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Biomedical subjects

F H Mikx

Publications and source records attributed to F H Mikx.

At least 37 records · Page 2Linked to original sources
PubMed1993

The influence of dietary sugars and starch on the establishment of Streptococcus mutans and Actinomyces viscosus in dental plaque of specific pathogen-free rats.

The establishment of S. mutans together with A. viscosus was investigated in dental plaque of specific pathogen-free (SPF) rats fed different carbohydrate diets. Two Tanzanian S.mutans strains MM3 and MM24 and one Tanzanian A. viscosus strain MM13 were used for this purpose. The basic diet consisting of 32% skim-milk, 7% yeast extract and 1% soy bean oil was supplemented with either 10% lactose and 50% corn flour, or 10% glucose and 50% corn flour, or 60% amylum or 60% wheat flour. S. mutans and A. viscosus were enumerated twenty days after inoculation. S. mutans counts were high irrespective of the dietary regime. A. viscosus counts in the glucose, lactose and amylum groups were of the same magnitude and significantly higher than those of the wheat flour group. The hypothesis that the establishment of S. mutans in sucrose free diets could be facilitated by the extracellular polysaccharides produced by A. viscosus was not supported by the present data. The finding that S. mutans can establish in high number in dental plaque of SPF rats in the absence of sucrose corroborates previous reports indicating high S. mutans counts in African populations with a low sucrose intake.

Actinomyces viscosus↗
PubMed1992

Cell-bound peptidase activities of Treponema denticola ATCC 33520 in continuous culture.

The oral spirochaete Treponema denticola ATCC 33520 was grown at a mean generation time of 10 h in anaerobic continuous culture in a serum- and carbohydrate-free medium at pH 7.0. The extracellular proteolytic activities of this spirochaete were then investigated by incubating washed cells with 68 2-naphthylamide derivatives of the Extended API System. Chymotrypsin-like, trypsin-like, elastase-like and iminopeptidase activities were demonstrated. The phenylalanine peptidase or chymotrypsin-like activity of T. denticola ATCC 33520, estimated with N-succinyl-L-phenylalanyl-L-leucyl-L-phenylalanine-thiobenzyl ester (SPLP) had a pH optimum at pH 8.5, a specific activity of 36.6 nmol min-1 (mg dry wt)-1 and was inhibited only slightly by HgCl2. The trypsin-like activity, estimated with benzoyl-DL-arginine-7-amido-4-methylcoumarin (BAMC), had a pH optimum at pH9, and a specific activity of 0.3 nmol min-1 (mg dry wt)-1; inhibition by HgCl2 indicated the involvement of active thiol groups. The activity should preferably be termed arginine peptidase activity, according to the carboxy-terminal amino acid of the test substrate. The extracellular proline peptidase activity, estimated with L-proline-7-amido-4-methylcoumarin. HBr (PRAMC), had an activity of 1.5 nmol min-1 (mg dry wt)-1, an optimum at pH 8.5 and the properties of a thiol protease. The main cell-bound and extracellular active peptidase activities of fast-growing cells of T. denticola ATCC 33520 are phenylalanine peptidase, proline peptidase, arginine peptidase and an oligopeptide-dependent alanine peptidase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopeptidases↗
PubMed1992

Hemagglutination activity of Treponema denticola grown in serum-free medium in continuous culture.

Hemagglutination by different Treponema denticola strains was observed for erythrocytes of human, horse, bovine, and rabbit origin. The growth of T. denticola ATCC 33520 in serum-free medium in continuous culture enabled us to study the hemagglutinating activity of freshly harvested spirochetes of a defined physiological status. The hemagglutinating activity was cell bound and not related to motility or appendages, such as fimbriae. The activity was destroyed by proteolytic enzymes, heat, and alkylation, indicating that the agglutinin is of a proteinaceous nature. In addition, periodate oxidation of the spirochetes indicated the involvement of carbohydrate groups. Microscopic inspection of the hemagglutination mixtures at the titration endpoints revealed that only a part of the spirochete population was involved in the hemagglutination process. The hemagglutinating activity was found to be growth phase related. The activity was blocked by serum, while of all tested amino acids and carbohydrates, only sialic acid blocked the activity at low concentrations. In conclusion, we found a hemagglutinating activity in T. denticola which was cell bound and growth phase related. The agglutinin may be a glycoprotein, like lectin, that recognizes sialic acid as a receptor.

Animals↗
PubMed1992

Mutans streptococci and lactobacilli in breast-fed children with rampant caries.

This study aimed to investigate the prevalence of selected components of the oral microflora in breast-fed children who developed rampant caries (resembling nursing caries) under hitherto unexplained circumstances. Dental plaque and saliva samples were collected from breast-fed children, aged between 1 and 2.5 years, with and without rampant caries. Mutans streptococci and lactobacilli were isolated from dental plaque of all children with rampant caries and from most caries-free children. None of the colonies of mutans streptococci resembled those of Streptococcus sobrinus. The mean counts of the mutans streptococci and lactobacilli were 100-fold higher in plaque samples from children with rampant caries as compared with caries-free children. No difference could be found between the numbers of mutans streptococci in plaque overlaying cavities and that from adjacent sound enamel. In contrast, the counts of lactobacilli in plaque were approximately 100-fold higher from cavities than from sound surfaces. The levels of mutans streptococci in saliva were directly related to the presence of rampant caries. The results show that caries-free and caries-active breast-fed children, aged 1 to 2.5 years, harbour mutans streptococci and lactobacilli on their teeth. Rampant caries in these children can occur in the absence of nursing bottles or any other feeding abuse during weaning and in the presence of an aciduric plaque microflora, as has been reported for children with nursing bottle caries.

Breast Feeding↗
PubMed1992

[Individual risk assessment of caries].

The estimation of individual caries risk factors and the related preventive treatment in the dental practice are discussed. Salivary counts of mutans streptococci and lactobacilli reflect the bacteriological attack (mutans streptococci) and sugar intake (lactobacilli). Caries resistance can be estimated by measurement of the salivary secretion rate and buffer capacity. Treatment of high caries risk patients should be directed against etiological factors. Salivary flow rates and buffer capacity can be stimulated by daily (sugar-free) gum-chewing. For the use of fluoridated toothpaste and sugar intake the dentist is dependent upon the cooperation of the patient. The bacteriological factor in the caries process can be suppressed by application of chlorhexidine varnish.

Anti-Infective Agents, Local↗
PubMed1991

Comparison of peptidase, glycosidase and esterase activities of oral and non-oral Treponema species.

The enzyme profiles of 20 oral and non-oral Treponema strains were investigated using an API ZYM Complete Research kit. The test included 10 2-naphthyl derivatives of fatty acids, 20 p-nitrophenol derivatives of carbohydrates and 60 2-naphthylamide derivatives of amino acids and peptides. The oral Treponema species investigated were T. denticola, T. vincentii and T. Pectinovorum. The non-oral species examined were T. phagedenis, T. hyodysenteriae and intestinal spirochaetes of human and chicken origin. Esterase activities on C5 to C10 fatty acids were common among different Treponema species. Glycosidase activities were infrequently observed in T. vincentii, T. pectinovorum and T. phagedenis Reiter strain. Arabinosidase, lactosidase and xylosidase activity was observed in the T. hyodysenteriae strains but alpha-L-fucosidase activity was found only in T. denticola and T. phagedenis. More exo- and endo-peptidase activities were found in T. denticola than in other species. The enteropathogenic T. hyodysenteriae isolates had a very low proteolytic profile. Dipeptidyl prolyl amidase activity was observed in all species except in the T. phagedenis Reiter strain and the avian intestinal spirochaetes. The enzyme profiles did not discriminate between oral and non-oral Treponema species.

Amino Acid Sequence↗
PubMed1991

Comparison of the antimicrobial effect of the application of chlorhexidine gel, amine fluoride gel and stannous fluoride gel in debrided periodontal pockets.

The clinical and microbiological effect of locally-applied chlorhexidine gel 2%, amine fluoride gel 1.25%, stannous fluoride gel 4% or placebo gel in 40 periodontal pockets of 10 patients were studied. The gels were applied 3 x within 10 min. after mechanical debridement of the pockets. The treatment effect on the subgingival microflora was evaluated by microscopic and culture studies of the subgingival plaque samples. In addition, supragingival plaque, bleeding after probing and probing pocket depth were scored. Examination were carried out before and during a period of 36 weeks after treatment. At the start, the cultured microflora consisted mainly of anaerobic Gram-positive bacteria. Following treatment, the clinical parameters were significantly reduced. Concomitantly, the %s of spirochetes, motile rods and non-motile rods decreased significantly. A significant decrease was also found in the total anaerobic count, whereas the facultative counts remained at the same level found before treatment. This suggested that the treatment resulted in a mainly facultative subgingival microflora. The % Gram-negative rods showed a significant reduction after treatment, but returned to base line at week 12. Statistical analysis of the bacteriological and clinical examinations failed to demonstrate any significant differences between the 4 treatment groups. Thus, in comparison to the placebo gel, subgingival application of chlorhexidine gel 2%, amine fluoride gel 1.25% or stannous fluoride gel 4% did not augment the effect of mechanical debridement on bacteriological and clinical parameters during the experimental period of 36 weeks. However the indicated treatments resulted in a facultative subgingival microflora which is compatible with the host.

Adult↗
PubMed1991

Short-term bactericidal activity of chlorhexidine gel, stannous fluoride gel and amine fluoride gel tested in periodontal pockets.

The short-term bactericidal effect of 2% chlorhexidine gel, 4% stannous fluoride gel or amine fluoride gel containing 1.25% fluoride on the subgingival microflora was determined in 40 periodontal pockets of 10 patients. The antimicrobial gels or placebo gel were applied in 5-9 mm deep periodontal pockets 3 times within 10 min. Before and 30 min after the applications, samples were taken of the subgingival microflora for determination of the total number of bacteria as well as the number of black pigmented Bacteroides. Reductions of the total number of bacteria were found in all test groups. The reductions found in the pockets treated with chlorhexidine gel or stannous fluoride gel were significantly greater than the reduction found in the pockets treated with a placebo gel. A significant reduction of black-pigmented Bacteroides was found after treatment with chlorhexidine gel or amine fluoride gel. It is concluded that 2% chlorhexidine gel or 4% stannous fluoride gel has a more than 99% reduction effect on the microflora of periodontal pockets within 30 min after application.

Adult↗
PubMed1991

[Microbiological tests of patients at risk].

The Streptococcus- and Lactobacillus-tests available in The Netherlands for the selection of patients at risk are discussed. Attention is paid tot the calculation of sensitivity, specificity and predictive value of microbiological tests. Although the predictive values or diagnostic power of the saliva tests are rather low, the use of such tests in dental practice is advocated.

Colony Count, Microbial↗
PubMed1990

Spirochetes in early lesions of necrotizing ulcerative gingivitis experimentally induced in beagles.

The presence of spirochetes and other bacteria during the induction of necrotizing ulcerative gingivitis (NUG) in beagle dogs was studied by transmission electron microscopy. NUG was induced by application of dental debris from diseased dogs to 4 beagles treated with corticosteroid. Biopsies of interdental papillae were collected during a period of 7 weeks. Spirochetes and other bacteria were observed in enlarged intercellular spaces between non-keratinized epithelial cells. Intracellular bacteria were found with and without surrounding vesicular spaces. The invasive spirochetes were mainly intermediately sized and of flagellar "4-8-4" configuration or higher. Bacterial invasion of the sulcular epithelium occurred before clinical evidence of NUG could be observed. It is concluded that invasion by intermediate spirochetes and other bacteria plays a role in initiating ulcerative gingivitis in beagles.

Animals↗
PubMed1990

[Bacteriological tests in periodontal practice].

The specificity, sensitivity and predictive value of bacteriological tests in periodontology are reviewed. It is stated that the bacteriological aim in periodontal therapy is the change of the subgingival flora in a facultative flora which is compatible with the host. Bacteriological tests can be used to identify indicator bacteria. It is discussed how a microscopical or a bacteriological identification test can support periodontal diagnoses and indication of periodontal therapy.

Aggregatibacter actinomycetemcomitans↗
PubMed1990

Clearance of a topically applied fluorescein gel from periodontal pockets.

The clearance of a fluorescein gel applied with an irrigation technique in periodontal pockets was studied. In order to evaluate the time a drug remains in a periodontal pocket, the alteration in concentration of this drug in a given time period was investigated. After application of the gel in 4 pockets of 10 patients, samples were taken from 1 of the 4 pockets at 5, 10, 20 and 40 min. The results show that in the 1st phase, directly after application, most of the gel disappeared from the pocket, while in the 2nd phase, the fluorescein gel is washed out with a calculated 50% reduction time of 12.5 min. The rapid clearance of the gel observed after irrigation might provide a partial explanation of the minor effect of pocket irrigation on the subgingival microflora.

Administration, Topical↗
PubMed1989

Bactericidal concentrations of chlorhexidine-digluconate, amine fluoride gel and stannous fluoride gel for subgingival bacteria tested in serum at short contact times.

In vitro inhibitory and bactericidal concentrations in serum of chlorhexidine-digluconate, amine fluoride gel, stannous fluoride gel, stannous fluoride, metronidazole and amoxicillin were determined against Bacteroides gingivalis, Bacteroides intermedius, Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans and Capnocytophaga sputigena. The minimal inhibitory concentration was assessed by the agar dilution technique. The killing curves and minimal bactericidal concentration of the antimicrobial agents in inactivated bovine serum were determined after 5, 10, 20 and 60 minutes contact time. The minimal inhibitory concentration varied amongst the tested bacteria. A concentration of 128 micrograms/ml chlorhexidine digluconate, 20 mg/ml amine fluoride gel, 1 mg/ml stannous fluoride, 128 micrograms/ml metronidazole and 4 micrograms/ml amoxicillin inhibited the growth of the tested species. The minimal bactericidal concentration in serum for B. gingivalis, B. intermedius, F. nucleatum, A. actinomycetemcomitans and C. sputigena after 10 min contact time was 5 mg/ml for chlorhexidine digluconate and 100 mg/ml for amine fluoride gel. A concentration of 200 mg/ml stannous fluoride gel in serum was bactericidal for the tested species after 10 min contact time, with exception of F. nucleatum.

Actinobacillus↗
PubMed1987

Microbial and clinical measurements of periodontal pockets during sequential periods of non-treatment, mechanical debridement and metronidazole therapy.

Microbial and clinical parameters were studied in 11 subjects with chronic inflammatory periodontitis. 2 periodontal pockets per subject were studied longitudinally. The microbial parameters included counts of different subgingival micro-organisms by dark field microscopy, counts of the total colony forming units (c.f.u.) on anaerobic blood agar, the facultative anaerobic counts and counts of black-pigmented Bacteroides, Fusobacterium and E. corrodens. The clinical parameters were probing pocket depth, bleeding after probing and crevicular fluid production. Clinical and microbial observations were compared during 3 consecutive periods of non-treatment, debridement and metronidazole therapy. The experimental sites were debrided by deep scaling while no debridement was carried out at the control sites. The effect of this treatment was studied over a period of 3 months. Then, at the experimental sites, a 2nd session of debridement was followed by administration of metronidazole. The effect of metronidazole alone and combined with mechanical debridement was studied during a subsequent 3-month period. The disease activity did not correlate with the microbial parameters and was evident in the presence as well as in the absence of black-pigmented Bacteroides. A single session of subgingival debridement resulted in significant reductions in probing depth, spirochetes, motile organisms, black-pigmented Bacteroides and E. corrodens. Repopulation of the subgingival sites was observed. However, the composition of the subgingival microbiota remained significantly changed during the 3 months after debridement. The re-isolation of the same Bacteroides-species and the same B. gingivalis type after treatment indicated an outgrowth of micro-organisms remaining at these sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

The effect of subgingival debridement with hand and ultrasonic instruments on the subgingival microflora.

The effect of hand or ultrasonic instrumentation on the subgingival microflora of periodontal pockets was investigated. Pockets with probing depths of 6-9 mm were selected in 12 patients and were randomly assigned per patient to the experimental and control groups. After oral hygiene instruction, instrumentation of the experimental pockets was carried out either by ultrasonic or by hand instruments in a split-mouth design. The treatment effect on the subgingival microbiota was evaluated by microscopic and culture studies of subgingival plaque samples, while in addition, supragingival plaque, bleeding after probing and probing pocket depth were scored. Examinations were carried out before and 7, 21 and 49 days after treatment. The hand and ultrasonic treatments were equally effective in reducing probing pocket depths and bleeding scores. At the end of the experimental period, the probing depths of 54% of the hand-treated pockets and 43% of the ultrasonic-treated pockets were reduced to 4 mm or less while the bleeding scores were reduced to 29% and 22%, respectively. The analysis of microscopical and cultural data did not show any differences between hand and ultrasonic debridement. Both treatments reduced the microscopical counts of rods, spirochetes and motiles and reduced the total colony-forming units and number of black-pigmented Bacteroides and Capnocytophaga, resulting in a subgingival microbiota consistent with periodontal health.

Adult↗
PubMed1987

Keratinolytic activity of cutaneous and oral bacteria.

A test was developed to measure the keratinolytic activity of cutaneous and oral bacteria. Keratin, labeled with fluorescein isothiocyanate, was used in a phosphate buffer (pH 7.2) with 1 mM dithiothreitol. The degradation of keratin was estimated by measuring the fluorescence of the degradation products in the supernatant of the reaction mixtures in a luminescence spectrometer. Several oral and cutaneous bacteria were investigated: Bacteroides gingivalis, Bacteroides intermedius, Treponema denticola, Actinomyces odontolyticus, Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus saprophyticus, Brevibacterium epidermidis, Brevibacterium lines, Corynebacterium glutamicum, Corynebacterium minutissimum, Corynebacterium ovis, and Rhodococcus equi. The dermatophyte Trichophyton rubrum was used as a control organism. The test offered a simple and quantitative method for the estimation of keratin degradation and enabled us to show keratinolytic activity in Trichophyton rubrum, S. epidermidis, S. haemolyticus, B. linens, B. epidermidis, Bacteroides gingivalis, and Treponema denticola. The keratinolytic activity was cell bound and heat sensitive. The presence of dithiothreitol stimulated the degradation of keratin to mainly high-molecular-weight products.

Bacteria↗