memory failed to reach statistical significance. No trend was observed for MPH effectiveness in improving learning of a word association task. No significant side effects from MPH were observed.

CONCLUSION

MPH resulted in a statistically significant improvement on measures of attention abilities that cannot be explained by placebo or practice effects.

Human islet cell transplantation--future prospects

BACKGROUND

Islet transplantation has the potential to cure diabetes mellitus. Nevertheless despite successful reversal of diabetes in many small animal models, the clinical situation has been far more challenging. The aim of this review is to discuss why insulin-independence after islet allotransplantation has been so difficult to achieve.

METHODS

A literature review was undertaken using Medline from 1975 to July 2000. Results reported to the International Islet Transplant Registry (ITR) up to December 1998 were also analysed.

RESULTS

Up to December 1998, 405 islet allotransplants have been reported the ITR. Of those accurately documented between 1990 and 1998 (n = 267) only 12% have achieved insulin-independence (greater than 7 days). However with refined peri-transplant protocols insulin independence at 1 year can reach 20%.

CONCLUSIONS

There are many factors which can explain the failure of achieving insulin-independence after islet allotransplantation. These include the use of diabetogenic immunosuppressive agents to abrogate both islet allo-immunity and auto-immunity, the critical islet mass to achieve insulin-independence and the detrimental effects of transplanting islets in an ectopic site. However recent evidence most notably from the Edmonton group demonstrates that islet allotransplantation still has great potential to become an established treatment option for diabetic patients.

Prevention of early islet graft failure by selective inducible nitric oxide synthase inhibitors after pig to nude rat intraportal islet transplantation

BACKGROUND

Clinical and experimental data indicate that early failure of intraportally grafted islets is caused by inflammation including secretion of cytokines and nitric oxide. Direct inducible nitric oxide synthase suppression may avoid detrimental effects associated with steroid administration. We compared the efficiency of selective and unselective inducible nitric oxide synthase inhibitors with dexamethasone to suppress nitric oxide generation after intraportal islet xenotransplantation into nude rats.

METHODS

Nonfasting serum glucose levels were daily evaluated after intraportal transplantation of 4000 freshly isolated pig islets into diabetic nude rats (85 mg/kg streptozotocin) either sham-treated with saline (n=21) or continuously infused for 7 days with L-NG-monomethyl-arginine (n=7), S-methyl-isothiourea (n=15), or S-(2-aminoethyl)-isothiourea (n=19) in a dosage of 240, 100, or 50 mg/kg/day, respectively. Dexamethasone was injected i.p. twice as a daily bolus of 20 mg/kg (n=10) starting 1 day pretransplant. The nitrate/nitrite serum level was quantified colorimetrically 0, 24, and 48 hr posttransplant.

RESULTS

Saline treatment partially resulted in graft function (4/21) throughout the observation period (21 days). L-NG-monomethyl-arginine-treated rats showed sustained hyperglycemia (0/7) not different from diabetic controls. Normoglycemia was observed after treatment with dexamethasone (6/10, P<0.05 versus saline and L-NG-monomethyl-arginine), S-methyl-isothiourea (10/15, P<0.01), or S-(2-aminoethyl)-isothiourea (15/19, P<0.001). Graft function was associated with complete suppression of nitric oxide generation after S-methyl-isothiourea and S-(2-aminoethyl)-isothiourea treatment (P<0.001 versus saline) and partial suppression after dexamethasone treatment (P<0.05).

CONCLUSIONS

Our observation of long-term function of xenogeneic islets in an inflammatory environment without interference of reactive T cells revealed the potency of highly selective isothioureas to completely suppress inducible nitric oxide synthase making reduction of islet-toxic immunosuppression feasible.

Predictors of survival after In vivo split liver transplantation: analysis of 110 consecutive patients

OBJECTIVE

To determine the factors that influence patient survival after in vivo split liver transplantation (SLT).

SUMMARY BACKGROUND DATA

Split liver transplantation is effective in expanding the donor pool, and its use reduces the number of deaths in patients awaiting orthotopic liver transplantation. Early SLTs were associated with poor outcomes, and acceptance of the technique has been slow. A better understanding of the factors that influence patient and graft survival would be useful in widening the application of SLT.

METHODS

During a 3.5-year period, 55 right and 55 left lateral in vivo split grafts were transplanted in 102 pediatric and adult recipients. The authors' in vivo split technique has been previously described. Median follow-up was 14.5 months. Recipient, donor, and surgical variables were analyzed for their effect on patient survival after SLT.

RESULTS

Overall survival rates of patients who received an SLT were not significantly different from those of patients who received whole organ transplants. Survival of left lateral segment recipients, at median follow-up time, was 76% versus 80% in patients receiving a trisegment. Fifty of 102 patients (49%) were high-risk urgent recipients (United Network for Organ Sharing [UNOS] status 1 and 2A) and 52 (51%) were nonurgent recipients (UNOS status 2B, 3). High-risk recipients had a survival rate significantly lower than that of nonurgent recipients. By univariate comparison, two variables-UNOS status and number of transplants per patient-were significantly associated with an increased risk of death. Preoperative recipient mechanical ventilation, preoperative prothrombin time, donor sodium level, donor length of hospital stay, and warm ischemia time approached significance. The type of graft (right vs. left) did not reduce the survival rate after transplantation. Multivariate logistic regression analysis identified UNOS status and length of donor hospital stay as independent predictors of survival.

CONCLUSIONS

Patient survival of in vivo SLT is not significantly different from that of whole-organ orthotopic liver transplantation. The variables affecting outcome of in vivo SLT are similar to those in whole-organ transplantation. in vivo SLT should be widely applied to expand a severely depleted donor pool.

Piggyback technique and selective use of veno-venous bypass in adult orthotopic liver transplantation

BACKGROUND

The piggyback technique (PT), with preservation of the cava, is being used more frequently in adult orthotopic liver transplantation (OLT). The advantages of PT include hemodynamic stability during the anhepatic phase without a large-volume fluid infusion and obviating the need for veno-venous bypass (VVB). At our center, we changed our practice in July 1997 from the standard technique (ST) of OLT with routine use of VVB to PT and selective use of VVB. The purpose of the present study was to analyze the results with the two different practices, ST-routine VVB versus PT-selective VVB.

METHODS

Forty OLTs were performed during the period July 1995 July 1997 using ST-routine VVB (group I) and 36 during August 1997-December 1998 using PT-selective VVB (group II). The etiology of liver disease was similar in the two groups, with hepatitis C and alcoholic liver disease accounting for half of the patients in each group. The UNOS status, age, sex, and percentage of patients with previous upper abdominal surgery were also similar between the two groups.

RESULTS

In the PT-selective VVB era (group II), 34/36 patients (94%) underwent OLT with PT and VVB was used for 8 (22%) patients. The decision to use VVB was elective for 3 patients (fulminant hepatic failure, 2; severe portal hypertension, 1) and urgent for 5 patients (hemodynamic instability during hepatectomy). The intraoperative use of packed red blood cells (PRBC) (mean +/- SD) was 15+/-12 units for group I and 9+/-8 units for group II (p = 0.023). Anastomosis time and total operating time (mean +/- SD) were 91 + 30 min and 9.5+/-3.2 h, respectively, for group I patients compared with 52+/-28 min and 7.6+/-1.6 h, respectively, for group II patients (p<0.0001 and 0.002, respectively). Median post-operative stays in the intensive care unit (ICU) and in the hospital were 5 and 17 d, respectively, for group I and 4 and 11 d, respectively, for group II (p = NS). Mean serum creatinine on day 3 was similar in the two groups. Median hospital charges for group I patients were $105439 compared with $91779 for group II patients (p = NS). The 1-year actuarial graft and patient survival rates were 78% and 82%, respectively, for group I, and 92% and 95%, respectively, for group II.

CONCLUSIONS

PT is safe and can be performed in the majority of adult patients (>90%) undergoing OLT. With the routine application of the piggyback procedure, the use of VVB has been reduced to 20% of OLTs at our center. The practice of piggyback technique with the selective use of VVB is associated with shorter anhepatic phase and total operating time, lower blood product use, a trend towards shorter hospital length of stay, and reduced hospital charges compared with standard technique of OLT with routine use of VVB.

Reoperation for secondary uremic hyperparathyroidism: are technical difficulties influenced by initial surgical procedure?

BACKGROUND

Parathyroid surgery in patients with uremia and secondary hyperparathyroidism is performed either by subtotal parathyroidectomy or total parathyroidectomy with immediate reimplantation. The aim of this study was to compare the results of reoperation for persistent or recurrent hyperparathyroidism after parathyroidectomy according to which initial operative procedure was used.

PATIENTS AND METHODS

Eighty-nine patients had reoperation for persistent (28 patients) or recurrent (61 patients) hyperparathyroidism after 53 subtotal parathyroidectomies and 36 total parathyroidectomies with immediate reimplantation. Results of the reoperation were assessed in terms of success rate, morbidity, and operative findings.

RESULTS

The success rate of reoperation in patients with persistent hyperparathyroidism was 89% and was independent of the initial type of surgery. Success rates of reoperation for recurrent hyperparathyroidism after initial subtotal parathyroidectomy and total parathyroidectomy with immediate reimplantation were 87% and 70%, respectively (P = .02). Hypertrophy of the parathyroid remnant was the main cause of recurrence after subtotal parathyroidectomy. After total parathyroidectomy with immediate reimplantation, recurrence was located in the graft in half the patients, while hyperplastic tissue was found in the neck or the mediastinum in the other half.

CONCLUSIONS

Subtotal parathyroidectomy provides the best conditions for successful reoperation in case of recurrent hyperparathyroidism and should become the surgical treatment of choice for secondary hyperparathyroidism.

Influence of postangioplasty beta-irradiation on endothelial function in porcine coronary arteries

BACKGROUND

Postangioplasty (PTCA) intracoronary radiation therapy (ICRT) has been demonstrated to limit restenosis. The consequences of these procedures on coronary reactivity are unknown.

METHODS AND RESULTS

Porcine coronary arteries were studied after PTCA immediately (n=5) and 6 weeks (n=5) after ICRT (n=5 and 5, respectively), after combined PTCA+ICRT (n=5 and 7, respectively), and after no intervention (n=11). A 3-cm-long source train of Sr/Y(90) was used in vivo to deliver 16 Gy at a depth of 2 mm from the source center, as used in clinical trials. Arterial rings were mounted on myographs to record isometric tension. After achieving steady-state contraction to depolarizing physiological solution containing 40 mmol/L KCl, measured baseline tension was significantly elevated immediately after all interventions. It returned to normal levels 6 weeks after PTCA and ICRT alone but was significantly reduced if combined. Active contractions induced by 40 mmol/L KCl were maintained after combined therapy both immediately after and at 6 weeks. In these depolarizing conditions, nitric oxide-dependent relaxation to substance P was trivial after PTCA+ICRT and reduced after ICRT, whereas in the presence of physiological solution and N(omega)-nitro-L-arginine, substance P-induced relaxation was reduced after PTCA and abolished after PTCA+ICRT 6 weeks after intervention. In rings without endothelium, the relaxation mediated by sodium nitroprusside (0.1 micromol/L) was reduced immediately after PTCA and at 6 weeks.

CONCLUSIONS

PTCA+ICRT altered the passive mechanical properties of porcine coronary arterial wall. Furthermore, at 6 weeks, receptor-operated release of endothelium-derived nitric oxide and endothelium-derived hyperpolarizing factor was reduced by ICRT and PTCA alone, respectively, and was prevented by their combination.

Ascites due to anastomotic stenosis after liver transplantation using the piggyback technique: treatment with endovascular prosthesis

Liver transplantation preserving the retrohepatic inferior vena cava, the so-called piggyback technique, is becoming more frequently used because it avoids caval cross-clamping during the anhepatic phase of surgery. However, hepatic venous outflow blockade causing ascites seems to be less infrequent after piggyback than with cavo-caval anastomosis. We report a 62-year-old patient who underwent liver transplantation using the piggyback technique and developed a stenosis in the anastomosis between the hepatic veins and the inferior vena cava leading to severe postoperative ascites. Ascites was unresponsive to diuretic therapy and was associated with renal function impairment. Since the etiology of the stenosis was mechanical (torsion), percutaneous transluminal angioplasty was unsuccessful. Finally, an autoexpandable prosthesis was placed across the anastomosis resulting in rapid and permanent (3 years of follow-up) resolution of ascites.

Different time course of circulating adhesion molecules and hyaluran during hepatic allograft rejection

BACKGROUND

Inducible adhesion molecules are involved in cell-mediated allograft rejection. In addition, the endothelium is the main target of this process. This study investigated, whether soluble (s) forms of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) are elevated during cellular rejection and whether hyaluran is a useful marker of endothelial function in liver transplantation.

METHODS

Serum levels of sICAM-1, sVCAM-1, and hyaluran were determined in 24 controls and 27 hepatic transplant recipients. These patients were divided in two groups: group I, 14 patients without rejection; and group II, 13 patients with rejection. Samples were collected on day 1 and 7 after transplantation, on the day of liver biopsy, and after treatment of the rejection.

RESULTS

We found a significant increase in sICAM-1 levels in the postoperative period in the rejection group compared with the non rejection group. It persisted significantly elevated until the diagnosis of rejection was made. In contrast, sVCAM-1 was only significantly elevated in the rejection group when diagnosis of rejection was evident. Hyaluran levels were also significantly elevated in the rejection group at diagnosis of rejection. We noticed a significant decline in sICAM-1, sVCAM-1, and hyaluran levels after successful treatment of rejection. In addition, we observed in the non-rejection group a stable lower levels of hyaluran during the entire postoperative period.

CONCLUSIONS

The release of circulating adhesion molecules is a prominent feature coinciding with the first episode of hepatic rejection. Differential patterns of sICAM-1 and sVCAM-1 exist during rejection. In addition, hyaluran levels may be a sensitive marker of liver endothelial cell function in the postoperative period of liver transplantation.

Subcutaneous forearm transplantation of autologous parathyroid tissue in patients with renal hyperparathyroidism

BACKGROUND

Parathyroidectomy is required in up to 5% of patients with chronic renal failure. Intramuscular transplantation of autologous parathyroid tissue in the forearm has been the traditional method of transplantation at the time of total parathyroidectomy. The removal of an intramuscular transplantation can be technically difficult should graft-dependent hyperparathyroidism (GRH) occur. This problem resulted in our initiating a study of subcutaneous transplantation with total parathyroidectomy in patients with renal failure.

METHODS

Twenty-six patients who were receiving dialysis therapy underwent total parathyroidectomy and subcutaneous transplantation. Parathyroid tissue was diced into 1- to 2-mm pieces, and 6 pieces were grafted into 6 subcutaneous pockets of the forearm. Intact parathyroid hormone was measured within 48 hours of operation and in the bilateral antecubital veins 1 to 24 months after the operation to assess completeness of resection and graft function, respectively.

RESULTS

No major surgical complications occurred. Symptoms improved in 24 patients (85%). Graft failure rate was 4.3%. No GRH was observed. Follow-up was 4 to 55 months (mean, 27 months).

CONCLUSIONS

This study indicates that the subcutaneous transplantation function is comparable to intramuscular transplantation and suggests a decreased incidence of GRH. Subcutaneous transplantation is technically easier than intramuscular transplantation and has the additional advantage of easy removal should GRH occur.

Adrenomedullin in liver transplantation and its relationship with vascular complications

Adrenomedullin (AM) is a potent vasodilating peptide that increases rat platelet cyclic adenosine monophosphate levels and acts on endothelial cells to stimulate nitric oxide release. Both mechanisms inhibit platelet function. Considering these effects, AM may have a role in cardiovascular regulation after orthotopic liver transplantation (OLT) and could have an antithrombotic effect. The aim of the present study is to investigate plasma AM levels in the early postoperative period after OLT and their relationship with vascular complications in OLT. We measured plasma AM levels in 35 patients with cirrhosis who underwent OLT at baseline and 1, 7, and 15 days postoperatively. We found that AM levels were significantly greater in patients with cirrhosis compared with healthy subjects. Of the 35 patients, 10 had vascular complications. In these 10 patients, AM concentrations were significantly greater than those observed in the nonthrombotic group in the early postoperative period. In addition, we also noticed in the nonthrombotic group a significant increase in AM levels from baseline to day 1, then a decrease to baseline levels in the early postoperative period. Our study shows that AM might act as a new humoral factor involved in the response to surgery in OLT and is significantly associated with vascular thrombosis in OLT.

Influence of high donor serum sodium levels on early postoperative graft function in human liver transplantation: effect of correction of donor hypernatremia

Donor hypernatremia was reported to cause postoperative graft dysfunction in human orthotopic liver transplantation (OLT). However, the effects of the correction of donor hypernatremia before organ procurement have not been confirmed. The aim of this study is to determine whether donor hypernatremia is associated with early graft dysfunction after OLT and to determine the effect of the correction of donor hypernatremia. One hundred eighty-one consecutive OLTs performed between May 1997 and July 1998 were entered onto this study. The cases were divided into three groups according to the donor serum sodium concentration: group A, serum sodium of 155 mEq/L or less before organ procurement (n = 118); group B, peak sodium greater than 155 mEq/L and final sodium 155 mEq/L or less (n = 36); and group C, final sodium greater than 155 mEq/L (n = 27). Graft survival within 90 days after OLT and early postoperative graft function were analyzed. There were no significant differences in donor and recipient variables among the three groups. The frequencies of graft loss were 15 of 118 grafts (12.7%) in group A, 4 of 36 grafts (11.1%) in group B, and 9 of 27 grafts (33.3%; P <.05 v groups A and B) in group C. The liver enzyme values in groups B and C were significantly greater than those in group A postoperatively. The prothrombin times of group C were significantly longer than those of group A for the first 4 postoperative days. Recipients of hepatic allografts from donors with uncorrected hypernatremia had a significantly greater incidence of graft loss compared with recipients of hepatic allografts from normonatremic donors. However, the differences in graft survival were abrogated by the correction of donor hypernatremia before procurement.

Analysis of the complications of the piggy-back technique in 1,112 liver transplants

BACKGROUND

The "piggy-back" technique has gained acceptance in adult orthotopic liver transplantation during the last few years, especially in European countries. At the moment, however, there is controversy over advantages or specific complications (suprahepatic thrombosis or narrowing, etc.) related to this surgical technique. The aim of this study is to know of the immediate per-and postoperative morbidity and mortality rates in 1112 orthotopic liver transplantations performed with a vena cava preservation technique.

METHODS

All liver transplant units in Spain were sent a questionnaire on retrohepatic vena cava preservation during orthotopic liver transplantation. The number of orthotopic liver transplantations that had been performed in the seven centers that answered the questionnaire, because the beginning of the program, was 1674, with the vena cava preservation technique used in 1112.

RESULTS

Twenty-eight patients (2.5%) had intraoperative complications related to the vena cava preservation technique, which were treated during the operation. Eleven patients (1%) had early postoperative complications (first week), the most frequent (nine cases) being an acute Budd-Chiari syndrome in the first 48 hr. Three patients developed symptoms of massive ascites between 2 and 3 months (late postoperative complications), with patency of the retrohepatic cava verified by cavography. A hemodynamic study revealed a hyperpressure at the suprahepatic veins. This chronic Budd-Chiari syndrome was controlled in all patients with diuretics. Only six patients (0.5%) died as a result of complications related to the "piggy-back" technique. These complications were more frequent when venous reconstruction was done using two suprahepatic veins than when the three veins were used (P<0.001).

CONCLUSIONS

The vena cava preservation technique can be used routinely in orthotopic liver transplantation because it is safe and efficient and involves few surgical complications especially if for venous reconstruction we use the patch obtained by joining the three suprahepatic veins.

Clinical islet cell transplantation. Are we there yet?

Diabetes mellitus is perhaps the most devastating chronic disease of all time. A brief history of the evolution of treatment modalities is provided, culminating in the rationale for the physiologic replacement of a functioning beta-cell mass by transplantation. Vascularized pancreas transplantation is discussed briefly as an introduction to the transplantation of the isolated islet. A detailed review of the current state of human islet transplantation for the cure of diabetes is then described. Finally, areas for future development are highlighted.

Early allograft dysfunction after liver transplantation: a definition and predictors of outcome. National Institute of Diabetes and Digestive and Kidney Diseases Liver Transplantation Database

BACKGROUND

Poor graft function early after liver transplantation is an important cause of morbidity and mortality. We defined early allograft dysfunction (EAD) using readily available indices of function and identified donor, graft, and pretransplant recipient factors associated with this outcome.

METHODS

This study examined 710 adult recipients of a first, single-organ liver transplantation for non-fulminant liver disease at three United States centers. EAD was defined by the presence of at least one of the following between 2 and 7 days after liver transplantation: serum bilirubin >10 mg/dl, prothrombin time (PT) > or =17 sec, and hepatic encephalopathy.

RESULTS

EAD incidence was 23%. Median intensive care unit (ICU) and hospital stays were longer for recipients with EAD than those without (4 days vs. 3 days, P = 0.0001; 24 vs. 15 days, P = 0.0001, respectively). Three-year recipient and graft survival were worse in those with EAD than in those without (68% vs. 83%, P = .0001; 61% vs. 79%, P = 0.0001). A logistic regression model combining donor, graft, and recipient factors predicted EAD better than models examining these factors in isolation. Pretransplant recipient elevations in PT and bilirubin, awaiting a graft in hospital or ICU, donor age > or =50 years, donor hospital stay >3 days, preprocurement acidosis, and cold ischemia time > or =15 hr were independently associated with EAD.

CONCLUSION

Recipients who develop EAD have longer ICU and hospital stays and greater mortality than those without. Donor, graft, and recipient risk factors all contribute to the development of EAD. Results of these analyses identify factors that, if modified, may alter the risk of EAD.

Vena cava vascular reconstruction during orthotopic liver transplantation: a comparative study

The aim of this study was to evaluate the influence of preserving the recipient's inferior vena cava during orthotopic liver transplantation (OLT) on hemodynamic alterations, blood component requirements, postoperative liver and renal function, as well as vascular-related complications. A total of 122 OLTs was studied. In 35 OLTs, venovenous bypass (BP) was used; in 35 OLTs, bypass was not used (NBP); and in 52 OLTs, the recipient's inferior vena cava was preserved (PC). Preservation of the inferior vena cava means that venous return is not compromised at any time during transplantation. The time of hepatectomy was not different among the three groups (208 +/- 11, 188 +/- 13, and 194 +/- 6 minutes for BP, NBP, and PC, respectively); however, the total operating time was significantly lower in PC patients (492 +/- 24, 459 +/- 18, and 419 +/- 10 minutes for BP, NBP, and PC, respectively; P = .004, ANOVA). Blood component requirements were significantly lower in patients with PC. For red blood cells, these were 15.2 +/- 2.6, 16 +/- 3.4, and 7.1 +/- 1.5 units for BP, NBP, and PC, respectively (P = .009, ANOVA), and for fresh-frozen plasma, these were 5.4 +/- .7, 5.8 +/- .9, and 3 +/- .4 L for BP, NBP, and PC, respectively (P = .005, ANOVA). Postoperative liver and renal function did not differ among the three groups. The incidence of surgical complications (bleeding and vascular) was similar. Preservation of the inferior vena cava of the recipient significantly reduces the magnitude of OLT.

Experience with the piggyback technique without caval occlusion in adult orthotopic liver transplantation

BACKGROUND

To assess the feasibility and outcome of a piggyback technique without caval occlusion or veno-venous bypass (VB), we retrospectively reviewed 131 consecutive adult orthotopic liver transplantation (OLT) performed in 129 patients between May 1993 and February 1995. Six were second transplants, and six were combined liver-kidney transplants. The piggyback technique was attempted in all cases.

METHODS

We were able to perform the piggyback technique in 98 OLTs (75%). The remaining 33 OLTs (25%) were converted to the standard technique; of these, 20 (15%) required VB. The reasons for conversion to the standard technique were: anatomical (22 transplants), severe portal hypertension requiring VB (8 transplants), tumor (1 transplant), and other reasons (2 transplants). Six retransplantations were performed (four piggyback, two standard).

RESULTS

There was no significant difference in age, United Network for Organ Sharing status, Child's classification, and diagnosis between the patients in whom piggyback was possible or not. The actuarial patient and graft survival at 1 year were similar between the piggyback group and the group of patients converted to standard technique (87/85% vs. 86/86%, respectively). No death was related to either technique. With piggyback, the average operative time was 8.6+/-1.9 hr, median amount of blood transfused intraoperatively was 2 U (33% did not require transfusion), and median intensive care unit and hospital stays were 3 and 11 days, respectively. With the piggyback technique, the mean preoperative and maximum postoperative serum creatinine levels were 1.4+/-1.0 and 1.8+/-1.5 mg/dl.

CONCLUSION

The piggyback technique without caval occlusion is possible in the majority of patients. It is safe and has reduced the use of VB to 15% of our adult OLTs. The piggyback technique avoids retrocaval dissection, facilitates retransplantation, and is associated with a short anhepatic phase, low blood product usage, and short intensive care unit stay.