Noninvasive Diagnostic Technique for Nonalcoholic Fatty Liver Disease Based on Features of Tongue Images

OBJECTIVE

To investigate a new noninvasive diagnostic model for nonalcoholic fatty liver disease (NAFLD) based on features of tongue images.

METHODS

Healthy controls and volunteers confirmed to have NAFLD by liver ultrasound were recruited from China-Japan Friendship Hospital between September 2018 and May 2019, then the anthropometric indexes and sampled tongue images were measured. The tongue images were labeled by features, based on a brief protocol, without knowing any other clinical data, after a series of corrections and data cleaning. The algorithm was trained on images using labels and several anthropometric indexes for inputs, utilizing machine learning technology. Finally, a logistic regression algorithm and a decision tree model were constructed as 2 diagnostic models for NAFLD.

RESULTS

A total of 720 subjects were enrolled in this study, including 432 patients with NAFLD and 288 healthy volunteers. Of them, 482 were randomly allocated into the training set and 238 into the validation set. The diagnostic model based on logistic regression exhibited excellent performance: in validation set, it achieved an accuracy of 86.98%, sensitivity of 91.43%, and specificity of 80.61%; with an area under the curve (AUC) of 0.93 [95% confidence interval (CI) 0.68-0.98]. The decision tree model achieved an accuracy of 81.09%, sensitivity of 91.43%, and specificity of 66.33%; with an AUC of 0.89 (95% CI 0.66-0.92) in validation set.

CONCLUSIONS

The features of tongue images were associated with NAFLD. Both the 2 diagnostic models, which would be convenient, noninvasive, lightweight, rapid, and inexpensive technical references for early screening, can accurately distinguish NAFLD and are worth further study.

[Outcome of pediatric-to-adult liver transplantation:a single-center study in China]

Objective: To explore the outcome of the pediatric-to-adult liver transplantation, including postoperative complications and relevant factors which affecting graft survival. Methods: Data of 55 patients undergoing pediatric-to-adult liver transplantation at the First Affiliated Hospital of Zhejiang University between January 2015 and August 2021 were retrospectively analyzed. The donors consisted of 34 males and 21 females, and the age was (11.8±4.7) years (range: 1 to 17 years). Among the cases,17 cases (30.9%) were donation of brain death,32 cases (58.2%) were donation of cardiac death, and 6 cases (10.9%) were donation after brain death plus cardiac death. The recipients consisted of 32 males and 23 females, and the age was (51.6±10.1) years (range: 27 to 70 years). Among the recipients,10 cases (18.2%) were ABO-incompatible liver transplantation.The influencing factors of early graft survival were analyzed by Student t test,Mann-Whitney U test or χ² test,respectively.Survival curve was drawn by Kaplan-Meier method.Logistic multivariate analysis was used to analyze the independent relevant factors of early postoperative graft loss. Results: Up to October 31,2021,the follow-up time (M(IQR)) was 36.0(43.1)months(range:5.9 to 81.7 months).There were 13 cases with graft loss (two of them underwent re-transplantation due to acute liver failure).The monofactor analysis indicated that cold ischemia time and donor-recipient blood group matching were the relevant factors affecting the early graft survival rate(both P<0.05).Logistic multivariate analysis showed that cold ischemia time and history of recipient gastrointestinal bleeding were independent relevant factors(both P<0.05).Postoperative hepatic artery thrombosis occurred in 3 cases(5.5%), portal vein thrombosis diagnosed in 4 cases(7.3%), portal vein stenosis occurred in 2 cases(3.6%),biliary complications diagnosed in 7 cases(12.7%), and small liver syndrome was found in 8 cases(14.5%). Conclusions: Adult liver transplantation with pediatric donor liver is an effective method to treat end-stage liver disease.Cold ischemia time and history of recipient gastrointestinal bleeding were independent relevant factors for the early graft survival.

Atherogenic index of plasma combined with waist circumference and body mass index to predict metabolic-associated fatty liver disease

BACKGROUND

Early identification of metabolic-associated fatty liver disease (MAFLD) is urgent. Atherogenic index of plasma (AIP) is a reference predictor of obesity-related diseases, but its predictive value for MAFLD remains unclear. No studies have reported whether its combination with waist circumference (WC) and body mass index (BMI) can improve the predictive performance for MAFLD.

AIM

To systematically explore the relationship between AIP and MAFLD and evaluate its predictive value for MAFLD and to pioneer a novel noninvasive predictive model combining AIP, WC, and BMI while validating its predictive performance for MAFLD.

METHODS

This cross-sectional study consecutively enrolled 864 participants. Multivariate logistic regression analysis and receiver operating characteristic curve were used to evaluate the relationship between AIP and MAFLD and its predictive power for MAFLD. The novel prediction model A-W-B combining AIP, WC, and BMI to predict MAFLD was established, and internal verification was completed by magnetic resonance imaging diagnosis.

RESULTS

Subjects with higher AIP exhibited a significantly increased risk of MAFLD, with an odds ratio of 12.420 (6.008-25.675) for AIP after adjusting for various confounding factors. The area under receiver operating characteristic curve of the A-W-B model was 0.833 (0.807-0.858), which was significantly higher than that of AIP, WC, and BMI (all P < 0.05). Subgroup analysis illustrated that the A-W-B model had significantly higher area under receiver operating characteristic curves in female, young and nonobese subgroups (all P < 0.05). The best cutoff values for the A-W-B model to predict MAFLD in males and females were 0.5932 and 0.4105, respectively. Additionally, in the validation set, the area under receiver operating characteristic curve of the A-W-B model to predict MAFLD was 0.862 (0.791-0.916). The A-W-B level was strongly and positively associated with the liver proton density fat fraction (r = 0.630, P < 0.001) and significantly increased with the severity of MAFLD (P < 0.05).

CONCLUSION

AIP was strongly and positively associated with the risk of MAFLD and can be a reference predictor for MAFLD. The novel prediction model A-W-B combining AIP, WC, and BMI can significantly improve the predictive ability of MAFLD and provide better services for clinical prediction and screening of MAFLD.

Conversion efficiency of multi-keV L-shell-band X-ray emission

This study explored the influence of foil thickness, laser pulse width, and laser intensity to optimize the multi-keV X-ray conversion efficiency of a sandwiched (CH/Sn/CH) planar target under laser irradiation at the Shenguang II laser facility. The X-ray photon field values were measured using a set of elliptically bent crystal spectrometers and the conversion efficiencies (ξ_x) of photon energies were in the range of 3.7-4.3 keV. The experimental results indicate that the X-ray yields of 3.7 to 4.3 keV radiation strongly depend on the laser pulse width, target thickness, and laser intensity. The results also demonstrate that three-layer thin foils can provide an efficient multi-keV X-ray source because they can change the distribution of emitted multi-keV X-rays and target dynamics versus nanosecond laser pulses to produce large, hot, and underdense plasma. However, the underdense plasma produced as a rarefaction wave causes the overdense plasma generated by the laser pulse to expand. Therefore, the laser parameters and foil thickness must be carefully optimized to produce an efficient 3.7 to 4.3 keV X-ray source. Otherwise, the rarefaction waves from both sides of the thin foil may suppress multi-keV X-ray emission. This study represents an important advancement in the development of an efficient multi-keV L-shell-band X-ray source.

[Follow-up study of patients with chronic obstructive pulmonary disease complicated with pulmonary hypertension]

Objective: To investigate the relationship between clinical characteristics of patients with chronic obstructive pulmonary disease (COPD) with pulmonary hypertension (PH) and COPD exacerbation over a three-year observation period. Methods: A total of 366 cases of stable COPD patients were enrolled from the Department of Respiratory Medicine of the First Affiliated Hospital of Henan University of Science and Technology. The patients underwent pulmonary function tests(PFT), COPD assessment test (CAT), Saint George's respiratory questionnaire (SGRQ), transthoracic echocardiogrophy(TTE), chest CT and biochemical detection. The likelihood of PH was evaluated based on the peak tricuspid regurgitation velocity (TRV) measured by echocardiography at rest and other indicators, which were represented by low, medium, and high probability, respectively. Highly probability was defined as PH. The mean values of the groups were compared using a two-tailed unpaired t test for normally distributed variables. Qualitative data were assessed using a χ² test. Pearson correlation analysis was performed, and risk factors were analyzed using logistic regression analysis and stepwise regression analysis. P<0.05 was considered to indicate statistical significance. Results: The prevalence of patients with high likelihood of PH was 18.3% (n=67) in a series of 366 patients with COPD. The median estimated systolic pulmonary artery pressure in patients with PH was (51.7±6.7) mmHg(1mmHg=0.133 kPa). There were differences between patients with high likelihood of PH and those with low to moderate likelihood of PH for the following factors: age (76.0 vs. 64.0), body mass index (BMI) [(21.4±6.0) kg/m² vs. (22.6±7.2)kg/m²], brain natriureticpeptide (BNP) [(50.8±9.1) pg/ml vs. (36.4±8.1) pg/ml], toral number of acute exacerbation in three-year [(6.1±0.1) times vs. (2.8±0.4) times], CAT (17.0 vs. 10.0), SGRQ (48.9 vs. 32.1), carbon monoxide diffusion percentage of predicted value (D_LCO%) [(51.9±21.9)% vs. (67.0±22.1)%]; all the differences being statistically significant(mean P<0.05).There was a negative correlation between D_LCO% and SPAP (r=-0.28, P<0.01).In patients with high likelihood of PH, the percentage of low attenuation area (LAA%) and interstitial abnormalities in chest CT were higher than those in patients with low to moderate likelihood of PH (56.1% vs. 34.3% and 30.8% vs. 15.6%, mean P<0.05).LAA% ≥ 30% and pulmonary interstitial abnormalities were independent risk factors for pH [beta value were 1.479, 1.065, OR value was (3.640-5.720), 95%CI (1.462-8.571), mean P<0.01]. The ratio of main pulmonary diameter to aortic artery diameter was significantly correlated with estimated systolic pulmonary artery pressure(r=-0.35, P<0.01).Age ≥75 years, FEV₁%predicted value<50% and the presence of PH increased the likelihood of exacerbations of COPD over three years[beta value (0.459-1.211), OR value (3.643-5.722), 95%CI (1.463-8.904), mean P<0.01]. Conclusions: COPD patients with high likelihood of PH assessed by echocardiography were older, had a lower BMI, and presented with a worse health status compared to those with low to moderate likelihood of PH. The presence of PH assessed by echocardiography was related to future COPD exacerbations in COPD patients, and emphysema was closely related to PH assessed by echocardiography.

[Effects of different fluid resuscitation on renal function and glycocalyx in septic shock rats]

To investigate the effects of different fluid resuscitation on renal function and glycocalyx in septic shock rats. The septic shock SD rats (induced by lipopolysaccharide) were randomly divided into control group, normal saline resuscitation group, Lactate Ringer's solution resuscitation group and succinyl gelatin resuscitation group (n=6 each). The mean arterial pressure, heart rate, serum creatinine (Scr), urea nitrogen (BUN), renal blood flow, renal tissue pathology, serum interleukin-6, tumor necrosis factor α and glycocalyx were measured at baseline, the development of septic shock, 0 hour and 8 hours after resuscitation. When shock was established, the renal blood flow significantly decreased (P<0.05) and recovered to normal at 0 hour and 8 hours after resuscitation. Compared with normal saline group and succinyl gelatin group, the levels of Scr, BUN and glycocalyx components (heparan sulfate, syndecan-1) were significant lower in Lactate Ringer's solution group (P<0.05). The pathology of kidney tissue suggested that the microscopic ischemic damage with Lactate Ringer's solution were minor than the other two groups. Compared with normal saline and succinyl gelatin, Lactate Ringer's solution can reduce the damage of renal function and glycocalyx in septic shock rats.

[Application of the Virtual Reality-Pattern Visual Evoked Potential in Forensic Visual Acuity Evaluation]

Abstract

Objective To explore a kind of visual evoked potential test equipment and method that is more suitable for the application of forensic clinical visual acuity evaluation. Methods Thirty-four volunteers （68 eyes） were selected, including 15 males and 19 females, aged between 20 and 40 years. Test lenses were placed before the tested eyes of volunteers to induce refractive myopia with insert method, and the diopter lenses were adjusted so that the visual acuity level of one eye of volunteers was above 0.8, and the visual acuity of the other eye was at moderate damage level （<0.3 and ≥0.1）. The tests were carried out under the binocular simultaneous asynchronous stimulation mode （hereinafter referred to as "binocular mode"） and monocular separate stimulation mode （hereinafter referred to as "monocular mode"） of virtual reality-pattern visual evoked potential （VR-PVEP）, and the amplitude of PVEP of volunteers under the two modes was compared at four spatial frequencies of 8×8, 16×16, 24×24 and 32×32. Results The differences in the amplitude of P100 wave between monocular and binocular modes at 8×8 spatial frequency had no statistical significance and the differences in amplitude of P100 wave between monocular and binocular modes at 16×16, 24×24, and 32×32 spatial frequencies had statistical significance （P<0.05）. The amplitude of the same eye in monocular mode was higher than that in binocular mode. Through correlation analysis, it was found that the amplitude of P100 wave in monocular mode was moderately correlated with amplitude of P100 wave in binocular mode. Conclusion In forensic identification practice, VR-PVEP is helpful for overcoming the disturbance of poor fixation, and to increase the reliability of PVEP evaluation results. It can greatly shorten the detection time of PVEP and improve work efficiency.

Effects of acarbose and siglitine on blood glucose fluctuation and islet β-cell function in patients with type 2 diabetes mellitus

The effects of acarbose and sitagliptin on blood glucose fluctuation and islet β-cell function in patients with type 2 diabetes mellitus (T2DM) were studied. One hundred and three patients with poorly controlled T2DM with insulin aspart 30 were selected and randomly divided into three groups: group A [continuous subcutaneous insulin infusion (CSII) treatment group], group B (CSII combined with acarbose treatment), group C (CSII combined with sitagliptin treatment). The treatment lasted for two weeks and the clinical indicators in the three groups were measured. The insulin dosage was adjusted according to the blood glucose statuses of the three groups of patients. In the final three days, 72 h of continuous glucose monitoring (CGM) were carried out, and the OGTT test was performed again. The results showed that the MODD (absolute means of daily difference), intra-day blood glucose fluctuation indices [(24 h MBG (mean blood glucose), LAGE (largest amplitude of glycemic excursions) and MAGE (average blood glucose fluctuation)] and postprandial blood glucose fluctuation indices [PGS (postprandial glucose spike), △t, PPGE (postprandial glucose excursion) and T (time) total] in group C and group B were significantly lower than those in group A. Compared with group B, the difference in blood glucose fluctuation indices in group C was not statistically significant (P>0.05). The HOMA-islet (homeostasis model assessment of islet) (CP-DM) index and FC-P (Fasting c-peptide) levels in group C and group B were significantly higher than those in group A (P less than 0.01). The HOMA-IR (CP) index of groups B and C was significantly lower than that of group A (P less than 0.01), and there was no statistically significant difference between groups B and C (P less than 0.05). Sitagliptin combined with intensive insulin pump therapy can reduce blood glucose fluctuation throughout the day, reduce insulin dosage, improve islet B cell function and reduce hypoglycemia better than intensive insulin pump therapy alone.

Elliptically bent crystal x-ray spectrometer for time-resolved laser plasma experiments

Measuring time-resolved spectra is crucial in inertial confinement fusion and radiation source development experiments. An elliptically bent crystal spectrometer is designed to measure X-rays in the range of 2.5-11.0 keV, which was achieved using four different lattice spacings of 0.8512, 0.6687, 0.4246, and 0.2749 nm with spectral resolution E/δE of ∼500. The X-rays emitted from a source at one focus of the ellipse undergo Bragg reflection off a crystal and pass through the second focus of the ellipse to a streak camera slit with 18-mm length and 80-μm width to generate a time-resolved spectrum. An alignment method for the time-resolved spectrometer was developed with the straight line connecting the centers of the two small holes on the fabricated substrate being the axis of the ellipse, thus allowing the spacing between the source and the elliptical crystal to be tuned to couple with the streak camera. The time-resolved spectrometer's performance was experimentally tested at the Shenguang II laser facility. The results indicate that its performance is close to that predicted theoretically.

Smoking prevalence and its influence on disease course and surgery in Crohn's disease and ulcerative colitis

BACKGROUND

Smoking demonstrates divergent effects in Crohn's disease (CD) and ulcerative colitis (UC). Smoking frequency is greater in CD and deleterious to its disease course. Conversely, UC is primarily a disease of nonsmokers and ex-smokers, with reports of disease amelioration in active smoking.

AIM

To determine the prevalence of smoking and its effects on disease progression and surgery in a well-characterised cohort of inflammatory bowel diseases (IBD) patients.

METHODS

Patients with smoking data of the Sydney IBD Cohort were included. Demographic, phenotypic, medical, surgical and hospitalisation data were analysed and reported on the basis of patient smoking status.

RESULTS

1203 IBD patients were identified comprising 626 CD and 557 UC with 6725 and 6672 patient-years of follow-up, respectively. CD patients were more likely to smoke than UC patients (19.2% vs. 10.2%, P < 0.001). A history of smoking in CD was associated with an increased proportional surgery rate (45.8% vs. 37.8%, P = 0.045), requirement for IBD-related hospitalisation (P = 0.009) and incidence of peripheral arthritis (29.8% vs. 22.0%, P = 0.027). Current smokers with UC demonstrated reduced corticosteroid utilisation (24.1% vs. 37.5%, P = 0.045), yet no reduction in the rates of colectomy (3.4% vs. 6.6%, P = 0.34) or hospital admission (P = 0.25) relative to nonsmokers. Ex-smokers with UC required proportionately greater immunosuppressive (36.2% vs. 26.3%, P = 0.041) and corticosteroid (43.7% vs. 34.5%, P = 0.078) therapies compared with current and never smokers.

CONCLUSIONS

This study confirms the detrimental effects of smoking in CD, yet failed to demonstrate substantial benefit from smoking in UC. These data should encourage all patients with IBD to quit smoking.

Development of three vitrification-based cryopreservation procedures for shoot tips of China's potato

China is now the largest potato producing country worldwide. The establishment of efficient conservation techniques for potato germplasm is a prerequisite for breeding of elite cultivars. Potato viral diseases have been a great threat for sustainable potato production in China. Use of virus-free seed tubers is an effective and practical means to control viral diseases. In the present study, three vitrification-based cryopreservation techniques, i.e. droplet-vitrification, encapsulation-vitrification and vitrification were successfully developed for the first time for China's potato. Cultivar 'Zihuabai' was used to optimize key parameters involved in the three vitrification-based procedures. With the optimized parameters, shoot regrowth percentages of 71%, 76% and 43% were obtained for droplet-vitrification, encapsulation-vitrification and vitrification, respectively. The three protocols developed were further tested with eight China's major cultivars, with average shoot regrowth of 61%, 38% and 28% for droplet-vitrification, encapsulation-vitrification and vitrification, respectively. Successful development of the three cryopreservation procedures using a single cultivar will facilitate a number of comparative studies such as cryo-injury, regrowth pattern, genetic stability and efficiency of virus elimination. Testing these three cryogenic procedures for potato major cultivars representing a wide range of genetic background, will help the establishment of potato cryobanking in China and the production of virus-free plants.

Varying chromosome composition of 56-chromosome wheat x Thinopyrum intermedium partial amphiploids

Thinopyrum intermedium (2n = 42) is a source of many potentially useful genes for wheat improvement. Many partial amphiploids have been produced between Th. intermedium and Triticum aestivum that are fertile and stable. These partial amphiploids all have 56 chromosomes, including seven pairs of chromosomes from Th. intermedium. To explore the genomic composition of these lines, meiotic analysis was conducted on 32 hybrid combinations between eight different partial amphiploids. All but two of the chosen parents were distinguishable on the basis of perenniality, head morphology, and reactions to leaf, stripe, and stem rusts and to barley yellow dwarf virus. Chromosome pairing in the hybrids clearly indicated that all but two of the partial amphiploids differed in their composition of Thinopyrum chromosomes. The differences varied from one to five chromosomes. This confirms molecular evidence that the extra genome of the octoploid partial amphiploids is a variable synthetic genome combining chromosomes of the three Thinopyrum genomes E, J, and X. Though the extra synthetic genomes vary widely between different octoploids, they are nevertheless stable once formed. It is argued that the failure to establish these octoploid amphiploids as a new crop is a consequence of their differing chromosome complements, which makes it impractical to interbreed them.

Effects of heat exposure on muscle oxidation and protein functionalities of pectoralis majors in broilers

This study was conducted to determine the effects of heat stress on pH, lipid peroxidation, protein oxidation, and functionalities of breast meat in broilers. The experimental birds were exposed to 2 temperatures: 24 degrees C (control) and 41 degrees C (heat-stressed) for 0, 1, 2, 3, and 5 h. As compared with control, the pH determinations after slaughter for 30 min and 24 h of chilling, respectively, of the pectoralis major in the heat-stressed groups were significantly lower (P < 0.05). Oxidative stability of i.m. lipid in 3- and 5-h groups (P < 0.01) and protein in 2-, 3-, and 5-h groups (P < 0.01) increased. Protein solubility of pectorilas major decreased after heat exposure. Drip loss and cooking loss were increased in groups from 1 to 5 h of exposure. A reduced strength was noted for myofibrillar protein gels of heat-stressed breasts in exposed groups (P < 0.01); also water-holding capacity of the gels was reduced in treatments of 2, 3, and 5 h (P < 0.01). The results demonstrated that preslaughter exposures to heat reduced the oxidative stability of broiler muscle protein, which might be responsible for decreased protein functionalities such as gelation.

[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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

[Distribution of E- and St-specific RAPD fragments in few genomes of triticeae]

Two E genome--(including Ee and Eb) and two St-genome-specific RAPD markers were successfully cloned. Sequencing data indicated that the four DNA fragments were reported for the first time. Chromosome fluorescent in situ hybridization (FISH) showed that OPD-12(444) (E-specific) was a highly tandem repeat. OPF-03(1296) (Eb-specific), OPB-08(525) (St-specific), and OPN-01(817) (St-specific) were highly dispersed repetitive sequences. The FISH and Southern hybridization of genomic DNA also revealed that all of the four highly repetitive sequences were shared among relatively closer genomes of triticeae. The difference was mainly in the fragment length and the copy number. Whether a genome can amplify a specific sequence via RAPD is mainly dependent on if there are primering sites at both ends of this sequence in the genome. We also discussed the potentiality of these highly repetitive DNA fragments in detection of alien chromatin in wheat and determination of genome constitution of polyploid triticeae species.

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.

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.

Interfacial reactions of cast titanium with mold materials

PURPOSE

Dental casting requires replication of complex shapes with high fidelity. To achieve this objective, the problem of scale formation on titanium dental castings must be overcome. Scaling occurs readily at high temperatures because of the high reactivity of molten titanium with investment materials. The purpose of this study was to examine the effectiveness of using stable oxide coatings on the mold surface to reduce the interfacial reactions.

MATERIALS AND METHODS

A traditional phosphate-bonded dental investment, a commercial titanium investment, and an experimental oxide coating were used for the molds. Pure titanium samples were cast, divested, and prepared for scanning electron microscopic and energy dispersive x-ray spectroscopic analyses.

RESULTS

Layers of 7- to 10-micron-thick scale were formed on titanium castings during reaction with traditional mold materials. Interface reaction was reduced between the molten titanium and the investment material when yttrium oxide or zirconium oxide coatings were applied to the mold before casting.

CONCLUSION

Less titanium-mold interfacial reactions occurred when protective coatings were used as diffusion barriers for titanium casting. Y2O3-coating oxide particles applied without binder were entrapped in the cast titanium surface layer. Further study of a binder system for Y2O3 coating is needed.

Microperoxidases catalytically degrade reactive oxygen species and may be anti-cataract agents

microPx-11, a ferriheme undecapeptide proteolytic degradation product of cytochrome C is shown to be a peroxidase with broad specificity degrading H2O2 and tertiary butyl hydroperoxide. It is also capable of effectively eliminating superoxide and hydroxyl radical. The peroxidase loses activity in the presence of peroxide unless it is stabilized by ascorbate (Asc) or solutions such as aqueous humor or medium 199. While thiol but not disulfides inactivates the microPx-11, it is not inhibited in the presence of the rat lens which has a high GSH content. microPx-11 at concentrations 10 to 50 fold greater than are required to achieve good protective activity exhibits no toxicity based on cell viability, ATP levels and lens transparency after long-term incubations of alpha TN4-1 cells or cultured rat lens. The peroxidase is capable of protecting cultured rat lenses from photochemical stress where H2O2, O2.- and OH. are generated based on transparency, choline transport, epithelial cell viability and protein integrity as indicated by SDS-PAGE of the rat lens protein. In the absence of the peroxidase, extensive epithelial cell death and other degradative changes are observed. The DNA of alpha TN4-1 cells can also be protected from H2O2 induced single strand breaks by the microPx-11. The overall results suggest that a number of cytochrome C proteolytic degradation products are peroxidases which may be effective anti-cataract agents protecting the lens from oxidative stress.

Sectional prosthesis for total maxillectomy patients: a clinical report

Total maxillectomy is a relatively uncommon surgical procedure and usually results in a surgical and prosthetic reconstructive challenge. The goals of prosthetic treatment include separation of oral and nasal cavities, which allows for adequate speech and deglutition, along with restoration of esthetics. Treatment of a patient with total maxillectomy due to verrucous carcinoma was presented in this clinical report. Clinical and laboratory procedures of the prosthetic treatment were described. The sectional prosthesis retained by magnets eliminated long-term use of a nasogastric tube, rehabilitated the patient's speech, and restored proper midfacial esthetic contour.

Refining hollow obturator base using light-activated resin

The disadvantages of an open-type hollow obturator include difficulty in polishing and cleaning of the internal surface, food accumulation in the hollow obturator and inability to obtain support from the superior aspect in the defect area. This article describes and easy time-saving procedure that uses visible light-activated denture base materials as a reline material to close an open type interim obturator. This procedure can be used successfully for both late stage interim obturators and/or for correcting leakage problems for patients who wear definitive obturators.

Oxidation behavior of surface-modified titanium for titanium-ceramic restorations

STATEMENT OF PROBLEM

Titanium-ceramic bonding is an unsolved problem for the current use of titanium-ceramic restorations.

PURPOSE

The purpose of the study was to characterize oxide formation on titanium surfaces at porcelain sintering temperatures and to determine the effect of chromium coating methods on titanium oxide formation.

MATERIAL AND METHODS

Sputter coating and electroplating methods of chromium application were compared and combined.

RESULTS

Porous, weak titanium oxide formation on uncoated samples was demonstrated at porcelain sintering temperatures. Groups with chromium coating as an oxygen diffusion barrier exhibited lower oxidation rates, except samples coated by sputtering alone. Temperature effect was found to have the greatest significance on titanium oxidation rate. The overall lowest oxidation rate was located in the group that had chromium coating by the combined coating method and was oxidized at 750 degrees C.

CONCLUSION

The electroplating method requires further investigation and development so that a uniform chromium layer can be deposited on titanium.

The contribution of GSH peroxidase-1, catalase and GSH to the degradation of H2O2 by the mouse lens

Utilizing cultured lenses from normal and homozygous glutathione peroxidase (GSHPx-1) knockout mice and inhibitors for GSSG Reductase (GSSG Red), 1,3-bis(2-chlorethyl)-1-nitrosourea (BCNU) and catalase (Cat), 3-aminotriazole (3-AT), the ability to degrade H2O2 was examined at two H2O2 concentrations, 300 microM and 80 microM. It was found that GSHPx-1 contributed about 15% to the H2O2 degradation. The Cat contribution was concentration dependent being about 30% at 300 microM H2O2 and approximately 8% to 15% at 80 microM H2O2. GSH loss measured as nonprotein thiol (NP-SH) was shown to be linked to most of the remaining H2O2 degradation accounting for about 54% to 72% of the H2O2 degradation at 300 microM and 80 microM, respectively. However, based on evaluation of the ability of GSH to nonenzymatically degrade H2O2, it can only account for about 36% at 300 microM and 19% at 80 microM H2O2 of the observed lens H2O2 degradation. It is, therefore, concluded that lens GSH must be involved in other reactions either directly or indirectly related to H2O2 degradation.

Effects of attachment clips on occlusal force transmission in removable implant-supported overdentures and cantilevered superstructures

Attachment clips are commonly used to provide retention for removable implant-supported overdentures. In this study, the effects of attachment clips on occlusal force transmission in four implant-supported overdentures with cantilever extensions were investigated using beam theory. Distributions of moments and of forces in overdenture, clips, cantilevered superstructure, and implants were calculated as functions of position, number, and stiffness of attachment clips. Three-, four-, and five-attachment clip configurations were analyzed. Results showed that maximum bending moments and forces in all components are strong functions of position, number, and retention of attachment clips, while the effects of attachment clip stiffness are negligible. Increasing the number of attachment clips from three to five results in a significant decrease of maximum bending moments in the superstructure and implant. For a wide range of attachment clip positioning, the maximum tensile force on the implants is as high as half the applied load. At least one attachment clip for all configurations is also subjected to tensile force, which can cause it to slip out from the superstructure and increase maximum bending moment in the superstructure and implants.

Fusaricide, a new cytotoxic N-hydroxypyridone from Fusarium sp

A new cytotoxic N-hydroxypyridone, fusaricide (1), was isolated from a Fusarium sp. Its structure was solved by X-ray diffraction and spectroscopic analyses.

Characterization of the translocated chromosome using fluorescence in situ hybridization and random amplified polymorphic DNA on two Triticum aestivum-Thinopyrum intermedium translocation lines resistant to wheat streak mosaic or barley yellow dwarf virus

Fluorescence in situ hybridization (FISH) was used to determine the breakpoint of the translocation chromosome in two bread wheat (Triticum aestivum) germplasm lines with Thinopyrum intermedium chromatin carrying resistance to either wheat streak mosaic virus (WSMV) or barley yellow dwarf virus (BYDV). In addition, genome-specific random amplified polymorphic DNA (RAPD) markers were used to ascertain the genomic sources of the Th. intermedium chromosome carrying the WSMV or BYDV resistance. CI17766, a WSMV-resistant wheat germplasm line derived from induced homoeologous pairing by using the ph1b mutant, had a translocation chromosome composed of the complete 4AL and about 45% of proximal 4AS from wheat, and the entire 4ES of Th. intermedium. The BYDV-resistant translocation line, TC14, derived from tissue culture, had a very short distal segment of 7StL from Th. intermedium terminally attached to 56% of the proximal 7DL. These observations indicate that translocations in these wheat germplasm lines did not involve centromeric breaks and fusion but were a result of homoeologous chromosomes recombination.

Titanium for prosthodontic applications: a review of the literature

Titanium has become a material of great interest in prosthodontics in recent years. A growing trend involves the use of titanium as an economical and biocompatible replacement for existing alloys for fixed and removable prostheses. However, long-term results of titanium casting, joining, and porcelain bonding have to be evaluated before this wonder metal can be used routinely in clinical dentistry. This article describes the development and properties of titanium and reviews the literature related to the use of titanium in prosthodontics, for the purpose of evaluating the present status and future trends in its use.

In vitro backscattering from implant materials during radiotherapy

It is a certainty that many of the patients now receiving dental implants will one day require radiotherapy if they have head and neck cancer. The purpose of this study was to examine the dose enhancement form backscattered radiation at implant/bone interfaces irradiated with high-energy 6 MV and 10 MV x-rays. Three commonly used implant materials, pure titanium, Ti-6A1-4V alloy, and a high gold content implant material of various thicknesses, were used to measure the dose enhancement caused by backscattered radiation. The relative ionization charges at implant/bone interfaces were measured at distances of 0, 1, 2, and 3 mm away from the implant material by insertion of 0, 1, 2, and 3 mm thick bone substitute disks between the implant material and an ionization chamber. The results indicated that the highest dose enhancement occurred at a distance of 0 mm from the implant/bone interface for all the materials studied. The Au-Cu-Ag implant material had more average relative dose than pure titanium or Ti-6A1-4V alloy. The backscattered electrons decreased as the thickness of the bone substitute (distance between the implant material and the ionization chamber) increased.

Variation in cellular glutathione peroxidase activity in lens epithelial cells, transgenics and knockouts does not significantly change the response to H2O2 stress

This investigation examines the contribution of glutathione peroxidase (GSHPx-1) in degrading H2O2 in lens preparations. Rabbit (N/N1003A) and normal and GSHPx-1 transfected mouse (alpha TN4-1) lens epithelial cell lines and normal and GSHPx-1 transgenic and knockout mouse lenses were utilized. GSHPx-1 activity in the cell lines was increased from two-fold to about four-fold, in the lenses from transgenics more than four-fold and the lenses from knockouts had less than 3% of normal GSHPx-1 activity. The transgenic and knockout mice as well as their lenses appeared normal for up to 3 to 4 months, the longest period of observation. The preparations were subjected to oxidative stress by placing them either in a medium containing 120 or 300 microM H2O2 or utilizing photochemical stress where the H2O2 levels normally rise to about 100 microM over a few hours in the presence of a normal lens. With all preparations, it was found that either markedly increasing or eliminating GSHPx-1 activity had only a small effect on the system's ability to metabolize H2O2, 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), an inhibitor of GSSG reductase (GSSG Red) and 3-aminotriazole (3-AT), an inhibitor of catalase, also had little effect. However, the addition of both inhibitors caused a marked decrease in H2O2 degradation. Examination of the distribution of GSHPx-1 in the lens indicated that the activity per milligram of protein was evenly distributed between the epithelium and the remainder of the lens in the normal lens and was about 1.7-fold greater in the epithelium of transgenic lenses than in the remainder of the lens. Surprisingly, the distribution of GSSG Red was quite different with eight- to ten-fold more activity in the epithelium. Catalase was also found to be concentrated in the epithelium. With H2O2 exposure, a rapid loss of non-protein thiol (NP-thiol) was found in cell cultures and in the epithelia of cultured lenses. However, the remainder of the lens showed little change in NP-thiol. The variation of GSHPx-1 activity did not influence the NP-thiol changes which occurred more rapidly and to a greater extent in the presence of BCNU. The addition of BCNU also caused a decrease in total lens NP-thiol. Examination of thymidine incorporation and choline transport, indicators of nuclear and membrane function, also reflects the H2O2 degradation data, showing little difference in the degree to which H2O2 effects these parameters in lenses from normal and transgenic animals. Catalase activity is four- to six-fold greater than GSHPX-1 activity in the alpha TN4-1 cell lines, about three-fold lower in the rabbit cell line and, remarkably, about 18-fold lower than the peroxidase in the normal mouse lens. In spite of such observations, the consistent overall conclusion is that GSHPx-1 and catalase function together but when GSHPx-1 is knocked out or GSSG Red is inhibited, catalase is able to protect the system from H2O2 stress. Indeed, the young mouse does not appear to require GSH Px-1 for normal function.

[RAPD markers for wheat chromosomes in Langdon disomic substitution lines]

Optimal conditions were developed for a random amplified polymorphio DNA (RAPD) assay of hexaploid bread wheat and tetraploid durum wheat. AmpliTaq Stoffcl fragment was found to be better than Taq DNA polymerase in generating RAPDs. Studies on chromosome specific RAPD markers of the A- and B- and D-genome were performed using the complete set of Langdon disomic substitution lines and the parental lines (Langdon and Chinese Spring) as templete. Seven out of twelve arbitrary primers (all Operon 10-mer sequences) yielded 13 products that could be assigned to 1.0 chromosomes of A- and B- and D-genome, five of 13 markers for A-genome (2A: J6a and J11b; 3A: D11b; 6A: J17; 7A: J15a), seven for B-genome (1B: J11c; 2B: D5, D11c and J18) and one for D-genome (1D: J11a). Using Chinese Spring ditelosomic lines, four RAPD markers were further mapped to a specific chromosome arm (i.e., J11b-2AL, J17-6AL, D11c-2BL, and J11a-1DL). This study demonstrates that reproduoible RAPID markers can be generated and assigned to wheat chromosomes except 4AL, using Langdon disomic substitution lines and Chinese Spring euploid and aneuploids as malerids.

Variations of two repetitive DNA sequences in several Triticeae genomes revealed by polymerase chain reaction and sequencing

Genomes of Triticeae were analyzed using PCR with synthesized primers that were based on two published repetitive DNA sequences, pLeUCD2 (pLe2) and 1-E6hcII-1 (L02368),which were originally isolated from Thinopyrum elongatum. The various genomes produced a 2240 bp PCR product having high homology with the repetitive DNA pLe2. The PCR fragments produced from different genomes differed mainly in amplification quantity and in base composition at 89 variable sites. On the other hand, amplification products from the primer set for L02368 were of different sizes and nucleotide sequences. These results show that the two repetitive DNA sequences have different evolutionary significance. ple2 is present in all genomes tested, although differences in copy number and nucleotide sequence are notable. L02368 is more genome specific, i.e., fewer genomes possess this family of repetitive sequences. It was concluded that the repetitive sequence pLe2 family is an ancient one that existed in progenitor genome prior to divergence of annual and perennial genomes. In contrast, sequences similar to L02368 have only evolved following genome divergence.

Standard Giemsa C-banded karyotype of Russian wildrye (Psathyrostachys juncea) and its use in identification of a deletion-translocation heterozygote

Ten accessions of Russian wildrye, Psathyrostachys juncea (Fisch.) Nevski (2n = 2x = 14; NsNs), collected from different geographical regions were analyzed using the C-banding technique. C-banding pattern polymorphisms were observed at all levels, i.e., within homologous chromosome pairs of the same plant, among different individuals within accessions, between different accessions of the same geographic area, and among accessions of different origins. The seven homologous groups varied in the level of C-banding pattern polymorphism; chromosomes A, B, E, and F were more variable than chromosomes C, D, and G. The polymorphisms did not hamper chromosome identification in Ps. juncea, because each chromosome pair of the Ns genome had a different basic C-banding pattern and karyotypic character. A standard C-banded karyotype of Ps. juncea is proposed based on the overall karyotypes and C-bands in the 10 accessions. The C-bands on the Ns-genome chromosomes were designated according to the rules of nomenclature used in wheat. A deletion-translocation heterozygote of Russian wildrye was identified based on the karyotype and C-banding patterns established. The chromosome F pair consisted of a chromosome having the distal segment in the long arm deleted and a translocated chromosome having the distal segment of long arm replaced by the distal segment of the long arm of chromosome E. The chromosome E pair had a normal chromosome E and a translocated chromosome having the short arm and the proximal segment of the long arm of chromosome E and the distal segment of the long arm of chromosome F.

Cytological identification of some trisomics of Russian wildrye (Psathyrostachys juncea)

Russian wildrye, Psathyrostachys juncea (Fisch.) Nevski (2n = 2x = 14; NsNs), is an important forage grass and a potential source of germplasm for cereal crop improvement. Because of genetic heterogeneity as a result of its self-incompatibility, it is difficult to identify trisomics of this diploid species based on morphological characters alone. Putative trisomies (2n = 2x + 1 = 15), derived from open pollination of a triploid plant by pollen grains of diploid plants, were characterized by Giemsa C-banding. Based on both karyotypic criteria and C-banding patterns, four of the seven possible primary trisomics, a double-deletion trisomic, and two tertiary trisomics were identified.

Joining titanium materials with tungsten inert gas welding, laser welding, and infrared brazing

Titanium has a number of desirable properties for dental applications that include low density, excellent biocompatibility, and corrosion resistance. However, joining titanium is one of the practical problems with the use of titanium prostheses. Dissolved oxygen and hydrogen may cause severe embrittlement in titanium materials. Therefore the conventional dental soldering methods that use oxygen flame or air torch are not indicated for joining titanium materials. This study compared laser, tungsten inert gas, and infrared radiation heating methods for joining both pure titanium and Ti-6Al-4V alloy. Original rods that were not subjected to joining procedures were used as a control method. Mechanical tests and microstructure analysis were used to evaluate joined samples. Mechanical tests included Vickers microhardness and uniaxial tensile testing of the strength of the joints and percentage elongation. Two-way analysis of variance and Duncan's multiple range test were used to compare mean values of tensile strength and elongation for significant differences (p < or = 0.05). Tensile rupture occurred in the joint region of all specimens by cohesive failure. Ti-6Al-4V samples exhibited significantly greater tensile strength than pure titanium samples. Samples prepared by the three joining methods had markedly lower tensile elongation than the control titanium and Ti-6Al-4V rods. The changes in microstructure and microhardness were studied in the heat-affected and unaffected zones. Microhardness values increased in the heat-affected zone for all the specimens tested.

The effect of tray material and surface condition on the shear bond strength of impression materials

This study compared the adhesive shear bond strength of three selected impression materials with that of thermoplastic and acrylic resin tray materials as a function of surface preparation. Polyether (Impregum), polyvinylsiloxane (Reprosil), and polysulfide (Permlastic) impression materials were evaluated on smooth, rough, and contaminated tray surfaces. Smooth surface samples were formed against glass and served as the control groups. Experimental groups consisted of samples contaminated with artificial saliva and rough surface samples that were abraded with 110 microns of Al203. A total of 126 samples were subdivided into 18 groups of seven specimens each. Each sample consisted of a 1 inch square, 3 mm thick mass of an impression material sandwiched between the prepared surfaces of a pair of resin plates. Each specimen was tested in a universal testing machine for adhesive shear bond strength. Data were analyzed with three-way analysis of variance and Scheffe's test. The results indicated that the thermoplastic resin material had better adhesive properties than the acrylic resin. For both tray materials mean adhesive shear bond strengths for Impregum and Reprosil were significantly greater than those of Permlastic. Tray surface contaminated with saliva decreased the adhesive shear strength at the tray adhesive impression interface.