Assessing goodness-of-fit of parametric regression models for lifetime data-graphical methods

Graphical methods are often used to check goodness-of-fit of models to data. It is common to plot residuals against a reference distribution so that when the model fits the data, the configuration should be close to a straight line. Since the resemblance to a straight line is often unclear, it has been suggested to add simulated envelopes within which the configuration is expected to lie. The implementation of this method for survival data analysis is not straightforward. In this paper we point out the difficulties which arise in constructing envelopes on residual plots for randomly censored data. Methods are suggested to deal with the problems and evaluated; they are illustrated by simulated data and on a follow-up study of myeloma.

p53 expression is required for thymocyte apoptosis induced by adenosine deaminase deficiency

Adenosine deaminase (ADA, EC 3.5.4.4) is a ubiquitous enzyme in the purine catabolic pathway. In contrast to the widespread tissue distribution of this enzyme, inherited ADA deficiency in human results in a tissue-specific severe combined immunodeficiency. To explain the molecular basis for this remarkable tissue specificity, we have used a genetic approach to study ADA deficiency. We demonstrate that ADA deficiency causes depletion of CD8low transitional and CD4+CD8+ double-positive thymocytes by an apoptotic mechanism. This effect is mediated by a p53-dependent pathway, since p53-deficient mice are resistant to the apoptosis induced by ADA deficiency. DNA damage, known to be caused by the abnormal accumulation of dATP in ADA deficiency, is therefore responsible for the ablation of T-cell development and for the immunodeficiency. The two thymocyte subsets most susceptible to apoptosis induced by ADA deficiency are also the two thymocyte subsets with the lowest levels of bcl-2 expression. We show that thymocytes from transgenic mice that overexpress bcl-2 in the thymus are rescued from apoptosis induced by ADA deficiency. Thus, the tissue specificity of the pathological effects of ADA deficiency is due to the low bcl-2 expression in CD8low transitional and CD4+CD8+ double-positive thymocytes.

Hemodynamic criteria for diagnosis of right ventricular ischemia associated with inferior wall left ventricular acute myocardial infarction

To test the diagnostic value of different hemodynamic indexes for the diagnosis of acute right ventricular (RV) ischemic dysfunction, we studied 2 groups of consecutive patients admitted for an acute left ventricular inferior wall myocardial infarction: 51 patients with (group 1) and 32 patients without (group 2) RV ischemia as determined by coronary angiography. In both groups, we analyzed by right-sided cardiac catheterization right-sided heart pressures, pulmonary capillary wedge pressure, and cardiac index. We also calculated pressure ratios (mean right atrial pressure or RV end-diastolic over pulmonary capillary wedge pressures), pulmonary vascular resistance, and RV stroke work index. We found significant differences (p < 0.01) between the 2 groups when comparing mean right atrial pressure, RV end-diastolic pressure, ratio of these 2 pressures over pulmonary capillary wedge pressure, RV stroke work index, and right atrial and RV pressure waveforms. The best combined sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were found for the right atrial M or W waveform pattern, isolated or combined with a disproportionate elevation of RV end-diastolic over pulmonary capillary wedge pressures (respectively, 92%, 94%, 90%, 87%, and 89%). Volume loading was performed in 27 patients (18 with and 9 without RV ischemia). Right heart pressures and RV stroke work index increased significantly and similarly in both groups. Cardiac index increased significantly only in patients without RV ischemia (p = 0.02). However, volume loading did not significantly modify the diagnostic value of the different hemodynamic criteria studied.(ABSTRACT TRUNCATED AT 250 WORDS)

A skeletal muscle-specific enhancer regulated by factors binding to E and CArG boxes is present in the promoter of the mouse myosin light-chain 1A gene

The mouse myosin light-chain 1A (MLC1A) gene, expressed in the atria of the adult heart, is one of the first muscle genes to be activated when skeletal as well as cardiac muscles form in the embryo. It is also transcribed in skeletal muscle cell lines at the onset of differentiation. Transient transfection assays of mouse skeletal muscle cell lines with DNA constructs containing MLC1A promoter fragments fused to the chloramphenicol acetyltransferase (CAT) gene show that the first 630 bp of the promoter is sufficient to direct expression of the reporter gene during myotube formation. Two E boxes located at bp -76 and -519 are necessary for this regulation. MyoD and myogenin proteins bind to them as heterodimers with E12 protein and, moreover, transactivate them in cotransfection experiments with the MLC1A promoter in nonmuscle cells. Interestingly, the effect of mutating each E box is less striking in primary cultures than in the C2 or Sol8 muscle cell line. A DNA fragment from bp -36 to -597 confers tissue- and stage-specific activity to the herpes simplex virus thymidine kinase promoter in both orientations, showing that the skeletal muscle-specific regulation of the MLC1A gene is under the control of a muscle-specific enhancer which extends into the proximal promoter region. At bp -89 is a diverged CArG box, CC(A/T)6AG, which binds the serum response factor (SRF) in myotube nuclear extracts, as does the wild-type sequence, CC(A/T)6GG. Both types of CArG box also bind a novel myotube-enriched complex which has contact points with the AT-rich part of the CArG box and adjacent 3' nucleotides. Mutations within the CArG box distinguish between the binding of this complex and binding of SRF; only SRF binding is directly involved in the specific regulation of the MLC1A gene in skeletal muscle cell lines.

Comparative evaluation of microagglutination test and serum agglutination test as supplementary diagnostic methods for brucellosis

The diagnosis of brucellosis in cattle and small ruminants requires the use of more than one serological test. The complement fixation test (CFT), the rose bengal test (RBT), and the serum agglutination test (SAT) are among the most useful tests for routine diagnosis. The microagglutination test (MAT) was developed as a simpler and more efficient test than the SAT. The relative efficacy of this test compared with that of the SAT was evaluated by using brucella-free sheep and goats prior to and after vaccination treatment. The specificities of the MAT and the SAT were 100%. Of the ewes and goats with a vaccination history, one ewe, expectedly a negative responder, had reactions in the MAT, the complement fixation test, and the rose bengal test but not in the SAT, suggesting a lower sensitivity of the SAT in this case. The calculated sensitivities of the MAT and the SAT were 93.9%. The agreement between MAT and SAT results from nonresponders was examined by using sera from unvaccinated lambs and kids (95.2% agreement), unvaccinated ewes and goats (84.4%), and ewes and goats with a vaccination history (43.9%). For the latter group higher levels of agglutination units were observed by the MAT than by the SAT in 51.5% of the samples. In testing sera from positive reactors after vaccination neither method was superior (MAT values were greater than SAT values for 23.5% of the samples, and MAT values were less than SAT values for 21.9% of the samples). Comparison of the methods on the individual sample level revealed a significant correlation between the MAT and the SAT (r = 0.96 +/- 0.005; P < 0.001). Since the MAT is simpler to perform than the SAT and can potentially be automated, the inclusion of the MAT as a supplementary test in brucellosis control programs is recommended.

Interference with thymocyte differentiation by an inhibitor of S-adenosylhomocysteine hydrolase

Adenosine deaminase (ADA) deficiency causes severe combined immune-deficiency disease in humans. It is believed that the accumulation of the ADA substrate deoxyadenosine affects T cell development through interference with deoxynucleotide metabolism and/or S-adenosylmethionine-mediated methylation processes. In this study, we used a specific inhibitor of methylation, (Z)-5'-fluoro-4',5'-didehydro-5'-deoxyadenosine (FddA), to study the effect of inhibition of methylation on intrathymic T cell development in a murine model for ADA deficiency. FddA causes inhibition of thymocyte differentiation specifically at the CD8low and CD4CD8 double-positive stages. This inhibition is not due to induction of apoptosis, rather it is a result of specific inhibition of regulation of the levels of the mRNAs coding for TCR and CD4 and CD8 co-receptor molecules that normally occurs at these stages of thymocyte differentiation. We hypothesize that the transcription of these T cell-specific molecules is regulated by a common developmental stimulus involving a S-adenosylmethionine-mediated methylation step. Identification of this step will help in understanding the role of methylation in intrathymic differentiation and will also provide a molecular explanation for the tissue and developmental stage specificity observed in severe combined-immune-deficient patients with ADA deficiency.

Interference with thymocyte differentiation by an inhibitor of S-adenosylhomocysteine hydrolase

Adenosine deaminase (ADA) deficiency causes severe combined immune-deficiency disease in humans. It is believed that the accumulation of the ADA substrate deoxyadenosine affects T cell development through interference with deoxynucleotide metabolism and/or S-adenosylmethionine-mediated methylation processes. In this study, we used a specific inhibitor of methylation, (Z)-5'-fluoro-4',5'-didehydro-5'-deoxyadenosine (FddA), to study the effect of inhibition of methylation on intrathymic T cell development in a murine model for ADA deficiency. FddA causes inhibition of thymocyte differentiation specifically at the CD8low and CD4CD8 double-positive stages. This inhibition is not due to induction of apoptosis, rather it is a result of specific inhibition of regulation of the levels of the mRNAs coding for TCR and CD4 and CD8 co-receptor molecules that normally occurs at these stages of thymocyte differentiation. We hypothesize that the transcription of these T cell-specific molecules is regulated by a common developmental stimulus involving a S-adenosylmethionine-mediated methylation step. Identification of this step will help in understanding the role of methylation in intrathymic differentiation and will also provide a molecular explanation for the tissue and developmental stage specificity observed in severe combined-immune-deficient patients with ADA deficiency.

High levels of transforming growth factor beta 1 correlate with disease progression in human colon cancer

Several genes have identified that play a role in colon cancer development. However, less is known about factors that increase the rate of progression of colon cancers to metastasis. One candidate is transforming growth factor beta 1 (TGF beta 1), which can enhance the aggressiveness of human colorectal cell lines in vitro and in vivo. The amount of TGF beta 1, TGF beta 2, and TGF beta 3 protein isoforms expressed in primary site colorectal cancers were measured to determine whether any correlation existed between protein levels and disease recurrence in a series of Memorial Sloan-Kettering Hospital patients who underwent potentially curative resections. Intense staining for TGF beta 1 correlated significantly (P < 0.0013; odds ratio, 18) with disease progression to metastasis and was independent of nodal status and the degree of differentiation of the primary tumor. Therefore, in this study, patients with high TGF beta 1 protein levels in their primary site colorectal cancer were 18 times more likely to experience recurrence of their disease than were patients whose tumors exhibited low levels of TGF beta 1. In this case-control study, patients whose cancer recurred and those remaining cancer free were age and sex matched. The disease recurred at a mean of 26.8 +/- 4.3 (SE) months, whereas the mean follow-up time in patients whose disease did not recur was over twice as long, 57.3 +/- 6.6 months. Ninety-four % of the patients in each group were node positive at the time of resection, with equal mean numbers of positive nodes per patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of interferon alpha IIb on the activity of sialyltransferase in testis homogenates of adult rats

Interferon alpha IIb was injected to adult male rats at doses ranging from 10,000 to 200,000 units. Animals were dissected at intervals of 12 h, 24 h, and 5 days. The activity of the enzyme sialyltransferase in testis homogenates was estimated. In the majority of experiments enzyme activity decreased in comparison to controls.

Constructing a bootstrap confidence interval for the unknown concentration in radioimmunoassay

The statistical problem associated with radioimmunoassay is known as calibration or inverse regression. In the current study, we propose a bootstrap procedure aimed at constructing an inverse confidence interval for the univariate calibration problem. The calibration curve is estimated either parametrically or by non-parametric regression. The methods are illustrated by an example.

B-lineage lymphoid blast crisis in juvenile chronic myelogenous leukemia: II. Interleukin-1-mediated autocrine growth regulation of the lymphoblasts

A pre-B acute lymphoblastic leukemia (ALL) cell line with monosomy 7 was established from a child with juvenile chronic myelogenous leukemia (JCML) in lymphoid blast crisis. Analysis of the growth properties of the cell line, termed 'W1' showed an interleukin-1 (IL-1) mediated autocrine pattern of cell proliferation with the following features: W1 colony growth without added growth factor was density-dependent and colony growth was augmented with serum-free autologous cell culture supernatant; exogenous IL-1 beta had a growth-promoting effect on W1 colony numbers when cells were seeded at low density; W1 cells constitutively expressed mRNA for IL-1 beta, and high levels of IL-1 beta were measured in W1 cell lysates; anti-IL-1 beta antibodies as well as IL-1 receptor antagonist markedly suppressed W1 colony growth when either was added to cultures of cells seeded without growth factors at low density; anti-GM-CSF antibodies and anti-IL-3 antibodies had no inhibitory effect on W1 colony growth. Whereas W1 colony growth was also augmented by adding IL-3, IL-4, IL-6, IL-7, GM-CSF, Steel factor and erythropoietin individually to the cultures, W1 cells did not constitutively express mRNA for any of these cytokines. W1 colony growth was markedly suppressed by exogenous TNF-alpha which contrasts sharply with the autocrine growth promoting effect of TNF-alpha on myelomonocytic elements of JCML in 'chronic' phase. The inhibitory effect of TNF-alpha on W1 cells was not due to downregulation of IL-1 production. The IL-1-dependent growth of W1 cells appeared to be unique because none of five other pre-B lineage ALL cell lines established as controls showed an autocrine growth loop via IL-1. W1 cells provide a valuable opportunity to examine the relationship of monosomy 7, B-lineage acute lymphoblastic leukemia, aberrant genetic expression of cytokines and their receptors, and IL-1 mediated autocrine cell growth in cancer.

Separation of human semen on Percoll gradients: effect on percentage of motile and morphologically normal sperm and proportion of acrosome reacted sperm

OBJECTIVES

To examine whether sperm motility and morphology correlate with ability to undergo the acrosome reaction in vitro.

METHODS

Sixty-one seminal specimens were separated on a discontinuous Percoll gradient (70%, 40%). Percentages of motile and morphologically normal sperm, their motility grade, and percentages of acrosome-reacted sperm before and following acrosome reaction inducing treatment were estimated.

RESULTS

Percentage of motile sperm from normozoospermic specimens increased from whole semen (47.6 +/- 5.6) to sediments (59.6 +/- 13.0). Motility grade exhibited a similar trend (2.1 +/- 0.5 and 3.6 +/- 0.5-scale of 1-4). Percentage of morphologically normal sperm increased from semen (27.3 +/- 10.9) to sediment (53.8 +/- 14.8). All differences were statistically significant, (P < 0.00). In abnormal semen the motility grade and percentage of morphologically normal sperm also increased from semen to sediment (1.9 +/- 0.4 to 3.2 +/- 0.8 and 17.7 +/- 7.8 to 37.1 +/- 15.4 respectively, (P < 0.001). Percentages of motile sperm were similar. In normozoospermic sediments, both non-treated or treated to induce the acrosome reaction, proportions of acrosome-reacted sperm were significantly higher than in semen (18.3 +/- 6.9% and 20.0 +/- 6.5% vs. 6.8 +/- 4.2% respectively, P < 0.001). A similar trend was obtained using abnormal aliquots; however, the acrosome-reacted sperm accounted for only 9.0 +/- 5.1% and 10.8 +/- 4.3% versus 5.4 +/- 2.8% (P < 0.025).

CONCLUSIONS

Morphology and motility of sperm were correlated with the proportion of acrosome-reacted sperm.

Final height of girls with Turner's syndrome: correlation with karyotype and parental height

Final height of 75 adults with Turner's syndrome (45 Israeli, 30 Italian), never treated with GH, was examined to see if a relationship with karyotype patterns and parental height existed. Patients were divided into five groups according to their chromosome pattern, as follows: group A = 45, X karyotype (34 patients); group B = mosaicism (11 with karyotype 45,X/46,XX and 7 with karyotype 45,X/46,XY); group C = deletion of all or part of Xp (19 patients); subgroup C1 = 6 with complete deletion of Xp; subgroup C2 = 9 with mosaicism 45,X/46,X,i(Xq); subgroup C3 = 4 with 45,X/46,X,ring(X); group D = deletion of Xq (4 patients); pure gonadal dysgenesis (PGD) group = 9 patients with pure 46,XX gonadal dysgenesis. No statistical difference was noted between the mean height of the two national populations studied (Italian 142.2 +/- 5.7 and Israeli 143.0 +/- 7.2 cm). The mean heights of group D (148.9 cm; range 147-166.2) and the PGD group (156.0 cm; 141-171.5) were found to be significantly higher than those observed in groups A, B and C (p < 0.03, p < 0.02 and p < 0.02, respectively), even though gonadal distinction existed in all five groups. Subgroup C1, where a deletion of the entire Xp segment [46,X,i(Xq)] was present, was found to be the shortest group (median height 134.5; range 131.9-138 cm).(ABSTRACT TRUNCATED AT 250 WORDS)

[Diabetic cardiomyopathy]

Type I and type II diabetes is associated with increased cardiovascular complications, the most common of which are ischaemic cardiomyopathy and left ventricular dysfunction. The existence of an independent disease, diabetic cardiomyopathy, was suggested by initial anatomic studies, experimental models, and, more recently, by epidemiological studies. The exact cause of this ventricular dysfunction is not known: several mechanisms have been proposed, such as metabolic abnormalities of glucose transport, cellular overload in fatty acid metabolites, alteration of calcium uptake by the sarcoplasmic reticulum leading to cellular calcium overload, coronary microangiopathy, structural collagen abnormalities, interstitial and perivascular fibrosis or the presence of an autonomic neuropathy. The condition is characterised by abnormal left ventricular filling suggesting poor compliance or prolongation of left ventricular relaxation. Left ventricular systolic function is usually normal at rest but abnormally decreased on effort. The value of strict metabolic control and the place of drug therapy, especially calcium antagonists which oppose cellular calcium overload, has yet to be established. The natural history of diabetic cardiomyopathy should be defined by clinical studies taking care to differentiate it from the cardiovascular consequences of hypertension or obesity which aggravate or stimulate this condition.

Tools for working with guidelines

This article reports on a Special Interest Group meeting held at CHI '94, Boston, to discuss the past, present, and future of "Tools for Working with Guidelines". Though working with guidelines has gained today more common practice than in the past, it is still not always obvious which methods can be effectively used for managing guidelines during the whole development life-cycle of an interactive application. Moreover, it is not clear which kind of tools could be made available to designers for helping them in the process.This SIG focused on existing and planned tools for working with guidelines and related computer-aided activities involving guidelines: learning, understanding, teaching, illustration, documentation, standard compliance, usability assessment, guidelines evaluation, computer-aided generation of user interfaces explicitly based on guidelines, advice-giving systems.

Primary products of break-induced recombination by Escherichia coli RecE pathway

Alternative models for break-induced recombination predict different distributions of primary products. The double-stranded break-repair model predicts a noncrossover product and equimolar amounts of two crossover products. The one-end pairing model predicts two crossover products, but not necessarily in equimolar amounts, and the single-stranded annealing model predicts deletion of the fragment between the pairing sequences. Depending on the structure of the recombining substrate(s) and the nature of the resectioning step that precedes strand annealing, the single-stranded annealing mechanism would yield only one or both crossover products. We tested these predictions for the RecE recombination pathway of Escherichia coli. Nonreplicating intramolecular recombination substrates with a double-stranded break (DSB) within one copy of a direct repeat were released from chimera lambda phage by in vivo restriction, and the distribution of primary circular recombination products was determined. Noncrossover products were barely detectable, and the molar ratio of the two crossover products was proportional to the length ratio of the homologous ends flanking the DSB. These results suggest an independent pairing of each end with the intact homolog and argue against the double-stranded break-repair model. However, the results do not distinguish alternative pairing mechanisms (strand invasion and strand annealing). The kinetics of heteroduplex formation and heteroduplex strand polarity were investigated. Immediately following the DSB induction, heteroduplex formation was done by pairing the strands ending 3' at the break. A slow accumulation of the complementary heteroduplex made by the pairing of the strands ending 5' at the break (5' heteroduplexes) was observed at a larger stage. The observed bias in heteroduplex strand polarity depended on DSB induction at a specific site. The 5' heteroduplexes may have been generated by reciprocal strand exchange, pairing that is not strand specific, or strand-specific pairing induced at random breaks.

Cloud-droplet-size distribution from lidar multiple-scattering measurements

A method for calculating droplet-size distribution in atmospheric clouds is presented, based on measurement of laser backscattering and multiple scattering from water clouds. The lidar uses a Nd:YAG laser that emits short pulses at a moderate repetition rate. The backscattering, which is composed mainly of single scattering, is measured with a detector pointing along the laser beam. The multiple scattering, which is mainly double scattering, is measured with a second detector, pointing at a specified angle to the laser beam. The domain of scattering angles that contribute to the doublescattering signal increases monotonically as the pulse penetrates the cloud. The water droplets within the probed volume are assumed to have a constant size distribution. Hence, from the double-scatteringmeasured signal as a function of penetration depth within the cloud, the double-scattering phase function of the scattering volume is derived. Inverting the phase function results in a cloud-droplet-size distribution in the form of a log-normal function.

Growth in patients after allogeneic bone marrow transplant for hematological diseases in childhood

The growth of 66 long-term survivors, transplanted in two centres (Genoa S. Martino and Monza) is reported. Patients were all under age 15 at the time of bone marrow transplantation (mean 9.8 +/- 3.4 years; range 1.07-15 years) with a minimum follow-up of at least 12 months. They were divided into four groups. Group 1: eight patients with severe aplastic anemia (SAA): conditioning included cyclophosphamide (CY) 200 mg/kg only. Group 2: 32 patients with acute lymphoblastic leukemia (ALL), and acute myeloid leukemia (AML): conditioning included CY 120 mg/kg and 10-12 Gy fractionated total body irradiation (fTBI). Group 3: 20 patients with ALL, who had previously received cranial irradiation; conditioning included CY 120 mg/kg and fTBI with an additional testicular irradiation (4 Gy). Group 4: six patients with chronic myeloid leukemia (CML) and AML; conditioning included CY 200 mg/kg and busulfan (BU) 16 mg/kg. Group was impaired in all four groups, including the unirradiated groups (-0.2 +/- 0.7 and -0.5 +/- 0.6 delta-SDS in groups I and 4, respectively). Growth impairment-SDS was statistically significant in the two irradiated groups (-0.7 +/- 1.0 and -0.9 +/- 1.0 delta-SDS in groups 2 and 3, respectively), more marked in patients who had had previous cranial irradiation. Chronic graft-versus-host disease and its treatment were not found to have a major effect on growth.

Chronic obstructive pulmonary disease in patients undergoing coronary artery bypass grafting

The purpose of this study was to evaluate the effect of chronic obstructive pulmonary disease on patients undergoing coronary artery bypass grafting. Between June 1991 and June 1993, 651 patients underwent coronary artery bypass grafting: 37 patients (group I) had significant chronic obstructive pulmonary disease. These patients were compared with 37 matched control subjects (group II). Comparison of the groups was made with regard to postoperative morbidity and mortality. Quality of life of survivors was compared at the last follow-up. More patients in group I had preoperative arrhythmias (8 versus 1, p = 0.014). Group I patients had lower values of forced expiratory volume in 1 second (1.366 +/- 0.032 L versus 2.335 +/- 0.49 L, p < 0.0001), lower oxygen tension (63.5 +/- 8.2 versus 79.1 +/- 13.4 mm Hg, p = 0.001), and higher carbon dioxide tension (44.8 +/- 6.5 mm Hg versus 39.7 +/- 3.6 mm Hg, p = 0.001). After operation patients in group I had a longer hospital stay (8.1 +/- 3.6 days versus 6.6 +/- 1.7 days, p = 0.0236) and longer intensive care unit stay (2.64 +/- 0.9 days versus 1.23 +/- 0.49 days, p = 0.0001). More patients in group I required prolonged intubation (7 versus 1, p = 0.0278) and reintubation (5 versus 1, p = 0.088). More patients in group I had significant arrhythmias (27 versus 9, p < 0.0001). During a 16-month follow-up period, five patients in group I died, whereas none in group II died (p = 0.0271). Four deaths were related to arrhythmias. More group I patients were not functionally improved by the operation (17 versus 3, p = 0.0056). The results of coronary artery bypass grafting in patients with significant chronic obstructive pulmonary disease were not favorable in midterm follow-up. A major cause for morbidity and mortality was postoperative arrhythmias.

[Morphological study by transesophageal echocardiography and clinical aspects of ruptured chordae tendineae in the elderly]

Ruptured mitral chordae tendinae is a classical complication of myxomatous mitral valves or Barlow's syndrome. This complication is controversial in non-myxomatous mitral valve. Of 91 consecutive patients with mitral valve prolapse examined over an 18 months period by transthoracic and transesophageal echocardiography, 42 (18 women and 24 men) with an average age of 76 +/- 8 years (60-93 years) had ruptured mitral chordae tendinae. The thickness of the anterior mitral leaflet measured at the distal third of the valve by transesophageal echocardiography enabled the identification of two groups of patients; group I: > 3 mm (24 patients), average 4.8 +/- 0.8 mm and group II: < or = 3 mm (18 patients), average 2.6 +/- 0.3 mm. The diameter of the mitral ring and left atrium, the length of the anterior mitral leaflet, the left ventricular end diastolic dimensions and fractional shortening, were measured by transthoracic 2D echocardiography (mitral ring) and M mode (other parameters). Ruptured chordae were detected in only 13 cases (31%) by transthoracic echocardiography; 38% were asymptomatic and a chance finding at transesophageal echocardiography. No significant difference was observed between the two groups with respect to age, gender presence of hypertension, dimensions of the cardiac chambers, fractional shortening or localisation of the prolapse related to the ruptured chordae. Fifty-eight per cent of patients in group I were in NYHA functional classes 3-4 as compared to 16% in group II (p < 0.02). The size of the left atrium was significantly greater in group I, 51 +/- 8 mm vs 38 +/- 7 mm (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)