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1.
2.
Carolien J. Bouma Wiro J. Niessen Karel J. Zuiderveld Elma J. Gussenhoven Max A. Viergever 《Medical image analysis》1997,1(4):363-377
One prerequisite for standard clinical use of intravascular ultrasound imaging is rapid evaluation of the data. The main quantities to be extracted from the data are the size and the shape of the lumen. Until now, no accurate, robust and reproducible method to obtain the lumen boundaries from intravascular ultrasound images has been described. In this study, 21 different (semi-)automated binary-segmentation methods for determining the lumen are compared with manual segmentation to find an alternative for the laborious and subjective procedure of manual editing. After a preprocessing step in which the catheter area is filled with lumen-like grey values, all approaches consist of two steps: (i) smoothing the images with different filtering methods and (ii) extracting the lumen by an object definition method. The combination of different filtering methods and object definition methods results in a total of 21 methods and 80 experiments. The results are compared with a reference image, obtained from manual editing, by use of four different quality parameters—two based on squared distances and two based on Mahalanobis distances. The evaluation has been carried out on 15 images, of which seven are obtained before balloon dilation and eight after balloon dilation. While for the post-dilation images no definite conclusions can be drawn, an automated contour model applied to images smoothed with a large kernel appears to be a good alternative to manual contouring. For pre-dilation images a fully automated active contour model, initialized by thresholding, preceded by filtering with a small-scale median filter is the best alternative for manual delineation. The results of this method are even better than manual segmentation, i.e. they are consistently closer to the reference image than the average distance of all individual manual segmentations. 相似文献
3.
Keratinocyte-derived growth factors play a role in the formation of hypertrophic scars 总被引:17,自引:0,他引:17
Niessen FB Andriessen MP Schalkwijk J Visser L Timens W 《The Journal of pathology》2001,194(2):207-216
In predisposed individuals, wound healing can lead to hypertrophic scar or keloid formation, characterized by an overabundant extracellular matrix. It has recently been shown that hypertrophic scars are accompanied by abnormal keratinocyte differentiation and proliferation, and significantly increased acanthosis, compared with normal scars. This study addressed the question of whether the development of normal and hypertrophic scars is regulated by differences in the growth factor profiles of both the epidermis and the dermis. The presence of interleukin-1alpha (IL-1alpha), IL-1beta, tumour necrosis factor-alpha (TNF-alpha), platelet-derived growth factor (PDGF), transforming growth factor-beta1 (TGF-beta1), and basic fibroblast growth factor (bFGF) was investigated in biopsies taken from breast reduction scars at 3 and 12 months following surgery. The samples were analysed by immunohistological methods and categorized as scars that remained hypertrophic (HH), became normal (HN) or remained normal after 12 months (NN). The epidermal expression of IL-1alpha was significantly increased in NN scars compared with HN and HH scars 3 and 12 months following operation, whereas the dermal expression showed no difference. PDGF was significantly increased in the dermis of normal scars after 3 months and in both the epidermis and the dermis of hypertrophic scars after 12 months. IL-1beta, TNF-alpha, TGF-beta and bFGF showed no differences. It is hypothesized that impaired production of keratinocyte-derived growth factors, such as IL-1alpha, leads to a decrease in the catabolism of the dermal matrix, whereas augmented epidermal PDGF production leads to increased formation of the dermal matrix in hypertrophic scars. These observations support the possibility that the epidermis is involved in preventing the formation of hypertrophic scars. 相似文献
4.
Calcium ionophore-induced acrosome reaction correlates with fertilization rates in vitro in patients with teratozoospermic semen 总被引:5,自引:3,他引:5
The aim of this study was to determine the relationship between calcium
ionophore A23187-induced acrosome reaction (AR) and sperm fertilizing
ability. Semen samples remaining after preparation for standard IVF were
studied in 109 patients who had sperm concentrations > or =20 x
10(6)/ml. Ionophore-induced AR was performed on motile spermatozoa selected
by centrifugation on a Percoll gradient. Semen analysis was performed using
standard methods. Patients with higher (>50%, n = 76) fertilization
rates had significantly higher ionophore-induced AR than patients with
lower (<50%, n = 33) fertilization rates (49 +/- 14 versus 38 +/- 21%, P
< 0.05). When the data from all patients were analysed by logistic
regression, only the percentage sperm motility in insemination medium and
ionophore-induced AR were significantly related to fertilization rates.
Similar results were also obtained when the data from a subgroup of
patients with poor (<15% normal) sperm morphology were analysed.
However, when patients with normal sperm morphology > or =15% were
analysed separately, only sperm count and the percentage of spermatozoa
with progressive motility in semen were significantly related to
fertilization rates. In conclusion, ionophore- induced AR was significantly
related to fertilization rates in vitro mainly in patients with
teratozoospermic semen. Tests for ionophore- induced AR may provide
additional information about sperm fertilizing ability but may not indicate
specific defects of the physiological AR.
相似文献
5.
Stein TP; Oram-Smith JC; Leskiw MJ; Wallace HW; Long LC; Leonard JM 《The American journal of physiology》1976,230(5):1321-1325
6.
Interchromosomal duplications of the adrenoleukodystrophy locus: a phenomenon of pericentromeric plasticity 总被引:13,自引:5,他引:13
Eichler EE; Budarf ML; Rocchi M; Deaven LL; Doggett NA; Baldini A; Nelson DL; Mohrenweiser HW 《Human molecular genetics》1997,6(7):991-1002
A 9.7 kb segment encompassing exons 7-10 of the adrenoleukodystrophy (ALD)
locus of the X chromosome has duplicated to specific locations near the
pericentromeric regions of human chromosomes 2p11,10p11, 16p11 and 22q11.
Comparative sequence analysis reveals 92-96% nucleotide identity,
indicating that the autosomal ALD paralogs arose relatively recently during
the course of higher primate evolution (5-10 million years ago). Analysis
of sequences flanking the duplication region identifies the presence of an
unusual GCTTTTTGC repeat which may be a sequence-specific integration site
for the process of pericentromeric- directed transposition. The breakpoint
sequence and phylogenetic analysis predict a two-step transposition model,
in which a duplication from Xq28 to pericentromeric 2p11 occurred once,
followed by a rapid distribution of a larger duplicon cassette among the
pericentromeric regions. In addition to facilitating more effective
mutation detection among ALD patients, these findings provide further
insight into the molecular basis underlying a pericentromeric-directed
mechanism for non- homologous interchromosomal exchange.
相似文献
7.
Hypertrophic scar formation is associated with an increased number of epidermal Langerhans cells 总被引:11,自引:0,他引:11
The exact pathogenesis of hypertrophic scar and keloid formation is still unknown and a good therapy to prevent or treat these scars is lacking. Because immunological processes seem to be important in excessive scar formation, immunological cells and parameters were studied in a standardized breast reduction wound-healing model in the present study. Standardized scar samples were taken from infra-mammary breast reduction scars, 3 and 12 months following surgery. The samples were investigated for their number of mast cells, Langerhans cells, T-lymphocytes, and macrophages, and the presence of interleukin-4 (IL-4) and counter-regulating interferon-gamma (gamma-IFN), in relation to the scar's clinical appearance--normal or hypertrophic. In this study, hypertrophic scar formation was significantly associated with an increased number of epidermal Langerhans cells (p=0.0001) and significantly (p<0.05) increased expression of epidermal IL-4. No relationship was found between mast cell, T-lymphocyte and macrophage numbers or gamma-IFN staining and the formation of normal or hypertrophic scars. These results, combined with previous observation of abnormal keratinocyte behaviour in this context, indicate that the epidermal immune barrier plays an important role in the development of hypertrophic scars. 相似文献
8.
Labetoulle M Goujard C Frau E Rogier H Niessen F Furlan V Lantz O Lecointe D Delfraissy JF Offret H 《Journal of acquired immune deficiency syndromes (1999)》1999,22(3):228-234
We prospectively studied the incidence of cytomegalovirus (CMV) retinitis in 93 patients treated with highly active antiretroviral therapy (HAART) containing a protease inhibitor (PI), during a median follow-up period of 24 months. The median initial CD4+ count was 22 cells/microl (range, 1-311 cells/microl), and the median plasma HIV viral load was 5.1 log10 copies/ml (range, 2.4-6.4 log10 copies/ml). The fundus was examined monthly in patients with a history of CMV retinitis or an initial CD4+ count <50 cells/microl and every 3 months in the other patients. Of patients with previously controlled CMV retinitis, 1 of 7 relapsed. In addition, 6 of 59 patients with a CD4+ count <50 cells/microl and no history of CMV retinitis before starting PI therapy developed CMV retinitis. Of them, 3 had at least one relapse during follow-up. CD4+ counts were <40 cells/microl at the time of primary or recurrent CMV retinitis, except in two cases (147 cells/microl and 203 cells/microl). In conclusion, the incidence of CMV retinitis was 0.091 per patient-year among study subjects with advanced HIV infection who were receiving HAART (95% confidence interval [CI], 0.037-0.145). The time to progression of CMV retinitis (mean, 215 days; 95% CI, 113-317 days) was longer than reported before widespread use of PIs. 相似文献
9.
Clarke GN; Bourne H; Hill P; Johnston WI; Speirs A; McBain JC; Baker HW 《Human reproduction (Oxford, England)》1997,12(4):722-726
Donor insemination (DI) using cryopreserved semen commenced at The Royal
Women's Hospital in 1976. Over the next 15 years we performed 5953
treatment cycles to achieve 816 pregnancies (13.7% per cycle) and 706 live
births. In-vitro fertilization (IVF) using donor spermatozoa commenced in
1986. Over the next 5 years we performed 303 treatment cycles for 185
couples. Including subsequent transfer of cryopreserved embryos, a total of
33% of couples achieved a successful pregnancy by IVF. Statistical analysis
indicated that, for DI pregnancies, the most important semen variable was
the percentage post-thaw motility, whilst for normal fertilization in IVF
it was the pre-freeze motility. These results may be explained by the
compensatory effects of post-thaw processing of spermatozoa for IVF, but
not for DI in our clinic.
相似文献
10.
Giroud C van der Leer T van der Heijden R Verpoorte R Heeremans CE Niessen WM Vander Greef J 《Planta medica》1991,57(2):142-148
The alkaloids from CINCHONA LEDGERIANA shoot cultures and from CINCHONA ROBUSTA shoot cultures and a compact globular structure (CGS) culture were analyzed by thermospray liquid chromatography/mass spectrometry (TSP LC/MS). Because of the relative stability of the alkaloids under TSP discharge ionization conditions, a protonated molecule was observed in the mass spectra with hardly any fragmentation. When the reference compounds were available, the knowledge of the molecular mass and of the retention time was sufficient to identify most of the alkaloids. HPLC with UV photodiode-array detection complemented LC/MS perfectly by providing information about the aromatic part of the alkaloids (structure and substitution pattern). New alkaloids detected in CINCHONA IN VITRO cultures were 5-methoxytryptamine and corynantheal. In order to determine whether 5-methoxytryptamine was a precursor of the methoxylated quinolines, this indole was incubated with secologanin and several CINCHONA ROBUSTA crude protein extracts. Under all conditions tested, the coupling of 5-methoxytryptamine with secologanin remained unsuccessful. Only tryptamine condensed with secologanin to yield strictosidine. These results indicate that CINCHONA cells are able to methoxylate simple indoles like tryptamine and that 5-methoxytryptamine is very likely not used for the subsequent biosynthesis of the methoxylated quinolines. 相似文献