Phospho-ΔNp63α is a key regulator of the cisplatin-induced microRNAome in cancer cells

Head and neck squamous cell carcinoma (HNSCC) cells exposed to cisplatin (CIS) displayed a dramatic ATM-dependent phosphorylation of ΔNp63α that leads to the transcriptional regulation of downstream mRNAs. Here, we report that phospho (p)-ΔNp63α transcriptionally deregulates miRNA expression after CIS treatment. Several p-ΔNp63α-dependent microRNA species (miRNAs) were deregulated in HNSCC cells upon CIS exposure, including miR-181a, miR-519a, and miR-374a (downregulated) and miR-630 (upregulated). Deregulation of miRNA expression led to subsequent modulation of mRNA expression of several targets (TP53-S46, HIPK2, ATM, CDKN1A and 1B, CASP3, PARP1 and 2, DDIT1 and 4, BCL2 and BCL2L2, TP73, YES1, and YAP1) that are involved in the apoptotic process. Our data support the notion that miRNAs are critical downstream targets of p-ΔNp63α and mediate key pathways implicated in the response of cancer cells to chemotherapeutic drugs.

Salt supplementation blunts the blood pressure response to telmisartan with or without hydrochlorothiazide in hypertensive patients with type 2 diabetes

AIMS/HYPOTHESIS

We assessed the effects of sodium chloride (NaCl) supplementation on the blood pressure response to treatment with telmisartan with or without hydrochlorothiazide in hypertensive patients with type 2 diabetes and habitually high (HDS, sodium excretion >200 mmol/24 h on two out of three consecutive occasions) or low (LDS, sodium excretion <100 mmol/24 h on two out of three consecutive occasions) salt intake.

METHODS

Patients received 4 weeks of telmisartan followed by 4 weeks of telmisartan plus hydrochlorothiazide. In a double-blind randomised fashion, patients received sodium chloride (NaCl, 100 mmol/24 h) or placebo capsules in addition to their habitual salt intake during the last 2 weeks of telmisartan and telmisartan plus hydrochlorothiazide therapy. The protocol was repeated with NaCl and placebo capsules administered in reverse order to allow each participant to act as his or her own control. At 0, 4, 8, 14, 18 and 22 weeks, 24 h ambulatory blood pressure (ABP) and 24 h urine collections were performed.

RESULTS

No statistically significant differences were seen in the ABP response in the LDS vs HDS groups to any of the interventions (p = 0.58). NaCl supplementation reduced the effect of telmisartan with or without hydrochlorothiazide on systolic BP by approximately 50% (-5.8 mmHg during NaCl supplementation vs -11.3 mmHg during placebo, mean difference 5.6 mmHg [95% CI 1.7-9.4 mmHg], p = 0.005), irrespective of habitual salt intake. By contrast, addition of hydrochlorothiazide increased the antihypertensive effect of telmisartan on systolic BP by approximately 35% (p = 0.048) in both groups of patients.

CONCLUSIONS/INTERPRETATION

NaCl supplementation blunts the effectiveness of telmisartan with or without hydrochlorothiazide in hypertensive patients with type 2 diabetes, independently of habitual low or high salt intake.

Osmotic Swelling Pressure Response of Smart Hydrogels Suitable for Chronically-Implantable Glucose Sensors

In the last few years, a new type of glucose-sensitive hydrogel (GSH) has been developed that shrinks with increasing glucose concentration due to the formation of reversible crosslinks The first osmotic swelling pressure results measured for any member of this new class of GSH are reported, so that their suitability for use in sensors combining pressure transducers and smart gels can be evaluated. Comparison is also made with results obtained for an older type of GSH that expands with increasing glucose concentration due to an increase in the concentration of counterions within the gel. The newer type of GSH exhibits both faster kinetics and weaker fructose interference, and therefore is more suitable for in vivo glucose sensing.

A mouse model of a human multiple GIST family with KIT-Asp820Tyr mutation generated by a knock-in strategy

Several families exhibiting multiple gastrointestinal stromal tumours (GISTs) and germline c-kit gene mutations at exons 8, 11, 13, or 17 have been reported. These patients also exhibit diffuse hyperplasia of the interstitial cells of Cajal (ICCs) as a pre-existing lesion of multiple GISTs. We generated a mouse model of a family with germline c-kit gene mutation at exon 17, and compared the phenotypes between the mice and humans. The mouse counterpart (KIT-Asp818Tyr) of the human KIT-Asp820Tyr mutation was transmitted into germline by a knock-in strategy. Mating of male and female heterozygotes (KIT-Asp818Tyr/+) resulted in the generation of homozygotes (KIT-Asp818Tyr/KIT-Asp818Tyr). Histological examination revealed that all heterozygotes had both a small KIT-positive mesenchymal tumour at the caecum, consistent with GIST, and KIT-positive diffuse spindle-shaped cell proliferation in the distal oesophagus, stomach, proximal duodenum, and colon consistent with ICC hyperplasia. All homozygotes exhibited a larger caecal tumour and more prominent spindle-shaped cell proliferation compared with the heterozygous mice, and they usually died within 10 weeks after birth, likely due to ileus. The small intestine of both genotypes showed no apparent morphological abnormality, and autonomous contraction of the ileal segments appeared normal. Western blotting demonstrated that the caecal tumours expressed phosphorylated KIT, MAPK, Stat1, and Stat5. These mutant mice are considered to be useful for further investigation of the mechanism of GIST development as a result of ICC hyperplasia and for assessment of the in vivo effects of drugs against molecular targets.

MAPK/ERK signalling mediates VEGF-induced bone marrow stem cell differentiation into endothelial cell

Multi-potent adult progenitor cells (MAPCs) differentiate into endothelial cells (ECs) in the presence of vascular endothelial growth factor (VEGF). The mechanism(s) of VEGF-induced differentiation of MAPCs to ECs are not yet known. We, therefore, examined the role of mitogen-activated protein kinase/extracellular signal-regulated kinase (p42/44-MAPK/ERK1/2) signalling in endothelial differentiation from bone marrow stem cells. We observed that VEGF stimulation of MAPCs for 14 days results in a significant expression of endothelial-specific gene and/or proteins including von Willebrand factor (vWF), vascular endothelial-cadherin (VE-cadherin), VEGF receptor-2 (VEGFR2), and CD31. Up-regulation of EC-specific markers was accompanied by a cobblestone morphology, expression of endothelial nitric oxide synthase (eNOS), and Dil-Ac-LDL uptake, typical for EC morphology and function. VEGF induced a sustained activation of p42 MAPK/ERK, but not that of p44 MAPK/ERK during the course of MAPCs differentiation in a time-dependent manner up to 14 days. VEGF-induced activation of p42 MAPK/ERK also led to the nuclear translocation of MAPK/ERK1/2. Incubation of MAPCs with MAPK/ERK1/2 phosphorylation inhibitor PD98059 blocked the sustained VEGF-induced MAPK/ERK1/2 phosphorylation as well as its nuclear translocation in the differentiating MAPCs. Inhibition of MAPK/ERK1/2 phosphorylation by PD98059 also blocked the expression of EC-specific genes in these cells and their differentiation to ECs. These data suggest that VEGF induces MAPC differentiation into EC via a. MAPK/ERK1/2 signalling pathway-mediated mechanism in vitro.

Estrogen-induced and TAFII30-mediated gene repression by direct recruitment of the estrogen receptor and co-repressors to the core promoter and its reversal by tamoxifen

Estradiol (E2) acts through the estrogen receptor (ER) to downregulate many genes, and tamoxifen (Tam) largely reverses this repression but the underlying mechanisms are unclear. Repression of the folate receptor (FR)-alpha P4 core promoter by ER is enhanced by E2 and reversed by Tam. This effect was unaffected by inhibition of new protein synthesis and required the E/F and the DNA-binding domains of ER without direct binding of ER to DNA. The repression by E2/ER was not specific for either Sp1 or TATA elements but was loosely selective for the initiator and flanking sequence. Insertion of a response element or a relatively strong Sp1 cluster to recruit ER upstream of the core promoters caused a switch to activation by E2/ER that was inhibited by Tam. In nuclear extracts, association of ER with a biotinylated core promoter fragment was promoted by E2 but Tam blocked this effect. Repression/de-repression of the P4 promoter and endogenous FR-alpha expression by E2/Tam required SMRT and/or NCoR. ER associated with the chromosomal P4 promoter and SMRT and NCoR associated with it in an ER-dependent manner; these associations were favored by E2 but disrupted by Tam, in the short term, without changes in ER expression. TAFII30 was required for optimal P4 promoter activity and for the repressive association of ER. E2 may thus maintain a low transcriptional status of genes by favoring direct TAFII30-dependent association of ER with the core promoter in a co-repressor complex containing SMRT and/or NCoR; this repression is overridden in target genes containing an upstream element that strongly recruits ER. In addition to suppressing the activation of classical E2 target genes, Tam may upregulate genes by passively dissociating the ER co-repressor complex.

Short-interfering RNA-mediated silencing of proliferating cell nuclear antigen inhibit proliferation and induce apoptosis in HeLa cells

Proliferating cell nuclear antigen (PCNA) is an important protein for DNA polymerase delta in the nucleus, and shown to have a fundamental role in cellular proliferation. It is overexpressed to support cell growth in cervical carcinoma. To study its role in stress response, we design and use short hairpin RNA (shRNA) to inhibit PCNA expression in HeLa cells and validate its effect on cell proliferation. In this study, three PCNA-shRNA expression vectors are constructed and introduced into HeLa cells, and the cell cycle is analyzed by flow cytometry. Apoptotic cell is detected by single cell gel electrophoresis assay (comet assay), and caspase cleavage is studied also. Expression of PCNA is assessed by real-time reverse transcription-polymerase chain reaction and Western blot analysis. Upon transient transfection with plasmid encoding shRNA, it is found that expression of PCNA decreased in shRNA-transfected cells, downregulation of PCNA inhibit cell growth and induce apoptosis in HeLa cells. PCNA downregulation also increase cell population in the G0-G1 phase. In conclusion, our findings demonstrate that shRNA can inhibit the DNA replication and induce apoptosis in HeLa cells effectively and, therefore, could be used as a new potential anticancer tool for therapy of human cervical carcinoma.

The recombinant nonstructural polyprotein NS1 of porcine parvovirus (PPV) as diagnostic antigen in ELISA to differentiate infected from vaccinated pigs

To differentiate pigs infected with porcine parvovirus (PPV) from those vaccinated with inactivated whole-virus vaccine, an enzyme-linked immunosorbent assay (ELISA) based on detection of a nonstructural polyprotein 1 (NS1) was developed. A threshold of 0.23 optical density units was established and the assay had high specificity (100), sensitivity (88), accuracy (90) and positive predictive value (100) using haemagglutination inhibition as the standard method. A reproducibility test revealed that the coefficients of variation of sera within-plates and between-run were less than 10%. The assay showed no cross-reactivity with antibodies to porcine reproductive respiratory syndrome virus, pseudorabies virus, foot and mouth disease virus, Actinobacillus pleuropneumoniae, Toxoplasma or Chlamydia. Sera obtained from pigs infected with PPV reacted with recombinant NS1 protein in the ELISA. Sera from pigs vaccinated with inactivated whole virus did not recognize this protein in the ELISA. In contrast, antibodies against PPV whole virus were present in both PPV-infected and vaccinated animals. Serum conversion against NS1 was first detected 10 days after infection and NS1-specific antibodies were detectable up to half a year post infection. In conclusion, the PPV-NS1 ELISA can differentiate PPV-infected versus inactivated PPV-vaccinated pigs and could be applied in disease diagnosis and surveillance.

cisRED: a database system for genome-scale computational discovery of regulatory elements

We describe cisRED, a database for conserved regulatory elements that are identified and ranked by a genome-scale computational system (www.cisred.org). The database and high-throughput predictive pipeline are designed to address diverse target genomes in the context of rapidly evolving data resources and tools. Motifs are predicted in promoter regions using multiple discovery methods applied to sequence sets that include corresponding sequence regions from vertebrates. We estimate motif significance by applying discovery and post-processing methods to randomized sequence sets that are adaptively derived from target sequence sets, retain motifs with p-values below a threshold and identify groups of similar motifs and co-occurring motif patterns. The database offers information on atomic motifs, motif groups and patterns. It is web-accessible, and can be queried directly, downloaded or installed locally.

[Cytokine expression in effusions of secretory otitis media]

OBJECTIVE

To assess the cytokine level in effusions of secretary otitis media and it's relationship with clinical index. To further study the inflammatory mechanism of otitis media with effusion.

METHOD

The concentration of TNF-alpha and TNFsolR II was quantitatively determined using enzyme-linked immunosorbent assay and it was correlated with clinical index in otitis media with effusion using stepwise regression analysis.

RESULT

TNF-alpha and TNFsolR II was found in 100% effusions. Mean values of TNF-alpha were (3.42 +/- 2.25) ng/g total protein. Mean values of TNFsolR II were (405.80 +/- 216.53) ng/g total protein. Mean values of TNFsolR II index was (154.18 +/- 90.45) U. There was a significant decrease of TNFsolR II and TNFsolR II index in patients who recurred (P < 0.05).

CONCLUSION

Cytokine TNF-alpha and TNFsolR II are important inflammatory medium which exist in all otitis media effusions. The decrease of the level of TNFsolR II and TNFsolR II index present significantly in middle ear effusions with recurrence, but there is no any relation of TNF-alpha in middle ear effusions with recurrence.

Specific sequences outside the E-box are required for proper per expression and behavioral rescue

A 69 bp circadian regulatory sequence (CRS) upstream of the per gene is sufficient to drive circadian transcription, mediate proper spatial expression, and rescue behavioral rhythmicity in per01 flies. Within the CRS, an E-box is required for transcriptional activation by two basic-helix-loop-helix (bHLH) PERARNT-SIM (PAS) transcription factors, dCLOCK (dCLK) and CYCLE (CYC). To define sequences within the CRS that are required for spatial expression, circadian expression, and behavioral rhythmicity, a series of mutants that alter blocks of 3 to 12 nucleotides across the entire CRS were used to drive lacZ or per expression in vivo. As expected, the E-box within the CRS is necessary for high-level expression and behavioral rhythmicity, but sequences outside the E-box are also required for transcriptional activation, proper spatial expression, and behavioral rhythmicity. These results indicate that the dCLK-CYC target site extends beyond the E-box and that factors other than dCLK and CYC modulate per transcription.

Bleomycin-induced pulmonary fibrosis is independent of eosinophils

Eosinophils have been shown to increase in tissues during many fibrotic conditions and consequently have been suggested to contribute to the development of fibrosis. This study tested the hypothesis that eosinophils are essential in the development of lung fibrosis in mice in response to bleomycin (BLM). Anti-IL-5 antibody was administered intraperitoneally into mice 2 h prior to endotracheal BLM inoculation and thereafter, every other day. Lung eosinophilia was evaluated by measurement of eosinophil peroxidase activity and confirmed by eosinophil counts in histologic sections. Lung fibrosis was evaluated by hydroxyproline content and confirmed by collagen staining in histological sections. Results demonstrated that BLM induced pronounced lung eosinophilia, which was maximal 7 days after BLM treatment and remained elevated through day 14, in C57B1/6 SCID mice and CBA/J mice. In contrast, eosinophilia was a minor component in the lungs of wildtype C57B1/6 mice after BLM treatment, although lung fibrosis developed similarly in all three strains of mice. Treatment with anti-IL-5 completely abrogated eosinophilia but failed to block pulmonary fibrosis induced by BLM in all mouse strains, including C57B1/6 SCID, wildtype C57B1/6 mice, and CBA/J mice. Analysis of cytokine mRNA by RNase-protection assay in C57B1/6 SCID mice indicated that BLM treatment caused enhanced expression of the cytokines, TNF-alpha, and IL-6 at days 3, 7, and 14 post-BLM inoculation, regardless of whether eosinophils were depleted by anti-IL-5. Finally, the importance of eosinophils in lung fibrosis was examined in IL-5 gene knockout mice (IL-5tm1Kopf). BLM treatment induced significant lung fibrosis in IL-5 knockout mice in the absence of eosinophilia. These findings indicate that eosinophils are not an absolute requirement for BLM-induced pulmonary fibrosis in the mouse.

Melatonin does not shift circadian phase in baboons

It has been suggested that the pineal hormone melatonin can modulate circadian rhythmicity and may have clinical utility in treating biological clock disorders. Thus, there is considerable clinical interest in using melatonin to treat disorders, such as jet-lag. Yet, despite growing enthusiasm for the use of melatonin, it is not clear whether melatonin indeed shifts the circadian phase in humans and other primate species. Thus, to assess whether melatonin can influence circadian phase, we studied the phase-shifting effects of melatonin on baboons to provide insights into the role of melatonin. Mel- atonin was administered orally to baboons (0.5, 3, 5, or 10 mg) either in the early morning hours from circadian time (CT) 0 to CT3 or late in the afternoon from CT9 to CT12, and changes in circadian phase were assessed. Surprisingly, at all doses and times tested, melatonin did not shift circadian phase. Physical activity was reduced after 5- and 10-mg doses given late in the afternoon, but not after doses given early in the morning. These observations suggest that melatonin does not shift circadian phase in baboons using doses similar to those prescribed for treating human circadian system disorders.

Multiple levels of regulation of selenoprotein biosynthesis revealed from the analysis of human glioma cell lines

To gain a better understanding of the biological consequences of the exposure of tumor cells to selenium, we evaluated the selenium-dependent responses of two selenoproteins (glutathione peroxidase and the recently characterized 15-kDa selenoprotein) in three human glioma cell lines. Protein levels, mRNA levels, and the relative distribution of the two selenocysteine tRNA isoacceptors (designated mcm(5)U and mcm(5)Um) were determined for standard as well as selenium-supplemented conditions. The human malignant glioma cell lines D54, U251, and U87 were maintained in normal or selenium-supplemented (30 nM sodium selenite) conditions. Northern blot analysis demonstrated only minor increases in steady-state GSHPx-1 mRNA in response to selenium addition. Baseline glutathione peroxidase activity was 10.7 +/- 0.7, 7.6 +/- 0.7, and 4.3 +/- 0.7 nmol NADPH oxidized/min/mg protein for D54, U251, and U87, respectively, as determined by the standard coupled spectrophotometric assay. Glutathione peroxidase activity increased in a cell line-specific manner to 19.7 +/- 1.4, 15.6 +/- 2.1, and 6. 7 +/- 0.5 nmol NADPH oxidized/min/mg protein, respectively, as did a proportional increase in cellular resistance to H(2)O(2), in response to added selenium. The 15-kDa selenoprotein mRNA levels likewise remained constant despite selenium supplementation. The selenium-dependent change in distribution between the two selenocysteine tRNA isoacceptors also occurred in a cell line-specific manner. The percentage of the methylated isoacceptor, mcm(5)Um, changed from 35.5 to 47.2 for D54, from 38.1 to 47.3 for U251, and from 49.0 to 47.6 for U87. These data represent the first time that selenium-dependent changes in selenoprotein mRNA and protein levels, as well as selenocysteine tRNA distribution, were examined in human glioma cell lines.

Developing circadian rhythmicity

Circadian rhythms are endogenously generated rhythms with a period length of about 24-hours. Evidence gathered over the past decade indicates that the circadian timing system develops prenatally, and the suprachiasmatic nuclei, the site of a circadian clock, is present by midgestation in human and nonhuman primates. Recent evidence also shows that the circadian system of primate infants is responsive to light at very premature stages and that low intensity lighting can regulate the developing clock. After birth, there is progressive maturation of the circadian system outputs, with pronounced rhythms in sleep-wake and hormone secretion generally developing after 2 months of age. With the continued elucidation of circadian system development and influences on human physiology and illness, it is anticipated that consideration of circadian biology will become an increasingly important component of neonatal care.

Study of phonon dispersion in silicon and germanium at long wavelengths using picosecond ultrasonics

We have studied the dispersion of long wavelength longitudinal phonons in silicon and germanium using ultrasonic techniques. For long wavelengths, the acoustic phonon dispersion relation is of the form omega(k) approximately ck-gammak(3), where c is the speed of sound and gamma measures the lowest-order phonon dispersion. By sending an ultrasonic pulse of length a few hundred angstroms into a crystal and measuring the change of the pulse shape with propagation distance, we are able to determine the parameter gamma. The results are compared with lattice dynamics models.

Knowledge-based grouping of modeled HLA peptide complexes

Human leukocyte antigens are the most polymorphic of human genes and multiple sequence alignment shows that such polymorphisms are clustered in the functional peptide binding domains. Because of such polymorphism among the peptide binding residues, the prediction of peptides that bind to specific HLA molecules is very difficult. In recent years two different types of computer based prediction methods have been developed and both the methods have their own advantages and disadvantages. The nonavailability of allele specific binding data restricts the use of knowledge-based prediction methods for a wide range of HLA alleles. Alternatively, the modeling scheme appears to be a promising predictive tool for the selection of peptides that bind to specific HLA molecules. The scoring of the modeled HLA-peptide complexes is a major concern. The use of knowledge based rules (van der Waals clashes and solvent exposed hydrophobic residues) to distinguish binders from nonbinders is applied in the present study. The rules based on (1) number of observed atomic clashes between the modeled peptide and the HLA structure, and (2) number of solvent exposed hydrophobic residues on the modeled peptide effectively discriminate experimentally known binders from poor/nonbinders. Solved crystal complexes show no vdW Clash (vdWC) in 95% cases and no solvent exposed hydrophobic peptide residues (SEHPR) were seen in 86% cases. In our attempt to compare experimental binding data with the predicted scores by this scoring scheme, 77% of the peptides are correctly grouped as good binders with a sensitivity of 71%.

HLA alleles in patients with Guillain-Barre syndrome

OBJECTIVE

To determine whether genetic factors may work in concert with autoimmune factors in the pathogenesis of Guillain-Barre syndrome (GBS).

METHODS

We determined the differences in the distribution of HLA alleles between GBS patients and normal controls. HLA-DQA, -DQB and -DRB alleles were typed by the sequence specific primer polymerase chain reaction (PCR-SSP) methods in 47 GBS, 7 patients with Campylobacter jejuni (CJ) enteritis and 50 normal controls.

RESULTS

There were no differences in the frequency of HLA-DQA, -DQB and -DRB among GBS group, CJ group, normal controls and GBS subgroups with respect to recent CJ infection, GM1 IgG and GM1 IgM antibodies (P > 0.05). There was an increasing tendency of DQA1 * 0301 (P = 0.056, RR = 2.991) in the subgroup with GM1 IgG antibodies and DQA1 * 0302 (P = 0.087, RR = 3.587) in the subgroup with recent CJ infection. No difference was found among GBS, CJ enteritis patients and normal controls.

CONCLUSIONS

The increasing tendency of the two alleles suggests that there may be some relation between genetic factors and immunological factors, but a definite conclusion waits for more cases.

Are A3 adenosine receptors expressed in the brain?

An increasing number of reports suggest a role for A3 adenosine receptors (A3ARs) in mediating adenosine action in the central nervous system. However, studies of A3AR localization in the brain have yet to be performed. To provide insights into the central sites of A3AR action, we compared patterns of A1 and A3AR mRNA and binding site expression in the brains of rats, mice and humans. We also assessed whether A3 agonists are selective for A3ARs. Whereas it was possible to detect high-level A1AR expression in many brain regions, it was not possible to detect either A3AR gene or binding site expression in the central nervous system. When we examined the affinities of the A3AR agonists CI-IAB-MECA and IAB-MECA for A1ARs, we found that these compounds bound to A1ARs with high affinity. These observations suggest that studies using A3-agonists need to consider potential effects of A1ARs activation, as A1ARs are abundantly expressed in the nervous system whereas A3AR expression in the brain cannot be directly demonstrated.

Mechanisms of human mitochondrial DNA maintenance: the determining role of primary sequence and length over function

Although the regulation of mitochondrial DNA (mtDNA) copy number is performed by nuclear-coded factors, very little is known about the mechanisms controlling this process. We attempted to introduce nonhuman ape mtDNA into human cells harboring either no mtDNA or mutated mtDNAs (partial deletion and tRNA gene point mutation). Unexpectedly, only cells containing no mtDNA could be repopulated with nonhuman ape mtDNA. Cells containing a defective human mtDNA did not incorporate or maintain ape mtDNA and therefore died under selection for oxidative phosphorylation function. On the other hand, foreign human mtDNA was readily incorporated and maintained in these cells. The suicidal preference for self-mtDNA showed that functional parameters associated with oxidative phosphorylation are less relevant to mtDNA maintenance and copy number control than recognition of mtDNA self-determinants. Non-self-mtDNA could not be maintained into cells with mtDNA even if no selection for oxidative phosphorylation was applied. The repopulation kinetics of several mtDNA forms after severe depletion by ethidium bromide treatment showed that replication and maintenance of mtDNA in human cells are highly dependent on molecular features, because partially deleted mtDNA molecules repopulated cells significantly faster than full-length mtDNA. Taken together, our results suggest that mtDNA copy number may be controlled by competition for limiting levels of trans-acting factors that recognize primarily mtDNA molecular features. In agreement with this hypothesis, marked variations in mtDNA levels did not affect the transcription of nuclear-coded factors involved in mtDNA replication.

Relationship between pathogenesis of Guillain-Barre syndrome and Penner's serotypes of Campylobacter jejuni

OBJECTIVE

To investigate the relationship between the pathogenesis of Guillain-Barre syndrome (GBS) and Campylobacter jejuni (C. jejuni) in China.

METHODS

C. jejuni strains were isolated from fresh stools of 47 GBS patients in Beijing area from 1995 to 1997 by modified Skirrow's method. Serotyping of C. jejuni was performed with Penner's method in 47 GBS patients and 171 patients with C. jejuni enteritis in our hospital during the same period. The stools from which no C. jejuni strains could be isolated were typed by PCR-RFLP (restriction fragment length polymorphism) method.

RESULTS

Six C. jejuni strains were isolated by Skirrow's method, including 3 strains of Penner serotype 2, 1 Penner serotype 4, 1 Penner serotype 19 and 1 Penner serotype 26. Three strains of DNA-I, which was equal to the same type of Penner serotype 19, were found by PCR-RFLP method.

CONCLUSION

C. jejuni isolated from Beijing area are similar to those reported in literature, which once more confirms the molecular mimicry pathogenetic theory of GBS caused by C. jejuni infection in China. The similarities of serotypes between C. jejuni strains from GBS patients and those from C. jejuni enteritis patients may explain the high incidence of GBS following C. jejuni infection in China.

[The relationship between Guillain-Barre syndrome and serotypes of Campylobacter jejuni isolated from the patients]

OBJECTIVE

To investigate the relationship between Campylobacter jejuni (CJ) serotype and the high incidence of Guillain-Barre syndrome (GBS) following CJ enteritis in China.

METHODS

CJ was isolated from fresh stool of 47 GBS patients in Beijing area from 1995-1997 with a combination of Skirrow method and micro-filtration method. Serotyping of the CJ strains was performed with passive hemagglutination method with standard serum from CDC. 171 CJ strains from CJ enteritis in our hospital in the same period were serotyped with the same method. The stool from which no CJ could be isolated was typed with PCR-RFLP method.

RESULTS

3 Penner 2, 1 Penner 4, 1 Penner 19 and 1 Penner 26 strains were isolated and serotyped. Three strains which could not be isolated were found by PCR-RFLP method to be DNA-I, which is equivalent to the type of Penner 19. There were some CJ strains which could be typed with serum from CDC.

CONCLUSION

CJ from GBS patients in Beijing area are similar to those reported in the world; it is suggested that CJ may cause GBS by molecular mimicry mechanism in China. The most common serotype of CJ from GBS was reported to be Penner 19 in Japan, while it was rare in CJ enteritis. However, the similarity of the serotypes between CJ from GBS patients and CJ from enteritis patients may explain the high incidence of GBS following CJ infection in China. Penner 26 is reported to be isolated from GBS patients for the first time.

Suppression of a mitochondrial tRNA gene mutation phenotype associated with changes in the nuclear background

We previously have characterized a pathogenic mtDNA mutation in the tRNAAsn gene. This mutation (G5703A) was associated with a severe mitochondrial protein synthesis defect and a reduction in steady-state levels of tRNAAsn. We now show that, although transmitochondrial cybrids harboring homoplasmic levels of the mutation do not survive in galactose medium, several galactose-resistant clones could be obtained. These cell lines had restored oxidative phosphorylation function and 2-fold higher steady-state levels of tRNAAsn when compared with the parental mutant cell line. The revertant lines contained apparently homoplasmic levels of the mutation and no other detectable alteration in the tRNAAsn gene. To investigate the origin of the suppression, we transferred mtDNA from the revertants (143B/206 TK-) to a different nuclear background (143B/207 TK-, 8AGr). These new transmitochondrial cybrids became defective once again in oxidative phosphorylation and regained galactose sensitivity. However, galactose-resistant clones could also be obtained by growing the 8AGr transmitochondrial cybrids under selection. Because the original rate of reversion was higher than that expected by a classic second site nuclear mutation, and because of the aneuploid features of these cell lines, we searched for the presence of chromosomal alterations that could be associated with the revertant phenotype. These studies, however, did not reveal any gross changes. Our results suggest that modulation of the dosage or expression of unknown nuclear-coded factor(s) can compensate for a pathogenic mitochondrial tRNA gene mutation, suggesting new strategies for therapeutic intervention.

The biological clock of very premature primate infants is responsive to light

Each year more than 250,000 infants in the United States are exposed to artificial lighting in hospital nurseries with little consideration given to environmental lighting cycles. Essential in determining whether environmental lighting cycles need to be considered in hospital nurseries is identifying when the infant's endogenous circadian clock becomes responsive to light. Using a non-human primate model of the developing human, we examined when the circadian clock, located in the hypothalamic suprachiasmatic nuclei (SCN), becomes responsive to light. Preterm infant baboons of different ages were exposed to light (5,000 lux) at night, and then changes in SCN metabolic activity and gene expression were assessed. After exposure to bright light at night, robust increases in SCN metabolic activity and gene expression were seen at ages that were equivalent to human infants at 24 weeks after conception. These data provide direct evidence that the biological clock of very premature primate infants is responsive to light.

The 69 bp circadian regulatory sequence (CRS) mediates per-like developmental, spatial, and circadian expression and behavioral rescue in Drosophila

The period (per) gene is an essential component of the circadian timekeeping mechanism in Drosophila. This gene is expressed in a circadian manner, giving rise to a protein that feeds-back to regulate its own transcription. A 69 bp clock regulatory sequence (CRS) has been identified previously upstream of the period gene. The CRS confers wild-type mRNA cycling when used to drive a lacZ reporter gene in transgenic flies. To determine whether the CRS also mediates proper developmental and spatial expression and behavioral rescue, we used the CRS to drive either lacZ or per in transgenic flies. The results show that the CRS is able to activate expression in pacemaker neuron precursors in larvae and essentially all tissues that normally express per in pupae and adults. The CRS is sufficient to rescue circadian feedback loop function and behavioral rhythms in per01 flies. However, the period of locomotor activity rhythms shortens if a stronger basal promoter is used. This study shows that regulatory elements sufficient for clock-dependent and tissue-specific per expression in larvae, pupae, and adults are present in the CRS and that the period of adult locomotor activity rhythms is dependent, in part, on the overall level of per transcripts.

T cell independence of bleomycin-induced pulmonary fibrosis

The role of T cells and cytokines in bleomycin (BLM)-induced fibrosis was evaluated in susceptible and resistant strains of normal and SCID mice. Histology and hydroxyproline analysis showed that BLM induced pulmonary fibrosis in C57BL/6 and (C57BL/6 x BALB/c)F1 mice, whereas BALB/c mice were resistant to the disease. To test whether lymphocytes were required for the induction of BLM-induced pulmonary fibrosis, SCID mice were injected intratracheally with BLM and evaluated for the development of pulmonary inflammation and fibrosis. Similar morphological changes and increases in hydroxyproline were observed in both C57BL/6 SCID and (C57BL/6 x CB.17)F1 SCID animals compared to those seen in wild-type C57BL/6 and (C57BL/6 x BALB/c)F1 mice. In contrast, CB.17 SCID mice, which are genetically similar to BALB/c mice, were resistant to disease induction. Analysis of the cellular infiltrate in BLM-treated C57Bl/6 SCID mice confirmed a lack of T cells in the lungs of SCID mice and demonstrated a pronounced accumulation of eosinophils in areas of developing pulmonary fibrosis. NK cells were significantly elevated in untreated SCID mice and did not increase further after BLM treatment. Analysis of selected cytokines 1 day after initiation of BLM-induced pulmonary fibrosis indicated that the levels of TNF-alpha and IFN-gamma appeared to segregate with fibrosis in both the SCID and wild-type mice. The data demonstrate that T cells are not required for the induction of fibrosis by BLM and suggest that responses by non-lymphoid cells may be sufficient for the induction of fibrosis.

Brain natriuretic peptide enhances the endothelium-independent cAMP and vasorelaxant responses of calcitonin gene-related peptide in rat aorta

Calcitonin gene-related peptide (CGRP) causes vasorelaxation in rat aorta involving endothelium/nitric oxide (NO)-dependent elevations of both cAMP and cGMP levels. When endothelium is removed, preincubation with exogenous NO uncovers and potentiates direct (endothelium-independent) cAMP elevations and vasorelaxations caused by CGRP. This enhancing effect of NO potentially involves elevation of cGMP and inhibition of Type III (cGMP-inhibitable) phosphodiesterase, causing accumulation of cAMP. However, NO may have other actions. The aim of the present study was to determine if brain natriuretic peptide (BNP), which elevates cGMP levels independent of NO, could enhance cAMP accumulations and vasorelaxations induced by CGRP in rat aortic rings denuded of endothelium. When added separately, neither CGRP (100 nM) nor BNP (10 nM) altered cAMP levels. When added in combination, CGRP (100 nM) and BNP (10 nM) significantly elevated cAMP levels (from control of 0.95+/-0.08 to 1.53+/-0.09 pmol/mg protein) at 2 min. BNP (10 nM) elevated cGMP levels 10-fold at 2 min and this response was not altered by co-administration of CGRP (100 nM). Pretreatment with BNP at concentrations as low as 1 nM in endothelium-denuded aortic rings greatly enhanced the direct vasorelaxant effects of CGRP (100 nM) (from control of 0% to 57.6+/-6.8% relaxation of phenylephrine-precontractions). Our findings indicate that BNP enhances direct (endothelium-independent) cAMP elevations and vasorelaxations caused by CGRP in rat aorta, thus supporting the concept that cGMP inhibits cAMP metabolism and enhances CGRP-induced responses in aortic smooth muscle cells.

[Pathogenesis of acute coronary syndromes]

Coronary artery diseases may categorized into asymptomatic disease, angina pectoris, myocardial infarction, chronic heart failure, and sudden coronary death. Unstable angina, acute myocardial infarction, and sudden cardiac death are known as the acute coronary syndromes. Coronary atheroma is unstable in the patients with acute coronary syndromes. Stable plaques will be unstable when dynamic alterations occur. The alterations are plaque rupture, plaque hemorrhage, coronary thrombosis and vasospasm. They act each other. We analysed the histopathology of coronary arteries who died of acute myocardial infarction in 85 cases. It showed that the risk factors of plaque rupture are clusters of form cells, eccentric plaque with soft lipid rich core, and thinning of fibrous cap in atheroma. Most of these cases ruptured at edge of the atheroma.

A disease-associated G5703A mutation in human mitochondrial DNA causes a conformational change and a marked decrease in steady-state levels of mitochondrial tRNA(Asn)

We introduced mitochondrial DNA (mtDNA) from a patient with a mitochondrial myopathy into established mtDNA-less human osteosarcoma cells. The resulting transmitochondrial cybrid lines, containing either exclusively wild-type or mutated (G5703A transition in the tRNA[Asn] gene) mtDNA, were characterized and analyzed for oxidative phosphorylation function and steady-state levels of different RNA species. Functional studies showed that the G5703A mutation severely impairs oxidative phosphorylation function and mitochondrial protein synthesis. We detected a marked reduction in tRNA(Asn) steady-state levels which was not associated with an accumulation of intermediate transcripts containing tRNA(Asn) sequences or decreased transcription. Native polyacrylamide gel electrophoresis showed that the residual tRNA(Asn) fraction in mutant cybrids had an altered conformation, suggesting that the mutation destabilized the tRNA(Asn) secondary or tertiary structure. Our results suggest that the G5703 mutation causes a conformational change in the tRNA(Asn) which may impair aminoacylation. This alteration leads to a severe reduction in the functional tRNA(Asn) pool by increasing its in vivo degradation by mitochondrial RNases.

Anti-acetylcholinesterase antibody in myasthenic syndrome

OBJECTIVE

To examine the relationship between antibodies to acetylcholinesterase and myasthenic syndrome.

METHODS

Serum class specific antibodies to acetylcholinesterase and acetylcholine receptor were prepared with solid phase enzyme-linked immunosorbent assay in 51 patients with myasthenic syndrome, 31 controls with other neurological diseases (diseased controls) and 44 normal controls.

RESULTS

The positive rate of anti-acetylcholinesterase antibody in patients with myasthenic syndrome was 25%, while the results of the other two control groups were negative. Furthermore, the positive rate in patients without myasthenia gravis was 45%, which was much higher than that (13%) in those with myasthenic gravis.

CONCLUSION

Anti-acetylcholinesterase antibody may play a role in the pathogenesis of myasthenic syndrome.

A circadian enhancer mediates PER-dependent mRNA cycling in Drosophila melanogaster

Genes expressed under circadian-clock control are found in organisms ranging from prokaryotes to humans. In Drosophila melanogaster, the period (per) gene, which is required for clock function, is transcribed in a circadian manner. We have identified a circadian transcriptional enhancer within a 69-bp DNA fragment upstream of the per gene. This enhancer drives high-amplitude mRNA cycling under light-dark-cycling or constant-dark conditions, and this activity is per protein (PER) dependent. An E-box sequence within this 69-bp fragment is necessary for high-level expression, but not for rhythmic expression, indicating that PER mediates circadian transcription through other sequences in this fragment.

Functional and structural features of a tandem duplication of the human mtDNA promoter region

An approximately 260-bp tandem duplication of the human mtDNA regulatory region has been identified in patients with mitochondrial disorders and in a specific Caucasian haplogroup. The functional significance of this mtDNA duplication was difficult to assess, because it was present at very low levels in human tissues. We have isolated several transmitochondrial cybrid lines harboring this mutation, one of which (clone CA17.1) was essentially homoplasmic for the duplication. Oxidative-phosphorylation function was not impaired in clone CA17.1, suggesting that this mtDNA alteration is not pathogenic. mtDNA copy number and steady-state levels of heavy- and light-strand transcripts were unaltered in clone CA 17.1. The steady-state levels of RNAs made from the two promoters (either from the heavy-strand or from the light-strand) were also similar, indicating that oppositely oriented promoters did not interfere with each other.

Wall composition in intravascular ultrasound layered appearance of human coronary artery

To evaluate the impact of histological factors on the appearance of the wall of the coronary artery by intravascular ultrasound (IVUS), we performed an in vitro study of 34 coronary artery segments from eight autopsied patients. We assumed the coronary cross section to be divided into four equal parts, and assessed the quadrants with maximal and minimal wall thickness by IVUS (30 MHz; 4.3 Fr; 1800 rpm) and by a histological study. The histological layer thickness and composition were also evaluated in terms of their contribution to the appearance of the ultrasound layer. Fifty-eight quadrants were clearly visible on ultrasound. A three-layered appearance, with inner echogenic, subjacent sonolucent, and outer echogenic layers, was observed in 32 quadrants, while 26 quadrants showed a two-layered appearance with inner and outer echogenic layers. The thickness of the inner echogenic layer (0.77 +/- 0.38 mm) was moderately correlated with the intimal thickness (0.51 +/- 0.45 mm; r = 0.85, standard error of estimate [SEE] = 0.24 mm); however, the correlation was significantly improved when the thickness of the inner echogenic plus sonolucent layers (0.89 +/- 0.47 mm) was compared with that of the intima plus media (0.69 +/- 0.47 mm; r = 0.94, SEE = 0.15 mm; P = 0.012 between the coefficients). Discriminant analysis showed that intimal hyalinization, associated with intimal thickening, was strongly related to the presence of the three-layered appearance on IVUS (F to enter 40.0, P < 0.0001). These results indicate that the ultrasound layered appearance of human coronary arteries varies with histological alterations. We suggest that the thickness of the inner echogenic plus sonolucent layers on IVUS represents the intimal plus medial thickness observed by histology, and that the use of this value may be appropriate in the assessment of coronary wall thickening associated with atherosclerosis.

Functional and molecular mitochondrial abnormalities associated with a C --> T transition at position 3256 of the human mitochondrial genome. The effects of a pathogenic mitochondrial tRNA point mutation in organelle translation and RNA processing

We have previously identified a mitochondrial DNA polymorphism (a C --> T transition at position 3256, within the mitochondrial tRNALeu(UUR) gene in a patient with a multisystem disorder. Although there were several indicators suggesting a pathogenetic role for this mtDNA polymorphism, its heteroplasmic nature made functional and molecular studies difficult to interpret. We have now fused enucleated fibroblasts from the patient with a mtDNA-less cell line to generate transmitochondrial cybrids harboring different proportions of mutated and wild-type mtDNA. Individual clones harboring essentially 100% wild-type or > 99% mutated mtDNAs were characterized and studied for respiratory capacity, respiratory chain enzymes activity, mitochondrial protein synthesis, and RNA steady-state levels and processing. Our results showed that cell lines containing exclusively mutated mtDNAs respire poorly, overproduce lactic acid, and have significantly impaired activity of respiratory complexes I and IV. Molecular studies showed that mutant clones have a decrease in steady-state levels of mitochondrial tRNALeu(UUR), and a partial impairment of mitochondrial protein synthesis and steady-state levels, suggesting that these molecular abnormalities are involved in the pathogenetic mechanism of the mtDNA 3256 mutation.

Alterations of bone matrix protein mRNA expression in rat aorta in vitro

We examined the expression of matrix Gla protein (MGP), osteopontin (OPN), and osteonectin (ON) mRNAs in aortic rings excised from 3-month-, 10-month-, and 2-week-old rats during 72-hour incubations in serum-free media. In the aortic rings from 3-month-old rats, the expression of MGP mRNA was strong before incubation and increased during the 72-hour incubation. The expression of OPN mRNA was first detected after a 5-hour incubation and increased thereafter, and that of ON mRNA was strong before the incubation and decreased during the incubation. The expression of MGP and OPN mRNAs in 10-month- and 2-week-old rats was similar to that in 3-month-old rats. In contrast, expression of ON mRNA in 10-month-old rats and the expression of ON mRNA in 2-week-old rats was stronger than that in 3-month-old rats at every incubation period. In situ hybridization and immunohistochemistry identified the MGP, OPN, and ON mRNA-expressing cells as vascular smooth muscle cells. These results suggest that the expression of these mRNAs was regulated in incubation time-dependent and age-specific ways. We believe that this organ culture model is useful for further studies of the function of these bone matrix proteins and regulation of their expression in the vessel wall.