The Often-Overlooked Power of Summary Statistics in Exploratory Data Analysis: Comparison of Pattern Recognition Entropy (PRE) to Other Summary Statistics and Introduction of Divided Spectrum-PRE (DS-PRE)

Unsupervised exploratory data analysis (EDA) is often the first step in understanding complex data sets. While summary statistics are among the most efficient and convenient tools for exploring and describing sets of data, they are often overlooked in EDA. In this paper, we show multiple case studies that compare the performance, including clustering, of a series of summary statistics in EDA. The summary statistics considered here are pattern recognition entropy (PRE), the mean, standard deviation (STD), 1-norm, range, sum of squares (SSQ), and X⁴, which are compared with principal component analysis (PCA), multivariate curve resolution (MCR), and/or cluster analysis. PRE and the other summary statistics are direct methods for analyzing data-they are not factor-based approaches. To quantify the performance of summary statistics, we use the concept of the "critical pair," which is employed in chromatography. The data analyzed here come from different analytical methods. Hyperspectral images, including one of a biological material, are also analyzed. In general, PRE outperforms the other summary statistics, especially in image analysis, although a suite of summary statistics is useful in exploring complex data sets. While PRE results were generally comparable to those from PCA and MCR, PRE is easier to apply. For example, there is no need to determine the number of factors that describe a data set. Finally, we introduce the concept of divided spectrum-PRE (DS-PRE) as a new EDA method. DS-PRE increases the discrimination power of PRE. We also show that DS-PRE can be used to provide the inputs for the k-nearest neighbor (kNN) algorithm. We recommend PRE and DS-PRE as rapid new tools for unsupervised EDA.

Laminin alpha2 muscular dystrophy: genotype/phenotype studies of 22 patients

OBJECTIVE

To determine the number of primary laminin alpha2 gene mutations and to conduct genotype/phenotype correlation in a cohort of laminin alpha2-deficient congenital muscular dystrophy patients.

BACKGROUND

Congenital muscular dystrophies (CMD) are a heterogeneous group of muscle disorders characterized by early onset muscular dystrophy and a variable involvement of the CNS. Laminin alpha2 deficiency has been reported in about 40 to 50% of cases of the occidental, classic type of CMD. Laminin alpha2 is a muscle specific isoform of laminin localized to the basal lamina of muscle fibers, where it is thought to interact with myofiber membrane receptor, such as integrins, and possibly dystrophin-associated glycoproteins.

METHODS

Seventy-five CMD patients were tested for laminin alpha2 expression by immunofluorescence and immunoblot. The entire 10 kb laminin alpha2 coding sequence of 22 completely laminin alpha2-deficient patients was screened for causative mutations by reverse transcription (RT)-PCR/single strand conformational polymorphisms (SSCP) analysis and protein truncation test (PTT) analysis followed by automatic sequencing of patient cDNA. Clinical data from the laminin alpha2-deficient patients were collected.

RESULTS

Thirty laminin alpha2-negative patients were identified (40% of CMD patients tested) and 22 of them were screened for laminin alpha2 mutations. Clinical features of laminin alpha2-deficient patients were similar, with severe floppiness at birth, delay in achievement of motor milestones, and MRI findings of white matter changes with normal intelligence. Loss-of-function mutations were identified in 95% (21/22) of the patients studied. SSCP analysis detected laminin alpha2 gene mutations in about 50% of the mutant chromosomes; PTT successfully identified 75% of the mutations. A two base pair deletion mutation at position 2,096-2,097 bp was present in 23% of the patients analyzed.

CONCLUSIONS

Our data suggest that the large majority of laminin alpha2-deficient patients show laminin alpha2 gene mutations.

Congenital muscular dystrophy with primary laminin alpha2 (merosin) deficiency presenting as inflammatory myopathy

Ten laminin alpha2-deficient patients were identified by both immunofluorescence and immunoblotting (30% of congenital muscular dystrophy patients tested). Three of the laminin alpha2-deficient patients were carrying a diagnosis of infantile polymyositis prior to immunostaining studies. The clinical features in the 10 merosin-deficient patients were homogeneous, with severe floppiness at birth, delay in achievement of motor milestones, and magnetic resonance imaging findings of white matter changes with normal intelligence. The 10-kb laminin alpha2-coding sequence was screened for causative mutations by reverse transcriptase-polymerase chain reaction/single-stranded conformational polymorphism analysis in muscle biopsy specimens from 5 patients, followed by automatic sequencing of aberrant conformers. Clear loss-of-function deletion mutations were identified in both alleles of 1 patient. Muscle histopathology in this patient showed a striking inflammatory infiltrate of T cells and B cells. Reexamination of biopsy specimens from other laminin alpha2-deficient patients showed minor signs of inflammation in each. Based on these findings and the histological and clinical picture suggesting failure of muscle regeneration, a pathogenesis model for this major subset of congenital muscular dystrophy is proposed. Our data show that muscle histopathology showing a neonatal inflammatory process should be considered consistent with congenital muscular dystrophy.

Addictive behavior of older adults

Very little is known about addictive alcohol use by older people. In the present paper personal effects reasons for drinking (i.e. drinking for the effects of alcohol) and concerns about drinking were used as indicators of addictive drinking behavior among a sample of 826 people aged 65 and older who participated in survey interviews in their homes. The relationship of addictive drinking behavior to frequency of drinking, quantity of drinks per occasion, and depressant drug use was examined. Alcohol use was higher among males and young-old (aged 65-74), while depressant medication use was higher among females and old-old (aged 75+). However, with the exception of use of over-the-counter medications containing codeine (which was significantly higher among current drinkers), no relationship existed between alcohol use and use of depressant medications. Personal effects reasons for drinking and concerns about drinking were related both to alcohol and depressant medication use. Frequency of drinking was associated with higher endorsement of both personal effects and social reasons, whereas volume of alcohol consumption (drinks per drinking day) was associated only with personal effects drinking. In addition, use of depressant medications by drinkers was significantly related to consuming alcohol for personal effects reasons (but unrelated to consuming for social reasons) and with having concerns about one's own drinking. These results suggest that even within the generally low levels of alcohol consumption of older people, addictive-use patterns emerge. In addition, the results confirm the importance of including depressant medication use in evaluating the drinking behavior of older people.

Alcohol education in schools: toward a lifestyle risk-reduction approach

This article calls for a refocusing of alcohol education to facilitate the adoption of low-risk lifestyle choices regarding decisions about abstinence and quantity and frequency of alcohol use. Five goals are presented as a focal point for lifestyle risk-reduction education about alcohol. It is essential that research and education activities become more focused on the link between the quantity-frequency of alcohol use and alcohol-related problems, and on the information and attitudes that support low-risk versus high-risk A/Q/F choices.