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Biomedical subjects

S H Wei

Publications and source records attributed to S H Wei.

At least 19 recordsLinked to original sources
PubMed1992

Glutathione monoethyl ester moderates mercuric chloride-induced acute renal failure.

Glutathione (GSH)-dependent reactions are an important cellular defense against ischemic or oxidative injury, although their role in toxin-induced renal cellular injury is less clear. Because of the known sulfhydryl reactivity of mercury (M), we hypothesized that GSH could modify mercuric chloride (MC)-induced acute renal failure (ARF). Therefore, we evaluated the effects of glutathione monoethyl ester (GE), which produces high intrarenal levels of GSH, on the nephrotoxicity of MC. GE treatment in normal rats did not alter their creatinine clearance (CCr), fractional sodium (CNa/CCr) or lysozyme (CLy/CCr) excretion, but histologically resulted in prominent proximal tubular vacuolization. GE pretreatment in rats with MC-induced ARF resulted in partial preservation of their CCr, CNa/CCr and CLy/CCr. Renal histology also demonstrated a reduction in tubular necrosis. M content in the renal cortex 3 following MC was lower in the MC + GE group, but levels were higher in the liver and inner stripe/inner medulla as compared to animals receiving MC alone. No differences were seen in the outer stripe at 3 h or in any of the tissues 24 h following MC injection. Thus, GE moderated MC-induced ARF, likely by providing a large intracellular sulfhydryl pool and thereby reducing M reactivity with endogenous cellular proteins and enzymes.

Acute Kidney Injury↗
PubMed1992

Role of glutathione metabolism in the reduction of proteinuria by dimethylthiourea in adriamycin nephrosis.

Glutathione (GSH) metabolism, a tissue detoxification pathway, was evaluated in rats with adriamycin nephrosis (AN) treated with dimethylthiourea (DMTU), a free radical scavenger. After 7 days of DMTU, a significant reduction in proteinuria occurred as compared to AN controls (62.4 +/- 13.3 vs. 155.0 +/- 24.0 mg/24 h). A significant increase in renal cortical GSH content as well as glutathione peroxidase (GP) and transferase (GT) activities occurred in DMTU-treated rats as compared to controls. Glutathione monoethyl ester (GME) administration alone reduced proteinuria by 21% in AN, which was not significant despite a large increase in the renal GSH content, however, GP and GT activities were not increased by GME. We conclude that DMTU ameliorates glomerular injury in AN by stimulating GSH metabolism.

Animals↗
PubMed1992

Treatment of Class II open bite in the mixed dentition with a removable functional appliance and headgear.

Early diagnosis of patients exhibiting open bites that are complicated by skeletal Class II and vertical growth problems can facilitate subsequent treatment. Eight patients with Class II skeletal open bite were treated with the high-pull activator appliance and compared to reasonably matched controls to determine the effects of the appliance. The high-pull activator was found to reduce forward growth of the maxilla and increase mandibular alveolar height, transforming the Class II molar relationship into a Class I molar relationship. The overjet and open bite were decreased, and, in addition, the appliance reduced the amount of forward and downward movement of the maxillary molars, providing vertical control of the maxilla during Class II orthopedic correction. These results demonstrated that open bite complicated by a Class II vertical growth pattern can be treated during the mixed dentition with favorable results by a combination of a removable functional appliance and high-pull headgear.

Activator Appliances↗
PubMed1992

Management of rampant caries in children.

Because research has resulted in a better understanding of the etiology of dental caries as well as the introduction of new techniques and materials in the practice of dentistry, approaches toward the management of rampant caries should be reevaluated. The development of the acid-etching technique and the improvements in the physical properties and clinical performance of composite resins and glass-ionomer cements have completely changed the concepts of prevention, conservative dentistry, and dental esthetics. Several methods for the treatment of rampant caries are described and management of two cases is documented.

Acute Disease↗
PubMed1992

Effect of protraction headgear on Class III malocclusion.

Ten patients with skeletal Class III malocclusion in the early mixed dentition who were treated with maxillary expansion appliance and protraction headgear were compared with reasonably matched controls. Significant orthopedic effects were found after as little as 6 months of treatment. Cephalometric analysis revealed that the correction of Class III malocclusion was primarily a result of forward and downward movement of the maxilla and backward rotation of the mandible. The clinical result of one patient treated with this appliance is used to demonstrate the importance of force magnitudes and directions, as well as the design of the appliance, to the success of the treatment.

Cephalometry↗
PubMed1991

Purification, physicochemical characterization, and immunohistochemical localization of a major 11.7 S glycoprotein from the jelly coats of the anuran Lepidobatrachus laevis.

Embryos of the frog Lepidobatrachus laevis are encased by a fertilization envelope and two jelly layers, termed J1 (innermost) and J2 (outermost). From preparations of total jelly solubilized from cleavage-stage embryos by a solution of alkaline beta-mercaptoethanol we have purified one jelly coat glycoprotein to homogeneity via FPLC gel permeation chromatography on Superose 6H. The purified glycoprotein was 94% protein and 6% carbohydrate, had an s0(20),w of 11.7 S, with a molecular weight of 245,000 measured by sedimentation equilibrium and 263,000 by gel permeation chromatography. SDS-PAGE revealed that the glycoprotein is composed of a single subunit near 29,700 molecular weight; thus we propose that eight of these subunits comprise the native molecule. Amino acid analysis of the glycoprotein indicated a high content of Glx + Asx (32.4 mole%), a low content of basic amino acids (Arg + Lys = 12.2 mole%), and a single cysteine residue per subunit. The N-terminal amino acid was threonine and the sequence of the first twenty amino acids was determined. Monospecific antisera to the glycoprotein were prepared in rabbits and were used to immunohistochemically localize the glycoprotein throughout the matrix of both jelly layers. Antiserum against the glycoprotein had virtually no effect on the fertilizability of jellied eggs in vitro; thus we hypothesize that the glycoprotein fulfills a structural role in both jelly layers.

Amino Acid Sequence↗
PubMed1991

Cephalometric errors: a comparison between repeat measurements and retaken radiographs.

This study compares landmark location errors in cephalometric radiography (when re-measuring radiographs) and radiographic errors (when retaking the radiograph). The samples comprised 32 remeasured and re-digitized radiographs and a further series of 22 retaken radiographs drawn from the same overall sample of 12-year-old Chinese children in Hong Kong. All radiographs were recorded in natural head posture with the lips in light contact. The relative size of the errors were assessed by calculating the 'error percentage' for both selected dento-skeletal and soft tissue profile measures. It is suggested that this index is clinically more meaningful than the usually used 'method error'. It expresses the variance of the method error (me2) as a percentage of the variance of the measurement under study (standard deviation2). This error percentage was found to be doubled, on average, for measurements on the retaken radiographs. In general, measures with most landmarks in the mid-sagittal plane showed the least increase in percentage error. The results suggest that errors arising from retaking cephalometric radiographs may effectively be greater than those usually reported. The Frankfort plane, the functional occlusal plane and the incisor long axes displayed poor reproducibility. For the soft tissues the lips served as poor angular landmarks and relatively acute angles with short 'arms' also displayed large errors.

Analysis of Variance↗
PubMed1991

Amelioration of glomerular injury in doxorubicin hydrochloride nephrosis by dimethylthiourea.

The hydroxyl radical scavengers dimethylthiourea (DMTU), sodium benzoate, and dimethylsulfoxide (DMSO) were administered to rats before doxorubicin hydrochloride (ADR) (5 mg/kg, IV) to probe the role of free radicals in mediating proteinuria in doxorubicin hydrochloride nephrosis (AN). Because ADR stimulates free radical production, the role of renal glutathione was also evaluated; glutathione metabolism is involved in tissue detoxification processes. DMTU administration to rats with AN caused a significant (p less than 0.01) reduction in their proteinuria after 7 days (52.84 +/- 13.21 mg/24 hours) when they were compared with ADR controls (155.81 +/- 20.16 mg/24 hours). In similar fashion, their urine albumin excretion was also significantly reduced when compared with that of ADR controls (11.13 +/- 2.75 mg/24 hours vs 32.08 +/- 4.14 mg/24 hours; p less than 0.01). DMTU-treated rats also had significantly (p less than 0.001) reduced urinary protein and albumin excretion at 14 days when compared with rats that received ADR alone. The urinary excretion of lysozyme and N-acetyl-glucosaminidase, markers of renal tubular injury, were significantly increased after 7 or 14 days in rats with AN, despite DMTU treatment. Creatinine clearance was significantly reduced (p less than 0.05) in rats receiving ADR alone (0.223 +/- 0.011 ml/min/100 gm) when compared with that in normal controls (0.331 +/- 0.027 ml/min/100 gm) or DMTU-treated rats (0.289 +/- 0.035 ml/min/100 gm). Unlike DMTU, neither sodium benzoate nor DMSO reduced proteinuria in rats with AN.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylglucosaminidase↗
PubMed1991

Grafted and ungrafted labial gingival recession in pediatric orthodontic patients: effects of retraction and inflammation.

The purpose of this retrospective study was to determine changes in recession and other periodontal factors after orthodontic treatment of malocclusions. Twenty patients with preorthodontic labial recession on one or more mandibular central incisors were studied. Ten patients had received autogenous gingival grafts in the area of recession prior to orthodontics, while ten received no graft. The teeth presenting recession had been retruded from a preorthodontically prominent arch position. Moderate inflammation of marginal tissues and fair-to-poor oral hygiene were maintained by the patients. Statistically significantly less gingival recession was found in both groups after orthodontic treatment than was found pretreatment. The results of this study indicated that labial recession tends to decrease with retrusion of mandibular incisors even when moderate inflammation and fair-to-poor oral hygiene persist. Preorthodontic gingival grafting did not further decrease the postorthodontic gingival recession.

Adolescent↗
PubMed1990

Assessing treatment effectiveness of removable and fixed orthodontic appliances with the occlusal index.

Orthodontists from different backgrounds may have different opinions about removable and fixed orthodontic appliances, but there have been few objective comparisons of their relative treatment effectiveness. It is the purpose of the present study to analyze objectively the effectiveness of these two types of appliances. Eighty cases involving patients who had been treated with removable appliances and 67 cases of patients treated with fixed appliances were studied with respect to the Occlusal Index (OI). Scores indicating severity of malocclusion were obtained from pretreatment and posttreatment study casts. The effectiveness of the fixed appliance (represented by average reduction in OI score) was much greater than that of the removable appliance. The result of treatment with the fixed appliance was also found to be much better than that of the treatment with the removable appliance (indicated by the much lower posttreatment OI score in the fixed-appliance cases). The Occlusal Index was designed to measure features of basic malocclusion and is not a very sensitive index for assessing symptoms of a developing malocclusion. The fact that both the treatment effectiveness and the treatment results of the removable appliance were found to be inferior to those of the fixed appliance may indicate that the removable appliance has been used largely to correct "symptoms" rather than basic malocclusion.

Adolescent↗
PubMed1989

A comparative study of southern Chinese and British Caucasian cephalometric standards.

A comprehensive cephalometric comparison between unselected Chinese and Caucasian 12-year-old male children in natural head posture finds the intracranial reference planes to slope down more caudally in the Chinese. By superimposing on true vertical, the degree of prognathism in the Chinese becomes apparent. Significant intergroup differences are highlighted for both selected dentoskeletal and soft tissue profile variables.

Asian People↗