Haikady N. Nagaraja

A first course in order statistics

Basic Distribution Theory Discrete Order Statistics Order Statistics from Some Specific Distributions Moment Relations, Bounds, and Approximations Characterizations Using Order Statistics Order Statistics in Statistical Inference Asymptotic Theory Record Values Bibliography Indexes.

Myoblast Transfer in the Treatment of Duchenne's Muscular Dystrophy

BACKGROUND Myoblast transfer has been proposed as a technique to replace dystrophin, the skeletal-muscle protein that is deficient in Duchennes muscular dystrophy. Donor myoblasts injected into muscles of affected patients can fuse with host muscle fibers, thus contributing their nuclei, which are potentially capable of replacing deficient gene products. Previous controlled trials involving a single transfer of myoblasts have been unsuccessful. METHODS We injected donor muscle cells once a month for six months to the biceps brachii muscles of one arm of each of 12 boys with Duchennes muscular dystrophy. The opposite arms served as sham-injected controls. In each procedure 110 million cells donated by fathers or brothers were transferred. The patients were randomly assigned to receive either cyclosporine or placebo. Strength was measured by quantitative isometric muscle testing. Six months after the final myoblast transfer, the presence of dystrophin was assessed with the use of peptide antibodies specific to the deleted exons of the dystrophin gene. RESULTS There was no significant difference in muscle strength between arms injected with myoblasts and sham-injected arms. In one patient, 10.3 percent of muscle fibers expressed donor-derived dystrophin after myoblast transfer. Three other patients also had a low level of donor dystrophin (< 1 percent); eight had none. CONCLUSIONS Myoblasts transferred once a month for six months failed to improve strength in patients with Duchennes muscular dystrophy. The value of exon-specific peptide antibodies in the interpretation of myoblast-transfer results was demonstrated in a patient with Duchennes muscular dystrophy who had a high percentage of donor-derived dystrophin. Specific variables affecting the efficiency of myoblast transfer need to be identified in order to improve upon this technique.

Gene copy-number variation and associated polymorphisms of complement component C4 in human systemic lupus erythematosus (SLE): low copy number is a risk factor for and high copy number is a protective factor against SLE susceptibility in European Americans.

Interindividual gene copy-number variation (CNV) of complement component C4 and its associated polymorphisms in gene size (long and short) and protein isotypes (C4A and C4B) probably lead to different susceptibilities to autoimmune disease. We investigated the C4 gene CNV in 1,241 European Americans, including patients with systemic lupus erythematosus (SLE), their first-degree relatives, and unrelated healthy subjects, by definitive genotyping and phenotyping techniques. The gene copy number (GCN) varied from 2 to 6 for total C4, from 0 to 5 for C4A, and from 0 to 4 for C4B. Four copies of total C4, two copies of C4A, and two copies of C4B were the most common GCN counts, but each constituted only between one-half and three-quarters of the study populations. Long C4 genes were strongly correlated with C4A (R=0.695; P<.0001). Short C4 genes were correlated with C4B (R=0.437; P<.0001). In comparison with healthy subjects, patients with SLE clearly had the GCN of total C4 and C4A shifting to the lower side. The risk of SLE disease susceptibility significantly increased among subjects with only two copies of total C4 (patients 9.3%; unrelated controls 1.5%; odds ratio [OR] = 6.514; P=.00002) but decreased in those with > or =5 copies of C4 (patients 5.79%; controls 12%; OR=0.466; P=.016). Both zero copies (OR=5.267; P=.001) and one copy (OR=1.613; P=.022) of C4A were risk factors for SLE, whereas > or =3 copies of C4A appeared to be protective (OR=0.574; P=.012). Family-based association tests suggested that a specific haplotype with a single short C4B in tight linkage disequilibrium with the -308A allele of TNFA was more likely to be transmitted to patients with SLE. This work demonstrates how gene CNV and its related polymorphisms are associated with the susceptibility to a human complex disease.

Painful sensory neuropathy Prospective evaluation using skin biopsy

Objective: In patients presenting with painful, burning feet with minimal signs of neuropathy, the following questions were addressed: 1) How many of these patients have a peripheral neuropathy? 2) What is the role of skin biopsy in establishing a diagnosis of neuropathy? 3) What conditions are associated with the neuropathy? and 4) What laboratory studies are useful in this patient population? Methods: A total of 117 consecutive patients referred for evaluation were prospectively studied. All underwent nerve conduction studies (NCS) and a battery of blood tests, including antinerve antibodies. If NCS were normal, a punch biopsy of the skin of the distal leg was performed to ascertain the intraepidermal nerve fiber (IENF) density. In a subset of 32 patients, the sensitivity of skin biopsy was compared to quantitative sudomotor axon test (QSART) and quantitative sensory tests (QST). Results: Three groups emerged. Group 1, with abnormal NCS (n = 60, 34 F/26 M, mean age 60 ± 14 years), represented 51% of the cohort. The majority had neuropathies of undetermined cause, but 18 (30%) had associated conditions. Group 2, with normal NCS and reduced IENF density (n = 44, 29 F/15 M, mean age 57 ± 14 years), represented 38% of the cohort. Three in this group had associated conditions. Group 3, with normal NCS and IENF density (n = 13, 6 F/7 M, mean age 53 ± 13 years), represented 11% of the cohort; most had no diagnoses but two had MS. In a comparative subset analysis, skin biopsy was more sensitive than QSART or QST in diagnosing a neuropathy. Conclusions: Patients presenting with painful feet are heterogeneous, consisting of both large and small fiber sensory neuropathies. In rare cases, a central cause for pain can be found. Over one-third of patients required a skin biopsy to diagnose a small fiber sensory neuropathy. A limited battery of blood tests facilitated diagnosis, but serum antinerve antibodies were not helpful.

Increased Susceptibility to Pulmonary Emphysema among HIV-Seropositive Smokers

Several reports (1-3) have suggested that before recognized AIDS-related respiratory complications develop, some HIV-seropositive persons may develop an accelerated form of lung injury that has physiologic features or findings on computed tomography of the chest that are consistent with pulmonary emphysema. Emphysema, defined as enlargement of the terminal air spaces and destruction of the alveolar walls (4), is uniquely characterized by disappearance of lung tissue (4). Insight into the cellular mechanisms critical to pathogenesis of this condition in humans has been limited by the lengthy course over which the disease develops and by the fact that only a minority of smokers develops significant disease (5). The possibility that HIV-seropositive persons may have a greater risk for developing accelerated lung destruction may have broad biological relevance regarding emphysema pathogenesis. With this in mind, we sought to extend previous anecdotal studies and attempted to prospectively characterize a group of HIV-infected persons exhibiting evidence of emphysema-like destructive lung disease. Methods The study sample consisted of 114 consecutive HIV-seropositive persons who underwent high-resolution computed tomography of the chest (1994 through 1997). This group was a sample of a larger cohort of 321 HIV-seropositive persons who had undergone a detailed assessment of respiratory symptoms and pulmonary function. Most participants were from Columbus, Ohio, and were recruited through advertisements, by word of mouth, and by the Ohio State University Medical Center AIDS-Clinical Trials Unit. Less than 10% of the participants were receiving protease inhibitors at the time of this study. Persons with a history of Pneumocystis carinii pneumonia and other pulmonary complications of AIDS were excluded. Controls consisted of 44 HIV - seronegative volunteers matched for age, sex, and smoking history; they were recruited from the general population by advertisements. All participants completed a modified American Thoracic Society Questionnaire (6) for symptoms, smoking history, drug use, history of pneumonia, and medications. Nonsmokers were identified as having a history of cumulative cigarette smoking of 1 pack-year or less. Pulmonary function studies were performed according to American Thoracic Society standards. The study was approved by the Ohio State University human subjects review board. Informed consent was obtained from all participants. Computed tomography was performed with a GE 9800 CT scanner (GE Medical Systems, Milwaukee, Wisconsin) or a Picker PQ 2000 CT scanner (Picker International, Solon, Ohio) with 1.5-mm collimation at 10-mm intervals through the chest. Scans were obtained at total lung capacity in the supine position. Images were reconstructed by using the high spatial frequency algorithm and were photographed at a lung window width of 1500 Hounsfield units (brightness level, 700 Hounsfield units). Emphysema was considered present if the scans showed evidence of bullae, thin-walled cystic spaces, or abnormal decreases in attenuation, accompanied by vascular disruption. Emphysema severity was estimated by assigning an emphysema score (0 to 10) for each lobe according to the percentage of the lobe that was affected. The lingula was considered a separate lobe. The total score represented the sum for all lobes. Scans were interpreted by two experienced chest radiologists, who were blinded to the patients HIV status and physiologic data. Participants were considered to have clear evidence of at least early emphysema if 1) the computed tomography emphysema score was 6 or higher [for example, 25% of two lobes involved with emphysema] or 2) pulmonary function tests demonstrated a total lung capacity greater than 120% of the predicted value, a diffusing capacity less than 60% of predicted, and computed tomographic evidence of emphysema in more than two lobes. Bronchoalveolar lavage and differential cell counts were performed according to standard techniques (7) on consenting participants. This included 46 HIV-seropositive smokers and 14 control smokers. A sample containing more than 1 000 000 cells was analyzed by a fluorescence-activated cell sorter for T-lymphocyte subtyping. An experienced microbiologist, who was blinded to HIV status, examined all lavage samples for the presence of fungi, acid-fast bacilli, P. carinii, and bacteria. Statistical analyses were performed by using the SAS JMP package (8). Analysis of variance was used to compare groups, and post hoc analysis was performed by using the Dunnett procedure (8). The Pearson chi-square test was used for equality of proportions; exact P values were calculated for small samples (9). Results With the exception of a lower CD4 count and diffusing capacity in the HIV-seropositive group, the two study groups had similar baseline characteristics (Table). Of note, 25% of the HIV-seropositive group had a history of oral thrush; however, other HIV-related opportunistic infections were rarely reported (<2%). The percentage of HIV-seropositive persons who reported any use of intravenous drugs was low (approximately 10%), and no significant differences in the use of intravenous drugs, crack cocaine, or marijuana were found between the HIV-seropositive group and the control group. Table. Clinical and Demographic Characteristics of the Study Groups Clinical variables did not significantly differ between the HIV-seropositive group of this study and the 321 persons in the overall HIV cohort (Table). For example, the median age of the overall cohort was 33 years (range, 20 to 66 years), the median CD4 count was 348 cells/mm3 (range, 0 to 1188 cells/mm3), and the median diffusing capacity was 83.7% of predicted (range, 38.8% to 153%). Sixty-three percent of the overall cohort smoked cigarettes. Emphysema was identified in 17 of 114 HIV-seropositive participants compared with 1 of 44 HIV-seronegative controls (P=0.025). Only one HIV-seronegative participant had a computed tomography emphysema score as high as 6, whereas 14 HIV-seropositive participants had scores between 6 and 23. The mean (SE) emphysema score for the HIV-seropositive group with emphysema was 10.5 1.7, the mean total lung capacity was 110% 6.9% of predicted, and the diffusing capacity was 60.1% 11.3% of predicted. Of note, persons with emphysema had only mild airflow obstruction (ratio of FEV1 to FVC, 69.2% 9.4%), which may relate to a higher than expected number of persons (approximately 30%) demonstrating subpleural or peripheral lesions (10). The Figure shows examples of precocious emphysema in HIV-seropositive persons, with accompanying emphysema scores. Figure. High-resolution computed tomographic scans of the chest.A. arrows B. Because a relatively high proportion of cigarette smokers appeared to be susceptible to early destructive changes, we specifically studied the role of smoking history. Thirty-seven percent (14 of 38) of HIV-seropositive smokers with a smoking history of 12 pack-years or more met criteria for emphysema, compared with 0% (0 of 14) HIV-seronegative controls (P=0.011). Furthermore, 46% (11 of 24) of HIV-seropositive participants with a smoking history of 25 pack-years or more met criteria for emphysema, compared with 0% (0 of 10) in the HIV-seronegative controls (P=0.013). Next, using current pack-year of cigarette smoking as a covariate, we compared lung-cell populations among three groups of smokers: HIV-seronegative smokers (n=14), HIV-seropositive smokers without emphysema (n=34), and HIV-seropositive smokers with emphysema (n=12). The numbers of alveolar macrophages and neutrophils in the lavage fluid were similar among the three groups. Although the two HIV-seropositive groups were found to have threefold more lymphocytes than the uninfected controls, no significant difference in lymphocyte numbers were noted between HIV-seropositive persons with and those without emphysema. However, when lymphocyte subtypes were examined, HIV-seropositive persons with emphysema were found to have the highest percentage of lavage lymphocytes bearing the cytotoxic phenotype; the mean (SE) value in this group was 58% 4.6%, compared with 46.6% 2.3% in HIV-seropositive smokers without emphysema (P<0.05) and 32.2% 4.6% in HIV-seronegative smokers (P<0.01). Of note, no pathogens were observed in microbiological stains of lavage fluid from study participants. Discussion This prospective study demonstrates the development of an accelerated form of pulmonary emphysema in a stable HIV-seropositive outpatient sample. Furthermore, the results suggest that the lesion is related to a heightened susceptibility to cigarette smoke. We hypothesize that HIV infection or secondary inflammatory abnormalities directly accelerate the process of smoking-induced parenchymal lung destruction. The cellular mechanisms predisposing HIV-seropositive smokers to emphysema are unclear. However, immunologic aspects of HIV disease may be relevant to understanding emphysema pathogenesis in the general population. Of particular interest are the many bronchoalveolar lavage and lung pathology studies that have demonstrated increased numbers of cytotoxic lymphocytes in the lungs of HIV-seropositive persons (11-13). Although prevailing theories for emphysema have focused on smoking-induced production of proteolytic enzymes by neutrophils and macrophages (4, 5), recent morphometric analyses of lung biopsy sections from non-HIV-infected smokers have demonstrated a high correlation between lung lymphocytes and the presence of emphysema (14, 15). Furthermore, experimental evidence suggests that viral activation of cytotoxic lymphocytes may contribute to parenchymal lung destruction (16). Another potential mechanism recently hypothesized is that latent viral infections may be an important cofactor in the development of chronic obstructive pulmonary disease (17). Adenoviral proteins, latently expressed in host epithelial cells, a

Urine Chemokines as Biomarkers of Human Systemic Lupus Erythematosus Activity

The purpose of this study was to evaluate urine monocyte chemoattractant protein-1 (MCP-1) and IL-8 as biomarkers of SLE flare. Urine was collected every 2 mo from patients who were followed prospectively in the Ohio SLE Study. Renal and nonrenal flares were identified and MCP-1 and IL-8 were measured by specific ELISA in samples that were collected at flare. When available, MCP-1 and IL-8 were also measured in urine samples before and after flare. For comparison, MCP-1 and IL-8 were measured in the urine of healthy individuals and in renal and nonrenal SLE patients with stable disease activity (disease controls). Most patients were receiving maintenance immunosuppressive therapy before flare. At renal flare, mean urine MCP-1 (uMCP-1) was significantly greater than uMCP-1 at nonrenal flare and from healthy volunteers and renal disease controls. The level of uMCP-1 correlated with the increase in proteinuria at flare and was higher in patients with proliferative glomerulonephritis and in patients with impaired renal function. Urine MCP-1 was increased beginning 2 to 4 mo before flare. Patients who responded to therapy showed a slow decline in uMCP-1 over several months, whereas nonresponders had persistently high uMCP-1. In contrast, uIL-8 did not change with disease activity and was not elevated at renal or nonrenal flare compared with disease controls. In conclusion, uMCP-1 but not uIL-8 is a sensitive and specific biomarker of renal SLE flare and its severity, even in patients who receive significant immunosuppressive therapy. Persistently elevated uMCP-1 after treatment may indicate ongoing kidney injury that may adversely affect renal prognosis.

Galectin-3, fibronectin-1, CITED-1, HBME1 and cytokeratin-19 immunohistochemistry is useful for the differential diagnosis of thyroid tumors

The diagnosis of thyroid tumors is critical for clinical management; however, tumors with follicular architecture often present problems. We evaluated the diagnostic use of the protein expression of four genes that were found to be upregulated in papillary thyroid carcinoma compared to normal thyroid (LGALS3, FN1, CITED1 and KRT19), and of the mesothelial cell surface protein recognized by monoclonal antibody HBME1 in thyroid tumors. Tissues from 85 carcinomas (67 papillary, six follicular, eight Hürthle cell and four anaplastic) and 21 adenomas were evaluated by immunohistochemistry for the expression of these gene protein products, for example, galectin-3 (GAL3), fibronectin-1 (FN1), CITED1, cytokeratin-19 (CK19) and HBME1. Non-neoplastic thyroids (29 adenomatous and 14 thyrotoxic hyperplasia, and 59 normal) were also studied. The expression of all five proteins was significantly associated with malignancy, and highly specific (≥90%) for carcinoma compared to adenoma. GAL3, FN1 and/or HBME1 expression was seen in 100% of carcinomas (85/85) and in 24% of adenomas (5/21). Coexpression of multiple proteins was seen in 95% of carcinomas and only 5% of adenomas (P<0.0001). Coexpression of FN1 and GAL3 (FN1+GAL3+, 70/85) or FN1 and HBME1 (FN1+HBME1+, 53/85) was restricted to carcinomas, while their concurrent absence (FN1−GAL3− or FN1−HBME1−, 18/21 adenoma) was highly specific (96%) for benign lesions. Among non-neoplastic thyroids, adenomatous hyperplasia frequently expressed GAL3 (n=16), CK19 (n=9) and CITED1 (n=7), but the expression was predominantly focal in contrast to the diffuse expression in carcinomas. An immunohistochemical panel consisting of GAL3, FN1 and HBME1 may be useful in the diagnosis of follicular cell-derived thyroid tumors.

Record values and related statistics - a review

In this brief survey, we discuss major developments of the past decade in the study of record values, record times, inter-record times and some related statistics from a series of observations

A case-control study of anterior cruciate ligament volume, tibial plateau slopes and intercondylar notch dimensions in ACL-injured knees ☆

The role played by anatomical factors in ACL injury remains elusive. In this study, objective methods were used to characterize ACL volume, tibial slopes and notch geometry from ACL-injured and matched-control subjects. The study tested four hypotheses: (1) the medial tibial plateau slope is steeper posteriorly in the injured group compared to the non-injured group, (2) the lateral tibial plateau slope is steeper posteriorly in the injured group compared to the non-injured group, (3) the femoral intercondylar notch dimensions are smaller in the injured group compared to the non-injured group and (4) the ACL volume, tibial plateau slopes and intercondylar notch dimensions are all independent of each other. Fifty-four subjects were divided into two groups, those who had suffered a non-contact ACL injury and those who still had two healthy ACLs, matched to the injured subjects by gender, age, height and weight. The lateral tibial plateaus in the uninjured contralateral knees of the injured subjects had a significantly steeper posterior slope (1.8 degrees vs. -0.3 degrees ), a factor that potentially contributed to the ACL injury in the opposite knee. The intercondylar notch dimensions were found to be smaller in the injured subjects, potentially putting the ACL at risk of impingement, and intercondylar notch volume was correlated to ACL volume (r=0.58). Discriminant analysis showed that the notch width at the inlet was the best single predictor of ACL injury.

Subgingival Microbial Profiles of Smokers with Periodontitis

The subgingival microbiome is largely uncultivated, and therefore, cultivation-based and targeted molecular approaches have limited value in examining the effect of smoking on this community. We tested the hypothesis that the subgingival biofilm is compositionally different in current and never-smokers by using an open-ended molecular approach for bacterial identification. Subgingival plaque from deep sites of current and never-smokers matched for disease was analyzed by 16S sequencing. Smokers demonstrated greater abundance of Parvimonas, Fusobacterium, Campylobacter, Bacteroides, and Treponema and lower levels of Veillonella, Neisseria, and Streptococcus. Several uncultivated Peptostreptococci, Parvimonas micra, Campy-lobacter gracilis, Treponema socranskii, Dialister pneumosintes, and Tannerella forsythia were elevated in this group, while Veillonella sp. oral clone B2, Neisseria sp. oral clone 2.24, Streptococcus sanguinis, and Capnocytophaga sp. clone AH015 were at lower levels. The microbial profile of smoking-associated periodontitis is distinct from that of non-smokers, with significant differences in the prevalence and abundance of disease-associated and health-compatible organisms.