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Biomedical subjects

S S Yang

Publications and source records attributed to S S Yang.

At least 109 records · Page 6Linked to original sources
PubMed1993

Valve-related events and valve-related mortality in 340 mitral valve repairs. A late phase follow-up study.

To assess the early and late valve-related events, 340 consecutive patients undergoing mitral valve repair from 1969 to 1988 were evaluated. Follow-up was complete, with a mean of 7.5% years and range from 2 to 22 years (cumulative 2456 patient-years). There were 221 (65%) female patients. Rheumatic valvular disease was present in 246 (68%) patients. The remaining patients had ischemic or congenital valve disease, floppy valve or infective endocarditis. At surgery, 47% of the patients had pure mitral incompetence, 43% had mixed mitral stenosis and incompetence and 10% had predominant mitral stenosis. Seventy-three percent of the patients were in functional class III or IV. Twelve percent had had prior heart surgery. Concomitant valve procedures including coronary revascularization were performed in 62.3%. There were 23 hospital deaths (6.8%) but only 3 of these (0.8%) were valve-related in patients who died at reoperation for valve repair failure. There were 4 other early repair failures who survived early reoperation. Of the 317 hospital survivors, there were 127 late deaths, and an actuarial survival of 44 +/- 3.7% (70% CL) at 14 years. Of these, 13 were valve-related or 0.5% patient-year. Late events included thromboembolism (TE) 1% patient-year, anticoagulant bleeding 0.4% patient-year, infective endocarditis (IE) 0.2% patient-year and late reoperation for mitral valve repair failure in 63 patients or 2.8% patient-year. At the late follow-up, 88% of the hospital survivors were in functional class I or II.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1993

Prospective study of abdominal ultrasonography before laparoscopic cholecystectomy.

To investigate the role of abdominal ultrasonography (US) in predicting possible difficulties during laparoscopic cholecystectomy, we performed preoperative US evaluation prospectively in 82 consecutive patients. We correlated our predictions of "easy" and "difficult" with difficulties experienced at operation in surgery. The binary outcomes were analyzed by taking both easy category of US and surgical operation as positive results and both difficult category as negative results. We obtained satisfactory sensitivity (93.8%), accuracy (81.4%), and positive predictive value (84.7%), but low specificity (35.3%) and negative predictive value (60%). The highly positive results were the result of careful US examination. The low specificity and negative predictive value were attributed to the fact that most surgically difficult cases were due to adhesions around the gallbladder, difficult indeed to detect at US. We conclude that thorough abdominal US examination before laparoscopic cholecystectomy is useful in preoperative evaluation of patients undergoing laparoscopic cholecystectomy, even if it not infrequently fails to predict the surgically difficult cases mainly due to adhesions around the gallbladder.

Abdomen↗
PubMed1993

Disappearance of N20 and P25 components of somatosensory evoked potential: an ominous sign in severe acute hepatitis.

The scalp-recorded somatosensory evoked potentials (SSEPs) of 14 patients who died of hepatic encephalopathy (HE) caused by severe acute hepatitis and 22 normal volunteers were studied. The present data showed that progressive deterioration of HE resulted in sequential prolongation and eventual disappearance of SSEP components beginning from the late P90 component towards the early P25 and N20 components. Four patients with systemic hypotension, supposedly due to brain edema and increased intracranial pressure, showed disappearance of the N20 and P25 components and died within 24 hours. The N20 and P25 components were preserved in the other 10 patients without systemic hypotension. The disappearance of the N20 and P25 components as well as later components suggests an almost total loss of cortical function. The present study suggests that the disappearance of the N20 and P25 components during the course of HE is an ominous sign in severe acute hepatitis.

Acute Disease↗
PubMed1992

The crystal structure of the Bacillus lentus alkaline protease, subtilisin BL, at 1.4 A resolution.

The crystal structure of subtilisin BL, an alkaline protease from Bacillus lentus with activity at pH 11, has been determined to 1.4 A resolution. The structure was solved by molecular replacement starting with the 2.1 A structure of subtilisin BPN' followed by molecular dynamics refinement using X-PLOR. A final crystallographic R-factor of 19% overall was obtained. The enzyme possesses stability at high pH, which is a result of the high pI of the protein. Almost all of the acidic side-chains are involved in some type of electrostatic interaction (ion pairs, calcium binding, etc.). Furthermore, three of seven tyrosine residues have potential partners for forming salt bridges. All of the potential partners are arginine with a pK around 12. Lysine would not function well in a salt bridge with tyrosine as it deprotonates at around the same pH as tyrosine ionizes. Stability at high pH is acquired in part from the pI of the protein, but also from the formation of salt bridges (which would affect the pI). The overall structure of the enzyme is very similar to other subtilisins and shows that the subtilisin fold is more highly conserved than would be expected from the differences in amino acid sequence. The amino acid side-chains in the hydrophobic core are not conserved, though the inter-residue interactions are. Finally, one third of the serine side-chains in the protein have multiple conformations. This presents an opportunity to correlate computer simulations with observed occupancies in the crystal structure.

Amino Acid Sequence↗
PubMed1992

Effect of moisture content on the microbial activity in JP-5 fuel oil.

The water solubility of JP-5 fuel oil was found to be proportional to the reciprocal of absolute temperature from 0 degree C to 60 degrees C. Water in the fuel oil would become condensed once the temperature was shifted from a high temperature to low temperature. During the storage, condensed water was precipitated in the bottom of the tank. Both the static and the dynamic dehumidification processes with molecular sieve could reduce the moisture content of fuel oil to less than 5 ppm. However, pre-dried fuel oil had a mildly hydroscopic phenomenon at relatively high humidity condition. The spores of contaminated microbes could survive in the fuel oil with 5 to 80 ppm of moisture content. High moisture content of fuel oil was not favorable to the spore survival. Penicillium sp. could survive in the fuel oil longer than Cladosporium resinae.

Cladosporium↗
PubMed1992

Baclofen intoxication: report of four cases and review of the literature.

Four cases of baclofen intoxication are reported, with a review of 33 cases from the literature. Analysis of these 37 cases suggests that there are two types of baclofen intoxication syndrome. Patients with acute intoxication present with four major clinical manifestations: encephalopathy (disturbance of consciousness and/or seizure), respiratory depression, muscular hypotonia, and generalized hyporeflexia. Patients with chronic intoxication present with hallucinosis, impaired memory, catatonia, or acute mania. The acute intoxication syndrome has a faster onset, shorter duration, more severe clinical manifestations, and higher incidence of seizures than the chronic intoxication syndrome. Baclofen intoxication, although it may cause grave encephalopathic manifestations and electroencephalographic findings, has a benign outcome if actively managed.

Adult↗
PubMed1991

Short rib syndrome Beemer-Langer type with polydactyly: a multiple congenital anomalies syndrome.

A male fetus with short rib (polydactyly) syndrome, Beemer-Langer type was aborted at 30 weeks' gestation because of abnormalities visualized on sonography. This is the first documented case with polydactyly in this recently defined entity. The clinical, radiological, and pathological findings, especially of the bones, are described. The differential diagnosis of this entity is discussed.

Adult↗
PubMed1991

Report of fourteen cases of nonimmune hydrops fetalis in association with hemorrhagic endovasculitis of the placenta.

Hemorrhagic endovasculitis of the placenta is a distinct vasodestructive process of unknown cause that has been associated with perinatal morbidity and mortality. A relationship between nonimmune hydrops fetalis and hemorrhagic endovasculitis has not been previously described. At a large teaching hospital, six cases of nonimmune hydrops fetalis were identified out of 72 cases of hemorrhagic endovasculitis over 6 years, for an incidence of 8%. Conversely, these same six cases represented 24% of the 25 cases of nonimmune hydrops fetalis from this time period. Eight additional cases of nonimmune hydrops fetalis were found among 2064 cases of hemorrhagic endovasculitis at the Michigan Placental Tissue Registry. In eight of the total 14 cases, after congenital malformations and cytomegalovirus infections were excluded, hemorrhagic endovasculitis was the only significant associated pathologic finding evident. The significance of the relationship between nonimmune hydrops fetalis and the vascular abnormalities of hemorrhagic endovasculitis remains to be determined.

Adult↗
PubMed1991

The effect of oral nitroglycerin on portal blood velocity as measured by ultrasonic Doppler. A double blind, placebo controlled study.

We studied the effect of oral nitroglycerin on portal blood velocity (PBV) in 20 cirrhotic patients by a double blind, placebo controlled method using noninvasive Doppler sonography. After we obtained baseline Doppler in the fasting state, 0.6 mg nitroglycerin or placebo was given orally and the mean of 3 s averaged mean PBVs was repeated at 5 min intervals for 60 min. Ten patients each received nitroglycerin or placebo. Portal vein flows were antegrade in all. Of the 10 patients receiving nitroglycerin, seven (P = 0.002) showed a greater than 10% fall in the mean PBVs for at least 15 min. Of these seven "responders," five patients had a 10% decrease in mean systemic blood pressure for at least 15 min. None of the "nonresponders" had systemic hypotension. Our study suggests that the PBV-reducing effect of nitroglycerin in cirrhotics may be explained in part by systemic hypotension.

Administration, Oral↗
PubMed1991

[Idiopathic retroperitoneal fibrosis causing obstructive uropathy: a case report].

Idiopathic retroperitoneal fibrosis leading to obstructive uropathy is a rare disease in our country, so a typical case deserves presentation. The patient is a 56-year-old female to have a clinical manifestation of obstructive uropathy. Retrograde pyelogram permitted 5 Fr. ureteral catheter to pass the stenotic segment. At the mean-time, there was hydronephrosis, medial deviation and gradual thinning and pointing of the middle segment of the ureter (classic triad). Computed tomography revealed that retroperitoneal soft tissue plaque enveloped aorta, inferior vena cava, and bilateral ureters. The patient received ureterolysis with ureter intraperitonealization and lateralization. The plaque was pathologically proved fibrosis. Renal function became normal postoperatively.

Female↗
PubMed1991

Chemical analysis and amino acid content of temperature-sensitive mutants of Saccharomyces cerevisiae.

Temperature-sensitive (ts) mutants of Saccharomyces cerevisiae Y-196 were isolated by using UV irradiation and/or EMS treatment. They grew normally at permissive temperature (30 degrees C), but could not grow at restrictive temperature (38 degrees C). From chemical composition analysis, it was found that ts mutants AMY-159, and AMY-88 had the highest protein and RNA contents, respectively. When the cells were cultivated at 30 degrees C to stationary phase and then shifted to 38 degrees C for 4 hr, protein contents of wild-type and most of the ts mutants increased but RNA contents decreased. Glutamic acid, aspartic acid and lysine were the three major amino acids of protein in all isolates tested at both temperatures. When the ts mutants AMY-136, AMY-161, and AMY-157 were cultured at 38 degrees C for 4 hr, methionine contents increased Amino acid scores of ts mutants AMY-15 and AMY-88 increased when they were shifted to 38 degrees C for 2 to 4 doubling times. The amounts of amino acids produced in some ts mutants were higher than that of wild-type.

Amino Acids↗
PubMed1991

Oxytetracycline production in solid state and submerged fermentation by protoplast fusants of Streptomyces rimosus.

Streptomyces rimosus TM-55 was treated with 3% EMS, and 29 auxotrophic mutants (AM-1 - AM-29) were isolated from 5457 colonies at a survival rate between 6.6-66.7%. Three sets of the auxotrophic mutants, AM-3 and AM-27, AM-7 and AM-28, and AM-3 and AM-21, were chosen for protoplast fusion with 50% PEG 1000 for 30 minutes at 25 degrees C, and 25 fusants were isolated (f-1 - f-25). In solid substrate, oxytetracycline production of 20% fusants was higher than that of the wild strain, while in submerged fermentation, it was 44%. Oxytetracycline productions of fusants f-1, f-6, f-11, f-12, f-20 and f-21 were lower than that of the wild strain in solid substrate, but this was reversed in submerged fermentation. On the other hand, OTC production of fusant f-8 was higher than that of the wild strain in solid substrate, and this was reversed in submerged fermentation.

Fermentation↗
PubMed1990

A human hepatocellular carcinoma 3.0-kilobase DNA sequence transforms both rat liver cells and NIH3T3 fibroblasts and encodes a 52-kilodalton protein.

Neoplastic transformation of rat liver cells in vitro by DNA-mediated gene transfer with an oncogene, hhcM, derived from human (Mahlavu) hepatocellular carcinoma, is described and compared with that of NIH3T3 cells. hhcM was cloned in a neomycin-resistant simian virus 40 promoter vector (pNeor/S) and was designated pNrpM-1. BRL-1 or NIH3T3 cells, transfected with pNrpM-1 DNA, showed significant morphological changes, loss of contact inhibition, and anchorage-independent growth. They became highly tumorigenic in nude rats and nu/nu mice. Control BRL-1 and NIH3T3 cells, whether transfected with pNeor/S DNA or not, remained contact inhibited and nontumorigenic. Both the transformants and the tumor cells contained integrated hhcM DNA as shown by Southern blot hybridization. The complete nucleotide sequence of the hhcM 3.0-kilobase DNA was also determined, and it consisted of a possible open reading frame for a protein of 52 kilodaltons (467 amino acids). The high-level production of a slightly modified form of this 52-kilodalton protein in a bacterial expression system has been successfully achieved. The bacteria-produced protein was similar in electrophoretic behavior to the 52- to 53-kilodalton protein synthesized in a cell-free translation system using rabbit reticulocyte lysate programmed with hybrid-selected hhcM-specific mRNA from Mahlavu hepatocellular carcinoma cells.

Animals↗
PubMed1990

ADAM sequence and innocent amniotic band: manifestations of early amnion rupture.

Thirteen placentas with early amnion rupture (EAR) are described. These placentas were characterized by the absence of amniotic epithelium on the fetal surface, presence of a slightly fibrotic small amniotic band (remnant) attaching to the umbilical cord at the placental end, and the presence of degenerated vernix squamous cells in the fibrous stroma of chorion and amnion. Eight fetuses had ADAM sequence. Six of these fetuses were miscarried between 16 and 28 weeks of gestation. Two affected infants were born alive at gestational ages of 29 and 39 weeks. Five infants were spared by ADAM sequence; two had the umbilical cord strangulated by an amniotic band and were delivered at 27 and 37 weeks. In the 3 infants unassociated with ADAM sequence or strangulation of the umbilical cord, their placentas were interpreted as having innocent amniotic band (IAB) and they were delivered between 32 and 40 weeks. The findings in this study support Torpin's hypothesis that ADAM sequence is a complication of EAR. This ADAM sequence due to simple EAR must be separated from the limb body wall malformation complex because visceral anomalies are uncommon in the former condition but are frequently seen in the latter. In this study the placental pathology of EAR was helpful in confirming the ADAM sequence in the fetus.

Abnormalities, Multiple↗
PubMed1990

Urachal remnants: sonographic demonstration in children.

On 62 of 100 pediatric bladder sonograms a small, elliptical, hypoechoic structure was observed on the middle of the anterosuperior surface of the urinary bladder. One of the these structures was removed surgically, and pathologic examination disclosed a normal urachal remnant. Since it is a common sonographic finding in children, it should not be mistaken for a pathologic process unless it is accompanied by signs and symptoms of infection or bladder obstruction.

Abdominal Muscles↗