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Biomedical subjects

S M Chen

Publications and source records attributed to S M Chen.

At least 73 records · Page 4Linked to original sources
PubMed1995

A prospective, randomized trial of sclerotherapy versus ligation in the management of bleeding esophageal varices.

We conducted a prospective, randomized trial comparing sclerotherapy and ligation in 120 patients with acute bleeding of esophageal varices. All the patients were cirrhotic, 59 received sclerotherapy, and 61 received ligation. Treatment was repeated regularly until the varices were obliterated. The mean follow-up period was 295 +/- 120 days and 310 +/- 105 days for the sclerotherapy and ligation groups, respectively. The control of active bleeding was 12/15 (80%) in the sclerotherapy group and 18/19 (94%) in the ligation group (P = .23). The numbers of treatment sessions required to achieve variceal obliteration were 6.5 +/- 1.2 in the sclerotherapy group and 3.8 +/- 0.4 in the ligation group (P < .001). Recurrent bleeding from the gastrointestinal tract was 51% in the sclerotherapy group compared with 33% in the ligation group (P < .05). Recurrent bleeding from esophageal varices was 36% in the sclerotherapy group and 11% in the ligation group (P < .01). However, bleeding from ectopic varices and congestive gastropathy was less common in the sclerotherapy group (7%) than in the ligation group (18%) (P = .05). Significant complications were encountered in 19% of the sclerotherapy group and in 3.3% of the ligation group (P < .01). Comparison of Kaplan-Meier estimates of time to death of both groups showed a significantly lower mortality in the ligation group (P = .011). Both sclerotherapy and ligation can effectively arrest active bleeding from esophageal varices. However, ligation is more effective than sclerotherapy in decreasing the risk of rebleeding from esophageal varices with fewer complications. Ligation can also achieve obliteration of esophageal varices more rapidly than sclerotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

A study of different postures on isometric lifting strength in normal college students.

The purpose of this study was to describe norms of isometric lifting strength for normal college students and to investigate the effects of gender, body weight, height, and upper and lower limb length on lifting strength. Three types of lifting (i.e., arm, back, and leg lifting) were measured in a sample of 104 college students aged between 18 and 26 years. A Force Evaluation and Testing System (FET 5000) was used for strength measurements with three standard lifting positions. The average of three trials for each lifting strength test was used as the subject's test score. The results showed that the highest mean lifting strength was recorded for leg lifting in both males and females. Both groups also had the lowest score in arm lifting. Of the total sample, there was a difference of strength of nearly three- times between leg and arm lifting. Males were stronger than females in all lifting patterns. In addition, lifting strengths were significantly affected by such variables as sex, weight and height. Body weight was an effective predictor of arm lifting strength, and height an effective predictor of leg lifting strength. Finally, we found that strength in one position had positive relations with strength in other positions. These findings and the establishment of data base can in future provide therapists with an objective evaluation regarding lifting strength of individuals for clinical use.

Adolescent↗
PubMed1994

Function of streptokinase fragments in plasminogen activation.

Several peptide fragments of streptokinase (SK) were prepared by incubating SK with immobilized human plasmin (hPlm) and purified by h.p.l.c. with a reverse-phase phenyl column. The N-terminal sequences, amino acid compositions and molecular masses of these peptide fragments were determined. The SK peptide fragment of 36 kDa consisting of Ser60-Lys387 (SK-p), was the only peptide fragment that could be tightly bound to immobilized hPlm. Another three large SK peptide fragments, SK-m, SK-n and SK-o, with molecular masses of 7 kDa, 18 kDa and 30 kDa, and consisting of Ile1-Lys59, Glu148-Lys333, Ser60-Lys333 respectively, were also obtained from the supernatant of the reaction mixture. The purified SK-p had high affinity with hPlm and could activate human plasminogen (hPlg) with a kPlg one-sixth that of the native SK. SK-o had low affinity with hPlm and could also activate hPlg, although the catalytic constant was less than 1% of the native SK. SK-n, as well as SK-m, which is the N-terminal 59 amino acid peptide of the native SK, had no activator activity. However, SK-m could enhance the activator activity of both SK-o and SK-p and increase their second-order rate constants by two- and six-fold respectively. It was concluded from these studies that (1) SK-o, the Ser60-Lys333 peptide of SK, was essential for minimal SK activator activity, (2) the C-terminal peptide of SK-p, Ala334-Lys387, was essential for high affinity with hPlm, and (3) the N-terminal 59-amino-acid peptide was important in maintaining the proper conformation of SK to have its full activator activity.

Amino Acid Sequence↗
PubMed1994

Two-dimensional 1H NMR studies of immobile Holliday junctions: nonlabile proton assignments and identification of crossover isomers.

The nonlabile protons of two 32-base-pair models of the Holliday junction intermediate in genetic recombination have been studied by two-dimensional 1H nuclear magnetic resonance (NMR) spectroscopy. The sequence of these models is designed to fully inhibit branch migration of the junction and to probe the possible sequence dependence of these four-arm DNA structures. Overlap of resonances in homonuclear two-dimensional nuclear Overhauser enhancement (NOE) spectra necessitates the use of a multipathway approach for obtaining sequence-specific assignments, wherein all possible NOE connectivities are analyzed in parallel. Using this strategy, 1H resonance assignments were obtained for virtually all nonlabile base protons and C1', C2', and C3' sugar protons. Several unambiguous cross-arm NOE connectivities were identified, directly establishing the stacking arrangements of each contiguous (two-arm) helical domain. The distribution of the two possible stacking isomers is distinctly different for the two junctions studied, thereby indicating that the relative stability of the isomers is dependent on the sequence at the junction.

Base Sequence↗
PubMed1994

Human granulocytic ehrlichiosis in the upper Midwest United States. A new species emerging?

OBJECTIVE: To characterize the clinical presentation and course, laboratory findings, and treatment outcome of 12 patients with human granulocytic ehrlichiosis. SETTING: The 12 patients were male, ranged in age from 29 to 91 years, and contracted their illness in Wisconsin or Minnesota. METHODS: Cases were recognized by the presence of intracytoplasmic inclusions (morulae) in peripheral neutrophils of patients presenting with temperature of 38.5 degrees C or higher, chills, severe headache, and myalgias. All patients had a complete blood cell count and blood chemistry profile. Blood smears were examined by light microscopy. All available paired serum samples were analyzed for presence of indirect fluorescent antibodies against Ehrlichia chaffeensis, Ehrlichia phagocytophila, and Ehrlichia equi. Blood samples from 12 patients were subjected to polymerase chain reaction analysis using primers specific for the E phagocytophila/E equi group, primers that include the agent identified in our patients, as well as E chaffeensis. RESULTS: Varying combinations of leukopenia, anemia, and thrombocytopenia were found in all but one patient. All 12 patients demonstrated morulae in the cytoplasm of neutrophils, but not in mononuclear white blood cells. Serum assays failed to detect antibodies against E chaffeensis, but eight of 10 patients and seven of 10 patients tested had antibody titers of 1:80 or more for E phagocytophila and E equi, respectively. Polymerase chain reaction products obtained with primers for E phagocytophila, E equi, and the granulocytotropic Ehrlichia revealed that seven patients were infected with the same agent. The results of serological assays or polymerase chain reaction strongly suggest that all 12 patients were infected by E phagocytophila, E equi, or a closely related Ehrlichia species. Two of the 12 patients died. The other 10 patients improved rapidly with oral doxycycline treatment. CONCLUSIONS: We believe that all 12 patients have been infected with a granulocytic Ehrlichia species, reflecting a recently described new disease entity. The infective organism appears to be closely related to E phagocytophila and E equi. The geographic domain of human granulocytic ehrlichiosis is currently unknown. This novel granulocytic Ehrlichia species is capable of causing fatal infections in humans. Early detection and treatment with tetracycline drugs appear to offer the best chance for complete recovery.

Adult↗
PubMed1994

Early detection of unilateral occlusion of duplicated müllerian ducts: the use of serial pelvic sonography for girls with renal agenesis.

For early detection of unilateral occlusion of duplicated müllerian ducts, serial pelvic sonography was performed in 215 girls with known renal agenesis, especially following menarche, during the last 6 years. To date, 16 girls with unilateral occlusion of duplicated müllerian ducts were detected. We stress the value of this modality, which can lead to a prompt diagnosis, and allow for early and appropriate surgical intervention.

Abnormalities, Multiple↗
PubMed1994

Effect of intradialytic parenteral nutrition on mortality rates in end-stage renal disease care.

Several studies have now demonstrated that low serum albumin and/or low protein catabolic rates correlate with increased risk of death in the chronic hemodialysis patient. A study involving 81 patients receiving thrice-weekly hemodialysis treatments and who had either a low serum albumin and/or protein catabolic rate was conducted to compare the effect of intradialytic parenteral nutrition (IDPN) on mortality rates. Fifty patients received IDPN and 31 patients did not. Thirty-eight of the patients were black (47%), 34 were white (42%), and 9 were Hispanic (11%). The study included 33 diabetic patients (41%), 20 of whom received IDPN. Nondiabetic patients received an average of 725 kcal/hemodialysis treatment and diabetic patients received an average of 670 kcal/hemodialysis treatment. The average length of treatment was 9 months. The results of the study revealed a better survival rate (64% v 52%) for patients treated with IDPN. Using Cox analysis, the IDPN-treated group had a significantly better survival rate (P < 0.01). Serum albumin increased by 12% in the survivors. There was no difference in survival when considered separately for diabetic and nondiabetic patients who received IDPN (mortality rate for diabetics: 50% for treated patients and 54% for untreated patients; mortality rate for nondiabetics: 26% for treated patients and 44% for untreated patients). However, the nondiabetic treated patients had the lowest mortality rates. In conclusion, correction of hypoalbuminemia by IDPN significantly reduced mortality rates overall.

Body Weight↗
PubMed1994

Identification of a granulocytotropic Ehrlichia species as the etiologic agent of human disease.

Six patients from northern Minnesota and Wisconsin with a febrile illness accompanied by granulocytic cytoplasmic morulae suggestive of ehrlichial infection were identified. Two patients died, and splenic granulocytes of one patient contained cytoplasmic vacuoles with organisms ultrastructurally characteristic of ehrlichiae. From one patient, a 1.5-kb DNA product was amplified by PCR with universal eubacterial primers of 16S rDNA. Analysis of the nucleotide sequence of the amplified product revealed 99.9 and 99.8% similarities with E. phagocytophila and E. equi, respectively, neither of which has previously been known to infect humans. From the variable regions of the determined sequence, a forward primer specific for three organisms (human granulocytic ehrlichia, E. phagocytophila, and E. equi) and a reverse primer for these ehrlichiae and E. platys were designed. By nested PCR with amplification by the universal primers and then reamplification with the specific primers described above, the expected 919-bp product was generated from the blood of the index patient and three additional patients. Blood from these four patients and two more patients with granulocytic morulae contained DNA which was amplified by nested PCR involving a combination of a universal primer and the human granulocytic ehrlichia-E. phagocytophila-E. equi-E. platys group-specific primer. This apparently vector-borne human granulocytic ehrlichia has only 92.5% 16S rDNA homology with E. chaffeensis. Nested PCR with group-specific primers did not amplify E. chaffeensis DNA, and E. chaffeensis-specific primers did not amplify DNAs of the human granulocytic ehrlichia. Thus, six patients were shown to be infected by an Ehrlichia species never previously reported to infect humans.

Aged↗
PubMed1994

Serum and ascitic concentration of C3, C4 and protein in cirrhotic patients with spontaneous bacterial peritonitis.

BACKGROUND: Lower concentration of ascitic or serum complement (C3, C4) or protein has been reported to participate in the development of spontaneous bacterial peritonitis (SBP). In Taiwan, the etiology of hepatic cirrhosis is mainly post-hepatic and SBP is the common complication. This study aims to determine the role of protein and complements in the pathogenesis of SBP. METHODS: 119 cirrhotic patients were divided into two groups, 30 SBP and 89 non-SBP. The concentrations of ascitic and serum complement and protein were measured for comparison. RESULTS: The ascitic and serum C3, C4 and protein levels were significantly lower (P < 0.05) in patients with SBP than in non-SBP patients. No significant differences were noted in the ascites/serum ratio of C3, C4 and protein in patient with or without SBP. CONCLUSIONS: Low levels of ascitic and serum protein and complements, C3 and C4, may be prone to develop SBP in our patients mostly with post-hepatitic cirrhosis.

Aged↗
PubMed1994

Identification of the antigenic constituents of Ehrlichia chaffeensis.

Ehrlichia chaffeensis, the novel etiologic agent of human ehrlichiosis in the United States, was first isolated in 1990 and reported in 1991. To analyze the antigenic components of E. chaffeensis, we cultivated these obligate intracellular bacteria in DH82 cells, purified the ehrlichiae by renografin density gradient centrifugation, and examined the antigens by Western immunoblotting. Rabbit and human antisera to E. chaffeensis revealed more than 20 bands ranging from 20 to 200 kD. The distinct 22-kD protein was heat labile. The rest of the major immunoreactive components were heat stable. The immunoblots of E. chaffeensis were highly similar when probed with antisera to E. chaffeensis, E. canis, and E. ewingii, indicating the close antigenic relationships among the three species. The 22-kD protein cross-reacted only with anti-E. canis serum. The antibody against E. sennetsu reacted strongly with the 66-, 64-, 55-, and 44-kD antigens of E. chaffeensis. The E. risticii antisera reacted strongly with the 55- and 44-kD bands but only faintly with the 66-kD band. The major immunoreactive antigens of E. chaffeensis (66, 55, and 44 kD) showed cross-reactions with all the different antisera tested. The results indicated that E. chaffeensis is antigenically most closely related to E. canis, is less closely related to E. ewingii, and is only distantly related to E. sennetsu and E. risticii.

Animals↗
PubMed1993

Two-dimensional 1H NMR studies of 32-base-pair synthetic immobile Holliday junctions: complete assignments of the labile protons and identification of the base-pairing scheme.

The labile protons of two 32-base-pair, four-arm models of immobile Holliday junctions have been studied by two-dimensional 1H nuclear magnetic resonance (NMR) spectroscopy. Overlap of resonances in the imino-imino region of two-dimensional nuclear Overhauser enhancement (NOE) spectra necessitates the use of a multi-pathway approach for obtaining sequence-specific assignments wherein all possible NOE connectivities to the labile protons are utilized, including those from the 2H of adenine, 5CH3 of thymine, and 5H of cytosine. Resonance assignments are obtained for all slowly exchanging imino and cytosine amino protons. Base-pairing up to and including the junction point is found in all four arms of both Holliday junctions. Several cross-arm NOE connectivities are identified and can be used to infer the geometry of the helical stacking domains. The two Holliday junctions studied, which differ only by the exchange of two base pairs at the branch point, appear to have opposite arm stacking geometries. These assignments form an important part of the critical background for detailed NMR analysis of Holliday junction structure and dynamics.

Base Composition↗
PubMed1993

Synthesis of new amino acid and peptide derivatives of estradiol and their binding affinities for the estrogen receptor.

A series of amino acid and peptide derivatives of estradiol have been synthesized by coupling 17 beta-aminoestra-1,3,5(10)-trien-3-ol, 17-hydrazonoestra-1,3,5(10)-trien-3-ol with amino acids or peptides, using tetrahydrothiazole-2-thione, N-hydroxy-1,4-epoxycyclohex-5-ene-2,3-dicarbonylimide, benzotriazolyloxy-tris(dimethylamino)phosphonium hexafluorophosphate, and p-nitrophenol as reagents. N-protected peptidyl steroids were deprotected by traditional methods. The relative binding affinities of the deprotected derivatives to the estrogen receptor were determined by competitive radioligand binding assay.

Amino Acids↗
PubMed1993

Amelioration of antioxidant enzyme suppression and proteinuria in cyclosporin-treated puromycin nephrosis.

The effect of cyclosporin (CS) on intrinsic glomerular level of antioxidants in puromycin aminonucleoside (PAN) nephrosis was examined. A single intravenous dose of PAN (50 mg/kg body weight) given to Sprague-Dawley rats resulted in marked proteinuria. Ten days after PAN injection, the rats were treated with daily intraperitoneal injection of CS (10 mg/kg body weight/day) for 10 days. PAN-treated rats without CS treatment (PAN rats) had significantly lower activities of glomerular superoxide dismutase (SOD) and catalase (CAT) than normal rats (p < 0.05, respectively). When compared with PAN rats, CS-treated PAN rats had significantly less proteinuria and higher activities of glomerular SOD and CAT (p < 0.01 and p < 0.05, respectively). Significant elevation of glomerular malondialdehyde (MDA) level characteristic of PAN rats was absent in CS-treated PAN rats. Moreover, segmental sclerosis with capsular adhesion, hyalinosis, epithelial cell foot process fusion and microvillous transformation seen in PAN rats were apparently attenuated in CS-treated PAN rats. When compared with normal rats, rats receiving CS only had a significantly higher CAT activity and MDA level (p < 0.01 and p < 0.05, respectively). Assessment of glomerular reduced glutathione revealed no significant differences among PAN rats, CS-treated PAN rats, normal rats, and rats receiving only CS. These data indicate that glomerular antioxidant enzyme activities are modulated by CS.

Animals↗
PubMed1993

Diminution of antidiuretic and natriuretic response to arginine vasopressin in rats with five-sixths nephrectomy.

Adult male Sprague-Dawley rats subjected to five-sixths nephrectomy (5/6NX) and uninephrectomy (UNX) were tested for their responses to arginine vasopressin (AVP) at a rate of 100 microunit/kg/min during water diuresis. Blood and timed urine samples were collected for determination of inulin, creatinine, urea nitrogen, osmolality and sodium. The levels in plasma of urea nitrogen and creatinine were greater in 5/6NX than in intact or UNX group. Antidiuretic response to AVP diminished with intensity of renal ablation. The increased urine osmolality in response to AVP was also found to attenuate with varying degrees of nephrectomy. Marked natriuretic response to AVP was observed in intact and UNX rats but not in the 5/6NX group. In conclusion, diminished antidiuretic and natriuretic response to AVP in rats with 5/6NX might be the results of alteration of lower segments of remnant nephron secondary to uremia following extensive renal ablation.

Animals↗
PubMed1993

The effect of mannitol on antidiuretic and natriuretic actions of ADH in rats.

The effect of mannitol and glucose on antidiuretic and natriuretic actions of ADH was investigated in water-loaded, male Sprague-Dawley rats anesthetized with sodium pentobarbital (5 mg/100g). Water diuresis was induced and sustained by continuous intravenous perfusion of hypotonic solution containing 0.3% NaCl, 1.67% glucose, 1.2% ethanol and sufficient inulin at a constant rate 150 microliters/min. Arginine vasopressin at a single dose 0.1 ng/100g was tested twice in the phase of water diuresis and in the phase of water diuresis plus mannitol osmotic diuresis. Urine samples were collected at ten-minute intervals. Three doses of mannitol (5.18, 3.63, 1.81 mumol/min/100g) were given into the right renal artery in three groups of experimental rats, respectively. Administration of mannitol did not alter renal inulin clearance but increased urine flow and excretion of sodium from experimental kidney. Our findings show that mannitol reduced antidiuretic response to ADH in the experimental kidney. This reduction was related to intraarterial mannitol doses. Local administration of mannitol increased natriuretic action of ADH in the experimental kidney. However, a small dose (1.81 mumol/min/100g) of mannitol did not increase natriuretic action of ADH. Saline and glucose (5.23 mumol/min/100g) were also infused intra-arterially to replace mannitol. The effect of saline on antidiuretic and natriuretic responses to ADH was found to be insignificant. Glucose reduced antidiuretic response to ADH as mannitol did but failed to alter natriuretic response to ADH as saline did. We conclude that mannitol does positively affect antidiuretic and natriuretic actions of ADH. Glucose has similar effect but much less than mannitol.

Animals↗
PubMed1992

The use of capillary electrophoresis in a micropreparative mode: methods and applications.

The ability to collect sufficient quantities of analytes from capillary electrophoresis for subsequent analyses is demonstrated. Fractions collected have been analyzed using the following techniques: capillary electrophoresis, mass spectrometry, and protein sequencing. Fractions can be collected directly into small volumes of buffer or directly onto membrane surfaces. Relevant parameters such as capillary diameter, mass loading, and separation parameters are addressed.

Amino Acid Sequence↗
PubMed1992

Two-dimensional NMR studies of d(GGTTAATGCGGT).d(ACCGCATTAACC) complexed with the minor groove binding drug SN-6999.

The dodecadeoxynucleotide duplex d(GGTTAATGCGGT).d(ACCGCATTAACC) and its 1:1 complex with the minor groove binding drug SN-6999 have been prepared and studied by two-dimensional 1H nuclear magnetic resonance spectroscopy. Complete sequence-specific assignments have been obtained for the free duplex by standard methods. The line widths of the resonances in the complex are greater than those observed for the free duplex, which complicates the assignment process. Extensive use of two-quantum spectroscopy was required to determine the scalar correlations for identifying all of the base proton and most of the 1'H-2'H-2''H spin subsystems for the complex. This permitted unambiguous sequence-specific resonance assignments for the complex, which provides the necessary background for a detailed comparison of the structure of the duplex, with and without bound drug. A series of intermolecular NOEs between drug and DNA were identified, providing sufficient structural constraints to position the drug in the minor groove of the duplex. However, the combination of NOEs observed can only be rationalized by a model wherein the drug binds in the minor groove of the DNA in both orientations relative to the long helix axis and exchanges rapidly between the two orientations. The drug binds primarily in the segment of five consecutive dA-dT base pairs d(T3T4A5A6T7).d(A18T19T20A21A22), but surprisingly strong interactions are found to extend one residue in the 3' direction along each strand to G8 and C23. The observation of intermolecular contacts to residues neighboring the AT-rich region demonstrates that the stabilization of the bis(quaternary ammonium) heterocycle family of AT-specific, minor groove binding drugs is not based exclusively on interactions with dA-dT base pairs.

Antineoplastic Agents↗