Clinical evaluation of an automated chemical inhibition assay for lactate dehydrogenase isoenzyme 1

We evaluated an automated assay for lactate dehydrogenase (LD; EC 1.1.1.27) isoenzymes, supplied by Boehringer Mannheim Diagnostics (BMD) and based on selective chemical inhibition of non-LD-1 isoenzymes by guanidine thiocyanate. Results were compared with the Roche Isomune LD-1 method. The Hitachi 717 analyzer was used to measure enzyme activity for both procedures in 229 serum samples. One hundred specimens were also analyzed by the Helena rapid electrophoresis (REP) method. We determined the limit of linearity of the BMD method to be about 1200 U of LD-1 per liter. The analytical correlation of BMD (y) with Isomune (x) yielded y = 1.0x + 0.5 U/L, r = 0.997, Sy/x = 16.9 (range 20-1397 U/L). The regression equation for BMD vs REP was y = 1.1x + 7.2% (r = 0.800, Sy/x = 7.4, range 14-83%). Average values for within-run precision for low (38 U/L), medium (180 U/L), and high (865 U/L) controls were 4.1%, 1.0%, and 0.5%, respectively (16 trials of six each). The average values for run-to-run precision were 4.1%, 1.7%, and 1.1%, respectively, for these controls (n = 16). We used receiver-operating characteristic curves to determine optimum decision limits. Using an LD-1 cutoff of 40% of total LD, we obtained a clinical sensitivity of 97-100% and a specificity of 95% when blood was collected during the optimum interval, 24-48 h after the onset of chest pain. We conclude that the BMD LD-1 assay is equivalent to the immunochemical and electrophoretic assays for measuring the LD-1 isoenzyme.

Clinical evaluation of an automated chemical inhibition assay for lactate dehydrogenase isoenzyme 1

We evaluated an automated assay for lactate dehydrogenase (LD; EC 1.1.1.27) isoenzymes, supplied by Boehringer Mannheim Diagnostics (BMD) and based on selective chemical inhibition of non-LD-1 isoenzymes by guanidine thiocyanate. Results were compared with the Roche Isomune LD-1 method. The Hitachi 717 analyzer was used to measure enzyme activity for both procedures in 229 serum samples. One hundred specimens were also analyzed by the Helena rapid electrophoresis (REP) method. We determined the limit of linearity of the BMD method to be about 1200 U of LD-1 per liter. The analytical correlation of BMD (y) with Isomune (x) yielded y = 1.0x + 0.5 U/L, r = 0.997, Sy/x = 16.9 (range 20-1397 U/L). The regression equation for BMD vs REP was y = 1.1x + 7.2% (r = 0.800, Sy/x = 7.4, range 14-83%). Average values for within-run precision for low (38 U/L), medium (180 U/L), and high (865 U/L) controls were 4.1%, 1.0%, and 0.5%, respectively (16 trials of six each). The average values for run-to-run precision were 4.1%, 1.7%, and 1.1%, respectively, for these controls (n = 16). We used receiver-operating characteristic curves to determine optimum decision limits. Using an LD-1 cutoff of 40% of total LD, we obtained a clinical sensitivity of 97-100% and a specificity of 95% when blood was collected during the optimum interval, 24-48 h after the onset of chest pain. We conclude that the BMD LD-1 assay is equivalent to the immunochemical and electrophoretic assays for measuring the LD-1 isoenzyme.

[Observations on substance P in the brain and spinal cord in schizophrenia]

The regional distribution of substance P in postmortem brain and spinal cord of 5 cases of schizophrenia were investigated using the immunohistochemical PAP and ABC technique. Substance P immunoreactive fibers were primarily found in Substantia nigra, nucleus tractus spinalis n. trigemini, nucleus tractus solitarii, nucleus spinalis n. vestibuli, nucleus ambiguous, Central gray matter of the midbrain, globus pallidus and cornua posteriora spinales. The 5 cases showed no differences to the controls. These results agree with the finding reported abroad that the brain tissues were measured by radioimmunoassays. It was also discussed on study method of substance P in Central nervous system.

Relationships among direct-acting mutagenicity, nitro group orientation and polarographic reduction potential of 6-nitrobenzo[a]pyrene, 7-nitrobenz[a]anthracene and their derivatives

The direct-acting mutagenicity in Salmonella typhimurium strains TA98 and TA100 and the half-wave reduction potentials of 6-nitrobenzo[a]pyrene (6-nitro-BaP), 7-nitrobenz[a]anthracene (7-nitro-BA), and a series of their derivatives were compared. The common structural feature of these compounds is that their nitro substituents, in order to minimize steric hindrance, preferentially adopt an orientation perpendicular or nearly perpendicular to the aromatic rings. All of the compounds, except 7-hydroxy-6-nitro-BaP and 7-acetoxy-6-nitro-BaP, were found to exhibit very weak or no direct-acting mutagenicity. 7-Acetoxy-6-nitro-BaP and 7-hydroxy-6-nitro-BaP were also found to have the lowest reduction potentials among the tested compounds. The results suggest that a combination of the orientation of the nitro substituent and the first half-wave reduction potential of the compound may correlate with the direct-acting bacterial mutagenicity of nitro-polycyclic aromatic hydrocarbons.

Interaction of alpha-agglutinin with Saccharomyces cerevisiae a cells

Binding of Saccharomyces cerevisiae alpha-agglutinin to target a cells was assayed by agglutination inhibition and 125I-alpha-agglutinin binding. The assays showed characteristics of equilibrium binding, namely saturability, competability, and the establishment of a kinetic endpoint in the presence of free alpha-agglutinin and free receptor. The binding was heterogeneous, displaying strong binding (10(9) liters/mol) and a weaker interaction. There were about 2 X 10(4) strong binding sites per a cell. Denaturing gels displayed identical labeled species binding to the a cells in the weak and strong interactions. Furthermore, weakly bound material could subsequently bind tightly to fresh a cells, implying that the same species of alpha-agglutinin was bound in the two states.

Identification of glycoprotein components of alpha-agglutinin, a cell adhesion protein from Saccharomyces cerevisiae

Several glycoproteins which inhibit the agglutinability of Saccharomyces cerevisiae mating type a cells were partially purified from extracts of mating type alpha cells. These proteins, called alpha-agglutinin, were labeled with 125I-Bolton-Hunter reagent. The labeled alpha-agglutinin showed specific binding to a cells. Such specific binding approached saturation with respect to agglutinin or cells and was inhibited in the presence of excess unlabeled alpha-agglutinin. Nonspecific binding was similar in a and alpha cells, was neither saturable nor competable, and was three- to fourfold less than the specific binding to a cells at maximum tested agglutinin concentrations. The major a-specific binding species had a low electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels and had an apparent molecular weight of 155,000 by rate zonal centrifugation. Endo-N-acetylglucosaminidase H digestion of the purified glycoprotein complex converted the low-mobility material to four major and several minor bands which were resolved by polyacrylamide gel electrophoresis. All but two minor peptides bound specifically to a cells. Analyses of agglutinin from mnn mutants confirmed the deglycosylation results in suggesting that the N-linked carbohydrate portion of alpha-agglutinin was not necessary for activity.

A comparison of the treatment of hypertension with Chinese herbal and Western medication

Forty-five patients with diastolic blood pressure (DBP) greater than or equal to 105 mmHg were randomly assigned to receive Western (group 1, n = 21) or a classical Chinese herbal preparation (group 2, n = 24) to treat their hypertension (HBP). All remained hypertensive after 4 days in the hospital without treatment. Except for baseline Na+ excretion (higher in group 1) and somewhat more evidence of end organ damage in group 1, the patient groups were comparable. Those in group 1 were given a thiazide diuretic and propranolol if needed, and those in group 2, a mixture of 12 herbs. Patients on active therapy in group 1 had a drop in blood pressure (BP) from 172.6 +/- 27.8/107.4 +/- 13.6 to 141.2 +/- 26.2/89.6 +/- 12.0 mmHg, whereas those in group 2 had no change in BP, 168.8 +/- 22.0/107.7 +/- 9.8 mmHg to 165.7 +/- 23.7/106.0 +/- 11.8 mmHg. Although 66% of patients in group 1 had a DBP under 90 mmHg by discharge, only 8% of those in group 2 did. Except for a fall in serum K+ in group 1, there were no significant biochemical or clinical problems in either group. We conclude that standard Western medication is more effective than a classical Chinese herbal preparation used to treat HBP.

Etiologic studies of epidemic hemorrhagic fever (hemorrhagic fever with renal syndrome)

Two strains of epidemic hemorrhagic fever (EHF) virus were isolated from the lung tissues of Apodemus agrarius mice that were captured in an area where EHF is endemic. The strains were isolated by passages in A. agrarius mice from a nonendemic area. Identification of the isolates by usual procedures was confirmed by repeated blind tests with coded sera. Contamination with certain known viruses such as reovirus, adenovirus (types 3 and 7), and other pathogens, such as murine typhus rickettsiae and Leptospira, which may be naturally present in wild rodents, appeared to have been ruled out. The antigen slides made from these isolates are in use in the specific diagnosis and seroepidemiologic studies of EHF. The first successful application is the serodiagnosis of a mild type of hemorrhagic fever that occurs with characteristic epidemiologic features in certain provinces of China.

Potential inhibitors of S-adenosylmethionine-dependent methyltransferases. 7. Role of the ribosyl moiety in enzymatic binding of S-adenosyl-L-homocysteine and S-adenosyl-L-methionine

A series of 2',3'-acyclic analogues of S-adenosyl-L-homocysteine were synthesized and evaluated as inhibitors of S-adenosyl-L-methionine-dependent methyltransferases. The 2',3'-acyclic analogues were prepared by periodate oxidation of the corresponding ribonucleosides, followed by reduction of the intermediate dialdehydes with sodium borohydride. These 2',3'-acyclic ribonucleosides were inactive as inhibitors of histamine N-methyltransferase, catechol O-methyltransferase, phenylethanolamine N-methyltransferase, and hydroxyindole O-methyltransferase. These results suggest that the rigidity of the ribosyl ring of S-adenosyl-L-homocysteine is crucial to its enzymatic bindings.

Affinity labeling of histamine N-methyltransferase by 2',3'-dialdehyde derivatives of S-adenosylhomocysteine and S-adenosylmethionine. Kinetics of inactivation

S-Adenosyl-L-methionine (AdoMet), S-adenosyl-L-homocysteine (L-AdoHcy), and related ribonucleosides have been oxidized with periodic acid to the corresponding 2',3'-dialdehydes. Both AdoMet dialdehyde and L-AdoHcy dialdehyde were observed to rapidly and irreversibly inactivate histamine N-methyltransferase (HMT). Equally active as an irreversible inhibitor was S-adenosyl-D-homocysteine dialdehyde (D-AdoHcy dialdehyde), which is consistent with the known affinity of HMT for S-adenosyl-D-homocysteine (D-AdoHcy). Other analogues of AdoHcy dialdehyde (S-adenosyl-L-cysteine dialdehyde, S-adenosyl-L-homocysteine sulfoxide dialdehyde, and adenosine dialdehyde) also produced irreversible inactivation of HMT, but at predictably slower rates. The corresponding acyclic 2',3'-ribonucleosides, which were obtained by NaBH4 reduction of the ribonucleosides dialdehydes, were found to be very weak, reversible inhibitors of HMT. Kinetic analysis of the inactivation of HMT produced by L-AdoHcy dialdehyde, AdoMet dialdehyde, and D-AdoHcy dialdehyde suggested mechanisms involving the formation of dissociable enzyme-inhibitor complexes prior to irreversible inactivation. Studies using L-[2,8-3H] AdoHcy dialdehyde revealed that incorporation of radioactivity into HMT closely paralleled the loss of enzyme activity. The results of these studies indicate that L-AdoHcy dialdehyde, D-AdoHcy dialdehyde, and AdoMet dialdehyde are affinity labeling reagents for HMT.

Antitumor agents XXX: Evaluation of alpha-methylene-gamma-lactone-containing agents for inhibition of tumor growth, respiration, and nucleic acid synthesis

Evidence is presented that a number of sesquiterpene lactones isolated from plants and synthesized pyrimidines containing the alpha-methylene-gamma-lactone moiety are potent inhibitors of Walker 256 carcinosarcoma and Ehrlich ascites tumor growth and marginal inhibitors of P-388 lymphocytic leukemia and Lewis lung tumor growth. In vitro aerobic basal respiration and oxidative phosphorylation processes of Ehrlich ascites cells were inhibited by these agents as well as deoxyribonucleic acid polymerase and thymidylate synthetase enzymatic activities. These studies indicate that the alpha-methylene-gamma-lactone moiety, the beta-unsubstituted cyclopentenone ring, and the alpha-epoxycyclopentanone system are the essential moieties for inhibition of these biochemical parameters.

Antitumor agents. 25. Synthesis and antitumor activity of uracil and thymine alpha-methylene-gamma-lactones and related derivatives

Uracil and thymine alpha-methylene-gamma-lactones and related derivatives have been synthesized as novel potential alkylating antitumor agents. The synthesis of these compounds involved the convenient Reformatsky-type reaction between ethyl-alpha-(bromomethyl)acrylate and the proper pyrimidinyl ketones. Preliminary in vivo tumor assay indicated that these compounds were active against the Walker 256 carcinosarcoma in rats and the P-388 lymphocytic leukemia as well as the B-16 melanotic melanoma in mice at 2.5-25 mg/kg.

Potential inhibitors of S-adenosylmethionine-dependent methyltransferases. 5. Role of the asymmetric sulfonium pole in the enzymatic binding of S-adenosyl-L-methionine

The configuration at the asymmetric sulfonium pole of S-adenosyl-L-methionine (SAM) necessary for optimal enzymatic binding and methyl donation has been elucidated in this study. For the transmethylations catalyzed by catechol O-methyltransferase, phenylethanolamine N-methyltransferase, histamine N-methyltransferase, and hydroxyindole O-methyltransferase, it was demonstrated that only the natural (-) enantiomer of SAM was active as a methyl donor. The corresponding (+)-SAM, which was prepared by enzymatic resolution of synthetic (+/-)-SAM, was shown to be inactive as a methyl donor in these enzymatic reactions. The (+)-SAM was found, however, to be a potent inhibitor of each of these enzyme-catalyzed transmethylations. These results suggest that the (+) enantiomer offers a nonproductive configuration for the methyl-transfer reaction itself; however, this configuration fails to hamper enzymatic binding. These results are discussed relative to the geometric requirements necessary for the methyl-transfer reaction and the requirements for enzymatic binding.

Potential inhibitors of S-adenosylmethionine-dependent methyltransferases. 4. Further modifications of the amino and base portions of S-adenosyl-L-homocysteine

Structural analogues of S-adenosyl-L-homocysteine (L-SAH), with modifications in the amino acid or base portions of the molecule, have been synthesized and evaluated for their abilities to inhibit the transmethylations catalyzed by catechol O-methyltransferase (COMT), phenylethanolamine N-methyltransferase (PNMT), histamine N-methyltransferase (HMT), hydroxyindole O-methyltransferase (HIOMT), and indoleethylamine N-methyltransferase (INMT). From these studies some interesting and potentially useful differences in the structural features of L-SAH needed to produce maximal binding to these methyltransferases were detected. This paper provides evidence that 8-azaadenosyl-L-homocysteine is a potent and selective inhibitor of HIOMT, whereas N6-methyladenosyl-L-homocysteine and N6-methyl-3-deazaadenosyl-L-homocysteine are selective inhibitors in INMT. In contrast, it was found that S-tubercidinyl-L-homocysteine was a fairly potent, but nonselective inhibitor of all of the methyltransferases studied. The differences and the similarities in the requirements for the binding of SAH to methyltransferases which were detected in this study and earlier studies from our laboratory, are described. The possibilites of utilizing differences in binding requirements for the design of SAH analogues as specific inhibitors of methyltransferases are discussed.

Potential inhibitors of S-adenosylmethionine-dependent methyltransferases. 3. Modifications of the sugar portion of S-adenosylhomocysteine

Structural analogs of S-ADENOSYL-L-HONOCYSTEINE (L-SAG), WITH MODIFICATION IN THE RIBCOSE PORTION OF THE MOLECULE, HAVE BEEN SYNTHESIZED AND THEIR ABILITIES TO INHIBIT CATECHOL O-METHYLTRANSFERECE(COMT), phenylethanolamine N-methltransferase (PNMT) histamine N-methyltransferase (HMT),and hydroxyindole o-methytransferase (HIOMT) have been investigated. From these studies it was concluded that, in general, the 2'-hydroxyl and 3'-hydroxyl groups of the ribcose moiety of SAH play crucial roles in the binding of this molecule to most methyltransferases. However several interesting exceptions to this strict structural specificity have been observed. While S-3'-DEOXY-ADENOSYL-L-HOMOCYSTEINE PRODUCED NO INHIBITION OF HMT and HIOMT, it produced strong inhibition of the transmethylation catalyzed by PNMT and COMT. Likewise, S-2'-DEOXYADENOSYL-L-HOMOCYSTEINE AND S-5'-(9-(arabinofuranosyl)adenyl)-l-homocysteine had little or no effect of COMT, HMT, and HIOMT but were potent inhibtors of PNMT. The significance of these data relative to the nature of the SAH binding sites and the potential inhibitors of PNMT. The significance of these data relative to the nature of the SAH binding sites and the potential for in vivo differential inhibition of methyltransferases will be discussed.