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A survey of weighing performance in clinical biochemistry laboratories.

Results of a survey of accuracy and precision of weighing in a sample of clinical biochemistry laboratories in the U.K. are reported. 101 laboratories each carried out eight weighings. 94% of weighings were subject to errors of not more than 1.7 mg at the 2 g level and not more than 1.0 mg at the 100 mg level. However, 9% of the laboratories produced results which were consistently subject to larger errors.

Chemistry, Clinical↗

Biochemistry of Alzheimer's disease amyloid plaques.

One of the principal identifying features of Alzheimer's disease (AD) is the extracellular deposition of fibrous protein aggregates in the form of amyloid plaques. The major component of these deposits is the amyloid beta (A beta) protein that is a proteolytic fragment of the integral membrane amyloid precursor protein (APP). Understanding the pathways responsible for A beta formation and the mechanism by which it accumulates within the brain could provide key answers to AD pathogenesis. This review will explore the biochemistry of A beta and its precursor, the possible causal relationship between amyloid and AD-associated neuronal death, the role of additional cellular elements in amyloid formation, and the potential application of these components in clinical diagnosis.

Alzheimer Disease↗

An off-line data processing system for biochemistry profiling based on a 2K programmable calculator.

An off-line data processing system based on a Hewlett Packard 2K programmable calculator to be used with a biochemistry profiling system is described. The program is in two sections. A Data Acquisition phase calculates results from Auto Analyser II peak heights after corrections for drift and stores them on magnetic tape cassettes. Quality control statistics are produced. A Reporting phase types the profile results on self-adhesive pre-printed labels to be attached to the test-request form and also prepares a laboratory record sheet. The system is routinely used to process up to 2000 peak heights per day. Non-profile heights may also be read using this program.

Autoanalysis↗

A survey of the state of the art of clinical biochemistry laboratory computerisation.

This paper presents the results of a survey which was recently carried out in order to clarify the current 'state of the art' regarding the use of computers in hospital biochemistry laboratories. Information was obtained by means of a questionnaire which was mailed to a sample of United Kingdom hospital laboratories. The results obtained from the analysis of the data from the questionnaire replies are presented, and conclusions are drawn regarding the implications of hospital laboratory computerisation.

Chemistry, Clinical↗

Ancient biochemistries and the evolution of parasites.

The characteristic respiratory metabolism of parasites consists of fermentation to carbon-rich, highly reduced volatile fatty acids which are excreted, and electron transport systems emphasising fumarate reductase and b-type cytochromes. The taxonomic groups that contribute major parasites (the heterogeneous protozoa and the helminths) have their evolutionary origins in environments from which oxygen was absent or present in very low concentrations. The Ediacarian period, about 700 million years ago, contains fossils of the appropriate grade of organisation to be contemporaneous with the ancestors of platyhelminths, nematodes and acanthocephalans. With the oxygen transition, carbon flow in the biosphere resulted in conservative, anoxic environments together with oxygen rich ones. The organisms of the former retained their emphasis on anaerobic energy generation, while cytochrome systems were as much concerned with oxygen detoxification as energy generation. Metabolic pathways in the modern parasitic groups are echoes of such ancient biochemistries.

Anaerobiosis↗

VisiCalc and VisiPlot software routines and the analysis of data routinely encountered in steroid biochemistry.

The use of VisiCalc and VisiPlot software routines for performing calculations and graphing of data commonly encountered in steroid biochemistry is described. These software routines have utility and are relatively easy to use, requiring little or no programming experience. Use of these routines is demonstrated in terms of data processing associated with chromatography of receptor preparations and equilibrium binding analyses. The execution of these software routines is rapid and can result in a considerable savings of time and personnel. These and other generically similar software routines should have the greatest utility in laboratories where the experimental design is subject to on-going change.

Animals↗

Effects of cycloheximide, a protein synthesis inhibitor, on mouse brain catecholamine biochemistry.

Cycloheximide (CXM), a protein synthesis inhibitor, has been shown to result in a marked inhibition of central catecholamine (CA) synthetic mechanisms at doses that cause amnesia in animals. Unlike other inhibitors of CA synthesis no significant depletion of whole brain NE or DA concentrations was observed 0.75, 1, 2, 3, 4, 6, 17, or 24 hours after administration of CXM (120 mg/kg) to C57BL/6J mice. In order to investigate the underlying basis of maintenance of CA levels in face of CA synthesis inhibition, the effects of CXM on in vitro release of 3H-NE was studied in mouse hypothalamic slices. CXM, in a dose related manner, significantly inhibited the potassium stimulated release of NE from hypothalamic slices. Anisomycin, another protein synthesis inhibitor, similarly inhibited NE release. These studies further document the effects of protein synthesis inhibitors on CA mechanisms and suggest that disruption of CA biochemistry may play a role in the amnesia observed after administration of protein synthesis inhibitors.

Animals↗

Antitumor activity and toxicity of peroxo heteroligand vanadates(V) in relation to biochemistry of vanadium.

A selected set of 14 V(V) complexes was tested for toxicity and antitumor activity against L1210 murine leukemia, to examine the biological properties of peroxoheteroligand vanadates(V) of the formula (NH4)4[O(VO(O2)2)2], M3I[VO(O2)2C2O4], and MI[VO(O2)L], L = malate, citrate, iminodiacetate, nitrilotriacetate, and EDTA. The x-ray structure is known for five of these compounds. A relationship has been found between the chemical composition and the biological activity (antitumor activity-toxicity) of these complexes. Activity in the L1210 system is defined as greater than or equal to 25% increase in life span, and this was seen with (NH4)4[O(VO(O2)2)2]; M3[VO(O2)2(C2O4)]2H2O, M = K, NH4; and NH4[VO(O2)Malato]H2O. These observations are important for the biochemistry of vanadium. The special nature of electron transfer within the V(V)-peroxo moiety is proposed to be responsible for this phenomenon. Peroxo heteroligand vanadates(V) therefore represent a model system for studying some biochemical interactions of vanadium in living matter.

Animals↗

Biochemistry and genetics of monoamine oxidase.

This chapter reviews the two mitochondrial flavin containing isozymes of monoamine oxidase. Section 1, "Biochemistry" discusses assays, substrates and inhibitors, phylogenic and tissue distribution, interactions with lipids, nutritional studies, protein structure, kinetic and chemical mechanistic proposals, and biosynthesis. Section 2, "Inheritance" discusses possible genes involved in expression, genetic studies of platelet MAO-B and fibroblast MAO-A, and chromosomal location. Section 3, "Molecular Genetics" reviews the cloning of their cDNAs, their intra- and interspecies homology and structural inferences made from deduced amino acid sequences. Section 4, "Regulation" gives an overview of levels in development and aging, and effect of drugs. The final section 5, "Role in Human Disease" discusses physiological function and effects of altered levels in humans and animal models including complete absence due to a submicroscopic chromosomal deletion in several human patients.

Amino Acid Sequence↗

The biochemistry and toxicology of benzoic acid metabolism and its relationship to the elimination of waste nitrogen.

Detoxification of sodium benzoate by elimination as a conjugate with glycine, a nonessential amino acid, provides a pathway for the disposal of waste nitrogen. Since 1979, sodium benzoate has been widely used in the therapeutic regimen to combat ammonia toxicity in patients born with genetic defects in the urea cycle. Although the clinical use of benzoate is associated with improved outcome, the search for biochemical evidence in support of the rationale for benzoate therapy has produced conflicting results. This review begins with an historical account leading to elucidation of the biochemistry of benzoate detoxification and early work indicating the potential utility of the pathway for elimination of waste nitrogen. An introduction to contemporary efforts at employing benzoate to treat hyperammonemia is followed by a detailed review of studies on benzoate metabolism and resultant toxic interactions with other major metabolic pathways. With this background, the several metabolic routes by which benzoate is thought to promote the disposal of waste nitrogen are then examined, followed by a consideration of alternative mechanisms by which benzoate might combat ammonia toxicity.

Ammonia↗

Molecular biology and biochemistry of the endothelins.

Endothelin-1 (ET-1), the first member of the newly discovered mammalian endothelin family of biologically active peptides, was originally identified as a 21 residue potent vasoconstrictor peptide in vascular endothelial cells. However, it has since been demonstrated to possess a wide variety of pharmacological activities in tissues both within and outside the cardiovascular system, and peptides with a striking similarity to ET-1 have been found to be the major toxic component of a snake venom. Moreover, recent studies have suggested that mammals including humans produce three distinct members of this peptide family, ET-1, ET-2 and ET-3, which may have different profiles of biological activity, and may act on distinct subtypes of endothelin receptor. Masashi Yanagisawa and Tomoh Masaki review the current status of the biochemistry and molecular biology of endothelin.

Amino Acid Sequence↗

A new in vitro model for studies of pancreatic polypeptide secretion and biochemistry.

A new model tissue (pseudoislet) is described for studies of pancreatic polypeptide (PP) secretion and biochemistry. It consists of islet-like aggregates of canine pancreatic endocrine cells which are formed and maintained on tissue culture. Immunocytochemical staining revealed that pseudoislets prepared from the duodenal end of the pancreas contained a predominance (40-60%) of F cells (the PP secreting cell). Also present were 10-25% exocrine cells and an equal proportion of A, B and D cells. Several studies were conducted to characterize the pseudoislets' capacity to secrete PP. Basal rates of PP release and the concentration of PP per pseudoislet remained constant during four weeks of culture. Stimulation at weekly intervals by carbachol (0.1 mM) resulted in a stable secretory rate for 2 weeks, that declined progressively at weeks 3 and 4. When studied in a perfusion system, carbachol-stimulated PP release occurred in a biphasic pattern, similar to the well-recognized biphasic release of insulin from perifused rat islets. Dose-response curves of four cholinergic agonists revealed clear differences in secretagogue activity. Acetylcholine and methacholine were found to be equipotent, followed in order of potency by carbachol and bethanechol. These histologic and secretory data show that canine pseudoislets are healthy tissues composed of a high proportion of F cells which secrete PP in response to cholinergic stimulation. The data suggest that the cultured canine pseudoislet model provides an excellent system useful in studies of PP secretion and biosynthesis.

Animals↗

Nitrogen sparing effect of Ornicetil in the immediate postoperative state clinical biochemistry and nitrogen balance.

The salt complex of alpha-ketoglutarate and ornithine, L(+)ornithine alpha-ketoglutarate - ORNICETIL (OR) - is able to bind six amino groups per molecule without enzymatic intervention. The present study was undertaken to determine whether intravenous administration of OR together with total parenteral nutrition (TPN) has a beneficial effect on nitrogen utilization in the immediate postoperative phase. Thirteen patients were investigated after major abdominal operations (resection of colon or rectum). All patients received TPN for 5 days postoperatively. Energy (165 kJ/kg BW) was given as fat (Intralipid 20%) and carbohydrate (Glucose 20%). Seven patients (controls) received 0.15 g amino acid (AA)-N/kg BW (Vamin). Six patients had an isonitrogenous regimen but with 2.5 g AA-N being replaced by Ornicetil (OR group). The excretion of urea, creatinine, ammonia, 3-methyl-histidine (3-MeHis) and total-N was determined throughout the study and the daily nitrogen balance was calculated. Blood samples were drawn serially before and after surgery for routine clinical biochemistry. The day-to-day nitrogen balance was significantly better when OR was given. Urea excretion was significantly reduced, and the urinary ammonia losses in the OR group were one third of those in the control group. In the control group 3-MeHis correlated negatively with the nitrogen balance. The regression line obtained, y = 265 - 21.6 x (p < 001), and the calculated correlation coefficient, r = 0.87 (p < 0.001), were highly significant. In contrast, no correlation could be demonstrated between 3-MeHis output and nitrogen balance in the OR group (r = 0.18, N.S.). The results indicate better postoperative nitrogen economy in the OR group than in the control group. Stimulation of insulin and growth hormone secretion may be contributing factors in the better nitrogen utilization. The increased ammonia excretion postoperatively in the control group was completely abolished when OR was given simultaneously with decreased urea formation, suggesting a product inhibition of arginase in the liver cytosol and also indicating that amino groups generated by the enhanced gluconeogenesis were trapped by OR owing to stimulated transamination in peripheral muscle tissues. The significant negative correlation between 3-MeHis excretion and nitrogen balance in the control group strongly indicates a correlation between net protein catabolism and increased postoperative muscle protein breakdown. In contrast, the total absence of correlation between nitrogen balance and 3-MeHis excretion in the OR group suggests a diminished (or zero) net muscle protein breakdown.

Journal Article↗

The toxicity of T-2 toxin in swine following topical application. II. Effects on hematology, serum biochemistry, and immune response.

T-2 toxin at 0 (6 pigs) or 15 mg/kg (8 pigs) in 0.75 ml of dimethyl sulfoxide was topically applied to 9- to 10-week-old, male castrated, specific-pathogen-free derived pigs which were immunized subcutaneously with sheep red blood cells (SRBC) on Days 0 and 21. Whole blood and serum samples were taken periodically for clinical pathologic and immunologic evaluations. The pigs were observed daily and weighed weekly; their rectal temperatures were measured periodically. The T-2-treated pigs displayed anorexia, lethargy, posterior weakness and paresis, persistent high fever, and reduced body weight gain. Prominent neutrophilia, decreased serum glucose, albumin, and alkaline phosphatase activity, and increased serum globulin were seen in the T-2-treated group. The responses of enriched peripheral blood mononuclear cells to mitogens concanavalin A, phytohemagglutinin, and pokeweed mitogen of the T-2-treated group were significantly lower than those of the control group both at early (3 to 5 days) and late (20 to 28 days) postdosing intervals. No significant effects were noted in the hemagglutination titer to SRBC. Thus, in addition to the severe local dermal injury reported previously, topical exposure of swine to a sublethal dose of T-2 toxin, 15 mg/kg, can cause significant systemic effects on parameters such as body weight gain, rectal temperature, hematology, serum biochemistry, and cellular immune response.

Administration, Topical↗

Normal cartilage structure, biochemistry, and metabolism: a review of the literature.

PURPOSE: To understand the possible significance of the presence of proteases, cytokines, growth factors, and arachidonic acid metabolites in the osteoarthritic temporomandibular joint (TMJ), a review of the normal physiologic processes and participating factors in the normal TMJ is established, based on knowledge of structure, biochemistry and metabolism of normal cartilage in general.

Arachidonic Acid↗

The interplay between X-ray crystallography, neutron diffraction, image reconstruction, organo-metallic chemistry and biochemistry in structural studies of ribosomes.

Crystals of ribosomes, their complexes with components of protein biosynthesis, their natural, mutated and modified subunits, have been subjected to X-ray and neutron crystallographic analyses. Electron microscopy and 3-dimensional image reconstruction, supported by biochemistry, genetic, functional and organo-metallic studies were employed for facilitating phasing of the crystallographic data. For example, a monofunctional multi heavy-atom cluster (undecagold) was designed for covalent and quantitative binding to ribosomes. The modified particles were crystallized isomorphously with the native ones. Their difference-Patterson maps contain indications for the usefulness of these derivatives for subsequent phasing. Models of the ribosome and its large subunit were reconstructed from tilt series of 2-dimensional sheets. The comparison of the various reconstructed images enabled an initial assessment of the reliability of these models and led to tentative assignments of several functional features. These include the presumed sites for binding mRNA and for codon-anticodon interactions, the path taken by the nascent protein chain and the mode for tRNA binding to ribosomes. These assignments assisted in the design of biologically meaningful crystal systems. The reconstructed models are being used to identify structural features in initial density maps derived from X-ray and neutron diffraction data.

Crystallography↗

Nutrition and biochemistry of anaerobic Chytridiomycetes.

The nutrition and biochemistry of anaerobic Chytridiomycetes is at present poorly understood. Data has been obtained principally from studies of rumen isolates of Neocallimastix spp. grown in vitro. Our knowledge of the nutrition of Neocallimastix is summarised. Current information on glycolysis and fermentation product generation via cystosolic and hydrogenosomal systems, production of enzymes involved in plant cell wall hydrolysis, lipid metabolism and the role of Chytridiomycetes in ruminal proteolysis is discussed. At present this is insufficient to provide useful phylogenetic information.

Anaerobiosis↗

Biochemistry of the nematode cuticle: relevance to parasitic nematodes of livestock.

The cuticle of nematodes is a thin, flexible outer covering composed primarily of protein with trace amounts of lipid and carbohydrate. There has been considerable recent interest in the biochemistry, immunology and molecular biology of the cuticle of parasitic nematodes because of its role as an interface between parasite and host. The cuticle consists of: (1) collagen-like proteins that form the medial and basal layers; (2) non-collagen proteins that form the epicuticular and external cortical regions; (3) non-structural proteins associated with the external surface. The collagen-like proteins are solubilized by reducing agents, have molecular weights of 30-120 kDa and exhibit stage and species variations. Nematode collagen genes, however, code only for proteins with molecular weights of 30 kDa. The non-collagenous proteins, referred to as cuticlin, exhibit unusual chemical properties as indicated by their resistance to solubilization even under strongly denaturing conditions. Recent studies of Ascaris suum have demonstrated the presence of tyrosine-derived cross-links, dityrosine and isotrityrosine, that may form the linkage between subunits in assemblage of the collagenous and noncollagenous structural components of the cuticle. A peroxidase enzyme has been implicated in the synthesis of these cross-links. Recent 125I labeling studies of Haemonchus contortus have identified and characterized stage-specific proteins on the cuticular surface.

Animals↗