An efficient chemical approach to bispecific antibodies and antibodies of high valency

Irreversible chemical programming of monoclonal aldolase antibody (mAb) 38C2 has been accomplished with β-lactam equipped mono- and bifunctional targeting modules, including a cyclic-RGD peptide linked to either the peptide (d-Lys⁶)-LHRH or another cyclic RGD unit and a small-molecule integrin inhibitor SCS-873 conjugated to (d-Lys⁶)LHRH. We also prepared monofunctional targeting modules containing either cyclic RGD or (d-Lys⁶)-LHRH peptides. Binding of the chemically programmed antibodies to integrin receptors α(v)β(3) and α(v)β(5) and to the luteinizing hormone releasing hormone receptor were evaluated. The bifunctional and bivalent c-RGD/LHRH and SCS-783/LHRH, the monofunctional and tetravalent c-RGD/c-RGD, and the monofunctional bivalent c-RGD chemically programmed antibodies bound specifically to the isolated integrin receptor proteins as well as to integrins expressed on human melanoma M-21 cells. c-RGD/LHRH, SCS-783/LHRH, and LHRH chemically programmed antibodies bound specifically to the LHRH receptors expressed on human ovarian cancer cells. This approach provides an efficient, versatile, and economically viable route to high-valency therapeutic antibodies that target defined combinations of specific receptors. Additionally, this approach should be applicable to chemically programmed vaccines.     

Serum Levels of Soluble CD26/Dipeptidyl Peptidase-IV in Type 2 Diabetes Mellitus and Its Association with Metabolic Syndrome and Therapy with Antidiabetic Agents in Malaysian Subjects

BackgroundA soluble form of CD26/dipeptidyl peptidase-IV (sCD26/DPP-IV) induces DPP-IV enzymatic activity that degrades incretin. We investigated fasting serum levels of sCD26/DPP-IV and active glucagon-like peptide-1 (GLP-1) in Malaysian patients with type 2 diabetes mellitus (T2DM) with and without metabolic syndrome (MetS), as well as the associations between sCD26/DPP-IV levels, MetS, and antidiabetic therapy.MethodsWe assessed sCD26/DPP-IV levels, active GLP-1 levels, body mass index (BMI), glucose, insulin, A1c, glucose homeostasis indices, and lipid profiles in 549 Malaysian subjects (including 257 T2DM patients with MetS, 57 T2DM patients without MetS, 71 non-diabetics with MetS, and 164 control subjects without diabetes or metabolic syndrome).ResultsFasting serum levels of sCD26/DPP-IV were significantly higher in T2DM patients with and without MetS than in normal subjects. Likewise, sCD26/DPP-IV levels were significantly higher in patients with T2DM and MetS than in non-diabetic patients with MetS. However, active GLP-1 levels were significantly lower in T2DM patients both with and without MetS than in normal subjects. In T2DM subjects, sCD26/DPP-IV levels were associated with significantly higher A1c levels, but were significantly lower in patients using monotherapy with metformin. In addition, no significant differences in sCD26/DPP-IV levels were found between diabetic subjects with and without MetS. Furthermore, sCD26/DPP-IV levels were negatively correlated with active GLP-1 levels in T2DM patients both with and without MetS. In normal subjects, sCD26/DPP-IV levels were associated with increased BMI, cholesterol, and LDL-cholesterol (LDL-c) levels.ConclusionSerum sCD26/DPP-IV levels increased in T2DM subjects with and without MetS. Active GLP-1 levels decreased in T2DM patients both with and without MetS. In addition, sCD26/DPP-IV levels were associated with Alc levels and negatively correlated with active GLP-1 levels. Moreover, metformin monotherapy was associated with reduced sCD26/DPP-IV levels. In normal subjects, sCD26/DPP-IV levels were associated with increased BMI, cholesterol, and LDL-c.     

Prostaglandins in cerebrospinal fluid of healthy human volunteers, abstinent alcoholics and rhesus monkeys

A sensitive and selective assay for measuring prostaglandins in cerebrospinal fluid has been developed, based on the selected-ion-monitoring, electron-capture negative ionization GC/MS detection for the MO-PFB-TMS derivatives of prostaglandins E2, E1, F2 alpha, F1 alpha, and 6-keto-F1 alpha. Improvements over previously published assay procedures have been made, and the new assay has been applied to measurement of prostaglandin concentrations in lumbar CSF of healthy human volunteers, abstinent alcoholic patients, in cisternal CSF of Rhesus monkeys, and continuously sampled lumbar CSF of awake Rhesus monkeys. Results indicated that the concentrations of PGE2, PGE1, PGF1 alpha, and 6-keto-PGF1 alpha were below 15 pg/mL CSF in lumbar CSF of healthy humans and abstinent alcoholics, and in cisternal CSF of Rhesus monkeys. In contrast, continuously sampled lumbar CSF of awake Rhesus monkeys contained more than 200 pg/mL of PGE2, PGF2 alpha, and 6-keto-PGF1 alpha, probably present as a result of local production.     

Effect of incubation conditions, inhibitors, 2-mercaptoethanol and testosterone on RNA synthesis in ram spermatozoa

In vitro studies on RNA synthesis using washed ram spermatozoa were carried out by measuring the incorporation of (3)H-uridine into RNA. Penicillin-G (100 mug/ml medium) was added to prevent contamination by microorganisms. Spermatozoa were quickly separated from seminal plasma by washing twice in Tris-HCl buffer (at pH 7.2) and centrifuged at 1,000 g for 5 min. Washed spermatozoa were then diluted to 1 10 , 1 20 or 1 40 (v/v) by the same buffer system (containing 400 mg% glucose) and were incubated in air at 37 degrees C for 1, 2 and 4 h. Results indicated that the rate of RNA synthesis was maximal at 1 40 semenbuffer dilution (5-8 x 10(7) spermatozoa/ml) and increased linearly up to 4 h of incubation. The rate of RNA synthesis at 1 40 dilution also increased linearly as the dose of exogenous glucose substrate was increased up to 400 mg%. Denaturation of the ram spermatozoa by 1% HgCl(2) caused almost complete inhibition of RNA synthesis that amounted to 97% of the control samples. Incubation of spermatozoa with 50, 100 or 200 mug/ml chloramphenicol also inhibited uridine incorporation by 86 to 94%, while equivalent doses of cycloheximide did not. On the other hand, the incorporation of (3)H-uridine into the RNA of ram spermatozoa was significantly enhanced by graded doses of 2-mercaptoethanol (0.2, 0.4 and 0.8 muM) and of testosterone (15 and 30 mug/ml). The results of this study indicate RNA synthesis, mainly of mitochondrial origin, by mature ram sperm. The data also suggest a role for intracellular cyclic adenosine monophosphate in the regulation of sperm RNA synthesis.     

Synaptic effects of the synthetic pyrethroid resmethrin in rat brain in vitro

Resmethrin (30 microM) induced release of transmitters was not affected by manipulation of the Na+ current with either choline or tetrodotoxin agents which readily reversed the effects of veratridine, deltamethrin and cypermethrin. Resmethrin (I50: 2.2 microM) inhibited the ATP dependent uptake of Ca2+ but deltamethrin and cypermethrin were much less effective. Resmethrin also displaced Ca2+ from crude synaptosomal membranes. The release promoting effects of resmethrin in rat brain in vitro are better explained by its effects on Ca2+ rather than through a specific effect on the Na+ channel. In contrast, the effects of deltamethrin and cypermethrin promote transmitter release by a Na+ dependent process.     

Analysis of aminophospholipid molecular species by high performance liquid chromatography

A new method is described for the separation of individual molecular species of the aminophospholipids, phosphatidylethanolamine and phosphatidylserine. Trinitrobenzene-sulfonic acid was used to derivatize both aminophospholipids and the derivatives were purified by thin-layer chromatography. A reversed-phase high performance liquid chromatography technique was developed to separate and quantify individual molecular species based upon ultraviolet detection of the attached chromophore. The retention times of the molecular species on the C18 reversed-phase column were longer with increasing carbon chain length and decreasing degree of unsaturation of fatty acyl chain. The overall procedure allowed a quantitative recovery of the aminophospholipid species. The lower limit of detection was about 10 pmol and a linear response was observed in the range of 0.1-10 nmol of phospholipid. Using this method, we were able to separate and quantify trinitrophenyl-phosphatidylethanolamine molecular species of both subclasses (diacyl and alkenyl) from human red blood cells and rat brains. Separation of species was confirmed by gas-liquid chromatographic analysis of the fatty acid content of each peak and by thermospray liquid chromatography-mass spectrometry. This new method provides a convenient and sensitive technique for studies of aminophospholipid molecular species composition. Furthermore, it appears to be a useful tool for the analysis of asymmetric distribution of these species in biological membranes.     

Studies on activation and inhibition of cathepsin B from buffalo liver

Cathepsin B (EC 3.4.22.1) was purified from buffalo liver. The enzyme activity against-benzoyl-dl-arginine-naphthylamme (BANA) was substantially reduced by heat (above 37C) and by nondenaturing concentrations of urea (3 M) and guanidine hydrochloride (1 M). Cathepsin B was significantly activated by 1.5 mM EDTA alone. The activation of the enzyme was further enhanced in the presence of thiol compounds, e.g., cysteine thioglycolic acid, 2,3-dimercapto-1-propenol, and dithioerythritol (DTE). The minimum concentration of the thiol compound required for optimal activation of cathepsin B was found to be lowest (0.2 mM) for DTE. The BANA hydrolyzing activity of cathepsin B was substantially reduced by Cu²⁺ (20–200M) and Ca²⁺ (30–250 mM) as well as by thiol blocking reagents, e.g., iodoacetate, 5,5-dithiobis(2-nitro-benzoic acid) (DTNB), andp-hydroxymercuribenzoate (pHMB). The enzyme activity was completely abolished when the molar ratio of the reagent: cathepsin B was close to 1. The number of free sulfhydryl groups in cathepsin B was determined to be 2 by titration against DTNB and pHMB. Modification of one free thiol group of cathepsin B resulted in complete loss of BANA hydrolyzing activity.