CHX Group Research Articles

O8 Impact of periodontal therapy (including antiseptics) on tongue coating and malodour

Background Bad breath is often caused by periodontitis and/or tongue coating. This study aimed to follow, over a 6 months period, the impact of periodontal therapy on several parameters linked with oral malodour.Methods In this double‐blind, randomized, long‐term, parallel study 45 moderate periodontitis patients without obvious tongue coating were enrolled. Besides a ‘one‐stage, full‐mouth’ disinfection and oral hygiene improvement (including tongue scraping), patients were instructed to rinse with one of the following products (randomly allocated): CHX 0.2% + alcohol (Corsodyl®), CHX 0.05% + CPC 0.05% and no alcohol (Perio.Aid®Maintenance, a new formulation), or the placebo of the latter for 6 months. At baseline and after 3 and 6 months, a serious of parameters was recorded including VSC rating (Halimeter), tongue coating and an estimation of the microbial load (anterior & posterior part tongue, saliva, supragingival plaque).Results Even though the initial VSC values were not high (±90, only 18 patients >100), significant (P < 0.05) reductions could be recorded in the CHX and CHX+CPC group, but only to a minor extent in the placebo group. Tongue scraping resulted in a significant reduction (P ≤ 0.05) of the coating up to month 6 in the placebo and CHX+CPC group, but not in the CHX group. The microbial changes in the placebo group were never significant (≤0.3 log values), even though the tongue had been scraped daily. The CHX and CHX‐CPC group showed, in comparison to baseline, significant (P < 0.001) reductions in the number of anaerobic species in the supra gingival plaque, in the saliva and on the anterior part of the tongue. For the posterior part of the tongue the microbial changes remained ≤0.3 log values.Conclusions The results of this study indicate that, in patients with moderate periodontitis, periodontal therapy including tongue scraping did not have a significant effect on the microbial load of the tongue or the VSC level, except when combined with a mouthrinse.

Thermodynamic Approach to Optimization of SrTiO3Chemical Vapor Deposition from Volatile Metalorganic Precursors

Thermodynamic analysis is used to examine the possibility of producing SrTiO3 films in two precursor systems containing different volatile Ti compounds: TiO(dpm)2–Sr(dpm)2–N2O–Ar (I) and Ti(OPri)2(dpm)2–Sr(dpm)2–N2O–Ar (II). The results demonstrate that, at an initial Ti : Sr atomic ratio of 1 : 1 and a ratio of flow rates \(f_{{\text{N}}_{\text{2}} {\text{O}}} \)/fAr = 1, system I contains no region of single-phase SrTiO3 deposition. Raising the N2O concentration in the vapor phase makes it possible to deposit SrTiO3. System II contains a broad temperature range of SrTiO3 deposition (400–1300 K) over the entire pressure range examined, ptotal = 1–100 Pa. These conclusions are verified by depositing films in systems I and II (in particular, in system I in the presence of N2O activated in an rf discharge). The films grown in system I are found to consist of crystalline SrTiO3 and an amorphous phase containing residual organics, in particular in the form of CHx groups with x = 1–3. The films produced in system II consist of nanocrystalline SrTiO3. In this system, the equilibrium phase SrTiO3 is formed on the substrate surface via solid-state reaction between TiO2 and SrO intermediates. The rf activation of N2O makes it possible to grow crystalline SrTiO3 at much lower temperatures.

306SPONTANEOUS AND PARTHENOGENETIC ACTIVATION OF RAT OOCYTES

Oocyte activation is one of the critical steps for the success in a mammalian cloning program. In rats, information regarding parthenogenetic activation of oocytes is limited and further studies are required to elucidate the phenomenon of spontaneous activation and to develop effective protocols of induced activation. The objectives of the study were (1) to characterize the kinetics of spontaneous activation and (2) to examine different activation regimens for rat oocytes. Oocytes were collected from 3–4-wk-old PMSG-primed Sprague Dawley rats at 14h after hCG injection. HEPES-mR1ECM was used for oocyte collection and mR1ECM for in vitro culture (Miyoshi et al., 1995 J. Reprod. Fert. 103, 27–32). Experiment 1: Cumulus-denuded oocytes were fixed and stained with bisbenzimide (Hoechst 33342) at 10, 40, 70, 100 and 130min after recovery. Most oocytes (92.9%) were still arrested in the metaphase II stage at 10min after recovery, but the proportion of activated oocytes increased in a time-dependent manner, i.e. at 40min after recovery 50% were at anaphase. At 70min, 32.4%, 40.5%, 8.1%; at 100min, 4.8%, 57.1%, 23.8%; and at 130min, 0%, 3.3%, 86.7% had progressed to anaphase II, telophase II and extruded a 2nd PB, respectively. Experiment 2: Oocytes were exposed to the following activation treatments: Two sets of electrical stimuli (ES) 1h apart composed of 3 DC pulses, 1s apart of 1.2kVcm−1 field strength and 60μs duration in 0.25M mannitol solution (Roh et al., 2003 Reprod. Fert. and Dev., 15, 135–140). After ES treatment, oocytes were exposed for 3h to either cycloheximide (CHX, 10μg mL−1, Group 1), 6-dimethylaminopurine (DMAP, 2mM, Group 2), or CHX (10μgmL−1) and DMAP (2mM) (Group 3). Group 4 was exposed to Strontium (10mM) for 1h and then incubated with CHX (10μgmL−1) and DMAP (2mM) for 3h. Oocytes were washed thoroughly after treatment, transferred to 50-μL droplets of mR1ECM and cultured at 37°C in a humidified atmosphere of 5% O2, 5% CO2 and 90% N2. Pronuclear formation and cleavage rates were significantly higher in Groups 2 and 3 than in Groups 1 and 4 (92.6%, 88.9% and 84.6%, 80.8% v. 49.1%, 45.6% and 62.8%, 55.8%, respectively). First, these results show that rat oocytes undergo spontaneous activation very rapidly after recovery from the oviducts. Second, activation protocols with two sets of triple DC electrical stimulation followed by exposure to DMAP or CHX/DMAP are effective means of activation. In conclusion, the above information will be useful in establishing effective protocols for cloning rats. (Financial support by NSERC and Canada Research Chairs.)

Packing Effects in the Liquid-Phase Adsorption of C5-C22 n-Alkanes on ZSM-5

The liquid-phase adsorption of C5-C22 linear alkanes on ZSM-5 was studied using a batch adsorption technique. Saturation capacities of the alkanes depend strongly on the chain length. The number of −CHx groups adsorbed per unit cell drops steeply between C7 and C8 and then increases steadily to reach a plateau of 53−54 for C14−C22. In this plateau region, the pores of ZSM-5 are densely packed with alkane molecules. The mechanisms of packing in liquid-phase adsorption were studied using configurational-bias grand canonical Monte Carlo simulations. These simulations revealed that the probability of bending and crossing in the intersections increases with chain length, explaining the very good packing of long-chain alkanes. Short alkanes tend to stay away from the intersections, resulting in a lower packing density.

Comparative study of two treatment procedures in periodontitis: Nd:YAG laser with biodegradable chlorhexidine chip (CHX) and manual curettage with CHX

The purpose of the study was to evince the most suitable therapeutic method for the reduction of probing pocket depth in patients with adult periodontitis. Nd:YAG laser curettage associated with biodegradable chlorhexidine chip (CHX) was compared with manual curettage combined with CHX. Eleven patients (eight females and three males) with at least four single-rooted teeth with 4–8 mm pocket depth participated in this study. Clinical examination of gingival index (GI) and probing pocket depth (PPD) was performed before and after treatment (6 weeks, 3 months, and 6 months later). Bacteriological investigation (spirochetes and motile rods bacteria) of the periodontal pocket contents from each treatment site was carried out. Clinical results indicated a significant improvement in the PD mean observed in the laser+CHX group (mean change in PD was 1.25±0.06 mm) compared to the manual curettage+CHX group (mean change in PD was −0.68±0.07 mm), checked 3 months later. The bacteriological results showed that the mean percentage of spirochetes before treatment was 19.82±1.65%, and 6 weeks later, the mean percentage was 0.19±0.12% for the laser+CHX group in comparison with 2.11±0.14% for the manual curettage+CHX group and 1.98±0.09% for the laser group. In conclusion, under the study conditions, the healing response was achieved sooner when Nd:YAG laser curettage was associated with CHX.

Layering and orientational ordering of propane on graphite: An experimental and simulation study

We report the results of an experimental and theoretical study of propane adsorption on highly oriented pyrolytic graphite. Simulations and experiments were carried out for temperatures from 90 to 110 K and pressures from ultrahigh vacuum up to about 0.5 mTorr. Both simulations and experiments show that propane adsorbs in a layer-by-layer fashion and exhibits continuous growth beyond the second layer at the higher temperatures studied. Experimental adsorption data were obtained by optical differential reflectance (ODR) and temperature programmed desorption (TPD). The ODR method is able to dynamically follow the adsorption and desorption process as a function of time over a wide pressures range, while TPD probes only the desorption events at ultrahigh vacuum conditions. The influence of the fluid–fluid potential on the adsorption isotherms has been investigated by comparing simulations using five different propane potentials. The pressure at which the second layer forms was found to vary by more than 1 order of magnitude among the potentials tested, whereas the isosteric heat of adsorption is less sensitive to the potential. We find that the propane potential that best describes the liquid phase energetics is in the best agreement with experimental adsorption isotherms and isosteric heats. The binding energy of propane in the monolayer measured from TPD experiments is in excellent agreement with that computed from simulations, both giving values of about 30 kJ mol−1. The isosteric heat of adsorption at incipient second layer formation is 23±2 kJ mol−1 as measured from ODR isotherms and 24±1 kJ mol−1 computed from simulations. The isosteric heat as a function of coverage computed from molecular simulations is roughly constant over the 1–2 and the 2–3 layering transitions at 91 K. We show that this unusual behavior is due to a rotational transition, whereby molecules in the first layer rotate from a parallel (all CHx groups in contact with the graphite plane) to a perpendicular (one CH3 group pointing up) orientation. This rotational transition has two effects: it allows more molecules to adsorb in the monolayer and increases the isosteric heat of adsorption in the second layer over that for adsorption onto an atomically smooth surface.

NEMD Simulations of Viscosity and Viscosity Index for Lubricant-Size Model Molecules

Synthetic lubricant research can be facilitated with nonequilibrium molecular dynamics simulations (NEMD) of viscosity and viscosity index (VI). While previously reported simulations using united atom (UA) models for intermolecular interactions have generally under-predicted the viscosity of lubricant-size alkanes, VI values, trends with respect to structure, and viscosity pressure coefficients obtained from simulations are generally accurate, suggesting that simulations of UA models can be used for screening candidate fluids. This requires some reliance on the expected accuracy of the method as established by application to a wide variety of model fluids. We report here the results of NEMD simulations on UA models for 2,2,4,4,6,8,8-heptamethylnonane (HMN) and 11-n-amylheneicosane (NAH). HMN represents a molecule with significant branching, dominated with tertiary carbons; NAH represents a fluid with a single large aliphatic branch off of a long aliphatic chain, and a molecule for which there is some interest as a lubricant component. Additionally, we test here a new parameterization of UA potentials for –CHX groups. VI results from simulations using the new parameterization are in excellent agreement with experiment. Viscosity results are significantly better with the new parameterization, but the UA model still tends to underestimate the viscosity of larger, lubricant-size molecules.

Chemistry of Methoxonium on (2 × 1)Pt(110)

In a previous paper, (Chen, N.; Blowers, P.; Masel, R. I. Surf. Sci. 1998, 418, 329−341.) we found that methoxonium ions (CH3OH2)+ can form when methanol and hydrogen coadsorb on Pt(110). In this paper, we characterize the chemistry of methoxonium on (2 × 1)Pt(110) using mainly TPD. We observe three reaction pathways: a simple dehydrogenation to CO and hydrogen; an SN1 pathway to form water, methane, and adsorbed CHx groups; and an SN2 pathway yielding dimethyl ether. The SN1 pathway shows a strong secondary isotope effect implying that the transition state is ionic. The SN2 pathway is seen at high hydrogen coverages and shows kinetics typical for an SN2 process. This work demonstrates for the first time that cationic species on surfaces react via the same SN1 and SN2 pathways seen during reactions of cations in solution.

An efficient synthesis of N-tert-butoxycarbonyl-O-cyclohexyl-L-tyrosine.

A facile and efficient synthesis of N-tert-butoxycarbonyl-O-cyclohexyl-L-tyrosine [Boc-Tyr(Chx)-OH] is described. Boc-Tyr-OH was treated with NaH in dimethylformamide and then with 3-bromocyclohexene to give N-Boc-O-(cyclohex-2-enyl)-L-tyrosine [Boc-Tyr(Che)-OH] in 70% yield. Hydrogenation of Boc-Tyr(Che)-OH over PtO2 afforded Boc-Tyr(Chx)-OH in almost quantitative yield. The highest yield was achieved when a side product in the synthesis of Boc-Tyr-OH, Boc-Tyr(Boc)-OH, was not removed, because it was also converted to Boc-Tyr(Che)-OH without any additional manipulations. The new synthetic method described here is convenient for practical use, and would facilitate the widespread use of the Chx group for the hydroxy-protection of Tyr.

ChemInform Abstract: Cyclohexyl Ether as a New Hydroxy-Protecting Group for Serine and Threonine in Peptide Synthesis.

A new hydroxy-protecting group for Ser and Thr, cyclohexyl (Chx), has been developed, and its application to peptide synthesis is described. The Chx group is introduced to the hydroxy functions of Boc-Ser-OH and Boc-Thr-OH in two steps; Boc-Ser-OH and Boc-Thr-OH are treated with NaH and then allowed to react with 3-bromocyclohexene to afford N-Boc-O-(cyclohex-2-enyl)-Ser and N-Boc-O-(cyclohex-2-enyl)-Thr in satisfactory yields, which are hydrogenated in the presence of PtO2 to give Boc-Ser(Chx)-OH and Boc-Thr(Chx)-OH in good yields. The O-Chx group is stable to various acidic and basic conditions including TFA and 20% piperidine in DMF. It is not removed with catalytic hydrogenation over Pd–charcoal. The Chx group is, however, removed quantitatively with 1 mol dm−3 trifluoromethanesulfonic acid–thioanisole in TFA over a short period. These results indicate that the Chx group is suitable for the hydroxy-protection of Ser and Thr in peptide synthesis based on Boc-chemistry and can be used also in combination with either Nα-Fmoc or Nα-Z-protection. The apparent rate constant for removal of the Chx group with 50% TFA in CH2Cl2 (kChx) is found to be less than a twentieth of that of the Bzl group (kBzl), confirming the substantial stability of the Chx group under common Boc-deprotection conditions. Simulations of solid-phase peptide syntheses using kChx and kBzl indicate that the Chx group would be adequate for solid-phase synthesis of large peptides and proteins. Solid-phase synthesis of a peptide and conventional solution synthesis of a protected peptide segment using Chx protection are also demonstrated.

Amine Fluoride/Stannous Fluoride and Chlorhexidine Mouthwashes as Adjuncts to Surgical Periodontal Therapy: A Comparative Study

Postsurgical mouthwashes are routinely used in clinical studies and also in daily clinical practice. Chlorhexidine gluconate (CHX) has long been the gold standard for supra-gingival chemical plaque control regimens. Amine fluoride/stannous fluoride (AmF/SnF2) formulations have also been extensively studied and shown to have an antibacterial effect and be useful as antiplaque agents. The antibacterial effect of AmF/SnF2 and its minimal extrinsic tooth staining make it a possible alternative to CHX as an adjunct to periodontal surgical therapy. The aim of this double-blind, controlled clinical trial was to evaluate and compare the combined effect of an AmF/SnF2 or a CHX mouthwash and surgical periodontal therapy on periodontal parameters. Thirty-two patients with at least 3 pockets > or =5 mm in the same quadrant were selected for this study, following a hygienic phase of therapy. They were randomized into 2 treatment groups: surgical flap debridement and a postsurgical CHX mouthwash or surgical flap debridement and an AmF/SnF2 postsurgical mouthwash, performed twice daily for 3 weeks. Clinical measurements were taken at baseline and 3 and 12 weeks postsurgery. Both treatment modalities resulted in significant improvements in probing depth and clinical attachment level. There was no significant difference between groups in any of the recorded parameters. Staining index at week 3 in the CHX group was significantly higher than in the AmF/SnF2 group (P<0.05). However these differences leveled down at 12 weeks. Our results support the alternative use of an AmF/SnF2 mouthwash in plaque control management of patients following flap debridement surgery.

Optical Properties and Defect Structure of CVD Diamond Films Annealed at 900-1600 �C

Optical absorption evolution is studied for 150–800 μm thick diamond films grown by microwave plasma enhanced CVD technique and annealed in vacuum at temperatures 900–1600 °C. A noticeable internal degradation (darkening) of the films takes place at T > 1300 °C. Changes in the concentration of different CHx groups are revealed from the IR spectra starting at T > 1000 °C. Up to 25% of the total amount of hydrogen in as-grown films is found to be unbonded. An interesting effect of reduced absorption in UV range due to the formation of new C–H bonds by reaction of primarily unbonded hydrogen is observed. The diamond darkening correlating with the bonded hydrogen loss process, is ascribed to the appearance of a graphite-like phase (being under a high stress) presumably at grain boundaries, that is revealed by the appearance of a specific absorption peak in UV spectra.

Nitrogen and hydrogen in thick diamond films grown by microwave plasma enhanced chemical vapor deposition at variable H2 flow rates

The presence and concentration of nitrogen and hydrogen impurities in thick diamond films grown by microwave plasma chemical vapor deposition at various H2 gas flow rates, keeping a constant [CH4]:[H2]=2.5% concentration ratio, have been determined by electron spin resonance and optical absorption spectroscopy. The relative concentration of both impurities, present as paramagnetic atomic species with different relaxation properties, has been found by ESR measurements to decrease exponentially with the increase in the H2 gas flow rate. Moreover, the resulting values were proportional to the content of substitutional nitrogen and CHx groups obtained from infrared and ultraviolet-visible optical absorption measurements, respectively. The decrease in the concentration of both impurities with an increase in the quality of the studied diamond films, early observed from high resolution electron microscopy studies on the same samples, strongly suggests that the incorporation of both impurities, as paramagnetic atomic species, is directly related to the concentration of the extended lattice defects.

Adsorption of Fluorine on Bare, Hydrogen- and Hydrocarbon-Covered Diamond C(111) Surfaces

The adsorption of fluorine delivered as xenon difluoride has been examined on a bare diamond C(111)(2×1) surface as well as modified surfaces of hydrogen-terminated H:C(111)(1×1) and hydrocarbon-precovered CHx/C(111) by means of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED). The F intake by bare C(111)(2×1) at nearly 105 Langmuir of XeF2 exposure reached close to two monolayers on C(111). The adsorbed F was removed by annealing to 1400 K in vacuum, and was replaced by atomic hydrogen generated by a hot filament. The saturation coverage of F on H:C(111)(1×1) was one monolayer. The adsorbed F on H:C(111)(1×1) was removed by annealing to 1300 K and H:C(111)(1×1) was restored. On C(111) precovered with CHx groups, the initial sticking probability of F was definitely smaller than that of C(111)(2×1). The adsorbed F was less stable and desorbed completely at 1200 K. The structures of adsorbed F on C(111)(2×1) and H:C(111)(1×1) are discussed.

Cyclohexyl ether as a new hydroxy-protecting group for serine and threonine in peptide synthesis

A new hydroxy-protecting group for Ser and Thr, cyclohexyl (Chx), has been developed, and its application to peptide synthesis is described. The Chx group is introduced to the hydroxy functions of Boc-Ser-OH and Boc-Thr-OH in two steps; Boc-Ser-OH and Boc-Thr-OH are treated with NaH and then allowed to react with 3-bromocyclohexene to afford N-Boc-O-(cyclohex-2-enyl)-Ser and N-Boc-O-(cyclohex-2-enyl)-Thr in satisfactory yields, which are hydrogenated in the presence of PtO2 to give Boc-Ser(Chx)-OH and Boc-Thr(Chx)-OH in good yields. The O-Chx group is stable to various acidic and basic conditions including TFA and 20% piperidine in DMF. It is not removed with catalytic hydrogenation over Pd–charcoal. The Chx group is, however, removed quantitatively with 1 mol dm−3 trifluoromethanesulfonic acid–thioanisole in TFA over a short period. These results indicate that the Chx group is suitable for the hydroxy-protection of Ser and Thr in peptide synthesis based on Boc-chemistry and can be used also in combination with either Nα-Fmoc or Nα-Z-protection. The apparent rate constant for removal of the Chx group with 50% TFA in CH2Cl2 (kChx) is found to be less than a twentieth of that of the Bzl group (kBzl), confirming the substantial stability of the Chx group under common Boc-deprotection conditions. Simulations of solid-phase peptide syntheses using kChx and kBzl indicate that the Chx group would be adequate for solid-phase synthesis of large peptides and proteins. Solid-phase synthesis of a peptide and conventional solution synthesis of a protected peptide segment using Chx protection are also demonstrated.

Nonequilibrium Molecular Dynamics Simulations of 3-Methylhexane: The Effect of Inter- and Intramolecular Potential Models on Simulated Viscosity

Nonequilibrium molecular dynamics simulations of viscosity were performed using various molecular representations of 3-methylhexane in order to study the influence of potential models on simulated viscosity. The models investigated were united atom models with fixed bond lengths and bond angles. The effect of intermolecular potential was examined by comparing results from a homogeneous (in which all -CHx groups are equivalent) model and two heterogeneous models. The effect of intramolecular potential was investigated by comparing results from three different torsional potential models. The simulations were carried out at three different densities to investigate the sensitivity of the contributions from the various models to the viscosity at different conditions. Large changes in viscosity were produced by relatively small changes in the intermolecular potential parameters of the branched methyl group. The viscosity was found to be less sensitive to the intermolecular potential parameters of the chain methyl groups and the torsional potential. Our results suggest that an accurate representation of the molecular structure and size as governed by intermolecular interactions is more important in accurate viscosity predictions than careful modeling of the intramolecular potential.

Clinical effects of chlorhexidine mouthwashes on patients undergoing orthodontic treatment

This study compared the short-term clinical effect of 0.12% chlorhexidine gluconate and placebo mouthrinses in 30 adolescents (ages 11 to 15) undergoing orthodontic treatment. Subjects were randomized into experimental (CHX) and control (C) groups. Baseline values were recorded 10 days after prophylaxis and included Plaque Index (PI), Gingival Index (GI), Rentention Index (RI), Discoloration Index (DI), and probing depths (PD). Both groups (CHX and C) received soft toothbrushes with instructions to brush twice daily, as well as the CHX and placebo mouthrinses, respectively, with oral and written instructions for rinsing twice daily with 15 ml for 30 seconds. Reevaluations were performed 1, 2, and 3 months after baseline, except for the DI and PD, which were only assessed at 3 months. The Student's t test and the paired t test were used to analyze the data at the P < 0.05 level of significance. No differences between groups were seen at baseline for any of the parameters. At 30 days, there was a significant difference for the RI between CHX (0.15 ± 0.16; mean ± SD) and C (0.05 ± 0.06) at the mesial buccal, and for CHX (0.07 ± 0.10) and C (0.02 ± 0.05) at the midbuccal. The 60-day evaluation showed similar results. At 90 days, lower PI were observed in the CHX group at the distal buccal (0.38 ± 0.19), midbuccal (0.22 ± 0.17), and mesial buccal (0.47 ± 0.22) sites as compared with the C group (0.97 ± 0.38, 0.83 ± 0.40, and 0.95 ± 0.43, respectively). A similar trend was noted with the GI, as the lower values were related to the CHX group. The changes of the PI and GI, at 30, 60, and 90 days, as analyzed by the paired t test, were statistically significant in the case of the experimental group, as the changes in the means were a reflection of significantly lower scores observed in the experimental group. After 3 months, the DI showed higher scores in the experimental group as compared with the control, but they were not statistically significant. Deeper PD were detected in the C group at 90 days, and they were statistically significant, except for the midlingual site. The RI did not show significant differences at 90 days, but higher values were recorded in the CHX group. The data indicate that the use of the CHX, in addition to regular oral hygiene habits, was effective in reducing plaque and gingivitis in adolescents undergoing orthodontic treatment. (Am J Orthod Dentofac Orthop 1997; 111: 606-12.)

Synthesis of gamma-carboxyglutamic acid-containing peptides by the Boc strategy.

gamma-Carboxyglutamic acid (Gla) derivatives having several protecting groups at the gamma-carboxyl function were synthesized and examined for their stabilities and removabilities under the conditions used in peptide synthesis by the Boc strategy. Among them, the cyclohexyl (cHx) group of the Gla residue was found to be stable during the synthesis of the protected peptides, but was quantitatively cleaved by the final HF treatment without decarboxylation. Using Boc-Gla(OcHx)2-OH as a starting material, the synthesis of Gla-containing peptides was achieved by the Boc strategy using a standard HF procedure for the final deprotection.

Bacteremia Following Subgingival Irrigation and Scaling and Root Planing

The purpose of this study was to determine the incidence of bacteremia after a single professional subgingival irrigation with a 0.12% chlorhexidine gluconate mouthrinse (CHX) as well as after a subsequent scaling and root planing (S/RP) during the same visit. Thirty subjects each with at least 1 site that probed 4 mm or more and bled on probing were randomly assigned to the following groups: 1) irrigation with 0.12% CHX; 2) irrigation with sterile water; and 3) non-irrigated controls. To begin the study blood was drawn just before and 2 minutes after irrigation. Thirty minutes later, blood was drawn again just before and 2 minutes after S/RP at the same site. Specimens were cultured for anaerobic and aerobic microorganisms using standard cultural techniques. Eighteen blood cultures from 15 subjects yielded positive cultures resulting in 23 isolates. Gram-positive rods comprised 34.8% of the total isolates; Gram-positive cocci 34.8%, Gram-negative rods 21.7%, and Gram-negative cocci 8.7%. In the CHX group, bacteremia was detected in 5 subjects after irrigation and in 2 other subjects after S/RP. In the water group, bacteremia was detected in one subject after irrigation and in 4 subjects after S/RP. The control group had 3 bacteremias after S/RP. There was no significant difference between the incidence of bacteremia associated with irrigation by CHX or sterile water (P = 0.141). There was also no significant difference in the incidence of bacteremia after S/RP between the CHX and sterile water irrigation groups and in patients who did not receive irrigation (control group) (P = 0.88).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of whole body disinfection on intraoperative wound contamination

As part of a large whole body disinfection (WBD) trial two small sub-groups of patients who showered preoperatively with either a 4% chlorhexidine (CHX; N = 29) or placebo ( N = 27) detergent were studied to assess intraoperative wound contamination. The groups were well matched for age, sex and length of surgery. A membrane filter contact technique was used for bacterial recovery from the wounds after the initial skin incision and before wound closure. The membrane filters were incubated aerobically on blood agar plates with a CHX neutralizer for 48 h at 37 °C and colonies were counted. The results show a significant difference between the bacterial counts at the start and end of surgery in the CHX and placebo groups. There was no difference in bacterial counts at the start of surgery between the CHX and placebo groups. There was a significant difference in the bacterial counts at the end of surgery between the CHX and placebo groups. These results indicate that preoperative WBD with CHX reduces intraoperative wound contamination but the effect of this on postoperative wound sepsis rates awaits the results of a large WBD trial.