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Biomedical subjects

J Hu

Publications and source records attributed to J Hu.

At least 469 records · Page 26Linked to original sources
PubMed1996

Intricate regulation of nitric oxide synthesis in neurons.

There is little doubt that nitric oxide (NO) is one of the most important second messengers yet to be discovered, particularly in relation to its diverse roles in the regulation of neuronal function. As expected, synthesis of such a multifunctional molecule has to be under very tight control. For example, there is evidence that the rate of production of NO in neurons is regulated by several second messengers and their related protein kinases. NO by itself is also able to elicit negative feedback on the activity NO synthase (NOS) to attenuate its own rate of synthesis. Furthermore, NO modulates the release of neurotransmitters and alters the sensitivity of receptors that are coupled to stimulation of its synthesis. In healthy neurons, all of these intricate mechanisms are expected to cross-talk in harmony to result in the generation of optimal amounts of NO.

Calcium↗
PubMed1996

Investigation of a naphthalene pitch by high-resolution solid-state dynamic nuclear polarization.

The possibility of applying the dynamic nuclear polarization (DNP) technique to a study of char is explored with a naphthalene-derived pitch. It is shown that a 13C DNP enhancement factor of about 10(2) is obtained when the polarization is directly transferred from the unpaired electrons to the 13C nuclei. An undistorted spectrum with an enhancement factor of 8 is obtained by the DNP cross-polarization magic-angle spinning nuclear magnetic resonance (DNP-CP-MAS NMR) method. With such a high increase in S/N, it is possible to measure the 13C polarization time (Tp) and the spin-lattice relaxation time (T1) of the system in a reasonable experimental time. The resultant values are Tp = 19 s and T1 = 38 s, respectively. Based on the DNP enhancement as a function of the microwave frequency, it is found that the predominant DNP mechanism in the pitch is the solid-state effect.

Carbon Isotopes↗
PubMed1996

Ciliary neurotrophic factor (CNTF) genotypes and CNTF contents in human sciatic nerves as measured by a sensitive enzyme-linked immunoassay.

To study the level of ciliary neurotrophic factor (CNTF) in human nervous tissues, we developed a sensitive enzyme-linked immunoassay using a specific antibody against human CNTF. This method allowed us to detect as little as 0.3 ng/ml of human CNTF with good linearity and accuracy. Using this method, CNTF levels were determined in human sciatic nerves obtained at autopsy from 21 amyotrophic lateral sclerosis (ALS) patients and 48 subjects who had died of other neurological diseases. CNTF genotypes were also determined. The results indicated that CNTF levels were high in the normal homozygotes and approximately halved in the heterozygote subjects. There was, however, no significant difference in CNTF levels in the sciatic nerves between ALS and other neurological disease patients, indicating that the CNTF level was mainly determined by its genotypes and that the level in the sciatic nerves was not reduced in ALS patients.

Amyotrophic Lateral Sclerosis↗
PubMed1996

Demonstration and characterization of the iron regulatory protein in human brain.

Iron regulatory proteins (IRPs) are cytoplasmic RNA binding proteins that regulate expression of ferritin, erythroid 5-aminolevulinic acid synthase, and transferrin receptor through interaction with conserved RNA stem-loop structures called iron-responsive elements (IREs). Two IRPs (IRP1 and IRP2) have been reported. In the present study we provide evidence for and initial characterization of the IRPs in human brain. Two RNA-protein complexes were obtained by RNA band shift assay on cytoplasmic extracts from human brain. Competition studies indicate that the formations of the RNA-protein complexes are specific to the IRE structure. UV crosslinking of brain cytoplasmic extracts with ferritin IRE RNA transcripts revealed a single RNA-protein complex with a molecular mass of 110 kDa. A single band at 100 kDa was obtained with IRP1 antiserum on western blot analysis of brain cytoplasmic extracts, and a supershift in the RNA-protein complexes was observed with an IRP1 antiserum. Two cDNA clones were isolated from a human brain cDNA library with IRP1 cDNA probes, and both of these cDNA probes recognized a single mRNA species (4.0 kb) from human astrocytoma cells. Purified human brain IRP protein has a molecular mass of approximately 100 kDa and is capable of forming two RNA-protein complexes with ferritin IRE RNA and reacts strongly with IRP1 antiserum. These data indicate that IRP1 is predominant in the adult human brain and, in this tissue, is capable of forming a double IRE/IRP complex. This latter observation suggests the brain IRP undergoes posttranslational modification, the result of which may influence the stability of the IRE/IRP complex.

Adult↗
PubMed1996

Structural organization, sequence, and expression of the chicken NRAMP1 gene encoding the natural resistance-associated macrophage protein 1.

One of the most common causes of food poisoning in humans is salmonellosis, which is frequently caused by ingestion with Salmonella-contaminated poultry products. Several lines of evidence suggest that genetic factors control resistance and susceptibility of chickens to infection with Salmonellae. In the mouse, innate resistance to infection with intracellular pathogens such as Salmonella typhimurium, several species of Mycobacteria, and Leishmania donovani is controlled by the mouse chromosome 1 Nramp1Bcg gene. To investigate the role of NRAMP1 in the differential resistance and susceptibility of chickens to infections with S. typhimurium, we have cloned and characterized cDNA clones corresponding to the chicken NRAMP1 gene. Nucleotide and predicted amino acid sequence analyses indicate that the chicken NRAMP1 polypeptide encodes a 555-amino-acid residue membrane protein with 12 putative transmembrane domains, two N-linked glycosylation sites, and an evolutionary conserved consensus transport motif. The peptide sequence identity among chicken, mouse, and human NRAMP1 is 68%. The chicken NRAMP1 gene contains 15 exons and spans 5 kb of genomic DNA. One major and two minor transcription initiation sites were detected using primer extension. Nucleotide sequencing of the promoter region revealed the presence of a classical TATAA element and consensus sequences for binding the myeloid specific PU.1 factor and several lipopolysaccharide (LPS) (NF-IL6 and NF-kappa B) and interferon-gamma (IFN-gamma)-inducible response elements. Similar regulatory elements are found in the promoters of mouse and human NRAMP1. Northern blot analyses revealed NRAMP1 expression in reticuloendothelial organs (spleen and liver), lung, and thymus. As demonstrated in mice and humans, the macrophage is also a major site of NRAMP1 mRNA expression in chickens. However, the high levels of expression detected in chicken thymus contrast with the absence of expression of the mammalian Nramp1 gene in this tissue.

Amino Acid Sequence↗
PubMed1996

Isolation and characterization of rice R genes: evidence for distinct evolutionary paths in rice and maize.

R and B genes and their homologues encode basic helix-loop-helix (bHLH) transcriptional activators that regulate the anthocyanin biosynthetic pathway in flowering plants. In maize, R/B genes comprise a very small gene family whose organization reflects the unique evolutionary history and genome architecture of maize. To know whether the organization of the R gene family could provide information about the origins of the distantly related grass rice, we characterized members of the R gene family from rice Oryza saliva. Despite being a true diploid, O. sativa has at least two R genes. An active homologue (Ra) with extensive homology with other R genes is located at a position on chromosome 4 previously shown to be in synteny with regions of maize chromosomes 2 and 10 that contain the B and R loci, respectively. A second rice R gene (Rb) of undetermined function was identified on chromosome 1 and found to be present only in rice species with AA genomes. All non-AA species have but one R gene that is Ra-like. These data suggest that the common ancestor shared by maize and rice had a single R gene and that the small R gene families of grasses have arisen recently and independently.

Amino Acid Sequence↗
PubMed1996

Psoriasis: pathophysiology and oral manifestations.

Psoriasis is a chronic, remitting and relapsing inflammatory skin disorder with a strong genetic predisposition. Psoriasis affects 1-3% of the world's population in their early lives representing a disabling condition with significant social and economic impact. Despite a great deal of research on the etiology and tissue destruction mechanisms, the disease is not well understood. The purpose of this paper is to provide current information from the literature with a special focus on oral manifestations. The major signs and symptoms presented in the oral environment of a psoriasis patient may include geographic tongue, fissure tongue, gingival and/or mucosal lesions. Inflammatory temporomandibular joint lesions have been reported in less than 5% of psoriasis patients. Multiple treatment strategies, be they topical or systemic, have been applied to these patients for symptom relief but not for cure.

Adolescent↗
PubMed1996

Gamma radiation-sterilized, triple-lumen catheters coated with a low concentration of chlorhexidine were not efficacious at preventing catheter infections in intensive care unit patients.

In a randomized, double-blind trial, gamma radiation-sterilized, chlorhexidine-coated triple-lumen catheters were compared with uncoated control catheters for their ability to prevent catheter infection in 254 intensive care unit patients. The chlorhexidine coating was not efficacious, and a rabbit model demonstrated that reduction of chlorhexidine activity by gamma radiation sterilization was the likely explanation for the failure.

Bacteremia↗
PubMed1996

[Analysis for 13 term deliveries after cardiac valve replacement and percutaneous transluminal mitral commissuroplasty].

OBJECTIVE: To study the cardiac function, mode of delivery and anticoagulant therapy in 13 pregnant women after cardiac valves replacement (CVR) and percutaneous transluminal mitral commissuroplasty (PTMC). METHOD: Retrospective data analysis. RESULTS: Patients with cardiac function of degree I to III can accomplish pregnancy and delivery safely after cardiac operation one and a half years. Using warfarin during pregnancy and delivery safely. Using warfarin during pregnancy and heparin during delivery did not increase the blood loss in both mothers and neonates, and congenital malformation either. It is more appropriate for pregnant women who had CVR to deliver by cesarean section and those who had PTMC to deliver vaginally. CONCLUSIONS: Women after cardiac operation can accomplish pregnancy and delivery if their cardiac function belong to degree I-III with or without digoxin treatment before delivery. Using anticoagulant therapy correctly according to prothrombin time (PT) test during pregnancy does not increase delivery complications to both mothers and neonates.

Adult↗
PubMed1996

Expression of a viral oncoprotein during mammary gland development alters cell fate and function: induction of p53-independent apoptosis is followed by impaired milk protein production in surviving cells.

The disruption of cell cycle regulation is associated with developmental abnormalities and tumorigenesis. The SV40 large T antigen (Tag) interferes with cell cycle control by interacting with the pRb family and p53. Mice carrying a transgene composed of the whey acidic protein (WAP) gene promoter and the Tag coding sequence express Tag during pregnancy and are unable to nurse their young. Tag expression induced apoptosis in mammary epithelial cells during late pregnancy. At least 5% of mammary epithelial cells were undergoing apoptosis at any one time. In contrast, less than 0.2% of mammary epithelial cells in nontransgenic littermates was undergoing apoptosis. Apoptosis in Tag mice was associated with increased steady-state RNA levels of bax and bcl-xL + S, with a relative increase in bcl-xs expression. Since p53 was sequestered by Tag, it is likely that p53-independent mechanisms precipitated apoptosis. The Tag-expressing mammary alveolar cells that did not undergo apoptosis continued to differentiate through late pregnancy, as measured by the sequential activation of milk protein gene expression. However, milk protein production, processing, and secretion was impaired, resulting in lactation failure.

Animals↗
PubMed1996

Apoptosis and remodeling of mammary gland tissue during involution proceeds through p53-independent pathways.

Mammary gland involution is a physiological process that follows lactation and results in the rapid disappearance of the entire lobulo-alveolar compartment. Coincident with the onset of involution, milk protein gene expression ceases and alveolar cells undergo programmed cell death. In mammary epithelial tissue culture cells in vitro, both p53-dependent and p53-independent apoptosis pathways have been identified. We investigated whether p53 induces apoptosis during mammary gland involution in vivo and participates in tissue remodeling. Toward this end, we examined the process of involution in the presence and absence of functional p53 in mouse models: wild-type, transgenic mice that express SV40 T-antigen specifically in mammary tissue during pregnancy; and mice that carry nonfunctional p53 alleles in their germ line. Mammary gland whole-mount and histological analyses revealed that involution and remodeling, with the concomitant disappearance of the lobulo-alveolar structures, proceeded normally in the absence of functional p53. In addition, the absence of functional p53 did not alter the involution related pattern of bax (death inducer) gene expression or the ratio of RNAs encoding bcl-xs (death inducer) to bcl-xL (survival inducer).

Animals↗
PubMed1996

[Postoperative function exercise for replantation of severed limbs in children].

The speciality of limb replantation in children included thread and thin for blood vessels, growth development for muscles and epiphyses, morable and incooperation in clinical. The function exercises after limb replantation in children must be connected with the clinical speciality of vascular microsurgery, the anthor divided it into four stages; vascular crises stage, limb aliving stage, clinical healing of bone stage, and function recovery stage. The different treatment performed in four stages, and excellent clinical results were achieved.

Amputation, Traumatic↗
PubMed1996

[Clinical application of 72-hour fast expansion of the soft tissue].

The rapid expansion of the soft tissue has been applied in plastic surgery. To further shorten the expansion period, we undertook a clinical study on 72-hour fast expansion and applied this technique to 11 patients with different defects on their face, neck, shoulder or elbow after resection of scar, melanoma, angioma or due to trauma. Satisfactory results have gained. This paper not only introduces the clinical application of the technique, but also discusses the theoretical basis, advantages and key points of the operation.

Adolescent↗
PubMed1996

Lysosomal enzyme activities in cultured retinal pigment epithelial and glial cells of RCS rat.

PURPOSE: To compare the activities of acid phosphatase, N-acetyl-beta-glucosaminidase and alpha-mannosidase in cultured retinal pigment epithelium (RPE) and glial cells of Royal College of Surgeons (RCS) rat with those in Long Evans (LE). METHODS: The cultured RPE and glial cells of RCS and LE rat were plated into the same 96 well microtitre, and the biochemical method in microsystem were used for enzyme assays. RESULTS: The activities of acid phosphatase and N-acetyl-beta-glucosaminidase are higher by, respectively, 30% and 46% in cultured RPE of RCS rat than LE rat. The activity of alpha-mannosidase has no significant difference. The activities of 3 enzymes in the retinal glial cells derived from RCS rats are higher than LE rat by 13% to 77%. CONCLUSION: These results suggest that the high activities of lysosomal enzymes in RCS RPE and glial cells may play an important role in the pathogenesis of retinal dystrophy.

Acetylglucosaminidase↗
PubMed1996

[Relations between p53 and p185 expression and prognosis of patients with colon cancers].

The expression of p53 and HER-2/neu p185 was studied immunohistochemically in 120 paraffin-embeded specimens of colon cancer with specific monoclonal antibodies. Sixty-eight of the 120 patients were positive for p53(57%), and 55 were positive for p185(46%), p53 was always expressed in the cell nucleus, and p185, the cell membrane. The expression of p53 and p185 was not correlated to sex and age of the patients, to primary sites, stages and pathological classification of the tumors. The survival period of patients with positive p53 was shorter than those with negative p53, while p185 expression showed no correlation to the survival period. The results suggest that p53 expression may be of some value in predicting prognosis in patients with colon cancer.

Adenocarcinoma↗