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Biomedical subjects

P Berthold

Publications and source records attributed to P Berthold.

52 records · Page 3Linked to original sources

Electron immunoperoxidase stainings in sections of unfixed pure cultures of Streptococcus mutans.

Unfixed as well as glutaraldehyde-fixed pelleted cells from pure cultures of Streptococcus mutans subspecies sobrinus (B13) were embedded in glycolmethacrylate. Ultrathin were sections immunoperoxidase labelled with rabbit anti-S. mutans sobrinus gamma-globulin. It was found that unfixed specimens became labelled as precisely and as distinctly as did the fixed specimens. All controls were negative.

Fixatives↗

Encapsulated strains of Bacteroides fragilis in clinical specimens.

Studies were made of the presence of capsules in 294 strains of the Bacteroides fragilis group of bacteria isolated from clinical infections and in 30 strains from the fecal flora using the Indian ink and ruthenium red staining methods. A total of 77% of the B. fragilis strains were encapsulated; higher figures were observed in isolates from blood and wound infections. Of the B. ovatus, B. distasonis, B. vulgatus, B. uniformis, and B. thetaiotaomicron isolates from clinical infections, 17% were encapsulated. The percentage of encapsulated Bacteroides strains isolated from feces was approximately the same as in the strains isolated from clinical infections.

Bacteroides↗

Electron microscopy and immunoperoxidase staining of Streptococcus mutans during controlled growth in two different media.

Streptococcus mutans subspecies sobrinus serotype d (B13) was cultivated in a fermentor under controlled conditions in two different media: a complex proteose-peptone medium and a defined minimal medium (C4). Specimens from different growth phases were examined by electron-microscopy and tested electron-immunohistochemically. Irrespective of the growth medium used, no differences were observed in the immunohistochemical staining pattern of bacteria during the lag, the exponential and the early staionary phases. Specimens obtained several hours after exponential growth contained areas where the bacteria showed staining that ranged from a strong deposit of reaction product to no deposit. This appearance seems partly to explain the differences in the intensity of immunohistochemical staining of certain bacteria observed in dental plaques stained for identification of S. mutans subspecies sorbrinus.

Bacteriological Techniques↗

Formation of salivary coating and dental plaque on two different supporting materials. An electron microscopic study.

The formation of salivary coating (SC) and dental plaque on top of Vestopal W and enamel inlays was studied with scanning and transmission electron microscopy. No clear morphological differences were found between SC and dental plaque formed on either material. A thin continuous SC was formed on the supporting material in all volunteers within 30 minutes' oral exposure. The SC appeared smooth and contained numerous protruding small round bodies (40-200 nm in size), the numbers of which increased with increasing time. Bacterial colonization of the SC started between 6 and 12 hours' oral exposure. After 24 hours' oral exposure, bacterial colonies were confluenting and partly obscuring the subjacent SC. No evidence was obtained in this study contraindicating the use of Vestopal W as supporting material for experimental plaque studies.

Adult↗

Electron-microscopic demonstration of Streptococcus mutans in 5-day-old experimental dental plaque using immunohistochemistry.

The present work described the distribution of horseradish peroxidase reaction product obtained after immunohistochemical staining of consecutive ultra-thin sections of 5-day-old experimental dental plaques using differently absorbed anti-S.mutans sobrinus, anti-S.mutans mutans, and normal rabbit lambda-globulins. It was found that an in situ identification of S.mutans subspecies sobrinus could be obtained using thoroughly absorbed anti-S.mutans sobrinus gamma-globulins and consecutive sections. The anti-S.mutans mutans gamma-globulins were after tests on pure cultures of several oral bacteria found to cross-react with S.milleri. Furthermore, crude and absorbed normal rabbit gamma-globulins were observed to contain antibodies that cross-reacted with several plaque microorganisms.

Bacteriological Techniques↗

Some immunohistochemical experiments aiming at the electron-microscopic in situ identification of a dental plaque microorganism--Streptococcus mutans.

The aim of the present investigation was to test a procedure useful for the electron-microscopic in situ identification of the presumptive cariogenic microorganism Streptococcus mutans (serotype d) growing in the human dental plaque. For this purpose, different parameters of an indirect immunohistochemical method were tested in three sets of experiments. In experiment set I, all serological and histochemical procedures were performed en bloc on specimens fixed only with glutaraldehyde before embedding in Vestopal W. Different marking substances, such as ferritin, alkaline phosphatase and horseradish peroxidase (HRP) were tested. The en bloc method using HRP-labelled antibodies was found useful for staining of in vitro-grown bacteria but failed when applied to dental plaque. In experiment set II, ultrathin sections of glutaraldehyde-fixed and glycol methacrylate-embedded in vitro-grown bacteria were section-stained. The bacteria became outlined with a highly electron-dense HRP reaction product which accumulated on top of the cell envelope. The same type of HRP reaction product was found on some bacteria in the 2-day-old dental plaque after section-staining. This system was further tested in a series of controls also using consecutive serial sections. In exp. set III, a number of different stationary and transient oral bacteria were immunohistochemically section-stained. A cross-reaction with bacteria belonging to S.salivarius was discovered and removed by absorbing the anti-S.mutans serotype d serum with S.salivarius (NCTC 8618).

Antibodies, Bacterial↗

PENN PASS: a program for graduates of foreign dental schools.

An increasing number of graduates of foreign dental schools who enroll in advanced standing programs to qualify for licensure calls for dental schools to be prepared to handle not only the curricular demands but also the growing cultural diversity among its student population. The "reeducation" of this student group not only meets the need of foreign dentists for an American degree but may also provide health professionals to service various ethnic populations whose language and culture they are able to understand and identify with. A survey of students and graduates of a two-year Program for Advanced Standing Students (PASS) for graduates of foreign dental schools representing 34 countries aimed to arrive at an understanding of this student group through characterization of the foreign dentists and identification of their attitudes and feelings toward various aspects of the program, the school and faculty and their experience of stress. This report includes description of the distinctive features of the program which cater to specific needs and concerns of this non-traditional group of dental students. PASS students are accepted on the basis of their grades in dental school in home country, scores in the National Dental Board Examination Part I, Test of English as Foreign Language (TOEFL), and ratings in personal interviews. They complete an intensive summer program consisting of didactic and laboratory courses which prepares them for integration with four-year students for the last two years of didactic and clinical curriculum. Cultural diversity seminars, a special English class, PASS class meetings and seminars are unique additions to their program and aim to assist them adjust to the educational, social and cultural systems in an American school. Results of the survey show a majority of the PASS students feel that they are part of the school and that there is someone in the school whom they can approach for problems. An understanding of their ethnic and educational background is seen as a significant factor in their second basic dental education. Implications for education of foreign dental graduates amidst increasing diversification of the student body are discussed.

Credentialing↗