The immobilization of mitochondrial malate dehydrogenase on Sepharose beads and the demonstration of catalytically active subunits

Porcine heart mitochondrial malate dehydrogenase (L-malate:NAD+ oxidoreductase, EC 1.1.1.37) has been immobilized by covalent attachment to CNBr-activated Sepharose 4B-Cl gel. The gel was activated with low levels of CNBr to produce a low density of linkage sites and, hence, to facilitate linkage of the enzyme through a single subunit. Matrix-bound mitochondrial malate dehydrogenase was found to possess 50-65% of the native mitochondrial malate dehydrogenase specific activity when assayed in the NAD+ leads to NADH direction but only 5-15% of the native enzyme specific activity when assayed in the NADH leads to NAD+ direction. MB-dimeric mitochondrial malate dehydrogenase was dissociated to MB-monomer by exposure to pH 5.0 buffer. The MB-monomer was found to be catalytically active, possessing only a slightly decreased specific activity when compared to MB-dimer. The reconstitution of Mb-monomer to MB-dimer was accomplished by adding dissociated mitochondrial malate dehydrogenase, which exists at pH 5.0, to MB-monomer and adjusting to pH 7.5. The kinetic parameters, pH activity profile, and stability toward heat denaturation for MB-mitochondrial malate dehydrogenase (monomer and dimer) were determined and compared to native mitochondrial malate dehydrogenase. MB-mitochondrial malate dehydrogenase exhibited enhanced stability and similar pH activity profiles when compared to native mitochondrial malate dehydrogenase. Immobilization of mitochondrial malate dehydrogenase altered the enzyme's kinetic parameters in such a manner as to increase the values of Km for the substrates and decrease the values of Vmax.

Mini-pump: method of diabetic control during minor surgery under general anaesthesia

A simple method for maintaining diabetic control during and after minor surgery requiring a general anaesthetic was studied in 20 insulin-treated diabetics. Long-acting insulin was omitted on the night before the operation, and a mini-pump delivering insulin at a rate of 0.5 units/h was strapped to the arm early on the morning of the operation regardless of the time of operation. Insulin was infused at this rate throughout the day, the usual evening dose of insulin given and followed by supper, and the pump then stopped. In all 20 patients studied blood glucose concentrations fell steadily throughout the day. Hypoglycaemia did not occur. The mini-pump is simple to use and with the same standard insulin dose for all patients maintains satisfactory blood glucose concentrations throughout the day of operation.

Frog lysozyme. V. Isolation and some physical and immunochemical properties of lysozyme isozymes of the leopard frog, Rana pipiens

Frog Lysozyme has been purified by sequential application of acid extraction, salt fractionation, CM-cellulose chromatography, heat treatment, and gel filtration. Eight isozymes of purified lysozyme were found to be stable during prolonged storage. Isozymes were separated by preparative polyacrylamide gel electrophoresis, Ninety percent of the lytic activity of frog ovarian egg was represented by forms 7 and 8, the most highly charged isozymes. Seventy-eight percent of frog liver lysozyme activity was that of form 4. Forms 7 and 8 differed from form 4 by being larger (apparent molecular weight of 18,000 vs. 16,000), by remaining active in more acidic environment, and by exhibiting a dependency upon NaCl for activity. Antiserum prepared against frog form 4 did not react with frog forms 7 and 8 and antiserum to chicken egg-white lysozyme did not react with any frog lysozymes. All frog lysozymes showed identical reversible binding to deaminated chitin. Apparent size differences and lack of immunological cross-reactivity suggest that at least some of the isozymes are non-allelic.

Investigation of the relation of the pH-dependent dissociation of malate dehydrogenase to modification of the enzyme by N-ethylmaleimide

The pH-dependent dissociation of porcine heart mitochondrial malate dehydrogenase (L-malate:NAD+ oxidoreductase, EC 1.1.1.37) has been further characterized using the technique of sedimentation velocity ultracentrifugation. The increased rate and specificity of the inactivation of mitochondrial malate dehydrogenase by the sulfhydryl reagent N-ethylmaleimide has been correlated with the pH-dependent dissociation of the enzyme. Data obtained using NAD+ and its component parts to reassociate the enzyme and also to protect the enzyme from inactivation by N-ethylmaleimide suggest that the sulfhydryl residues being modified by N-ethylmaleimide are inaccessible when the enzyme is in its dimeric form. A dissociation curve for the pH-dependent dissociation suggests that a limited number of residues are being protonated concomitant with dissociation of the enzyme. An apparent pKa of 5.3 has been determined for this phenomenon. Studies using enzyme modified by the sulfhydryl reagent N-ethylmaleimide indicate that selective modification of essential sulfhydryl residues alters the proper binding of NADH.

Functioning and nonfunctioning cysts of the adrenal cortex and medulla

Adrenal cysts are rare clinical and pathologic entities. The vast majority are minute in size, unilateral, and found in females at autopsy. They come to the physician's attention when they produce symptoms or are identified on x-ray studies. When symptomatic, they generally produce lumbar discomfort and gastrointestinal symptoms, and occasionally are palpable by abdominal examination. There is no significant agreement as to cause and pathogenesis of the disease. The most common histologic types are lymphangiomatous endothelial cysts, secondary to lymphangiectasis, and the fibrous wall or hemorrhagic pseudocysts. In many patients preoperative diagnosis is now possible with high quality nephrotomography, ultrasonography, and adrenal arteriography. The presence of a suprarenal mass with peripheral or laminar calcification strongly suggests the presence of an adrenal pseudocyst. Selective biochemical studies are mandatory to rule out the presence of an occult cystic pheochromocytoma, and adrenal cortical tumor. Adrenal cysts must be differentiated from all space-occupying lesions of the upper abdomen. Surgical exploration is recommended in almost all patients for accurate diagnosis and to rule out malignant disease or occult pheochromocytoma. The choice of the surgical approach should be planned to provide for safe and adequate exposure, depending on the size and location of the lesion. Careful dissection with preservation of the adjacent kidney, liver, and pancreas should be performed.

Malignant pheochromocytoma: clinical course and treatment

We describe 7 patients with 16 malignant pheochromocytomas, with followup for 7 to 21 years. Five patients are free of disease at a mean of 13.5 years and 2 patients died of malignancy at 10 and 13 years. The 3 criteria believed important for a maximum tumor-free interval are: 1) adjunctive lymphadenectomy at the initial operation when 1 or more lymph nodes contain tumor, 2) close followup of all patients with pheochromocytoma by diagnostic biochemical assay for 15 years and 3) an aggressive excision of all single or multiple recurrent pheochromocytomas as soon as a biochemical diagnosis is established.

The familial liver donor in renal transplantation

A survey is made of the 20-year experience with more than 300 living donors in renal transplantation at the Peter Bent Brigham Hospital. Details are given pertaining to the first transplantation of the kidney from one living person to another in December 1954. The surgical technique, the complications and the results of renal transplantation from a living donor are summarized. The philosophic and psychologic problems encountered are described. A comparison of results summarized by Murray of living, related donor transplants to cadaveric donor transplants is included. This paper constitutes a salute to the familial living donor.

Investigation of the subunit interactions in malate dehydrogenase

The dissociations of porcine heart mitochondrial, bovine heart mitochondrial, and porcine heart cytoplasmic malate dehydrogenase dimers (L-malate: NAD+oxidoreductase, EC 1.1.1.37) have been examined by Sephadex G-100 gel filtration chromatography and sedimentation velocity ultracentrifugation. The porcine mitochondrial enzyme was found to chromatograph as subunits when applied to a gel filtration column at a concentration of .02 muM or less at pH 7.0. The presence of coenzymes shifted the dissociation equilibrium at low enzyme concentrations in favor of dimer formation. Monomer formation was also favored when procine mitochondrial enzyme was incubated at pH 5.0 even at concentrations as high as 120 muM. This shift in equilibrium has been correlated with the increased rate and specificity of sulfhydryl residue modification with N-ethylmaleimide at pH 5.0 (Gregory, E.M., Yost, F.J.,Jr., Rohrbach, M.S., and Harrison, J.H. (1971)J. Biol. Chem. 246, 5491-5497). Bovine mitochondrial enzyme did not exhibit a concentration-dependent disociation under the conditions examined. However, at pH5.0 monomer formation was favored, and correlations could again be drawn with sulfhydryl residue modification (Gregory, E.M. (1975)J.Biol. Chem. 250, 5470-5474). In both mitochondrial enzymes, coenzyme binding was found capable of overcoming the effects of pH on the dissociation equilibrium, and dimer formation was favored. Unlike either of the above mentioned enzymes, porcine cytoplasmic malate dehydrogenase did not dissociate into its monomeric form under any conditions investigated.

Inactivation of porcine heart cytoplasmic malate dehydrogenase by pyridoxal 5'-phosphate

Pyridoxal 5'-phosphate (pyridoxal-5'-P) has been found to act as a bifunctional reagent during the inactivation of porcine heart cytoplasmic malate dehydrogenase (L-malate: NAD+ oxidoreductase, EC 1.1.1.37). The biphasic kinetics and X-azolidine-like structure formed were similar to those observed for mitochondrial malate dehydrogenase (Wimmer, M.J., Mo, T., Sawyers, D.L., and Harrison, J.H. (1975) J. Biol. Chem. 250, 710-715). In the cytoplasmic enzyme, however, irreversible inactivation representing X-azolidine formation was found to be the dominant characteristic of the interaction with pyridoxal-5'-P. Spectral evidence indicated that at total inactivation 2 mol of pyridoxal-5'-P were incorporated per mol of enzyme or one pyridoxal-5'-P per enzymatic active site. The presence of NADH protected the enzyme from inactivation suggesting interaction of pyridoxal-5'-P at or near the enzymatic active centers of this enzyme. Fluorometric titrations indicated that pyridoxal-5'-P-inactivated enzyme failed to bind NADH or at least failed to bind NADH in the same fashion as native enzyme.

Coagulum pyelolithotomy using autogenous plasma a and bovine thrombin

Herein we describe a technique in which the patient's own plasma was used to form an intrapelvic clot, thus aiding in the removal of calculi lying loose in the renal pelvis or infundibula.

Venacavography, corticosteroids and surgery in the management of idiopathic retroperitoneal fibrosis

Four patients with idiopathic retroperitoneal fibrosis were found to have characteristic obstruction and anterior displacement of the lumbar vena cava. Varying degrees of venous collateral circulation were present, depending on the degree of vena caval compression. All 4 patients underwent ureterolysis to relieve the hydronephrosis and to confirm diagnosis by biopsy. Two patients were treated with corticosteroids postoperatively. Followup venacavography demonstrated improved filling and decrease in the collateral circulation in these 2 patients. Of the remaining 2 untreated patients 1 was lost to followup and the other revealed no change. Diagnosis of idiopathic retroperitoneal fibrosis can be made if characteristic changes are present on inferior venacavography and may provide an objective measure for following the basic disease process during medical treatment.

Identification of an essential lysine in porcine heart mitochondrial malate dehydrogenase

The reversible inactivation of porcine heart mitochondrial malate dehydrogenase by pyridoxal 5'-phosphate yields an irreversible modification upon sodium borohydride reduction. A 200-fold molar excess of pyridoxal-5'-P over enzyme results in inactivation to the extent of 54%, and incorporation of 5.7 mol of inactivator per mol of enzyme. The same inactivation carried out in the presence of 80 mM coenzyme, NADH, produces malate dehydrogenase which is approximately 94% active and contains 4.6 mol of pyridoxal-5'-P per mol of enzyme. The incorporation difference between inactivated and protected samples suggests, for total inactivation, the modification of 2 residues per mol of enzyme (i.e. 1 residue per subunit, or 1 per enzymatic active site). This specificity was confirmed by the isolation of a single pyridoxyl-5'-P-labeled "difference peptide" obtained by comparison of the Dowex 1-X2 elution profiles of tryptic digests of protected and inactivated samples, respectively. Amino acid analysis of the peptide demonstrated the presence of N6-pyridoxyl-L-lysine (Lys(Pyx)), establishing the existence of an essential lysing residue in the active center of malate dehydrogenase. The amino acid sequence of the active center hexapeptide has been determined to be: H2NLys(Pyx)Pro-Gly-Met-Thr-Arg-COOH.

Renal cell carcinoma: natural history and chemotherapeutic experience

Eght-four patients with renal cell carcinoma were analyzed retrospectively in order to 1) determine the effectiveness of systemic chemotherapy-hormonal and non-hormmonal, 2) identify the clinical features of renal cell carcinoma that may be important in prognosis and 3) characterize the paraneoplastic features of renal cell carcinoma. Metastatic disease was present at diagnosis in 57 per cent of the cases and developed within 1 year in an additional 19 per cent of the cases were paradoxically associated with a longer survival (20 months median) compared to single-organ metastasis (5 to 11 months median). Paraneoplastic syndromes occurred in up to 40 per cent of patients with variable survival. Metastatic disease was unresponsive objectively to either primary nephrectomy or to a variety of chemotherapy trials.

Identification of essential arginyl residues in cytoplasmic malate dehydrogenase with butanedione

The inactivation of cytoplasmic malate dehydrogenase (L-malate: NAD+ oxidoreductase, EC 1.1.1.37) from porcine heart and the specific modification of arginyl residues have been found to occur when the enzyme is inhibited with the reagent butanedione in sodium borate buffer. The inactivation of the enzyme was found to follow pseudo-first order kinetics. This loss of enzymatic activity was concomitant with the modification of 4 arginyl residues per molecule of enzyme. All 4 residues could be made inaccessible to modification when a malate dehydrogenase-NADH-hydroxymalonate ternary complex was formed. Only 2 of the residues were protected by NADH alone and appear to be essential. Studies of the butanedione inactivation in sodium phosphate buffer and of reactivation of enzymatic activity, upon the removal of excess butanedione and borate, support the role of borate ion stabilization in the inactivation mechanism previously reported by Riordan (Riordan, J.F. (1970) Fed. Proc. 29, Abstr. 462; Riordan, J.F. (1973) Biochemistry 12, 3915-3923). Protection from inactivation was also provided by the competitive inhibitor AMP, while nicotinamide exhibited no effect. Such results suggest that the AMP moiety of the NADH molecule is of major importance in the ability of NADH to protect the enzyme. When fluorescence titrations were used to monitor the ability of cytoplasmic malate dehydrogenase to form a binary complex with NADH and to form a ternary complex with NADH and hydroxymalonate, only the formation of ternary complex seemed to be effected by arginine modification.

Post-diversion pre-cystectomy irradiation for carcinoma of the bladder

In 47 patients treated sequentially with urinary diversion and laparotomy staging, irradiation therapy and total cystectomy for invasive carcinoma of the bladder, the mortality rate was 2 per cent and the complication rate was 20 per cent. The survival rate was most favorable in patients in whom the pathologic specimen revealed no tumor after irradiation. The lower mortality and morbidity rates are attributed to staging of surgical procedures and the challenge remains to increase the number of patients in whom carcinoma of the bladder is converted by irradiation therapy to a lower stage or no tumor.