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.

The leucine-rich repeat as a protein recognition motif

Leucine-rich repeats (LRRs) are 20-29-residue sequence motifs present in a number of proteins with diverse functions. The primary function of these motifs appears to be to provide a versatile structural framework for the formation of protein-protein interactions. The past two years have seen an explosion of new structural information on proteins with LRRs. The new structures represent different LRR subfamilies and proteins with diverse functions, including GTPase-activating protein rna 1 p from the ribonuclease-inhibitor-like subfamily; spliceosomal protein U2A', Rab geranylgeranyltransferase, internalin B, dynein light chain 1 and nuclear export protein TAP from the SDS22-like subfamily; Skp2 from the cysteine-containing subfamily; and YopM from the bacterial subfamily. The new structural information has increased our understanding of the structural determinants of LRR proteins and our ability to model such proteins with unknown structures, and has shed new light on how these proteins participate in protein-protein interactions.

Glucose induced IEG expression in the thiamin-deficient rat brain

Glucose loading of rats made thiamin deficient by dietary deprivation of thiamin and the administration of pyrithiamin (40 mug/100 g, i.p.) precipitates an acute neuropathy, a model of Wernicke's encephalopathy in man (Zimitat and Nixon, Metab. Brain Dis. 1999;14:1-20). Immunohistochemical detection of Fos proteins was used as a marker to identify neuronal populations in the thiamin-deficient rat brain affected by glucose loading. As thiamin deficiency progressed, the extent and intensity of Fos-Like immunoreactivity (FLI) in brain structures typically affected by thiamin deficiency (the thalamus, mammillary bodies, inferior colliculus, vestibular nucleus and inferior olives) were markedly increased when compared to thiamin-replete controls. Glucose loading for 1-3 days further increased the intensity of FLI in these same regions, consistent with a dependence of Fos expression on carbohydrate metabolism as well as on thiamin deficiency. The timed acute changes that follow a bolus glucose load administered to thiamin-deficient animals may provide a sequential account of events in the pathogenesis of brain damage in this model of Wernicke's encephalopathy. (C) 2001 Elsevier Science B.V. All rights reserved.

Changes in non-22-kilodalton (kDa) isoforms of growth hormone (GH) after administration of 22-kDa recombinant human GH in trained adult males

GH is being used by elite athletes to enhance sporting performance. To examine the hypothesis that exogenous 22-kDa recombinant human GH (rhGH) administration could be detected through suppression of non-22-kDa isoforms of GH, we studied seventeen aerobically trained males (age, 26.9 +/- 1.5 yr) randomized to rhGH or placebo treatment (0.15 IU/kg/day for 1 week). Subjects were studied at rest and in response to exercise (cycle-ergometry at 65% of maximal work capacity for 20 min). Serum was assayed for total GH (Pharmacia IRMA and pituitary GH), 22-kDa GH (2 different 2-site monoclonal immunoassays), non-22-kDa GH (22-kDa GH-exclusion assay), 20-kDa GH, and immunofunctional GH. In the study, 3 h after the last dose of rhGH, total and 22-kDa GH concentrations were elevated, reflecting exogenous 22-kDa GH. Non-22-kDa and 20-kDa GH levels were suppressed. Regression of non-22-kDa or 20-kDa GH against total or 22-kDa GH produced clear separation of treatment groups. In identical exercise studies repeated between 24 and 96 h after cessation of treatment, the magnitude of the responses of all GH isoforms was suppressed (P < 0.01), but the relative proportions were similar to those before treatment. We conclude: 1) supraphysiological doses of rhGH in trained adult males suppressed exercise-stimulated endogenous circulating isoforms of GH for up to 4 days; 2) the dearest separation of treatment groups required the simultaneous presence of high exogenous 22-kDa GH and suppressed 20-kDa or non-22-kDa GH concentrations; and 3) these methods may prove useful in detecting rhGH abuse in athletes.

The response of molecular isoforms of growth hormone to acute exercise in trained adult males

Circulating GH consists of multiple molecular isoforms, all derived from the one gene in nonpregnant humans. To assess the effect of a potent stimulus to pituitary secretion on GH isoforms, we studied 17 aerobically trained males (age, 26.9 +/- 1.5 yr) in a randomized, repeat measures study of rest vs. exercise. Exercise consisted of continuous cycle ergometry at approximately 80% of predetermined maximal oxygen uptake for 20 min. Serum was assayed for total, pituitary, 22-kDa, recombinant, non-22-kDa, 20-kDa, and immunofunctional GH. All isoforms increased during, peaked at the end, and declined after exercise. At peak exercise, 22-kDa GH was the predominant isoform. After exercise, the ratios of non-22 kDa/total GH and 20-kDa GH/total GH increased and those of recombinant/pituitary GH decreased. The disappearance half-times for pituitary GH and 20-kDa GH were significantly longer than those for all other isoforms. We conclude that 1) all molecular isoforms of GH measured increased with and peaked at the end of acute exercise, with 22-kBa GH constituting the major isoform in serum during exercise; and 2) the proportion of non-22-kDa isoforms increased after exercise due in part to slower disappearance rates of 20-kDa and perhaps other non-22-kDa GH isoforms. It remains to be determined whether the various biological actions of different GH isoforms impact on postexercise homeostasis.

Being breastfed in infancy and breast cancer incidence in adult life: Results from the two Nurses' Health studies

Events during perinatal and early life may influence the incidence of breast cancer in adult life, and some case-control studies suggest that having been breastfed may reduce breast cancer risk. The authors studied this association among premenopausal and postmenopausal women by using data from the two Nurses' Health Studies, the Nurses' Health Study (using data from 1992 to 1996) and the Nurses' Health Study II (using data from 1991 to 1997). A history of being breastfed was self-reported by the study participants. During a total of 695,655 person-years, 1,073 cases of invasive breast cancer were diagnosed. The authors did not observe any important overall association between having been breastfed and the development of breast cancer later in life among premenopausal women (covariate-adjusted relative risk = 0.97, 95% confidence interval (CI): 0.78, 1.20) or postmenopausal women (covariate-adjusted relative risk = 1.12, 95% CI: 0.92, 1.37). No significant trend was observed with increasing duration of breastfeeding. The authors also used data on breastfeeding retrospectively collected from 2,103 mothers of participants of the two Nurses' Health Studies. With the mothers' reports, the covariate-adjusted odds ratio of breast cancer was 1.11 (95% CI: 0.88, 1.39) for women who were breastfed compared with those who were not. Data from these two large cohorts do not support the hypothesis that being breastfed confers protection against subsequent breast cancer.

An ESR study on gamma-irradiated poly(vinyl alcohol)

The formation of radicals in poly(vinyl alcohol), PVA, powder irradiated at 77 K by gamma -rays and the transformations of these radicals during photolysis with visible wavelengths and on thermal annealing have been studied. After irradiation a four-line ESR spectrum was observed. It was assigned to a triplet of the C-alpha-radical (38%), with a splitting of 3.27 mT, superimposed on a doublet (62%) with a splitting of 2.7 mT. The doublet appears to be composed of two radicals, one of which is photo-bleachable (58%) and the other which is not photo-bleachable (42%). This suggests that the latter radical is a neutral radical. The photo-bleachable component of the doublet has been assigned to a carbonyl anion radical. but the second doublet due to a neutral radical is unassigned. The total G-value for formation of radicals at 77 K was found to be 2.41 +/- 0.03. Upon illumination with visible light, the anion radicals were removed and the doublet components or the spectrum diminished in intensity, while the three-line spectrum of the C-alpha-radical became more clearly visible. This transition was due to the photo-detachment of electrons from traps which were proposed to be located on carbonyl groups in the polymer resulting from incomplete hydrolysis of the vinyl acetate. The photo-decay of the anion radicals could be satisfactorily described by a two-stage process. The first stage comprised the decay of approximately 80% of the anion radicals present, while the second stage was associated with the decay of the remaining 20%. Subsequent thermal annealing of a photolysed sample to 290 K led to a change in the shape of the spectrum to form a more clearly defined triplet, As the doublet of the neutral radical decays on thermal annealing between 150 and 250K, the C-alpha-radical is formed. (C) 2001 Elsevier Science Ltd. All rights reserved.

Evidence for three tumor suppressor loci on chromosome 9p involved in melanoma development

Cytogenetic and loss of heterozygosity (LOH) studies have long indicated the presence of a tumor suppressor gene (TSG) on 90 involved in the development of melanoma, Although LOH at 90 has been reported in approximately 60% of melanoma tumors, only 5-10% of these tumors have been shown to carry CDKN2A mutations, raising the possibility that another TSG involved in melanoma maps to chromosome 90. To investigate this possibility, a panel of 37 melanomas derived from 35 individuals was analyzed for CDKN2A mutations hy single-strand conformation polymorphism analysis and sequencing. The melanoma samples were then typed for 15 markers that map to 9p13-24 to investigate LOH trends in this region. In those tumors demonstrating retention of heterozygosity at markers flanking CDKN2A and LOH on one or both sides of the gene, multiplex microsatellite PCR was performed to rule out homozygous deletion of the region encompassing CDKN2A. CDKN2A mutations were found in tumors from 5 patients [5 (14%) of 35], 4 of which demonstrated LOH across the entire region examined. The remaining tumor with no observed LOH carried two point mutations, one on each allele, Although LOH was identified at one or more markers in 22 (59%) of 37 melanoma tumors corresponding to 20 (57%) of 35 individuals, only 11 tumors from 9 individuals [9 (26%) of 35] demonstrated LOH at D9S942 and D9S1748, the markers closest to CDKN2A. Of the remaining 11 tumors with LOH, 9 demonstrated LOH at two or more contiguous markers either centromeric and/or telomeric to CDKN2A while retaining heterozygosity at several markers adjacent to CDKN2A. Multiplex PCR revealed one tumor carried a homozygous deletion extending from D9S1748 to the IFN-alpha locus. In the remaining eight tumors, multiplex PCR demonstrated that the observed heterozygosity was not attributable to homozygous deletion and stromal contamination at D9S1748, D9S942, or D9S974, as measured by comparative amplification strengths, which indicates that retention of heterozygosity with flanking LOH does not always indicate a homozygous deletion, This report supports the conclusions of previous studies that at least two TSGs involved in melanoma development in addition to CDKN2A may reside on chromosome 9p.

A single nucleotide polymorphism in the 5' untranslated region of RAD51 and risk of cancer among BRCA1/2 mutation carriers

RAD51 colocalizes with both BRCA1 and BRCA2, and genetic variants in RAD51 would be candidate BRCA1/2 modifiers. We searched for RAD51 polymorphisms by sequencing 20 individuals. We compared the polymorphism allele frequencies between female BRCA1/2 mutation carriers with and without breast or ovarian cancer and between population-based ovarian cancer cases with BRCA1/2 mutations to cases and controls without mutations. We discovered two single nucleotide polymorphisms (SNPs) at positions 135 g-->c and 172 g-->t of the 5' untranslated region. In an initial group of BRCA1/2 mutation carriers, 14 (21%) of 67 breast cancer cases carried a c allele at RAD51:135 g-->c, whereas 8 (7%) of 119 women without breast cancer carried this allele. In a second set of 466 mutation carriers from three centers, the association of RAD51:135 g-->c with breast cancer risk was not confirmed. Analyses restricted to the 216 BRCA2 mutation carriers, however, showed a statistically significant association of the 135 c allele with the risk of breast cancer (adjusted odds ratio, 3.2; 95% confidence limit, 1.4-40). BRCA1/2 mutation carriers with ovarian cancer were only about one half as likely to carry the RAD51:135 g-->c SNP. Analysis of the RAD51:135 g-->c SNP in 738 subjects from an Israeli ovarian cancer case-control study was consistent with a lower risk of ovarian cancer among BRCA1/2 mutation carriers with the c allele. We have identified a RAD51 5' untranslated region SNP that may be associated with an increased risk of breast cancer and a lower risk of ovarian cancer among BRCA2 mutation carriers. The biochemical basis of this risk modifier is currently unknown.

Early diagnosis of lymphedema using multiple frequency bioimpedance

Multiple frequency bioelectrical impedance analysis (MFBIA) has previously been shown to provide accurate relative measures of lymphedema in the upper limb of patients (1). This paper reports the results of a three year prospective study to evaluate the efficacy of MFBIA to predict the early onset of lymphedema in patients following treatment for breast cancer. Bioelectrical impedance measurements and circumferential measurements of each upper limb were recorded in healthy control subjects (n=60) to determine the normal range of the ratio (dominant/non-dominant) of extracellular and total limb volumes respectively. Patients undergoing surgery for the treatment of breast cancer were recruited as the study group; MFBIA and circumferential measurements were recorded pre-surgery, one month post-surgery and then at two month intervals for 24 months. One hundred and two patients were recruited into the study. Twenty patients developed lymphedema in the 24 months follow up period of this study. In each of these 20 cases MFBIA predicted the onset of the condition up to 10 months before the condition could be clinically diagnosed. Estimates of the sensitivity and specificity were both approximately 100%. At the time of detection by MFBIA, only one of the patients returned a positive test result from the total limb volumes determined from the circumferential measures. These results confirmed the suitability of the MFBIA technique as a reliable diagnostic procedure for the early detection of lymphedema.

Developments in the understanding of South African style SAG mills

The South African style SAG (RoM) mills operate in a window that is almost exclusive from the operation of the Australian and North American mills that have been used for the development of SAG mill models. Combining good quality, test data from the RoM mills is extending and improving these models, and assisting in a practical manner in improving our understanding of SAG/AG milling. Data from high mill loads, both in absolute filling and ball loading, have been used to extend and improve the JK SAG mill model. This improved understanding has been successfully applied to increasing the throughput of a mill by 8%. Data is presented on relationships between power and load for high mill loading. Slurry pooling is common in closed-circuit RoM mills, and the detrimental effect of this has been dramatically demonstrated at ALCOA with a mill throughput increase of over 20%. Techniques for calculating the effects of slurry pooling have been developed and a new pulp lifter system designed to give optimal slurry discharge. The influence of mill speed in shifting the product size distribution has also been measured. (C) 2001 Elsevier Science Ltd. All rights reserved.

Dendritic branching patterns of pyramidal cells in the visual cortex of the new world marmoset monkey, with comparative notes on the old world macaque monkey

The basal dendritic arbors of 442 supragranular pyramidal cells in visual cortex of the marmoset monkey were compared by fractal analyses. As detailed in a previous study,(1) individual cells were injected with Lucifer Yellow and processed for a DAB reaction product. The basal dendritic arbors were drawn, in the tangential plane, and the fractal dimension (D) determined by the dilation method. The fractal dimensions were compared between cells in ten cortical areas containing cells involved in visual processing, including the primary visual area (Vi), the second visual area (V2), the dorsoanterior area (DA), the dorsomedial area (DM), the dorsolateral. area (DL), the middle temporal area (MT), the posterior parietal area (PP), the fundus of the superior temporal area (FST) and the caudal and rostral subdivisions of inferotemporal cortex (ITc and ITr, respectively). Of 45 pairwise interareal comparisons of the fractal dimension of neurones, 20 were significantly different. Moreover, comparison of data according to previously published visual processing pathways revealed a trend for cells with greater fractal dimensions in higher cortical areas. Comparison of the present results with those in homologous cortical areas in the macaque monkey(2) revealed some similarities between the two species. The similarity in the trends of D values of cells in both species may reflect developmental features which, result in different functional attributes.

A parent-completed developmental questionnaire: Follow up of ex-premature infants

Objective: premature infants are at increased risk of developmental disability. Early identification of problems allows intervention to ameliorate or attenuate problems. A reliable screening tool allows triage of children in this high-risk population by identifying those unlikely to need full developmental assessment. To explore the test characteristics of an established parent-completed developmental assessment questionnaire 'Ages and Stages Questionnaire' (ASQ) in follow up of an Australian population of premature infants. Methodology: One hundred and sixty-seven children born prematurely with corrected ages 12- to 48-months attending the Growth and Development Clinic at the Mater Children's Hospital in Brisbane, Queensland, Australia; 136 questionnaires 'ASQ' were returned completed (81%) and were compared to formal psychometric assessment (Griffith Mental Development Scales for 12- and 24-months, Bayley Mental Development Intelligence Scale for 18-months, McCarthy General Cognitive Intelligence Scale for 18-months). Developmental delay was considered to be present if any of the above psychometric assessments fell below 1.0 standard deviations (SD). The ASQ cut-off used was 2.0 SD (US data derived means and SD). Results: Aggregate results for all age groups comparing ASQ to psychometric assessments as 'gold standards' found the ASQ to have the following test characteristics: sensitivity (90%); specificity (77%); positive predictive value (40%); negative predictive value (98%): % over-referred (20%); % under-referred (1%); % agreement (79%). likelihood ratio for children failing the ASQ was 3.8 and for passing the ASQ was 0.13. Twenty-one children with known disabilities were included in the study and in 14 of these, the ASQ overall score agreed with the psychometric assessment (67%). Conclusion: The high negative predictive value of the ASQ supports its use as a screening tool for cognitive and motor delays in the follow up of ex-premature infants. This would need to be combined with other strategies as part of a comprehensive follow up program for ex-premature infants.