China marks World Population Day. Address by Chang Congxuan.
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Asia↗
Biomedical subjects
C Chang
Publications and source records attributed to C Chang.
[Determination of beryllium in geological samples with slurry sampling and probe atomization in graphite furnace atomic absorption spectrometry].
A method of loading a slurry prepared from a solid sample for analysis of beryllium in geological samples using graphite furnace atomic absorption spectrometry was approached by combining slurry sampling with probe atomization. The factors that influence the performances of beryllium including ashing and atomization temperature, atomization surfaces (probe and tube), the materials of the tube and probe, and the use of matrix modifiers were investigated. The results show that the determination of beryllium in geological samples could be performed by direct slurry sampling with the use of calcium as the matrix modifier for a calibration established with aqueous standards. The relative standard deviations (RSD) of the method were 3.1-5.2%. The analytical results of the geological reference samples were consistent with the certified values. The activation energy during beryllium atomization was calculated using the Arrhenius graph method which was in good with the bonding energy of Be-O.
English Abstract↗
The similarity between parents and offspring in facial soft tissue: a frontal-view study.
Similarities between parents and their offspring in facial soft tissue features were investigated. Fifty boys and fifty girls aged 9-10 years, excluding those with congenital anomalies, were selected. Frontal photographs of the family (father, mother and offspring) were taken and twenty-nine landmarks located on each enlarged tracing made from a photograph. Each landmark was digitised into (x, y) co-ordinate values from which the area and linear ratio dimensions were calculated and statistically evaluated. Results indicated that: (1) The nose was the feature that was most significantly correlated between parents and offspring. (2) The similarities between parents and offspring were closer for the relative positions of other features to the eyes than for individual features of the face. In general, the correlations between 'midparents' (the mean value of both parents) and offspring were higher than those between one parent and offspring. (3) The correlations between parents and offspring for size were higher than those for shape. (4) The similarities between mothers and offspring were closer than those between fathers and offspring. Furthermore: among four pairs of father/son, father/daughter, mother/son and mother/daughter, the mother/daughter pair had the highest correlation and the father/son pair had the lowest, which appears to be related to X-chromosome inheritance.
Adult↗
Hemichorea-hemiballism: an explanation for MR signal changes.
PURPOSE: Some cases of hemichorea-hemiballism (HCHB) are associated with a hyperintense putamen on T1-weighted MR images, the cause of which remains unclear. Our purpose was to determine the cause and significance of these MR signal changes. METHODS: We analyzed the clinical and neuroimaging findings in 10 patients with HCHB, focusing on locations of the hyperintense lesions on T1-weighted images, comparing them with those on CT scans, and evaluating their changes after years of follow-up. A biopsy was performed in one patient. RESULTS: Seven patients had hyperglycemia and two had cortical infarcts. HCHB recurred in four patients. A hyperintense putamen preceded the occurrence of HCHB in two patients. T1-weighted MR images revealed hyperintense lesions limited to the ventral striatum in six patients. Hyperintense lesions extended to the level of the midbrain in one patient and persisted for as long as 6 years in another patient. T2-weighted MR images revealed slit-shaped cystic lesions in the lateral part of the putamina 2 to 6 years after the onset of symptoms in two patients. A biopsy specimen from the hyperintense putamen in one patient revealed a fragment of gliotic brain tissue with abundant gemistocytes. Proton MR spectroscopy of the specimen showed an increase in lactic acid, acetate, and lipids, and a decrease in N-acetylaspartate and creatine, suggesting the presence of pronounced energy depletion and neuronal dysfunction. CONCLUSION: Gemistocytes are sufficient to explain the shortening of T1 relaxation time. Our investigation suggests that neurons in the ventral striatum and striatonigral pathway may play a critical role in generating ballism.
Adolescent↗
Avascular necrosis.
There are multiple conditions associated with the development of osteonecrosis including trauma, hemoglobinopathies, Caisson disease, local infiltrative lesions, hypercortisolism, alcohol consumption, chronic renal failure, and autoimmune disease.
Angiography↗
Androgen receptors in ovarian tumors: correlation with oestrogen and progesterone receptors in an immunohistochemical and semiquantitative image analysis study.
The expression and distribution of androgen, estrogen and progesterone receptors was examined by immunohistochemical staining in 31 paraffin-embedded sections from ovarian tumors and the results were assessed by semiquantitative image analysis. Immunohistochemical staining showed heterogeneous patterns of steroid receptor distribution, with mainly nuclear immunoreactivity. Eighty-four percent of benign and malignant ovarian tumors expressed androgen receptors (AR), 74.19% estrogen receptors (ER) and 41.16% progesterone receptors (PR). All benign tumors showed immunoreactivity for the three steroid receptors. Malignant tumors expressed higher AR and ER histochemical scores (H-scores) than PR (82% vs 71% vs 39%). The incidence and expression levels of the steroid receptors varied widely in the different histological types of malignant tumors. Spearman rank analysis showed a positive significant (P < 0.05) correlation between AR- and ER and between ER- and PR-H-scores. In malignant ovarian tumors, neither AR, ER nor PR immunohistochemical scores correlated with tumor FIGO stage. Densitrometric analysis of immunostained steroid receptors is a valid method for assessing the steroid status, because it reduces subjective elements in scoring sections and increases the reliability of results. The high incidence of AR expression confirms the functional role of AR in ovarian tumors and suggests that the determination of AR content in ovarian cancer could have prognostic value.
Densitometry↗
Cell fate determination in embryonic ectoderm.
During gastrulation in vertebrates the cells of the embryonic ectoderm give rise to epidermal progenitors in the ventral side and neural progenitors in the dorsal side. Despite many years of scrutiny, the molecular basis of these important embryonic cell fate decisions have not been solved. Only recently have we witnessed swift progress in the quest for factors involved in neural and epidermal induction. Several of what seem to be bona fide in vivo neural and epidermal inducers have been cloned, and the mechanism of their functions in embryos is also beginning to be understood. These new molecular results have revolutionized our view on the patterning of embryonic ectoderm and suggest that while the induction of epidermis requires instructive inductive signals, the establishment of neural fate occurs by default when epidermal inducers are inhibited. In this review, we discuss recent advances of our knowledge on epidermal and neural induction in the context of the "default model". We will then address the process of neurogenesis as well as recent findings on neural patterning. Emphasis is placed on, but not limited to, discoveries made in Xenopus, as most of our progress in understanding the ectodermal patterning is obtained from studies using this organism.
Animals↗
Comparison of cerebral occipital gray and parietal white matter metabolite differences using PRESS and STEAM at different echo times.
BACKGROUND: Reports regarding the differences in metabolite ratios with different echo times (TEs) at various brain regions are rare. The purpose of this study is to investigate in Chinese the cerebral metabolite ratios in gray matter (GM) and white matter (WM) using both STEAM and PRESS techniques at TEs of 30 ms and 136 ms, respectively. MATERIALS AND METHODS: Using GE Signa 1.5 T Scanner with STEAM and PRESS sequences, automated single voxel localized proton magnetic resonance spectroscopy (1H-MRS) were applied to identify the metabolite ratio differences in cerebral parietal white and occipital gray matter of healthy volunteers. RESULTS: Metabolite ratios between GM and WM were significantly different in N-acetyl aspartate/creatine (Cr), choline/Cr and myo-inositol/Cr. There were also significant differences in metabolite ratios when different echo times were applied. CONCLUSION: Reliable metabolite ratios at different brain regions can be obtained using automated data acquisition and spectral processing in single voxel localized 1H-MRS. This technique may remove user-dependent bias and provide more efficient and consistent ways to analyze the spectral data. However, one must be careful in interpreting spectroscopic data based on different regions and acquisition parameters.
Adult↗
Epidemiology of immediate and early trauma deaths at an urban Level I trauma center.
The objective of this study is to identify and differentiate the injury patterns and causes of death among patients who died within the 1st hour and those in the period between 1 and 48 hours after hospital admission. Information was collected from the 1994 to 1996 trauma data base at an urban Level I trauma center. The records of 155 trauma patients who died within the 1st hour (immediate trauma death, ITD) and between 1 and 48 hours (early trauma death, ETD) were examined retrospectively. Total and constituent Injury Severity Score (ISS), Trauma Score (TS), and Glasgow Coma Score were analyzed. ITDs constituted 49 per cent of all deaths within 48 hours. Blunt mechanisms accounted for 37 per cent of ITDs and 40 per cent of ETDs (not significant), whereas penetrating trauma accounted for 59 per cent of ITDs and 56 per cent of ETDs (not significant). Exsanguination most commonly caused death among ITDs (54%) and head injury (51%) among ETDs (P < 0.01). Patients who died within the 1st hour had higher ISS (42.6 +/- 23.2, P < 0.03), lower TS (1.7 +/- 1.9, P < 0.0001), and lower Glasgow Coma Score (3.1 +/- 1.1, P < 0.0001) than those who died after the 1st hour. Patients with ITD had a significantly worse chest ISS than those with ETD (47.4 +/- 28.6 vs 19.0 +/- 19.1, P < 0.0001). We conclude that 1) ITD is caused primarily by exsanguination, whereas ETD is largely due to the sequelae of severe neurologic injury; 2) ITD has a significantly lower TS and higher ISS than ETD; and 3) thoracic injuries are more severe among patients with ITDs than among those with ETDs. The severity of thoracic injury among ITDs suggests that rapid surgical intervention is critical during the resuscitation of these severely injured patients.
Adolescent↗
Expression of human aldehyde dehydrogenase-3 associated with hepatocellular carcinoma: promoter regions and nuclear protein factors related to the expression.
The human ALDH3 gene is constitutively expressed in stomach, lung, esophagus, and cornea, but hardly detectable in the normal liver. However, it is highly activated in the hepatocellular carcinoma tissues from approximately 50% of patients. The nuclear DNA binding factors exist in both ALDH3-positive cancerous liver and ALDH3-positive HepG2 cells, but not in ALDH3-negative Hep3B cells and normal liver tissues. South-western blot hybridization showed the existence of two nuclear-binding protein components, 35 and 14 kDa, in ALDH3-positive cancerous liver tissues. These two DNA binding proteins were not found in normal stomach tissues and stomach carcinoma KATO III cells. DNaseI footprint analysis identified two protective regions within the ALDH3 promoter. The first protected region has one putative CCAAT-box and one putative Sp1-site. The second protected region contains a putative HiNF-A binding sequence. These findings suggest that a high level of expression of ALDH3 in cancerous liver tissues resulted from the expression or activation of at least two nuclear proteins reacting to the ALDH3 promoter region.
Alcohol Dehydrogenase↗
A branched DNA signal amplification assay for quantification of nucleic acid targets below 100 molecules/ml.
The branched DNA hybridization assay has been improved by the inclusion of the novel nucleotides, isoC and isoG, in the amplification sequences to prevent non-specific hybridization. The novel isoC, isoG-containing amplification sequences have no detectable interaction with any natural DNA sequence. The control of non-specific hybridization in turn permits increased signal amplification. Addition of a 14 site preamplifier was found to increase the signal/noise ratio 8-fold. A set of 74 oligonucleotide probes was designed to the consensus HIV POL sequence. The detection limit of this new HIV branched DNA amplifier assay was approximately 50 molecules/ml. The assay was used to measure viral load in 87 plasma samples of HIV- infected patients on triple drug therapy whose RNA titers were <500 molecules/ml. In all 11 patients viral load eventually declined to below the detection limit with the new assay.
Adenosine↗
Exon/intron structure of aldehyde dehydrogenase genes supports the "introns-late" theory.
Whether or not nuclear introns predate the divergence of bacteria and eukaryotes is the central argument between the proponents of the "introns-early" and "introns-late" theories. In this study we compared the goodness-of-fit of each theory with a probabilistic model of exon/intron evolution and multiple nonallelic genes encoding human aldehyde dehydrogenases (ALDHs). Using a reconstructed phylogenetic tree of ALDH genes, we computed the likelihood of obtaining the present-day ALDH sequences under the assumptions of each competing theory. Although on the grounds of its own assumptions each theory accounted for the ALDH data significantly better than its rival, the introns-early model required frequent intron slippage, and the estimated slippage rates were too high to be consistent with reported correlations between the boundaries of ancient protein modules and the ends of ancient exons. Because the molecular mechanisms proposed to explain intron slippage are incapable of providing such high rates and are incompatible with the observed distribution of introns in higher eukaryotes, the ALDH data support the introns-late theory.
Aldehyde Dehydrogenase↗
Identification of the human aldolase A gene as the first induced target for the TR2 orphan receptor, a member of the steroid hormone receptor superfamily.
The human TR2 orphan receptor (TR2) is a member of the steroid/thyroid hormone receptor superfamily that regulates the transcription of complex gene networks and subsequently controls diverse aspects of growth, development, and differentiation. In the present study, we have found that the TR2 is one of the M1 site (nucleotide numbers 2017-2034, 5'-AAAAGGGCAGGGGTCATT-3') binding proteins of the muscle-specific pM promoter in the human aldolase A gene. Electrophoretic mobility shift assay (EMSA) showed a specific binding with high affinity (dissociation constant = 4.6 nM) between the TR2 and the M1 element. Circular permutation assay revealed a localized DNA flexibility induced by the TR2 binding, and the bend angle was estimated to be 73 +/- 2 degrees. Furthermore, a dual-luciferase reporter gene assay demonstrated that the TR2 may enhance the expression of luciferase activities via the wild-type M1 site but not the mutant M1 element in human QM7 muscle myoblasts. In conclusion, our data represent the first case of demonstrating that the TR2 may serve as a transcriptional inducer in muscle-specific aldolase A gene expression.
Base Sequence↗
Cloning and characterization of TDD5, an androgen target gene that is differentially repressed by testosterone and dihydrotestosterone.
By using mRNA polymerase chain reaction differential display technique (DDPCR), we have identified one early responsive cDNA fragment, TDD5, from a 5alpha-reductase-deficient T cell hybridoma. The DDPCR profiles of TDD5 suggest that its expression can be repressed by testosterone (T) within 2 hr. More importantly, both DDPCR and Northern blot analysis further demonstrated that the expression of TDD5 was differentially repressed by T and dihydrotestosterone (DHT) at the mRNA level. To our knowledge, this is the first androgen target gene to show a preference in response to T over DHT in cell culture. TDD5 is expressed in several tissues with particular abundance in kidney. Full-length TDD5 cDNA (2,916 bp) encodes a protein with a calculated molecular weight of 42,000. Finally, our animal studies further confirm that TDD5 mRNA levels can be repressed to the basal level 8 hr after DHT administration. The isolation and characterization of the early-responsive androgen target gene TDD5 and the fact that TDD5 mRNA level can be differentially regulated by T and DHT may provide a useful tool to study the molecular mechanism of androgen preference on target gene regulation.
3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
Identification of direct repeat 4 as a positive regulatory element for the human TR4 orphan receptor. A modulator for the thyroid hormone target genes.
While the TR4 orphan receptor (TR4) is able to repress the expression of its target genes via its interaction with the direct repeat 1-hormone response element (DR1-HRE) and DR2-HRE, we now report that TR4 can also induce the transcriptional activity of the reporter gene containing a DR4-HRE via chloramphenicol acetyltransferase assay. Electrophoretic mobility shift assay and Scatchard analysis reveal a strong binding affinity (dissociation constant = 2 nM) between TR4 and DR4-HRE. The induction mediated by TR4 was detected not only in the synthetic DR4-HRE but also in some genes, such as rat alpha-myosin heavy-chain and S14 genes, containing the DR4 or DR4-like motif, which have been suggested to be the response elements for a thyroid hormone receptor. Our data also demonstrate this TR4-mediated gene induction is TR4 dose- and DR4 sequence-dependent. Together, our data suggest that DR4-HRE can be a positive regulatory element for TR4, which may be able to induce the transcriptional activity of the genes containing such positive HREs.
Animals↗
Crystal structure of thermostable alpha-amylase from Bacillus licheniformis refined at 1.7 A resolution.
alpha-Amylases (alpha-1,4-glucan-4-glucanohydrolase, E.C.3.2.1.1) catalyze the cleavage of alpha-1, 4-glucosidic linkages of starch components, glycogen, and various oligosaccharides. Thermostable alpha-amylases from Bacillus species are of great industrial importance in the production of corn syrup or dextrose. Thermostable alpha-amylase from Bacillus licheniformis, a monomeric enzyme with molecular mass of 55,200 Da (483 amino acid residues), shows a remarkable heat stability. This enzyme provides an attractive model for investigating the structural basis for thermostability of proteins. The three-dimensional structure of thermostable alpha-amylase from Bacillus licheniformis has been determined by the multiple isomorphous replacement method of X-ray crystallography. The structure has been refined to a crystallographic R-factor of 19.9% for 58,601 independent reflections with F0 > 2 sigma F0 between 8.0 and 1.7 A resolution, with root mean square deviations of 0.013 A from ideal bond lengths and 1.72 degrees from ideal bond angles. The final model consists of 469 amino acid residues and 294 water molecules. Missing from the model are the N- and C-termini and the segment between Trp182 and Asn192. Like other alpha-amylases, the polypeptide chain folds into three distinct domains. The first domain (domain A), consisting of 291 residues (from residue 3 to 103 and 207 to 396), forms a (beta/alpha)8-barrel structure. The second domain (domain B), consisting of residues 104 to 206, is inserted between the third beta-strand and the third alpha-helix of domain A. The third C-terminal domain (domain C), consisting of residues 397 to 482, folds into an eight-stranded antiparallel beta-barrel. Neither calcium ion nor chloride ion is located near the active site. This study reveals the architecture of the thermostable alpha-amylase from Bacillus licheniformis. By homology with other alpha-amylases, important active site residues can be identified as Asp231, Glu261, and Asp328, which are all located at the C-terminal end of the central (beta/alpha)8-barrel. Since many of the stabilizing and destabilizing mutations obtained so far fall in domain B or at its border, this region of the enzyme appears to be important for thermostability. The factors responsible for the remarkable thermostability of this enzyme may be increased ionic interactions, reduced surface area, and increased packing interactions in the interior.
Amino Acid Sequence↗
Smad5 induces ventral fates in Xenopus embryo.
The Smad proteins have been implicated in the intracellular signaling of transforming growth factor-beta (TGF-beta) ligands. Here we describe the function of Smad5 in early Xenopus development. Misexpression of Smad5 in the embryo causes ventralization and induces ventral mesoderm. Moreover, Smad5 induces epidermis in dissociated ectoderm cells which would otherwise form neural tissue. Both of these activities require Smad4 (DPC4) activity. We propose that Smad5 acts downstream of the BMP4 signaling pathway in Xenopus embryos and directs the formation of ventral mesoderm and epidermis.
Animals↗
Hydroxyflutamide may not always be a pure antiandrogen.
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Androgen Antagonists↗