Biomedical subjects

J H Chang

Publications and source records attributed to J H Chang.

At least 145 records · Page 8Linked to original sources

PubMed1992

Tuberculosis of the ribs: a recurrent attack of rib caries.

Rib tuberculosis is an extremely rare condition with the incidence not exceeding 3 percent of all skeletal tuberculosis. The authors experienced a recalcitrant case of pulmonary tuberculosis accompanied by chest wall cold abscesses involving ribs recurring at a new site in approximately 10 months despite of medical and surgical treatment. The patient has twice taken thoracotomy for abscess drainage and during the second thoracotomy, a partial resection of involved ribs was performed.

Adolescent↗

PubMed1991

Large scale screen for transposon insertions into cloned genes.

We describe a method of screening for transposon insertions in or near Drosophila loci that correspond to cloned DNA sequences. We mobilize a modified P element transposon that carries a bacterial plasmid origin of replication and a drug-resistance marker. The genomic sequences flanking each transposon insertion site can then be rescued as a plasmid in Escherichia coli. Libraries of such plasmids, representing pools of transposon-mutagenized individuals, are used as hybridization probes against cloned sequences to determine whether a transposon has inserted next to a particular site in the genome. The number of loci that can be screened simultaneously by this procedure is quite large. We have screened an array of cDNA clones representing almost 700 distinct loci against libraries representing 760 mutagenized flies, and we obtained hybridization signals to 7 different cDNAs. Three of these events have been analyzed in detail and represent genuine insertions near genomic sequences that correspond to the cDNAs.

Animals↗

PubMed1991

Secretin as a potential mediator of antiulcer actions of mucosal protective agents.

Recently, we have reported that several nonacid agents including phenylpentol, methanol extract of licorice root (FM 100), plaunotol, and teprenon stimulate release of endogenous secretin in humans, dogs, and rats. The latter three are antiulcer agents developed in Japan that have a protective effect on the gastric mucosa. We have clearly shown that plaunotol inhibits postprandial gastrin release and gastric acid secretion that parallel the increase in plasma secretin concentration. It has also been recently demonstrated that the secretin-induced inhibition of gastric acid secretion in rats is completely blocked by indomethacin, a potent inhibitor of prostaglandin synthesis. It appears that the inhibitory action of secretin on gastric acid secretion is mediated mainly by endogenous prostaglandins. Because the three antiulcer agents FM 100, plaunotol, and teprenon have been shown to increase the content of endogenous prostaglandins in the gastric mucosa, endogenous secretin released by these agents may play a significant role in their mucosal protective action. It is concluded that the antiulcer effect of these drugs could in part be attributable to their unique ability to release endogenous secretin, and that secretin is a potential mediator of the antiulcer actions of mucosal protective agents.

Animals↗

PubMed1991

Long-term results of implantation of posterior chamber intraocular lens by suture fixation.

We reviewed the long-term results of implantation of posterior chamber intraocular lens (PC IOL) by suture fixation in 23 patients without zonular or capsular support. In terms of preoperative state, 15 were aphakic, 5 had cataracts and 3 were aphakic with concurrent corneal opacity. The latter had penetrating keratoplasty as well at the time of surgery. They were followed up for more than 1 year, and the best corrected vision remained the same or improved in all cases after surgery. The transscleral suture fixation-related complications included vitreous hemorrhage, hyphema and retinal detachment.

Adult↗

PubMed1991

Progress in pediatric surgery. Historical aspects.

Although thoracic afflictions may be traced to the prehistoric age, successful thoracic surgery was a development of the late nineteenth and early twentieth centuries. From 1543 to 1661, Vesalius, Servetus, Harvey and Malpighi established the dynamic anatomy of the pulmonary system. Boyle, Hooke, Black and Lavoisier elaborated upon the respiratory gases between 1660 and 1794. Although the drainage of empyema had been known since Hippocratic times, the underwater seal drainage bottle to prevent pneumothorax was not invented until 1872. At the turn of the century, Sauerbruch delayed the development of thoracic surgery for 30 years by opposing the use of positive pressure ventilation, which had not only been known to the ancients but also in clinical practice since the mid-1800s. Once positive pressure ventilation was established, routine successful thoracic surgery still had to await the development of safe blood transfusion by Landsteiner (1900, 1940) and the availability of antibiotics discovered by Chain, Florey and Waksman in the 1940s. Techniques and instrumentation were then developed for the safe and routine surgery of specific thoracic organs.

History, 16th Century↗

PubMed1990

Structure of the gene for rat nucleolar protein B23.

Protein B23 is an abundant RNA-associated nucleolar phosphoprotein involved in the ribosome assembly process. Previous studies showed that two forms of the protein (B23.1 and B23.2) are generated from a single gene via alternative splicing of 3' exons at the mRNA level (Chang, J. H., and Olson, M. O. J. (1989) J. Biol. Chem. 264, 11732-11737). We now report the structure of the complete B23 gene which spans 11-kilobases of DNA and contains 12 exons coding for the 294 amino acid residues. B23.1 mRNA is encoded by exons 1-9, 11, and 12, whereas exons 1-10 code for the B23.2 mRNA. Each exon codes for a relatively short segment of the protein (2-40 amino acid residues). The exons, which are distributed unevenly over the length of the gene, are separated by introns varying in size between 122 base pairs and 2.2 kilobases. Southern blot analyses using a probe derived from the untranslated segment of exon 10 suggests that a single expressed gene is present in the rat genome. Additional genomic clones contained apparent processed pseudogenes for protein B23. Primer extension studies and comparison with a processed pseudogene reveal a probable transcription initiation site at position -96 from the first ATG. The 5' region of the gene contains several possible regulatory elements. Three GC boxes which are potential binding sites for transcription factor Sp1 were found, including one within the first intron. A segment of about 1500 base pairs in the 5' region is unusually rich in the dinucleotide CpG. Although no CCAAT box was found a well-defined TATA box is present at position -126. The latter feature suggests that the B23 gene has some properties of tissue-specific genes in addition to the predominant characteristics of housekeeping genes.

Amino Acid Sequence↗

PubMed1990

Comparison of antigen expression on normal urothelial cells in tissue section and tissue culture.

Antigenic characterization of urothelial cells cultured from normal adult ureter was performed. These cells were cultured using a simplified isolation and culture technique and a commercially available serum-free medium. The cells growing in these cultures had epithelioid morphology and normal quantities of DNA. The antigen expression on these cultured normal urothelial cells was evaluated using a panel of monoclonal antibodies: 5G6.4, AN43, URO-5, anti-keratin and anti-blood group antibodies, and 425 (anti-epidermal growth factor receptor). Lower levels of anti-A and AN43 binding on cultured cells were observed than are seen on urothelial cells in sections of normal ureter, while the binding of anti-blood group H, 5G6.4, and URO-5 was unchanged. Binding of anti-epidermal growth factor receptor antibody 425 was improved if the cells were grown in medium lacking epidermal growth factor. These results confirm the urothelial origin of these cultured urothelial cells but indicate that some antigenic differences between cultured normal urothelial cells and urothelial cells in situ in the normal ureter exist.

ABO Blood-Group System↗

PubMed1990

Characterization of monoclonal antibodies to young-adult worms of Angiostrongylus cantonensis.

Three IgG1 and one IgG2a monoclonal antibodies were obtained by fusion of NS-1 cells with spleen cells of BALB/C mice immunized with young-adult worm antigen of A. cantonensis. These 4 monoclonal antibodies were specific to A. cantonensis without cross-reactivity to any antigens of Toxocara canis, Ascaris suum, Clonorchis sinensis, Dirofilaria immitis, Paragonimus westermani, Gnathostoma spinigerum, Strongyloides stercoralis and Anisakis spp. detected by ELISA. The affinity constants of monoclonal antibodies specific to young-adult worms antigen of A. cantonensis were in the range of 10(7) M-1 to 10(9) M-1. The immunoblots showed that the 4 monoclonal antibodies recognized epitope on molecular weight of 204 kiloDaltons. They will be utilized to purify their corresponding antigen by an immunoaffinity column for the specific immunodiagnosis.

Angiostrongylus↗

PubMed1990

A cryodamage model for studying corneal nerve regeneration.

This study used a transcorneal freezing technique to produce a 2-mm circular, central wound in the rabbit cornea for investigating corneal nerve regeneration. All the corneal cells, nerves, and associated Schwann cells were dead inside the wound, but the extracellular matrix components remained intact. The destroyed epithelium and endothelium were replaced in 1 and 5-7 days, respectively. The necrotic keratocytes and stromal and subepithelial nerves were removed completely in 1-3 days by invading macrophage-like cells. The wounded stroma was repopulated centripetally by migrating keratocytes between days 1-5. Two types of nerve growth were identified in the stroma. The first type was novel sprouting of straight, long neurites between days 2-21, initially from the undamaged, periwound nerves and later from regenerated stromal nerves inside the wound. These small-caliber neurites proliferated in a random and disorderly pattern both inside and outside the wound and sometimes terminated on stationary, stellate keratocytes. The second type was genuine regrowth of stromal and subepithelial nerves in a centripetal direction between days 3-7. Schwann cells appeared on the newly formed nerves starting on day 4 or 5. A near-normal pattern and size of the nerves were established in the wound as early as day 10. In the epithelium, transient, wound-oriented neurites (days 1-3), single nerves, and semileashes (days 4-10) appeared. A near-normal leash pattern was restored between days 10-21 only at the wound periphery. Thus, in this model, the major groundwork of nerve regeneration occurred between days 3-10, simultaneously, at all three levels of nerve organization. These data suggest that nerve-Schwann cell interaction contributes to the restoration of stromal and subepithelial nerves, whereas a reparative epithelium deficient in trophic activity may account for the incomplete regrowth of epithelial nerves. The cryodamage model offers an efficient and multifaceted system for the experimental study of corneal nerve regeneration.

Animals↗

PubMed1990

[Survey of Enterobius vermicularis infection among school children in Tainan City].

A survey was conducted for enterobiasis, in six primary schools at Tainan city. The survey was conducted in 1986, involving 8,120 school children. The manner of testing, was two consecutive day, adhesive cellophane paper perianal swabs. The test resulted in general infection rate of 30.4%. The positive rates among those primary school children were significantly different (chi 2-test, p less than 0.001). The highest rate (40.3%), was in Shih-Men primary school and the lowest rate (18.7%) in Pao-Jeng primary school. Gender occurrence of enterobiasis was determined by making a statistic analysis between sex. We found significantly higher occurrence in males (32.4%) as opposed to females (28.3%) (chi 2-test, p less than 0.001). The infection rates were also significantly different by grade (chi 2-test, p less than 0.001). The highest rate was found in the lower grades (35.3%), the next in the middle grades (32.4%), and the lowest in the higher grades (21.6%). A questionnaire demonstrated that the family status and personal hygiene are the most important factors in transmission of pinworm infection, among the group surveyed. Moreover, the educational levels, occupations of parents, and facilities of bathrooms, (between both primary schools) were also found significantly associated with the transmission of pinworm infection. Therefore, we believe that these factors play a role in transmission of pinworm infection among school children.

Age Factors↗

PubMed1989

A single gene codes for two forms of rat nucleolar protein B23 mRNA.

Protein B23 (38 kDa, pI = 5.1) is an abundant RNA-associated nucleolar phosphoprotein and putative ribosome assembly factor. A full length cDNA clone (lambda JH1) encoding a major expressed form of rat protein B23, now designated B23.1, was reported recently (Chang, J. H., Dumbar, T. S., and Olson, M. O. J. (1988) J. Biol. Chem. 263, 12824-12837). In this paper the isolation from a rat brain library and sequence of a cDNA clone (lambda JH2) coding for a second form (B23.2) of protein B23 is reported. Isoforms B23.1 and B23.2 are polypeptides of 292 and 257 amino acids, respectively. The 5'-untranslated regions of the two cDNAs and the amino-terminal 255 amino acids of the proteins are identical in the two isoforms. However, the 3'-untranslated regions of the mRNAs are completely different, and the dipeptide Gly-Gly in B23.1 (residues 256 and 257) is replaced by Ala-His in B23.2 indicating that the former is not a precursor of the latter. The finding of AGGT sequences in the 3' regions of lambda JH1 suggest the presence of intron-exon boundaries at the point where the two cDNAs begin to differ. To investigate the origin of the two isoforms, two rat genomic libraries were screened with oligonucleotide probes based on sequences from the unique regions of the two cDNAs. One of the genomic clones isolated (lambda JH125) contained a 6.5-kilobase fragment encoding the 3' end of both cDNAs. lambda JH125 contains four exons designated W, X, Y, and Z in the order indicated. Exons W and X encode 36 amino acids at the carboxyl terminus of B23.2, whereas exons W, Y, and Z encode the carboxyl-terminal 71 amino acid residues of B23.1. Exons X and Z each contain distinct 3'-untranslated sequences in which are found polyadenylation signals. These data suggest that two different mRNAs are formed by alternative splicing of separate 3' segments onto a common 5' region.

Amino Acid Sequence↗

PubMed1989

A standard of comparison for acute surgical necrotizing enterocolitis.

We reviewed 187 cases of documented neonatal necrotizing enterocolitis (NEC) from 1976 to 1988. Of these patients, 111 infants underwent celiotomy for acute surgical complications. The following protocol of operative indications was employed: pneumoperitoneum, localized mass, abdominal wall erythema, portal venous air, and clinical deterioration, singly or in any combination. Clinical deterioration was defined as falling platelet count, rising or falling white blood cell count, left shift in the myeloid series, persistently or progressively low pH, and increasing frequency of apnea or bradycardia. Overall mortality was 15% (28 of 187). For the patients who underwent celiotomy, all had histologic confirmation of NEC. Ninety-five had localized disease, and 16 had diffuse disease. All of the former had resection and diverting enterostomy with 85 (89.5%) surviving; none with diffuse disease survived, P less than 0.0001. Forty-one infants with NEC weighed less than 1,000 g; 25 underwent surgery and 15 (60%) survived. Fifty-one of the 159 surviving neonates (32%) developed intestinal strictures. All neonates with strictures have had resection and successful reconstruction of their gastrointestinal tract. These indications and surgical principles resulted in a high degree of diagnostic accuracy and a low degree of surgical mortality.

Clostridium↗

PubMed1989

Effect of plaunotol on release of plasma secretin and pancreatic exocrine secretion in humans.

Plaunotol, an acyclic diterpene alcohol is a new antiulcer agent derived from the leaves of the plau-noi plant. We investigated the effect of plaunotol on the release of endogenous secretin with radioimmunoassay and exocrine pancreatic secretion, using a dye dilution technique with polyethylene glycol 4,000 as a nonabsorbable marker in eight human volunteers. Intrajejunal administration of plaunotol (pH 6.5) in three different doses (80, 160, and 320 mg/30 min) resulted in significant increases in both plasma secretin concentration and pancreatic bicarbonate secretion in a dose-related manner (r = 0.819 and 0.701, p less than 0.001, respectively). Bicarbonate outputs produced by plaunotol correlated well with plasma secretin concentrations (r = 0.727, p less than 0.001). Amylase output was also increased significantly by plaunotol. However, the response was not dose-dependent from that of bicarbonate output. These results indicate that endogenous secretin is released by plaunotol in humans and suggest that the increased pancreatic bicarbonate secretion can be attributed to the increased plasma secretin concentration.

Adult↗

PubMed1989

Plaunotol stimulates endogenous secretin release and exocrine pancreatic secretion in rats.

The effect of the new antiulcer agent plaunotol on the release of endogenous secretin and the pancreatic exocrine secretion was investigated in anesthetized rats. In 48 rats with pancreatic and biliary diversion, continuous intraduodenal infusion of plaunotol in 3 graded doses (5, 20 and 80 mg/h/rat) resulted in significant increases in both circulating plasma secretin concentration and pancreatic exocrine secretion, including volume and bicarbonate output, in a dose-dependent manner (r = 0.655, p less than 0.001; r = 0.598, p less than 0.001; r = 0.436, p less than 0.01, respectively). The pancreatic bicarbonate output was closely correlated to plasma secretin concentrations (r = 0.631, p less than 0.001). Amylase output also increased after plaunotol administration, but not in a dose-dependent manner (r = 0.092, n.s.). These findings suggest strongly that the increase in pancreatic secretion of fluid and bicarbonate output was mainly due to increased endogenous secretin release resulting from plaunotol administration.

Amylases↗

PubMed1989

Implantation of posterior chamber intraocular lenses by suture fixation without capsular and zonular support.

We implanted sulcus-fixated posterior chamber intraocular lenses (PCL) in three cataractous, six aphakic, and four eyes during penetrating keratoplasty due to corneal opacity in the absence of capsular and zonular support. This technique has been successfully performed in all cases and produced good visual outcome in 12 eyes (93%). In four eyes which had penetrating keratoplasty and the fixation of PCL, one developed vitreous hemorrhage and one developed corneal graft rejection.

Adult↗

PubMed1989

[Inhibitory effect of CR 1409 (cholecystokinin antagonist) on pancreatic exocrine secretion in rats].

New cholecystokinin (CCK) receptor antagonist, CR 1409 (lorglumide), was evaluated for anti-CCK activity on pancreatic exocrine secretion in anesthetized rats in vivo, compared with proglumide. Both CR 1409 in a dose range of 0.04-25 mg/kg-hr and proglumide in a dose range of 30-600 mg/kg-hr given intravenously, showed significant inhibitory effect on pancreatic secretion in terms of juice volume and amylase output stimulated by intravenous CCK-8 (0.06 micrograms/kg-hr), in a dose-related manner. CR 1409 is about 1000 times more potent than proglumide, based on ED 50. Furthermore, intravenous administration of either CR 1409 (5 mg/kg-hr) or proglumide (600 mg/kg-hr) resulted in significant suppression on pancreatic secretion stimulated by intraduodenal casein in a dose of 400 mg/hr. Thus, very potent CCK receptor antagonist, CR 1409, inhibited pancreatic exocrine secretion stimulated by not only exogenous CCK, but also intraduodenal casein in rats.

Amylases↗

PubMed1988

cDNA and deduced primary structure of rat protein B23, a nucleolar protein containing highly conserved sequences.

Protein B23 (Mr/pI = 38,000/5.1) is a major RNA-associated nucleolar phosphoprotein which contains highly acidic segments and has a high affinity for silver ions. Using synthetic oligonucleotides as probes cloned cDNAs encoding protein B23 were isolated and characterized. One of the cDNAs, obtained from a rat brain library, contained an insert of 1232 base pairs of DNA encoding a polypeptide of 292 amino acid residues. Segments of the protein sequence were confirmed by partial sequencing of CNBr fragments from rat hepatoma protein B23. The protein contains a methionine-rich amino-terminal sequence and two highly acidic segments in the center of the sequence. The first acidic segment, in which 11 of the 13 residues are acidic, begins at residue 120 and contains a major phosphorylation site. In the second segment (residues 159-187) there are four copies of the sequence Asp-Asp-Glu, and all but two of the 29 residues have acidic side chains. When the sequence of the rat protein was compared with available sequences from other species a high degree of conservation was found; the 77-residue carboxyl-terminal sequence is identical with that of human protein B23 (Chan, P. K., Chan, W.-Y., Yung, B. Y. M., Cook, R. G., Aldrich, M. B., Ku, D., Goldknopf, I. L., and Busch, H. (1986) J. Biol. Chem. 261, 14335-24341), and about 63% of the residues are identical when the rat B23 sequence is compared with protein N038 from Xenopus laevis (Schmidt-Zachmann, M. S., Hügle-Dörr, B., and Franke, W. (1987) EMBO J. 6, 1881-1890). Except for the presence of highly acidic regions no significant similarities were found with protein C23 (nucleolin), the other major nucleolar protein.

Amino Acid Sequence↗

PubMed1988

Effects of anti-C23 (nucleolin) antibody on transcription of ribosomal DNA in Chironomus salivary gland cells.

Protein C23 (also called nucleolin or 100-kDa nucleolar protein) is a major nucleolar phosphoprotein involved in ribosome biogenesis. To determine the effects of protein C23 on preribosomal RNA (pre-rRNA) synthesis anti-C23 antiserum was microinjected into nuclei of Chironomus tentans salivary glands. Transcription was measured by incubation of the glands with 32P-labeled RNA precorsors followed by microdissection of nucleoli, RNA extraction, and electrophoretic analyses. Injection of the anti-C23 antibody caused a 2- to 3.5-fold stimulation of 32P incorporation into 38S pre-rRNA. No stimulation was observed in salivary glands injected with preimmune serum or antiserum preabsorbed with protein C23. The stimulatory effect was selective for pre-rRNA as indicated by the lack of stimulation of 32P incorporation into extranucleolar RNA. Injection of the antiserum produced little or no effect on pre-RNA processing as measured by the relative amounts of 32P-labeled intermediate cleavage products of pre-rRNA in stimulated versus control glands. When protein extracts of Chironomus tentans salivary gland nuclei were probed on Western blots with anti-C23 antibody the predominant cross-reacting species was a 110-kDa polypeptide which had an electrophoretic mobility similar to that of protein C23. These results suggest that protein C23 not only is involved in ribosome assembly but also plays a role in regulating the transcription of the preribosomal RNA.

Animals↗