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PubMed2006

Multivariate analysis of microarray data by principal component discriminant analysis: prioritizing relevant transcripts linked to the degradation of different carbohydrates in Pseudomonas putida S12.

The value of the multivariate data analysis tools principal component analysis (PCA) and principal component discriminant analysis (PCDA) for prioritizing leads generated by microarrays was evaluated. To this end, Pseudomonas putida S12 was grown in independent triplicate fermentations on four different carbon sources, i.e. fructose, glucose, gluconate and succinate. RNA isolated from these samples was analysed in duplicate on an anonymous clone-based array to avoid bias during data analysis. The relevant transcripts were identified by analysing the loadings of the principal components (PC) and discriminants (D) in PCA and PCDA, respectively. Even more specifically, the relevant transcripts for a specific phenotype could also be ranked from the loadings under an angle (biplot) obtained after PCDA analysis. The leads identified in this way were compared with those identified using the commonly applied fold-difference and hierarchical clustering approaches. The different data analysis methods gave different results. The methods used were complementary and together resulted in a comprehensive picture of the processes important for the different carbon sources studied. For the more subtle, regulatory processes in a cell, the PCDA approach seemed to be the most effective. Except for glucose and gluconate dehydrogenase, all genes involved in the degradation of glucose, gluconate and fructose were identified. Moreover, the transcriptomics approach resulted in potential new insights into the physiology of the degradation of these carbon sources. Indications of iron limitation were observed with cells grown on glucose, gluconate or succinate but not with fructose-grown cells. Moreover, several cytochrome- or quinone-associated genes seemed to be specifically up- or downregulated, indicating that the composition of the electron-transport chain in P. putida S12 might change significantly in fructose-grown cells compared to glucose-, gluconate- or succinate-grown cells.

Carbohydrate Metabolism↗

PubMed1993

Gamma knife radiosurgery for acoustic tumors: multivariate analysis of four year results.

In order to evaluate the results of radiosurgery for acoustic tumors and to identify optimum treatment parameters, an analysis of tumor control, as well as incidences of hearing loss, facial and trigeminal neuropathies was undertaken. Between August 1987 and August 1991, 134 patients with 136 acoustic tumors received stereotactic gamma knife radiosurgery at the University of Pittsburgh. Median follow-up was 24 months (range: 6-56 months). Tumor volumes ranged from 0.10 to 17.00 cm3 (median = 2.75 cm3). From one to ten isocenters were utilized per tumor treated (median = 3). Minimum tumor doses varied from 12 to 20 Gy (median = 17 Gy). The 4-year actuarial tumor control rate was 89.2 +/- 6.0%. Some degree of hearing (by pure tone audiometry) was preserved in 71.0 +/- 4.4% of patients. The actuarial rates for preservation of either pretreatment hearing level or useful hearing were 34.4 +/- 6.6% and 35.1 +/- 97% respectively. Respectively, the actuarial incidences of postradiosurgery facial and trigeminal neuropathies were 29.0 +/- 4.4% and 32.9 +/- 4.5%, respectively. No significant factors affecting tumor control were identified. Multivariate analysis identified a significantly increased risk of hearing loss in patients with neurofibromatosis (p = 0.0003) as well as decreased risks of facial and trigeminal neuropathies with both decreasing tumor diameter (p = 0.001) and increasing number of isocenters treated (p = 0.003). Radiosurgery is a safe and effective treatment for acoustic neuromas with acceptable morbidity that may be lowered by the use of multiple isocenter treatment techniques and by earlier treatment of small tumors.

Adolescent↗

PubMed2001

Improved survival and local control after intraoperative radiation therapy and postoperative radiotherapy: a multivariate analysis of 46 patients undergoing surgery for pancreatic head cancer.

HYPOTHESIS: Despite aggressive approaches, locoregional tumor control and survival rates for patients with cancer of the pancreatic head remain disappointing. In the present study, we address whether intraoperative and adjuvant radiotherapy may improve the prognosis for these patients. DESIGN: A retrospective study. SETTING: University hospital. PATIENTS: From February 1985 to December 1995, 46 patients with an adenocarcinoma of the pancreatic head underwent pancreatic resection. The last 26 patients also received intraoperative radiotherapy (except 5 patients) and adjuvant external beam radiation therapy. MAIN OUTCOME MEASURES: Demographic data, tumor characteristics, surgical procedures, 5-year survival, and local control of disease were analyzed retrospectively. RESULTS: The morbidity rate was not increased by adjuvant radiation therapy; it was 43% in patients treated with surgery alone and 57% in patients treated with surgery and radiotherapy (P =.1); operative mortality was 8% (n = 2) and 9% (n = 2), respectively (P =.8). Overall 5-year survival and local control were 13% and 48.6%, respectively. The mean +/- SD 5-year survival was 5.5% +/- 5.3% (median, 10.8 months) in the surgery-alone group and 15.7% +/- 8.6% (median, 14.3 months) in the surgery plus radiotherapy group (P =.06); local control at 5 years was 29.8% +/- 16.9% and 58.4% +/- 19.9%, respectively (P<.01). Median metastasis-free survival was 8 and 9 months, respectively (P =.52). Multivariate analysis showed that adjuvant radiotherapy was an independent prognostic factor for survival (P<.01) and local control of the disease (P =.03). CONCLUSION: The present study supports the role of radiotherapy combined with pancreatoduodenectomy for treatment of cancer of the pancreatic head because even if the improvement in overall survival is moderate, it is effective in improving the local control of the tumor.

Adenocarcinoma↗

PubMedDate not supplied

Performance status and age as independent predictors of survival among AIDS patients with primary CNS lymphoma: a multivariate analysis of a multi-institutional experience.

PURPOSE: There is limited information about the outcome of AIDS patients with primary central nervous system lymphoma treated with definitive irradiation. The purpose of this study was to determine factors associated with increased survival in such patients. METHODS: An analysis was performed of 163 patients with AIDS who were evaluated at nine urban hospitals. These patients were treated for primary central nervous system lymphoma after the establishment of a tissue diagnosis or on a presumptive basis after failing empiric treatment for toxoplasmosis. All patients were treated between 1983 and 1995 with radiotherapy (median dose-fractionation scheme = 3 Gy x 10) and steroids (> 90% dexamethasone). Because multiple fractionation schemes were used, prescriptions were converted to biologically effective dose according to the formula Gy10 = Total Dose x (1 + fractional dose/alpha-beta), using an alpha-beta of 10. RESULTS: Longer median survival times were associated with high Karnofsky performance status (KPS > or = 70 vs < or = 60: 181 vs 77 days), young age (< 35 vs > 35: 162 vs 61 days), and high total definitive irradiation doses (> 39 Gy10 vs < 39 Gy10: 162 vs 40 days). Tissue diagnosis, gender, race, number of lesions (solitary vs multiple), and the presence of other cancers did not influence outcome. In multivariate analysis, young age, high Karnofsky performance status, and the delivery of higher biologically effective doses of irradiation retained independent significance relative to the endpoint of survival. CONCLUSIONS: Even at urban tertiary medical centers, few AIDS patients with intracranial lesions undergo biopsies to establish a precise tissue diagnosis. Survival following definitive irradiation is strongly related to two pretreatment factors (young age, high performance status) and one treatment factor (total biologically effective dose of cranial radiotherapy). These variables should be considered in selecting patients for definitive irradiation and in designing future studies.

Acquired Immunodeficiency Syndrome↗

PubMed2001

Colonization and infection of pulmonary artery catheter in cardiac surgery patients: epidemiology and multivariate analysis of risk factors.

OBJECTIVE: To assess the incidence and etiology of colonization and infection of pulmonary artery catheters inserted in cardiac surgery patients. To determine the influence of some variables on the risk of developing pulmonary artery catheter colonization and infection. DESIGN: Prospective observational study of pulmonary artery catheters inserted into the internal jugular vein that were in place for >48 hrs over a 13-month period. Data collected included age, gender, nature of the cardiac surgery intervention, duration of extracorporeal circulation, date of insertion and removal, subsequent infection, and curative antimicrobial therapy. End points were pulmonary artery catheter colonization with >or=10(3) colonies on quantitative cultures and pulmonary artery catheter-related bacteremia. Risk factors for colonization were determined by multiple logistic regression. SETTING: A 17-bed cardiac surgery intensive care unit in a 480-bed teaching hospital in Paris. PATIENTS: Patients undergoing cardiac surgery procedures between May 1, 1997, and May 31, 1998. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 164 pulmonary artery catheters inserted in 157 patients, 19 (11.6%) and 1 (0.6%) were associated with colonization (mean duration of catheterization, 7.5 +/- 2.8 days) and bacteremia, respectively. These data represent an incidence of 17.7 and 0.93 episodes per 1000 catheterization-days, respectively. Pulmonary artery catheter colonization was caused by Gram-positive cocci in 48% (67% were coagulase-negative staphylococci), Gram-negative rods in 48%, and Candida albicans in 4%. From multivariate analysis, >4 days of catheterization was the single variable associated with a significantly increased risk of pulmonary artery catheter colonization (odds ratio, 9.81; 95% confidence interval, 1.24-77.5, p = .03). CONCLUSIONS: Our data show that the risk of pulmonary artery catheter-related colonization and bacteremia is quite low despite the use of a high-risk insertion site. In cardiac surgery patient populations, a trial evaluating the impact of a systematic pulmonary artery catheter removal after 4 days is warranted.

Bacteremia↗

PubMed1996

Multivariate analysis of risk factors for hepatocellular carcinoma in patients with hepatitis C virus-related liver cirrhosis.

To elucidate the risk factors for hepatocellular carcinoma (HCC) in hepatitis C virus (HCV)-related liver cirrhosis (LC), we examined 204 cirrhotic patients negative for hepatitis B surface antigen and positive for HCV antibodies. The independent influence of various clinical characteristics in these patients was analyzed by multiple logistic regression, and the risk factors for HCC were identified. Multiple logistic regression analysis identified and ranked the following four risk factors: male sex (P < 0.001), habitual heavy drinking (P < 0.005), hepatitis B virus antibody positivity (anti-HBs and/or anti-HBc, P < 0.05), and age greater than 60 years (P < 0.05). The odds ratio of HCC was 4.20 (95% confidence interval; CI, 1.80-9.78) in male patients, 3.27 (95% CI, 1.46-7.30) in habitual heavy drinkers, 2.01 (95% CI, 1.01-3.99) in patients positive for hepatitis B virus antibodies, and 2.06 (95% CI, 1.00-4.23) in patients older than 60 years. The cumulative occurrence rates of HCC after blood transfusion were significantly higher in habitual heavy drinkers (4.8%, 49.4%, and 74.7% at 10, 20, and 30 years, respectively) than in non-drinkers (0%, 21.0%, and 23.3% at 10, 20, and 30 years, respectively, P < 0.0003). The mean interval for progression to LC after blood transfusion was significantly shorter in the habitual heavy drinkers than in the non-drinkers (22.4 +/- 4.4 years vs 28.4 +/- 3.9 years; P < 0.0003). This multivariate analysis revealed that habitual heavy drinking and hepatitis B virus antibody positivity are significant risk factors for HCC in HCV-related liver cirrhosis.

Age Factors↗

PubMed2003

Raltitrexed-induced hepatotoxicity: multivariate analysis of predictive factors.

Raltitrexed (Tomudex; TOM) hepatotoxicity is usually characterized by a transient and self-limiting increase in transaminase levels. How this may condition daily clinical practice is still unclear. The aim of this study was to investigate predictive factors of TOM hepatotoxicity. In total, 130 patients were treated at two medical oncology institutions with TOM (3 mg/m2) (52 patients) or TOM plus oxaliplatin (TOMOX) (100 mg/m2 day 1 or 70 mg/m2 day 1, 8) (78 patients). A multinomial logistic regression (adjusted for multilevel data) was performed (on all administered chemotherapy courses) to assess the dependence of hepatic toxicity on a set of clinical factors correlated with patient, disease and treatment characteristics. Creatinine clearance was calculated by the Cockcroft formula before each chemotherapy course. Most of the patients presented colorectal cancer (95%) and metastatic disease (93%). Out of the 130 patients, 41 were aged 70 or more, while 119 (91.5%) had a good performance status (PS) (ECOG 0 or 1). Before chemotherapy, liver metastases were present in 78 (60%) patients and elevated transaminase in 25 (19%). A total of 584 courses were administered (252 TOM and 332 TOMOX). National Cancer Institute Common Toxicity Criteria grade 1/2 and 3/4 transaminase toxicity was observed in 62 and 20% of patients, respectively. To control transaminase increase, glutathione (GSH) or ademethionine (SAMe) was administered in 96 and 129 cycles, respectively. Hepatotoxicity conditioned delays (a week or more) in 60 (10%) chemotherapy cycles and was the reason for the discontinuation of chemotherapy in eight (6%) patients. Among the factors evaluated with multivariate analysis, sex, age, PS, creatinine clearance, previous chemotherapy treatment, presence of liver metastases and oncology centre were not significantly associated with TOM hepatotoxicity. Elevated baseline transaminase levels (p=0.001), number of chemotherapy cycles (p<0.001), TOM cumulative dose (p=0.018), unprolonged intervals between courses (p<0.001) and TOMOX regimen (p<0.001) emerged as factors predictive of hepatotoxicity. In the same analysis, GSH (p<0.001) and SAMe (p<0.001) were hepatoprotective agents. This study confirmed TOM-based hepatotoxicity as a clinical relevant side-effect and a major factor for treatment delays or discontinuation. Predictive and protective factors listed above could assist the management of this toxicity that has probably been underestimated until now.

Adult↗

PubMed1984

Multivariate analysis of prognostic factors in penetrating ocular injuries.

We used a multivariate statistical analysis to identify factors predicting visual outcome in 281 eyes that underwent primary repair of a penetrating ocular injury. Visual acuity of 20/800 or better on initial examination was the most important factor, with these eyes 28 times more likely to have a final visual acuity of 20/800 or better than eyes with initial visual acuities worse than 20/800. The effect of other factors differed depending on the initial visual acuity. In patients with initial visual acuities of 20/800 or better, youth (less than or equal to 18 years) was a significant predictor of final visual acuities of 20/50 or better. In patients with initial visual acuities worse than 20/800, a laceration limited to the cornea was the best predictor of good visual outcome. Absence of an expelled or subluxed lens and lacerations limited to a location anterior to the rectus muscle insertions were also important predictors of good visual outcome. When an intraocular foreign body was present these factors were no longer significant and older age (greater than 18 years) was the most important predictor of good visual outcome.

Adolescent↗

PubMed2004

A multivariate analysis of the outcome of endodontic treatment.

In the present study, multivariate analyses were performed on clinical and treatment variables that may influence the outcome of endodontic treatment. Data collected in a previous clinical-radiographic follow-up study were used. Of 810 treated, 675 roots in 498 teeth were followed for 6 months to 4 yr. Of these, 192 (the CAP group) had pre-existing, chronic apical periodontitis and 483 (the NAP group) had not. Root canal treatment followed a standard procedure with one of three sealers chosen at random. Demographic, clinical and radiographic variables were recorded at the start of, and during treatment. The periapical index (PAI) score was used to record the outcome of treatment, and applied in two different endpoint modes (END1 and END2) as the dependent variable for multivariate statistical analyses using logistic regression and the general model. The modes reflected increasing PAI scores (END1) and conventional success/failure assessment (END2). Dropouts were largely similar to the cases followed up. A total of 10 preoperative and peroperative variables were found to be significantly associated with treatment outcome by the multivariate analyses of either the total material or the NAP or CAP subgroups. Several of these were not significant in univariate analyses (e.g. the effect of sealer). Conventional success/failure analyses (END2) identified fewer of the influential variables and had low explanatory power, whereas PAI scores on an ordinal scale (END1) were most sensitive in identifying variables of influence on the treatment outcome.

Adolescent↗

PubMed1993

Multivariate analysis for predicting the presence of bacteria in bile in patients with acute cholecystitis.

OBJECTIVE: to find out whether the presence of bacteria in bile could be predicted accurately from preoperative data in patients with acute cholecystitis. DESIGN: Prospective open study. SETTING: University hospital. SUBJECTS: 42 patients undergoing cholecystectomy for acute gallstone cholecystitis. MAIN OUTCOME MEASURES: Correlations between 24 preoperative clinical and laboratory variables, and the incidence of pathogenic organism in bile. RESULTS: 4 of the 24 variables tested were of predictive significance. These were external body temperature on admission, percentage of neutrophils, preoperative white blood cell count, and total serum concentration of bilirubin. When these predictive variables were evaluated in the discriminant analysis equation they had a sensitivity of 92% and a specificity of 100% in predicting positive bile culture. CONCLUSION: Multivariate discriminant analysis permits accurate preoperative prediction of bile cultures growing pathogens in patient undergoing cholecystectomy for acute cholecystitis.

Acute Disease↗

PubMed2006

Rectal cancer surgery in the elderly: a multivariate analysis of outcome risk factors.

BACKGROUND AND OBJECTIVES: Geriatric population life expectancy is rapidly increasing and the impact of major surgical procedures is not well defined. The purpose of this study was to compare short term surgical results assessing mortality and morbidity and long-term survival and disease-free interval in elective rectal surgery patients older than 65 years of age. The main independent risk factors of mortality, morbidity, and overall and disease-free survival were also identified. METHODS: Out of 177 rectal cancer accepted consecutively from 1991 to 2002, we studied the main clinical and pathological parameters comparing patients older and younger than 65 years. Data have been collected in a database and variables considered were studied by univariate analysis; independent predictive factors of 30-day mortality and morbidity were identified by multiple logistic regression analysis. Overall, cancer specific and disease-free survival curves were obtained with the Kaplan-Meier method and results compared with the log-rank test. Independent risk factors of overall and disease-free survival have been identified by multivariate logistic regression analysis. RESULTS: In patients younger and older than 65 years postoperative mortality (3.2% vs. 9.6%) and morbidity (30% vs. 29%) were not significantly different. Variables independently associated with 30-day mortality were the duration of surgical procedures and postoperative complications. The Kaplan-Meier survival curves showed a significantly worst overall survival (P = 0.003), cancer specific survival (P = 0.02), and disease-free survival (P = 0.03) in patients aged 65 years or more. Multivariate analysis showed that pT, grading, preoperative CEA level, gender, and site of the tumor along the rectum, the number of blood transfusion and the age group of more than 65 years are independent risk factors for both overall survival and disease-free interval. The presence of residual disease was an adjunctive factor of overall survival, whereas the Astler and Coller staging was a risk factor for the disease-free survival. CONCLUSION: The short-term prognosis for elective rectal cancer procedure in patients over 65 years of age was comparable to that of younger patients, whereas long term cancer-related survival was statistically worst in older patients.

Adult↗

PubMed1994

Prognosis after extracorporeal shock wave lithotripsy of radiopaque renal calculi: a multivariate analysis.

To obtain a better understanding of the prognostic factors influencing treatment outcome after extracorporeal shock wave lithotripsy (ESWL), a multivariate logistic analysis of the data from 246 patients has been undertaken. All of the patients were treated with the Dornier lithotriptor HM-3 for radiopaque renal calculi. Treatment success was defined as stone-free within 3 months of one ESWL session and without adjuvant measures after ESWL. In a first analysis, 210 patients with solitary and multiple calculi without adjuvant measures before ESWL were studied. Of 210 patients, 141 (67%) were free from stones after 3 months). Significant influences on the success rate were body mass index and stone number. In a second analysis only those 160 patients with solitary calculi were considered. In this group, age, body mass index, stone location, stone burden and serum calcium significantly influenced the prognosis. When patients with adjuvant measures were added to the analysis an increasing prognostic importance of the stone burden was seen. In patients with a small to medium stone burden (< 4.0 cm3), the number of stones seemed to be more important than the stone burden. Patients appear to have the best chance for successful ESWL when their body mass index is between 20 and 28, their age is between 40 and 60 years, their stones are in the renal pelvis and solitary, the stone burden is < 1.0 cm3, and when their serum calcium is normal.

Adult↗

PubMed2001

Morphometric multivariate analysis of GABAergic neurons containing calretinin and neuronal nitric oxide synthase in the mouse hippocampus.

Several studies reported the morphology of calretinin-positive (CR+) neurons and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) labeled or neuronal nitric oxide synthase-positive (nNOS+) neurons in the rodent hippocampus, where these neurons showed similar morphological features. In addition, a previous study reported the frequent colocalization of CR and NADPH-d in the rat hippocampus. In this study, we aimed to examine whether CR+ neurons and nNOS+ neurons belong to a same morphological subpopulation of GABAergic neurons in the mouse hippocampus. Neurons were immunocytochemically classified into three groups, i.e., CR+/nNOS-, CR-/nNOS+ and CR+/nNOS+ groups. The present morphometric analysis was performed in the mouse Ammon's horn, because CR+/nNOS+ neurons were rarely found in the mouse dentate gyrus. We selected three morphometric parameters, i.e., soma area, soma form factor (FF) and number of primary dendrites. Dunnett's post-hoc analysis revealed that soma area, soma FF and number of primary dendrites were significantly larger in CR-/nNOS+ group than in CR+/nNOS- and CR+/nNOS+ groups. The morphometric data of CR+/nNOS+ group were quite similar to those of CR+/nNOS- group. The morphometric multivariate logistic regression analysis revealed that these three morphometric parameters were independent significant variables to discriminate between CR+/nNOS- and CR-/nNOS+ groups, and the majority of CR+/nNOS- and CR-/nNOS+ groups were correctly classified from the morphometric features. The present results clearly indicate that CR+/nNOS- neurons and CR-/nNOS+ neurons belong to different morphological subpopulations, and lead us to speculate that they might play different functional roles in the hippocampal circuit. The further application of morphometric multivariate analysis would be valuable to understand the functional roles of chemically defined neurons in the various brain regions.

Animals↗

PubMed1998

Primary radiotherapy of carcinoma of the supraglottic larynx--a multivariate analysis of prognostic factors.

PURPOSE: The aim of this study was to analyze the importance of different possible prognostic factors in cancer of the supraglottic larynx. METHODS AND MATERIALS: Nine hundred thirty-two patients with carcinoma of the supraglottic larynx were consecutively treated at The Finseninstitute in Copenhagen between 1966 and 1991. Of the patients, 768 treated with radiotherapy only were eligible for a multivariate Cox regression analysis of prognostic factors with local-regional control as endpoint. Of these, 73% (561) were men and 27% (207) women. Twelve factors: Age; gender; tumor size; site; T category (UICC78); nodal involvement (UICC 78); stage (UICC78); treatment period; tumor surface appearance; histopathologic differentiation; cord mobility; and hemoglobin level were tested. RESULTS: Only gender, T, N, and size proved to have independent significant prognostic importance in the multivariate analysis. A hazard index including these four factors for each patient was calculated, and eight risk groups formed. When the relative risks (RR) for these groups were plotted against the corresponding 5-year local-regional control failure rates, a very simple equation for the risk of failure could be derived as: 5-year local failure risk = 0.2 + 0.1 RR. CONCLUSION: We recommend that this estimation of an individual patient's risk of failure should be implemented in future clinical decision making.

Adult↗

PubMed2000

Long-term survival of transmural advanced gastric carcinoma following curative resection: multivariate analysis of prognostic factors.

Patients with transmural (T2N0-T3N2) advanced gastric carcinoma comprise the largest group with uncertain outcome. These patients must be stratified according to the prognostic variables so the high risk group can be precisely identified. A total of 152 patients with transmural advanced gastric carcinomas were uniformly treated with a curative intent between 1979 and 1989 with at least a 7-year follow-up. Results and prognostic factors of long-term survival were analyzed by univariate and multivariate analyses. Seventy-five (49%) patients with advanced gastric carcinoma survived more than 7 years, which indicates the curative nature of surgery for gastric carcinoma. Seventeen variables were evaluated by univariate analysis. In the multivariate analysis, patient's age [>70 years, relative risk (RR) 2.4)], intraoperative blood loss (>500 ml, RR 1.7), blood vessel invasion (RR 2.3), ratio of invaded dissected lymph nodes (>0.2, RR 3.0), and tumors penetrating the serosa (RR 3.9) were the independent prognostic variables. The results of this study indicate that extensive lymphadenectomy and minimal intraoperative blood loss might be helpful for improving patient survival following a curative resection. Patients with vessel invasion, serosal involvement, and those >70 years of age should be considered at high risk and require appropriate adjuvant therapy to prolong survival.

Adenocarcinoma↗

PubMed2002

Use of NIR and pyrolysis-MBMS coupled with multivariate analysis for detecting the chemical changes associated with brown-rot biodegradation of spruce wood.

Near infrared (NIR) spectroscopy and pyrolysis-molecular beam mass spectrometry (py-MBMS) analysis can be used in conjunction with multivariate regression and principal components analysis to differentiate brown-rot-degraded wood from non-degraded spruce and to follow the temporal changes in wood undergoing brown-rot degradation. Regression of NIR test results vs. percent weight loss for Postia placenta- and Gloeophyllum trabeum-infected spruce wood blocks yielded a correlation coefficient of 0.96. Regression of MBMS test results for the same samples yielded a correlation coefficient of 0.96. Principle components analysis was used to differentiate non-infected wood and P. placenta- and G. trabeum-infected wood. These techniques may be used to detect different types of biodegradation and to develop a better understanding of the chemical changes that the wood undergoes when it is subjected to brown-rot biodegradation.

Biodegradation, Environmental↗

PubMed1979

A multivariate analysis of fatness and relative fat patterning.

Skinfold measurements (triceps, subscapular, suprailiac and medial calf) in four samples (376 boys, 352 girs, 338 men and 380 women from rural Colombia) were subjected to principal components analysis to identify components of obesity and relative fat patterning. Three components emerged which were similar in the four samples: a first component of fatness explaining 70-80% of the variance and two fat pattern components each explaining 10-15% of the variance: trunk-extremity and upper-lower body. Fatness and the trunk-extremity pattern components changed with age in children (7-12 years), but none of the components changed with age in adults (25-60+). The fatter tended to be more patterned in both age groups. Canonical correlation analysis revealed that socioeconomic status was more related to fatness than to patterning. With the exception of brothers, all first degree relatives (sib, parent-off-spring) and spouses were correlated in fatness. Some of the correlations between relatives--usually sibs, but not spouses--were also significant for the pattern components, suggesting a genetic basis for the known stability of this characteristic (Garn, '55a). Principal components analysis is a useful multivariate alternative for quantitative studies of anthropometric patterning.

Adipose Tissue↗

PubMed1995

Multivariate analysis of limb long bone growth during the human prenatal period.

Prenatal development of the human limb bones (humerus, ulna, radius, femur, tibia, fibula) was studied. Cross-sectional data, consisting of 21 anthropometric measures of these bones were collected from 122 Japanese fetuses between the gestational ages of 18 and 40 weeks. Principal component analysis was applied to the data to provide multivariate assessments of morphological patterning among the variables. Three orthogonal components that accounted for 94.2% of the overall sample variation were extracted. The first component accounted for 88.2% of the variation and represented an axis of overall body size that was dependent on gestational age. The second and third components both reflected a trend in shape involving the cartilaginous parts of the humerus and femur. The findings indicated that different growth factors existed between the ossified and cartilaginous parts of fetal long bones. Multivariate allometric coefficients were extracted from the first principal component. The variables that were related to the construction of the articulate showed positive allometry, and the central widths of the diaphysis showed negative allometry compared with total size. In prenatal skeleton, certain shape changes are functionally linked to and required by changes in body size. A comparison among the coefficients of long bone length revealed that lower limb bones grew faster than upper limb bones during the period under study here. Allometric coefficients were equivalent among bones within a limb, whereas homologous bones in the upper and lower limb grew at different rates.

Bone and Bones↗