Apoptosis in rabbit haemorrhagic disease

Rabbit haemorrhagic disease virus (RHDV) causes an acute hepatitis and disseminated intravascular coagulation. Six rabbits were inoculated experimentally with RHDV to investigate any potential relationship between infection and apoptosis in the liver. Two rabbits were killed at 12 h post-inoculation (PI) and two at 24 h PI. The remaining two rabbits died at 30 h and 31 h PI. Immunohistochemical labelling for RHDV antigen-positive cells, TUNEL assay for apoptotic cells, and DNA analysis were performed on samples of liver. The four rabbits that died or were killed 24-31 h PI had acute hepatitis with infiltration of heterophils and necrotic hepatocytes. RHDV antigen-positive cells and apoptotic cells appeared in the centriacinar areas at 12 h PI; subsequently they spread to periacinar areas and increased in number, but the viral antigen-positive cells outnumbered apoptotic cells. At 24-31 h PI, few apoptotic cells were recognized in the areas infiltrated with lymphocytes and heterophils. The results suggested an association between RHDV infection and apoptosis of hepatocytes.

Brain uptake and the analgesic effect of oxytocin--its usefulness as an analgesic agent

To establish the usefulness of oxytocin (OT) as an analgesic for women in delivery, the pharmacokinetic parameters and blood-brain barrier (BBB) permeability of [3H]OT were obtained using an intravenous injection technique or the internal carotid artery perfusion/capillary depletion (ICAP/CDM) method. Brain uptake of OT was similar to that of sucrose, plasma space marker, indicating that OT has a poor BBB permeability. Moreover, the analgesic effects of OT injected through the jugular vein on nociception were evaluated by the tail-flick method. The antinociceptive effects of OT injected at a dose of 0.2 mg/kg or 2 mg/kg were dose-dependent. In addition, the analgesic effects of OT on the CNS were unaffected by naloxone, a m-receptor antagonist. In a similar manner to the opioid system, OT may play a modulatory role in antinociception.

Activation of heat shock factor 1 by hyperosmotic or hypo-osmotic stress is drastically attenuated in normal human fibroblasts during senescence

We have previously reported that osmotic stress prominently induces the DNA binding activity of the heat shock transcription factor 1 (HSF1). In the present study, we examined the effects of medium osmolarity on both the activation of HSF1 and the programmed cell death in normal human fibroblasts during cellular senescence. The activation of HSF1 occurred rapidly in presenescent (early passage) IMR-90 cells when exposed to either hypo-osmotic or hyperosmotic stress. In contrast, the activation of HSF1 was significantly attenuated in senescent cells. Western blot analysis indicated that equal amounts of HSF1 were present as monomers in the cytoplasm of both presenescent and senescent cells in normal growth medium. Under either hypo-osmotic or hyperosmotic stress, trimerization and nuclear localization of HSF1 occurred in presenescent cells but not in senescent cells. More than 80% of HSF1 in senescent cells remained as monomers in the cytoplasm under osmotic stress, suggesting a defect in the signal transduction pathways that lead to HSF1 trimerization or a dysfunction in the HSF1 protein itself. Possible involvement of mitogen-activated protein kinase (MAPK) signal transduction pathways in the activation HSF1 was investigated by monitoring the activation of the three MAPKs, ERK1/2, JNK1/2, and p38, in cells exposed to hypo-osmotic or hyperosmotic stress. All three MAPKs were activated by hyperosmotic stress but not hypo-osmotic stress, suggesting that the MAPK signal transduction pathways may not be directly linked to the osmotic stress-induced activation of HSF1. In contrast to the rapid heat shock transcription factor (HSF) activation, apoptosis occurred only after long-term exposure to hypo-osmotic or hyperosmotic stress. Despite the prominent induction of HSF1 activation, the presenescent cells were more sensitive than the senescent cells to the osmotic stress-induced apoptosis.

Dual anticancer activity of 8-Cl-cAMP: inhibition of cell proliferation and induction of apoptotic cell death

8-Cl-cAMP induces apoptotic cell death in human cancer cells. To look at this more closely, we examined the changes in the levels of Bcl-2 family proteins during 8-Cl-cAMP-induced apoptosis of SH-SY5Y human neuroblastoma cells. Following the treatment with 8-Cl-cAMP, Bcl-2 was transiently down-regulated and Bad was increased continuously up to day 5. In addition, overexpression of Bcl-2 efficiently blocked the 8-Cl-cAMP-induced apoptosis, suggesting Bcl-2 family proteins may be involved in the 8-Cl-cAMP-induced apoptosis. The contribution of the apoptotic cell death and the inhibition of cell proliferation in the 8-Cl-cAMP-induced growth inhibition was closely monitored in the Bcl-2-overexpressing cells. Though the apoptosis was reduced significantly, no significant difference was observed in the inhibition of cell proliferation up to day 2 of 8-Cl-cAMP treatment. These results suggest that 8-Cl-cAMP exerts anticancer activity by two distinct mechanisms, i.e. , through the inhibition of cell proliferation as well as the induction of apoptosis. Supporting this notion was the observations that (1) suppression of apoptosis by zVAD did not abrogate 8-Cl-cAMP-induced inhibition of cell proliferation, and (2) 8-Cl-cAMP did not show additive inhibition of cell proliferation in RIIbeta-overexpressing cells.

Frequent alteration of p63 expression in human primary bladder carcinomas

p63, a recently identified member of the p53 gene family, encodes multiple products with transactivating, death-inducing, and dominant-negative activities. To explore the penetrance of p63 in bladder carcinogenesis, we performed expression and mutation analyses of two major isotypes, TAp63 and deltaNp63, in 63 bladder specimens. In 12 normal tissues, TAp63 was expressed at an easily detectable level whereas deltaNp63 was absent or extremely low. While none of 47 carcinomas showed allelic deletion of the gene, marked reduction of TAp63 and abnormal overexpression of deltaNp63 were found in 25 (53.2%) and 30 (63.8%) carcinomas, respectively. Tumor-specific alteration of TAp63 and deltaNp63 expression was identified in two and three of six matched sets, respectively. In addition, reduced expression of TAp63 showed a correlation with tumor stage and grade. Abnormal expression of TAp63 or deltaNp63 isoform was also observed in three of four cell lines, and treatment with 5-Aza-2'-deoxycytidine led to up- or down-regulation of TAp63 and/or deltaNp63 expression, suggesting that the promoters of both isoforms might be affected by DNA methylation, but not in a reciprocal fashion. No sequence alteration of p63 was identified in 47 carcinomas whereas 17 (34.8%) of these showed p53 mutations, and no association between p63 expression and the mutational status of p53 or expression of p21Waf1, MDM2, and 14-3-3sigma was recognized. Our data suggest that altered expression of p63 is a frequent event in bladder carcinogenesis and might contribute to the progression of bladder tumors, possibly via the mechanism(s) distinct from the p53 pathway.

p16 is a major inactivation target in hepatocellular carcinoma

BACKGROUND

The p16(INK4A) gene encodes 2 cell cycle regulator proteins, p16 and p14(ARF), by alternative splicing. This genetic locus also contains another cell cycle regulator gene, p15(INK4B), which encodes p15. The inactivation of the p16 protein has been demonstrated in some hepatocellular carcinomas (HCCs); however, the inactivation of the other 2 cell regulator proteins and their inactivation patterns are not well characterized.

METHODS

To characterize the role of the above 3 cell cycle regulator proteins in HCCs, the authors examined the genomic status of the p16(INK4A) and p15(INK4B) genes and their RNA products in 20 HCC tissues and 7 human HCC cell lines. Homozygous deletions in each exon of p16(INK4A) and p15(INK4B) were evaluated by comparative multiplex polymerase chain reaction (PCR), and the methylation status of the p16(INK4A) and p15(INK4B) promoter region was analyzed by methylation specific PCR.

RESULTS

Homozygous deletions were found in 6 of 20 HCCs (30%) and 2 of 7 HCC cell lines (29%). In 20 HCCs, the frequency of homozygous deletions was 20% in exon 1 of p15(INK4B), 20% in exon 2 of p15(INK4B), 10% in exon 1beta of p16(INK4A), 25% in exon 1alpha of p16(INK4A), 15% in exon 2 of p16(INK4A), and 15% in exon 3 of p16(INK4A). The authors found hypermethylation of the p16(INK4A) promoter region in 7 HCCs (35%) and 3 HCC cell lines (43%). The overall frequency of p16 alterations in HCCs, including hypermethylation and homozygous deletions, was 60% (12 of 20 cases). According to reverse transcriptase-PCR analysis, the absence of RNA expression was most frequent in p16 (11 of 20 cases, 55%) and less frequent in p15 (7 of 20 cases, 35%) and p14(ARF) (5 of 20 cases, 25%).

CONCLUSIONS

Among the 3 cell cycle regulator proteins encoded at the 9p21 genetic locus, inactivation of p16 is the most frequent event in HCCs in which promoter hypermethylation and homozygous deletions are the common mechanisms.

Diagnostic accuracy in sinus fungus balls: CT scan and operative findings

A fungus ball may be characterized by its radiologic and operative gross findings. Computed tomography (CT) revealed a rim of soft tissue attenuation of variable thickening along the bony walls of the isolated paranasal sinus, or mottled hyperdense foci of variable size. A small amount of friable muddy mass surrounded by purulent secretions or dirty brown clay-like materials provide highly pathognomonic findings. However, these characteristics may induce clinical misdiagnosis. During the last four years we experienced 11 cases of chronic paranasal sinusitis in which pathologic examination failed to confirm fungal hyphae, despite clinical suspicion of a fungus ball based on operative or CT findings. During the same period, we also experienced another 52 patients who were diagnosed with fungus ball at pathologic examination. To evaluate the diagnostic accuracy of CT scans and operative gross findings in sinus fungus balls, we reviewed the medical records of these 63 patients and also reviewed CT scans and operative records of another 1127 patients who received endoscopic sinus surgery for chronic rhinosinusitis. The sensitivity of CT evaluation was 62%, and specificity was 99%. The false-positive and false-negative rate were 22% and 2%, respectively. With regard to operative findings, such as clay-like inspissated mucus, the sensitivity, specificity, and predictive value positive rate were 100%, 99%, and 83%, respectively. To make a diagnosis of fungus ball, a high index of suspicion is necessary and a pathologic confirmation is mandatory.

Association of tightly spiraled bacterial infection and gastritis in pigs

Tightly spiral bacteria were observed only in the pyloric mucosa of 4 (8.0%) of 50 swine stomachs, mainly in the surface of epithelia, the gastric pits and the lumen of gastric glands. The presence of the spiral bacteria was significantly associated with chronic pyloric gastritis (p<0.05). Mean gastritis score of the bacteria-positive pyloric mucosa was 3.25 +/- 0.25, whereas that of the bacteria-negative pyloric mucosa was 2.37 +/- 0.12. Parakeratosis and hyperkeratosis were spontaneously seen in the mucosa layer of pars oesophagea, regardless of the bacterial infection. Marked infiltration of mononuclear cells and granulocytes were seen in the cardiac mucosa, regardless of the bacterial infection. Mean gastritis score of the bacteria-positive cardiac mucosa was 3.27 +/- 0.32, whereas that of the bacteria-negative cardiac mucosa was 2.84 +/- 0.13. There was no significant difference between the bacteria-positive and negative cardiac mucosa (p>0.05). Inflammatory response in the fundic mucosa was rare (gastritis score=0.75 +/- 0.08). The tightly spiraled bactera were not cultured with various culture media. These results suggest that the presence of tightly spiraled bacteria is associated with only the pyloric gastritis in pigs.

Production of D-amino acid using whole cells of recombinant Escherichia coli with separately and coexpressed D-hydantoinase and N-carbamoylase

We developed a fully enzymatic process employing D-hydantoinase and N-carbamoylase for the production of D-amino acid from 5'-monosubstituted hydantoin. For the comparison of the reaction systems using two sequential enzymes, D-hydantoinase of Bacillus stearothermophilus SD1 and N-carbamoyl-D-amino acid amidohydrolase (N-carbamoylase) of Agrobacterium tumefaciens NRRL B11291 were separately expressed in each host cell and coexpressed in the same host cell. A high level and constitutive expression of both enzymes in Escherichia coli in a soluble form was achieved using a promoter derived from B. stearothermophilus SD1. The expression levels of both enzymes ranged from 17% to 23% of the total soluble protein, depending on the expression system. In the case of employing separately expressed enzymes, the product yield of D-hydroxyphenylglycine from D,L-p-hydroxyphenylhydantoin and productivity were 71% and 2.57 mM/g-cell/h in 15 h, respectively. The accumulation of N-carbamoyl-D-hydroxyphenylglycine was significant over the reaction time. On the other hand, use of coexpressed enzymes resulted in 98% product yield of D-hydroxyphenylglycine in 15 h, minimizing the level of intermediates in the reaction mixture. The productivity of coexpressed whole cell reaction was estimated to be 6.47 mM/g-cell/h in 15 h. The coexpressed system was tested for an elevated concentration of D,L-p-hydroxyphenylhydantoin, and efficient production can be achieved.

Bioadhesive-based dosage forms: the next generation

Prolonged contact time of a drug with a body tissue, through the use of a bioadhesive polymer, can significantly improve the performance of many drugs. These improvements range from better treatment of local pathologies to improved drug bioavailability and controlled release to enhanced patient compliance. There are abundant examples in the literature over the past 15 years of these improvements using first generation or "off-the-shelf" bioadhesive polymers. The present mini-review will remind us of the success achieved with these first-generation polymers and focus on proposals for the next-generation polymers and attendant benefits likely to occur with these improved polymeric systems.

Functional characterization of the rat gamma-glutamyl transpeptidase promoter that is expressed in transformed rat liver epithelial cells

In the rat the gamma-glutamyl transpeptidase (GGT) gene codes for at least four different messenger RNAs (mRNA I to mRNA IV) which differ only in their 5' untranslated regions and are transcribed from a single copy gene in a tissue-specific manner. In the liver GGT expression is up-regulated in transformed cells. To understand the induction mechanisms of GGT activity by transformation, we previously cloned the 5' region of the rat GGT gene which contains the 5' untranslated leader sequence for mRNA I. In the present study, using transfection and reporter gene assays, I have demonstrated that (1) the sequence from positions -369 to +226 drives a relatively strong promoter activity in C5 and AKG cell lines, transformed rat liver epithelial cells, but a very weak one in RLE-228 cells, a normal rat liver epithelial cell line; and (2) removal of the region between -418 and -369 increases CAT activity more than 10-fold in RLE-228, C5 and AKG cells, and the DNA fragment spanning nucleotides -761 to -292 significantly reduces CAT activity driven by the adenine phosphoribosyl transferase (APRT) promoter in RLE-228 cells.

Dimerization of the insulin-like growth factor II/mannose 6-phosphate receptor

The insulin-like growth factor II/mannose 6-phosphate receptor (IGF2R) interacts with lysosomal enzymes through two binding domains in its extracytoplasmic domain. We report in the accompanying article (Byrd, J. C., and MacDonald, R. G. (2000) J. Biol. Chem. 275, 18638-18646) that only one of the two extracytoplasmic mannose 6-phosphate (Man-6-P) binding domains is necessary for high affinity Man-6-P ligand binding, suggesting that, like the cation-dependent Man-6-P receptor, oligomerization of the IGF2R contributes to high affinity interaction with lysosomal enzymes. In the present study, we have directly characterized both naturally occurring and engineered forms of the IGF2R for their ability to form oligomeric structures. Whereas gel filtration chromatography suggested that purified bovine IGF2R species exist in a monomeric form, native gel electrophoresis allowed for the separation of dimeric and monomeric forms of the receptors with distinct phosphomannosyl ligand binding characteristics. The ability of the IGF2R to form oligomeric complexes was confirmed and localized to the extracytoplasmic domain through the use of epitope-tagged soluble IGF2R constructs bearing deletions of the transmembrane and cytoplasmic domains. Finally, chimeric receptors were engineered containing the extracytoplasmic and transmembrane domains of the IGF2R fused to the cytoplasmic domain of the epidermal growth factor receptor with which dimerization of the chimeras could be monitored by measuring autophosphorylation. Collectively, these results show that the IGF2R is capable of forming oligomeric complexes, most likely dimers, in the absence of Man-6-P ligands.

Involvement of two NF-kappa B binding elements in tumor necrosis factor alpha -, CD40-, and epstein-barr virus latent membrane protein 1-mediated induction of the cellular inhibitor of apoptosis protein 2 gene

The antiapoptotic function of NF-kappaB is believed to be mediated through the induction of antiapoptotic genes. Among the antiapoptotic genes, cellular inhibitor of apoptosis protein 2 (c-IAP2/HIAP-1/MIHC) is originally identified as a molecule recruited to the tumor necrosis factor (TNF) receptor complex, and its expression is preferentially up-regulated by TNF and other stimuli activating NF-kappaB. However, direct evidence of transcriptional regulation of NF-kappaB on the c-IAP2 gene is still missing. Here, we have cloned and characterized the promoter region required for NF-kappaB-dependent transcription of the c-IAP2 gene. Sequencing of a 3.5-kilobase fragment of the 5'-flanking region of the c-IAP2 gene has identified a TATA-like sequence and potential binding sites for nuclear factor of activated T cells, interferon regulatory factor 1, activator protein 1, glucocorticoid response element, and three putative NF-kappaB binding elements. Deletion and mutational analysis of the 5'-flanking region linked to the luciferase gene revealed that transcriptional activation by TNF or interleukin 1 is mediated cooperatively by two NF-kappaB binding sites. Electrophoretic mobility shift assays characterized that the two NF-kappaB sites can be recognized and bound by the NF-kappaB p50/p65 heterodimer. In addition, the transcription of c-IAP2 promoter was strongly up-regulated when CD40 or Epstein-Barr virus latent membrane protein 1 was overexpressed.

Cloning and characterization of the murine pkd2 promoter

Pkd2, the mouse homologue of PKD2, the gene responsible for the second form of autosomal dominant polycystic kidney disease, is highly expressed in fetal and adult mouse tissues. The expression of Pkd2 is developmentally regulated. To begin to dissect out the regulatory mechanism of Pkd2 expression, we characterized the basic features of the gene structure and identified potential cis-regulatory elements of Pkd2 transcription. Pkd2 spans 42 kb with a transcription start site 165 bp upstream of the translation start codon. Exon 1 of Pkd2 is 755 bp long, and the full-length transcript is 5215 bp. The Pkd2 promoter region is GC-rich and lacks a consensus TATA or CCAAT box. Consensus binding sites for the transcription factors Sp-1, NF-1, and Ap-2 lie in the 5' upstream region of Pkd2. The Sp-1 binding site is conserved in 5' upstream sequences of both the mouse and the human genes. The CAT activity of a series of upstream segments from +178 to -2749 was assessed in MDCK, LLCPK1, COS-7, and HEK293 cells. Deletion analysis identified a 409-bp fragment from position -221 to +178 responsible for basal promoter activity. A 922-bp fragment from -744 to +178 showed the highest level of CAT activity in the cell lines tested. These data define a functional promoter candidate region for Pkd2.

Detection of human herpesvirus 6 variant A in peripheral blood mononuclear cells from multiple sclerosis patients

Several authors report that human herpesvirus 6 (HHV-6) variants have different epidemiologies, in vivo tropism and pathogenic potentials. However, it is not well known what pathogenic roles its neurotropism might have in the variant type. As some active plaques of multiple sclerosis (MS) brain tissue harbor HHV-6 DNA divergent from the prototype virus, the possibility that the variant strain may play a role in the pathogenesis of MS has been suggested. Therefore, we tried to investigate the role of HHV-6 variants in the pathogenesis of MS. As HHV-6 is predominantly a T-cell-tropic virus, we examined HHV-6 DNA sequences in peripheral blood mononuclear cells (PBMC) from 34 MS patients, 6 with idiopathic transverse myelitis, 2 with optic neuritis and 20 healthy controls. Nested polymerase chain reaction was used to detect the HHV-6 genome. To discern HHV-6 variants A and B, amplification products were digested by restriction enzyme. We found that 7 of 34 MS patients and 2 of 6 patients with idiopathic transverse myelitis had the HHV-6 genome. On the contrary, there was no HHV-6 genome in the control group. All genomic sequences were of HHV-6 variant A (HHV-6A). Our results suggest that the detection of HHV-6A in the PBMC of patients with MS may raise the possibility of a relationship between latent HHV-6A infection and the pathogenesis of MS.

Disruption of synaptic transmission or clock-gene-product oscillations in circadian pacemaker cells of Drosophila cause abnormal behavioral rhythms

To study the function of clock-gene-expressing neurons, the tetanus-toxin light chain (TeTxLC), which blocks chemical synaptic transmission, was expressed under the control of promoters of the clock genes period (per) and timeless (tim), each fused to GAL4-encoding sequences. Although TeTxLC did not affect cycling of a clock-gene product at the gross level, it disrupted the rhythmic behavior of adult Drosophila. In constant darkness, the proportion of rhythmic flies was reduced in flies expressing active TeTxLC compared to controls, including those expressing inactive toxin. The behavior of TeTxLC-expressing flies was less synchronized to light:dark cycles than that of controls. To determine which neurons are responsible for these effects on behavior, the toxin was also expressed in restricted subsets of per/tim-expressing, laterally located pacemaker neurons by expressing TeTxLC under the control of a driver in which GAL4-encoding sequences are fused to the promoter of the pigment dispersing factor (pdf) gene. pdf-gal4-driven TeTxLC expression had relatively little effect on behavioral rhythms, implying that per/tim neurons other than pdf-expressing lateral neurons participate in the generation of rhythmic behavior. In another set of experiments, period gene products were expressed under the control of per-gal4 or tim-gal4. This resulted in an increased level of PER protein in many brain cells and reduction of bioluminescence cycling reported by a per-luciferase transgene, especially in the case of per expression affected by tim-gal4. This indicates a disruption of the transcriptional feedback loop that is a part of the oscillatory mechanism underlying Drosophila's circadian rhythms. Consistent with this molecular defect, the proportion of rhythmic individuals in constant darkness was subnormal in flies expressing PER under the control of tim-gal4, and their behavior in light:dark cycles was abnormal.

Islet cell hyperplasia of the pancreas presenting as hyperinsulinemic hypoglycemia in an adult

A 72-year-old man who had suffered several episodes of syncope was diagnosed as having hyperinsulinemic hypoglycemia. Although imaging studies and percutaneous transhepatic portal venous sampling did not reveal the existence of any tumors in the pancreas, distal pancreatectomy was performed because the possibility of a small pancreatic endocrine tumor could not be completely rejected. External examination of the surgically removed pancreas did not reveal any tumors. Microscopically, the pancreas exhibited diffuse islet cell hyperplasia without nesidioblastosis. The patient remains euglycemic and has tolerated 24-hour fasting without any medication for a period of 10 months after the operation.

A novel microbial interaction: obligate commensalism between a new gram-negative thermophile and a thermophilic Bacillus strain

Obligately commensal interaction between a new gram-negative thermophile and a thermophilic Bacillus strain was investigated. From compost samples, a mixed culture showing tyrosine phenol-lyase activity was enriched at 60 degrees C. The mixed culture consisted of a thermophilic gram-negative strain, SC-1, and a gram-positive spore-forming strain, SK-1. In mixed cultures, strain SC-1 started to grow only when strain SK-1 entered the stationary phase. Although strain SC-1 showed tyrosine phenol lyase activity, we could not isolate a colony with any nutrient medium. For the isolation and cultivation of strain SC-1, we added culture supernatant and cell extract of the mixed culture to the basal medium. The supernatant and cell extract of the mixed culture contained heat-stable and heat-labile factors, respectively, that are essential to the growth of strain SC-1. During pure cultures of strain SK-1, the heat-stable growth factors were released during the growth phase and the heat-labile growth factors were produced intracellularly at the early stationary phase. Strain SC-1 was gram-negative and microaerophilic, and grows optimally at 60 degrees C. Based on these results, we propose a novel commensal interaction between a new gram-negative thermophile, strain SC-1, and Bacillus sp. strain SK-1.

Mitogenic conversion of transforming growth factor-beta1 effect by oncogenic Ha-Ras-induced activation of the mitogen-activated protein kinase signaling pathway in human prostate cancer

Elevated expression of transforming growth factor (TGF)-beta1 has been implicated in prostate tumorigenesis despite its growth-inhibitory effect on normal epithelial and carcinoma cells of the prostate. In this study, we identified that G1-to-S transition of the cell cycle is stimulated by TGF-beta1 in the prostate cancer cell line TSU-Pr1. No mutation of signal mediators, including Smads, and induction of PAI-1 transcription indicated that the TGF-beta1 signaling cascade is functionally intact in this cell line. Whereas pharmacological inhibitors of various mitogenic signaling pathways showed no effects, blockade of the mitogen-activated protein kinase (MAPK) pathway by the MAPK kinase 1 inhibitor PD98059 restored the growth inhibitory role of TGF-beta1 in TSU-Pr1, which carries an oncogenic mutation in Ha-Ras (V12). Moreover, expression of antisense Ha-Ras or dominant negative Raf-1 abrogated the mitogenic effect of TGF-beta1 in TSU-Pr1, and the TGF-beta1 inhibition of DU145 was switched to stimulation by V12Ha-Ras transfection. Whereas the negative growth regulation by TGF-beta1 was completely inhibited by dominant negative Smad2, Smad3, or Smad4, its mitogenic effect was not affected, suggesting that this action is Smad-independent. Interestingly, whereas the TGF-beta1-mediated up-regulation of p15INK4B and p21WAF1 transcription was abolished in TSU-Pr1 and V12Ha-Ras-transfected DU145, inhibition of the Ras/MAPK pathway restored the TGF-beta1 induction of these genes. Taken together, our data suggest that prostate carcinomas with the Ras/MAPK pathway activation might have a selective growth advantage by autocrine TGF-beta1 production.

Loss of imprinting and elevated expression of wild-type p73 in human gastric adenocarcinoma

The p73 gene located at 1p36.3 encodes for a protein with significant similarity to p53. To investigate the penetrance of p73 in gastric carcinogenesis, we analyzed the expression, allelotype, and mutation of p73 in five cell lines and 75 tissues. Although extremely low levels of p73 expression were observed in all noncancerous gastric tissues and four of five cell lines, a significant elevation of p73 was detected in 37 of 39 (94.9%) carcinoma tissues. Furthermore, a tumor-specific increase of p73 was identified in 14 of 16 (87.5%) matched sets. Allelotyping analysis using a StyI or BanI polymorphism revealed that 5 of 21 (23.8%) informative carcinomas, but none of 19 noncancerous cases, express p73 biallelically, suggesting the transcriptional activation of a silent allele in a subset of cancers. Whereas the transcription of an active allele was markedly induced by serum starvation or clump formation of the cells, treatment with 5-aza-2'deoxycytidine activated a silent allele with a subsequent up-regulation of an active allele, supporting the genomic imprinting and autoregulation of the gene. Allelic deletion or mutation of the gene was not found, and no association of p73 expression with the mutational status of p53 or expression of p21Waf1 was recognized. Taken together, this study argues that p73 is not a target of genetic alteration in gastric carcinogenesis and suggests that overexpression of p73 might be triggered by physiological stresses accompanied with outgrowth of tumors, such as hypoxia or nutrient deprivation.

Ectopic expression of the neuropeptide pigment-dispersing factor alters behavioral rhythms in Drosophila melanogaster

To study the function of the neuropeptide pigment-dispersing factor (PDF) in the circadian system of Drosophila, we misexpressed the pdf gene from the grasshopper Romalea in the CNS of Drosophila and investigated the effect of this on behavioral rhythmicity. pdf was either ectopically expressed in different numbers of neurons in the brain or the thoracical nervous system or overexpressed in the pacemaker neurons alone. We found severe alterations in the activity and eclosion rhythm of several but not all lines with ectopic pdf expression. Only ectopic pdf expression in neurons that projected into the dorsal central brain severely influenced activity rhythms. Therefore, we conclude that PDF acts as a neuromodulator in the dorsal central brain that is involved in the rhythmic control of behavior. Overexpression of pdf in the pacemaker neurons alone or in the other neurons that express the clock genes period (per) and timeless (tim) did not disturb the activity rhythm. Such flies still showed a rhythm in PDF accumulation in the central brain terminals. This rhythm was absent in the terminals of neurons that expressed PDF ectopically. Probably, PDF is rhythmically processed, transported, or secreted in neurons expressing per and tim, and additional PDF expression in these cells does not influence this rhythmic process. In neurons lacking per and tim, PDF appears to be continuously processed, leading to a constant PDF secretion at their nerve terminals. This may lead to conflicting signals in the rhythmic output pathway and result in a severely altered rhythmic behavior.

Resolution enhancement in a reflection mode near-field optical microscope by second-harmonic modulation signals

The motion of the probe tip in a near-field scanning optical microscope, dithered by vibration of a tuning fork, can modulate the reflection signal from the sample surface not only at the fundamental dithering frequency but also at its second harmonic. By lock-in amplification of these modulated signals, enhanced optical images are obtained, even with an uncoated fiber probe. In particular, accurate optical images with higher resolution are obtained when the second-harmonic signal is detected, which results from the parametric modulation of the tip-sample separation at the double frequency of the horizontal dithering motion of the tip. Using a DVD ROM with a track pitch of 0.74 mum as a test sample, we observed that the sharp edges around the pits are clearly resolved with the second-harmonic signals and obtained enhanced resolution of ~70 nm full width at half-maximum.