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Biomedical subjects

M J Wu

Publications and source records attributed to M J Wu.

At least 55 records · Page 3Linked to original sources
PubMed1998

Usage of cryptic splice sites in citrullinemia fibroblasts suggests role of polyadenylation in splice-site selection during terminal exon definition.

Citrullinemia is a human genetic disease caused by a deficient argininosuccinate synthetase. In fibroblasts established from a citrullinemia patient with a mutation at the 3' splice site of the terminal intron of the gene, three cryptic 3' splice sites; i.e., SA1275, SA1636, and SA1663, residing on the terminal exon were activated. The usage of the cryptic sites showed a gradient, with the most downstream site having the highest usage; i.e., SA1663 > SA1636 > SA1275. However, when these cryptic sites were relocated to the internal exon, SA1636 was used the most. The splice-site strength of SA1636 was at least 10-fold higher than that of SA1663 in this situation. The results suggest that the preferential usage of SA1663 residing on the terminal exon may depend on its proximity to the poly(A) signal rather than on the strength of the splice site. Furthermore, when the strength of the downstream-most splice site increased, almost all the RNAs spliced to this site. However, in the presence of the wild-type splice site, all the RNAs were processed to the authentic site. Apparently, the selection of splice site can be revealed only when the sites being selected do not differ too much in their strength. By using a naturally occurring human mutant gene as a model, this study reveals that polyadenylation may play an important role in the selection of splice site during terminal exon definition.

Amino Acid Metabolism, Inborn Errors↗
PubMed1998

Malignancy following renal transplantation.

BACKGROUND: A markedly increased incidence of malignancy in transplant recipients is well recognized. However, the incidence and pattern of post-transplantation malignancies shows some discrepancy among different reports. The renal transplant recipients monitored at Taichung Veterans' General Hospital comprise the largest group in Taiwan. An analysis of the characteristics of post-transplant malignancies emphasizes the differences from malignancies that occur in the Taiwanese general population and those reported in Western countries. METHODS: The incidence and characteristics of de novo malignancy in 390 renal transplant recipients who underwent renal transplantation between May 1983 and June 1996 were analyzed. A total of 232 men and 158 women (mean age at transplantation: 38.5 +/- 10.7 years) were included. The relative risk for developing malignancies was calculated based on the sex- and age-matched cancer incidence of reference for the Taiwanese population; data from the Cancer Registry Annual Report in Taiwan (1989) was obtained for comparison. RESULTS: A total of 25 cancers were diagnosed in 24 renal transplant recipients, for an incidence of 6.2%. The relative risk of renal malignancy was 13.8-fold higher among transplant recipients than in the general population. The impact of gender and age on the development of post-transplantation malignancy was not significant. The most common types of cancer were transitional cell carcinoma (TCC) of the urinary tract (8/25), and hepatoma (8/25), followed by two cases of Kaposi's sarcoma. Aside from immunosuppressive agents, the high incidence of hepatoma and TCC may be attributed to the high incidence of hepatitis infection and the possible carcinogenic effect of abnormal milieu induced by uremia per se. Survival was largely dependent on the extent of disease at presentation, and post-transplantation cancer did not show more aggressive behavior if detected early. CONCLUSIONS: The high cumulative incidence of malignancies makes it imperative to define an effective safe immunosuppressive regimen to achieve a lower risk of malignancies. In the future, the prime approach to treatment of post-transplantation malignancies should begin with early detection and ensuing aggressive treatment to improve the outcome.

Adolescent↗
PubMed1997

The core domain of the tissue transglutaminase Gh hydrolyzes GTP and ATP.

Tissue transglutaminase (TGase II) catalyzes the posttranslational modification of proteins by transamidation of available glutamine residues and is also a guanosinetriphosphatase (GTPase) and adenosinetriphosphatase (ATPase). Based on its homology with factor XIIIA, an extracellular transglutaminase, the structure of TGase II is likely composed of an N-terminal beta-sandwich domain, an alpha/beta catalytic core, and two C-terminally located beta-barrels. Here we used a domain-deletion approach to identify the GTP and ATP hydrolytic domains of TGase II. Full-length TGase II and two domain-deletion mutants, one retaining the N-terminal beta-sandwich and core domains (betaSCore) and the other retaining only the core domain, were expressed as glutathione S-transferase (GST) fusion proteins and purified. GST-Full and GST-betaSCore exhibited calcium-dependent TGase activity, whereas GST-Core had no detectable TGase activity, indicating the beta-sandwich domain is required for TGase activity but the C-terminal beta-barrels are not. All three GST-TGase II fusion proteins were photoaffinity-labeled with [alpha-32P]-8-azidoGTP and were able to bind GTP-agarose. The GTPase activity of GST-betaSCore was equivalent to that of GST-Full, whereas the ATPase activity was approximately 40% higher than GST-Full. GST-Core had approximately 50% higher GTPase activity and approximately 75% higher ATPase activity than GST-Full. The GTPase and ATPase activities of each of the GST-TGase II fusion proteins were inhibited in a dose-dependent manner by both GTPgammaS and ATPgammaS. These results demonstrate that the GTP and ATP hydrolysis sites are localized within the core domain of TGase II and that neither the N-terminal beta-sandwich domain nor the C-terminal beta-barrels are required for either GTP or ATP hydrolysis. Taken together with previous work [Singh, U. S., Erickson, J. W., & Cerione, R. A. (1995) Biochemistry 34, 15863-15871; Lai, T.-S., Slaughter, T. F., Koropchak, C. M., Haroon, Z. A., & Greenberg, C. S. (1996) J. Biol. Chem. 271, 31191-31195] the results of this study indicate that the GTP and ATP hydrolysis sites are localized to a 5. 5 kDa (47 amino acid) region at the start of the core domain.

Adenosine Triphosphatases↗
PubMed1997

Selection of an adjuvant for vaccination with the malaria antigen, MSA-2.

Various formulations of the Plasmodium falciparum merozoite surface antigen, MSA-2, were made and tested in animals in order to select one for use in human vaccine trials. Recombinant constructs representing both major allelic forms of MSA-2 were formulated with a range of adjuvants and used to immunize rabbits, mice and sheep. After immunization, antibody responses obtained with the most potent adjuvants were at least tenfold greater than responses obtained with the least potent adjuvant Alhydrogel, which was used as the reference standard, although its lower potency indicated against its further use in clinical trials. Based on broadly similar results obtained with the three animal species, several adjuvants, including the water-in-oil adjuvant Montanide ISA 720, the oil-in-water adjuvant SAF-1, and liposomes containing lipid A formulated with Alhydrogel were demonstrated to be potent and potentially suitable for the clinical evaluation of MSA-2 as a candidate malaria vaccine antigen. Of these, ISA 720 was selected for further trial.

Adjuvants, Immunologic↗
PubMed1997

Another simpler bypassing dialysate technique for measuring post-haemodialysis BUN.

BACKGROUND: The most popular method for estimating post-haemodialysis BUN is the low blood flow technique. The low blood flow technique with a blood flow of 50 ml/min for 3 min may encompass the first two phases of post-haemodialysis urea rebound by access and cardiopulmonary recirculations. Some patients may have risk of clotting in extracorporeal circuit while slowing blood flow. Therefore we proposed another simpler sampling technique for measuring post-haemodialysis BUN(C2). METHODS: In the present study, 28 long-term haemodialysis patients were divided into two groups. In group 1 (n = 15), C2 sample (C2-50) was collected immediately after blood flow was slowed down to 50 ml/min for another 3 min. Then blood flow was reset to 300 ml/min. Finally, C2 sample (C2B) was obtained from arterial port at the end of bypassing dialysate for another 3 min. In group 2 (n = 13), C2 sample (C2B) was obtained from arterial port at the end of bypassing dialysate for 3 min with a blood flow of 250 ml/min. Then dialysate was reset to original flow rate and C2 sample (C2-50) was collected soon after blood flow was slowed down to 50 ml/min for another 3 min. In the meantime, recirculation rate was also checked. RESULTS: The above two groups have similar results and there are no significant differences of post-haemodialysis BUN and calculated Kt/V between low blood flow technique and bypassing dialysate technique. CONCLUSION: The bypassing dialysate technique is another simpler and practical technique for the routine estimation of post-haemodialysis BUN.

Aged↗
PubMed1997

Complications of membrane-filtration plasma exchange.

BACKGROUND: Plasma exchange (PE) has been extensively used to treat a variety of disease states in the past three decades. Although PE is commonly thought to be a relatively safe procedure, a number of unpleasant side effects may occur. To highlight the need for continuing quality assurance in providing PE service, a retrospective review of PE records over a 13-year period was undertaken. METHODS: From April 1983 to March 1996, 694 therapeutic PE procedures, membrane-filtration type, were performed on a total of 157 patients in this hospital. Plasmaflo op-05(L) (Asahi Japan) was used as the plasma separator and fresh frozen plasma of one plasma volume as replacement fluid. The PE sheets for all procedures were reviewed as were medical charts in order to evaluate clinical efficacy. RESULTS: Totally 694 PEs in 157 patients, 84 male and 73 females, ranging in age from 1 to 75 years (median, 35 years), were treated. Patients received a median of 4 treatments (range, 1 to 34). The most frequent indications were severe jaundice (41.4%), systemic lupus erythematosus (23.6%), and myasthenia gravis (15.3%). The overall effective rate was 40.8%, and was best in neurological diseases (91.4% effective). Complications of PE were noted during 36% of the procedures involving 59.2% of the patients treated. The most common adverse reactions were paresthesia (12.7%), chills (10.2%), urticaria (8.5%), chest pain (5.9%), nausea (2.9%) and dyspnea (2.0%). Less common complications included: catheter infection (0.3%), catheter oozing (1.2%), dizziness (1.3%), headache (0.4%), muscle cramps (1.3%), vomiting (0.4%), abdominal pain (0.9%), fever (0.3%), hypotension (1.3%), bleeding (0.4%), consciousness change (0.7%) and respiratory arrest (0.4%). These complications were classified as "mild" (23%), "moderate" (11.4%) and "severe" (1.6%). No deaths occurred within 24 hours after PE. CONCLUSIONS: Although the use of membrane-filtration PE represents a valuable and relatively safe therapy, some life-threatening reactions do occur.

Adolescent↗
PubMed1997

Secretion from cell culture of HDL and VLDL bearing apoB-33 with a large internal deletion.

Rat hepatoma McA-RH7777 cells synthesize and secrete two populations of apoB-containing lipoproteins: a larger, VLDL-sized population floating in the Sf 40-150 range and a smaller, LDL and HDL-sized population. Three permanently transfected cell lines of McA-RH7777 cells secreted (in addition to the endogenous lipoproteins) lipoproteins containing 1) a carboxyl-terminally truncated human apoB-53 (2377 amino acids in length); 2) a carboxyl-terminally truncated human apoB-31 (1420 amino acids in length); or 3) an internally deleted human apoB protein, apoB-18/95, containing a total of 1490 amino acid residues, equivalent in length to an apoB33. The apoB-18/95 protein contained amino acid residues 1-782 joined to 708 residues near the C-terminus of apoB (residues 36364343). All three of the apoB peptides, apoB53, apoB-31, and apoB-18/95, were present on smaller LDL-HDL-class lipoproteins, with buoyant densities in the HDL density range. The sizes of the HDL class lipoproteins agreed with prior observations that lipoprotein core circumference is directly proportional to apoB size. As HDL containing apoB-18/95 conformed to this rule, contiguous apoB amino acid sequence is not required for the rule to be obeyed. In addition, apoB-18/95, but not apoB-31, was also present on the VLDL-sized lipoproteins even in the absence of serum or oleate supplementation. As the latter two constructs encode equally sized apoB peptides, their particular amino acid sequences rather than just overall length must determine whether they can assemble into a VLDL particle.

Animals↗
PubMed1996

Identification of cholecystokinin-B/gastrin receptor domains that confer high gastrin affinity: utilization of a novel Xenopus laevis cholecystokinin receptor.

A hallmark of the mammalian brain cholecystokinin (CCK) receptor, CCK-B/gastrin (CCK-BR), is its high affinity for two structurally related peptides, CCK and gastrin. Previous radioligand binding experiments suggested that the predominant CCK receptor from Xenopus laevis brain shares high affinity for sulfated cholecystokinin octapeptide but has > or = 1000-fold lower affinity for gastrin. To determine the molecular basis for this pharmacological divergence between mammalian and lower vertebrate receptors, we isolated a cDNA encoding the X. laevis brain CCK receptor (CCK-XLR). CCK-XLR shares approximately 50% homology at the amino acid level with both the human CCK-BR and the peripheral CCK-A receptor subtypes. The recombinant X. laevis receptor has a distinct pharmacological profile of agonist and antagonist affinities and as such offers a useful tool for structure-function studies. We used CCK-XLR to map the human CCK-BR domains that confer high affinity for gastrin. A series of chimeric CCK-BR/CCK-XLR constructs was generated and pharmacologically characterized. While maintaining wild-type affinity for sulfated cholecystokinin octapeptide, receptors with increasing amino-terminal contributions from CCK-BR demonstrated a stepwise increase in gastrin affinity. Further dissection of the amino-terminal third of the human receptor, a domain that confers a > 250-fold increase in gastrin affinity, revealed the importance of interactions among at least three subdomains. Additional structural requirements for gastrin affinity mapped to a segment spanning transmembrane domains IV and V.

Amino Acid Sequence↗
PubMed1996

Long-term clinical and morphological evaluation of primary membranoproliferative glomerulonephritis.

BACKGROUND: Membranoproliferative glomerulonephritis (MPGN) is a relatively rare primary glomerulonephritis (GN). Its incidence has decreased progressively in the past two decades. To improve knowledge of this rare GN, a retrospective review of 22 patients during a 12-year period was undertaken. METHODS: From November 1982 to December 1994, from a total 814 cases of primary GN, 22 patients with primary MPGN were diagnosed. Clinical data, medical records, renal pathology and outcome were reviewed. RESULTS: Patients included 15 male and 7 females, aged from 11 to 67 years. The average follow-up period was 46.3 months, with a range of 1 to 140 months. Tissue was available for electromicroscopic study in 11 cases; of which 9 cases fulfilled morphologic criteria of Type I MPGN; the other 2 cases were Type II MPGN. The clinical presentations at diagnosis included nephrotic syndrome (86.4%), impaired renal function (63.6%), microhematuria (50%), gross hematuria (31.8%) and hypertension (50%). Low serum C3 was found in 40.9% cases, 44.4% in Type I and 50% in Type III MPGN. The positive rate of hepatitis B virus infection was 22.7% with 33.3% in Type I and none in Type III MPGN. All 22 patients received various combined antihypertensive agents, immunosuppressant, anticoagulant and antiplatelet agents at diagnosis, but 17 had progressive disease, 4 maintained normal renal function with proteinuria and only 1 had complete remission. Fifteen patients, including six Type I and no Type III MPGN, progressed to end-stage renal failure. Both patients with Type III MPGN maintained normal renal function and responded to treatment. The 5 and 10 year actuarial renal survival rates were 33.3% and 16.7% respectively. The median kidney survival time was 51.2 months. CONCLUSIONS: A majority of cases with MPGN presenting with impaired renal function (86.7%) and hypertension (85%) at diagnosis progressed to end-stage renal failure. Delayed diagnosis and poor compliance were possible reasons for compared with for worse prognosis previous reports. But two patients with Type III MPGN had favorable prognosis previously described. Treatments generally failed to halt disease progression. Since at least five cases (22.7%) maintained normal renal function after treatments, a course of immunosuppressant is probably indicated if there is no contraindication. Further study with a larger population is warranted to clarify this issue.

Adolescent↗
PubMed1995

Mayer-Rokitansky-Kuster-Hauser syndrome with immature teratoma of the ovary at age 4 years.

We describe a rare combination of Mayer-Rokitansky-Kuster-Hauser syndrome and immature teratoma of the ovary in a 4-year-old girl. The patient was admitted due to increased abdominal size. Sonagraphy and C-T scan revealed a heterogeneous mass with cystic, calcified, and solid parts. A right salpingo-oophorectomy was performed under the FIGO (International Federation of Gynecology and Obstetrics) staging of stage Ia. The diagnosis of immature teratoma, grade II, was confirmed by histopathologic examination. Agenesis of the upper third of the vagina and the uterus was also confirmed by the surgery.

Abnormalities, Multiple↗
PubMed1994

Cytokine binding to CD4+ inflammatory cells: implications for asthma.

While LCF is present in BAL early after antigen challenge, we know little about its other potential effects beyond CD4+ T cell, monocyte, and eosinophil chemotaxis and monocyte and CD4+ T cell activation. The work described here focuses on the hypothesis that the secreted protein products of T cells participate in the airway inflammatory process that underlies human asthma, and in particular that LCF could play an early role because of the unusual responsiveness of LCF-producing T to histamine. To date, most studies have addressed the measurement of cytokines derived from CD4+ T cells (e.g., IL-2, IL-3, IL-4, IL-5, and GM-CSF) in the airways of asthmatics, and attempted to correlate the presence of protein or mRNA with the complexion of the inflammatory infiltrate. These studies have been based upon the reports that there are increased numbers of CD4+ T cells in the airways of asthmatics, and that the presence of eosinophils might correlate with the secretion of TH2-type cytokines like IL-3, -4, and -5. Using this information as a background, our work has approached the problem in an entirely different way. We have focused our attention on the early events in antigen-induced asthma that are responsible for CD4+ cell accumulation in the lung, including CD4+ T cells, eosinophils, and monocytes. We have attempted to identify mechanisms by which mast cell mediators, in particular histamine, might play a role in the secretion of chemotactic lymphokines that are selective for CD4+ cells by using CD4 itself as a chemotactic factor receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Isolation, characterization and evolution of ovine major histocompatibility complex class II DRA and DQA genes.

Four full-length ovine major histocompatibility complex (MHC) class II A cDNA clones coding for new alleles of DRA, DQA1 and DQA2 genes were isolated from two ovine lambda gt10 cDNA libraries. The derived amino acid sequences of these clones resemble class II A molecules from other species in both size and structure. Restriction fragment length polymorphism analysis, using an Ovar-DRA probe on DNA from Merino and Romney sheep revealed only limited polymorphism in contrast to the high levels of polymorphism revealed by Ovar-DQA probes. Comparison of the predicted amino acid sequences for the three ovine A genes with class II A genes from five other species revealed that the most variable region of the molecule is the signal peptide. Although virtually every amino acid site shows variation, within or between species, there are some blocks of highly conserved residues. Within gene comparisons of nucleotide differences reveal that the greatest number of changes is found between the alleles of Ovar-DQA1 and -DQA2 genes and the least between Ovar-DRA1 alleles. Phylogenetic analysis of class II A sequences from several species place DRA and DQA genes on two distinct branches, with Ovar-DRA1 and BOLA-DRA, and Ovar-DQA1 and BOLA-DQA being most similar on their respective branches.

Alleles↗
PubMed1991

Identification of the ancestral haplotype for apolipoprotein B suggests an African origin of Homo sapiens sapiens and traces their subsequent migration to Europe and the Pacific.

The probable ancestral haplotype for human apolipoprotein B (apoB) has been identified through immunological analysis of chimpanzee and gorilla serum and sequence analysis of their DNA. Moreover, the frequency of this ancestral apoB haplotype among different human populations provides strong support for the African origin of Homo sapiens sapiens and their subsequent migration from Africa to Europe and to the Pacific. The approach used here for the identification of the ancestral human apoB haplotype is likely to be applicable to many other genes.

Africa↗
PubMed1991

Synthetic studies toward 9-keto-cannabinoids.

9-Keto-cannabinoid methyl ether, the precursor for many cannabinoid metabolites and analogues, was prepared from (+)-apoverbenone in 5 steps. This synthesis includes the condensation of apoverbenone with aryllithium followed by oxidation, hydrolysis of the MOM ether, acid-catalyzed cyclization, and metal ammonia reduction.

Dronabinol↗