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At least 1,531 records · Page 85Linked to original sources
PubMed2000

Correlation between static automated and scanning laser entoptic perimetry in normal subjects and glaucoma patients.

OBJECTIVE: To compare the effectiveness of scanning laser entoptic perimetry with static automated perimetry as a noninvasive instrument for screening for glaucomatous damage in visually asymptomatic subjects within the central 60 degrees (diameter) of vision. DESIGN: A masked cross-sectional study comparing entoptic perimetry to achromatic threshold perimetry. PARTICIPANTS: Twenty-three subjects and controls from the Sharp Rees-Stealy Hospital and the Shiley Eye Center at the University of California, San Diego. TESTING: Virtual reality-based entoptic perimetry was compared with achromatic threshold perimetry. MAIN OUTCOME MEASURES: For each testing session, we compared the presence of a disturbance in the entoptic perimetry stimulus with the presence of defects in visual function as measured by Humphrey automated visual field perimetry. RESULTS: Scanning laser entoptic perimetry reasonably estimates the overall visual field loss for moderate-to-severe scotomas as measured by the pattern deviation in standard visual field perimetry. Scanning laser entoptic perimetry has a sensitivity from 27% to 90% and a specificity from 50% to 100% for screening moderate-to-severe visual field defects caused by glaucoma within the central 60 degrees diameter of vision. CONCLUSIONS: Scanning laser entoptic perimetry may be an effective and inexpensive screening test in hospitals and community clinics for diagnosing visual field loss caused by glaucoma.

Cross-Sectional Studies↗
PubMed1994

tRNA structure and ribosomal function. I. tRNA nucleotide 27-43 mutations enhance first position wobble.

Transfer RNA su7 G36 is a derivative of tRNA(Trp) with a 3'GUC anticodon complementary to the glutamine codon CAG. This tRNA requires a normally forbidden G-U wobble at the first codon position to suppress a UAG (amber) termination codon. Measurement of amber suppression by mutated su7 G36 tRNAs and correction for tRNA levels and aminoacylation allowed calculation of KUAG, a linearized index of in vivo ribosomal function. Following saturating mutagenesis of the anticodon arm of su7 G36, screening for UAG suppression using a lacZ reporter yielded tRNAs with up to 40-fold increased first position G-U wobble, judged from KUAG. The parental anticodon helix has minimized this type of miscoding, and virtually all changes in the top base-pair of the anticodon helix, nucleotides (nt) 27-43, increased the error. Thus, misincorporation of amino acids due to aberrant first position wobble is apparently prevented by normal tRNA structure, which is specifically altered by substitution at nt 27-43, the top base-pair of the anticodon helix. All 16 permutations of nt 27-43, the hotspot for increased wobble, were subsequently constructed and compared. Comparison of values for tRNA coding function, tRNA level, and aminoacylation for the 16 suggest that a tRNA conformational change, specifically involving both nt 27-43, differentially affects all these tRNA functions. This conformational alteration, which presumably occurs normally on the ribosome, appears more complex than simple breakage of the normal 27-43 base-pair. We suggest that the change is in the angle and/or flexibility of the tRNA L-shape. Among these 16 tRNAs, efficient wobble is strongly and inversely correlated with good aminoacylation and high tRNA levels; this quality may have been selected. Constraints on the sequences of natural tRNAs suggest that nt 27-43 have effects on function in many tRNAs.

Anticodon↗
PubMed2003

Amplification and overexpression of the L-MYC proto-oncogene in ovarian carcinomas.

Gene amplification is an important mechanism of oncogene activation in various human cancers, including ovarian carcinomas (OvCas). We used restriction landmark genomic scanning (RLGS) to detect amplified DNA fragments in the genomes of 47 primary OvCas. Visual analysis of the RLGS gel images revealed several OvCa samples with spots of greater intensity than corresponding spots from normal tissues, indicating possible DNA amplification in specific tumors. Two primary tumors (E1 and S12) shared four high-intensity spots. A recently developed informatics tool termed Virtual Genome Scans was used to compare the RLGS patterns in these tumors with patterns predicted from the human genome sequence. Virtual Genome Scans determined that three of the four fragments localized to chromosome 1p34-35, a region containing the proto-oncogene L-MYC. Sixty-eight primary OvCas, including 40 analyzed by RLGS, were screened by quantitative polymerase chain reaction (PCR) for possible amplification of L-MYC. Ten tumors with increased L-MYC copy number were identified, including tumor E1, which showed an approximately 24-fold increase in copy number compared to normal DNA. Southern analysis of several tumors confirmed the quantitative PCR results. Using sequence tagged site (STS) markers flanking L-MYC, increased DNA copy number in tumor E1 was found to span the region flanking L-MYC between D1S432 and D1S463 ( approximately 3.1 Mb). Other tumors showed amplification only at the L-MYC locus. Using oligonucleotide microarrays, L-MYC was found to be more frequently overexpressed in OvCas than either c-MYC or N-MYC relative to ovarian surface epithelium. Quantitative reverse transcriptase-PCR analysis confirmed elevated L-MYC expression in a substantial fraction of OvCas, including nine of nine tumors with increased L-MYC copy number. The data implicate L-MYC gene amplification and/or overexpression in human OvCa pathogenesis.

Base Sequence↗
PubMed1996

The immunodominant major histocompatibility complex class I-restricted antigen of a murine colon tumor derives from an endogenous retroviral gene product.

Tumors express peptide antigens capable of being recognized by tumor-specific cytotoxic T lymphocytes (CTL). Immunization of mice with a carcinogen-induced colorectal tumor, CT26, engineered to secrete granulocyte/macrophage colony-stimulating factor, routinely generated both short-term and long-term CTL lines that not only lysed the parental tumor in vitro, but also cured mice of established tumor following adoptive transfer in vivo. When either short-term or long-term CTL lines were used to screen peptides isolated from CT26, one reverse-phase high performance liquid chromatography peptide fraction consistently sensitized a surrogate target for specific lysis. The bioactivity remained localized within one fraction following multiple purification procedures, indicating that virtually all of the CT26-specific CTL recognized a single peptide. This result contrasts with other tumor systems, where multiple bioactive peptide fractions have been detected. The bioactive peptide was identified as a nonmutated nonamer derived from the envelope protein (gp70) of an endogenous ecotropic murine leukemia provirus. Adoptive transfer with CTL lines specific for this antigen demonstrated that this epitope represents a potent tumor rejection antigen. The selective expression of this antigen in multiple non-viral-induced tumors provides evidence for a unique class of shared immunodominant tumor associated antigens as targets for antitumor immunity.

Animals↗
PubMedDate not supplied

Knowledge, satisfaction, and perceived cancer risk among women diagnosed with ductal carcinoma in situ.

The prevalence of ductal carcinoma in situ (DCIS) has increased through more widespread use of screening mammography. Little is known about what women with DCIS understand about their disease and future health. Although there is a wealth of information about the psychological characteristics of women with invasive breast cancer, there is virtually no information about women who have received treatment for DCIS. Seventy-six women diagnosed with DCIS who were identified through the Duke University Tumor Registry completed a mailed self-administered questionnaire including a broad range of items to measure knowledge, satisfaction with care, risk perceptions, and psychological distress. Women with DCIS have knowledge deficits about DCIS and breast cancer, as well as concerns about recurrence and misperceptions about the likelihood for DCIS metastasis. Women were generally satisfied with their care. They were less satisfied with information related to prognosis and with perceived support from their doctors. The results of this study suggest several areas of concern for women diagnosed with DCIS. Data about risk perceptions, knowledge, and attitudes in women diagnosed with DCIS provide important preliminary ideas for future studies. In view of the frequency of the DCIS diagnosis, future investigation should be conducted to build on these findings.

Adaptation, Psychological↗
PubMed1987

Studies on the hemolytic activity of the classical and alternative pathway of complement in various animal species.

The classical complement pathway (CP) activity (CH50) of sera of 13 animal species was compared by parallel assays using rabbit erythrocytes sensitized with immune antibody (RaE-Ab) and sensitized sheep erythrocytes (ShE-Ab). The alternative complement pathway (AP) activity (ACH50) in various species of animals was also measured using 13 species of erythrocytes and RaE-Ab as target cells. The results have demonstrated that virtually all species of animals studied possess CP and AP activity levels comparable with or higher than those in human sera. Concomitant measurement of the hemagglutinin titer to various species of erythrocytes carried out in the screening ACH50 assays on various species of sera with these erythrocytes disclosed a significant correlation between natural antibody level and AP activity (p less than 0.05).

Animals↗
PubMedDate not supplied

Anticonvulsants for soman-induced seizure activity.

This report describes studies of anticonvulsants for the organophosphorus (OP) nerve agent soman: a basic research effort to understand how different pharmacological classes of compounds influence the expression of seizure produced by soman in rats, and a drug screening effort to determine whether clinically useful antiepileptics can modulate soman-induced seizures in rats. Electroencephalographic (EEG) recordings were used in these studies. Basic studies were conducted in rats pretreated with HI-6 and challenged with 1.6 x LD50 soman. Antimuscarinic compounds were extremely effective in blocking (pretreatment) or terminating soman seizures when given 5 min after seizure onset. However, significantly higher doses were required when treatment was delayed for more than 10 min, and some antimuscarinic compounds lost anticonvulsant efficacy when treatment was delayed for more than 40 min. Diazepam blocked seizure onset, yet seizures could recur after an initial period of anticonvulsant effect at doses </=2.5 mg/kg. Diazepam could terminate ongoing seizures when given 5 min after seizure onset, but doses up to 20 mg/kg were ineffective when treatment was delayed for 40 min. The GABA uptake inhibitor, tiagabine, was ineffective in blocking or terminating soman motor convulsions or seizures. The glutamate receptor antagonists, NBQX, GYKI 52466, and memantine, had weak or minimal antiseizure activity, even at doses that virtually eliminated signs of motor convulsions. The antinicotinic, mecamylamine, was ineffective in blocking or stopping seizure activity. Pretreatment with a narrow range of doses of alpha2-adrenergic agonist, clonidine, produced variable protection (40-60%) against seizure onset; treatment after seizure onset with clonidine was not effective. Screening studies in rats, using HI-6 pretreatment, showed that benzodiazepines (diazepam, midazolam and lorazepam) were quite effective when given 5 min after seizure onset, but lost their efficacy when given 40 min after onset. The barbiturate, pentobarbital, was modestly effective in terminating seizures when given 5 or 40 min after seizure onset, while other clinically effective antiepileptic drugs, trimethadione and valproic acid, were only slightly effective when given 5 min after onset. In contrast, phenytoin, carbamazepine, ethosuximide, magnesium sulfate, lamotrigine, primidone, felbamate, acetazolamide, and ketamine were ineffective.

Animals↗
PubMed1990

Labeled antigen capture assay: a method for detecting monoclonal antibodies to cloned gene products.

We report here a relatively easy and highly sensitive assay for detecting monoclonal antibodies to the product of virtually any cloned gene. The protocol, termed labeled antigen capture assay (LACA), is a solid-phase type radioimmunoassay which uses a bacteriophage T7 expression system to generate exclusively radiolabeled antigen. Thus, to generate radiolabeled antigen for screening, the gene encoding the protein of interest need only be subcloned downstream of a T7 promoter, and the new construct transformed into an Escherichia coli strain harboring a compatible plasmid which encodes a thermal inducible copy of the T7 RNA polymerase. Expression of the T7-promoted gene in the presence of rifampicin and [35S]cysteine (or methionine) yields labeled antigen, which is then "captured" by specific monoclonal antibody and detected by autoradiography. Our results indicate that as little as 30 ng of specific monoclonal antibody can be detected using the LACA protocol. The protocol is applicable to the product of any cloned gene but is particularly useful in the case where the biochemical properties of the gene product of interest are unavailable. In this report we use the LACA protocol to screen a hybridoma library for monoclonal antibodies to the STb heat-stable enterotoxin (STb) of E. coli. Mice were immunized with a genetically constructed, affinity-purified Protein A-STb hybrid protein, and following spleen cell fusion and HAT selection, hybridomas were screened by the described LACA protocol for production of STb-specific monoclonal antibody. Of over 1500 hybridomas tested 138 were positive, by primary LACA screening, for STb-specific IgG monoclonal antibodies.

Alkaline Phosphatase↗
PubMedDate not supplied

Diversity measures for enhancing ADME admissibility of combinatorial libraries.

For general screening libraries, structural diversity descriptors and drug-likeness indicators still do not guarantee the in vivo bioavailability for the candidates, which is considered a major bottleneck in drug development. Early prediction of pharmacokinetics (log P, log D), metabolism, and toxicity makes it possible to deal with ADME (adsorption, distribution, metabolism, excretion) related diversity as an extension to the classical diversity concepts. It opens several new possibilities for optimization of a discovery library before doing any experimental screening. This new diversity concept is demonstrated on a subset of MeDiverse, which is a diverse collection of pharmacologically relevant compounds selected from our in-house library. From consideration of the ADME interface in living systems, virtual secondary libraries of metabolites and retrometabolites (prodrugs) can be generated. These additional libraries readily enhance both the structural and ADME related diversity. This new opportunity in library design can substantially improve the success rate for in vivo lead generation from in vitro hits.

Biological Assay↗
PubMed1986

Molecular cloning of tomato fruit polygalacturonase: Analysis of polygalacturonase mRNA levels during ripening.

The expression of a gene encoding the cell wall-degrading enzyme polygalacturonase [poly(1,4-alpha-D-galacturonide) glucanohydrolase, EC 3.2.1.15] was characterized during tomato fruit ripening. Polygalacturonase was purified from ripe tomato fruit and used to produce highly specific antiserum. Immunoblot analyses detected a 45- and a 46-kDa protein in ripe fruit but immunoprecipitation of in vitro translation products of mRNA from ripe tomato fruit yielded a single 54-kDa polypeptide, suggesting post-translational processing. A plasmid cDNA library was prepared from poly(A)(+) RNA isolated from ripe tomato fruit. The cDNA library was inserted into a lambda-based expression vector, and polygalacturonase cDNA clones were identified by immunological screening. Hybrid-select translation experiments indicated that the cDNAs encode a 54-kDa in vitro translation product that is specifically immunoprecipitated with polygalacturonase antiserum. RNA-blot analysis indicated that the 1.9-kilobase polygalacturonase mRNA was virtually absent from immature-green fruit, accumulated steadily during the ripening process, and was at its highest level in red-ripe fruit. There was at least a 2000-fold increase in the level of polygalacturonase mRNA between immature-green and red-ripe tomato fruit. These studies show that the levels of polygalacturonase mRNA are developmentally regulated during tomato fruit ripening.

Journal Article↗
PubMed2005

The elevated 10-year risk of cervical precancer and cancer in women with human papillomavirus (HPV) type 16 or 18 and the possible utility of type-specific HPV testing in clinical practice.

BACKGROUND: Human papillomavirus (HPV) types 16 and 18 cause 60%-70% of cervical cancer worldwide, and other HPV types cause virtually all remaining cases. Pooled HPV testing for 13 oncogenic types, including HPV16 and 18, is currently used in clinical practice for triage of equivocal cytology and, in conjunction with Pap tests, is an option for general screening among women 30 years of age and older. It is not clear to what extent individual identification of HPV16 or HPV18 as an adjunct to pooled oncogenic HPV testing might effectively identify women at particularly high risk of cervical cancer or its immediate precursor, cervical intraepithelial neoplasia 3 (CIN3). METHODS: From April 1, 1989, to November 2, 1990, a total of 20 810 women in the Kaiser Permanente health plan in Portland, OR, enrolled in a cohort study of HPV and cervical neoplasia. Women were tested for 13 oncogenic HPV types by Hybrid Capture 2 (HC2), and those women with a positive HC2 test were tested for HPV16 and 18. Enrollment Pap smear interpretation and HPV test results were linked to histologically confirmed CIN3 and cervical cancer (> or = CIN3) occurring during 10 years of cytologic follow-up. We calculated cumulative incidence rates with 95% confidence intervals for each interval up to 122 months using Kaplan-Meier methods. RESULTS: The 10-year cumulative incidence rates of > or = CIN3 were 17.2% (95% confidence interval [CI] = 11.5% to 22.9%) among HPV16+ women and 13.6% (95% CI = 3.6% to 23.7%) among HPV18+ (HPV16-) women, but only 3.0% (95% CI = 1.9% to 4.2%) among HC2+ women negative for HPV16 or HPV18. The 10-year cumulative incidence among HC2- women was 0.8% (95% CI = 0.6% to 1.1%). A subanalysis among women 30 years of age and older with normal cytology at enrollment strengthened the observed risk differences. CONCLUSIONS: HPV screening that distinguishes HPV16 and HPV18 from other oncogenic HPV types may identify women at the greatest risk of > or = CIN3 and may permit less aggressive management of other women with oncogenic HPV infections.

Adult↗
PubMed1986

Apolipoprotein C-II deficiency syndrome. Clinical features, lipoprotein characterization, lipase activity, and correction of hypertriglyceridemia after apolipoprotein C-II administration in two affected patients.

Two patients (brother and sister, 41 and 39 yr of age, respectively) have been shown to have marked elevation of plasma triglycerides and chylomicrons, decreased low density lipoproteins (LDL) and high density lipoproteins (HDL), a type I lipoprotein phenotype, and a deficiency of plasma apolipoprotein C-II (apo C-II). The male patient had a history of recurrent bouts of abdominal pain often accompanied by eruptive xanthomas. The female subject, identified by family screening, was asymptomatic. Hepatosplenomegaly was present in both subjects. Analytical and zonal ultracentrifugation revealed a marked increase in triglyceride-rich lipoproteins including chylomicrons and very low density lipoproteins, a reduction in LDL, and the presence of virtually only the HDL3 subfraction. LDL were heterogeneous with the major subfraction of a higher hydrated density than that observed in plasma lipoproteins of normal subjects. Apo C-II levels, quantitated by radioimmunoassay, were 0.13 mg/dl and 0.12 mg/dl, in the male and female proband, respectively. A variant of apo C-II (apo C-IIPadova) with lower apparent molecular weight and more acidic isoelectric point was identified in both probands by two-dimensional gel electrophoresis. The marked hypertriglyceridemia and elevation of triglyceride-rich lipoproteins were corrected by the infusion of normal plasma or the injection of a biologically active synthesized 44-79 amino acid residue peptide fragment of apo C-II. The reduction in plasma triglycerides after the injection of the synthetic apo C-II peptide persisted for 13-20 d. These results definitively established that the dyslipoproteinemia in this syndrome is due to a deficiency of normal apo C-II. A possible therapeutic role for replacement therapy of apo C-II by synthetic or recombinant apo C-II in those patients with severe hypertriglyceridemia and recurrent pancreatitis may be possible in the future.

Adult↗
PubMed2003

The assessment of deep vein thromboses for therapeutic trials.

In the current paper, we provide recommendations for the assessment of deep vein thromboses for the purpose of therapeutic trials evaluating antithrombotic drugs in the prevention of deep venous thrombosis. We have reviewed recently published articles on diagnostic and therapeutic studies, and we have evaluated methods of assessments. Ascending venography has been considered as the reference test for the confirmation of DVT. A roentgenographic image is subsequently available for review and allows classification by blinded, objective observers. However, venography poses substantial clinical and methodological limitations, particularly in the setting of systematic screening for all patients enrolled in a randomized clinical trial. Compression ultrasonography may replace venography for systematic screening of DVT in clinical trials, provided that specific methodological details are specified in the protocol and are fulfilled to ensure high and comparable sensitivity and specificity from all participating centers. This non-invasive technique has virtually no contraindications, and therefore more patients can be enrolled and evaluated. Furthermore, the compression ultrasonograph can be videotaped for central reading. Compression ultrasonography has already been adopted as the principal method for evaluating DVT in several ongoing large scale prevention trials with the approval of major drug agencies.

Clinical Trials as Topic↗
PubMed2000

Regression models for disease prevalence with diagnostic tests on pools of serum samples.

Whether the aim is to diagnose individuals or estimate prevalence, many epidemiological studies have demonstrated the successful use of tests on pooled sera. These tests detect whether at least one sample in the pool is positive. Although originally designed to reduce diagnostic costs, testing pools also lowers false positive and negative rates in low prevalence settings and yields more precise prevalence estimates. Current methods are aimed at estimating the average population risk from diagnostic tests on pools. In this article, we extend the original class of risk estimators to adjust for covariates recorded on individual pool members. Maximum likelihood theory provides a flexible estimation method that handles different covariate values in the pool, different pool sizes, and errors in test results. In special cases, software for generalized linear models can be used. Pool design has a strong impact on precision and cost efficiency, with covariate-homogeneous pools carrying the largest amount of information. We perform joint pool and sample size calculations using information from individual contributors to the pool and show that a good design can severely reduce cost and yet increase precision. The methods are illustrated using data from a Kenyan surveillance study of HIV. Compared to individual testing, age-homogeneous, optimal-sized pools of average size seven reduce cost to 44% of the original price with virtually no loss in precision.

Biometry↗
PubMed1996

Developmental dysplasia of the hip. A population-based comparison of ultrasound and clinical findings.

Clinical and ultrasound findings were compared in 3613 newborns examined for developmental dysplasia of the hip (DDH) within 48 hours of delivery. Clinical and sonographic hip stability was described as stable, borderline unstable, dislocatable or dislocated, and the morphology on ultrasound as normal, immature or dysplastic. Persistent clinical or sonographic dislocatability or dislocation, major dysplasia or minor dysplasia combined with an unstable femoral head were indications for early treatment. A total of 123 (3.4%) infants were subjected to early treatment, of which 55 (45%) fulfilled the criteria for treatment on both clinical and ultrasound examinations, 52 (42%) were treated on the basis of ultrasound findings alone, and 16 (13%) on the basis of clinical findings alone. Thirty per cent of the infants with clinically dislocated or dislocatable hips were judged to have stable or just borderline unstable hips on the first clinical examination. Of 486 (13.5%) infants with sonographically immature or minor dysplastic but stable hips, 472 (97%) normalized spontaneously, while treatment was initiated in 14 (3%) of them at 1-3 months of age because of lack of sonographic improvement. Only one infant presented with late DDH during an observation period of 3 years. Accepting sonographic dysplasia as a criterion for early splinting may result in a treatment rate which is almost twice the rate based on clinical criteria, but late dislocation may be virtually eliminated.

Cross-Sectional Studies↗
PubMed1991

Rigorous health screening reduces age effect on memory scanning task.

Eighty subjects participated in a study with five age groups (20, 30, 40, 50, and 60 years). Forty subjects showed evidence of factors related to brain dysfunction (risk factors). Their performance on a Sternberg-type memory scanning task was assessed. Age-related slowing of virtually all aspects of the memory scanning process was observed in the healthy group. However, the effect of the presence of risk factors was larger than that of biological age. The results of the present study make a reasonable case for the view that many age effects reported in the literature can be largely explained by suboptimal brain functioning, i.e., by other factors than aging per se.

Adult↗
PubMed2003

Staging tools for nonsmall cell lung cancer.

Accurate staging remains the cornerstone of initial managment of nonsmall cell lung cancer. CT offers the potential advantage of identifying early stage tumors when broadly applied as a screening tool, although studies that are evaluating the sensitivity, specificity, and impact on survival are ongoing. PET is a functional imaging tool with ever-broadening applications. New techniques, such as CT-PET fusion imaging, endoscopic ultrasound, virtual bronchoscopy, and three-dimensional volumetric reconstruction may further refine noninvasive diagnostic and staging options.

Carcinoma, Non-Small-Cell Lung↗
PubMed1996

A critical arginine residue mediates cooperativity in the contact interface between transcription factors NFAT and AP-1.

The heterologous transcription factors NFAT and AP-1 coordinately regulate cytokine gene expression through cooperative binding to precisely juxtaposed DNA recognition elements. The molecular origins of cooperativity in the binding of NFAT and AP-1 to DNA are poorly understood. Herein we have used yeast one-hybrid screening and alanine-scanning mutagenesis to identify residues in AP-1 that affect cooperative interactions with NFAT on DNA. Mutation of a single conserved Arg residue to Ala in the cJun spacer region (R285A) led to a virtually complete abolition of cooperative interactions with NFAT. The DNA-binding activity of AP-1 alone was unaffected by the cJun R285A mutation, thus indicating that this residue influences cooperative binding only. Ala-scanning mutations elsewhere in AP-1, including the cFos subunit, revealed no other strongly interacting single positions. We thus conclude that NFAT contacts AP-1 in the spacer region of the cJun subunit, making an especially important contact to R285, and that these interactions drive formation of the cooperative NFAT/AP-1/DNA complex. These results provide a general strategy for selectively ablating cooperativity between transcription factors without affecting their ability to act alone and yield insights into the structural basis for coordinate regulation of gene expression.

Alanine↗