Altered fibrin architecture is associated with hypofibrinolysis and premature coronary atherothrombosis.

OBJECTIVE: Hypofibrinolysis promotes atherosclerosis progression and recurrent ischemic events in premature coronary artery disease. We investigated the role of fibrin physical properties in this particular setting. METHODS AND RESULTS: Biomarkers of recurrent thrombosis and premature coronary artery disease (CAD) were measured in 33 young post-myocardial infarction patients with angiographic-proven CAD and in 33 healthy volunteers matched for age and sex. Ex vivo plasma fibrin physical properties were assessed by measuring fibrin rigidity and fibrin morphological properties using a torsion pendulum and optical confocal microscopy. The fibrinolysis rate was derived from continuous monitoring of the viscoelastic properties after addition of lytic enzymes. Young CAD patients had a significant increase in plasma concentration of fibrinogen, von Willebrand factor, plasminogen activator inhibitor type 1, and lipoprotein(a) as compared with controls (P<0.05). Fibrin of young CAD patients was stiffer (P=0.002), made of numerous (P=0.002) and shorter fibers (P=0.04), and lysed at a slower rate than that of controls (P=0.03). Fibrin stiffness was an independent predictor for both premature CAD and hypofibrinolysis. CONCLUSIONS: This first detailed study of clot properties in such a group of patients demonstrated that abnormal plasma fibrin architecture is an important feature of both premature CAD and fibrinolysis rate. The determinants of this particular phenotype warrant further investigation.

A structural and dynamic investigation of the facilitating effect of glycoprotein IIb/IIIa inhibitors in dissolving platelet-rich clots.

Glycoprotein IIb/IIIa (GP IIb/IIIa) inhibitors were shown recently to facilitate the rate and the extent of pharmacological thrombolysis. However, their synergistic potential with rtPA in dissolving thrombotic vaso-occlusions is not fully understood. We have therefore developed a dynamic and structural approach for analysis of fibrinolysis to assess the inhibiting effect of platelets and the facilitating effect of GPIIb/IIIa inhibitors in dissolving platelet-rich clots (PRCs). Fluorescent rtPA was used to study the architecture of PRCs, to follow the progression of the rtPA binding front, and to measure the lysis-front velocity using confocal microscopy. Fibrinolysis resistance of PRCs was related to a reduction of both rtPA binding and lysis-front velocities of platelet-rich areas compared with platelet-poor areas (2.4 +/- 0.2 versus 3.5 +/- 0.4 microm/min for rtPA binding velocity, P=0.04, and 1.2 +/- 0.6 versus 2.8 +/- 0.2 microm/min for lysis-front velocity, P=0.008, in platelet-rich and platelet-poor areas, respectively). Fibrinolysis appeared heterogeneous, leaving platelet-rich areas un-lysed. Adding pharmacological concentrations of abciximab (0.068 micromol/L) or eptifibatide (1 micromol/L) before clotting decreased the average surface of platelet-rich areas by 64% (P=0.0005) and 72% (P=0.0007), respectively. The resulting equalization of rtPA binding rate and rtPA binding-front velocity between platelet-rich and platelet-poor areas led to a 3-fold increase of the lysis-front velocity in platelet-rich areas of either abciximab-PRC (P=0.006) or eptifibatide-PRC (P=0.03). The overall lysis rate of treated-PRC was increased by 74% compared with control-PRC (P<0.01). These results demonstrate that fibrinolysis resistance of PRCs is related primarily to the heterogeneity in the clot structure between platelet-rich and platelet-poor areas. GP IIb/IIIa inhibitors facilitate the rate and the extent of fibrinolysis by improving rtPA binding velocity and, subsequently, the lysis rate in platelet-rich areas. These findings provide new insights on the synergistic potential of GP IIb/IIIa inhibitors and fibrinolytic agents.

Effects of Abciximab on the architecture of platelet-rich clots in patients with acute myocardial infarction undergoing primary coronary intervention.

BACKGROUND: Abciximab plus aspirin improves the TIMI 3 flow rate of the infarct-related artery in patients treated with either percutaneous coronary intervention or thrombolysis. The present study investigated whether the reperfusion efficacy of abciximab relates to modifications of clot architecture in patients admitted for acute myocardial infarction (AMI). METHODS AND RESULTS: A total of 23 AMI patients in the Abciximab before Direct angioplasty and stenting in Myocardial Infarction Regarding Acute and Long term follow-up (ADMIRAL) trial received, in a double-blind fashion, either abciximab (n=13) or placebo (n=10) before primary stenting. Viscoelastic (G' in dyne/cm(2)) and morphological (mean platelet aggregate surface area [SAG] in micrometer(2)) indexes of ex vivo platelet-rich clots (PRC) were assessed in a double-blind fashion before and after the bolus administration of abciximab or placebo. G' and SAG reflect the mechanical and morphological impact of activated platelets on the PRC fibrin network, respectively. Abciximab administration reduced G' by 63% (P=0.0001) and SAG by 65% (P=0.0007), and no effect was seen in the placebo group. These abciximab-related changes increased fibrin exposure as a consequence of the platelet-aggregate surface reduction and may have improved endogenous fibrinolysis. These effects were identified in all patients, independent of previous heparin administration. CONCLUSIONS: Abciximab dramatically reduces platelet aggregate size and increases the fibrin accessibility of ex vivo PRC in AMI patients. These modifications could participate in the better coronary artery patency observed with abciximab.

Acute release of plasminogen activator inhibitor-1 in ST-segment elevation myocardial infarction predicts mortality.

BACKGROUND: A few studies have suggested that von Willebrand factor (vWF) or plasminogen activator inhibitor-1 (PAI-1) can be associated with outcomes of acute coronary syndromes. The present study was designed to assess the acute release of these markers in ST-segment elevation myocardial infarction (STEMI) and their relations to death. METHODS AND RESULTS: In 153 consecutive patients with STEMI, vWF and PAI-1 antigens were measured on admission (H0) and 24 hours later (H24). At 30 days, the death rate was 7.2%. Heart failure (Killip stage > or =3) on admission was present in 13.7% of patients. The acute release of PAI-1 (H24-H0, in ng/mL) and of vWF (H24-H0, in %) was dramatically higher in patients who died than in those who survived (46.9+/-26.3 versus -0.6+/-2.8 ng/mL, P=0.0001 and 65.8+/-20.0% versus 10.0+/-5.1%, P=0.004 for PAI-1 and vWF, respectively) and in patients developing heart failure compared with those without (24.8+/-10.1 versus -1.1+/-3.3 ng/mL, P=0.004 and 47.3+/-11.0% versus 8.1+/-5.6%, P=0.005 for PAI-1 and vWF, respectively). The release of PAI-1 correlated weakly with the left ventricular ejection fraction (R=-0.195, P=0.01) and the peak of troponin (R=0.149, P=0.045). Postangioplasty TIMI-3 flow and the acute release of PAI-1 were the only 2 independent predictors of death at 30 days. CONCLUSIONS: The acute release of vWF and PAI-1 over the first 24 hours of STEMI is associated with death and heart failure. The acute rise of PAI-1 is also a strong independent predictor of death at 30 days.

Disaggregation of in vitro preformed platelet-rich clots by abciximab increases fibrin exposure and promotes fibrinolysis.

The glycoprotein IIb/IIIa receptor inhibitor abciximab has been shown to facilitate the rate and the extent of pharmacological thrombolysis with recombinant tissue plasminogen activator (rtPA) in patients with acute myocardial infarction. However, the underlying mechanisms remain not fully determined. We sought to demonstrate that this facilitating effect of abciximab could be related to its potential to modify the clot architecture and the clot physical properties. Compared with fibrin-rich clots, platelets dramatically modified the in vitro properties of the fibrin network, leading to a significant increase of the permeability (K(s)) and the viscoelasticity (G') indexes but also leading to the appearance of platelet aggregates (surface area [S.ag]). These modifications resulted in a 2.6-fold decrease of the fibrinolysis rate when rtPA (1 nmol/L) was added before the initiation of clotting. Adding aspirin (100 microgram/mL) or abciximab (0.068 micromol/L) before the clotting of platelet-rich clots (PRCs) lowered K(s) by 50% and 70%, respectively (P<0.01), G' by 41% and 66%, respectively (P<0.01), and S.ag by 32% and 61%, respectively (P<0.01). As a consequence, the lysis speed was increased by 21% with aspirin (P<0.01) and 45% with abciximab (P<0.01). However, unlike aspirin, permeation of preformed PRCs with abciximab (0.068 micromol/L) decreased G' (37%, P<0.01), K(s) (35%, P<0.001) and S.ag (25%, P=NS) and resulted in a 27% (P<0.01) increase of the lysis speed when abciximab and rtPA (0.2 micromol/L) were simultaneously permeated. This effect was found to be time dependent and was observed only with early permeation, starting within the first 10 minutes of clotting. These changes in the physical properties of the PRC architecture suggest that fibrin is removed from the platelet-fibrin aggregates and reexposed into the surrounding fibrin network, increasing rtPA access to fibrin and therefore the fibrinolysis rate. The superiority of abciximab over aspirin in accelerating fibrinolysis of forming and preformed PRCs is related to its ability to modulate the interactions of fibrinogen and fibrin with platelets. These findings provide new mechanistic information on reperfusion therapy.

Abnormal fibrin clot architecture in nephrotic patients is related to hypofibrinolysis: influence of plasma biochemical modifications: a possible mechanism for the high thrombotic tendency?

Porosity, viscoelasticity and morphological properties of plasma fibrin from 16 nephrotic patients and 16 healthy volunteers were compared. Nephrotic patients were characterized by formation of tight and rigid plasma fibrin gels which resulted in a slower rate of fibrin lysis studied either under pressure-driven permeation or diffusional transport of fibrinolytic agents. These latter findings indicated that both abnormal fibrin network conformation and abnormal fibrin fiber structure were involved in hypofibrinolysis. Albumin supplementation up to 40 mg/ml partially restored normal fibrin architecture and increased the rate of fibrinolysis in these patients. Multiparametric analysis showed that nephrotic patients were mainly characterized by a low plasma albumin level (R = -0.85), a low albumin to fibrinogen ratio (R = -0.89) and a high resistance to lysis (R = -0.82). High triglycerides level was the only plasma modification related to the slower fibrin lysis rate (R = -0.54). High fibrin rigidity (G') was the only fibrin parameter simultaneously related to the nephrotic state (R = 0.75) and the lysis resistance (R = -0.71). After eliminating the effects of age, albumin and fibrinogen levels, low fibrin porosity (Ks) and low fiber mass-length ratio (mu) were the main features of the nephrotic state. These findings are discussed in relation to both the pathophysiology of thrombotic complications in nephrotic syndrome and their pharmacological prevention.

Morphological and biochemical changes in old rat muscles: effect of increased use.

Male Wistar rats were strength and swim trained during a substantial period of old age to determine the influence of aging and activity on the histochemical and metabolic characteristics of a predominantly slow (soleus) and a predominantly fast (plantaris) skeletal muscle. Strength training counteracted the age-related atrophy of the fibers and the age-induced changes in fiber-type distribution of both muscles. Swim training, on the other hand, was without any effect on these parameters. The activity of both mitochondrial and cytoplasmic enzymes became lower with aging in the soleus muscle, whereas only the activity of the cytoplasmic enzymes became lower in the plantaris. Strength training reduced the aerobic capacity of both muscles, whereas swim training had the opposite effect. Aging induced a lower glycogen concentration of the lateral gastrocnemius muscle. This was avoided by swim training. The phosphocreatine and adenosine 5'-triphosphate concentrations were unchanged with aging but became higher with strength training. The activity pattern, therefore, seems to have a considerable influence on the age-related modification of the histochemical and metabolic characteristics of skeletal muscles of the rat. The effect, however, is related to the recruitment pattern of the fiber populations and the form of activity.

Comparative quantitative study of Ki-67 antibody staining in 78 B and T cell malignant lymphoma (ML) using two image analyser systems.

Total Ki-67 stained area percentage was studied in 32 B and 46 T malignant lymphomas (ML) using two different image analyser systems (TAS, Leitz; SAMBA TM 2005, TITN) respectively. The total Ki-67 area percentage was highly correlated to the number of Ki-67 positive cellular profiles (B-ML, r = 0.93; T-ML, r = 0.88), indicating that area percentage is a reliable alternative method to the manual cell counting. Image analysis allows quicker measurements, appropriate to large and strictly lymphomatous regions. The cell image processor (SAMBA TM 2005, TITN) linked to a color video camera was more suitable for immunohistochemical sections and allowed more automated and faster measurements than the texture analyser (TAS, Leitz) linked with a black and white camera. Alkaline phosphatase technique with fast red as chromogen was more suitable for the detection of Ki-67 stained area by thresholding than peroxidase technique with aminoethylcarbazol or with diaminobenzidine as chromogens. Significant differences were found between low and high grade in B and T ML according to the Kiel classification (mean values +/- SD of 7.7 +/- 3.8% and 16.6 +/- 6.2% in B-ML and of 10.2 +/- 7.9% and 25.6 +/- 16.3% in T-ML respectively). In follicular B-ML, considering follicular areas only, values were comparable to high grade ML; angioimmunoblastic-lymphadenopathy-like (AILD-type) T-ML belonging to low grade ML showed similar values to pleomorphic T-ML with medium and/or large cells belonging to high grade ML.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphometric analysis of dermal collagen fibers in normal human skin as a function of age.

A quantitative study of dermal collagen as a function of age was carried out by computerized digital image analysis. Fast Green-Syrius Red stained sections were obtained of skin biopsies taken from the upper inner arm of 33 healthy women and 38 healthy men. The Leitz texture Analysis System (Leitz-TAS) and mathematical morphology (Serra, 1982) were used for the evaluation of the data. Collagen was studied in the superficial dermis and also in the reticular dermis using the same program. There were significant correlations, firstly between the percentage of collagen measured by the morphometric method and the concentration of collagen analysed biochemically (microg/mm(2) of tissue section) (r = 0.79, p < 0.001) and secondly between the decreased concentration of collagen and age (r = 0.58, p < 0.05). The morphometrical measurements have shown that the relative percentage of collagen bundles (surface of collagen fibers as a function of the dermal area analyzed) was 93.35% in the superficial dermis and 89.2% in the reticular dermis. Although this value is higher than the chemically determined ratio of collagen to other proteins (over 70%), this may be due to the relatively uniform distribution pattern of (type I and III) collagen through the dermis covering most other components of the skin. As the collagen fiber density per unit dermal surface did not change with age, the decrease in collagen content of the skin may be ascribed to the loss of about 6% of dermal mass per decade (Branchet, 1990), although large individual variations exist. The histogram of the diameter distribution of collagen fiber bundles of the reticular dermis showed thinner diameters in persons between 20 and 40 years of age than in older persons. The histogram of the distribution of interfiber spaces did not show any variation with age in the superficial dermis, while in the reticular dermis there was a predominance of smaller interspaces in persons older than 50 years.

Elastic fibers in normal human skin. Variations with age: a morphometric analysis.

A quantitative study of dermal elastic fibers was carried out by computerized digital image analysis. Sections of skin biopsies taken from the upper inner arm of 33 healthy women and 38 healthy men were stained by a selective procedure for elastic fibers. The Leitz texture analysis system (Leitz-Tas) and mathematical morphology were used for the evaluation of the data. Distinct programs were used for the vertical superficial elastic fibers and for the mature elastic fibers of the reticular dermis. For elastic fibers of the superficial dermis there was no significant variation with age or sex for total area occupied by the fibers or for the total number of fibers per unit skin area or total fiber length. The distribution of the relative fiber number as a function of their length showed that about 80% of the fibers had a length of 0-20 microm, with no detectable age- or sex-dependent variation. The distribution of fiber number frequency as a function of fiber diameter did not show any significant variation with sex or age, either. The relative area of mature elastic fibers increased significantly with age after the sixth decade of life. The total number (Nt) of these fibers did not show however any significant variation with age or sex: Nt per mm(2) of skin surface was 3220+/-660 (S.D.). We found for all age groups a significant increase of total fiber length by comparing persons between 20 and 30 years with those above 60 years. There was, however, no significant variations according to age or sex for the frequency distribution of mature elastic fiber length and diameter. As a significant decrease with age of the dermal thickness was also found in males and females, the loss of elastic fibers with age is mainly due to a loss of skin thickness (skin volume) with age. This loss is about 30% at 50 years and nearly 50% at 80 years. Loss of skin elasticity with age can be due to loss of cells (fibroblasts), to a decrease of their biosynthetic activity and to qualitative modifications of extracellular matrix macromolecules.

2D modelling of nucleus location in lymphoid cells.

Cytologists have seldom made a quantitative study of the location of the nucleus within the cell. We have mathematically defined three parameters in two dimensions: the number of distinct cell/nucleus boundary contacts (Ncon), the length of such contacts (Lcon), and the degree of nucleus location eccentricity (Ecc), expressed as a function of the greatest distance between cell and nucleus boundaries, and of the nucleus/cytoplasm ratio (N/C). Based on the analysis of 68 circular or elongated cell and nucleus models, we identify 21 topographies, for a range of N/C values between 20% and 70% and for a range of cell surface area values between 2900 and 6700 pixels on a hexagonal raster (256 x 256). Beyond 70%, a maximum of two topographies may be distinguished; below 20%--a figure nearer a nucleolus-nucleus ratio--the relevance and reliability of the approach are subject to some doubt. We conclude that the problem of describing the location of one structure within another remains dependent on N/C. The method has been applied to 59 lymphoid cells on smear photographs recognized internationally by hematologists as characteristic of lymphoid diseases. The results show the robustness of the combination of four criteria in relation to the overall elongation of nucleus or cell profiles, and to significant contour irregularities. The method has demonstrated its ability to describe and quantify the eccentric position of the nucleus within plasmocytic lymphocytes, and provide a further degree of discrimination.

New cementum formation induced by cyclosporin A: a histological, ultrastructural and histomorphometric study in the rat.

Cyclosporin A (CsA), a widely used immunosuppressive agent, is known to induce gingival overgrowth; 30 mg/kg/d of CsA were administrated orally in young and adult male Sprague-Dawley rats. The same number of rats received oil-based vehicle solution. After 4, 9, 14 and 19 wk of CsA or vehicle administration 3 control and 3 experimental rats were anaesthetized and tissues fixed by an intracardiac perfusion of fixative solution. Upper and lower jaws were dissected, demineralized and processed for Epon inclusion. Histological examination revealed the presence of large amounts of new cementum (NC) covering extensive areas of the acellular extrinsic fibre cementum (AEFC) in all the root surfaces. NC was particularly abundant at the cervical third of the roots facing the gingival connective tissue, where it occurred as layers, spurs or in both configurations. NC was characterized by its irregular outline, globular body content and infrequent presence of incremental lines. Histomorphometric evaluation by semi-automatic image analysis indicated that the volume and the external surface of NC spurs were 2.86-6.49 and 1.29-1.97-fold increased comparative to those of the AEFC covering the same root areas. Electron microscopy revealed that NC was a functional tissue with insertion of collagen fibres perpendicularly to the long axis of the root. It can be concluded that under some experimental conditions formation of abundant amounts of NC can be achieved and that these results must be taken into account for a new approach in the treatment of periodontal disease.

Cyclosporin A-induced gingival overgrowth in the rat: a histological, ultrastructural and histomorphometric evaluation.

This investigation was undertaken to further study cyclosporin A (CsA)-induced gingival overgrowth. Thirty mg/kg/d of vehicle or CsA solutions were given orally to 6-wk-old male Sprague-Dawley rats. After 4, 9, 14 and 19 wk 2 control and 2 experimental rats were anaesthetized, tissues fixed by intracardiac perfusion of fixative solution and jaws processed for Epon inclusion. Histological and ultrastructural studies conducted in a gingival portion (free gingiva) revealed the presence of hyalinization areas and of multinucleated cells (MCs) containing collagen fibrils (connective tissue), of amorphous areas and disorders of keratinization (epithelia). Histomorphometric evaluation indicated that in the CsA rats the mean cross-sectional area of the free gingiva was 2.52-fold increased compared to the controls. The connective tissue comprised 41.43% of this area (instead of 31.49% in controls). Additional histomorphometric evaluation was performed in 3 groups of free gingival portions: control (C group), CsA-non-respondent (CsA-nR) and CsA-respondent (CsA-R). The cross-sectional gingival areas studied were slightly lower than the mean area of all the control sites previously defined (groups C and CsA-nR) or showed the higher degrees of enlargement (CsA-R). In the CsA-R group the mean cross-sectioned area of the vessel profiles was increased and the number of fibroblast profiles decreased. In the CsA-nR group the number of vessel profiles and that of MCs profiles were increased. In the epithelia of the CsA-R group were increased (a) keratinized epithelia: thickness; thickness of the inner and of the outer compartments; surface area of spinous cell profiles; (b) oral gingival epithelium: number of cell layers (inner compartment); (c) oral sulcular epithelium: surface area of granular cell profiles; (d) junctional epithelium: thickness; number of cell layers. These results indicate that (a) the CsA induced modifications are not limited to enlarged gingiva (b) the overgrowth of the GCT is the result of a vasodilatation and of an increase in the volume of the extracellular matrix and (c) the increase of the epithelial thickness is mainly the result of a cell hypertrophy in the keratinized epithelia and of a cell hyperplasia in the junctional epithelium.

Maintenance of new cementum formed during cyclosporin A administration after suspension of the treatment.

The aim of the present investigation was to examine if new cementum (NC) formed during cyclosporin A (CsA) administration was maintained after suspension of the treatment. Thirty mg/kg/d of CsA were given to 3 male Sprague-Dawley rats. Three control rats received oil-based vehicle solution. Nine wk later the drug and vehicle administration were stopped and the rats continued to be fed with the same standard laboratory diet and water ad libitum for 5 months. The rats were anaesthetized, the tissues fixed by intracardiac perfusion of fixative solution and the mandibles processed for Epon inclusion. Histological, histomorphometric and ultrastructural analysis revealed that (a) NC covered extensive areas of the root surfaces; its structural characteristics were identical to those observed in the rats killed during CsA administration. (b) collagen fibres of the adjacent connective tissue were functionally inserted into the NC. (c) In the presence of cervical NC spurs the extent of the apical downgrowth of the junctional epithelium, measured parallel to the cemento-dentinal junction, was decreased (up to 64%) compared to the one occurring in areas devoid of NC deposits. These results suggest that (a) NC deposition and its functional relations with the adjacent connective tissue are not reversible after cessation of CsA treatment and (b) in the presence of cervical NC spurs the amount of connective tissue attachment on the root surfaces is increased.

Nucleoli and AgNOR proteins in 32 cases of primary breast carcinoma. Spatial pattern of interactions between 50 clinical and histometric criteria.

The purpose of this paper is to analyze a method allowing selection of the best morphometric criterion for quantifying AgNOR proteins under conventional observation conditions by light microscopy. We determined 50 parameters for 32 cases of primary breast carcinoma. For each case, three 100-nucleus samples (tumor center and periphery on a Giemsa-stained, 3-microns tumor section, periphery on a silver-stained section) were quantified. Distribution-free multidimensional data analysis was used to explore the geometric significance of the coefficient of correlation. This analysis revealed a clinical message linked with the largest "nucleolar structure" (nucleolus or AgNOR clump) per nucleus on the tumor periphery. Tumor recurrence or death correlated only with the coefficient of variation of the "nucleolar/nuclear" ratio of the greatest clump of AgNORs per nucleus periphery (CVRSa). The prognostic value of CVRSa is independent of that of conventional criteria, such as age, tumor size, Scarff-Bloom-Richardson grading and lymph node status. The largest AgNOR clump per nucleus may prove to be a further practical prognostic predictor.

Ageing of the skin: study of elastic fiber network modifications by computerized image analysis.

We quantitated the skin elastic fibers of the papillary and reticular dermis using specific staining procedure followed by automated computerized image analysis. Fifty skin biopsies of patients consulting for cardiovascular risk factors were studied. The following parameters were estimated: surface area (% of total surface), length, and number of fibers as a function of age. The evaluation of the skin elastic fiber system showed no significant trend with age in the number of elastic fibers per unit area in the superficial or deep dermis. We found, however, a continuous increase with age in the relative surface area, and the length of the elastic fiber system. These results can best be interpreted as a continuous apposition of elastic-type material to the preexisting fibers by skin fibroblasts. This material may well be of a different composition than young elastin, for instance enriched in structural glycoproteins (microfibrils), lipids and calcium as found in the elastic fibers of aorta and lung. Such quantitative modifications may explain the decrease in skin elasticity, and the continuous increase in stained fibers.

Computer analysis of platelet volumes.

A Coulter ZB was used to measure electronically the size of circulating platelets collected from normal subjects. EDTA or ACD were used for collection. Three mathematical models of volume histograms were tested. The lognormal law model is clearly unacceptable if all particles are used, but is applicable in the particle range of 3-15 mu 3. The model of a mixture of two lognormal populations closely approximates observed volume distribution. The model of three lognormal populations also approximates well when the largest volume population is divided into two subpopulations. The contribution of these results to an understanding of heterogeneity in platelet size is discussed.

Nucleolar topography of nuclei in histologic sections. Application of a nonparametric approach to the study of breast cancer and non-Hodgkin's lymphoma.

The position of the nucleolus within a near-convex nuclear profile was defined, without taking stereology into account, in terms of two distances, P and G, where P = pi p2/SN, G = pi 2/SN, p and g being, respectively, the smallest and greatest distances between the center of the nucleolus (considered as a disk) and the superficial nuclear membrane, and SN being the surface area of the nucleus. Nuclear elongation (ND) was defined by the ratio ND = SN/A, where A is the area of the largest inscribed disk. The nucleolus-nucleus ratio RS = Sn/SN (i.e., the surface of the nucleolus over that of the nucleus) describes the size of the nucleolus. A four-class classification of nucleolar topography was then developed from the model of an ellipsoid nuclear profile (1 less than ND less than 2.5), for which the probability that a randomly located nucleolus (with RS less than 0.23) will be classified as central (G less than 2.5 and 0.40 less than or equal to P less than 1) is less than 0.14, as paracentral (G less than 2.5 and 0.23 less than or equal to P less than 0.40) is less than 0.13, as "transversely eccentric" (G less than 2.5 and P less than 0.23) is less than 0.10 and as "longitudinally eccentric" (G greater than or equal to 2.5) is greater than 0.66. This theoretical distribution into four classes was compared to that of nuclear profiles in four cases of breast cancer and in typical cases of immunoblastic, centroblastic and Burkitt's non-Hodgkin's lymphomas. The findings illustrate the ability of this nonparametric method to indicate characteristic nucleolar locations in relation to the number of nucleoli, their size and their nuclear profile elongation.

Two statistical approaches to nuclei shape and size in a morphometric description of lymph node sections in non-Hodgkin's lymphoma.

An attempt is made to evaluate more clearly the potential contribution of quantitative nuclear profile shape and size measurements to lymph node section histologic description in 70 cases of non-Hodgkin's lymphoma (NHL). The area of nuclear profiles and five nonredundant and size-free shape indices were measured using the THECLA program on a Leitz Texture Analysis System (Leitz-TAS). Two statistical approaches were applied, known respectively as "parametric," (first statistical moments of variable distributions over samples of 200 nuclear profiles) and "nonparametric," which are percentages of nuclear profiles distributed into five "cytological" classes that are defined by shape: round (A), elongated (B), kidney shaped (C), irregular (D) and cleaved (E) nuclear profiles. Both statistical approaches provide proper overall discrimination of the eight histological categories identified with reasonable reliability by pathologists. Above all, the present report discusses the ability of a set of parametric and nonparametric variables to describe NHL cell populations, in an objective and meaningful way, according to nuclei shape. A method of synthesizing multidimensional correlations (CORICO program) is proposed in support of the discussion. Also, the specific descriptive power of each of the variables is described; in particular, it is concluded that there is a close link between the shape and size of the nuclear profiles of the cells.