On sex ratios at birth and in childhood.
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Asia↗
Biomedical subjects
H Cheng
Publications and source records attributed to H Cheng.
[The determination of vitamin D in fortified milk and other foods by high performance liquid chromatography (HPLC)].
An HPLC procedure for determination of vitamin D(VD) in fortified milk and food has been developed. The samples were saponified by adding KOH, ethanol and vitamin C at 75 degrees C for 30 min. The digest was extracted with hexane in multistep manner. The extract was washed with 5% KOH, distilled water and 55% ethanol, and evaporated under reduced pressure at 50 degrees C. The residue was dissolved in hexane, transferred to a coentrifuge tube, evaporated under N2 and then dissolved in 200 microL mobile phase. The latter was injected into a silica column (10 microm, 30 cm x 4 mm) for cleanup, eluted with mixture of cyclohexane-hexane containing 0.8% isopropanol and detected at UV 254nm. VD fraction was collected according to the retention time of standard, evaporized under N2, redissolved in 100 microL MeOH, and separated on a C18 column (10 microm, 30 cm x 4 mm) with MeOH/H2O (98:2) as eluent. VD2 and VD3 were eluted as a mixture under the conditions. Recoveries of the method were 94.8% to 99.7%. The average CV (n = 5) for within and between day measurements were 1.6% and 2.1% respectively. This method was already used to determine the content of vitamin D in milk powder, pulvis elementi compound, mixed proteins, dried meat floss, humanized milk power, children health drink, milk wheat powder and fortified milk. The method is simple, rapid and accurate.
Animals↗
[Separation of alpha-amino acids and peptides by chelated metal ion affinity chromatography].
The hydrolytic solution of proteins mainly contains free amino acids and peptides. The separation of amino acids and di- and tri-peptides is very significant and also a complicated work. This report presents a chelated metal ion affinity chromatographic (CMAC) method for the separation of alpha-amino acids and peptides. Sephadex G10 was used as the solid matrix. It was epoxy-activated by epichlorophydrin; then coupled with iminodiacetate (IDA) and chelated with copper ion to produce immobilized copper-ion affinity chromatographic packing. Some examples are given for the chromatography of model mixtures of L-Val, L-His, L-Tyr, L-Try, Tyr-Try dipeptides and protein hydrolyzing solution of fish. The separation was based on the different stabilities of copper complexes of alpha-amino acids, peptides and IDA-Sephadex G10. The components which form weak complexes with copper apparently move along with the solvent front. Alpha-amino acids-copper complexes with a stability comparable to that of copper-IDA-Sephadex G10 are retained on the matrix. Peptides form strong complexes and catch copper from the matrix. They are only slightly retained. The results showed that alpha-amino acids and peptides were completely separated under the experimental conditions.
Amino Acids↗
APC mutation and the crypt cycle in murine and human intestine.
Dysplastic colon adenomas are thought to arise from growth of clones of APC -/- colonic epithelial cells. Isolated clusters of dysplastic crypts are often observed in patients with familial adenomatous polyposis. These patients have genotype APC +/-, and the clusters of dysplastic crypts (called microadenoma or aberrant crypt foci) are thought to represent an early stage in the expansion of a mutant clone of APC -/- cells. It is thought that the growth of these clusters of mutant crypts results from crypt replication through a process similar to what occurs in the normal crypt cycle. We measured the relative replication rate of mutant crypts by analyzing the size of clusters of mutant crypts in APC +/- individuals and found that mutant APC -/- crypts replicate more rapidly than do normal APC +/- (i.e., nonneoplastic) crypts. In contrast, the replication rate of mutant crypts in Apc +/- mice is not significantly different from that of normal crypts, thus supporting previous findings that aberrant crypt foci do not contribute significantly to the colon adenoma population in adult Apc +/- mice. Intriguingly, we found an effect of Apc heterozygosity on the frequency of branching crypts in young mice.
Adenomatous Polyposis Coli↗
The pattern of monocyte recruitment in tumors is modulated by MCP-1 expression and influences the rate of tumor growth.
Macrophage infiltration is an important aspect of the host response to tumor growth. Tumor-associated macrophages often exhibit intratumoral or peritumoral infiltration patterns. However, the mechanism that mediates distinctive patterns of macrophage infiltration and their impact on tumor growth is not known. We studied macrophage infiltration and the effect of this infiltration on tumor growth in mice inoculated with four human tumor cell lines. We report here that tumor cells producing high levels of monocyte chemoattractant protein-1 (MCP-1) had earlier recruitment of intratumoral macrophages than did lower producers and nonproducers. These MCP-1 high producers also had a lower tumor take rate than tumors that produced little or no MCP-1. The importance of early recruitment of monocytes was further demonstrated by introduction of fMLP (a chemotactic peptide) to the tumor sites. Administration of fMLP abolished the tumor formation when applied at the time of tumor-cell inoculation. When injection of fMLP was delayed, tumor growth was slowed but not eliminated. We also demonstrated that all MCP-1-producing tumors exhibited both intratumoral and peritumoral macrophage patterns, whereas MCP-1 nonproducers exhibited a peritumoral macrophage pattern only. The number of intratumoral macrophages was negatively correlated with tumor size. Collectively, our results suggest that (a) early recruitment of monocytes inhibits tumor growth; and (b) early intratumoral macrophage infiltration in vivo corresponds to the level of MCP-1 produced by tumors in vitro. In contrast, recruitment of neutrophils was not negatively correlated with tumor growth. Thus, early recruitment of macrophages may be beneficial to cancer patients.
Animals↗
Characteristics of risk-taking behaviors, HIV and AIDS knowledge, and risk perception among young males in southwest China.
A cross-sectional survey was undertaken to describe risk-taking behaviors and to assess the knowledge and risk perception of HIV and AIDS among young males aged 18 to 29 years in 82 villages in Longchuan, Yunnan, China, in 1994. Information on demographic, behavioral, and drug-using factors, and knowledge of HIV transmission and prevention, and risk perception was collected using an interviewer-administered anonymous questionnaire. A total of 1,548 individuals were interviewed and 433 drug users, including 52 nonsharing injectors and 140 sharing injectors, were identified. Over half the individuals scored 0 on HIV knowledge, but knowledge was greater among nonsharing drug injectors. Most drug injectors had initiated drug injection after 1990. The reported incidence continues to increase in all three major ethnic groups. Sharing of equipment was common (73%) among injectors. Drug users were four times more likely to have had premarital or extramarital sex, but condoms were used by only 2.5%. Thus, factors promoting spreading of HIV are common in this area. We recommend that a community-based intervention program, targeting both young men and women, be implemented and evaluated in Longchuan as soon as possible.
Acquired Immunodeficiency Syndrome↗
International clinical trials of HIV vaccines: II. phase I trial of an HIV-1 synthetic peptide vaccine evaluating an accelerated immunization schedule in Yunnan, China.
A Phase 1, double-blind, placebo controlled trial was conducted in Longchuan County, China, to evaluate the safety and immunogenicity of a prototype HIV-1 synthetic peptide vaccine in a target population at risk for HIV infection, and to establish the infrastructure for future large-scale HIV vaccine efficacy trials. Subjects were randomly assigned to receive 100 microg or 500 microg of vaccine or alum placebo, and were given three injections at an accelerated 0, 1, and 2 month schedule. The vaccine was well tolerated with no significant local or systemic reactions observed in any subjects. Fifty-five percent (100 microg dose) and 64% (500 microg dose) of subjects who received the vaccine produced binding antibody to the immunogen as determined by ELISA. However, HIV-1 (MN) neutralizing antibody was detected in only 23% (3/13) of subjects with detectable HIV-1 specific binding antibody. It was concluded that this prototype HIV-1 synthetic peptide vaccine was well tolerated, safe and immunogenic, and that a 0, 1, 2 month schedule was not as effective in stimulating HIV-1 specific neutralizing antibodies compared with previous trials utilizing a 0, 1, 6 month schedule. Finally, this trial demonstrated that well-designed HIV vaccine trials can be performed at this clinical trials site in Yunnan, China, and that this site should be considered for conducting larger safety, immunogenicity and efficacy trials of candidate HIV vaccines.
AIDS Vaccines↗
[Preliminary studies of auditory fusion frequency in noise effects].
Auditory fusion frequency (AFF) of impulse sound and paired pitch in 80 workers exposed to noise and 60 non-exposed ones were measured to study the relationship between AFF and auditory fatigue. AFF test software was made by the authors themselves, and a stimulating sound signal was evoked in a personal computer. Relationship between AFF in non-exposed workers and their ages was explored, and AFF in exposed ones before and after their exposure was compared. Results showed that no relationship between AFF and their sex and ears in non-exposed group was found. There was a significant difference in AFF between groups of 50-59-year and less than or equal to 49-year. Stimulating sound was more sensitive in its carrier wave or center frequency of 1,000 Hz, and paired pitch has higher value in screening for subjects with auditory threshold shift at about 1/40 octave band. There was significant consistency in transient auditory threshold shift, an important indicator of AFF and auditory fatigue. Measurement of AFF is more stable, repeatable and less deviated, and needs only simple acoustic conditions. Hence, it is a practical superthreshold audiometry.
Adult↗
[Effects of vasoactive intestinal peptide, alpha-chymotrypsin, pancreozymin, lipase, phospholipase A2 and collagenase on the viscoelasticity properties of red blood cell suspension].
Using Low Shear-30 Rheometer, we studied the effects of vasoactive intestinal peptide, alpha-chymotrypsin, pancreozymin, lipase, phospholipase A2 and collagenase on the viscoelasticity properties of RBC suspension. The result showed that these drugs could increase the values of eta 0.512 and A. I. It suggests that these drugs could increase the degree of RBC aggregation. Among the drugs and concentrations, there is no significant difference.
Blood Viscosity↗
[Experimental study on porous hydroxyapatite ceramics in repair of skull bone defect of rabbit].
In order to investigate the possibility of porous hydroxyapatite ceramics (HAC) in the repair of skull bone defect, twenty-four rabbits were used. The bone defect model was created by operation to obtain a defect in parietal bone in a size of 1 cm x 1 cm. Filled the defect with HAC and methyl-methacrylate-syrene copolymer (MMAS) to fill the defect as control. At 1st, 2nd and 3rd months after operation, behavior of the rabbits was observed and then these animals were sacrificed and specimens were examined under microscope. Results showed as follows: after operation, behavior of all animals were normal. By histological examination, it was found that in HAC group, there were granulation tissue, fibrous tissue and newly formed vessels grew into the pores and the osteoblasts formed osseous trabeculae. There was no inflammatory cell infiltration. In the MMAS grafted asea, there was formation of fibrous membrane. It suggested that HAC might be a good material for bone substitute in repair of skull bone defect.
Animals↗
TCFL4: a gene at 17q21.1 encoding a putative basic helix-loop-helix leucine-zipper transcription factor.
TCFL4 (transcription factor like 4) is the HGMW-approved symbol for the gene of a widely expressed putative basic helix-loop-helix leucine-zipper (bHLH-zip) transcription factor which is located 3' to HSD17B1 (17-beta-hydroxysteroid dehydrogenase gene) at 17q21.1, centromeric to the BRCA1 (a gene implicated in familial breast cancer) locus. We report the human gene structure and the murine cDNA sequence of two variants, about 1.5 and 2.2 kb in size. The deduced protein is highly conserved between mouse and man.
Amino Acid Sequence↗
Ca2+ diffusion and sarcoplasmic reticulum transport both contribute to [Ca2+]i decline during Ca2+ sparks in rat ventricular myocytes.
1. We sought to evaluate the contribution of the sarcoplasmic reticulum (SR) Ca2+ pump (vs. diffusion) to the kinetics of [Ca24]i decline during Ca2+ sparks, which are due to spontaneous local SR Ca2+ release, in isolated rat ventricular myocytes measured using fluo-3 and laser scanning confocal microscopy. 2. Resting Ca2+ sparks were compared before (control) and after the SR Ca2(+)-ATPase was either completely blocked by 5 microM thapsigargin (TG) or stimulated by isoprenaline. Na(+)-Ca2+ exchange was blocked using Na(+)-free, Ca(2+)-free solution (0 Na+, O Ca2+) and conditions were arranged so that the SR Ca2+ content was the same under all conditions when Ca2+ sparks were measured. 3. The control Ca2+ spark amplitude (281 +/- 13 nM) was not changed by TG (270 +/- 21 nM) or isoprenaline (302 +/- 10 nM). However, the time constant of [Ca2+]i decline was significantly slower in the presence of TG (29.3 +/- 4.3 ms) compared with control (21.6 +/- 1.5 ms) and faster with isoprenaline (14.5 +/- 0.9 ms), but in all cases was much faster than the global [Ca2+]i decline during a control twitch (177 +/- 10 ms). 4. The spatial spread of Ca2+ during the Ca2+ spark was also influenced by the SR Ca2+ pump. The apparent 'space constant' of the Ca2+ sparks was longest when the SR Ca2+ pump was blocked, intermediate in control and shortest with isoprenaline. 5. We conclude that while Ca2+ diffusion from the source of Ca2+ release is the dominant process in local [Ca2+]i decline during the Ca2+ spark, Ca2+ transport by the SR contributes significantly to both the kinetics and spatial distribution of [Ca2+]i during the Ca2+ spark.
Adrenergic beta-Agonists↗
Spontaneous intestinal carcinomas and skin neoplasms in Msh2-deficient mice.
Hereditary nonpolyposis colorectal cancer is associated with defects in DNA mismatch repair. Here, we characterize tumor susceptibility of the recently described Msh2-deficient mouse model. Within the first year of observation, all homozygous mice succumbed to disease, with lymphomas observed in at least 80% of the cases. The majority (70%) of animals 6 months or older developed intestinal neoplasms associated with APC inactivation. Microsatellite instability was more common in carcinomas than in adenomas, but uncommon in normal tissues. Some animals (7%) developed a variety of skin neoplasms analogous to the Muir-Torre syndrome. Msh2-/- mice implicate a direct role for mismatch repair in several neoplasms with striking phenotypic similarities to humans.
Adenomatous Polyposis Coli Protein↗
Spinal cord repair in adult paraplegic rats: partial restoration of hind limb function.
Complete spinal cord gaps in adult rats were bridged with multiple intercostal nerve grafts that redirected specific pathways from white to gray matter. The grafted area was stabilized with fibrin glue containing acidic fibroblast growth factor and by compressive wiring of posterior spinal processes. Hind limb function improved progressively during the first 6 months, as assessed by two scoring systems. The corticospinal tract regenerated through the grafted area to the lumbar enlargement, as did several bulbospinal pathways. These data suggest a possible repair strategy for spinal cord injury.
Animals↗
Human ferredoxin: overproduction in Escherichia coli, reconstitution in vitro, and spectroscopic studies of iron-sulfur cluster ligand cysteine-to-serine mutants.
Human ferredoxin, the human equivalent of bovine adrenodoxin, is a small iron-sulfur protein with one [2Fe-2S] cluster. It functions, as do other vertebrate ferredoxins, to transfer electrons during the processes of steroid hormone synthesis. A DNA fragment encoding the mature form of human ferredoxin was cloned into an expression vector under control of the T7 RNA polymerase/promoter system. The protein was overproduced in Escherichia coli, and the [2Fe-2S] cluster was incorporated into the protein by in vitro reconstitution. The overall yield was approximately 30 mg of purified, reconstituted ferredoxin per liter of culture. Four of the five cysteines in human ferredoxin are coordinated to the iron-sulfur cluster. First, the non-ligand cysteine (cysteine-95) was mutated to alanine, and then double mutants were created in which each of the other four cysteines (at positions 46, 52, 55, and 92) were mutated individually to serine. The wild-type ferredoxin and each of the five mutant proteins were studied by UV-visible spectroscopy and electron paramagnetic resonance spectroscopy. The EPR gav values of all five mutants were very similar to that of wild-type human ferredoxin. In the reduced state, three of the cysteine-to-serine mutants exhibited axial EPR spectra similar to that of wild-type, but one of the double mutants (C52S/C95A) exhibited a rhombic EPR spectrum. The UV-visible spectroscopic properties of the wild-type and the C95A mutant ferredoxins were identical, but those of the other cysteine-to-serine mutant proteins of human ferredoxin were quite different from those of the wild-type protein and each other. These results, along with those from cysteine-to-serine mutations in other ferredoxins, provide the basis for a more comprehensive theoretical and practical understanding of the features important to the ligation of [2Fe-2S] clusters, although they do not yet permit determination of which two cysteines ligate Fe(II) and which ligate Fe(III) in the reduced protein.
Amino Acid Sequence↗
Dimer Growth, Structural Transition, and Antiferromagnetic Ordering of Small Chromium Clusters.
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Journal Article↗
MSH2 deficiency contributes to accelerated APC-mediated intestinal tumorigenesis.
Accelerated intestinal tumorigenesis is probable in hereditary nonpolyposis colorectal cancer, a condition associated with germ line DNA mismatch repair (MMR) gene defects, and is believed to be caused by rapid accumulation of replication errors in critical genes, such as the APC (adenomatous polyposis coli) tumor suppressor gene. To study the potential contribution of MMR genes to accelerated intestinal tumorigenesis, we crossed the Min mouse, heterozygous for a germ line mutation of Apc, with an MMR gene (Msh2)-deficient mouse. MSH2 deficiency resulted in the development of many colonic aberrant crypt foci, as well as reduced survival of the mice, secondary to both a greater number and more rapidly developing adenomas. The mechanism of inactivation of the wild-type Apc allele depended on MSH2 status. In the presence of functional MSH2, all tumors demonstrated loss of heterozygosity. In contrast, whereas all adenomas were APC negative by immunostaining, only 5 of 34 adenomas from Apc+/-/Msh2-/- mice demonstrated loss of heterozygosity of the wild-type Apc allele, suggesting that somatic Apc mutations are responsible for the additional tumors. These findings provide evidence for the important role of MMR genes in accelerated intestinal tumorigenesis, thus supporting more aggressive surveillance strategies to prevent colorectal cancer in hereditary nonpolyposis colorectal cancer.
Adenoma↗
The molecular biology of the Na(+)-Ca2+ exchanger and its functional roles in heart, smooth muscle cells, neurons, glia, lymphocytes, and nonexcitable cells.
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Animals↗