Calibration inference based on multiple runs of an immunoassay

Several authors have documented the poor performance of usual large-sample, individual calibration confidence intervals based on a single run of an immunoassay. Inaccuracy of these intervals may be attributed to the paucity of information on model parameters available in a single run. Methods for combining information from multiple runs to estimate assay response variance parameters and to refine characterization of the standard curve for the current run via empirical Bayes techniques have been proposed. We investigate formally the utility of these techniques for improving the quality of routine individual calibration inference.

Testing homogeneity of intra-run variance parameters in immunoassay

A common assumption in the analysis of immunoassay data is a similar pattern of within-run variation across runs of the assays. One makes this assumption without formal investigation of its validity, despite the widely acknowledged fact that accurate understanding of intra-run variation is critical to reliable calibration inference. We propose a simple procedure for a formal test of the assumption of the homogeneity of parameters that characterize intra-run variation based on representation of standard curve data from multiple assay runs by a non-linear mixed effects model. We examine the performance of the procedure and investigate the robustness of calibration inference to incorrect assumptions about the pattern of intra-run variation.

Inhibition of epidermal growth factor receptor gene expression and function decreases proliferation of head and neck squamous carcinoma but not normal mucosal epithelial cells

Previous reports have shown that fresh tissues and cell lines from patients with squamous cell carcinoma of the head and neck (SCCHN) overexpress transforming growth factor alpha (TGF-alpha) and its receptor, the epidermal growth factor receptor (EGFR) at both the mRNA and protein levels. Protein localization studies confirm that TGF-alpha and EGFR are produced by the same epithelial cells in tissues from head and neck cancer patients further supporting an autocrine growth pathway. Using three strategies, we examined the hypothesis that downmodulation of EGFR would reduce the proliferation of SCCHN cells. We targeted EGFR mRNA using antisense oligonucleotides and the mature EGFR protein at two sites, the ligand-binding domain and the kinase domain, and determined the effects of this targeting on SCCHN proliferation. Treatment of several SCCHN cell lines with a pair of antisense oligodeoxynucleotides directed against the translation start site and first intron-exon splice junction of the human EGFR gene resulted in decreased EGFR protein production and inhibited growth by 86% compared to a 13% reduction in cells treated with sense oligonucleotides (P=0.03). Growth inhibition was specific for carcinoma cells since the same EGFR antisense oligonucleotides had no effect on the proliferation of normal mucosa cells harvested from non-cancer patients. Two monoclonal antibodies which block ligand binding to EGFR (MAbs 425 and 528) inhibited the growth of several SCCHN cell lines by up to 97% which suggests that EGFR is participating in an autocrine pathway in SCCHN that is, at least in part, external. An EGFR-specific tyrosine kinase inhibitor (PD 153035) was found to inhibit EGFR phosphorylation in SCCHN cell lines and to reduce growth by 68% although it had no effect on the growth rate of normal mucosal epithelial cells. These experiments indicate that EGFR gene expression and function is critical for SCCHN cell growth but not for growth of normal mucosa cells and therefore may serve as a tumor-specific target for preventive and therapeutic strategies in head and neck cancer.

Contribution of the C-terminal tail of U1A RBD1 to RNA recognition and protein stability

The N-terminal RNA binding domain (RBD1) of the human U1A protein interacts specifically with a short RNA hairpin containing the U1 snRNA stem/loop II sequence. Previous RNA binding studies have suggested that the C-terminal tail of RBD1 contributes to RNA recognition in addition to interactions on the beta-sheet surface of the protein. To evaluate the contributions of these C-terminal residues in RBD1 to RNA binding affinity and specificity, as well as to study the thermodynamic stability of RBDs, a number of RBD1 mutants with truncated tails, with single amino acid substitutions, and with both a truncation and an amino acid substitution, have been constructed. The thermodynamic stabilities of these mutants have been measured and compared by GdnHCI unfolding experiments. The RNA binding affinity and specificity of these mutant proteins have been assessed by measuring the binding of each protein to the wild-type RNA hairpin and to selected RNA mutants with nucleotide substitutions in the RNA loop. The results demonstrate first that, although the C-terminal tail of RBD1 makes significant contributions to RNA binding affinity, it is not required for RNA binding, and second, its contributions to binding specificity are mediated only through selected nucleotides in the RNA loop, for in the absence of the tail, the protein continues to use other nucleotides to discriminate among RNAs. In these truncated proteins, the secondary structure intrinsic to the C-terminal tail is absent, yet their affinity and discrimination for RNAs are not lost. Thus, a structured tail is not required for RNA recognition.

[10-year epidemiological study on rheumatic diseases in Shantou area]

22,049 adults were surveyed in a ten-year epidemiological study. The frequency of common rheumatic symptoms in Shantou population was much lower than that in northern China. The prevalence of ankylosing spondylitis, rheumatoid arthritis, osteoarthritis, osteoporosis and gout was 0.20%-0.32%, 0.20%-0.26%, 8.3%-10.8%, 12.4% and 0.15%-0.17% respectively. The frequency of HLA-B27 was 4.1% among general population and 90.6% in ankylosing spondylitis. The most commonly involved sites of osteoarthritis were lumbar spine, neck, and knee; but hands and hip were rarely involved. 85% subjects under investigation were found to be short of calcium intake. The differences between the north and the south of China in the prevalence of rheumatic symptoms may be related to the diversities in consciousness of seeking medical advice, reduction of bone content, climate and ergonomics.

Supporting infobuttons with terminological knowledge

We have developed several prototype applications which integrate clinical systems with on-line information resources by using patient data to drive queries in response to user information needs. We refer to these collectively as infobuttons because they are evoked with a minimum of keyboard entry. We make use of knowledge in our terminology, the Medical Entities Dictionary (MED) to assist with the selection of appropriate queries and resources, as well as the translation of patient data to forms recognized by the resources. This paper describes the kinds of knowledge in the MED, including literal attributes, hierarchical links and other semantic links, and how this knowledge is used in system integration.

Linking a clinical system to heterogeneous information resources

We present a model for providing clinical information system (CIS) users with quick access to high quality information resources. We have developed a chest X-ray information button application which is attached to the chest X-ray reports in the CIS at the Columbia Presbyterian Medical Center. The application generates questions based on clinical information, user interest, generic question templates, and resource availability. It then provides answers to the questions through integrated access to heterogeneous information resources including the CIS itself and publicly accessible Web resources.

[Combustion under microgravity and technique of fire prevention and suppression in space cabin]

This is a brief review on microgravity combustion, along with the discussion of the fundamental characteristics of combustion and fire processes under microgravity. Recent research activities in microgravity combustion and space fire prevention were emphasized. In addition, the potential use of flame-inhibiting atmospheres in the space cabin was introduced. The technique of fire detection and extinguishment in spacecraft environments was also discussed.

Exact solution to the electric field of the double-sided electrode structure in a lead lanthanum zirconated titanate transverse electro-optic modulator

Analytical expressions for the electric field and the capacitance of a double-sided electrode structure are derived by the conformal-mapping method. A clear picture of the electric field is given for an analysis of the quadratic electro-optic effect in a lead lanthanum zirconated titanate transverse modulator. The excess birefringence in the region near the edge of the electrodes causes a reduction of the nonuniformity in the intensity modulation of a double-sided electrode structure compared with that of single-sided electrodes; this reduction is calculated.

Measuring self-efficacy in people with multiple sclerosis: a validation study

OBJECTIVE

To assess the psychometric properties of a measure of self-efficacy in people with multiple sclerosis (MS).

DESIGN

Cross-sectional study by mail with retest.

SETTING

MS Clinic registry of a large Boston teaching hospital .

PATIENTS

141 MS patients representing a broad range of disability.

MAIN OUTCOME MEASURES

The MS Self-Efficacy Scale (MSSE), the Expanded Disability Status Scale, the Sickness Impact Profile, and the mastery subscale of the Ryff Happiness Scale.

RESULTS

The MSSE has high internal consistency and test-retest reliability, both for the overall scale and for the SE Function and SE Control subscales. Results of convergent and divergent validity analyses suggest that the scale is both sensitive and specific.

CONCLUSIONS

We conclude that MSSE is appropriate for assessing self-efficacy in the MS population.

Psychosocial correlates of fatigue in multiple sclerosis

OBJECTIVE

To explore: (1) the interrelation among the neuropsychological, psychological, and psychosocial factors and fatigue as measured by the Multidimensional Assessment of Fatigue scale, and (2) the impact of fatigue on role performance.

DESIGN

Clinical interview with neuropsychological testing and cross-sectional study by mail.

SETTING

Multiple sclerosis (MS) clinic registry of a large Boston teaching hospital.

PATIENTS

139 MS patients representing a broad range of disability.

MAIN OUTCOME MEASURES

The Multidimensional Assessment of Fatigue (MAF) scale, the Extended Disability Status Scale, the Sickness Impact Profile, Rao cognitive battery, the Trailmaking Test, depression, anxiety, and social activity limitations subscales from the Arthritis Impact Measurement Scales, and the Ryff Happiness Scale.

RESULTS

Stepwise multiple regression analyses revealed that having a low sense of environmental mastery was the best psychosocial predictor of both global fatigue and fatigue-related distress, after adjusting for sociodemographic and medical factors. Further, people who reported being more depressed tended to report more severe fatigue. Neuropsychological performance was not associated with fatigue. Fatigue was found to limit social, work, and overall role performance, but not physical role performance.

CONCLUSIONS

People who feel that they can choose or create environments suitable to their psychic or physical conditions report less global fatigue and less fatigue-related distress, and fatigue can have an important impact on role performance. The implications of these findings for designing fatigue management interventions are discussed.

Retinoic acid normalizes the increased gene transcription rate of TGF-alpha and EGFR in head and neck cancer cell lines

Retinoic acid (RA) has been shown to be effective in eradicating premalignant lesions and preventing second primary malignancies in patients cured of squamous cell carcinoma of the head and neck (SCCHN) in clinical trials. The basis for this effect is unclear. We have previously demonstrated that messenger RNA from tumor growth factor-alpha (TGF-alpha) and its receptor, the epidermal growth factor (EGFR), is unregulated in tumors and histologically normal mucosal samples from patients with SCCHN compared with control normal mucosa from patients without cancer, implicating this ligand-receptor pair in an autocrine growth pathway early in the molecular pathogenesis of this disease. In this report, we examined the hypothesis that the action of RA on the mucosa of the upper aerodigestive tract is mediated via downregulation of steady-state TGF-alpha and/or EGFR mRNA levels. Following exposure to all-trans-RA, a series of SCCHN cell lines demonstrated a 35.4% reduction in TGF-alpha mRNA expression (P = 0.022) and 58.5% reduction in EGFR mRNA (P = 0.0027). Nuclear run-on analysis indicated that the RA-mediated reduction of TGF-alpha and EGFR steady-state mRNA levels was a result of decreased gene transcription. These results suggest that the clinical effects of RA in SCCHN patients may be due to a downmodulation of TGF-alpha and EGFR mRNA production.

The N-terminal domain of TFIIB from Pyrococcus furiosus forms a zinc ribbon

The three-dimensional structure of the N-terminal domain of an archaeal TFIIB, which has high sequence homology with eucaryal analogues, is strikingly similar to that of the C-terminal zinc ribbon of the eucaryal transcription elongation factor TFIIB.

Mapping medical vocabularies to the Unified Medical Language System

This paper presents our work in automated mapping of medical vocabularies to the National Library of Medicine's Unified Medical Language System (UMLS). We used the UMLS Knowledge Source (KS) tool to map terms from several sources to UMLS Metathesaurus concepts. We compared performance of the KS tools with our own Minimal Representable Units Method (MRUM). The KS tools were able to map terms from 13% to 54% of the time, depending on the term set and the KS options used. Our MRUM method mapped between 96% and 99% of the terms. Based on our experience, we believe that questions remain about the best method by which the UMLS can be used to achieve automated term translation.

Insect-resistant tobacco plants expressing insect-specific neurotoxin AaIT

The recombinant plant expression vector pNGY-2 with designed and synthesized AaIT gene had been constructed. The AaIT gene was fused behind the sequence of TMV and inserted into expression vector under the control of two linked 35s promoters. The recombinant plasmid pNGY-2 was transferred into tobacco NC89 by agrobacterium-mediated transfer system. The GUS activity analysis and Southern blotting of regenerated plants indicated that AaIT gene had been integrated into tobacco genome. Insect bioassays showed that some transgenic plants had notable insect-resistant activity.

Glycoconjugates and keratin 18 define subsets of taste cells

Sections of neonatal, normal adult and denervated adult rat tongue were examined with lectin histochemistry. Attention was focused upon intragemmal cells (cells within the taste bud) and the surrounding perigemmal cells. Informative staining patterns were observed with four of 12 lectins: Ulex europaeus (UEA-I), Bauhinia purpurea (BPA), Helix pomatia (HPA) and Lotus tetragonolobus (LTA) agglutinins. In normal adult tongues, BPA bound to those lingual epithelial cells lacking contact with the basal lamina. After they formed, vallate taste buds were laterally surrounded by distinctive BPA-positive cells. HPA reacted selectively with 28% and LTA with 23% of the intragemmal cells in vallate/foliate taste buds. In double-stained taste buds there was a statistically significant overlap of LTA-positive cells and keratin 18-positive cells. The overlap between HPA binding and keratin 18 was more marked: double-stained cells comprized 67% of all stained cells. During taste bud development in neonates keratin 18 synthesis preceded HPA binding. In contrast, during the replacement of adult taste cells, keratin 18 synthesis and HPA binding were generally concurrent. Keratin 18 and HPA probably identify the same subset of older taste receptor cells. HPA may bind to glycoconjugates on the surface of keratin 18-positive cells. In denervated adult tongue the loss of all UEA-I-positive or BPA-positive perigemmal cells suggests that perigemmal as well as intragemmal cells are nerve-dependent.

[Plasma nitric oxide in patients with renal transplants]

The plasma nitric oxide (NO) in 32 patients with renal allografts was observed before transplantation and in the early period of three months after transplantation. Endothelin (ET), cyclosporin A blood concentration, Creatinine (Cr), blood urea nitrogen (BUN) were measured simultaneously. The results showed that plasma NO level (24.01 +/- 1.15 mumol/L) before transplantation was significantly higher than that after transplantation. There was significant correlation between plasma NO level and ET, Cr, BUN and blood pressure. We consider that plasma NO concentration may reflect the function of renal transplant and play an important role in early renal injury after kidney transplantation.

Keratin 18 is associated with a subset of older taste cells in the rat

All or nearly all intragemmal (elongated) cells of rat taste buds were immunopositive for keratins 7, 8, and 19. In contrast, keratin 18 was detected in 19 +/- 5 cells per taste bud (mean +/- sd), or about 25% of the intragemmal cells. During taste bud development keratins 7, 8, and 19 were evident initially in polygonal cells and later in elongated taste cells. Keratin 8 appeared in vallate taste cells at P0 (postnatal day 0), followed by keratins 7 and 19 at P1, and keratin 18 at P2-P3. Keratin 18 was always limited to elongated cells. The assemblage of elongated taste cells comprising a taste bud began with a single elongated cell, rather than with the synchronous elongation of a cluster of cells. Developmental errors were observed at P2-P3, e.g., some vallate taste cells had a misoriented axis. In order to study the pace of keratin differentiation during cell turnover we injected bromodeoxyuridine (BrdU) into adult rats to monitor taste cell age. Keratin-19-positive intragemmal cells differentiated within 1 day. In contrast, keratin 18 was first detected in cells aged 3 days. Hence, both in taste cell development and replacement, keratin 18 was restricted to the older cells; it was the last taste cell keratin to become expressed during differentiation.

An apolipoprotein CIII marker associated with hypertriglyceridemia in Caucasians also confers increased risk in a west Japanese population

Polymorphisms and haplotypes at the adjacent apolipoprotein (apo) AI and CIII gene loci were investigated in 61 Japanese patients with triglycerides greater than 350 mg/dl and in 66 unrelated normolipidemic subjects. The polymorphic sites were the SstI site in the apoCIII 3' untranslated region, whose presence has previously been shown to be associated with hypertriglyceridemia (HTG) in Caucasians, and the MspI site in the third intron of the apoAI gene. The frequencies of the SstI minor allele (S2) were 0.48 in HTG patients and 0.25 in normolipidemic subjects (P < 0.00015). The frequencies of the MspI minor allele (M2) were 0.61 in HTG patients and 0.33 in normolipidemic subjects (P < 0.00001). The two polymorphic sites were in strong linkage disequilibrium, and maximum likelihood analysis supported the existence of three of the four possible haplotypes: S1-M1, S1-M2, and S2-M2. Since all S2 alleles were estimated to be present on M2-bearing chromosomes, the HTG-associated S2-M2 haplotype conferred the same approximate relative risk as the S2 allele alone when compared with the other two haplotypes (odds ratio 2.8). This study demonstrates that the S2 allele is a marker for HTG among west Japanese subjects as well as among Caucasians. The results suggest that S2-M2 chromosomes carry HTG susceptibility sequences that predate the separation of the Asian and Caucasian races.