Precise U-Pb age constrains on the Ediacaran biota in Podolia, East European Platform, Ukraine.

The Neoproterozoic Era was characterized by rapidly changing paleogeography, global climate changes and especially by the rise and fall of the Ediacaran macro-biota. The correlation between disparate Ediacaran fossil-bearing localities and the tentative reconstruction of their paleoenvironmental and paleogeographic contexts are usually complicated by the lack of precise and accurate age data. For this reason, Neoproterozoic sedimentary sections associating Ediacaran biota fossils and fresh volcanic material are especially valuable for radioisotopic dating. Our research in the Podolya Basin, southwestern Ukraine, revealed the presence of four Neoproterozoic volcanic ash deposits (potassium-bentonite layers) within Ediacaran fossil-bearing siliciclastic rocks of the Mohyliv-Podilskyi Group. We used zircon U-Pb LA-ICPMS and CA-ID-TIMS methods to date two of those layers. The results indicate that a diverse assemblage of body and trace Ediacaran fossils occurred as early as 556.78 ± 0.18 million years (Ma) ago. By combining morphological evidence and new age determinations, we suggest a closer paleobiogeographical relationship between the Ukrainian Ediacaran assemblage and the Avalon paleocontinent than previously estimated.

Foetal pulmonary maturity in dogs: Estimated from bubble tests in amniotic fluid obtained via amniocentesis.

The goal of this study was to evaluate the reliability of amniocentesis during late pregnancy to assess lung maturity in puppies using a bubble test as described by Gunston and Davey (South African Medical Journal, 54, 1978, 495). Thirty-five bitches from eight different breeds were followed during late pregnancy before undergoing elective Caesarean (C)-section on days 61-62 after ovulation. Bubble tests were performed the day before the C-section (n = 11 bitches) and before the administration of aglepristone on amniotic fluid samples obtained via amniocentesis and were repeated the day of the surgery on amniotic fluid samples collected via puncture of the amniotic bags before they were opened (n = 35 bitches). No complications were observed following amniocenteses and the C-sections. The mortality rate (2.3%) was similar to the result of other studies using the same protocol for an elective C-section. Of the non-contaminated samples collected the day of the C-section, 89.6% were positive in the bubble test, which was consistent with observations of clinical maturity the day of the surgery and on the following days. In contrast, 70% of the samples collected the day before the C-section (when progesterone concentrations were still high) were negative, suggesting that the puppies were still immature at this point in the pregnancy. Additionally, we observed a significant difference in the bubble test results before and 18 hr after the administration of aglepristone, suggesting that aglepristone may act as an inducer of the final maturation of the puppies by inactivating progesterone receptors and simulating a physiological decrease in progesterone. Finally, we confirmed the need to exclude all contaminated samples, which could lead to false-negative results.

High mobility group box 1 promotes tumor cell migration through epigenetic silencing of semaphorin 3A.

High mobility group box 1 (HMGB1) is a 25-kDa chromatin-associated protein that aids in transcription and DNA repair by directly binding to DNA and altering its conformation. Additionally, HMGB1 can act as an extracellular ligand. When released from dying or stressed cells, HMGB1 binds to the RAGE receptor and activates the p42/44 MAP kinase (MAPK) cascade. HMGB1 is overexpressed in many types of cancer and frequently associated with tumor stage and metastasis. This has predominantly been attributed to an autocrine function that drives MAPK pathway activity. However, by using tumor cells with activating MAPK pathway mutations, we have identified a role for HMGB1 in promoting metastasis and tumor growth that is independent of this pathway. In the absence of HMGB1, these tumor cells show defective in vitro migration as well as reduced metastasis and tumor growth in vivo despite high p42/44 phosphorylation. We found that semaphorin 3A (SEMA3A), previously shown to act as a suppressor of angiogenesis and migration, was highly increased during expression in the absence of HMGB1. SEMA3A/HMGB1 double knockdown rescued the migration defect in HMGB1 single knockdown cells. HMGB1 bound at the semaphorin 3A genomic locus, promoted hetrochromatin formation, and decreased occupancy of acetylated histones. Based on human tumor gene expression databases, HMGB1 was significantly inversely correlated with SEMA3A, suggesting that this mechanism may be more widely relevant in different cancer types.

46, XY gonadal dysgenesis: new SRY point mutation in two siblings with paternal germ line mosaicism.

Familial recurrence risks are poorly understood in cases of de novo mutations. In the event of parental germ line mosaicism, recurrence risks can be higher than generally appreciated, with implications for genetic counseling and clinical practice. In the course of treating a female with pubertal delay and hypergonadotropic hypogonadism, we identified a new missense mutation in the SRY gene, leading to somatic feminization of this karyotypically normal XY individual. We tested a younger sister despite a normal onset of puberty, who also possessed an XY karyotype and the same SRY mutation. Imaging studies in the sister revealed an ovarian tumor, which was removed. DNA from the father's blood possessed the wild type SRY sequence, and paternity testing was consistent with the given family structure. A brother was 46, XY with a wild type SRY sequence strongly suggesting paternal Y-chromosome germline mosaicism for the mutation. In disorders of sexual development (DSDs), early diagnosis is critical for optimal psychological development of the affected patients. In this case, preventive karyotypic screening allowed early diagnosis of a gonadal tumor in the sibling prior to the age of normal puberty. Our results suggest that cytological or molecular diagnosis should be applied for siblings of an affected DSD individual.

Risk of autoimmune diabetes in APECED: association with short alleles of the 5'insulin VNTR.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autoimmune disease causing a wide spectrum of autoimmune dysfunction potentially including diabetes of an autoimmune etiology. We have previously described a pair of discordant APECED siblings and pointed to a possible role of 5'insulin variable number of tandem repeats (VNTR) locus IDDM2 in the appearance of diabetes within this disease. In vitro studies have previously suggested that class I VNTR alleles were associated with decreased fetal thymic insulin expression. We genotyped the 5'INS VNTR locus and several flanking 11p15.5 markers in 50 Finnish APECED subjects and explored the possible contribution of IDDM2 in the development of diabetes. The shorter 5'INS VNTR class I alleles (<35 repeats) were more prevalent in the diabetic Finnish APECED subjects than in non-diabetic APECED subjects. Logistic regression analysis revealed that having 1 short (<35) VNTR allele did not increase the risk of developing diabetes (95% CI 0.6-27.0), whereas having 2 short alleles conferred a 43.5-fold increased risk (95% CI 3.0-634.6). We conclude that short 5'INS VNTR class I alleles play a role in susceptibility to autoimmune diabetes in the context of APECED.

Molecular studies of a patient with complete androgen insensitivity and a 47,XXY karyotype.

A phenotypic female with complete androgen insensitivity from a maternally inherited mutation in the androgen receptor had a 47,XXY karyotype. Partial maternal X isodisomy explained the expression of androgen insensitivity despite the presence of 2 X chromosomes.

Genetic and epigenetic variability in the gene for IGFBP-3 (IGFBP3): correlation with serum IGFBP-3 levels and growth in short children born small for gestational age.

CONTEXT: IGF-I and IGFBP-3 play a central role in fetal and postnatal growth and levels are low in short SGA children. The -202 A/C and -185 C/T SNPs are located near elements involved in directing IGFBP3 promoter activity and expression. Changes in promoter CpG methylation status affect transcription factor binding and transcriptional activation of IGFBP3 in vitro. OBJECTIVE: To assess the relationship between IGFBP3 promoter SNPs, IGFBP-3 levels, spontaneous growth and growth response to GH treatment in short prepubertal SGA children. To assess promoter methylation status in a subgroup of short SGA subjects and controls. PATIENTS: 292 Short prepubertal SGA children, 39 short young SGA adults and 85 young adults with normal stature. INTERVENTION: Short prepubertal SGA children received GH 1mg/m(2)/day. OUTCOME MEASURES: Fasting levels of IGF-I and IGFBP-3, baseline and delta height SDS. RESULTS: At baseline, IGFBP-3 levels were highest in SGA children with -202 AA genotype and lower in children with 1 or 2 copies of the C-allele (P<0.001). Children with C(-202)/C(-185) haplotype, compared to children with A(-202)/C(-185) haplotype, had lower IGFBP-3 levels (P=0.003) and were shorter (P=0.03). During GH treatment, children with C(-202)/C(-185) haplotype showed a significantly greater increase in IGFBP-3 SDS and in height SDS than children with A(-202)/C(-185) haplotype, resulting in similar IGFBP-3 levels and similar height SDS after 12 months of GH treatment. CpG methylation patterns showed a trend towards more methylation of CpGs involved in transcription factor binding in short young SGA adults compared to controls. CONCLUSION: Polymorphic variation in the IGFBP3 promoter region is correlated with IGFBP-3 levels, spontaneous growth and response to GH treatment in short SGA children.

Production of tissue-engineered three-dimensional human bronchial models.

We have reported morphological and functional features of cells isolated from human bronchial biopsies. Both epithelial and fibroblastic cells were isolated from the same biopsies using collagenase. A few models have been established to study normal bronchial response to various agents and to understand the mechanisms responsible for some disorders, such as asthma. We produced three-dimensional bronchial equivalents in culture, using human epithelial and fibroblastic cells. We previously showed that peripheral anchorage can prevent the dramatic collagen contraction in gels seeded with fibroblasts when properly adapted to the size and type of cultured tissues. Our bilayered bronchial constructs were anchored and cultured under submerged conditions and at the air-liquid interface. Three culture media were compared. Serum-free medium supplemented with retinoic acid (5 x 10(-8) M) was found to be the best for maintenance of bronchial cell properties in the reconstructed bronchial tissue. Immunohistological and ultrastructural analyses showed that these equivalents present good structural organization, allowing ciliogenesis to occur in culture. Moreover, human bronchial goblet cells could differentiate and secrete mucus with culture time. Laminin, a major constituent of the basement membrane and basal cells, was also detected at the mesenchymoepithelial interface. Such models will be useful for studying human bronchial properties in vitro.

Influence of Bacillus subtilis cell walls and EDTA on calcite dissolution rates and crystal surface features.

This study investigates the influence of EDTA and the Gram-positive cell walls of Bacillus subtilis on the dissolution rates and development of morphological features on the calcite [1014] surface. The calcite dissolution rates are compared at equivalent saturation indicies (SI) and relative to its dissolution behavior in distilled water (DW). Results indicate that the presence of metabolically inactive B. subtilis does not affect the dissolution rates significantly. Apparent increases in dissolution rates in the presence of the dead bacterial cells can be accounted for by a decrease of the saturation state of the solution with respect to calcite resulting from bonding of dissolved Ca2+ by functional groups on the cell walls. In contrast, the addition of EDTA to the experimental solutions results in a distinct increase in dissolution rates relative to those measured in DW and the bacterial cell suspensions. These results are partly explained by the 6.5-8 orders of magnitude greater stability of the Ca-EDTA complex relative to the Ca-B. subtilis complexes as well as its free diffusion to and direct attack of the calcite surface. Atomic force microscopy images of the [1014] surface of calcite crystals exposed to our experimental solutions reveal the development of dissolution pits with different morphologies according to the nature and concentration of the ligand. Highly anisotropic dissolution pits develop in the early stages of the dissolution reaction at low B. subtilis concentrations (0.004 mM functional group sites) and in DW. In contrast, at high functional group concentrations (4.0 mM EDTA or equivalent B. subtilis functional group sites), dissolution pits are more isotropic. These results suggest that the mechanism of calcite dissolution is modified by the presence of high concentrations of organic ligands. Since all the pits that developed on the calcite surfaces display some degree of anisotropy and dissolution rates are strongly SI dependent, the rate-limiting step is most likely a surface reaction for all systems investigated in this study. Results of this study emphasize the importance of solution chemistry and speciation in determining calcite reaction rates and give a more accurate and thermodynamically sound representation of dead bacterial cell wall-mineral interactions. In studies of natural aquatic systems, the presence of organic ligands is most often ignored in speciation calculations. This study clearly demonstrates that this oversight may lead to an overestimation of the saturation state of the solutions with respect to calcite and thermodynamic inconsistencies.

Glycosaminoglycan mimetics: a therapeutic approach to cerebral amyloid angiopathy.

Amyloid deposits characteristic of cerebral amyloid angiopathy lead to vessel rupture and intracerebral hemorrhage. Proteoglycans associate with the amyloid fibril deposits and are thought to play a role in the polymerization of amyloid proteins and the propagation of the deposition process. A series of low molecular weight anionic compounds was developed to mimic the glycosaminoglycan moieties of these proteoglycans. These compounds were tested in different in vitro systems to determine their anti-Abeta amyloid activity. Specific compounds were identified as being anti-fibrillogenic and protective against Abeta-induced cvtotoxicity. Such compounds also did not show intrinsic cellular toxicity could cross the blood-brain barrier (BBB) in vivo, and showed a good safety profile following chronic' exposure. Molecules showing an anti-amyloid profile combined with the ability to cross the BBB represent promising therapeutics for CAA.

Novel promoter polymorphism in insulin-like growth factor-binding protein-3: correlation with serum levels and interaction with known regulators.

Insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) is a major determinant of circulating levels of the IGFs and is clinically useful for the evaluation of GH deficiency and for predicting the response to GH treatment. Recent studies provide evidence that the circulating level of IGFBP-3 is inversely related to the risk of several common cancers, and that antiproliferative agents such as antiestrogens and retinoids act in part by up-regulating IGFBP-3 gene (IGFBP3) expression. Although approximately 50% of the substantial interindividual variability in circulating IGFBP-3 levels is known to have a genetic basis, the specific loci involved are unknown. Direct sequencing of genomic DNA specimens from a multiethnic population identified several single nucleotide polymorphisms in the promoter region of IGFBP3. For the most common single nucleotide polymorphism (nucleotide -202) found to be in Hardy-Weinberg equilibrium, genotype was highly correlated to circulating level of IGFBP-3 in 478 men from the Physicians' Health Study. In vitro, we documented significantly higher promoter activity of the A allele at the -202 locus compared with the C allele, consistent with the relationship observed between genotype and circulating IGFBP-3 (AA > AC > CC). A positive correlation was observed between circulating retinol levels and circulating IGFBP-3 levels; subset analysis by genotype showed that this relationship was only present among individuals carrying an A allele at -202 (AA > AC > CC). Tall individuals or individuals with a body mass index of 27 or greater had levels of circulating IGFBP-3 that were significantly higher when they possessed at least one A allele (AA > AC > CC). The IGFBP3 promoter region deserves investigation as a locus where polymorphic variation occurs frequently and may influence GH responsiveness, somatic growth, and possibly cancer risk.

Early-onset amyloid deposition and cognitive deficits in transgenic mice expressing a double mutant form of amyloid precursor protein 695.

We have created early-onset transgenic (Tg) models by exploiting the synergistic effects of familial Alzheimer's disease mutations on amyloid beta-peptide (Abeta) biogenesis. TgCRND8 mice encode a double mutant form of amyloid precursor protein 695 (KM670/671NL+V717F) under the control of the PrP gene promoter. Thioflavine S-positive Abeta amyloid deposits are present at 3 months, with dense-cored plaques and neuritic pathology evident from 5 months of age. TgCRND8 mice exhibit 3,200-4,600 pmol of Abeta42 per g brain at age 6 months, with an excess of Abeta42 over Abeta40. High level production of the pathogenic Abeta42 form of Abeta peptide was associated with an early impairment in TgCRND8 mice in acquisition and learning reversal in the reference memory version of the Morris water maze, present by 3 months of age. Notably, learning impairment in young mice was offset by immunization against Abeta42 (Janus, C., Pearson, J., McLaurin, J., Mathews, P. M., Jiang, Y., Schmidt, S. D., Chishti, M. A., Horne, P., Heslin, D., French, J., Mount, H. T. J., Nixon, R. A., Mercken, M., Bergeron, C., Fraser, P. E., St. George-Hyslop, P., and Westaway, D. (2000) Nature 408, 979-982). Amyloid deposition in TgCRND8 mice was enhanced by the expression of presenilin 1 transgenes including familial Alzheimer's disease mutations; for mice also expressing a M146L+L286V presenilin 1 transgene, amyloid deposits were apparent by 1 month of age. The Tg mice described here suggest a potential to investigate aspects of Alzheimer's disease pathogenesis, prophylaxis, and therapy within short time frames.

Molecular characterization of a pediatric pheochromocytoma with suspected bilateral disease.

An 11-year-old boy with hypertension was suspected of having bilateral adrenal pheochromocytomas and hyperplasia. Molecular analysis of specific tumor suppressor genes and oncogenes excluded the familial syndromes, von Hippel-Lindau (VHL) disease and multiple endocrine neoplasia (MEN) type 2A. Further evaluation identified a unilateral adrenal pheochromocytoma with a VHL heterozygous somatic mutation (G695A) and loss of the maternal allele at 11p15.5-11p14 exclusively in the tumor tissue. Both reverse-transcriptase polymerase chain reaction and immunohistochemistry confirmed increased expression of IGF2 within the tumoral tissue, relative to a normal control adrenal gland. These results ruled out familial syndromes and suggested that the VHL mutation and the loss of maternal allele on chromosome 11 could have contributed to tumor development.

Acute treatment with tamoxifen reduces ischemic damage following middle cerebral artery occlusion.

Inhibitors of cell-swelling-activated anion channels, including the antiestrogenic compound tamoxifen (TAM), have been shown to attenuate the increase in excitatory amino acids (EAA) during ischemia. Since TAM enters the CNS we tested whether it provides protection from damage due to reversible middle cerebral artery occlusion (rMCAo) in rats. TAM (5 mg/kg, i.v.) infused 25 min before ischemia, potently reduced the total volume of the infarct from 328 +/- 34 mm3 to 41 +/- 21 mm3, a reduction of 87%, as measured by TTC staining. It was equally effective when infused starting at 1 h after reperfusion, i.e. 3 h after initiation of rMCAo. Protection of neurons was also found histologically. TAM had no effect on CBF as measured by hydrogen clearance. This appears to be the first report of a marked neuroprotective effect of TAM. Further studies are needed to determine whether its effects are due to inhibition of EAA release and/or other potential neuroprotective sites of action.

H19 sense and antisense transgenes modify insulin-like growth factor-II mRNA levels.

The oppositely-imprinted genes insulin-like growth factor-II (IGF2) and H19, a putative tumor suppressor, often show coordinate, reciprocal regulation and are believed to play a role in carcinogenesis. To explore the possible interactions between these genes, we stably transfected diHepG2 cells with a plasmid containing either the sense or the antisense H19 cDNA sequences and verified their expression by Northern analysis and by RNase protection analysis. Levels of H19, IGF2 and gamma-actin mRNA were quantified by competitive RT-PCR analysis. Although H19 sense transgene overexpression (n = 24 clones) did not decrease the low, basal levels of IGF2 mRNA compared to control cells, levels of IGF2 mRNA were positively correlated with the levels of H19 antisense mRNA (P < 0.0001, n = 40 clones). Furthermore, the increase in IGF2 mRNA level was accompanied by an elevation of IGF-II peptide in conditioned media. To see if H19 mRNA had a specific effect on transcription, we also performed transient transfections with reporter gene constructs containing IGF2 promoter 3 in the presence of sense or antisense H19 cDNA sequences under control of a cytomegalovirus promoter. We show a lower reporter gene activity from reporter gene constructs in the presence of sense H19 cDNA than from those with antisense or neomycin. Our results suggest that H19 participates in the repression of IGF2, at least in part through effects on IGF2 transcription, an effect which may contribute to its action as a tumor suppressor.

Pediatric adrenocortical tumors: molecular events leading to insulin-like growth factor II gene overexpression.

It has been previously shown that adrenocortical tumors (ACT) in adults exhibit structural abnormalities in tumor DNA in approximately 30% of cases. These abnormalities involve chromosome 11p15 and include loss of heterozygosity, paternal isodisomy, and overexpression of the gene for insulin-like growth factor II (IGF2), correlating with DNA demethylation at this locus. It has been hypothesized that these events occur late in the tumorigenic process in adults and seem to correlate with a worse prognosis. We present 4 pediatric cases of ACT diagnosed at 2.5 yr, 10 months, 12 yr, and 2.2 yr. All 4 patients presented with virilization, and 1 patient also showed signs and symptoms of glucocorticoid excess. The youngest patient's maternal aunt had surgical excision of a more than 15-cm ACT 18 yr previously, but the aunt is doing well at age 23 yr. They all had surgical removal of their tumors. The 2.5-yr-old child also received chemotherapy and radiotherapy because of capsular rupture and, after 3 local recurrences, died 3.3 yr after initial presentation. We investigated all 4 tumors for chromosome 11 structural abnormalities (11p15.5 to 11q23), IGF2 and H19 expression by competitive RT-PCR analysis, and IGF2 methylation patterns by Southern analysis. All 4 tumors (100%) showed a combination of structural abnormalities at the 11p15 locus with mosaic loss of heterozygosity involving 11p. All tumors also had significantly increased IGF2 messenger ribonucleic acid levels relative to normal adrenal (up to 36-fold) and significant IGF2 demethylation (mean, 87%). H19 messenger ribonucleic acid levels were undetectable in 3 of 4 tumors, explained in part by mosaic loss of the actively expressed maternal allele for this imprinted gene. By immunohistochemistry we were able to confirm increased IGF-II peptide levels within the tumor tissue in 10 pediatric patients, including the 4 patients described above. Concomitantly, we also observed nuclear accumulation of p53, suggesting somatic mutations. For the 10-month-old patient, sequencing revealed a p53 germline mutation. We therefore conclude that in pediatric ACT, structural abnormalities of tumor DNA and IGF2 overexpression as well as p53 mutations are very common and are therefore less useful for prognosis than in adults. Our findings support the theory that pediatric ACT, whose IGF2 expression and steroidogenesis evoke the phenotype of the fetal adrenal cortex, may arise because of defective apoptosis.

Dimensional accuracy of an epoxy resin die material using two setting methods.

STATEMENT OF PROBLEM: Resinous die materials have several important advantages including strength, abrasion resistance, and detail reproduction. Despite these advantages, the shrinkage of resinous die materials during polymerization has limited their widespread acceptance. PURPOSE: This study determined whether a retarded setting reaction could improve the accuracy of an epoxy resin die system, and compared the accuracy of this epoxy resin system with gypsum-based die materials. MATERIAL AND METHODS: Four groups were compared: an epoxy resin manipulated according to manufacturer's instructions (Ivoclar, Schaan, Liechtenstein); the same epoxy resin manipulated to undergo a retarded set; a high-strength high-expansion gypsum (Die Keen); and a resin-filled gypsum (Resin Rock). Ten dies were fabricated for each material from a master metal model using conventional prosthodontic laboratory techniques. The mean of 3 independent measurements recorded using a toolmaker's microscope and digital positioners was used to describe each die. RESULTS: One-way ANOVA revealed that significant differences existed among the materials (P <.0001). Tukey's multiple comparisons testing ranked the dies as follows, from largest to smallest: high-strength high-expansion gypsum, resin-filled gypsum, master metal model, retarded epoxy, and manufacturers epoxy (P <.05). CONCLUSION: Retarding the setting reaction of an epoxy resin die material improved its accuracy. Of the materials tested, retarded set epoxy dies had the least mean dimensional change from the metal master. Epoxy resin die materials had a net shrinkage, but the gypsum-based materials had a net expansion. The epoxy resin materials exhibited more variability than the gypsum-based materials.