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L K Johnson

Publications and source records attributed to L K Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1989

Short-term and long-term variability of indices related to nutritional status. I: Ca, Cu, Fe, Mg, and Zn.

Five free-living women (ages 28-38 y) and five women (ages 23-44 y) residing in a metabolic unit and eating a constant diet were assessed for variation in indices related to mineral nutrition. Blood was sampled once a month for five months, once a week for five weeks, and once a day for five days to assess analytical and biological variability. Analytical variability was determined by using concurrently run duplicate control samples prepared from plasma or serum pools. Of the measured indices, serum ferritin varied most, with intra-individual variance of 4.72% to 18.0%. Much of this variance may have been because of changes in iron status or in the analytical technique used. Intra-individual month-to-month variance for other indices ranged from 17% for superoxide dismutase (EC 1.15.1.1) to 1.5% for calcium. Correction for long-term analytical variation indicated that most of the variance was associated with the biological component. The higher biological variabilities of some indices, including ferritin or superoxide dismutase, need to be considered when nutritional status is being evaluated or when serial observations are made over a protracted period in clinical studies or trials.

Adult↗
PubMed1988

Evaluation of the antiinflammatory and phospholipase-inhibitory activity of calpactin II/lipocortin I.

We have examined the ability of a highly purified 38-kD phospholipase-inhibitory protein (p38) isolated from human placental membranes that is also a preferred substrate for the epidermal growth factor-urogastrone (EGF-URO) receptor/kinase, to block the release of arachidonate from zymosan-stimulated murine peritoneal macrophages in vitro and to exhibit antiinflammatory activity in a carrageenin rat paw edema test in vivo. The ability of glucocorticoids to increase the amounts of this protein in macrophage cultures was also examined. p38 represents the naturally occurring, intact, NH2-terminally blocked human placental form of the protein termed calpactin II (or lipocortin I), for which partial amino acid sequence data and a complete amino acid sequence deduced from cDNA analysis have been reported. Our data demonstrated that, whereas p38 was an effective inhibitor of pancreatic phospholipase A2 in vitro, it was unable to inhibit either the release of arachidonate from cultured zymosan-stimulated mouse peritoneal macrophages or inflammation in a rat paw edema test. At comparatively high protein concentrations, p38 enhanced either arachidonate release from intact macrophages in vitro (0.5-10 micrograms/ml) or carrageenin-induced paw swelling in vivo (2.5 or 25 micrograms per injection). Furthermore, we were unable to detect induced amounts of p38 in cultures of glucocorticoid-treated peritoneal macrophages obtained from either mice or rats. Our data indicate that the antiphospholipase activity of p38 in vitro and the ability of p38 to serve as a receptor/kinase substrate may in no way relate to the putative ability of the protein to modify eicosanoid release from macrophages in vivo, so as to modulate the inflammatory process. Our data also raise the possibility that p38 (calpactin II) may not be a true representative of the lipocortin family of glucocorticoid-inducible antiinflammatory proteins, despite its ability to inhibit phospholipase A2 in vitro.

Animals↗
PubMed1986

Pancreatic phospholipase A2: isolation of the human gene and cDNAs from porcine pancreas and human lung.

Oligonucleotide probes synthesized using the published protein sequence for porcine pancreatic phospholipase A2 (PLA2; Puijk et al., 1977), were used to screen a cDNA library made from porcine pancreas. One resulting clone which encoded the entire porcine PLA2 enzyme was then used to screen various human cDNA and gene libraries. A 562-bp cDNA clone from human lung and two overlapping genomic clones encoding the identical transcript were obtained. These clones encoded a 126-residue peptide corresponding to human "pancreatic" PLA2. The gene spanned 4.9 kb and contained three introns of 1692, 800, and about 2650 bases, respectively. Hybridization of the human cDNA against blots of total human DNA detected the same set of fragments contained in both genomic clones and failed to detect more than one distinct gene. Under equivalent conditions, the same probe detected two discrete bands in cobra (Naja naja) genomic DNA. Apparently, there is a single or small number of identical human genes encoding "pancreatic" PLA2 which are transcribed also in lung tissue; human pancreatic PLA2 appeared more closely related at the nucleotide level to snake counterparts than to other reported human PLA2 enzyme forms.

Animals↗
PubMed1986

Response of the microflora in outdoor experimental streams to pentachlorophenol: environmental factors.

The 2nd year of a 2-year study of the fate of pentachlorophenol in outdoor artificial streams focused on details of microbial degradation by a combination of in situ and laboratory measurements. Replicate streams were dosed continuously at pentachlorophenol concentrations of 0, 48, and 144 micrograms/L, respectively, for an 88-d period during the summer of 1983. Pentachlorophenol was degraded both aerobically and anaerobically. Aerobic degradation was more rapid than anaerobic degradation. Mineralization of pentachlorophenol was concommitant with pentachlorophenol disappearance under aerobic conditions, but lagged behind loss of the parent molecule under anaerobic conditions. Biodegradation in the streams, or in specific stream compartments such as the sediment or water column, was characterized by an adaptation period (3-5 weeks for the stream as a whole, and reproducible from the previous year), which was inversely dependent on the concentration of pentachlorophenol and microbial biomass. The adaptation in the streams could be attributed to the time necessary for selective enrichment of an initially low population of pentachlorophenol degraders on surface compartments. The extent of biodegradation in the streams (percent loss of initial concentration of pentachlorophenol) increased with increasing pentachlorophenol input, which was explicable by an increase in the pentachlorophenol degrader population with increasing pentachlorophenol concentration. The sediment zone most significant to overall pentachlorophenol biodegradation was the top 0.5- to 1-cm layer as shown by pentachlorophenol migration rates and depth profiles of degrader density within the sediment. Pentachlorophenol profiles in sediment cores taken during and after the adaptation period for degradation showed that diffusion of pentachlorophenol into the sediment was rate limiting to degradation in this compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerobiosis↗
PubMed1986

Cloning, sequence analysis, and processing of the rat and human atrial natriuretic peptide precursors.

Complementary DNA sequences and structural genes encoding the atrial natriuretic peptide precursor (prepro-ANP) have been cloned. Analysis of DNA sequences, complementary to rat atrial prepro-ANP mRNA, has revealed that the various natriuretic peptides isolated from rat atrium reside at the carboxy terminus of a 152-amino-acid precursor protein. The human gene, comprised of three exons and two intervening sequences, encodes a protein of 151 amino acids highly homologous to the rat precursor. Although putative proteolytic processing sites can be identified throughout the prepro-ANP amino acid sequence, the natural form of the mature ANP has not been identified. Therefore, the sites and mechanisms of prepro-ANP processing to mature peptides forms are unknown. However, the successful cloning of the prepro-ANP gene and corresponding cDNAs provide the necessary molecular tools to address these fundamental questions relating to the regulation of ANP synthesis and processing in atrial and extraatrial tissues.

Amino Acid Sequence↗
PubMed1986

Risk factors for estrogen receptor-rich and estrogen receptor-poor breast cancers.

A population-based case-control study was conducted in King County, WA, to investigate whether risk factors for estrogen receptor (ER)-rich and ER-poor breast cancers differ. Responses to interviews with 329 women with breast cancer who were between 25 and 54 years of age at the time of diagnosis were compared to responses of 332 women of similar age who were selected from female residents of King County by random digit dialing. Of the 329 interviewed cases, 143 had ER-rich tumors, 97 had ER-poor tumors, and 89 had tumors that were not assayed for receptors. The relative risks of ER-rich and ER-poor breast cancers were similar with respect to late menarche, single marital status, history of extended lactation, menopause before age 40, history of benign breast disease, positive family history of breast cancer, obesity, and history of oral contraceptive and noncontraceptive estrogen use. Late age at first full-term pregnancy was a risk factor for ER-rich breast cancer but not for ER-poor breast cancer. This finding suggests that different causal mechanisms operate for these two types of breast cancer and supports the hypothesis that an early first birth protects against breast cancer by reducing the level of ERs in the mammary epithelial cells from which carcinomas develop.

Adult↗
PubMed1985

Distinct atrial natriuretic factor receptor sites on cultured bovine aortic smooth muscle and endothelial cells.

Cultured bovine aortic smooth muscle and endothelial cells each display distinct specific binding sites for radiolabeled atrial natriuretic peptide (ANF). 125I-pro-rANF (103-126)I binding to both cell types is rapid, reversible and competitive. Scatchard plots of the binding data show Bmax values of 5.5 and 0.1 - 2.1 X 10(5) sites/cell and Kd values of 2.1 and 0.3 nM for smooth muscle and endothelial cells, respectively. In addition, ANF elevates levels of cGMP substantially in both cell types at concentrations of ANF close to its Kd and Ki for binding. Sodium nitroprusside, however, has essentially no effect on cGMP levels in either cell type. These results show that distinct functionally active receptor sites for ANF exist on both vascular smooth muscle and endothelial cells.

Animals↗
PubMed1985

Comparison of dietary histories and seven-day food records in a nutritional assessment of older adults.

Dietary histories and seven-day food records were obtained for 54 apparently healthy older adults. The two dietary methods correlated for most nutrients, but mean differences were significant for several nutrients. Intakes below recommended levels occurred most frequently for energy, calcium, and zinc. Biochemical evidence of thiamin and riboflavin deficiency was unexpectedly frequent. Using food records, dietary iron correlated with serum ferritin. Using dietary histories, dietary protein correlated with serum albumin, and dietary zinc correlated with plasma zinc. Using either dietary method, plasma ascorbate was associated positively with both dietary ascorbate and ascorbate supplements, and negatively with cigarette smoking. Use of thiamin- or folate-containing supplements was associated with improved biochemical status for the respective vitamin. Though neither dietary histories nor food records give precise intake data for individuals, either method may be useful for epidemiologic studies with appropriate sample sizes.

Aged↗
PubMed1985

Response of the microflora in outdoor experimental streams to pentachlorophenol: compartmental contributions.

Outdoor artificial streams were treated continuously with pentachlorophenol (PCP) for 88 days during the summer of 1983. The contributions of different stream compartments (microbial habitats) to microbial degradation of PCP were determined in a stream treated with 144 micrograms of PCP per liter. The 488-m long stream was composed of mud-bottomed pools alternating with gravel riffles. PCP loss in the stream attributable to microbial degradation after an adaptation period was in the range of 55 to 74%. Contributions to PCP loss were determined for rock surface (epilithic), macrophyte surface (epiphytic), sedimentary, and water column communities by measuring rates of PCP disappearance in stream water, containing ambient concentrations of PCP, in contact with representative compartmental samples. The specific capability, in units of micrograms of PCP per hour per square meter of stream cross-sectional area (macrophytes at maximum plant density, water column at mean depth, upper 10-cm layer of gravel), followed the order rock surface much greater than macrophytes greater than sediment approximately equal to water column. The compartmental contribution to total stream losses in units of grams per hour followed the same order, although the differences were smaller. The rate of PCP disappearance in the water column above sediment cores followed the order oxygen-rich greater than oxygen-poor approximately equal to anaerobic greater than sorption-only conditions. The large difference in specific capability between the rock surface and sediment compartments could be attributed to oxygen deficiency (because of chemical and biological oxygen demand) in the sediments. Free-floating and particle-attached organisms in the water column were important to PCP biodegradation.

Aerobiosis↗
PubMed1985

Renal mechanism of action of rat atrial natriuretic factor.

There has been conflict as to whether crude extracts of atrial natriuretic factor increase renal solute excretion by a hemodynamic mechanism or by direct inhibition of tubular transport. To investigate this issue, seven rats were studied during a euvolemic control period and following continuous administration of pure, synthetic 24 amino acid atrial natriuretic factor. A 10-25-fold increase in urinary sodium and chloride excretion occurred with a brisk kaliuresis but little bicarbonaturia. Atrial natriuretic factor caused whole kidney glomerular filtration rate to increase from 1.17 +/- 0.04 to 1.52 +/- 0.07 ml/min (P less than 0.005). A parallel increase in single nephron glomerular filtration rate, from 34 +/- 1 to 44 +/- 2 nl/min (P less than 0.001), and from 26 +/- 1 to 37 +/- 2 nl/min (P less than 0.005) was measured at the end-proximal and early distal nephron sites, respectively. Appropriate for the higher flows were an increase in absolute proximal and loop reabsorptive rates for bicarbonate, chloride, and water, with a slight decrease in fractional solute and volume reabsorption in proximal and loop segments. To exclude the possibility that atrial natriuretic factor increased filtration rate only in anesthetized animals, eight unanesthetized rats were studied. Glomerular filtration rate increased by 45%, from 2.04 +/- 0.17 to 2.97 +/- 0.27 ml/min (P less than 0.005) without significant change in renal plasma flow, as reflected by 14C-para-aminohippurate clearance (5.4 +/- 0.5-5.6 +/- 0.9 ml/min). The clearance and micropuncture data did not preclude changes in relative blood flow distribution to or in transport by deep nephron segments. In conclusion, atrial natriuretic factor appears to increase renal solute excretion predominantly by a hemodynamic mechanism without directly inhibiting superficial tubular transport.

Animals↗
PubMed1985

Canned foods: appropriate in trace element studies?

This study was conducted to help decrease the variability of metabolic diets. The effects of production lot and storage time on the trace element content of canned food products were compared. Various production lots of peaches, green beans, and tomatoes, canned in tinplate, were purchased and opened at three different times, spaced at 6-month periods. Storage time contributed more to the variability of tomatoes and green beans than production lot. Production lot was the more important factor in peaches. The following guidelines may be useful for metabolic studies lasting more than a few weeks: Use only frozen foods or foods canned in glass, maintaining constant production lots when possible. If only tin-canned products are available, remove the product from the can and freeze when appropriate. When products are retained in the can, maintain storeroom at a low temperature above freezing. In all cases, purchase specifications should require products to be from the most recent canning season, and kitchen procedures should be constant.

Analysis of Variance↗
PubMed1984

Monoclonal antibodies against human DNA polymerase-alpha do not cross-react with glucocorticoid receptors.

None of 16 independent monoclonal antibodies against human (KB cell) DNA polymerase-alpha recognizes epitopes on cytoplasmic glucocorticoid receptors prepared from the same cells. Consistently negative results are obtained with separate assays that measure antibody binding to uncharged receptors or to charged receptor complexes that have been preloaded with a specific steroid ligand. These results must qualify the interpretation of possible immunological relations between polymerase-alpha and glucocorticoid receptors that were inferred from studies with polyclonal antisera of poorly defined specificity.

Antibodies, Monoclonal↗
PubMed1984

Increased cholesterol in plasma in a young man during experimental copper depletion.

Signs of copper depletion were produced in a healthy man by an amount of dietary copper (0.83 mg/day) similar to that in some contemporary diets. Urinary and fecal loss of copper exceeded intake. Plasma copper, ceruloplasmin, and superoxide dismutase activity in erythrocytes decreased. Cholesterol in plasma increased, and hematologic indices were unchanged. Lipid metabolism may be a more sensitive index of copper nutriture than are changes in hematology. The findings support the hypothesis that inadequate copper nutriture or altered copper metabolism contributes to the occurrence of ischemic heart disease.

Adult↗
PubMed1984

Glucocorticoid inhibition of vascular smooth muscle cell proliferation: influence of homologous extracellular matrix and serum mitogens.

We examined the influence of glucocorticoid hormones on the proliferation of cultured adult bovine aortic smooth muscle cells (BASM) using both primary mass cultures and a cloned strain. Cloned BASM cells maintained on plastic culture dishes were inhibited by approximately 40% by dexamethasone treatment but showed no inhibition when grown of homologous extracellular matrix (ECM) coated dishes. Dexamethasone inhibited growth of primary cultures by 73% on plastic and by 45% on ECM. The inhibitory effect was specific for the glucocorticoids, dexamethasone, corticosterone, and cortisol and was not observed with progesterone, aldosterone, estradiol or 17-alpha OH progesterone. In cloned cells, the abolition of glucocorticoid inhibition by ECM was independent of seeding density and serum concentration. The inhibition on plastic was dependent on serum concentrations greater than 1% and resulted in both a slow rate of proliferation and a lower saturation density. A specific subset of peptides detected on two-dimensional gels was induced by glucocorticoids under growth inhibitory conditions but was not induced when the cells were grown on ECM. Primary cultures grown on ECM and exposed to Dulbecco's modified Eagle's Medium (DME) containing high density lipoprotein and transferrin grew at 40% of the rate observed for cultures exposed to DME with 10% serum. Both conditions showed growth inhibition of 70% in the presence of dexamethasone. The addition of epidermal and platelet-derived growth factors in DME containing high density lipoprotein and transferrin to cells grown on ECM resulted in growth rates comparable to that observed with cultures exposed to 10% serum and were inhibited 45% by dexamethasone. These results suggest that glucocorticoids inhibit smooth muscle proliferation by decreasing the sensitivity of the cells to mitogenic stimulation by high density lipoprotein when the cells are maintained on a homologous substrate.

Animals↗
PubMed1984

Glucocorticoids stimulate collagen and noncollagen protein synthesis in cultured vascular smooth muscle cells.

The effect of glucocorticoids on collagen synthesis was examined in cultured bovine aortic smooth muscle (BASM) cells. BASM cells treated with 0.1 microM dexamethasone during their proliferative phase (11 d) were labeled with [3H]proline for 24 h, and the acid-precipitable material was incubated with bacterial collagenase. Dexamethasone produced an approximate twofold increase in the incorporation of proline into collagenase-digestible protein (CDP) and noncollagen protein (NCP) in the cell layer and medium. The stimulation was present in both primary mass cultures and cloned BASM. An increase in CDP and NCP was detected at 0.1 nM, while maximal stimulation occurred at 0.1 microM. Only cells exposed to dexamethasone during their log phase of growth (1-6 d after plating) showed the increase in CDP and NCP when labeled 11 d after plating. The stimulatory effect was observed in BASM cells treated with the natural bovine glucocorticoid, cortisol, dexamethasone, and testosterone, but was absent in cells treated with aldosterone, corticosterone, cholesterol, 17 beta-estradiol, and progesterone. The increase in CDP and NCP was absent in cells treated with the inactive glucocorticoid, epicortisol, and totally abolished by the antagonist, 17 alpha-hydroxyprogesterone, suggesting that the response was mediated by specific cytoplasmic glucocorticoid receptors. Dexamethasone-treated BASM cells showed a 4.5-fold increase in the specific activity of intracellular proline, which was the result of a twofold increase in the uptake of proline and depletion of the total proline pool. After normalizing for specific activity, dexamethasone produced a 2.4- and 2.8-fold increase in the rate of collagen and NCP synthesis, respectively. Cells treated with dexamethasone secreted 1.7-fold more collagen protein in 24 h compared to control cultures. The BASM cells secreted 70% Type I and 30% Type III collagen into the media as assessed by two-dimensional gel electrophoresis. The ratio of these two types was not altered by dexamethasone. The results of the present study demonstrate that glucocorticoids can act directly on vascular smooth muscle cells to increase the synthesis and secretion of collagen and NCP.

Animals↗
PubMed1984

Effect of consuming fiber from corn bran, soy hulls, or apple powder on glucose tolerance and plasma lipids in type II diabetes.

The effects of consuming corn bran, soy hulls, or apple powder on glucose and lipid metabolism were investigated in two studies of persons with type II diabetes. Fiber sources, completely or partially added to bread, were incorporated into subjects' self-selected diets. Low fiber white bread served as a control. In study A, 10 subjects consumed 26 g fiber source daily; in study B, eight subjects consumed 52 g fiber source. Biochemical tests, including a 2-h postprandial glucose test using a low fiber formula meal, were scheduled after 2 and 4 wk of each dietary treatment. Soy hull consumption slightly improved some measures of glucose tolerance, with results varying between the studies. Consumption of 52 g corn bran decreased very low-density lipoprotein cholesterol, triglycerides, and glycosylated Hb, but subject tolerance was poor with the particle size used. Consumption of 52 g apple powder increased low-density lipoprotein and total cholesterol levels.

Aged↗