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Biomedical subjects

J Chai

Publications and source records attributed to J Chai.

At least 19 recordsLinked to original sources
PubMed2001

Seroprevalence of Borna disease virus in domestic animals in Xinjiang, China.

To investigate the animals infected with Borna disease virus (BDV) in Xinjiang, China, we examined for BDV antibodies in the sera from groups of 20 horses, sheep and cattle, and from 165 wild rodents (18 species) by ELISA and immunoblot. The serological study disclosed the presence of antibodies to both BDV-p24 and -p40 in the horses (20%) and sheep (25%), whereas no apparent positive reaction was detected either in cattle or rodents. The results suggested that BDV is prevalent in horses and sheep in the district investigated.

Animals↗
PubMed2001

Structural basis of caspase-7 inhibition by XIAP.

The inhibitor of apoptosis (IAP) proteins suppress cell death by inhibiting the catalytic activity of caspases. Here we present the crystal structure of caspase-7 in complex with a potent inhibitory fragment from XIAP at 2.45 A resolution. An 18-residue XIAP peptide binds the catalytic groove of caspase-7, making extensive contacts to the residues that are essential for its catalytic activity. Strikingly, despite a reversal of relative orientation, a subset of interactions between caspase-7 and XIAP closely resemble those between caspase-7 and its tetrapeptide inhibitor DEVD-CHO. Our biochemical and structural analyses reveal that the BIR domains are dispensable for the inhibition of caspase-3 and -7. This study provides a structural basis for the design of the next-generation caspase inhibitors.

Apoptosis↗
PubMed2001

A conserved XIAP-interaction motif in caspase-9 and Smac/DIABLO regulates caspase activity and apoptosis.

X-linked inhibitor-of-apoptosis protein (XIAP) interacts with caspase-9 and inhibits its activity, whereas Smac (also known as DIABLO) relieves this inhibition through interaction with XIAP. Here we show that XIAP associates with the active caspase-9-Apaf-1 holoenzyme complex through binding to the amino terminus of the linker peptide on the small subunit of caspase-9, which becomes exposed after proteolytic processing of procaspase-9 at Asp315. Supporting this observation, point mutations that abrogate the proteolytic processing but not the catalytic activity of caspase-9, or deletion of the linker peptide, prevented caspase-9 association with XIAP and its concomitant inhibition. We note that the N-terminal four residues of caspase-9 linker peptide share significant homology with the N-terminal tetra-peptide in mature Smac and in the Drosophila proteins Hid/Grim/Reaper, defining a conserved class of IAP-binding motifs. Consistent with this finding, binding of the caspase-9 linker peptide and Smac to the BIR3 domain of XIAP is mutually exclusive, suggesting that Smac potentiates caspase-9 activity by disrupting the interaction of the linker peptide of caspase-9 with BIR3. Our studies reveal a mechanism in which binding to the BIR3 domain by two conserved peptides, one from Smac and the other one from caspase-9, has opposing effects on caspase activity and apoptosis.

Amino Acid Motifs↗
PubMed2001

Cardiomyopathy in transgenic mice with cardiac-specific overexpression of serum response factor.

Serum response factor (SRF), a member of the MCM1, agamous, deficiens, SRF (MADS) family of transcriptional activators, has been implicated in the transcriptional control of a number of cardiac muscle genes, including cardiac alpha-actin, skeletal alpha-actin, alpha-myosin heavy chain (alpha-MHC), and beta-MHC. To better understand the in vivo role of SRF in regulating genes responsible for maintenance of cardiac function, we sought to test the hypothesis that increased cardiac-specific SRF expression might be associated with altered cardiac morphology and function. We generated transgenic mice with cardiac-specific overexpression of the human SRF gene. The transgenic mice developed cardiomyopathy and exhibited increased heart weight-to-body weight ratio, increased heart weight, and four-chamber dilation. Histological examination revealed cardiomyocyte hypertrophy, collagen deposition, and interstitial fibrosis. SRF overexpression altered the expression of SRF-regulated genes and resulted in cardiac muscle dysfunction. Our results demonstrate that sustained overexpression of SRF, in the absence of other stimuli, is sufficient to induce cardiac change and suggest that SRF is likely to be one of the downstream effectors of the signaling pathways involved in mediating cardiac hypertrophy.

Actins↗
PubMed2001

[Evaluation of radiation dose and radiation risk for dental patients].

1. The collective dental radiation dose in Israel in 1998 is 42.86 Sv. 2. The collective dental radiation is responsible for a mortality of about 2.14 people per year in Israel, and a similar number of morbidity from non-lethal cancer. 3. It seems that the quality of the picture in dental radiographs in Israel is not satisfactory, so is the dentists' level of knowledge about it. 4. Exposure to dental radiographs may be reduced by half if measures are taken to ensure the quality of the radiographs and the knowledge of dentists on the subject.

Clinical Competence↗
PubMed2000

Structural and biochemical basis of apoptotic activation by Smac/DIABLO.

Apoptosis (programmed cell death), an essential process in the development and homeostasis of metazoans, is carried out by caspases. The mitochondrial protein Smac/DIABLO performs a critical function in apoptosis by eliminating the inhibitory effect of IAPs (inhibitor of apoptosis proteins) on caspases. Here we show that Smac/DIABLO promotes not only the proteolytic activation of procaspase-3 but also the enzymatic activity of mature caspase-3, both of which depend upon its ability to interact physically with IAPs. The crystal structure of Smac/DIABLO at 2.2 A resolution reveals that it homodimerizes through an extensive hydrophobic interface. Missense mutations inactivating this dimeric interface significantly compromise the function of Smac/DIABLO. As in the Drosophila proteins Reaper, Grim and Hid, the amino-terminal amino acids of Smac/DIABLO are indispensable for its function, and a seven-residue peptide derived from the amino terminus promotes procaspase-3 activation in vitro. These results establish an evolutionarily conserved structural and biochemical basis for the activation of apoptosis by Smac/DIABLO.

Amino Acid Sequence↗
PubMed2000

Heparin-free hemodialysis in the treatment of hypernatremia in severely burned patients.

BACKGROUND: Hypernatremia in severely burned patients is associated with high morbidity and mortality rates. As the causes of hypernatremia in major burn patients are still not clear, hemodialysis is the method of choice for the treatment. While hemodialysis is effective for the control of hypernatremia, it can cause bleeding complications that may be fatal for burn patients with extensive wounds and potential gastro-intestinal mucosal damage. CLINICAL DATA: In the present study heparin-free hemodialysis in which the heparin is firmly absorbed to the haemofiltration membrane, hemophan, dispensed with systemic use of heparin. In two extensively burned patients with burn area of 100% TBSA and 98% TBSA respectively and hypernatremia with serum sodium concentration as high as 169 and 158 mmol/l respectively, heparin-free hemodialysis was performed five times and three times each. RESULTS: Hypernatremia was satisfactorily corrected with no interference to the coagulation system in the two patients as indicated by clinical observation and biochemical analysis. The patient with burn area of 98% TBSA survived and the patient with burn area of 100% TBSA died of wound coverage failure 6 weeks after injury because of non-availability of autograft. CONCLUSION: Heparin-free hemodialysis is an effective and safe method in the treatment of hypernatremia in extensively burned patients.

Adult↗
PubMed2000

Photophysical processes of a copolymer containing naphthalene and carbazole rings.

The photophysical processes of copolymer formed by copolymerization of beta-naphthyl-methacrylate (NMA) with vinylcarbazole (VCZ) were studied. The results show that when the solution of copolymer (NMA-VCZ) in THF is located in a low concentration range (about 10(-8) mol/l), the fluorescence emission is in good agreement with that of NMA monomer and the excimer is formed with gradual increase in concentration of copolymer (NMA-VCZ). The fluorescence of copolymer (NMA-VCZ) can be efficiently quenched both by electron donors and acceptors where the quenching effects follow the Stern-Volmer equation. The dimolecular exciplex between copolymer (NMA-VCZ) and N,N-dimethylaniline (DMA) is formed and the triple exciplex is also observed in the same system.

Carbazoles↗
PubMed2000

[Exclusive mapping on polydactyly with markers on chromosome 7 and 2 in a Chinese kindred].

OBJECTIVE: This study was aimed at mapping polydactyly related genes in a Chinese kindred. METHODS: Linkage analysis was performed using 7 markers on chromosome 7 and 1 marker on chromosome 2. RESULTS: Pairwise linkage analysis showed no linkage between the markers and polydactyly related gene in the kindred. CONCLUSION: The polydactyly related gene in this kindred may be located on a new locus.

Chromosome Mapping↗
PubMed1999

[Experimental study on the mechanisms of enhancement of aerobic glycolysis of muscles in burns and sepsis--the verification of the existence and the enhancement of the aerobic glycolysis of muscles in early postburn period and sepsis].

OBJECTIVE: To verify if aerobic glycolysis exists in the muscle cells in normal rats and to analyze the changes in aerobic glycolysis in the muscle cells in the early postburn period and in septic states. METHOD: Using septic model of rats, we established the in vitro muscle incubation system with sufficient oxygen supply as well as the NADH fluoremetric method for the detection of trace amount of lactate in the samples. Extensor digitorium longus (EDL) and soleus muscles which represent two types of muscle fiber were studied. RESULTS: In the early postburn period as well as in septic states, the lactate production of muscle cells was significantly elevated as compared to the normal controls even though the muscles were incubated in a fully oxygenated media. The levels of aerobic glyoclysis, as well as its changes in postburn period and in septic states, vary depending on the difference in the fiber composition of the muscles. CONCLUSION: Muscle cells might develop a kind of metabolic enhancement which is referred to as aerobic glycolysis rather than the metabolic defect which results from tissue hypoperfusion and hypoxia in the early postburn period as well as in septic states. This provides us a special insight to elucidate the mechanisms of the metabolic derangement in the early postburn period and in sepsis.

Animals↗
PubMed1999

[Analysis of factors influencing healing time of burn wounds].

OBJECTIVE: To analyze the factors influencing healing time, length of hospital stay and hospital costs in burn patients. METHODS: Seven hundred and ninety-one burn patients with principal component analysis were studied retrospectively. RESULTS: There were some factors that influence healing time, including total area of burn, the area of full-thickness burn, the area of partial-thickness burn, inhalation injury, sepsis, shock, visceral complication, combined injuries, the size of surgical excision, the time of surgical excision, whether or not excision of burn wound was done in shock stage, and use of antibiotic, etc. Further analysis indicated that the patients undergo escharectomy during shock stage had better recovery with lower incidence of visceral complications and sepsis, especially in those with major burn over 30 percent TBSA. CONCLUSION: To reduce healing time of burn patients, there are many effective methods such as the prevention and treatment of shock, sepsis, visceral complication, and appropriate use of antibiotics. The most important factor to reduce healing time of burn patients is escharectomy as early as possible for major burns.

Adult↗
PubMed1999

[Hemodynamic monitoring in 52 serious burn patients in ten years].

OBJECTIVE: To determine the benefit of hemodynamic monitoring for resuscitation of burn shock. METHODS: A group of 52 burned patients with mean burn area of (69.9 +/- 20.1)% TBSA burn injury (range 31%-100%), and mean III burn area of (60.4 +/- 13.6)% TBSA were included in this study. Swan-Ganz catheters were inserted to monitor hemodynamics including RAP, PAP, PAWP, HR, CO, CI, and SI, etc. after admission at 8, 16, 24, 36, 48, 72, and 96 hours postburn. RESULTS: It was reasonably safe to perform invasive monitoring during early resuscitation. With the guide of hemodynamic monitoring, evidence of global hypovolemia disappeared at 24 hours after burn injury with appropriate resuscitation therapy. CONCLUSION: Invasive hemodynamic monitoring may be necessary to optimize resuscitation of serious burn patients with reasonable safety.

Adolescent↗
PubMed1998

Linkage analysis of the genetic markers of the candidate genes with non-insulin dependent diabetes mellitus in Chinese families.

OBJECTIVE: To explore the relationship between the genetic markers of the candidate genes (insulin receptor, glucose transporter 2 and glucokinase) and non-insulin dependent diabetes mellitus (NIDDM) in Chinese pedigrees. METHODS: Genomic DNA of 87 members in 12 Chinese NIDDM pedigrees was amplified using PCR technique. Denaturing polyacrylamide gel electrophoresis was applied to detect short tandem repeat polymorphisms. The linkage program was used under the models of autosomal dominant and recessive. The individuals with impaired glucose tolerance (IGT) of age < or = 45 and age > 45 were counted as affected and unknown status respectively. RESULTS: Linkage of insulin receptor gene and NIDDM was strongly and significantly rejected with total LOD score of-infinity (theta = 0.000). Linkage analysis of glucose transporter 2 gave the result with total LOD score of 2.646 (theta = 0.000) in 4 pedigrees. Linkage of glucokinase and NIDDM was of significance with total LOD score reaching 3.150 in the integration of 6 pedigrees. CONCLUSIONS: Mutations in or near the insulin receptor gene are unlikely to be the major cause of inherited predisposition to NIDDM in Chinese pedigrees that are related in this study, not excluding the principal role in the other Chinese or populations, while the mutations/variations near or at the glucose transporter 2 gene locus might be something of the cause, which needs more data to be ascertained, of familial NIDDM in Chinese pedigrees. However, the variations in or near the glucokinase gene might play a dominant role in the development of NIDDM in some Chinese and represent a subgroup of common NIDDM.

Adult↗
PubMed1998

MHCWeb: converting a WWW database into a knowledge-based collaborative environment.

The World Wide Web (WWW) is useful for distributing scientific data. Most existing web data resources organize their information either in structured flat files or relational databases with basic retrieval capabilities. For databases with one or a few simple relations, these approaches are successful, but they can be cumbersome when there is a data model involving multiple relations between complex data. We believe that knowledge-based resources offer a solution in these cases. Knowledge bases have explicit declarations of the concepts in the domain, along with the relations between them. They are usually organized hierarchically, and provide a global data model with a controlled vocabulary. We have created the OWEB architecture for building online scientific data resources using knowledge bases. OWEB provides a shell for structuring data, providing secure and shared access, and creating computational modules for processing and displaying data. In this paper, we describe the translation of the online immunological database MHCPEP into an OWEB system called MHCWeb. This effort involved building a conceptual model for the data, creating a controlled terminology for the legal values for different types of data, and then translating the original data into the new structure. The OWEB environment allows for flexible access to the data by both users and computer programs.

Artificial Intelligence↗
PubMed1997

A multicenter longitudinal clinical trial of a new system for restorations.

STATEMENT OF PROBLEM: A new method for fabrication of crowns and fixed partial dentures (Procera system) that involves electric discharge machining and copy milling has been developed. The metal used is unalloyed titanium, which can be processed as a single coping or multiple units joined to a pontic by laser welding. PURPOSE: The single-unit coping or the fixed partial denture (FPD) substructure is then veneered with a low-fusing porcelain. MATERIAL AND METHODS: In this article the clinical application of this technique was evaluated by six major universities in the United States. A total of 114 patients participated in this study, which involved 126 restorations (55 maxillary and 71 mandibular prostheses). There were 179 abutments, of which 73 were crowns and 53 were three-unit FPDs. Surface and color, anatomic form, and margin integrity were assessed 1 month after cementation and at 1 year with the California Dental Association (CDA) quality assessment evaluation system. RESULTS: No statistically significant differences in CDA scores between the 1 month evaluations and the 1 year assessments were found for surface and color (p = 0.68), anatomic form (p > 0.99), or margin integrity (p = 0.57). By use of the lowest ranking in the three categories as the overall quality of the restoration, only 3.3% (two crowns and two FPDs) were not acceptable at the 1-month visit and 4.5% (two crowns and three FPDs) were not acceptable at the 1-year evaluation. At-the 1-month visit 96.6% (114) of the restorations were considered to be satisfactory, whereas 95.5% (107 restorations) were evaluated similarly at the 1-year evaluation. CONCLUSIONS: The Procera system demonstrated, by use of the CDA criteria, its capability to produce quality prostheses that were rated satisfactory more than 95% of the time after insertion and maintained this high rating at least for 1 year.

Adolescent↗
PubMed1997

Isolation of specific DNA probes for detection of Cryptococcus neoformans.

We report the construction of a genomic library and isolation of repetitive DNA probes from Cr. neoformans that are species- and variety-specific. The inserts of the genomic library were in a range of 0.3-1.8 kb, which were in normal distribution in length. Among 592 clones of the genomic library, there were 400(67.6%) clones inserted repetitive DNA sequence and 192(32.4%) inserted single copy DNA sequence of the Cr. neoformans genome. From the library, three specific probes were identified. Clone pCNIIA6 was serotype A-specific, pCNIIB5 species-specific, and pCNIIIG1 variety-specific (var. neoformans). On the basis of the high specificity and sensitivity of the signals observed by hybridization, we suggest that these probes provide a means for both biotyping and early diagnosis of Cr. neoformans.

Cryptococcus neoformans↗