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At least 163 records · Page 9Linked to original sources
PubMed2000

Biological and molecular characterization of cellular differentiation in Tetrahymena vorax: a potential biocontrol protozoan.

Tetrahymena vorax (T. vorax) is an indigenous fresh water protozoan with the natural biological potential to maintain a specific aquatic microbial flora by ingesting and eliminating specific microorganism. To investigate the molecular mechanisms controlling Tetrahymena vorax (T. vorax) cellular differentiation from a small-mouth vegetative cell to a voracious large-mouth carnivore capable of ingesting prey ciliates and bacteria from aquatic environments, we use DNA subtraction and gene discovery techniques to identify and isolate T. vorax differentiation-specific genes. The physiological necessity for one newly discovered gene, SUBII-TG, was determined in vivo using an antisense oligonucleotide directed against the 5' SUBII-TG DNA sequence. The barriers to delivering antisense oligonucleotides to the cytoplasm of T. vorax were circumvented by employing a new but simple procedure of processing the oligonucleotide with the differentiation stimulus, stomatin. In these studies, the antisense oligonucleotide down-regulated SUBII-TG mRNA expression, and blocked differentiation and ingestion of prey ciliates. The ability to down-regulate SUBII-TG expression with the antisense oligonucleotide suggests that the molecular mechanisms controlling the natural biological activities of T. vorax can be manipulated to further study its cellular differentiation and potential as a biocontrol microorganism.

Amino Acid Sequence↗
PubMed2006

Punica granatum (pomegranate) extract is active against dental plaque.

In the present work, we studied the effect of the hydroalcoholic extract (HAE) from Punica granatum (pomegranate) fruits on dental plaque microorganisms. The study was conducted on 60 healthy patients (33 females and 27 males, with age ranging from 9 to 25 years) using fixed orthodontic appliances, and randomly distributed into 3 groups of 20 patients each. The first group (control) used distilled water, while the second and third groups used chlorhexidine (standard) and HAE as mouth-rinses, respectively. The dental plaque material was collected from each patient, before and after a 1-min mouth-rinse with 15 ml of either distilled water, chlorhexidine or HAE. In both dental plaque collections, the material was removed from patients without oral hygiene, for 24 h (no tooth brushing). Dental plaque samples were diluted in phosphate buffered saline (PBS) plated on Mueller-Hinton agar, and incubated for 48 h, at 37 degrees C. Results, expressed as the number of colony forming units per milliliter (CFU/mL), show that the HAE was very effective against dental plaque microorganisms, decreasing the CFU/ml by 84% (CFU x 10(5)), before mouth-rinse: 154.0 +/- 41.18; after mouthrinse: 25.4 +/- 7.76). While similar values were observed with chlorhexidine, used as standard and positive control (79% inhibition), only an 11% inhibition of CFU/ml was demonstrated in the distilled water group, negative control (CFU x 10(5)), before mouth-rinse: chlorhexidine, 208.7 +/- 58.81 and distilled water, 81.1 +/- 10.12; after mouth-rinse: chlorhexidine, 44.0 +/- 15.85 and distilled water, 71.9 +/- 8.68). The HAE presented also an antibacterial activity against selected microorganisms, and may be a possible alternative for the treatment of dental plaque bacteria.

Adolescent↗
PubMed1997

Mutans streptococci and incipient caries adjacent to glass ionomer cement or resin-based composite in orthodontics.

Levels of mutans streptococci in plaque adjacent to orthodontic brackets retained with a glass ionomer cement (GIC) (Ketac-Cem) and a resin-based composite (CR) (Concise) were investigated, using the split mouth technique in 11 patients who, before treatment, had more than 10(5) CFU of these microorganisms. After full-term orthodontic treatment (mean 9.5 months), the percentage of mutans streptococci of total CFU count in plaque was lower adjacent to GIC-retained brackets (mean 3.9) than adjacent to CR-retained brackets (6.7), but the difference was not statistically significant. Two subjects harbored S. sobrinus. These subjects were the only ones who developed incipient caries during the orthodontic treatment. Incipient lesion formation occurred only adjacent to CR-retained brackets. This suggests that in patients who have relatively high salivary levels of mutans streptococci before treatment and especially in those who harbor S. sobrinus, the use of GIC for bonding may prevent incipient caries formation during orthodontic treatment.

Adolescent↗
PubMed1985

Nine-year microflora study of an isolator-maintained immunodeficient child.

A male child, maintained in a controlled environment, was monitored each month for bacteria, yeasts, and filamentous fungi recovered from the mouth, nasal passages, feces, and nine body surface sites. Three natural microbial categories became apparent. Incident microorganisms were recovered from within the isolator but did not establish permanent residence. Of the 53 incident types isolated, 20 were filamentous fungi and 4 were yeasts. Some genera, such as Fusobacterium, Lactobacillus, Neisseria, and Rothia, which were commonly found in the reference group, did not become permanent inhabitants. Transient microorganisms were repeatedly recovered but could not be demonstrated within the isolated environment at the end of the study. The loss of only a few of the 19 transient species could be associated with antimicrobial therapy. Permanent microorganisms consisted of Pencillium citrinum and 17 bacterial types, of which alpha-hemolytic streptococci, Staphylococcus edpidermidis subgroups II and V, Micrococcus groups 1 and 2, Clostridium bifermentans, and Propionibacterium acnes were recovered throughout the entire 9 years of the study. The number of CFUs recovered from each sample type was generally not unlike that from the reference group of healthy male adults. Also, the number of different aerobic species recovered from the feces was within the normal range of that of the reference group. In contrast, the number of different species recovered from all other samples was less than that commonly found in the reference group.

Aerobiosis↗
PubMedDate not supplied

[Evaluation of the microbial burden using rinsing of the oral cavity in patients undergoing bone marrow transplantation].

We report the methodology and the results of our research on the total microbic charge of the oral cavity carried out in 35 (thirty-five) patients undergoing bone marrow transplant and selective decontamination at the Bone Marrow Transplant Unit Perugia, between July 1985 and December 1988. The specimens, obtained by washing the oral cavity for 15 seconds with 10 ml of sterile distilled water, were taken from each patient during his stay in the Laminar Air Flow Room (from day -7 to day +28 of the transplant). The first sample was taken before starting the selective decontamination and the microbiological controls were carried out weekly. The quantitative determination of the microbic charge was made by diluting and plating, while selective media for gram-positive and gram-negative microorganisms were used for the qualitative evaluation. The results obtained prove the effectiveness of the mouth-wash method as an instrument for the evaluation of microbial contamination of the "mouth"-area, since it determines the oral microbic flora by standardized counting and testing methods which are simple to use and give rapid and reliable results. Furthermore, this method has proved to be especially useful for studying the effectiveness of the decontamination and chemoprophylaxis treatments carried out on the patients undergoing bone marrow transplants.

Anti-Bacterial Agents↗
PubMed1977

Production and origin of oral malodor: a review of mechanisms and methods of analysis.

Organoleptic studies indicate that the oral cavity is usually the principal source of physiologic malodor associated with the early morning halitosis. In all individuals, regardless of the age or health status of the oral tissues, the most intense oral malodor is exhibited after prolonged periods of reduced saliva flow and abstinence from food and liquid. This results from normal metabolic activity in the oral cavity and is accentuated in cases with periodontal involvement. Physiologic oral malodor is transient in duration as it can be controlled to varying degrees in most individuals by oral hygiene measures, such as tooth brushing, dental prophylaxis, tongue scraping and rinsing with antiseptic mouth washes. Experimental evidence strongly suggests that putrefaction of sulphur-containing proteinaceous substrates by predominantly gram-negative oral microorganisms is the primary cause of oral malodor. Optimum putrefactive activity occurs in low carbohydrate environment, physiological pH, and anaerobic conditions. Salivary sediment containing the exfoliated epithelial cells is the primary source of substrate which exists in a disulphide state. Proteolysis and reduction of disulphide bonds precedes the formation of odor. The odor intensity of putrescent saliva and plaque head-space vapor has been correlated with the concentration of volatile sulphur compounds consisting of hydrogen sulphide, methyl mercaptan, dimethyl sulphide and dimethyl disulphide. Except for dimethyl disulphide, the same sulphur-containing compounds have been found in mouth air of all tested individuals. Hydrogen sulphide and methyl mercaptan emanate an offensive putrid odor and account for approxiamtely 90% of the total sulphur content of mouth air. In half of the population tested, methyl mercaptan and hydrogen sulphide content of early morning mouth air is sufficiently high to account for the oral malodor. Brushing studies indicate that both plaque and tongue are important sources of malodor with most of the odor emanating from the dorso-posterior surface of the tongue. None of the gas chromatographic or mass spectrometric analyses have detected the presence of amines, indole, or skatole in the head-space, mouth air, or breath vapor samples.

Amino Acids↗
PubMed1976

A method for studying adherence of oral streptococci to solid surfaces.

The adherence of different streptococci to test pieces of glass, human enamel and whale dentin carried in the mouth or immersed in saliva or bacterial suspensions was studied by examining the number and frequency of microorganisms which were selectively desorbed by a standardized washing technique. The results obtained from in vivo and in vitro experiments were similar in principle. The proportion of streptococci obtained in the first washing resembled that found in the saliva, but with more vigorous washing the proportion of S. sanguis increased while that of S. salivarius decreased. This illustrates that different microorganisms can attach to solid surfaces with different strengths. The applicability of the method was tested by treating dentin surfaces with fluoride solutions and by incorporating sucrose in the test solution. The fluoride treatment reduced while the sucrose addition increased the number of streptococci which could be removed from the surfaces.

Bacteriological Techniques↗
PubMedDate not supplied

[Microbacterium oxydans, a symbiont of Djungarian hamster, displaying probiotic properties].

A resident microorganism (strain Kho-17) was isolated from secretions of the specific glandular structures at the angles of mouth of Djungarian hamster (Phodopus campbelli). According to cultural, morphological, and physiological properties as well as to the phylogenetic analysis basing on the sequences of 16S rRNA gene and analysis of the cell wall the strain was assigned to the species Microbacterium oxydans. The bacterium isolated displayed probiotic properties when administered orally as a suspension of live cells for 20 days to Syrian hamster (Mesocricetus auratus), which manifested themselves in increased body weight and weights of several organs and stimulation of both cell-mediated and humoral immunities.

Animals↗