Quantitation of bacterial adhesion to polymer surfaces by bioluminescence

Quantitation of microbes adhering to a surface is commonly used in studies of microbial adhesion to different surfaces. We have quantified different staphylococcal strains adhering to polymer surfaces by measuring bacterial ATP (adenosine triphosphate) by bioluminescence. The method is sensitive, having a detection limit of 10(4) bacterial cells. Viable counting of bacterial cells may yield falsely low results due to the presence of "dormant" and adherent bacteria. By using bioluminescence, this can be avoided. Cells of different bacterial species and cells of strains of the same species were shown to differ significantly in their basal ATP content (8.7 x 10(-13) - 5.2 x 10(-22) MATP). The size of adherent and planktonic bacteria decreased with time (0.7 micron-->0.3 micron, 20 days). During incubation in nutrient-poor buffer ("starvation"), the ATP content of adherent bacteria decreased after 24-96 h whereas that of planktonic bacteria was stable over 20 days. The presence of human serum or plasma did not interfere significantly with the test results. Since the ATP concentration of bacterial strains of different species varies and is also influenced by the growth conditions of bacteria (solid or liquid culture medium), a species-specific standard curve has to be established for bacteria grown under the same culture conditions. We conclude that the method is a sensitive tool to quantify adherent bacteria during experiments lasting for less than 6 h and constitutes a valuable method to be used in conjunction with different microscopical techniques.     

Motivation and characterization of finnish meat inspection veterinarians

A questionnaire survey on the factors affecting the motivation and work attitudes of Finnish veterinary meat inspectors was conducted. Traditional meat inspection on the slaughtering line and in the emergency department took up most of the weekly work time (15.8% and 15.8%, respectively). Emergency slaughtering (29%) and general hygiene control (29%) were considered the most important tasks of veterinary meat inspectors. Assurance of meat safety (68%) was cited as the most important single reason for meat inspection. Veterinary meat inspectors were of the opinion that they do not play an important role in the training of slaughterhouse personnel, although they considered training to be a very important means for promoting hygienic work methods among workers. Three orientations of the respondents toward meat inspection and slaughterhouse operations were revealed from the survey: hygiene, education, and emergency slaughter work orientation. Meat inspection veterinarians may feel isolated from the other personnel responsible for maintaining quality and hygiene. The orientation and possible isolated position of veterinary meat inspectors should be given more attention in both the basic undergraduate and postgraduate training of veterinary meat inspectors.     

Short-term effects of initial, nonsurgical periodontal treatment (hygienic phase)

Longitudinal studies have reported the effect of various modalities of periodontal surgery on pocket depth and attachment levels related to pretreatment measurements. However, possible changes in these measurements as a result of scaling, oral hygiene improvements and occlusal adjustment during the hygienic phase were not considered. The purpose of the present study was to examine the short-term effect of treatment of the hygienic phase in 90 patients with some pockets extending 4 mm or more apically to the CEJ. Pretreatment pocket depths and attachment levels related to the CEJ were measured by a thin probe in five sites at all 2,355 teeth in the sample. Scaling, root planing, instruction in oral hygiene and occlusal adjustment were completed during four to six sessions for each patient. Four weeks after completion of the hygienic phase, all variables were recorded. Mean measurements for pocket depths 1-3 mm, 4-6 mm, and greater than or equal to 7 mm prior to treatment were compared to their posttreatment scores. Pocket depth decreased significantly for pockets extending 4 mm or more apically to the FGM. For pockets 4-6 mm there was a mean difference in pocket depth of 0.96 +/- 0.47 mm (P < .0001) between pretreatment and posttreatment observations. For pockets 7 mm or greater the mean difference was 2.22 +/- 1.35 mm (P < .0001). Reduction in depth of pocket and improvement in attachment levels were related to the initial level of severity. Pocket reduction was in part due to the improvement in attachment levels. This study has demonstrated that the clinical severity of periodontitis is reduced significantly 1 month following the hygienic phase of periodontal therapy, and that need for surgical pocket treatment cannot be assessed properly until completion of the hygienic phase of treatment.     

SV40 as a possible cofactor in the etiopathogenesis of mesothelioma and other human tumors

Equine artificial insemination (AI) meanwhile has been widely established in the warm blood horse industry. Because of its importance consistent hygienic aspects and their significance for the use of stallions as semen donors in AI-programs are presented and clarified. Incidence as well as importance of equine venereal infectious diseases are considered. Data of physiological bacterial genital flora and treatment principles of therapeutic control of venereal infectious bacterial agents as well as a model of control of Equine Viral Arteritis are given. A prophylactic hygiene program for donor stallions in routine AI including special microbiological monitoring is presented.     

Treating dental caries as an infectious disease. Applying the medical model in practice to prevent dental caries

The article stresses that railway hygiene has accumulated vast experience in evaluation of working environment of railway construction workers in severe climate conditions, thorough hygienic characteristics cover the main construction occupations and the exploitation staffers. The research helped to elaborate variety of hygienic regulations on occupational hygiene and work schedules for railway construction workers, on hygienic basis of the workers' everyday life in severe climate conditions.     

Results of hygienic investigations in hospitals and their consequences (author's transl)

In all parts of the hospitals examined results were found, which demonstrated, in part considerable, gaps in the hygienic systems. Therefore the enforcement of the following measures must be emphatically postulated: - Development of hospital hygiene plans by competent experts in cooperation with the doctors and nurses in charge. - Foundation of commissions for hygiene, who are responsible for preventive measures and for the establishment of a survey of hospital infections. - Delegation of the internal control of hospital hygiene to a person experienced in that field without other functions. - Renovation of supplementation of the technical hygienical facilities especially in old hospitals.     

Assessing abattoir hygiene with a marker organism

A study was made to evaluate the use of a marker organism for assessing whether hygienic slaughter practices were being followed at red meat abattoirs. The organism, a nonpathogenic strain of Escherichia coli K12 that was resistant to nalidixic acid, was detected and counted on a highly specific isolation medium. With beef carcases, the practice of bagging the excised anus reduced, but did not prevent the spread of the organism from an inoculum applied in the anal region before the hide was removed. The carcases of sheep that were processed at a low-throughput abattoir, were contaminated with the marker after the fleece had been inoculated at a single site. The contamination was significantly reduced (P<0.001) when the operative responsible for flaying had cleaned his hands, arms and apron before and during the handling of each carcase, and used a knife which was freshly pasteurised on several occasions. However, the subsequent washing of carcases had little or no effect on the levels of the marker organism. It was concluded that the marker may be of value in assessing hygiene control, improving present practices, and training abattoir staff.     

Pharmacodynamic effects of antibiotics and acid pump inhibitors on Helicobacter pylori

Pharmacodynamic studies of Helicobacter pylori exposed to amoxicillin, clarithromycin, metronidazole, omeprazole, and lansoprazole were performed with microscopy, viable count determination, and bioluminescence assay of intracellular ATP. The pharmacodynamic parameters determined were change in morphology, change in cell density, postantibiotic effect (PAE), and control-related effective regrowth time (CERT). The PAE is delayed regrowth after brief exposure to antibiotics or acid pump inhibitors. CERT was defined as the time required for the bacteria to resume logarithmic growth and return to the pre-exposure inoculum in the test culture minus the corresponding time for the control culture. CERT measures the combined effect of initial killing and PAE. There was a good concordance between the bioluminescence assay and viable counts for determining CERT, which makes this parameter useful for pharmacodynamic studies of the effects of antibiotics and acid pump inhibitors on H. pylori. Amoxicillin and metronidazole produced a strong, concentration-dependent initial decrease in CFU per milliliter, but there was a less prominent initial change in intracellular ATP in these cultures. Amoxicillin caused a long PAE when assayed by the bioluminescence assay but no PAE or a negative PAE when assayed by viable count determination. However, amoxicillin showed similar long CERTs with both methods. The pharmacodynamic effects of amoxicillin were concentration dependent up to a maximum response, indicating that concentrations above this level do not increase the antibiotic effect. The PAEs and CERTs of clarithromycin and metronidazole were concentration dependent with no maximum response. With omeprazole and lanzoprazole, there was no PAE or CERT.     

Recovery of EDTA from Power Plant Boiler Chemical Cleaning Wastewater

The deposition of iron oxides, metallic copper, and other impurities on boiler tube surfaces causes loss of heat transfer efficiency at electrical power plants. Hence, the tubes are cleaned every 3–5 years in order to restore the heat transfer efficiency. Chelating agents, mainly ethylenediaminetetraacetate (EDTA) and its salts, have been extensively used for the removal of metal deposits from the boiler tube surfaces. Consequently, the boiler chemical cleaning wastewater (BCCW) contains large amounts of iron, copper, and chelating agents. An electrochemical reduction process that reduces metal ions to their elemental state is tested and evaluated in order to provide the potential option to recover EDTA for reuse from power plant BCCW. Results from controlled direct current electrolysis experiments show that the electroreduction process can successfully remove metal ions from the synthetic solution and field BCCW samples and can deposit elemental metals on the cathodic plate. At a current density of 15.5 mA∕cm2 and a temperature of 40°C, the percentage metal removal and current efficiency were 94.16 and 8.27%, respectively, with a cadmium cathodic plate. Moreover, results also indicate that the percentage of metal removal and overall current efficiency increase with increasing current density and temperature under the optimal condition (15.5 mA∕cm2 and 40°C). The electroreduction process is able to separate metal ions from their EDTA complexes. The free EDTA can be recovered from field power plant BCCW and be reused again as cleaning agent.     

Autoaggregation and adhesion ability in a Bifidobacterium suis strain

According to the current law of preventing infectious diseases in Germany, bacterial as well as aseptic meningitis have to be reported to the health authorities, whereas according to the amendment aseptic meningitis will no longer be notifiable. In Summer 1997, 63 children with aseptic meningitis were reported to the local health authorities of Frankfurt compared with 4 or 5 per year during the preceding years. In 40% enterovirus, resp. ECHO-30 virus could be detected. The local health authorities gave detailed information on the medical relevance as well as necessary hygienic measures to the families and kindergartens. During the same time reports on aseptic meningitis increased to double compared with 1996, with hot spots in 4 defined regions in Bavaria, Hesse and in Northern Germany. According to these data the duty of notification of aseptic meningitis should be maintained, so that health authorities can inform the population and ensure good hygiene methods.     

Pyrolysis mass spectrometry: data processing in classification studies

A scheme for numerical processing of pyrolysis mass spectrometry (Py-MS) data is detailed, along with methods for combining the results of conventional phenotypic and Py-MS taxonomic surveys. The importance of this combined approach in polyphasic taxonomy is emphasised; it yields data on cell composition and the nutritional and physiological interactions of strains with their environment. Large collections of strains can be surveyed rapidly and economically, yielding presumptive classifications, which may then be confirmed with a few representative strains in more demanding, difficult and expensive approaches. An objective, non-arbitrary method of establishing suitable cut-off points to delineate group structures in dendrograms is also described.     

Closed or open periodontitis treatment. A review of the literature

Clinical data characterizing the results of non-surgical, conservative versus surgical modalities of periodontal treatment are presented and summarized, as they appeared in the international literature. Primarily, the clinical disease status prior to treatment is discussed. Thereafter, the therapeutic success of either modality was measured on the basis of the following parameters: reduction of probing depth, changes in attachment levels, cleanliness of root surfaces, elimination of inflammation, and longlasting tooth survival. The literature review revealed that the choice of either treatment modality influences the therapeutic success only indirectly. More important is that the diseased root surface is meticulously cleaned from all bacterial debris. In the presence of shallow (1 to 3 mm) and medium-sized (4 to 6 mm) pockets, surgical and non-surgical treatment provides equally good results. Deep pockets (7 mm or deeper) and, in particular, crater-like bony pockets as well as furcation involvement respond with better results, if surgical treatment is assigned. In the long run, however, therapeutic success can be secured only by means of a consequent periodical recall and with support of the patient's willingness to perform optimal oral hygiene.     

Modification of official method for analysis of carotenes and xanthophylls in dried plant materials and mixed feeds

The official method (43.018-43.023) for extraction and separation of carotenes and xanthophylls in dried plant materials and mixed feeds is modified. These pigments are extracted from samples lacking xanthophyll esters by stirring 2 hr, followed by 1-hr cold saponification. The official method recommends 16-hr static extraction preceding the cold saponification. For samples containing xanthophyll esters, we preceded the 20-min hot saponification step by 2 hr stirring. This extra step increased the yield of mono- and dihydroxy pigments, especially from marigold meal. For separation, Merck silica gel 60 plus Hyflo Supercel is substituted for silica gel G in adsorbent I, resulting in 30-min separation. Also, at least 4 separations can be performed using the same adsorbent, and the column is more easily cleaned between separations. Results of the modified method were comparable to those of the official method.     

The effect of aurotherapy on the level of unsaturated fatty acids during the treatment of rheumatoid arthritis patients

In the last decade a good number of biotechnical methods have been developed. They are available in medical, biological, and ecological fields of work as well as techniques that can replace animal experiments. These methods have been developed on the basis of researchwork in andrology (AI and cryoconservation of spermatozoa), endocrinology (hormonal control of reproduction) and the availability of industrial produced hormones and their analog. On the other hand practical clinical techniques for examination like the availability of sonography advice and clinical practical techniques for non-surgical recovery and transplantation of gamets and embryos have been the prerequisites for a successful work in this field of action. These fields of action are extended from breeding aspects (genetical progress) over the control of epidemics to the exportation of genetic material (especially developing countries to overcome hygienic and adaptation problems), the creation of gen-pools (conservation of breeds-species) and as well as the elimination of genetic defects like BLAD or DUMPS by help of PCR-techniques or the identification of positive characters like milk components and sexing of embryos. The industrial use of bioproducts produced by especially designed biosystems is in work but in Germany not possible by reasons of legislative restrictions. In the light of these developments the veterinary fields of work should be discussed and focussed towards an understanding that the veterinarian should be active and in a polposition in the processing of reproduction and production and presentation of food of animal origin by using these new technologies.     

Arrest of root surface caries in situ

This study tests the hypothesis that daily oral hygiene combined with topical fluoride arrests active root-surface caries lesions without changing the mineral content of the lesions. Therefore, changes in mineral content and distribution were studied in root surfaces during caries lesion development and subsequent arrest of lesion progression in situ. In 18 subjects, lesions were developed during 3 months in sound root-surface specimens inserted into lower partial dentures. After 3 months, ground sections were prepared from each lesion prior to re-insertion of the specimens into the dentures. In addition, one sound root specimen was added per subject. During the following 3 months, half of the subjects cleaned both sound and carious specimens once a day with an 1100-ppm fluoride toothpaste, and the specimens were treated twice with 2% NaF for 2 min in situ. The other half of the subjects continued the experiment without cleaning. During the initial three-month period, all specimens developed subsurface lesions extending 187 to 583 microm into the dentin. Lesion depth increased somewhat in both experimental groups during the following 3 months (P > or = 0.1). There was a non-significant increase in mineral loss in the plaque-covered specimens (P = 0.08). However, the total mineral content of specimens subjected to plaque removal and topical fluoride did not change. This treatment resulted in an increased mineral content in the surface layer (P < 0.01) and formation of a zone of higher mineral content within the body of the lesion. The sound root surfaces which had been cleaned for a three-month period showed mineral uptake in the surface layer, occasionally associated with subsurface demineralization extending 20 to 70 microm into the tissue. The mineral loss of these specimens was significantly smaller than that of plaque-covered surfaces (P < 0.001). It is concluded that daily plaque removal and topical fluoride use influence the distribution of mineral in sound and carious root surfaces and may arrest lesion progression without affecting the total mineral content.     

Comparison between two types of air microorganism sampling

The airflow striking sampling was compared with flat utensils sedimentation sampling for collection of air microorganisms. The result showed that air microorganism count with the former method is more efficient than the latter method (P < 0.05). The flat utensils sedimentation sampling only collected larger particles of microorganism so the air microorganism count was not accurate. However, it is still a suitable method in hygiene without other choices. The airflow striking sampling collected more middle and tiny particles for air microorganism than the sedimentation sampling and can accurately show microorganism content in air, so it is an optimal sampling method.     

Supervisory Fuzzy Expert Controller for Sag Mill Grinding Circuits: Sungun Copper Concentrator

Successful control of Semi-Autogenous Grinding (SAG) mill circuits has been the subject of many researches and main concern of plant operators for years. Distributed Control Systems (DCS) have had some degree of success in the mineral processing circuits, but maintaining operation of a SAG mill on the “edge” of its full capacity is not easily achievable by DCS. Advanced control systems, however, are a relatively new opportunity to successful control of mineral processing plants. This article presents the basis of a supervisory fuzzy expert controller for SAG mill circuits. Although leading companies in control and automation have their own commercial packages, this supervisory controller is coded in Matlab using Mamdani method and is able to connect to plant lower level control system. In the proposed controller, fuzzy system calculates optimum set points to the plant DCS control loops, enabling them to change the manipulating parameters to reach the new set points. This controller was installed, tested and verified in a copper grinding circuit. Results showed 1.8% increase in mill throughput, 3% decrease in power draw and more stable feeding regime at the same time.     

Comparison of 2 toothbrushing methods for efficacy in supragingival plaque removal. The Toothpick method and the Bass method

Plaque removing efficacy was compared between a new toothbrushing method named the Toothpick method and the Bass method. 20 male university dental students participated in the study, which consisted of 2 experiments. Prior to each experiment, all subjects were asked to abstain from all oral hygiene procedures for 48 h. In Exp. I, plaque-removing efficacy was assessed after each participant's mouth had been professionally brushed by a dentist. In this experiment, 2 quadrants were brushed professionally using the Toothpick method, and the remaining 2 quadrants were brushed using the Bass method. The brushing time amounted to a total of 2 min per mouth. In Exp. II, the subjects brushed their own teeth after receiving toothbrushing instruction. A blind examiner assessed dental plaque using a modification of the Quigley and Hein index at 6 sites around each tooth. Toothbrushing using the Toothpick method was found to remove significantly more plaque from proximal tooth surfaces than brushing using the Bass method.     

Psychiatric and psychologic aspects of stomatologic diseases, or stomatologic aspects of psychiatric diseases. Review of the literature

Dental symptoms, oral medicine and psychiatric and psychologic problems have strict relationships in several domains. Behavior and behavioural problems (deficient oral hygiene, lack of regular dental control, dependence of nicotine or alcohol, etc.) as well as certain psychiatric diseases influence the patients' dental state to a great extent. There are further problems determined by the different types of anxiety, fear and bad previous experiences which have an impact on people's attitudes towards dental treatment and the development of hygienic habits. Dentists' psychologic and psychiatric knowledge can have a considerable contribution to the reduction of the patients' anxiety, furthermore to an appropriate treatment, by the recognition of the underlying psychiatric disease.     

矿用铰接式车辆路径跟踪控制研究现状与进展

铰接式车辆的路径跟踪控制是矿山自动化领域中的关键技术，而数学模型和路径跟踪控制方法是铰接式车辆路径跟踪控制中的两项重要研究内容。在数学模型研究中，铰接式车辆的无侧滑经典运动学模型较为适合作为低速路径跟踪控制的参考模型，而有侧滑运动学模型作为参考模型时则可能导致侧滑加剧。此外基于牛顿–欧拉法建立的铰接式车辆四自由度动力学模型原则上满足路径跟踪控制的需求，但是还需要解决当前的四自由度模型无法同时反映瞬态转向特性和稳态转向特性的问题。在路径跟踪控制方法研究中，反馈线性化控制、最优控制、滑模控制等无前馈信息的控制方法无法有效解决铰接式车辆跟踪存在较大幅度曲率突变的参考路径时误差较大的问题，前馈–反馈控制可以用于解决上述问题，但是在参考路径具有不同幅度的曲率突变时需要解决自动调整预瞄距离的问题，而模型预测控制，尤其是非线性模型预测控制，可以更加有效地利用前馈信息，且不需要考虑预瞄距离的设置，从而可以有效提高铰接式车辆跟踪存在较大幅度曲率突变的参考路径时的精确性。此外，对于基于非线性模型预测控制的铰接式车辆路径跟踪控制，还需深化三个方面的研究。首先，该控制方法仍然存在误差最大值随参考速度增大而增加的趋势。其次，目前该控制方法以运动学模型作为预测模型，无法解决铰接式车辆以较高的参考速度运行时侧向速度导致的精确性下降和安全性恶化的问题。最后，还需对这种控制方法进行实时性方面的优化研究。