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Biomedical subjects

C W Chen

Publications and source records attributed to C W Chen.

At least 19 recordsLinked to original sources
PubMed1992

argJ mutations are highly inducible by ethidium bromide in proB strains of Streptomyces lividans: implication of pathway interactions.

Spontaneous Arg- mutants arose at high frequencies in Streptomyces lividans. Exposure to ethidium bromide increased the frequency of arg instability. In Pro+ strains the induced arg mutants were mainly argG, but in the proB mutants, a new mutation, argJ, prevailed which lacked ornithine acetyltransferase activity and required ornithine for growth. Introduction of the cloned proB gene of Streptomyces coelicolor A3(2) into the proB argJ mutants not only complemented the proB mutation but also suppressed the argJ mutation. The proB mutation was also suppressed by adding ornithine to the medium. These results indicated crossfeeding(s) between the arginine and proline pathways in S. lividans, which presumably circumvented the detection of argJ mutations in Pro+ strains.

Acetyltransferases↗
PubMed1992

Cancer potential in liver, lung, bladder and kidney due to ingested inorganic arsenic in drinking water.

In order to compare risk of various internal organ cancers induced by ingested inorganic arsenic and to assess the differences in risk between males and females, cancer potency indices were calculated using mortality rates among residents in an endemic area of chronic arsenicism on the southwest coast of Taiwan, and the Armitage-Doll multistage model. Based on a total of 898,806 person-years as well as 202 liver cancer, 304 lung cancer, 202 bladder cancer and 64 kidney cancer deaths, a significant dose-response relationship was observed between arsenic level in drinking water and mortality of the cancers. The potency index of developing cancer of the liver, lung, bladder and kidney due to an intake of 10 micrograms kg day of arsenic was estimated as 4.3 x 10(-3), 1.2 x 10(-2), 1.2 x 10(-2), and 4.2 x 10(-3), respectively, for males; as well as 3.6 x 10(-3), 1.3 x 10(-2), 1.7 x 10(-2), and 4.8 x 10(-3), respectively, for females in the study area. The multiplicity of inorganic arsenic-induced carcinogenicity without showing any organotropism deserves further investigation.

Adult↗
PubMed1992

Tc-99m HMPAO labeled WBC scan for the detection of myocarditis in different phases of Kawasaki disease.

Myocardial imaging with Tc-99m HMPAO WBC was used to detect myocarditis of Kawasaki disease in 103 infants and children (66 boys and 37 girls, mean age 3 years and 4 months). The clinical course of Kawasaki disease may be divided into three phases, from the onset of illness onset until all clinical symptoms and signs have disappeared. Twenty-four hour myocardial imaging was performed in anterior, LAO, and left lateral views. The grading system was as follows: score 0 less than bone uptake; 1 = bone uptake; 2 greater than bone uptake; and 3 greater than or equal to liver uptake. If the score was greater than or equal to 2, significant myocarditis was considered. The appearing ratio of myocarditis was 57% (13/23) in the first phase; 65% (15/23) in the second phase; 54% (31/57) in the third phase. No significant difference was demonstrated among the three groups of patients (P greater than 0.1, by Chi-square test). In conclusion, an occult myocarditis may continue in all three phases of Kawasaki disease, even if the clinical symptoms and signs had improved by the evidence of Tc-99m HMPAO labeled WBC scan to avoid advanced cardiac complication.

Child↗
PubMed1992

Tc-99m HMPAO WBC imaging to detect carditis and to evaluate the results of high-dose gamma globulin treatment in Kawasaki disease.

Eighteen patients with Kawasaki disease and suspected carditis (11 boys, 7 girls, mean age 18 months) in acute stages underwent Tc-99m HMPAO WBC imaging of the heart. Signs and symptoms subsided after conventional aspirin therapy and the intravenous injection of high-dose (400 mg/kg per day for 5 days) gamma-globulin treatments. Tc-99m HMPAO WBC imaging of the heart was arranged a second time to evaluate the effects of the treatments for carditis. The results showed that a significant difference existed in the severity of carditis before and after the treatments (P less than 0.001, by signed rank test), 39% (7/18) with significant improvement in severity of carditis, 50% (9/18) without definite change. However, 11% (2/18) became more severely ill after the treatments. Tc-99m HMPAO WBC imaging may be useful in detecting carditis in Kawasaki disease and in evaluating the effects of aspirin plus the newly recommended gamma-globulin for the treatment of carditis in Kawasaki disease.

Child, Preschool↗
PubMed1992

99Tcm-HMPAO-labelled white blood cell scanning for the detection of carditis in the differentiation of rheumatic fever and inactive rheumatic heart disease in children.

Myocardial imaging with 99Tcm-hexamethylpropylene amineoxime (HMPAO)-labelled white blood cells (Tc-WBC) was used to detect carditis and differentiate rheumatic fever (RF) and inactive rheumatic heart disease (IRHD). Ten cases of RF and 15 cases of IRHD were studied, and the results revealed 60% (6/10) of the cases of RF with carditis, but none of the cases (0/15) of IRHD with carditis. There was significant difference (P less than 0.05, by Fisher's test) between RF and IRHD. In our preliminary conclusion, Tc-WBC heart scanning may be a noninvasive method for evaluating the existence of carditis in cases of RHD and in the differentiation of RF and IRHD.

Adolescent↗
PubMed1992

Discovery and characterization of a new transposable element, Tn4811, in Streptomyces lividans 66.

Transposition of a new 5.4-kb transposon, Tn4811, of Streptomyces lividans to the melC operon of Streptomyces antibioticus on plasmid pIJ702 was discovered. The nucleotide sequence of this copy of Tn4811, which contained an imperfect (9 of 11 bp) terminal inverted repeat, five putative Streptomyces coding sequences for an oxidoreductase and its transcription regulator, and three transposition-related proteins, was determined. SLP- strains of S. lividans contained one copy (A) of Tn4811, while SLP2+ strains contained an additional copy (B) on the SLP2 plasmid. The nucleotide sequences at three insertion junctions of Tn4811 were determined. Copy B lacked 41 bp from the left end. At the other five junctions the duplication of a putative 3-bp target sequence (TGA) was observed. A sequence of less than 3 kb homologous to Tn4811 was present in S. antibioticus. DNA homologous to Tn4811 was not detected in 14 other Streptomyces species.

Amino Acid Sequence↗
PubMed1992

[Double aortic arch-three cases report and operative treatment].

This report is on three double aortic arch cases. They were diagnosed in our department between 1982 and 1992. The first case was complicated by dilated cardiomyopathy whose diagnosis was delayed due to a lack of clinical experience. Corrective surgery relieved the airway obstruction and his breathing improved postoperatively. The patient finally died of heart failure due to concurrent progressive dilated cardiomyopathy one and half years later. The second and third cases were diagnosed on the day of admission by a barium esophagogram and echocardiogram. MRI (Magnetic resonance image) of the cardiovascular system on these two patients revealed no other associated abnormalities. No angiography was done on the third case. They underwent surgery with excellent results. In any infant younger than 3 months with dyspnea and dysphagia, double aortic arch should be suspected. The esophagogram can show extrinsic compression. An echocardiogram can reveal two aortic arches. Both procedures can be performed easily and safely at the bedside. We recommend that these to be considered as routine examinations in such patients.

Aorta, Thoracic↗
PubMed1992

Adult bacteremic pneumonia: bacteriology and prognostic factors.

Bacteremic pneumonia is a highly specified subgroup of pneumonia that is potentially life-threatening. In order to find out the prognostic factors in this subgroup of pneumonia, we conducted a 40-month retrospective analysis of 70 cases in our hospital. The male to female ratio was 54:16. Forty-one cases were community-acquired bacteremic pneumonia (CABP), and 29 cases were nosocomial bacteremic pneumonia (NBP). Both CABP and NBP were predominated by gram-negative bacteria. Klebsiella pneumoniae was the most common microorganism isolated in both CABP and NBP. The overall mortality was 62.9% (44/70). There was no significant difference in the mortality between CABP (61.0%) and NBP (65.5%). After univariate analysis of all possible prognostic factors, 10 variables were found to have significantly poor prognostic values. They were: 1) the presence of septic shock; 2) the use of ventilatory support; 3) the presence of radiologic spread; 4) treatment in an intensive care unit; 5) male gender; 6) the development of adult respiratory distress syndrome; 7) Klebsiella bacteremic pneumonia in patients with an alcohol habit; 8) patients with ultimately fatal underlying diseases; 9) an initial AaDO2 > 200 mmHg; and 10) an initial arterial pH < 7.25.

Adult↗
PubMed1991

Decreased norepinephrine release in anterior hypothalamus of NaCl-sensitive spontaneously hypertensive rats during high NaCl intake.

We previously demonstrated that dietary NaCl supplementation reduces endogenous norepinephrine stores and turnover in the anterior hypothalamic area (AHA) of male NaCl sensitive spontaneously hypertensive rats (SHR-S) but not in NaCl resistant control rats and have implicated this mechanism in the pathogenesis of NaCl sensitive hypertension. In the current study, we tested directly the hypothesis that dietary NaCl supplementation decreases the release of norepinephrine from nerve terminals in the AHA of SHR-S using the push-pull perfusion technique. Conscious, freely moving SHR-S and control Wistar-Kyoto (WKY) rats were studied after 2-3 weeks of 8% or 1% NaCl feeding. In the 1% NaCl fed SHR-S, 3-methoxy-4-hydroxyphenylglycol (MOPEG, the major metabolite of norepinephrine in brain) levels averaged 272 +/- 32 pg/10 min; norepinephrine levels, 17 +/- 2 pg/10 min; in the 8% NaCl fed SHR-S, MOPEG levels averaged 72 +/- 7 pg/10 min; norepinephrine levels were 6 +/- 1 pg/10 min. There was a positive linear correlation (r = 0.777; P less than 0.01) between MOPEG and norepinephrine levels in AHA perfusates, indicating that perfusate MOPEG levels provide a useful index of norepinephrine release from AHA nerve terminals. In contrast, MOPEG levels in AHA perfusates were not affected by dietary NaCl intake in control WKY, and in control posterior hypothalamic perfusates, were not affected by dietary NaCl intake in SHR-S.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dihydroxyphenylacetic Acid↗
PubMed1991

The nucleotide sequence of 3C proteinase region of the coxsackievirus A24 variant: comparison of the isolates in Taiwan in 1985-1988.

Acute hemorrhagic conjunctivitis caused by coxsackievirus A24 variant (CA24v) first appeared in Taiwan in October 1985, followed by two other sequential epidemics in 1986 and 1988. In order to know the evolutionary relationship of the CA24v strains isolated in Taiwan, we first determined the nucleotide sequence of the 3C proteinase (3Cpro) region of the prototype strain (EH24/70), isolated in Singapore in 1970, by molecular cloning. The nucleotide sequence of the 3Cpro region thus sequenced showed striking homology with polioviruses and coxsackievirus A21. Viral RNA of eight isolates obtained from the three epidemics was reverse transcribed, amplified by the polymerase chain reaction, and cloned into M13 phage for the production of ssDNA for nucleotide sequencing by the dideoxy chain termination method. When the number of nucleotide difference was taken as a genetic distance between isolates, all isolates showed a very similar distance from the EH24/70, the earliest isolate of CA24v, indicating that they evolved at a constant evolutionary rate. Phylogenetic analysis by the unweighted pairwise grouping method of arithmetic average (UPGMA) indicated that the six isolates collected in 1985 and 1986 were closely related, while two 1988 isolates were more distant from them. The branching time between these two groups was estimated to be May 1984, 18 months before the first recognition of the CA24v epidemic in Taiwan. This is the first report of the nucleotide sequence of CA24v genome RNA and of an evolutionary analysis of the virus using the nucleotide sequence.

3C Viral Proteases↗
PubMed1991

A stochastic two-stage carcinogenesis model: a new approach to computing the probability of observing tumor in animal bioassays.

A new definition of probability of observing tumor in animal bioassay is developed. It is derived from a two-stage stochastic model for carcinogenesis with time-dependent birth and death rates for cell proliferation. The model takes into account the method of collecting data on preneoplastic and neoplastic lesions. The new definition is appropriate for analyzing the presence or absence of tumors in animal bioassays.

Animals↗
PubMed1991

Comparison of 99Tcm-HMPAO-labelled white blood cells and 67Ga citrate scans to detect myocarditis in the acute phase of Kawasaki disease.

Myocardial imaging with 99Tcm-HMPAO-labelled white blood cells (WBC) and 67Ga citrate was used to detect myocarditis in the acute phase of Kawasaki disease among 22 infants and children; 18 cases of myocarditis were detected by 99Tcm-HMPAO-labelled WBC heart scans, but only one case was detected by 67Ga citrate heart scans. In conclusion, 99Tcm-HMPAO-labelled WBC scanning provides a more sensitive method than 67Ga citrate scanning in the detection of myocarditis in Kawasaki disease.

Child, Preschool↗
PubMed1991

A cloned ompR-like gene of Streptomyces lividans 66 suppresses defective melC1, a putative copper-transfer gene.

Expression of tyrosinase in Streptomyces requires functional MelC1 protein, which is postulated to transfer copper to apotyrosinase. We have previously isolated a mutant of Streptomyces lividans, HT32, that phenotypically suppressed mutations in cloned melC1 (H.-C. Tseng and C. W. Chen, in preparation). Plasmid pLUS132, containing an ATG to ATA transition at the initiation codon of melC1, was used for cloning the suppressor gene from HT32. A 1687 bp suppressor DNA was isolated that contained two characteristic Streptomyces coding sequences: a 217-amino-acid open reading frame (cutR) and a truncated open reading frame (cutS) downstream. Subcloning analysis attributed the phenotypic suppression activity to the putative cutR gene from HT32. The putative CutR exhibited similarity to the response regulator OmpR of the osmoregulatory signal-transduction system in Escherichia coli. The truncated CutS resembled, to a lesser degree, the N-terminus of EnvZ, the histidine protein kinase counterpart of OmpR. DNA hybridizing to the cloned cutR-cutS sequence was detected in 16 other Streptomyces species. We postulate that the putative cutR-cutS operon regulates copper metabolism in Streptomyces.

Amino Acid Sequence↗
PubMed1991

Response of medullary reticular neurons of cat to off-vertical axis rotations.

To investigate whether neurons in the medullary reticular formation of decerebrate cats can encode spatial orientation during 360 degrees off-vertical axis rotations (OVAR), responses of these units were studied during constant velocity OVAR in clockwise (CW) and counter-clockwise (CCW) directions. Tilt-sensitive units, some of which were activated by antidromic stimulation of the thoracic cord, were found to respond to 360 degrees OVAR with position-and direction-dependent modulation in discharge rates. For the individual responsive unit there was a difference in the spatial location of the CW and CCW discharge maxima, while a comparable response gain was obtained for rotations in either direction. The orientation of the best response of each unit was not significantly modified by changes in the amplitude of head tilt and/or velocity of rotation. Such characterized directional axes of the medullary reticular units were found to have a fairly equal distribution over the 360 degrees. The role that neurons in the medullary reticular formation plays in encoding otolith inputs with respect to head movements is discussed.

Animals↗
PubMed1991

Gas-forming vertebral osteomyelitis in diabetic patients.

We report 2 cases of gas-forming vertebral osteomyelitis in diabetic patients. Both were caused by gram-negative bacilli, Escherichia coli and Klebsiella pneumoniae respectively. Both ran a fulminant course to death despite appropriate parenteral antibiotics. We suggest that early surgical intervention may be needed in cases with gas-forming vertebral osteomyelitis.

Aged↗
PubMed1991

[Nemaline myopathy--a case report].

An 8-year-old Chinese girl who was noted to have feeding difficulty and poor weight gain since her infancy. Her motor development was delayed with sitting at 1-year-old and walking independently at 2-year-old. She visited our OPD when she was 8. Physically, she was thin and slender. Her height and weight were below the 10th and 3rd percentile. Her face was elongated with high arched palate. Neurologically, she had waddling gate with marked proximal muscle weakness. Her cranial nerves and sensation remained intact. Laboratory tests including blood routine, liver function, renal function, electrolytes, NCV and cardiac echo all were within normal limits. The EMG showed myopathic pattern. A fresh-frozen muscle biopsy stained with the modified Gomori trichrome, processed by histochemistry and electronmicroscopic examination showed typical nemaline rods with predominance of type 1 muscle fibers. She was then diagnosed to have nemaline myopathy.

Child↗
PubMed1991

[Double aortic arch associated with severe left ventricular dysfunction--a case report].

A case of a 3-month-old male infant with severe LV dysfunction and a complete double aortic arch (both arches patient) is reported. The right dominant aortic arch runs retroesophageally to the right and joins with the left smaller arch to form the descending thoracic aorta on the right side while the ligamentum arteriosum was located in its normal position (the left side). Through a left thoracotomy, the smaller left arch and the ligamentum were divided to relieve the obstruction of the trachea from compression of the vascular ring. Postoperative convalescence was good. Further follow up of this patient after 9 months showed that there was neither any respiratory failure nor any heart failure sign present, though severe LV dysfunction persisted.

Aorta, Thoracic↗