Extreme Subgroups Research Articles

No Influence of Body Weight on Serum Levels of Antidepressants

Body weight may affect pharmacokinetic parameters in various ways and may therefore have a significant impact on the serum concentration of a drug at a given dose. Although patients with major depressive disorder frequently show an elevated body mass index, studies investigating the relation between body weight and serum concentration of antidepressants are lacking. This study should help to clarify the influence of body weight on the serum levels of the antidepressants amitriptyline (AMI), clomipramine (CLO), doxepine (DOX), escitalopram (ESC), and venlafaxine (VEN) in a naturalistic clinical setting. Therapeutic drug monitoring analyses obtained in the psychiatric university hospital of Wuerzburg from patients treated with AMI (n = 171), CLO (n = 94), DOX (n = 133), ESC (n = 19), and VEN (n = 24) were retrospectively assessed. The influence of body weight on dose-corrected serum concentrations was evaluated by Spearman-Rho correlations and by comparing dose-corrected serum levels in patients with low and high body weight (first versus fourth quartile). The serum concentrations were determined by high-performance liquid chromatography methods in the therapeutic drug monitoring laboratory of the psychiatric university hospital of Wuerzburg. Dose-corrected serum concentrations did not significantly correlate with body weight in patients treated with AMI, CLO, DOX, ESC, or VEN. There was no significant difference in the dose-corrected serum concentrations of AMI, CLO, and DOX between patients of the first and fourth quartiles of body weight. The latter evaluation was not performed for ESC and VEN because of too small samples. Against the intuitive presumption of a weight dependency of dose-corrected serum concentrations, the findings suggest that there is no relevant influence of body weight on the dose-corrected serum level of several widely used antidepressants even if extreme subgroups of patients with low and high body weights are considered.

Extremal and maximal normal abelian subgroups of a maximal unipotent subgroup in groups of Lie type

We describe all maximal abelian normal subgroups in the unipotent radical U of a Borel subgroup in a group of Lie type G over a field K. This gives a new description of the extremal subgroups in U which were studied by C. Parker and P. Rowley. For a finite field K, we prove that either each large abelian subgroup in U is G-conjugate to a normal subgroup in U or G is of certain exceptional Lie type.

No influence of body weight on serum levels of antidepressants

Background Body weight may affect pharmacokinetic parameters in various ways and may therefore have a significant impact on the serum concentration of a drug at a given dose. Although patients with major depressive disorder frequently show an elevated body mass index, studies investigating the relation between body weight and serum concentration of antidepressants are lacking. This study should help to clarify the influence of body weight on the serum levels of the antidepressants amitriptyline (AMI), clomipramine (CLO), doxepine (DOX), escitalopram (ESC), and venlafaxine (VEN) in a naturalistic clinical setting. Methods Therapeutic drug monitoring analyses obtained in the psychiatric university hospital of Wuerzburg from patients treated with AMI (n = 171), CLO (n = 94), DOX (n = 133), ESC (n = 19), and VEN (n = 24) were retrospectively assessed. The influence of body weight on dose-corrected serum concentrations was evaluated by Spearman-Rho correlations and by comparing dose-corrected serum levels in patients with low and high body weight (first versus fourth quartile). The serum concentrations were determined by high-performance liquid chromatography methods in the therapeutic drug monitoring laboratory of the psychiatric university hospital of Wuerzburg. Results Dose-corrected serum concentrations did not significantly correlate with body weight in patients treated with AMI, CLO, DOX, ESC, or VEN. There was no significant difference in the dose-corrected serum concentrations of AMI, CLO, and DOX between patients of the first and fourth quartiles of body weight. The latter evaluation was not performed for ESC and VEN because of too small samples. Conclusions Against the intuitive presumption of a weight dependency of dose-corrected serum concentrations, the findings suggest that there is no relevant influence of body weight on the dose-corrected serum level of several widely used antidepressants even if extreme subgroups of patients with low and high body weights are considered.

Performance of the Cockcroft-Gault, MDRD, and New CKD-EPI Formulas in Relation to GFR, Age, and Body Size

We compared the estimations of Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations to a gold standard GFR measurement using (125)I-iothalamate, within strata of GFR, gender, age, body weight, and body mass index (BMI). For people who previously underwent a GFR measurement, bias, precision, and accuracies between measured and estimated kidney functions were calculated within strata of the variables. The relation between the absolute bias and the variables was tested with linear regression analysis. Overall (n = 271, 44% male, mean measured GFR 72.6 ml/min per 1.73 m(2) [SD 30.4 ml/min per 1.73 m(2)]), mean bias was smallest for MDRD (P < 0.01). CKD-EPI had highest accuracy (P < 0.01 compared with Cockcroft-Gault), which did not differ from MDRD (P = 0.14). The absolute bias of all formulas was related to age. For MDRD and CKD-EPI, absolute bias was also related to the GFR; for Cockcroft-Gault, it was related to body weight and BMI as well. In all extreme subgroups, MDRD and CKD-EPI provided highest accuracies. The absolute bias of all formulas is influenced by age; CKD-EPI and MDRD are also influenced by GFR. Cockcroft-Gault is additionally influenced by body weight and BMI. In general, CKD-EPI gives the best estimation of GFR, although its accuracy is close to that of the MDRD.

The Five Factor Model and Accessibility/Remoteness: Novel evidence for person–environment interaction

The Accessibility/Remoteness Index of Australia (ARIA) is a validated index of the availability of services and opportunities for social interaction afforded by every location in Australia. ARIA therefore measures a feature of the social environment, and provides a unique foundation for investigating the relationship between persons and environments. The present study used ARIA alongside a measure of the Five-Factor Model of personality to test predictions about person–environment interactions deduced from the seminal work of Emmons and colleagues. Survey responses were received from N = 7615 adults residing across a range of non-metropolitan locales ranging from very accessible (ARIA = 0.0) to very remote (ARIA = 11.1). Respondents were categorised into High, Moderate and Low Accessibility based on the ARIA value of their location of residence. Consistent with the choice of situations model, average levels of the traits openness to experience (O) and extraversion (E) tended to be higher amongst respondents living in High Accessibility locations. As predicted under the affect congruence model, analyses of extreme subgroups found that for both O and E, those respondents high on the trait who resided in more accessible locales reported higher Positive Affect than similar respondents who resided in less accessible locales. Avenues for future research are discussed in light of the findings and the present study’s limitations.

Memory and self-induced shocks in an evolutionary population competing for limited resources

We present a detailed discussion of the role played by memory, and the nature of self-induced shocks, in an evolutionary population competing for limited resources. Our study builds on a previously introduced multiagent system [Phys. Rev. Lett. 82, 3360 (1999)] which has attracted significant attention in the literature. This system exhibits self-segregation of the population based on the "gene" value p (where 0< or =p< or =1 ), transitions to "frozen" populations as a function of the global resource level, and self-induced large changes which spontaneously arise as the dynamical system evolves. We find that the large, macroscopic self-induced shocks that arise are controlled by microscopic changes within extreme subgroups of the population (i.e., subgroups with "gene" values p approximately 0 and p approximately 1).

Special Image Contents, Personality Features, and Aesthetic Preferences

The theory of aesthetic emotion predicts higher aesthetic appraisals when images fit the beholder's main motivations, and, moreover, a relative equivalence between representations of violent scenes or incongruent configurations sensu strictu (Bonaiuto, 1966, 1983, 1998). Our new study aimed to specify distinctions among conflictual images, providing insights into taste formation processes that prefigure substantial differences found in studies on adulthood. Ten pairs of color laser reproductions of paintings by great artists were prepared, contrasting harmonious configurations with scenes strongly contradicting expectations. Five pairs contained an openly aggressive scene juxtaposed by a calm one; the others a structurally very incongruous picture juxtaposed by a congruent one. We first examined 500 children (7-10 years old), with appropriate scales, selecting two extreme subgroups: very aggressive and pro-social subjects (“altruists”). The image pairs were individually presented, recording the preferences. Data show a clear rejection of aggressive images by altruists, and attraction for such images in aggressive participants. The latter, nevertheless, had a greater liking for the incongruous images, that more indirectly and symbolically correspond to destructive drives. Socio-cultural variables were found to be non-influential.

Unique Node Extremal Subgroups in Chevalley Groups

Taking G to be a Chevalley group of rank at least 3 and U to be the unipotent radical of a Borel subgroup B,an extremal subgroup A is an abelian normal subgroup of U which is not contained in the intersection of all the unipotent radicals of the rank 1 parabolic subgroups of G containing B. If there is an unique rank 1 parabolic subgroup P of G containing B with the property that A is not contained in the unipotent radical of P,then A is called a unique node extremal subgroup. In this paper we investigate the embedding of unique node extremal subgroups in U and prove that,apart from some specified cases,such a subgroup is contained in the unipotent radical of a certain maximal parabolic subgroup.

Peritraumatic dissociation and physiological response to trauma-relevant stimuli in Vietnam combat veterans with posttraumatic stress disorder.

A recent study found that female rape victims with acute posttraumatic stress disorder (PTSD) who received a high score on the Peritraumatic Dissociative Experiences Questionnaire exhibited suppression of physiological responses during exposure to trauma-related stimuli. The goal of our present study was to test whether the same relationship holds true for male Vietnam combat veterans with chronic PTSD, using secondary analyses applied to data derived from a Veteran's Affairs Cooperative Study. Vietnam combat veterans (N = 1238) completed measures to establish combat-related PTSD diagnostic status, extent of PTSD-related symptomatic distress, and presence of dissociative symptoms during their most stressful combat-related experiences. Extreme subgroups of veterans with current PTSD were classified as either low dissociators (N = 118) or high dissociators (N = 256) based on an abbreviated version of the Peritraumatic Dissociative Experiences Questionnaire. Dependent variables reflected subjective distress along with heart rate, skin conductance, electromyographic, and blood pressure data when responding to neutral and trauma-related audiovisual and imagery presentations. Veterans in the current PTSD group had significantly higher dissociation scores than did veterans in the lifetime and never PTSD groups. Among veterans with current PTSD, high dissociators reported greater PTSD-related symptomatic distress than did low dissociators, but the groups did not differ with respect to physiological reactivity to the trauma-related laboratory presentations. Our results replicate the previously reported relationship between peritraumatic dissociation and PTSD status in Vietnam combat veterans. However, we found no association between peritraumatic dissociation and the extent of physiological responding to trauma-relevant cues in male veterans with chronic combat-related PTSD.

Natural changes in peritoneal equilibration test results in continuous ambulatory peritoneal dialysis patients: a retrospective, seven year cohort survey.

We conducted a retrospective, 7 year cohort survey to examine the natural changes in peritoneal equilibration test (PET) results in patients with long-term uneventful continuous ambulatory peritoneal dialysis (CAPD). Thirty-two (17 males, 15 females) patients on CAPD with two or more standard PETs performed more than 6 months apart, in the absence of peritoneal insult, were included. Changes and pattern of PET results were evaluated by the dialysate to plasma ratio of creatinine (D:P-cre), the fourth h dialysate to instilled glucose ratio (D4:Do) and ultrafiltration volume (UF, ml). The subgroups included high (H), high-average (HA), low-average (LA), or low (L) transporters with the dividing ratios (D:P-cre) of >0.81, >0. 65 to 0.81, >0.5 to 0.65, and <0.5, respectively. The median D:P-cre significantly decreased (p = 0.04), but neither the D4:Do nor the final median UF significantly decreased. The change in D:P-cre was strongly and inversely correlated with the initial D:P-cre value (r = -0.68; p < 0.05). A similar relationship was found between the change in the final D4:Do and the initial D4:Do (r = -0.752; p < 0. 01) and between the change in the final UF and the initial UF (r = -0.875; p < 0.01). No correlation was found between the change in D:P-cre and the age of the patient, the time interval between PETs, monthly dialysate glucose exposure, or underlying diabetes/non-diabetes. The final peritoneal transport pattern was altered with 5 (15.6%) patients remaining in the extreme subgroups (H or L) and, by contrast, 84.4% (27/32) of the patients now in the averaged (HA or LA) groups (p < 0.01, chi2 test). We demonstrated a natural "centralization" migration of PET results after long-term uneventful CAPD, which may help to explain why patients with extreme PET characteristics, that is, H or L, continued to do well on CAPD.

Depression, pain, and site:

Objective: To assess the level of depression, severity of pain and pain in single/multiple sites in patients with different severity of bruxing behavior and Temporomandibular Disorders (TMDs). Methods: We evaluated 131 patients with bruxism and TMDs: 20 patients with mild bruxism, 42 patients with moderate bruxism, 45 patients with severe bruxism and 24 patients with extreme bruxism. We used the Beck Depression Inventory (BDI), clinical examination, a questionnaire of clinical epidemiological data, criteria for TMDs and bruxism, palpation of muscles and joints, the Visual Analogue Scale for pain, classification of the occlusion and biomechanical tests to assess for internal joint derangements. Results: The level of depression increased from the mild, to the moderate, severe and extreme bruxing behavior groups, but the difference was significant only from the mild to the extreme group (p&lt;0.001). Pain levels increased from the mild and moderate to the severe and extreme subgroups, but were not statistically significant. Mean number of pain sites increased from the mild, to the moderate, severe and extreme subgroup and the difference was extremely significant (p&lt;0.0001). Conclusion: Levels of depression, severity of pain and pain sites increased with severity of bruxing behavior. A higher number of pain sites with more severe bruxism indicates somatization in bruxers, but a further study using the same protocol and a psychological test for somatization would be indicated to further substantiate these findings.

Contrasting Aesthetic Evaluations of “Graffiti” Images as a Function of Incongruity Intolerance Levels

This investigation develops a line of research aimed at examining the influence of incongruity intolerance level on subjects' aesthetic evaluations of relatively harmonious or very conflictual images. Sixty young adults were selected from a larger population and divided into two extreme subgroups: thirty very incongruity intolerant persons and thirty very incongruity tolerant ones. Both genders were equally represented in each category. Selection was based on a specific quick visual procedure, the Building Inclination Test (BIT: Bonaiuto, Giannini, &amp; Bonaiuto, 1987, 1989; Bonaiuto, Biasi, Giannini, &amp; Bartoli, 1996), providing a numerical index of incongruity intolerance, which has also been proved to be positively related to behavioral rigidity and negatively to ambiguity tolerance. Twelve full-color A4 reproductions of American “graffiti” paintings (made from 1981 to 1990 by artists such as Basquiat, Brown, Cutrone, Haring, Scharf, or others) were shown one at a time on a lectern and individually submitted to each subject for evaluating aesthetic and emotional properties using eleven-point scales. Systematic rotation of scales and pictures and double-blind experimental conditions were used. The images were selected corresponding to three categories: a) figurative playful and relaxing representations, b) semiabstract, emotionally quite neutral representations, and c) figurative disquieting, very conflictual representations. An overall progressive decrease of attributed beauty was found moving from the first to the third group of images. This effect was more intense for the very incongruity intolerant observers, who highly preferred images of the first category and deeply disliked those of the third category. On the other hand, the very incongruity tolerant participants recorded on average a less positive aesthetical appreciation score with the first category and a less negative one for the third category (there was a significant interaction between image category and observer's personality, p &lt; 0.002). The aesthetic rejection of the most disquieting and conflictual images especially by the very incongruity intolerant persons is explained by the authors as an effect of the overloading of psychic conflict in this type of persons.

Bruxism as mechanism subserving hysteria

Objective. To explore the hypothesis that bruxism is a mechanism in hysteria by comparing features in hysteria, bruxism, hostility, and local complaints in bruxers. Method. We evaluated 33 patients with mild bruxism, 52 with moderate, 55 with severe, and 42 with extreme bruxism with the Minnesota Multiphasic Personality Index and the Cook-Medley scale for hostility. Results. Scores of hysteria and hostility increased from the mild to the moderate, severe, and extreme bruxism subgroup (p&lt;0.0001). Mean local complaints increased with the severity of bruxism and with scores of hysteria (p&gt;&lt;0.0001). The group that presented higher scores in both hysteria and hostility and greater local complaints as compared to two groups, low hysteria and high hostility, and low hysteria and hostility (p&gt;&lt;0.003). Conclusion. Scores in hysteria e hostility increased with the severity of bruxism, and the number of local complaints increased with scores in hysteria and severe bruxism, suggesting that bruxism may be a hysterical mechanism in temporomandibular disorders/bruxing behavior patients&gt;

Extremal subgroups in twisted Lie type groups

Extremal subgroups in twisted Lie type groups

Extremal Subgroups in Chevalley Groups

Throughout this paper G(k) denotes a Chevalley group of rank n defined over the field k, where n⩾3. Let Φ be the root system associated with G(k) and let Π={α1, α2, …, αn} be a set of fundamental roots of Φ, with Φ+ being the set of positive roots of Φ with respect to Π. For α∈Π and γ∈Φ+, let nα(γ) be the coefficient of α in the expression of γ as a sum of fundamental roots; so γ=∑α∈Πnα(γ)α. Also we recall that ht(γ), the height of γ, is given by ht(γ)=∑α∈Πnα(γ). The highest root in Φ+ will be denoted by ρ. We additionally assume that the Dynkin diagram of G(k) is connected.

Comparison of Multivariate Calibration and Discriminant Analysis in Evaluating NIR Spectroscopy for Determination of Meat Tenderness

Often the primary goal of analytical measurement tasks is not to find good estimates of continuous reference values but rather to determine whether a sample belongs to one of a number of categories or subgroups. In this paper the potential of different statistical techniques in the classification of raw beef samples in tenderness subgroups was studied. The reference values were based on sensory analysis of beef tenderness of 90 samples from bovine M. longissimus dorsi muscles. The sample set was divided into three categories—very tough, intermediate, and very tender—according to degree of tenderness. A training set of samples was used to find the relationship between category and near-infrared (NIR) spectroscopic measurements. The study indicates that classical discriminant analysis has advantages in comparison to multivariate calibration methods [i.e., principal component regression (PCR)], in this application. One reason for this observation seems to be that PCR underestimates high measurement values and overestimates low values. In this way most samples are assigned to the intermediate group of samples, causing a small number of erroneous classifications for the intermediate subgroup, but a large number of errors for the two extreme groups. With the use of PCR the number of correct classifications in the extreme subgroups was as low as 23%, while the use of discriminate analysis increased this number to almost 60%. The number of classifications in correct or neighbor subgroup for the two extreme subgroups was equal to 97%. A “bias-correction” was also attempted for PCR, and this gave results comparable to the best results obtained by discriminant analysis methods. Test sets used NIR analysis of fresh, raw beef samples with different processing. While this spectroscopic approach had previously been shown to be useful with frozen products, it appears unsuitable at this time for fresh beef. However, its marginal analytical utility proved useful in evaluating the two classification approaches employed in this study.

Ranking Dispatching Rules by Data Envelopment Analysis in a Job Shop Environment

This paper uses Data Envelopment Analysis (DEA) to measure multiple performance criteria for 42 dispatching rules in a job shop environment. We introduce a DEA application in production scheduling. Seven performance measures are considered in the evaluation. Without pre-assigning weights to any performance measure, DEA evaluates the efficiency of each dispatching rule relative to the other rules. After running a large number of experiments, the results show that two extreme subgroups of dispatching rules perform consistently. The shortest processing time related rules form the top group, while the longest processing time related rules form the bottom group. The due date or slack-related rules perform well in tardiness. However, they are ranked low if all seven criteria are considered together. The results provide guidance to scheduling practitioners in choosing priority dispatching rules when there are multiple objectives.

Clinical utility of insulin-like growth factor-I (IGF-I) and IGF binding protein-3 levels in the diagnosis of GH deficiency (GHD) during childhood.

Diagnosis of GH deficiency (GHD) has been done traditionally by the combination of auxological data and the results of GH provocation tests. Recently, limitations of GH provocation tests have been advocated. Thus, three extreme subgroups (G-1; normal, G2; severe GHD, G-3; short children with normal GH secretion) were selected in order to show that insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP-3) levels reflect GH secretion. In G-1 (n = 52), all had normal IGF parameters. In G-2 (n = 27), all had low IGF parameters. In G-3 (n = 28), all except for one patient had normal IGF parameters. Taken together with the assumption that GH secretion status is continuous from 0 to normal (or to acromegalic), the data on IGF parameters in the three subgroups indicate that they are functional tests for GH secretion. IGF-I and IGFBP-3, together with free IGF-I and acid-labile subunit, may replace GH provocation tests in the diagnosis of GH deficiency during childhood; these functional tests for GH secretion, which show minimal intradaily variation, are more physiological and cost-effective than GH provocation test.

Ischaemic heart disease, skeletal muscle fibres and exercise capacity.

Twenty-eight male patients with ischaemic heart disease (IHD) performed OBLA (onset of blood lactate accumulation) exercise stress tests and had muscle biopsies taken from their vastus lateralis muscle the day before coronary bypass grafting. All 28 patients showed the same exercise performance pattern as compared to healthy sedentary, age-matched, controls: a low exercise intensity eliciting a blood lactate concentration of 2.0 mmol x l-1 (WOBLA), WOBLA corresponded to a high fraction (% WOBLA) of WSL (symptom limited or 'maximal' capacity), and a low peak blood lactate concentration. The high % WOBLA and low peak blood lactate indicated a reduced glycogenolytic capacity ('anaerobic' performance). Muscle fibre composition disclosed a high mean value of fast twitch (FT), type II or 'white' muscle fibres, as compared to sedentary healthy controls. This indicated that this patient group constituted an extreme subgroup of the age-matched population. The distorted muscle fibre composition in IHD could reflect both heredity as well as adaptation to physical inactivity, degenerative cytosolic properties, etc. Muscle and blood contents of a mitochondrial electron translocator and nonspecific radical scavenger, ubiquinone or coenzyme Q10(CoQ10), were low, which coincided with an elevated frequency of the fibre subgroup FT(c). The presence of the FT(c) fibre type is assumed to reflect histological trauma.

Psychiatric status of adolescents who had extreme temperaments at age 7

Two temperamentally extreme (extremely easy and extremely difficult) subgroups of children were selected at the age of 7 years from a large random sample of the general population of Quebec City. The clinical status, family functioning, IQ, and academic performance of these children were reassessed at 12 and 16 years of age. Findings suggest that extreme temperament at age 7 predicts psychiatric status in preadolescence and adolescence only when family functioning is also taken into account. The adolescents who had been temperamentally difficult children and who were living in families with dysfunctional behavior control displayed more clinical disorders.