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At least 865 records · Page 48Linked to original sources
PubMed2006

Melanin content and MC1R function independently affect UVR-induced DNA damage in cultured human melanocytes.

Malignant transformation of melanocytes leads to melanoma, the most fatal form of skin cancer. Ultraviolet radiation (UVR)-induced DNA photoproducts play an important role in melanomagenesis. Cutaneous melanin content represents a major photoprotective mechanism against UVR-induced DNA damage, and generally correlates inversely with the risk of skin cancer, including melanoma. Melanoma risk is also determined by susceptibility genes, one of which is the melanocortin 1 receptor (MC1R) gene. Certain MC1R alleles are strongly associated with melanoma. We hereby present experimental evidence for the role of two melanoma risk factors, constitutive pigmentation, as assessed by total melanin, eumelanin and pheomelanin contents, and MC1R genotype and function, in determining the induction and repair of DNA photoproducts in cultured human melanocytes after irradiation with increasing doses of UVR. We found that total melanin and eumelanin contents (MC and EC) correlated inversely with the extent of UVR-induced growth arrest, apoptosis and induction of cyclobutane pyrimidine dimers (CPD), but not with hydrogen peroxide release in melanocytes expressing functional MC1R. In comparison, melanocytes with loss-of-function MC1R, regardless of their MC or EC, sustained more UVR-induced apoptosis and CPD, and exhibited reduced CPD repair. Therefore, MC, mainly EC, and MC1R function are independent determinants of UVR-induced DNA damage in melanocytes.

Adult↗
PubMed1995

Reduction of ultraviolet-induced skin cancer in mice by topical application of DNA excision repair enzymes.

Ultraviolet (UV) irradiation produces two major photoproducts, cyclobutane pyrimidine dimers (CPD) and (6-4) photoproducts. T4 endonuclease V (T4N5), which specifically repairs CPD, is encapsulated in liposomes. A previous study has shown that UV-induced carcinogenesis in mice was suppressed by the application of T4N5 liposomes. To confirm the suppressive effect, we applied T4N5 liposomes with repeated UVB exposure to hairless mice. At the end of the experiment, mice treated with T4N5 liposomes had 3.5 +/- 1.3 tumors per mouse, and control mice had 6.3 +/- 2.8 tumors per mouse. In addition, the incidence of tumors was reduced in T4N5 liposome-treated mice compared with controls. The pathological diagnosis of the tumors was not significantly different between two groups. Immunohistochemical analysis of p53 protein in UV-induced tumors showed that nearly half of the tumors in both groups were positive. When the biopsied normal-looking skin taken during the experiment was stained with p53 antibody, there was no significant difference of the timing of p53 protein expression between the control mice and T4N5 liposome-treated mice. These results confirmed that CPD plays a pivotal role in UV carcinogenesis, although the molecular mechanisms of the suppression by T4N5 liposomes should be further clarified.

Administration, Topical↗
PubMed1996

Higher cyclobutane pyrimidine dimer and (6-4) photoproduct yields in epidermis of normal humans with increased sensitivity to ultraviolet B radiation.

Cyclobutane pyrimidine dimer (CPD) and (6-4) photoproduct induced in the epidermis of five Japanese volunteers exposed to ultraviolet (UVB) radiation were measured with monoclonal antibodies specific for each photoproduct. The volunteers comprised two individuals who are sensitive to solar irradiation (low minimal erythema dose [MED]) and three who are less sensitive. The yields of CPD and (6-4) photoproduct were within similar ranges after 1 MED or 3 MED doses. The yields of both photoproducts after the same dose of irradiation (120 mJ/cm2) were higher in UV-sensitive individuals than in less sensitive individuals. By 24 h after irradiation, an average of 60% of CPD had been removed after the 1 MED dose, 27% after the 3 MED dose and 34% after 120 mJ/cm2. The (6-4) photoproduct was removed within 24 h, independently of the dose of UVB tested. These data suggest that DNA photoproducts participate in initiating UVB-induced erythema, and partially explain why individuals with higher sensitivity to UVB have a higher risk of UV-induced skin cancer.

Adult↗
PubMed2005

Sorting of major cargo glycoproteins into clathrin-coated vesicles.

The AP-1 and AP-2 complexes are the most abundant adaptors in clathrin-coated vesicles (CCVs), but clathrin-mediated trafficking can still occur in the absence of any detectable AP-1 or AP-2. To find out whether adaptor abundance reflects cargo abundance, we used lectin pulldowns to identify the major membrane glycoproteins in CCVs from human placenta and rat liver. Both preparations contained three prominent high molecular-weight proteins: the cation-independent mannose 6-phosphate receptor (CIMPR), carboxypeptidase D (CPD) and low-density lipoprotein receptor-related protein 1 (LRP1). To investigate how these proteins are sorted, we constructed and stably transfected CD8 chimeras into HeLa cells. CD8-CIMPR localized mainly to early/tubular endosomes, CD8-CPD to the trans Golgi network and CD8-LRP1 to late/multivesicular endosomes. All three constructs redistributed to the plasma membrane when clathrin was depleted by siRNA. CD8-CIMPR was also strongly affected by AP-2 depletion. CD8-CPD was moderately affected by AP-2 depletion but strongly affected by depleting AP-1 and AP-2 together. CD8-LRP1 was only slightly affected by AP-2 depletion; however, mutating an NPXY motif in the LRP1 tail caused it to become AP-2 dependent. These results indicate that all three proteins have AP-dependent sorting signals, which may help to explain the relative abundance of AP complexes in CCVs. However, the relatively low abundance of cargo proteins in CCV preparations suggests either that some of the APs may be empty or that the preparations may be dominated by empty coats.

Amino Acid Sequence↗
PubMed2005

Swedish dental hygienists' preferences for workplace improvement and continuing professional development.

UNLABELLED: The present study examined factors for workplace improvement and continuing professional development (CPD) for Swedish dental hygienists. Seventy-one per cent of 577 randomly selected members of Sweden's Dental Hygienist Association responded to a questionnaire. The chi-square test, Spearman's rank correlation, and multiple stepwise logistic regression modelling were used in the statistical analysis. The results showed that dental hygienists having more than 10 sick days annually and with a strong commitment to their work increased the preference for workplace improvements, such as peer recognition of dental hygienists' professional qualifications, clinical process quality, and time for reading research articles and participating in projects. In addition, dental hygienists in the 41-52 age group were associated with workplace improvements. This is in contrast to the factors that decreased preferences for workplace improvements: clear work roles, a 1-year training programme, a male clinic manager, and working in the private sector. Practicing dental hygiene in the public sector and lifestyle factors were the most influential determinants for a strong interest in CPD. CONCLUSION: Workplaces should observe people that are obviously committed to their work, those with many sick days, and those in a specific age group, as they indicate different preferences for workplace improvements. CPD seems to be a lower priority than workplace improvements for Swedish dental hygienists.

Adult↗
PubMed2000

Segmentation of carotid artery in ultrasound images: method development and evaluation technique.

Segmentation of carotid artery lumen in two-dimensional and three-dimensional ultrasonography is an important step in computerized evaluation of arterial disease severity and in finding vulnerable atherosclerotic plaques susceptible to rupture causing stroke. Because of the complexity of anatomical structures, noise as well as the requirement of accurate segmentation, interactions are necessary between observers and the computer segmentation process. In this paper a segmentation process is described based on the deformable model method with only one seed point to guide the initialization of the deformable model for each lumen cross section. With one seed, the initial contour of the deformable model is generated using the entropy map of the original image and mathematical morphology operations. The deformable model is driven to fit the lumen contour by an internal force and an external force that are calculated, respectively, with geometrical properties of deformed contour and with the image gray level features. The evaluation methodology using distance-based and area-based metrics is introduced in this paper. A contour probability distribution (CPD) method for calculating distance-based metrics is introduced. The CPD is obtained by generating contours of the lumen using a set of possible seed locations. The mean contour can be compared to a manual outlined contour to provide accuracy metrics. The variance computed from the CPD can provide metrics of local and global variability. These metrics provide a complete performance evaluation of an interactive segmentation algorithm and a means for comparing different algorithm settings.

Algorithms↗
PubMed1996

Similarity among the Drosophila (6-4)photolyase, a human photolyase homolog, and the DNA photolyase-blue-light photoreceptor family.

Ultraviolet light (UV)-induced DNA damage can be repaired by DNA photolyase in a light-dependent manner. Two types of photolyase are known, one specific for cyclobutane pyrimidine dimers (CPD photolyase) and another specific for pyrimidine (6-4) pyrimidone photoproducts[(6-4)photolyase]. In contrast to the CPD photolyase, which has been detected in a wide variety of organisms, the (6-4)photolyase has been found only in Drosophila melanogaster. In the present study a gene encoding the Drosophila(6-4)photolyase ws cloned, and the deduced amino acid sequence of the product was found to be similar to the CPD photolyase and to the blue-light photoreceptor of plants. A homolog of the Drosophila (6-4)photolyase gene was also cloned from human cells.

Amino Acid Sequence↗
PubMed2006

Staphylococcus aureus carriage patterns and the risk of infections associated with continuous peritoneal dialysis.

The epidemiology and risks of Staphylococcus aureus carriage in continuous peritoneal dialysis (CPD) patients was studied in a single tertiary-care institution. On outpatient visits samples for culture were routinely taken prospectively from the CPD catheter exit site and the vestibulum nasi. Seventy-five patients with at least one culture positive for S. aureus in this period were included: 43 had genotypically identical S. aureus strains in over 80% of the cultures and were classified as persistent carriers; 32 were intermittent carriers. Persistent carriage was associated with a threefold higher risk for CPD-related infections and sixfold higher rates of vancomycin consumption compared to those for the intermittent carriers. No methicillin or vancomycin resistance was detected.

Adolescent↗
PubMed2004

Superinfection exclusion in duck hepatitis B virus infection is mediated by the large surface antigen.

Superinfection exclusion is the phenomenon whereby a virus prevents the subsequent infection of an already infected host cell. The Pekin duck hepatitis B virus (DHBV) model was used to investigate superinfection exclusion in hepadnavirus infections. Superinfection exclusion was shown to occur both in vivo and in vitro with a genetically marked DHBV, DHBV-ClaI, which was unable to establish an infection in either DHBV-infected ducklings or DHBV-infected primary duck hepatocytes (PDHs). In addition, exclusion occurred in vivo even when the second virus had a replicative advantage. Superinfection exclusion appears to be restricted to DHBV, as adenovirus, herpes simplex virus type 1, and vesicular stomatitis virus were all capable of efficiently infecting DHBV-infected PDHs. Exclusion was dependent on gene expression by the original infecting virus, since UV-irradiated DHBV was unable to mediate the exclusion of DHBV-ClaI. Using recombinant adenoviruses expressing DHBV proteins, we determined that the large surface antigen mediated exclusion. The large surface antigen is known to cause down-regulation of a DHBV receptor, carboxypeptidase D (CPD). Receptor down-regulation is a mechanism of superinfection exclusion seen in other viral infections, and so it was investigated as a possible mechanism of DHBV-mediated exclusion. However, a mutant large surface antigen which did not down-regulate CPD was still capable of inhibiting DHBV infection of PDHs. In addition, exclusion of DHBV-ClaI did not correlate with a decrease in CPD levels. Finally, virus binding assays and confocal microscopy analysis of infected PDHs indicated that the block in infection occurs after internalization of the second virus. We suggest that superinfection exclusion may result from the role of the L surface antigen as a regulator of intracellular trafficking.

Animals↗
PubMed2003

Effect of damage type on stimulation of human excision nuclease by SWI/SNF chromatin remodeling factor.

To investigate the repair of different types of DNA lesions in chromatin, we prepared mononucleosomes containing an acetylaminofluorene-guanine adduct (AAF-G), a (6-4) photoproduct, or a cyclobutane pyrimidine dimer (CPD) and measured the repair of these lesions by reconstituted 6-factor human excision nuclease. We find that incorporation into nucleosomes inhibits the repair of CPD more severely than repair of the AAF-G adduct and the (6-4) photoproduct. Equally important, we find that SWI/SNF stimulates the removal of AAF-G and (6-4) photoproduct but not of CPD from nucleosomal DNA. These results shed new light on the low rate of repair of CPDs in human cells in vivo.

2-Acetylaminofluorene↗
PubMed2003

Contrast sensitivity improves after brimonidine therapy in primary open angle glaucoma: a case for neuroprotection.

AIMS: To determine the visual outcome following initiation of brimonidine therapy in glaucoma. METHODS: 16 newly diagnosed previously untreated glaucoma patients were randomly assigned to either timolol 0.5% or brimonidine 0.2%. Visual acuity, contrast sensitivity (CS), visual fields, intraocular pressure (IOP), blood pressure, and heart rate were evaluated at baseline and after 3 months. RESULTS: IOP reduction was similar for both groups (p<0.05). Brimonidine improved CS; in the right eye at 6 and 12 cpd (p=0.043, p=0.017); in the left eye at 3 and 12 cpd (p=0.044, p=0.046). Timolol reduced CS at 18 cpd in the right eye (p=0.041). There was no change in any other measured parameters. CONCLUSION: Glaucoma patients exhibit improved CS on initiation of brimonidine therapy.

Adrenergic alpha-Agonists↗
PubMed1994

Breast tumors: computer-assisted quantitative assessment with color Doppler US.

PURPOSE: To compare quantified measurements with color Doppler ultrasonography (US) with those obtained with conventional duplex US in the differential diagnosis of suspect lesions in the breast. MATERIALS AND METHODS: A computer-assisted protocol was used to calculate the color pixel density (CPD) and the mean color value (MCV) in US images of breast lesions. These results were compared with conventional results in the examination of 25 patients (aged 29-78 years) with carcinomas and 32 patients (aged 23-73 years) with benign lesions of the breast. RESULTS: The sensitivity of maximum flow velocity in helping identify carcinomas was 60% and the specificity was 70%. In color Doppler US, the sensitivity for MCV in helping identify carcinomas was 92% and the specificity was 78%; for CPD the sensitivity was 64% and the specificity was 91%. Combining MCV and CPD did not improve differentiation. CONCLUSION: Computer-assisted image analysis may be superior to conventional duplex US in helping differentiate between carcinomas and benign lesions.

Adult↗
PubMed2002

Endothelial cells maintain a reduced redox environment even as mitochondrial function declines.

Human umbilical vein endothelial cells (HUVECs) are an endothelial model of replicative senescence. Oxidative stress, possibly due to dysfunctional mitochondria, is believed to play a key role in replicative senescence and atherosclerosis, an age-related vascular disease. In this study, we determined the effect of cell division on genomic instability, mitochondrial function, and redox status in HUVECs that were able to replicate for approximately 60 cumulative population doublings (CPD). After 20 CPD, the nuclear genome deteriorated and the protein content of the cell population increased. This indicated an increase in cell size, which was accompanied by an increase in oxygen consumption, ATP production, and mitochondrial genome copy number and approximately 10% increase in mitochondrial mass. The antioxidant capacity increased, as seen by an increase in reduced glutathione, glutathione peroxidase, GSSG reductase, and glucose-6-phosphate dehydrogenase. However, by CPD 52, the latter two enzymes decreased, as well as the ratio of mitochondrial-to-nuclear genome copies, the mitochondrial mass, and the oxygen consumption per milligram of protein. Our results signify that HUVECs maintain a highly reducing (GSH) environment as they replicate despite genomic instability and loss of mitochondrial function.

Cells, Cultured↗
PubMed2003

Kininase I-type carboxypeptidases enhance nitric oxide production in endothelial cells by generating bradykinin B1 receptor agonists.

Kininase I-type carboxypeptidases convert native kinin agonists for B(2) receptors into B(1) receptor agonists by specifically removing the COOH-terminal Arg residue. The membrane localization of carboxypeptidase M (CPM) and carboxypeptidase D (CPD) make them ideally situated to regulate kinin activity. Nitric oxide (NO) release from human lung microvascular endothelial cells (HLMVEC) was measured directly in real time with a porphyrinic microsensor. Bradykinin (1-100 nM) elicited a transient (5 min) peak of generation of NO that was blocked by the B(2) antagonist HOE 140, whereas B(1) agonist des-Arg(10)-kallidin caused a small linear increase in NO over 20 min. Treatment of HLMVEC with 5 ng/ml interleukin-1beta and 200 U/ml interferon-gamma for 16 h upregulated B(1) receptors as shown by an approximately fourfold increase in prolonged (>20 min) output of NO in response to des-Arg(10)-kallidin, which was blocked by the B(1) antagonist des-Arg(10)-Leu(9)-kallidin. B(2) receptor agonists bradykinin or kallidin also generated prolonged NO production in treated HLMVEC, which was significantly reduced by either a B(1) antagonist or carboxypeptidase inhibitor, and completely abolished with a combination of B(1) and B(2) receptor antagonists. Furthermore, CPM and CPD activities were increased about twofold in membrane fractions of HLMVEC treated with interleukin-1beta and interferon-gamma compared with control cells. Immunostaining localized CPD primarily in a perinuclear/Golgi region, whereas CPM was on the cell membrane. These data show that cellular kininase I-type carboxypeptidases can enhance kinin signaling and NO production by converting B(2) agonists to B(1) agonists, especially in inflammatory conditions.

Bradykinin↗
PubMed2006

Interhemispheric integration at different spatial scales: the evidence from EEG coherence and FMRI.

The early visual system processes different spatial frequencies (SFs) separately. To examine where in the brain the scale-specific information is integrated, we mapped the neural assemblies engaged in interhemispheric coupling with electroencephalographic (EEG) coherence and blood-oxygen-level dependent (BOLD) signal. During similar EEG and functional magnetic resonance imaging (fMRI) experiments, our subjects viewed centrally presented bilateral gratings of different SF (0.25-8.0 cpd), which either obeyed Gestalt grouping rules (iso-oriented, IG) or violated them (orthogonally oriented, OG). The IG stimuli (0.5-4.0 cpd) synchronized EEG at discrete beta frequencies (beta1, beta2) and increased BOLD (0.5 and 2.0 cpd tested) in ventral (around collateral sulcus) and dorsal (parieto-occipital fissure) regions compared with OG. At both SF, the beta1 coherence correlated with the ventral activations, whereas the beta2 coherence correlated with the dorsal ones. Thus distributed neural substrates mediated interhemispheric integration at single SF. The relative impact of the ventral versus dorsal networks was modulated by the SF of the stimulus.

Adult↗
PubMed1978

Application of the critical point dried whole cell technique to the study of animal rhabdoviruses.

The critical point dried (CPD) whole cell technique was applied to the study of the morphogenesis and morphology of rabies virus and vesicular stomatitis virus (VSV) in mouse neuroblastoma and baby hamster kidney (BHK) cells. With the stereoscopic technique, progeny viruses at the cell surface and within the cytoplasm of the CPD whole cells were clearly visualized. The presence of many fine cellular processes and of virus budding from these processes were prominent features of the infected cells. Long strings of virus particles and virus apparently fused into different forms were often seen; a possible mechanism for the formation of these aberrant forms is discussed. Negative staining of the CPD whole cells clearly revealed the detailed structure of virus particles in the process of budding.

Animals↗
PubMed1995

Assessment of right ventricular diastolic function by pulsed Doppler echocardiography in chronic pulmonary disease and pulmonary thromboembolism.

We evaluated right ventricular (RV) diastolic performance in 12 healthy subjects (control), 25 patients with chronic pulmonary diseases (CPD) and 6 patients with chronic pulmonary thromboembolism (PTE). Flow velocity patterns were determined by the pulsed Doppler technique. The values determined included acceleration time (AT), deceleration time (DT), and the ratio of the atrial contraction wave (A) to the rapid filling wave (R) (A/R ratio) from flow velocity patterns in the RV inflow tract. DT was significantly prolonged in the CPD and PTE groups compared with the control group, indicating dysfunction during the early (middle) filling period. The prolongation was marked in those patients with pulmonary hypertension. The A/R ratio was significantly higher in the CPD and PTE groups than in the control group, indicating a decrease in RV compliance. The A/R ratio increased slightly with the increase in the end-diastolic volume index. These results suggested that the pressure overload plays an important role in RV diastolic dysfunction in patients with pulmonary disease, and that preload contributes to the dysfunction.

Aged↗
PubMedDate not supplied

Cytodifferentiation and expression of alpha-smooth muscle actin mRNA and protein during primary culture of aortic smooth muscle cells. Correlation with cell density and proliferative state.

To investigate a possible correlation between cytodifferentiation, proliferation, and actin expression, smooth muscle cells from the 9-week-old rabbit aortic media were enzyme-dispersed into single cells and were plated in primary culture at different initial seeding densities. The volume fraction of myofilaments (Vv myo) in cells seeded moderately densely fell from 39.5% +/- 1.2% in the intact aortic media to 11.5% +/- 1.6% on Day 5, one day before the onset of logarithmic growth. The Vv myo remained low over the next 3 days, then began to rise as the density of cells increased, returning almost to the original levels after confluency and 1.84 cumulative population doublings (CPD). The expression of alpha-smooth muscle actin mRNA followed a similar time course of change, falling from 84.7% +/- 1.2% of total actin mRNA in freshly isolated cells to 54.0% +/- 6.5% on Day 5, returning to 87.5% +/- 0.5% after confluency. In these cultures, the alpha-smooth muscle actin protein content was 93.7% +/- 2.9% of total actin in freshly isolated cells, 68.7% +/- 3.1% on Day 5, and 73.3% +/- 2.5% 3 days after confluency. In densely seeded cultures, the Vv myo and expression of alpha-smooth muscle actin mRNA fell only slightly on Day 5 and rose to original levels upon confluency after 0.33 CPD. However, at the protein level, alpha-smooth muscle actin decreased on Day 5 and remained low on Day 12. The Vv myo, alpha-smooth muscle actin mRNA, and actin protein of sparsely seeded cells fell on Day 5 and then remained low throughout the culture period, including 5 days after confluency (Day 24), when the cells had undergone 5.37 CPD. Cells that were maintained subconfluent but quiescent on Day 7 in culture had the same low Vv myo, low alpha-actin mRNA expression, and low alpha-actin protein content as actively proliferating cells. The results show that Vv myo and alpha-smooth muscle actin mRNA undergo parallel changes during primary culture according to seeding density, but not to replication, and that alpha-smooth muscle actin protein decreases in culture then remains low irrespective of culture conditions.

Actins↗