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Chromatographic fractions obtained from Phyllanthus amarus were tested for toxicity on the serum biochemistry of rats. The results revealed that some fractions of P. amarus had potentially deleterious effects on the blood and therefore caution should be exercised in the use of P. amarus as a medicinal plant.
Abnormalities of the p53 tumor suppressor gene are the single most common molecular abnormality seen in human cancer. Considerable evidence indicates that the product of this gene has critical roles in coordinating the response of cells to a diverse range of environmental stresses. At present, there is a gamut of biochemical properties and interactions ascribed to p53, but the in vivo physiological relevance of many of these remains uncertain. The development of clinical applications and novel therapeutic strategies utilizing our knowledge of p53 is contingent upon bridging the gap between rigorous biochemistry and holistic in vivo studies.
The newly introduced sulfhydryl reductant tris(2-carboxyethyl)phosphine (TCEP) is a potentially attractive alternative to commonly used dithiothreitol (DTT). We compare properties of DTT and TCEP important in protein biochemistry, using the motor enzyme myosin as an example protein. The reductants equally preserve myosin's enzymatic activity, which is sensitive to sulfhydryl oxidation. When labeling with extrinsic probes, DTT inhibits maleimide attachment to myosin and must be removed before labeling. In contrast, maleimide attachment to myosin was achieved in the presence of TCEP, although with less efficiency than no reductant. Surprisingly, iodoacetamide attachment to myosin was nearly unaffected by either reductant at low (0.1 mM) concentrations. In electron paramagnetic resonance (EPR) spectroscopy utilizing nitroxide spin labels, TCEP is highly advantageous: spin labels are two to four times more stable in TCEP than DTT, thereby alleviating a long-standing problem in EPR. During protein purification, Ni(2+) concentrations contaminating proteins eluted from Ni(2+) affinity columns cause rapid oxidation of DTT without affecting TCEP. For long-term storage of proteins, TCEP is significantly more stable than DTT without metal chelates such as EGTA in the buffer, whereas DTT is more stable if metal chelates are present. Thus TCEP has advantages over DTT, although the choice of reductant is application specific.
Sunfish were collected from a fly ash pond-receiving stream and an Ohio River reference site to assess biochemical responses to coal ash effluent exposure. Selenium levels in sunfish from the receiving stream were higher than toxic thresholds associated with adverse population effects and reproductive impairment. Tissue biochemistry was found to be indicative of metal exposure and effect, but varied widely. Liver glycogen was positively correlated with increased liver metal levels, indicating no adverse effect upon stored carbohydrate levels. Lipid levels decreased with increasing metals, indicating possible nutritional stress. Protein levels increased with increasing metal levels, possibly due to the synthesis of proteins to sequester the metals. ATPase, dUTPase, and alkaline phosphatase activity generally decreased with exposure to ash pond metals, but remained within normal physiological ranges. Fish condition factors and liver somatic indices were correlated with liver lipid levels, dUTPase activity, and gill ATPase and alkaline phosphatase activity. Exposure to coal ash effluents produced biochemical markers of exposure that were associated with fish condition indicators; however, the indices themselves were not significantly affected by effluent exposure.
The Chediak-Higashi syndrome (CHS) is an inherited disorder of humans and of several animal species, characterized by partial albinism, pseudohemophilia, increased susceptibility to disease, and large inclusions in all granule-forming cells. In this study, various parameters of adenine nucleotide biochemistry were examined in beige mouse kidney tissue and in peripheral blood leukocytes from CHS mink. There were no differences in the total protein content, total ATPase activity or the magnesium (Mg2+) ATPase or the sodium-potassium (Na(+)-K+) ATPase activities, the concentrations of ATP, ADP, and AMP, or the adenylate energy charge (AEC) in kidney extracts from beige and normal mice. In studies of leukocytes, there were no differences in the concentrations of ATP, ADP, AMP, and cAMP or the AECs in total leukocyte preparations and in extracts from granulocytes or nongranulocytes. These results can be explained by any one of several hypotheses: no storage pool of adenine nucleotides exists in the tissues examined; or the alleged storage pool is not affected by CHS; or the quantity of nucleotides in the alleged storage pool is too minute to be evaluated by current techniques; or the CHS defect might cause a shift from the storage pool to the metabolic pool.
The genes that encode immunoglobulin and T cell receptor proteins are assembled from component gene segments in a reaction known as V(D)J recombination. The reaction, and its crucial mediators RAG1 and RAG2, are essential for lymphocyte development and hence for adaptive immunity. Here we consider the biochemistry of this reaction, focusing on the DNA transactions and the proteins involved. We discuss how the RAG proteins interact with DNA and how coordinate cleavage of the DNA at two sites might be achieved. Finally, we consider the RAG proteins and V(D)J recombination from an evolutionary point of view.
We have reviewed the biochemistry of the normal and warfarinized vitamin K-dependent coagulation proteins, both individually and as members of their respective macromolecular enzyme complexes. Much has been learned in the past 10-15 years about the molecular mechanisms of coagulation. However, we have only scratched the surface and are beset by a number of interesting challenges. Clearly, we must begin to dissect the other vitamin K-dependent macromolecular enzyme complexes as has been done for prothrombinase. Prothrombin differs in fundamental ways from the other vitamin K-dependent proteins and we can anticipate significant differences as well as similarities in the other complexes. The presence of potentially functional domains in the non-catalytic portions of the vitamin K-dependent proteins and their similarities within this family of proteins should prove a fruitful area of future research. Finally, the evaluation of warfarinized vitamin K-dependent proteins, both in fundamental studies with purified systems and using uniquely engineered immunoassays, should shed light on basic molecular mechanisms and modes of monitoring warfarin therapy.
In Solenopsis spp., muscle histolysis or breakdown is a normal process in females and is initiated in the flight muscles only immediately after a mating flight. Information regarding the presence of the oxyradical scavenging enzyme superoxide dismutase (SOD) and the formation of the radical oxygen intermediate superoxide (SO) during the early stages of flight muscle histolysis in this insect was investigated. In normal fibrillar flight muscles from control animals, SOD was immunolocalized to vesicular and tubular components of the sarcotubular system. Lanthanum tracer studies indicated that some of these SOD-positive structures might be tubulovesicles continuous with the extracellular space. Following the injection of virgin alates with experimental haemolymph obtained from artificially inseminated females, the membrane delimited elements of the sarcotubular system became increasingly swollen and dilated with time (from 60 to 120 minutes postinjection) with a concomitant decrease in SOD activity and an increase in oxyradical formation. Many similar vesicles were lanthanum-positive. SO was not seen in the sarcoplasmic vesicles and tubules of control insects. The biochemical quantification of SO release over a 2-hour period showed a marked increase in oxyradical formation following treatment with the experimental haemolymph in comparison to control insects. Also, the addition of superoxide dismutase depressed SO formation under these conditions. Despite the histochemical and biochemical changes seen in the muscles of experimental insects, by 2 hours post-treatment there was no evidence of muscle necrosis. From these studies on flight muscle histolysis/necrosis in Solenopsis it appears that the formation of oxyradicals might represent an early event in myopathogenesis and subsequent tissue involution. The generation of SO is more than likely to be associated with alterations in the normal structure, biochemistry and permeability of the biomembranes which delimit the sarcotubular system.
During a subchronic toxicity and reproduction study with tri-n-butyltin oxide (TBTO) concentrations of 0, 24, 60, and 150 mg/kg diet in Japanese quail, preliminary data on hematology and serum biochemistry were obtained. The absence of serious effects in blood parameters in both adult quail and developing chicks are discussed in view of the adverse effects of TBTO on reproduction.
A complex stimulation regimen (visual, auditory, and somesthetic-kinesthetic with forced movements, 30 times for 30 min each within 14 days) increased significantly the amplitudes of visual cortical evoked potentials (EPs) in adult rats if applied during the second postnatal fortnight. The EP increase after stimulation during the first 14 days after birth was not significant. Visual stimulation alone was compared with complex stimulation (visual plus forced movements) during the 2nd postnatal fortnight. More specific local changes in the visual cortex were revealed in brain biochemistry (lower DNA concentration, more RNA and protein per cell) and cortical electrogenesis (enhanced visual EPs) after visual stimulation alone, whereas complex stimulation induced more diffuse changes and rather profoundly influenced higher nervous functions (viz., memory retrieval - improved 24-h). Involvement of both specific and nonspecific mechanisms in the aftereffects of early stimulation is indicated.
The dietary intakes of 88 renal stone cases and 88 age and sex matched controls were assessed by dietary history using a standardised questionnaire. The stone cases were divided into six subgroups established on the basis of urine biochemistry (calcium, oxalate and uric acid) and stone composition. The average intake of each group was then compared with that of their controls using standard statistical procedures. Cases with idiopathic calcium oxalate stones had significantly lower intakes of dietary fibre, non-cellulose polysaccharide, phytate, magnesium, phosphate and thiamine than controls. No significant difference in dietary intake was found between cases with high urinary calcium and uric acid and their respective controls. All cases with a high urinary oxalate had a significantly higher intake of vitamin C than controls. Our results support the belief that dietary intake is an important pre-urinary risk factor of idiopathic renal stone disease.
Ribozymes are a class of ribonucleic acid (RNA) molecules that possess enzymatic properties. Upon binding to complementary nucleic acid strands, catalytic degradation takes place via a cleavage reaction. In effect, inactivation of susceptible substrate RNA molecules takes place at a catalytic rate and with a high degree of substrate specificity. This article reviews the biology and biochemistry of this class of molecules and its potential applications in clinical medicine.
Some of the more interesting and important proteins are those that function by forming associations or complexes with other substances. The structure-function relationships of three of these with very different substances are transferrins, which chelate metal ions; avian ovomucoids, which form complexes with proteolytic enzymes; and antifreeze glycoproteins, which interact at the ice-solution interface. Interrelating studies on the comparative biochemistry with studies using chemical modification have helped identify the side-chain groups of the proteins involved in function as well as to be useful for studies on general protein chemistry. The most strongly associated interaction is the chelation of iron by transferrin, with an association constant of approximately 10(21); tyrosines, histidines, and sometimes aspartate are involved. For ovomucoids, individual substratelike residues such as lysine are involved in a Michaelis-like complex, and association constants are as high as 10(10). By contrast, the antifreeze glycoproteins appear to function by a polymeric interaction at the surface of ice, with a much weaker association.
Early lesions of arteriosclerosis are characterized by proliferating smooth muscle cells, macrophages,and foam cells. In addition, large amounts of connective tissue components and cholesterol esters are found. These changes are primarily located in the intima of the arterial wall. The initial mechanisms responsible for lesion formation are largely unknown. In recent years progress has been made particularly in fields of research related to the biochemistry of arterial wall cells in tissue culture. The findings obtained allow us to deepen our knowledge of the pathophysiology of arteriosclerosis. Of special interest are mechanisms involved in the maintenance of the thromboresistant endothelium, the factors triggering proliferation of intimal smooth muscle cells, and the transformation of macrophages to foam cells.
Haematology and blood biochemistry were monitored during the development and regression of psoroptic scabies in sheep. There were rises in numbers of neutrophils and eosinophils and in the fibrinogen concentrations, with lowered haemoglobin concentrations any lymphocyte numbers. The only biochemical parameters that were affected were the estimated serum globulin concentration, which rose during the disease process, and the serum albumin concentration, which fell. All of these changes reverted to normal soon after treatment.
There are several groups of animals that are adapted for extremely long duration fasting as part of their reproductive cycle. Penguins, bears and seals routinely fast without food or water for months at time. However, they do not 'starve', as the biochemical implications of starving are very different from those of successful fasting. There are distinct biochemical adaptations in lipid, carbohydrate and especially protein metabolism that allow these animals to survive. It appears, at least for penguins and seals, that the duration of the fast may be limited by changes that occur in biochemical regulation near the ned of the fast. In all of these species, the biochemistry of fasting and the ecological and behavioral demands of their breeding cycles are closely interrelated.
This article reviews several new developments in vanadium biochemistry, as elucidated from studies of ascidians. A hypothesis correlating ascidian blood cell function to anaerobiosis, via two prominent redox constituents, namely vanadium(III) and the tunichromes, a family of metal ion complexing/reducing hydroquinonoid peptides, is presented.
Our investigations have brought new aspects of the biochemistry of ascorbic acid to light: Ascorbic acid exceeds the functions of a vitamin, since it not only has its known cofactor roles for several enzymes, but also affects the regulation of the levels of the circulating thyroid and adrenal cortical hormones. In guinea-pigs the ability to detoxicate certain drugs, e.g. barbiturates, decreases with a minimal but not yet perilous supply of ascorbic acid. This symptom is connected with high blood levels of cortisol, which are probably also involved in the injuries to connective tissue known in scurvy. Guinea-pigs, which like man are dependent on ascorbic acid as an essential foodstuff, are able to adapt to high doses of ascorbic acid. Under these conditions they catabolize it at an increased rate. However, for a certain period after a sudden drop in the high dosage of ascorbic acid there is a danger that a hypovitaminotic, suboptimal metabolic state will develop. Oral and parenteral applications of ascorbic acid yield different results, since the organism limits the absorption of the physiological oral uptake. When this limit is exceeded, the liver in particular is unprotected and becomes swamped. The harmlessness of high doses of ascorbic acid probably holds true only in the case of oral uptake.