Low frequency sound propagation in activated carbon.

Activated carbon can adsorb and desorb gas molecules onto and off its surface. Research has examined whether this sorption affects low frequency sound waves, with pressures typical of audible sound, interacting with granular activated carbon. Impedance tube measurements were undertaken examining the resonant frequencies of Helmholtz resonators with different backing materials. It was found that the addition of activated carbon increased the compliance of the backing volume. The effect was observed up to the highest frequency measured (500 Hz), but was most significant at lower frequencies (at higher frequencies another phenomenon can explain the behavior). An apparatus was constructed to measure the effective porosity of the activated carbon as well as the number of moles adsorbed at sound pressures between 104 and 118 dB and low frequencies between 20 and 55 Hz. Whilst the results were consistent with adsorption affecting sound propagation, other phenomena cannot be ruled out. Measurements of sorption isotherms showed that additional energy losses can be caused by water vapor condensing onto and then evaporating from the surface of the material. However, the excess absorption measured for low frequency sound waves is primarily caused by decreases in surface reactance rather than changes in surface resistance.

In vitro metabolism of the specific endothelin-A receptor antagonist ZD4054 and clinical drug interactions between ZD4054 and rifampicin or itraconazole in healthy male volunteers.

ZD4054 is an oral specific endothelin-A receptor antagonist in development for the treatment of hormone-resistant prostate cancer. Both renal and metabolic processes contribute to its overall clearance. Two preclinical in vitro studies investigated the metabolism of ZD4054 using human liver microsomes, individual cytochrome P450 (CYP) isozymes, and flavin-containing monooxygenase isoforms. Two Phase I open-label crossover volunteer studies subsequently investigated in vivo drug interactions between ZD4054 and the CYP450 inducer rifampicin or CYP3A4 inhibitor itraconazole. The most abundant metabolite produced in in vitro incubations accounted for 12.8% of radioactivity after ZD4054 was incubated with CYP3A4. No significant flavin-containing monooxygenase metabolism of ZD4054 was observed. In the in vivo studies, rifampicin co-administration reduced the area under the concentration-time curve and maximum plasma concentration of ZD4054 by 68% and 29%, respectively, whilst co-administration with itraconazole was associated with an increase in ZD4054 area under the curve of approximately 28%. While co-administration of CYP450 inducers might be associated with reduced efficacy of ZD4054, dose reduction is unlikely to be required with concomitant administration of CYP3A4 inhibitors.

Accurate diagnosis of occlusal carious lesions--a stereo microscope evaluation of clinical diagnosis.

This study was undertaken to validate the caries status of 214 teeth by serial sectioning and microscopy after caries diagnosis using four methods. Two hundred and fourteen extracted human teeth with varying degrees of caries were mounted in the jaws of nine training manikins. All tooth surfaces were examined and recorded for caries by four dentists using bitewing radiographs, fibre-optic transillumination (FOTI), mirror alone and a mirror and sharp probe on two separate occasions. Thereafter the teeth were serially sectioned and assessed microscopically for depth of caries lesion on a graded score of 0-7. This report assessed the diagnostic outcome of 2,183 observations for occlusal surfaces. Sound diagnoses predominated over unsound until caries was present in the inner half of dentine. Specificity was between 90% and 95% and sensitivity 26% and 50% depending on which diagnostic method was used and where the sound/unsound threshold was set. Negative and positive predictive values were similarly influenced and varied between 53% and 80% and 73% and 90%, respectively. Probit analysis showed no significant differences (P < 0.05) between examiners and diagnostic methods. Diagnosis of occlusal caries undertaken in an in vitro simulated clinical situation is inaccurate until the caries lesion extends deep into the dentine no matter which of the four methods was used.

Examiner performance with visual, probing and FOTI caries diagnosis in the primary dentition.

To compare clinical reproducibility of dental caries diagnosis in the primary dentition under field conditions, a convenience sample of 5-year-old children in a nursery school in Germiston, was examined for dental caries by four dentists using visual (mirror), visual plus tactile (mirror plus probe) and fibre-optic transillumination (FOTI) methods. Seventeen children were examined on day one and 11 re-examined on day two. Inter-examiner agreement was high, above 90%. Visual examination on its own is comparable with the traditional visual plus tactile method and to FOTI under field conditions. New caries data collected by visual diagnosis alone may, reasonably, be compared with historical data diagnosed with visual + tactile examination.

Accumulation, distribution, and toxicity of copper in sediments of catfish ponds receiving periodic copper sulfate applications.

Copper sulfate (CuSO4) is applied periodically to commercial channel catfish (Ictalurus panctatus) ponds as an algicide or parasiticide. Current understanding of the chemistry of copper in soil-water systems suggests that copper may accumulate in pond sediments, although the forms and potential bioavailability of copper in catfish pond sediments are not known. This study investigated the accumulation and distribution of copper in the sediment of catfish ponds receiving periodic additions of CuSO4.5H2O. All ponds were constructed in Sharkey (very-fine, smectitic, thermic Chromic Epiaquert) soil. Nine 0.40-ha ponds received 59 applications of 2.27 kg CuSO4.5H2O per application per pond over 3 yr; no CuSO4.5H2O applications were made to nine additional ponds. Total Cu concentration in the sediments of CuSO4.5H2O-amended catfish ponds (172.5 mg kg(-1)) was four to five times higher than that in the sediments of nonamended ponds (36.1 mg kg(-1)). Copper accumulated in catfish pond sediments at a rate of 41 microg kg(-1) dry sediment for each 1 kg ha(-1) of CuSO4. 5H2O applied to ponds. Copper in the sediments of amended ponds was mainly in the organic matter-bound (30.7%), carbonate-bound (31.8%), and amorphous iron oxide-bound (22.1%) fractions with a considerable fraction (3.4%; 3 to 8 mg kg(-1)) in soluble and exchangeable fractions. This indicates that Cu accumulates differentially in various fractions, with proportionally greater initial accumulation in potentially bioavailable forms. However, toxicity bioassays with amphipods (Hyallela azteca) and common cattail (Typha latifolia L.) indicated that the effect of exposure to amended or nonamended pond sediments was not different.

Trauma to primary teeth of South African pre-school children.

A clinical survey of 1466 children of typical South African communities showed a prevalence rate of primary tooth trauma of 15%. Trauma was least common at age 1-2 years (10.7%) and most common at 4-5 years (20.6%). The commonest trauma seen was fracture of enamel only (71.8%) followed by fracture of dentine (11.2%), tooth loss (8.2%) and discolouration without other sign of injury (5.6%).

Lack of evidence for antisense suppression in the fungal plant pathogen Ustilago maydis.

Modulation of the expression of the Ustilago maydis Pyr3 gene, encoding dihydroorotase (DHOase), through antisense RNA regulation has been explored. This was done by placing the gene in sense and antisense orientations under the control of an hsp70-like gene promoter in a high-copy number autonomously replicating expression vector. Cells transformed with the antisense vector contained similar levels of DHOase activity to those found in cells harboring the expression vector alone. Transformants containing the antisense vector did not exhibit uridine-dependent growth, which would be expected for a Pyr3-deficient phenocopy. This was despite detection of high levels of antisense RNA transcripts in cells transformed with the Pyr3 antisense vector.

Defence-related gene activation during an incompatible interaction between Stagonospora (Septoria) nodorum and barley (Hordeum vulgare L.) coleoptile cells.

Two previously unidentified cDNA clones (bsi1 and bpr1-1) were isolated by differential hybridization from a cDNA library of Stagonospora (Septoria) nodorum (Berk) Castellani & E.G. Germano (teleomorph Phaeosphaeria (Leptosphaeria) nodorum (E. Muller) Hedjaroude-challenged barley (Hordeum vulgare L.) coleoptiles. bsi1 encoded a cysteine-rich protein containing 89 amino acids (aa) with a relative molecular mass (M(r)) of 9405. Protein sequence homologies showed that Bsi1 was very similar to an aluminium-induced protein from wheat and indicated that it was related to the Bowman-Birk-type proteinase inhibitors (BB-PIs). The predicted aa sequence of Bsi1 contained an N-terminal secretory signal sequence which implied that the protein was exported. The other clone, bprl-1, which was truncated at the 5' end, encoded a type-1 pathogenesis-related (PR-1) protein. The complete sequence of bpr1-1 was obtained after cloning a barley genomic DNA fragment and was shown to encode a basic protein containing 174 aa with a M(r) of 18 859. The deduced aa sequence of bpr1-1 contained both an N-terminal secretory signal sequence and a charged C-terminal extension. This latter sequence may represent a vacuolar targeting signal. bsil and bpr1-1 and four other defence-related genes (encoding 1,3-beta-glucanase, 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, a homologue of a putative wheat peroxidase, and barley leaf-specific thionin), showed increased transcription levels in S. nodorum-challenged coleoptiles, although their pattern of accumulation varied after inoculation (a.i.). The potential role of these induced genes in defence against fungal attack is discussed.

Isolation of an Ustilago maydis ERG11 gene and its expression in a mutant deficient in sterol 14 alpha-demethylase activity.

A gene (ERG11) encoding cytochrome P450 sterol 14 alpha-demethylase (P450(14DM)) was isolated from the maize pathogen, Ustilago maydis, by amplifying part of the coding region of the gene using PCR and by employing the amplified DNA fragment as a hybridization probe to recover the complete gene from an U. maydis lambda EMBL3 genomic library. The deduced amino acid sequence of the U. maydis gene showed homology to P450(14DM)s from other organisms and contained specific motifs which were hallmarks of P450s. Expression of the gene in an U. maydis mutant (A20) deficient in P450(14DM) led to only a partial restoration of P450(14DM) activity. Accumulation of ergosta-7,22-dienol and ergost-7-enol in A20 transformants containing the ERG11 gene implied that an additional mutation affecting sterol delta 5,6-desaturase activity accompanied the P450(14DM) lesion.

Anterior tooth trauma in eleven-year-old South African children.

Little new evidence on the prevalence of injury to the anterior teeth of children has been reported in the past five years and, in South Africa, trauma to the teeth of children in different ethnic groups has not been compared respectively. The purpose of this investigation was to determine the prevalence of dental trauma using well-defined criteria and to sample a specific age-group. Five regions were chosen and 1035 children in the eleven-year age-group were examined. No statistical significance was found between the ethnic groups related to the amount of injury sustained. For all groups, boys received more injuries than girls. The most common injury was fracture of the enamel of the maxillary central incisor. With 15 percent of the children receiving some level of trauma by age eleven years, this is one of the main dental treatment needs for South African children.

A gene encoding gamma-adaptin is required for apical extension growth in Ustilago maydis.

The nucleotide (nt) sequence of an Ustilago maydis (Um) gene that complemented a partially osmotic-remedial temperature-sensitive (or-ts) mutant defective in apical extension growth has been determined. It contained a continuous open reading frame (OFR) predicted to encode a protein of 853 amino acids (aa). The deduced aa sequence was homologous to gamma-adaptin, a component of clathrin-coated vesicles derived from the Golgi.

Energy intake, dental caries and periodontal disease in 11-year-old black children in two regions of Southern Africa: KwaZulu and Namibia.

The study examined energy intake in relation to dental caries and periodontal disease in 11-yr-old rural and urban black children in low fluoride areas of KwaZulu and Namibia (0.15 ppm F) and one higher fluoride area of Namibia (1.56 ppm F). Twenty-four hour dietary recalls were conducted by trained interviewers and daily energy intake estimated using the MRC dietary analysis programme. DMFS was recorded according to WHO criteria: periodontal disease was measured using CPITN and SAS was used for statistical analysis. The prevalence of dental caries and periodontal disease (using CPITN), were compared within three energy groupings; < or = 850 kcal/day; > 850, < 1400 kcal/day and > or = 1400 kcal/day. The rural low fluoride Namibian children had the lowest mean energy intake (616 kcal/day), which also was the grouping with highest healthy periodontal prevalence (65%). The urban groups had higher energy intakes than the rural communities. Statistically significant effects on caries prevalence were seen for country and fluoride grouping; for periodontal disease, significant effects were noted for country, fluoride group and environment. Energy intake had no statistically significant effect, so this is not a risk marker for the disease.

Discussion: diet and nutrition in dental health and disease.

The recognition in 1993 by the International Association of Dental Research (IADR) for the initiation of a Nutrition Research Group within the Association prompted this nutrition symposium related to diet and nutrition in health and disease. The IADR Nutrition Research Group is encouraged to collaborate with other nutritional research groups in important areas of medicine, food science technology, and agriculture to target health issues influenced by dietary choices, nutritional adequacy, and dental health status.

Seasonal variation of vitamin A (retinol) status in older men and women.

OBJECTIVE: The present study was undertaken to determine vitamin A status in 59 free-living (26 males, 33 females) healthy older persons (65-74 years) in winter and summer. DESIGN: Three-day dietary intake data for vitamin A along with carbohydrate, lipid and protein were collected during the summer (June-September) and again during the winter (November-March). In addition, retinol and its carrier proteins, retinol-binding protein (RBP) and transthyretin (TTR), were measured in the plasma in each season. RESULTS: The mean vitamin A intake met the Canadian Recommended Intake (RNI) for both gender and season. However, probability analysis of dietary data revealed that 7 and 11% of males, and 8 and 14% of females, in summer and winter, respectively, were at risk of deficiency. None of the subjects in the present study exhibited biochemical evidence of vitamin A deficiency as determined by plasma levels of retinol and its transport proteins. Overall, the mean intake of vitamin A was significantly higher in males than in females; no seasonal effect was observed. On the other hand, the plasma levels of retinol and its carrier proteins were significantly lower in winter season than in summer, without any gender variation effect. CONCLUSION: Although mean values for dietary intake and plasma concentration of vitamin A may indicate nutritional adequacy, a small proportion of an older population may be at nutritional risk. The prevalence of risk appears to be generally higher in the winter than in the summer season and in females than in males.

Isolation of an Ustilago maydis gene encoding 3-hydroxy-3-methylglutaryl-coenzyme A reductase and expression of a C-terminal-truncated form in Escherichia coli.

A gene encoding 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase was isolated from the maize fungal pathogen Ustilago maydis. This was accomplished by identifying cDNA and genomic clones that hybridized to an internal fragment of the gene, amplified from U. maydis genomic DNA by PCR. The nature of the gene was determined by nucleotide sequence analysis, and by comparing the derived amino acid sequence of the gene with HMG-CoA reductases from yeast, and from other organisms. The hydrophobic nature of the N-terminal region of the deduced protein sequence also supported the view that this gene encoded HMG-CoA reductase. A C-terminal-truncated fragment of the U. maydis HMG-CoA reductase gene was shown to be expressed in Escherichia coli in a catalytically active form. The expressed protein was also shown to be sensitive to an inhibitor of mammalian HMG-CoA reductase activity.

Isolation of the ERG2 gene, encoding sterol delta 8-->delta 7 isomerase, from the rice blast fungus Magnaporthe grisea and its expression in the maize smut pathogen Ustilago maydis.

The Magnaporthe grisea ERG2 gene, encoding delta 8-->delta 7 sterol isomerase, was isolated from a genomic library by heterologous hybridization to a fragment of the Ustilago maydis ERG2 gene. The isolated gene contained a reading frame of 745 bp which encoded a protein of 221 amino acids. The coding region was interrupted by a single putative 79-bp-long intron. The deduced amino-acid sequence exhibited similarity to the ERG2 gene products of U. maydis and of Saccharomyces cerevisiae, particularly in the central region of the proteins. The NH2-terminal of all three proteins contained a long stretch of amino acids that were strongly hydrophobic, suggesting that they may function by anchoring the protein to a membrane surface. The M. grisea ERG2 gene complemented a U. maydis deletion mutant in which the ERG2 gene had been removed using a one-step gene replacement procedure. The delta 8-->delta 7 sterol isomerase produced by the M. grisea ERG2 gene exhibited a level of sensitivity to the sterol biosynthesis inhibitor, tridemorph, similar to that of the enzyme derived from the U. maydis ERG2 gene.

Associations of dental caries with salivary mutans streptococci and acid producing bacteria in 5-year-old children from KwaZulu and Namibia.

Two hundred and eighty-five, 5-year-old children from rural and urban KwaZulu and Namibia were examined for dental caries, salivary mutans streptococci and salivary acid producing bacteria. The findings showed statistically significant correlations between salivary mutans streptococci counts and ds and dmfs scores in all groups of children, the highest values being in Namibian children. Salivary acid forming bacteria had low correlations with few statistically significant groups. While salivary mutans streptococci counts may be a useful caries screening method in children of this age, salivary acid forming bacterial counts appear unsuitable.