Assessment of newly developed tongue sulfide probe for detecting oral malodor

Aim: The present study examined the relationship between sulfide levels on tongue dorsum surfaces (pS levels) and oral malodor. Method: The pS levels of 20 systemically healthy volunteers were evaluated using an industrial device equipped with a newly-developed tongue sulfide probe. The pS levels on 3 parts of the tongue – anterior, middle and posterior along the median groove of the tongue dorsum – were determined for each subject. Results: The device reported the pS level in a digital score ranging from 0.0 (<10 −7 M of sulfide) to 5.0 (ges;10 −2 M of sulfide) in increments of 0.5. Oral malodor was assessed by measuring the level of volatile sulfur compounds in mouth air, as well as by the organoleptic method. The pS levels were 0.03±0.11, 0.20±0.41 and 0.88±0.76 for the anterior, middle and posterior parts, respectively. This difference was significant ( p <0.001). Both oral malodor measurements showed significant correlation ( p <0.05) with the pS levels of middle and posterior parts of tongue. Conclusion: It was concluded that the tongue sulfide probe might be useful in management of subjects with oral malodor.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75342/1/j.1600-051x.2001.028005494.x.pd

Association between oral malodor and adult periodontitis: a review

Background: Bad breath has a significant impact on our daily social life to those who suffer from it. The majority of bad breath originates within the oral cavity. However, it is also possible that it can come from other sources such as gastric-intestine imbalance. The term “oral malodor” is used to describe a foul or offensive odor emanating from the oral cavity, in which proteolysis, metabolic products of the desquamating cell, and bacterial putrefaction are involved. Recent evidence has demonstrated a link between oral malodor and adult periodontitis. The process of developing bad breath is similar to that noted in the progression of gingivitis/periodontitis. Oral malodor is mainly attributed to volatile sulfur compounds (VSC) such as hydrogen sulfide, methyl mercaptan and dimethyl sulfide. The primary causative microbes are gram-negative, anaerobic bacteria that are similar to the bacteria causing periodontitis. These bacteria produce the VSC by metabolizing different cells/tissues (i.e., epithelial cells, leukocytes, etc.) located in saliva, dental plaque, and gingival crevicular fluid. Tongue surface is composed of blood components, nutrients, large amounts of desquamated epithelial cells and bacteria, suggesting that it has the proteolytic and putrefactive capacity to produce VSC. One of the challenges in dealing with oral malodor is to identify a reliable test for detecting bad breath. Aims: The purposes of this review article were: (1) to correlate the relationship between oral malodor and adult periodontitis; (2) to analyze current malodor tests and discuss available treatment regimens.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73536/1/j.1600-051x.2001.028009813.x.pd

Detecting and Understanding the Roles of Nitric Oxide in biology

We are pursuing a dual strategy for investigating the chemistry of nitric oxide as a biological signaling agent. In one approach, metal-based fluorescent sensors for the detection of NO in living cells are evaluated, and a sensor based on a copper fluorescein complex has proved to be a valuable lead compound. Sensors of this class permit identification of NO from both inducible and constitutive forms of nitric oxide synthase and facilitate investigation of different NO functions in response to external stimuli. In the other approach, we employ synthetic model complexes of iron−sulfur clusters to probe their reactivity toward nitric oxide as biomimics of the active sites of iron−sulfur proteins. Our studies reveal that NO disassembles the Fe−S clusters to form dinitrosyl iron complexes.National Science Foundation (U.S.) (CHE-0907905)National Institute of General Medical Sciences (U.S.) (Grant F32 GM082031-03

Early transitional metal alkyl, alkylidene, and alkylidyne chemistry

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references.CHAPTER 1. Zirconium and hafnium complexes of several new unsymmetric diamide ligands have been prepared and their proficiency in olefin polymerization reactions evaluated. The first set of supporting ligands examined are diamido-donor ligands that contain ethylene/o-phenylene "arms" and a phenyl-substituted amine donor in the central position. These ligands are derived from the triamines, [MesitylNH-o-C6H4N(Ph)CH2CH2NHMesityl] (H2[MesNNPhMes]) and [t- Bud6-NH-o-C6H4N(Ph)CH2CH2NHMesityl] (H2[t-BuNNPhNMes]). The Zr and Hf complexes that can be isolated include [MesNNPhNMes]MX2 (M = Zr or Hf, X = NMe2, Cl, or Me) and [t- BuNNPhNMes]MX2 (M = Zr or Hf, X = NMe2, Cl, Me). The structures of [MesNNPhNMes]ZrMe2, [t-BuNNPhNMes]ZrMe2, and a dimeric species with the formula [MesitylN-o-C6H4NCH2CH2NMesityl]Zr2(NMe2)5 are reported. Abstraction of a methyl group in [MesNNPhNMes]MMe2 (M = Zr or Hf) with [Ph3C][B(C6F5)4] gives rise to cationic complexes which are active initiators for the polymerization of 1-hexene. Similar activation of [t- BuNNPhNMes]MMe2 (M = Zr or Hf) gives rise to dimeric monocations that eventually break-up and react further to yield cationic monomethyl species. In all cases the poly[1-hexene] produced in the presence of the monometallic cations was found to be atactic.(cont.) The second ligand explored is a diamido-didonor ligand based on the diamine, rac-H2[MepyN] (rac-N,N'-di-(6- methylpyridin-2-yl)-2,2'-diaminobinaphthalene), which can be prepared through reductive amination of rac-2,2'-diaminobinaphthalene with 6-methylpyridinecarboxaldehyde. The deprotonated amine [MepyN]2- supports of variety of zirconium and hafnium complexes including [MepyN]MX2 (M = Zr, X = NMe2, Cl, OSO2CF3, CH2CHMe2, CH2Ph; M = Hf, X = NMe2, OSO2CF3, i-Bu). The solid state structures of [MepyN]Zr(CH2Ph)2, [MepyN]Zr(NMe2)Cl, [MepyN]Hf(CH2CHMe2)2, and [MepyN]Hf(OSO2CF3)2 are reported. Activation of [MepyN]Zr(CH2Ph)2 and [MepyN]Hf(i-Bu)2 with various Lewis acids leads to observable cationic alkyls that are not active towards 1-hexene polymerization. The third ligand examined is a diamide ligand based on the diamine rac-H2[HIPTN2] (HIPTN2 = (Nhexaisopropyl- 3,5-terphenyl)diaminobinaphthalene), which can be prepared through palladiumcatalyzed N-aryl coupling of diaminobinaphthalene and 3,5-bis-(2,4,6- triisopropylphenyl)bromobenzene. The reaction between H2[HIPTN2] and M(NMe2)4 (M = Ti, Zr, and Hf) yields [HIPTN2]M(NMe2)2 complexes. Other complexes of [HIPTN2]2- that can be prepared include [HIPTN2]ZrCl2, [HIPTN2]ZrMe2, [HIPTN2]Zr(CH2-t-Bu)2, [HIPTN2]HfCl2, [HIPTN2]HfMe2, and [HIPTN2]Hf(CH2CHMe2)2.(cont.) Activation of [HIPTN2]ZrMe2 with a variety of Lewis acids gives rise to different species depending on the nature of the activator employed. For example, [HIPTN2]ZrMe2 reacts with [Ph3C][B(C6F5)4] to give a cationic complex that is active toward oligomerization of 1-hexene, while activation with B(C6F5)3 leads to formation of [HIPTN2]Zr(C6F5)2. No polymerization of 1-hexene by activated complexes of the [HIPTN2]2- ligand is observed. CHAPTER 2. Imido alkylidene initiators for the controlled polymerization of diethyl dipropargylmalonate (DEDPM) have been prepared. A vinyl alkylidene complex, 2a, containing a five-membered ring as part of a trienylidene unit can be obtained by treating Mo(NAr)(CHCMe2R)(O-t-BuF6)2 (Ar = 2,6-diisopropylphenyl; R = Me, Ph; t-BuF6 = C(CF3)2Me) with diethyl 3-(2-methylprop-1- enyl)-4-vinylcyclopent-3-ene-1,1-dicarboxylate in pentane. A related complex, 4b, containing a six-membered ring alkylidene ligand can be prepared by a reaction between Mo(NAr)(CH-t- Bu)(O-t-BuF6)2 and 1-methylidene-5,5-bis(carboxyethyl)cyclohex-1-ene. Treatment of 2a or 4b with LiO-t-Bu yields the analogous tert-butoxide species (2c and 4c). An X-ray structure of a sample of 4c that retained two equivalents of LiO-t-BuF6 shows it to be a dimeric species in which two Mo complexes were joined through a Li4O4 heterocubane-type structure binding to one ester in each complex.(cont.) Reactions between DEDPM and 4c demonstrate smooth initiation with a kp/ki value of less than one. The carboxylate species, Mo(NR)(CHCMe2R')(O2CCPh3)2 (R = various aryl groups or 1-adamantyl; R' = Ph or Me) can be prepared by salt metathesis reactions between Mo(NR)(CHCMe2R')(OTf)2(DME) (OTf = trifluoromethanesulfonate; DME = 1,2-dimethoxyethane) and sodium triphenylacetate. Trimethylphosphine adducts of selected triphenylacetate complexes can also be synthesized, and the X-ray structure of Mo(NAr'')(CH-t- Bu)(O2CCPh3)2(PMe3) (Ar'' = 2-tert-butylphenyl) is reported. Several of the triphenylacetate complexes are active initiators for the regioselective polymerization of DEPDM. Several of the alkylidene initiators serve as precursors to oligomeric fragments of poly[DEDPM], which represent structural models of the polymer chain. CHAPTER 3. Reaction of Mo(NR)(CHCMe2R')(OTf)2(DME) (R = ,6-diisopropylphenyl, 2,6-dichlorophenyl, or 2-tert-butylphenyl; R' = Me or Ph) with the lithium salt of various [beta]-diketonate and [beta]- diketiminates leads to complexes of the type Mo(NR)(CHCMe2R')(L)(OTf) (L = [beta]-diketonate or [beta]-diketiminate). Treatment of Mo(NR)(CHCMe2R')(L)(OTf) with NaBArf4 (Arf = 3,5- (CF3)2C6H3) in the presence of THF affords the cationic species {Mo(NR)(CHCMe2R')(L)(THF)}{BArf4}.(cont.) The reactivity of the cationic [beta]-diketonate (acac) and [beta]-diketiminate (nacnac) complexes towards olefins has been examined, as has the thermal decomposition modes of the neutral and cationic nacnac complexes. Results demonstrate that the cationic species have short catalyst lifetimes, and that decomposition modes dominate the chemistry of several of the nacnac complexes. The X-ray crystal structures of several neutral and cationic complexes are reported. CHAPTER 4. Reaction of WCl3(OAr)3 (Ar = 2,6-diisopropylphenyl) with 4 equivalents of t-BuCH2MgCl in diethyl ether produces yellow crystalline W(C-t-Bu)(CH2-t-Bu)(OAr)2 in 40 - 50% isolated yield. The alkyl alkylidyne species reacts with 2-butyne and 3-hexyne in a metathetical fashion to generate the symmetric metallacyclobutadiene species, W(C3R3)(CH2-t-Bu)(OAr)2 (R = Me and Et, respectively). Replacement of the OAr ligands with LiNPh2 generates W(C-t-Bu)(CH2-t Bu)(NPh2)2 which serves as an in situ precursor to other dialkoxide species as demonstrated by alcoholysis with 1-adamantanol. The reaction between W(C-t-Bu)(CH2-t-Bu)(OAr)2 and benzonitrile generates the dimeric nitride species, [W(N)(CH2-t-Bu)(OAr)2]2.(cont.) The nitride reacts with trimethylsilyl trifluoromethanesulfonate to afford the imido complex, W(NTMS)(CH2-t- Bu)(OAr)2(OTf), The X-ray crystal structure of W(C-t-Bu)(CH2-t-Bu)(OAr)2, [W(N)(CH2-t- Bu)(OAr)2]2, and W(NTMS)(CH2-t-Bu)(OAr)2(OTf) are reported as are studies concerning the catalytic efficiency of both W(C-t-Bu)(CH2-t-Bu)(OAr)2 and W(C-t-Bu)(CH2-t-Bu)(O-1- adamantyl)2. APPENDIX A. The reaction of Ph3P=CH2 with Mo(NAr)(CH-t-Bu)(O-t-BuF6)2 (Ar = 2,6-i-Pr2C6H3; O-t-BuF6 = OC(CF3)2Me) produces the anionic alkylidyne complex {Ph3PMe}{Mo(NAr)(C-t-Bu)(O-t- BuF6)2}. An X-ray structure determination of the complex reveals a bent Mo-N-C angle for the imido group, as expected when a metal-carbon triple bond is present. The reactivity of the anion towards electrophiles has been examined and shown to occur predominantly at the imido nitrogen.by Zachary John Tonzetich.Ph.D

A new portable monitor for measuring odorous compounds in oral, exhaled and nasal air

<p>Abstract</p> <p>Background</p> <p>The B/B Checker^®, a new portable device for detecting odorous compounds in oral, exhaled, and nasal air, is now available. As a single unit, this device is capable of detecting several kinds of gases mixed with volatile sulfur compounds (VSC) in addition to other odorous gasses. The purpose of the present study was to evaluate the effectiveness of the B/B Checker^®for detecting the malodor level of oral, exhaled, and nasal air.</p> <p>Methods</p> <p>A total of 30 healthy, non-smoking volunteers (16 males and 14 females) participated in this study. The malodor levels in oral, exhaled, and nasal air were measured using the B/B Checker^®and by organoleptic test (OT) scores. The VSCs in each air were also measured by gas chromatography (GC). Associations among B/B Checker^®measurements, OT scores and VSC levels were analyzed using Spearman correlation coefficients. In order to determine the appropriate B/B Checker^®level for screening subjects with malodor, sensitivity and specificity were calculated using OT scores as an identifier for diagnosing oral malodor.</p> <p>Results</p> <p>In oral and nasal air, the total VSC levels measured by GC significantly correlated to that measured by the B/B Checker^®. Significant correlation was observed between the results of OT scores and the B/B Checker^®measurements in oral (r = 0.892, p < 0.001), exhaled (r = 0.748, p < 0.001) and nasal air (r = 0.534, p < 0.001). The correlation between the OT scores and VSC levels was significant only for oral air (r = 0.790, p < 0.001) and nasal air (r = 0.431, p = 0.002); not for exhaled air (r = 0.310, p = 0.096). When the screening level of the B/B Checker^®was set to 50.0 for oral air, the sensitivity and specificity were 1.00 and 0.90, respectively. On the other hand, the screening level of the B/B Checker^®was set to 60.0 for exhaled air, the sensitivity and specificity were 0.82 and 1.00, respectively.</p> <p>Conclusion</p> <p>The B/B Checker^®is useful for objective evaluation of malodor in oral, exhaled and nasal air and for screening subjects with halitosis.</p> <p>Trial registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01139073">NCT01139073</a></p

Characterization of a High‐Spin Non‐Heme {FeNO} 8 Complex: Implications for the Reactivity of Iron Nitroxyl Species in Biology

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/101872/1/12283_ftp.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/101872/2/anie_201305291_sm_miscellaneous_information.pd

Cytochrome C Biosensor—A Model for Gas Sensing

This work is about gas biosensing with a cytochrome c biosensor. Emphasis is put on the analysis of the sensing process and a mathematical model to make predictions about the biosensor response. Reliable predictions about biosensor responses can provide valuable information and facilitate biosensor development, particularly at an early development stage. The sensing process comprises several individual steps, such as phase partition equilibrium, intermediate reactions, mass-transport, and reaction kinetics, which take place in and between the gas and liquid phases. A quantitative description of each step was worked out and finally combined into a mathematical model. The applicability of the model was demonstrated for a particular example of methanethiol gas detection by a cytochrome c biosensor. The model allowed us to predict the optical readout response of the biosensor from tabulated data and data obtained in simple liquid phase experiments. The prediction was experimentally verified with a planar three-electrode electro-optical cytochrome c biosensor in contact with methanethiol gas in a gas tight spectroelectrochemical measurement cell