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PubMed1994

Enamel thickness and the helicoidal occlusal plane.

In the present study 38 unworn maxillary molars (M1 = 16, M2 = 12, M3 = 10) of modern humans from a Slavic necropolis were sectioned through the mesial cusps in a plane perpendicular to the cervical margin of the crown. Five slightly worn M1s and one slightly worn M3 were also used thus increasing the total sample to 44, but measurements made on the worn areas were coded as missing values. Seven measurements of enamel thickness as well as the heights of the protocone and the paracone dentine horns were recorded in order to analyze whether changes in these dimensions in anteroposterior direction can be related to the helicoidal occlusal plane. Uni- and multivariate analyses revealed that the distribution of enamel thickness within and between maxillary molars corresponds to a helicoidal occlusal wear pattern. Enamel thickness along the occlusal basin increases from anterior to posterior, which may lead to rapid development of a reverse curve of Monson in first molars when compared to posterior teeth. However, although these overall differences together with the serial, especially delayed eruption pattern of human molars, contribute to the marked expression of the helicoidal occlusal plane in Homo, differences in enamel patterning between molars indicate that a helicoidal plane is a structural feature of the orofacial skeleton. In contrast to first upper molars, second and third molars show absolutely and relatively thicker enamel under the Phase I wear facet of the paracone, i.e., the lingual slope of the paracone, than under the Phase II facet of the protocone, i.e., the buccal slope of that cusp. These proportional differences are most pronounced in M3, as evidenced by uni- and multivariate statistics. It thus appears that the pattern of enamel thickness distribution from M1 to M3 follows a trend towards providing additional tooth material in areas that are under greater functional demands, that is, corresponding to a lingual slope of wear anteriorly and to a flat or even buccal one posteriorly. In addition, the heights of the dentine horns in anteroposterior direction change in a way that lends support to the hypothesis that the axial inclination of teeth could be one of the most important factors for the development of the helicoidal occlusal plane. Finally, the changes in morphology and enamel thickness distribution from first to third upper molars found in this study suggest that molars could be "specialized" in their function, i.e., from performing proportionally more shearing anteriorly to increased crushing and grinding activities posteriorly.

Adaptation, Physiological↗

PubMed1995

Hypoplastic area method for analyzing dental enamel hypoplasia.

Most analyses of dental enamel hypoplasia compare frequencies of disturbed tooth types, which do not account for variability in the area of affected enamel. An alternate methodology, hypoplastic area, is presented here that accounts for this variability by combining acute and continuous enamel hypoplasia into an interval-level variable. The method compares samples based on individuals, by multiple tooth type variables, or by a single value rather than by tooth types. Use of the hypoplastic area method is illustrated by analyzing human skeletal dentitions in three archaeological samples: Meroitic Nubians from Semna South, Sudan; Anasazi from Navajo Reservoir, New Mexico; and Mogollon from Grasshopper Pueblo, Arizona. Both univariate and multivariate statistical tests are employed to assess variation in defects between individuals and samples. By incorporating measurements of continuous defects, the hypoplastic area method provides information beyond that of frequency data in comparing levels of stress. Flexibility of the method is also discussed.

Arizona↗

PubMed2007

Cerebrospinal fluid proteomic biomarkers for Alzheimer's disease.

OBJECTIVE: To find a panel of proteins in antemortem cerebrospinal fluid (CSF) that could be used to differentiate between samples from Alzheimer's disease (AD) patients and samples from healthy and neurological control subjects. METHODS: For a test cohort, antemortem CSF proteins from 34 AD and 34 non-AD patients were separated using two-dimensional gel electrophoresis. The resulting protein patterns were analyzed using the random forest multivariate statistical method. Protein spots of interest were identified using tandem time-of-flight mass spectrometry. A validation cohort consisting of CSF from 18 AD patients and 10 non-AD subjects was analyzed in a similar way. RESULTS: Using the test cohort, a panel of 23 spots was identified that could be used to differentiate AD and non-AD gels with a sensitivity of 94%, a specificity of 94%, and a predicted classification error rate of only 5.9%. These proteins are related to the transport of beta-amyloid, the inflammatory response, proteolytic inhibition, and neuronal membrane proteins. The 23 spots separately classified the validation cohort with 90% sensitivity (probable AD subjects), 83% specificity, and a predicted classification error rate of 14% in a blinded analysis. The total observed sensitivity is 93%, the total observed specificity is 90%, and the predicted classification error rate is 8.3%. INTERPRETATION: A panel of possible CSF biomarkers for AD has been identified using proteomic methods.

Alzheimer Disease↗

PubMedDate not supplied

Patterns of obsessive compulsive symptoms in Tourette subjects are independent of severity.

Studies have examined the expression of obsessive compulsive (OC) symptoms in obsessive compulsive disorder (OCD), OCD with co-occurring Tourette's Syndrome (TS) or chronic motor tic disorder (CMT) and TS alone. In adult samples, there appears to be a relatively consistent OC symptom thematic content that characterizes OCD alone and OCD in conjunction with tics or TS. Previous studies have controlled for the severity of OC symptoms in OCD and TS groups. In the current study, it was our objective to determine whether patterns of OC symptoms in TS are independent of OC symptom severity. The current exploratory study examined OC symptom expression in a nonclinically based TS sample with a broad range of OC symptoms and severity and a selected clinical OCD sample without TS/tics. Univariate and multivariate statistical analysis explored patterns of OC symptom expression between the two groups. Similar to previous reports examining OC symptoms in OCD and OCD with TS/tics, subjects with OCD alone were characterized by contamination obsessions and cleaning compulsions. In contrast, TS subjects had more somatic, sexual and symmetry obsessions and more checking, counting and touching/blinking compulsions, independent of OC symptom and tic severity. A discriminant function using obsessive items alone correctly grouped 91.4% of cases. The current study replicates patterns of OC symptom expression unique to OCD alone. Patterns of OC symptoms, in particular obsessive symptoms, can robustly predict membership in OCD or TS groups, even with a substantial variation in OC symptom severity as measured by the Y-BOCS score.

Adult↗

PubMed2007

Volsurf computational method applied to the prediction of stability of thermostable enzymes.

A computational model for the quantitative prediction of protein thermostability has been developed by means of the Volsurf method. A data set of 22 enzymes of reported thermostability in water systems, for the most part coming from thermophilic and hyperthermophilic organisms, has been built up. Molecular descriptors of the protein surface have been calculated and their role in the stabilization of the macromolecule has been analyzed by a multivariate statistical approach. The resulting regression model has shown a good predictivity and it has been able to quantitatively identify some structural requirements correlated with protein stability. The method can be the basis for a new computational support tool in rational protein design, which is complementary to the existing methods based on the sequence analysis.

Algorithms↗

PubMed2006

Discrimination of normal, benign, and malignant breast tissues by Raman spectroscopy.

Breast cancers are the leading cancers among females. Diagnosis by fine needle aspiration cytology (FNAC) is the gold standard. The widely practiced screening method, mammography, suffers from high false positive results and repeated exposure to harmful ionizing radiation. As with all other cancers survival rates are shown to heavily depend on stage of the cancers (Stage 0, 95%; Stage IV, 75%). Hence development of more reliable screening and diagnosis methodology is of considerable interest in breast cancer management. Raman spectra of normal, benign, and malignant breast tissue show significant differences. Spectral differences between normal and diseased breast tissues are more pronounced than between the two pathological conditions, malignant and benign tissues. Based on spectral profiles, the presence of lipids (1078, 1267, 1301, 1440, 1654, 1746 cm(-1)) is indicated in normal tissue and proteins (stronger amide I, red shifted DeltaCH2, broad and strong amide III, 1002, 1033, 1530, 1556 cm(-1)) are found in benign and malignant tissues. The major differences between benign and malignant tissue spectra are malignant tissues seem to have an excess of lipids (1082, 1301, 1440 cm(-1)) and presence of excess proteins (amide I, amide III, red shifted DeltaCH2, 1033, 1002 cm(-1)) is indicated in benign spectra. The multivariate statistical tool, principal components analysis (PCA) is employed for developing discrimination methods. A score of factor 1 provided a reasonable classification of all three tissue types. The analysis is further fine-tuned by employing Mahalanobis distance and spectral residuals as discriminating parameters. This approach is tested both retrospectively and prospectively. The limit test, which provides the most unambiguous discrimination, is also considered and this approach clearly discriminated all three tissue types. These results further support the efficacy of Raman spectroscopic methods in discriminating normal and diseased breast tissues.

Breast↗

PubMed2000

Prognostic role of plasminogen-activator-inhibitor-1 levels in treatment with streptokinase of patients with acute myocardial infarction.

BACKGROUND: The antifibrinolytic effect of plasminogen-activator-inhibitor type 1 (PAI-1) may be responsible for delays in reperfusion and/or reinfarctions after streptokinase (STK) therapy in patients with acute myocardial infarction (AMI). HYPOTHESIS: This study aimed to demonstrate the prognostic role of pretreatment PAI-1 levels for the outcome of STK therapy in patients with AMI, depending on reperfusion and/ or reinfarction. METHODS: The mean pretreatment PAI-1 level of 104 patients with AMI, treated with STK, determined by chromogenic method, was 5.8 +/- 8.6 U/ml, range 0.3-66.2 U/ml. Streptokinase therapy was successful when reperfusion was achieved, as assessed noninvasively, without subsequent reinfarction; it failed when reperfusion was delayed and/or reinfarction developed. RESULTS: Fibrinolysis with STK failed significantly in patients with elevated pretreatment PAI-1 levels (p < 0.05), especially with levels >4.0 U/ml (p< 0.01). The mean pretreatment PAI-1 level was significantly higher in unsuccessfully treated patients. Multivariate statistical testing demonstrated that among pretreatment variables, elevated PAI-1 activity was the most significant independent risk factor of failed fibrinolysis with STK. CONCLUSIONS: Among pretreatment variables, elevated pretreatment PAI-1 activity in patients with AMI was the most significant independent risk factor of failed fibrinolysis with STK, especially at levels > 4.0 U/ml.

Adult↗

PubMed2002

Adult rhabdomyosarcoma: outcome following multimodality treatment.

BACKGROUND: Childhood rhabdomyosarcoma (RMS) has a relatively good prognosis. Outcome for adults with this disease is poorly documented due to its rarity. METHODS: The clinicopathologic features, treatment methods, and disease outcome were reviewed retrospectively for 82 adults with locoregional RMS treated between 1960 and 1998. Patients with distant metastasis at diagnosis were excluded. Actuarial univariate and multivariate statistical methods were used to evaluate outcome. RESULTS: Patient ages ranged from 17 to 84 years (median, 27 years). Histologic subtypes were embryonal (34%), pleomorphic (43%), and alveolar (23%). Anatomic sites of origin were head and neck (52%), trunk (26%), and extremity (7%). Tumor size was 5 cm or smaller in 51% of patients. Regional lymph node metastasis was present in 33% of patients at presentation. Treatment consisted of radiation alone in 11%, radiation and surgery in 18%, radiation and chemotherapy in 34%, and all three modalities in 37%. With a median follow-up of 10.5 years, the 10-year actuarial disease-free and overall survival rates were 41% and 40%, respectively. The 10-year actuarial local, lymph node, and metastatic control rates were 75%, 82%, and 53%, respectively. The major determinant of metastatic control and survival was primary tumor size (< or = 5 vs. > 5 cm). Local control was satisfactory (10-year rate of 87%) for sites other than parameningeal (50% at 10 years). Patients whose disease responded to chemotherapy had a significantly better metastasis free period (72% at 10 years) than those whose disease failed to respond (19% at 10 years). CONCLUSIONS: Adult RMS is a highly malignant tumor with a significant incidence of metastatic recurrence. Continuing investigation of new and potentially more effective chemotherapy is crucial. Local control is satisfactory for sites other than parameningeal where new radiation technologies such as intensity-modulated therapy may be necessary to safely deliver adequate doses.

Adolescent↗

PubMed2003

Prognostic factors for patients with localized soft-tissue sarcoma treated with conservation surgery and radiation therapy: an analysis of 1225 patients.

BACKGROUND: Prognostic factors for patients with soft-tissue sarcoma who are treated with conservative surgery and radiation are documented poorly. METHODS: The clinicopathologic features and disease outcome for 1225 patients with localized sarcoma who were treated with conservative surgery and radiation were reviewed retrospectively. Actuarial univariate and multivariate statistical methods were used to determine significant prognostic factors for local control, metastatic recurrence, and disease specific survival. RESULTS: The median follow-up of surviving patients was 9.5 years. The respective local control rates at 5 years, 10 years, and 15 years were 83%, 80%, and 79%. Factors predictive of local recurrence were positive or uncertain resection margins; tumors located in the head and neck and the deep trunk; presentation with local recurrence; patient age > 64 years; malignant fibrous histiocytoma, neurogenic sarcoma. or epithelioid sarcoma histopathology; tumor measuring > 10 cm in greatest dimension; and high pathologic grade. Freedom from metastasis at 5 years, 10 years, and 15 years was 71%, 68%, and 66%, respectively. Factors that were predictive of metastatic recurrence were high tumor grade; large tumor size (> 5 cm); and leiomyosarcoma, rhabdomyosarcoma, synovial sarcoma, or epithelioid sarcoma. The respective disease specific survival rates at 5 years, 10 years, and 15 years were 73%, 68%, and 65%. Adverse factors for disease specific survival were high tumor grade; large tumor size (> 5 cm); tumors located in the head and neck and deep trunk; rhabdomyosarcoma, epithelioid sarcoma, or clear cell sarcoma; patient age > 64 years; and positive or uncertain resection margins. CONCLUSIONS: Soft-tissue sarcoma comprises a heterogeneous group of diseases. Prognostic factors for local recurrence, metastatic recurrence, lymph node recurrence, disease free survival, and disease specific survival are different, and optimal treatment strategies need to take this complexity into account.

Adolescent↗

PubMed2003

Childbearing and survival after breast carcinoma in young women.

BACKGROUND: Many young patients with breast carcinoma have not started, or completed, their desired families. How childbearing after a diagnosis of breast carcinoma affects survival is of importance to these women and their families. The authors measured relative mortality among young patients with breast carcinoma with and without births occurring after diagnosis. METHODS: The authors conducted a cohort study using data from three population-based cancer registries in the U.S. (Seattle, Detroit, and Los Angeles), linked to birth certificate data in each state. Four hundred thirty-eight women younger than 45 years of age with primary invasive breast carcinoma were identified as having births after diagnosis. In addition, 2775 comparison women, matched on the basis of age at the time of diagnosis, race/ethnicity, diagnosis year, disease stage, and presence of previous nonbreast primary tumors, were identified among those with breast carcinoma without births after diagnosis. Relative mortality was assessed using multivariable statistical methods. RESULTS: After adjustment for stage of disease, age at diagnosis, study region, diagnosis year, and race/ethnicity, women with births occurring 10 months or more after diagnosis had a significantly decreased risk of dying (relative Risk [RR] = 0.54, 95% confidence interval [CI], 0.41-0.71) compared to women without subsequent births. Women pregnant at the time of diagnosis had a mortality rate similar to those who did not give birth (RR = 1.10, 95% CI, 0.80-1.60). CONCLUSIONS: The results of the current study, in light of growing evidence from other studies using various methods, may provide some reassurance to young women with breast carcinoma that subsequent childbearing is unlikely to increase their risk of mortality.

Adult↗

PubMed2004

The superior prognostic value of humoral factors compared with molecular proliferation markers in renal cell carcinoma.

BACKGROUND: The American Joint Committee on Cancer and the Union Internationale Contre le Cancer have acknowledged routine laboratory parameters, such as serum calcium, alkaline phosphatase, hemoglobin, and the erythrocyte sedimentation rate (ESR), as predictors of survival in patients with renal cell carcinoma. The predictive value of these parameters compared with proliferation markers, such as Ki-67, proliferating cell nuclear antigen (PCNA), topoisomerase II-alpha, and p100, has not been determined. METHODS: Forty-eight consecutive patients who underwent nephrectomy for nonmetastatic renal cell carcinoma between 1990 and 1994 were observed up to 120 months postoperatively. Ten of 48 patients developed tumor progression 6-69 months after surgery. Routine preoperative laboratory parameters as well as tumor-specific data were assessed. Findings were compared with tumor proliferation indices, which were obtained by immunohistochemical staining for nuclear antigens Ki-67, PCNA, topoisomerase II-alpha, and p100 in paraffin embedded tumor tissue. RESULTS: Univariate and multivariate statistical analyses demonstrated superiority of routine laboratory values compared with tumor proliferation indices in predicting progression-free survival and disease-specific death. The best predictor after tumor size and symptomatic presentation was ESR (P < 0.0001), with ESR values > 70 mm at 2 hours indicating a significantly poorer prognosis. Only the proliferation marker Ki-67 reached univariate significance at a threshold of 7%. CONCLUSIONS: Routine laboratory parameters, such as alkaline phosphatase, lactate dehydrogenase, thrombocyte count, and especially ESR, provided superior long-term prognostic information for patients with nonmetastatic renal cell carcinoma compared with the molecular tumor proliferation markers Ki-67, PCNA, topoisomerase II-alpha, and p100.

Adult↗

PubMed1989

Quantitative Golgi study of anatomically identified subdivisions of motor thalamus in the rat.

A Golgi study of neurons in the ventroanterior-ventrolateral complex (VAL) and ventromedial (VM) nucleus in the dorsal thalamus of rats was performed. To facilitate the delineation of subdivisions of these nuclei, some animals received injections of horseradish peroxidase (HRP) into the afferent and efferent fields of VAL and VM, and alternate sections were processed for the histochemical detection of HRP. As an adjunct to subjective observations, a multivariate statistical analysis of morphometric variables was performed to provide an objective assessment of neuronal morphology. All Golgi-stained neurons in VAL and VM were tentatively identified as projection neurons; no cells with morphological features commonly ascribed to thalamic interneurons were impregnated. Four classes of morphologically distinct neurons were identified in VAL. Type 1 neurons, the most commonly impregnated cell, were found throughout the extent of VAL and resembled "tufted" or "multipolar bush" neurons described previously in many thalamic nuclei. The remaining three neuronal types differed in a number of morphometric parameters and were differentially distributed throughout VAL. Type 2 neurons, distinguished in part by dendritic spine morphology and elongated bipolar dendritic fields, were found only in the rostral sector of the dorsal division of VAL (VALD). Type 3 neurons, characterized by a large and evenly distributed dendritic field, were situated in rostral VAL (all subdivisions). Type 4 neurons had small soma and dendritic dimensions and were located in the ventromedial aspect of the ventral division of VAL (VALV) adjacent to VM. In contrast, the vast majority of neurons in VM were considered to be a single morphological class (similar in form to type 4 neurons in VAL), although a rarely impregnated second type of neuron was also observed. The apparent scarcity of interneurons in VAL and VM is consistent with previous evidence that the synaptic organization of motor thalamus in the rat is markedly different from that of higher-order mammals. Speculation about the functional attributes of the neuronal types in VAL and VM is necessarily restricted to considerations of afferent and efferent relations, since "motor modality" functions of neurons in these nuclei have yet to be elucidated.

Animals↗

PubMed1987

On multiparameter data analysis in flow cytometry.

Increasing numbers of parameters that are accessible to simultaneous measurement in flow cytometric instruments, combined with the extremely large sample sizes common in flow cytometry, make it necessary to examine methods of multivariate statistics for their applicability to problems of visualization and quantitative analysis of flow cytometric data. This article describes some approaches to dimensionality reduction that appear well suited for data sets obtained by flow cytometry.

Flow Cytometry↗

PubMed2006

Branch to colony trajectory in a modular organism: pattern formation in the Indo-Pacific coral Stylophora pistillata.

The architecture of the colony in a branching coral is an iterative process in which new layers of calcium carbonate compile atop existing structures that remain unchanged. Colony growth and development, known as astogeny, is believed to be a continuous process, characterized by replication of lower rank unites, polyps, and branches. This study seeks to explore the genetic blueprint of branch-to-colony developmental trajectory in the branching coral Stylophora pistillata, within an astogeny period of 1 year. One hundred small branches (initially 2-4 cm long) were sampled from 10 colonies. A year later, 63 remaining colonies were analyzed for their architectural rules by using 15 morphometric parameters. Multivariate statistical tests were preformed. Cluster and two-dimensional nonmetric Multi-Dimensional Scaling analyses revealed that the 10 genotypes could be divided into two major morphometric groups and two intermediate groups, whereas SIMPER analyses (a similarity percentage test) on within-genet similarities showed high similarity between the ramets developed from each of the 10 genotypes. Although, at first, it seemed that different colonies exhibited variable and different architectural designs (each characterized by specific morphometric parameters), a comprehensive analysis revealed that all 10 coral genotypes exhibited a single common developmental plan that was characterized by a continuum of architectural design with several distinct stages. Each stage is marked by its own characteristic morphometric parameters. Changing of developmental rules during the trajectory from branch to coral colony may help the colony to cope better with environmental constraints.

Animals↗

PubMed2005

A case-control study of family composition in anorexia nervosa.

OBJECTIVES: The family compositions of patients with anorexia nervosa may inform consideration of the etiology of the disorder, and previous studies in this area have had methodologic weaknesses which we sought to address in a case-control design. METHODS: The family composition of 259 females with anorexia nervosa was compared with that of 200 control subjects. Birth order and numbers of brothers and sisters were compared in unmatched and matched analyses using both univariate and multivariate statistical techniques. RESULTS: In both the unpaired univariate and the matched conditional logistic regression analyses, the anorexic females were both significantly later in the birth order and had significantly fewer brothers than control subjects. DISCUSSION: Although it is possible that these findings were affected by response bias among control subjects, it is more likely that they are informative with regard to the etiology of anorexia nervosa. Possible etiologic links are discussed in relation to biologic, family, and sociocultural factors.

Adult↗

PubMed1993

Global analysis of antibody repertoires. II. Evidence for specificity, self-selection and the immunological "homunculus" of antibodies in normal serum.

The serum IgM repertoires of C57BL/6, DBA/2 and BALB/c mouse strains were analyzed using a recently developed global and quantitative assay that measures antibody reactivities to a very large number of antigens. A characteristic repertoire could be assigned to each strain. The different repertoires could be successfully classified with multivariate statistics. Many common reactivities were also observed among the different strains, which allows the definition of a mouse-specific repertoire. Analysis of human sera support this notion. To investigate the impact of minor genetic differences on the serum IgM repertoire, the congenic strains B10.D2/oSn and B10.D2/nSn, which differ in the expression of the C5 component of complement, were analyzed. The two strains could be separated based on the reactivity profiles obtained. The analysis of the results reveals that many antigenic proteins are not recognized at all by natural antibodies, while others are disproportionately reactive, the resulting patterns giving rise to what could be the definition of an "immunological homunculus". The relevance of this type of analysis for clinical applications is discussed.

Adult↗

PubMed1998

Effects of renovascular hypertension on myocardial protein patterns: analysis by computer-assisted two-dimensional gel electrophoresis.

Hypertensive heart disease caused by renovascular hypertension reflects the response of the heart to an increased afterload and neurohormonal stimulation. We hypothesized that in this condition the composition of the myocardial proteins of rats was altered. To identify yet unknown quantitative and qualitative differences in myocardial proteins in renovascular hypertensive heart disease, we analyzed protein patterns by computer-assisted two-dimensional polyacrylamide large gel electrophoresis. Renovascular hypertension was induced by placing a silver clip on the left renal artery in 9-week-old rat siblings. Sham-operated animals served as controls. Systolic blood pressure (197 +/- 19 mm Hg) and heart/body weight ratios (0.36 +/- 0.04%) were significantly increased in the hypertensive animals. Twenty protein patterns from the left ventricle of five hypertensive and five control rats were compared. The molecular mass and isoelectric point (pI) of proteins spots ranging from 13 to 100 kDa and from 4.5 to 8.5, respectively, were determined using marker proteins. In total, 761 +/- 88 protein spots were resolved in all twenty gels. For the quantitative data analysis a univariate (Mann-Whitney test) as well as a multivariate statistical approach (correspondence analysis) were applied. Only one myocardial protein spot (molecular mass = 41.3 kDa; pI = 6.3) was decreased by more than twofold (p < 0.05) in renovascular hypertension. The vast majority of spots did not indicate a significant alteration of intensity. Left ventricular hypertrophy in early renovascular hypertension induces a form of myocardial hypertrophy that conserves the naturally occurring protein expression pattern.

Animals↗

PubMed1992

Rational approach to the quantification of genotoxicity.

The question of how many and which short-term tests (STT) are necessary for a satisfactory characterization of the genotoxic properties of chemicals is still open. The answer is important for both basic mutagenicity research and risk assessment. This paper, aimed at giving a rational answer to the problem, analyzes with multivariate statistical methods the data generated by the International Program for the Evaluation of Short-Term Tests for Carcinogens (IPESTTC). Although it has been found that this data base has a limited reliability for assessing the ability of STTs to predict carcinogenicity, the IPESTTC results are an important source of information on the relationships among different assays, and their ability to identify genotoxic chemicals. A scale of genotoxicity of the chemicals was established by studying with factor analysis their results in 20 IPESTTC tests. The next step of the analysis consisted in the identification of the STT batteries which are the most able to reproduce the genotoxicity scale based on the entire set of STTs. Different batteries were ranked according to their ability to quantify genotoxicity. As a general conclusion, this study indicated that an articulated range of STTs is necessary, and it is not possible to use only one assay (e.g., Salmonella) as an exhaustive indicator of genotoxicity.

Carcinogenicity Tests↗