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Biomedical subjects

L H Chen

Publications and source records attributed to L H Chen.

At least 19 recordsLinked to original sources
PubMed2026

[Analysis of clinical spectrum and genotype characteristics of 9 cases of Fabry disease].

Objective: To investigate the genetic characteristics and clinical phenotypes across different genotypes in patients with Fabry disease. Methods: Clinical data of 9 confirmed FD patients treated from June 2019 to December 2025 at the Affiliated Huai'an No.1 people's Hospital of Nanjing Medical University were retrospectively analyzed. The diagnostic criteria for FD included α-galactosidase A (α-GalA) activity, GLA gene sequencing, globotriaosylsphingosine levels, and renal biopsy findings, supplemented by clinical symptoms and signs. Genetic testing was performed on both the proband and their family members. Proband underwent next-generation sequencing of the GLA gene using the long-range PCR. Family members were verified by conventional PCR combined with Sanger sequencing. Variants were classified according to the 2015 American College of Medical Genetics and Genomics guidelines for sequence variation interpretation. Results: Of the 9 patients, 4 were males and 5 were females. The mean α-Gal A activity was (0.47±0.13) μmol·L-1·h-1 in males and (2.38±0.91) μmol·L-1·h-1 in females. The mean age at diagnosis was (43.0±16.7) years. The main clinical manifestations included renal impairment in 7 cases (proteinuria, chronic kidney disease, or end-stage renal disease), cardiac involvement in 8 cases (myocardial hypertrophy, arrhythmia, etc.), and autonomic nervous system symptoms in 6 cases (hypohidrosis). Pathogenic or likely pathogenic GLA variants were identified in all 9 patients, of which 8 were classified as pathogenic and 1 as a variant of uncertain significance. Three patients underwent family screening: in one case, the variant was possibly inherited from the maternal grandmother; one case was confirmed as a de novo mutation; and in one case, paternal inheritance could not be excluded. Renal biopsy in one patient revealed characteristic myeloid bodies and zebra bodies. Among the 9 patients, 1 received agalsidase α and 8 received agalsidase β, with one case developing infusion-associated reactions after 12 infusions. During the follow-up period, one patient died due to cardiac complications. Conclusions: FD patients exhibit a broad clinical spectrum and diverse genotypes. Atypical presentations should be closely monitored to enable early diagnosis and treatment, thereby improving prognosis.

Humans↗
PubMed1992

4-Oxalocrotonate tautomerase, an enzyme composed of 62 amino acid residues per monomer.

The xylH gene encoding 4-oxalocrotonate tautomerase (4-OT) has been located on a subclone of the Pseudomonas putida mt-2 TOL plasmid pWW0 and inserted into an Escherichia coli expression vector. Several of the genes of the metafission pathway encoded by pWW0 have been cloned in E. coli, but the overexpression of their gene products has met with limited success. By utilizing the E. coli alkaline phosphatase promoter (phoA) coupled with the proper positioning of a ribosome-binding region, we are able to express functional 4-OT in yields of at least 10 mg of pure enzyme/liter of culture. 4-OT has been previously characterized and shown to be an extremely efficient catalyst (Whitman, C. P., Aird, B. A., Gillespie, W. R., and Stolowich, N. J. (1991) J. Am. Chem. Soc. 113, 3154-3162). Kinetic and physical characterization of the E. coli-expressed protein show that it is identical with that of the 4-OT isolated from P. putida. The functional unit is apparently a pentamer of identical subunits, each consisting of only 62 amino acid residues. This is the smallest enzyme subunit reported to date. The amino acid sequence, determined in part from automated Edman degradation and also deduced from the primary sequence of xylH, did not show homology with any of the sequences in the current data bases nor with any of the sequences of enzymes that catalyze similar reactions. We propose that the active site of 4-OT may be established by an overlap of subunits and comprised of amino acid residues belonging to several, if not all, of the subunits.

Amino Acid Sequence↗
PubMed1992

Effects of the peroxisome proliferators ciprofibrate and perfluorodecanoic acid on hepatic cellular antioxidants and lipid peroxidation in rats.

The purpose of this study was to determine if hepatic cellular antioxidants and indices of oxidative damage are altered by administration of the peroxisome proliferators ciprofibrate and perfluorodecanoic acid (PFDA). Rats were fed 0.01% ciprofibrate in the diet or were injected with PFDA (0.5 or 5.0 mg/kg, i.p.) every 4 weeks for 6, 14, 30, 54, and 78 weeks. Peroxisomal fatty acyl-CoA oxidase and catalase activities were increased by both ciprofibrate and PFDA throughout the study. Neither ciprofibrate nor PFDA increased the levels of malonaldehyde or conjugated dienes, but ciprofibrate decreased these indices at early time points. Ciprofibrate decreased the following cellular antioxidants or antioxidant enzymes: vitamin C, vitamin D, DT-diaphorase, glutathione peroxidase, glutathione-S-transferase, and glutathione reductase; superoxide dismutase and glutathione were not affected. PFDA decreased DT-diaphorase and increased superoxide dismutase, but did not affect other cellular antioxidants. This study shows that administration of the peroxisome proliferators ciprofibrate and PFDA did not increase indices of lipid peroxidation, but that cellular antioxidant defenses were inhibited for a prolonged period of time by the peroxisome proliferator ciprofibrate.

Acyl-CoA Oxidase↗
PubMed1992

Preliminary results of concurrent radiotherapy and chemotherapy with cis-platinum, vincristine, and bleomycin in bulky, advanced cervical carcinoma: a pilot study.

Twenty-four patients with bulky (greater than 4 cm), advanced (stages IIB-IVA) carcinoma of the uterine cervix were prospectively treated with a concurrent combination of radiotherapy (RT) and chemotherapy (CT). RT consisted of 4400 cGy (22 fractions) to the whole pelvis and a 1400-cGy boost to the parametrium. This was followed by two to three intracavitary brachytherapy courses. CT consisted of one to four course (median, three) of cisplatin (50 mg/m2) on Day 1, vincristine (1 mg/m2) on Day 2, and bleomycin (25 mg/m2) on Days 2-4. CT was started on the first day of external radiation and the scheduled course interval was 21 days. Among the 20 evaluable patients who completed at least one course of chemotherapy and a full course of radiation, 13 (65%) achieved complete response and 5 (25%) had partial response. Fatal complication occurred in 1 patient with stationary disease who died of septic shock due to ruptured pyometra. The other patient with primary stage IVA disease had progressive disease with ascites appearance after two courses of CT and later expired. Transient drug fever occurred in 19 (40.4%) of the 47 bleomycin-containing CT cycles. Grade 2 or 3 hematological toxicities occurred in 16 (30.2%) of a total of 53 CT cycles. Treatment delays of 1 to 7 days occurred in 15 (28.3%) CT cycles. Except for the case of septic shock, all of the other toxicities were generally tolerable and reversible. From this preliminary result we concluded that this particular combination of RT and CT in bulky, advanced cervical carcinoma is effective in enhancing local pelvic tumor control and well tolerated if strict selection of accrued patients is applied. Further investigation to assess its impact on long-term survival is in progress.

Adenocarcinoma↗
PubMed1992

Use of an oligonucleotide probe to detect Vibrio parahaemolyticus in artificially contaminated oysters.

A 26-mer oligonucleotide specific to Vibrio parahaemolyticus was synthesized from a 1,275-bp thermostable direct hemolysin (tdh) gene. This oligonucleotide probe specifically reacted with DNA from 89 of 95 V. parahaemolyticus isolates but not with DNA from other vibrios or other enteric and nonenteric organisms (n = 48). The probe hybridized with Southern blots of 0.5-kb HindIII-restricted chromosomal DNA fragments from all but five V. parahaemolyticus test isolates. The probe could be used to directly identify V. parahaemolyticus in artificially contaminated food without an isolation step.

Animals↗
PubMed1992

[Clinical applications of MRI in ophthalmology].

Magnetic resonance imaging (MRI) of the normal eyeball and orbital tissues is introduced, along with the MRI manifestations in 39 patients comprising 6 cases of intraocular and 29 cases of intraorbital disorders, and 4 cases of vascular diseases. The advantages and limitations of MRI in ophthalmology are discussed. It appears that MRI is more sensitive than ultrasonic B-scan or CT.

Adolescent↗
PubMed1991

Cloning and expression of functional rabbit muscle creatine kinase in Escherichia coli. Addressing the problem of microheterogeneity.

The gene encoding rabbit muscle creatine kinase (CK) has been subcloned into a single plasmid, and the protein expressed in a soluble and functional form in Escherichia coli. The amino terminus, specific activity, and electrophoretic mobility of the E. coli-expressed creatine kinase are all identical with that of creatine kinase purified from rabbit skeletal muscle. Surprisingly, isoelectric focusing shows that the expressed protein displays no less heterogeneity than the tissue-purified material. The identification of the source(s) of this heterogeneity is important for the preparation of highly homogeneous material needed for structural studies and clinical applications. This issue also has implications for studies of the developmental regulation and tissue localization of the various CK genes. Our results allow us to eliminate some of the proposals, such as the presence of multiple alleles, alternative ribosomal initiation sites, and post-translational glycosylation or phosphorylation that have been suggested to explain the presence of the numerous isoforms present in apparently pure preparations of CK.

Animals↗
PubMed1991

Structure and function of a bacterial mRNA stabilizer: analysis of the 5' untranslated region of ompA mRNA.

The 5' untranslated region (UTR) of the Escherichia coli ompA transcript functions in vivo as a growth rate-regulated mRNA stabilizer. The secondary structure of this mRNA segment has been determined by a combination of three methods: phylogenetic analysis, in vitro probing with a structure-specific RNase, and methylation by dimethylsulfate in vivo and in vitro. These studies reveal that despite extensive sequence differences, the 5' UTRs of the ompA transcripts of E. coli, Serratia marcescens, and Enterobacter aerogenes can fold in a remarkably similar fashion. Furthermore, the Serratia and Enterobacter ompA 5' UTRs function as effective mRNA stabilizers in E. coli. Stabilization of mRNA by the Serratia ompA 5' UTR is growth rate dependent. These findings indicate that the features of the ompA 5' UTR responsible for its ability to stabilize mRNA in a growth rate-regulated manner are to be found among the structural similarities shared by these diverse evolutionary variants.

Bacterial Outer Membrane Proteins↗
PubMed1991

Phosphocreatine protects ATP from a fructose load in transgenic mouse liver expressing creatine kinase.

The effects of an intraperitoneal dose of fructose on hepatic metabolism in transgenic mice expressing creatine kinase in liver were investigated using phosphorus-31 nuclear magnetic resonance (31P-NMR). Transgenic mice were fed diets containing varying amounts of creatine (Cr; 0-12%). It has previously been shown that 31P-NMR spectra of transgenic mice have a peak due to phosphocreatine (PCr), the intensity of which was proportional to the amount of Cr in the diet. No PCr peak was detected in control mice or transgenic mice not fed Cr. In the present study NMR spectra were collected before and for a 1-h recovery period after infusion of 0.15 mmol/10 g body wt fructose. In all mice infusion of fructose resulted in a two- to threefold elevation of phosphomonoesters. In control and non-Cr-fed transgenic mice this was accompanied by a 60% reduction of the inorganic phosphate (Pi) and a 50% fall in ATP. In transgenic mice fed Cr, the extent of reduction of Pi was dependent on the level of PCr and was markedly reduced compared with controls. Falls in Pi of 46, 24, and 6% were detected 12.5 min after fructose infusion in low, intermediate, and high PCr-containing livers, respectively. The presence of PCr also protected hepatic ATP levels from a fructose load. Transgenic mice fed on high or intermediate Cr diets showed no significant loss of ATP. However, livers with low levels of PCr lost ATP during a fructose challenge. From the equilibrium established by creatine kinase, free ADP levels were calculated throughout the fructose dose. Fructose caused a 2.5-fold increase in free ADP. This rise in ADP was independent of the total Cr or whether Pi and ATP were reduced by fructose infusion. These results indicate that an increase in ADP is not sufficient to cause depletion of ATP during a fructose challenge.

Adenosine Triphosphate↗
PubMed1991

[Combined methods of dialysis, cooked meat medium enrichment and laboratory animal toxicity for screening Clostridium botulinum spores in honey and infant food].

One hundred and fifty two samples of honey were purchased from apiaries and markets in Taiwan, meanwhile fifty samples of infant food including powders of infant milk, wheat, rice and commercial mixed cereals, as well as juice had been bought from supermarkets in Taipei city from July 1988 through April 1989. The samples were used for detecting the presence of Clostridium botulinum spores. Honey samples were prepared by dialysis to obtain the bacterial spores; however, infant food had been innoculated directly into the cooked meat medium. The suspicious isolated colonies were identified by Vitek automatic microbial identification system. The supernatants of cooked meat medium enrichment were performed for typing botulinum toxins via the laboratory animal toxicity test. The results showed that two samples of honey contained the spores of C. botulinum type B, but none in samples of infant food. The specific response of clinical signs in mice, after being administered the supernatant of suspected cultural broth, were also observed and described in this article.

Animals↗
PubMed1991

[Total synthesis of an analogue of schizandrin].

A schizandrin analogue 9, 1, 2, 3, 10, 11, 12-hexamethoxy-6,7-dihydroxy-cis-6,7-dimethyl dibenzocyclooctadiene, is one of the metabolites of schizandrin with comparable anti-convulsion activity. In this paper, compound 9 was synthesized from gallic acid through the following sequence of reactions: methylation, Henry condensation, reduction with Fe-FeCl3-HCl, intermolecular reductive coupling and intramolecular nonphenolic oxidative coupling, totally in seven steps. The intermediate 1,4-diaryl-2,3-dimethyl-2,3-butanediol (7) which is a mixture of erythro and threo isomers was converted by DDQ in TFA into compound 9 and another new compound 10 via a different reaction path.

Animals↗
PubMed1990

NMR detection of creatine kinase expressed in liver of transgenic mice: determination of free ADP levels.

To use the equilibrium established by creatine kinase (CK) to determine hepatic free ADP levels, the transcriptional control elements of the transthyretin gene were used to direct expression of the CK B isozyme to the livers of transgenic mice. Activities of CK ranging from 80-250 mumol per min per g (wet weight) were detected in liver extracts from five founder mice. The CK activity was stably transmitted to subsequent generations. Isozyme gels and immunoblots confirmed that the activity detected in extracts was due to the B isozyme of CK. Immunohistology indicated that the protein was expressed uniformly throughout the liver and was localized primarily to the cytoplasm. 31P NMR spectroscopy was used to detect the metabolic product of the CK reaction, phosphocreatine, demonstrating that the enzyme was active in vivo. The phosphocreatine level fell rapidly during anoxia (t1/2 = 1 min), indicating that the CK reaction was integrated into hepatic energy metabolism. The equilibrium established by CK was used to calculate a hepatic free ADP level of 0.059 +/- 0.004 mumol/g (wet weight). In vivo NMR studies of these mice will be valuable for studying the role of free ADP in regulating liver metabolism.

Adenosine Diphosphate↗
PubMed1990

[Chemical identification of structure of podocarpamide by synthesis].

Podocarpamide, isolated from the bark of Zanthoxylum podocarpum Hemsl., is a new compound with platelet aggregation inhibiting and SGPT level lowering activities. Its structure was inferred to have two possible forms, either I or II, from its spectra. The structure of podocarpamide was identified as I by synthesis.

Amides↗
PubMed1989

Random and site-directed mutagenesis of bacterial luciferase: investigation of the aldehyde binding site.

Numerous luciferase structural gene mutants of Vibrio harveyi have been generated by random mutagenesis and phenotypically characterized [Cline, T.W., & Hastings, J.W. (1972) Biochemistry 11, 3359-3370]. All mutants selected by Cline and Hastings for altered kinetics in the bioluminescence reaction had lesions in the alpha subunit. One of these mutants, AK-20, has normal or slightly enhanced thermal stability and enhanced FMNH2 binding affinity but a much-reduced quantum yield of bioluminescence and dramatically altered stability of the aldehyde-C4a-peroxydihydroflavin-luciferase intermediate (IIA), with a different aldehyde chain length dependence from that of the wild-type luciferase. To better understand the structural aspects of the aldehyde binding site in bacterial luciferase, we have cloned the luxAB genes from the V. harveyi mutant AK-20, determined the nucleotide sequence of the entire luxA gene, and determined the mutation to be TCT----TTT, resulting in a change of serine----phenylalanine at position 227 of the alpha subunit. To confirm that this alteration caused the altered kinetic properties of AK-20, we reverted the AK-20 luxA gene by oligonucleotide-directed site-specific mutagenesis to the wild-type sequence and found that the resulting enzyme is indistinguishable from the wild-type luciferase with respect to quantum yield, FMNH2 binding affinity, and intermediate IIA decay rates with 1-octanal, 1-decanal, and 1-dodecanal. To investigate the cause of the AK-20 phenotype, i.e., whether the phenotype is due to loss of the seryl residue or to the properties of the phenylalanyl residue, we have constructed mutants with alanine, tyrosine, and tryptophan at alpha 227.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehydes↗
PubMed1989

Site-directed mutagenesis of bacterial luciferase: analysis of the 'essential' thiol.

It has been appreciated for many years that the luciferase from the luminous marine bacterium Vibrio harveyi has a highly reactive cysteinyl residue which is protected from alkylation by binding of flavin. Alkylation of the reactive thiol, which resides in a hydrophobic pocket, leads to inactivation of the enzyme. To determine conclusively whether the reactive thiol is required for the catalytic mechanism, we have constructed a mutant by oligonucleotide directed site-specific mutagenesis in which the reactive cysteinyl residue, which resides at position 106 of the alpha subunit, has been replaced with a seryl residue. The resulting alpha 106Ser luciferase retains full activity in the bioluminescence reaction, although the mutant enzyme has a ca 100-fold increase in the FMNH2 dissociation constant. The alpha 106Ser luciferase is still inactivated by N-ethylmaleimide, albeit at about 1/10 the rate of the wild-type (alpha 106Cys) enzyme, demonstrating the existence of a second, less reactive, cysteinyl residue that was obscured in the wild-type enzyme by the highly reactive cysteinyl residue at position alpha 106. An alpha 106Ala variant luciferase was also active, but the alpha 106Val mutant enzyme was about 50-fold less active than the wild type. All three variants (Ser, Ala and Val) appeared to have somewhat reduced affinities for the aldehyde substrate, the valine mutant being the most affected. It is interesting to note that the alpha 106 mutant luciferases are much less subject to aldehyde substrate inhibition than is the wild-type V. harveyi luciferase, suggesting that the molecular mechanism of aldehyde substrate inhibition involves the Cys at alpha 106.

Aldehydes↗
PubMed1989

A novel regulatory mechanism for whey acidic protein gene expression.

When primary mouse mammary epithelial cells (PMME) are cultured on a basement membrane type matrix, they undergo extensive morphogenesis leading to the formation of 3-dimensional alveoli-like spherical structures surrounding a closed lumen. We show for the first time that cells cultured on basement membrane-type matrix express high levels of whey acidic protein (WAP) mRNA and secrete the protein into the lumen. The expression of WAP appears to be dependent upon the formation of the alveoli-like spheres: prevention of sphere formation by fixation or drying of the matrix abolishes the expression of WAP. Co-culturing PMME on native and fixed basement membrane matrix indicates that the suppression of WAP expression is dominant, thereby revealing the existence of a diffusible inhibitor(s). The inhibitory activity is present in the conditioned medium of PMME cultured on plastic surface and floating collagen gels, substrata that do not form alveoli and do not allow WAP expression. These findings are consistent with the model that the synthesis, or the action, of the WAP inhibitory factor is regulated by the tissue-like multicellular organization of mammary cells. When PMME do not have correct 3-dimensional structures, one (or more) inhibitor is secreted into the medium which suppresses WAP expression by an autocrine or paracrine mechanism. Nuclear run-on experiments suggest that the suppression of WAP expression is posttranscriptional. These results have obvious bearings on the understanding of the mechanisms by which cell-cell and cell-extracellular matrix interaction regulate tissue specific gene expressions.

Animals↗