A comparison of the thresholding strategies of micro-CT for periodontal bone loss: a pilot study

Objectives:

Micro-CT provides three-dimensional details and has been widely used for biomedical assessments. This study aimed to determine the most appropriate threshold method for quantitatively assessing the dynamics of periodontal destruction.

Methods:

Inflammation was induced by submerging a silk ligature in the sulcus of the maxillary second molars of rats, and the animals were killed prior to ligature placement and after 7 and 21 days. The maxillae were examined for the bone resorptive activities by micro-CT, histology and tartrate-resistant acid phosphatase staining. The imaging threshold was determined by CT phantom, global and local algorithms. A bone fraction measurement from each threshold-determining technique was compared with histomorphometry. The reliability and reproducibility were examined by the intraclass correlation coefficient (ICC) and the coefficient of variation.

Results:

Significant reduction of inflammatory infiltration (p < 0.01) and active osteoclastic resorption (p < 0.05) from Day 7 to Day 21 were noted. High inter- and intraexaminer agreement were demonstrated in both histomorphometric and micro-CT assessments (ICC > 0.98). The algorithm-based technique demonstrated stronger correlation to histomorphometry than phantom-based thresholds, and the highest agreement was presented by the local algorithm (ICC > 0.96). This, however, was considerably computationally expensive.

Conclusions:

The local threshold-determining algorithm is suggested for examining inflammation-induced bone loss. Further investigation will be aimed at enhancing computational efficiency.     

Synthesis of cobalamin coenzymes by human lymphocytes in vitro and the effect of folates and metabolic inhibitors

The uptake of 57Co-cyanocobalamin (CN-Cbl) and its conversion to 5- deoxyadenosylcobalamin (Ado-Cbl), methylcobalamin (Me-Cbl), and hydroxocobalamin (OH-Cbl) has been studied in phytohemagglutinin (PHA)- transformed lymphocytes from normal subjects and patients with patients with pernicious anemia. Uptake and conversion were much greater by PHA- stimulated lymphocytes than by mature non-transformed lymphocytes. In normal cells, uptake of 57Co-CN-Cbl and synthesis of the cobalamin coenzymes were approximately linear between 3 and 48 hr incubation. Ado- Cbl was the major cobalamin formed, and after 72 hr the cells contained about twice as much Ado-Cbl as Me-Cbl. Uptake by lymphocytes from patients with untreated pernicious anemia (PA) was greater than that by normal lymphocytes, but the proportions of Ado-Cbl and Me-Cbl synthesized by each were similar. Folic acid and methyltetrahydrofolate enhanced synthesis of Me-Cbl both in normal and in PA cells, while methotrexate and 5-fluorouracil depressed it. This depression was overcome by 5-formyltetrahydrofolate, suggesting that an uninterrupted folate cycle may play an important role in Me-Cbl synthesis.     

镁及镁合金在仿生体液中的腐蚀降解行为

目的:观察纯镁及镁锌系列合金在仿生体液中的腐蚀行为,分析其是否具有生物临床应用价值。方法:实验采用纯镁(99.9%)、镁锌锆(ZK60)、镁锌锆钇(Mg-5.6Zn-0.55Zr-0.9Y)3种合金材料,将试样分别放入仿生溶液中浸泡10d,仿生溶液恒温(37.0±0.5)℃。用BP211D电子天平测量了试样在仿生体液中的腐蚀失重,用LK98BII型电化学系统测量了试样在仿生体液中腐蚀时的Tafel曲线,同时观察仿生溶液pH值的变化结果:①在仿生体液中242h后,纯镁、镁锌锆和镁锌锆钇损失量分别为0.9%,3.1%和抗蚀性1.7%。②在实验条件下,腐蚀电流密度纯镁为2.03mA/mm2,镁锌锆为10.14mA/mm2,镁锌锆钇为4.42mA/mm2。③随着镁合金在仿生体液中浸泡时间延长,溶液的pH值增高,电势也随着pH值的增加而减小,镁及镁合金的腐蚀速率会降低。结论:①合金中杂质元素越少,耐腐蚀性能越好,选择纯镁或含Y的镁合金作为镁基生物材料的耐蚀性较好。②在镁锌合金中添加钇后其耐体液腐蚀性能得到了改善。     

International variation in GP treatment strategies for subclinical hypothyroidism in older adults: a case-based survey

Background

There is limited evidence about the impact of treatment for subclinical hypothyroidism, especially among older people.

Aim

To investigate the variation in GP treatment strategies for older patients with subclinical hypothyroidism depending on country and patient characteristics.

Design and setting

Case-based survey of GPs in the Netherlands, Germany, England, Ireland, Switzerland, and New Zealand.

Method

The treatment strategy of GPs (treatment yes/no, starting-dose thyroxine) was assessed for eight cases presenting a woman with subclinical hypothyroidism. The cases differed in the patient characteristics of age (70 versus 85 years), vitality status (vital versus vulnerable), and thyroid-stimulating hormone (TSH) concentration (6 versus 15 mU/L).

Results

A total of 526 GPs participated (the Netherlands n = 129, Germany n = 61, England n = 22, Ireland n = 21, Switzerland n = 262, New Zealand n = 31; overall response 19%). Across countries, differences in treatment strategy were observed. GPs from the Netherlands (mean treatment percentage 34%), England (40%), and New Zealand (39%) were less inclined to start treatment than GPs in Germany (73%), Ireland (62%), and Switzerland (52%) (P = 0.05). Overall, GPs were less inclined to start treatment in 85-year-old than in 70-year-old females (pooled odds ratio [OR] 0.74 [95% confidence interval [CI] = 0.63 to 0.87]). Females with a TSH of 15 mU/L were more likely to get treated than those with a TSH of 6 mU/L (pooled OR 9.49 [95% CI = 5.81 to 15.5]).

Conclusion

GP treatment strategies of older people with subclinical hypothyroidism vary largely by country and patient characteristics. This variation underlines the need for a new generation of international guidelines based on the outcomes of randomised clinical trials set within primary care.     

Genetic control of the circulating concentration of transforming growth factor type beta1

The concentration of transforming growth factor beta (TGF-beta) in plasma has been correlated with the development of several diseases, including atherosclerosis and certain forms of cancer. However, the mechanisms that control the concentration of TGF-beta in plasma are poorly understood. In a study of 170 pairs of female twins (average age 57.7 years) we show that the concentration of active plus acid- activatable latent TGF-beta1 [(a+l) TGF-beta therefore is predominantly under genetic control (heritability estimate 0.54). Single strand conformation polymorphism (SSCP) mapping of the TGF-beta1 gene promoter has identified two single base substitution polymorphisms. The two polymorphisms (G-->A at position -800 bp and C-->T at position -509 bp) are in linkage disequilibrium (correlation coefficient Delta = 0.215, P < 0.01). The C-509T polymorphism is significantly associated with the plasma concentration of (a+l) TGF-beta1, explaining 8.2% of the additive genetic variance of (a+l) TGF-beta1 concentration. It is therefore possible that predisposition to atherosclerosis, bone diseases or various forms of cancer may be correlated with the presence of particular alleles at the TGFB1 locus.      

Oxidant-antioxidant status in acute and chronic renal failure

Present study was carried out to evaluate oxidant-antioxidant status and effect of hemodialysis in acute and chronic renal failure. Serum MDA levels increased while serum SOD found decreased significantly. This study indicates the existence and increased production of an oxidizing stress resulting from hemodialysis and disturbance in antioxidant enzyme system.     

The effect of benzamide riboside on the VX2 model of liver cancer in rabbits

PURPOSE: Benzamide riboside (BR) causes apoptosis in multiple tumor cell lines by its inhibition of guanylate biosynthesis. The purpose of this study was to determine the feasibility of the use of BR as a therapeutic agent for hepatic artery infusional cancer therapy in a rabbit VX2 papilloma tumor model. MATERIALS AND METHODS: VX2 tumor was implanted into the left lobe of the liver of each of 14 New Zealand White rabbits and allowed to grow for 19 days +/- 3. The proper hepatic artery was selected with a 3-F catheter via right femoral cutdown. The animals were treated with one infusion of 0.9% saline solution (n = 2), 1 mg/kg BR (n = 4), 5 mg/kg BR (n = 4), or 10 mg/kg BR (n = 4). One animal treated with 5 mg/kg BR did not develop tumor. Livers were explanted after 24 hours and sectioned through the tumor. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining was performed on the slides and they were imaged at a magnification of 40 to detect apoptotic cells. Four random fields were obtained from each slide and the percentage of apoptotic cells was calculated by dividing the number of TUNEL-positive cells by the total number of cells. Sections of liver not involved with tumor were seen in five animals: two that received 1 mg/kg BR, one that received 5 mg/kg, and two that received 10 mg/kg. RESULTS: The mean tumor apoptosis rates were 1.3% with saline solution treatment, 44.8% with 1 mg/kg BR, 52.7% with 5 mg/kg BR, and 70.7% with 10 mg/kg BR. The mean tumor apoptosis in treated animals was significantly greater than in control animals (P = .003) and mean tumor apoptosis was significantly greater with 10 mg/kg BR than with 1 mg/kg BR (P = .03). There were no apoptotic cells in normal liver treated with 1 mg/kg BR or 10 mg/kg BR. The animal that received 5 mg/kg BR exhibited 10.5% apoptotic cells in the field examined (eight of 76 cells). In the animal treated with 5 mg/kg BR but in which tumor did not grow, only one of 76 cells (0.65%) was apoptotic in the area of the injection scar. CONCLUSION: BR induces apoptosis in VX2 tumor in the rabbit model with minimal apoptosis in normal liver.     

Difficulty in dislodging in vivo fixed radiostrontium

Many trials based on the basic phenomena of isotopic dilution, adsorption, ion exchange, chelation, etc., have been attempted for the decorporation of radiostrontium, particularly Sr, after its entry in the in vivo system. We have recently demonstrated a non-isotopic carrier effect of some common calcium salts (calcium = 9 mg mL) to reduce the whole body retention of radiostrontium, if administered within 2 h after radiostrontium exposure and furthermore once daily, in rats, supplemented with calcium fortified diet. However, 25-30% of radiostrontium (compared to 50-60% in untreated animals) was still found to be retained in the animal even after 2 wk of treatment. Trial of some simple interventional measures, which would not adversely affect the animal metabolism, like pyrophosphate and magnesium sulfate, sodium citrate, chitin (a bio-absorbent), crown ether (a metal-chelator), and ammonium chloride, was therefore attempted to dislodge this remaining radiostrontium by switching over these animals to normal diet and subjecting them to different lines of treatment with these simple interventions through diet and drinking water separately for a further 4 wk. However, this remaining portion of radiostrontium is fixed in the bone and is difficult to dislodge.