Biomedical subjects

D C Wang

Publications and source records attributed to D C Wang.

At least 19 recordsLinked to original sources

PubMed2006

Factors affecting growth factor activity in goat milk.

Growth factors that are present in goat milk may be responsible for its beneficial effects on the digestive system as described in ancient Chinese medical texts. To develop a nutraceutical product rich in growth factors for promoting gastrointestinal health, it is essential to collect milk with consistently high growth factor activity. Therefore, we investigated the factors affecting growth factor activity in goat milk. Among the 5 breeds of dairy goats tested, milk from Nubian goats had the highest growth factor activity. Tight-junction leakage induced by a 24-h milking interval did not increase growth factor activity in the milk. Milk collected from pregnant does had a significantly higher growth factor activity than milk collected postpartum. Growth factor activity decreased during the first 8 wk of lactation, fluctuated thereafter, and then increased dramatically after natural mating. During wk 1 to 8, growth factor activity was inversely correlated with milk yield and week of lactation. No correlation was observed during wk 9 to 29. After natural mating of the goats, the growth factor activity in the milk correlated significantly with somatic cell count and conductivity (a measure of membrane permeability), and correlated inversely with milk yield. Based on the above data, goat milk with higher growth factor activity could be selectively collected from Nubian pregnant does.

Animals↗

PubMed2003

Multivariate statistical study of heavy metal enrichment in sediments of the Pearl River Estuary.

The concentrations and chemical partitioning of heavy metals in the sediment cores of the Pearl River Estuary were studied. Based on Pearson correlation coefficients and principal component analysis results, Al was selected as the concentration normalizer for Pb, while Fe was used as the normalizing element for Co, Cu, Ni and Zn. In each profile, sections with metal concentrations exceeding the upper 95% prediction interval of the linear regression model were regarded as metal enrichment layers. The heavy metal accumulation mainly occurred at sites in the western shallow water areas and east channel, which reflected the hydraulic conditions and influence from riparian anthropogenic activities. Heavy metals in the enrichment sections were evaluated by a sequential extraction method for possible chemical forms in sediments. Since the residual, Fe/Mn oxides and organic/sulfide fractions were dominant geochemical phases in the enriched sections, the bioavailability of heavy metals in sediments was generally low. The 206Pb/207Pb ratios in the metal-enriched sediment sections also revealed the influence of anthropogenic sources. The spatial distribution of cumulative heavy metals in the sediments suggested that the Zn and Cu mainly originated from point sources, while the Pb probably came from non-point sources in the estuary.

China↗

PubMed2003

Structural genomics efforts at the Chinese Academy of Sciences and Peking University.

Structural genomics efforts at the Chinese Academy of Sciences and Peking University are reported in this article. The major targets for the structural genomics project are targeted proteins expressed in human hematopoietic stem/progenitor cells, proteins related to blood diseases and other human proteins. Up to now 328 target genes have been constructed in expression vectors. Among them, more than 50% genes have been expressed in Escherichia coli, approximately 25% of the resulting proteins are soluble, and 35 proteins have been purified. Crystallization, data collection and structure determination are continuing. Experiences accumulated during this initial stage are useful for designing and applying high-throughput approaches in structural genomics.

Academies and Institutes↗

PubMed2002

The mass transfer process and the growth rate of protein crystals.

In this paper, protein crystal growth is studied by a Mach-Zehnder interferometer and an image process system. The interference fringe images are recorded during the crystallization of tetragonal hen egg white lysozyme crystal. Concentration distributions of the protein solution are given from the interference fringe images recorded by the Mach-Zehnder interferometer with a real time servo system of a four-step phase shift. The mass transfer flux and the crystal growth rates are obtained from the concentration distribution. The results show that the observed rates are in accordance with those demonstrated by measurements of the experimental images; therefore the method for determining growth rate by the diffusion process is reasonable.

Crystallization↗

PubMed2001

Molecular scaffold of a new pokeweed antifungal peptide deduced by 1H nuclear magnetic resonance.

The antifungal peptide from seeds of Phytolacca americana (Pokeweed), designated PAFP-S hereinafter, is a recently found cationic peptide which consists of 38 amino acid residues and exhibits a broad spectrum of antifungal activity, including inhibition of certain saprophytic fungi and some plant pathogens. The secondary structure and three cysteine pairings have been investigated by 1H NMR analysis. The results show that the molecular scaffold of PAFP-S features a triple-stranded antiparallel beta-sheet knotted by a typical disulfide bridge motif, which characterizes the knottin fold. CD spectroscopy indicates a high stability of the molecule in solution. Therefore, PAFP-S should be a new member of the knottin structural family and the first antifungal peptide that adopts the knottin-like fold.

Amino Acid Motifs↗

PubMed2001

Overexpression, purification, crystallization and preliminary X-ray diffraction analysis of Cu,Zn superoxide dismutase from Peking duck.

The cDNA encoding Peking duck Cu,Zn superoxide dismutase (dSOD) was cloned and sequenced. The recombinant enzyme was overexpressed in Escherichia coli, purified to homogeneity and crystallized using the sitting-drop vapour-diffusion technique. Trigonal crystals of dSOD were obtained at 278 K at low ionic strength and around neutral pH. These crystals belong to space group P3(2)21, with unit-cell parameters a = 124.4, c = 163.5 A, gamma = 120 degrees. The asymmetric unit contains four dimers (eight monomers of Cu,Zn dSOD) and has a 56% solvent content, with a V(M) of 2.8 A(3) Da(-1). On a Rigaku R-AXIS IIc image-plate area-detector system, the crystal diffracted to 2.9 A. Unusual supermolecular double-helix packing with 9(2)2 non-crystallographic symmetry in crystals has been observed in the initial structural analysis.

Amino Acid Sequence↗

PubMed2001

Solution structure of PAFP-S: a new knottin-type antifungal peptide from the seeds of Phytolacca americana.

The three-dimensional solution structure of PAFP-S, an antifungal peptide extracted from the seeds of Phytolacca americana, was determined using 1H NMR spectroscopy. This cationic peptide contains 38 amino acid residues. Its structure was determined from 302 distance restraints and 36 dihedral restraints derived from NOEs and coupling constants. The peptide has six cysteines involved in three disulfide bonds. The previously unassigned parings have now been determined from NMR data. The solution structure of PAFP-S is presented as a set of 20 structures using ab initio dynamic simulated annealing, with an average RMS deviation of 1.68 A for the backbone heavy atoms and 2.19 A for all heavy atoms, respectively. For the well-defined triple-stranded beta-sheet involving residues 8-10, 23-27, and 32-36, the corresponding values were 0.39 and 1.25 A. The global fold involves a cystine-knotted three-stranded antiparallel beta-sheet (residues 8-10, 23-27, 32-36), a flexible loop (residues 14-19), and four beta-reverse turns (residues 4-8, 11-14, 19-22, 28-32). This structure features all the characteristics of the knottin fold. It is the first structural model of an antifungal peptide that adopts a knottin-type structure. PAFP-S has an extended hydrophobic surface comprised of residues Tyr23, Phe25, Ile27, Tyr32, and Val34. The side chains of these residues are well-defined in the NMR structure. Several hydrophilic and positively charged residues (Arg9, Arg38, and Lys36) surround the hydrophobic surface, giving PAFP-S an amphiphilic character which would be the main structural basis of its biological function.

Amino Acid Sequence↗

PubMed2001

A depressant insect toxin with a novel analgesic effect from scorpion Buthus martensii Karsch.

A new peptide named BmK dITAP3 from scorpion Buthus martensii Karsch (BmK) has been identified to possess a dual bioactivity, a depressant neurotoxicity on insects and an analgesic effect on mice. The bioassays also showed that the peptide was definitely devoid of the neurotoxicity on mammals, which indicated that the analgesic effect of BmK dITAP3 could not be ascribed to the syndromic effects of a mammalian neurotoxicity. BmK dITAP3 exhibited 43.0% inhibition efficiency of the analgesic effect on mice at a dose of 5 mg/kg and the FPU value of 0.5 microg/body (approximately 30 mg) on the fly larvae. The pI value and the molecular mass determined by MALDI-TOF MS for dITAP3 were 6.5 and 6722.7, respectively. Its first 15 N-terminal residues were determined by Edman degradation, based on which the full amino acid sequence was deduced from the cDNA sequence encoding the peptide with 3'-RACE. Circular dichroism and sequence based prediction analyses showed dITAP3 may have a similar molecular scaffold as the most scorpion toxins but with features of the more beta structures and much less of alpha helix. The details of the purification, characterization and sequencing as well as the sequence comparison with other depressant insect toxins and the correlation between the analgesic effect and the insect toxicity will be reported and discussed, respectively.

Amino Acid Sequence↗

PubMed2001

Crystallization and preliminary X-ray analysis of a depressant insect toxin from the scorpion Buthus martensii Karsch.

Depressant insect toxins are a distinct group of scorpion neurotoxins for which no three-dimensional structures are yet available. A depressant insect toxin named BmK dITAP3 from the scorpion Buthus martensii Karsch (BmK) has been purified and crystallized. Single crystals of dITAP3 grew in the presence of the detergent CYMAL-6 using the hanging-drop vapour-diffusion method with ammonium sulfate as precipitant. A set of diffraction data to 2.6 A resolution has been collected. Preliminary analysis of the diffraction data indicated that the crystal belonged to space group R3, with unit-cell parameters a = b = 73.29, c = 68.90 A, alpha = beta = 90, gamma = 120 degrees. Assuming two molecules in the asymmetric unit, the estimated solvent content is 53.4%.

Animals↗

PubMed2001

Electrophysiological characterization of BmK M1, an alpha-like toxin from Buthus martensi Karsch venom.

The present study investigates the electrophysiological actions of BmK M1, an alpha-like toxin purified from the venom of the scorpion Buthus martensi Karsch, on voltage-gated Na+ channels. Using the voltage clamp technique, we assessed the BmK M1 activity on the cardiac Na+ channel (hH1) functionally expressed in Xenopus oocytes. The main actions of the toxin are a concentration-dependent slowing of the inactivation process and a hyperpolarizing shift of the steady-state inactivation. This work is the first electrophysiological characterization of BmK M1 on a cloned Na+ channel, demonstrating that this toxin belongs to the class of scorpion alpha-toxins. Our results also show that BmK M1 can be considered as a cardiotoxin.

Animals↗

PubMed2001

A new insect neurotoxin AngP1 with analgesic effect from the scorpion Buthus martensii Karsch: purification and characterization.

An insect toxin named BmK AngP1 was purified from the venom of the scorpion Buthus martensii Karsch (BmK). It also shows an evident analgesic effect on mice, but is interestingly devoid of mammalian toxicity. Bioassay showed that the CPU value of AngP1 was 0.01 microg/body ( approximately 30 mg) for the excitatory insect toxicity and 43.0% inhibition efficiency for analgesia at a dose of 5 mg/kg. However, even at the dosage of 10 mg/kg no detectable toxicity on mice could be found. The isoelectric point (pI) value for AngP1 was 4.0, and its molecular mass analyzed by MALDI-TOF MS was 8141.0. The first 15 N-terminal residues of AngP1 were determined by Edman degradation and showed high similarity to that of other excitatory scorpion insect toxins. The circular dichroism spectroscopy measured on a JASCO J-720 system showed that there were 10.4% alpha-helix, 46.2% beta-strand and 14.1% turn structure in this peptide. Under two conditions single crystals of AngP1 were obtained.

Amino Acid Sequence↗

PubMed2001

Molecular characterization of an anti-epilepsy peptide from the scorpion Buthus martensi Karsch.

For a long time Asian scorpion Buthus martensi Karsch (BmK) has been used in Chinese traditional medicine to cure many diseases of nervous system. Here we report the purification and characterization of a pharmacologically active neurotoxin from the scorpion BmK. This toxin had little toxicity in mice and insects but was found to have an anti-epilepsy effect in rats, and is thus named as BmK anti-epilepsy peptide (BmK AEP). Its amino-acid sequence was determined by lysylendopeptidase digestion, Edman degradation and mass spectrographic analysis. Based on the determined sequence, the gene coding for this peptide was also cloned and sequenced by the 3' and 5' RACE methods. It encodes a precursor of 85 amino-acid residues including a signal peptide of 21 residues, a mature peptide of 61 residues and three additional residues Gly-Lys-Lys at the C-terminus. The additional Gly sometimes followed by one or two basic residues is prerequisite for the amidation of its C-terminus. C-terminal amidation was also verified by the molecular-mass determination of BmK AEP. This anti-epilepsy peptide toxin shares homology with other depressant insect toxins. The remarkable difference between them was mainly focused at residues 6, 7 and 39; these residues might relate to the unique action of BmK AEP.

Amino Acid Sequence↗

PubMed2001

Administration of chinese herbal medicines facilitates the locomotor activity in dystrophin-deficient mice.

The purpose of this study was to access the effects of chinese herbal medicines on Duchenne muscular dystrophy (DMD). We use dystrophin-deficient mice (mdx), an animal model of DMD, to evaluate the effect of chinese herbal medicines on locomotor activity. The consumption of water for each mouse was controlled during the three-month experimental session. Each mouse was allowed to drink 3 ml water with or without herbal medicines daily for three months. The estimated intake of chinese herbal medicine in adult mdx mouse with 30 g weight is 100 mg/kg per day, close to a dose used in human. The locomotor activity of the mdx mice was measured every month. Monitoring the locomotor activity of mdx mice after three-month administration of chinese herbal medicines, the results showed that liu-wei-di-huang-wan (LDW) and san-lin-pai-tsu-san (SPS) can facilitate locomotor activity with the parameters of horizontal activity, total distance, number of movements, movement time, vertical activity, number of vertical movements, vertical movement time, stereotypy, number of stereotyped movements, and stereotyped movement time. These results suggest that either LDW or SPS can act as a potent herbal medicine for the pharmacological treatment of DMD patients.

Analysis of Variance↗

PubMed2001

Scientific basis of spasticity: insights from a laboratory model.

A variety of central nervous system injuries, diseases, and developmental deficits can lead to motor disorders that present complex mixtures of symptoms. Those that have a fundamental similarity characterized by the appearance of exaggerated velocity-dependent resistance to the lengthening of skeletal muscles are called spasticity. Reports based on clinical observations of motor disorders have and continue to provide the essential database of information regarding the range and distribution of unifying and discordant features of spasticity. Laboratory investigations employing animal models of motor disorders following experimental lesions of the central nervous system have reproduced some of the neurophysiologic changes that accompany injury of the central nervous system in humans. Those experimental lesions produced by spinal cord contusion/compression reproduce many of the histopathologic features displayed in traumatic injury of the human spinal cord as well. Studies using this model have revealed not only changes in reflex threshold and amplitude but also alterations in fundamental rate-modulation processes that regulate reflex excitability during repetitive stimulation. This report characterizes insights obtained from a laboratory investigation in search of fundamental mechanisms that contribute to the development of spasticity and provides a vantage point for understanding therapeutic strategies for treatment of spasticity.

Animals↗

PubMed2000

Conformational correlation and coupled motion between residue A21 and B25 side chain observed in crystal structures of insulin mutants at position A21.

The C-terminal residue of the insulin A chain is invariant and kept as asparagine in all known insulin molecules from hagfish through birds to mammals. To get information on the role of this conserved residue, which is still unclear, the three-dimensional structures of four human insulin mutants, A21 Asn-->Gly, A21 Asn-->Asp, A21 Asn-->Ala, and A21 Asn-->Gln DesB30, were determined by X-ray crystallography. The four mutants crystallize separately into two kinds (rhombohedral and cubic) of crystals. In the refined structures, conformational correlation and coupled motion between the A chain C-terminal residue A21 and the B25 side chain was observed, in contrast to the nearly unchanged general structures as compared with the native insulin structures in their respective crystals. A detailed analysis suggests that residue A21 can affect insulin receptor binding by interaction with the B25 side chain and the B chain C-terminal segment to assist the B25 side chain rearranging into the 'active' conformation.

Crystallography, X-Ray↗

PubMed2000

The determination of RWJ-38705 (tramadol N-oxide) and its metabolites in preclinical pharmacokinetic studies using LC-MS/MS.

A rapid and reliable analytical method is described for the simultaneous determination of RWJ-38705 (tramadol N-oxide) and several of its major metabolites in the plasma of Sprague-Dawley rats and Beagle dogs. Sample preparation using solid phase extraction was followed by reversed phase liquid chromatography (LC) coupled with tandem mass spectrometric (MS/MS) detection in the positive ionization mode. The assay was linear for all analytes over concentrations ranging from approximately 6 to 2000 ng/ml. The inter-assay reproducibility was generally less than 15% while accuracy values were within 13% of theoretical. The overall recovery of the analytes ranged from approximately 40 to 64% in rat plasma and 53-75% in dog plasma. This assay has proven to be sensitive, specific and reproducible, and it has been readily implemented in preclinical PK studies. Representative plasma concentration versus time profiles resulting from administration of TNO to rats and dogs are presented in this communication.

Administration, Oral↗

PubMed2000

Crystallization and preliminary X-ray analysis of the thermostable sweet protein mabinlin II.

Mabinlin II is a sweet protein with the highest known thermostablility and is isolated from the seeds of Capparis masaikai Levl. grown in south China. Two crystal forms of mabinlin II were obtained using the hanging-drop vapour-diffusion method. One of them diffracts to 2.8 A resolution and belongs to space group P2, with unit-cell parameters a = 50.16, b = 50.17, c = 76.60 A, beta = 99.6 degrees. There are four molecules per asymmetric unit, with a solvent content of 35.3%.

Crystallization↗

PubMed2000

Crystallization and preliminary X-ray analyses of insect neurotoxins with analgesic effect from the scorpion Buthus martensii Karsch.

Three insect neurotoxins from the scorpion Buthus martensii Karsch, named BmK I1, BmK I4 and BmK I6, have been purified and crystallized. BmK I1 and BmK I4 show strong toxicity to insects, while BmK I6 is relatively weaker. They all exhibit an evident analgesic effect on mice; this is a novel biological function for scorpion insect toxins. Their crystals diffract to at least 3.5 (BmK I1), 2.8 (BmK I4), 2.8 (BmK I6 crystal form I) and 2.2 A (of BmK I6 crystal form II) resolution on an ordinary X-ray source. Crystals of BmK I1 belong to space group P6, with unit-cell parameters a = b = 66.2, c = 176.7 A. BmK I4 crystallized in the tetragonal space group I4, with unit-cell parameters a = b = 134.5, c = 60.6 A. BmK I6 has been crystallized in two forms: form I belongs to space group C2, with unit-cell parameters a = 46.5, b = 85.2, c = 32.6 A, beta = 110.5 degrees; form II belongs to space group R3, with the hexagonal unit-cell parameters a = b = 44.5, c = 164.7 A.

Amino Acid Sequence↗