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Biomedical subjects

S K Smith

Publications and source records attributed to S K Smith.

At least 163 records · Page 9Linked to original sources
PubMed1992

Presence of messenger ribonucleic acid for endothelin-1, endothelin-2, and endothelin-3 in human endometrium and a change in the ratio of ETA and ETB receptor subtype across the menstrual cycle.

The aim of the present study was to determine whether mRNA for the three endothelin peptides (endothelin-1, endothelin-2, and endothelin-3) and the two known receptor subtypes (ETA and ETB) was present in human endometrium at different stages of the menstrual cycle (menstrual, early and mid-proliferative, and early, mid-, and late secretory). Endometrium was obtained from women undergoing surgery for benign disease, and total RNA was extracted using a guanidinium isothiocyanate method. mRNA for endothelin peptide and receptor was detected using the reverse transcriptase-polymerase chain reaction with nested oligonucleotide primers. mRNA for endothelin-1, endothelin-2, and endothelin-3 was demonstrated throughout the menstrual cycle, and three splice variants of mRNA encoding endothelin-3 were found in all samples. The ratio of ETA to ETB receptor mRNA was found to change throughout the menstrual cycle. In the proliferative phase, amplified cDNA product was almost exclusively confined to the ETA receptor, whereas an increase in the amplified product of the ETB receptor cDNA was seen in the secretory and menstrual phases. These studies show that mRNA for endothelin-1, endothelin-2, and endothelin-3 is present in human endometrium at all stages of the menstrual cycle and suggest that different physiological actions of the endothelin peptides may be mediated through changes in the ratio of the ETA and ETB receptor subtypes.

Base Sequence↗
PubMed1992

Expression of messenger RNA for kit-ligand in human placenta: localization by in situ hybridization and identification of alternatively spliced variants.

Kit-ligand is a novel polypeptide growth factor which binds and activates the c-kit protooncogene, a receptor tyrosine kinase. We used the technique of reverse transcription-polymerase chain reaction to demonstrate the expression of this growth factor in human placenta. In situ hybridization showed that kit-ligand mRNA is expressed in cytotrophoblast and syncytiotrophoblast cells in the placenta, and in fetally derived extravillous trophoblast cells which have invaded the maternal endometrium. Five species of mRNA encoding variants of kit-ligand were identified by nested reverse transcription-polymerase chain reaction. Cloning and sequencing indicate that these variants arise by alternative splicing of the kit-ligand transcript. One of these species, KL486, uses a novel splice site in exon 8. There is a different pattern of expression of the variants in amnion, chorion, trophoblast, and placenta, indicating tissue-specific control of splicing.

Alternative Splicing↗
PubMed1992

Endothelin-like immunoreactivity in human endometrium.

Endothelin-like immunoreactivity (ET-IR) was detected immunocytochemically in glandular epithelium and vascular endothelium of human endometrium and myometrium. Primary antibody was raised in rabbits against the carboxy-terminal heptapeptide of endothelin 1 (ET-1), ET-1(15-21), and compared with antibodies raised against the cyclized amino-terminal, ET-1(2-13), and commercially obtained antibodies against the whole ET-1 or ET-3 molecule. Binding was visualized using the peroxidase technique in sections counter-stained with haemalum. Staining was seen in each of 15 sections from eight women in the proliferative (five) or secretory (three) phase of the cycle. Intense staining was present in the cytoplasm of endometrial glands and vascular endothelium, and was greatest at the endometrial-myometrial junction. The pattern of staining was similar with all primary antibodies tested. The demonstration of ET-IR in endometrium suggests that the endothelins may play a role in control of the uterine vascular bed.

Endometrium↗
PubMed1992

Activation of phospholipase A2 and phospholipase C by endothelin-1 in human endometrium.

Human endometrium contains specific binding sites for iodinated endothelin (ET)-1, ET-2 and ET-3, and ET-1 stimulates prostaglandin (PG) F2 alpha synthesis from explants of proliferative endometrium in short-term culture. This study has investigated the cellular responses of normal proliferative endometrium to ET-1. Radioimmunoassay was used to measure PG release and Dowex anion-exchange column chromatography was utilized to assess the accumulation of inositol phosphates. Endothelin-1 induced a significant increase in PGF2 alpha release (basal median: 1465 pg/mg per 60 min (range: 541-3935 pg/mg per 60 min); ET-1-stimulated: 1813 pg/mg per 60 min (1021-5714 pg/mg per 60 min); P < 0.04 using Wilcoxon signed rank test). The effect of ET-1 was attenuated in the presence of the phospholipase A2 inhibitor quinacrine. Endothelin-1 induced a rapid, transient and concentration-dependent hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2), measured by the accumulation of tritiated inositol phosphates. Following a 1-min stimulation with ET-1 (100 nmol/l), [3H]inositol mono-, bis- and trisphosphate fractions increased from median values of 490.0 d.p.m./mg dry wt (range: 348.0-807.0 d.p.m./mg dry wt), 120.0 d.p.m./mg dry wt (93.6-144.1 d.p.m./mg dry wt) and 67.0 d.p.m./mg dry wt (54.2-85.0 d.p.m./mg dry wt) to 939.0 d.p.m./mg dry wt (635.9-1596.0 d.p.m./mg dry wt; P < 0.03), 145.0 d.p.m./mg dry wt (127.0-293.9 d.p.m./mg dry wt; P < 0.05) and 146.0 d.p.m./mg dry wt (77.5-187.0 d.p.m./mg dry wt; P < 0.03) respectively. These results suggest that ET-1 activates the phospholipase A2 and PtdIns(4,5)P2-specific phospholipase C in human proliferative endometrium, resulting in the generation of PGF2 alpha and second messengers respectively which are pivotal to endometrial function.

Endometrium↗
PubMed1992

An evaluation of population forecast errors for Florida and its counties.

The authors evaluate the forecasting accuracy of population projections formulated at state and county levels for Florida. They find that "projections of Florida population made in the 1970s and 1980s had errors...of approximately 2-3 percent for 5-year horizons, 5-6 percent for 10-year horizons and 8-9 percent for 15-year horizons. County projections had errors averaging approximately 5, 10 and 15 percent for these three lengths of horizon, respectively. Based on comparisons with other studies of state and substate population projections, we believe this is a good record of forecast accuracy...."

Americas↗
PubMed1991

The mechanisms of action of progesterone and the anti-progestin ZK 98734 on PGF2 alpha synthesis by early human decidua.

The inhibition of prostaglandin (PG) synthesis found in early human decidua is antagonized by the anti-progestin, ZK 98734. This action of ZK 98734 is abolished by actinomycin, an inhibitor of protein synthesis and by the calcium channel blocker, verapamil. Calmidazolium, an antagonist of the intracellular calcium binding protein calmodulin was less effective in inhibiting the stimulation of PG synthesis induced by the anti-progestin. Chronic stimulation of protein kinase C activity by 1-oleoyl-2-acetyl-sn-glycerol (OAG) induced a slight reduction of PG release and was antagonized by polymixin. These findings suggest that inhibition of PG synthesis in early pregnancy is caused by progesterone and that increased release of PGs induced by anti-progestins is dependent on new protein formation and requires extracellular calcium.

Abortion, Spontaneous↗
PubMed1991

Endothelin-1 stimulates prostaglandin F2 alpha release from human endometrium.

Despite a key role in the pathogenesis of menorrhagia, the factors controlling the uterine vascular bed are poorly understood. This study has assessed the effects of the potent vasoconstrictor endothelin (ET)-1 on prostaglandin (PG) release from human endometrial explants in short-term culture. There was no significant difference between the production of PGF2 alpha in proliferative and secretory tissue (1709 and 2434 pg/mg/h--median values, range 70,3745 and 219,6700 pg/mg/h). Less PGE was released than PGF2 alpha, and the amount did not vary with the phase of the menstrual cycle (308 and 296 pg/mg/h (range 65,387 and 105,429) for proliferative and secretory tissue). ET-1 (10 and 100 nM) and arachidonic acid (AA, 30 microM), stimulated PGF2 alpha release from proliferative, but not secretory endometrium, by 78%, 86% (P less than 0.01) and 80% respectively, compared with control tissue. No effect was seen on PGE release. ET-1 may play a role in the local control of the endometrial vascular bed either directly, or via the release of PGF2 alpha.

Adult↗
PubMed1991

Epidermal growth factor in human endometrium: proliferative effects in culture and immunocytochemical localization in normal and endometriotic tissues.

Endometrial proliferation is stimulated by oestradiol. The precise mechanism is poorly understood, but may be mediated by epidermal growth factor (EGF). The aim of the present study was to assess the effects of oestradiol and EGF on glandular and stromal proliferation in human endometrial cell cultures, and to determine the localization of EGF-like immunoreactivity (EGF-IR) using immunocytochemistry in normal and endometriotic tissue. Endometrium was obtained from women undergoing curettage or hysterectomy for benign disease, or laparoscopy for endometriosis. For tissue culture experiments, enriched glandular and stromal cells were prepared by digestion with collagenase and DNAase, and cultured for 4 days with oestradiol or EGF, both alone and in combination. Immunocytochemical studies were performed using sheep primary antibody against EGF, with binding visualized using the unlabelled antibody--enzyme method. In combination, oestradiol and EGF increased mean cell counts from 1.15 +/- 0.06 and 1.36 +/- 0.05 x 10(5)/ml to 1.68 +/- 0.1 (+46%) and 1.94 +/- 0.16 (+43%) x 10(5)/ml, in proliferative and secretory gland preparations respectively (n = 10, P less than 0.01). No effect was seen in stromal cell preparations; however the stimulation in gland preparations was further augmented after the addition of stromal-conditioned medium. EGF-IR was detected in endometrium from normal women, and in normal and ectopic endometrium from women with endometriosis. EGF-IR was seen in glands and stroma and was not related to the phase of the menstrual cycle. EGF may play a role in the oestrogen-stimulated proliferation of normal and endometriotic endometrium.

Animals↗
PubMed1991

Evaluation of the genus Listonella and reassignment of Listonella damsela (Love et al.) MacDonell and Colwell to the genus Photobacterium as Photobacterium damsela comb. nov. with an emended description.

The genus Listonella, which was recently described on the basis of 5S rRNA sequence data, was found to be of dubious value on the basis of the results of a comparison of a number of taxonomic studies involving members of the Vibrionaceae. The available data suggest that 5S rRNA sequences may be of limited taxonomic use at the intra- and intergeneric levels, at least for apparently recently evolved groups, such as the Vibrionaceae. In this light, we assessed the generic assignment of the species Listonella damsela. Phenotypic characterization of 12 strains of bacteria assigned to L. damsela, including type strain ATCC 33539, revealed a strong resemblance to members of the genus Photobacterium. All of the strains conformed to major characteristics common to all known Photobacterium species. The characteristics of these organisms included the absence of a flagellar sheath and accumulation of poly-beta-hydroxybutyrate during growth on glucose coupled with the inability to utilize DL-beta-hydroxybutyrate as a sole carbon source. On the basis of the phenotypic data, we propose that L. damsela should be reassigned to the genus Photobacterium as Photobacterium damsela comb. nov.

Animals↗
PubMed1991

Identification of mRNA for epidermal growth factor and transforming growth factor-alpha present in low copy number in human endometrium and decidua using reverse transcriptase-polymerase chain reaction.

The presence of mRNA for epidermal growth factor (EGF) and transforming growth factor-alpha (TGF alpha) was demonstrated in small fragments of human endometrium and decidua by use of the technique of reverse transcriptase-polymerase chain reaction with nested oligonucleotide primers. The presence of mRNA encoding EGF and TGF alpha has not been shown in human endometrium previously. Other studies using conventional techniques, such as Northern blot or in-situ hybridization, showed the presence in low copy number of EGF but not TGF alpha in murine endometrium. Messenger RNA for EGF was not present in peripheral leukocytes or platelets, suggesting an endometrial source for the message. Messenger RNA for TGF alpha was found in these blood components, thus preventing confirmation of the source of TGF alpha mRNA.

Base Sequence↗
PubMed1991

Binding sites for iodinated endothelin-1, endothelin-2 and endothelin-3 demonstrated on human uterine glandular epithelial cells by quantitative high-resolution autoradiography.

Quantitative in-vitro receptor autoradiography has been used to localize and compare the anatomical distribution of binding sites for iodinated endothelins (ET-1, ET-2 and ET-3) in human uterus. Binding sites for the three iodinated isoforms had a similar gross anatomical distribution. The density of binding sites was significantly higher in the endometrium compared with the myometrium and greatest at the endometrial-myometrial junction. In cross-competition experiments, unlabelled ET-1, ET-2, ET-3, sarafotoxin S6b and mouse vasoactive intestinal contractor (1 mumol/l) competed for the binding sites of all the iodinated peptides suggesting that ETs may bind to the same receptor. However, preproendothelin(110-130) (endothelin-like peptide) or preproendothelin(124-130) and other non-endothelin vasoactive peptides tested as a concentration of 1 mumol/l did not compete. Micro-autoradiography revealed that high densities of iodinated ET-1, ET-2 and ET-3 binding sites were localized to glandular epithelial cells and blood vessels with lower levels in the myometrium and vascular smooth muscle, suggesting that these potent vasoactive and proliferative agents could play a role in the control of menstruation.

Adult↗
PubMed1991

Localization and endogenous concentration of endothelin-like immunoreactivity in human placenta.

The aim of this study was to investigate the localization of endothelin-like immunoreactivity (ET-IR) in human placenta, chorion and amnion and to compare the endogenous concentration of immunoreactive endothelin (ET) in these tissues before and after the onset of labour. ET-IR was detected in the endothelium of stem vessels in placental villi, as well as in decidual stromal cells in the basal maternal plate, by immunocytochemistry using primary polyclonal rabbit antibody. A specific radioimmunoassay was used to detect endogenous concentration of ET in homogenized placental tissues. The endogenous concentration of ET-IR was significantly greater in amnion than in chorion and placenta (amnion 249 +/- 13 fmol/g; chorion 190 +/- 11 fmol/g; placenta 169 +/- 14 fmol/g; means +/- S.E.M.; n = 12; P less than 0.01). No significant difference was seen before or after the onset of labour. The detection of ET-IR in placenta, chorion and amnion suggests that the ETs may play a role in the paracrine control of human uterine function.

Amnion↗
PubMed1991

An empirical analysis of the effect of length of forecast horizon on population forecast errors.

Many studies have found that population forecast errors generally increase with the length of the forecast horizon, but none have examined this relationship in detail. Do errors grow linearly, exponentially, or in some other manner as the forecast horizon becomes longer? Does the error-horizon relationship differ by forecasting technique, launch year, size of place, or rate of growth? Do alternative measures of error make a difference? In this article we address these questions using two simple forecasting techniques and population data from 1900 to 1980 for states in the United States. We find that in most instances there is a linear or nearly linear relationship between forecast accuracy and the length of the forecast horizon, but no consistent relationship between bias and the length of the horizon. We believe that these results provide useful information regarding the nature of population forecast errors.

Humans↗
PubMed1990

Effect of methionine oxidation and deletion of amino-terminal residues on the conformation of parathyroid hormone. Circular dichroism studies.

Circular dichroism (CD) studies of parathyroid hormone (PTH), its oxidized forms, and some fragments of the hormone are described. The CD spectrum of native PTH (84 amino acids) and the active fragment, 1-34 PTH, suggests that most of the secondary structure resides in the amino-terminal segment of this hormone. Oxidation of the methionine residue at position 18 has a small impact on secondary structure, whereas oxidation of the methionine at position 8 produces substantial changes. Oxidation of both methionines produces secondary structure changes that are greater than the sum of those seen upon oxidation of the individual methionines. The CD spectrum for the 3-34 fragment of PTH is identical to that of the 1-34 fragment, and that of the 7-34 fragment is only slightly different. The spectra of the 13-34 and 19-34 fragments are markedly altered from that of the 1-34 peptide, and those of the 9-84 and 19-84 fragments of native PTH are significantly different from the intact hormone. Computer-assisted estimates of secondary structure content, and difference spectra, were utilized to evaluate the secondary structure content of the peptides. These results suggest that residues 6-12 are important in formation of helical secondary structure and that a reverse turn may be important for the folding of PTH into a conformation with high affinity for receptors. Residues 1 and 2 appear to make no contribution to the secondary structure and may be directly involved in activation of receptors.

Animals↗
PubMed1990

Is genetic code redundancy related to retention of structural information in both DNA strands?

We have noted that the sense-antisense relationships inherent in the genetic code divide the amino acids into three separate groups. The nature of the amino acids in each group may allow the polypeptides coded by the antisense strand to retain the secondary structure patterns of the translated strand. Also, this relationship requires all but eight of the codons in the eukaryotic code and all but four in the mitochondrial code. Thus, genetic code redundancy could be related to evolutionary pressure toward retention of protein structural information in both strands of DNA.

Amino Acids↗
PubMed1990

Long-term suppression of ovarian function by a luteinizing-hormone releasing hormone agonist implant in patients with endometriosis.

Ten endometriosis patients received luteinizing hormone releasing hormone (LH-RH) agonist (buserelin) implant injections (6.6 mg subcutaneously) at days 0, 42, 84 and 126. Serum LH and follicle-stimulating hormone (FSH) were lowered by day 14. Luteinizing hormone remained at basal concentrations while FSH returned to values in the low-normal range of the menstrual cycle by day 35. At the end of the luteal phase during which treatment commenced, estrone and pregnanediol declined and remained at postmenopausal or early follicular phase values until days 305 to 460. Time to first ovulation ranged from 321 to 481 days after starting treatment. After the initial menstruation, only three instances of bleeding occurred during treatment. Pelvic pain was relieved or markedly reduced by day 42 and remained absent throughout the period of ovarian suppression. These results indicate the potential of a long-acting LH-RH agonist implant to form the basis for the treatment of symptomatic endometriosis.

Administration, Intranasal↗