The opdB locus encodes the trypsin-like peptidase activity of Treponema denticola

High levels of Treponema denticola in subgingival dental plaque are associated with severe periodontal disease. T. denticola, along with Porphyromonas gingivalis and Bacteroides forsythus, are the only cultivatable oral microorganisms that produce significant amounts of "trypsin-like" peptidase activity. The ability of subgingival plaque to hydrolyze N-alpha-benzoyl-DL-arginine-2-naphthylamide (BANA) is associated with high levels of one or more of these organisms. The purpose of this study was to identify the gene encoding trypsin-like activity in T. denticola and thus facilitate molecular-level studies of its potential role in disease. Using published peptide sequences of a T. denticola surface-associated oligopeptidase with BANA-hydrolyzing activity, we identified the gene, designated opdB, in an apparently noncoding region of the T. denticola genome unannotated contigs (11/2000; http://www.tigr.org). The opdB gene begins with a TTG start codon and encodes a 685-residue peptide with high homology to the oligopeptidase B family in prokaryotes and eukaryotes. An isogenic T. denticola opdB mutant was constructed by allelic replacement mutagenesis using an ermF/AM gene cassette. The mutant lacked BANA-hydrolyzing activity and had a slightly slower growth rate than the parent strain. This mutant will be used in future studies of interactions of T. denticola with host cells and tissue.

Association of plasma cortisol and chronic lung disease in preterm infants

BACKGROUND

It has been suggested that preterm infants may have developmental immaturity of the hypothalamic-pituitary-adrenal axis, and that decreased cortisol response to stress increases risk of chronic lung disease (CLD) secondary to inflammatory lung injury.

METHODS

To investigate the relationship between endogenous corticosteroid and CLD, we measured plasma cortisol during the first 28 days of life in a subset of neonates in the North American Thyrotropin-Releasing Hormone (TRH) Collaborative Trial. Analyses were performed on 314 infants, 24 to 32 weeks' gestation, whose mothers received 1 or 2 courses of antenatal corticosteroids plus TRH or placebo.

RESULTS

Mean cortisol was 3.1 microg/dL (range: 0.1-17.9) at birth, reached maximal levels at 24 hours (19.4 microg/dL, range: 0.8-124.6), and decreased to 5.9 microg/dL (range: 0.2-24.7) at 14 to 28 days of age; levels during the first week were not associated with gestational age. The Clinical Risk Index for Babies (CRIB), a neonatal assessment tool that is correlated with risk of mortality, was positively associated with cortisol level on days 1 and 3 through 7. TRH versus placebo treatment did not influence cortisol levels at any time point. To examine the relationship between cortisol and adverse outcome of death or CLD at 36 weeks' postmenstrual age (CLD36), logistic regression models adjusting for known contributing clinical factors (gestational age and CRIB score) were fit. There was a statistically borderline negative association between median cortisol level at 3 to 7 days and CLD36. After adjusting for gestational age and CRIB score, the predicted probability of CLD36 was only minimally influenced by the cortisol concentration.

CONCLUSION

In preterm infants, basal plasma cortisol concentration during the first week is a weak predictor for CLD36. Possible benefits as well as risks of supplemental, low-dose cortisol treatment of high-risk preterm infants remain to be determined.

Flat panel detector-based cone-beam volume CT angiography imaging: system evaluation

Preliminary evaluation of recently developed large-area flat panel detectors (FPDs) indicates that FPDs have some potential advantages: compactness, absence of geometric distortion and veiling glare with the benefits of high resolution, high detective quantum efficiency (DQE), high frame rate and high dynamic range, small image lag (< 1%), and excellent linearity (approximately 1%). The advantages of the new FPD make it a promising candidate for cone-beam volume computed tomography (CT) angiography (CBVCTA) imaging. The purpose of this study is to characterize a prototype FPD-based imaging system for CBVCTA applications. A prototype FPD-based CBVCTA imaging system has been designed and constructed around a modified GE 8800 CT scanner. This system is evaluated for a CBVCTA imaging task in the head and neck using four phantoms and a frozen rat. The system is first characterized in terms of linearity and dynamic range of the detector. Then, the optimal selection of kVps for CBVCTA is determined and the effect of image lag and scatter on the image quality of the CBVCTA system is evaluated. Next, low-contrast resolution and high-contrast spatial resolution are measured. Finally, the example reconstruction images of a frozen rat are presented. The results indicate that the FPD-based CBVCT can achieve 2.75-lp/mm spatial resolution at 0% modulation transfer function (MTF) and provide more than enough low-contrast resolution for intravenous CBVCTA imaging in the head and neck with clinically acceptable entrance exposure level. The results also suggest that to use an FPD for large cone-angle applications, such as body angiography, further investigations are required.

Insoluble components of concentrated air particles mediate alveolar macrophage responses in vitro

We sought to characterize the bioactive constituents of concentrated ambient air particles (CAPs) through correlation of alveolar macrophage (AM) biological responses (production of TNF, macrophage inflammatory protein (MIP-2), nitrite; cell viability) to components of particle samples. CAPs samples collected on different days showed a range of bioactivity and a strong correlation was found between AM cytokine release and increased AM light scatter, a flow cytometric measure of relative particle load. Evaluation of soluble and insoluble fractions of CAPs suspensions indicate that 1) most biological effects on AMs are mediated by insoluble components and certain particle adsorbed factors such as endotoxin; 2) the variable bioactivity of CAPs collected on different days arises primarily from differences in the relative proportion of insoluble and soluble mass present in particle suspensions; and 3) the activation state of the AM influences which insoluble components are most bioactive. Use of endotoxin neutralizing agents (e.g., polymyxin-B) showed particle-adsorbed endotoxin in CAPs suspensions causes activation of normal (control) AMs while other (nonendotoxin) components are predominantly responsible for the enhanced cytokine release observed by primed AMs incubated with CAPs. The AM biological response did not correlate with any of a panel of elements quantified within insoluble CAPs samples (Al, Cd, Cr, Cu, Fe, Mg, Mn, Ni, S, Ti, V). These data demonstrate an important role for cell activation and phagocytosis of insoluble particulate matter in the response of AMs to CAPs suspensions.

Suppression of X-ray-induced chromatid breaks in human tumor cells by introduction of normal chromosome 4

Human tumor cells in culture frequently show an infinite lifespan and are characterized by an abnormally high frequency of chromatid breaks after x-irradiation during G(2) phase of the cell cycle. This abnormally high frequency of persistent chromatid breaks results from deficient repair of the radiation-induced DNA damage. In three of four tumor cell lines, addition of a single human chromosome 4 from normal cells by microcell fusion resulted in efficient repair as evidenced by suppression of radiation-induced chromatid breaks to the level in normal cells. With respect to senescence-related gene (s), two of these four tumor cell lines belonged to complementation group A and one each to groups C and D. Chromosome 4 restored DNA repair efficiency in only one of the two tumor cell lines of complementation group A. These results suggest that chromosome 4 carries a DNA repair gene or gene(s) that complement the repair deficiency in three of these four tumor lines. Furthermore, the gene(s) involved in cellular senescence on chromosome 4 appear to differ from the gene(s) for repair of radiation-induced DNA damage during G(2).

An epidemiological analysis of leprosy from 1951-1996 in Sichuan

Through the leprosy surveillance system established in 1990s the authors analysed the epidemiology of leprosy in Sichuan province from 1951 to 1996. By the end of 1996, the total number of registered cases was 32,772, the peak incidence rate (2.44/100,000) was in 1958. The annual average progressively decreasing speed (AAPDS) of the number of new cases, incidence rate, incidence rate among children, number of newly detected patients, detection rate, number of registered cases and registered prevalence rates were 4.7% (xg = 0.9534), 5.9% (xg = 0.9407), 7.4% (xg = 0.9263), 6.7% (xg = 0.9326), 8.1% (xg = 0.9195), 10.9% (xg = 0.8913) and 11.7% (xg = 0.8828) respectively. Among newly detected cases, the proportion of children gradually declined with an AAPDS of 2.9% (xg = 0.9712), but that of household contacts gradually increased, showing a gradual decline of source of infection. The multibacillary (MB) rate among new cases, newly registered cases and active cases also increased gradually. The MB rate among child cases was much lower than that among adults. The disability rates among newly registered cases tended to decline. The peak incidence was in the 20 to 35 years age group, the average age at onset being 31.92 years. Average age at onset gradually increased to 34.19 during 1991-1995. The average interval between onset of symptoms and diagnosis was 4.89 years and that had reduced gradually to 3.24 years during 1991-1995. The authors conclude that: (1) the epidemiological trend of leprosy in Sichuan province shows decline; (2) the case-finding activities have improved and intensified; but (3) the disability rate among newly detected cases is still high (> 20%) and the average delay in diagnosis is still too long, showing that early case finding is still not satisfactory.

[Photoluminescent properties of organic film in flat optical microcavity]

The microcavity is sandwiched between a quarterwavelength distributed Bragg reflector(DBR) and a metal Ag reflective mirror. A single layer of a Tris(8-quinolinolato) aluminum (Alq) film was used as the light-emitting layer. The photoluminescent properties of the optical microcavity and that of the Alq film were studied at the same excitation condition. Compared with the Alq film, the significantly narrowed spectral emission linewidth from 90 nm to 10 nm was observed, the PL emission intensity of the microcavity at the resonant mode is enhanced by the order of 1. The spectral narrowing and intensity enhancement of the microcavity is attributed to the microcavity effect.

Alveolar macrophage cytokine production in response to air particles in vitro: role of endotoxin

The interaction of air particles and alveolar macrophages (AMs) may result in the release of proinflammatory cytokines. Normal mouse AMs were treated with concentrated air particle (CAPs) suspensions in vitro. After 5 h, cytokine release [macrophage inflammatory protein-2 (MIP-2) and tumor necrosis factor-alpha (TNF-alpha)] and phagocytosis of ambient air particles were measured. CAPs samples collected from urban air (Boston) on different days were used. The CAPs samples and their soluble and solid components caused significant MIP-2 and TNF-alpha production. Variability in the potency of samples collected on different days was observed. Trace endotoxin was measured in CAPs samples (EU/mg: 2.3 +/- 0.7, mean +/- SE, n = 10). A majority of biologic activity (cytokine induction) and endotoxin content was associated with the solid components. Neutralization of endotoxin by polymyxin B abrogated >80% of TNF-alpha induction by CAPs samples, but inhibited MIP-2 production by only approximately 40%. The trace endotoxin present in CAPs caused much more MIP-2 production than predicted by concentration alone (28 +/- 8-fold increase, n = 9), indicating synergistic interaction with other AM-activating components of the particles. Data suggest that low levels of endotoxin may interact with air particles to activate lung macrophages.

Detection of chromosomal aberrations by a whole-genome microsatellite screen

Chromosomal aberrations are a common cause of multiple anomaly syndromes that include developmental and growth retardation. Current microscopic techniques are useful for the detection of such aberrations but have a limit of resolution that is above the threshold for phenotypic effect. We hypothesized that a genomewide microsatellite screen could detect chromosomal aberrations that were not detected by standard cytogenetic techniques in a portion of these individuals. To test this hypothesis, we performed a genomewide microsatellite screen of patients, by use of a currently available genetic-marker panel that was originally designed for meiotic mapping of Mendelian traits. We genotyped approximately 400 markers on 17 pairs of parents and their children who had normal karyotypes. By using this approach, we detected and confirmed two cases of segmental aneusomy among 11 children with multiple congenital anomalies. These data demonstrate that a genomewide microsatellite scan can be used to detect chromosomal aberrations that are not detected by microscopic techniques.

[Effect of emodin on human kidney fibroblast proliferation]

OBJECTIVE

To study the effect of emodin on proliferation of human kidney fibroblasts in vitro.

METHODS

After human kidney fibroblasts were cultured, isolated and identified, both the effects of five different concentrations of emodin (10, 30, 50, 80 and 100 micrograms/ml) on 3H-TdR incorporation, and the effects of three different concentrations of emodin (10, 50 and 100 micrograms/ml) on cell cycle by flow cytometry were investigated.

RESULTS

The exposure of human kidney fibroblasts to emodin (10-100 micrograms/ml) caused a dose-dependent reduction in 3H-TdR (r = 0.995, P < 0.01), and could delay the progress of human kidney fibroblasts from G1 to S phase.

CONCLUSIONS

Emodin inhibited the proliferation of human kidney's fibroblasts by inhibiting the cell DNA synthase and delaying the progress of cell cycle. These findings might provide part of experimental basis for the clinical use of emodin.

An enhanced microfluidic chip coupled to an electrospray Qstar mass spectrometer for protein identification

The combination of microfabricated fluidic systems (muFAB) and electrospray mass spectrometers (ESI-MS) will provide multiplexed and integrated analytical systems for proteins and other biomolecules. Implementation of this novel approach requires the development of robust and user-friendly muFAB devices. Here, we present new approaches that improve the robustness, user friendliness and performance of muFAB devices coupled to MS. First, we present the development of a convenient mount to connect a muFAB device to the ESI-MS and the incorporation of filters in the reservoirs and exit of the muFAB. This mount facilitates interfacing and significantly reduces the chemical noise observed by the MS. Furthermore, we demonstrate improvements in sample handling and delivery by using either a nonaqueous electrolyte or a cationic coating on the surfaces in the muFAB device and transfer capillary. These improvements are applied to protein analysis by continuous infusion of proteolytic digests.

Autosomal XX sex reversal caused by duplication of SOX9

SOX9 is one of the genes that play critical roles in male sexual differentiation. Mutations of SOX9 leading to haploinsufficiency can cause campomelic dysplasia and XY sex reversal. We report here evidence supporting that SOX9 duplication can cause XX sex reversal. A newborn infant was referred for genetic evaluation because of abnormal male external genitalia. The infant had severe penile/scrotal hypospadias. Gonads were palpable. Cytogenetic analysis demonstrated a de novo mosaic 46,XX,dup(17)(q23.1q24.3)/46, XX karyotype. Fluorescent in situ hybridization (FISH) with a BAC clone containing the SOX9 gene demonstrated that the SOX9 gene is duplicated on the rearranged chromosome 17. The presence of SRY was ruled out by FISH with a probe containing the SRY gene and polymerase chain reaction with SRY-specific primers. Microsatellite analysis with 13 markers on 17q23-24 determined that the duplication is maternal in origin and defined the boundary of the duplication to be approximately 12 centimorgans (cM) proximal and 4 cM distal to the SOX9 gene. Thus, SOX9 duplication is the most likely cause for the sex reversal in this case because it plays an important role in male sex determination and differentiation. This study suggests that extra dose of SOX9 is sufficient to initiate testis differentiation in the absence of SRY. Other SRY-negative XX sex-reversed individuals deserve thorough investigation of SOX9 gene.

Effects of environmental aerosols on airway hyperresponsiveness in a murine model of asthma

Increased morbidity in persons suffering from inflammatory lung diseases, such as asthma and bronchitis, has been associated with air pollution particles. One hypothesis is that particles can cause an amplification of the pulmonary inflammation associated with these diseases, thus worsening affected individuals' symptoms. This hypothesis was tested in a murine model of asthma by inhalation exposure to (1) concentrated air particles (CAPs), (2) the leachate of residual oil fly ash (ROFA-S), and (3) lipopolysaccharide (LPS). Allergen-sensitized mice (ip ovalbumin, OVA) were 21 days old when challenged with an aerosol of 3% OVA in phosphate-buffered saline (PBS) for 10 min (controls were challenged with PBS only) for 3 days. On the same days, mice were further exposed to 1 of 3 additional agents: CAPs (or filtered air) for 6 h/day; LPS (5 microg/ml, or PBS) for 10 min/day; or ROFA-S (leachate of 50 mg/ml, or PBS) for 30 min on day 2 only. At 24 h later, mice challenged with OVA aerosol showed airway inflammation and airway hyperresponsiveness (AHR) to methacholine (Mch), features absent in mice challenged with PBS alone. Both OVA- and PBS-challenged mice subsequently exposed to ROFA-S showed increased AHR to Mch when compared to their respective controls (OVA only or PBS only). In contrast, when OVA-challenged mice were further exposed to CAPs or LPS, no changes in AHR were seen in comparison to mice challenged with OVA only. Bronchoalveolar lavage (BAL) analysis and histopathology 48 h postexposure showed OVA-induced allergic inflammation. No significant additional effects were caused by CAPs or ROFA-S. LPS, in contrast, caused significant increases in total cell, macrophage, and polymorphonuclear cell numbers. The data highlight discordance between airway inflammation and hyperresponsiveness.

Spectral karyotypic study of the HL-60 cell line: detection of complex rearrangements involving chromosomes 5, 7, and 16 and delineation of critical region of deletion on 5q31.1

Interstitial deletions of the q arm of chromosome 5 have been associated with acute myelogenous leukemia (AML); therefore, accurate identification of rearrangements of this chromosome in a model cell line, HL-60, is important for understanding the critical genes involved in this disease. In this study, we employed a newly developed technology termed spectral karyotyping to delineate chromosomal rearrangements in this cell line. Our study revealed a derivative of chromosome 7 that resulted from translocations of chromosome arms 5q and 16q to 7q; that is, der(7)t(5;7)(?;q?)t(5;16)(?;q?). Interestingly, both chromosomes 5 and 7 were also involved in translocations with chromosome 16 in der(16) t(5;16)(q?;q?22-24) and der(16)t(7;16)(?;q?22-24), respectively. Other notable chromosomal abnormalities that were not previously reported in the HL-60 included an insertion of chromosome 8 in the q arm of chromosome 11, a translocation between chromosomes 9 and 14, and a translocation between chromosomes 14 and 15. In an attempt to define the loss of the 5q31.1 region in HL-60, we performed fluorescence in situ hybridization analysis by utilizing bacterial artificial chromosomes BAC1 and BAC2 that spanned the IL9 and EGR1 gene interval, which was previously shown to be a critical region of loss in AML. We showed that a copy of both BAC1 (spanning the D5S399 locus) and BAC2 (spanning the D5S393 locus centromeric to BAC1) were present in the normal chromosome 5, but a second copy of BAC1 was lost and a second copy of BAC2 was inserted in the der(16)t(7;16) chromosome. Thus, not only was this study the first to use the new 24-color karyotyping technique to identify several novel chromosomal rearrangements in HL-60, but it also narrowed the 5q31.1 critical region of deletion to the region represented by BAC1.

Late changes in spliceosomal introns define clades in vertebrate evolution

The evolutionary origin of spliceosomal introns has been the subject of much controversy. Introns are proposed to have been both lost and gained during evolution. If the gain or loss of introns are unique events in evolution, they can serve as markers for phylogenetic analysis. We have made an extensive survey of the phylogenetic distribution of seven spliceosomal introns that are present in Fugu genes, but not in their mammalian homologues; we show that these introns were acquired by actinopterygian (ray-finned) fishes at various stages of evolution. We have also investigated the intron pattern of the rhodopsin gene in fishes, and show that the four introns found in the ancestral chordate rhodopsin gene were simultaneously lost in a common ancestor of ray-finned fishes. These changes in introns serve as excellent markers for phylogenetic analysis because they reliably define clades. Our intron-based cladogram establishes the difficult-to-ascertain phylogenetic relationships of some ray-finned fishes. For example, it shows that bichirs (Polypterus) are the sister group of all other extant ray-finned fishes.

Prenatal diagnosis of a mosaic extra structurally abnormal chromosome by spectral karyotyping

A de novo mosaic extra structurally abnormal chromosome (ESAC) was detected in 33 per cent of cultured amniotic fluid cells from a pregnant woman. Neither Q-banding nor fluorescence in situ hybridization (FISH) employing a DNA probe for nucleolar organizer region demonstrated the presence of satellites on the ESAC. Spectral karyotyping (SKY) was performed in this prenatal case and led to a quick and accurate determination of the ESAC as chromosome 14 in origin. The SKY finding was confirmed by conventional FISH analysis using a chromosome 14 specific painting probe. Subsequent hybridizations with a centromeric probe and a 14q subtelomeric probe were also performed to further characterize the ESAC. Absence of (TTAGGG)n sequence on the ESAC, determined postnatally, suggested it is a ring chromosome 14. Genetic counselling concerning these findings was provided to the parents who chose to continue the pregnancy. The male infant had no apparent abnormal phenotype at birth.

Identification of a gene that reverses the immortal phenotype of a subset of cells and is a member of a novel family of transcription factor-like genes

Based on the dominance of cellular senescence over immortality, immortal human cell lines have been assigned to four complementation groups for indefinite division. Human chromosomes carrying senescence genes have been identified, including chromosome 4. We report the cloning and identification of a gene, mortality factor 4 (MORF 4), which induces a senescent-like phenotype in immortal cell lines assigned to complementation group B with concomitant changes in two markers for senescence. MORF 4 is a member of a novel family of genes with transcription factor-like motifs. We present here the sequences of the seven family members, their chromosomal locations, and a partial characterization of the three members that are expressed. Elucidation of the mechanism of action of these genes should enhance our understanding of growth regulation and cellular aging.

Enhancement of aflatoxin B1-induced enzyme altered hepatic foci in rats by treatment with carbon tetrachloride

The effect of carbon tetrachloride (CCl4) on aflatoxin B1 (AFB1)-induced enzyme altered hepatic foci has been examined in young male Fischer rats given AIN-76A diet. A single i.p. dose of AFB1 (0.2 mg/kg body wt) was given to rats 24 h after partial hepatectomy. Two weeks later, CCl4 (0.8 ml/kg body wt) was injected i.p. once a week for 9 weeks. Animals were sacrificed 24 h after the last dose of CCl4 and glutathione S-transferase placental form (GST-P) and gamma-glutamyl transpeptidase (GGT) positive hepatic foci were analyzed by immunohistochemical and histochemical methods, respectively. Ten weeks after AFB1 dosing, treatment with CCl4 increased the number of AFB1-induced enzyme altered foci several fold and produced a ten to twenty-fold increase in area and volume. GST-P was more sensitive than GGT in detecting AFB1-induced enzyme altered foci. Treatment with AFB1 or CCl4 produced mild hepatic fibrosis in zones 1 and 3 respectively, whereas both treatments produced severe fibrosis in zones 1 to 3 areas. Treatment with CCl4 after AFB1 dosing lowered hepatic GSH levels by 20% and increased lipid peroxidation by 40%. It appears that CCl4, by being an effective enhancer of AFB1-induced enzyme altered hepatic foci in the rat, may mimic cirrhosis observed in human hepatocellular carcinoma.

Identification of an unusual marker chromosome by spectral karyotyping

We ascertained a newborn girl with multiple congenital anomalies including severe hypotonia, cardiovascular defects, hearing loss, central nervous system anomalies, and facial anomalies. The infant died at 12 days. Cytogenetic analysis showed a de novo supernumerary marker chromosome. Fluorescence in situ hybridization (FISH) with a combination of chromosome specific alpha-satellite probes and an all-human centromere probe failed to show hybridization to the marker, indicating that the marker chromosome lacked detectable alpha satellite sequences. Spectral karyotyping (SKY) was performed and showed that the marker was chromosome 15 in origin. This was confirmed by FISH with a 15q specific subtelomerie probe, which showed hybridization to both ends of the marker chromosome. Based on FISH information and G-banding pattern, the marker was determined to be an inverted duplication of 15q25-qter, leading to partial tetrasomy for chromosome 15. Although the marker chromosome lacked detectable centromeric alpha-satellite sequences, it seemed to have a functional centromere as it is mitotically stable. This observation is consistent with previous studies on acentric marker chromosomes, which suggested that the DNA sequence at the breakpoint could function similarly to alpha-satellite sequences once activated through marker formation.

FISH analysis of a complex chromosome rearrangement involving nine breakpoints on chromosomes 6, 12, 14 and 16

We report the prenatal diagnosis of an apparently balanced de novo complex chromosome rearrangement (CCR) which involved nine breakpoints on four different chromosomes. Fluorescence in situ hybridization (FISH) and spectral karyotyping (SKY) were performed as an adjunct to G-banding for characterization of the abnormal chromosomes. The 22-week female fetus showed minor dysmorphic features including dolichocephaly, broad fingernails, tibial bowing, clubfoot, thoracolumbar scoliosis and hypoplastic toenails. Autopsy revealed gall-bladder hypoplasia and an atrial septal defect. Chromosome analysis of fetal tissue confirmed the presence of the complex rearrangement.

Plasma thyroid hormones in premature infants: effect of gestational age and antenatal thyrotropin-releasing hormone treatment. TRH Collaborative Trial Participants

Thyroid hormones are important for both perinatal adaptation and long-term psychomotor development; however, there is limited information on the effects of extreme prematurity and antenatal TSH-releasing hormone (TRH) treatment on pituitary-thyroid function. In this study we assayed plasma triiodothyronine (T3) and TSH in infants who were part of a collaborative trial of antenatal maternal TRH therapy. Within the control population (n = 166), infants of 24-28-wk and 28-32-wk gestational age had comparable levels of T3 (0.94 and 1.06 nmol/L, respectively) and TSH (5.7 and 7.2 mU/L) at birth, but the increases at 2 h and subsequent T3 levels were less in the 24-28 wk versus 28-32-wk gestation infants. In the TRH-treated group (n = 131), T3 was lower in the first day for infants delivered 7-72 h after antenatal TRH compared with control infants. TSH at birth was approximately 3.5-fold greater for infants delivered at 0-6 h after the last TRH dose compared with the control group and was suppressed in infants delivering at 7-36 h. T3 and TSH levels were not different between control and TRH-treated groups at 3-28 d of age. In TRH stimulation tests on d 28, control and TRH-treated groups had similar peak levels of TSH and incidence of exaggerated response (TSH > or = 35 mU/L). We conclude that extremely premature infants have a reduced postnatal surge in TSH and T3 and maintain lower T3 concentrations, probably reflecting tertiary hypothyroidism. The stimulatory and suppressive effects of antenatal TRH treatment observed at birth are transient and do not affect pituitary-thyroid responsiveness at 28 d of age.

Chromosome painting: a useful art

Chromosome 'painting' refers to the hybridization of fluorescently labeled chromosome-specific, composite probe pools to cytological preparations. Chromosome painting allows the visualization of individual chromosomes in metaphase or interphase cells and the identification of both numerical and structural chromosomal aberrations in human pathology with high sensitivity and specificity. In addition to human chromosome-specific probe pools, painting probes have become available for an increasing range of different species. They can be applied to cross-species comparisons as well as to the study of chromosomal rearrangements in animal models of human diseases. The simultaneous hybridization of multiple chromosome painting probes, each tagged with a specific fluorochrome or fluorochrome combination, has resulted in the differential color display of human (and mouse) chromosomes, i.e. color karyotyping. In this review, we will summarize recent developments of multicolor chromosome painting, describe applications in basic chromosome research and cytogenetic diagnostics, and discuss limitations and future directions.

Multicolor spectral karyotyping identifies new recurring breakpoints and translocations in multiple myeloma

Karyotypic information on multiple myeloma (MM) is less extensive than that on other myeloid or lymphoid malignancies due to low mitotic activity of plasma cells. An add(14)(q32) marker chromosome has been reported to be the most frequent recurring abnormality in clonally abnormal cases; in approximately one third of the latter cases, this marker has been identified as a der(14)t(11;14)(q13;q32) chromosome. To map chromosomal breakpoints, characterize the add(14)(q32) marker chromosomes, and to identify other recurring translocations in MM, we used spectral karyotyping (SKY) to analyze a panel of nine bone marrow (BM) biopsy samples from eight patients and 10 tumor cell lines derived from MM patients. SKY involves hybridization of 24 fluorescently labeled chromosome painting probes to metaphase spreads in such a manner that simultaneous visualization of each of the chromosomes in a different color is accomplished. By this method, it was possible to define all chromosomal rearrangements and identify all of the clonal marker chromosomes in tumor cells. By detailed mapping of breakpoints of rearrangement, it was also possible to identify several novel recurring sites of breakage that map to the chromosomal bands 3q27, 17q24-25, and 20q11. The partner chromosomes in translocations that generated the add (14)(q32) marker chromosomes were identified in all cases in which they were detected by G-banding (one biopsy and six cell lines). In addition, two new translocations involving band 14q32, ie, t(12;14)(q24;q32) and t(14;20)(q32;q11) have also been identified. These studies demonstrate the power of SKY in resolving the full spectrum of chromosome abnormalities in tumors.

Cytogenetic and molecular characterization of random chromosomal rearrangements activating the drug resistance gene, MDR1/P-glycoprotein, in drug-selected cell lines and patients with drug refractory ALL

Drug resistance, both primary and acquired, is a major obstacle to advances in cancer chemotherapy. In vitro, multidrug resistance can be mediated by P-glycoprotein (PGY1), a cell surface phosphoglycoprotein that acts to efflux natural products from cells. PGY1 is encoded by the MDR1 gene located at 7q21.1. Overexpression of MDR1 has been demonstrated in many cancers, both in patient tumors and in cell lines selected with a variety of chemotherapeutic agents. Recent studies in drug-selected cell lines and patients samples have identified hybrid mRNAs comprised of an active, but apparently random, gene fused 5' to MDR1. This observation indicates that random chromosomal rearrangements, such as translocations and inversions, leading to "capture" of MDR1 by constitutively expressed genes may be a mechanism for activation of this gene following drug exposure. In this study, fluorescence in situ hybridization (FISH) using whole chromosome paints (WCP) and bacterial artificial chromosome (BAC)-derived probes showed structural rearrangements involving 7q in metaphase and interphase cells, and comparative genomic hybridization (CGH) revealed high levels of amplification at chromosomal breakpoints. In an adriamycin-selected resistant colon cancer line (S48-3s/Adr), WCP4/WCP7 revealed t(4;7)(q31;q21) and BAC-derived probes demonstrated that the breakpoint lay between MDR1 and sequences 500-1000 KB telomeric to it. Similarly, in a subline isolated following exposure to actinomycin D (S48-3s/ActD), a hybrid MDR1 gene composed of heme oxygenase-2 sequences (at 16p13) fused to MDR1 was identified and a rearrangement confirmed with WCP7 and a subtelomeric 16p probe. Likewise, in a paclitaxel-selected MCF-7 subline where CASP sequences (at 7q22) were shown to be fused to MDR1, WCP7 showed an elongated chromosome 7 with a homogeneously staining regions (hsr); BAC-derived probes demonstrated that the hsr was composed of highly amplified MDR1 and CASP sequences. In all three selected cell lines, CGH demonstrated amplification at breakpoints involving MDR1 (at 7q21) and genes fused to MDR1 at 4q31, 7q22, and 16p13.3. Finally, in samples obtained from two patients with drug refractory ALL, BAC-derived probes applied to archived marrow cells demonstrated that a breakpoint occurred between MDR1 and sequences 500-1000 KB telomeric to MDR1, consistent with a random chromosomal rearrangement. These results support the proposal that random chromosomal rearrangement leading to capture and activation of MDR1 is a mechanism of acquired drug resistance.

Stromelysin-3 is induced in tumor/stroma cocultures and inactivated via a tumor-specific and basic fibroblast growth factor-dependent mechanism

Stromelysin-3 (STR-3) is a recently characterized matrix metalloproteinase (MMP) with a unique pattern of expression and substrate specificity. Unlike other MMPs, STR-3 is consistently and dramatically overexpressed by multiple epithelial malignancies, including carcinomas of the breast, lung, colon, head and neck, and skin. Recent studies suggest that STR-3 promotes the local establishment of epithelial malignancies, contributing to tumor cell survival and implantation in host tissues; however, STR-3's mechanism of action remains undefined. STR-3 is a stromal cell product, prompting speculation that infiltrating stromal cells secrete STR-3 in response to tumor-derived factors. To explore this possibility, we developed a tumor/"stroma" coculture assay in which non-small cell lung cancer (NSCLC) cell lines were grown on confluent monolayers of normal pulmonary fibroblasts. In these tumor/stroma cocultures, NSCLCs stimulate normal pulmonary fibroblasts to secrete STR-3 and release extracellular basic fibroblast growth factor. Thereafter, STR-3 is processed at a unique internal sequence via a basic fibroblast growth factor- and MMP-dependent mechanism to a previously unidentified 35-kDa protein that lacks enzymatic activity. 35-kDa STR-3 is the most abundant STR-3 protein in tumor/stroma cocultures and is only detected when normal pulmonary fibroblasts are cultured with malignant bronchial epithelial cells. Therefore, the tumor-specific processing of STR-3 to the 35-kDa protein is likely to be an important regulatory mechanism.

p53 protein expression in patients with hepatocellular carcinoma from the high incidence area of Guangxi, Southern China

Mutation of the p53 gene has been reported in hepatocellular carcinoma (HCC) occurring worldwide. The most frequent p53 mutation has been found in HCCs in regions with high hepatitis B virus (HBV) infection and intake of aflatoxin B1 (AFB1). The aim of our study was to examine p53 protein expression in HCCs from a high incidence area of Guangxi, Southern China, where HBV infection and dietary intake of AFB1 are high. Immunohistochemical staining of p53 protein was carried out using a polyclonal rabbit antibody (CM-1). Serial sections were also stained for hepatitis B surface antigen and core antigen. p53 Protein expression was detected in 13 (43.3%) of the 30 HCCs. Expression of p53 was found in 25.0% (1/4) of the < or = 5.0 cm diameter HCCs, in 36.8% (7/19) of the 5.1-10.0 cm diameter HCCs and in 71.4% (5/7) of the >10.0 cm diameter HCCs. Expression of p53 was observed more in moderately and poorly differentiated than in the well differentiated HCCs and more frequently seen in HCCs from younger patients. These data indicate that there is a close association between p53 protein expression and tumor size, histological grade and age of patients. Twenty-seven out of 30 cases (90.0%) were positive for HBV. No significant association between p53 expression and sex. HBV infection, cirrhosis or alpha-fetoprotein has been found.

Spectral karyotyping refines cytogenetic diagnostics of constitutional chromosomal abnormalities

Karyotype analysis by chromosome banding is the standard method for identifying numerical and structural chromosomal aberrations in pre- and postnatal cytogenetics laboratories. However, the chromosomal origins of markers, subtle translocations, or complex chromosomal rearrangements are often difficult to identify with certainty. We have developed a novel karyotyping technique, termed spectral karyotyping (SKY), which is based on the simultaneous hybridization of 24 chromosome-specific painting probes labeled with different fluorochromes or fluorochrome combinations. The measurement of defined emission spectra by means of interferometer-based spectral imaging allows for the definitive discernment of all human chromosomes in different colors. Here, we report the comprehensive karyotype analysis of 16 samples from different cytogenetic laboratories by merging conventional cytogenetic methodology and spectral karyotyping. This approach could become a powerful tool for the cytogeneticists, because it results in a considerable improvement of karyotype analysis by identifying chromosomal aberrations not previously detected by G-banding alone. Advantages, limitations, and future directions of spectral karyotyping are discussed.

Glucocorticoid regulation of surfactant components in immature lambs

To assess effects of dose and duration of glucocorticoid exposure on maturation of the fetal lung, we administered single or multiple doses of betamethasone (0.5 mg/kg im) to pregnant sheep for 2 or 21 days before preterm delivery at 125 days of gestation. Lung function (compliance, lung volume at 40 cmH2O pressure, and ventilatory efficiency index) was increased after two to four weekly doses of glucocorticoid (2.5- to 4-fold increase) and after 48 h of exposure (1.4- to 2.3-fold). Total protein of lavage fluid decreased similarly with three doses, four doses, and 48 h of treatment. In lambs with long-term exposure to betamethasone, there was a similar, dose-dependent increase in concentrations of saturated phosphatidylcholine and surfactant proteins A (SP-A) and B (SP-B) (maximal 2- to 3-fold in tissue and 10- to 15-fold in lavage fluid). Levels of SP-A and SP-B were closely correlated in lavage fluid. In animals treated for 48 h, only tissue SP-B was increased (2.7-fold). We conclude that 48 h of glucocorticoid treatment improves lung function in the premature lamb without a detectable increase in lavage surfactant components and that longer exposure to antenatal glucocorticoid increases surfactant lipid and proteins in a coordinated fashion. The enhanced response with repetitive dosing indicates that the process of glucocorticoid-induced lung maturation is either reversible and/or gestational age dependent.

A microfabricated device for rapid protein identification by microelectrospray ion trap mass spectrometry

Nanoelectrospray mass spectrometry, the infusion at low flow rates of unseparated peptide mixtures representing protein proteolytic digests into an electrospray ionization mass spectrometer (MS), has been shown to be a suitable method for the analysis of small amounts of proteins. However, the current technique is time consuming, tedious, and difficult to automate. We used microfabrication technologies to construct a device for the sequential infusion of different peptide samples into an electrospray ionization MS without the need for sample manipulation. In this device, etched sample and buffer reservoirs are connected via etched channels to microelectrospray ion source. Peptide samples, typically unseparated tryptic digests of proteins, are applied to different reservoirs. A flow of liquid originating from a specific reservoir is generated and selectively directed toward the microsprayer and the MS by electroosmotic pumping. The analyte proteins are identified by searching sequence databases with the information contained in the collision-induced spectra of selected peptides. With this system, we have achieved a limit of detection in the low femtomoles per microliter range for peptide standards. We also show that samples deposited in different reservoirs can be sequentially mobilized without cross-contamination and that proteins can be conclusively identified at the low femtomoles per microliter level. The successful coupling online of microfabricated devices to an electrospray ionization MS represents an essential step toward the construction of automated, high-throughput, and high-sensitivity analytical systems.

Transcriptional regulation of surfactant proteins SP-A and SP-B by phorbol ester

Phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate (TPA) activate protein kinase C and have been previously shown to down-regulate surfactant proteins SP-A and SP-B in H441 adenocarcinoma cells. We used H441 cells and human fetal lung to further study the mechanism of TPA action and to examine physiologic relevance. In H441 cells, TPA (10 nM) treatment for 24 h decreased SP-A mRNA content to approximately 5% of control cells, with half-maximal effect at approximately 0.5 nM, and reduced SP-A gene transcription rate to 28% of control after 8 h exposure. In cells cultured in the presence of dexamethasone, which increases the low basal level of SP-B expression, TPA decreased both SP-B mRNA content (approximately 8% of control) and rate of transcription (7% of control). In cultured human fetal lung explants, TPA decreased SP-A and SP-B protein and mRNA in a time- and dose-dependent fashion, with half-maximal effect on mRNAs at approximately 3 nM and approximately 50% inhibition after 24 h of exposure, and similarly reduced SP-A and SP-B gene transcription (approximately 55% of control at 8-24 h). We conclude that TPA acts primarily at the level of gene transcription to down-regulate both SP-A and SP-B in H441 and fetal lung cells, and we speculate that inflammatory and other agents that act through PKC may modulate expression of the surfactant proteins and alter surfactant function in vivo.

Inhibition of aflatoxin B1-induced initiation of hepatocarcinogenesis in the rat by green tea

Several studies have demonstrated that green tea (GT) inhibits various chemically induced cancers in experimental animals. In the present study, effect of GT has been examined on the initiation of aflatoxin B1 (AFB1)-induced hepatocarcinogenesis in the rat. Young male Fischer rats were given AIN-76A diet with or without 0.5% instant GT powder in their drinking water for 2 or 4 weeks. Initiation was examined by hepatic AFB1-DNA binding in vivo, AFB1 metabolism in vitro and by the appearance of AFB1-induced glutathione S-transferase placental form (GST-P)-positive hepatocytes detected by immunohistochemical method. There was no influence of GT feeding on microsome-mediated AFB1 binding to exogenous DNA. However, GT feeding enhanced microsome-mediated formation of non-toxic hydroxylated metabolites of AFB1 by 2-3-fold. Hepatic nuclear AFB1-DNA binding in vivo was significantly inhibited by about 20-30% in animals pretreated with GT: AFB1-induced GST-P positive single hepatocytes were inhibited significantly by 60-70% in rats pretreated with GT. These results suggest that feeding of GT inhibits initiation of AFB1-induced hepatocarcinogenesis in the rat by modulation of AFB1 metabolism, thereby inhibiting AFB1-DNA binding and AFB1-induced GST-P-positive hepatocytes.

Molecular characterization of a 130-kb terminal microdeletion at 22q in a child with mild mental retardation

We have analyzed a recently described 22q13.3 microdeletion in a child with some overlapping features of the cytologically visible 22q13.3 deletion syndrome. Patient NT, who shows mild mental retardation and delay of expressive speech, was previously found to have a paternal microdeletion in the subtelomeric region of 22q. In order to characterize this abnormality further, we have constructed a cosmid/P1 contig covering the terminal 150 kb of 22q, which encompasses the 130-kb microdeletion. The microdeletion breakpoint is within the VNTR locus D22S163. The cloning of the breakpoint sequence revealed that the broken chromosome end was healed by the addition of telomeric repeats, indicating that the microdeletion is terminal. This is the first cloned terminal deletion breakpoint on a human chromosome other than 16p. The cosmid/P1 contig was mapped by pulsed-field gel electrophoresis analysis to within 120 kb of the arylsulfatase A gene, which places the contig in relation to genetic and physical maps of the chromosome. The acrosin gene maps within the microdeletion, approximately 70 kb from the telomere. With the distal end of chromosome 22q cloned, it is now possible to isolate genes that may be involved in the overlapping phenotype of this microdeletion and 22q13.3 deletion syndrome.

Regulation of surfactant protein D in human fetal lung

Surfactant protein D (SP-D) is a collagenous glycoprotein, produced by lung type II cells, that has structural and functional similarities with SP-A. In this study we postulated that SP-D and SP-A gene expression are regulated in a similar fashion to provide a coordinated local immune defense response to pulmonary infection. We determined content of SP-D protein and mRNA in second-trimester fetal lung and in postnatal tissue by protein blotting and hybridization analyses. Low levels of SP-D mRNA and protein were detected at 16 wk gestation, before appearance of SP-A, and levels increased during gestation. The content of SP-D did not change during 5 days of explant culture, whereas SP-A increased manyfold. Dexamethasone treatment during culture increased SP-D mRNA and protein about 2-fold with maximal response after 1 to 3 days' exposure to 100 nM steroid; under the same conditions SP-A mRNA content is inhibited. There was no significant change in SP-D mRNA after treatment of explants with adenosine 3',5'-monophosphate (cAMP) analog or interferon-gamma, agents which increase SP-A gene expression, nor after exposure to phorbol ester, tumor necrosis factor-alpha, or lipopolysaccharide at concentrations that reduced levels of SP-A mRNA by approximately 50%. We conclude that SP-D in the human lung is under developmental and glucocorticoid regulation occurring at a pretranslational level. SP-D is not influenced by inflammatory mediators that regulate SP-A, suggesting that these two proteins are not coordinately regulated in response to lung infection.

Characterization of familial partial 10p trisomy by chromosomal microdissection, FISH, and microsatellite dosage analysis

Unbalanced translocations are a frequent cause of multiple congenital anomalies in children. Translocations as small as 2-5 Mb of DNA are detectable by G-banding under optimal conditions. Some of these small translocations are visible but cannot be characterized cytogenetically due to the lack of characteristic banding on Giemsa preparations. We have combined chromosomal microdissection and fluorescence in situ hybridization (FISH) to identify the origin of a small translocated segment in three members of a family with a derivative chromosome 9 and multiple anomalies, including several ophthalmologic anomalies. We microdissected the abnormal region of the derivative 9 chromosome and used this DNA to generate a FISH probe. This probe hybridized to distal 10p on the metaphase spread of the proband, indicating the origin of the translocated segment. A whole 10p FISH probe confirmed the origin by hybridizing to the translocated segment of the derivative chromosome. FISH was then performed with a whole chromosome 9 painting probe and excluded the presence of a reciprocal, balancing translocation. We then studied the chromosome 10 partial duplication with microsatellite markers to better characterize the chromosomal segment that caused these phenotypic features. By examining the involved areas with distal 10p and 9p microsatellite markers, we were able to demonstrate a minimum of 9 Mb of trisomic 10p DNA with a chromosomal breakpoint between 10p14-10p15. We then compared this family's clinical findings to those of individuals with partial 10p trisomy who had been reported in the literature. The clinical phenotypes seen in this family are similar to, but milder than, the phenotypes of persons with the larger partial trisomies of 10p that were diagnosable by cytogenetic analysis alone. This study shows that microdissection and DNA markers can be used to precisely define small translocations that are difficult to identify by conventional G-banded chromosome analysis.

Identification of a novel paternally expressed transcript adjacent to snRPN in the Prader-Willi syndrome critical region

Small nuclear ribonucleoprotein-associated polypeptide N (snRPN) and an anonymous transcript, PAR-5, are two of the paternally expressed transcripts mapped to the Prader-Willi syndrome critical region. Using long-range PCR, we have isolated the genomic interval between snRPN and PAR-5, identified a novel transcript in this region, and termed it PAR-SN. Northern analysis demonstrates that PAR-SN is expressed in brain, skeletal muscle, and heart. Like snRPN and PAR-5, PAR-SN is expressed exclusively from the paternal homolog in cultured lymphoblasts. Sequence analysis of the transcript revealed no significant open reading frame but did include a polymorphic dinucleotide repeat (CA)17.

Multicolor spectral karyotyping of human chromosomes

The simultaneous and unequivocal discernment of all human chromosomes in different colors would be of significant clinical and biologic importance. Whole-genome scanning by spectral karyotyping allowed instantaneous visualization of defined emission spectra for each human chromosome after fluorescence in situ hybridization. By means of computer separation (classification) of spectra, spectrally overlapping chromosome-specific DNA probes could be resolved, and all human chromosomes were simultaneously identified.

Isolation of the human chromosome 22q telomere and its application to detection of cryptic chromosomal abnormalities

A number of human telomeres have been successfully cloned using a modified yeast artificial chromosome (YAC) vector (half-YAC) cloning strategy, but to date, human chromosome 22q has not been identified by this approach. We used an alternative approach of genomic walking, starting from a subtelomeric sequence, Tel-Bam3.4. present on a number of human chromosomes including 22q. This approach was successful in the development of a cosmid contig representing the terminal 140 kb of human chromosome 22q, providing telomeric closure of the genetic and physical maps for 22q. The most distal region of the contig contains subtelomeric repeats which crosshybridize to a number of chromosomes, while the proximal sequences are unique for 22q. The unique sequence cosmid was used as a 22qter-specific probe for fluorescence in situ hybridization (FISH) analysis, which confirmed that this cosmid was distal to the most telomeric marker previously available for chromosome 22. In addition, this cosmid was used to document a 22q terminal deletion that was not detectable by conventional cytogenetic analysis. Unique telomere-specific FISH probes such as this one will have significant diagnostic value in the detection of cryptic deletions and translocations in patients with unexplained mental retardation and other patient populations.

Detection of a subtle rearrangement of chromosome 22 using molecular techniques

Conventional cytogenetics is a useful clinical tool that has a lower limit of sensitivity of 2-5 Mb for detection of duplications or deletions. Because the threshold of clinically significant aneusomy is below this range, there is a need for approaches to improve the sensitivity of the detection of aneusomy. We have implemented a system of screening for subtle unbalanced translocations in children with multiple congenital anomalies of unknown cause. Our approach uses subtelomeric microsatellite markers to detect small areas of segmental aneusomy due to unbalanced translocations. Herein we report a patient with severe multiple congenital anomalies and a normal karyotype who was diagnosed by this approach. Microsatellite markers from 41 telomeres were analyzed and were normal with the exception of those on distal chromosome 22. Further analysis with additional microsatellites and fluorescent in situ hybridization confirmed duplication of 22q13.2-qter. We conclude that microsatellite screening can detect subtle unbalanced translocations in children with severe anomalies.

The vascular cell adhesion molecule (VCAM-1) is expressed on a subset of lymphoid and myeloid leukaemias

The expression of the vascular cell adhesion molecule (VCAM-1), recently identified as cytokine-inducible ligand of the beta 1-integrin VLA-4, was investigated on normal and malignant haemopoietic precursors as well as on haemopoietic cell lines. VCAM-1 was demonstrated on > 20% blasts in 4/22 acute myeloid leukaemia (AML) and 6/10 acute lymphoblastic leukaemia (ALL) specimens but was absent from CD34+ normal bone marrow precursor cells. Interestingly, the VCAM-1+ AMLs classified as M1 and M5 simultaneously expressed N-CAM (CD56), a member of the immunoglobulin family. In ALL, VCAM-1 expression was restricted to Calla+ CD19+ precursors of the c-ALL subtype. VCAM-1 was also found on some cell lines, mainly of the B-lymphocytic type. Furthermore, in 13/20 chronic lymphocytic leukaemia (CLL) samples > 20% of the CD19+ B-lymphocytic precursors carried VCAM-1, which seemed to correlate with more advanced disease. Therefore VCAM-1 expression appeared to characterize leukaemic cells of the B-cell lineage as well as a CD56+ subset of AML. Since its expression was clinically correlated with dermal infiltrates of leukaemic cells in AML and with advanced Rai stages in CLL, VCAM-1 may play a role in enhanced adhesion of the malignant cells to tissues and/or to each other.

[A study of prostaglandine E(2) level in root canal fluid of patients with periapical lesions]

It has been reported that there is close relationship between prostaglandine E(PGE) and the pathogenesis of periapical lesions, In this study the root canal fluid(RCF) of 35 cases with acute,chronic and convalescent periradicular lesions were collected with assessed by the method of radioimmunoassay.The results showed:RCF-PGE(2) levels were increased with the severity of periapical lesion(P<0.01).The PGE level was highest in acute periradicular lesions,middle in chronic,and lowest in convalescent.RCF-PGE(2) levels were significantly different between either two groups of the three groups of patients(P<0.01-0.05).This study repeatedly proved that PGE(2) has certain effect in pathogenesis of periapical lesions and it is meaningful in guiding clinical therapy.It was also pointed out that RCF is one of worthwhile samples in the study of periradicular lesion.

Cloning of senescent cell-derived inhibitors of DNA synthesis using an expression screen

We here describe a rapid and simple expression screen method that has allowed us to isolate cDNAs coding for inhibitors of DNA synthesis from senescent human diploid fibroblasts. The assay involved transient transcriptional overexpression of a gene product encoded by a cDNA in a proliferating cell, on the assumption that this would be sufficient to block DNA synthesis in a short-term assay using tritiated thymidine autoradiography. Three cDNAs, referred to as senescent cell-derived inhibitors (sdi), that exhibit DNA synthesis-inhibitory activity when introduced into young cycling cells, were successfully identified. Expression of one of the cDNAs, sdi1, increased 10- to 20-fold in senescent compared with young cells and the increase in RNA closely paralleled the onset of the senescent phenotype and loss of cell proliferation. sdi1 expression was also increased in young cells made nondividing (quiescent) by deprivation of growth factors or contact inhibition. Following serum stimulation, RNA levels of sdi1 in quiescent cells were initially increased, but then declined to low levels just prior to the entry of the cells into S phase. In contrast, RNA levels of sdi1 in senescent cells failed to decline, suggesting a role for this gene in maintaining the senescent phenotype. The sdi1 gene has been mapped to the p arm of chromosome 6.

Highly polymorphic tetramer repeat (GATA)n on human chromosome 11p15.3

A tetrameric repeat sequence (GATA)n was identified by random DNA sequencing of chromosome 11-specific cosmid clones and located at 11p15.3 by fluorescence in situ hybridization. Oligonucleotide primers flanking the repetitive unit were used to amplify the DNA using the polymerase chain reaction (PCR) and this repetitive element was shown to be highly polymorphic and inherited in typical Mendelian fashion. Analysis of amplification products containing the repetitive element from 45 unrelated Caucasian individuals and five families showed at least five alleles at this locus, ranging from 227 to 249 bases in length. This polymorphism may serve as a useful PCR-detectable genetic marker for 11p15.3, a landmark for disease gene isolation, and a locus for identity testing.

"PCR karyotype" of monochromosomal somatic cell hybrids

Following fusion of human diploid fibroblast-derived microcells with mouse A9 cells, we isolated seven monochromosomal hybrids containing a single human chromosome 2, 3, 5, 12, 15, 20, or 22. Cytogenetic analysis as well as PCR karyotyping (chromosome-specific banding pattern generated by Alu-PCR) was performed on all the hybrids. We here present, for the first time, the specific PCR karyotypes of human chromosomes 2 and 20.

FK506 binding to the 56-kilodalton immunophilin (Hsp56) in the glucocorticoid receptor heterocomplex has no effect on receptor folding or function

It has recently been reported that the hsp56 component of glucocorticoid receptor heterocomplexes is an immunophilin of the FK506 binding class [Yem, A. W., Tomasselli, A. G., Heinrikson, R. L., Zurcher-Neely, H., Ruff, V. A., Johnson, R. A., & Deibel, M. R. (1992) J. Biol. Chem. 267, 2868-2871; Tai, P. K., Albers, M. W., Chang, H., Faber, L. E., & Schreiber, S. L. (1992) Science 256, 1315-1318]. The existence of binding proteins for these two potent groups of immunosuppressants in the same molecular complex compels us to ask whether FK506 affects glucocorticoid receptor function. We show here that hsp56 is a component of the native L-cell glucocorticoid receptor heterocomplex and that [3H]FK506 binds to the immunopurified, untransformed receptor complex. However, at concentrations in excess of those required to occupy all of its binding sites on hsp56, FK506 does not affect the steroid binding activity of the receptor nor does it stabilize or dissociate the receptor-hsp90 complex. FK506 does not affect steroid-mediated hsp90 dissociation from the receptor in vitro, and it does not affect steroid-mediated nuclear transfer of the receptor or steroid-mediated transcriptional enhancement from a reporter in intact cells. When immunopurified mouse glucocorticoid receptor is reconstituted into a heat shock protein complex by rabbit reticulocyte lysate, hsp56 is present in the reconstituted complex in addition to hsp90 and hsp70. FK506, however, does not affect reconstitution of the complex or return of the receptor to the steroid binding state, a change of conformation that occurs upon receptor association with hsp90.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular genetic studies of cellular senescence

The limited doubling potential of normal cells in culture was first proposed as a model for cellular aging by Hayflick in 1961. This phenomenon of in vitro cellular senescence is now well documented for a number of different normal human cell types. In an attempt to determine whether random events or programmed genetic processes were responsible for cellular aging, we performed a series of cell fusion studies. We determined that hybrids from fusion of normal with immortal human cells had limited proliferative potential, indicating that senescence is a dominant phenotype. We exploited the fact that immortality was recessive to assign a large number of different immortal human cell lines to four complementation groups for indefinite division. More recently, we have determined that the introduction of a single normal human chromosome 4 into HeLa (cervical carcinoma) cells by microcell fusion induced senescence in this immortal line. The results of these whole cell and microcell fusion studies support the hypotheses that propose senescence results from active, genetic mechanisms.

Why are transformed cells immortal? Is the process reversible?

Normal cells have finite proliferative potential in culture. In contrast, cells derived from tumors immortalized by chemical carcinogens or viruses are able to divide indefinitely. A question of major importance is the mechanism that limits the proliferative potential of normal cells, and conversely, the process by which immortal cells have escaped irreversible growth cessation. To address this question we fused a number of different normal human fibroblast cell lines with various immortal human cell lines and determined the proliferative behavior of the resulting hybrids. In all cases the hybrids had a limited ability to proliferate in culture. These results suggested that the finite proliferative capacity of normal human cells was dominant and that immortal cells had acquired recessive changes in their genetic program, which allowed them to escape senescence. We were also able to assign approximately 30 immortal human cell lines to four complementation groups for indefinite division.

Heterozygote detection through bleomycin-induced G2 chromatid breakage in dyskeratosis congenita families

We determined the mean number of chromatid breaks per cell (b/c) in the bleomycin-treated lymphocytes of 10 patients with dyskeratosis congenita (DC) and 26 of their relatives to ascertain whether bleomycin sensitivity would distinguish DC heterozygotes from normal individuals. We observed a significantly higher mean number of chromatid b/c in DC patients and obligate heterozygotes (patients versus controls, p less than 0.0001; heterozygotes versus controls, p = 0.0076, Mann-Whitney rank-sum test). Unequivocal heterozygote detection was not possible owing to overlap of the b/c values of patients, heterozygotes, and controls, but our findings provided strong evidence of a link between autosomal recessive as well as X-linked recessive DC mutations and bleomycin sensitivity in homozygous, hemizygous, and heterozygous individuals.