Abnormal proinsulin levels in thyroid dysfunction measured by a sensitive proinsulin immunochemiluminoassay

Abnormalities of carbohydrate metabolism in hyperthyroid patients have been long noted. Elevated proinsulin level is considered as an early marker of B-cell impairment. Proinsulin levels in hyperthyroid patients decreased after antithyroid drug therapy. However, proinsulin in hypothyroid patients was only rarely reported, and the difference was only demonstrated after glucose stimulation-there was a greater response of proinsulin secretion after thyroxine therapy-and the basal fasting proinsulin level was not different after therapy. One of the reasons might be that the assay was not sensitive enough to detect the change of basal proinsulin levels in patients with hypothyroidism after therapy. A newly developed immunochemiluminometric assay of proinsulin was used to demonstrate that the suppressed proinsulin level increased after thyroxine therapy in hypothyroid patients (4.2 +/- 2.4 vs. 10.0 +/- 5.6 pmol/L, p < 0.05; n = 7). On the other hand, our study also confirmed that the proinsulin levels decreased in hyperthyroid patients after antithyroid therapy by methimazole (27.8 +/- 26.0 vs. 15.8 +/- 15.7 pmol/L, p < 0.05; n = 12). In conclusion, proinsulin increased in hypothyroid patients after thyroxine therapy and decreased in hyperthyroid patients after methimazole therapy. The results demonstrated there is a high correlation between thyroid function and B-cell function in hypothyroid as well as hyperthyroid patients.

A modified design of microwave tissue coagulator monopolar antenna for applications in laparoscopic hepatic surgery

Massive hemorrhage is of primary concern during hepatic surgery. In this study, we not only modified the monopolar antenna of the microwave tissue coagulator but also investigated its feasible applications in laparoscopic hepatic surgery. In addition, the conventional antenna of the microwave tissue coagulator was used as a model. A catheter was attached to the antenna. The network analyzer was used to analyze the impedance of the novel monopolar antenna. Moreover, we designed and constructed a novel monopolar antenna for the microwave tissue coagulator. The antenna is gas-leak-proof, having sufficient stiffness and length and retaining similar microwave emission strength, pattern, and shielding property as the conventional antenna. In vitro tests in porcine liver confirm the coagulation and hemostatic effects of the novel type laparoscopic monopolar antenna. Results presented herein confirm the effectiveness of a laparoscopic monopolar antenna for a microwave tissue coagulator with sufficient coagulation effects.

Donor leukocyte infusion as salvage therapy in an adult with relapsed acute lymphoblastic leukemia after allogeneic bone marrow transplantation

Relapse of malignancy after allogeneic bone marrow transplantation remains the major cause of treatment failure in patients with leukemia. While donor leukocyte infusion (DLI) has been used to treat such patients, its use in patients with acute lymphoblastic leukemia is seldom reported. We describe a 35-year-old woman who suffered relapse of acute lymphoblastic leukemia after allogeneic bone marrow transplantation. She received DLI twice as salvage therapy. This patient achieved complete remission following DLI and has remained in remission for more than 11 months without further chemotherapy. We suggest DLI can be used as an initial salvage therapy, without significant toxicity, for patients with relapsed acute lymphoblastic leukemia following bone marrow transplantation.

ATRA-induced pseudotumour cerebri--one case report

A 17-year-old girl with acute pomyelocytic leukemia (APL) went into complete remission following Daunorubicin, Ara-C and ATRA chemotherapy for 1 month. Unfortunately, prolonged administration of ATRA 6 weeks later caused binocular diplopia with left abducent nerve paresis, which gradually disappeared upon withdrawal of ATRA. We propose that it is ATRA induced pseudotumour cerebri and present this case to discuss the relationship between the ATRA and pseudotumour cerebri.

Consequences of metabolic inhibition in smooth muscle isolated from guinea-pig stomach

1. In smooth muscle isolated from the guinea-pig stomach, cyanide (CN) and iodoacetic acid (IAA) were applied to block oxidative phosphorylation and glycolysis, respectively. Effects of IAA on generation of spontaneous mechanical and electrical activities were systematically investigated by comparing those of CN. Spontaneous activity ceased in 10-20 min during applications of 1 mM IAA. On the other hand, application of 1 mM CN also reduced the spontaneous activity, but never terminated it. In the presence of CN the negativity of the resting membrane potential was slightly reduced. 2. When spontaneous activity ceased with IAA, the resting membrane potential was not significantly affected. Also, before ceasing, the amplitude and duration of the spontaneous electrical activity were significantly reduced. The amplitude of the electrotonic potential was, however, not changed by IAA. Further, glibenclamide did not prevent the effects of IAA. These results suggest that, unlike cardiac muscle, activation of metabolism-dependent K+ channels in stomach smooth muscle does not seem to play a major role in reducing and terminating spontaneous activity during metabolic inhibition. 3. Carbachol-induced contraction transiently increased, and subsequently decreased gradually during application of IAA. 4. After 50 min application of IAA, when there was no spontaneous activity, the concentrations of phosphocreatine (PCr) and ATP measured with 31P nuclear magnetic resonance decreased to 60 and 80% of the control, respectively, while inorganic phosphate (Pi) concentration paradoxically fell to below detectable levels. During subsequent prolonged application of IAA, high-energy phosphates steadily decreased. On the other hand, after 50 min CN application, [PCr] and [ATP] decreased to approximately 30 and 80% of the control, respectively, while [Pi] increased by 2.6-fold. 5. In the presence of either CN or IAA, spontaneous mechanical and electrical activities were reduced or eliminated, although amounts of high-energy phosphates sufficient to contract smooth muscle remained. It can be postulated that some mechanism(s) related to energy metabolism, but not including ATP-sensitive K+ channels, plays an important role in generating spontaneous activity in guinea-pig stomach smooth muscle. During metabolic inhibition the energy metabolism-dependent mechanism(s) would preserve high-energy phosphates, and consequently cell viability, by stopping spontaneous activity.

Functional roles of the N-terminal amino acid residues in the Mn(II)-L-malate binding and subunit interactions of pigeon liver malic enzyme

Pigeon liver malic enzyme has an N-terminal amino acid sequence of Met-Lys-Lys-Gly-Tyr-Glu-. In this work, various mutants of the enzyme with individual or combinational deletion (delta) or substitution at these amino acids were constructed and functionally expressed in Escherichia coli cells. A major protein band corresponding to an Mr of approximately 65000 was observed for all recombinant enzymes in sodium dodecyl sulfate polyacrylamide gel electrophoresis. However, when examining by polyacrylamide gel electrophoresis under native conditions, the recombinant enzymes were found to possess a tetrameric structure with Mr approximately 260000 or a mixture of tetramers and dimers with the exception of delta(K2K3G4) and delta(1-16) mutants, which existed exclusively as dimers at the protein concentration we employed. K3A and K3E also dissociated substantially. K(2,3)A was a tetramer but K(2,3)E essentially existed as dimers. All tetramers and dimers were enzymatically active in the gels. All mutants displayed a similar apparent Km value for NADP+. The apparent Km for L-malate and Mn(II), on the other hand, was increased by 4-27-fold for the delta(K2/K3) and the delta(1-16) mutants. The small binding affinity of delta(K2/K3) with Mn(II)-L-malate was specific. With additional deletion at positions 3 and/or 4, the delta(K2K3), delta(K2G4/K3G4) or delta(K2K3G4) mutants exhibited similar kinetic properties for the wild type. The lysine residues at the positions 2 or 3 seem to be crucial for the correct active site conformation. The results indicate that the N-terminus of malic enzyme is located at the Mn(II)-L-malate binding domain of the active center and is also near the subunit's interface. These results were interpreted with our asymmetric double-dimer model for the enzyme in which the N-terminus was involved in the head-to-tail monomer-monomer interactions but not the dimer-dimer interactions.

[Clinical report of 60 cases of diabetic cardio-vascular autonomous neuropathy by stasis removing treatment of combined traditional and Western medicine]

OBJECTIVE

To study the treatment of diabetic cardio-vascular autonomous neuropathy (DCVAN) by TCM-WM following the principle of promoting blood circulation to remove blood stasis.

METHODS

Sixty patients with DCVAN were randomly divided into two groups, the treatment group (30 patients) were treated with combined TCM-WM therapy. Based on the control of blood sugar by WM effectively, then use TCM-Tangxinshen ([symbol: see text], TXS) with the function of supplementing the Qi and nourishing Yin, promoting blood circulation to remove blood stasis. Thirty cases of the control group were treated with WM alone. The course of treatment was three months.

RESULTS

The total effective rate of the treatment group and the control group was 77.3% and 33.4% respectively, which were significantly different statistically (P < 0.005).

CONCLUSION

The therapeutic effect of TCM-WM was better than that of WM.

Intestinal obstruction after laparoscopic herniorrhaphy

Laparoscopic herniorrhaphy is still a controversial procedure. Two cases of intestinal obstruction after laparoscopic herniorrhaphy are reported. The clinical features, possible mechanisms, managements, and outcomes were analyzed. The results showed that preexisting mesenteric defect, fibrin depositions, and longer operation time were predisposing factors for post-laparoscopic herniorrhaphy intestinal obstruction. These findings suggest that cleansing of fibrin deposition and shorter operation times may be important to avoid postoperative intestinal obstruction.

Bezoar manifested with digestive and biliary obstruction

BACKGROUND/AIMS

Gastrointestinal obstructions caused by bezoars are uncommon but are encountered with increasing frequency in general surgery.

METHODOLOGY

We made a retrospective review of 30 cases treated in the National Cheng Kung University hospital between July 1988 and December 1994.

RESULTS

Fourteen patients had either prior gastric surgery (9) or peptic ulcer disease (5) and were categorized as group I. The remaining 16 patients without above conditions were categorized as group II; and seven of them had history of ingestion of Pho Pu Zi (Cordia dichotoma Frost. f.), three had food bolus ingestion, two had diverticulum, two had adhesion and the remaining two had no significant features. Two patients, who received endoscopic removal of gastric bezoar and subsequently developed bowel obstruction, needed operation. Sixteen of 30 who underwent operation within 24 hours after arrival, recuperated uneventfully and most were discharged within a week. Eleven patients who received operation after 24 hours resulted in prolonged hospitalization in 9 and death in two. Re-operation was performed in one case for the recurrence of obstruction by the residual bezoar.

CONCLUSION

Dietary factors (Pho Pu Zi or bolus ingestion), and gastrointestinal (GI) anatomical lesion (diverticulum or adhesion) are the profound etiologies for formation of bezoars in cases without previous gastric surgery. On the other hand, gastric factors (previous ulcer surgery or peptic ulcer) play a major role even after ingestion of nonspecific high fiber diet. Early diagnosis, surgical intervention without delay and thorough exploration of the entire GI tract are essential for good postoperative results.

Prenatal molecular diagnosis of RET proto-oncogene mutation in multiple endocrine neoplasia type 2A

We report a case of multiple endocrine neoplasia type 2A (MEN 2A) diagnosed prenatally at 16 weeks gestation. The 35-year-old mother is a MEN 2A patient. She had had three prior pregnancies: one resulted in a stillbirth; one produced a genetically unaffected boy; and the third was terminated in the first trimester owing to a diagnosis of blighted ovum. Autopsy did not reveal the cause of death of the stillborn infant, who was also found to be affected with MEN 2A by molecular study of paraffin-embedded tissue. Because of poor obstetric history and the patient's age, amniocentesis for cytogenetic and molecular studies was performed at 16 weeks' gestation during the pregnancy under discussion. As with other affected members in the mother's family, the missense mutation of TGC to TTC at codon 634 of the RET proto-oncogene was found in amniotic fluid cells. Analysis of DNA extracted from the lymphocytes of the infant's blood at birth confirmed the diagnosis. To our knowledge, this is the first report of prenatal diagnosis of MEN 2A.

Implications of serum basic fibroblast growth factor levels in chronic liver diseases and hepatocellular carcinoma

Angiogenesis occurs in response to tissue damage, and is of vital importance for tumor growth and metastasis. Basic fibroblast growth factor (bFGF), a well-known angiogenic factor, has been suggested to be a useful diagnostic marker in certain hypervascular tumors. However, the relevance of its detection has not been well evaluated in patients with hepatocellular carcinoma (HCC) and benign chronic liver diseases. In the current study, immunoassay of bFGF was performed on serum samples from 39 patients with HCC, 21 with liver cirrhosis, 22 with chronic hepatitis and 40 normal subjects. The serum bFGF level was significantly increased in patients with liver cirrhosis and HCC when compared with those with chronic hepatitis or normal subjects (all p-values < 0.001). However, no difference was observed between the groups with liver cirrhosis and HCC (p > 0.05). If we set 9.6 pg/ml (mean + 3 standard deviations of bFGF in the control group) as the upper limit of normal serum level of bFGF, elevated bFGF concentrations were noted in 9.1%, 42.9% and 51.3% of patients with chronic hepatitis, liver cirrhosis and HCC respectively. In non-cancer patients, the coexistence of acute illness (p = 0.000) was an independent factor related to the elevation of serum bFGF. On the other hand, a multivariate analysis demonstrated that both advanced stage of cancer (p = 0.026) and coexistence of acute illness (p = 0.000) influence the serum level of bFGF in patients with HCC. We conclude that serum bFGF levels are significantly higher in patients with HCC and are positively correlated with advanced tumor stage. Nevertheless, elevation of serum bFGF may also be observed in a significant number of patients with liver cirrhosis. Therefore, measurement of serum bFGF alone cannot be satisfactory as a tumor marker for diagnosis of HCC. In addition, it is important to point out that coexistence of acute illness may be a crucial confounding factor in the diagnosis or monitoring of any cancer by the estimation of serum bFGF.

Expression of vascular endothelial growth factor in normal liver and hepatocellular carcinoma: an immunohistochemical study

Angiogenesis is of vital importance during the development and progression of solid tumors. To examine the role of vascular endothelial growth factor (VEGF) in hepatocarcinogenesis, we evaluated the expression of peptide in normal human liver (n = 6) and in 36 cases of hepatocellular carcinoma (HCC). Immunoreactivity for VEGF was present in the extracellular matrix of the portal tracts in the normal and nontumor part of liver, but not in hepatocytes and bile duct epithelium. For HCC, variable amounts of VEGF were expressed in 13 cases (36.1%) of tumor cells. Using a logistic regression model, expression of VEGF was significantly associated with a higher proliferative index (P = .01) and sonographic portal vein thrombosis (P = .05). However, VEGF expression did not correlate with a biochemical liver profile, alpha-fetoprotein levels, histological grading, gender, or clinical stage of cirrhosis (P > 0.1, respectively). Log-rank test showed that evaluation of VEGF did not provide more prognostic information (P > .5) than that from tumor volume and portal vein thrombosis (P < .01, respectively). In addition, VEGF was always present in the fibrovascular stroma or pericellular matrix of HCC, although no strong relationship was observed with the expression of VEGF in tumor cells (P > .5). Our data suggested that expression of VEGF may characterize a progression toward higher proliferation in hepatocarcinogenesis in vivo. The relevance of VEGF existing in the extracellular matrix of the normal liver and HCC remains to be clarified.

High dose chemotherapy with peripheral blood stem cells transplantation in patients with relapsed or refractory lymphomas preliminary reports

High dose chemotherapy with peripheral blood stem cells transplantation (PBSCT) has been used worldwide in the treatment of patients with various hematological malignancies and other solid tumors. It has just come into use as a salvage therapy in various malignancies in Taiwan in recent years. We report eight cases with relapsed or refractory lymphoma treated with high dose chemotherapy and PBSCT. Our results showed all cases but one achieved complete remission. The mean days of white cell recovery were 10 days to > 500/microliter (ranges, 8-16 days) and 12 days to > 1,000/microliter (ranges, 9-19 days). The mean days to platelet transfusion independent, i.e. platelet > 20,000/microliters, was 14 days. No specific side effect was noted except death in one case on D+9 during cytopenia state. Four patients relapsed and died during the follow-up after PBSCT. From our preliminary results we suggest that high dose chemotherapy with PBSCT could be used as a salvage therapy in patients with relapsed or refractory lymphomas with favorable and sustained hematological recovery. Most cases were tolerable with myeloablative chemotherapy and re-achieved remission, however, remission duration was still short and relapse remained the main problem to be overcome. The long term effects of high dose chemotherapy with PBSCT still need further study.

Cardiac and glycemic benefits of troglitazone treatment in NIDDM. The Troglitazone Study Group

Troglitazone is a thiazolidinedione under development for the treatment of NIDDM and potentially other insulin-resistant disease states. Treatment with troglitazone is associated with an improvement in hyperglycemia, hyperinsulinemia, and insulin-mediated glucose disposal. No significant side effects have been observed in humans. Because of reported cardiac changes in animals treated with drugs of this class, this multicenter 48-week study was conducted to evaluate whether NIDDM patients treated with troglitazone develop any cardiac mass increase or functional impairment. A total of 154 NIDDM patients were randomized to receive troglitazone 800 mg q.d. or glyburide titrated to achieve glycemic control (< or =20 mg b.i.d. or q.d.). Two-dimensional echocardiography and pulsed Doppler were used to measure left ventricular mass index (LVMI), cardiac index (CI), and stroke volume index (SVI). All echocardiograms were performed at each center (baseline, 12, 24, 36, and 48 weeks), recorded on videotape, and forwarded to a blinded central echocardiographic interpreter for analysis. The results showed that LVMI of patients treated with troglitazone was not statistically or clinically different from baseline after 24 or 48 weeks. Statistically significant increases in SVI and CI and a statistically significant decrease in diastolic pressure and estimated peripheral resistance were observed in troglitazone-treated patients. These results were not sex-specific. Glycemic benefits of troglitazone treatment were observed as evidenced by long-term improvement of HbA1c and C-peptide levels. Furthermore, triglycerides were significantly lower, and HDL was significantly higher at weeks 24 and 48. In conclusion, NIDDM patients treated with troglitazone do not show any cardiac mass increase or cardiac function impairment. Conversely, patients on troglitazone benefited from enhanced cardiac output and stroke volume, possibly as a result of decreased peripheral resistance. Treatment with troglitazone appears to have a favorable impact on known cardiovascular risk factors and could potentially lower cardiovascular morbidity in NIDDM patients.

Comparison of intravenous granisetron with metoclopramide plus dexamethasone in the prevention of nausea and vomiting associated with emetogenic cytotoxic chemotherapy

Fifty-one patients who received their first course of chemotherapy were studied to compare the respective efficacy and safety of granisetron and metoclopramide plus dexamethasone in the prevention of nausea and vomiting induced by emetogenic cytotoxic drugs. The results showed the response rate of antiemesis in the first 24 hours was higher in the metoclopramide plus dexamethasone group than in the granisetron group: 95% vs 84%. For the next six days of the study period, the response rate of the granisetron group was shown to be more effective than that of metoclopramide plus dexamethasone group: 77% vs 60%. Furthermore, the granisetron seemed to display enhanced tolerability with less drug-related side effects and no extrapyramidal effects which appeared in 2 cases of the metoclopramide plus dexamethasone group. In conclusion, a single dose of granisetron can be as effective as the gold standard of metoclopramide plus dexamethasone regimen in preventing and treating acute nausea and vomiting. For preventing delayed nausea and vomiting, granisetron is shown to be more effective than metoclopramide plus dexamethasone.

Familial hyperparathyroidism without multiple endocrine neoplasia

Hyperparathyroidism occurs sporadically, in association with multiple endocrine neoplasia (MEN) types I and II, or rarely as familial hyperparathyroidism (FHPT) without other manifestations. We analyzed our experience in 16 FHPT patients from 14 families treated between 1934 and 1991 and reviewed 51 other FHPT patients reported in the literature to determine the clinical course of these patients. Among our 16 patients, 7 (44%) had a serum calcium level >/= 3.75 mmol/L, 5 (31%) presented with hypercalcemic crisis, 3 (19%) had osteitis fibrosa cystica, 5 (31%) had nephrolithiasis, 1 had pancreatitis, 12 (75%) had multiple abnormal parathyroid glands, 3 (19%) had supernumerary glands, and 7 (44%) required reoperation for persistent (n = 4) or recurrent (n = 3) hyperparathyroidism. Three patients (19%) also had papillary thyroid cancer, and 7 (44%) had other coexistent thyroid disorders. Among 51 patients with FHPT reported in the literature, 23 (45%) had serum calcium >/= 3.75 mmol/L, and 23 (45%) had multiple abnormal parathyroid glands; 10 (20%) had recurrent hyperparathyroidism. FHPT without other endocrinopathies is a distinct entity. Patients with FHPT have multiple abnormal parathyroid glands and are prone to both recurrent and persistent hyperparathyroidism. They frequently present with profound hypercalcemia or hypercalcemic crisis, in contrast to patients with MEN-associated hyperparathyroidism or sporadic hyperparathyroidism.

Effect of thyroid hormone on urinary excretion of epidermal growth factor

Thyroid hormones were demonstrated to upregulate the synthesis of epidermal growth factor (EGF) mRNA and proEGF in the kidneys in vivo. This prospective study was performed to examine the extent of the hypothyroid state in modulating EGF excretion in the urine (U-EGF; n = 23). Patients with thyroid cancer were serially followed up from the euthyroid status, which was retained by thyroxine supplement after thyroidectomy, to the hypothyroidism in preparing for 131I whole body scanning. Paired thyroid function panel, including triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), and U-EGF levels were measured on a weekly basis. Logarithmically transformed values of U-EGF were inversely correlated with TSH serum levels (p = 0.0000), but positively associated with T4 levels (p = 0.0005). No apparent correlation was observed with the T3 serum content, age and gender of the patients (p > 0.1, respectively). If the interval of measurement was taken into consideration, serum TSH was the most significant factor in association with U-EGF (p = 0.0003). Our data indicate that excretion of EGF in human urine depends substantially upon thyroid hormone support.

A prospective randomised study of laparoscopic v. open cholecystectomy in aged patients with cholecystolithiasis

Between August 1992 and July 1993, 27 patients aged 70 years of older with cholelithiasis were prospectively randomised into 2 groups. Fifteen patients underwent laparoscopic cholecystectomy and 12 patients underwent open cholecystectomy. Shorter operation time (93.3 +/- 25.3 minutes v. 176.3 +/- 26.1 minutes, P < 0.00001), fewer postoperative analgesic requirements (0.53 +/- 0.52 days v. 2.00 +/- 0.74 days, P < 0.00001), shorter postoperative hospital stay (3.93 +/- 1.71 days v. 7.92 +/- 0.79 days, P < 0.00001) and better cosmesis were found in the laparoscopic cholecystectomy group. The above data suggest that laparoscopic cholecystectomy is the treatment of choice for cholecystolithiasis in elderly patients.

Surgical resection of primary hepatocellular carcinoma extending to adjacent organ(s)

Primary hepatocellular carcinoma (HCC) extending to the adjacent organ(s) is sometimes encountered in patients with large, peripherally located tumours. Over a 4-year period, a total of 151 patients received curative resection of HCC at the Surgical Department of Veterans General Hospital-Taipei, Taiwan. Of these patients, 21 underwent hepatic resection combined with en-bloc resection of the adjacent organ(s) because tumour extension was found during operation. Subsequent histological examination of the resected specimens found evidence of HCC invasion into the resected adjacent organ(s) in only nine patients (group I), and the remaining 12 patients showed no evidence of extrahepatic HCC invasion (group II). Twenty-seven HCC patients with clinico-pathologically matched tumours but without extrahepatic extension were selected as controls (group III). One patient in group I died of hepatic failure after the operation. The morbidity rate was 48% in group I and group II patients, and 30% in group III patients. The difference was not statistically significant. On evaluating the clinico-pathological factors, including DNA ploidy status of the tumours, there were no significant differences between tumours with and without extrahepatic invasion. Patients with locally invasive HCC (group I) had disease-free and overall survival rates comparable with those of the patients without local tumour invasion (group II and III). We conclude that HCC with invasion to the adjacent organ(s) does not seem to be directly related to the 'aggressiveness' of the tumour, and extrahepatic infiltration of the tumour does not preclude a chance of cure. Our results underscore the need for en-bloc resection as treatment of choice for these patients.

ACAT inhibitors derived from hetero-Diels-Alder cycloadducts of thioaldehydes

Acyl-CoA:cholesterol acyltransferase (ACAT) is the enzyme largely responsible for intracellular cholesterol esterification. A systemic inhibitor of ACAT is believed to be able to slow or even reverse the atherosclerotic process. Towards that goal, a series of cyclic sulfides, derived from the hetero-Diels-Alder reaction of thioaldehydes with 1,3-dienes, and bearing carboxamide substituents, were prepared and evaluated for in vitro (in several tissues and species) and ex vivo ACAT inhibition. Minor changes in subsequent structure were found to have a significant effect in optimization of the biological activity of this series of compounds.

Involvement of Phe19 in the Mn(2+)-L-malate binding and the subunit interactions of pigeon liver malic enzyme

A triple mutant, F19S/N250S/L353Q, of pigeon liver malic enzyme was found to have no detectable enzymatic activity [Chou, W.-Y., Huang, S.-M., & Chang, G.-G. (1994) Arch. Biochem. Biophys. 310, 158-166]. In the present study, point mutants at these positions (F19S, N250S, and L353Q) were prepared by site-directed mutagenesis. Both N250S and L353Q have kinetic properties similar to those of the wild-type. On the other hand, the K(m)(app) values for both Mn2+ and L-malate of F19S were increased by approximately 10-fold, while the kcat value was decreased by 5-fold, which results in a decrease of the apparent catalytic efficiency (kcat/K(mNADP)K(mMal)K(mMn) by approximately 300-fold. These results clearly indicate that the F19S mutation is mainly responsible for the undetectable enzyme activity of the triple mutant. Three more Phe19 mutants (F19Y, F19G, and F19A) were then prepared. There is a direct correlation between the size of the substitutes and the affinities for Mn2+ and L-malate. The kinetic parameters for F19Y were similar to those for wild-type. Both F19A and F19G reveal a 5-fold decrease of kcat values. Two K(dMn) values for the high- and low-affinity sites, respectively, were detectable for the wild-type. On the contrary, only one K(dMn) value was detected for the F19 mutants, which was increased in the order of F19G > F19A > F19S > F19Y, with F19G being the most affected mutant. The K(mMal) values of F19G and F19A were increased 100- and 6-fold, respectively. The catalytic efficiency (kcat/K(mNADP)K(dMal)K(dMn)) of F19G was decreased to only 0.01% of that of the wild-type. The above results clearly indicate that the hydrophobic aromatic ring at position 19 plays a critical role in L-malate and Mn2+ binding. Furthermore, all mutants that have a small residue at position 19 exist as monomers. Therefore, Phe19 may locate in or near the regions for Mn(2+)-L-malate binding as well as for the subunit contact. These results are compatible with the asymmetric model for the quaternary structure of malic enzyme we proposed previously [Chang, G.-G., Huang, T.-M., Huang, S.-M., & Chou, W.-Y. (1994) Eur. J. Biochem. 225, 1021-1027]. The possible roles of the N-terminus of malic enzyme were also addressed.

Transverse abdominis musculo-peritoneal (TRAMP) flap for the repair of large duodenal defects

Definitive surgical management of major acute injuries to the second and third portions of the duodenum has been enigmatic. Sometimes, the defect is so large that it is unwise to do primary repair, and resection at this critical portion of the intestinal tract is technically hazardous or impossible. A serosal or mucosal patch technique has been used to repair this kind of duodenal defect with encouraging results. Since the use of this technique has proved effective, such a defect was not necessarily treated with the more complicated pancreaticoduodenectomy and was managed with less morbidity and mortality. But these techniques are still controversial. So, we tried a pedicle flap, called the transverse abdominis musculo-peritoneal (TRAMP) flap, for repair of large duodenal defect. We have used this flap in 25 rabbits, and the specimens were followed up to a period of 3 months. The flap showed satisfactory results and is presented as another option for repair of large duodenal defects.

An alternative approach of choledocholithotomy via laparoscopic choledochotomy

OBJECTIVE

To evaluate the safety and feasibility of laparoscopic choledocholithotomy via choledochotomy for the treatment of choledocholithiasis.

DESIGN

A prospective series of 1332 consecutive patients who underwent laparoscopic cholecystectomies, with a mean follow-up of 21.2 months.

SETTING

University-affiliated referral center.

PATIENTS

Forty-three patients (3%) with documented common bile duct stones from January 1991 to February 1995.

INTERVENTIONS

Laparoscopic choledocholithotomy with choledochotomy and T tube drainage were performed in 40 patients. Postoperative endoscopic sphincterotomy after laparoscopic cholecystectomy was performed in three patients.

MAIN OUTCOME MEASURES

Documented removal of common bile duct stones and procedure-related complications.

RESULTS

Laparoscopic choledocholithotomy via choledochotomy was successful in 35 (88%) of 40 patients in whom this procedure was attempted. The mean (+/- SD) operation time was 191.3 +/- 75.4 minutes, and the mean (+/- SD) length of postoperative stay was 10.4 +/- 2.7 days. Seven complications (18%) were recorded, including three major complications (8%) and two retained stones (5%).

CONCLUSIONS

Laparoscopic choledocholithotomy via choledochotomy can be performed safely, without increasing the morbidity rate as compared with that of open choledocholithotomy. Thus, some of the advantages of minimally invasive surgery are preserved.