Association of Streptococcus mutans Infection and Oral Developmental Nodules in Pre-dentate Infants

Since dental caries may present soon after tooth eruption, we hypothesized that colonization of Streptococcus mutans can occur in the predentate stages. In this study, we examined S. mutans colonization and its association with oral developmental nodules (Bohn's nodules) in 60 pre-term and 128 full-term, three-month-old infants. Overall, S. mutans was cultured from 30% (56/188) of the infants, and oral developmental nodules were noted in 55% (103/188). Compared with the pre-term, full-term infants showed a higher prevalence of S. mutans (34% vs. 20%, p < 0.02) as well as developmental nodules (61% vs. 42%, p < 0.05). In both groups, S. mutans was positively associated with numbers of developmental nodules in a dose-response relationship (p < 0,001), and with maternal salivary levels of the bacteria (p = 0.03). The permanence of S. mutans infection was confirmed by repeat saliva sampling at 6 months of age. Our results thus showed that many infants have already acquired S. mutans at 3 months of age, prior to tooth eruption.

Oral Colonization of Streptococcus mutans in Six-month-old Predentate Infants

We hypothesize that S. mutans colonization occurs more frequently in pre-term children due to their relative immaturity. In this study of 172 predentate, six-month-old infants, we found that 50% of pre-term and 60% of full-term children harbored S. mutans. The colonization was confirmed by repeat sampling. Although there were minor differences, factors associated with S. mutans infection in pre-term and full-term infants were generally similar. In both groups, increased frequency of sugar was ranked the most important factor (p < 0.001), followed by breast-feeding (p < 0.001), and habits which allowed saliva transfer from mother to infant (p < 0.01). By contrast, non-colonization of S. mutans was associated with multiple courses of antibiotics (p < 0.001). Compared with pre-term children, there were higher percentages of full-term who had night feedings and consumed sugar during sleep times. Mothers with infected infants had S. mutans levels > 5 x 10(5) CFU/mL saliva (p < 0.001), poorer oral hygiene,, more periodontal disease, and lower socio-economic status (P < 0.02) and snacked frequently (p < 0.001), compared with mothers with non-infected infants.

Functional development of the inferior colliculus (IQ and its relationship with the auditory brainstem response (ABR) in the tammar wallaby (Macropus eugenii)

To discover the developmental relationship between the auditory brainstem response (ABR) and the focal inferior colliculus (IC) response, 32 young tammar wallabies were used, by the application of simultaneous ABR and focal brainstem recordings, in response to acoustic clicks and tone bursts of seven frequencies. The ic or the tammar wallaby undergoes a rapid functional development from postnatal day (PND) 114 to 160. The earliest (PND 114) auditory evoked response was recorded from the rostral IC. With development, more caudal parts of the IC became functional until age about PND 127, when all parts of the IC were responsive to sound. Along a dorsoventral direction, the duration of the IC response decreased, the peak latency shortened, while the amplitude increased, reaching a maximum value at the central IC, then decreased. After PND 160, the best frequency (BF) of the ventral IC was the highest, with values between 12.5 and 16 kHz, the BF of the dorsal IC was the lowest, varying between 3.2 and 6.4 kHz, while the BF of the central IC was between 6.4 and 12.5 kHz. Between PND 114 and 125, the IC response did not have temporal correlation with the ABR. Between PND 140 and 160, only the early components of the responses from the ventral and central IC correlated with the P4 waves of the ABR. After PND 160, responses recorded from different depths of the IC had a temporal correlation with the ABR. (C) 2001 Published by Elsevier Science B.V.

Structural Dynamics in (ND4)2[Cu(D2O)6](SO4)2

The extended X-ray absorption fine structure spectroscopy (EXAFS) of (ND4)(2)[CU(D2O)(6)](SO4)(2) at 5, 14,100, 200, and 298 K is reported. This indicates that the Cu-O bond lengths of the Cu(D2O)(6)(2+) ion do not change significantly within this temperature range, which contrasts with EPR results and X-ray and neutron diffraction experiments, which imply that two of the Cu-(D2O) bonds converge in length as the temperature is raised. The EXAFS measurements thus confirm that the bond distances yielded by the diffraction experiments refer to the average positions of ligands involved in a dynamic equilibrium in which the directions of the long and intermediate bonds of the Jahn-Teller distorted Cu(D2O)(6)(2+) ion are interchanged in the crystal lattice. Analysis of the displacement parameters is consistent with this interpretation, as are the wave functions calculated using a model involving Jahn-Teller vibronic coupling and the influence of lattice strain interactions.

Photoinduced electron transfer and electronic energy transfer in naphthyl-appended cyclams

A series of novel macrocyclic tetraaza ligands that incorporate a naphthalene moiety as a photoactive chromophore have been prepared and structurally characterized as their Cu(II) complexes. Variable-temperature photophysical studies have concluded that the luminescence quenching evident in the Cu(H) complexes is due to intramolecular electronic energy transfer (EET). In their free-base forms, these ligands undergo reductive luminescence quenching via photoinduced electron transfer (PET) reactions, with proximate amine lone pairs acting as electron donors. Consequently, the emission behavior can be modulated by variations in pH and/or the presence of other Lewis acids such as Zn(H).

The behaviour of phenylphosphine oxide containing polyimides in a water plasma following gamma-radiolysis

The surface oxidation of two polyimides containing fluorinated phenylphosphine oxide units, TOR-RC and TOR-RC ODPA, have been studied by (XPS) spectroscopy following gamma -radiolysis under vacuum or in air and subsequent treatment in a water plasma. The changes in the O 1s/C 1s ratios obtained from (XPS) analysis showed that on exposure to the water plasma the ratio increases and then levels to a constant value which is similar to that found for exposure to the plasma without prior gamma -radiation treatment. Evidence for the formation of phosphate species was also obtained from the (XPS) analyses. (C) 2001 Elsevier Science Ltd. All rights reserved.

Human papillomavirus type 6b virus-like particles are able to activate the Ras-MAP kinase pathway and induce cell proliferation

The initial step in viral infection is the attachment of the virus to the host cell via an interaction with its receptor. We have previously shown that a receptor for human papillomavirus is the alpha6 integrin. The alpha6 integrin is involved in the attachment of epithelial cells with the basement membrane, but recent evidence suggests that ligation of many integrins results in intracellular signaling events that influence cell proliferation. sere we present evidence that exposure of A431 human epithelial cells to human papillomavirus type 6b L1 virus-like particles (VLPs) results in a dose-dependent increase in cell proliferation, as measured by bromodeoxyuridine incorporation. This proliferation is Lost if VLPs are first denatured or incubated with a monoclonal antibody against L1 protein. The MEK1 inhibitor PB98059 inhibits the VLP-mediated increase in fell proliferation, suggesting involvement of the Ras-MAP kinase pathway, Indeed, VLP binding results in rapid phosphorylation of the beta4 integrin upon tyrosine residues and subsequent recruitment of the adapter protein She to beta4, Within 30 min, the activation of Ras, Raf, and Erk2 was observed. Finally, the upregulation of c-myc mRNA was observed at 60 min, These data indicate that human papillomavirus type 6b is able to signal cells via the Ras-MAP kinase pathway to induce cell proliferation. We hypothesize that such a mechanism would allow papillomaviruses to infect hosts more successfully by increasing the potential pool of cells they are able to infect via the initiation of proliferation in resting keratinocyte stem and suprabasal cells.

X-linked neonatal diabetes mellitus, enteropathy and endocrinopathy syndrome is the human equivalent of mouse scurfy

To determine whether human X-linked neonatal diabetes mellitus, enteropathy and endocrinopathy syndrome (IPEX; MIM 304930) is the genetic equivalent of the scurfy (sf) mouse, we sequenced the human ortholog (FOXP3) of the gene mutated in scurfy mice (Foxp3), in IPEX patients. We found four non-polymorphic mutations. Each mutation affects the forkhead/winged-helix domain of the scurfin protein, indicating that the mutations may disrupt critical DNA interactions.

Elucidation of reaction scheme describing malondialdehyde-acetaldehyde-protein adduct formation

Malondialdehyde and acetaldehyde react together with proteins and form hybrid protein conjugates designated as MAA adducts, which have been detected in livers of ethanol-fed animals. Our previous studies have shown that MAA adducts are comprised of two distinct products. One adduct is composed of two molecules of malondialdehyde and one molecule of acetaldehyde and was identified as the 4-methpl-1,4-dihydropyridine-3,5-dicarbaldehyde derivative of an amino group (MHHDC adduct). The other adduct is a 1:1 adduct of malondialdehyde and acetaldehyde and was identified as the 2-formyl-3-(alkylamino)butanal derivative of an amino group (FAAB adduct). In this study, information on the mechanism of MAA adduct formation was obtained, focusing on whether the FAAB adduct serves as a precursor for the MDHDC adduct. Upon the basis of chemical analysis and NMR spectroscopy, two initial reaction steps appear to be a prerequisite for MDHDC formation. One step involves the reaction of one molecule of malondialdehyde and one of acetaldehyde with an amino group of a protein to form the FAAB product, while the other step involves the generation of a malondialdehyde-enamine. It appears that generation of the MDHDC adduct requires the FAAB moiety to be transferred to the nitrogen of the MDA-enamine. For efficient reaction of FAAB with the enamine to take place, additional experiments indicated that these two intermediates likely must be in positions on the protein of close proximity to each other. Further studies showed that the incubation of liver proteins from ethanol-fed rats with MDA resulted in a marked generation of MDHDC adducts, indicating the presence of a pool of FAAB adducts in the liver of ethanol-fed animals. Overall, these findings show that MDHDC-protein adduct formation occurs via the reaction of the FAAB moiety with a malondialdehyde-enamine, and further suggest that a similar mechanism may be operative in vivo in the liver during prolonged ethanol consumption.

Using Theory to Understand the Multiple Determinants of Low Participation in Worksite Health Promotion Programs

Low participation at the employee or worksite level limits the potential public health impact of worksite-based interventions. Ecological models suggest that multiple levels of influence operate to determine participation patterns in worksite health promotion programs. Most investigations into the determinants of low participation study the intrapersonal, interpersonal, and institutional influences on employee participation. Community- and policy-level influences have not received attention, nor has consideration been given to worksite-level participation issues. The purpose of this article is to discuss one macrosocial theoretical perspective—political economy of health—that may guide practitioners and researchers interested in addressing the community- and policy-level determinants of participation in worksite health promotion programs. The authors argue that using theory to investigate the full spectrum of determinants offers a more complete range of intervention and research options for maximizing employee and worksite levels of participation.

Corneal endothelial response to induced myopia in the chicken

Purpose: To investigate the role of corneal endothelial surface enlargement in the chicken myopia model in inducing corneal endothelial changes. Methods: Lid suture was performed on one eye of 1-day-old cockerels. Five chickens were killed at 1 week, and four chickens killed at each of 3 weeks, 6 weeks, and 10 weeks postnatal. The endothelial morphology was obtained by flat mounting the endothelial surface and the subsequent digitisation. Comparisons were undertaken between the control unsutured eye and the lid-sutured eye endothelium, and between the central endothelial areas compared to the peripheral endothelial areas in both the myopic and the normal corneas. Calculation of the contribution to the endothelial change by hypertrophy and mitosis were calculated using Bahn's formula. Results: Total endothelial surface area increased significantly over time in the myopic model compared to control eyes but the mean cell area of endothelial cells remained the same for both the enlarged myopic endothelial surface area and in the normal controls. Sampling from the central and the peripheral corneal endothelial surface also disclosed no difference. The mean cell area did increase steadily with age but was the same for both normal and myopic corneas. Conclusions: It would appear that there are equal contributions from hypertrophy and mitosis in the myopic group and the normal corneal group with a slightly increasing trend towards mitotic activity in the myopic corneal endothelial layer.