Biomedical subjects

C M Lee

Publications and source records attributed to C M Lee.

At least 127 records · Page 7Linked to original sources

PubMed1997

Characterization of neuronal cell death induced by complement activation.

The complement system plays an important role in human immune defense mechanism. Its activation via either the classical or the alternative pathway can lead to the formation of membrane attack complex (MAC) and subsequently kills target cells. Activation of the classical pathway can be initiated with binding of C1q which is first factor of complement cascade to the Fc (fragment crystalline) region of immunoglobulin. This triggers a cascade of proteolytic events resulting in the activation of C5 convertase which cleaves C5 into C5b and C5a. The C5b then binds C6, C7, C8 to form a C5b-8 complex. Binding of C9 molecules to C5b-8 forms C5b-9, the MAC, which pore size increases as the number of C9 in the complex increases. If this membrane lesion persists and results in uncontrolled ion fluxes, the cells swell and eventually lyse. To restrict the activity of the complement system, endogenous complement inhibitors are available to regulate complement-mediated cytolysis. This enables the complement system to distinguish "self" from "foreign" and protect the host from inadvertent complement attack. Activation of the classical complement cascade has been reported in Alzheimer's disease and other neurodegenerative disorders. Recently, we demonstrated that complement activation causes neuronal cell death in vitro, and this neurodegenerative process is regulated by homologous restriction. In this article, we describe the use of two cell lines as in vitro models to evaluate cell injury/cell death induced by complement activation.

Animals↗

PubMed1997

Water sorption and solubility of resin-modified polyalkenoate cements.

The purpose of this study was to compare the water sorption and solubility of several resin-modified polyalkenoate cements. The materials evaluated included Variglass used as a restoration, base on liner; Fuji II LC, Fuji Liner; Vitrebond; Vitremer and Photac-Bond. Z100, a composite resin, was used as control. All specimens were manipulated according to the manufacturers' instructions and then subjected to water sorption and solubility tests based on the ISO 4049 requirements. Data were subjected to one-way ANOVA and Duncan's test at a 0.05 significance level. Results show that the composite resin control had significantly less water sorption than any of the resin-modified polyalkenoate cements evaluated. The degree of water sorption was product dependent and appeared to be influenced by the resin (HEMA) content. There was no apparent correlation between water sorption and solubility. Some of the resin-modified polyalkenoate cements retained water in their set structure and hence solubility could not be assessed.

Absorption↗

PubMed1997

In vivo expression of an interferon-alpha gene by intramuscular injection of naked DNA.

Acid-stable type I interferons belong to a multigene family. The biologic relevance of each subtype in vivo remains unknown. We have developed an experimental model in which muscles were transfected in situ with naked DNA plasmids encoding an IFN transgene to assess the roles of individual IFN subtypes in vivo. Murine IFN-alpha 9 gene was subcloned into several mammalian expression vectors. Adult C57BL/6 mice were injected bilaterally in regenerating tibialis anterior muscles with naked DNA 5 days after muscle injury to enhance DNA uptake and expression. In the muscles of mice given the IFN-alpha 9 plasmid constructs, acid-stable IFNs were detected by bioassay using reduction in cytopathic effect of encephalomyocarditis virus-infected L929 cells. In these same muscles, IFN-alpha 9 transcripts were identified by RT-PCR, indicating that transcription had occurred. Acid-stable IFNs were detected from days 7 to 28 post-DNA inoculation. Furthermore, these proteins were found in the sera of DNA-inoculated mice. Control groups of mice given the blank expression vectors did not produce detectable IFNs in muscle or sera as determined by bioassay, nor were transcripts detected by RT-PCR. This approach now allows investigation of the effector function of individual subtypes in various murine disease models.

Animals↗

PubMed1997

Caloric restriction reduces fiber loss and mitochondrial abnormalities in aged rat muscle.

The influence of caloric restriction (CR) initiated at 17 months of age was investigated on selected age-associated measures in skeletal muscle. Tissue from young (3-4 months) ad libitum-fed, old (30-32 months) restricted (35% and 50% CR, designated CR35 and CR50, respectively), and old ad libitum-fed rats (29 months) was studied. CR preserved fiber number and fiber type composition in the vastus lateralis muscle of the CR50 rats. In the old rats from all groups, individual fibers were found with either no detectable cytochrome c oxidase activity (COX-), hyperreactivity for succinate dehydrogenase activity (SDH++; also known as ragged red fibers [RRF]), or both COX- and SDH++. Muscle from the CR50 rats contained significantly fewer COX- and SDH++ fibers than did the muscle from CR35 rats. CR50 rats also had significantly lower numbers of mtDNA deletion products in two (adductor longus and soleus) of the four muscles examined compared to CR35 rats. These data indicate that CR begun in late middle age can retard age-associated fiber loss and fiber type changes, as well as increases in the number of skeletal muscle fibers showing mitochondrial enzyme abnormalities. CR also decreased the accumulation of mtDNA deletions.

Aging↗

PubMed1997

Reverse pedicled lateral arm flap for reconstruction of posterior soft-tissue defects of the elbow.

Posterior soft-tissue defects of the elbow are difficult to reconstruct by conventional techniques such as closure by approximation or skin graft. An ideal technique should be an easy and reliable one-stage procedure that provides predictable surgical results with regard to elbow function and cosmesis. This report details our experience in 7 patients who underwent a one-stage procedure for coverage of the posterior elbow employing the reverse pedicled lateral arm flap. All flaps survived and all patients were able to resume full range of motion of the elbow joint at the 6-month follow-up. Complications included forearm paraesthesia in 3 patients and conspicuous scarring in a young female patient. We emphasize two valuable refinements in surgical technique including measuring posterior elbow defect in full flexion and postoperative elbow extension splinting. In trauma-related defects of the posterior elbow, a preoperative angiogram is important before raising this flap.

Adolescent↗

PubMed1997

Endoscopic injection sclerotherapy with 1.5% Sotradecol for bleeding cardiac varices.

The authors retrospectively studied the efficacy of endoscopic injection sclerotherapy (EIS) with 1.5% Sotradecol (STD) in patients with bleeding cardiac varices (CV). Case histories of 27 patients with large, isolated, bleeding CVs were reviewed. Case records of another 27 patients with isolated esophageal varices (EV), matched for age, sex, and year EIS was performed, were selected from a computer data bank as controls. Using a small volume (2-4 ml) of injection per vessel, the rate of immediate control of bleeding was 66.7% (18 of 27) in the CV group and 70.4% (19 of 27) in the EV group. The early rebleeding rate was higher for patients in the EV group (48.1%, 13 of 27) than for those in the CV group (18.5%, 5 of 27) (p = 0.0209). On the other hand, it was more difficult to control the rebleeding from CV (p = 0.00494). In terms of mortality, there was no statistically significant difference between the CV and EV groups (33.3 versus 29.6%) within 1 week after EIS, but the 1-month post-EIS mortality rate was significantly higher (p = 0.0278) in the CV group (18 of 27, 66.7%) than in the EV group (10 of 27, 37.0%). Among those in the CV group who died of late complications within 1 month after EIS, three died of recurrent hemorrhage, five of infection, and one of viscus perforation. In the EV group, only two patients died of infection. Thus, it was concluded that EIS with small volumes (2-4 ml) of 1.5% STD was equally effective in controlling immediate bleeding from CV and EV. However, it was more difficult to control early rebleeding from CV, and the mortality and complications within 1 month after EIS were significantly higher in patients with CV. These observations are currently under careful study and evaluation.

Adult↗

PubMed1997

Molecular subtyping of the HIV-1 V3 loop sequences detected in HIV-1-positive patients in southern Taiwan.

Polymerase chain reaction and nucleotide sequence analysis were performed to amplify and determine the V3 loop sequences of human immunodeficiency virus type 1 (HIV-1) from ten seropositive patients at National Cheng Kung University Hospital, Tainan. The nucleotide sequences and the deduced amino acid (a. a.) sequences of these V3 regions were compared with those of known HIV-1 prototypes. The V3 loop a. a. sequences detected in eight individuals belong to subtype B which predominates in North America and Europe, whereas two individuals were infected with HIV-1 subtype E which is mainly found in the heterosexual populations of Thailand. Sequence analysis of these variant HIV-1 strains revealed a number of interesting features and a phylogenetic tree was also constructed according to the V3 loop nucleotide sequences of these variant strains and HIV-1 isolates from other parts of the world. Furthermore, our results suggest that the north vs south geographical separation in terms of HIV-1 epidemiology in Taiwan is insignificant.

Amino Acid Sequence↗

PubMed1997

Growth of trypanosomes in vivo, host body weight gains, and food consumption in zinc-deficient mice.

This study examined the effect of zinc deficiency on food consumption and the growth of mice infected with Trypanosoma musculi or immunized with parasite products. In addition, the effects of zinc deficiency on the growth and development of parasites in vivo was studied. Infected mice consumed more food than noninfected mice, and the level of food consumption in the zinc-deficient mice was much less and showed general decline during the observation period. Also, infected mice on both full-complement and zinc-deficient diets gained more body weight than control mice. Throughout the observational period, trypanosomes from zinc-deficient mice showed considerably higher variability in size as determined by coefficient of variation. In both dietary groups, the average length of trypanosomes was not significantly different.

Animals↗

PubMed1997

Radiological finding of Menetrier's disease: a case report.

Menetrier's disease is a relative rare disease. Its origin remains obscure. The characteristics are folded thickened mucosa resulted from hyperplasia of gastric glands. This report concerns a 30-year-old man who received upper gastrointestinal (UGI) series, abdominal sonography, UGI endoscopy and computed tomography (CT) because of UGI bleeding and abdominal discomfort which finally led to the diagnosis of this disease. Radiological imaging such as UGI series and CT scan was useful to arrive at an accurate diagnosis.

Adult↗

PubMed1997

Hepatic cells' mitotic and peritoneal macrophage phagocytic activities during Trypanosoma musculi infection in zinc-deficient mice.

The effects of zinc deficiency on hepatic cell mitotic and peritoneal macrophage phagocytic activities were examined in mice infected with Trypanosoma musculi or immunized with parasitic products. On a full-complement or pair-fed diet, infected and homogenate-inoculated mice showed mitotic activity gains of 7.9% to 80.3% and 6.5% to 99.0%, respectively. Infected and homogenate-inoculated mice on a zinc-deficient diet showed 21.8% to 95.7% and 17.2% to 65.2%, respectively, more dividing liver cells compared with controls. In comparison to controls, macrophages isolated from infected and homogenate-immunized mice on full-complement or pair-fed diets had phagocytized 13.4% to 31.4% more latex particles from day 50 to 80. In the zinc-deficient group, macrophages isolated from infected mice had significant numbers of phagocytized latex particles (1.8% to 38.5%) from day 20 to day 80 compared with controls. The homogenate-immunized mice also had increased numbers (18.6 to 30.8%) of phagocytized latex particles.

Animals↗

PubMed1997

Frequency of the CCR5 delta 32 mutant allele in HIV-1-positive patients, female sex workers, and a normal population in Taiwan.

A specific 32-nucleotide deletion mutant of the CCR5 gene (Accr5), the coreceptor gene for human immunodeficiency virus type 1 (HIV-1), can effectively suppress the transmission and pathogenesis of the virus. Individuals homozygous for the delta ccr5 allele resist primary macrophage-tropic HIV-1 infection, despite multiple high-risk sexual exposures. This gene deletion is relatively common among Caucasians but uncommon among Africans, Asians, and South Americans. We used polymerase chain reaction (PCR) technology to determine the frequency of the delta ccr5 allele in a Taiwanese population with diverse health status and social backgrounds. Subjects included 24 HIV-1-infected persons in the northern and southern parts of Taiwan; 131 HIV-1 high-risk, licensed female sex workers in the northern part of the island (21% of whom were aborigines); and 187 unrelated, healthy, HIV-1-negative individuals in southern Taiwan. PCR with primers encompassing the entire CCR5 gene was used to explore possible deletions at regions other than the 32-nucleotide area in the female sex workers. No ccr5 deletions were detected, indicating that they are rare or absent in the Taiwanese population. This finding implies that delta ccr5 is not likely to be part of the defense against the spread of HIV-1-infection in Taiwanese.

Acquired Immunodeficiency Syndrome↗

PubMed1997

Small bowel stenosis from blunt abdominal trauma.

A patient with a segmental stricture of the small bowel resulting from blunt abdominal trauma is reported. Symptoms and signs developed as vague abdominal distension with chronic, incomplete small bowel obstruction four weeks after the accident. A small bowel barium examination provided the important images for preoperative evaluation.

Abdominal Injuries↗

PubMed1996

The kidneys that nobody wanted: support for the utilization of expanded criteria donors.

The continuing shortage of cadaveric donors necessitates constant reappraisal of donor refusal criteria. From 1/1/95 to 3/20/96, 180 renal transplants were performed at our center. Of these, 26 were kidney/pancreas, 30 pediatric, 37 live donor adult, and 87 adult cadaveric renal transplants (CRT). In the CRT group there were 31 recipients of kidneys that all other local transplant centers declined. We retrospectively compared this group of kidneys that nobody wanted (KNW) to the remaining 56 CRTs (controls) performed at our center during the same period. Of the 31 recipients of KNW, 18 received kidneys declined for reasons of advanced age, defined as > or =60 years (including 8 who also had a history of hypertension, 4 who also had >10% sclerosed glomeruli on biopsy, and 3 also declined based upon donor quality because of acute injury), 8 for donor quality alone (e.g., prolonged hypotension), 3 on the basis of biopsy results alone, and 2 for anatomic abnormalities. Twelve recipients of KNW were "dual transplanted" with both donor kidneys. Of 27 donor variables compared between the KNW and control groups, only donor age (52+/-17 versus 40+/-17 years, respectively) and lowest total 4-hr urine output (327+/-208 versus 507+/-437 cc, respectively) proved to be significantly different (p< or =0.05). Of the 25 recipient variables examined, a significant difference was found only in serum creatinine at one month posttransplant (2.6+/-1.8 versus 1.8+/-1.0 mg/dl, respectively), although there was no difference in serum creatinine at three and six months. Actuarial one year patient (100 vs. 95%) and graft (97 vs. 91%) survival, KNW vs. controls respectively, are excellent to date. Further analyses showed no differences in outcome variables between recipients of KNW versus controls when the donor age was > or =60 years. Similar outcome was achieved by transplanting both kidneys from a KNW donor into a single recipient as compared with single-kidney transplantation from control donors. Careful donor-recipient pairing using kidneys from advanced-age donors for smaller, advanced-age recipients provided good short-term outcome. In conclusion, there was no significant difference in short-term outcome in recipients of KNW versus controls despite differences in donor age and lowest total 4-hr urine output. We believe that, with careful consideration, existing donor selection criteria can be expanded to include certain donors previously considered unusable.

Adult↗

PubMed1996

Beta-amyloid induces apoptosis in human-derived neurotypic SH-SY5Y cells.

Alzheimer's disease is primarily characterized by neurofibrillary tangles, senile plaques, and neurodegeneration. The major component of senile plaques is the beta-amyloid peptide (beta A4), which has been shown to be toxic to neurons in vitro. To date, the mechanism of beta A4-induced neurotoxicity has not been determined in human-derived neurons. In this report, we present evidence that programmed cell death, or apoptosis, is involved in the neurotoxic activity of beta A41-40 and beta A425-35 in the human-derived neurotypic cell line SH-SY5Y cells. The evidence for beta A4-induced apoptosis includes: (1) labeling of cell nuclei for DNA nicked ends; (2) morphological changes in ultrastructure that are consistent with apoptosis (shrunken cells with pyknotic nuclei); (3) DNA laddering which can be blocked by aurintricarboxylic acid (ATA), an inhibitor of apoptosis; and (4) marginal release of intracellular lactate dehydrogenase (LDH), an indicator of necrosis. These results suggest that apoptosis is the major event involved in beta A4-induced cytotoxicity in SH-SY5Y cells. A variety of reagents were tested to determine their activities against beta A4-induced DNA laddering. Nerve growth factor and free radical scavengers were inactive in this system. While ATA blocked DNA laddering resulting from either beta A4 or okadaic acid treatment, Congo red specifically attenuated only beta A4-induced DNA fragmentation. These results suggest that compounds which bind fibrillar beta-peptides can protect this human neurotypic cell line against apoptosis induced by beta A4.

Amyloid beta-Protein Precursor↗

PubMed1996

Synthesis and structure-activity relationships of 2-pyridones: a novel series of potent DNA gyrase inhibitors as antibacterial agents.

Two novel series of 2-pyridones were synthesized by transposition of the nitrogen of 4-quinolones to the bridgehead position. This subtle interchange of the nitrogen atom with a carbon atom yielded two novel heterocyclic nuclei, pyrido[1,2-alpha]pyrimidine and quinolizine, which had not previously been evaluated as antibacterial agents and were found to be potent inhibitors of DNA gyrase. Quinolizines with a methyl group at the 9-position such as (S)-45a (ABT-719) demonstrate exceptional broad spectrum antibacterial activity. Most notably, they are active against resistant bacteria such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant strains of enterococci, and ciprofloxacin-resistant organisms. In addition, 2-pyridones also possess favorable physiochemical and pharmacokinetic properties. These 2-pyridones were synthesized from the commercially available starting materials by 10-17 linear transformations. The structure of an adduct yielded by this sequence, (S)-45a (ABT-719), was determined by X-ray crystallographic analysis.

Animals↗

PubMed1996

Characterization of a new genotype II hepatitis delta virus from Taiwan.

Three genotypes of HDV, which may be associated with different clinical pictures and epidemiological patterns, have been identified. In contrast to Type I and Type III HDV, both of which have multiple isolates, Type II HDV so far includes only a single isolate (Japan-1) from a low prevalence area (Japan). Recently, Type II has been reported to be the predominant genotype in Taiwan, which is also a low prevalence area, and is associated with less aggresive disease than Type I. However, the sequence and structure of these viruses have not been characterized. The complete characterization of a second member (Taiwan-3 isolate) of the Type II HDV from Taiwan is reported. These two Type II HDV isolates (Taiwan-3 and Japan-1) have 93.8% nucleotide homology and 89.3% amino acid homology, respectively. These shared sequences establish the common characteristics of Type II viruses. Sequence comparisons of various HDV genotypes show that the autocatalytic region of the RNA is relatively conserved between Type I and Type II (88.5-95.6% homology) but is significantly divergent in Type III (76.8-80.3% homology). The hypervariable region (nucleotides 1602-658) of RNA, however, is heterogeneous (64.9-73.0%) among all three genotypes. The delta antigen sequence is also very heterogeneous (64.9-73.0%). Most strikingly, the C-terminal sequence (19 amino acids) of the large delta antigen is almost completely different in each of the three genotypes. The heterogeneity in this region of three HDV genotypes may be a basis for their different biological properties, and the nucleotide sequences of this region can be used to differentiate the different genotypes of HDV. The consensus sequence in the four previously identified conserved domains of HDV RNA is defined more precisely.

Adult↗

PubMed1996

Age-associated mitochondrial DNA deletions in mouse skeletal muscle: comparison of different regions of the mitochondrial genome.

The abundance of mitochondrial DNA (mtDNA) deletions has been shown to increase with age in a number of species and may contribute to the aging process. Estimating the total mtDNA deletion load of an individual is essential in evaluating the potential physiological impact. In this study, we compared three 5-kb regions of the mitochondrial genome: one in the major arc, one in the minor arc, and a third containing the light strand origin of replication. Through PCR analysis of mouse skeletal muscle, we have determined that not all regions produce equal numbers of age-associated deletions. There are, on average, twofold more detectable deletions in the major arc region than in the minor arc region. Deletions that result in the loss of the light strand origin of replication are rarely detected. Furthermore, the mechanism of deletion formation seems to be similar in both the major and minor arcs, with direct repeats playing an important, although not essential, role.

Aging↗

PubMed1996

Expression in human endothelial cells of ADP-ribosylation factors, 20-kDa guanine nucleotide-binding proteins involved in the initiation of vesicular transport.

ADP-ribosylation factors (ARFs) are approximately 20-kDa, guanine nucleotide-binding proteins, initially discovered as stimulators of cholera toxin ADP-ribosyltransferase activity and subsequently shown to participate in vesicular trafficking. Five of the six mammalian ARFs have been identified in human tissues by molecular cloning. They fall into three classes (class I: ARFs 1-3; class II: ARFs 4, 5; class III: ARF 6) based on deduced amino acid sequence, size, phylogenetic analysis, and gene structure. Similar to the rab family of approximately 20 kDa guanine nucleotide-binding proteins, the ARFs appear to function in specific trafficking pathways. The presence of a specific ARF might serve as a marker for that pathway. To verify expression of ARF mRNA and protein in human umbilical vein endothelial cells, immunoreactivity using antibodies specific for each ARF class, quantitative polymerase chain reaction (PCR) using ARF-specific, internal cRNA standards containing unique restriction enzyme cleavage sites introduced by point mutations, and Northern analysis with probes specific for ARFs 1, and 3-6, were utilized. PCR and Northern analysis were in agreement in showing that amounts of mRNA for ARF 1 and ARF 4 were similar and higher than those of ARF 3 and ARF 5 which were greater than ARF 6. Primarily, Class 1 ARF proteins were detected by immunoreactivity, with the majority in the supernatant fraction. The relative expression of ARFs in endothelial cells thus differs from that in neuronal tissues where it had been found that ARF3 is the predominant species.

ADP-Ribosylation Factor 6↗