[Effect of alcohol extract of Cornus officinalis Sieb. et Zucc on GLUT4 expression in skeletal muscle in type 2 (non-insulin-dependent) diabetic mellitus rats]

OBJECTIVE

Based on its effects of decreasing postprandial plasma glucose and increasing insulin level in non-insulin-dependent diabetic mellitus (NIDDM) rats, we studied the effects of Alcohol extract of Cornus officinalis Sieb. et Zucc on the GLUT4 expression in NIDDM model rats.

METHOD

The rat model of NIDDM was made. The animals were divided into three groups(six for each group): group I: control; group II: NIDDM model; group III: NIDDM model + Cornus officinalis Sieb. et Zucc. The drug was given orally to animals one time a day, uninterrupted for a month. The GLUT4 mRNA and its protein expression in skeletal muscle were observed with Northern blot and Western blot method, respectively.

RESULT

The GLUT4 mRNA expression in skeletal muscle was decreased remarkably in NIDDM rats (P < 0.01, compared to control group). Alcohol extract of Cornus officinalis Sieb. et Zucc increased GLUT4 mRNA expression in NIDDM rats(P < 0.01), compared to NIDDM model group). The result of GLUT4 protein expression was similar to GLUT4 mRNA expression.

CONCLUSION

This experiment demonstrated that alcohol extract of Cornus officinalis Sieb. et Zucc can increase GLUT4 mRNA and its protein expression in NIDDM rats through promoting proliferation of islet and increasing postprandial secretion of insulin and therefore accelerate glucose transport.

Discovery of a series of nonpeptide small molecules that inhibit the binding of insulin-like growth factor (IGF) to IGF-binding proteins

Insulin-like growth factors (IGF-I and II) play an important role in metabolic and mitogenic activities through stimulation of the IGF-I receptor on the cell surface. Although the concentration of IGF in blood and cerebrospinal fluid is quite high (>100 nM), this large pool of IGF is biologically inactive because of its association with six distinct binding proteins, which form high-affinity complexes with IGF. Thus, inhibitors of IGF-binding proteins (IGFBPs), especially IGFBP-3, could potentially alter the distribution between the "free" and "bound" forms of IGF and thereby elevate biologically active IGF-I to exert a beneficial effect on those patients with diseases that respond to the application of exogenous IGF-I. Whereas IGF-I peptide variants, which bind to IGFBPs but not the IGF-I receptor, have been shown to be potent IGF/IGFBP inhibitors, small molecule nonpeptide IGF/IGFBP inhibitors have the potential advantages of oral bioavailability and flexible dosing regimen. Here we report the discovery of several isoquinoline analogues, exemplified by 1 and 2, which bind IGFBP-3 as well as other IGFBPs at low nanomolar concentrations. More importantly, both compounds were shown to be able to release biologically active IGF-I from the IGF-I/IGFBP-3 complex. These results point to the feasibility of developing orally active therapeutics to treat IGF-responsive diseases by optimization of the lead molecules 1 and 2.

Identification of a nonpeptide ligand that releases bioactive insulin-like growth factor-I from its binding protein complex

Insulin-like growth factor-I (IGF-I) has both metabolic and mitogenic activities mediated through interaction with the type 1 IGF receptor. The circulation of IGF-I in blood and interstitial fluid is not free but bound mostly to a family of six high affinity IGF-binding proteins, which form stable complexes with IGF and neutralize its bioactivity. Therefore, displacement of this large pool of endogenous IGF from the binding proteins could elevate "free" IGF levels to elicit beneficial effects in diabetes and other IGF-responsive diseases comparable with those produced by administration of exogenous IGF-I. We report here the identification of a nonpeptide ligand NBI-31772, which displaces IGF-I from all six IGF-binding proteins at low nanomolar concentrations from screening of the in-house chemical libraries. Furthermore, the released free IGF-I was shown to be biologically active in an in vitro bioassay. Thus, NBI-31772 could serve as a valuable lead molecule for the design of novel therapeutics to treat diabetes and other IGF-responsive diseases.

A cytoplasmic RNA vector derived from nontransmissible Sendai virus with efficient gene transfer and expression

We have recovered a virion from defective cDNA of Sendai virus (SeV) that is capable of self-replication but incapable of transmissible-virion production. This virion delivers and expresses foreign genes in infected cells, and this is the first report of a gene expression vector derived from a defective viral genome of the Paramyxoviridae. First, functional ribonucleoprotein complexes (RNPs) were recovered from SeV cloned cDNA defective in the F (envelope fusion protein) gene, in the presence of plasmids expressing nucleocapsid protein and viral RNA polymerase. Then the RNPs were transfected to the cells inducibly expressing F protein. Virion-like particles thus obtained had a titer of 0.5 x 10(8) to 1. 0 x 10(8) cell infectious units/ml and contained F-defective RNA genome. This defective vector amplified specifically in an F-expressing packaging cell line in a trypsin-dependent manner but did not spread to F-nonexpressing cells. This vector infected and expressed an enhanced green fluorescent protein reporter gene in various types of animal and human cells, including nondividing cells, with high efficiency. These results suggest that this vector has great potential for use in human gene therapy and vaccine delivery systems.

Progress towards the development of non-peptide orally-active gonadotropin-releasing hormone (GnRH) antagonists: therapeutic implications

Gonadotropin-releasing hormone (GnRH) is a decapeptide (pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly.NH2) which is produced from a precursor polypeptide in hypothalamic neurons and secreted in a pulsatile fashion to stimulate the secretion of LH and FSH via its interaction with a cognate receptor on gonadotropes. Low doses of the native peptide delivered in a pulsatile manner to mimic that found in the hypothalamic portal vessels restore fertility in hypogonadal patients, and are also effective in treating cryptorchidism and delayed puberty. Administration of high doses of GnRH, or agonist analogues, causes desensitization of the gonadotrope with consequent decline in gonadal gametogenesis and steroid and peptide hormone synthesis. This phenomenon finds extensive therapeutic application in clinical medicine in a wide spectrum of disease (Table 1). In addition, GnRH analogues have promise as new generation male and female contraceptives in conjunction with steroid hormone replacement. GnRH antagonists inhibit the reproductive system through competition with endogenous GnRH for the receptor and, in view of their rapid effects, are being increasingly used for the above mentioned applications. The peptide agonists and antagonists currently available require parenteral administration, typically in the form of long-acting depots. A new generation of non-peptide GnRH antagonists are beginning to emerge which should allow oral administration and, therefore, may provide greater flexibility of dosing, lower costs and increased patient acceptance.

In situ investigation of Fas/FasL expression in chronic hepatitis B infection and related liver diseases

To evaluate Fas/FasL expression in hepatitis B virus-related chronic liver disease, liver biopsies from 44 such cases were studied immunohistochemically. FasL was detected in the infiltrating lymphocytes and both FasL and Fas were found in the hepatocytes. The Fas and FasL-positive cells were mostly found at the advancing edges of interphase hepatitis, and Fas/FasL expression was closely correlated with the inflammatory activity. Unexpectedly, FasL was also expressed in liver cirrhotic nodules, particularly in those with hepatocellular carcinoma with or without inflammation. These results suggest that the factors which induce hepatocyte transformation might also trigger FasL expression and promote FasL/Fas-mediated apoptosis.

The correlation of Ureaplasma urealyticum infection with infertility

A prevalence study of Ureaplasma urealyticum (UU) infection of the male genital tract was carried out in Shanghai between March 1992 and June 1995. Significantly higher frequency of UU infection was found among infertile males (549/1416) as compared to fertile controls (34/375). Examination of 8 specimens each from infertile men and fertile subjects by electron microscopy, immunogold and immunofluorescence techniques, demonstrated adhesion of Ureaplasma urealyticum to the membrane of spermatozoa and exfoliated germ cells. In addition, gold particles on Ureaplasma urealyticum were found to be adhered to the sperm surface in 4 of the 8 samples. Strong specific anti-UU fluorescence was detected in 6 of 8 samples, mainly on the midpieces and post-acrosomal regions of the spermatozoa. To further study the effects of Ureaplasma urealyticum on fertility, 47 male Sprague-Dawley (SD) rats were infected artificially with Ureaplasma urealyticum serotype 8 (T960). Morphological changes in the seminiferous tubules were observed 3-5 weeks after inoculation in the sacrificed animals. Dramatic impairment of spermatogenesis of both testes was found in 11 rats. Mating experiment confirmed infertility in 12 of 40 rats. Offsprings of the infected rats were significantly smaller than those of controls in terms of prenatal weights and birthweights.

Matrix-assisted laser desorption/ionization for sequencing single-stranded and double-stranded DNA

The DNA sequence of a single-stranded and double-stranded template was determined. The templates were sequenced using the chain termination method and cycle sequencing method and detected by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The sequencing products were analyzed successfully without the laborious and expensive methods for removal of the template. Direct sequencing of the double-stranded template was achieved with minimal post-reaction purifications, which could be extremely important for mutation analysis and clinical diagnosis. A systematic study of the mechanisms and kinetics of sequencing reactions was also performed. The details of this analysis and directions for future improvements of the quality of sequencing are presented.

Laser desorption mass spectrometry for point mutation detection

A point mutation can be associated with the pathogenesis of inherited or acquired diseases. Laser desorption mass spectrometry coupled with allele specific polymerase chain reaction (PCR) was first used for point mutation detection. G551D is one of several mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene present in 1-3% of the mutant CFTR alleles in most European populations. In this work, two different approaches were pursued to detect G551D point mutation in the cystic fibrosis gene. The strategy is to amplify the desired region of DNA template by PCR using two primers that overlap one base at the site of the point mutation and which vary in size. If the two primers based on the normal sequence match the target DNA sequence, a normal PCR product will be produced. However, if the alternately sized primers that match the mutant sequence recognize the target DNA, an abnormal PCR product will be produced. Thus, the mass spectrometer can be used to identify patients that are homozygous normal, heterozygous for a mutation or homozygous abnormal at a mutation site. Another approach to identify similar mutations is the use of sequence specific restriction enzymes which respond to changes in the DNA sequence. Mass spectrometry is used to detect the length of the restriction fragments generated by digestion of a PCR generated target fragment.

The study of 2,3,4-trihydroxyacetophenone and 2,4,6-trihydroxyacetophenone as matrices for DNA detection in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometric study of DNA detection using 2,3,4-trihydroxyacetophenone, 2,4,6-trihydroxyacetophenone, and their combination has been carried out systematically. The results show that a mixture of 2,4,6-trihydroxyacetophenone, 2,3,4-trihydroxyacetophenone and ammonium citrate with molar ratios of 2:1:1 serves as a good matrix for the detection of DNA, especially for samples containing a small quantity of DNA such as polymerase chain reaction product. The resolution and shot-to-shot reproducibility using this matrix are better than, and the MALDI sensitivity comparable to, that obtained when using 3-hydroxy picotinic acid (3-HPA), PA and ammonium citrate matrix (9:1:1). The mechanism of desorption/ionization using this matrix is discussed.

Urethane-protected alpha-amino acid N-carboxyanhydrides and peptide synthesis

The preparation, physical properties and analytical data are reported for seventy urethane-protected (Boc, Cbz, FMOC) amino acid N-carboxyanhydrides (UNCAs). Most of the UNCAs are crystalline and the X-ray diffraction patterns for several of these are described. UNCAs are stable to routine laboratory manipulations and can be stored for extended periods of time (1-2 years at below 0 degrees C). Most are completely stable to the conditions commonly employed for peptide synthesis. The correct choice of base is key for the successful introduction of urethane protecting groups into NCAs. N-Methylmorpholine is used for the introduction of FMOC, Cbz or Boc from the chloroformates, and pyridine is used for the introduction of the Boc group from Boc anhydride. UNCAs represent a unique class of preactivated, isolable and stable amino acid derivatives that generate no side products or co-products, other than CO2, during condensation reactions. The application of UNCAs in peptide synthesis in both solid phase and in solution is reviewed in detail.

Sweet and bitter taste: structure and conformations of two aspartame dipeptide analogues

The synthesis and X-ray diffraction analysis of two dipeptide taste ligands have been carried out as part of our study of the molecular basis of taste. The compounds L-aspartyl-D-alpha-methylphenylalanine methyl ester [L-Asp-D-(alpha Me)Phe-OMe] and L-aspartyl-D-alanyl-2,2,5, 5-tetramethylcyclopentanyl ester [L-Asp-D-Ala-OTMCP] elicit bitter and sweet taste, respectively. The C-terminal residues of the two analogues adopt distinctly different conformations in the solid state. The aspartyl moiety assumes the same conformation found in other dipeptide taste ligands with the side-chain carboxylate and the amino groups forming a zwitterionic ring with a conformation defined by psi, chi 1 = 157.7 degrees, -61.5 degrees for L-Asp-D-Ala-OTMCP and 151.0 degrees, -68.8 degrees for L-Asp-D-(alpha Me)Phe-OMe. In the second residue, a left-handed helical conformation is observed for the (alpha Me)Phe residue of L-Asp-D-(alpha Me)Phe-OMe with phi 2 = 49.0 degrees and psi 2 = 47.9 degrees, while the Ala residue of L-Asp-D-Ala-OTMCP adopts a semi-extended conformation characterized by dihedral angles phi 2 = 62.8 degrees and psi 2 = -139.9 degrees. The solid-state structure of the bitter L-Asp-D-(alpha Me)Phe-OMe is extended: while the crystal structure of the sweet L-Asp-D-OTMCP roughly adopts the typical L-shaped structure shown by other sweeteners. The data of L-Asp-D-(alpha Me)Phe-OMe are compared with those of its diastereoisomer L-Asp-L-(alpha Me)Phe-OMe. Conformational analysis of the two taste ligands in solution by NMR and computer simulations agrees well with our model for sweet and bitter tastes.

Revisit of MALDI for small proteins

Matrix-assisted laser desorption/ionization (MALDI) was used for several small proteins (such as insulin) and for peptides. It was found that the detection efficiencies of MALDI for the insulin B chain and the insulin A chain are drastically different. Similar phenomena were also observed for various types of peptides. The positive-ion signal of MALDI in detecting proteins or peptides was found to be greatly enhanced by the presence of a basic amino acid in their chains. The experimental results indicate that this enhancement may arise from proton transfer in solution by an acid-base reaction between the protein/peptide and matrix molecule. This pre-protonated mechanism provides a low energy barrier for the ionization of peptides in a MALDI process, and greatly reduces the energy threshold of MALDI. Matrix effects on the ionization mechanism are discussed.

A second regulatory gene, blaR1, encoding a potential penicillin-binding protein required for induction of beta-lactamase in Bacillus licheniformis

A second regulatory locus (blaR1) required for the induction of beta-lactamase synthesis in Bacillus licheniformis 749 was cloned and sequenced. The gene was located on a 5.2-kilobase-pair SphI DNA fragment which also contained the beta-lactamase (blaP) and repressor (blaI) genes. Bacillus subtilis BD224 carrying these three genes synthesized beta-lactamase on exposure to cephalosporin C, whereas Escherichia coli HB101 carrying the genes did not show any detectable induction of the enzyme. An open reading frame of 1,803 bases was identified as the blaR1 gene by subcloning and DNA sequencing. The gene started 2 bases downstream of the termination codon of bla1 and was preceded by a putative Shine-Dalgarno sequence (AAGGA) with a spacing of 5 bases. The deduced blaR1 product (601 amino acids) had a molecular weight of 68,425. Five transmembrane regions were predicted from the hydrophobicity profile. The region around Phe-Ala-Pro-Ala-Ser-Thr-Tyr-Lys (amino acids 398 to 405), which appeared to be located outside the membrane, was homologous to the binding regions of penicillin-binding proteins, including the beta-lactamases. The segment of 22 amino acids from 400 to 421 showed more than 70% homology to the penicillin-binding region of PBP 2 of E. coli. The blaR1 gene encodes a potential penicillin receptor which is required for the induction of beta-lactamase in B. licheniformis 749.