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PubMed1987

Impact of intensive venous sampling on characterization of pulsatile GH release.

The effect of sampling intensity on quantitative properties of pulsatile growth hormone (GH) release was tested using an objective, statistically based pulse detection algorithm (Cluster). Seven normal young men had blood withdrawn at 5-min intervals for 24 h. The number of GH peaks/24 h (mean +/- SE) detected in the 5-min series (5.93 +/- 0.66) was significantly greater than the number of peaks documented in the constituent 10-min (3.45 +/- 0.28), 15-min (2.79 +/- 0.31), 20-min (2.86 +/- 0.64), 30-min (2.5 +/- 0.36), 45-min (2.21 +/- 0.21), and 60-min (1.93 +/- 0.23) series. The increased number of peaks detected with 5-min sampling reflected high-frequency pulsatile GH release occurring within the major GH secretory episodes. Both the mean widths and areas associated with peaks identified in the 5-min series were smaller than those documented with less intensive sampling. Peak amplitude did not change with sampling intensity. These data suggest that the major secretory episodes of GH release in normal young men encompass high-frequency GH secretory activity. That these high-frequency GH secretory events have not previously been described probably reflects the relatively infrequent sampling paradigms (e.g., every 20-30 min) commonly used in the past.

Adult↗

PubMed1988

Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man.

Studies in man have shown that the episodic release of growth hormone (GH) is infrequent and erratic, and unlike that in the rat does not appear to have discernible ultradian periodicities. However, these observations in nonfasted subjects may be invalid since mixed nutrients have unpredictable effects on GH release. Moreover, in the fed state basal GH levels are frequently undetectable, thus rendering the identification of low amplitude pulses unreliable. Accordingly, the 24-h pulsatile pattern of GH secretion obtained from repetitive venous sampling in six normal adult male subjects was examined during a control fed day and during the first and fifth days of a 5-d fast. The GH data were analyzed using two distinct methods: a discrete pulse detection algorithm (Cluster analysis) and Fourier expansion time-series, which allows fixed periodicities of secretory activity to be resolved. The 5-d fast resulted in a significant increase in discrete GH pulse frequency (5.8 +/- 0.7 vs. 9.9 +/- 0.7 pulses/24 h, P = 0.028), 24 h integrated GH concentration (2.82 +/- 0.50 vs. 8.75 +/- 0.82 micrograms.min/ml; P = 0.0002), and maximal pulse amplitude (5.9 +/- 1.1 vs. 12.3 +/- 1.6 ng/ml, P less than 0.005). While multiple low-amplitude sinusoidal periodicities were present on the control fed day, time-series analysis revealed enhancement of circadian and ultradian cycles on the first and fifth days of fasting. Concomitantly, fasting resulted in a decline (day 1 vs. day 5) in serum concentrations of somatomedin C (1.31 +/- 0.22 vs. 0.77 +/- 0.18 U/ml) and glucose (4.9 +/- 0.2 vs. 3.2 +/- 0.2 mmol/liter), and a marked rise in free fatty acid (0.43 +/- 0.12 vs. 1.55 +/- 0.35 mmol/liter) and acetoacetate (35 +/- 6 vs. 507 +/- 80 nmol/liter). We conclude that the acute nutritional status is an important determinant of spontaneous pulsatile GH secretion in man. Fast-induced enhancement of GH release is achieved through combined frequency (discrete pulses) and amplitude (sinusoidal periodicities) modulation. Such alterations in somatotropic hormone release may play an important role in substrate homeostasis during starvation.

Acetoacetates↗

PubMed1977

Automated classification of cells in electron microscopic images of lymphoreticular tissue.

In classifying cells in tissue sections, one must consider the fact that only random projections of cells and of subcellular structures are available in the two-dimensional image. Therefore, measurement values that solely reflect the size of such projections cannot be taken on their own as a basis for cell classification. More complex morphologic features such as shape, texture and distribution pattern of cells and their components should be analyzed. Using cell nuclei as an example, the relationship between such features and geometric measurement values is evaluated. It can be shown that a well balanced combination of geometric parameters provides a suitable basis for reproducing the visual preclassification of lymphocytes in tissue sections. Moreover, using a cluster algorithm, which allows different levels of similarity to be defined, a hierarchical sequence of subclusters turns out, indicating the heterogeneity of the visually determined cell classes. Whether or not these subclusters can be correlated to functionally defined subpopulations of lymphocytes remains a matter for further investigation.

Autoanalysis↗

PubMed1990

Variations of pulsatile growth hormone release in healthy short prepubertal boys.

Overnight growth hormone (GH) concentrations obtained by frequent venous sampling of 20 healthy, short prepubertal boys were evaluated using the objective pulse detection algorithm, CLUSTER. The resulting pulsatile characteristics were compared with those of 11 healthy prepubertal boys of normal stature and with those of nine prepubertal children with documented GH deficiency. Although no significant differences of pulsatile GH release were found between the normal and short subjects, a subset of the short prepubertal boys with significantly delayed skeletal ages had subnormal sum of GH pulse areas and sum of GH pulse amplitudes. The finding of a significant correlation in all subjects between growth velocity and the sum of GH pulse amplitudes is important, as the results are compatible with the hypothesis that alterations of amplitude-modulated GH release underlie the pathophysiology of suboptimal growth in some short prepubertal children.

Adolescent↗

PubMed1989

Fasting alters pulsatile and rhythmic cortisol release in normal man.

The effect of a 5-day fast on integrated, pulsatile, and periodic cortisol release was studied in 10 normal men by measuring serum cortisol concentrations every 20 min for 24 h before (day 0) and during the fifth day of fasting (day 5). Serum concentration profiles were analyzed for integrated cortisol release (area under the curve), pulsatile hormone release by an objective, statistically based pulse detection algorithm (cluster analysis), and periodic hormone release (circadian and ultradian rhythms) by Fourier expansion time series analysis. Urinary cortisol excretion per 24 h was measured in 5 men. The mean 24-h integrated serum cortisol concentration increased 1.7-fold during fasting (P = 0.0006). This increase resulted from a 2-fold increase in the serum cortisol concentrations between pulses (valley mean; P = 0.0004), an increase in the pulse height (P = 0.001), and an increase in pulse increment above baseline (P = 0.01). There were no changes in the number of pulses per 24 h, the interval between pulses, the width of the pulses, or the area of the pulses during fasting. Twenty-four-hour urinary cortisol excretion increased in all men, and the mean urinary cortisol (nanomoles per L)/creatinine clearance (milliliters per s) ratio increased from 119 on day 0 to 187 on day 5 (n = 5; P = 0.05). The pattern of periodic hormone release also changed during fasting; the mean (+/- SE) circadian rhythm (24-h) amplitude decreased from 160 +/- 14 nmol/L on day 0 to 102 +/- 105 nmol/L on day 5 (P = 0.06), and the amplitude of the 12-h rhythm increased from 68 +/- 11 to 99 +/- 11 nmol/L. There also were significant increases in the amplitudes of rhythms with periodicities of 8.1, 4.1, 2.4, 1.6, and 1.3 h (P = 0.02-0.008). Fasting in normal men results in distinct changes in the amount and pattern of pulsatile, circadian, and ultradian cortisol release.

Adult↗

PubMed1989

Alterations in the pulsatile mode of growth hormone release in men and women with insulin-dependent diabetes mellitus.

The mechanisms responsible for the elevated levels of circulating GH observed in diabetes mellitus (DM) remain incompletely defined. To assess the episodic fluctuations in serum GH as a reflection of hypothalamic-pituitary activity, we accumulated GH concentration-time series in a total of 48 adult men and women with and without insulin-dependent DM by obtaining serum samples at 10-min intervals over 24 h. Significant pulses of GH release were subsequently identified and characterized by an objective, statistically based pulse detection algorithm (Cluster) and fixed circadian (24-h) periodicities of secretory activity, resolved using Fourier expansion time-series analysis. Compared to those in age-matched controls, integrated 24-h concentrations of GH were 2- to 3.5-fold higher in diabetic men (P = 0.002) and women (P = 0.0005). Both men and women with DM had over 50% more GH pulses per 24 h than their non-DM counterparts. In addition, maximal GH pulse amplitude was markedly elevated in the men and women with DM (P = 0.0019 and 0.0189, respectively). That the increase in maximal pulse amplitude was accounted for by greater baseline levels was documented by a higher interpulse valley mean GH concentration in the diabetics compared to the controls (P = 0.0437 and 0.0056, men and women, respectively) and the absence of any difference in incremental pulse amplitude for either sex (P greater than 0.05). DM men had larger GH pulse areas (P = 0.039) than control men, apparently accounted for by greater pulse width (P = 0.0037). Pulse areas in DM and non-DM women were indistinguishable. Time-series analysis revealed that the 24-h (circadian) rhythms of serum GH concentrations exhibited significantly increased amplitudes in the diabetic group as a whole (compared to the controls, P = 0.011). However, the times of maximal GH concentrations (acrophases) were not significantly different. As a group, serum insulin-like growth factor-I was lower in DM vs. non-DM individuals (P = 0.0014), although when separated by sex this difference did not reach statistical significance in women (P = 0.317). The present data confirm the higher circulating levels of GH previously reported to occur in individuals with poorly controlled DM. The altered frequency of GH pulses together with enhanced interpulse GH concentrations and an amplified circadian GH rhythm are compatible with hypothalamic dysfunction associated with dysregulation of somatostatin and/or GHRH secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1989

Specific, time-dependent actions of low-dose ethinyl estradiol administration on the episodic release of growth hormone, follicle-stimulating hormone, and luteinizing hormone in prepubertal girls with Turner's syndrome.

To investigate the actions of acute and chronic low doses of ethinyl estradiol (EE) on the pulsatile characteristics of GH and gonadotropin release we studied seven girls with Turner's syndrome [mean age, 7.5 +/- 0.75 (+/- SE) yr] on 3 separate study days. At baseline (study I), blood was drawn every 20 min from 2000-0800 h for GH, LH, and FSH determinations. One month after study I the patients were started on 100 ng/kg EE, orally, daily, and an identical study was repeated 1 week (study II) and 5 weeks (study III) from the initiation of low dose EE therapy. A pulse detection algorithm, Cluster, was used to objectively analyze pulsatility profiles. There were consistent and significant increases in all seven patients after 5 weeks of low dose EE therapy in mean GH concentrations (study I, 7.0 +/- 1.1 micrograms/L; study III, 13.4 +/- 1.7; P = 0.008), mean area under the GH pulse (study I, 602 +/- 52 micrograms/L.min; study III, 1350 +/- 261; P = 0.026), and mean GH pulse amplitude (study I, 14.0 +/- 2.2 micrograms/L; study III, 32.8 +/- 6.0; P = 0.018); with no detectable changes in GH pulse frequency (study I, 5.3 +/- 0.6 pulses/12 h; study III, 5.3 +/- 0.4). These findings were not accompanied by any significant changes in plasma somatomedin-C or serum estradiol concentrations or urinary cytological maturation indexes. Conversely, the amount of radioimmunoassayable FSH activity was suppressed after low dose EE therapy, with a decrease in mean FSH concentrations (study I, 23.5 +/- 6.6 IU/L; study III, 5.9 +/- 1.2; P = 0.035) and mean pulse amplitude (study I, 28.6 +/- 8.6 IU/L; study III, 8.2 +/- 1.8; P = 0.038), with no detectable changes in FSH pulse frequency (study I, 7.6 +/- 0.6 pulses/12 h; study III, 7.3 +/- 0.6). Similar qualitative changes in LH pulsatility were observed after low dose estradiol administration. In conclusion, our results demonstrate that low dose EE therapy results in a significant augmentation of pulsatile GH activity, with reciprocal decreases in gonadotropin concentrations in girls with Turner's syndrome. Such observations indicate an exquisite sensitivity of gonadotrope and somatotrope function to low dose estrogen action in this prepubertal hypogonadal model.

Adolescent↗

PubMed1990

Basal plasma growth hormone levels in man: new evidence for rhythmicity of growth hormone secretion.

Circulating GH levels in man fluctuate widely due to pulsatile GH secretion by the pituitary gland. During much of the time, plasma GH is undetectable by current assays. This is punctuated by occasional secretory episodes, resulting in plasma GH peaks of varying height. The principal diurnal secretory event for GH is that associated with early slow wave sleep, but little is known about the prevailing level and dynamics of GH during the day. We used a new ultrasensitive immunoradiometric assay for GH (Boots-Celltech IRMA; limit of detection, 20 ng/L) to measure plasma GH in the previously undetectable range and to assess its diurnal pattern. Plasma GH was measured every 20 min over a 24-h period in 12 normal subjects (6 men and 6 women, aged 20-47 yr) under physiological conditions. Time series analysis of plasma GH patterns was performed by the Cluster algorithm, autocorrelation, and spectral analysis. Plasma GH, as measured by IRMA, was detectable at all time points and ranged from 40-19,695 ng/L. Dynamic fluctuations occurred within and above the previously undetectable range, with amplitudes varying over 3 orders of magnitude. Women had significantly higher overall GH levels, higher peak amplitudes, and higher valley levels/nadirs than men. GH pulses occurred with an average frequency of about 13/day in both sexes, with a dominant, but not strictly periodic, 2-h rhythmicity. We conclude that in man pulsatile GH secretion occurs throughout the day, and that it is oscillatory rather than episodic. This neurosecretory pattern has eluded recognition heretofore because of the lack of assay sensitivity. Women of reproductive age have higher pulse amplitudes and a higher baseline but equal pulse frequency compared to men. Previous estimates of integrated GH concentrations and GH production rates were too high by a factor of 2 due to overestimation of GH levels in the undetectable range.

Adult↗

PubMed1990

Intensive venous sampling paradigms disclose high frequency adrenocorticotropin release episodes in normal men.

Recent studies in the rat and rhesus monkey have disclosed apparently high frequency in vivo ACTH release episodes. While the circadian pattern of plasma ACTH concentrations has been known for many years, the exact frequency of ultradian pulsatile ACTH release in man is not clear, due in part to variable intensities of blood-sampling schedules and the limited availability of sensitive ACTH assays. In this study we used a new sensitive and specific immunoradiometric assay to measure plasma ACTH concentrations in blood sampled at 1) 2-min intervals for 3 h, followed by 4-min intervals for 4 more h in six men; and 2) 10-min intervals for 24 h in eight other men. An objective peak detection algorithm (Cluster) and cosinor analyses were used to assess the episodic pulsatility and circadian rhythmicity of ACTH. Comparisons were made among the 2 min (3 h), 4, 8, and 12 min (7 h), and 10 min (24 h) time series. Mean ACTH interpulse intervals were significantly different among the five sampling groups (P less than 0.00001). Sampling every 2 min yielded a mean ACTH interpulse interval of 18 min, which was significantly shorter than the mean interpulse intervals of 35, 53, 52, and 73 min resulting, respectively, from sampling every 4, 8, 10, and 12 min (P less than 0.05). In contrast, maximal peak ACTH amplitudes (picomoles per L or percent increase) did not vary as a function of sampling frequency. The 24-h plasma ACTH concentration time series showed significant diurnal variation, with a mean circadian amplitude of 0.95 +/- 0.15 pmol/L occurring at 1008 h (+/- 25 min). Cosinor analysis of various ACTH pulse parameters deduced from the 24-h time series revealed significant circadian rhythmicity in the ACTH peak maxima (P less than 0.05), peak increments (P less than 0.05), and prepeak nadir (P less than 0.05) concentrations, but not in ACTH interpulse intervals. We conclude that in men, 1) intensive sampling at 2-min intervals unmasks high frequency ACTH release episodes that cannot be detected at conventional sampling rates; and 2) ACTH peak amplitude, but not frequency, varies significantly during the course of circadian changes in the plasma ACTH concentrations.

Adrenocorticotropic Hormone↗

PubMed1992

Spontaneous and stimulated growth hormone release in adolescents with type I diabetes mellitus: effects of metabolic control.

Abnormalities in GH release have been found in adults with poorly controlled type I diabetes mellitus. During puberty, circulating GH concentrations transiently increase. To investigate in pubertal diabetic adolescents, the physiological relationship between metabolic control and GH release, we compared spontaneous and GH-releasing hormone (GHRH)-stimulated GH release in six pubertal subjects during poor (study A) and improved (study B) metabolic control. The subjects included two females and four males (mean age +/- SE, 15.5 +/- 1 yr; duration of diabetes, 8.6 +/- 0.9 yr; Tanner stages II-V). Serum samples for glucose and GH determinations were obtained at 20-min intervals over a 24-h period. Significant pulses of GH release were identified using a pulse detection algorithm (Cluster). Fourier expansion time series was used to document the occurrence of significant periodicities in the GH concentration-time data series. All subjects received 1.0 microgram/kg GHRH-44, iv, at 0800 h on the day after the 24-h monitoring for GH. After GHRH administration, samples were taken for glucose and GH determinations over 90 min. The overall mean glucose level (+/- SE) during the 24-h monitoring was 11.5 +/- 0.2 mmol/L during study A and 7.2 +/- 0.2 during study B (P = 0.0001). During the 4 weeks of improved control, glycated hemoglobin fell from 13.9 +/- 1.4% to 11.7 +/- 0.8% (mean +/- SE; P < 0.025). All subjects had significant pulses of GH release during poor or improved metabolic control. Relative to that at night, the daytime pulse frequency was higher in study A (P < 0.025). The overnight pulse frequency increased during study B (P < 0.01). Other pulse parameters, including maximal and incremental pulse amplitudes, pulse width, and interpulse valley mean, did not change during improved control. The mean +/- SE 24-h GH concentration was 4.1 +/- 0.7 micrograms/L during study A and 4.3 +/- 0.8 during study B. The amplitude of the circadian GH rhythm was not different by Fourier analysis. The overall mean glucose +/- SE after GHRH administration was 15.3 +/- 0.2 mmol/L in study A and 6.8 +/- 0.1 in study B. In spite of the marked hyperglycemia during study A, the GH responses were similar during studies A and B. Maximal GH levels were obtained at 15-30 min (mean +/- SE) and were 36.0 +/- 16.9 micrograms/L in study A and 38.7 +/- 18.9 in study B.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1992

Immunoradiometric analysis of circulating human glycosylated and nonglycosylated prolactin forms: spontaneous and stimulated secretions.

The monoclonal antibodies (MAbs) obtained in mice immunized with human PRL coupled to an anti-PRL MAb were screened for their ability to distinguish the glycosylated (G-) and nonglycosylated (NG-) forms of PRL. The 431-29 MAb exhibited high affinity binding for NG-PRL but little or no cross-reactivity to G-PRL. Using this antibody in conjunction with other MAbs which equally recognized both forms, we developed 2 immunoradiometric assays which were used to determine the amount of G- and NG-PRL in plasma. In 85 normal subjects, NG-PRL baseline levels averaged 6.6 +/- 3 micrograms/L, and represented 76 +/- 8% of the total PRL immunoreactivity. In 74 pregnant women, this proportion was significantly higher during the last 2 trimesters (84 +/- 4% and 85 +/- 6%), as compared to the first trimester (76 +/- 7%). In 6 healthy volunteers studied over 24 h, 79% of the NG-PRL peaks detected using the cluster algorithm occurred concomitantly to a G-PRL peak. The mean NG-PRL/PRL ratio was significantly higher during NG-PRL pulses (81 +/- 9%) than during valleys (71 +/- 12%). Similarly, this ratio was significantly increased during TRH or metoclopramide stimulated PRL secretion (to 88 +/- 7% and 86 +/- 6%, respectively). We conclude that 1) NG-PRL is the predominant immunoassayable form of PRL in plasma; 2) both G- and NG-PRL are cosecreted but NG-PRL is the main PRL form released during spontaneous or pharmacologically induced PRL secretion.

Adult↗

PubMed2025

Genetically distinct within-host subpopulations of hepatitis C virus persist after Direct-Acting Antiviral treatment failure.

Analysis of viral genetic data has previously revealed distinct within-host population structures in both untreated and interferon-treated chronic hepatitis C virus (HCV) infections. While multiple subpopulations persisted during the infection, each subpopulation was observed only intermittently. However, it was unknown whether similar patterns were also present after Direct-Acting Antiviral (DAA) treatment, where viral populations were often assumed to go through narrow bottlenecks. Here we tested for the maintenance of population structure after DAA treatment failure, and whether there were different evolutionary rates along distinct lineages where they were observed. We analysed whole-genome next-generation sequencing data generated from a randomised study using DAAs (the BOSON study). We focused on samples collected from patients (N=84) who did not achieve sustained virological response (i.e., treatment failure) and had sequenced virus from multiple timepoints. Given the short-read nature of the data, we used a number of methods to identify distinct within-host lineages including tracking concordance in intra-host nucleotide variant (iSNV) frequencies, applying sequenced-based and tree-based clustering algorithms to sliding windows along the genome, and haplotype reconstruction. Distinct viral subpopulations were maintained among a high proportion of individuals post DAA treatment failure. Using maximum likelihood modelling and model comparison, we found an overdispersion of viral evolutionary rates among individuals, and significant differences in evolutionary rates between lineages within individuals. These results suggest the virus is compartmentalised within individuals, with the varying evolutionary rates due to different viral replication rates and/or different selection pressures. We endorse lineage awareness in future analyses of HCV evolution and infections to avoid conflating patterns from distinct lineages, and to recognise the likely existence of unsampled subpopulations.

Humans↗

PubMed2026

Machine Learning-Based Preoperative Predicting TERT Promoter Mutation and EGFR Gene Amplification Phenotype in IDH Wild-Type Glioblastoma Using Advanced MR Habitat Imaging.

BACKGROUND AND PURPOSE: The telomerase reverse transcriptase (TERT) gene promoter mutation is a crucial factor for identifying an isocitrate dehydrogenase (IDH) wild-type glioblastoma with poor prognosis, and the epidermal growth factor receptor (EGFR) amplification may be a potential prognostic factor. The purpose of this study was to investigate the value of the tumor habitats imaging model on advanced MRI in predicting TERT promoter mutation and EGFR gene amplification phenotype of IDH wild-type glioblastoma. MATERIALS AND METHODS: One hundred seventy-nine patients with pretreatment conventional MRI, DWI, and DSC-PWI were included. The data were divided into the training set (n=112), test set (n=29), and time-independent validation set (n=38). Based on the ADC and CBV map, the solid tumor area was split into several habitat subregions using the k-means clustering algorithm (hypovascular hypercellular area, hypervascular area, and hypovascular hypocellular area). In the training set, TERT promoter mutation and EGFR gene amplification phenotype prediction models were constructed using the random forest method. The reliability of prediction models was validated in the test and the time-independent validation sets. Receiver operating characteristic (ROC) curve analysis, calibration curve, and decision curve analysis (DCA) were used. RESULTS: The area under the curve (AUC) of the training, test, and validation sets of the TERT promoter prediction model was 0.877, 0.783, and 0.796, respectively. The accuracy of the TERT promoter prediction model was 82.1%, 75.9%, and 76.3%, respectively. The AUCs of the 3 sets for the EGFR gene amplification status prediction model were 0.877, 0.784, and 0.878, respectively. The accuracy of the EGFR gene amplification status prediction model was 79.5%, 75.9%, and 89.5%, respectively. Moreover, the prediction probability of these models was in good agreement with the actual result. CONCLUSIONS: The tumor habitat imaging model based on advanced MRI was useful for accurately predicting TERT promoter mutation and EGFR amplification status in IDH wild-type glioblastoma.

Humans↗

PubMed1975

A flow-system multiangle light-scattering instrument for cell characterization.

A flow-system cell-analysis instrument is described in which cells from a heterogeneous population are characterized by their light-scatter patterns alone. As the cells pass at high speed through a focused helium/neon laser beam, the scatter pattern from each cell is sampled simultaneously at up to 32 angles between 0 degrees and 30 degrees with respect to the laser beam axis, and the scatter pattern for each cell is transferred to a computer. A mathematical clustering algorithm is used to determine the number of classes into which the cells can be divided, and a linear separation algorithm is used to find the boundaries between the classes. Preliminary results on exfoliated cells from gynecological specimens are presented. This technique may be useful for automated prescreening of gynecological specimens.

Autoanalysis↗

PubMed1992

Emotion differentiation. A correlate of symptom severity in major depression.

The relationship of emotion differentiation to symptom severity in depression was investigated. The subjects were 25 patients diagnosed with unipolar major depression. Subjects were clinically assessed using the Schedule for Affective Disorders and Schizophrenia and the Hamilton rating scales for anxiety and depression. In addition, subjects completed a number of self-report measures of symptoms and attitudes. Twelve basic emotion terms were incorporated into free-response attribute lists which subjects used to rate aspects of themselves and of other significant people in their lives. A clustering algorithm (HICLAS) was used to derive a social perception structure from this data for each subject. The differentiation of negative emotion within an individual's structure (NES) was measured by dividing the number of attribute categories containing negative emotions by the total number of categories in that person's structure. The results indicated that NES is a significant correlate of depressive symptomatology independent of self-esteem and other variables. Relatively undifferentiated emotion structure (low NES) was associated with significantly higher levels of depressive symptomatology.

Adult↗

PubMed1991

Multivariate procedures to describe clinical staging of melanoma.

Analyzing multivariate clinical data to identify subclasses of patients being treated for a specific disease may improve patient management and increase understanding of the behavior of disease under clinical conditions. In some cases, patients have been classified on prognostic characteristics using standard risk assessment procedures (e.g., Cox' regression). This requires long term follow-up, differentiates patients only on attributes relevant to survival, and assumes that patients are sampled from a common population. Other approaches involve the use of clustering algorithms to classify patients into categories based on multiple clinical attributes. We illustrate the use of a multivariate statistical procedure to directly characterize patients on multiple clinical characteristics. The procedure is designed to analyze discrete response data with parameters representing individual differences within groups. Its use is illustrated for patients with Stage I melanoma in determining how age is related to treatment response in different patient groups.

Adult↗

PubMed1990

From biopsy to automatic diagnosis.

High resolution two-dimensional gel electrophoresis is a very powerful biochemical tool for analysis of complex protein mixtures. In well defined situations, protein maps, obtained from tissue biopsies or biological fluids by this technique, can be automatically analyzed by computer. Some polypeptide patterns are the fingerprints of diseases. Applying clustering algorithm and learning techniques, the prototype expert system MELANIE recognized patterns and associated the correct diagnosis to the specific pattern.

Diagnosis, Computer-Assisted↗

PubMedDate not supplied

[Phylogenetic analysis of partial nucleotide sequences of 18S rRNA for 14 plant species].

The variable 260 base long region from the interior of 18S rRNA of 14 plant species was determined by chain termination method with the use of reverse transcriptase. The hairpin revealed in this region appeared to be conservative in all species compared. Thermodynamic stability of such hairpin is lower than of an alternative structure with different base pairing mode. From sequence data dendrograms were produced by clustering algorithms and by the compatibility method. In addition to the plant sequences these dendrograms included also the homologous regions from yeast and Xenopus 18S rRNAs. The compatibility method seems to be more reliable. Inferences were drawn on relations between gymnosperms and angiosperms, monocots and dicots on the bases of the analysis of this tree.

Base Sequence↗