Pulpal reactions to glutaraldehyde and paraformaldehyde pulpotomy dressings in monkey primary teeth

Abstract Pulpotomy was performed in primary teeth of 4 vervet monkeys to compare the effect of an experimental dressing containing glutaraldehyde (GL) to a similar formula with paraformaldehyde (PF). Forty teeth were examined histologically 2 weeks to 5 months post-operatively. In the PF group, calcifications were more frequently observed and the central core of tissue in the root canal was heavily laden with debris. Pathologic apical resorption and lesions were more frequent. The pulp in the apical third of the root canal was usually uninflamed in the GL group and peripheral calcifications were seldom observed in it. Reaction to GL seemed, therefore, more favorable clinically. Defects were not observed in the permanent teeth that erupted following shedding or extraction of the experimental primary ones of either group.     

Fluorescence spectroscopy monitoring of the conformational restraint of formaldehyde- and glutaraldehyde- treated infectious bursal disease virus proteins

Interaction of native proteinaceous antigens during the recognition and the effector phases of an immune response leads to antigenic conformational modifications which may elicit additional specific immune response. Protein cross-linking and conformation restraining formaldehyde and glutaraldehyde have been extensively used in vaccine preparation, but the relative efficiencies of conformational restraint at concentrations similar to those used in vaccine preparation have not been investigated. We addressed this issue by comparing the extent of conformational restraint of virus proteins in formaldehyde- and glutaraldehyde-treated virus preparations by monitoring the fluorescence intensities (I₃₂₀) of infectious bursal disease virus preparations (IBDV) and those of untreated virus during thermal denaturation. Formaldehyde was found to cause no detectable conformational restraint at 0.01% and only very weak restraint at 1%, while glutaraldehyde caused very strong conformational restraint at 0.01%. It is proposed how conformational restraint of proteinaceous antigens may alter ensuing immunity.     

组织工程血管瓣膜研究中的染料介导光氧化固定技术

心血管外科中应用的异种生物组织一般都要进行固定，最为成熟和广泛的方法是戊二醛固定，但是其存在很多的缺点，具有生物毒性，容易钙化，耐久性差，促使人们努力寻找一种更好的替代方法，其中染料介导的光氧化固定被认为是一种很有前途的方法。染料介导光氧化固定方法比较简单，把需要固定的组织浸泡于含有光敏染料的缓冲液中光照。染料介导光氧化固定方法相比戊二醛固定，具有生物毒性低，不易钙化的优点，与戊二醛固定一样，具有生物稳定性高、免疫原性低的特点。从目前的研究看，染料介导光氧化固定技术是一种很有前途的生物组织固定方法。     

Occupational asthma and rhinitis due to glutaraldehyde: changes in nasal lavage fluid after specific inhalatory challenge test

BACKGROUNDd: Glutaraldehyde (GA) is a known respiratory sensitizers, and some studies have reported occupational asthma in exposed workers. Specific changes in nasal lavage fluid (NLF) induced by high-molecular-weight allergen provocation in sensitized subjects were described previously. The purpose of this study was to evaluate the changes in cytogram, protein content, eosinophil cationic protein (ECP), and mast-cell tryptase concentrations in NLF after GA inhalation challenge in patients with a positive history of GA-induced asthma and late or dual asthmatic response due to exposure to low-level GA. METHODS: A single-blind, placebo-controlled study was performed on 11 health workers with occupational asthma and rhinitis due to GA. The control groups comprised 10 atopic subjects with perennial asthma and rhinitis and 10 healthy ones. A "nasal pool" technique was used to evaluate the examined parameters in nasal washings before and 30 min, 4 h, and 24 h after the inhalatory provocation with GA and placebo. RESULTS: There was a significant increase in eosinophil number and percentage, and albumin, ECP, and tryptase concentrations in NLF from patients with occupational asthma and rhinitis when compared to controls. CONCLUSIONS: The results indicate the immunologic mechanism of GA-induced asthma and the applicability of the "nasal pool" technique as the diagnostic procedure in GA-induced airway allergy.     

The use of meniscal fibrocartilage as a surface arthroplasty to effect the repair of osteochondral defects: an experimental study

Meniscal fibrocartilage autografts, homografts, glutaraldehyde treated homografts and glutaraldehyde treated xenografts were inserted into articular defects in the rabbit patello-femoral groove. They appeared capable of restoring a functional articular surface. Considerable variation in the type of bond formed between the host and graft occurred but no evidence of rejection was observed. This tissue would appear to offer potential for restoring localized articular osteochondral defects.     

Parameterization of red blood cell elongation index – shear stress curves obtained by ektacytometry

Abstract

Measurement of red blood cell (RBC) deformability by ektacytometry yields a set of elongation indexes (EI) measured at various shear stresses (SS) presented as SS-EI curves, or tabulated data. These are useful for detailed analysis, but may not be appropriate when a simple comparison of a global parameter between groups is required. Based on the characteristic shape of SS-EI curves, two approaches have been proposed to calculate the maximal RBC elongation index (EI_max) and the shear stress required for one-half of this maximal deformation (SS_1/2): (i) linear Lineweaver-Burke (LB) model; (ii) Streekstra-Bronkhorst (SB) model. Both approaches have specific assumptions and thus may be subject to the measurement conditions. Using RBC treated with various concentrations of glutaraldehyde (GA) and data obtained by ektacytometry, the two approaches have been compared for nine different ranges of SS between 0.6–75 Pa. Our results indicate that: (i) the sensitivity of both models can be affected by the SS range and limits employed; (ii) over the entire range of SS-data, a non-linear curve fitting approach to the LB model gave more consistent results than a linear approach; (iii) the LB method is better for detecting SS_1/2 differences between RBC treated with 0.001–0.005% glutaraldehyde (GA) and for a 40% mixture of rigid cells but is equally sensitive to SB for 10% rigid cells; and (iv) the LB and SB methods for EI_max are equivalent for 0.001% and 0.003% GA and 40% rigid, with the SB better for 0.005% GA and the LB better for 10% rigid.     

Effect of different fixative solutions on eyes with experimental proliferative vitreoretinopathy

The aim of this study was to evaluate the use of different fixatives on the reliability of histopathological changes in a rabbit model of proliferative vitreoretinopathy (PVR). Twenty eyes from 10 rabbits were divided into four groups. The right eyes were used in two experimental groups (each n = 5), and the left, in two control groups (each n = 5). Using a newly developed scleral incision marker, an oblique scleral incision was standardized in the experimental groups, followed by intravitreal injection of 0.4 ml autologous blood and the left for wound repair for four weeks. Eyes were enucleated at four weeks. The groups differed in the type of used fixative solution (formaldehyde 4% vs. 1% buffered formaldehyde and 1.25% glutaraldehyde). The eyes were evaluated for the development of fibrosis, retinal detachment (RD), and processed for histopathology. Fibrous ingrowth of a variable degree was present in the experimental groups originating from the trauma site. Experimental eyes fixed with formaldehyde 4% had RD extension that was greater than that fixed in formaldehyde/glutaraldehyde mixture; however, the difference did not reach statistical significance (P = 0.15). This difference was not fully explained by the fibrosis which developed. In addition, in control groups, formaldehyde 4% induced a fixative-dependent retinal separation that was absent in eyes fixed with formaldehyde/glutaraldehyde mixture (P = 0.03). In conclusion, a mixture of buffered formaldehyde 1% and glutaraldehyde 1.25% combined with standardized scleral incision resulted in consistent pathological changes. A reliable PVR model is a condition sine qua non to evaluate antifibrotic treatment strategies.     

A pseudoepidemic of Mycobacterium chelonae: contamination of a bronchoscope and autocleaner

Background: At fibreoptic bronchoscopy the potential exists for contamination of bronchoscopes and microbiological specimens. Patients may also be cross infected with acid fast bacilli (AFB). During a five month period, 12 bronchial wash specimens of 65 patients undergoing bronchoscopy, one bronchoscope and an autocleaner, were contaminated with the AFB, Mycobacterium chelonae (MCH).
Aim: To eradicate AFB contamination of bronchoscopy specimens by identifying sources of contamination and modifying disinfection procedures.
Methods: To identify the source of contamination, samples for AFB culture were taken from three bronchoscopes, the autocleaner and water taps. To eradicate MCH contamination, the bronchoscopes were soaked in 2% glutaraldehyde overnight and flushed with 70% alcohol. Disinfection procedures were altered by using sterile water and containers in cleaning. Autocleaner use was discontinued.
Results: The autocleaner, one bronchoscope and 12 bronchial wash specimens were contaminated with MCH. All contaminants had similar electrophoretic banding on probing of their DNA fragments, suggesting a common clone of origin. After the alterations in disinfection procedures and despite prolonged soaking in 2% glutaraldehyde, three further contaminated wash specimens were isolated from one bronchoscope. Only after ethylene oxide sterilisation of this bronchoscope was the contamination overcome. Since then no further MCH contamination has occurred. No patient required treatment and there has been no clinical evidence of mycobacterial disease.
Conclusion: To avoid contamination of bronchoscopy specimens with MCH, use of autocleaners should be discouraged and sterile water and containers used in cleaning procedures. If MCH contamination occurs in this setting, the bronchoscope and dismantled valve mechanism should undergo ethylene oxide sterilisation. (Aust NZ J Med 1994; 24: 693–695.)     

Glutaraldehyde in collagen gel formation

The effect of glutaraldehyde (GTA) on the course of collagen gel formation was studied by measuring the absorbance against time. It was found that the t_1/2 of fibril formation decreased with the addition of GTA and reached a minimum at a concentration of 6μl of GTA per g of collagen. For GTA concentrations, [GTA], above this value, t_1/2 increased again and fibril formation was inhibited at concentrations of about 50-60 μl of GTA per g of collagen. Thermal analysis showed that the denaturation temperature was the highest for the gels formed with [GTA] of 6 μl/g, the transition peak also being the sharpest. At this [GTA], the compressive rigidity of the gels was also the highest. For low [GTA], above and below the optimum value, the fibrils formed had the normal collagen periodicity when observed in the electron microscope. This study shows that collagen gels which find applications as biomaterials can be effectively crosslinked at the gelation stage itself by the addition of low concentrations of GTA.     

PG消毒剂的研究

PG 消毒剂含2%强化中性戊二醛,醇类和香料.该消毒剂对细菌、真菌与 HBsAg 有良好灭活作用.以其制成消毒纸巾擦手1分钟,可将自然菌减少99%.