Quantum resonances in selective rotational excitation of molecules with a sequence of ultrashort laser pulses.

We experimentally investigate the effect of quantum resonance in the rotational excitation of the simplest quantum rotor--a diatomic molecule. Using the techniques of high-resolution femtosecond pulse shaping and rotational state-resolved detection, we measure directly the amount of energy absorbed by molecules interacting with a periodic train of laser pulses, and study their dependence on the train period. We show that the energy transfer is significantly enhanced at quantum resonance, and use this effect to demonstrate selective rotational excitation of two nitrogen isotopologs, (14)N(2) and (15)N(2). Moreover, by tuning the period of the pulse train in the vicinity of a fractional quantum resonance, we achieve selective rotational excitation of para- and ortho-isomers of (15)N(2).

Control of molecular rotation with a chiral train of ultrashort pulses.

Trains of ultrashort laser pulses separated by the time of rotational revival (typically, tens of picoseconds) have been exploited for creating ensembles of aligned molecules. In this work we introduce a chiral pulse train--a sequence of linearly polarized pulses with the polarization direction rotating from pulse to pulse by a controllable angle. The chirality of such a train, expressed through the period and direction of its polarization rotation, is used as a new control parameter for achieving selectivity and directionality of laser-induced rotational excitation. The method employs chiral trains with a large number of pulses separated on the time scale much shorter than the rotational revival (a few hundred femtosecond), enabling the use of conventional pulse shapers.

Isolation and characterization of microsatellite loci in the beaver (Castor canadensis).

We have isolated and characterized 10 microsatellite loci in the beaver (Castor canadensis). Sixty individuals from southern and central Illinois were screened at each locus. All loci exhibited moderate levels of polymorphism, ranging from five to 13 alleles per locus with average heterozygosity ranging from 0.317 to 0.867. Locus Cca5 deviated significantly from HWE (P < 0.001). The locus pair Cca4/Cca5 was shown to be in linkage disequilibrium in southern Illinois, but not in the central Illinois population. The remaining eight loci will be useful in investigations of mating and kinship patterns in beaver populations in Illinois.

Retrieval of biofilms from the oral cavity.

With the use of the removable stents or bonded enamel piece models with or without a continuous bacterial layer, many in vitro or in vivo studies can be initiated. For example, studies on salivary pellicle formation, surface characteristics of biomaterials as they affect plaque development, antiplaque agents, the dynamics of adhesion of bacteria, interspecies adhesion of bacteria, the colonization of bacteria, the dynamics of bacterial growth in vivo, and the succession of growth in older supragingival plaques can be carried out.

New and clarified safe harbors may ease certain provider transactions.

The recent final rule issued by the Office of Inspector General adds eight new safe harbors to the Federal antikickback statute to the 13 currently in force. This final rule also clarifies six of the original 11 safe harbors published in 1991. In general, safe-harbor provisions to the antikickback statute specify payments that will not provide a basis for criminal prosecution or for exclusion from the Medicare or state healthcare programs. While safe harbors are very narrow and transactions must meet each requirement of an applicable safe harbor to be protected, the new final rule should help facilitate certain financial arrangements between provider organizations. It may, however, prohibit other arrangements.

A comparison of three methods for detecting Candida albicans in patients with Sjögren's syndrome.

OBJECTIVE: An immediate chairside technique (Latex Candida) for the detection of Candida albicans was compared with a simple tube culturing technique (Oricult) and the traditional laboratory culturing technique in patients with Sjögren's syndrome. METHOD AND MATERIALS: Subjects with primary (n = 9) and secondary (n = 9) Sjögren's syndrome (mean age of 56.7 years; all female) and an age- and sex-matched group of control subjects (n = 9) were selected. Three different methods for culturing Candida albicans were performed for each subject. One culturette was plated on a trypticase soy-agar streptomycin-vancomycin medium plate and incubated for 48 hours at 37 degrees C. Another swab was plated on a reagent paper with the Latex Candida test kit. The third swab was placed in a culture media tube using the Oricult kit and incubated for 48 hours at 37 degrees C. RESULTS: All three techniques indicated a significant difference in the prevalence of Candida between the control group and both Sjögren's groups. The Latex Candida technique indicated that 78% of all Sjögren's subjects were positive for Candida, while the other two tests indicated that 83% were positive. CONCLUSION: The Latex Candida technique was comparable to Oricult and streptomycin-vancomycin culturing techniques for negative results and was correctly positive for 90% of cases.

Candida albicans levels in patients with Sjögren's syndrome before and after long-term use of pilocarpine hydrochloride: a pilot study.

OBJECTIVE: The purpose of this study was to compare the quantities of oral Candida albicans in patients with primary and secondary Sjögren's syndrome before and after the use of orally administered pilocarpine hydrochloride for 1 year. METHOD AND MATERIALS: Twelve female subjects with primary (n = 4) and secondary (n = 8) Sjögren's syndrome (mean age +/- SEM = 56.7 +/- 5.7 years) were enrolled in the study, after meeting rigid enrollment criteria. Oropharyngeal collection of samples and culturing was performed on each subject. Cultures specific for Candida albicans were plated into a culture media tube using the Oricult kit and also by serial dilutions and plating by a streptomycin-vancomycin technique. Cultures were incubated for 48 hours at 37 degrees C. The subjects used 5 mg of pilocarpine hydrochloride, administered orally three times daily, for 1 year, after which both of the Candida cultures were repeated. None of the subjects used antifungal medications, none smoked, and all were dentate. RESULTS: There was a significant difference in the prevalence of Candida after the use of pilocarpine hydrochloride for both groups. At the start of the study, 75% of all subjects were positive for Candida. Following the use of pilocarpine, 25% had positive cultures. There was also a decrease in the prevalence of clinical manifestations of infection from 75% of subjects to 25%. There was a significant decrease in the numbers of Candida cultured following the use of pilocarpine. CONCLUSION: Long-term administration of pilocarpine hydrochloride resulted in a significant reduction in Candida albicans colonization in patients with primary or secondary Sjögren's syndrome.

Prevalence, density, and manifestations of oral Candida albicans in patients with Sjögren's syndrome.

OBJECTIVE: Various investigators have reported a high prevalence of oral Candida species in patients with salivary gland dysfunction (SGD). The purpose of this study was to assess the prevalence of oral Candida albicans, its oral manifestations, and to compare the number of colony-forming units of Candida albicans in patients with primary Sjögren's syndrome and secondary Sjögren's syndrome with the whole unstimulated salivary flow rate in each group. METHOD: An age-sex-matched group of control subjects was selected for comparison. Oropharyngeal collection of samples and culturing was performed on each subject. Quantitative cultures specific for Candida albicans were performed. RESULTS: The frequency distribution indicated that > 80% of all SS subjects were positive for Candida albicans vs. none of the controls. The most common lesion was angular cheilitis followed by chronic atrophic candidiasis. The subjects with Sjögren's syndrome also demonstrated significantly high numbers of Candida albicans colony-forming units. CONCLUSIONS: This study indicates significantly higher Candida albicans colonization in patients with primary or secondary Sjögren's syndrome as compared to a control population. Candida albicans colonization was higher in patients with secondary Sjögren's syndrome than in patients with primary Sjögren's syndrome; however, the amount of Candida albicans was not universally relative to salivary flow.

Growth dynamics in a natural biofilm and its impact on oral disease management.

Measurements of the microbial growth dynamics in natural biofilm communities are almost non-existent. In a recent study, the biofilm formation on teeth was examined. A previously unknown active period of bacterial division occurred at a certain density of plaque bacteria on tooth enamel. The density-dependent cell-division phase of plaque formation contributed 90% of the biomass in the first 24 hrs of plaque formation. This suggested that growth was induced by the bacteria. In vitro assays were developed for rapid evaluation of the growth of surface-linked bacteria by the measurement of cellular components associated with growth on a per cell per time basis. Cell-free supernatants (termed START) of media in contact with bacteria were assayed for their effects on DNA synthesis and other cellular components associated with growth. START was found to increase the incorporation of [3H-methyl]-thymidine on a per cell per time basis, when compared with media not in contact with bacteria. Additional in vivo studies and in situ-based models of complex biofilms are needed if all of the mechanisms involved in the rapid accumulation of biofilm bacteria on teeth and other surfaces are to be understood.

Adherence, accumulation, and cell division of a natural adherent bacterial population.

Developing dental bacterial plaques formed in vivo on enamel surfaces were examined in specimens from 18 adult volunteers during the first day of plaque formation. An intraoral model placing enamel pieces onto teeth was used to study bacterial plaque populations developing naturally to various cell densities per square millimeter of surface area of the enamel (W. F. Liljemark, C. G. Bloomquist, C. L. Bandt, B. L. Philstrom, J. E. Hinrichs, and L. F. Wolff, Oral Microbiol. Immunol. 8:5-15, 1993). Radiolabeled nucleoside incorporation was used to measure DNA synthesis concurrent with the taking of standard viable cell counts of the plaque samples. Results showed that in vivo plaque formation began with the rapid adherence of bacteria until ca. 12 to 32% of the enamel's salivary pellicle was saturated (ca. 2.5 x 10(5) to 6.3 x 10(5) cells per mm2). The pioneer adherent species were predominantly those of the "sanguis streptococci." At the above-noted density, the bacteria present on the salivary pellicle incorporated low levels of radiolabeled nucleoside per viable cell. As bacterial numbers reached densities between 8.0 x 10(5) and 2.0 x 10(6) cells per mm2, there was a small increase in the incorporation of radiolabeled nucleosides per cell. At 2.5 x 10(6) to 4.0 x 10(6) cells per mm2 of enamel surface, there was a marked increase in the incorporation of radiolabeled nucleosides per cell which appeared to be cell-density dependent. The predominant species group in developing dental plaque films during density-dependent growth was the sanguis streptococci; however, most other species present showed similar patterns of increased DNA synthesis as the density noted above approached 2.5 x 10(6) to 4.0 x 10(6) cells per mm2.

Human oral microbial ecology and dental caries and periodontal diseases.

In the human oral cavity, which is an open growth system, bacteria must first adhere to a surface in order to be able to colonize. Ability to colonize a non-shedding tooth surface is necessary prior to any odontopathic or periodontopathic process. Complex microbe-host relationships occur and must be studied before the commensal-to-pathogenic nature of the human indigenous oral flora can be understood. Medical pathogens, if present in the appropriate host, always produce specific disease. Caries and periodontal diseases are conditional diseases, requiring numbers of certain indigenous species at various sites, particularly the tooth surface. In the case of caries, the condition is related to sugar consumption. Periodontal disease/s may require certain host and environmental conditions, such as local environment or nutritional factors in gingival crevicular fluids. Nonetheless, critical numbers of certain indigenous species must be present in order for these diseases to occur. The aim of this review is to understand the acquisition of the indigenous oral flora and the development of human dental plaque. The role of the salivary pellicle and adherence of indigenous bacteria to it are critical first steps in plaque development. Bacterial interactions with saliva, nutritional factors, growth factors, and microbial physiologic processes are all involved in the overall process of microbial colonization.

Dental plaque development on defined streptococcal surfaces.

Coaggregations between bacterial species have been widely studied in vitro but not in the mouth. A new in vivo assay was used to measure the rate and composition of indigenous plaque formation onto bovine enamel chips covered with a continuous layer of bacteria. Chips were covered with Streptococcus oralis ATCC 10557, which coaggregated with many oral species, or Streptococcus gordonii S7, which did not coaggregate with these oral species, and placed in the mouth for 4 and 24 h. There were no differences in the number of most indigenous bacterial species isolated from the two streptococcal surfaces. However, the number of Actinomyces viscosus as a proportion of total Actinomyces spp. was significantly different on the two surfaces at 24 h. With the exception of Actinomyces naeslundii and A. viscosus removed from the S7 surface, all indigenous species increased significantly in number from 4 to 24 h, irrespective of the streptococcal surface. This study demonstrated that interbacterial coaggregation had only a limited effect on in vivo plaque development. Thus suggesting that environmental factors, growth or other adherence phenomena are dominant in in vivo plaque formation.

Comparison of the distribution of Actinomyces in dental plaque on inserted enamel and natural tooth surfaces in periodontal health and disease.

The distribution of Actinomyces naeslundii, Actinomyces viscosus and Actinomyces odontolyticus in healthy and diseased adult populations was studied in 3 different ways. First, supragingival plaque formation at 2 through 72 h was examined in 12 periodontally healthy adults using a removable pre-measured surface of enamel bonded to molars and premolars. Second, a cross-sectional examination of the composition of both supragingival and subgingival plaque of unknown age was conducted in 205 adults exhibiting periodontal health to moderate disease. Third, the effects of oral hygiene instruction and root planing on the subgingival microflora of a subset of 19 subjects with moderate periodontitis were examined. The evaluation of 12 adults revealed that the predominant species in early plaque formation (2, 4 and 8 h) was A. odontolyticus. A. viscosus and A. naeslundii were present in developing plaques in almost all subjects in 2-h plaque, but absent in half the subjects when 4-, 8- or 24-h plaque was examined. These two species significantly increased in numbers per mm2 enamel surface area in 48- and 72-h plaques. A. odontolyticus was not related to clinical signs of periodontal disease in 205 adults, and its subgingival proportions in plaque did not change following periodontal treatment of 19 individuals. A. naeslundii was found in significantly higher numbers in supragingival than subgingival plaques in the 205 adults examined. The mean proportion of A. naeslundii significantly decreased as the magnitude of probing depth and attachment loss increased. The proportions of A. naeslundii and A. viscosus were found to be significantly increased in subgingival plaques following periodontal treatment.

A follow-up case report of Actinobacillus actinomycetemcomitans in human periodontal disease.

The purpose of this investigation was to compare clinical and microbial parameters in a follow-up case report of adult subjects harboring Actinobacillus actinomycetemcomitans (Aa) with clinically matched subjects who did not have detectable Aa. 16 subjects with Aa and 16 subjects without Aa at the baseline examination were re-examined at an average of 46 months following collection of baseline data. Clinical measurements were recorded and subgingival plaque sampled and evaluated for microbial flora from each maxillary first molar. In 16 subjects with Aa at baseline, 4 sites in 3 subjects had detectable actinobacilli at the follow-up appointment. 26 sites in 13 individuals with Aa at baseline had a significantly increased gingival index at the follow-up visit (p less than or equal to 0.05), but there was no significant increase in probing depth or attachment loss. 32 sites in the 16 subjects without Aa at baseline still did not have detectable levels of this microorganism at the follow-up examination nor was there any significant difference between baseline and the follow-up appointment for the gingival index, probing depth and attachment level measurements. In subjects with Aa at baseline, 1 of 12 teeth without Aa and 5 of 20 teeth with Aa had been extracted prior to the follow-up visit. In this population group, having sites where Aa was detected, 6 of 9 teeth which had a probing depth greater than or equal to 5 mm were lost before the follow-up data collection appointment. In the control group, which did not have detectable Aa at baseline, 9 teeth with probing depths greater than or equal to 5 mm were not lost. These observations, although not proving, suggest in this population group, that deeper probing depths taken together with the presence of Aa may have placed an individual at greater risk of tooth loss.

Clustering of an outer membrane adhesin of Haemophilus parainfluenzae.

Haemophilus parainfluenzae synthesizes an outer membrane protein adhesin which mediates binding to oral streptococci, salivary pellicle, and neuraminidase-treated erythrocytes. An indirect gold labeling technique and immunoelectron microscopy verified the location of this outer membrane protein. Further, a clustering of gold particles was observed in irregular patches at the cell surface.

Purification and characterization of an outer membrane protein adhesin from Haemophilus parainfluenzae HP-28.

Outer membranes were isolated from Haemophilus parainfluenzae HP-28 by a mild extraction method followed by Sephadex G-150 gel filtration chromatography. The first peak (pool 1) recovered contained an activity which inhibited adherence of HP-28 cells to saliva-coated spheroidal hydroxyapatite. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of pool 1 revealed a dominant protein band of 34 kDa. The SDS-PAGE-purified 34-kDa protein was excised from the gel and used for antibody preparation in rabbits. The antiserum produced was analyzed by immunoblot and was shown to be monospecific for the 34-kDa protein. Anti-34-kDa protein antibody was purified from the rabbit antiserum by protein A-Sepharose 6MB affinity chromatography. This antibody was then cross-linked to protein A-Sepharose 6MB to construct a second affinity column. The 34-kDa proteins were purified from outer membranes by this affinity chromatography. The 34-kDa protein was homogeneous, as confirmed by SDS-PAGE, isoelectric focusing, and reverse-phase chromatography analyses. Fab and Fc fragments of the purified anti-34-kDa protein antibodies were prepared by papain digestion, followed by carboxymethyl cellulose chromatography. Fab fragments from the anti-34-kDa protein antibody and the affinity-purified 34-kDa protein both showed significant inhibition of parent H. parainfluenzae HP-28 cell adherence to experimental salivary pellicle and to Streptococcus sanguis SA-1.

Comparison of plaque microflora between Chinese and Caucasian population groups.

This investigation was designed to compare the predominant plaque micro-organisms from a Chinese group of patients exhibiting periodontitis with an age-, sex- and periodontal disease-matched Caucasian group of patients. In addition to race, the 2 population groups differed with respect to diet and oral hygiene habits, or effectiveness at removing plaque. Clinical measurements were determined along with an evaluation for micro-organisms in supragingival and subgingival plaque. Although the Chinese and Caucasian population groups were similar with respect to composition of micro-organisms in subgingival plaque, notable differences were observed in supragingival plaque. The Chinese group had higher mean proportions of spirochetes, motile rods. Fusobacterium spp. and dark-pigmented Bacteroides species, while the Caucasian group had higher mean proportions of cocci, total Actinomyces spp., A. viscosus and total Streptococcus spp. in supragingival plaque. The microbial differences observed in supragingival plaque may be explained at least in part, if not totally, by the higher plaque index scores of the Chinese versus Caucasian population groups.

Effect of neuraminidase on the adherence to salivary pellicle of Streptococcus sanguis and Streptococcus mitis.

Neuraminidase-sensitive adherence to experimental salivary pellicles was studied using eight strains of Streptococcus sanguis and five strains of Streptococcus mitis. Approximately 60% of the strains of each species showed significantly lower adherence to neuraminidase-treated versus untreated saliva-coated hydroxyapatite. In addition, the adherence of several of these streptococcal strains to saliva-coated hydroxyapatite and neuraminidase-treated saliva-coated hydroxyapatite was inhibited using galactose and N-acetyl-D-galactosamine. Results from these studies suggested that several salivary receptors mediate adherence of these species.

Utilization of a continuous streptococcal surface to measure interbacterial adherence in vitro and in vivo.

Cell-to-cell interactions are essential for the formation of dental plaque. A continuous layer of Streptococcus sanguis SA-1 cells fixed to a solid surface has been used to evaluate interactions among this bacterium, Haemophilus parainfluenzae, and Streptococcus sobrinus. S. sanguis cells were attached to a Falcon 3001 tissue culture plates or bovine enamel chips, coated with a biological adhesive. Scanning electron microscopy of the chips showed the streptococci as a contiguous surface. Radiolabeled bacteria were used to measure a second-species interbacterial adherence to the streptococcal-coated culture plates. Strains of H. parainfluenzae known to coaggregate (strain HP-28) and not to coaggregate (strains HP-42 and HP-80), in suspension with S. sanguis strain SA-1, were studied for adherence. Ten-fold-higher numbers of coaggregating strain HP-28 adhered in vitro to the streptococcal layer than did the non-coaggregating strains. S. sobrinus strain 6715 did not show appreciable adherence to the S. sanguis surface. Saliva did not affect the adherence of coaggregating or non-coaggregating H. parainfluenzae strains to S. sanguis strain SA-1. Bovine enamel chips, coated with streptococci, mounted on modified orthodontic appliances and placed in the mouths of three volunteers, facilitated the measurement of interbacterial adherence in vivo of streptomycin-resistant strains of H. parainfluenzae (HP-28R or HP-42R). Suspensions of bacteria were placed into the mouth, distributed throughout, and expectorated. After 15 or 120 minutes, the appliance with the chips was removed, the chips sonified, and colony-forming units (CFU) of streptomycin-resistant haemophili determined per chip.(ABSTRACT TRUNCATED AT 250 WORDS)