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Biomedical subjects

R R Wang

Publications and source records attributed to R R Wang.

At least 19 recordsLinked to original sources
PubMed2001

[Value of transvaginal sonography in diagnosis of placenta previa].

OBJECTIVE: To investigate the value of transvaginal sonography (TVS) in diagnosis of placenta previa. METHODS: Transabdominal sonography(TAS) and TVS localization of the placenta were performed in 78 pregnant women after 35 week's gestation. It was suspected of having placenta previa when the placental edge appeared to be over or within 2 cm in diameter of the internal cervical os demonstrated by TAS or TVS. Final diagnosis depended on diagnosis at delivery. The diagnostic sensitivity, specificity, false-positive rate and coincidence rate were made in comparison between TVS and TAS. RESULTS: The sensitivity, specificity, false-positive rate and coincidence rate of TVS were 100%, 90%, 10% and 93.6%, while that of TAS were 71.4%, 60%, 40% and 64.1%, respectively. The coincidence rate of TVS was better than TAS (p < 0.01). CONCLUSION: TVS is superior to TAS in diagnosis of placenta previa.

Adult↗
PubMed2001

The effect of aging on glutathione peroxidase-i knockout mice-resistance of the lens to oxidative stress.

Populations of control, C, and glutathione peroxidase-1 (GPx-1) knockout mice, K, were studied over a period of 2 years. No significant difference was observed between the C and K populations with respect to longevity, vitality, weight, lens biochemistry or morphology based on light and electron microscopy. It was concluded that under normal animal room barrier facilities, GPx-1 is not required. Furthermore, C and K lenses placed in organ culture and observed over a 24 hr period were indistinguishable. Organ cultured C lenses degraded medium H(2)O(2)levels at only a slightly greater rate than K lenses and this did not appear to change with age. However, tertiary butyl hydroperoxide (TBHP) was degraded less effectively by K lenses and this deficiency increased with age. No indication of change in redox non-protein SH (equivalent to GSH) status was observed between C and K whole lenses or epithelial cell fractions. With H(2)O(2)stress, the drop in C and K non-protein SH was comparable and there was little change with age. Examination of the impact of photochemical stress with 1.5 microM riboflavin and 4% O(2)upon choline transport indicated considerable damage with both C and K lenses, but little difference between the two populations until 1 or 2 years of age when the K lenses appear more vulnerable. With TBHP, the detrimental effect on the K lenses is greater and is observed earlier than with photochemical stress suggesting that the K lens membrane function is more susceptible to phospholipid hydroperoxide stress than are C lenses. Light and electron microscopy of the oxidative stressed lenses indicates significant damage which was generally somewhat greater in the K lenses. TBHP was a more potent oxidant than photochemically generated oxidants particularly at the anterior pole. The overall results suggest that under normal conditions, at any age, the lens does not require the presence of GPx-1 but depending on the type of oxidative stress, the enzyme may significantly contribute to its defense and this dependency may increase with age.

Aging↗
PubMed2001

Development of a STS marker assay for detecting loss of heterozygosity in rice hybrids.

The RAPD (random amplified polymorphic DNA) markers OPE15750 and OPE15300 were affected by loss of heterozygosity (LOH) in rice hybrids AMR x 'M202' and AMR x 'L202'. The markers were mapped to the same locus at or near the centromere of rice chromosome 2. The two RAPD products were cloned, sequenced, and found to have lengths of 734 bp and 297 bp, respectively. The 297-bp sequence shares a 98% homology with one end of the 734-bp sequence, accounting for the cross-hybridization previously observed between the two clones. Based on the DNA sequence of the 734-bp fragment, a pair of STS (sequence-tagged site) primers was designed and tested. Rice plants homozygous for either OPE15734 or OPE15297 all produced PCR fragments of the same length, 482 bp. However, the two PCR products were discernible by digestion with the restriction enzyme XbaI prior to gel electrophoresis. The STS product from plants homozygous for OPE15734 was cut into two fragments of 239 and 240 bp, which appeared as one single band in an agarose gel; whereas the STS product from plants homozygous for OPE15297 was not cut by XbaI and was characterized by a 482-bp band in the agarose gel. These STS primers were tested in rice hybrids and F2 progenies derived from the hybrids of AMR x 'M202' and AMR x 'L202'. Homozygosity for OPE15297 was confirmed for all F2 panicle rows derived from AMR x 'M202'. In contrast, F2 panicle rows of AMR x 'L202' exhibited two different segregation patterns (genotypes), i.e., either uniformly homozygous for the 240-bp marker (OPE15734/OPE15734) or segregating for the 482- and 240-bp markers (OPE15734/OPE15297). This STS-marker system provides a robust assay for detecting the occurrence of LOH in rice hybrid progenies.

Base Sequence↗
PubMed2000

Effect of acupuncture on pain management in patients before and after lumbar disc protrusion surgery--a randomized control study.

Management of acute and chronic low back and leg pain often includes the use of acupuncture. The effectiveness of this form of therapy is dependent upon compliance, which in turn is dependent on availability, response, treatment of proper acupoints, and the placebo effect. We hypothesized that classical acupuncture would be more effective than placebo acupuncture. One hundred and thirty-two patients with acute and chronic low back and leg pain were examined before and after surgery for lumbar disc protrusion. Diagnosis was based on CT and MRT findings. Patients received acupuncture drug-free throughout the study period. The visual analogue scale was used to assess pain intensity before and after (i.e. 30 min. 60 min. 2 h and 6 h) acupuncture. Classical acupuncture resulted in a significant reduction in pain that become increasingly stronger during the 6h study period. Placebo acupuncture lead to same early pain relief that did not reach statistic significant and then declined thereafter.

Acupuncture Analgesia↗
PubMed2000

Development and characterization of an H2O2-resistant immortal lens epithelial cell line.

PURPOSE: To determine how nature would protect lens epithelial cells from H2O2 stress, an immortal murine lens epithelial cell line, alphaTN4-1, was subjected to gradually increasing H2O2 levels over a period of approximately 8 months. The resultant conditioned cells grew normally when exposed daily to 125 microM H2O2, whereas normal cells died within 9 hours. This communication describes changes in the cell biology of the conditioned cells that allowed them to remain viable. The manner in which critical biochemical parameters were affected in both conditioned and normal cells is also reported. METHODS: Conditioned cells were obtained by gradually increasing the concentration of H2O2 over a period of approximately 8 months, introducing an aliquot of H2O2 every 24 hours. A wide spectra of biological parameters were evaluated, including catalase, GSH peroxidase and other antioxidative enzyme activities, cell number and cell viability, non-protein thiol, ATP, transport systems, thymidine incorporation, and DNA cleavage. RESULTS: Surprisingly, the conditioned cells did not degrade the medium H2O2 more rapidly than normal cells. However, analyses of the antioxidative defenses indicated that catalase activity was increased 60-fold and glutathione peroxidase (GSH Px) approximately 2.7-fold. Glucose-6-phosphate dehydrogenase, GSH S-transferase, and GSSG reductase also had increased activity. Using one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, in situ trypsin digestion and matrix-assisted laser desorption/ionization mass spectrometry, a highly amplified doublet in the conditioned cell preparation was shown to be GSH S-transferase alpha-1 and alpha-2 isomers. Examination of key biochemical parameters indicated that while most such parameters in the conditioned cells showed marked decay in the first hour or so after stress, recovery was then observed and within a few hours, these parameters were back in the normal range. In contrast, damage in the normal cells was not repaired. The damage to DNA was shown to involve Fenton chemistry. In the presence of a metal ion chelator, normal cells survive H2O2 stress. CONCLUSIONS: The overall conclusion from this investigation is that nature has chosen to respond to the H2O2 stress by not only increasing the activity of enzymes degrading H2O2 but also the systems involved in repair, generation of reducing potential, and detoxification. All but one system of those evaluated appears to be permanently modified.

Adenosine Triphosphate↗
PubMed2000

Linkage mapping and nucleotide polymorphisms of the 6-SFT gene of cool-season grasses.

Fructan plays an important role as an alternate carbohydrate and may contribute to drought and cold-stress tolerances in various plant species. The gene coding for sucrose:fructan 6-fructosyltransferase (6-SFT; EC 2.4.1.10), an enzyme that catalyzes the formation and extension of beta-2,6-linked fructans (levans), is important to fructan synthesis in many cool-season grasses, including cereal species. In this study, we compared a conserved sequence from the 6-SFT gene in barley with comparable sequences in 20 other cool-season grasses. We detected several DNA length polymorphisms, including variations in one simple-sequence repeat (SSR) in a 6-SFT intron of the barley cultivars Steptoe and Morex. Using the 'Steptoe' x 'Morex' doubled-haploid mapping population, the 6-SFT gene was genetically mapped to the distal region in the short arm of barley chromosome 1 (7H), where it is closely linked with trait locus Rpg1. Primers designed from other conserved regions of the barley 6-SFT gene successfully amplified 351- or 354-bp sequences of this gene from diverse cool season grass species. Sequence identities of the PCR products were greater than 80% among the 21 species. Phylogeny, as determined using these DNA sequences, is similar to that obtained from rDNA ITS sequences, and congruent with our current knowledge of genome relationships.

Base Sequence↗
PubMed1999

Silicon nitride coating on titanium to enable titanium-ceramic bonding.

Failures that occur in titanium-ceramic restorations are of concern to clinicians. The formation of poorly adhering oxide on titanium at dental porcelain sintering temperatures causes adherence problems between titanium and porcelain, which is the main limiting factor in the fabrication of titanium-ceramic restorations. To overcome this problem a 1-microm thick Si3N4 coating was applied to a titanium surface using a plasma-immersion implantation and deposition method. Such a coating serves as an oxygen diffusion barrier on titanium during the porcelain firings. The protective coating was characterized in the as-deposited condition and after thermal cycling. Cross sections of Ti/Si3N4-porcelain interface regions were examined by various electron microscopy methods and by energy dispersive analysis of X-rays to study the Si3N4 film's effectiveness in preventing titanium oxidation and in forming a bond with porcelain. The experiments have shown that this Si3N4 coating enables significant improvement in Ti-ceramic bonding.

Dental Porcelain↗
PubMed1999

Hemifacial microsomia and treatment options for auricular replacement: A review of the literature.

STATEMENT OF PROBLEM: Although surgical reconstruction is the treatment of choice for auricular deformities that result from hemifacial microsomia, the implant-retained auricular prosthesis must be considered when surgical reconstruction is not possible. The competent and successful practitioner should be knowledgeable of the nature of this congenital disease. PURPOSE: This article reviewed the first and second branchial syndrome, treatment approaches, and potential advances in surgical and prosthetic rehabilitation for patients with hemifacial microsomia. CONCLUSION: Advantages and disadvantages of autogenous and alloplastic ear reconstructions are discussed. New research initiatives, such as tissue engineering and fabrication of auricular prosthesis by CAD/CAM, offer the potential for improved treatment for the future treatment of hemifacial microsomia.

Branchial Region↗
PubMed1998

Scanning acoustic microscopy study of titanium-ceramic interface of dental restorations.

Failures that occur in titanium-ceramic restorations are of concern in clinical dentistry. The purpose of this study was to nondestructively characterize the internal cracks and nonadherent defects at the titanium-porcelain interface using scanning acoustic microscopy. Titanium samples coated with porcelain without a bonding agent, with sputter coated palladium or chromium as an oxygen diffusion barrier on the titanium, and with the use of a porcelain bonding agent (control group) were compared. The scanning acoustic microscopy analyses were correlated with four-point bending test results. The group that was initially coated with palladium had fewer interfacial defects and a higher load to failure than the control group, and the group that did not contain the bonding agent had a higher void area and a lower load to failure than the control group. The use of chromium produced no differences from the control group. Samples after a four-point bending test were also analyzed by scanning electron microscopy. The scanning electron microscopy was not able to characterize interfacial defects at the fractured titanium-ceramic interface for some of the samples. The validity of nondestructive analysis at the Ti-ceramic interface using scanning acoustic microscopy was demonstrated in this study.

Chromium↗
PubMed1998

The effect of photochemical stress upon the lenses of normal and glutathione peroxidase-1 knockout mice.

This communication investigates the effect of oxidative stress upon the lenses of young normal and glutathione peroxidase-1 (GSHPx-1) Knockout mice. Both normal and knockout lenses have similar biochemical and morpholigical characteristics and the elimination of GSHPx-1 only decreases slightly the ability of the lens to degrade H2O2. Examination of the effect of a 4 hr photochemical stress on morphological characteristics indicates that there is comparable damage in the normal and knockout lenses in the epithelial and bow regions while the posterior region remains normal. However, at 24 hrs post-insult, the normal lenses appear to recover somewhat in the bow region while the knockout bow and posterior regions have extensive damage. In contrast to the morphological data, the biochemical parameters (14C)choline transport and (3H)thymidine incorporation are affected to a somewhat greater extent in the knockout lenses than in normal lenses. While both of these parameters are further affected in the 24 hr post-insult period, there is no further change in the relative effects upon normal and knockout lenses. Non-protein thiol is affected in a similar manner in both lens types. The effect upon biochemical parameters of tertiary butyl hydroperoxide (TBHP) insult was similar to H2O2 and photochemical stress. The overall conclusion is that young GSHPx-1 knockout lenses handle oxidative stress somewhat less effectively than comparable normal lenses but non-stressed knockout lenses appear normal. These results differ from observations reported by Reddy et al. (1997) under somewhat different conditions.

Animals↗
PubMed1998

The effect of catalase amplification on immortal lens epithelial cell lines.

Utilizing a human beta-actin promoter, a catalase cDNA expression vector was constructed. This construct was used to transfect two immortal cell lines, mouse alpha TN4-1 and rabbit N/N 1003A. The catalase activity was increased about 3.4 fold in the alpha TN4-1 cells and 38 fold in the N/N 1003A cells. Some changes in other enzyme activities were also observed as a result of the transfections. Surprisingly, the ability to degrade H2O2 in the extracellular environment of the cells did not markedly change as a result of the catalase amplification. However, the ability to resist H2O2 stress was dramatically altered. Non-protein thiol (NP-SH) levels, choline uptake and glyceraldehyde phosphate dehydrogenase (GPD) activity were all markedly decreased in the non-transfected cells when they were subjected to 300 microM H2O2. However, in both transfected cell lines, these parameters remained in the normal range during H2O2 stress. The results obtained upon observing aspects of DNA metabolism were more complicated. While on H2O2 stress, non-transfected cell lines showed a marked decrease in thymidine incorporation, only the transfected alpha TN4-1 line remained in the normal range. Thymidine incorporation in transfected rabbit N/N 1003A cells was decreased compared to normal cells. In contrast, studies on single strand DNA breaks indicated that transfected rabbit cells had little damage compared to the significant DNA damage observed in the normal cells. The normal N/N 1003A cells were also much more susceptible to H2O2 induced damage than normal alpha TN4-1 cells, suggesting that the high GSH peroxidase activity observed in the rabbit cells may be detrimental since the low glutathione reductase activity in such cells results in an accelerated depletion of glutathione. The overall results suggest that augmenting lens catalase may prevent cataract development caused by H2O2 stress.

Animals↗
PubMed1998

In vitro evaluation of biocompatibility of experimental titanium alloys for dental restorations.

STATEMENT OF PROBLEM: Applications of titanium casting to fixed and removable prostheses have not been satisfactory because of the high melting point of titanium and its great reactivity with mold materials. Low-melting titanium alloys would alleviate many casting problems. At the present time, low-melting titanium alloys are not available for clinical dental use. PURPOSE: The study evaluated the safety of 2 prototype low-melting titanium casting alloys for their future development for dental restorations. The 2 experimental titanium alloys were titanium-cobalt(Ti 81.4% wt, Co 18.6% wt) and titanium-silver (Ti 75% wt, Ag 25% wt). Commercially pure titanium and a commonly used nickel-chromium-based dental alloy were also included for comparison. MATERIAL AND METHOD: Assays for evaluating mutagenicity and cytotoxicity were Ames salmonella/microsome mutagenicity spot test, agar diffusion method, and cell attachment assay. RESULTS: The results of Ames test showed that none of the experimental titanium alloys, pure titanium, or nickel-chromium samples were mutagenic. There were no leachable components to cause cellular lysis or decolorization in the agar diffusion assay from the 4 group metals. The results of the cell attachment assay demonstrated that there was no significant difference in the numbers of cells attached to the 4 group metals. However, the mean number of cells attached to nickel-chromium samples was significantly lower than that of the control group. CONCLUSIONS: On the basis of the data obtained from this study, it is concluded that the prototype Ti alloys are not mutagenic and imposes minimal risks associated with cytotoxicity.

Agar↗
PubMed1998

Thermoplastic resin used to modify an alveolar orthopedic prosthesis in a patient with cleft lip before cheiloplasty: a clinical report.

Correction of cleft lip and cleft palate is a multidisciplinary team effort. Severe bilateral clefts with protruded and rotated premaxillae may complicate surgical correction. Prosthetic intervention to reposition segments before surgical correction may improve the bony base for tissue molding and avoid excess tension at the surgical site. A conventional bulb prosthesis with bonnet and straps is often used as an extraoral device to retract a protruded premaxilla for severe cleft patients before cheiloplasty. Sometimes, because of lack of retention, stability, patient compliance, and controllable forces from a bonnet and straps, movement of the premaxillae to a desirable position is difficult to achieve. The use of thermoplastic resin to modify a bulb prosthesis as described in this clinical report is a simple method to provide good retention for the bulb prosthesis and to move a laterally displaced premaxillae to the facial midline. The wedging effect created by the thermoplastic resin generated "compressive forces" to the premaxilla that was more controllable than the pulling forces created by the bonnet and straps therapy. Thermoplastic resin is also a better material than a conventional chemically polymerized acrylic resin in dealing with an infant's delicate mucosa before cheiloplasty.

Cleft Lip↗
PubMed1998

Thermal modeling of laser welding for titanium dental restorations.

STATEMENT OF PROBLEM: Concerns of laser welding for titanium dental prostheses are the limited depth of laser beam penetration and extensive surface damage. PURPOSE: This study used numerical heat transfer simulation to explain this behavior and offers an alternate multiple-pulsed method. MATERIAL AND METHODS: A one-dimensional finite difference analysis was used to simulate heat transfer in pure titanium and gold during laser welding with a custom-constructed software program. RESULTS: The thermal gradient profiles revealed the problem to be inherent in titanium's low thermal conductivity; gold did not have this problem. Time-elapsed multiple pulses on titanium relieved this problem by giving the energy time to diffuse into the depth of the material. CONCLUSIONS: With single-pulse laser irradiation on titanium, an increase in power could not greatly increase melting depth. The excess energy only vaporized the material surface.

Computer Simulation↗
PubMed1998

Genome-specific repetitive DNA and RAPD markers for genome identification in Elymus and Hordelymus.

We have developed RFLP and RAPD markers specific for the genomes involved in the evolution of Elymus species, i.e., the St, Y, H, P, and W genomes. Two P genome specific repetitive DNA sequences, pAgc1 (350 bp) and pAgc30 (458 bp), and three W genome specific sequences, pAuv3 (221 bp), pAuv7 (200 bp), and pAuv13 (207 bp), were isolated from the genomes of Agropyron cristatum and Australopyrum velutinum, respectively. Attempts to find Y genome specific sequences were not successful. Primary-structure analysis demonstrated that pAgc1 (P genome) and pAgc30 (P genome) share 81% similarity over a 227-bp stretch. The three W genome specific sequences were also highly homologous. Sequence comparison analysis revealed no homology to sequences in the EMBL-GenBank databases. Three to four genome-specific RAPD markers were found for each of the five genomes. Genome-specific bands were cloned and demonstrated to be mainly low-copy sequences present in various Triticeae species. The RFLP and RAPD markers obtained, together with the previously described H and St genome specific clones pHch2 and pP1Taq2.5 and the Ns genome specific RAPD markers were used to investigate the genomic composition of a few Elymus species and Hordelymus europaeus, whose genome formulas were unknown. Our results demonstrate that only three of eight Elymus species examined (the tetraploid species Elymus grandis and the hexaploid species Elymus caesifolius and Elymus borianus) really belong to Elymus.

Base Sequence↗
PubMed1998

The aqueous humor is capable of generating and degrading H2O2.

PURPOSE: To determine the ability of the aqueous humor to generate and degrade H2O2, the effect of environmental factors such as oxygen tension and temperature, and the constituents contributing to the observed results. METHODS: Aqueous humor was carefully removed from bovine eyes within 3 hours of death. Standard and new techniques were used to follow H2O2 degradation and formation. Catalase activity was measured by H2O2 decomposition, usually at 100 microM and 10 mM H2O2, and in some cases by O2 generation. RESULTS: Bovine aqueous humor generated and degraded H2O2. The generation of H2O2 was minimal at 0 degrees C but increased as temperature increased, so that at 37 degrees C at 3 hours, approximately 90 microM H2O2 was observed. Degradation was more complex. At 0 degrees C, only a slow rate of degradation was observed. At 25 degrees C, it was more rapid, and a steady state between generation and degradation was observed at approximately 30 microM. However, at 37 degrees C, starting with 100 microM H2O2, degradation was initially rapid, but then generation became predominant and H2O2, concentration increased to more than 100 microM in 3 hours. No H2O2 was generated in the absence of O2, and H2O2 production increased with increasing O2 tension. Both low and high molecular weight components contributed to the degradation, but synthesis was completely dependent on low molecular weight constituents. Ascorbic acid and metal ions such as Cu+ made a major contribution to H2O2 production. Catalase may be the macromolecular component responsible for aqueous H2O2 decay, as evidenced by H2O2 degradation, inhibition by boiling or 3-aminotriazole, and the approximate correspondence between oxygen generation and H2O2 degradation. CONCLUSIONS: The results indicate that the aqueous humor is capable of producing levels of H2O2 that have been shown previously to cause cataract in organ culture. Changes in aqueous humor metal ion content and concentration of oxygen level have profound effects on H2O2 concentration and may effect lens viability. The variation in published H2O2 levels may in part be the result of the conditions under which the aqueous humor was obtained, stored, and used for assay. The observed steady state H2O2 concentration of 1 microM in fresh aqueous from bovine eyes must be maintained by the metabolism of surrounding tissues as well as intrinsic components capable of degrading H2O2.

Animals↗