The molecular basis of sister-chromatid cohesion

The replicated copies of each chromosome, the sister chromatids, are attached prior to their segregation in mitosis and meiosis. This association or cohesion is critical for each sister chromatid to bind to microtubules from opposite spindle poles and thus segregate away from each other at anaphase of mitosis or meiosis II. The cohesin protein complex is essential for cohesion in both mitosis and meiosis, and cleavage of one of the subunits is sufficient for loss of cohesion at anaphase. The localization of the cohesin complex and other cohesion proteins permits evaluation of the positions of sister-chromatid associations within the chromosome structure, as well as the relationship between cohesion and condensation. Recently, two key riddles in the mechanism of meiotic chromosome segregation have yielded to molecular answers. First, analysis of the cohesin complex in meiosis provides molecular support for the long-standing hypothesis that sister-chromatid cohesion links homologs in meiosis I by stabilizing chiasmata. Second, the isolation of the monopolin protein that controls kinetochore behavior in meiosis I defines a functional basis by which sister kinetochores are directed toward the same pole in meiosis I.

The proteins of synaptic vesicle membranes are affected during ageing of rat brain

Low molecular weight GTP-binding proteins are molecular switches that are believed to play pivotal roles in cell growth, differentiation, cytoskeletal organization, and vesicular trafficking. Rab proteins are key players in the regulation of vesicular transport, while Rho family members control actin-dependent cell functions, i.e. the regulation of cytoskeletal organization in response to extracelluar growth factors and in dendritic neuron development. In this study, we have examined the regulation of small GTP-binding proteins that are implicated in neurosecretion and differentiation of neuron during ageing processes. Comparison of small GTP-binding proteins from the synaptosome and crude synaptic vesicles (LP2 membranes) of 2 months and 20 months old rat brain respectively showed no difference in the level of Rab family proteins (Rab3A and Rab5A). However, Rho family proteins such as RhoA and Cdc42 were elevated in LP2 membranes of the aged brain. The dissociation of Rab3A by Ca2+/calmodulin (CaM) from SV membranes was not changed during aging. Ca2+/CaM stimulated phosphorylation of the 22 and 55-kDa proteins in SV membranes from the aged rat brain, and inhibited phosporylation of 30-kDa proteins. GTPgammaS inhibited phosphorylation of the 100-kDa proteins and stimulated phosphorylation of the 70 kDa in LP2 membranes from both the young and aged rat brains, whereas GDPbetaS caused just the opposite reaction. These results suggest that protein phosphorylation and regulation of Rho family GTPases in rat brain appears to be altered during ageing processes.

differential L-selectin binding activities of human hematopoietic cell L-selectin ligands, HCELL and PSGL-1

Expression of L-selectin on human hematopoietic cells (HC) is associated with a higher proliferative activity and a more rapid engraftment after hematopoietic stem cell transplantation. Two L-selectin ligands are expressed on human HCs, P-selectin glycoprotein ligand-1 (PSGL-1) and a specialized glycoform of CD44 (hematopoietic cell E- and L-selectin ligand, HCELL). Although the structural biochemistry of HCELL and PSGL-1 is well characterized, the relative capacity of these molecules to mediate L-selectin-dependent adhesion has not been explored. In this study, we examined under shear stress conditions L-selectin-dependent leukocyte adhesive interactions mediated by HCELL and PSGL-1, both as naturally expressed on human HC membranes and as purified molecules. By utilizing both Stamper-Woodruff and parallel-plate flow chamber assays, we found that HCELL displayed a 5-fold greater capacity to support L-selectin-dependent leukocyte adherence across a broad range of shear stresses compared with that of PSGL-1. Moreover, L-selectin-mediated leukocyte binding to immunopurified HCELL was consistently >5-fold higher than leukocyte binding to equivalent amounts of PSGL-1. Taken together, these data indicate that HCELL is a more avid L-selectin ligand than PSGL-1 and may be the preferential mediator of L-selectin-dependent adhesive interactions among human HCs in the bone marrow.

Sequence analysis of hemagglutinin and nucleoprotein genes of measles viruses isolated in Korea during the 2000 epidemic

To characterize the genetic properties of currently circulating measles viruses in Korea, the complete nucleotide sequences of hemagglutinin (H) protein and nucleoprotein (N) genes of Korean viruses were analyzed. The entire genes of H and N were directly amplified by RT-PCR from each clinical specimen and sequenced. Sequence analyses of H and N genes indicated that all Korean viruses had a high degree of homology (>99.8%) when compared with each other. The Korean viruses differed from other wild-type viruses by as much as 6.8% in the H gene and 6.5% in the N gene at the nucleotide level. The deduced amino acid variability was up to 6.4% for the H protein and up to 6.5% for the N protein. Phylogenetic analyses of nucleotide sequences and deduced amino acid sequences of the H and N genes revealed that all Korean viruses were grouped into the clade H1.

Molecular mechanisms underlying anti-tumor promoting activities of heat-processed Panax ginseng C.A. Meyer

Recently, there have been considerable efforts to search for naturally occurring substances that can inhibit, reverse, or retard the multi-stage carcinogenesis. A wide array of phenolic substances derived from edible and medicinal plants have been reported to possess anticarcinogenic and antimutagenic activities and in many cases, the chemopreventive activities of phytochemicals are associated with their anti-inflammatory and/or antioxidative properties. Panax ginseng C.A. Meyer cultivated in Korea has been widely used in traditional herbal medicine for the treatment of various diseases. Certain fractions or purified ingredients of ginseng have been shown to exert anticarcinogenic and antimutagenic activities. Our previous studies have revealed that the methanol extract of heat-processed Panax ginseng C.A. Meyer attenuates the lipid peroxidation in rat brain homogenates and is also capable of scavenging superoxide generated by xanthine- xanthine oxidase or by 12-O-tetradecanoylphorbol-13-acetate (TPA) in differentiated human promyelocytic leukemia (HL-60) cells. Topical application of the same extract onto shaven backs of female ICR mice also suppressed TPA-induced skin tumor promotion. Likewise, topical application of ginsenoside Rg3, one of the constituents of heat-treated ginseng, significantly inhibited TPA-induced mouse epidermal ornithine decarboxylase activity and skin tumor promotion. Expression of cyclooxygenase-2 (COX-2) in TPA-stimulated mouse skin was markedly suppressed by Rg3 pretreatment. In addition, Rg3 inhibited TPA-stimulated activation of NF-kappaB and extracellular-regulated protein kinase (ERK), one of the mitogen-activated protein (MAP) kinase in mouse skin and also in cultured human breast epithelial cells (MCF-10A).

The impact of culture isolation of Aspergillus species: a hospital-based survey of aspergillosis

The term "aspergillosis" comprises several categories of infection: invasive aspergillosis; chronic necrotizing aspergillosis; aspergilloma, or fungus ball; and allergic bronchopulmonary aspergillosis. In 24 medical centers, we examined the impact of a culture positive for Aspergillus species on the diagnosis, risk factors, management, and outcome associated with these diseases. Most Aspergillus culture isolates from nonsterile body sites do not represent disease. However, for high-risk patients, such as allogeneic bone marrow transplant recipients (60%), persons with hematologic cancer (50%), and those with signs of neutropenia (60%) or malnutrition (30%), a positive culture result is associated with invasive disease. When such risk factors as human immunodeficiency virus infection (20%), solid-organ transplantation (20%), corticosteroid use (20%), or an underlying pulmonary disease (10%) are associated with a positive culture result, clinical judgment and better diagnostic tests are necessary. The management of invasive aspergillosis remains suboptimal: only 38% of patients are alive 3 months after diagnosis. Chronic necrotizing aspergillosis, aspergilloma, and allergic bronchopulmonary aspergillosis have variable management strategies and better short-term outcomes.

Antiplatelet activity of green tea catechins is mediated by inhibition of cytoplasmic calcium increase

We have previously reported that green tea catechins (GTC) display a potent antithrombotic activity, which might be due to antiplatelet rather than anticoagulation effects. In the current study, we investigated the antiplatelet mechanism of GTC. We tested the effects of GTC on the aggregation of human platelets and on the binding of fluorescein isothiocyanate-conjugated fibrinogen to human platelet glycoprotein (GP) IIb/IIIa. GTC inhibited the collagen-, thrombin-, adenosine diphosphate (ADP)-, and calcium ionophore A23187-induced aggregation of washed human platelets, with 50% inhibitory concentration values of 0.64, 0.52, 0.63, and 0.45 mg/ml, respectively. GTC significantly inhibited fibrinogen binding to human platelet surface GPIIb/IIIa complex but failed to inhibit binding to purified GPIIb/IIIa complex. These results indicate that the antiplatelet activity of GTC may be due to inhibition of an intracellular pathway preceding GPIIb/IIIa complex exposure. We also investigated the effects of GTC on intracellular calcium levels, which are critical in determining the activation status of platelets and on induction of platelet aggregation by thapsigargin, which is a selective inhibitor of the Ca(2+)-ATPase pump. Pretreatment of human platelets with GTC significantly inhibited the rise in intracellular Ca(2+) concentration induced by thrombin treatment, and GTC significantly inhibited the thapsigargin-induced platelet aggregation. We also examined the effect of GTC on the second messenger, inositol 1,4,5-triphosphate (IP(3)). GTC significantly inhibited the phosphoinositide breakdown induced by thrombin. Taken together, these observations suggest that the antiplatelet activity of GTC is be mediated by inhibition of cytoplasmic calcium increase, which leads to the inhibition of fibrinogen-GPIIb/IIIa binding via the activation of Ca(2+)-ATPase and inhibition of IP(3) formation.

Age-related change of neuropeptide Y-immunoreactive neurons in the rat anterior olfactory nucleus

Neuropeptide Y (NPY) is located in the olfactory system, including the olfactory bulb, and is thought to be one of the main neurotransmitters for olfaction. Thus, we examined age-related changes of NPY-immunoreactive (IR) neurons in the rat anterior olfactory nucleus (AON) at various aging stages over a period of 2 years; postnatal months 1 (PM 1), PM 6, PM 12 and PM 24. NPY-IR neurons in the AON were present in the lateral and medial subdivisions at PM 1 and at PM 6 were distributed in all subdivisions of the AON. Prior to PM 12, the NPY-IR neurons showed a tendency to change from bipolar cells with short processes into multipolar cells with long processes. Moreover, the population of NPY-IR neurons and nerve fibers in the AON increased in proportion to age. In particular, the number of NPY-IR neurons increased about 6-fold between PM 1 and PM 3. At PM 24, the number of NPY-IR neurons was much smaller than that at PM 12 and somal size had decreased. It is therefore suggested that the dramatic increase in the number and size of the NPY-IR neurons between PM 1 and PM 3 may be associated with sexual maturation and that the decrease in the number and cell size of the NPY-IR neurons at PM 24 may underlie age-related changes in the olfactory process.

Medullary nephrocalcinosis associated with long-term furosemide abuse in adults

BACKGROUND

The use of furosemide is well recognized as a predisposing factor of nephrocalcinosis in infants. Although furosemide is widely used for various medical conditions in adults, its association with nephrocalcinosis in adults is not well established.

METHODS

We studied 18 consecutive adult patients (male:female ratio 1:17, age range 21-59 years) who habitually took furosemide to control weight or oedema for long periods of time (range 3-25 years). The daily dose of continuous intake of furosemide ranged from 40 to 2800 mg. Nephrocalcinosis was evaluated using renal ultrasonography (US), computed tomography (CT), or kidney biopsies.

RESULTS

Renal US and CT revealed bilateral nephrocalcinosis of the medullary pyramids in 15 (83.3%) out of 18 patients. The duration of furosemide abuse was similar between nephrocalcinosis positive (NC(+)) and nephrocalcinosis negative (NC(-)) groups. The daily dose of furosemide was nearly 10 times higher in the NC(+) group (range 120-2800 mg, mean 538 mg) than the NC(-) group (range 40-80 mg, mean 67 mg). All patients showed variable degrees of renal insufficiency and there was no difference in creatinine clearance between the NC(+) and NC(-) groups (P>0.05). Kidney biopsies performed in three patients showed focal tubulo-interstitial fibrosis and atrophy and calcifications were observed in outer medullary tubulo-interstitium.

CONCLUSIONS

Long-term furosemide abuse can cause medullary nephrocalcinosis in adults, and the risk of developing of nephrocalcinosis seems to be correlated with the daily dose of furosemide. We suggest that long-term furosemide abuse should be suspected in adult patients when medullary nephrocalcinosis is incidentally detected by US or CT.

The hcKrox gene family regulates multiple extracellular matrix genes

The transcription factor cKrox was originally identified as a protein that bound to a negative transcription regulatory element in the murine alpha1(I) collagen promoter. We recently reported the cloning and characterization of human cKrox (hcKrox). Overexpression of hcKrox in NIH3T3 fibroblasts efficiently repressed the promoters of the fibronectin and alpha1(I) collagen genes (70-90%) in transient transfection assays and suppressed the endogenous genes in hcKrox expressing permanent cell lines. We have now isolated genomic clones and cDNAs encoding two novel transcription factors related to hcKrox termed hcKrox-beta and hcKrox-gamma (the original clone is now referred to as hcKrox-alpha). Both contain three kruppel-like zinc-finger DNA binding motifs that are 71-78% identical to those of hcKrox-alpha. The NH(2)-terminus of all three proteins contains a POZ domain, a conserved 120 amino acid motif involved in transcriptional repression and protein dimerization. RT-PCR experiments demonstrate that all three hcKrox family members are expressed in foreskin and dermal fibroblasts. Transient transfection studies in NIH3T3 fibroblasts demonstrate that hcKrox-alpha -beta and -gamma, as well as the murine cKrox-beta homologue, LRF, suppress transcription driven by promoters for the alpha1(I) and alpha2(I) collagen, fibronectin and elastin genes. Electrophoretic mobility shift assays and coimmunoprecipitation studies suggest that homo- and heterodimerization occurs between cKrox family members. Dimer formation is influenced by amino acids in the NH(2)-terminal POZ domain and the Zn(+2)-finger region. Immunoprecipitation studies indicate that cKrox can form heterodimers in solution in the absence of DNA. Thus, a multi-gene family exists that can coordinately regulate several extracellular matrix genes and has the potential to form many heterodimeric transcription factors.

New use of a three-dimensional pellet culture system for human intervertebral disc cells: initial characterization and potential use for tissue engineering

STUDY DESIGN

Human intervertebral disc cells were cultured in a new three-dimensional "pellet culture" system as an alternative to conventional alginate bead microspheres. Histologic, biochemical, and immunohistologic assays were performed to characterize this new culturing method for disc cells. The feasibility of using the pellet culture system to study effects of gene therapy was also assessed.

OBJECTIVES

To characterize a new and simpler, three-dimensional culture system for human intervertebral disc cells and to assess the feasibility of its use for gene therapy and tissue engineering studies.

SUMMARY OF BACKGROUND DATA

The alginate microsphere three-dimensional culture system has been the most utilized culture method for disc cells, but it is technically difficult and has some disadvantages. Recently, the "pellet culture" method, a simpler three-dimensional culture system, was described for bone marrow stromal cells. This simpler method might be useful for in vitro and in vivo studies of disc cells as well as for delivery of exogenous genes.

METHODS

Isolated human intervertebral disc cells were centrifuged at low speeds to form aggregates and allowed to grow as pellets for up to 3 weeks. At various times these pellet cultures were analyzed grossly, histologically, and immunohistologically. Their ability to incorporate [35S]sulfate in their response to TGF-beta1 was also analyzed. The ability of these pellets to deliver and express exogenous genes in vivo was analyzed by implantation of pellet cultures in muscles of SCID mice.

RESULTS

Within several days the intervertebral disc cells were able to form mature three-dimensional aggregates that were each well encapsulated by a fibrous capsule. These pellets successfully synthesized proteoglycan and collagen Type II matrix as determined by histology and immunohistochemistry. In response to TGF-beta1, the pellets increased synthesis of proteoglycan and collagen Type II. When implanted into thigh muscles of SCID mice, the pellets remained aggregated and expressed the beta-galactosidase marker gene in vivo for up to 2 weeks.

CONCLUSIONS

The pellet culture system is a new and technically simple method to culture human intervertebral disc cells. The majority of the human intervertebral disc cells retained their native phenotype in this three dimensional system and expressed a marker gene both in vitro and in vivo. Thus, this pellet system might be useful for in vitro and in vivo biochemical studies as well as for studies involving gene therapy and tissue engineering.

Phylogeny of Alariaceae, Laminariaceae, and Lessoniaceae (Phaeophyceae) based on plastid-encoded RuBisCo spacer and nuclear-encoded ITS sequence comparisons

Concatenated sequences from the plastid-encoded RuBisCo spacer and nuclear-encoded rDNA ITS region of the Alariaceae, Laminariaceae, and Lessoniaceae as currently recognized were used to determine the phylogeny of kelps (Phaeophyceae). Our analyses indicate that all taxa in the Alariaceae, Laminariaceae, and Lessoniaceae form a monophyletic lineage (the Laminariales sensu stricto). The phylogenetic analyses show that the kelps form eight well-supported clades (represented by Egregia, Laminaria, Hedophyllum, Macrocystis, Alaria, Agarum, Ecklonia, and Lessonia) that conform to the tribes of the current morphological classification system of the "advanced" kelps. Our results suggest that the kelps should be classified into eight families rather than the three that are presently used. The interrelationships among the eight lineages were, however, unresolved in the phylogenetic analyses. In all trees, Egregia diverged first and is the sister to the other kelp taxa. Our phylogenetic analyses also indicate that Kjellmaniella and Laminaria do not form a monophyletic group. Taken together, the RuBisCo spacer and rDNA ITS prove useful for understanding the evolutionary history of the advanced kelps and provide a new framework for establishing the systematics of these commercially important brown algae.

1,4-dioxane-fused 4-anilinoquinazoline as inhibitors of epidermal growth factor receptor kinase

The 4-anilinoquinazoline PD 153035 (1) is a potential antitumor agent which acts by inhibiting tyrosine kinase activity of epidermal growth factor receptor (EFGR) via competitive binding at the ATP site of enzyme. A series of cyclic analogues of PD 153035 bearing the 1,4-dioxane ring was prepared by reaction of 6-chloro derivative 5 with several aniline nucleophiles. These were evaluated for their ability to inhibit the EGFR kinase and the growth of primary human tumor cell cultures. All of the new 4-anilinoquinazolines exhibited less potency than PD 153035 against EGFR kinase. However, compounds 2b, 2c, 2e, 2g, and 2h showed higher inhibitory activities than PD 153035 against the growth of A431 tumor cell line. The compound 2b containing 3-chloroaniline ring was as potent as PD 153035 against EGFR kinase and showed about 5.4-fold better potency than PD153035 in the inhibition of growth of A431 cell line with good selectivity.

Synthesis and phosphodiesterase inhibitory activity of new sildenafil analogues containing a carboxylic acid group in the 5'-sulfonamide moiety of a phenyl ring

New sildenafil analogues possessing a carboxylic acid group in the 5'-sulfonamide of the phenyl ring, 9a-l, were prepared from the readily available starting compounds 6a-b and cyclic amines 3-5 in a three-step sequence. In the enzyme assays, it has been shown that all the target compounds 9a-l proved to be more potent in inhibiting phosphodiesterase type 5 (PDE5) than sildenafil by 4-38-fold. The effects on the IC(50) values were investigated by varying the alkoxy group (R) of the phenyl ring, the sulfonamide type (X), and the length of the methylene chain linking the carboxylic acid, and the results were discussed in detail. From this study, we have clearly demonstrated that introduction of a carboxylic acid group to the 5'-sulfonamide moiety of the phenyl ring greatly enhanced PDE5 inhibitory activity, probably by mimicking the phosphate group of cGMP. The piperidinyl propionic acid derivative 9i, which showed the highest PDE5 inhibitory activity and comparable to better selectivity over PDE isozymes in comparison with sildenafil, has been selected for more detailed biological investigations.

Inactivating mutations of KILLER/DR5 gene in gastric cancers

BACKGROUND & AIMS

The KILLER/death receptor (DR)5 has been identified as a potent inducer of apoptosis, and mapped to chromosome 8p21-22, showing frequent allelic loss in gastric cancer. The p53-induced apoptosis is an important biological process to prevent the development of cancer, and is mediated in part by expression of KILLER/DR5 only in cells with wild-type p53 protein, but not in those lacking p53 function. The aim of this study was to determine whether genetic alterations of KILLER/DR5 could be involved in the tumorigenesis of gastric cancer.

METHODS

We analyzed the genetic alterations of KILLER/DR5 and p53 in 43 gastric cancers and the loss of function of KILLER/DR5 mutants, detected in this study.

RESULTS

We found 3 KILLER/DR5 missense mutations (7%), and 2 of them showed allelic loss in the remaining allele. Interestingly, all the mutants inhibit apoptotic cell death in transfection studies. We also found 6 p53 mutations (14%). Interestingly, the tumors containing the KILLER/DR5 mutation did not carry the p53 mutation.

CONCLUSIONS

These results suggest that inactivation of KILLER/DR5 caused by mutations of KILLER/DR5 may be one of the possible escaping mechanisms against KILLER/DR5-mediated apoptosis and that inactivating mutation of KILLER/DR5 may contribute to the development or progression of a subset of gastric cancers.

Uncertainty analysis of absolute concentration measurement with continuous-wave cavity ringdown spectroscopy

To evaluate the uncertainty of concentration measurement using cavity ringdown spectroscopy, we analytically derived expressions for uncertainty for parameters, such as temperature, laser frequency, and ringdown time deviation, from the model equation. The uncertainties that are due to systematic errors in a practical cavity ringdown system were assessed through an experimental study of the PQ(35) transition in an A band of molecular oxygen. We found that, except for the line strength that is regarded as a reference value independent of the measurement, the laser frequency jitter is the largest uncertainty source in the system. Some practical requirements for minimizing the uncertainty in concentration measurements are discussed. We also demonstrated determination of the line strength of the PQ(35) transition line of oxygen to be 8.63(3) x 10(-27) cm(-1) with a relative uncertainty of less than 0.4%.

Protection by pyruvate against transient forebrain ischemia in rats

Pyruvate has a remarkable protective effect against zinc neurotoxicity. Because zinc neurotoxicity is likely one of the key mechanisms of ischemic brain injury, the neuroprotective effect of pyruvate was tested in a rat model of transient forebrain ischemia. Control experiments in mouse cortical culture showed that pyruvate almost completely blocked zinc toxicity but did not attenuate calcium-overload neuronal death. Adult rats subjected to 12 min forebrain ischemia exhibited widespread zinc accumulation and neuronal death throughout hippocampus and cortex 72 hr after reperfusion. However, rats injected intraperitoneally with sodium pyruvate (500-1000 mg/kg) within 1 hr after 12 min forebrain ischemia showed almost no neuronal death. In addition, the mortality was markedly decreased in the pyruvate-protected groups (3.8%) compared with the NaCl-injected control group (58.1%). The neuroprotective effect persisted even at 30 d after the insult. The spectacular protection without noticeable side effects makes pyruvate a promising neuroprotectant in human ischemic stroke.

Proteolytic processing of the p2/nucleocapsid cleavage site is critical for human immunodeficiency virus type 1 RNA dimer maturation

Differences in virion RNA dimer stability between mature and protease-defective (immature) forms of human immunodeficiency virus type 1 (HIV-1) suggest that maturation of the viral RNA dimer is regulated by the proteolytic processing of the HIV-1 Gag and Gag-Pol precursor proteins. However, the proteolytic processing of these proteins occurs in several steps denoted primary, secondary, and tertiary cleavage events and, to date, the processing step associated with formation of stable HIV-1 RNA dimers has not been identified. We show here that a mutation in the primary cleavage site (p2/nucleocapsid [NC]) hinders formation of stable virion RNA dimers, while dimer stability is unaffected by mutations in the secondary (matrix/capsid [CA], p1/p6) or a tertiary cleavage site (CA/p2). By introducing mutations in a shared cleavage site of either Gag or Gag-Pol, we also show that the cleavage of the p2/NC site in Gag is more important for dimer formation and stability than p2/NC cleavage in Gag-Pol. Electron microscopy analysis of viral particles shows that mutations in the primary cleavage site in Gag but not in Gag-Pol inhibit viral particle maturation. We conclude that virion RNA dimer maturation is dependent on proteolytic processing of the primary cleavage site and is associated with virion core formation.

Comparison of contrast-enhanced fundamental imaging, second-harmonic imaging, and pulse-inversion harmonic imaging

RATIONALE AND OBJECTIVES

To investigate the feasibility of recent contrast-specific ultrasound techniques in depicting vascular flow and the effects of changing the output power of the transducer and insonation mode on contrast enhancement, the authors performed an experimental study with a flow phantom.

METHODS

While changing the mechanical index and the sound insonation mode (continuous and intermittent), images were obtained with three contrast-enhanced ultrasound techniques: fundamental, second-harmonic, and pulse-inversion harmonic imaging (PIHI) after a bolus injection of microbubble contrast agent. The images were compared on a time-intensity curve.

RESULTS

In assessing fixed flow (10 cm/s), PIHI showed the best depiction of flow signal. In intermittent scanning, increases in the mechanical index caused stronger flow signals and longer enhancement duration in all techniques. However, continuous scanning revealed poor depiction of flow signal regardless of the technique or changes in the mechanical index because of significant bubble destruction.

CONCLUSIONS

Microbubble-enhanced PIHI with intermittent scanning at a high mechanical index can depict vascular flow highly effectively without shortening the duration of enhancement.

Induction of cell cycle arrest and apoptosis in human breast cancer cells by quercetin

Quercetin, a widely distributed bioflavonoid, has been shown to induce growth inhibition in certain cancer cell types. In the present study we have pursued the mechanism of growth inhibition in MCF-7 human breast cancer cells. Quercetin treatment resulted in the accumulation of cells specifically at G2/M phase of the cell cycle. Mitotic index measured by MPM2 staining clearly showed that cells were transiently accumulated in M phase, 24 h after treatment. The transient M phase accumulation was accompanied by a transient increase in the levels of cyclin B1 and Cdc2 kinase activity. However, 24 h or longer treatment caused a marked accumulation of cells in G2 instead of M phase. Levels of cyclin B1 and cyclin B1-associated Cdc2 kinase activity were also decreased. We also found that quercetin markedly increased Cdk-inhibitor p21CIP1/WAF1 protein level after treatment for 48 h or longer, and the induction of p21CIP1/WAF1 increased its association with Cdc2-cyclin B1 complex, however, up-regulation of p53 by quercetin was not observed. Quercetin also induced significant apoptosis in MCF-7 cells in addition to cell cycle arrest, and the induction of apoptosis was markedly blocked by antisense p21CIP1/WAF1 expression. The present data, therefore, demonstrate that a flavonoid quercetin induces growth inhibition in the human breast carcinoma cell line MCF-7 through at least two different mechanisms; by inhibiting cell cycle progression through transient M phase accumulation and subsequent G2 arrest, and by inducing apoptosis.

Laser Doppler flowmetry for monitoring traumatized teeth

Laser Doppler Flowmetry (LDF) has been shown to be valuable in monitoring revascularization of immature incisors following severe dental trauma. Several investigators have demonstrated the ability of LDF to record blood flow signals from vital tooth pulps. In this case report, LDF was used for a 7-year-old child patient following a severe luxation of tooth #9. During follow-up examinations the traumatized tooth was unresponsive to traditional vitality testing during the first 6 months; however, LDF indicated that revascularization had occurred much sooner. Until recently, CO2 ice has been the most effective method for sensitivity testing in trauma cases such as presented here. In this case, LDF gave us the assurance that we could defer invasive care during a critical time period when root canal therapy might have been initiated for this child patient.