Construction and identification of a single stranded cDNA clone containing full-length genome of hepatitis G virus

AIM

To construct a single cDNA clone with full-length genome of hepatitis G virus (HGV) could be transcribed and expressed in vitro.

METHODS

The 5 initial HGV cDNA fragments of Iw5, Iwq2, Iwh6, Iw3 and Iw3 used in this study were amplified from serum of a Japanese non A-E hepatitis patient. These fragments overlapped and covered the entire genome from 5'-end to 3'-end of HGV cDNA. Overlap extension PCR and ligation methods were used with 12 primers for the construction of a full-length genomic HGV cDNA clone from the subgenomic fragments.

RESULTS

A single HGV cDNA clone (pHGVqz) was successfully constructed, physical mapping of the generated pHGVqz found identical to what we expected, and the sequence was deposited with the GenBank under the Accession number AF081782. The analysis of the full-length sequence, which was able to be in vitro transcribed and expressed, showed that this single clone contained 9373 nucleotides (encoding 2873 amino acids), and shared high homologies with other compared HGV isolates.

CONCLUSION

A full-length genomic HGV cDNA clone is generated for the first of the kind in this study, it could be expressed and transcripted. This single cDNA clone is expected to be of importance in the investigation on replication and pathogenicity of HGV.

Transition from an electron solid to the sequence of fractional quantum Hall states at very low Landau level filling factor

At low Landau level filling of a two-dimensional electron system, typically associated with the formation of an electron crystal, we observe local minima in Rxx at filling factors nu = 2/11, 3/17, 3/19, 2/13, 1/7, 2/15, 2/17, and 1/9. Each of these developing fractional quantum Hall (FQHE) states appears only above a filling-factor-specific temperature. This can be interpreted as the melting of an electron crystal and subsequent FQHE liquid formation. The observed sequence of FQHE states follows the series of composite fermion states emanating from nu = 1/6 and nu = 1/8.

Density-induced interchange of anisotropy axes at half-filled high Landau levels

We observe density-induced 90 degrees rotations of the anisotropy axes in transport measurements at half-filled high Landau levels in the two dimensional electron system, where stripe states are proposed ( nu = 9/2, 11/2, etc.). Using a field effect transistor, we find the transition density to be 2.9x10(11) cm(-2) at nu = 9/2. Hysteresis is observed in the vicinity of the transition. We construct a phase boundary in the filling factor magnetic field plane in the regime 4.4<nu<4.6. An in-plane magnetic field applied along either anisotropy axis always stabilizes the low density orientation of the stripes.

X-ray photoelectron spectroscopy study of disordering in Gd2(Ti1-xZrx)2O7 pyrochlores

The dramatic increases in ionic conductivity in Gd2(Ti1-xZrx)2O7 solid solution are related to disordering on the cation and anion lattices. Disordering in Gd2(Ti1-xZrx)2O7 was characterized using x-ray photoelectron spectroscopy (XPS). As Zr substitutes for Ti in Gd2Ti2O7 to form Gd2(Ti1-xZrx)2O7 (0.25 < x < or =0.75), the corresponding O 1s XPS spectrum merges into a single symmetric peak. This confirms that the cation antisite disorder occurs simultaneously with anion disorder. Furthermore, the O 1s XPS spectrum of Gd2Zr2O7 experimentally suggests the formation of a split vacancy.

Involvement of the fungal nuclear migration gene nudC human homolog in cell proliferation and mitotic spindle formation

Essential genes which are required for normal nuclear migration and play a role in developmental processes have been isolated from model genetic organisms. One such gene is nudC (nuclear distribution C), which is required for positioning nuclei in the cytoplasm of the filamentous fungus Aspergillus nidulans and for normal colony growth. This gene is highly conserved, structurally and functionally, throughout evolution and the human homolog, HnudC, has been cloned. To study the function of nudC in higher eukaryotic cells, HnudC was downregulated by developing triple ribozyme constructs, consisting of two cis-acting ribozymes which liberate an internal trans-acting ribozyme targeted to HnudC. Efficient cleavage sites in HnudC mRNA were identified using a library selection technique and HnudC-targeted internal ribozymes were cloned into a triple ribozyme cassette. Triple ribozyme constructs were subcloned into an ecdysone-inducible expression vector and stably transfected into human embryonic 293 cells. Muristerone A induced expression of the HnudC ribozyme and produced specific reduction of HnudC mRNA. Downregulation of HnudC mRNA resulted in significant inhibition of cell proliferation in clones expressing the HnudC-targeted triple ribozyme, which was not observed in uninduced cells or cells transfected with vector alone. In induced cultures, many mitotic cells demonstrated defects in spindle architecture during mitosis. The most common defect observed was multiple mitotic spindle poles rather than the expected bipolar structure. These data demonstrate the fundamental importance of HnudC in eukaryotic cell proliferation and a functional role for HnudC in spindle formation at mitosis.

A multiple imputation approach to regression analysis for doubly censored data with application to AIDS studies

Sun, Liao, and Pagano (1999) proposed an interesting estimating equation approach to Cox regression with doubly censored data. Here we point out that a modification of their proposal leads to a multiple imputation approach, where the double censoring is reduced to single censoring by imputing for the censored initiating times. For each imputed data set one can take advantage of many existing techniques and software for singly censored data. Under the general framework of multiple imputation, the proposed method is simple to implement and can accommodate modeling issues such as model checking, which has not been adequately discussed previously in the literature for doubly censored data. Here we illustrate our method with an application to a formal goodness-of-fit test and a graphical check for the proportional hazards model for doubly censored data. We reanalyze a well-known AIDS data set.

Validity of multiple-time regression analysis in measurement of tritiated and iodinated leptin crossing the blood-brain barrier: meaningful controls

Multiple-time regression analysis has been used to study the influx of radiolabeled peptides and polypeptides across the blood-brain barrier (BBB). This study used both tritiated and iodinated leptin to clarify several issues associated with these measurements. Recombinant murine leptin was radiolabeled with 3H by derivatization or with 125I by the iodobead method and each studied separately in mice. Intact 3H-leptin had a higher apparent influx rate from blood to brain than did intact 125I-leptin, correlating with its higher proportion of reversible association with the capillary lumen that would misleadingly appear to reflect entry. Yet the majority of 3H-leptin and 125I-leptin reached brain parenchyma. There was no significant difference in the influx rate between cerebral cortex and the subcortical regions, thus ruling out a predominant contribution of simple diffusion through the circumventricular organs or choroid plexuses outside the BBB. The influx of radiolabeled leptin, especially 125I-leptin, was decreased by excess unlabeled leptin, supporting the presence of a saturable transport system for leptin at the BBB. To identify the specificity of the transport system and determine whether it is shared by 3H-leptin and 125I-leptin, these radioactively labeled leptins were heat-denatured. Denaturation had no effect on the fast influx of 3H-leptin, but abolished the entry of 125I-leptin into brain; excess denatured leptin failed to inhibit the influx of either 3H-leptin or 125I-leptin. This indicates that the conformation of 125I-leptin is similar to that of native unlabeled leptin, so that iodination would be the better choice for investigating the interaction of leptin with the BBB. However, 3H-leptin can use the same transport system, as shown by inhibition of its influx by unlabeled leptin, whereas the derivatization procedure altered its biophysical properties such that its non-saturated influx was greatly enhanced. Finally, the rapid influx of radioactively labeled leptin contrasted greatly with that of the reference compounds 99mTc-albumin and 3H-inulin which had no significant penetration of the BBB. Thus, with additional considerations such as stability and interactions with the vasculature, multiple-time regression analysis is sensitive and selective for study of the penetration of peptides across the BBB.

Effects of peptides on animal and human behavior: a review of studies published in the first twenty years of the journal Peptides

This review catalogs effects of peptides on various aspects of animal and human behavior as published in the journal Peptides in its first twenty years. Topics covered include: activity levels, addiction behavior, ingestive behaviors, learning and memory-based behaviors, nociceptive behaviors, social and sexual behavior, and stereotyped and other behaviors. There are separate tables for these behaviors and a short introduction for each section.

Preparation and incorporation of probe-labeled apoA-I for fluorescence resonance energy transfer studies of rHDL

Apolipoprotein A-I (apoA-I), the major constituent of HDL, plays an essential role in regulating cholesterol metabolism, acting as the physiological activator of lecithin: cholesterol acyltransferase, which converts cholesterol to cholesterol ester. Thiol-reactive fluorescent probes attached to cysteine-containing apoA-I mutants are currently being used to investigate the "LCAT active" conformation of lipid-bound apoA-I. Herein, we report new methodologies allowing rapid expression, fluorescent labeling, and recombinant HDL (rHDL) preparation for use in apoA-I in fluorescence resonance energy transfer (FRET) studies. Cysteine-containing mutant forms of human apoA-I were cloned into the pTYB12 vector containing a T7 promoter, a modified self-splicing protein element (intein), and a small affinity tag [chitin binding domain (CBD)]. The fusion proteins were expressed in Escherichia coli, isolated from cell lysates, and bound to a chitin-affinity column. Release of mature human apoA-I was initiated by the addition of DTT, which induced self-cleavage at the COOH terminus of the intein - CBD fusion protein. ApoA-I was further purified by Q-sepharose and then used for fluorescent probe labeling. Discoidal rHDL were then prepared with donor and/or acceptor labeled apoA-I and characterized with respect to their size, composition and ability to activate LCAT.

Graphical model checking with correlated response data

Correlated response data arise often in biomedical studies. The generalized estimation equation (GEE) approach is widely used in regression analysis for such data. However, there are few methods available to check the adequacy of regression models in GEE. In this paper, a graphical method is proposed based on Cook and Weisberg's marginal model plot. A bootstrap method is applied to obtain the reference band to assess statistical uncertainties in comparing two marginal mean functions. We also propose using the generalized additive model (GAM) in a similar fashion. The proposed two methods are easy to implement by taking advantage of existing smoothing and GAM softwares for independent data. The usefulness of the methodology is demonstrated through application to a correlated binary data set drawn from a clinical trial, the Lung Health Study.

Upregulation of the transport system for TNFalpha at the blood-brain barrier

The transport system for the cytokine tumor necrosis factor-alpha (TNFalpha) at the blood-brain barrier (BBB) enables an enhanced yet saturable entry of TNFalpha from blood to the CNS. This review focuses on the selective upregulation of the transport system for TNFalpha at the BBB that is specific for type of pathology, region, and time. The upregulation is reflected by increased CNS tissue uptake of radiolabeled TNFalpha after iv injection in mice and by inhibition of this increase with excess non-radiolabeled TNFalpha. (1) Spinal cord injury (SCI): upregulation of TNFalpha uptake after thoracic transection is seen in the delayed phase of BBB disruption at the lumbar spinal cord. Thoracic SCI by compression, however, has a longer lasting impact on TNFalpha transport that involves thoracic and lumbar spinal cord, in contrast to the upregulation confined to the lumbar region in lumbar SCI by compression. Regardless, the uptake of TNFalpha by spinal cord does not parallel BBB disruption as measured by the leakage of radiolabeled albumin. (2) Experimental autoimmune encephalomyelitis (EAE): the increase in the differential permeability to TNFalpha is seen in all CNS regions (brain and cervical, thoracic, and lumbar spinal cord) and has a distinct time course and reversibility. Exogenous TNFalpha has biphasic effects in modulating functional scores. The BBB, a dynamically regulated barrier, is actively involved in disease processes.

FUP1, a gene associated with hepatocellular carcinoma, stimulates NIH3T3 cell proliferation and tumor formation in nude mice

Human primary hepatocellular carcinoma (HCC)is one of the highly prevalent malignant diseases worldwide, the identification of HCC-associated genes has been a major approach in elucidating the molecular mechanism of tumorigenesis of HCC. In our previous studies, a function-unknown gene, which displayed marked expression difference between the HCC sample and normal liver control has been detected by cDNA microarray. This gene was named after fup1 (function-unknown protein 1), and was cloned according to the data of GenBank. The cDNA of fup1 has an open-reading frame 1233 base pairs in size. Here, the function analysis of FUP1 related to HCC is being reported. The NIH3T3 cells transiently transfected with FLAG-conjugated FUP1 revealed strong nuclear staining in immunofluorescent assay. Furthermore, cell proliferation enhancing activity of fup1 was shown by MTT assay in stable transfectant NIH3T3 cell line with pcDNA3-derived plasmid having fup1 under the regulation of pCMV, while cell proliferation repressing activity of antisense fup1 was observed in BEL7404 stable transfectant cells. Tumorigenicity of the above stable transfectant cells was analyzed in nude mice compared with appropriate controls. The result was in good agreement with MTT assay. Elevated tumorigenicity of fup1 transfected NIH3T3 cell and repressed tumorigenicity of antisense fup1 transfected BEL7404 cell were clearly demonstrated. The results above suggested that fup1 might be a critical gene related to carcinogenesis of HCC. Detailed molecular function of fup1 remains to be elucidated.

Regulation of GH secretion in acromegaly: reproducibility of daily GH profiles and attenuated negative feedback by IGF-I

GH hypersecretion is a hallmark of acromegaly. It is unknown whether the secretory activity of somatotroph adenoma is autonomous or is still governed by central or peripheral mechanisms. In this study we investigated whether GH secretion in acromegaly 1) has a reproducible circadian pattern and 2) is inhibited by exogenous IGF-I. Eleven patients with newly diagnosed acromegaly were studied in 2 protocols. In protocol 1, peripheral blood was sampled every 10 min for 48 h in 6 patients for the determination of concordance between 24-h GH profiles. There was no significant day to day variability in mean 24-h output. There was, however, a significant time effect, and the 24-h GH secretion pattern was maintained between days. In protocol 2, 5 patients were sampled for GH every 10 min twice, once during infusion of normal saline and once during iv infusion of recombinant human IGF-I (10 microg/kg x h). The recombinant human IGF-I infusion increased plasma IGF-I to approximately 230% of the baseline concentration. This resulted in GH suppression (4220 +/- 1950 vs. 3223 +/- 1472 microg/liter.min; P = 0.001), but did not alter GH secretion pattern. There were highly significant cross-correlations for 10 of the 11 of the subjects in the two protocols when the lag was 0 min. By harmonic analysis, nocturnal augmentation of GH was maintained, and maximum daily GH occurred at approximately 2300 h. These data demonstrate that the pattern of GH secretion in acromegaly is not random, but is highly preserved with 24-h periodicity. In addition, negative feedback regulation by IGF-I is preserved, although the degree of negative feedback is grossly attenuated. Thus, secretory activity of somatotroph adenomas is not autonomous or haphazard, but is still subject to both feedback and feedforward regulatory mechanisms.

[Identification of the genome of a picornavirus isolate using Random-PCR]

OBJECTIVE

To identify the genome of an enterovirus isolate (XJ90).

METHODS

The double-stranded cDNA of isolated virus was synthesized with anchored-random primer and was amplified with anchor primer; the PCR products were cloned into pGEM-T vector for sequencing and analysis.

RESULTS

Analysis on agarose gel electrophoresis of the Random-PCR products showed a typical smear; 11 randomly selected clones were all homologous to the members of enteroviruses and the homology rate over 80%; the 11 clones were distributed evenly along the whole genome and they assembled 4 contigs totally 2 261 bp long which covered 30% of the genome. The homology of the fourth contig and coxsackie virus B6 was 97.3% at amino acids level. The virus gene was specifically amplified with primers derived from the sequenced clones.

CONCLUSIONS

The picornavirus isolate XJ90 is a member of enteroviruses.

[The effects of gut -- origin lipopolysaccharide translocation on the apoptosis of lymphocytes in scalded rats]

OBJECTIVE

To investigate the relationship between lymphocyte apoptosis in spleen and mesenteric lymph nodes (MLNs) and gut -- origin lipopolysaccharide (LPS) translocation after severe scalding in rats.

METHODS

Wistar rats inflicted 30% TBSA III degree scalding were employed as the model. Serum LPS levels in portal vein and vena cava were determined by limulus amebocyte lysate (LAL) test. Apoptotic lymphocytes in paraffin -- embedded spleen and MLNs sections were detected with TdT -- mediated and dUTP nick end labeling (TUNEL) and peroxidase (POD) staining. The images were taken by cooldccd camera system, and the count and optical density (OD) value of apoptotic lymphocytes were analyzed with software Spot and Imagine proplus 4.10a (IPP4.10a).

RESULTS

Serum LPS levels in portal vein and vena cava increased sharply in rats postburn (P < 0.01) and reached a peak value at 6 postburn hour (PBH). LPS level in portal vein was higher than that in vena cava (P < 0.01) in the period of 3 to 48 PBHs. The results of TUNEL -- POD staining and the count of apoptotic lymphocytes showed that the apoptotic cells were few in normal MLNs, but increased obviously postburn (P < 0.01), especially at 3 PBH. On the contrary, apoptotic lymphocytes were concentrated in spleen cortex before injury and decreased obviously postburn (P < 0.01), though a slight recovery was found after 24 PBH. Optical density of apoptotic lymphocytes was significantly reduced in spleen at 24 PBH, But the OD value of apoptotic lymphocytes in MLNs increased significantly within 48 PBHs when compared with that before injury (P < 0.01).

CONCLUSION

Gut -- origin endotoxemia in rat could occur in early postburn period. The LPS translocation might induce lymphocyte apoptosis in MLNs. The decreased apoptotic lymphocytes in spleen implied abnormal immune function in spleen.

Increase in TNFalpha transport after SCI is specific for time, region, and type of lesion

The dynamic changes of the blood-brain barrier and blood-spinal cord barrier (BBB) are an important part of the CNS response to injury. This study addresses the permeability of the BBB in the acute phase of spinal cord injury (SCI) to the thoracic region. SCI by compression or by complete transection was generated in mice. BBB disruption was evaluated by spinal cord uptake of radiolabeled albumin. The BBB of the thoracic spinal cord was disrupted immediately after compression injury, lasting for 2 days. This was followed by a delayed permeability increase in the cervical spinal cord beginning 3 days after injury. After transection, BBB disruption was limited to the thoracic spinal cord and was present only immediately postinjury. The entry of TNFalpha not only was increased at the time of BBB disruption, following the same pattern, but also had secondary changes after the BBB permeability to albumin had returned to normal. The increase of TNFalpha entry, best explained by upregulation of the specific transport system for TNFalpha, was pronounced in the lumbar spinal cord as well as the thoracic region, and followed a different time course after the two types of injury. Integrating our results with those of the literature regarding the roles of inflammatory responses and the effects of TNFalpha in spinal cord regeneration, we conclude that the time-, region-, and lesion-specificity of the upregulation of TNFalpha transport is part of the regulatory changes at the BBB in response to SCI.

Bradykinin antagonist decreases early disruption of the blood-spinal cord barrier after spinal cord injury in mice

Bradykinin is one of the key molecules involved in the disruption of the blood-brain barrier and blood-spinal cord barrier occurring after spinal cord injury (SCI). Previously we have shown a biphasic opening of the blood-spinal cord barrier as well as increased transport of tumor necrosis factor-alpha (TNFalpha) after SCI by compression of the lumbar spinal cord in mice. To evaluate the role of bradykinin in the two phases of blood-spinal cord barrier disruption, we pretreated mice with a potent bradykinin antagonist, the decapeptide B9430, before SCI. Our results show that B9430 decreased the general blood-spinal cord barrier disruption occurring immediately after SCI but failed to affect the delayed opening of the blood-spinal cord barrier observed 72 h after SCI. By contrast, the entry of TNFalpha after SCI was not affected by B9430 treatment. We conclude that bradykinin is involved in the early phase of blood-spinal cord barrier disruption, with B9430 non-selectively blocking this early disruption without affecting the selective transport system for TNFalpha. This indicates the therapeutic potential of bradykinin antagonists in ameliorating tissue damage induced by SCI.

[Construction of Cryptococcus neoformans cap70 transformation system]

OBJECTIVE

To construct a transformation system of Cryptococcus neoformans capsule-deficient strain cap70.

METHODS

(1)Obtained ura5 mutants by screening the Cryptococcus neoformans cap70 using 5-fluoroorotic acid counter selection method, analyzed the obtaining strain by Southern blot and PCR; (2)Through the plasmid pCXJ18 and pCXJU which contained ura5 gene from Cryptococcus neoformans and ura3 from Kluyveromyces fragilils. as a selective marker, the ura5 strains were transformed by electrotransformation and chemical transformation.

RESULTS

Obtained ura5 mutants, they were detected as lack of ura function. The chemical transformation method was first be used in Cryptococcus neoformans transformation.

CONCLUSION

A transformation system of Cryptococcus neoformans cap70 has been established, which provides not only the basis for gene cloning from the species for studying gene function and gene expression.

A multiple imputation approach to linear regression with clustered censored data

We extend Wei and Tanner's (1991) multiple imputation approach in semi-parametric linear regression for univariate censored data to clustered censored data. The main idea is to iterate the following two steps: 1) using the data augmentation to impute for censored failure times; 2) fitting a linear model with imputed complete data, which takes into consideration of clustering among failure times. In particular, we propose using the generalized estimating equations (GEE) or a linear mixed-effects model to implement the second step. Through simulation studies our proposal compares favorably to the independence approach (Lee et al., 1993), which ignores the within-cluster correlation in estimating the regression coefficient. Our proposal is easy to implement by using existing softwares.

Sample size and power calculations with correlated binary data

Correlated binary data are common in biomedical studies. Such data can be analyzed using Liang and Zeger's generalized estimating equations (GEE) approach. An attractive point of the GEE approach is that one can use a misspecified working correlation matrix, such as the working independence model (i.e., the identity matrix), and draw (asymptotically) valid statistical inference by using the so-called robust or sandwich variance estimator. In this article we derive some explicit formulas for sample size and power calculations under various common situations. The given formulas are based on using the robust variance estimator in GEE. We believe that these formulas will facilitate the practice in planning two-arm clinical trials with correlated binary outcome data.

Model selection in estimating equations

Model selection is a necessary step in many practical regression analyses. But for methods based on estimating equations, such as the quasi-likelihood and generalized estimating equation (GEE) approaches, there seem to be few well-studied model selection techniques. In this article, we propose a new model selection criterion that minimizes the expected predictive bias (EPB) of estimating equations. A bootstrap smoothed cross-validation (BCV) estimate of EPB is presented and its performance is assessed via simulation for overdispersed generalized linear models. For illustration, the method is applied to a real data set taken from a study of the development of ewe embryos.

Diurnal variation of leptin entry from blood to brain involving partial saturation of the transport system

The blood-brain barrier (BBB) regulates the amount of peripherally produced leptin reaching the brain. Knowing that the blood concentration of leptin has a circadian rhythm, we investigated whether the influx of leptin at the BBB followed the same pattern in three main sets of experiments. (a): The entry of 125I-leptin from blood to brain was measured in mice every 4 h, as indicated by the influx rate of 125I-leptin 1-10 min after an iv bolus injection. The blood concentration of endogenous leptin was measured at the same times. Blood leptin concentrations were higher at night and early morning (peak at 0800 h) and lower during the day (nadir at 1600 h). By contrast, the influx of 125I-leptin was fastest at 2000 h and slowest at 0400 h. Addition of unlabeled leptin (1 microg/mouse) significantly decreased the influx rate of 125I-leptin at all time points, indicating saturability of the transport system. The unlabeled leptin also abolished the diurnal variation of the influx of 125I-leptin. (b): The entry of 125I-leptin into spinal cord was faster than that into brain and showed a different diurnal pattern. The greatest influx occurred at 2400 h and the slowest at 0800 h. In spinal cord, unlike brain, unlabeled leptin (1 microg/mouse) neither inhibited the influx of 125I-leptin nor abolished the diurnal rhythm. (c): Higher concentrations of unlabeled leptin (5 microg/mouse) inhibited the uptake of 125I-leptin in spinal cord as well as in brain, but not in muscle. This experiment measured uptake 10 min after iv injection at 0600 h (beginning of the light cycle) and 1800 h (beginning of the dark cycle). Thus, influx of 125I-leptin into the CNS shows diurnal variation, indicating a circadian rhythm in the transport system at the BBB, saturation of the leptin transport system shows differences between the brain and spinal cord, and blood concentrations of leptin suggest that partial saturation of the transport system occurs at physiological concentrations of circulating leptin, contributing to the differing diurnal patterns in brain and spinal cord. Together, the results show that the BBB is actively involved in the neuroendocrine regulation of feeding behavior.

Inhalable dust exposures, tasks, and use of ventilation in small woodworking shops: a pilot study

Measures of workers' inhalable dust exposures, tasks, and ventilation use were made in five small woodworking shops prior to the start of an intervention effectiveness study aimed at lowering personal wood dust exposures. The data were used to (1) design a sampling protocol for an intervention success measure, (2) identify targets for intervention among the tasks and activities responsible for high dust levels, and (3) develop shop-level measures as tools for tailoring intervention activities. Geometric mean dust concentrations ranged from 1.6 to 9.9 mg/m3 in the five shops, with the highest levels occurring in a cabinet shop. All shops had centralized dust collection systems and workers generally used dust control on stationary tools (60-100% of the time) when it was available. Sanding with both stationary and handheld powered tools, cleaning with methods that can disperse dust (e.g., brushes, compressed air), and miscellaneous tasks were all responsible for significant personal exposures. The positive association between miscellaneous tasks and exposures probably reflects the high background levels generated by nearby processes. Sanding with both stationary tools and handheld powered tools represents the most significant influence on personal exposures in small woodworking shops. The authors conclude that pilot studies are useful tools for designing occupational health and safety intervention effectiveness studies.

Involving AP-2 transcription factor in connexin 26 up-regulation during pregnancy and lactation

Gap junction connexin 26 (Cx26) is up-regulated in mammary epithelial cells during pregnancy and lactation. To understand the transcriptional regulation of Cx26, we identified a protected DNase I footprint region (-140 to -113) in the rat Cx26 promoter. This rCx26 Promoter Footprinting Region, or CPFR, contains an Sp binding site (CCGCCC) overlapping with an AP-2 binding site (GCCCGCGGC), and is evolutionarily conserved. Nuclear extracts from rat mammary glands and human MCF-10 mammary epithelial cells formed protein-DNA complexes with the labeled CPFR probe in the electrophoretic mobility shift assay (EMSA), and these complexes were markedly enhanced during pregnancy and lactation. Antibody supershift analysis further identified the presence of Sp1, Sp3, and AP-2 in these binding complexes. Human mammary epithelial MCF-10A and MCF-12A cells were transiently transfected with chimeric mutant rCx26 promoter/luciferase reporter constructs, and luciferase activities measured. Mutations along the CPFR fragment drastically reduced the promoter activity, specially at the Sp/AP-2 overlapping site. Cotransfection of AP-2 with rCx26 promoter/reporter constructs into MCF-10 cells markedly induced the reporter activity. These data infer that AP-2, along with previously reported Sp transcription factors, is involved in the up-regulation of Cx26 gene during pregnancy and lactation.