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PubMed2003

Preliminary report on the correlations among pineal concretions, prostatic calculi and age in human adult males.

By using quantitative image analysis of soft X-ray photographs on the bulk of extracted pineal glands and prostates, we made a preliminary investigation into the correlations among pineal concretions (% by mass), prostatic calculi (% by mass) and age (years) in 40 human adult males, ranging in age from 31 to 95 years (mean (+/-SD) 69.9 +/- 15.2 years), who died and underwent the routine dissection course. The mass concentrations of pineal concretions and prostatic calculi were 17.68 +/- 13.56% (range 0-51.34%) and 0.93 +/- 1.31% (range 0-5.82%), respectively. There was no correlation between the mass concentration of pineal concretions and aging (r = 0.03; P < 1.0). There was no correlation between mass concentration of prostatic calculi and aging (r = 0.28; P < 0.5). No pineal concretions and no prostatic calculi were observed in seven and 10 cases, respectively; in addition, in one case, neither-concretions nor calculi were seen. From such data and from the previously reported suggestion on the counteracting functions between the pineal gland and prostate, a negative correlation between the mass concentrations of pineal concretions and prostatic calculi was expected. This was certainly obtained, but the correlation was low (r = -0.39; P < 0.05). Such a low correlation and no correlations between the concentrations of pineal concretions and aging or between prostatic calculi and aging may have been caused by the examination of relatively older humans. Therefore, further investigations using a number of pair samples collected from males including younger age generations will be necessary.

Adult↗

PubMed2002

Correlation between midazolam and lignocaine pharmacokinetics and MEGX formation in healthy volunteers.

AIMS: The objectives of the present investigation were: (a) to determine the correlation between lignocaine and midazolam pharmacokinetics following intravenous administration in healthy volunteers, (b) to determine the effects of treatment with an inhibitor of CYP3A4 (erythromycin) on this correlation and (c) to assess the precision of the MEGX-test as a sole predictor of lignocaine and midazolam pharmacokinetics. METHODS: The study was conducted in four male and four female healthy volunteers, aged between 21 and 26 years, who received 1 mg kg-1 lignocaine HCl i.v. on days 1, 3, 5, 9 and 10 of the investigation. On days 5 and 10 they also received midazolam, 0.075 mg kg-1 i.v. and from days 6-10 they took erythromycin 500 mg orally, four times daily. Following administration of lignocaine and midazolam, frequent venous blood samples were obtained for determination of the concentrations of lignocaine, MEGX and midazolam. RESULTS: In the absence of erythromycin a statistically significant linear correlation was observed between the clearance of lignocaine and midazolam (CL(midazolam)= 0.41 x CL(lignocaine)+ 1.2; r(2) = 0.857; P < 0.001). Erythromycin cotreatment resulted in a loss of the correlation between the two clearances (r(2) = 0.39; P = 0.1). Erythromycin caused a statistically significant reduction in midazolam clearance from the original value of 3.8 to 2.5 (95% CI for the difference -2.27, -0.35) ml kg-1 min-1. Interestingly there was no significant change in the clearance of lignocaine (6.4 vs 5.8 (95% CI for the difference -2.74, -1.51) ml kg-1 min-1). Furthermore no correlation at all was observed between the MEGX-test and lignocaine or midazolam clearances. Considering the data on day 1, 3 and 5 the intra-individual coefficient of variation in the MEGX-test was 45.3% at 15 min and 23.5% at 30 min, respectively. CONCLUSIONS: It is concluded that there is a significant correlation between lignocaine and midazolam clearances but this correlation is lost after CYP3A4 inhibition by erythromycin. The MEGX-test is of no value in assessing intra- and inter-individual variability in midazolam clearance.

Adult↗

PubMed2001

Clinical correlates of Breslow thickness of malignant melanoma.

BACKGROUND: Breslow thickness is a major predictor of prognosis in cutaneous malignant melanoma (MM) and patients continue to present with thick lesions, which have a poorer prognosis. OBJECTIVES: To investigate correlations of Breslow thickness with demographic variables, tumour site, clinical features, false negative diagnostic rate and clinic of primary referral. METHODS: Data were obtained from the records of 738 patients with histologically diagnosed cutaneous MM. Tumours included were in situ and invasive MM and lentigo maligna melanoma. In view of the skewed distribution of MM thickness, categories of MM thickness were used for analysis, using the commonly applied cut-offs of 0.75, 1.5 and 3.5 mm. The variables investigated were particularly associated with changes in the proportion of the thickest group, 'thick' MMs. The proportion of this thickness category is proposed as an appropriate and sensitive variable for the investigation of correlations with MM thickness. Thickness >/= 1.5 mm has also been considered in view of its prognostic significance. RESULTS: Results were similar for the two thickness groups, but more significant for the thick group. The previously described correlations of tumour thickness and increasing age (P < 0.00001) and location on head and neck (P = 0.0002), together with the independence of these variables, have been confirmed. The correlation with male gender was also confirmed but this was weak (P = 0.05). Novel findings were correlations of Breslow thickness with all features of the seven-point checklist (P varying from P = 0.01 to P < 0.00001) and tumour elevation (P < 0.00001). In general in the seven-point checklist, the absence of the major features (except variation in size) (P < 0.00001) and presence of minor features (except altered sensation) (P varying from P = 0.004 to P < 0.00001) were strongly associated with thick MMs. These results for tumour thickness are a further argument for retention of the minor features of the seven-point checklist. False negative diagnosis was found to be correlated with tumour thickness (P < 0.02) but this relationship was lost on multivariate analysis with inclusion of the clinical features. MM thickness was highly correlated with primary referral clinic (P < 0.00001). Only approximately 8% of MMs presenting to the Pigmented Lesion Clinic (PLC) were thick, while the proportion presenting to general dermatology was about three times greater and to plastic surgery about five times greater. This was maintained on multivariate analysis, including all other variables and, therefore, there must be other determining factors of referral not examined in the study. Conclusion MM thickness is associated with increasing age, male gender, location on the head and neck, all features of the seven-point checklist, tumour elevation and referral to the PLC. It is important to investigate further the reasons for general practitioner referral of different thickness MM to different types of clinic, as referral to clinics other than the PLC results in delay in the first hospital appointment, and it is now apparent that thicker lesions are disproportionately affected.

Age Factors↗

PubMed2002

Quantitative in situ evaluation of telomeres in fluorescence in situ hybridization-processed sections of cutaneous melanocytic lesions and correlation with telomerase activity.

BACKGROUND: Telomere length is correlated with cellular ageing and immortalization processes. In some human cancers telomere length measurement has proved to be of diagnostic and prognostic value. Results comparable with the traditional terminal restriction fragment length determination by Southern blotting have been obtained in metaphase and interphase cells in some studies by fluorescence in situ hybridization (FISH) analysis; FISH additionally allows for the quantification of telomeres at the cellular level. OBJECTIVES: In this study, 32 melanocytic lesions were analysed by FISH, aiming at investigating possible telomere differences among various benign and malignant lesions and correlation with telomerase activity (TA) level. METHODS: FISH was performed on paraffin sections from six common naevi, eight Spitz naevi, 12 melanomas, six melanoma metastases and nine control samples of normal skin. Telomere mean maximum diameter (Feret max), area and number per nuclear area were calculated by image analysis on fluorescent images elaborated through KS400 and in situ imaging system (ISIS) for FISH analysis programs. Mean TA level was also calculated in all lesions and correlated with telomere parameters. RESULTS: Telomere number per nuclear area was significantly lower in melanomas and metastases than in benign common and Spitz naevi and in control skin (7 small middle dot24 +/- 3.3; 6.11 +/- 3 vs. 14.46 +/- 5.6; 16.92 +/- 7.8; and 12.59 +/- 3.4, respectively; P < 0 .001). No significant differences were found for the other telomere parameters. In common and Spitz naevi, telomere number was positively correlated with Feret max (P = 0.046 and P < 0.0001, respectively). TA was significantly higher in melanomas and metastases than in the other groups (70.18 +/- 25.2; 105.07 +/- 30 vs. 2.16 +/- 2.4; 2 .99 +/- 2.1; 2 +/- 1.2, respectively; P< or = 0. 001) and it was inversely correlated with telomere number per nuclear area in melanomas (P = 0.0041). No other significant correlations were found. CONCLUSIONS: Encouraging results have been obtained from quantitative telomere evaluation in the diagnosis of melanocytic lesions, although an analysis of a larger number of cases would be necessary to provide more reliable data. An extreme shortening of some telomeres probably results in the decrease of telomeric signals and the lower mean number of detectable telomeres in melanomas and metastases. In melanomas, telomere number per nuclear area is also inversely correlated with TA levels. Quantitative FISH of melanocytic lesions could give more specific information at the cellular level in telomere and telomerase fields of investigation.

Case-Control Studies↗

PubMed1999

Correlation between cortisol and insulin-like growth factor-binding proteins (IGFBPs) under physiological conditions in children.

OBJECTIVE: A positive correlation between 24-h spontaneous growth hormone (GH) and cortisol secretion was previously reported in children. This observation prompted us to examine the relationship between physiological diurnal cortisol variation and the levels of insulin-like growth factors (IGFs) and IGF-binding proteins (IGFBPs) under physiological conditions. DESIGN AND PATIENTS: Starting at 0800 h, blood was sampled every 20 minutes over 24 h for measurement of GH and cortisol concentration in nine non-GH- deficient boys as part of a protocol for the investigation of short stature. MEASUREMENTS: IGFBP-1 and insulin were measured in samples drawn every 4 h over the 24-h period while IGF-I, IGF-II, IGFBP-2 and IGFBP-3 were determined in samples collected at the end of the study. RESULTS: No correlation was observed between IGF-I or IGF-II and mean cortisol levels. IGFBP-1 concentrations showed a marked circadian variation that was superimposed on the circadian rhythm for cortisol while a significant positive correlation was found for single point measurements between IGFBP-1 concentrations and cortisol levels measured in the same sample (r = 0.53) or at the preceding 20 minutes (r = 0.43), 40 minutes (r = 0.47) and 2 h (r = 0.38), suggesting an interplay between cortisol and IGFBP-1. A negative correlation (r = - 0.54) was found between IGFBP-1 and insulin levels determined in the same sample. A negative correlation (r = - 0.93) was also found between IGFBP-2 levels and mean cortisol concentrations during the preceding 12 h. No correlation was observed between plasma IGFBP-3 measured by IRMA and mean cortisol levels. CONCLUSION: Our data indicate a clear correlation between cortisol and IGFBP-1 and IGFBP-2 levels. Thus, the interplay of spontaneous GH and cortisol secretion in children may involve changes in IGFBP-1 and IGFBP-2 levels.

Adolescent↗

PubMed1999

Expression of Bcl-2, but not Bax, correlates with estrogen receptor status and tumor proliferation in invasive breast carcinoma.

Bcl-2 and Bax have been demonstrated to be associated with apoptosis in breast carcinoma, and the ratio between Bax and Bcl-2 seems to be an important determinant of cellular sensitivity to induction of apoptosis. However, little information is available on the relationship between Bcl-2, Bax and the proliferative activity of breast carcinoma. The purpose of this study was to investigate the significance of apoptosis-related genes bcl-2 and Bax and their correlation with expression of p53, tumor proliferation defined by MIB-1 expression and estrogen receptor status. Immunohistochemistry was performed to determine Bcl-2, Bax, p53, estrogen receptor (ER) and MIB-1 expression in paraffin-embedded tissues of 177 invasive breast cancers. Expression of the anti-apoptotic protein Bcl-2 was not correlated with the pro-apoptotic Bax. Bcl-2 immunostaining displayed a negative correlation with increasing histologic grade, p53 and MIB-1 (P < 0.0001, P < 0.05 and P < 0.0001, respectively) and a positive correlation with rising ER immunostaining (r = 0.305, P < 0.0001). Conversely, expression of the apoptosis-promoting protein Bax did not correlate with increasing histologic grade, p53, MIB-1 or ER status. Neither Bcl-2 expression nor Bax expression correlated with age, menopausal status, tumor size, histologic type or axillary lymph node status. These results imply that Bcl-2 is associated with good prognostic markers and the regulation of Bax is complex and does not necessarily correlate with mutant p53 status in breast cancers.

Adenocarcinoma↗

PubMed1997

The correlation between prostate volume, transition zone volume, transition zone index and clinical and urodynamic investigations in patients with lower urinary tract symptoms.

OBJECTIVE: To determine if, in patients with lower urinary tract symptoms (LUTS), measurement of the transition zone (TZ) of the prostate by transrectal ultrasonography (TRUS) and the ratio between the TZ volume and total prostate volume (TZ index) correlates better with clinical and urodynamic investigations than total prostate volume alone. PATIENTS AND METHODS: In total, 150 consecutive patients with LUTS underwent a standardized screening programme including the International Prostate Symptom Sore (IPSS), a physical examination, TRUS of the prostate and urodynamic investigations with pressure-flow studies. The total prostate volume and TZ volume were assessed from TRUS using the ellipsoid formula. Spearman's rank correlation coefficients were calculated between different prostate volume measurements and specific symptomatic and urodynamic variables. RESULTS: The relationships between specific IPSS symptoms, symptom scores and the prostate volume measurements were not statistically significant except for one domain, nocturia, that appeared to be statistically significantly correlated with the TZ index (r = 0.25). The correlations for free flow, pressure-flow variables and prostate volume measurements were stronger, but only moderate at best. The highest correlations were between TZ volume and the linear passive urethral resistance obstruction category, urethral resistance factor and detrusor pressure at maximum flow (r = 0.43, 0.44 and 0.40, respectively). The differences between the correlations of prostate volume and TZ index and these variables were small (r = 0.39, 0.38 and 0.37, respectively for prostate volume and r = 0.38, 0.40 and 0.33 respectively for TZ index). CONCLUSIONS: There were very small differences between the correlations of total prostate volume, TZ volume and TZ index, and clinical and pressure-flow variables. In the assessment of the last two, the estimation of the total prostate volume by TRUS was a reasonable way to obtain the required information about prostate size and measuring TZ volume and calculating TZ index was of limited additional value. Symptoms and bladder outlet obstruction were mainly determined by other factors than the prostate and, specifically, TZ volume. As earlier studies have indicated that including pressure-flow data in the pre-operative evaluation and selection of patients for interventional therapies may improve the overall clinical results, we think that prostate volume, TZ volume or symptoms alone should not be used as the main indication for deciding on the appropriate invasive treatment options.

Adult↗

PubMed2003

Correlation analysis of visual field thresholds and scanning laser ophthalmoscopic optic nerve head measurements in glaucoma.

In a cross-sectional study of 50 consecutive primary open-angle glaucoma cases, full threshold 30-2 visual fields on Humphrey Visual Field Analyser were correlated to stereometric parameters obtained using a scanning laser ophthalmoscope (HRT II). The strength of linear correlation between the stereometric parameters and visual thresholds was used to generate a correspondence map between the optic disc and the visual field. Rim/disc area ratio and cup/disc area ratio correlated with the visual thresholds at the highest number of points in the visual fields. Thresholds at superior hemifield locations correlated best with the rim/disc area ratio and cup/disc area ratio in the inferonasal sector and the ones in the inferior hemifield correlated best with the rim/disc area ratio and cup/disc area ratio in the superotemporal sector. Optic disc parameters correlated better with inferior field locations and non-edge points than superior field locations and edge points. The data indicate that rim/disc area ratio and cup/disc area ratio measurements on HRT II have a good correlation with visual field damage seen on automated visual fields.

Adult↗

PubMed2003

Arthroscopic treatment of osteochondral lesions of the talus with correlation of outcome scoring systems.

PURPOSE: The goal of this study was to perform a retrospective review of arthroscopically treated osteochondral lesions of the talus (OCLTs) to determine their outcome and to analyze the correlation of 3 subjective outcome scoring systems for the ankle. METHODS: Between 1985 and 1999, 37 arthroscopic debridement or subchondral drilling procedures were performed on 33 ankles to treat OCLTs. The charts of these patients were reviewed for general demographic, preoperative, surgical, and postoperative information. Patients were sent a questionnaire that included 3 subjective outcome scoring systems: the Martin Score questionnaire; the Berndt and Harty scale; and the Single Assessment Numeric Evaluation (SANE) question. Twenty-eight people responded to the questionnaire. Twenty-four patients reported a history of trauma. There were 17 lesions on the medial aspect of the talus, 10 laterally, and 1 centrally. The lesions were classified according to their arthroscopic appearance. There were 7 stage I, 2 stage II, 10 stage III, and 9 stage IV lesions. After all data were analyzed, the Pearson product-moment correlation coefficient (r) and correlation of determination (r2) were performed among the 3 outcome scales. RESULTS: The mean follow-up time was 66 months (range, 6-169 months). Outcome results varied according to the scoring system. Using the Berndt and Harty scale, 13 (46%) patients had good, 13 (46%) fair, and 2 (8%) poor results. According to the Martin Score, 1 patient (4%) had excellent, 10 (35%) good, 9 (32%) fair, and 8 (29%) had poor results. According to the SANE score, 5 patients (18%) had excellent, 8 (29%) good, 9 (32%) fair, and 6 (21%) had poor results. Seventeen patients reported some form of pain at follow-up examination. Analysis of variables, including age at operation, stage of the lesion, length of follow-up, and previous surgery revealed no statistical significance. All 3 scales showed positive correlations. Based on these outcome data, the Berndt and Harty scale showed good correlation with both the SANE and the Martin outcome systems (r =.81 and r =.69, respectively). The Martin Score showed moderate correlation with the SANE outcome system (r =.57). CONCLUSIONS: The outcome results for our patient population were not as successful as has been previously reported. Our analysis showed positive correlation among the 3 subjective outcome systems. However, it remains difficult to compare these data with previous results secondary to the variety of outcome measures employed by previous reports in the literature.

Adolescent↗

PubMed1990

[Correlation of immunoglobulins, the complement system and inflammatory mediators with reference to the pathogenesis of serous otitis media].

Otitis media with effusion (OME) is a very common pediatric disease of unknown etiology which sometimes leads to chronic recurrent OME. The author investigated 90 secretions (39 serous/51 mucous) of 61 children whose ages ranged from 1 to 14 years (mean = 4.9 +/- 2.2) for correlations of Immunoglobulins A, E, G, M, the complement system and mediators of inflammation: histamine, Bradykinin, PGE2 and LTC4. A highly significant increase in IgA and IgG and a decrease in IgM and IgE were found in the secretions as compared to the serum concentrations. These data support the hypothesis that there is an independent mucosal immune response in the middle ear. The protein concentration was significantly higher in the mucous than in the serous secretion; for the other parameters determined only a slight tendency toward higher levels in serous secretions was found. There was a slight positive correlation between IgA and IgG in serum, and in particular in the serous secretions. A slightly negative correlation between IgM and IgE was found only in serum. The secretion showed highly significant correlations between the following: IgG:IgM, IgG:IgA, IgA:IgM, IgG:Kinin, C3c:Kinin and lg Histamine:lg PGE2. The correlations were stronger in serous than in mucous secretions. Only in mucous secretions there were any significant correlations between IgE:IgG, lg IgE:lg Kinin, and a negative correlation between IgE:C3c. Serous and mucous secretions represent different stages of inflammation. The kallikrein kinin system, complement-system, and the arachidonic acid cascade, especially the cyclo-oxygenase pathway, play a role in OME. Bradykinin showed a connection between the activated complement system and the immune system.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1988

[Parapapillary region in normal and glaucoma eyes. II. Correlation of planimetric findings to intrapapillary, perimetry and general data].

The planimetric values of the parapapillary region in 312 unselected eyes with chronic primary open-angle glaucoma and 125 normal eyes of an age-/and refraction-matched control group were correlated to the intrapapillary, perimetric, and general data of these eyes. High myopics (less than -8.00 D) and "ocular hypertensives" were excluded. Zone "Alpha" and "Beta" incipient to advanced or subtotal to total parapapillary chorio-pigmentepithelioretinal atrophy) were significantly correlated (p less than 0.001) to: 1) area and width of the neuroretinal rim as a whole and in four different optic disk sectors; 2) cup area; 3) horizontal and vertical c/d ratios; 4) glaucoma stage; 5) age, and 6) refraction. Zone "Beta" was additionally correlated to the perimetric indices. Its correlation coefficients were generally higher than those of zone "Alpha." Sex and side showed no significant relationships. Divided into four different radial sectors, both zones "Alpha" and "Beta" were significantly larger (p less than 0.001) the smaller the neuroretinal rim area (intrapapillary) in the same sector was. Additionally, zone "Beta" was significantly (p less than 0.001) most often largest in the sector where the rim area was smallest. Thus, besides the temporal there was also a spatial correlation between the intrapapillary and parapapillary glaucomatous alterations. "Conus pigmentosus" and the peripapillary scleral rim showed no significant glaucoma-associated correlations and are thus without importance for quantified optic disk evaluation in glaucoma. Zones "Alpha" and "Beta", as regions of early to advanced of subtotal to total parapapillary, chorio-pigmentepithelioretinal atrophy, are not only chronologically but also spatially correlated to intrapapillary glaucomatous changes and are important in optic disk evaluation in glaucoma.

Female↗

PubMed2004

On the calculation of single-particle time correlation functions from Bose-Einstein centroid dynamics.

The calculation of single-particle time correlation functions using the Bose-Einstein centroid dynamics formalism is discussed. A new definition of the quasidensity operator is used to calculate the centroid force on a given particle for an anharmonic system. The force includes correlation effects due to quantum statistics and is used for the calculation of the classical-like dynamics of phase-space centroid variables within the centroid molecular dynamics approximation. Time correlation functions are then obtained for single-particle quantities. These correspond to the double-Kubo transform of exact quantum-mechanical correlation functions. The centroid dynamics results are compared to those of exact basis-set calculations and a good agreement is found. The level of accuracy is in fact the same as what was observed earlier for the calculation of center-of-mass correlation functions for Fermi-Dirac and Bose-Einstein statistics, and for any correlation function for Boltzmann statistics. These results show that it is now possible to use Bose-Einstein centroid molecular dynamics to calculate single-particle correlation functions for systems where quantum exchange effects are present.

Journal Article↗

PubMed2005

Local correlation measures in atomic systems.

The phenomenon of electron correlation in atomic systems is examined and compared from the statistical, information theoretic, and energetic perspectives. Local correlation measures, based on the correlation coefficient, information entropies, and idempotency measure, are compared to the correlation energy density. Analysis of these local measures reveals that the chemically significant valence region is responsible for the behavior of their respective global measures in contrast to the correlation energy density which has large contributions to the correlation energy from both the core and valence regions. These results emphasize the difference in the mechanisms inherent in the different perspectives, the similarity between the statistical, information entropic, and idempotency views, and provides further evidence for the use of information theoretic based quantities in studies of electron correlation.

Journal Article↗

PubMed2005

Second-order Kohn-Sham perturbation theory: correlation potential for atoms in a cavity.

Second-order perturbation theory based on the Kohn-Sham Hamiltonian leads to an implicit density functional for the correlation energy E(c) (MP2), which is explicitly dependent on both occupied and unoccupied Kohn-Sham single-particle orbitals and energies. The corresponding correlation potential v(c) (MP2), which has to be evaluated by the optimized potential method, was found to be divergent in the asymptotic region of atoms, if positive-energy continuum states are included in the calculation [Facco Bonetti et al., Phys. Rev. Lett. 86, 2241 (2001)]. On the other hand, Niquet et al., [J. Chem. Phys. 118, 9504 (2003)] showed that v(c) (MP2) has the same asymptotic -alpha(2r(4)) behavior as the exact correlation potential, if the system under study has a discrete spectrum only. In this work we study v(c) (MP2) for atoms in a spherical cavity within a basis-set-free finite differences approach, ensuring a completely discrete spectrum by requiring hard-wall boundary conditions at the cavity radius. Choosing this radius sufficiently large, one can devise a numerical continuation procedure which allows to normalize v(c) (MP2) consistent with the standard choice v(c)(r-->infinity)=0 for free atoms, without modifying the potential in the chemically relevant region. An important prerequisite for the success of this scheme is the inclusion of very high-energy virtual states. Using this technique, we have calculated v(c) (MP2) for all closed-shell and spherical open-shell atoms up to argon. One finds that v(c) (MP2) reproduces the shell structure of the exact correlation potential very well but consistently overestimates the corresponding shell oscillations. In the case of spin-polarized atoms one observes a strong interrelation between the correlation potentials of the two spin channels, which is completely absent for standard density functionals. However, our results also demonstrate that E(c) (MP2) can only serve as a first step towards the construction of a suitable implicit correlation functional: The fundamental variational instability of this functional is recovered for beryllium, for which a breakdown of the self-consistent Kohn-Sham iteration is observed. Moreover, even for those atoms for which the self-consistent iteration is stable, the results indicate that the inclusion of v(c) (MP2) in the total Kohn-Sham potential does not lead to an improvement compared to the complete neglect of the correlation potential.

Algorithms↗

PubMed2006

Calculations of nuclear quadrupole coupling in noble gas-noble metal fluorides: interplay of relativistic and electron correlation effects.

The nuclear quadrupole coupling constants (NQCCs) of noble gas and noble metal nuclei in the recently found noble gas-noble metal fluorides (NgMF, where Ng=Ar,Kr,Xe and M=Cu,Ag,Au) are obtained theoretically by high-level ab initio calculations, where both relativistic and electron correlation effects are included, and compared to experimental results. Fully relativistic four-component Dirac-Hartree-Fock (DHF) calculations are carried out at the basis set limit for electric field gradient that couples with the electric quadrupole moment of the nucleus, and uncorrelated relativistic effects are extracted by comparing DHF results to nonrelativistic (NR) HF calculations. Electron correlation effects are investigated both at fully relativistic second-order Moller-Plesset (DMP2) and at NR MP2 levels of theory, as well as at the NR coupled-cluster singles and doubles with perturbational triples [CCSD(T)] level. The validity of the approximation where relativistic effects, on the one hand, and nonrelativistically obtained correlation effects, on the other hand, are evaluated separately and assumed to be additive, is investigated by comparison with the DMP2 results. Inclusion of relativistic effects is shown to be necessary for obtaining the correct NQCC trends as the nucleus of interest and/or its neighbors become heavier. Electron correlation treatment is needed for approaching quantitative agreement with the experimental NQCCs. The assumption of additive electron correlation and relativistic effects, corresponding to the NR correlation treatment added on top of relativistic DHF data, gives qualitatively correct noble gas NQCCs. For noble metal NQCCs, correlation treatment at the relativistic level of theory is mandatory for reaching agreement with experimental results. Current work also confirms the experimental trends of NQCCs, which have been taken as an indication of nearly covalent interaction between noble gas and noble metal in the heaviest present systems, especially in XeAuF.

Journal Article↗

PubMed2003

Three-dimensional reconstruction of magnetic resonance images of the anal sphincter and correlation between sphincter volume and pressure.

OBJECTIVE: The purpose of this study was to assess the correlation between internal and external anal sphincter volumes and manometric anal pressures. STUDY DESIGN: Ten healthy nulliparous women underwent anal sphincter magnetic resonance imaging and anal manometry measurement. A 3-dimensional reconstruction of magnetic resonance images was accomplished with the use of 3-dimensional slicer. Sphincter volumes were measured 3 times by the same observer for each of 10 patients. The intrarater reliability was measured with the use of the intraclass correlation coefficient (ICC = sigma (2)(patients)/(sigma (2)(patients) + sigma (2)(error))) from a 2-way analysis of variance model with terms for patient and measurement trial. Measurements that were recorded on anal manometry included squeeze length, length of the high-pressure zone, and maximal resting and squeeze pressures. RESULTS: The mean volumes (+/- SD) were 18.77 +/- 4.64 cm(3), 13.82 +/- 3.8 cm(3), and 32.36 +/- 8.37 cm(3) for internal, external, and combined sphincters, respectively. Intrarater reliability was 98% for external sphincter volume (95% CI, 94%-99%), 98% for internal sphincter volume (95% CI, 94%-99%), and 99% for total volume (95% CI, 97%-100%). On the 3-dimensional images, the internal sphincter was found to be cylindric in shape, with an ellipse as a base. It is elongated in the anterior and posterior direction and flattened on the sides. The external sphincter was found to be funnel-shaped, being narrower caudad and widening in the cephalad direction. Similar to the internal sphincter, the external sphincter is elongated in the anteroposterior diameter. Volumes of the internal, external, and combined sphincters did not correlate with the maximum pressures at rest and squeeze. Correlations higher than r = 0.5 were observed for all 3 sphincter volume measurements versus high pressure zone at squeeze. The highest correlation, r = 0.66, was for internal sphincter volume versus high pressure zone at squeeze CONCLUSION: Three-dimensional reconstruction of the rectal sphincter musculature can be performed easily with 3-dimensional software. Measurements of the sphincter volumes have excellent intrarater reliability. Sphincter volumes do not correlate with pressures at rest or squeeze, but the internal sphincter volume correlates with the length of the high pressure zone at squeeze. Contrary to current generalized concepts, it is possible that the internal sphincter may play some role in generating the squeeze pressure. More research is necessary in applying 3-dimensional magnetic resonance image reconstruction in patients with different parity and continence status. Reconstruction of magnetic resonance images of the rectal sphincter musculature may prove to be beneficial in planning the treatment of patients with fecal incontinence.

Adult↗

PubMed1998

The C-reactive protein to prealbumin ratio correlates with the severity of multiple organ dysfunction.

BACKGROUND: This study evaluates the correlation between a ratio of two hepatic proteins, C-reactive protein (CRP) and prealbumin (PALB), and the severity of organ dysfunction as measured by the multiple organ dysfunction score (MODS). METHODS: A prospective cohort study was undertaken in critically ill patients (n = 70) by measuring the serum levels of CRP and PALB, the energy expenditure via indirect calorimetry, and severity of organ dysfunction by the MODS. All three variables were recorded for a period of 5 days from admission and then assessed for correlation to each other and to the length of stay and mortality in the intensive care unit. RESULTS: The CRP/PALB ratio showed a statistically significant correlation at 48 hours (r = 0.45, P < .01) and 120 hours (r = 0.53, P < .01). This ratio showed higher degrees of correlation when applied to patients with a diagnosis of sepsis, multiple organ dysfunction, or single organ dysfunction, r = 0.71 and 0.56 at 48 and 120 hours, respectively. Receiver operating characteristics (ROC) curves show that a ratio of 2.07 correlated with a MODS of 16 with a sensitivity of 92% and a specificity of 71%. CONCLUSIONS: This study demonstrates a strong correlation between the severity of organ dysfunction and the ratio of two hepatic proteins, CRP and PALB. There was no correlation between the degree of energy expenditure and the MODS, Acute Physiology and Chronic Health Evaluation II score, or the ratio of CRP/PALB. The use of inflammatory markers may be an easy, inexpensive method of assessing severity of illness in the critically ill.

APACHE↗

PubMed1992

Correlation analysis of amino acid usage in protein classes.

We present a comparative study of residue usage correlations of various organism protein sets of diverse phylogenetic species and of open reading frames of several large human viral genomes. Our correlation analysis reveals three major tendencies: (i) charge compensation reflected by the high correlation of basic with acidic residues; (ii) the positive correlations of functionally and structurally similar amino acids including many pairs of hydrophobic amino acids, all pairs of aromatic amino acids, the anionic pair (glutamate and aspartate), but not the cationic pair (lysine and arginine), moderately the hydroxyl pair (serine and threonine), the small amino acids (glycine and alanine), and many (but not all) of those having high values in the Dayhoff substitutability matrix (characteristics such as amino acid polarity or codon usage agreement, except for the wobble position, do not necessarily imply significant positive correlations); (iii) a widespread negative correlation of the aggregate strong codon group amino acids (Ala, Gly, Pro) versus the weak codon group amino acids (Lys, Ile, Tyr, Asn, Phe). Discussion and speculations relate amino acid usage correlations to protein function/structure, cellular localization, proximity in amino acid biosynthetic pathways, amino acid relative abundances, tRNA and aminoacyl synthetase availabilities, and evolutionary processes.

Amino Acids↗