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C C McCormick

Publications and source records attributed to C C McCormick.

At least 19 recordsLinked to original sources
PubMed2001

Lipopolysaccharide and interferon-gamma-induced nitric oxide production and protein oxidation in mouse peritoneal macrophages are affected by glutathione peroxidase-1 gene knockout.

This study investigated the role of glutathione peroxidase-1 (GPX1) in protein oxidation in peritoneal macrophages. Macrophages isolated from both wild-type (WT) and GPX1 knockout (KO) mice were activated by lipopolysaccharide (LPS, 1 microg/ml) and interferon-gamma (IFN, 10 U/ml for 24 or 48 h in the presence or absence of 1 microM diquat (DQ), 250 microM aminoguanidine (AG, an inhibitor of inducible nitric oxide synthase), and (or) 100 microM diethyldithiocarbamate (DETC, an inhibitor of Cu,Zn-SOD). In the KO macrophages, there was no protein band detected by Western blot with anti-GPX1 antibody and 98% reduction in total GPX activity compared with WT cells. Nitric oxide (NO) synthesis was greatly enhanced after 24 h by GPX1 knockout and DQ, but inhibited by AG or DETC. Protein carbonyl formation in total cell extract was clearly associated with NO synthesis as higher levels of protein carbonyl were detected in activated KO than WT macrophages, and DQ enhanced slightly while AG or DETC virtually blocked its formation. A similarly marginal effect of GPX1 KO was observed on protein nitration. The LPS/IFN/DQ-induced DNA fragmentation was blocked by AG, but not by DETC. Cell viability at 48 h was decreased by the LPS/IFN activation and further reduced by the addition of DQ, but restored by AG. In conclusion, GPX1 affects the NO production in activated peritoneal macrophages and protects these cells against NO-associated protein oxidation.

Animals↗
PubMed2000

High-precision isotope ratio mass spectrometry and stable isotope precursors for tracer studies in cell culture.

The use of stable isotope-labeled tracers is demonstrated in an in vitro system with analysis by high-precision isotope ratio mass spectrometry (IRMS), using n-3 long-chain polyunsaturated fatty acid (LCP) biosynthesis from [U-(13)C]18:3n-3 (18:3n-3*) in Y79 human retinoblastoma cells as a model system. The cells were cultured as a suspension in RPMI 1640 medium supplemented with 15% fetal calf serum at 37 degrees C with 5% CO(2) in air. They were harvested by sedimentation and cell lipids were extracted to determine the presence of 18:3n-3* metabolites using gas chromatography-combustion (GCC)-IRMS. As the dose of 18:3n-3* was systematically increased from treatment to treatment, the atom percent excess and the amounts of biosynthesized LCP* increased, while the percentage dose in each n-3 LCP* remained constant. Cultures incubated with 0.5 micromol (10 microM) of albumin-bound 18:3n-3, composed of 18:3n-3* diluted 1/60 or 1/100 with natural abundance 18:3n-3, yielded products with enrichments about 1.5 at.% excess (delta(13)C(PDB) < 1500 per thousand), which is optimal for high-precision measurements. Kinetics in Y79 cells incubated with 18:3n-3* showed that n-3 LCP* incorporation increased over time; 18:3n-3*, 20:5n-3*, 22:5n-3*, and 22:6n-3* were detected at all time points with the 1/60 dilution. These data document experimental parameters for optimal stable isotope use and IRMS detection for in vitro tracer methodology.

Carbon Isotopes↗
PubMed2000

Oxygen tension limits nitric oxide synthesis by activated macrophages.

Previous studies have established that constitutive calcium-dependent ('low-output') nitric oxide synthase (NOS) is regulated by oxygen tension. We have investigated the role of oxygen tension in the synthesis of NO by the 'high-output' calcium-independent NOS in activated macrophages. Hypoxia increased macrophage NOS gene expression in the presence of one additional activator, such as lipopolysaccharide or interferon-gamma, but not in the presence of both. Hypoxia markedly reduced the synthesis of NO by activated macrophages (as measured by accumulation of nitrite and citrulline), such that, at 1% oxygen tension, NO accumulation was reduced by 80-90%. The apparent K(m) for oxygen calculated from cells exposed to a range of oxygen tensions was found to be 10.8%, or 137 microM, O(2) This value is considerably higher than the oxygen tension in tissues, and is virtually identical to that reported recently for purified recombinant macrophage NOS. The decrease in NO synthesis did not appear to be due to diminished arginine or cofactor availability, since arginine transport and NO synthesis during recovery in normoxia were normal. Analysis of NO synthesis during hypoxia as a function of extracellular arginine indicated that an altered V(max), but not K(m)(Arg), accounted for the observed decrease in NO synthesis. We conclude that oxygen tension regulates the synthesis of NO in macrophages by a mechanism similar to that described previously for the calcium-dependent low-output NOS. Our data suggest that oxygen tension may be an important physiological regulator of macrophage NO synthesis in vivo.

Animals↗
PubMed1996

Molecular cloning and expression of an avian macrophage nitric-oxide synthase cDNA and the analysis of the genomic 5'-flanking region.

We report the first nonmammalian inducible nitric-oxide synthase (NOS) cDNA obtained from chicken macrophages. It exhibits an open reading frame encoding 1,136 amino acid residues, predicting a protein of 129,648-Da molecular mass. The deduced NOS protein sequence showed 66.6%, 70.4%, 54.2%, and 48.7% sequence identity to mouse and human inducible NOS and to two constitutive NOSs from rat brain and bovine endothelium. Overall, NOS appears to be a moderately conserved protein. Northern analysis showed that chicken iNOS mRNA is approximately 4.5 kilobases (kb), a size similar to mammalian inducible NOS. Analysis of 3.2 kb of 5'-flanking sequence of the chicken iNOS gene showed a putative TATA box at 30 base pairs (bp) upstream of the transcription initiation site. The functional importance of the upstream region was determined by transient expression of deletion constructs. An endotoxin regulatory region was located exclusively within 300 bp upstream of the transcription initiation site. This is in contrast to the two distinct sites identified in the mouse macrophage NOS promoter. Transcription factor binding sites such as NF-kappaB, PEA1, PEA3, and C/EBP were identified. Using a NF-kappaB inhibitor, we showed that NF-kappaB is indeed involved in the induction of chicken iNOS gene by lipopolysaccharide. Our results suggest that NF-kappaB is a common regulatory component in the expression of both mammalian and nonmammalian iNOS genes.

Amino Acid Sequence↗
PubMed1996

Inhibition of nitric oxide synthase gene expression in vivo and in vitro by repeated doses of endotoxin.

We have examined the effects of repeated endotoxin administration in vivo and in vitro on the induction of nitric oxide synthase (NOS). In vivo, hepatic NOS activity and mRNA were increased markedly by the administration of Escherichia coli lipopolysaccharide (LPS). The change in hepatic NOS activity coincided with a marked accumulation of hepatic citrulline. Both enzyme activity and citrulline concentration returned to normal by 12 h after LPS administration. At this time, a subsequent administration of endotoxin caused no change in either NOS mRNA, NOS activity, or citrulline concentration, and thus an endotoxin-refractory state for nitric oxide (NO) synthesis was established. Normal sensitivity was reestablished by 24 h after the initial dose. In vitro studies using both a macrophage cell line (HD11) and primary macrophages indicated that LPS pretreatment caused cells in culture to become completely refractory to subsequent stimulation by LPS. Finally, we tested the hypothesis that NO may be involved in the development of the refractory state. Various inhibitors blocked the initial synthesis of NO by > 90% but failed to influence the development of the refractory state. Our study demonstrates both in vivo and in vitro that NO synthesis is completely blocked after repeated exposure to endotoxin by a mechanism that appears to be pretranslational. This model of early endotoxin tolerance may provide insight into the molecular mechanisms that regulate expression of the NOS gene.

Animals↗
PubMed1996

Recognizing the allergic child.

The delivery of health care is currently in a state of transition with managed care emerging as a frequently used method for health care delivery. A major tenet of many managed care systems is that specialized care is costly and thus is to be delayed or avoided when possible. The end result of this philosophy is that primary care physicians will find themselves providing patient care which, in the past, had been provided by the specialist. In the field of allergy, as in any other specialty, providing adequate and appropriate care to the patient is incumbent on recognizing that the patient's symptoms are allergic in etiology. This is especially true when presenting symptoms are different from the classical signs and symptoms of allergy. This paper presents: (1) specific comments and suggestions which will enable the primary care physician to recognize the allergic child, (2) data from over 800 children referred for allergy evaluation to support the foregoing comments and suggestions and, (3) recommendations as to how primary care physicians might effectively manage most children with certain types of allergic disease without referral to an allergist.

Adolescent↗
PubMed1995

An overview of medical imaging in the Röentgen centenary year.

This article reviews briefly current opinion regarding optimal imaging in a number of clinical situations presenting in family practice. The choice of imaging procedure, of course, depends upon availability, particularly in country areas. Nuclear medicine especially has not yet become as widely disseminated outside the large cities. To exclude repetition, topics that are the subject of more extensive review later in this issue have been excluded from this article.

Humans↗
PubMed1995

Radiology and low back pain.

An outline of radiological investigations for patients with low back pain is presented. The article emphasises the need for thorough clinical evaluation of patients before any radiological investigations are undertaken. The types of radiological tests best suited to particular clinical problems are highlighted.

Adolescent↗
PubMed1991

Triiodothyronine stimulates and cyclic AMP inhibits transcription of the gene for malic enzyme in chick embryo hepatocytes in culture.

In chick embryo hepatocytes in culture, insulin and triiodothyronine (T3) increase malic enzyme activity and the abundance of malic enzyme mRNA by at least 50-fold, and glucagon or cAMP blocks this effect. Steps regulated by these hormones were defined by measuring transcriptional activity with the nuclear run-on assay and multiple fragments of the malic enzyme gene as probes. T3 alone caused a significant increase in transcription within 1 h, with a maximal increase of 30-40-fold occurring by 24 h. When T3 was added with insulin, 80% of the maximum rate was reached in 1 h. Insulin alone had no effect on transcription of the malic enzyme gene; it amplified the response to T3 in the first few hours after adding T3 but did not alter T3's maximal effect. Cyclic AMP for 1 h completely inhibited the increase in transcription caused by T3. The size and speed of the responses of the malic enzyme gene to T3 and cAMP suggest regulation of transcription initiation. T3-stimulated transcription of the malic enzyme gene did not require ongoing protein synthesis despite the fact that inhibitors of protein synthesis inhibited the T3-stimulated accumulation of its mRNA. T3 may directly activate transcription of this gene via its receptor. The pattern of DNase I hypersensitivity of the malic enzyme gene in chick embryo hepatocytes was the same as that in fed chick liver. Insulin, T3, and cAMP had no effect on that pattern. In chick embryo hepatocytes in culture, factors involved in regulation of transcription by insulin, T3, and cAMP may be bound to DNA independently of hormonal treatment.

Animals↗
PubMed1991

Abundance of hepatic metallothionein mRNA is increased by protein-synthesis inhibitors. Evidence for transcriptional activation and post-transcriptional regulation.

Ongoing protein synthesis is a prerequisite in the expression of some genes. We studied the effect of various protein synthesis inhibitors on the expression of the avian metallothionein (MT) gene. Chicken embryonic hepatocytes in culture were exposed to various concentrations of cycloheximide, puromycin and pactamycin. At concentrations which decreased total protein synthesis by about 90% each inhibitor increased MT mRNA accumulation approx. 5-fold at 9 h of incubation. Incubation with puromycin or zinc for 2 h markedly increased the rate of MT gene transcription. Estimates of the half-life of MT mRNA by using actinomycin D suggested for cycloheximide, but not puromycin, decreased the decay rate of MT mRNA. These data suggest the potential for post-transcriptional regulation of the avian MT gene. We conclude that different antibiotics increase the accumulation of hepatocyte MT mRNA by different mechanisms and that the possibility of multiple mechanisms should be considered in other studies of the role of protein synthesis in gene expression.

Animals↗
PubMed1991

Lumbar facet joint fat pads: their normal anatomy and their appearance when enlarged.

The polar recesses, superior and inferior to lumbar facet joints, are filled by fat pads from which fat-filled synovial folds project between the articular surfaces for a distance of two to four millimetres. The intracapsular superior recess lies between the ligamentum flavum and the lamina above. The extracapsular inferior recess lies on the back of the lamina below and communicates with the joint through a hole in the inferior capsule. The intracapsular folds move freely in and out of the joint during movements. These features are demonstrated in anatomic studies using transverse sections and radiologic studies using computed tomography. In about 4% of lumbar spines examined, the intraarticular fat pads are enlarged and extend from the joint recess(es) into the middle third of one or more facet joints. The fat pads can be identified in CT scans by their radiolucency and distinguished from vacuum phenomenon by measuring their attenuation values. The cause of the intra-articular enlargement of the fat pads is unknown, but it is suggested that their extension into the middle third of the joint may be secondary to degenerative change in the motion segment with capsular laxity in the affected joint.

Adipose Tissue↗
PubMed1991

Effect of sodium aluminosilicate, oyster shell, and their combinations on acid-base balance and eggshell quality.

Three experiments were conducted to determine the effect of sodium aluminosilicate (SAS), oyster shell (OS), and their combinations on production performance, eggshell quality, and acid-base balance. Experiments 1 and 2 were conducted during summer and Experiment 3 in winter. In Experiment 1, the effect of two levels of SAS (0 and .75%) and two levels of OS (0 and 50% substitution for pulverized limestone) was studied. In Experiment 2, the effect of SAS (.75%) with or without Na adjustment was investigated. When Na was adjusted, various sources of chloride were used to maintain an adequate level of this mineral. Calcium and available P were maintained at a constant 3.5 and .4%, respectively in Experiments 1 and 2. In Experiment 3, the levels of SAS and OS were similar to those of Experiment 1, but dietary Ca was either 2.8 or 3.5%. Egg production performance was not influenced by dietary treatments in Experiments 1 and 2 (P greater than .05). Egg production, but not egg mass, was reduced due to SAS in Experiment 3 (P less than .05). Dropping moisture increased when SAS was used in the diets with or without Na correction. Shell quality increased (P less than .05) due to SAS in the summer (Experiments 1 and 2) but not in the winter (Experiment 3). The shell quality response due to SAS was independent of Na correction or the source of dietary chloride. The OS increased shell quality in both summer and winter (P less than .05). Combinations of SAS and OS did not have an additive effect on shell quality (P greater than .05). Blood acid-base balance, plasma Ca and P, bone ash, bone Ca, and Ca retention were not influenced by dietary treatments. The results suggest that elevated environmental temperatures may be required in order for SAS to show its optimum effect on shell quality.

Acid-Base Equilibrium↗
PubMed1990

Iron-induced metallothionein in chick liver: a rapid, route-dependent effect independent of zinc status.

The induction of hepatic metallothionein (MT) by the parenteral administration of iron was studied. Iron administered to chicks by intravenous or subcutaneous injection caused a 1.9-fold increase in hepatic MT. In marked contrast, intraperitoneal (ip) Fe resulted in a 10-fold increase, thus demonstrating the importance of the route of metal administration. This route-dependent effect was found to be dose-dependent, with ip injections between 1 and 10 mg Fe/kg resulting in a linear increase in MT and a concomitant reduction in serum zinc concentration and feed intake. High ip doses of Fe resulted in a persistent depression in serum Zn and elevated MT and MTmRNA. Equimolar ip injections of either Zn or Fe showed similar patterns of MTmRNA accumulation. In both cases MTmRNA levels were elevated by 3 h, with a peak at 6 h postinjection (Fe 8-fold, Zn 12-fold above 0 h). Plasma Zn was maximally reduced by Fe at 9 h (60%). The MT induction by Fe, as well as related depression in plasma Zn, was completely inhibited by actinomycin D. Zn depletion eliminated the accumulation of hepatic Zn and MT protein following ip injection of Fe or endotoxin, but not of cadmium, despite marked elevation of hepatic MTmRNA. Our results demonstrate Fe injected into the body cavity of chicks results in a rapid induction of hepatic MT that, like endotoxin induction, is independent of dietary Zn status.

Animals↗
PubMed1990

Induction of hepatic metallothionein by intraperitoneal metal injection: an associated inflammatory response.

The nature of hepatic metallothionein (MT) induction by several metals and its relationship to an inflammatory response was studied in chicks. Intraperitoneal (ip) injection of chromium (Cr), managanese, and iron (Fe) caused a much greater increase in hepatic MT (10.2-, 9.0-, and 6.8-fold) compared with cobalt and nickel (2.5- and 2.9-fold); thus not all transition metals are effective. Cr3+ caused markedly greater hepatic MT accumulation than Cr6+, suggesting that the ionic nature of the metal is an important factor. Small organic complexes of Fe (ferrous gluconate or lactate, 6.2-fold) caused significantly greater accumulation of hepatic MT than ferric dextran (1.4-fold), a large organic aggregate. In vitro data from chick hepatocytes and/or fibroblasts clearly indicated that Fe does not effect the induction of MT directly. The role of inflammation, as measured by recruitment of peritoneal exudate cells (PEC), was examined. Endotoxin (LPS), Sephadex (S), and Fe elicited significant elevations in PEC number at 24 h posttreatment (S), and Fe elicited significant elevations in PEC number at 24 h posttreatment (S = Fe greater than LPS much greater than control). The percentage of heterophils but not macrophages was significantly correlated with the accumulation and induction of hepatic MT. In a similar experiment with Cr, we demonstrated that Cr3+ but not Cr6+ stimulated MT messenger RNA accumulation and concomitant hetereophil infiltration at 3 h after injection. Our results indicate that the induction of hepatic MT by the parenteral administration of a number of metals is dependent on the chemical nature of the metal and is associated with an inflammatory response.

Animals↗