The role of mtDNA deletion in the sensitivity to aminoglycoside antibiotic induced deafness]

OBJECTIVE: To establish an animal model of mitochondrial DNA (mtDNA) deletion and investigate the possible role of mtDNA deletion in aminoglycoside antibiotic induced deafness. METHODS: Thirty wistar rats (4 months) were randomly divided into group A and B. Doxorubicin (DOX) was subcutaneously injected at doses of 2 mg/kg twice per week for 3 months in group A and then kanamycin (KM) was intraperitoneally injected 500 mg/kg per day for 10 consecutive days. The treatments of group B were identical to group A, except normal saline was substituted for DOX. The thresholds of auditory brainstem response (ABR) were measured before and after the drug administrations. The inner ear membranous labyrinthine tissue was harvested and mtDNA was amplified to identify 4,834 bp deletion by PCR technique. RESULTS: The elevation of the mean ABR thresholds in group A(67.08 +/- 8.59) dB peSPL was significantly higher than that in group B (12.71 +/- 4.42) dB peSPL after KM administration (P < 0.001). In group A, 9 of the 15 rats demonstrated 4,834 bp mtDNA deletion. However, mtDNA 4,834 bp deletion was negative in group B animals. CONCLUSION: DOX can induce mtDNA deletion in the inner ear tissue of the rat. mtDNA deletion in the inner ear may play an important role in the hypersensitivity to aminoglycoside antibiotic ototoxicity.     

EFFECT OF VL AND VH CONSENSUS SEQUENCE-SPECIFIC PRIMERS ON THE BINDING AND EXPRESSION OF A MINI- MOLECULE ANTIBODY DIRECTED TOWARDS HUMAN GASTRIC CANCER

Objective. To construct ScFv and Fab from murine anti-gastric cancer monoclonal antibody(mAb) 3H11.Methods. At first,3H11 ScFv and Fab were constructed with Ⅴ genes PCR amplified by degenerate primers for FR1 .The bacterial expressed 3H11 Ab fragments showed no antigen binding activity.Then,phage antibody library and random mutated library were constructed from 3H11 hybfidoma cells and panning selection was performed. Again the i-dentification of positive clone was failed. Finally the N-terminal sequences of Ⅴ regions were resumed to 3H11 original sequences by site-directed mutagenesis via PCR.Restdts. Binding activity to gastric cancer cells was detected only from N-terminal sequence corrected 3H11 ScFv and Fab, though the expression of the Ab fragments was not affected. Correction of either VL or VH N-terminal se-quences could partially resume the antigen binding activity. Conclusion. Sequence changes of Ⅴ region N terminal introduced by PCR may seriously affect antigen binding without affecting the expression of antibody.     

Disease type-associated increases of the plasma levels and ligand expression for natural alpha- or beta-galactoside-binding immunoglobulin G subfractions in patients with lung cancer

The presence of natural carbohydrate-binding antibodies may play a role in host defence against malignant cells in addition to elicitation of an immune response by artificial carbohydrate antigens. Human serum contains immunoglobulin G(2) (IgG) fractions with selectivity to alpha- and to beta-galactosides, respectively, irrespective of the type of blood group of the donor. To determine whether these naturally occurring subfractions may have any relevance for tumor disease control, their binding to malignant cells was ascertained by cytofluorimetric assays in vitro with a number of human tumor cell lines of different histogenetic origin. The affinity of cell binding was comparable to that of binding to lactosylated or melibiosylated neoglycoconjugates as model ligands in solid-phase assays and K-D values were found to be in the range of 5-300 nM. Cross-reactivity of the anomer-selective subfractions to the other type of ligand was observed to be rather low. When the IgG contents of plasma samples of patients with diverse types of lung cancer were assessed, the concentrations of both galactoside-binding immunoglobulin G subfractions were significantly increased in association with presence of small cell lung carcinoma and of metastatic lesions to the lung without any marked change in the overall IgG plasma level. Such an apparently general enhancement was seen for patients with adenocarcinoma and included both subfractions with no impact on their percentage in the total IEC content. When detergent extracts of tumor and tumor-free specimens of the same patient were analyzed with the affinity purified antibody subfractions to comparatively determine ligand presentation, increases in sugar-inhibitable binding were especially noted for the tumor tissue of small cell lung carcinomas and apparently tumor-free samples of cases with lung metastasis. Material from other types of lung cancer revealed no significant indication for disease-related alterations with the exception of carcinoids. These data demonstrate that plasma levels and ligand expression for two types of natural galactoside-binding immunoglobulin G fractions can show nonuniform responses in patients within the class of lung cancer. They encourage to deliberately monitor these parameters of the natural carbohydrate-directed antibody fractions in cancer patients with various types of disease to clarify the clinical significance of respective malignancy-associated changes.     

Effect of hepatic cirrhosis on the pharmacokinetics of theophylline in rats

The experimental hepatic cirrhosis was induced either by bile duct ligation (BDL) or by pretreatment with dimethylnitrosamine (DMNA). The pharmacokinetics of theophylline were studied after a single intravenous or a single oral administration. Using the ultrafiltration method, protein-drug binding experiments were also carried out. The bilirubin level was several-fold increased by BDL, but not by DMNA treatment. The albumin content was decreased in both cirrhotic groups. The total clearance (Clt, ml/kg/hr) of theophylline in both hepatic cirrhosis groups significantly decreased and the terminal half-life (t_1/2) in the cirrhotic rats was increased about two-fold after intravenous and oral administration. The volume of distribution at steady state (Vdss, ml/kg) was increased slightly in the cirrhotic groups. Protein binding in BDL (8.67±4.85%) decreased about four-folds, but in DMNA (73.00±9.85%) similar result, was observed as compared with the control. Increased free fraction of theophylline did not increase the volume of distribution in BDL. Therefore decreased total body clearance of theophylline was mainly due to decreased intrinsic clearance of theophylline in the liver. The absolute bioavailability of theophylline in these experiments was between 63.8 and 72.8%(66.1% in BDL, 63.8% in Sham operated and Control, 72.8% in DMNA). These results suggest that in the experimental hepatic cirrhosis model, administration route does not affect the disposition of theophylline.     

Current Status of the VU MFEL Compton X-Ray Program

The Vanderbilt University medical FEL (free electron laser) Compton x-ray program is close to being operational. The FEL modifications necessary for this new capability are near completion. The transport and detection systems for electron and IR beams have been designed, delivered, and tested. We initially expect to produce 108 x-ray photons per second in the 15- to 20-keV region.     

Use of refractometry to identify opioid-containing solutions

The purpose of this laboratory study was to assess the value of refractometry in identifying the contents of a variety of opioid-containing solutions. A hand-held refractometer was used to document the refraction produced by the undiluted contents of alfentanil, fentanyl, morphine, sufentanil ampoules and by solutions of Ringer’s lactate, 0.9% saline, 3.3% dextrose in 0.3% saline, and distilled water. Each opioid was then serially diluted in serial 1:2, 1:4, and 1:8 dilutions in each of these solutions and the refractions of each determined. Based on this information, blinded identification of various diluted opioid solutions was attempted. Refractometer values for undiluted fentanyl and sufentanil were identical with those for distilled water. Those for undiluted alfentanil and morphine were almost identical with each other and with 1:2 and 1:4 dilutions of either drug in Ringer’s lactate or 0.9% saline. We conclude that refractometry is an unreliable screening method to detect tampering with opioid solutions.     

Identification of the central vestibular projections in man: a positron emission tomography activation study

The cerebral representation of space depends on the integration of many different sensory inputs. The vestibular system provides one such input and its dysfunction can cause profound spatial disorientation. Using positron emission tomography (PET), we measured regional cerebral perfusion with various vestibular stimulations to map central vestibular projections and to investigate the cerebral basis of spatial disorientation. We showed that the temporoparietal cortex, the insula, the putamen, and the anterior cingulate cortex are the cerebral projections of the vestibular system in man and that the spatial disorientation caused by unilateral vestibular stimulation is associated with their asymmetric activation.     

上海市50岁及以上人群维生素D水平与握力的关联研究

目的 探讨上海市≥50岁人群维生素D水平与握力的关系。方法 数据来源于WHO全球老龄化与成人健康研究我国上海市2018-2019年数据,采用logistic回归模型分析维生素D水平与握力的关系,进一步按照性别、年龄及乳制品摄入情况进行分层;采用限制性立方样条曲线绘制维生素D水平与低握力的剂量-反应曲线。结果 共4 391人纳入研究,其中男性2 054人（46.8%）;年龄（67.02±8.81）岁;低握力1 421人（32.4%）;维生素D不足及缺乏分别为1 533人（34.9%）和401人（9.1%）。在调整相关混杂因素后,logistic回归分析结果显示,维生素D缺乏的人群发生低握力的风险更高（OR=1.41,95%CI：1.09~1.83）;在男性中,调整相关混杂因素后,维生素D缺乏与低握力发生风险呈显著正相关（OR=1.67,95%CI：1.12~2.50）,而女性中两者之间无关联（OR=1.30,95%CI：0.97~1.74）;在60~69岁及≥80岁年龄组中,调整相关混杂因素后,维生素D缺乏与低握力发生风险呈显著正相关（OR=1.57,95%CI：1.05~2.35;OR=2.40,95%CI：1.08~5.31）,在乳制品摄入<250 ml/d的人群中,调整相关混杂因素后,二者之间呈显著正相关（OR=1.57,95%CI：1.17~2.09）,而在乳制品摄入≥250 ml/d的人群中无明显关联。限制性立方条样图显示,低握力的发生风险可能随维生素D含量的上升而降低,但差异无统计学意义（P>0.05）。结论 维生素D水平与握力存在一定的关系,维生素D缺乏人群出现低握力的风险更高。