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G L Johanning

Publications and source records attributed to G L Johanning.

34 records · Page 2Linked to original sources
PubMed1996

Effect of angiotensin-converting enzyme gene polymorphism on pregnancy outcome, enzyme activity, and zinc concentration.

OBJECTIVE: To evaluate the effect of angiotensin-converting enzyme (ACE) genotypes on pregnancy outcome, the incidence of pregnancy-induced hypertension, and changes in blood pressure (BP) during pregnancy; and the relationship between plasma ACE activities and plasma and erythrocyte zinc concentrations in each genotype. METHODS: The subjects (n = 191) were selected from 580 indigent African-American pregnant women who enrolled toward the end of a trial to evaluate the effect of zinc supplementation on pregnancy outcome. This selection resulted in 93 subjects who received zinc and 98 who received placebo. Sample size was calculated with a 0.50 correlation coefficient between plasma ACE activities and zinc levels and a power of 80%. This calculation indicated that the sample size in each ACE genotype should be more than 28. Angiotensin-converting enzyme genotypes were identified using polymerase chain reaction. Blood pressure, plasma ACE activities, and plasma and erythrocyte zinc concentrations were measured at each prenatal clinical visit. RESULTS: Pregnancy outcome, the incidence of pregnancy-induced hypertension, and BP were not different among the three ACE genotypes. There was no significant correlation between plasma ACE activities and zinc concentrations. Zinc supplementation did not have a significant effect on either plasma ACE activities or zinc concentrations, probably because of the small sample size in our study. CONCLUSION: There was no effect of ACE gene polymorphism on pregnancy outcome, the incidence of pregnancy-induced hypertension, or changes in BP during pregnancy. Among each ACE genotype, plasma ACE activities did not correlate significantly with plasma zinc concentrations.

Adolescent↗
PubMed1995

Cofactor role for 10-formyldihydrofolic acid.

10-Formyl-7,8-dihydrofolic acid (10-HCO-H2folate) was prepared by controlled air oxidation of 10-formyl-5,6,7,8-tetrahydrofolic acid (10-HCO-H4folate). The UV spectra of the 10-HCO-H2folate preparation has lambda max. 234, 333 nm and lambda min. 301 nm at pH 7.4, and lambda max. 257, 328 nm and lambda min. 229, 307 nm at pH 1. 1H-NMR spectroscopy of 10-HCO-H2folate (in 2H2O; 300 MHz) suggested a pure compound and gave resonances for one formyl group proton, two protons on C-7 and C-9, and no evidence for a C-6 proton, which is consistent with the structure proposed. The spectral properties indicated that the 10-HCO-H2folate preparation is not appreciably contaminated with 10-HCO-H4folate, 5,10-methenyltetrahydrofolic acid (5,10-CH = H4folate) or 10-formylfolic acid (10-HCO-folate). The above data establish that the 10-HCO-H2folate prepared here is authentic. In contrast, a folate with a UV spectrum having lambda max. 272 nm and lambda min. 256 nm at pH 7, which was prepared by 2,6-dichloro-indophenol oxidation of 10-HCO-H4folate and reported to be 97% pure [Baram, Chabner, Drake, Fitzhugh, Sholar and Allegra (1988) J. Biol. Chem. 263, 7105-7111], is apparently not 10-HCO-H2folate. 10-HCO-H2folate is utilized by Jurkat-cell (human T-cell leukaemia) and chicken liver aminoimidazolecarboxamide ribonucleotide transformylase (AICAR T'ase; EC 2.1.2.3) in the presence of excess 5-amino-imidazole-4-carboxamide ribotide (AICAR) resulting in the appearance of approximately 1 mol of H2folate product for each mol of AICAR formylated. The present 10-HCO-H2folate preparation had a kinetic advantage over 10-HCO-H4folate resulting from a difference of approx. 5-fold in K(m) values when both folates were used as cofactors for Jurkat-cell and rat bone marrow AICAR T'ase. No substantial kinetic advantage was observed using chicken liver AICAR T'ase. 10-HCO-H2folate had little or no activity with Jurkat-cell or chicken liver glycinamide ribonucleotide transformylase (GAR T'ase, EC 2.1.2.2). The existence in vivo of 10-HCO-H2folate is suggested in mammals by several reports of detectable amounts of radiolabelled 10-HCO-folate in bile and urine after administration of radiolabelled folic acid.

Acyltransferases↗
PubMed1995

Unsaturated fatty acid effects on human breast cancer cell adhesion.

Polyunsaturated fatty acids influence several steps involved in metastasis formation in animal tumor models. During the process of metastasis from the primary site, tumor cells adhere to the endothelium and underlying basement membrane before extravasation and secondary growth. The purpose of this study was to determine the effect of unsaturated fatty acids on adhesion of human breast cancer cell lines to components of the basement membrane. Cells were cultured in low-serum medium for five days with or without added unsaturated fatty acids. Adhesion assays were conducted by incubating cells with basement membrane substrates coated on 96-well plates, washing to remove nonadherent cells, and staining adherent cells with crystal violet. Linoleic acid (LA) and eicosapentaenoic acid increased adhesion of the metastatic cell line MDA-MB-231 to Matrigel and type IV collagen, while eicosapentaenoic acid decreased adhesion of the less metastatic cell line SK-BR-3 to these two basement membrane substrates. Oleic acid increased adhesion of MDA-MB-231 cells to Matrigel and fibronectin. Nordihydroguaiaretic acid and high concentrations of indomethacin, each of which inhibits the lipoxygenase pathway of arachidonate metabolism, were effective in reversing the stimulatory effect of LA on MDA-MB-231 cell adhesion. A protein kinase C inhibitor likewise suppressed the increase in adhesion observed when MDA-MB-231 cells were incubated in media with added LA. Unsaturated fatty acids modified the adhesive properties of human breast cancer cell lines in vitro, and LA appeared to increase human breast cancer cell adhesion to extracellular matrix components by activating lipoxygenase and/or protein kinase C pathways.

Breast Neoplasms↗
PubMed1994

Chronological loss of bone zinc during dietary zinc deprivation in neonatal pigs.

This research was conducted to measure the chronological changes in zinc concentrations of biopsied bone, hair, and plasma samples collected weekly during dietary zinc deprivation. Pigs 1-2 wk of age were fed a basal diet (< 1 microgram Zn/g) during a 1-wk depletion period and then assigned to one of three dietary regimens for 4 wk: a low-zinc diet (4 micrograms Zn/g) fed ad libitum, an adequate-zinc diet (100 micrograms/g) fed ad libitum, and an adequate-zinc diet restricted in intake to allow eight gain comparable with that of the low-zinc group. Bone zinc remained at approximately 120 micrograms/g dry wt for the control groups fed adequate zinc but steadily declined in pigs fed the low-zinc diet, leveling off at approximately 25% of the control values. Plasma and hair zinc concentrations also decreased but at a more rapid rate. Bone zinc is mobilizable in neonatal pigs, and biopsied bone zinc concentration is a reliable index of zinc status.

Aging↗
PubMed1993

Multiple protein-binding domains and functional cis-elements in the 5'-flanking region of the human pyruvate dehydrogenase alpha-subunit gene.

We have characterized the 5'-flanking region of the alpha-subunit gene of the human pyruvate dehydrogenase (E1). DNase I footprinting with rat liver nuclear extracts identified 7 major protein-binding domains termed P1 through P7 in a 796 base pair DNA fragment (base pairs -763 to +33). P1 through P4 are clustered in the -221/+33 region. These protein-binding domains contain several known consensus sequences such as a TATA box, CAAT box, Sp1, and CRE, which all have previously been implicated in the constitutive transcription of several genes. Oligonucleotide competition studies indicate that oligonucleotides specific for CTF/NF-1 and Sp1 displaced the nuclear proteins bound to the CAAT box (within P3) and an Sp1 site (within P4), respectively. Several other well-characterized and purified transactivators (c-Fos, c-Jun, C/EBP, AP-2, and Sp1) have been shown to bind to the -221/+33 region. Other elements located upstream of the -221/+33 region, which includes nuclease protection domains P5-P7, are required for enhanced promoter activity of the 796 bp sequence. Promoter activity was measured by transient expression of a chloramphenicol acetyltransferase gene ligated to deletion fragments of the 5'-flanking region. Crucial element(s) for promoter activity and complex DNA-nuclear protein interactions were confined within a region spanning -221/+33. This region also retained more than 75% of the promoter activity of the 796 bp sequence. Additionally, this promoter region shows characteristics of both facultative and housekeeping gene promoters, suggesting complex transcriptional regulation.

Base Sequence↗
PubMed1993

Overview of pup in a cup model: hepatic lipogenesis in rats artificially reared on a high-carbohydrate formula.

The artificial rearing technique allows nutritional investigations to be conducted in rat pups during a critical period that previously has been inaccessible to researchers. The technique will be useful for identifying dietary components contributing to metabolic adaptations in the preweaning period as well as "metabolic imprinting" or permanent metabolic effects in adult rats resulting from early dietary intervention. Artificially reared rat pups fed a formula high in carbohydrate-derived energy in the preweaning period have the following characteristics compared with pups fed a high-fat formula or reared naturally: (i) a higher level of plasma insulin, (ii) an increased hepatic lipogenic capacity and (iii) precocious induction of hepatic malic enzyme. The results also show that early exposure to a high-carbohydrate diet in the preweaning period predisposes the rat to an increased lipogenic capacity in liver and adipose tissues and to the development of obesity later in adult life.

Animals↗
PubMed1993

Long-term effects of feeding high carbohydrate diet in pre-weaning period by gastrostomy: a new rat model for obesity.

In the present study, we report the long-term metabolic consequences of feeding a milk substitute formula that is high in carbohydrate-derived calories during the suckling period. Male Sprague-Dawley rat pups were raised by gastrostomy on a high carbohydrate (HC) formula or a high fat (HF) formula (which mimicked rat milk composition in macronutrients) during the pre-weaning period (day 4 to 24). These rats were then weaned to a laboratory stock diet and subsequently challenged with a high sucrose diet to augment the development of obesity. The pups receiving the HC formula developed obesity in later life, even though there was no change in the body weight of this group compared to mother-fed (MF) controls or HF formula fed animals during the pre-weaning period. The HC rats were hyperinsulinemic and their growth rates were greater than MF rats starting at day 55. The lipogenic capacity of liver as well as adipose tissues (epididymal and omental) was higher in HC animals compared to MF control animals, as reflected by increases in two key lipogenic enzymes (fatty acid synthase and glucose-6-phosphate dehydrogenase) and in vitro synthesis of lipids. An analysis of adipose tissue morphology in adult rats showed an increase in cell size in epididymal adipose tissue of HC rats compared to the MF group. However, there was no significant difference in cell size in omental adipose tissue between the MF and HC rats. The HF group behaved similarly to the MF control group in growth pattern and measured metabolic parameters.

Adipose Tissue↗
PubMed1992

Characterization of the transcriptional regulatory region of the human dihydrolipoamide dehydrogenase gene.

Dihydrolipoamide dehydrogenase (E3; EC 1.8.1.4) is the common component of the three mammalian alpha-ketoacid dehydrogenase complexes and the glycine cleavage system. To study regulation of E3 gene expression, a 12-kilobase clone from a human leukocyte genomic library was isolated, and a 1.8-kilobase fragment containing part of the first intron, the first exon, and 1.5 kilobases of the 5' flanking region of the E3 gene was sequenced. The nucleotide sequence of the E3 promoter region revealed consensus sequences for several DNA binding proteins but no apparent TATA box or Sp1 sites. Although the 1.6-kilobase 5' flanking region has a low percentage of G+C (44%), the nucleotide sequence between +1 and -150 base pairs has a G+C content of 67%. Primer extension analysis showed a major transcriptional start site located 95 nucleotides upstream from the translation initiation codon. A series of 5' deletions from the E3 promoter-regulatory region were ligated to the bacterial chloramphenicol acetyltransferase (CAT) gene, and the resulting constructs were transfected into HepG2 cells. The longest E3 promoter-CAT construct had a relatively high level of CAT enzyme activity, and deletion of a promoter element between -769 and -1223 base pairs resulted in a 3-fold increase in reporter gene expression. These results suggest that the human E3 promoter has characteristics of housekeeping and facultative promoters and that a negative regulatory element is present between 769 and 1223 base pairs upstream from the transcription start site.

Analysis of Variance↗
PubMed1990

Effect of zinc deficiency on enzyme activities in rat and pig erythrocyte membranes.

There is need for a reliable index of zinc status in humans. Considering the importance of zinc in membrane function, activities of erythrocyte membrane enzymes have been measured in animals of low and normal zinc status as possible indices. Immature rats and neonatal pigs were fed low and adequate zinc diets; the latter was fed both ad libitum and restricted so as to control for food intake effects. Low rates of gain and plasma zinc concentrations demonstrated that animals fed the low zinc diets were of low zinc status. Erythrocyte membranes were prepared and assayed for Na,K-ATPase, 5'-nucleotidase, and calcium-ATPase activities. Na,K-ATPase activity was not affected by zinc status, but 5'-nucleotidase was significantly lower in deficient animals of both species than in controls, whose food intake was restricted to maintain comparable weight (2.76 vs 3.94 nmol/hr/mg of protein in rats and 60.5 vs 119 in pigs). The basal calcium-ATPase activities were also decreased by low zinc status in both species. Addition of calmodulin in vitro stimulated activity two-fold to four-fold and resulted in the same maximal activities for all treatments. The results show that erythrocyte membrane 5'-nucleotidase activity is an index of zinc status in these species. It is suggested that the decreased membrane calcium-ATPase activity in zinc deficiency is caused by a defect in calmodulin metabolism.

5'-Nucleotidase↗
PubMed1989

Effect of zinc deficiency and food restriction in rats on erythrocyte membrane zinc, phospholipid and protein content.

Zinc deficiency in rats increases the osmotic fragility of erythrocytes, suggesting a structural defect in the plasma membrane. The purpose of this study was to determine the effect of zinc deficiency on membrane components that might be responsible for the increased fragility. Immature male rats were fed for 3 wk a zinc-deficient (0.5 mg Zn/kg) or a control (100 mg Zn/kg) diet either ad libitum or pair-fed. Red blood cell membranes were analyzed for zinc after wet ashing in nitric-perchloric acid. The fatty acid composition of membrane phosphatidylcholine and phosphatidylethanolamine was determined by gas-liquid chromatography, and the protein composition was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The membrane zinc concentration was decreased by zinc deficiency, but returned to control levels upon repletion with a zinc-adequate diet for 3 d. The increased osmotic fragility was also restored to the control level during the same repletion period, suggesting that zinc is an important determinant of membrane stability. The phospholipid fatty acid composition was altered by zinc deficiency, but these changes were not rapidly reversed by repletion. The membrane cholesterol:phospholipid ratio was also increased by zinc deficiency. Zinc status had no influence on the membrane protein profiles of the components visualized by staining. Only the concentration of membrane zinc correlated with osmotic fragility during zinc depletion and repletion.

Analysis of Variance↗
PubMed1984

Effect of dietary fiber on a guinea pig intestinal anaerobe, Bacteroides ovatus.

The purpose of this study was to determine the effect of fibrous plant components on the growth of intestinal bacteria. An anaerobe was isolated from the guinea pig cecum and identified as Bacteroides ovatus. The organism was grown anaerobically in two types of media and shown to require hemin or protoporphyrin IX. Treatment of the media with water-insoluble fractions of alfalfa, cabbage, spinach or wheat bran inhibited growth of the culture. Inhibition occurred whether the residue remained in the medium during culture growth or was removed before inoculation. A chelating resin also removed an essential component of the medium. Both treatments depleted the medium of hemin and addition of hemin restored growth and acid production. Treatment of the water-insoluble residues of alfalfa or cabbage with dilute NaOH decreased their inhibitory effects. This suggests that plant cell wall components possess unique and labile chemical properties. Dietary fiber may inhibit the growth of some anaerobic species in the lower intestinal tract by making hemin unavailable.

Animals↗
PubMedDate not supplied

Modulation of breast cancer cell adhesion by unsaturated fatty acids.

Triglycerides, which are major constituents of dietary fat, contain a mixture of saturated and unsaturated fatty acids. One newly recognized function of unsaturated fatty acids is modulation of cell adhesion to components of the extracellular matrix. Alterations in cell adhesiveness or cell adhesion molecule expression accompany the onset of a number of diseases including arthritis, atherosclerosis, and cancer. Cell adhesion is necessary for the metastatic spread of cancer cells to new organs. Circulating cancer cells adhere to endothelial cells and the underlying subendothelial basement membrane as an initial step in the process of invading target organs during metastasis. Several recent studies have provided convincing evidence that unsaturated fatty acids and their metabolites influence adhesion of cultured human cancer cells to individual components of the basement membrane. These unsaturated fatty acid effects appear to be dependent in some instances on the expression of specific cell surface adhesion molecules. Unsaturated fatty acids influence the development of metastases in animal tumor models by largely unexplored mechanisms; the possibility that cell adhesion is involved in this process has not been thoroughly investigated. Future studies of unsaturated fatty acid effects on cell adhesion molecule expression in breast cancer patients should reveal the clinical relevance of the studies reviewed here.

Breast Neoplasms↗
PubMedDate not supplied

Methylenetetrahydrofolate reductase (MTHFR) polymorphism increases the risk of cervical intraepithelial neoplasia.

Although cervical cancer is a common female cancer, little attention has been given to genetic susceptibility factors. The present case-control study was undertaken to examine MTHFR polymorphism as a potential molecular marker of cervical intraepithelial neoplasia (CIN) susceptibility and to relate the findings to smoking, HPV infection, ethnicity, parity and oral contraceptive use, which are known risk factors for cervical cancer. A base change from C to T at the nucleotide position 677 of the MTHFR gene results in substitution of valine (GTC) for alanine (GCC). The homozygous normal (Ala/Ala), homozygous mutant (Val/Val), and heterozygous mutant (Ala/Val) genotypes for the MTHFR gene were determined in cervical tissues of 64 cases of CIN lesions and 31 controls. The genotype frequencies of both Val/Val (17%) and Ala/Val (56%) were significantly higher in subjects with CIN lesions compared to controls with Val/Val (10%) and Ala/Val (39%), (trend p = 0.03). The results suggested a significantly increased CIN risk with an alanine to valine substitution at amino acid 223 of MTHFR with an odds ratio of 2.9 (95% confidence interval: 1.2-7.9, p = 0.02). Age, ethnicity, smoking and oral contraceptive use were weakly and nonsignificantly associated with CIN risk. HPV infection was associated with a statistically nonsignificant threefold increase in CIN risk. Parity and MTHFR genotype displayed a strong interaction. Neither nulliparous women with MTHFR polymorphism nor parous women without the polymorphism were at higher risk than women who did not have children and were MTHFR homozygous normal (the reference category). Women with mutant MTHFR genotype who had children, however, showed a significantly higher risk of CIN, with an odds ratio of 23 (95% confidence interval: 2.3-225) as compared to the reference category. No other factors displayed such a strong pattern of interaction. Since MTHFR polymorphism and pregnancy increases folate requirements and can impair folate status, this association could reflect an inadequate response of mutant MTHFR genotype carriers to the increased demand for folate imposed by pregnancy. Tissue folate deficiency, in turn, could increase the risk of CIN in the affected women.

Adult↗
PubMedDate not supplied

Effect of high retinoid doses on RAR-beta mRNA expression in female B6D2F1 mice.

The expression of retinoid receptors is altered during the development of several types of cancer. In the present study, we determined the influence of high dietary concentrations of 4-hydroxyphenylretinamide (4-HPR) and 13-cis-retinoic acid (13-cis-RA) on RAR-beta mRNA expression in female mice. Expression of liver and lung RAR-beta RNA increased with increasing levels of dietary retinoid (both 4-HPR and 13-cis RA). Bladder RAR-beta mRNA levels, however, were significantly decreased in mice fed 13-cis RA or 4-HPR. These results suggest that feeding high levels of retinoids to mice results in tissue-specific elfects on expression of RAR-beta mRNA.

Animals↗