The use of intravenous H2-receptor antagonists in a tertiary care hospital.

OBJECTIVE: The rationale for the widespread use of intravenous H2 receptor antagonists(IVH2 RA) in hospitalized patients is not clear. We therefore examined prescribing patterns and, using strict criteria, determined whether use was appropriate. Cost of administration and potential savings were also determined. METHODS: Data were obtained prospectively on 100 consecutive patients prescribed intravenous ranitidine and retrospectively on patients admitted with gastrointestinal (GI) bleeding. RESULTS: For the prospective study, various indications for prescribing intravenous ranitidine were given, including postoperative patients and patients treated with steroids. Using criteria from published literature 80% of the use was considered inappropriate. Nearly 40% of the doses were given while the patient was tolerating oral intake. Creatinine clearance was impaired in 26% of patients, though only one had dosage reduction. Estimated annual cost of intravenous ranitidine was $317,000. The retrospective study of 86 consecutive patients admitted with GI bleeding revealed that all patients received intravenous ranitidine on admission, none of which was considered appropriate. The final diagnoses were peptic ulcer (49), colonic process (11), esophagitis (seven), gastric erosions (five), esophageal varices (five), Mallory-Weiss tears (four), duodenitis (two), no diagnosis (three), and jejunal ulcer (one). CONCLUSIONS: Inappropriate use of intravenous ranitidine is common. This includes inappropriate indication, dosage, and duration of use. Large financial benefits could have been obtained if close attention was given to prescribing patterns.

LPS-binding protein protects mice from septic shock caused by LPS or gram-negative bacteria.

LPS-binding protein (LBP) recognizes bacterial LPS and transfers it to CD14, thereby enhancing host cell stimulation, eventually resulting in pathogenic states such as septic shock. Recently, LBP also was shown to detoxify LPS by transferring LPS into HDL particles in vitro. Thus, the predominant in vivo function of LBP has remained unclear. To investigate the biological activity of acute phase concentrations of recombinant murine LBP, high concentrations of LBP were investigated in vitro and in vivo. Although addition of low concentrations of LBP to a murine macrophage cell line enhanced LPS-induced TNF-alpha synthesis, acute phase concentrations of LBP blocked this effect in comparison to low-dose LBP. When injected into mice intraperitoneally, LBP inhibited LPS-mediated cytokine release and prevented hepatic failure resulting in a significantly decreased mortality rate in LPS-challenged and D-galactosamine-sensitized mice, as well as in a murine model of bacteremia. These results complement a recent study revealing LBP-deficient mice to be dramatically more susceptible to an intraperitoneal Salmonella infection as compared with normal mice. We conclude that acute phase LBP has a protective effect against LPS and bacterial infection and may represent a physiologic defense mechanism against infection. Despite the limitations of any murine sepsis model, the results shown may imply that LBP could have beneficial effects during gram-negative peritonitis in humans.

Bovine adrenodoxin--a mitochondrial iron-sulphur protein--binds to chaperonin GroEL.

The interaction of bovine adrenodoxin with the chaperonin GroEL was investigated using sucrose density centrifugation and analytical ultracentrifugation. It could be clearly established that denatured mature adrenodoxin comigrated in a sucrose density gradient with the GroEL oligomer, indicating that a complex had been formed. Up to 2 moles of adrenodoxin/mol GroEL can be bound. From the partial concentrations, association constants of 4.3 x 10(5) M-1 for the first adrenodoxin molecule and of 1.08 x 10(5) M-1 for the second molecule to the complex, respectively, were calculated. Upon addition of the cochaperonin GroES and Mg-ATP to the adrenodoxin-GroEL complex, adrenodoxin was released, indicating a specific binding between GroEL and adrenodoxin.

Mutations of tyrosine 82 in bovine adrenodoxin that affect binding to cytochromes P45011A1 and P45011B1 but not electron transfer.

To understand the function of the unique tyrosine in position 82 of bovine adrenodoxin (Adx), which had been proposed to be involved in electron transfer from NADPH-dependent adrenodoxin reductase (AdR) to cytochrome P-450 enzymes and/or AdR binding by chemical modification studies (Taniguchi, T., and Kimura, T. (1975) Biochemistry 14, 5573-5578), the residue was replaced by phenylalanine, leucine, or serine. Unchanged absorption, CD, and electron spin resonance spectra as well as redox potentials indicate that the environment of the [2Fe-2S] cluster was not affected by the mutations. The Vmax values in cytochrome c reduction, P45011A1- and P45011B1-dependent activities were also not changed when using Y82F, Y82S, and Y82L Adx mutants as electron donor, demonstrating that tyrosine 82 is not involved in the intra- or intermolecular electron transfer. Replacement of tyrosine 82 did not affect AdR binding as shown by unchanged cytochrome c activity. There are, however, changes in Km values up to 4-fold when measuring the enzymatic activities of mutant Adx with P45011A1 and P45011B1. These changes differ in dependence on the P-450 (P45011A1 or P45011B1) used. The results suggest that mutation of tyrosine 82 either directly or indirectly (by inducing small conformational changes of the binding domain) affects the binding of cytochromes P-450.

Crystallization and X-ray examination of bovine adrenodoxin.

Crystals of adrenodoxin from bovine adrenocortical mitochondria were obtained by the hanging-drop vapor diffusion technique. The crystals belong to a hexagonal crystal lattice with cell parameters 172.50 A and 183.49 A. There are 12 molecules in the asymmetric unit. The crystals diffract to beyond 4.0 A resolution.

Simple preparative two-step purification of interleukin-2 from culture medium of lectin stimulated normal human lymphocytes.

A procedure has been developed for the rapid purification of human IL-2 using reversed-phase liquid chromatography on LiChroprep RP-8 and Separon SGX C-18. The resulting IL-2 has a specific activity of 1 X 10(7) U/mg protein and reveals in SDS-PAGE 2 molecular weight forms (approximately 14 kDa and approximately 16 kDa) under reducing and non-reducing conditions. Both forms are biologically active. In 2-dimensional electrophoresis purified IL-2 shows a complex pattern of protein spots located in the IL-2 region which may be due to differences in glycosylation.

Preparation of 40S ribosomal subunit proteins of rat liver by combination of ion exchange chromatography with reversed phase liquid chromatography.

Total protein of small subunits of rat liver ribosomes was fractionated by chromatography on carboxymethylcellulose. Aliquots (between 5 and 30 mg) of the protein material of each peak were further separated by reversed phase liquid chromatography on an octadecasilyl silica column. In this way 15 of the 32 proteins of the small ribosomal subunit of rat liver could be isolated in milligram amounts.

Identification of the ligand trans to thiolate in cytochrome P-450 LM2 by chemical modification.

About 3 tyrosine residues of cytochrome P-450 LM2 are accessible to chemical modification with tetranitromethane. Nitration of two tyrosines inactivates the enzyme to about 20%. The partial formation of a hyper-porphyrin spectrum originating from the pK shift by nitration and formation of a tyrosinate is prevented by modification in the presence of the inhibitor metyrapone. These findings support the assumption of a tyrosine residue as sixth ligand of the heme iron in cytochrome P-450 LM2.

Carp insulin: amino acid sequence, biological activity and structural properties.

The amino acid sequence of insulin of carp (Cyprinus carpio) has been determined and correlated with its biological activity in a fat-cell test and its structural properties as measured by circular dichroism and sedimentation analysis. The amino acid sequence of carp insulin displays some unusual features: the B chain is longer at the N terminus by two residues as compared with mammalian insulins and there are substitutions of the charged residues, found in most insulins at positions B21 and B22, by proline and threonine respectively. On the other hand, all amino acid residues essential for biological activity and for the association of insulin monomers are the same in carp insulin. Accordingly, the half-maximal response in a fat-cell test is reached with carp insulin at concentrations which are only three times higher than with porcine insulin and the maximal response is the same. The circular dichroism spectrum of carp insulin resembles greatly that of bovine insulin indicating that it has a similar spatial structure. Despite amino acid substitutions in the dimer-dimer contact region, carp insulin is able to form hexamers.

Action of rat liver cathepsin L on glucagon.

The proteolytic specificity of cathepsin L on glucagon was determined. Major cleavages are found between Thr7 and Ser8, Asp15 and Ser16, and between Met27 and Asn28. The bonds Ser11-Lys12, Val23-Gln24, and Gln24-Trp25 are hydrolyzed to a relatively low extent only. Whereas cathepsin B hydroxyzes glucagon at the C-terminus by a peptidyldipeptidase mechanism, cathepsin L cleaves the same substrate clearly as endopeptidase.

[Polyamines and their significance for control of cancer chemotherapy (author's transl)]. / Polyamine und ihre Bedeutung für die Kontrolle der Tumorchemotherapie.

Determination of polyamines (putrescine, spermidine) can be useful for evaluation of treatment efficacy. The amount of putrescine and spermidine were estimated for 10 patients (breast carcinoma; stage IV; T0--4 N0--3 M1) prior to, during and after different combination chemotherapy (carminomycin-dibromodulcitol; cyclophosphamide-methotrexate-5-fluorouracil). Hydrolysis with hydrochloric acid showed best results. Automated ion exchange chromatography is a sensitive and reproducible method. 6 out of 10 patients did not show both clinical changes and changes in polyamine content comparable to values prior to combination chemotherapy. One example demonstrated both clinical progression and an increase of polyamine content. A correlation between decrease of putrescine and spermidine level and clinical remission were found in 3 out of 10 patients. These results support the usefulness of polyamine determinations to evaluate cancer chemotherapy.