Biomedical subjects

D J Smith

Publications and source records attributed to D J Smith.

At least 73 records · Page 4Linked to original sources

PubMed2000

Soluble nitric oxide donor and surfactant improve oxygenation and pulmonary hypertension in porcine lung injury.

Acute lung injury (ALI) is associated with diminished surfactant activity and pulmonary hypertension. NONOates are soluble NO donors which release NO in solution. Intratracheal NONOates reduce pulmonary hypertension and improve oxygenation in ALI. We hypothesized that the pharmacologic properties of NO donors would be unaltered after surfactant admixture in vitro and that aerosolized NONOate activity would be enhanced by surfactant pretreatment in vivo. NO donors were added to saline or surfactant and analyzed for nitrite/nitrate production and aortic ring vasodilation. Surfactant did not alter nitrate/nitrite production or aortic ring vasodilation. A porcine model of ALI with pulmonary hypertension was produced using intravenous oleic acid. Animals were assigned to Surfactant-Saline, Surfactant-NONOate, Saline-Saline, or Saline-NONOate groups. Saline or surfactant was instilled into the trachea, followed by gas exchange, pulmonary function, and hemodynamic measurements. NONOate or saline was then aerosolized, and additional data were collected. Oxygenation was improved in the Surfactant-NONOate group, while pulmonary hypertension was selectively reduced in both NONOate groups. Aerosolized NONOate following surfactant pretreatment improves oxygenation and reduces pulmonary hypertension in ALI.

Amino Acids, Diamino↗

PubMed2000

Production and characterization of a monoclonal antibody against the beta-adrenergic agonist ractopamine.

A monoclonal antibody was generated toward the beta-adrenergic agonist ractopamine hydrochloride ¿(1R,3R),(1R, 3S)-4-hydroxy-alpha-[[[3-(4-hydroxyphenyl)-1-methylpropyl]amino]methy l]benzenemethanol hydrochloride¿. Ractopamine-glutarate-keyhole limpet hemocyanin (KLH) was used as the antigen for antibody generation in mice. Clone 5G10, secreted antibody with isotype IgG1kappa, was used for the development of an immunoassay. The selected antibody was specific for racemic ractopamine with an IC(50) of 2.69 +/- 0.36 ng/mL (n = 15). Antibody binding toward ractopamine was stereoselective with (1R,3R)-ractopamine having an IC(50) of 0.55 +/- 0.09 ng/mL (n = 3). IC(50) values for the (1S, 3R)-, (1S,3S)-, and (1R,3S)-ractopamine stereoisomers were 2.00 +/- 0.37, 140 +/- 23, and 291+/- 32 ng/mL (n = 3), respectively. Phenethanolamine beta-agonists showed low cross-reactivity. Studies using a series of ractopamine metabolites and ractopamine analogues demonstrated structural requirements for the antibody binding. A free phenolic group on the N-butylphenol moiety was required for high-affinity binding because methoxylated analogues and metabolites glucuronidated at this phenol generally had IC(50) values greater than 200 ng/mL. Ractopamine analogues methoxylated or glucuronidated at the ethanolamine phenol had IC(50) values of 0.7-2.6 ng/mL. Lack of a benzylic hydroxyl group was of less importance to antibody binding than was the correct stereochemical orientation (3R) of ractopamine's N-phenylalkyl group. In conclusion, a highly specific monoclonal antibody to ractopamine hydrochloride was developed that could be of potential utility in screening assays.

Adrenergic beta-Agonists↗

PubMed2000

Stereochemical composition of clenbuterol residues in edible tissues of swine.

A gas chromatography-mass spectrometry method was developed to measure the stereochemical residues of clenbuterol derivatives in edible tissues of swine. Clenbuterol present in tissue extracts was derivatized with phosgene to form clenbuterol oxazolidin-3-one, which was then separated into component enantiomers using a dimethyl beta-cyclodextrin capillary gas chromatographic column. Purified clenbuterol stereoisomers, isolated using published liquid chromatographic techniques, were used to determine stereoisomer elution order, stereoisomer racemization potential, and accuracy of the method. The stereochemical composition of clenbuterol could be measured at tissue concentrations of <2 ppb using the method. The dextrorotatory stereoisomer was the predominant clenbuterol stereoisomer present in edible tissues of hogs slaughtered after withdrawal periods of 0, 3, and 7 days, with a (+)/(-) isomer ratio of about 3:1. The prevalence of the dextrorotatory stereoisomer in edible tissues of hogs at all withdrawal periods suggests that stereoselective processes are occurring during the absorption, distribution, metabolism, and (or) excretion of clenbuterol. The effect of clenbuterol dose on its stereochemical composition in edible tissues is unknown but will be an area of further investigation.

Adrenergic beta-Agonists↗

PubMed2000

Hollow porous particles in metered dose inhalers.

PURPOSE: To assess the physical stability and aerosol characteristics of suspensions of hollow porous microspheres (PulmoSpheres) in HFA-134a. METHODS: Cromolyn sodium, albuterol sulfate, and formoterol fumarate microspheres were prepared by a spray-drying method. Particle size and morphology were determined via electron microscopy. Particle aggregation and suspension creaming times were assessed visually, and aerosol performance was determined via Andersen cascade impaction and dose uniformity studies. RESULTS: The hollow porous particle morphology allows the propellant to permeate freely within the particles creating a novel form of suspension termed a homodispersion, wherein the dispersed and continuous phases are identical, separated by an insoluble interfacial layer of drug and excipient. Homodispersion formation improves suspension stability by minimizing the difference in density between the particles and the medium, and by reducing attractive forces between particles. The improved physical stability leads to excellent dose uniformity. Excellent aerosolization efficiencies are also observed with PulmoSpheres formulations, with fine particle fractions of about 70%. CONCLUSIONS: The formation of hollow porous particles provides a new formulation technology for stabilizing suspensions of drugs in hydrofluoroalkane propellants with improved physical stability, content uniformity, and aerosolization efficiency.

Administration, Inhalation↗

PubMed2000

Novel lipid-based hollow-porous microparticles as a platform for immunoglobulin delivery to the respiratory tract.

PURPOSE: Delivery of specific antibodies or immunoglobulin constructs to the respiratory tract may be useful for prophylaxis or active treatment of local or systemic disorders. Therefore, we evaluated the utility of lipid-based hollow-porous microparticles (PulmoSpheres) as a potential delivery vehicle for immunoglobulins. METHODS: Lipid-based microparticles loaded with human immunoglobulin (hIgG) or control peptide were synthesized by spray drying and tested for: i) the kinetics of peptide/protein release, using ELISA and bioassays; ii) bioavailability subsequent to nonaqueous liquid instillation into the respiratory tract of BALB/c mice, using ELISA and Western blotting; iii) bioactivity in terms of murine immune response to xenotypic epitopes on human IgG, using ELISA and T cell assays; and iv) mechanisms responsible for the observed enhancement of immune responses, using measurement of antibodies as well as tagged probes. RESULTS: Human IgG and the control peptide were both readily released from the hollow-porous microspheres once added to an aqueous environment, although the kinetics depended on the compound. Nonaqueous liquid instillation of hIgG formulated in PulmoSpheres into the upper and lower respiratory tract of BALB/c mice resulted in systemic biodistribution. The formulated human IgG triggered enhanced local and systemic immune responses against xenotypic epitopes and was associated with receptor-mediated loading of alveolar macrophages. CONCLUSIONS: Formulation of immunoglobulins in hollow-porous microparticles is compatible with local and systemic delivery via the respiratory mucosa and may be used as means to trigger or modulate immune responses.

Administration, Inhalation↗

PubMed2000

Induction of secretory immunity with bioadhesive poly (D,L-lactide-co-glycolide) microparticles containing Streptococcus sobrinus glucosyltransferase.

The effect of mucosal delivery of Streptococcus sobrinus glucosyltransferase (GTF) in bioadhesive poly (D,L-lactide-co-glycolide) (PLGA) microparticles on induction of salivary IgA and serum IgG antibody responses was measured in Sprague-Dawley rats. Preparations of GTF/PLGA/gelatin microparticles, or PLGA/gelatin microparticles or GTF in alum, were administered four times at weekly intervals by intranasal or intragastric routes. Two subcutaneous injections of GTF in PLGA/gelatin microparticles or in alum were given to separate groups of rats. Significant elevations in salivary IgA antibody levels to S. sobrinus GTF were observed only in the groups immunized intranasally 28 days after immunizations were begun. Five of six rats given the GTF microparticles intranasally had positive salivary IgA antibody responses to GTF, and the mean salivary IgA antibody level of this group was 30-fold higher than any other mucosally or systemically immunized group. Salivary IgA responses in the GTF-microparticle group remained significantly higher than all other mucosally immunized groups for at least 10 weeks after the primary immunization. All rats in this group demonstrated aspects of anamnesis following a more limited secondary course of intranasal administration. Intranasal administration of GTF in microparticles also induced a serum IgG response to GTF in some rats. After secondary intranasal GTF microparticle administration, several rats had sustained serum IgG antibody levels that were within the range of sera from rats subcutaneously injected with GTF in microparticles or in alum. Thus intranasal delivery of GTF-containing bioadhesive microparticles induced the highest and longest lasting salivary immune response of any mucosal or systemic route or vehicle tested and could be expected to be a useful method for induction of mucosal immunity.

Administration, Intranasal↗

PubMed2000

A genetic screen for novel behavioral mutations in mice.

A genetic screen using mice was performed to identify dominant loci affecting behavior. Mice were mutagenized with ENU, then bred to examine their G1 offspring for behavioral abnormalities. Potentially mutant G1 pups were screened through a variety of behavioral assays, including tests of learning and memory, sensorimotor gating, fear and anxiety, nociception (pain perception) and locomotor activity. Mice falling outside the normal performance distribution in these tests were considered potential behavioral mutants and were bred for further analysis. Outliers included both animals with very discrete defects and animals with abnormal performance across a range of tests. To date, we have identified two confirmed mutants affecting sensorimotor gating. These results provide further impetus for the use of random mutagenesis screens as a tool for dissecting the genetic basis of brain and behavior.

Alkylating Agents↗

PubMed2000

Off-axis electron holography of patterned magnetic nanostructures.

Magnetization reversal processes in lithographically patterned magnetic elements that have lateral dimensions of 70-500 nm, thicknesses of 3-30 nm and a wide range of shapes and layer sequences have been followed in situ using off-axis electron holography in the transmission electron microscope. This technique allows domain structures within individual elements and the magnetic interactions between them to be quantified at close to the nanometre scale. The behaviour of 30 nm-thick Co elements was compared with that of 10 nm-thick Ni and Co elements, as well as with Co/Au/Ni trilayers. The hysteresis loops of individual elements were determined directly from the measured holographic phase images. The reproducibility of an element's domain structure in successive cycles was found to be affected by the out-of-plane component of the applied magnetic field and by the exact details of its initial magnetic state. Close proximity to adjacent elements led to strong intercell coupling, and remanent states with the in-plane magnetic field removed included domain structures such as solenoidal (vortex) states that were never observed during hysteresis cycling. Narrow rectangular bars reversed without the formation of end domains, whereas closely separated magnetic layers within individual elements were observed to couple to each other during field reversal.

Journal Article↗

PubMed2000

Identification of turkey biliary metabolites of ractopamine hydrochloride and the metabolism and distribution of synthetic [14C]ractopamine glucuronides in the turkey.

1. The bile duct cannulated turkey poult (n = 3) dosed orally with [14C]ractopamine HCl [(1R*,3R*),(1R*,3S*)-4-hydroxy-alpha-[[[3-(4-hydroxy[14C]phenyl)-1-methy lpropyl]amino]methyl]-benzenemethanol hydrochloride; 19.9 mg; 9.28 microCi] excreted 37.4 +/- 12.1% (mean +/- SD) of the administered radioactivity in bile by 24 h post-dosing. 2. A mono-glucuronide, conjugated at C-10 (the methylpropylamino phenol) of ractopamine, accounted for 76.6% of biliary radioactivity. 3. Urine collected from the colostomized turkey poult (n = 3) orally dosed with synthetic [14C]ractopamine-glucuronides (10.1 mg; 3.6 microCi) contained 11.9 +/- 1.0% (mean +/- SD) of the administered radioactivity 24 h after dosing, indicating that some absorption of radioactivity occurred. Faeces contained 60.6% of the administered radioactivity and carcasses (with gastrointestinal tracts) contained 23.3% of the starting radioactivity. 4. Five colostomized poults were fitted with bile duct cannulas and were dosed intraduodenally with 10.2 mg (3.6 microCi) synthetic [14C]ractopamine-glucuronides. Urine and bile contained 15.5 +/- 2.2 and 16.8 +/- 2.1% respectively of the administered radiocarbon by 24 h post-dosing. Faeces contained 54.3% of the administered radioactivity. Total absorption of the dosed radioactivity averaged 33.4%. 5. Bile and urine collected from the colostomized, bile-duct cannulated bird contained mainly ractopamine glucuronides. Indirect evidence suggests that the dosed ractopamine glucuronides were not absorbed intact.

Adrenergic beta-Agonists↗

PubMed2000

Development of an immunoassay for the beta-adrenergic agonist ractopamine.

Antibody generated from ractopamine-hemiglutarate-KLH was used to develop a ractopamine ELISA. The antibody showed good sensitivity in phosphate buffer, with an IC50 of 4.2 ng/ml (ppb) toward ractopamine and 16.2 ng/ml toward glucuronides of ractopamine conjugated to the phenethanolamine phenol of ractopamine. Phenylbutylamine phenol glucuronides of the (RS, SR) ractopamine diastereoisomers showed about 4% cross-reactivity, but the glucuronide of the (RR, SS) diastereoisomers conjugated at the same phenolic group showed no detectable reactivity with the antibody. The antibody generally had cross-reactivity towards compounds with bis-phenylalkyl amine structures rather than compounds with simple branched N-alkyl substituents. For example, the antibody showed little or no cross reactivity towards clenbuterol, isoproterenol, metaproterenol, and salbutamol, but cross-reacted with dobutamine. The system demonstrated a matrix effect similar to other enzyme immunoassays, dilution of urine decreased but did not eliminate the matrix effect.

Adrenergic beta-Agonists↗

PubMed2000

Evaluation of commercial immunoassays for cross-reactivity to clenbuterol stereoisomers and bovine metabolites.

Several commercially available immunoassay kits have been developed to detect the beta-adrenergic agonist clenbuterol HCl. Technical materials supplied with the kits do not generally report cross-reactivity with clenbuterol metabolites. Use of such kits to quantitate clenbuterol might lead to an overestimation of parent drug if metabolites were present. The objective of this study was to measure the cross-reactivity of clenbuterol metabolites with several commercially available clenbuterol immunoassays. Three clenbuterol-glucuronide conjugates, clenbuterol-sulphamate, 4-amino-3,5-dichloro-hippuric acid (clenbuterol-hippurate), and purified clenbuterol-stereoisomers were tested for cross-reactivity. The clenbuterol-sulphamate metabolite showed significant cross-reactivity (42-77%), but clenbuterol-hippurate showed very little competition (< 0.2%) towards clenbuterol. Clenbuterol-glucuronides had little (0.1-1.6%) cross-reactivity. In addition, (R)-, (S)-, and racemic clenbuterol were used to determine the stereospecificity of the kits. Both (R)- and (S)-clenbuterol competed for binding in two of the kits, however, in one kit the (S)-clenbuterol stereoisomer had an affinity 100 times greater than the (R)-stereoisomer. The presence of significant quantities of the sulphamate metabolite of clenbuterol in a biological matrix would cause an overestimation of the amount of parent clenbuterol. This study illustrates the inherent problems of using unvalidated immunoassays for quantitation purposes.

Adrenergic beta-Agonists↗

PubMed2000

T(h)1 transmigration anergy: a new concept of endothelial cell-T cell regulatory interaction.

Stimulation of endothelial cells (EC) with IFN-gamma generates selective enhancement of T(h)1 cell transmigration and induction of MHC class II expression on EC. In the present study, we tested whether antigen presentation by EC could influence transmigrating T cells in an in vitro system. Bacterial antigen presentation by EC from primary culture and after cloning induced antigen-specific anergy of transmigrating T(h)1 clone cells in a MHC class II-dependent manner as characterized by non-responsiveness to subsequent antigen presentation and inability to produce IL-2. This T cell transmigration anergy induced by EC was abrogated by anti-rat CD28 mAb, suggesting that lack of B7 co-stimulatory signals by EC might be related to the induction of anergy. While MHC class II expression on primary and cloned EC was observed after IFN-gamma stimulation, these cells never expressed B7. B7-1 gene-transfected endothelial clone cells (ECC/B7-1) were developed to elucidate the influence of B7 co-stimulation by EC. ECC/B7-1 induced proliferation of T(h)1 clone cells, whereas ECC did not induce proliferation in co-culture of T(h)1 clone cells and EC stimulated with IFN-gamma and antigen. In the transmigration assay, ECC/B7-1 did not induce transmigration anergy of T(h)1 clones or T(h)1 lines unless anti-rat B7-1 blocking mAb was added. Therefore, in rats, the T cell anergy induced during transmigration across a layer of EC seemed to be due to antigen presentation in the absence of B7 on the EC. We introduce the concept of transmigration anergy in this manuscript. Thus, EC can play a critical immune regulatory role in the context of antigen presentation by MHC class II to transmigrating T cells.

Animals↗

PubMed2000

High dietary manganese lowers heart magnesium in pigs fed a low-magnesium diet.

Young pigs were fed a diet moderately high or low in manganese (Mn) (0.95 +/- 0.10 mmol Mn/kg, n = 8 or 0.040 +/- 0.003 mmol Mn/kg, n = 6) and deficient in magnesium (Mg) (4.1 mmol Mg/kg) for 5 wk. All eight pigs consuming the high Mn diet died following convulsive seizures, whereas only two of six died in the group fed low Mn. In an attempt to determine the cause of death, a subsequent study examined the interactive effect of deficient dietary Mg and Mn on the tissue distribution of Mg and Mn. Pigs were individually fed, for 5 wk, diets that contained: 4.1 mmol Mg/kg and 36.0 micromol Mn/kg, 4.1 mmol Mg/kg and 0.91 mmol Mn/kg, 4.1 mmol Mg/kg and 0.91 mmol Mn/kg with added ultratrace minerals, or 41.1 mmol Mg/kg and 0. 91 mmol Mn/kg, and ultratrace minerals. Liver and skeletal muscle Mn concentrations were significantly elevated by increased dietary Mn. Increased dietary Mn did not affect heart Mn, but heart Mg concentrations were significantly depressed by high, as compared to low, dietary Mn (38.7 +/- 3.3 vs. 32.7 +/- 2.6 mmol Mg/kg). These data suggest high dietary Mn may exacerbate Mg deficiency in heart muscle and thus may be a complicating factor in the deaths observed in Mg-deficient pigs.

Animals↗

PubMed2000

Outcomes in breast reduction surgery.

Previous studies have established that patients with macromastia rate their physical and emotional health as substantially poorer than a control population. The aim of the current study was to confirm this discrepancy, and to evaluate the hypothesis that patients with macromastia who undergo bilateral reduction mammaplasty experience a marked improvement of their general health, both physical and emotional, when compared with their preoperative state and age-matched control population. Sixty-nine consecutive patients were enrolled and evaluated preoperatively and 9 months postoperatively. The methods used for patient evaluation were the Short Form SF-36, a health-related quality-of-life questionnaire, and the Brief Symptom Inventory (BSI), a self-reporting instrument used to assess psychological symptoms. Preoperatively, all patients reported physical health poorer than the age-matched control group. At 9 months postoperatively, patients reported substantial improvement in all areas measured by SF-36 and in the variables this study measured with BSI. Postoperative groups reported their health to be similar to the nonpatient control groups. These findings confirm the therapeutic role of bilateral reduction mammaplasty in alleviation of symptoms associated with macromastia and in restoration of normal physical and emotional functioning.

Adult↗

PubMed2000

Changes in glutamine and glutamate concentrations for tracking training tolerance.

PURPOSE: The purpose was to monitor high-performance athletes throughout training macrocycles and competitions and examine the changes in plasma glutamine (Gm) and glutamate (Ga) concentrations in order to develop a model of tolerance to training. METHODS: Plasma glutamine and glutamate concentrations of 52 National team athletes (31 male and 21 female) divided into male and female groups of speed skating, swimming, and cross-country skiing were measured in an early season rested condition to determine highest Gm and lowest Ga concentrations and over 2-4 macrocycles, which included heavy training to establish lowest Gm and highest Ga concentrations. RESULTS: In the rested condition, there were no differences within and between the male and female groups, excluding five athletes (OTA) who became overtrained in heavy training. The mean (+/-SD) Gm concentration was 585 +/- 54 micromol x L(-1), Ga concentration 101 +/- 16 micromol x L(-1), and Gm/Ga ratio 5.88 +/- 0.84 micromol x L(-1). The OTA had a significantly higher Ga concentration of 128 +/- 16 micromol x L(-1) and lower Gm/Ga ratio of 4.43 +/- 0.49 micromol x L(-1) than all the other groups. In heavy training, there was a significant decrease (P < 0.05) in Gm concentration to 522 +/- 53 micromol x L(-1), significant increase in Ga concentration to 128 +/- 19 micromol x L(-1) and significant decrease in Gm/Ga ratio to 4.15 +/- 0.57 micromol x L(-1). The OTA Gm concentration of 488 +/- 31 micromol x L(-1) was significant lower than only the male speed skating and swimming groups. However, the Ga concentration of 171 +/- 17 micromol x L(-1) and Gm/Ga ratio of 2.88 +/- 0.27 micromol x L(-1) were significantly higher and lower respectively than all other groups. CONCLUSIONS: Based on the changes in Gm and Ga concentration under different training conditions, we propose an athlete tolerance to training model where glutamine concentration reflects tolerance to volume of work and glutamate concentration reflects tolerance to high intensity training. We suggest that the Gm/Ga ratio may globally represent overall tolerance to training.

Adult↗

PubMed2000

Coimmunization with complementary glucosyltransferase peptides results in enhanced immunogenicity and protection against dental caries.

Peptide constructs from the catalytic (CAT) and glucan-binding (GLU) regions of the mutans streptococcal glucosyltransferase enzymes (GTF) can provide immunity to dental caries infection. A strategy of coimmunization was tested to determine whether protection could be enhanced. Rats were immunized with one of the previously described peptide constructs from the CAT or GLU region of the GTF of mutans streptococci or coimmunized with a combination of these constructs (CAT-GLU). Coimmunized animals demonstrated significantly higher serum immunoglobulin G (IgG) and salivary IgA antibody levels to CAT or GTF than rats immunized with either construct alone. To assess the functional significance of coimmunization with these constructs, animals were immunized as above or with Streptococcus sobrinus GTF and then infected with S. sobrinus to explore the effects of immunization on immunological, microbiological, and disease (dental caries) parameters. Serum antibody from the communized group inhibited S. sobrinus GTF-mediated insoluble glucan synthesis in vitro above that of the individual-construct-immunized groups. Immunization with CAT or GLU constructs resulted in significantly reduced dental caries after infection with S. sobrinus compared with sham-immunized animals. Coimmunization produced greater reductions in caries than after immunization with either CAT or GLU. Also, significant elevations in lymphocyte proliferative responses to CAT, GLU, and GTF were observed after coimmunization with CAT-GLU compared with the responses after immunization with the individual constructs. The results suggested that increased numbers of memory T cells, which could proliferate to CAT, were generated by coimmunization. The experiments support the functional significance of these GTF domains in dental caries pathogenesis and present coimmunization as a simple alternative to intact GTF to enhance protective immunity against cariogenic microorganisms.

Amino Acid Sequence↗

PubMed2000

Ovine male genital duct epithelial cells differentiate in vitro and express functional CFTR and ENaC.

To investigate the biology of the male genital duct epithelium, we have established cell cultures from the ovine vas deferens and epididymis epithelium. These cells develop tight junctions, high transepithelial electrical resistance, and a lumen-negative transepithelial potential difference as a sign of active transepithelial ion transport. In epididymis cultures the equivalent short-circuit current (I(sc)) averaged 20.8+/-0.7 microA/cm(2) (n = 150) and was partially inhibited by apical application of amiloride with an inhibitor concentration of 0.64 microM. In vas deferens cultures, I(sc) averaged 14.4+/-1.1 microA/cm(2) (n = 18) and was also inhibited by apical application of amiloride with a half-maximal inhibitor concentration (K(i)) of 0.68 microM. The remaining amiloride-insensitive I(sc) component in epididymis and vas deferens cells was partially inhibited by apical application of the Cl(-) channel blocker diphenylamine-2-carboxylic acid (1 mM). It was largely dependent on extracellular Cl(-) and, to a lesser extent, on extracellular HCO(-)(3). It was further stimulated by basolateral application of forskolin (10(-5) M), which increased I(sc) by 3.1+/-0.3 microA/cm(2) (n = 65) in epididymis and 0.9+/-0.1 microA/cm(2) (n = 11) in vas deferens. These findings suggest that cultured ovine vas deferens and epididymis cells absorb Na(+) via amiloride-sensitive epithelial Na(+) channels (ENaC) and secrete Cl(-) and HCO(-)(3) via apical cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels. This interpretation is supported by RT-PCR data showing that vas deferens and epididymis cells express CFTR and ENaC mRNA.

Amiloride↗

PubMed2000

Water-insoluble glucan synthesis by mutans streptococcal strains correlates with caries incidence in 12- to 30-month-old children.

Early mutans streptococci (MS) infection has been associated with higher caries activity in childhood. Since colonization with MS does not always lead to caries activity, additional factors may be involved in MS cariogenicity. For example, MS may differ in virulence traits such as the potential to synthesize glucan polymers from sucrose. In the present study, we tested the hypothesis that caries activity can be associated with variations in virulence factor expression of MS-infecting strains. At baseline, levels of MS obtained by the tongue-blade sampling method, and the presence of visible plaque on upper incisors, were measured in 101 12- to 30-month-old children. Dental caries lesions were diagnosed at baseline and after one year. Caries incidence data were then used to select ten caries-free and nine caries-active children from whom a total of 20 MS fresh isolates was studied. Water-insoluble glucan (WIG) synthesis, final pH, and sucrose-dependent adherence on glass surfaces were measured in these MS isolates. Concentrated culture supernatants were separated in duplicate SDS-PAGE gels, which were then either stained for protein or incubated with 5% sucrose. The intensities of the WIG bands developed in the 5% sucrose PAGE gels and the corresponding protein-stained GTF bands were measured by scanning densitometry. High MS levels (> or = 100 CFU) were associated with high caries incidence (p < 0.01). The presence of visible plaque did not correlate with caries incidence. The intensities of WIG bands were positively correlated with caries incidence (p < 0.05) and with the ability of MS to adhere to glass surfaces (p < 0.05). Analysis of our data suggests that the ability to synthesize WIG is an important virulence factor in initial caries development by increasing MS adherence and accumulation in the plaque of young children.

Bacterial Adhesion↗