Biomedical subjects

M Li

Publications and source records attributed to M Li.

At least 145 records · Page 8Linked to original sources

PubMed2001

Applications of display technologies to proteomic analyses.

With the rapid accumulation of genetic information, development of general experimental approach suitable for large scale annotation and profiling of the whole proteome have become one of the major challenges in postgenomic era. Biomolecular display technologies, which allow expressing of a large pool of modularly coded biomolecules, are extremely useful for accessing and analyzing protein diversity and interaction profile on a large scale. Recent advances in protein display technologies and their applications to proteomic analyses have been discussed.

Cloning, Molecular↗

PubMed2001

Pathology-related differential expression regulation of NGF, GDNF, CNTF, and IL-6 mRNAs in human vasculitic neuropathy.

The mRNA levels of nerve growth factor (NGF), glial cell line-derived neurotrophic factor (GDNF), ciliary neurotrophic factor (CNTF), and interleukin-6 (IL-6) were examined in sural nerves of 22 patients with acute necrotizing vasculitic neuropathies. NGF, GDNF, and IL-6 mRNAs were upregulated and CNTF mRNA was downregulated in the lesioned nerves, but their up- and down-regulation levels were not correlated with each other, showing that these mRNAs were independently expressed. The expression of NGF and CNTF mRNAs was clearly correlated with the degree of infiltrated macrophages and T cells, and myelinated fiber density, respectively. These findings indicate that these neurotrophic factors are differentially expressed temporally and spatially in the vasculitic nerve lesion by an underlying pathology-related process.

Adult↗

PubMed2001

The Stat3/5 locus encodes novel endoplasmic reticulum and helicase-like proteins that are preferentially expressed in normal and neoplastic mammary tissue.

The signal transducers and activators of transcription (STAT) 5 and 3 are critical for mammary alveolar development during pregnancy and remodeling during involution. In the mouse, STAT3, STAT5a, and STAT5b are encoded by adjacent genes on chromosome 11 (60.5 cM). To identify additional genes in the Stat3/5 locus that may participate in normal and neoplastic development of the mammary gland, we have cloned and sequenced 500 kb and searched for genes preferentially expressed in mammary tissue. We identified six known genes and cloned two new genes, termed D11Lgp1 and D11Lgp2. Both genes are most highly expressed in normal mammary tissue and mammary tumors from several transgenic mouse models. LGP1 consists of 532 and 530 amino acids in mouse and human, respectively (88% similarity). A region in the carboxy-terminal half of LGP1 has limited homology with Arabidopsis thaliana GH3-like proteins. Immunofluorescence studies demonstrated that LGP1 is located in the nuclear envelope and the endoplasmic reticulum. LGP2 is a cytoplasmic protein of 678 amino acids.

Amino Acid Sequence↗

PubMed2001

Study on modification of the Misgav Ladach method for cesarean section.

172 cases of pregnant women scheduled for delivery by cesarean section were randomly assigned to 59 cases in modification group with modified Misgav Ladach technique, 57 cases in Misgav Ladach group with Misgav Ladach technique and 56 cases in Pfannenstiel group with Pfannenstiel technique from May to Dec. 1999. The modified points included: transversely incising the fascia 2 to 3 cm, then dividing it bluntly; without opening and dissociating the visceral peritoneum; two layers suturing of low transverse uterine incision; closing the skin by continuous suturing. Results showed the average delivery time in the modification group was (3.6 +/- 2.6) min and (5.7 +/- 2.9) min in the Misgav Ladach group (P < 0.05). Median operating time was (28.3 +/- 5.4) min in modification group compared with (27.5 +/- 6.5) min in the Misgav Ladach group (P > 0.05). Average blood loss was (128 +/- 35) ml in modification group compared with (212 +/- 147) ml in the Pfannenstiel group (P < 0.05). It was concluded that the modified Misgav Ladach technique not only preserved all advantages of Misgav Ladach method, but also had additional advantages, such as faster in delivering the fetus, less damage, easier mastering for obstetricians.

Adult↗

PubMed2001

Anterior approach to the second thoracic vertebral body for surgical treatment (vertebrectomy, bone grafting, and titanium alloy plate fixation).

The surgical approach to the second thoracic vertebral body is difficult from the anterior side. A 38-year-old woman suffering from plasmacytoma in the second thoracic vertebra showed paraplegia for 2 weeks prior to surgery. X-ray, computed tomography (CT), and magnetic resonance imaging (MRI) examinations indicated breakdown of the second thoracic vertebral body and arch, associated with spinal cord compression. A 99mTc bone scintigram showed accumulation only in the second thoracic vertebra. After one course of chemotherapy with cyclophosphamide and prednisone (CP protocol), surgery was carried out. The incision was made on the right side of the anterior of the neck, from the middle half of the sternocleidomastoideus along the anterior edge to the jugular notch of the sternum. After cutting the platysma, severing the sternohyoideus, splitting the sternothyroid muscle, and forming a compartment between the esophagus and vagina carotica, we extended the incision to the sternum. Without wedging the sternum, we separated tissue from the posterior of the sternum to the second and third thoracic vertebrae, excised the second thoracic vertebra to expose the hard spinal meninges, and removed the tumor in the vertebral canal to release the compression on the spinal cord. An autogeneous bone graft, taken from the right ilium (1.5 x 1.5 x 3 cm in size), was implanted between the first and third thoracic vertebrae, and a spinal titanium alloy plate was used to increase fixation between the first and third thoracic vertebrae from the front. During the surgery, 800 ml of blood was transfused. On the fifth postsurgical day, the patient could walk normally with a neck collar, and the paraplegia was completely alleviated, with no complications.

Adult↗

PubMed2001

Population bone mineral density measurements for Chinese women and men in Hong Kong.

The aim of the study was to establish population ranges of bone mineral density (BMD) for Hong Kong Chinese men and women for the Hologic QDR 2000 bone densitometer, to compare these values with the manufacturer's reference ranges, to compare these values with population ranges for women obtained for the Norland X26 bone densitometer, and to examine variations between the two densitometers. The subjects were 164 men aged 40-79 years and 436 women aged 20-89 years, who were all ethnic Chinese, recruited from volunteers, social centers for the elderly and general practice clinics. BMD in women began to decline rapidly between ages 50 and 79 years, averaging about 10% loss per decade from the young adult (20-29 years) mean. The percentage losses from young adult mean values in the spine, femroal neck, trochanter and total femur were 23%, 30%, 31% and 33%, respectively, from 20 to 79 years. In the ninth decade no further decrease in BMD occurred with the exception of a further 4% at the hip sites. In men, no decrease in spine BMD occurred between 40 and 70 years. Compared with BMD in the fourth decade, 10%, 13%, and 11% of BMD was lost at the femoral neck, trochanter and total femur, respectively, by the seventh decade. These values show differences compared with the manufacturer's reference ranges for Caucasians and Japanese. BMD values for the spine were comparable between Hologic and Norland densitometers, but Hologic values for femoral neck and trochanteric regions were lower than the Norland values. Data provided by this study may thus be used as normative values for the Hologic QDR2000 bone densitometer, instead of values provided by the manufacturer. BMD values at the hip sites are not interchangeable between Norland and Hologic bone densitometers, and estimation of numbers of the population with osteoporosis will depend on the model of densitometer used.

Absorptiometry, Photon↗

PubMed2001

A simple flow-injection on-line clean-up system for microwave plasma-torch atomic emission spectrometry.

A simple flow injection (FI) on-line clean-up system has been developed for microwave plasma-torch atomic emission spectrometry (MPT-AES). A non-selective strongly acidic cation-exchange resin was used to achieve the goal of "on-line clean-up". Ag and Zr, which form halogen-complex anions in halide acid media, and Cr, Mo, and P, which exist as acid group anions or acids (neutral) in acidic solution, were determined and the interfering matrix cations were removed on-line. Satisfactory analytical results were obtained from some practical samples by use of this procedure.

Journal Article↗

PubMed2001

Determination of proteins by their enhancement of resonance light scattering by fuchsine acid.

Based on the measurement of the enhancement of resonance light scattering (RLS) of fuchsine acid (FSA) by proteins, a novel sensitive assay of proteins in body fluid samples has been developed. Proteins, including bovine serum albumin (BSA), human serum albumin (HSA), pepsin (Pep), alpha-chymotrypsin (Chy), lysozyme (Lys), and cellulase (Cel), can bind to fuchsine acid (FSA), resulting in enhanced RLS signals at 277.0 nm. Linear relationships between the enhanced RLS intensity and the protein concentration were measured at different concentration of FSA, and the limits of detection for BSA, HSA, and Lys were found to lie in the nanogram range.

Animals↗

PubMed2001

Neuronal and glial advanced glycation end product [Nepsilon-(carboxymethyl)lysine]] in Alzheimer's disease brains.

The cellular distribution of an advanced glycation end product [Nepsilon-(carboxymethyl)lysine (CML)] in aged and Alzheimer's disease (AD) brains was assessed immunohistochemically. CML was localized in the cytoplasm of neurons, astrocytes, and microglia in both aged and AD brains. Glial deposition was far more marked in AD brains than in aged brains, and neuronal deposition was also increased. On electron microscopic immunohistochemistry, neuronal CML formed granular or linear deposits associated with lipofuscin, and glial deposits formed lines around the vacuoles. Neuronal and glial deposits were prominent throughout the cerebral cortex and hippocampus, but were sparse in the putamen, globus pallidus, substantia nigra, and cerebellum, with glial deposits being far more prominent in AD brains. The distribution of neuronal and glial deposits did not correspond with the distribution of AD pathology. The extent of CML deposits was inversely correlated with neurofibrillary tangle formation, particularly in the hippocampus. Most hippocampal pyramidal neurons with neurofibrillary tangles did not have CML, and most of the neurons with heavy CML deposits did not have neurofibrillary tangles. In the hippocampus, neuronal CML was prominent in the region where neuronal loss was mild. These observations suggest that CML deposition does not directly cause neurofibrillary tangle formation or neuronal loss in AD.

Aged↗

PubMed2001

The zygotic expression of zebrafish trebf during embryogenesis is restricted to the embryonic shield and its derivatives.

We have identified a zebrafish gene trebf that shows an overall similarity of 51.5% and 55.1% in amino acid sequence with human and mouse TREB5/hXBP-1/HTF, respectively. Northern hybridization reveals that trebf mRNA is expressed throughout the life cycle of zebrafish. Whole-mount in situ hybridization detects an expression pattern of trebf in zebrafish that is very different from that of mammalian TREB5. Just before the onset of gastrulation, trebf transcripts are accumulated in the dorsal blastoderm margin and subsequently in the forming organizer. During gastrulation, the trebf-positive cells in the organizer migrate toward the animal pole and form two distinct domains. The cells in the anterior leading expression domain ultimately differentiate into hatching gland, whereas those in the following domain form the notochord.

Amino Acid Sequence↗

PubMed2001

Assessment of a vaccinia virus vectored multi-epitope live vaccine candidate for Plasmodium falciparum.

We constructed a live recombinant vaccinia virus vaccine candidate containing a synthesised hybrid gene termed 'HGFSP' encoding circumsporozoite protein (CSP), major merozoite surface antigen-1(MSA1), major merozoite surface antigen-2 (MSA2), and ring-infected erythrocyte surface antigen (RESA) of Plasmodium falciparum, interleukin-1 (IL-1) and tetanus toxin (TT) epitopes. Anti-recombinant vaccinia virus rabbit sera and IgG were tested in inhibition experiments in vitro. Results showed that the recombinant vaccinia virus had some capability to inhibit the growth of P. falciparum in vitro. The sera of rabbits, rats, and mice immunised with recombinant virus showed obvious IL-2 activity 4-6 weeks after immunisation. The interferon (IFN) level of sera from these animals 6 weeks after immunisation was significantly higher than before immunisation. These results indicate that the recombinant vaccinia virus can stimulate cell mediated responses (Th1 cell response) in immunised animals, and has the capability to inhibit multiplication of in vitro cultured P. falciparum. Thus this recombinant vaccinia virus is an appropriate vaccine candidate for further evaluation in Aotus monkey or human clinical trails.

Animals↗

PubMed2001

Schedule control of quantal and graded dose-effect curves in a drug-drug-saline discrimination.

Pigeons were trained to discriminate among 5 mg/kg pentobarbital, 5 mg/kg morphine, and saline when responding was maintained under fixed-interval (FI) or fixed-ratio (FR) reinforcement schedules. After the discrimination was established, other drugs were substituted for the training drugs. After low doses of pentobarbital and chlordiazepoxide, responding shifted from the saline key to the pentobarbital key under both FR and FI schedules. After low doses of morphine and methadone, responding shifted from the saline key to the morphine key under both reinforcement schedules. After all doses of d-amphetamine, responding occurred largely on the saline key under both schedules. Responding also was confined largely to the saline key after phencyclidine administration under the FR schedule, but under the FI schedule, responding shifted from the saline key to the pentobarbital key at high doses of phencyclidine. When responding was maintained under the FR schedule, the dose-response curves for drugs that generalized to the training drugs were quantal in shape, while under the FI schedule, the dose-response curves for drugs that generalized to the training drugs were graded. These data extend observations that FR schedules generate quantal dose-response curves, and FI schedules generate graded dose-response curves to complex three-key drug discriminations.

Animals↗

PubMed2001

Pituitary adenylate cyclase activating polypeptide is highly abundant in the nervous system of anoxia-tolerant turtle, Pseudemys scripta elegans.

The levels of the pituitary adenylate cyclase activating polypeptide (PACAP) were measured in the central nervous system and in peripheral organs of the anoxia-tolerant freshwater turtle, Pseudemys scripta elegans by radioimmunoassay. The concentration of PACAP38 was strikingly high in the central nervous system and lower but considerable immunoreactivity was detected in the peripheral organs. Levels of PACAP38 in the turtle brain exceed those measured in rat and human brain areas by 10-100-fold. Based on these exceptionally high levels of PACAP and the known neuroprotective role of the peptide, it can be suggested that PACAP38 plays a role in the extraordinary resistance of the turtle brain from anoxia-induced neuronal damage.

Animals↗

PubMed2001

Sensitization of adenylate cyclase induced by a dopamine D2 receptor mutant: inverse agonism by D2 receptor antagonists.

Mutations of residues in the third intracellular loops of several G-protein coupled receptors have been shown to confer constitutive activation. The authors investigated the effects of one such mutation in the dopamine D2 receptor. Compared to the wild type D2, the mutant D2 receptor (D2T344K) showed a substantial increase in agonist affinity with affinity for antagonists unchanged. The increased agonist affinity was unaffected by pertussis toxin treatment, indicating it is an intrinsic property of the mutant receptor. The potency of dopamine for acute inhibition of forskolin-stimulated cAMP production in stably expressing Chinese Hamster Ovary (CHO) cells was higher for the mutant than the wild type receptor. CHO cells stably expressing D2T344K displayed enhanced responses to forskolin-stimulated adenylate cyclase activity compared with cells stably expressing the wild type D2 receptor. The increased forskolin responsiveness of adenylate cyclase is similar to the sensitization previously observed with wild type D2 receptor after agonist treatment. Adenylate cyclase responsiveness of CHO cells stably expressing D2T344K receptor was not further increased by agonist treatment. Sensitization was blocked by pertussis toxin and D2 receptor antagonists haloperidol, butaclamol, and clozapine, indicating inverse agonist activity of these compounds at D2T344K. Inverse agonist activity was further demonstrated by the finding that overnight treatment with these compounds drastically increased the density of the mutant receptor but had minimal effect on the density of the wild type receptor. Taken together, these results suggest the authors have generated a constitutively active dopamine D2 receptor capable of sensitizing adenylate cyclase in the absence of agonist activation.

Adenylyl Cyclase Inhibitors↗

PubMed2001

Differential expression of two scribble isoforms during Drosophila embryogenesis.

The tumour suppressor gene scribble (scrib) is required for epithelial polarity and growth control in Drosophila. Here, we report the identification and embryonic expression pattern of two Scrib protein isoforms resulting from alternative splicing during scrib transcription. Both proteins are first ubiquitously expressed during early embryogenesis. Then, during morphogenesis each Scrib protein displays a specific pattern of expression in the central and peripheral nervous systems, CNS and PNS, respectively. During germ band extension, the expression of the longer form Scrib1 occurs predominantly in the neuroblasts derived from the neuro-ectoderm and becomes later restricted to CNS neurones as well as to the pole cells in the gonads. By contrast, the shorter form Scrib2 is strongly expressed in the PNS and a subset of CNS neurones.

Alternative Splicing↗

PubMed2001

Views of Chinese parents on the provision of contraception to unmarried youth.

This study sought the views of Chinese parents on sex education and contraception for unmarried youth. Data were drawn from 16 focus group discussions conducted in eight sites in China in 1998-1999 with parents of unmarried children aged 18-24. While parents tended to recognise the reality of changing sexual norms, they were ambivalent with regard to sexual activity among young people and the provision of services to them. To prevent this ambivalence from posing a significant obstacle to the adoption of safe sex behaviours by young people, the dilemmas faced by parents need to be addressed through programmes for parents. Parents were clearly concerned for the well-being of their unmarried children, and keen to see their children protected from unwanted pregnancy and disease; they supported the provision of life skills education and the development of negotiation skills, self-esteem and the ability to exercise informed choice. Parents appeared willing for government to establish educational and service delivery programmes for the unmarried; it is important that government acts upon this.

Abortion, Induced↗

PubMed2001

Estrogen receptor gene polymorphism and bone mineral density in postmenopausal Chinese women.

PvuII and XbaI restriction fragment length polymorphisms (RFLPs) for the estrogen receptor gene (ERG) and its relation to bone mineral density (BMD) were examined in 454 postmenopausal Chinese women, aged 55-79 years. The RFLPs were represented as P or p (PvuII) and X or x (XbaI), with capital letters signifying the absence of and small letters the presence of restriction sites. There was no significant difference in BMD between the PP, Pp, and pp genotypes. However, women of the XX genotype had significantly higher BMD at the spine than women of the Xx or xx genotype. The magnitude of the difference in BMD was 80% of a standard deviation (SD) for BMD in elderly women and 40% of a SD in postmenopausal women. There was no statistically significant interaction between the PvuII genotype and the XbaI genotype in determining BMD. We conclude that postmenopausal Chinese women who were homozygous for the XX genotype had slightly higher BMD than the others. However, the difference in BMD was small and was unlikely to have any clinical significance. The ERG is not a major determinant of BMD in Chinese women in Hong Kong.

Aged↗

PubMed2001

Alendronate for the prevention of bone loss in patients on inhaled steroid therapy.

One hundred women on inhaled steroid therapy (dose range from 800 to <1600 microg per day) were randomized to receive 10 mg of oral alendronate or placebo (with 500 mg of calcium in the form of daily calcium carbonate). Bone mineral density (BMD) was measured at baseline, 6 months, and 12 months. The percentage changes in BMD were -0.80% in the placebo group and 2.99% in the alendronate group at the spine (p < 0.001 by analysis of covariance [ANCOVA]), and were -0.51% in the placebo group and 0.97% in the alendronate group at the femoral neck (p < 0.05 by ANCOVA). Five patients in the alendronate-treated group, and a similar number of patients in the placebo group, complained of mild gastric discomfort. We conclude that women on inhaled steroid therapy were at risk of accelerated bone loss, which could be prevented by a daily dose of 10 mg of alendronate.

Administration, Inhalation↗