Studies on compounds of cancer chemoprevention: synthesis of some amides

In search for cancer chemoprevention agents, seven new amide compounds have been synthesized. The structures have been determined based on spectral and chemical data. N-4-(ethoxycarbophenyl)-alpha-naphthamide and N-4-(ethoxycarbophenyl)-beta-naphthamide were shown to be 81% and 79% effective, respectively, for inducing different in HL-60 human promyelocytic leukemia cells at the concentration of 10(-5) mol/L in NBT tests.     

Structure-activity relationships of alkyl- and alkoxy-substituted 1,4-dihydroquinoxaline-2,3-diones: potent and systemically active antagonists for the glycine site of the NMDA receptor

We report on a series of alkyl- and alkoxy-substituted 1,4-dihydroquinoxaline-2,3-diones (QXs), prepared as a continuation of our structure-activity relationship (SAR) study of QXs as antagonists for the glycine site of the N-methyl-D-aspartate (NMDA) receptor. The in vitro potency of these antagonists was determined by displacement of the glycine site radioligand [3H]-5,7-dichlorokynurenic acid ([3H]DCKA) in rat brain cortical membranes. In general, methyl is a good replacement for chloro or bromo in the 6-position, and alkoxy-substituted QXs have lower potencies than alkyl- or halogen-substituted QXs. Ethyl-substituted QXs are generally less potent than methyl-substituted QXs, especially in the 6-position of 5,6,7-trisubstituted QXs. Fusion of a ring system at the 6,7-positions results in QXs with low potency. Several methyl-substituted QXs are potent glycine site antagonists that have surprisingly high in vivo activity in the maximal electroshock (MES) test in mice. Among these, 7-chloro-6-methyl-5-nitro QX (14g) (IC50 = 5 nM) and 7-bromo-6-methyl-5-nitro QX (14f) (IC50 = 9 nM) are comparable in potency to 6,7-dichloro-5-nitro QX (2) (ACEA 1021) as glycine site antagonists. QX 14g has an ED50 value of 1.2 mg/kg iv in the mouse MES assay. Interestingly, alkyl QXs with log P values of 0.5 or less tend to be more bioavailable than QXs with higher log P values. QX 14g has 440-fold selectivity for NMDA vs alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, as determined electrophysiologically under steady-state conditions in oocytes expressing rat cerebral cortex poly(A)+ RNA. Overall, 14g was found to have the best combination of in vitro and in vivo potency of all the compounds tested in this and previous studies on the QX series.     

Machanism of the stimulatory effect of intracerebroventricular administration of histamine on gastatric acid secretion induced by pentagastrin in rats

MOTIVATION: We needed an efficient way to explore the binding reactions leading to protein complexes of known composition and structure. RESULTS: A new program is described that allows the user to define a set of protein elements and to link these elements into an oligomeric 'ball-and-stick' assembly in a graphical interface. Once the structure of the oligomer has been defined, the program then employs a novel algorithm to deduce the binding reactions and intermediate complexes needed to make the oligomer from its starting protein components. The program also finds the equilibrium state of the system, using either default starting concentrations and Kd values or data supplied by the user.     

Effects of mutations in the starch-binding domain of Bacillus macerans cyclodextrin glycosyltransferase

Cyclodextrin glycosyltransferase (CGTase) is an industrially important enzyme that produces cyclodextrins (CD) from starch by intramolecular transglycosylation. CGTase consists of five globular domains labeled A through E. To better understand the role of domain E in CGTase catalysis, we have constructed several mutants of Bacillus macerans CGTase. Removing the entire E domain resulted in an inactive enzyme. Adding six amino acids between domains D and E caused a decrease in activity and thermostability. Replacing domain E with the similar starch-binding domain from Aspergillus awamori glucoamylase I caused a drastic decrease in activity, indicating the necessity of correct alignment of bound substrate. Substituting tyrosine residue 634 (Tyr634) with phenylalanine had very little effect on activity or thermostability. Substituting Tyr634 with glycine resulted in a 25% increase of specific cyclization and starch-hydrolyzing activities compared with that of the wild-type enzyme. The latter mutant was less thermostable. The results of this study indicate that domain E is important for the stability and integrity of B. macerans CGTase.     

Melanotic neuroectodermal tumour of infancy: an immunohistochemical and ultrastructural study

Two cases of melanotic neuro-ectodermal tumour of infancy (MNTI)--a rare neoplasm arising in the first year of life--are reported, with the results of immunohistochemical and ultrastructural examination. The tumours consisted of a biphasic cell population in a fibrous stroma. The small, darkly staining cells comprising the first population stained positively for synaptophysin, showing them to be neuroblasts, and the large epithelioid cells comprising the second cell population stained positively with the antibodies HMB-45 and NKI-Beteb, showing them to be melanocytes. Ultrastructural examination of the second case confirmed the biphasic nature of the tumour cells, with secretory granules and neurofilaments in the neuroblastic population, and melanosomes in the epithelioid population. These results add to the evidence supporting the neural crest origin of MNTI and confirm its formation from two distinct cell lines. Both cases have responded to local excision, with no recurrence more than a year after initial treatment.     

The catalytic domain of human immunodeficiency virus integrase: ordered active site in the F185H mutant

We solved the structure and traced the complete active site of the catalytic domain of the human immunodeficiency virus type 1 integrase (HIV-1 IN) with the F185H mutation. The only previously available crystal structure, the F185K mutant of this domain, lacks one of the catalytically important residues, E152, located in a stretch of 12 disordered residues [Dyda et al. (1994) Science 266, 1981-1986]. It is clear, however, that the active site of HIV-1 IN observed in either structure cannot correspond to that of the functional enzyme, since the cluster of three conserved carboxylic acids does not create a proper metal-binding site. The conformation of the loop was compared with two different conformations found in the catalytic domain of the related avian sarcoma virus integrase [Bujacz et al. (1995) J. Mol. Biol. 253, 333-346]. Flexibility of the active site region of integrases may be required in order for the enzyme to assume a functional conformation in the presence of substrate and/or cofactors.     

Endoscopic management of huge bezoars

The aim of our study was to investigate the coexistence of thyroid autoimmunity and allergic diseases. The prevalence of thyroid autoantibodies was studied in sera from 140 children with different kinds of allergic diseases, 370 11-13-y-old schoolchildren without allergic diseases serving as controls. The prevalence of thyroid peroxidase autoantibodies was found to be higher among the patients than in the control group, 11.4% vs 5.4% (p < 0.05). Ultrasound investigation identified autoimmune thyroiditis in 4.3% (6/140) of the series, which was later confirmed with fine needle aspiration in all six cases, four of which were unknown prior to the study. Our findings may be useful to alert clinicians that thyroid diseases may be superimposed on allergic children.     

Expression of dentin sialoprotein (DSP) and other molecular determinants by a new cell line from dental papillae, MDPC-23

The purpose of this study was to characterize the molecular expression of a spontaneously immortalized and cloned cell line (MDPC-23) derived from 18-19 day CD-I fetal mouse molar dental papillae to determine if these cells were odontoblast-like. Western blots showed that a protein band, at approximately 105 kDa, reacting positively with anti-DSP antibodies and co-migrating with mouse DSP, was present in lysates of cells from passages 7, 37 and 77, in serum-free conditioned medium from passage 37 cells, and in mouse dentin extract. A minor band at 55 kDa was also apparent in cell lysates. Using a cDNA probe for a 486bp mouse DSP coding sequence, DSP or DSP-PP mRNA expression was detected by Northern analysis as well as Southern analysis after RT-PCR in all three passages. It was also shown that in these cells 1,25 (OH)2 vitamin D3 upregulated both osteopontin and osteocalcin mRNA, and dexamethasone downregulated alkaline phosphatase and alpha2(I) collagen mRNA. Thus, MDPC-23 cells express proteins which are common to mineralizing tissue. The expression of DSP and DSP-PP strongly suggests that this cell line is from the odontoblast lineage.