P510树脂在氯化体系中用树脂矿浆法回收金的工艺条件试验研究

试验研究了P510树脂对某含金硫精矿焙砂在氯化体系中用树脂矿浆法提金的工艺条件。在最佳试验条件下,金的浸出吸附率可达96％以上。     

Electrochemical fixation techniques. II. Electrochemical dog body fixation. Histological study

BACKGROUND: Cervical lymph node metastasis in differentiated thyroid carcinoma has mostly been found to have little relationship to prognosis. However, some studies report nodal involvement to be an adverse factor, while others have found it to be favorable. We have undertaken a matched-pair analysis of previously untreated patients, with and without ipsilateral neck metastasis, to examine the significance of nodal spread in patients with otherwise equivalent prognostic factors for differentiated thyroid cancer. METHOD: From a database of 931 patients, treated from 1930 to 1980, we used a computer to match patients with confirmed lateral neck metastasis (N1) to those who were stage NO, and had the following identical prognostic factors: no distant metastasis, age (within 4 years), and tumor size, histology, and intrathyroidal extent. When possible, matches were also made for gender, multifocality, and extent of thyroid surgery. Survival and treatment failures were analyzed, with and without stratification for age. RESULTS: We were able to select 100 N1 patients with corresponding NO patients, sharing the major prognostic risk factors as listed. Overall, there was no difference in survival, although N1 patients more often had recurrence. Mortality increased with age. Analysis at high-risk age (45 years and older) showed significantly more recurrences in N1 patients (p = .008). Twenty-year survival in N1 patients over the age of 45 was lower than that of NO patients. On the other hand, under the age of 45, N1 patients had better survival. These differences, however, did not reach statistical significance. CONCLUSION: Nodal involvement in older patients with thyroid cancer increases the risk of recurrence, although no significant difference in survival is observed in relation to age.     

Tooth mobility and resolution of experimental periodontitis. An experimental study in the dog

The aim of the present experiment was to study alterations in the mobility of teeth that occurred during resolution of experimentally induced periodontitis lesions in the dog. 5, 1-year-old, beagle dogs were used in the study. The left and right 4th, 3rd, and 2nd mandibular premolars (4P4, 3P3, 2P2) served as experimental teeth. Periodontal tissue breakdown was initiated by placing plaque-collecting cotton-floss ligatures around the neck of the experimental teeth. The ligatures were replaced to the level of the receding gingival margin 1 x every month. On Day 120, the ligatures were removed and debridement was performed. A groove, parallel to the long axis of the mesial root, was prepared in the mesio-buccal surface of the crowns of 2P and P2. Guided by the groove and with a probing force of 0.5 N, a probe was inserted into the buccal gingival pocket of the mesial root and was attached to the buccal surface. Biopsies including both the mesial and distal root of 2P and P2 and the surrounding hard and soft tissues were harvested. The biopsy procedure was repeated in a similar manner 15 days (i.e. Day 135) and 3 months (i.e. Day 225) after ligature removal in the 4th (4P4) and 3rd (3P3) premolar regions. After fixation, decalcification and sectioning, the biopsy material was exposed to histometric and morphometric measurements. Assessment of the mobility of the experimental teeth was performed on Days 120, 135 and 225 using the Periotest system.(ABSTRACT TRUNCATED AT 250 WORDS)     

Histological, clinical, and digital subtraction radiographic evaluation of repair of periodontal defects resulting from mechanical perforation of the chamber floor using ePTFE membranes

The aim of this study was to test the hypothesis that a biocompatible membrane, when placed between the gingiva and cortical bone in teeth with periodontal defects that occurred following mechanical endodontic perforation, would facilitate greater regeneration than in control sites not treated with guided tissue regeneration. One beagle dog with a healthy periodontium was used in the study. The maxillary right first and second molars and the mandibular left first and second molars acted as the experimental group in which furcation perforations were treated by guided tissue regeneration. The maxillary left and mandibular right first and second molars served as the controls in which furcation perforation lesions were only treated by open flap debridement. Clinical, histological, and standardized radiographic evaluation showed significant differences between the test and control groups. In addition, digital subtraction radiography revealed a gain in alveolar bone height and increased density at all experimental sites, and a loss at all control sites. Histological evaluation showed extensive regeneration of both alveolar bone and connective tissue at experimental sites, but none at control sites. The results of this study suggest that the use of guided tissue regeneration in furcation lesions produced by endodontic perforations will result in significant new bone and connective tissue attachment.     

Chronic double-level cauda equina compression. An experimental study on the dog cauda equina with analyses of nerve conduction velocity

STUDY DESIGN: Nerve conduction velocity was studied in the dog cauda equina subjected to chronic double-level compression. OBJECTIVES: To analyze the effects of chronic double-level cauda equina compression. SUMMARY OF BACKGROUND DATA: Double-level cauda equina compression produces more symptoms in patients and more changes in acute experimental set-ups than does single-level compression. However, there have been no controlled, experimental studies on chronic double-level compression. METHODS: A total of 20 dogs were anesthetized. Two balloons were placed under the lamina of the seventh lumbar vertebra and the first sacral vertebra, respectively. One week (10 mm Hg, n = 5; 0 mm Hg, n = 5) and 1 month (10 mm Hg, n = 5; 0 mm Hg, n = 5) after inflation with a viscous substance, nerve conduction velocity was studied by local electrical stimulation and recording of muscle action potentials in the tail muscles. RESULTS: Nerve conduction velocity was determined over the cranial balloon, the caudal balloon, and both balloons. The data were similar for all three recordings. After 1 week there was a significant reduction in nerve conduction velocity induced by 10 mm Hg, compared with that induced by 0 mm Hg, which showed normal conditions. However, after 1 month this initial reduction in nerve conduction velocity had recovered partially. The reduction was similar to that described for single-level compression in a previous study in which the same compression model was used. CONCLUSIONS: Unlike the acute situation, chronic double-level compression does not induce more changes than single-level compression after 1 week, although the recovery after 1 month of compression is less complete after double-level compression. This less complete recovery may be a result of an adaptation of the nerve tissue and the vascularization of the cauda equina nerve roots to the applied pressure.     

The effect of levamisole on experimental gingivitis in the beagle dog

The effect of Levamisole on gingivitis development was studied in three beagle dogs. Plaque accumulation was first allowed on one side of the jaws whereas the other side was subjected to careful tooth cleaning procedures. After 2 weeks' experimental gingivitis the dogs were given Levamisole and plaque accumulation was permitted on the other side of the jaws for another two weeks. The following parameters were investigated in the two gingivitis experiments: Plaque and Gingival Indices, Gingival Exudate measurements and histologic measurements. The biopsies were prepared both for light and electron microscopy. The clinical parameters did not show any differences between the two gingivitis experiments. The biopsies, however, demonstrated a larger area of infiltrated connective tissue and an increased number of leukocytes in the junctional epithelium in Levamisole-treated compared to normal animals.     

Left ventricular diastolic chamber stiffness and intramyocardial coronary capacitance in isolated dog hearts

BACKGROUND: Because the myocardium is perfused primarily during diastole, changes in diastolic properties of the left ventricle (LV) should influence the intramyocardial circulation. METHODS AND RESULTS: We examined the influence of LV diastolic properties on the magnitude and localization of intramyocardial coronary capacitance by analyzing the coronary pressure-venous flow relation in isolated, isovolumic dog heart preparations. After sudden occlusion of the left coronary artery during a long diastole, we measured precapacitance and postcapacitance resistances (RPRE and RPOST) and calculated intramyocardial coronary capacitance (CIM) from RPOST and the time constant of the coronary venous flow decay. Using this method, we characterized the effects of coronary vasodilation, LV diastolic volume, and LV diastolic chamber stiffness on the coronary circulation. The magnitude of CIM increased from 0.09 +/- 0.01 to 0.24 +/- 0.20 mL.mm Hg-1 x 100 g-1 (P < .01) after adenosine-induced vasodilation, whereas both RPOST and RPRE decreased significantly. The ratio of RPOST to RPRE+RPOST decreased from 0.35 +/- 0.02 to 0.23 +/- 0.02 (P < .01), suggesting redistribution of CIM to the distal portion of the coronary vascular tree. An increase in LV volume and wall stress was imposed to increase LV diastolic pressure from 2 +/- 0.1 to 25 +/- 1 mm Hg: this increased RPOST significantly but not RPRE and decreased the magnitude of CIM. The resistance ratio did not change significantly. Increased LV diastolic chamber stiffness induced by hypoxic perfusion (isovolumic LV diastolic pressure increased from 11 +/- 1 to 28 +/- 1 mm Hg) raised RPOST and decreased the magnitude of CIM from 0.32 +/- 0.12 to 0.17 +/- 0.04 mL.mm Hg-1 x 100 g-1 (P < .05). The resistance ratio increased significantly from 0.21 +/- 0.05 to 0.33 +/- 0.05 with increased LV diastolic chamber stiffness. Adjustment of LV diastolic volume to lower diastolic pressure to 10 +/- 1 mm Hg did not alter these changes significantly, suggesting that an intrinsic increase in myocardial stiffness played a major role in these changes. CONCLUSIONS: Extravascular compression by raised LV diastolic volume and/or increased LV diastolic chamber stiffness acted mainly on coronary vessels that determine intramyocardial capacitance and postcapacitance resistance.     

The effect of acetazolamide on the movement of sodium into the posterior chamber of the dog eye

The rate of appearance (entry) of 22Na into the posterior chamber of the eye was determined in eight dogs under control conditions and again after pretreatment with acetazolamide, 50 mg/kg i.v. In comparison with the paired controls, pretreatment with acetazolamide decreased the average rate of entry of 22Na by 29% during the first 3 minutes after the intravenous administration of a tracer dose of the isotope. In separate experiments, the volumes of the chambers of the dog eye and the rate of aqueous humor formation were determined for the purpose of calculating nascent fluid ion concentrations. Comparisons of sodium data with the previously reported anion data are made. Results support the suggestion that reduction of intraocular pressure caused by acetazolamide is partially, if not wholly, the result of the action of the drug to reduce the secretion of aqueous humor.     

Biochemical changes in cytoplasmic membranes in dog liver during experimental viral hepatitis

The composition of cytoplasmic membranes isolated from livers of dogs infected with virus of infectious hepatitis of carnivora (IHC) was studied. Inoculation with IHC virus was found not to cause any marked changes in the contents of proteins, lipids and nucleic acids of the membranes under study, but considerable differences in the composition of membrane proteins, lipids and fatty acids of virus-affected cells were demonstrated. The experimental data suggest that the virus infection exerts a considerable effect on the protein-lipid complex of the cytoplasmic membranes of the cell.     

Histological study of mechanisms of adaptive cytoprotection on ethanol-induced mucosal damage in rat stomachs

Adaptive cytoprotection in the gastric mucosa could be induced by exposure to low concentrations of noxious agents. However, experimental results reported so far were based on macroscopic studies. We aimed to investigate the phenomenon of gastric adaptive cytoprotection of mild irritants and its correlation with intramucosal mucus at the histological level. It was found that histological damage induced by ethanol had a negative correlation with the length of the mucus-secreting layer in the gastric mucosa. Mild irritants such as 20% ethanol and 5% NaCl preserved the 100% ethanol-induced intramucosal mucus depletion, but only the former agent demonstrated a cytoprotective effect against the histological damage, indicating that preservation of intramucosal mucus may not necessarily play a permissive role in adaptive cytoprotection. The capsaicin-sensitive sensory afferent neurons, sensory chemoreceptors, muscarinic receptors, alpha2-adrenoceptors and peripheral dopamine D2-receptors were found to be the components of the autonomic nervous system involved in the cytoprotective processes of 20% ethanol. Endogenous mediators including nitric oxide, prostaglandins, and possibly nonprotein sulfhydryl compounds also seemed to participate in such protection. Nevertheless, 0.3 M HCl did not show any effect either on mucosal damage or depletion of intramucosal mucus induced by absolute ethanol. These findings suggest that only 20% ethanol shows histological cytoprotection, which would involve various components of the autonomic nervous system and endogenous mediators. Furthermore, this investigation also implies a new perspective: that in order to study a true adaptive cytoprotection, histological examination of the gastric mucosa should be performed.     

Application of microdialysis for pharmacokinetic study in rabbit anterior chamber

We evaluated a microdialysis technique for analyzing the pharmacokinetics of instilled or orally administered ofloxacin in the anterior chamber of pigmented rabbits. A microdialysis probe was inserted into the anterior chamber and was perfused (2 microliters/min) with Ringer solution using a microinjection pump. Two hours later, 20 microliters of 0.15 and 0.3% ofloxacin was instilled into an eye, or 20 mg/kg of the drug was administered into the stomach through an intubated catheter. Dialysate was then collected every 15 or 20 min for 6 (instillation) or 8 (oral administration) hours. Ofloxacin concentration in dialysates was determined with a HPLC-spectrofluorometry system. Ofloxacin levels in dialysates increased after the instillation in a dose-related manner, reached a maximum at 30 and 45 min, and then decreased gradually with t1/2 of 136 and 114 min after the 0.15% and 0.3% instillation, respectively. After oral administration, ofloxacin levels in dialysates reached a maximum at 120 min and decreased with t1/2 of 175 min. These data suggest the usefulness of microdialysis for pharmacokinetic studies in the anterior chamber, since continuous and stable data can be obtained from each animal.     

水隔离浆体泵水击问题的研究与解决措施

论述了水隔离体泵输送系统产生水击的原因及危害，并从理论上分析研究了浆体输送系统管道中压力波的传播速度，时间及压力增值，通过理论计算给出了水击问题的解决措施。     

A PET study on cortical and subcortical control of pelvic floor musculature in women

The possibility of hepatitis B virus (HBV) infection in HBsAg-negative patients has been shown. However, an "inapparent" coinfection by HBV in hepatitis C virus (HCV)-positive patients generally is not taken into account in clinical practice. Mechanisms responsible for resistance to interferon (IFN) have not been completely clarified. The aim of this study was to investigate whether an "inapparent" coinfection by HBV in anti-HCV-positive chronic liver disease patients may influence IFN response. Fourteen anti-HCV positive, HBsAg-negative but serum HBV DNA-positive patients by PCR and 111 anti-HCV-positive, HBsAg-negative and HBV DNA (PCR)-negative patients with chronic hepatitis were treated with 3 MU of recombinant alpha-2a IFN 3 times weekly for 12 months. Serum HBV DNA and HCV RNA were determined before treatment, after 6-12 months and in coincidence with ALT flare-up by PCR. HBV PCR was performed using primers specific for the S region of the HBV genome and HCV PCR with primers localised in the 5'NC region of HCV genome. IgM anti-HBc was tested using IMx Core-M Abbott assay. By the end of treatment, ALT values had become normal in 4/14 HBV DNA-positive patients (28%), but all "responders" (4/4) relapsed between 2 and 5 months after therapy. All but one patient were HCV RNA-positive before treatment, 6 were also both HBV DNA and HCV RNA-positive during ALT flare-ups. In 5 patients, only HBV DNA and in 3 patients, only HCV RNA was detected when transaminase values increased. All patients remained HBsAg-negative and anti-HCV-positive. IgM anti-HBc was detected both before treatment and during ALT elevation in 3 patients and only during ALT relapse in 3 others. Of the 111 anti-HCV positive, HBsAg-negative and HBV DNA (PCR)-negative patients with chronic hepatitis, a biochemical response to IFN treatment was observed in 54% of the cases. Relapse of ALT values was observed in 47% of the cases during a follow-up of 1 year after treatment. "Inapparent" HBV/HCV coinfection may be implicated in cases of resistance to IFN treatment. In addition, HBV replication may persist in patients in whom HCV replication was inhibited by IFN treatment. The pathogenic role of HBV in liver disease was confirmed by detection of IgM anti-HBc in some cases; the appearance of these antibodies only after IFN treatment suggests that IFN may exert a selective role in favour of HBV. Further studies will show the effect of different treatment schedules. HBV DNA and/or IgM anti-HBc detection with very sensitive methods may be important both as a prognostic factor and as a tool for better understanding interviral relationships and mechanisms involved in multiple hepatitis virus infections.     

Histological study on crude drugs pai-wei, pai-chein and indigenous species of Cynanchum in Taiwan

The botanical origins of Cynanchum species (Cynanchum spp.) on the Taiwan market have been established by histological studies in the present paper. The results showed that the Chinese crude drug Pai-wei on the Taiwan market was derived from the dried roots of Cynanchum atratum Bunge; that of Pai-chein was derived from the dried roots of C. stauntonii (Decne.) Hand.-Mazz; and the Wanling-shu used locally in Taiwan was derived from the dried roots of C. taiwanianum Yamazaki.     

An experimental study on interaction of nodular cast iron with CRT glass

In the manufacturing of glass components of cathode ray tubes, ductile cast iron rings are commonly used as an integral part of the mold assembly. The thermo-chemical interaction of molten glass with cast iron therefore becomes critical as far as the mold life and productivity is concerned. In this perspective, the present study is carried out to understand and analyze the chemical interaction of cast iron when immersed in molten glass. The experiments were conducted in the temperature range of 700°C to 900°C for selected time duration of 0 to 100 hours. The important observations include the formation of diffusion zone at the glass metal interface. SEM-EDS analysis revealed that diffusion of silicon and lead from glass takes place in diffusion zone with varying degree, depending on temperature and time. The hardness variation across the interface correlates well with the measured compositional changes. The plausible reasons for the measured hardness increase in the diffusion zone are also discussed.