Biomedical subjects
Publications and source records attributed to C J Briggs.
The major toxin present in the dry seeds and seedlings of Lathyrus sativus is the neurotoxin 3-N-oxalyl-L-2,3-diaminopropanoic acid (beta-ODAP). The presence of one additional neurotoxin and an osteotoxin in the seedlings increases the overall toxicity. Isolation, purification, and detection of these toxins are described.
Chimeric mice provide a unique approach to the analysis of genetic factors associated with aging since cells with two genetically distinct backgrounds can be analyzed in the same animal. In this study, bone marrow chimeras were produced by reconstituting lethally irradiated female B6AF1 [(C57BL/6 female x A male)F1] mice with varying mixtures of T cell-depleted bone marrow cells from A (short-lived) and C57BL/6 (long-lived) mice. The phenotypic composition of the peripheral blood lymphocytes was analyzed using either a cytotoxicity assay or flow cytometry with indirect immunofluorescence. The percentage of A-derived lymphocytes in the peripheral blood following reconstitution was generally higher than the percentage of A bone marrow cells with which the irradiated mice were inoculated, suggesting that the cells from the A donor bone marrow were more efficient at marrow reconstitution than the cells from the C57BL/6 donor bone marrow. In order to determine whether the percentage of A- versus C57BL/6-derived cells changed with age in each animal, the chimeric mice were bled for phenotype analysis of peripheral blood lymphocytes between 2-6 months following reconstitution and at 2-3 month intervals until death. For most animals [93/127 (73%)], there was no consistent pattern of increase or decrease (> 20%) with regard to the percentage of A lymphocytes in the peripheral blood over time. However, in 34/127 (27%) of the chimeras, a change greater than 20% in the phenotypic composition of the peripheral blood lymphocytes was observed and these animals were considered unstable. Among these 34 unstable animals, 6 (18%) showed an overall increase in A-derived lymphocytes, 24 (71%) showed an overall decrease in A-derived lymphocytes, and 4 (12%) showed fluctuating increases and decreases over their lifespan. While the lifespans of the chimeric animals in these studies were considerably shorter than those reported for untreated mice of the same strain and gender, in these animals increased proportions of A cells were associated with significantly longer lifespans. In addition, the lifespan of the B6AF1 chimeric mice was a function of the proportion of A lymphocytes present in the peripheral blood over the course of the animal's life.
Molecules encoded by the major histocompatibility complex (MHC) are crucial for the proper functioning of the immune response. In this study, the levels of class I and class II major histocompatibility antigens on lymphocytes from strain A mice were measured as a function of age. Class I protein levels increased significantly on both peripheral blood and spleen (T cells and B cells) lymphocytes with age. This increase in MHC class I protein levels was accompanied by an increase in class I mRNA levels. On the other hand, class II protein levels did not show a significant change with age. Moreover, while the percentage of class I-expressing spleen lymphocytes stayed at a steady-state level of 100% with age, the percentage of class II-expressing spleen lymphocytes decreased from 85% in young animals to 70% in old animals. This decrease was due to a decrease in the relative proportion of B cells compared to T cells in the spleen lymphocyte population of old mice. When class II mRNA levels were measured, it was found that these levels decreased markedly with age. Overall, it is clear that the regulation of MHC class I and class II expression changes with age in A strain mice. Since optimal levels of MHC expression are crucial for the proper functioning of cellular and humoral immune responses, it will be most interesting to understand how the control of MHC gene expression changes with age and whether MHC gene expression can be modulated in old individuals to restore better immune function.
The pharmacokinetics of the bispyridinium oxime HI-6 (CAS reg. no. 34433-31-3; 1-(((4-aminocarbonyl)pyridinio)methoxy)methyl)-2-[hydroxy i mino)methyl)- pyridinium dichloride) was investigated in rhesus monkeys (Macaca mulatta). The effects of methoxyflurane anesthesia, administration of atropine with and without diazepam were determined on the serum half-life (t1/2), clearance rate (CL), and the volume of distribution (Vd) following intramuscular (IM) administration of HI-6 (30 mg kg-1). The control t1/2, CL and Vd of HI-offere 27 min, 8.6 ml min-1 kg-1 and 0.34 l kg-1, respectively. These parameters were unaffected by the co-administration of either atropine (0.5 mg kg-1, IM) or atropine and diazepam (0.5 mg kg-1, IM + 0.2 mg kg-1 IV, respectively). Methoxyflurane anesthesia resulted in a significant increase in the HI-6 t1/2 to 61 min concomitant with a decrease in the CL to 4.1 ml min-1 kg-1 with no change in the Vd. The increase in the t1/2 of HI-6 in methoxyflurane anesthetized monkeys is probably the result of a decrease in the clearance rate and, thus, excretion of HI-6 by the kidneys.
The Cell-Dyn 1000 is a new eight parameter fully automatic cell counter. This was evaluated following the ICSH guidelines. Scientific evaluation was generally satisfactory, largely conforming to the manufacturer's specifications. A number of potential microbiological safety hazards were noted; many could be overcome by minor modifications. Throughput and start-up/close-down times were acceptable. However, the reliability of the tested machine was felt to be less than satisfactory although this may be corrected by further minor machine modifications.
In a comparative study of A/J (Gpi-1a) and C57BL/6J (Gpi-1b) mice, we observed that erythrocytes of A/J mice exhibited significantly higher glucose phosphate isomerase (GPI) activity compared to erythrocytes of C57BL/6J mice on a per cell, per gram of protein, or per gram of hemoglobin basis. Higher GPI activity per cell was detected for peripheral blood lymphocytes of A/J compared to C57BL/6J mice. (A/J X C57BL/6J)F1 mice expressed erythrocyte and peripheral blood lymphocyte GPI activities intermediate to those of the parental mouse strains. The GPI activities of spleen lymphocytes from A/J, C57BL/6J, or (A/J X C57BL/6J)F1 mice were not significantly different from each other. The higher activity in the A/J mice could be due to GPI of a higher catalytic rate or to the presence of more GPI molecules. In order to distinguish these two possibilities, GPI was purified to homogeneity from both strains of mice. The specific activities (activity per milligram of protein) of the purified enzymes from the two strains were found to be similar, indicating that GPI from the A/J strain was not a more active enzyme. Antibody to the purified enzymes was prepared and used in an enzyme-linked immunosorbent assay (ELISA) to compare the relative amounts of enzyme molecules in cells of A/J and C57BL/6J mice. Results of the ELISA tests on peripheral blood lymphocytes indicated that A/J mice contain more molecules of GPI per cell and, therefore, have a higher GPI activity than C57BL/6J mice.
Allophenic mice are chimeras which are produced from the aggregation of two genotypically distinct embryos. In this study, embryos from the C57BL/6J and A/J strains were used to produce C57BL/6J----A/J allophenic mice. These strains were chosen because of their markedly different lifespans, their different glucose phosphate isomerase (GPI) isozymes, and their different H-2 haplotypes [C57BL/6J: long-lived, Gpi-1b, H-2b; A/J: short-lived, Gpi-1a, H-2a]. The mice were bled at two month intervals and the composition of their peripheral blood lymphocytes determined at each point from analysis of GPI isozymes and H-2 antigens. It was found that the proportion of long-lived (C57BL/6J) lymphocytes tended to increase with age. Moreover, the total lifespan of the allophenic mice was directly related to the percentage of long-lived lymphocytes in their peripheral blood.
The pharmacokinetics of HI-6, a cholinesterase-reactivating oxime, were studied in rats, following intravenous or intramuscular administration. A two-compartment model was used to analyse the intravenous data and a one-compartment open model with first-order absorption was used for intramuscular data. Drug concentration had no influence on rate and extent of absorption of intramuscular injections, and bioavailability was 100%. Peak plasma concentrations of HI-6 occurred 15 min after intramuscular injection. No significant differences were found between mean values for half-life, plasma clearance, volume of distribution and area under the plasma concentration versus time curve for the two intramuscular doses and the intravenous dose used. Mean HI-6 plasma concentrations were 140.5 +/- 4.2 micrograms ml-1 3 min after 20 mg ml-1 i.v., with a mean elimination half-life of 65.2 +/- 21 min. Plasma clearance rate was 3.95 +/- 0.93 ml min-1 kg and the apparent volume of distribution was 0.38 +/- 0.17 litre kg-1. The oxime is rapidly distributed in and eliminated by rats when administered intravenously or intramuscularly.
Glucose phosphate isomerase (GPI) enzyme activity was measured in two strains of mice, A/HeNNial (Gpi-1a) and C57BL/6NNia1 (Gpi-1b). Seven solid tissues (muscle, brain, heart, kidney, liver, lung, spleen) and three cell types (peripheral blood lymphocytes, spleen lymphocytes, erythrocytes) were analyzed for GPI activity in mice from 6 to 36 months of age. No major changes in enzyme activity with age were found. The most striking observation was that A/HeNNial mice showed a significantly higher GPI activity than C57BL/6NNia1 mice in four of the solid tissues (muscle, heart, kidney, spleen) and two of the cell types (peripheral blood lymphocytes, erythrocytes) analyzed.
The binding of sulfadimethoxine to selected human blood protein fractions and to fresh serum has been examined by means of a new equilibrium dialysis technique which minimizes experimental error and permits the evaluation of low-level binding. Certain alpha-globulin fractions, containing mixtures of proteins, were found to bind the drug. Scatchard analysis of the binding of sulfadimethoxine to fresh serum, calculated as though all of the binding is due to albumin, gives a different result from that obtained with isolated albumin. This may be a reflection of the contribution of the alpha-globulins to the overall binding of sulfadimethoxine in fresh serum. Although sulfadimethoxine is amphoteric, it did not bind to the alpha 1-acid glycoprotein. The drug behaves as an acidic compound when binding to the blood proteins.
We report that interference with the cholesterol assay using the cholesterol oxidase: p-aminophenazone method which is observed during lipoprotein preparation, is caused by the anti-bacterial agent thimerosol used in the preparation. We suggest that an alternative anti-bacterial agent should be used in these circumstances.
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Analysis of C57BL/6J in equilibrium A/J allophenic mice for their lymphocyte composition, using H-2 antigens as external markers, and glucose phosphate isomerase (GPI) isozymes as internal markers, has led to the discovery of two unusual mice. Both mice showed heterodimers of GPI isozymes upon electrophoresis of the lymphocyte lysate. Specific anti-H-2 antisera confirmed that the cells of the mice were of C57BL/6J and A/J origin, as expected, but that the "A/J" cells seemed to behave as F1 hybrids containing the Gpi-1a and Gpi-1b alleles. Possible origins of the Gpi-1b allele in the "A/J" cells are discussed.
The binding of drugs to plasma proteins has been studied extensively using a variety of methods, including equilibrium dialysis. Published information on controls used in these studies is frequently inadequate; in other cases, there are deficiencies in the experimental design for the controls. A method is described that eliminates many of the problems associated with artifactual errors in dialysis studies. Multiple replicated controls are performed at the same time as the test, under identical conditions. The controls are used to correct for concentration-dependent binding of drug to the membrane or other equipment. The method was used to determine the binding of sulfadimethoxine to CF-IV-1 alpha-globulin at therapeutic concentrations. The level of binding was low (9-13%), but the stringent control technique permitted statistical analysis which showed each mean test value to be significantly different from its corresponding control. Furthermore, there was a linear relationship between the control-corrected percentage binding values and total drug concentration, whereas there was no correlation between total drug concentration and the uncorrected percentage binding values.
Monoclonal antibodies (MAb) that detect specific lymphocyte subsets of man were tested for their reactivity with peripheral blood lymphocytes (PBL) and established cell lines of owl monkeys (Aotus trivirgatus) and marmosets (Saguinus spp). Results of these studies showed that certain determinants were conserved and that the pattern of reactivity observed in one genus (or even species) could not be used to predict the reactivity in another. On owl monkey PBL, reactivity equivalent to that on human PBL was observed with OKT11a, anti-Leu 3a, B1, and anti-HLA-DR MAb thus detecting T cell, helper/inducer T cell, B cell, and HLA-DR determinants. After neuraminidase treatment of owl monkey PBL, reactivity with anti-Leu 5 and OKT8 (T cell and suppressor/cytotoxic T cell determinants) was observed. Cell separation experiments indicated these determinants were found on lymphocytes with the same general properties as those of human origin. The use of these MAb to examine owl monkeys infected with Herpesvirus saimiri and tumor cell lines established from H. saimiri-inoculated monkeys revealed that the virus was found in OKT11a-positive, B1-negative cells. In chronically infected nondiseased animals, H. saimiri was found in anti-HLA-DR-negative cells and was restricted to anti-Leu 3a-positive cells (two animals) or was nearly equally distributed in anti-Leu 3a-positive and negative cells (one animal). Established H. saimiri tumor cell lines had the phenotype OKT11 a-positive, anti-HLA-DR-positive, B1-negative and were either anti-Leu 3a-positive or negative. Studies of interleukin 2-responsive tumor cells in short-term culture suggested the tumor was composed of virus-positive anti-Leu 3a-positive and negative populations.
Treatment of fresh sera with polyethylene glycol 6000 at a final concentration of 100 g/l produced selective precipitation of low-density lipoproteins with only traces of contamination with high-density lipoproteins, as determined by electroimmunoassay using antisera to human alpha1-lipoprotein and human beta-lipoprotein. Supernatants collected for high-density lipoprotein-cholesterol estimation were free from low-density lipoproteins. Precipitates sedimented readily from specimens with high triglyceride contents, and secondary precipitation during enzymatic cholesterol determinations was absent. Values obtained by this method correlated well with those obtained by precipitation of low-density lipoproteins with heparin and manganous ions at concentrations optimal for discrete of lipoprotein classes (r = 0.975; p less than 0.001).
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