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At least 127 records · Page 7Linked to original sources

PubMed1975

[Glass fibre HEPA filters. II. Communication: Microbiological and physico-chemical researchs on used and unusued, hydrophilic and hydrophobic filter materials in an air conditioning plant (author's transl)].

Hydrophobic and hydrophilic, used and unused HEPA filters from various manufacturers, inoculated with vegetative bacteria, bacterial and fungal spores, were exposed to clean outside air for up to 17 weeks in an air conditioning plant. With relative humidities up to 60%, an increase in germ count could not be found. The rate of killing the micro-organisms inoculated were different and were generally higher on used filters. The low water content of the filter material was apparently not sufficient for microbial growth. In addition, the increase in electric conductivity and reduction of pH value resulting from deposition of substances from the outside air with an acid reaction ascertained in the aqueous filter extracts had a negative effect on the living conditions of the microorganisms.

Air Conditioning↗

PubMed1977

[The contents of caries-free fissures of human premolars and molars].

The contents of the fissures of occlusally caries-free human premolars and molars were examined for colour, consistency and removability, and under the microscope. The results obtained were brought in relation to the forms of the fissures. Superficial fissure contents contain micro-organisms, are similar to materia alba and may be considered as acquired. Contents from the depth of narrow fissures contain epithelial cell-like structures but no or very few bacteria and seem to be remnants from the time when the teeth were being formed.

Dental Caries Susceptibility↗

PubMed1979

[Influence of culture media on the growth of Streptococcus mutans ATCC 25175 in the presence of various carbohydrates and their derivatives].

The growth of Streptococcus mutans ATCC 25 175 has been studied in the presence of various sugars (sorbitol, mannitol, lycasin, sorbose and xylitol) and compared to sucrose, glucose and fructose, added to a complex and a synthetic culture medium. In these two media, the decrease in pH was related to the bacterial growth; this fact was confirmed by the dosages of the liberated lactic acid. In the complex medium, the different sugars influenced only slightly the bacterial growth, whereas in the synthetic medium the micro-organisms did not grow in the presence of sorbose, xylitol or lycasin 80/55. An adaptation period was necessary before the beginning of bacterial growth in the synthetic medium supplemented with sorbitol and mannitol.

Carbohydrates↗

PubMed1977

Biochemical markers for strain differentiation in malarial parasites.

Genetic differences between micro-organisms can be identified by studying variations in enzyme forms and DNA characteristics. Enzyme electrophoresis has revealed considerable genetic diversity in populations of malarial parasites and has enabled populations reproductively isolated from one another to be identified. Studies on rodent malarial parasites from four regions of Africa have shown that each species and subspecies can be distinguished by its pattern of enzyme forms. In subspecies in which enzyme polymorphism occurs, the frequencies of each combination of enzyme forms suggest an extensive degree of random mating in the population. Populations of Plasmodium falciparum are also enzymically polymorphic, similar enzyme variants being found in isolates from several parts of the world.

Africa↗

PubMed1977

[Studies on the spacial aerosol spreading during the use of turbines].

When treating hard tooth structures with a turbine instrument, a polydisperse aerosol is formed from the turbine exhaust air and the cooling-water spray and by the rotation of the abrasive tool. The oral cavity repels this aerosol that is contaminated with micro-organisms and particles of enamel and filling materials. The present paper deals with the spatial propagation of the aerosol cloud in front of the patient's mouth in relation to the site of impact of the turbine instrument. Recommendations are given for practice to reduce the possibilities of infection.

Aerosols↗

PubMed1978

[Disinfection of effluents from municipal sewage treatment plants with hydrogen peroxide (author's transl)].

Effluents from different sewage treatment plants were disinfected, using hydrogen peroxide in concentrations varying between 500 and 50,000 ppm. With a concentration of 5,500 ppm H2O2 and a contact time of 2 h more than 99% of bacteria were killed, including enterobacteria, total and fecal coliforms (Fig. 1 A, B, C and D) and fecal streptococci (Fig. 2 B). Staphylococci and micrococci were less sensitive and contact times of 2 h were not sufficient to kill 99% of this group (Fig. 2 A). Highly resistant were bacterial endospores (Fig. 2 C). With a concentration of 5% H2O2 50% of the spores still survived after a contact time of 2 h (Fig. 2 D). The effect of 5,500 ppm H2O2 by an exposure time of 2 h was then studied with other effluents. The results show that total counts were also reduced for 90% and some groups for more than 99% (table 1). There was no difference in reduction between catalase positive and catalase negative micro-organisms, indicating that the catalase activity of the bacteria offered no special resistance towards hydrogen peroxide in the concentrations used (table 2). Although the observations of some investigators have shown that metal ions act to increase the bactericidal effect of H2O2 as a result of formation of hydroxyl radicals, the additions of ferrous ions (5,25 and 50 ppm) did not improve the killing activity of H2O2 (table 3).

Disinfection↗

PubMed1978

The induction of salivary antibodies by topical sensitization with particulate and soluble bacterial immunogens.

This investigation attempted to characterize systematically the secretory and serum immune responses following oral administration of soluble and particulate bacterial immunogens. Following oral sensitization of axenic mice with Escherichia coli lipopolysaccharide, Candidin, or streptococcal group H antigen, a substantially longer latent period was observed before all salivary samples exhibited specific agglutinins when compared to a similar immunization regimen with intact nonviable micro-organisms. Also, the peak titres of salivary agglutinins were significantly lower when the soluble antigenic counterparts of particulate E. coli or Candida albicans were utilized as immunogens. Examination of serum antibodies showed that following administration of E. coli LPS, similar titres of exocrine and serum agglutinins were noted. The serum titres were significantly greater (P less than 0.01) than those elicited by oral immunization with particulate E. coli. After termination of the topical immunization regimen, salivary agglutinins were found to decline rapidly whether immunization was via soluble or particulate antigens; however, immunization with particulate bacterial antigens appeared capable of stimulating and maintaining a higher rate of local antibody secretion than similar sensitization with soluble immunogen preparations.

Animals↗

PubMed1978

Care of the burn wound.

The initial therapy of thermal injuries is directed at removal of loose debris and necrotic epidermis, alleviation of pain, and prevention of infection. Following initial wound debridement, bacterial growth in the wound itself is controlled primarily through the use of tropical antibiotic agents and daily hydrotherapy to clean the wounds and remove any loose eschar. Effectiveness of topical therapy is monitored by quantitative burn wound biopsy cultures; growth of greater than 10(4) micro-organisms per gram of tissue indicates invasive burn wound sepsis. Such bacterial invasion may be further controlled through the adjunctive use of antibiotics administered into the sub-eschar space. Once eschar separation has exposed healthy granulation tissue, the burn wound must be covered with suitable biologic dressings prior to autografting. All open wounds may then be autografted with sheet grafts to the face, neck, and areas exposed to trauma or by expansion mesh grafts to cover large areas from limited donor sites. Upon completion of autografting, a vigorous physical therapy program is necessary to rehabilitate victims of massive thermal injury to a functional existence.

Administration, Topical↗

PubMed1978

The early cellular response to M. leprae. An ultrastructural study.

The ultrastructural changes that develop in mouse peritoneal macrophages from 10 minutes up to 14 weeks after exposure to Mycobacterium leprae are presented. Phagocytosis occurred by a process of engulfment by cytoplasmic processes and incorporation into a phagosome, into which lysosomal enzymes were subsequently introduced. Electron transparent zones (E.T.Z.) were not observed around phagocytosed bacilli in this study, however discrete droplets of lipid-like material appeared in the cytoplasm of macrophages, between 2 and 4 weeks after ingestion of the micro-organisms. Phagosomes with double limiting membranes were observed in macrophages harvested as early as 40 minutes after exposure to M. leprae, contrary to the observations of Evans and Levy (1972).

Animals↗

PubMed1978

[Investigations into the incidence of the various causative agents of mastitis in cattle. Studies done in the ambulatory clinic of the Faculty of Veterinary Medicine, Utrecht].

The clinical and bacteriological findings in every head of cattle treated for clinical mastitis in the Ambulatory Clinic of the Veterinary Faculty of Utrecht University were recorded over a period of twelve months. Cattle affected with mastitis were classified into a number of groups, a classification based on the clinical symptoms shown by the animals. In each of these groups the incidence of the various causative agents of mastitis was determined. Another subject of study was the distribution of the causative agents over the various groups. The high proportion (34 percent) of coliform micro-organisms, isolated from animals affected with acute mastitis and showing symptoms of generalized disease was a striking feature.

Acute Disease↗

PubMed1978

Macrophage secretion and the complement cleavage product C3a in the pathogenesis of infections by mycoplasmas and L-forms of bacteria and in immunity to these organisms.

Mouse peritoneal macrophages in culture exposed to Mycoplasma pulmonis show marked biochemical changes. This micro-organism induces the release of hydrolytic enzymes from macrophages. The release is time- and dose-dependent and is not associated with loss of the cytoplasmic enzyme lactate dehydrogenase or any other sign of cell death. Secretory products of macrophages may play a role in the pathogenesis of chronic inflammatory responses elicited by mycoplasma infections. One of the products of activated macrophages is the complement cleavage product C3a. Purified C3a was incubated with M. hominis, M. pulmonis, Proteus mirabilis and an L-phase variant of this organism. All mycoplasmas and the L-phase variant were lysed by low concentrations of C3a, whereas the bacterial form of Pr. mirabilis was resistant.

Animals↗

PubMed1979

[Development of anaesthetic technique for endolaryngeal surgery 1960--1976 (author's transl)].

In 1960 direct laryngoscopy in combination with general anaesthesia with relaxation and intermittent positive negative pressure ventilation via a smallbore blocker tube was introduced. When, in 1965, microlaryngoscopy was developed it was exclusively performed with this technique. Since 1960, 44, 464 ear, nose or throat operations were carried out. 3,305 (7.4%) were endolaryngeal operations. 943 of them were performed in surface analgesia. 2,363 microlaryngoscopic operations were done under general anaesthesia. 22.5 per cent of the patients were women and 77.5 per cent were men. Their age varied between 6 weeks and 86 years. 2.4 per cent were children under 6 years of age and 33 per cent were aged over 60 years. The main advantages of this method over "open laryngeal surgery" are: 1. it provides a large measure of safety for the patient since even old and obese persons with a rigid rib cage can be adequately ventilated; the cuff prevents aspiration; there is no danger of the patient waking up during relaxation since he is being kept ventilated with a mixture of nitrous oxide-oxygen and halothane. Ventilation via the blocker tube begins immediately after intubation and not, as in open jet ventilation, after insertion of the laryngoscope. 2. The surgeon and his team are not exposed to the risk of infection since, in contrast to the "open larynx" methods, the closed system effectively prevents the escape of pathogenic micro-organisms.

Adolescent↗

PubMed1979

[Standardised antibiotic therapy in major lung surgery (author's transl)].

Sputum and bronchial biopsies and smears were obtained from 221 patients who had undergone partial pneumonectomy without preceding antibiotic therapy. The results of 343 sputum examinations and of 126 bacteriological examinations of biopsies and smears were evaluated. Pathogenic bacteria were demonstrated in about 50% of the sputa and in about 25% of the biopsies and swabs. Anaerobic micro-organisms were extremely rare. Treatment was with tetracycline. Before antibiotic therapy Haemophilus influenzae, staphylococci and E. coli predominated, afterwards there were practically only staphylococci and Esch. coli. The incidence of primary resistance to the usual antibiotics was high, especially in respect of gram-negative organisms. The difference in incidence between primary and secondary resistance was one of degree. The least effective agents were ampicillin and amoxicillin, the most active were the aminoglycosides. Erycin proved satisfactory in infections with grampositive organisms while the cephalosporins were active against both gram-positive and gram-negative bacteria. The development of resistance and the clinical picture suggest that "eradication" of the infection during the postoperative stage is not advisable as it causes the selection of more or less drug-resistant organisms. A more satisfactory approach is gradually to reduce the infection until the immediate postoperative stage is over. Macroscopic and microscopic examination of the sputum is important, as the choice of the appropriate antibiotic is determined by the result of gram-staining.

Aminoglycosides↗

PubMed1979

[Retinal detachment surgery: Incidence and causes of silicone sponge implant rejection].

In 51 patients with retinal detachments silicone sponge implants have been applicated. In 9 of these cases (17,6%) the implants had to be removed 3 weeks to 16 months postoperatively because of inflammatory reactions. The influence of these complications on the healing of the retinal detachment is considered as relatively unimportant. In light- and electron-microscopic examinations we could establish that the reactions are mainly caused by infections (which primarily spread within the caves of the sponge implants). Chronic infections caused by so-called apathogenic bacteria are more frequent than acute infections by so-called pathogenic micro-organisms. A foreign body reaction could be proved only in one case, in which the sponge was loosened and displaced. Defence reactions against the foreign body material probably develop only if mechanical irritation of the tissue is caused by the sponge material.

Adult↗

PubMedDate not supplied

[Problem of "biological compatibility" of crew members during prolonged space flight and possible directions for its solution].

The concept of biological compatibility of men can be defined as a phenomenon which includes an effect (that might be favorable or unfavorable) of one individuum on the other via trace amounts of chemicals released into their environment and micro-organisms. The paper presents the main results of studies of biological compatibility of crewmembers of space vehicles and outlines possible directions of research to be carried out in this area.

Bacteria↗

PubMed1976

Mycoplasma in tissue culture: overview of detection methods.

Mycoplasma contamination of tissue cultures is too costly, scientifically damaging and inappropriate, and perhaps, even medically hazardous to be ignored. Prevention by continuous surveillance demands adequate mycoplasma testing procedures. Despite a proliferation of indirect methods, the present consensus indicates that careful and extensive microbiological testing is still the cornerstone of any mycoplasma detection program. The finding of 'non-cultivable' or possible tissue-adapted micro-organisms plus the variability in microbiological expertise of many laboratories, makes the selection of at least one additional method imperative. At the present, though no one test will prove 100% satisfactory and selection should partly depend on available expertise, the method based on the ratio of the specific activities of incorporated radio-labelled uridine to uracil into RNA appears to be an acceptable choice due to its simplicity and general validity.

Bacteriological Techniques↗

PubMed1977

Microbial secondary metabolites with potential use in cancer treatment. (Plasmid involvement in biosynthesis and compounds.

Antibiotics and small molecular enzyme inhibitors produced by micro-organisms are microbial secondary metabolites which have no obvious function in the growth of microorganisms. Involvement of plasmids in their biosyntheses has been studied and the structure of the microbial world where various compounds with widely varying structures have been found has been shown to be due to the presence of a great variety of plasmids. On the basis of this structure of microbial world, the author has found the microbial products which have various activities useful in treatment of cancer or in suppression of carcinogenesis. In this paper, the author reviewed his following studies: the plasmid involvement in biosyntheses of bioactive microbial secondary metabolites; the mechanism of therapeutic effect of bleomycin, and the development of useful analogs and derivatives of bleomycin and anthracyclic antibiotics; the screening method to find compounds affecting immune system, and the action of bestatin in enhancing delayed-type hypersensitivity and therapeutic effects of anticancer agents; enzyme inhibitors with potential utility in treatment or prevention of cancer.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1979

[Immunotherapy of malignant growths (author's transl)].

Our knowledge of antigens which are associated with different types of malignant tumours is steadily increasing. These antigens exist in considerable numbers, but, so far with few exceptions, only their presence can be demonstrated by certain methods; to isolate and identify them has not yet been possible. These antigens are, therefore, suitable not so much for the primary diagnosis, but rather, like the carcinoembryonic antigen, the tissue-polypeptide antigen or the alpha-feto-protein, for assessing the success of treatment. Active immunization has recently received a fresh impulse by the use of the enzyme neuraminidase, derived from Vibrio cholerae, in the treatment of tumour cells. There is no passive specific immunotherapy in human cancer. As to specific active immunotherapy BCG, Corynebacterium parvum and preparations of these and other micro-organisms together with polynucleotides, levamisol, statolon, tilorone have been employed. Although the results are not uniform they are promising. Attempts at cellular transfer of immunity are not very encouraging. It should be emphasized that the findings apply to human cancer. Experimental studies have produced very interesting results.

Animals↗