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At least 577 records · Page 32Linked to original sources
PubMed1992

Blood spot screening and confirmatory tests for syphilis antibody.

We developed a blood spot test for syphilis antibody using enzyme-linked immunosorbent assay (ELISA) technology. Dried blood was eluted by buffered saline or, for a supplementary confirmatory test, by treponemal-antibody test diluent. Eluates were diluted in an absorption buffer (Calypte Biomedical, Berkeley, Calif.) and added to plate wells coated with cardiolipin antigen (ADI Diagnostics, Toronto, Ontario, Canada). The wells were washed and treated sequentially with an immunoglobulin G conjugate, buffer washes, and enzyme substrate. Substrate conversion was measured photometrically, and specimen reactivity was determined by reference to nonreactive controls. The optimum test protocol was established by tests of serum and plasma. The serum ELISA specificity with normal specimens was 98.9%. The sensitivity with sera from patients with undefined syphilis was 97.4%, that with sera from patients with documented primary and secondary disease was 100%, and that with sera from patients with early and late latent disease was 95.7%. The specificity of the spot test with donor blood was 94.2%, and its specificity with newborn blood was 94.9%. The sensitivity with 25 spots spiked with reactive sera was 96%. The seroprevalence rates for parturient women in one hospital were 6.01% according to spot tests of sera from 599 newborns and 6.81% according to Rapid Plasma Reagin tests of 499 maternal serum specimens. Seventy percent of infants born to 50 seropositive women were reactive by either the newborn spot or the Rapid Plasma Reagin serum test. The results show that blood spots may be used in seroprevalence or serodiagnostic studies, especially to identify women who are infected or to identify possible cases of congenital infection. The test provides for studies of children and adults when routine venipuncture and serum handling and storage are problematic.

Antibodies, Bacterial↗
PubMed2002

Performance of the New Bayer VERSANT HCV RNA 3.0 assay for quantitation of hepatitis C virus RNA in plasma and serum: conversion to international units and comparison with the Roche COBAS Amplicor HCV Monitor, Version 2.0, assay.

We have evaluated the VERSANT HCV RNA 3.0. Assay (HCV 3.0 bDNA assay) (Bayer Diagnostics, Berkeley, Calif.), which is an improved signal amplification procedure for the HCV 2.0 bDNA assay for the quantitation of hepatitis C virus (HCV) RNA in serum or plasma of HCV-infected individuals. The HCV 3.0 bDNA assay has a linear dynamic range of 2.5 x 10(3) to 4.0 x 10(7) HCV RNA copies per ml (c/ml). The performance of the HCV 3.0 bDNA assay was evaluated using three different test panels. An overall specificity of 96.8% relative to the detection limit of the HCV 3.0 bDNA assay was found. The intra- and interrun reproducibilities for both the dilution panel and the NAP (AcroMetrix, Benicia, Calif.) panel were consistent with coefficients of variation of less than 9%. Quantitation with the HCV 3.0 bDNA assay was linear over the entire range of both panels (ranges of 4.4 x 10(3) to 3.5 x 10(6) c/ml and 5 x 10(3) to 2 x 10(6) IU/ml, respectively), with correlation coefficients of 0.999, slopes close to one, and intercepts close to zero. The regression equation indicated that 1 IU corresponded to about 4.8 copies of HCV RNA. A correlation coefficient of 0.941 was found for HCV RNA values (in international units per milliliter) obtained from the HCV 3.0 bDNA assay and the HCV Monitor version 2.0 assay (HCV Monitor 2.0 assay) (Roche Diagnostic Systems, Branchburg, N.J.). Quantitative results obtained close to the lower limit of the HCV 3.0 bDNA assay might imply that its lower limit should be reconsidered and raised, if necessary. It appeared that quantitation values obtained from the HCV Monitor 2.0 assay of between 5 x 10(2) and 10(5) IU/ml were in general higher than those obtained from the HCV 3.0 bDNA assay, whereas values obtained from the HCV Monitor 2.0 assay were underestimated for samples with HCV RNA levels above 10(5) IU/ml.

DNA, Viral↗
PubMed2002

Diagnostic detection of human immunodeficiency virus type 1 antibodies in urine: a brazilian study.

We evaluated, for the first time in Latin America, the performance of a commercial enzyme immunoassay (EIA) (Calypte Biomedical Corporation, Berkeley, Calif.) that detects human immunodeficiency virus type 1 (HIV-1)-specific antibodies in urine in comparison to standard serological assays (two commercial EIAs and a commercial Western blot [WB] assay). Paired serum and urine specimens were collected from two different groups of Brazilian patients: 225 drug users with unknown HIV status who attended drug treatment centers in Rio de Janeiro, Brazil, and 135 subjects with known HIV status. Patients showing positive results in the serum EIAs and/or in the urine EIA were serologically confirmed by WB assay. For 135 individuals with known HIV status, the urine EIA showed 100% sensitivity (74 positive samples) and 95.1% specificity (58 of 61 negative specimens). For 225 drug users, the test showed 100% sensitivity (2 positive samples) and 98.7% specificity (220 of 223 negative samples) compared to WB-confirmed serological EIA results. Thus, in a total of 360 samples, the urine EIA correctly identified all 76 HIV-positive samples and 278 of 284 negative samples (100% sensitivity and 97.9% specificity). Detailed analysis of the urine EIA results indicates that an increase of the recommended cutoff value might raise the specificity of the assay without affecting its sensitivity. Our results suggest that the HIV-1 urine EIA is a good screening test suitable for developing countries like Brazil. However, as for all other HIV screening tests on the market, it is not specific enough to be used as a one-step test and therefore requires confirmation.

AIDS Serodiagnosis↗
PubMed1997

Glare sensitivity and visual acuity after excimer laser photorefractive keratectomy for myopia.

BACKGROUND: Following excimer laser photorefractive keratectomy (PRK), an increase in glare sensitivity and a reduction in contrast sensitivity can occur owing to changes in the cornea (structure and topography). In this study, an attempt was made to quantify and document objectively a change in those subjective perceptual factors. METHODS: Snellen visual acuity and disability glare were measured with the Berkeley glare test preoperatively as well as 1, 3, 6, 9, and 12 months postoperatively, after excimer laser photorefractive keratectomy (PRK) on 32 myopic patients (46 eyes). During the postoperative progress checks, haze was graded and contrast sensitivity was measured with the Vistech chart. All the data were statistically analysed by multiple regression. RESULTS: One year after PRK, a reduction in visual acuity (VA) measured with the low acuity contrast chart (10%) with and without glare could still be found, despite the fact that acuity measurements with a high contrast Snellen chart showed the same VA 6 months postoperatively as well as before the treatment. The lowest VA could be measured 1 month postoperatively; thereafter, the acuity increased despite the increase in haze that occurred during the first 3 months. CONCLUSION: Disability glare and a reduction in contrast sensitivity could be observed in most patients after PRK treatment with the Meditec laser system with its scanning slit. The future will show if new technology and a broader flattening area of 6 to 7 mm can minimise these postoperative complications.

Adult↗
PubMed2003

Construction of a cDNA-based microarray for Drosophila melanogaster: a comparison of gene transcription profiles from SL2 and Kc167 cells.

We have constructed a DNA microarray that represents approximately 6900 of the estimated 13,598 genes in the Drosophila melanogaster genome. The microarray contains 5756 target cDNAs from the Berkeley Drosophila Genome Project, 1078 cDNAs from the National Institutes of Health Drosophila testis cDNA library, and 546 gene fragments that were amplified from genomic DNA. The methods for DNA amplification and microarray manufacture are presented. Academic researchers can obtain the microarray from the Canadian Drosophila Microarray Centre. To evaluate the utility of these arrays, we compared the gene transcription profiles of two commonly used Drosophila cell lines. Analysis revealed that 5412 spot pairs gave signals consistently above the average background in Kc167 cells, whereas 5636 spot pairs met this criterion in SL2 cells. When the expression profiles of the cell lines were compared, 1437 genes displayed at least a 1.5-fold difference, and 170 genes had a threefold or greater difference between the two cell lines. In each case, with respect to Kc167 when compared with SL2 cells, the number of genes that were upregulated was nearly equal to the number of downregulated genes. This result demonstrates that despite the similar embryonic derivation of both cell lines, their transcriptional profiles are very different.

Animals↗
PubMed1998

Lethal P-lacZ insertion lines expressed during pattern respecification in the imaginal discs of Drosophila.

The imaginal discs of Drosophila are a useful experimental system in which we can study the origin and genetic determination of spatial patterns in development. This involves the separation of the disc-cell population into distinct lineage compartments, based on clonally transmitted expression states of a number of known selector genes. However, these commitments can be abrogated and the compartment boundaries redeployed, when repatterning occurs in cultured disc fragments. This has so far only been explained using the idea of positional information. The genetic basis of this property of the imaginal disc system and its relationship to compartments have not been identified. Here we have screened over 470 recessive lethal P-lacZ enhancer-trap insertions from the Berkeley Drosophila Genome Project for expression after cell death, which initiates pattern respecification in the imaginal discs. The positive lines obtained identify essential genes that may be important for pattern formation. Most show patterned imaginal disc expression, and many have maternal or zygotic effects on embryonic development. One is an allele of schnurri, a gene that encodes a component of the decapentaplegic (dpp) signal transduction pathway used for positional signalling in the embryo and in imaginal discs.

Animals↗
PubMed1981

Helical, motile mycoplasmas associated with flowers and honey bees in California.

Spiroplasmas were cultured from nonsurface-sterilized flowers of magnolia tree (Magnolia grandiflora L.) and tulip tree (Liriodendron tulipfera L.) in Alameda, Solano, and Yolo counties in California. Spiroplasmas were also isolated from honey bees (Apis mellifera L.) collected in the vicinity of Davis and Berkeley, CA. Most of the isolates grew relatively slowly at 31 or 37 degrees C reaching maximum population at 31 degrees C in 8-10 days. The flower isolates were serologically indistinguishable by deformation and growth inhibition tests of spiroplasma strain AS-576 from honey bee from Maryland. Isolates from honey bees were serologically closely related to spiroplasma strain SE-3 from tulip tree flower from Connecticut.

Bees↗
PubMed1993

Designing a connectionist network supercomputer.

This paper describes an effort at UC Berkeley and the International Computer Science Institute to develop a supercomputer for artificial neural network applications. Our perspective has been strongly influenced by earlier experiences with the construction and use of a simpler machine. In particular, we have observed Amdahl's Law in action in our designs and those of others. These observations inspire attention to many factors beyond fast multiply-accumulate arithmetic. We describe a number of these factors along with rough expressions for their influence and then give the applications targets, machine goals and the system architecture for the machine we are currently designing.

Algorithms↗
PubMed2000

Still looking for the Ivory Tower.

Following graduate training, which was disrupted by my changing schools and serving in the Navy in World War II, I arrived in Berkeley in 1948 as an instructor in the Biochemistry Department. Despite numerous academic reorganizations and a host of struggles over the University-imposed Loyalty Oath, dismissal of a faculty member because of political affiliations, free speech for students, and my resistance to mandatory retirement, I survived with the help of great graduate students, postdoctoral fellows, undergraduates, superb research assistants, and a supportive wife. Studies on structure of tobacco mosaic virus led to our investigating an ultracentrifuge anomaly and the construction of a synthetic boundary cell. In turn, this resulted in about 15 years of research on the ultracentrifuge and its application to the study of biological macromolecules. Among the latter, the discovery of large ribonucleoprotein complexes, now known as ribosomes, and chromatophores in photosynthetic microorganisms attracted the most attention. But it was the development of the photoelectric absorption optical system and the incorporation of the Rayleigh interferometer onto the ultracentrifuge that had the greatest impact on our further research. These tools, when applied to our initial research on E. coli aspartate transcarbamoylase (ATCase), led to the discovery of distinct subunits for catalysis and regulation and the global conformational change in the enzyme associated with its role in regulation. For almost 35 years we have been using the techniques of protein chemistry and molecular biology in studies of structural and conformational changes in the enzyme, the genes encoding the different polypeptides, subunit interactions, and assembly of the enzyme from six catalytic and six regulatory chains. Hybrids constructed from inactive mutants were used to demonstrate shared active sites requiring the joint participation of amino acid residues from adjoining polypeptide chains. ATCase is still being studied as a model for understanding allostery as a regulatory mechanism. Circularly permuted polypeptide chains are being used to study the folding and assembly pathways, and the recently determined crystal structure of the active nonallosteric catalytic subunit has led to new questions regarding the activated form of ATCase.

Aspartate Carbamoyltransferase↗
PubMed2001

Discoveries of vitamin B12 and selenium enzymes.

My undergraduate education at Cornell University was followed by graduate studies on methane fermentations under the guidance of H.A. Barker at the University of California, Berkeley. My Ph.D. degree was granted in June 1949. Two anaerobic microorganisms isolated from the mud flats of San Francisco Bay served as sources of biochemical research material for later studies at the National Institutes of Health in Bethesda. These organisms, Methanococcus vannielii and Clostridium sticklandii, proved to be especially rich sources of selenium-dependent enzymes and seleno-tRNAs. New B12 coenzyme-dependent enzymes that catalyzed intermediate steps in the anaerobic conversion of lysine to fatty acids and ammonia were isolated from C. sticklandii and characterized. My research efforts since 1970 have dealt primarily with various aspects of selenium biochemistry. We have shown that selenium is an essential constituent of several enzymes in prokaryotes. Se is present in these either as a selenocysteine residue in the protein or alternatively, in a few molybdoenzymes, as a component of a bound cofactor. Recent studies with a human adenocarcinoma cell line led to the unexpected discovery that selenocysteine occurs in mammalian thioredoxin reductase. The selenium located in a redox center of this enzyme is essential for catalytic activity.

Biochemistry↗
PubMed2005

Werner Goldsmith: life and work (1924-2003).

Werner Goldsmith, one of the foremost authorities on the mechanics of impact and the biomechanics of head and neck injuries, died peacefully at home in Oakland, California, on August 23, 2003, at age 79 after a short, courageous battle with leukemia, ending a long and very distinguished career in mechanics, dynamics, and biomechanics, and an almost six-decades-long association with the University of California, Berkeley. He was one of the pioneering, eminent solid and fluid mechanicians who made an early transition to biomechanics, and in rising to equal distinction in their new fields, added great credibility to biomechanics as a discipline in its own right. He was also a distinguished and influential figure in bioengineering education at his own institution, and, more broadly, in the United States and abroad. An emeritus professor for over a decade, he continued to be active in research and teaching until the very last days of his life.

Biomedical Engineering↗
PubMed2007

The professional development of an entomologist.

An account of the development of biological interest, and specifically interest in bees, by Charles D. Michener. Included topics are the role of graduate students and the relationship between behavioral studies and systematics. Sections are (a) upbringing, including initiation of biological interests, (b) early studies of bees, (c) student work at the University of California, Berkeley, (d) work at the American Museum of Natural History and in the U.S. Army, and (e) work at the University of Kansas, especially wild bee behavior and bee systematics.

Animals↗
PubMed2004

On becoming a nutritional biochemist.

Much of the science underlying nutrition has come from biochemical studies. This certainly is true in our understanding of the metabolism and function of such micronutrient cofactors as vitamins and metal ions. My own interest stems from an early desire to understand the molecular events in an organism and ultimately to know the fate of those nutrients that are needed to maintain life. My training in chemistry, biochemistry, and nutrition was helpful in gaining knowledge about the interface among these disciplines. My interests followed an understandable trail, beginning with those factors that cause plant galls and continuing through carbohydrate metabolism to vitamins. After all, from studying such pentitols as ribitol with Professor Touster at Vanderbilt University through indoctrination with enzymes, vitamins, and coenzymes with Professor Snell at the University of California-Berkeley, it was rational to begin my independent academic life investigating the enzymes that convert a ribityl-containing vitamin, namely riboflavin, to its operational flavocoenzymes. While at Cornell University, I encountered Professor Wright, who shared an interest in biotin. My realization that there was a similar need to determine the metabolism of lipoate followed logically. Interactions with inorganic chemists such as Professor Sigel at Basel University, as well as inorganic chemists at Cornell, led to an interest in metal ions. As summarized in this article, my colleagues and I are pleased to have contributed to both basic knowledge about cofactors and to have utilized much of this information in extensions to applications. Along the way, I have served by teaching, researching, and administrating at the universities that provided my positions in academe, and I have worked to share the load of numerous public and professional duties that are summarized herein. Altogether it has been an enjoyable career to be a nutritional biochemist. I recommend it for those who follow.

Biochemistry↗
PubMed2000

Fifty years in physical chemistry: homage to mentors, methods, and molecules.

A nostalgic account is given of my scientific odyssey, recalling early encounters, some fateful, some just fun, with mentors, methods, and molecules. These include stories of my student years at Stanford, pursuing chemical kinetics with Harold Johnston; graduate study at Harvard, doing molecular spectroscopy with Bright Wilson; and fledgling faculty years at Berkeley, launching molecular beam studies of reaction dynamics. A few vignettes from my "ever after " era on the Harvard faculty emphasize thematic motivations or methods inviting further exploration. An Appendix provides a concise listing of colleagues in research and the topics we have pursued.

Journal Article↗
PubMed2007

A spectroscopist's view of energy states, energy transfers, and chemical reactions.

This chapter describes a research career beginning at Berkeley in 1960, shortly after Sputnik and the invention of the laser. Following thesis work on vibrational spectroscopy and the chemical reactivity of small molecules, we studied vibrational energy transfers in my own lab. Collision-induced transfers among vibrations of a single molecule, from one molecule to another, and from vibration to rotation and translation were elucidated. My research group also studied the competition between vibrational relaxation and chemical reaction for potentially reactive collisions with one molecule vibrationally excited. Lasers were used to enrich isotopes by the excitation of a predissociative transition of a selected isotopomer. We also tested the hypotheses of transition-state theory for unimolecular reactions of ketene, formaldehyde, and formyl fluoride by (a) resolving individual molecular eigenstates above a dissociation threshold, (b) locating vibrational levels at the transition state, (c) observing quantum resonances in the barrier region for motion along a reaction coordinate, and (d) studying energy release to fragments.

Journal Article↗
PubMed1996

PLANT PATHOLOGY: a discipline at a crossroads.

The Department of Plant Pathology at the University of California at Berkeley was destroyed as a consequence of a contentious reorganization. The circumstances that led to the reorganization provide some insight into the challenges facing the discipline of plant pathology. The underlying basis for plant pathology as a science is to address problems of plant disease. This requires a balance between disciplinary and problem-solving research and a continuum from achieving fundamental advances in knowledge to the development and implementation of problem-solving approaches. Changes in colleges and universities have placed extreme stress on this essential structure. The dilemma that must be addressed is how to reestablish the problem-solving continuum where it has been broken and strengthen it where it has been weakened. Plants are essential for life, and they will always be affected by disease. The understanding and management of these diseases is the responsibility and the challenge of plant pathology today and in the future.

Journal Article↗
PubMed2005

Kenneth Frank Baker--pioneer leader in plant pathology.

Kenneth F. Baker (1908-1996) made major contributions to understanding diseases of ornamental plants, seed pathology, soil-borne plant pathogens, biological control, and history of plant pathology. His work set the stage for the success of today's ornamentals and nursery industries. His leadership and writings created the scientific framework for research and teaching on soil-borne plant pathogens and biological control. After B.Sc. and Ph.D. degrees from Washington State University in 1930 and 1934, respectively, and one year as a National Research Council Fellow with B.M. Dugger at Wisconsin, he took jobs in 1935 with the U.S. Department of Agriculture in Nebraska on establishment of shelter belts and 1936-39 with the Pineapple Producers Cooperative Association in Hawaii. He worked on diseases of ornamental plants at the University of California, Los Angeles, starting in 1939, moving to Berkeley in 1961 when the UCLA program closed. He retired in 1975 and moved to Corvallis, OR, as Emeritus Professor, Oregon State University, and Collaborator, U.S. Department of Agriculture, Agricultural Research Service. He spent four sabbatical leaves in Australia, and was elected fellow of the American Association for the Advancement of Science in 1950, fellow of the American Phytopathological Society in 1969, and the Horticultural Hall of Fame in 1976.

Botany↗
PubMed1994

Expression of intestinal fatty acid binding protein in intestinal epithelial cell lines, hBRIE 380 cells.

Intestinal fatty acid binding protein (I-FABP) is a cytosolic protein present only in differentiated intestinal epithelial cells. Here we report on an intestinal cell culture system expressing I-FABP during cell differentiation and the modulation of expression by extracellular factors. An I-FABP-expressing cell line (hBRIE 380i) was generated from Berkeley rat intestinal epithelial cells (hBRIE 380). Time- and substratum-dependent changes in I-FABP mRNA expression were paralleled by changes in protein levels. Induction of I-FABP levels observed on collagen type I gels in the presence of limiting serum was prevented by insulin. When cells were grown on collagen gels containing fibronectin and laminin, a stimulation of ultrastructural characteristics of cell differentiation was observed with no further induction of I-FABP expression. The data show that I-FABP expression is limited to a differentiated population of hBRIE 380i cells and that the expression can be regulated by factors present in the extracellular matrix as well as involved in regulation of replication or metabolic state of the cell.

Animals↗