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Biomedical subjects

L Lin

Publications and source records attributed to L Lin.

At least 307 records · Page 17Linked to original sources
PubMed1994

Management of insufficiency of posterior cruciate ligaments.

BACKGROUND: This study aims to evaluate the role of different methods in management of insufficiency of posterior cruciate ligament (PCL) that were used in VGH-Taipei. METHODS: 129 cases with insufficiency of PCL were collected to evaluate, according to functional and dynamic criteria, the results of different managements which were graded as good, fair, or poor. The patients were divided into 3 groups, i.e. group 1 with conservative rehabilitation therapy, group II with surgical reattachment, and group III with surgical ligament reconstruction that had 3 subgroups including IIIa reconstruction with medial head of gastrocnemius, IIIb with patellar tendon and IIIc with artificial ligament. The artificial ligaments used were Leeds-Keio ligament (group IIIcl), Dacron ligament (group IIIc2) and Goretex ligament (group IIIc3). The duration from injury to treatment varied from 3 days to 12 years with mean 45 weeks. The followup period was from 38 months to 112 months with mean 62 months. RESULTS: The results revealed 6 cases of good grade (25%) and 18 cases of fair grade (75%) in group 1, 20 cases of good grade (95%) and 1 case of fair grade (5%) in group II, 14 cases of good grade (40%), 10 cases of fair grade (29%) and 11 cases of poor grade (31%) in group IIIa, 3 cases of good grade (100%) in group IIIb, 13 cases of good grade (82%) and 3 cases of fair grade (18%) in group IIIcl, 19 cases of good grade (83%), 3 cases of fair grade (12%) and 1 case of poor grade (4%) in group IIIc2, and 3 cases of good grade (43%), 3 cases of fair grade (43%), and 1 case of poor grade (14%) in group IIIc3. CONCLUSIONS: Conservative intervention could be satisfactory in some cases with PCL insufficiency, especially in cases with isolated PCL injury, while surgical methods is mandatory in the others, especially in cases with chronic symptomatic PCL insufficiency.

Adolescent↗
PubMed1994

A clinical study on treatment of vascular complications of diabetes with the sugar--reducing and pulse--invigorating capsule.

The capsule is effective in replenishing qi, nourishing yin, activating blood, and resolving stasis. It can correct abnormalities in blood rheology, improve fat metabolism, enhance functioning of the islets of Langerhans, lower blood sugar, and alleviate clinical symptoms. Efficacious also against the chief vascular complications of diabetes, it helps in abating myocardial anoxia, improving left heart function, stimulating blood circulation to the brain, resisting coagulation and resolving thrombosis, also dilating the arteries of the legs. It is of some benefit in early diabetic retinopathy and renal diseases.

Adult↗
PubMed1994

Modulation of c-MET proto-oncogene (HGF receptor) mRNA abundance by cytokines and hormones: evidence for rapid decay of the 8 kb c-MET transcript.

The c-MET proto-oncogene product is a transmembrane tyrosine kinase receptor which was recently shown to transmit an array of important cellular responses induced by Hepatocyte Growth Factor (HGF). These biological effects include induction of mitogenesis, motogenesis, morphogenesis, metastogenesis and anti-tumor activity on a variety of epithelial cells. All of these processes are known to be associated with normal and abnormal tissue growth and development. The 190 kDa c-MET protein is encoded by a major transcript of 8 kilobases (kb), which is reported to be expressed predominantly in epithelial tissues. The expression pattern of c-MET mRNA and protein are drastically modified in many tumor tissues and cell lines. Currently, no information is available on the molecular mechanisms that regulate c-MET mRNA level. In the present communication, we report for the first time that the inflammatory cytokines such as IL-1 alpha, IL-6 and TNF-alpha, as well as TGF-beta 1, EGF, HGF and the steroidal hormones (estrogen, progesterone, tamoxifen and dexamethasone) markedly influence the steady-state levels of the 8 kb c-MET mRNA in human carcinoma cell lines derived from human tissues such as ovary, breast and endometrium. We demonstrate that c-MET receptor protein is present at high levels in primary tumors of human ovaries (clear cell carcinomas). We present evidence that the 8 kb c-MET mRNA undergoes rapid degradation with a half-life of less than 30 min and that this decay can be quickly inhibited by cycloheximide. Our results suggest that the expression of the c-met proto-oncogene resembles that of an immediate early response gene.

Cytokines↗
PubMed1993

Alpha-helix stability and the native state of myoglobin.

Native proteins fold to form structures that contain secondary-structure regular patterns in the peptide backbone, such as alpha-helix, beta-structure, and turns with high frequency. The role of this secondary structure in stabilizing the native folded state is presently unclear. Alanine substitutions at helical sites in myoglobin show no correlation with the helical propensity of the side chains involved. In an effort to demonstrate a relationship between the effect of a side chain on stabilizing secondary structure and the native structure, we have carried out site-directed changes in the sequence of the helical protein sperm whale myoglobin. Fully buried hydrophobic side chains were exchanged for similar side chains at sites corresponding to midhelical positions in the native state. The results show a positive correlation between the alpha-helix-forming ability of the substituted side chain and the stability of the mutant proteins, when differences between the size of the side chains are taken into account. If, in addition, each type of amino acid substitution is averaged over different sites, the helix propensities of the amino acids account for much of the residual variation. This implies that the stability of the native state of a protein is coupled to that of secondary structural elements in the structure. In magnitude, the net contribution of propensity differences is smaller than hydrophobic effects, but not negligible in terms of the net free energy of unfolding.

Mutagenesis, Site-Directed↗
PubMed1993

Photochemical inactivation of cell-associated human immunodeficiency virus in platelet concentrates.

Photochemical decontamination (PCD) of platelet concentrates, with adequate preservation of platelet function, has been shown using 8-methoxypsoralen (8-MOP) and long wavelength UV light (UVA). To further evaluate this technique, models for the inactivation of pathogenic human cell-associated viruses and integrated proviral sequences are required. We have assessed the ability of the PCD technique to inactivate cell-associated human immunodeficiency virus 1 (HIV-1) in platelet concentrates. We correlated PCD inhibition of HIV-1 infectivity with 8-MOP-DNA adduct formation in contaminating nucleated cells, and measured the inhibition of polymerase chain reaction (PCR)-mediated amplification of cellular DNA sequences as a surrogate for inactivation of integrated proviral nucleic acid sequences. After PCD treatment (8-MOP 300 micrograms/mL, UVA 17 mW/cm2) for 60 minutes, 0.5 x 10(6) plaque-forming units (PFU)/mL of cell-associated HIV-1 were inactivated and no virus was detectable by infectivity assay. After 60 minutes of PCD, 15 8-MOP-DNA adducts per 1,000 bp were formed, while in the absence of UVA, no adducts were formed. PCR-mediated amplification of a 242-bp cellular DNA sequence (HLA-DQ-alpha) was inhibited when greater than eight psoralen-DNA adducts per 1,000 bp were present. These studies indicate that high titers of cell-associated HIV-1 in platelet concentrates were inactivated by PCD, and the numbers of 8-MOP-DNA adducts in nucleated cells were sufficient to inhibit amplification of DNA segments that encode for as few as 80 amino acids. Based on the frequency of 8-MOP-DNA adducts, for the 10-kb HIV-1 genome, the probability of an integrated genome without at least one 8-MOP adduct after 60 minutes of PCD was 10(-33).

Blood Component Transfusion↗
PubMed1993

Enhancement of the stability and activity of aspartase by random and site-directed mutagenesis.

Enzymatic generation of mutant libraries for random mutagenesis of aspartase gene from E. coli J2 was made. A mutant enzyme with 4-fold increase in aspartase activity was found. It is stable at pH7.5-9.0 (wild-type: pH7.0-8.0); heat stability and alpha-helicity are higher than those of the wild-type. By using site directed mutagenesis, the aspartase was activated by replacement of Lys-126 with an arginine residue. The mutation produced functional alterations without appreciable structure changes. The optimum pH for the mutant enzyme is 8.5. The stable pH range is 7.0-9.0. Heat stability is higher than that of the wild-type one. Activity of the mutant enzyme is about 5-fold as much as that of wild-type one.

Amino Acid Sequence↗
PubMed1993

Isolation and characterization of C-reactive protein (CRP) cDNA and genomic DNA from Xenopus laevis. A species representing an intermediate stage in CRP evolution.

C-reactive protein (CRP) is a prototypic acute phase protein in human and rabbit. Although it is structurally and functionally conserved from invertebrate to human, there are species-specific differences in patterns of expression and putative function. To further investigate the biological significance, regulation, and evolution of CRP, we isolated Xenopus CRP and subsequently derived and sequenced corresponding cDNA and the genomic clones. The structure and expression of Xenopus CRP were also compared to those of the other CRPs. Analyses of the amino acid sequence and the nucleotide sequence reveal that the mature Xenopus CRP is a 222-amino acid protein preceded by a 16-residue signal peptide. During development, Xenopus CRP is expressed, only when the liver appears, and therefore is not likely to play a role in early embryonic development. Compared to other species, Xenopus CRP is present at an intermediate low level of < 1 microgram/ml in the normal serum. Unlike human and rabbit CRP, Xenopus CRP is not induced by turpentine or heatshock treatment. The heatshock consensus sequence (Woo, P., Korenberg, J. R., and Whitehead, A. S. (1985) J. Biol. Chem. 265, 4136-4142) are not present in the Xenopus CRP gene. It is suggested that Xenopus CRP represents a transitional period in CRP evolution when host defenses switched from primitive innate immunity to a much more complex immune system. The constitutive functions of CRP gradually became less essential as the result of the development of a complex immune system.

Amino Acid Sequence↗
PubMed1993

Membrane topology and biogenesis of eukaryotic signal peptidase.

The signal peptidase complex (SPC) is a hetero-oligomeric membrane protein containing subunits of 12, 18, 21, 22/23, and 25 kDa. The 18- and 21-kDa subunits are mammalian homologs of SEC11 protein, which is necessary for signal peptide processing and cell viability in the yeast Saccharomyces cerevisiae. The functional and/or structural contributions of the 12-, 22/23-, and 25-kDa subunits to SPC activity have not yet been elucidated. To explore the structure of SPC subunits and their relationships to signal peptide processing and protein translocation, we have examined their endoplasmic reticulum (ER) membrane topology and biogenesis. Signal peptidase activity and SPC subunits are resistant to protease treatment in intact and detergent-solubilized membranes. Heat-denatured SPC subunits and SPC subunits translated in vitro are, however, protease sensitive, suggesting that the assembly of the oligomeric complex confers protease resistance. To define the membrane topology of SPC subunits, both wild-type subunits and subunit fusion proteins containing additional sites for N-linked glycosylation were assembled into microsomal membranes in vitro. Despite the presence of multiple hydrophobic domains, each subunit is anchored to the ER membrane by a single amino-terminal transmembrane domain in an Ncytoplasmic Cexoplasmic (type II) orientation. This topology places the bulk of the protein mass in the ER lumen and positions a putative serine-containing active site domain in SPC 18 and 21 at the same relative distance from the membrane as the analogous region in Escherichia coli leader peptidase. These studies have also revealed that, in spite of the temporal and perhaps physical association of the SPC with the process of protein translocation, SPC subunits integrate into the ER membrane by a signal recognition particle-dependent pathway and, hence, rely on the existence of a preformed translocation apparatus for their own membrane assembly.

Amino Acid Sequence↗
PubMed1993

Effects of alanine substitutions in alpha-helices of sperm whale myoglobin on protein stability.

The peptide backbones in folded native proteins contain distinctive secondary structures, alpha-helices, beta-sheets, and turns, with significant frequency. One question that arises in folding is how the stability of this secondary structure relates to that of the protein as a whole. To address this question, we substituted the alpha-helix-stabilizing alanine side chain at 16 selected sites in the sequence of sperm whale myoglobin, 12 at helical sites on the surface of the protein, and 4 at obviously internal sites. Substitution of alanine for bulky side chains at internal sites destabilizes the protein, as expected if packing interactions are disrupted. Alanine substitutions do not uniformly stabilize the protein, either in capping positions near the ends of helices or at mid-helical sites near the surface of myoglobin. When corrected for the extent of exposure of each side chain replaced by alanine at a mid-helix position, alanine replacement still has no clear effect in stabilizing the native structure. Thus linkage between the stabilization of secondary structure and tertiary structure in myoglobin cannot be demonstrated, probably because of the relatively small free energy differences between side chains in stabilizing isolated helix. By contrast, about 80% of the variance in free energy observed can be accounted for by the loss in buried surface area of the native residue substituted by alanine. The differential free energy of helix stabilization does not account for any additional variation.

Alanine↗
PubMed1993

Chronic effects of intracerebral ventricular enterostatin in Osborne-Mendel rats fed a high-fat diet.

Enterostatin, a pentapeptide found in the procolipase molecule of the pancreas, has been infused chronically into the lateral ventricle of Osborne-Mendel rats for 11 days. Treatment with enterostatin acutely lowered food intake more in the treated animals than in the vehicle-treated controls. Weight gain and serum insulin were significantly reduced by enterostatin. Corticosterone was significantly increased in rats receiving chronic infusions of enterostatin into the lateral ventricle and was also increased following an acute ICV injection of enterostatin. CRH antagonist did not block the acute feeding response to enterostatin in Sprague-Dawley rats. The elevation of corticosterone during chronic infusion of enterostatin reduced the level of hepatic glucocorticoid receptor as measured by Western blot. We conclude that body weight gain of OM rats is reduced by centrally administered enterostatin, and that the acute effects of enterostatin on food intake are not mediated through stimulation of CRH secretion.

Animals↗
PubMed1993

The peptide enterostatin may produce early satiety.

The time course of feeding, grooming, exploration, and sleeping behaviors has been measured following treatment with enterostatin, the signal pentapeptide from procolipase. The peptide was injected intraperitoneally prior to presenting food, and the frequency of feeding and grooming activity, drinking, and rest or sleeping were observed at 10-s intervals for 60 min. Enterostatin did not delay the onset of feeding but shortened the time spent eating compared to saline injected controls. Conversely, grooming activity appeared earlier following enterostatin, activity was reduced, and resting behavior occurred earlier with this peptide. There were no changes in the drinking behavior. For the first hour following enterostatin, eating represented 20.8% of the time, grooming 9.2%, activity 18.3%, and rest or sleep 47.2%, with drinking making up the other 4.4%. In contrast, saline-injected animals ate for 27.1% of the time, groomed for 12.4%, were active 28.5% of the time, had sleep or rest time equal to 27.9%, and drank for 4.1% of the time. In fasted animals, the onset of grooming, the decrease in activity, and the increase in time sleeping occurred earlier than with saline. These studies support the concept that enterostatin decreases food intake by producing early satiety.

Animals↗
PubMed1993

Genotyping and association analysis of HLA-B61 in Japanese.

The distribution of HLA-B61-related alleles, B*4002-B*4006, was examined in the Japanese population by using PCR-SSO and PCR-RFLP methods. About half of the B61-positive individuals possessed B*4002 and the remaining half possessed B*4006. In addition, these two major B61 alleles were separately associated with different HLA-C alleles: B*4002 exhibited a strong linkage disequilibrium with Cw10, whereas B*4006 was strongly associated with C blank and DR9. Amino acid residues that contribute to the serologic epitopes of the B61 group and their relationships with other HLA-B locus antigens are discussed.

Alleles↗
PubMed1993

Substitution of a hydrophobic residue alters the conformational stability of Shaker K+ channels during gating and assembly.

A leucine residue at position 370 (L370) in 29-4 Shaker K+ channels resides within two overlapping sequence motifs conserved among most voltage-gated channels: the S4 segment and a leucine heptad repeat. Here we investigate the effects observed upon substitution of L370 with many other uncharged amino acid residues. We find that smaller or more hydrophilic residues produce greater alterations in both activation and inactivation gating than does substitution with other large hydrophobic residues. In addition, subunits containing less conservative substitutions at position 370 are restricted in their assembly with wild-type subunits and are unlikely to form homomultimeric channel complexes. Consistent with the idea that L370 influences the tertiary structure of these channels, the results indicate that L370 undergoes specific hydrophobic interactions during the conformational transitions of gating; similar interactions may take place during the folding, insertion, or assembly of Shaker K+ channel subunits.

Amino Acid Sequence↗
PubMed1993

Ventricular adenine nucleotide translocator mRNA is upregulated in dilated cardiomyopathy.

OBJECTIVE: A disturbed energy transfer involving the adenine nucleotide translocator across the inner mitochondrial membrane has been suggested to be one specific pathogenetic mechanism in dilated cardiomyopathy. Pretranslational steady state expression of this protein in dilated cardiomyopathy was investigated. METHODS: Concentrations of adenine nucleotide translocator were quantified by solution hybridisation. The enzyme or protein expressions of citrate synthase, lactate dehydrogenase, and creatine kinase with isozymes were determined. Analysis was performed on specimens from the left and right ventricles from six organ donor hearts, six explanted hearts with dilated cardiomyopathy, two explanted hearts with ischaemic cardiomyopathy, and from papillary muscles from seven patients operated on for mitral regurgitation. RESULTS: The ejection fraction in patients with mitral regurgitation was 50(10)%, significantly higher (p < 0.001) than in patients with dilated cardiomyopathy (23(5))%. In mitral regurgitation and in ischaemic cardiomyopathy left ventricular adenine nucleotide translocator mRNA concentrations did not differ from those in donor hearts. In dilated cardiomyopathy, adenine nucleotide translocator mRNA concentrations were significantly increased (p < 0.001). Upregulation was more pronounced in right ventricular than in left ventricular myocardium (p < 0.01). The lactate dehydrogenase M subunit fraction was increased to a similar degree in dilated cardiomyopathy and in mitral regurgitation (p < 0.05). Citrate synthase activity was significantly decreased only in dilated cardiomyopathy (p < 0.005). On the other hand, the creatine kinase B subunit content was significantly higher in mitral regurgitation than in dilated cardiomyopathy (p < 0.001). CONCLUSIONS: Despite signs of increased anaerobic and depressed oxidative capacities, dilated cardiomyopathy was specifically characterised by pretranslational upregulation of adenine nucleotide translocator.

Adolescent↗
PubMed1993

Increased expression of the lactate dehydrogenase M subunit in myocardial regions with decreased thallium uptake.

OBJECTIVE: In ischaemic heart disease, the heart muscle is subjected to repeated episodes of regional ischaemia or to a constant underperfusion. The purpose of the present investigation was to study the myocardial metabolic adaptation to this stress. METHODS: Eighteen male patients with ischaemic heart disease were studied by biopsies taken from the left ventricular septum during bypass surgery. Citrate synthase, total lactate dehydrogenase and its H and M subunits, coenzyme Q10, and myoglobin were determined in all biopsies. Concentrations of ATP, ADP, and AMP were determined and energy charge calculated in the biopsies from the patients with ischaemic heart disease. Biopsies from the septal region of hearts obtained from brain dead kidney and liver donors were used as reference and preoperative myocardial thallium scintigraphy was performed in the patients with ischaemic heart disease to relate the myocardial biochemical markers to thallium uptake at the biopsy site. RESULTS: Myocardial activities of citrate synthase as well as contents of coenzyme Q10 and myoglobin in patients with ischaemic heart disease were not different from those of the reference group, and no linear relation was found between these three markers on the one hand and thallium uptake on the other. The energy charge was directly related and the M subunit of lactate dehydrogenase inversely related to the thallium uptake. CONCLUSION: The results suggest an absence of adaptation to ischaemia in terms of increased myocardial oxidative capacity and O2 transport and storage capacity. Furthermore, it is indicated that a stressed energy metabolism with increasing severity of ischaemic heart disease enhances anaerobic metabolism and induces a shift in myocardial lactate dehydrogenase subunit fractions.

Adolescent↗
PubMed1993

Schizophrenic delusions among Koreans, Korean-Chinese and Chinese: a transcultural study.

In this transcultural study of schizophrenic delusions among Koreans, Korean-Chinese and Chinese, many delusions were shown to be different among the three groups in their frequency and content and the differences could be explained by sociocultural and political factors. Delusional themes sensitive to influence by sociocultural or political situations and changes seem to be 'family', 'love affairs', 'religious matters', 'economic matters', 'specific physical damage' and 'political themes.' Delusions about 'family', 'love affair', 'being raped', 'religious matters' and 'economic and business matters' were most frequent in Koreans. Delusions of 'blood-relatedness', 'longevity' and 'political themes' were most frequent in Korean-Chinese. Delusions of 'bloodsucking and brain or viscera extracted' and 'poison or being pricked by poisoned needle' were most prominent in Chinese.

Adult↗