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Y Collan

Publications and source records attributed to Y Collan.

At least 55 records · Page 3Linked to original sources
PubMed1997

The reproducibility of nuclear morphometric measurements in invasive breast carcinoma.

The intraobserver and interobserver reproducibility of computerized nuclear morphometry was determined in repeated measurements of 212 samples of invasive breast cancer. The influence of biological variation and the selection of the measurement area was also tested. Morphometrically determined mean nuclear profile area (Pearson's r 0.89, grading efficiency (GE) 0.95) and standard deviation (SD) of nuclear profile area (Pearson's r 0.84, GE 0.89) showed high reproducibility. In this respect, nuclear morphometry equals with other established methods of quantitative pathology and exceeds the results of subjective grading of nuclear atypia in invasive breast cancer. A training period of eight days was sufficient to produce clear improvement in consistency of nuclear morphometry results. By estimating the sources of variation it could be shown that the variation associated with the measurement procedure itself is small. Instead, sample associated variation is responsible for the majority of variation in the measurements (82.9% in mean nuclear profile area and 65.9% in SD of nuclear profile area). This study points out that when standardized methods are applied computerized morphometry is a reproducible and reliable method of assessing nuclear atypia in invasive breast cancer. For further improvement special emphasize should be put on sampling rules of selecting the microscope fields and measurement areas.

Breast Neoplasms↗
PubMed1997

PROGNOSTICATION OF BREAST CANCER BY MULTIVARIATE METHODS.

Three multivariate prognostic models based on Cox's regression were tested in terms of how they predicted prognosis in a material of 134 patients with breast cancer. The multivariate models all incorporated tumor size, mitotic activity index (MAI), and axillary lymph node status in their formulas, and were originally produced through studies on different patient materials. The predictive behavior of MAI was also tested separately in the same material. The multivariate models gave roughly parallel predicted percentages of survival at two years (CV=5.2%), but showed clearly greater variation later (12.3% and 24.4% at 5 and 9 years, respectively). The results were more uniform between the multivariate models, than between the prediction by MAI and the multivariate models. The variation between repeated estimates was smaller within multivariate models than within the estimation of one of their components (MAI). We found the use of the multivariate models easy. However, traditional hospital practice does not necessarily favor the use of multivariate models, although they seem to group patients more reliably than single prognostic features.

Journal Article↗
PubMed1996

A quantitative morphometrical study of neuron degeneration in the substantia nigra in Parkinson's disease.

We studied the pigmented neurons of the substantia nigra (SN) from 8 controls and 20 patients with Parkinson's disease (PD) using a computerized morphometric methodology. On the basis of neuronal topography, several anatomic regions were outlined in the SN. In these subregions the area, perimeter, diameter of the cell bodies and cell numbers were measured and were counted in the controls and PD patients. The measurements were made at the level of the exit of the third cranial nerve from the brain stem. In PD patients, when the whole SN was considered, the mean area, mean perimeter and diameter of the pigmented cell bodies were significantly reduced by 35%, 20% and 21% respectively from the control mean values. Regionally, the pigmented neuron area in the medial ventral part (VM), medial dorsal part (DM), lateral ventral part (VL), lateral dorsal part (DL) and pars lateralis part (PL) showed a significant reduction of 33-41% as compared to controls. In these subregions, a significant decrease in PD patients from the control mean values was seen both in the pigmented neuron perimeter, by 19-26%, and the diameter by 19-25%. This decrease in cell size suggests that, in PD patients, the remaining pigmented neurons in the SN are in a process of degeneration and atrophy. In PD patients the number of pigmented neurons in the whole SN decreased about 76% from control values. Evaluation of the influence of cell size on the apparent quantity of cells in sections indicates, however, that in PD patients the impact of true loss of pigmented neurons is far more dramatic than the impact of their decrease in size.

Aged↗
PubMed1996

Basics of quantitative polymerase chain reaction: 2. Electrophoresis and quantitation of polymerase chain reaction products.

The performance of agarose and polyacrylamide (PAGE) gels in quantitating polymerase chain reaction (PCR) amplified c-erbB2 and p53 gene sequences (213 and 133 base pairs, respectively) was studied by applying image analysis on photographed ethidium bromide stained gels. The 5 mm thick agarose gels were more insensitive than the 1 mm thin PAGE gels and already started to show saturation effects within a narrow concentration range. The explanation is the greater dilution of band-associated products within the volume of the gel and the inefficient penetration of exciting UV light through the gel. Such effects produced inconsistency and dramatic variations in the band ratio estimates. In the system used by us, agarose electrophoresis and also electrophoresis using 5 mm thick PAGE gels have only a limited value in quantitation of PCR products with the band density ratios, but both can be used well in qualitative work. The far thinner (1 mm) PAGE gels, which did not markedly absorb UV light, performed better in the light of band density ratio estimates. The linear or approximately linear range of concentrations was wider. The coefficient of variation of band ratio, when estimated from the same gels, after loading them with aliquots of identical DNA from several PCR amplified tubes, was in the range of 4%. The absolute values of band densities had a more remarkable variation (than 4%) in both agarose and PAGE gels. Our recommendation is that quantitation of PCR products be done with band density ratio estimates, and in thin PAGE gels.

Base Sequence↗
PubMed1996

Mitotic count in breast cancer. The influence of training on performance.

Two medical laboratory histotechnologists were trained on mitotic counting for 6 months and 1 year. The training included detailed theoretical education on mitotic counts and microscopy sessions with a motivated pathologist. Most of the training time, however, was used for mitotic counts from a large collection of breast cancer samples. The progress in performance was followed by allowing the technicians to count 20 breast cancer samples several times during the training. The mean value of the mitotic counts of technician 1 varied dramatically during the early phases of training but then stabilized near the levels of technician 2, whose mean values were more constant throughout the training period. Both observers showed changes in the standard deviation and coefficient of variation in the early phases of training but later stabilized at the same level. The proportion of the counting results of the technicians within the 95% confidence limits determined by the performance of already trained, experienced technicians varied considerably at first, but then stabilized at values 0.7 and above. The study showed that training improved the performance in mitotic counting. We suggest that the training of mitotic counts provides the means to achieve economical and reproducible estimates of tumor cell proliferation.

Breast Neoplasms↗
PubMed1996

Immunohistochemical expression of p53 protein, mitotic index and nuclear morphometry in primary malignant melanoma of the skin.

The immunohistochemical expression of the p53 tumor suppressor protein and the nuclear morphometric parameters were studied in 80 primary skin melanomas. The mitotic index was counted in 64 tumors. In 95% of the tumors p53 positive nuclei were detected, but in only 31% of the cases was the proportion of positive nuclei 3% or higher. The mitotic indices and the mean nuclear areas were not significantly different in melanomas with different p53 expression levels. The p53 positive nuclei had a larger mean nuclear area than the p53 negative nuclei. p53 expression did not increase with melanoma thickness. In Cox's stepwise proportional hazards model, the ratio of mean nuclear long and short axis and melanoma thickness had independent prognostic value, while the level of p53 expression, the mitotic index, and the mean nuclear area were not significantly associated with survival. We conclude that the nuclei expressing p53 protein are larger than p53 negative nuclei. The level of immunohistochemical expression of p53 is low in primary skin melanoma, and it is not valuable as a general prognostic marker for this tumor. p53 expression is not associated with melanoma thickness, indicating that high p53 expression is not a late phenomenon in the progression of this tumor.

Adolescent↗
PubMed1996

A molecular and epidemiological study on bladder cancer: p53 mutations, tobacco smoking, and occupational exposure to asbestos.

In this study, we found an unexpected association (crude odds ratio = 2.8; 95% confidence interval = 0.9-8.4) between definite work-related exposure to asbestos and carcinoma of the urinary bladder in a small group of patients (n = 28) initially recruited as referents for an epidemiological feasibility study on the occupational causes of lung cancer. We extended the study by using molecular methods to examine mutations in the p53 tumor suppressor gene in the same cases of bladder cancers. The same number of archival samples of transitional cell carcinoma, mainly of grade 3, were added to the analysis. We failed to show any association between occupational exposure to asbestos and p53 mutations among bladder cancer patients. We observed an increasing occurrence of p53 mutations in nonsmokers (5 of 17, 29%), former smokers (8 of 21, 38%), and current smokers (9 of 16, 56%) in that order; however, this was not statistically significant. The most prevalent type of mutation was G:C to A:T transition. Tumor grade was not associated with the frequency of mutations, but the higher stage (T3-T4) tumors appeared to have mutations more frequently than did the less invasive tumors (T1-T2).

Adult↗
PubMed1995

Cell counts in the substantia nigra: a comparison of single section counts and disector counts in patients with Parkinson's disease and in controls.

The disector (DS) is a method by which it is possible to estimate the density of cells in a volume of tissue, and when associated with Cavalieri's principle, the total number of cells of a neural nucleus. Since the introduction of this method, there has been some uncertainty about the value of cell counts estimated using single section (SS). To compare these two methods, we counted the pigmented neurons in the pars compacta of the substantia nigra (SNpc) in seven normal controls and in four patients with Parkinson's disease (PD), using both single histological sections and the DS. The calculations were performed at two different levels of the substantia nigra. Level I was cut through the colliculus superior and caudal red nucleus, and level II showed the exit of the third cranial nerve in all cases. As methods, the two counts were in close agreement (Pearson's correlation coefficient at levels I and II were r = 0.97 and r = 1.00, respectively, P < 0.001). The correspondence was different in the controls and in the parkinsonian patients, however, as can be judged from the slopes of the average regression lines (0.20 for controls, 0.31 for parkinsonian patients). It is nevertheless evident that once the regression line has been defined. DS counts can be estimated from SS counts when the pigmented neuron numbers are counted in the SNpc. The results suggest that comparisons of pigmented neuron counts made from SS are relevant if the cutting level of the section is well defined, and if section thickness is kept constant.

Adult↗
PubMed1995

Single section and disector counts in evaluating neuronal loss from the substantia nigra in patients with Parkinson's disease.

In order to investigate the correlation between single section (SS) and disector (DS) counts for estimating the pigmented neurons in the pars compacta of the substantia nigra (SNpc), 12 patients with Parkinson's disease (PD) and seven controls were studied. The SS counts were obtained at the level of the exit of the third cranial nerve in the SNpc. The DS counts were made from the whole volume of the SNpc. There was a significant correlation between SS and DS counts (r = 0.94, P < 0.001), suggesting that the methods closely agree. Comparison of SS and DS counts in controls and PD patients showed that the pigmented neurons in PD were decreased by 75% (P < 0.001) and 55% (P < 0.001) in the SS and DS counts, respectively. This study suggests that loss of pigmented neurons from the SNpc in PD can be estimated by either method.

Aged↗
PubMed1995

Basics of quantitative PCR 1: image analysis and quantitation of PCR products.

The reproducibility of quantitative image analytic assessment of agarose gel separated PCR products was tested in a computerised core facility image analysis unit serving several research groups. Routine type use of the instrumentation showed considerable variation (measurements of individuals bands: CV about 20%; ratio measurements: CV about 6.5%). Careful concentration on the methodology improved the result (CV about 9% and 4.5%, respectively). Focusing into the methodology clearly showed that the baseline correction was necessary. The magnification of the image and the width of the measurement window were important variation sources. If these were kept constant, the reproducibility improved remarkably (CVs of 1.69% and 2.90%, respectively). Further analysis showed that the results did not change during the warm up period of the instrumentation. Measurements based on integrated optical density or related variables were well correlated, but did not show linear relation with peak height estimates. The most reproducible results were achieved when the thresholds were placed at the point of 45 degrees inclination of the image density curve of the band, or at the half height points of the curve.

Base Sequence↗
PubMed1995

Nuclear morphometry in breast cancer: the influence of sampling rules and freezing of samples.

We studied nuclear morphometry of human breast cancer with special emphasis on two sources of variation: freezing prior to fixation and selection of measured objects on the basis of different sampling rules. Samples of 147 histologically verified invasive breast cancer cases were examined with a computer-based image overlay drawing system. Thirty-eight of the 147 samples of tissue frozen before embedding in paraffin were analyzed separately. Among the latter we found shrinkage of 35% and 46% (depending on the sampling rule) of the nuclear profile area as compared with samples not frozen before the standard tissue processing. These findings confirm that nuclear morphometry results from frozen and unfrozen tissue are not comparable. Frozen tissue later embedded in paraffin should not be used with prognostication models based on traditionally fixed tissue. In morphometry we applied two sampling rules that differed in the criteria used for selecting nuclei for measurement. We registered a significant difference in nuclear size and in the variation of nuclear size between the two sampling methods. Of the morphometric features studied, nuclear area was affected most. Finally, we examined the two sampling rules in light of the established prognosticators in breast cancer: tumor size, axillary lymph node status, and the Multivariate Prognostic Index (MPI). The two sampling rules resulted in different distributions of morphometric results in the prognostic groups. Our findings emphasize the significance of the sources of variation in nuclear morphometry. They also stress the need for well-standardized morphometric methods in predicting the outcome of breast cancer.

Breast Neoplasms↗
PubMed1994

Axonal reinnervation does not influence Schwann cell proliferation after rat sciatic nerve transection.

We asked whether reinnervating axons are Schwann cell mitogens in vivo as they are in vitro. Left sciatic nerves of 50 Wistar rats were transected. In one-half of the animals, axonal reinnervation from the proximal to the distal stump was allowed to take place, while in the other half, sutures were placed on the transected nerve ends to prevent reinnervation. Samples were collected from 3 days up to 8 weeks after the transection proximally and distally from the point of transection. PCNA-immunostaining was performed on paraffin sections to determine the number of proliferating cells. Axonal reinnervation was followed by Bielschowsky staining and Schwann cell number was determined by counting S-100-immunopositive cells from paraffin sections. In the distal stump Schwann cell proliferation was similar in both experimental groups. There was no statistical evidence of S-100 negative cell proliferation during the study. Proximally to the site of transection the number of small initial axonal sprouts and also the number of Schwann cells increased if the nerve stump had been sutured. In conclusion, although axons may be mitogenic for Schwann cells, axonal reinnervation into the distal stump of the transected peripheral nerve does not influence the proliferation of Schwann cells to a greater extent than other potential effects associated with nerve transection.

Animals↗