Hepatic and pulmonary enzyme activities in horses

OBJECTIVE

To determine hepatic and pulmonary phase-I and phase-II enzyme activities in horses.

SAMPLE POPULATION

Pulmonary and hepatic tissues from 22 horses that were 4 months to 32 years old.

PROCEDURE

Pulmonary and hepatic tissues from horses were used to prepare cytosolic (glutathione S-transferase and soluble epoxide hydrolase) and microsomal (cytochrome P450 monooxygenases) enzymes. Rates of microsomal metabolism of ethoxyresorufin, pentoxyresorufin, and naphthalene were determined by high-performance liquid chromatography. Activities of glutathione S-transferase and soluble epoxide hydrolase were determined spectrophotometrically. Cytochrome P450 content was determined by carbon monoxide bound-difference spectrum of dithionite-reduced microsomes. Activity was expressed relative to total protein concentration.

RESULTS

Microsomal protein and cytochromeP450 contents were detectable in all horses and did not vary with age. Hepatic ethoxyresorufin metabolism was detected in all horses; by comparison, pulmonary metabolism of ethoxyresorufin and hepatic and pulmonary metabolism of pentoxyresorufin were detected at lower rates. Rate of hepatic naphthalene metabolism remained constant with increasing age, whereas rate of pulmonary naphthalene metabolism was significantly lower in weanlings (ie, horses 4 to 6 months old), compared with adult horses. Hepatic glutathione S-transferase activity (cytosol) increased with age; however, these changes were not significant. Pulmonary glutathione S-transferase activity (cytosol) was significantly lower in weanlings than adult horses. Hepatic and pulmonary soluble epoxide hydrolase did not vary with age of horses.

CONCLUSIONS AND CLINICAL RELEVANCE

Activity of cytochrome P450 isoforms that metabolize naphthalene and glutathione S-transferases in lungs are significantly lower in weanlings than adult horses, which suggests reduced ability of young horses to metabolize xenobiotics by this organ.

Capgras syndrome: analysis of nine cases

Three hundred and sixty-four patients, 158 males and 206 females, were admitted to an acute psychiatric ward between November 1994 and October 1995, and only 9 patients (2 males and 7 females) fulfilled the clinical criteria for Capgras syndrome. The crude prevalence of Capgras syndrome in the acute psychiatric ward was 2.5% (1.3% for men and 3.4% for women), which is not uncommon. Medical records and laboratory examinations, including brain images and electroencephalographic examinations (EEG), were reviewed in the nine patients with Capgras syndrome. Four cases were proven to have apparently abnormal anatomical lesions on EEG, brain computed tomography, magnetic resonance imaging or single photon emission computed tomography (99mTc-HMPAO) examinations and five cases were associated with major physical illness. These findings support that organic factors could be important in the pathogenesis of Capgras syndrome.

Magnetic resonance of the hepatic veins with angular reconstruction: application in living-related liver transplantation

BACKGROUND

Preoperative mapping of the hepatic venous system of the partial liver graft is indispensable to the success of living-related liver transplantation. We assessed the accuracy of magnetic resonance (MR) venography with angular reconstruction in depicting the tributaries of the middle hepatic vein and left hepatic vein in the donors, which was essential in graft retrieval and venoplasty.

METHODS

Nineteen living-related liver transplantation donors underwent a pretransplantation survey, including sonography and MRI for hepatic venous evaluation. T1-weighted images were reconstructed manually, using the inferior vena cava as a fixed point for tilting to produce an oblique plane image where both the middle hepatic vein and left hepatic vein could be demonstrated draining into the inferior vena cava. The reconstructed images of the hepatic veins were compared with preoperative sonography, intraoperative sonography, and operative findings.

RESULTS

Preoperative sonography and MR findings correlated well with the operative findings in the major hepatic veins. The MR venography of the ramification of the hepatic veins has an accuracy of 93%, the sonography, 84%. Sonography is slightly inferior in the evaluation of the hepatic vein in segment 4 and the left superior hepatic vein, with an accuracy of 73% and 67%, respectively.

CONCLUSION

MR venography with angular reconstruction is accurate in depicting the complex distribution of the hepatic veins of the left liver, providing important information for decision making as to the cutting plane during graft retrieval and the method of venoplasty and anastomosis. Thus, unnecessary blood loss could be avoided and vascular complications could be prevented, as these conditions would be unacceptable for a healthy living donor. We propose that MR venography, a rapid and reliable technique, is an appropriate alternative examination or complementary modality to sonography in the pretransplantation evaluation of the living donor.

Novel bisbenzamidines and bisbenzimidazolines as noncompetitive NMDA receptor antagonists

A series of novel bisbenzamidines and bisbenzimidazolines with different linkers connecting the aromatic groups was tested in vitro for NMDA receptor antagonist activity. IC50 values for these compounds ranged from 1.2 to >200 microM. The bisbenzamidine with a homopiperazine ring as the central linker was found to be the most potent NMDA receptor antagonist among all the pentamidine analogues tested so far.

Catatonic features: differential diagnosis and treatments at an emergency unit

During a 2-year period, 34 patients of catatonic features in Chinese ethnic background Taiwanese were brought to the emergency unit of Chang Gung Memorial Hospital at Linkou. The ratios of the causes of catatonic features by schizophrenic disorders, mood disorders, neuroleptic-induced disorders, and general medical conditions were 26, 9, 24 and 41%, respectively. After the treatments of antipsychotics, benzodiazepam, or electroconvulsive therapy (ECT), 24 patients (70.6%) showed complete remission, seven patients (20.6%) showed partial remission, and three patients (8.8%) showed no response (two died). Additionally, a suggestive period is proposed in order to distinguish acute and insidious onset catatonic conditions to help clinicians in deciding on probability immediately. The patients were grouped into four diagnostic categories; namely, schizophrenic disorders, mood disorders, neuroleptic-induced disorders, and general medical conditions for comparison. One-way ANOVA and Duncan's multiple-range test were used for continuous variables, and the Chi-squared test was used for categorical variables. The mean duration of 'insidious onset catatonic condition' (including schizophrenic disorders and general medical conditions) before seeking medical help was longer than 3.33 weeks, while the mean duration of 'acute catatonic condition' (including mood disorders and neuroleptic-induced disorders) was shorter than 1.83 weeks. These findings suggest that 2-3 weeks would be a cut-off point for acute or insidious onsets of catatonic conditions.

Interleukin-1 beta and tumor necrosis factor-alpha suppress dexamethasone induction of glutamine synthetase in primary mouse astrocytes

Astrocytes play a key role in the protection of neurons from excitotoxicity by taking up excess glutamate and converting it to glutamine via the enzyme glutamine synthetase. In a number of cell types, glucocorticoid hormones induce glutamine synthetase. Glucocorticoids also down-regulate many genes induced by proinflammatory cytokines. As the glucocorticoid receptor has been shown to interact with transcription factors that may also be activated by the proinflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), we hypothesized that IL-1beta or TNF-alpha might oppose the induction of glutamine synthetase by dexamethasone. Primary mouse cortical astrocytes were treated with 10(-7) M dexamethasone and doses of IL-1beta or TNF-alpha ranging from 0.02 to 5 ng/ml or 0.05 to 20 ng/ml, respectively. We found that both cytokines attenuated the dexamethasone induction of glutamine synthetase protein at 24 h and that the effect was dose-dependent. We also found that IL-1beta and TNF-alpha inhibited the induction of glutamine synthetase mRNA by dexamethasone, and that the induction of enzymatic activity was similarly prevented by IL-1beta. As glutamine synthetase can be induced by physiological levels of glucocorticoids, the release of proinflammatory cytokines following acute injury or in neurodegenerative disorders may hinder the ability of astrocytes to protect neurons from excitotoxicity.

Intraoperative Doppler ultrasound in liver transplantation

The purpose of this study was to determine the utility of intraoperative Doppler ultrasound for the diagnosis and reduction of the vascular complications in liver transplantation. This study included 19 pediatric and 5 adult patients. In the pediatric group, 12 patients received living related liver transplantation (LRLT), two splitting liver transplantation (SLT), three reduced-size liver transplantation (RLT) and two full-size pediatric liver transplants (FPLT). The hemodynamics and waveform of the hepatic vein, portal vein and hepatic artery were evaluated by intraoperative Doppler ultrasound (US) after reperfusion of the graft. Unsatisfactory hemodynamics was identified in nine cases, including decrease hepatic venous flow (6-9 cm/s) with non-pulsative flat waveform (adults, n = 2 and LRLT, n = 2); portal vein thrombosis (LRLT, n = 1); decrease portal flow (8 mL/min/kg) (LRLT, n = 1); occlusion of the portal vein (SLT, n = 1); poor arterial flow with dampened artery waveform (FPLT, n = 2). These abnormalities were all successfully re-reconstructed by surgical procedures and achieved a graft survival rate of 100%. Two late vascular complications including hepatic venous thrombosis and recurrent portal vein stenosis with splenorenal shunt were discovered 1 month later. They were treated effectively by surgical thrombolectomy and percutaneous balloon dilatation and metallic coils embolization respectively. Three patients died of non-vascular complications and all patients who underwent LRLT survived with a resultant 87.5% overall survival rate. In conclusion, intraoperative Doppler US is efficient in detecting abnormal hepatic hemodynamics, which permits early intervention and hence a better prognosis for the patients. Re-reconstructive procedures were monitored closely under Doppler US guidance until proper flow and wave-form were established. This reduces post-transplant vascular complications and thereby eliminates the likelihood of a lethal complication that might call for re-transplantation.

Living related donor liver transplantation

Living related liver transplantation (LRLT) has been developed in response to the paediatric organ donor shortage. According to the International Living Donor Registry, 521 transplants had been performed in 515 patients between December 8 1988 and January 19 1996 in 30 centres worldwide. The overall actuarial patient and graft survival rates were 82.7 and 80%, respectively. Between June 17 1994 and November 30 1996, the authors performed 11 LRLT at the Chung Gung Memorial Hospital. The living donors consisted of 10 mothers and one father. The mean graft weight was 303 g and the mean graft recipient weight ratio was 2.2%. Donor hepatectomy was performed without vascular inflow occlusion. The intra-operative blood loss ranged from 30 mL to 120 mL with an average of 61 mL, and blood transfusion was not required in all donors both intra-operatively and during the postoperative period. Underlying diseases of the recipients were biliary atresia (n = 10) and glycogen storage disease (n = 1). The mean graft cold ischaemia time was 106 min, the mean second warm ischaemia time was 51 min and the mean interval between portal and arterial reperfusion was 81 min. The initial LRLT results were promising with all donors having been discharged without complication. The recipients experienced a few complications, all of which were manageable with early intervention. All 11 recipients are alive and well. These are encouraging results and the authors hope to expand the use of live donors for liver transplantation to cope with demand.

Variations of the intrahepatic bile ducts: application in living related liver transplantation and splitting liver transplantation

The variations in the anatomy of intrahepatic bile ducts complicate operations in living related liver transplantation (LRLT) and therefore preoperative delineation of the biliary system is important to achieve a successful outcome. The aim of this study was to establish a standard relationship between the biliary variations and the methods of the graft splitting and anastomosis. Of 958 endoscopic retrograde cholangiographies with good visualization of bile duct branches were selected and were available for evaluation of their ramifications and variants. According to drainage of right hepatic duct and left hepatic duct, we classified the bile ducts into two major groups. Unusual routes of the intrahepatic ducts were present in 105 cases (11% in group A) the right sectoral duct drained into the left hepatic duct directly; in 200 cases (21% in groups B) the duct of segment IV drained into right side or common hepatic duct; and in 29 cases (3% in groups B) the duct of segment: II and III drained into the CBD and right hepatic duct separately. There is no specific bile duct variation that forbids someone from LRLT and SLT, but unusual intrahepatic ducts routes may require a change both in the cutting plane during graft retrieval and pattern of ductoenteral anastomosis to avoid potential complications to both donors and recipients. Cholangiography for screening intrahepatic duct variations is therefore important for safe bile drainage for both donors and recipients.

Histopathology of the liver in pediatric patients following transplantation

Recognition of rejection and other hepatic complications by needle biopsy plays a significant role in the management of liver allograft recipients. In this report, 22 pediatric patients (below 18 years old) were selected from the 37 liver transplants. Seven of the 22 cases have an uneventful posttransplant course. The most common cause of allograft injury in these patients appeared to be acute cellular rejection. It occurred in 7 (31.8%) of the 22 cases and was the primary process in 8 of the 25 episodes of liver dysfunction. Other etiologies, such as opportunistic viral infection (3 cases), biliary obstruction (2 cases), preservation injury (1 case), and vascular obstruction (1 case) were less common. Acute graft rejection causing liver dysfunction was associated with a mixed portal inflammation, destruction of the interlobular bile ducts, and varied degree of venous endotheliitis, followed by centrilobular hepatocyte necrosis. Chronic rejection was not seen in our pediatric cases. Cold ischemic injury causing transient graft dysfunction as seen in one of our patients demonstrated focal, limited areas of hepatocyte necrosis, mild centrilobular hepatocyte ballooning, and cholestasis without evidence of bile duct damage. More severe ischemic injury resulted from vascular complication causing diffuse hepatocyte necrosis was seen in one patient with hepatic vein thrombosis. The histologic patterns observed were not pathognomic; however, liver biopsies were helpful in suggesting the probable cause of liver dysfunction and in predicting subsequent allograft recovery when used in conjunction with clinical information, radiologic, and other laboratory tests.

Three-dimensional helical computed tomographic cholangiography: application to living related hepatic transplantation

Variations in the anatomy of intrahepatic bile ducts complicate operations in living related hepatic transplantation (LRHT). Preoperative delineation of the biliary system is important to achieve successful results. The purpose of this study was to assess the utility and accuracy of three-dimensional helical computed tomographic cholangiography (3DHCTC) as a replacement for endoscopic retrograde cholangiography (ERC) in evaluating the anatomy of the intersegmental biliary connection of the potential donors in LRHT. Helical CT was performed in 16 potential donors after a slow infusion of 100 cm3 meglumine iodipamide. By using the maximum intensity projection and shaded surface displaced image reconstruction technique, three-dimensional images of the bile ducts were isolated from the surrounding hepatic parenchyma. Among the 16 potential donors, 3 cases underwent an ERC study and another 7 cases donated liver graft during LRHT. In all 16 cases the anatomy of the bilateral essential intrahepatic ducts was well displayed with and without the liver parenchyma background in an axial and three-dimensional fashion which had good correlation with images from ERC and intra-operative cholangiography. Two variants were found, including drainage of the right posterior intrahepatic duct into the left hepatic duct and direct drainage of the segment II bile duct into the common hepatic duct, respectively. It is concluded that unusual routes of intrahepatic ducts may necessitate a change in the cutting plane during graft retrieval and patterns of ductoenteral anastomosis to avoid potential complications to both donors and recipients. With the advantages of non-invasiveness and comparable accuracy in demonstrating biliary anatomy, 3DHCTC may replace the traditional ERC in the pre-transplant survey of potential donors for LRHT.

Variations of the middle and inferior right hepatic vein: application in hepatectomy

We evaluated the anatomic variations of the middle right hepatic vein (MRHV) and inferior right hepatic vein (IRHV) and their clinical application to the possibility of right subtotal hepatectomy. In 400 of normal livers studied with ultrasound, the IRHV was found to drain segment 6 of the liver and flow into the inferior vena cava (IVC) in 72 (18%) cases. In 22 (5.5%) cases, the MRHV was found to drain segment 5 of the liver and flow into the IVC. The size of the IRHV ranged from 0.1 cm to 0.8 cm with an average of 0.46 cm. For the MRHV, the sizes ranged from 0.1 cm to 0.9 cm with an average of 0.34 cm. In 10/79 (12.6%) cases the IRHV and in 4/ 22 (18.1%) cases the MRHV were bigger than the right hepatic vein (RHV). The distance between the RHV and IRHV ranged from 3 cm to 5 cm with an average of 3.7 cm. The distance between the RHV and MRHV ranged from 3 cm to 3.3 cm with an average of 3.1 cm. A hyperechoic edge, similar to that of the portal vein, was observed at the wall of the hypertrophic IRHV and was 0.3 cm or larger in size. Preoperative delineation of this complex venous anatomy is very important. It provides vital information in the preoperative evaluation needed before performing a right subtotal hepatectomy with preservation of segment 6 or segment 5 of the liver, and with RHV resection. Prior to undertaking a right hepatectomy, clamping the hypertrophic MRHV and IRHV electively may minimize intra-operative blood loss and extrahepatic spread of the malignancy.

Magnetic resonance venography in potential pediatric liver transplant recipients

Vascular anomalies may be hazardous to liver transplantation, and pre-operative vascular evaluation is important for a safe and successful operation. The purpose of this study was to assess the utility and accuracy of time-of-flight (TOF) magnetic resonance venography (MRV) with three-dimensional (3D) reconstruction as an alternative for conventional catheter angiography in evaluating the portal venous system and inferior vena cava (IVC) in potential pediatric liver transplant recipients. Twenty consecutive cases of small children with biliary atresia were evaluated with TOF MRV with 3D reconstruction by Advantage Window workstation. All 20 cases underwent conventional angiography; two cases received transhepatic portography and three cases received splenoportographic study. The whole MRV examination and filming required less than 30 min. Findings of portal vein and IVC completely agreed with or were superior to the successful catheter angiographic images. The portal vein was occluded in five cases, and patent in fifteen cases which included: twelve hepatopetal flow, two hepatofugal flow and one small caliber portal vein. Varices were found in 18 cases. In the case of the IVC, 18 of them were normal and 2 had congenital abnormalities which included paired vena cava and hypoplasia vena cava with compensatory enlargement of the azygos and hemiazygos systems. Eight of the cases received liver transplantation, and the MRV findings totally correlated with the final anatomy as found intraoperatively. MRV is accurate for evaluating the condition of the portal venous system and IVC, detection, and determining the distribution and extents of the varices. It is a reliable, noninvasive and rapid technique which can be considered as an alternative workup for the invasive angiography and or portography in small children for pre-transplantation evaluation.

Metalloprotein analysis by capillary isoelectric focusing

Capillary isoelectric focusing (cIEF) was used to analyze three metalloproteins: conalbumin, transferrin and metallothionein (MT). Two different ampholyte mixtures were employed that generated linear pH gradients of 3-10 and 5-8. Several different proteins and one peptide with known isoelectric points (pIs) were used to establish linear relationships between peak migration time and pI. These standards were also used as internal markers to estimate peak pI values of the metalloproteins subjected to cIEF. Conalbumin (iron-free) subjected to cIEF with a pH gradient of 3-10 yielded a single major component (pI 7.17). When the protein was saturated with iron (2 Fe3+/mol protein), a shift to lower pI was observed with a major peak (pI 6.24) and a lesser peak (pI 6.09). Mixing iron-free with iron-saturated conalbumin or adding iron to iron-free conalbumin prior to cIEF produced an additional peak (pI 6.68) that was presumed to be conalbumin containing a single iron atom (monoferric form). Human transferrin subjected to cIEF with a pH range of 3-10 gave a similar separation pattern to conalbumin with four major peaks at pI values of 6.25 (apotransferrin), 5.96 (monoferric form), 5.48 and 5.34 (diferric forms). Additional resolution of the molecular forms of both conalbumin and transferrin was achieved using a narrower pH gradient (5-8). Rabbit liver MT subjected to cIEF with a pH gradient of 3-10 gave a complex separation pattern with two prominent peaks (pI values of 3.73 and 3.56) that were presumed to be the fully metal-saturated MT-1 and MT-2 isoforms. When individual MT isoforms (MT-1 and MT-2) were separately subjected to cIEF with a pH gradient of 3-10, heterogeneous peaks with higher pI values (4.12-4.74) were observed. In contrast, horse kidney MT gave a single predominant peak with a pI of 4.09. MT samples could be separated using a pH gradient of 5-8 despite the fact that their apparent pI values were below the limits of the pH gradient established. In general, the heterogeneity observed for conalbumin, transferrin and MT proteins subjected to cIEF reflects the presence or absence of bound metal. Thus, cIEF represents a potentially useful analytical method which can provide information concerning the metal-binding characteristics of these and perhaps other metalloproteins.

Anatomic dissociation between the intrahepatic bile duct and portal vein: risk factors for left hepatectomy

The anatomic variations of the intrahepatic portal vein and bile duct were analyzed to evaluate the potential risk of left hepatectomy. A total of 210 cholangiograms and hepatic arterioportograms were performed in which the ramifications of the intrahepatic portal vein and bile duct were investigated. The orientation of the intrahepatic duct and portal vein were classified into five types. In 175 patients (83.33%), the intrahepatic portal vein and bile duct had the same anatomic classification. In 24 patients (11.43%), the right anterior or posterior intrahepatic duct drained into the left hepatic duct at the umbilical portion (type IV); there were only 15 patients (7.14%) whose portal veins fell into this category. All patients with type IV portal veins had type IV hepatic ducts, but there were 9/49 patients (18.36%) whose hepatic duct distribution belonged to type IV but their portal veins belonged to type II (6 cases) or III (3 cases). Without complete knowledge of the intrahepatic portal and biliary anatomy, insufficient portal perfusion and bile duct complications may result from the left hepatectomy operation. Preoperative portal vein evaluation or left portal vein clamping can provide significant information, but there are still 18.36% of patients where type IV biliary ducts were not detected in those with type II and III portal veins. Cholangiography is of paramount importance in these two groups of patients, as it can prevent inadvertent injury to the right intrahepatic ducts, which drain into the left intrahepatic duct. On the other hand, intraoperative ultrasonography is recommended to identify or exclude an aberrant portal vein if type VI biliary anatomy is detected during intraoperative cholangiography.

Development of a high-performance capillary isoelectric focusing technique with application to studies of microheterogeneity in chicken conalbumin

A robust, simple, reproducible isoelectric focusing method using capillary electrophoresis that exhibits high stability, migration time reproducibility and pH linearity over a wide pH gradient was developed. Consecutive runs (over 113 runs) of several proteins and one peptide with isoelectric points (p/s) ranging from 9.45 to 2.75 yielded excellent migration time reproducibility (< 2% R.S.D.). Experimental parameters including buffer aging and capillary-to-capillary variation were thoroughly examined and optimized to improve the migration time reproducibility. The capillary isoelectric focusing (CIEF) method was applied to the analysis of chicken conalbumin (ovotransferrin), an iron-binding protein in egg white. Conalbumin (low iron content) separated into three major components with p/s of 7.2, 6.6 and 6.2. When the protein was saturated with iron (2 Fe/mol), a shift to lower p/s was detected. Chicken serum transferrin subjected to CIEF gave a pattern similar to conalbumin with three p/s of 7.1, 6.6 and 6.1, indicating that it was not fully saturated with iron. Thus, CIEF can be used as a potential analytical method to provide information about the metal-binding properties of specific metalloproteins.

Structure-activity relationships for substrates and inhibitors of mammalian liver microsomal carboxylesterases

PURPOSE

Carboxylesterases are important in the detoxification of drugs, pesticides and other xenobiotics. This study was to evaluate a series of substrates and inhibitors for characterizing these enzymes.

METHODS

A series of novel aliphatic esters and thioesters were used in spectral assays to monitor human, murine and porcine esterases. A series of transition state mimics were evaluated as selective esterase inhibitors.

RESULTS

Several alpha-alkyl thioacetothioates were found to be approximately 2 to 11-fold superior to commonly used substrates for monitoring carboxylesterase activity. Insertion of a heteroatom in the acid portion of these esters in the beta or gamma position relative to the carbonyl had a dramatic effect on enzyme activity with S or O substituents often improving the kCAT/K(M) ratio of the substrate and N decreasing it. Several alpha,alpha'-bis (2-oxo-3,3,3-trifluoropropylthio)alkanes proved to be potent selective transition state mimics of the esterase activity with IC50's from 10(-5) to 10(-9)M.

CONCLUSIONS

This library of substrates and inhibitors are useful research tools for characterizing the numerous isozymes of carboxylesterases present in mammalian tissues.

Paediatric liver transplantation: a 10 year experience in Taiwan

Between March 1984 and August 1994, 13 orthotopic liver transplantations were performed in 13 patients < or = 25 years of age. The indications included Wilson's disease (n = 7), biliary atresia (n = 4), choledochal cyst (n = 1) and hepatitis C cirrhosis (n = 1). Technical variants included full-size (n = 11), reduced-size (n = 1) and living-related (n = 1) liver transplantation. These recent technical innovations have offered an expanded donor pool for earlier transplantation, shorter waiting times and excellent quality grafts. Surgical complications occurred in six patients; all required additional surgery. Biliary complications were encountered more commonly in our earlier patients. Our actuarial patient and graft survival rate is 92% at 2 years. The long-term follow-up of our liver-transplanted Wilson's disease patients provides confirmatory evidence that orthotopic liver transplantation cures the underlying metabolic defect with complete normalization of biochemical abnormalities of copper metabolism, reversal of neurological impairments and the disappearance of Kayser-Fleischer corneal rings. The high rate of patient survival and excellent rehabilitation indicate that with prudent clinical judgement, liver transplantation can be achieved with an acceptable rate of morbidity, mortality and cost in a setting where manpower and donor organs are very limited.

Total knee arthroplasty in tuberculous arthritis

Sixteen cases of tuberculosis of the knee treated by total knee arthroplasty with followup of 3.4 to 11 years were reviewed. Eight cases were treated with antituberculous chemotherapy for 2 to 20 months before and 1 year after the arthroplasty. Another 8 cases were not diagnosed primarily and therefore received only postoperative antituberculous chemotherapy. Five cases had a recurrence of tuberculosis. Four of these 5 cases did not receive preoperative antituberculous treatment. The infection in 1 case was controlled satisfactorily with chemotherapy alone, and for the other 3 cases, chemotherapy was supported by surgical debridements. The last case of recurrent infection occurred in a patient who had received long- standing corticosteroid therapy. He required an excisional arthroplasty to control the infection. The mean functional knee score was 30.5 points before surgery and 82.6 points at the time of the last followup. These results suggest that arthroplasty may be formed for knees badly damaged with tuberculous infection, and good results may be expected for those patients who have received effective antituberculous chemotherapy both before and after surgery. There is a substantial risk of reactivation of tuberculous infection for those patients not treated before surgery or for patients dependent on corticosteroids.

Variations of the left and middle hepatic veins: application in living related hepatic transplantation

The anatomic variations of the middle hepatic vein (MHV) and left hepatic vein (LHV) in 200 patients with normal liver function were analyzed using ultrasonography to clarify the feasibility of resecting the left lobe or left lateral segment in living subjects for living related hepatic transplantation (LRHT). The MHV and LHV form a common trunk in 70% of cases but drain independently into the inferior vena cava (IVC) in 30%. In 7% of cases, the left median vein (LMV) drains into the MHV, in 32% of cases the anterior superior segmental vein (ASSV) that drains segment 8 flows into the MHV. The distance between the two confluence points (LHV flows into MHV or IVC and LMV flows into the MHV) ranged from 0.3 cm to 2.5 cm with an average of 0.75 cm. The diameter of the LMV at the point that flows into MHV ranged from 0.3 cm to 0.9 cm. with an average of 0.61 cm. The distance from the IVC to the confluence of the MHV and LHV ranged from 0 cm to 3.5 cm with an average of 1.5 cm in those cases whose MHV and LHV presented as common trunks. Preoperative delineation of this complex venous anatomy is of paramount importance because the hepatic veins have to be transected in the cutting plane of the liver. The location of this plane is determined by the optimal graft volume required, and both the graft and the remnant liver have to retain perfect function. The venous anatomy would change the cutting plane in the living donor and the surgical method of anastomosis for the recipient.

Treatment of postoperative residual hepatolithiasis after progressive stenting of associated bile duct strictures through the T-tube tract

PURPOSE

The authors report their experience with the treatment of intrahepatic bile duct strictures associated with hepatolithiasis.

METHODS

Eighty patients had multiple postoperative retained intrahepatic duct stones trapped behind intrahepatic biliary strictures. Before stone extraction, the strictures were opened gradually by semirigid dilators, followed by stent placement to create enough patency for stone removal. All procedures were carried out through the T-tube tracts and were aided by cholangioscopy and electrohydraulic lithotripsy.

RESULTS

Complete clearance of stones was achieved in 69 patients. Failure to dilate the strictures was due to acute and multiple ductal angulations. These included the right posterior inferior intrahepatic duct at its junction with the left intrahepatic ducts when it was more than 2 cm distal to the hepatic bifurcation, when the angle between the T-tube tract and the common bile duct was smaller than 90 degrees, and when stones were located in peripheral intrahepatic ducts with more than five angulations.

CONCLUSION

This technique is considered safe and effective for complicated hepatolithiasis with intrahepatic biliary strictures.

Characterization of a spectrophotometric assay for juvenile hormone esterase

Two surrogate substrates, methyl 1-heptylthioacetothioate (HEPTAT) and methyl 1-hexylthioacetothioate (HEXTAT) were utilized to compare a new spectrophotometric assay with the standard radiochemical partition assay used to quantify juvenile hormone esterase (JHE) activity. The surrogate substrates were made with one common factor being a thiol ester moiety substituting for the ester moiety found in juvenile hormones (JHs) and a thioether replacing the 2,3-olefin of the JHs. As a result, nucleophilic attack by the serine residue of JHE at the carbonyl functional group results in a hydrolytic reaction and release of methanethiol. In the presence of Ellman's Reagent (DTNB) methanethiol will cleave the disulfide bond of DTNB resulting in a chromophore detectable at 405 nm. Methyl 1-hexylthioacetothioate and its oxygen ester analogue, methyl-1-hexylthioacetate, were compared for JHE activity. Statistical analysis of the slopes indicated a very small but significant difference between the hydrolytic rates for the thiol ester and oxygen ester. However, the data indicate that thiol esters can replace oxygen esters to quantify hydrolytic activity by the JHEs examined. Results gathered from different preparations of JHE including tissue culture media from a baculovirus expression system, affinity- and DEAE-purified enzyme, as well as insect hemolymph indicate an excellent correlation between the two assays. Isoelectric focusing of pure and crude JHE preparations resulted in coinciding peaks of hydrolytic activity when using the standard partition assay and the spectrophotometric assay, with no other peaks of activity found in the crude preparations with either substrate. Several esterase bands were found at different isoelectric points when gels were stained with alpha-naphthyl acetate.(ABSTRACT TRUNCATED AT 250 WORDS)

Juvenile hormone esterase purified by affinity chromatography with 8-mercapto-1,1,1-trifluoro-2-octanone as a rationally designed ligand

Trifluoromethyl ketones are potent inhibitors of a variety of serine hydrolases. Based on this chemistry improved affinity chromatography procedures were developed for juvenile hormone esterase from insects. New affinity gels were prepared by binding rationally designed ligands to epoxy-activated Sepharose. One ligand is 8-mercapto-1,1,1-trifluoro-2-octanone which has a methylene group replacing a sulfide sulfur beta to the carbonyl of the trifluoromethyl ketone of the previously reported ligand, 3-(4-mercaptobutylthio)-1,1,1-trifluoro-2-propanone. With many loading levels and esterases, the original gel bound enzymes too tightly, resulting in elution difficulties. This replacement of the sulfur beta to the ketone thought to interact with the catalytic serine decreases the binding capacity of the gel at similar loading by approximately 56% compared to the affinity gel with the thioether. However, elution of the enzyme from the column can be accomplished with less potent inhibitors such as 3-n-butylthio- or 3-n-pentylthio-1,1,1-trifluoro-2-propanone, which can easily be removed from the enzyme by dialysis in the presence of the detergent n-octyl beta-D-glucopyranoside. An alternative approach allowing elution with less potent inhibitors involved varying concentrations of the previous high-affinity ligand to optimize the concentration of ligand on the column. Low concentrations of the high-affinity ligand also allowed the use of less potent eluting agents. These two improved affinity chromatography systems have been successfully used to purify juvenile hormone esterase of Heliothis virescens to near homogeneity with a 30-90% recovery of recombinant esterase secreted into the cell media in a baculovirus expression system. The purity of the esterase after affinity chromatography with newly prepared gel was comparable to that produced using the original affinity system based on analyses by SDS-PAGE and isoelectric focusing. A library of affinity gels with ligands of different affinities used at several loading levels and a library of eluting inhibitors of varying potency facilitate the rational selection of conditions for the affinity purification of esterases.

Development of surrogate substrates for juvenile hormone esterase

Twenty-nine thioester compounds were synthesized to test their effectiveness as surrogate substrates for the insect enzyme, juvenile hormone esterase (JHE). Substrates were designed that resembled the endogenous substrate juvenile hormone (JH), with one common factor being a thioester instead of carboxyl ester found in JH. The principle of the spectrophotometric assay is based on a modification of Ellman's method. Characterization of the substrates showed that replacement of the carbon atom by a sulfur or oxygen beta to the carbonyl of the acyl group of the substrates resulted in an approximate five- to sixfold increase in the rate of hydrolysis by JHE. The specific activities of JHE, porcine liver carboxylesterase, and acetylcholinesterase were determined for the surrogate substrates. While JHE and porcine liver carboxylesterase hydrolyzed several of the substrates, acetylcholinesterase did not produce any detectable hydrolysis of the substrates. Michaelis-Menten kinetic parameters of the surrogate substrates when compared to a previously reported partition assay, utilizing radiolabeled [3H]JH III, indicated that the surrogate substrates have lower affinity as indicated by higher Km values but are more easily hydrolyzed (Vmax) by JHE. Furthermore, optimal reaction conditions for substrate hydrolysis and the spectrophotometric reaction were determined. In addition, first order rate constants for base hydrolysis and critical micelle concentrations were determined for several surrogate substrates. The spectrophotometric assay was also compared with a Vmax and research spectrophotometer, and these two instruments produced almost identical slopes. The relative potency of four transition state inhibitors of JHE was found to be similar with those of the surrogate substrates and the [3H]JH III substrate.

Effect of hepatotoxic doses of paracetamol and carbon tetrachloride on the serum and hepatic carboxylesterase activity in mice

The carboxylesterase activity in the serum and liver of untreated Swiss-Webster mice, and in mice administered hepatotoxic doses of either CCl4 or paracetamol was studied. In addition to p-nitrophenyl acetate (p-NpAc) and diethylsuccinate, a sensitive, spectrophotometric substrate, methyl beta-(1-pentylthio) propiothioate was used to determine the esterase activity. At 24 h after treatment with CCl4 (1 mL kg-1), the liver esterase activity in the soluble fraction acting on p-NpAc was increased 1.7-fold whereas the microsomal esterase activity decreased by one-half. The serum esterase activity increased 2.4- to 3.4-fold depending upon the substrate used. Esterase activity assays of sliced gels from isoelectric focusing (IEF) of serum from mice treated with CCl4 indicated the presence of at least three additional esterase peaks when compared with serum of control mice. These peaks correlated with esterase bands visualized after staining the IEF gel with 1-naphthyl acetate. Furthermore, these esterase bands matched closely the esterase bands from microsomes of normal mice. The serum esterase activity was analysed at 4, 8, 12 and 24 h after paracetamol (400 mg kg-1) treatment. Serum esterase activity remained unchanged or decreased marginally depending on the treatment time and substrate used. Serum glutamic oxalacetic transaminase levels in CCl4- and paracetamol-treated mice, however, were significantly elevated compared with control mice. These results suggest that acute liver damage might cause the release of carboxylesterase activity to the soluble intracellular and extracellular compartments, including blood serum, with some but not all toxicants. The results also indicate that the different modes of action of the two chemicals may account for the difference in the serum carboxylesterase activity of the experimental animals.

Hydrolysis of carbonates, thiocarbonates, carbamates, and carboxylic esters of alpha-naphthol, beta-naphthol, and p-nitrophenol by human, rat, and mouse liver carboxylesterases

Thirty carbonates, thiocarbonates, carbamates, and carboxylic esters of alpha-naphthol, beta-naphthol, and p-nitrophenol were synthesized and tested as substrates for liver carboxylesterases from the crude microsomal fractions of human and mouse, and purified isozymes, hydrolases A and B, from rat liver microsomes. The carbonates, thiocarbonates, and carboxylic esters of alpha-naphthol were cleaved more rapidly than the corresponding beta-naphthol isomers by the mammalian liver esterases. alpha-Naphthyl esters of acetic, propionic, and butyric acids were among the best substrates tested for these enzymes. The majority of the substrates was consistently hydrolyzed at higher rates by hydrolase B compared with hydrolase A, although the Michaelis-Menten constant (Km) values of selected substrates differed widely with these two isozymes. Malathion was a 15-fold better substrate for hydrolase B than for hydrolase A. Compared with the corresponding carboxylates, the carbonate moiety of alpha- and beta-naphthol and p-nitrophenol lowered the specific activities of the enzymes by about fivefold but improved stability under basic conditions. The optimum pH of mouse liver esterase with the acetate, methyl-carbonate, and ethylthiocarbonate of alpha-naphthol was between pH 7.0 and pH 7.6. Human and mouse liver microsomal esterase activities were about five orders of magnitude lower than the esterase activities of purified rat liver hydrolase B. A relationship between the catalytic activity of the enzymes and the lipophilicity of the naphthyl substrates indicated that (i) in the alpha- and beta-naphthyl carbonate series, an inverse relationship between enzyme activity and lipophilicity of the substrates was observed, whereas (ii) in the alpha-naphthyl carboxylate series, an increase in enzyme activity with increasing lipophilicity of the substrates up to a logP value of about 4.0 was observed, after which the enzyme activity decreased.

Effects of moderate dietary restriction and age on blood parameters and metabolic enzymes in Lobund—Wistar rats

The effects of moderate dietary restriction (DR) on certain blood parameters and metabolic enzymes were studied in 80 male Lobund-Wistar rats at 6, 12, 18, 24 and 30 months of age. Two groups of rats were fed ad libitum (AL) or restricted (DR) to 12 g per day from weaning. Adult DR rats received 30% less diet per day when compared to adult rats in AL group. Blood glycohemoglobin levels increased significantly with age in AL rats, but not in those of the DR group. Hematocrit showed a significant decrease at 24 and 30 months in both groups. Serum glucose levels in rats were not affected by either diet or age. Five enzymes in the liver cytosolic fractions were determined. Activities of pyruvate kinase (PK) and lactate dehydrogenase (LDH) were significantly lower in the DR group than in the AL group at each age. Activities of glutamate-pyruvate transaminase (GPT), glutamate-oxaloacetate transaminase (GOT) and malate dehydrogenase (MDH) were significantly higher in the DR group than in the AL group. The results suggest that moderate DR decreased the glycolytic pathway and appears to stimulate amino acid metabolism and increase gluconeogenesis.

Assessment of amyloid beta-protein precursor gene mutations in a large set of familial and sporadic Alzheimer disease cases

A genetic locus associated with familial Alzheimer disease (FAD) and a candidate gene, APP, encoding the amyloid protein precursor have both been assigned previously to chromosome 21, and, in a few FAD families, mutations of APP have been detected. However, obligate crossovers between APP and FAD have also been reported in several FAD pedigrees, including FAD4, a large kindred showing highly suggestive evidence for linkage of the disorder to chromosome 21. In case the apparent APP crossover in FAD4 actually represented an intragenic recombination event or segregation of different mutations in different family branches, we have performed a more detailed assessment of APP as a candidate gene in this family. The entire coding region of the APP gene was sequenced for FAD4 and for FAD1, a second large kindred. No mutations were found, indicating that, in at least one chromosome 21-linked FAD pedigree, the gene defect is not accounted for by a mutation in the known coding region of the APP gene. A total of 25 well-characterized early- and late-onset FAD pedigrees were typed for genetic linkage to APP, to assess the percentage of FAD families predicted to carry mutations in the APP gene. None of the FAD families yielded positive lod scores at a recombination fraction of 0.0. To estimate the overall prevalence of FAD-associated mutations in the beta A4 domain of APP, we sequenced exons 16 and 17 in 30 (20 early- and 10 late-onset) FAD kindreds and in 11 sporadic AD cases, and we screened 56 FAD kindreds and 81 cases of sporadic AD for the presence of the originally reported FAD-associated mutation, APP717 Val----Ile (by BclI digestion). No APP gene mutations were found in any of the FAD families or sporadic-AD samples examined in this study, suggesting that the mutations in exons 16 and 17 are a rare cause of FAD. Overall, these data suggest that APP gene mutations account for a very small portion of FAD.

Inhibition of N8-acetylspermidine deacetylase by active-site-directed metal coordinating inhibitors

A number of substrate analogues of N8-acetylspermidine (N8-AcSpd) (16) and chemical modifying agents containing metal coordinating ligands were assayed as inhibitors of the cytoplasmic enzyme N8-AcSpd deacetylase from rat liver. The enzyme is inhibited by metal chelators, several omega-amino-substituted carboxylic acids, and some thiol reagents. Inhibition by diisopropyl fluorophosphate was observed only at high concentrations. These results suggest that the catalytic mechanism of the enzyme requires a transition state metal and free sulfhydryl groups for activity. The most potent inhibitor synthesized 6-[(3-aminopropyl)amino]-N-hydroxyhexanamide (15), has an apparent Ki of 0.001 microM. It binds to the target enzyme 11,000 times tighter than the substrate (apparent Km = 11 microM). These compounds and a previously reported series of compounds (Dredar, S. A.; Blankenship, J. W.; Marchant, P. E.; Manneh, V. A.; Fries, D. S. J. Med. Chem. 1989, 32, 984-989) are useful in mapping the active site and determining the physiological function of N8-AcSpd deacetylase.