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A W Steggles

Publications and source records attributed to A W Steggles.

At least 37 records · Page 2Linked to original sources
PubMed1988

The complete nucleotide sequence of human liver cytochrome b5 mRNA.

We have isolated and sequenced a cDNA clone corresponding to human liver cytochrome b5 mRNA. The 760 base pair (bp) sequence contains the complete coding and 3' non-translated regions plus 52 bp of 5' non-translated sequence. The derived amino acid sequence showed that the previous assignment of several amino acids was in error. In addition, the sequence of the previously unknown COOH hydrophobic region has been obtained.

Amino Acid Sequence↗
PubMed1988

The nucleotide sequence of rabbit liver cytochrome b5 mRNA.

Using a synthetic 26 base pair (bp) oligonucleotide, we have screened a rabbit liver cDNA library in lambda gt11 and isolated a 1000 bp DNA clone corresponding to cytochrome b5 mRNA. The clone contains the complete coding region and long 5' and 3' non-translated regions. The derived amino acid sequence (sequence; see text) agrees with published sequences, and confirms that the amino acids 62 and 104 are asparagine and aspartic acid, respectively.

Amino Acid Sequence↗
PubMed1986

Isolation and characterization of genomic clones for two chicken phenobarbital-inducible cytochrome P-450 genes.

A cDNA clone specific for a chicken phenobarbital-inducible cytochrome P-450 was used to screen a chicken genomic library. Twenty-nine clones were isolated, restriction mapped, and divided into two non-overlapping groups. The cDNA clone hybridized to 12 kilobases of DNA from both groups. Both groups contained restriction fragments which hybridized to both 5' and 3' fragments of the cDNA clone, and it was concluded that the two groups were derived from two separate genes. Southern transfer analysis of individual chicken DNAs and quantitative hybridization analysis indicated that these two genes are independent and are present as single copies/haploid genome. Comparison of restriction digests of the cloned DNAs and total genomic DNA discounted the possibility that other closely related P-450 genes are present in the chicken genome.

Animals↗
PubMed1986

Upper genital tract abnormalities in the Syrian hamster as a result of in utero exposure to diethylstilbestrol. II. Scanning electron microscope analysis of endometrium cell surfaces.

Using scanning electron microscopy (SEM), we show that an in utero exposure to diethylstilbestrol (DES) will induce endometrial abnormalities postnatally. These changes are magnified when a subsequent postnatal DES treatment is given. More specifically, changes in cell surface morphology are associated with alterations in cell size and shape (from columnar to cuboid/squamous), and in microvilli and mucus secretion. Uteri from hamsters treated postnatally with DES and derived from normal (CD) or DES-treated mothers (DD) show that accumulated mucoid secretion products are not expelled in the uterine lumen but are "stored" in cystic dilated glandular spaces of the fibrocellular stroma of polyps and papillae filling the uterine lumen. Uteri from female hamsters that have been prenatally treated with DES (DC) show endometrial mucosal crypts containing mucus and other cell debris including migrating granulocytes. In all cases, DES-treated uteri show mucosal cell surface pleomorphism in the sequence DD greater than CD greater than DC Merocrine and/or cystic secretions were observed. Microvilli cover cell surfaces and include some rare and peculiar long microvillous growth. In contrast, DC hypoplastic uteri present no secretory activity. Structures similar to those described for CD uteri can be observed only after 250 days of age in DC uteri. This report confirms and complements previous observations, favoring the choice of the hamster as an animal mode for the study of endometrial carcinogenesis.

Abnormalities, Drug-Induced↗
PubMed1985

Endometrium cell surface abnormalities in the Syrian hamster as a result of in utero exposure to diethylstilbestrol.

Scanning electron microscopy (SEM) was used to observe changes in the hamster endometrium cell surface following in utero pre- and/or postnatal exposure to diethylstilbestrol (DES). Some of the changes in cell surfaces are associated with alterations in cell sizes and shapes (from columnar to cuboidal and/or squamous) and in microvilli and mucous secretion. In all cases, DES treated uteri show mucosal cell surface pleomorphism, apocrine secretion and cystic accumulation of secretory material. Microvillous pleomorphism and peculiar linkages attaching one microvillus to others were investigated. Although the function and nature of such linkages is unclear, their presence seems to be more prominent in the in utero DES treated hamster endometrium. These infrastructures may provide a support for the microvilli distributed on the mucosal cell surfaces, i.e., a morphological compromise between the single microvillous surface and the microridged structures. These interconnections may represent glycocalyx material or remodeling of cell surfaces toward squamous epithelium.

Animals↗
PubMed1984

Changes in hamster liver albumin synthesis during the development of cardiomyopathy.

Control ( F1B ) and cardiomyopathic (Bio 14.6) hamsters have been studied over an 11 month time interval, in an attempt to relate alterations in liver function with the onset of progressive heart damage. In most instances the parameters measured (e.g., liver weight, liver polysome content, in vitro polysome driven protein synthesis) were similar for both groups of animals. The exceptions appeared to be two Bio 14.6 animals that had liver hypertrophy, coupled with severe necrosis and liver damage. These livers had very low levels of virtually inactive polysomes and depicted many of the histopathological characteristics of hepatic ischemic injury known in humans to be associated with congestive heart failure. Our biochemical and histological data suggests that for the Bio 14.6 hamsters, progressive cardiomyopathy is associated with severe liver damage for only a few animals.

Albumins↗
PubMed1983

Changes in cholecystokinin receptor binding in rat brain after food deprivation.

Levels of cholecystokinin (CCK) receptor binding in 7 brain regions were measured in two groups of adult male rats using iodinated CCK-8 as the radioligand. One group was deprived of food for 72 h prior to sacrifice and the other group had food available ad libitum. The deprivation resulted in a 13% decrease in body weight. In comparison to the ad libitum rats, the deprived group had a significantly lower level of CCK receptor binding in the olfactory bulb, and significantly higher levels of binding in the caudate nucleus, hypothalamus and midbrain. No significant differences were noted in samples of cerebral cortex, hippocampus or hindbrain. These results demonstrate that levels of CCK receptor binding can be altered by an acute change in the metabolic state of the animal.

Animals↗
PubMed1983

Identification and partial purification of hamster microsomal cytochrome P-450 isoenzymes.

We have identified and partially purified three forms of cytochrome P-450 from hamster liver microsomes. Phenobarbital (PB) treatment induced three major polypeptides with relative mobilities (Mr) of 47,000, 50,000 and 51,500. The 47,000 polypeptide was assigned as epoxide hydrolase, since it was also enhanced by trans-stilbene oxide (TSO) treatment. Two polypeptides (Mr = 48,500 and 53,500) were induced by both 3-methylcholanthrene (3-MC) and beta-naphthoflavone (BNF) treatments. Treatment with Aroclor 1254 induced three polypeptides (Mr = 48,500, 50,000 and 53,500), indicating the induction of both drug- and carcinogen-inducible cytochrome P-450s. Liver microsomal benzo[a]pyrene hydroxylase activity was not affected significantly by any of these inducers. In contrast, it was induced 2- to 3-fold in lung microsomes by 3-MC, BNF or Aroclor 1254 treatment. Benzphetamine N-demethylase and 7-ethoxycoumarin O-deethylase activities, expressed as nmoles of product formed per min per mg of liver microsomal protein, were increased 3- to 4-fold by either PB or Aroclor treatment. The activity of 7-ethoxycoumarin O-deethylase was the only one enhanced significantly by 3-methylcholanthrene or beta-naphthoflavone treatment in liver microsomes. Pregnenolone-16-alpha-carbonitrile (PCN) and TSO did not alter any of these activities. The major polypeptides induced by PB (Mr = 50,000) and 3-MC (Mr = 48,500 and 53,500 respectively) were partially purified, to a specific content of 6-10 nmoles P-450/mg of protein and were active in catalyzing N-demethylation of benzphetamine, hydroxylation of benzo[a]pyrene, and O-deethylation of 7-ethoxycoumarin with different substrate specificity. None of these isoenzymes immuno-cross-reacted with antibodies prepared against rabbit cytochrome P-450LM2 or P-450LM4.

Animals↗
PubMed1983

Species differences in cytochromes P-450 and epoxide hydrolase: comparisons of xenobiotic-induced hepatic microsomal polypeptides in hamsters and rats.

Cytochromes P-450 and epoxide hydrolase in hamsters were studied by using two-dimensional gel electrophoresis of hepatic microsomes from untreated animals and those treated with phenobarbital, 3-methylcholanthrene, beta-naphthoflavone, trans-stilbene oxide, and pregnenolone-16 alpha-carbonitrile. Coelectrophoresis with corresponding microsomes from rats and in situ peptide mapping were used to identify resolved microsomal polypeptides as cytochromes P-450 or epoxide hydrolase. Two forms of hepatic microsomal epoxide hydrolase were shown to exist in hamsters; these evidenced extensive structural homology with the corresponding enzyme in rats and were induced by the same xenobiotics. At least eight inducible polypeptides in microsomes from hamsters were tentatively identified as cytochromes P-450. Two of these were electrophoretically identical and structurally related with previously characterized forms of the enzyme in rats. Homologues of several major cytochromes P-450 induced by pregnenolone-16 alpha-carbonitrile and/or phenobarbital in the rat were apparently not present in the hamster. In most cases, putative forms of inducible cytochrome P-450 in the hamster existed at significant levels in microsomes from untreated animals whereas in rats the levels of most inducible forms of the enzyme were low in control microsomes, being more strictly dependent on xenobiotic pretreatment. In contrast with epoxide hydrolase, the molecular complexity of hepatic cytochrome P-450 seems to be comparable for rats and hamsters, but the structure and control of these hemoproteins appear to have markedly diverged.

Animals↗
PubMed1983

Characterization of cholecystokinin binding sites in rat cerebral cortex using a 125I-CCK-8 probe resistant to degradation.

Specific binding sites for cholecystokinin (CCK) have been characterized in a particulate membrane fraction of rat cerebral cortex using a biologically active 125I-labeled derivative of the C-terminal octapeptide of CCK (CCK-8) prepared by reaction with the iodinated form of the imidoester (125IIE), methyl-p-hydroxybenzimidate. The time course of binding to cortical membranes was rapid, temperature dependent, and saturable. Half-maximal binding at 24 degrees C was reached in 30 min and full binding at 120 min. At 37 degrees C there was only a slight increase in 125IIE-CCK-8 bound after 15 min. The addition of a large excess of CCK-8 after 30 min of binding at 24 degrees C caused a prompt and rapid decline in radioligand bound showing that the interaction was reversible. There was a progressive decline in the amount of 125IIE-CCK-8 bound to membranes with increasing concentrations of CCK-8 and other structurally related peptides. CCK-8 displaced 50% of the radioligand at 4 nM, CCK-33 at 10 nM, and gastrin (desulfated CCK-8) at 60 nM. Secretin, a structurally unrelated peptide, was unable to displace the radioligand from cortical membranes at 1.0 microM. Finally, 125IIE-CCK-8 exposed to cortical membranes or to buffers that had previously contained such membranes for 60 min at 24 degrees C bound equally as well to fresh cortical membranes as control radioligand that had not been exposed to the same conditions. Thus the 125I-CCK-8 radioligand used in this study was highly resistant to degradative processes in rat brain tissue.

Animals↗
PubMed1982

Alterations in the subcellular distribution of Guanylate cyclase and its responsiveness to nitric oxide in diethylstilbestrol-induced renal tumors.

The cyclic GMP content of diethylstilbestrol-induced renal tumors in the male golden hamster was increased nearly 130-fold over that in kidney from control animals. Cyclic GMP in tumors was 91.80 +/- 19.18 pmoles cyclic GMP/mg protein compared to 0.72 +/- 0.07 in control kidneys. Cyclic AMP in tumors was also increased over control, however, to a much lesser degree (2.7-fold). In control kidneys, 84.6% of homogenate guanylate cyclase activity was recovered in the 100,000 X g supernatant fraction. Total homogenate guanylate cyclase activity from diethylstilbestrol-induced renal tumors was increased 5.5-fold over that in control kidneys and only 8.1% was associated with the 100,000 X g supernatant fraction. Neither the soluble or particulate guanylate cyclase from renal tumors could be activated by nitric oxide. The unresponsiveness of tumor guanylate cyclase to nitric oxide was independent of the cation cofactor, and not due to a shift in the dose response curve for nitric oxide. Responsiveness to nitric oxide was not restored by thiols, sugars, other proteins, or hemoglobin. Basal cyclic AMP formation by soluble guanylate cyclase from renal tumors was dramatically increased over that observed in control kidneys, and could not be increased further by nitric oxide. This is the first study of cyclic GMP and guanylate cyclase in a primary estrogen-induced tumor. The possibility that the changes observed in guanylate cyclase from diethylstilbestrol-induced renal tumors are related to in vivo activation of the enzyme by epoxide metabolites of diethylstilbestrol is discussed.

Animals↗
PubMed1982

Upper genital tract abnormalities in the Syrian hamster as a result of in utero exposure to diethylstilbestrol. I. Uterine cystadenomatous papilloma and hypoplasia.

Prenatal exposure to diethylstilbestrol (DES) causes a significant increase in the carcinogenic response of the hamster's reproductive tract to subsequent DES treatment. Uteri from DES treated females from untreated- and DES treated mothers (C.D & D.D) have abnormal hyperplasia with characteristic finger-like structures projecting into the lumen of the uteri. Inside these papillae along with the rest of the stroma are cystic glands. We found that these glands had no openings into the uterine lumen and that they "begin" and "end" in the stroma. In addition there are two types of cells lining the cystic gland i.e., pale cells and acidophilic cells. Capillary beds surround the cystic glands. We have named these uterine structures "cystadenomatous papilloma". In addition, we found a spectrum of hyperplastic abnormalities in C.D and D.D uteri and carcinoma in situ in D.D uteri. Similar neoplasms have been described in human pathology. Ultrasound observations have demonstrated that in utero exposure to DES may result in uterine hypoplasia and because it appears to be similar to the changes seen in prenatally DES treated (D.C) hamsters, cross sectional areas of C.C (untreated control), D.C, C.D and D.D uteri were compared. Our results show that later in life uterine hypoplasia also occurs in the 100 days old D.C hamsters and since D.C uteri present hyperplasia with cystic structures, our data support the hypothesis that in utero DES-treated human females may later in life develop benign and malignant lesions in their reproductive tract. Much of these data corresponds to what has been found in humans, and consequently warrants further investigation into the use of Syrian hamster as a model to understand the uterine abnormal morphogenesis in regards to hypoplasia, adenocarcinoma and carcinoma development in the human.

Animals↗