Biomedical subjects

S J Skinner

Publications and source records attributed to S J Skinner.

At least 19 recordsLinked to original sources

PubMed2000

Intracerebral transportation and cellular localisation of insulin-like growth factor-1 following central administration to rats with hypoxic-ischemic brain injury.

Insulin-like growth factor-1 (IGF-1) has been shown to be neuroprotective when administered centrally following hypoxic-ischemic (HI) brain injury. However, the cerebral distribution and site of action of IGF-1 after intracerebroventricular (i.c.v.) administration are not known. A unilateral HI brain injury was induced in adult rats by a modified Levine method. Either 3H-IGF-1 alone, or in combination with unlabelled IGF-1, was administered into the lateral ventricle 2 h after injury. The activity of 3H-IGF-1 signal in the potentially injured cortex was compared between two treatment groups using image analysis. The regional distribution and cellular localisation of 3H-IGF-1 were examined autoradiographically in potentially injured hemispheres at 0.5 and 6 h after administration. Tritiated IGF-1 was detected predominantly in the pia mater, perivascular spaces and subcortical white matter tracts 0.5 h after administration and decreased by 6 h (p<0.05). The signals associated with the perivascular spaces and pia mater were not blocked by unlabelled IGF-1, suggesting non-saturable binding in these brain areas. IGF-1 signal was co-localised with IGF binding protein (IGFBP)-2 immunostaining in the white matter tracts where the signal was blocked by unlabelled IGF-1, suggesting competitive association. IGF-1 signal associated with neurons and glia was maximal in the cerebral cortex and less in the CA1-2 subregion of the hippocampus which were blocked by unlabelled IGF-1 (p<0.05). The signals from cortical neurons did not decrease 6 h after administration, suggesting specific and persistent binding to these cells. Our results indicate that centrally administered IGF-1 can be translocated to neurons and glia via the perivascular circulation and the ependymal cell-white matter tract pathways.

Animals↗

PubMed2000

Impaired insulin-mediated glucose uptake in monocytes of short children with intrauterine growth retardation.

AIMS: To determine whether there was an impairment in insulin-mediated glucose uptake in monocytes from short children with intrauterine growth retardation (IUGR) when compared with control subjects. METHODS: Circulating monocytes were isolated by histopaque gradient separation followed by adherence. Monocytes were incubated with insulin at the following concentrations; 0, 0.1, 0.2, 0.6, 1, 2 and 6 nm. 2-deoxyglucose (2-DG) uptake was measured after incubation with [(3)H]2-DG and expressed as pmol/min/10(6) cells. Insulin-stimulated glucose uptake was determined in two ways: 6 nm insulin concentration minus baseline (6-0 nm) and the regression slope of glucose uptake over the range of log insulin concentrations (slope value). Insulin sensitivity was determined from a 90-min frequently sampled intravenous glucose tolerance test with the minimal model. RESULTS: Short children with IUGR (n = 16) had lower slope (4.6 +/- 1.1 vs. 9.5 +/- 2.0, p = 0.002) and 6-0 nm (8 +/- 2 vs. 15 +/- 3 pmol/min/10(6) cells, p = 0.048) glucose uptake values than normal children (n = 11). There was no difference in baseline glucose uptake between IUGR and normal children (36 +/- 5 vs. 48 +/- 7 pmol/min/10(6) cells). In the five subjects with IUGR that were evaluated, the in vivo insulin sensitivity index and glucose effectiveness were found to be positively correlated with insulin-mediated glucose uptake in monocytes (r = 0.54) and baseline glucose uptake in monocytes, respectively (r = 0.69). CONCLUSIONS: Short children with IUGR have impairment in insulin-mediated glucose uptake in monocytes when compared with normal children. Our hitherto limited data indicate that insulin-mediated glucose uptake in monocytes is correlated with in vivo assessment of insulin sensitivity in children with IUGR.

Journal Article↗

PubMed2000

Immunohistochemical staining for Chlamydia pneumoniae is increased in lung tissue from subjects with chronic obstructive pulmonary disease.

The seroprevalence of Chlamydia pneumoniae is increased in chronic obstructive pulmonary disease (COPD), and subjects with COPD are more likely to have a positive polymerase chain reaction for C. pneumoniae in their sputum. It has been suggested that C. pneumoniae may have a role in the pathogenesis of COPD. We undertook immunohistochemistical staining for C. pneumoniae in archival tissue from subjects who had undergone lobectomy for bronchial carcinoma. There were 16 subjects with COPD (FEV(1) = 64 +/- 8% [mean +/- SD] predicted) and 21 subjects with normal lung function (FEV(1) = 95 +/- 11% predicted). There was no difference between the two groups in age or smoking history. Tissues from all of the subjects stained positively for C. pneumoniae, but in the subjects with COPD there were 14.5 positive cells per field (magnification x400), as compared with 9.3 cells per field in the control subjects (p = 0.02). Fifty-four percent of the macrophages from the subjects with COPD stained positively for C. pneumoniae, as compared with 29% from the control subjects (p < 0.001). A second control group consisted of 18 younger individuals (mean age: 32 yr) who died accidentally. Only 44% of these subjects had positive staining for C. pneumoniae, and the mean number of cells per field was 0.4. These findings suggest that persistent infection with C. pneumoniae is common, and that there is increased immunostaining for C. pneumoniae in COPD. Further studies are necessary to determine whether chronic infection with C. pneumoniae is important in the pathogenesis of COPD.

Adult↗

PubMed1999

Neuroprotective effects of Gly-Pro-Glu, the N-terminal tripeptide of IGF-1, in the hippocampus in vitro.

Insulin-like growth factor 1 (IGF-1) plays a critical role in CNS development. IGF-1 can block neuronal apoptosis in vitro and in vivo. IGF-1 is thought to be cleaved into des-N-(1-3)-IGF-1 and an amino terminal glycine-proline-glutamate (GPE tripeptide). Here we report a neuroprotective role for GPE tripeptide, with enhanced survival of the CA1-2 hippocampal neurons following an excitotoxic insult in vitro. Binding and displacement studies suggest uniquely distributed sites of action within the rat including the hippocampal CA1-2, pyriform cortex, amygdala, choroid plexus, blood vessels and to a lesser extent in the cortical regions. A similar pattern of binding was seen in the human. This finding could lead to new strategies to reduce neuronal death after injury and in disease.

Animals↗

PubMed1999

Key enzymes of prostaglandin biosynthesis and metabolism. Coordinate regulation of expression by cytokines in gestational tissues: a review.

Preterm labor is frequently associated with ascending intrauterine infection, accompanied by leukocytes infiltration and enhanced local production of cytokines and other inflammatory mediators. The resulting amplification of the inflammatory response, and of prostanoid production in particular, is postulated to be a principal mechanism of infection-driven preterm labor. In this review the effects of pro- and anti-inflammatory cytokines are discussed with respect to the expression of enzymes involved in three key steps of prostanoid biosynthesis and metabolism: liberation of arachidonic acid (AA), conversion of AA to bioactive prostanoids, and prostanoid catabolism. We suggest that by exerting coordinate actions on all three key steps, through multiple molecular mechanisms, inflammatory cytokines acutely up-regulate prostanoid production in intrauterine tissues.

Chorioamnionitis↗

PubMed1999

Effects of maternal captopril treatment on growth, blood glucose and plasma insulin in the fetal spontaneously hypertensive rat.

In the spontaneously hypertensive rat (SHR) fetal growth and metabolism are abnormal. It has been speculated that maternal hypertension may be the cause of these abnormalities. Captopril treatment, which reduces maternal blood pressure, during pregnancy and lactation, is reported to have a beneficial effect postnatally, normalizing the blood pressure of offspring in the SHR. In the present study, the effects of maternal captopril treatment on fetal growth and plasma metabolites were investigated in the fetuses of two rat strains (SHR and Wistar-Kyoto (WKY)), in order to determine whether normalizing maternal blood pressure also normalized abnormalities in fetal growth and metabolism. On fetal Day 20, SHR fetuses were lighter and placentae were heavier than for the corresponding WKY. Captopril had no effect on fetal weight in the SHR, but decreased it in the WKY. There was no effect of captopril on placental weight. Fetal plasma insulin levels were higher in the SHR than in the WKY and were decreased by captopril treatment in both strains. Fetal blood glucose was elevated and fetal blood lactate was decreased in captopril-treated litters from both strains. Captopril had no effect on fetal plasma IGF-1 but fetal plasma IGF-2 levels were lower in the captopril-treated SHR than in the captopril-treated WKY. These findings suggest that maternal captopril treatment decreases insulin secretion in the fetal rat. High levels of fetal plasma insulin suggest that the SHR fetus is insulin resistant. Fetal insulin levels may contribute to the adverse consequences of gestational captopril treatment observed in many species. The differences in the effect of captopril on the two strains suggest that there are underlying endocrine differences in the SHR.

Animals↗

PubMed1998

Glucocorticoid activity in the fetal spontaneously hypertensive rat.

Fetal exposure to high concentrations of corticosteroids in the rat is associated with elevated blood pressure in postnatal life. In this study we have investigated indicators of corticosteroid activity in fetal spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) in order to determine whether fetal corticosteroid exposure is increased in the SHR. Placental 11beta-hydroxysteroid dehydrogenase (11beta-HSD) activity, which prevents maternal steroids from crossing the placenta, was not impaired in the SHR. Concentrations of amniotic fluid corticosterone were significantly decreased in the SHR compared with the WKY at fetal Day 20, but were not significantly different on fetal Days 16 or 22. This suggests that rather than increased exposure to corticosteroids in the SHR fetus corticosteroid exposure may be reduced. Expression of lung surfactant protein A (Sp-A), a gene induced in late gestation by corticosteroids, was decreased in the SHR. In addition, differences in amniotic fluid electrolyte concentrations were observed which may reflect delayed renal maturation in the fetal SHR. These data suggest that the SHR fetus is exposed to low concentrations of corticosteroids and that the late gestation rise in fetal corticosteroid may be delayed in the SHR.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1998

Fetal rat lung epithelium has a functional growth hormone receptor coupled to tyrosine kinase activity and insulin-like growth factor binding protein-2 production.

Although growth hormone (GH) receptor (GHR) mRNA and protein are present in fetal tissues such as the lung, there is little evidence that GH mediates growth in the fetus. We have identified functional responses to GH in fetal rat lung epithelia and suggest a possible role for GHR in the developing lung. GHR mRNA in lung extracts was high before birth at day 16 of gestation (16f), decreased to low levels at day 22f but increased again after birth. At day 20f GHR mRNA levels were higher in lung than in liver, whereas growth hormone binding protein mRNA levels were approximately equal in lung and liver. Stimulation of primary cell cultures of day 19f lung epithelia with GH caused increased tyrosine phosphorylation in specific proteins, demonstrating functional GHR. Lung fibroblasts isolated at the same time did not respond to GH. Ligand and Northern blot analysis of the epithelial cultures revealed that GH stimulation increased insulin-like growth factor binding protein-2 (IGFBP-2) activity and mRNA. These experiments demonstrate the functional activity of GHR, specifically in fetal lung epithelium. We suggest that one role for GH in vivo may be indirectly to modify insulin-like growth factor activity in the developing fetal lung by increasing IGFBP-2.

Animals↗

PubMed1997

Perinatal growth disturbance in the spontaneously hypertensive rat.

Disproportionate fetal and placental growth are associated with the development of hypertension in the rat and human. Here we report differences in fetal, neonatal, and placental growth, and in metabolism and endocrinology, between the spontaneously hypertensive rat (SHR), a genetic model for human essential hypertension, and the control Wistar-Kyoto (WKY) strain. Gestation in SHR (23 d) was longer than in WKY by 20 h. Body weights were lower in the SHR from fetal d 16 to 20 and on postnatal d 15. However, on fetal d 22 and postnatal d 1, there was no significant difference in body weight between SHR and WKY. SHR placentas were larger than those of WKY at d 20, and by term there was a difference of 30% (p < 0.01). Other indices of disproportionate growth were hypertrophy of the fetal heart and kidney and decreased ponderal index in the SHR neonate. Blood glucose in SHR fetuses was lower than in WKY fetuses (p < 0.05), whereas blood lactate was higher (p < 0.05) and fetal hematocrit was reduced (p < 0.001). These findings suggest undernutrition and placental insufficiency may occur in SHR fetuses. Plasma IGF-II was increased on the last day of gestation in both strains, whereas IGF-I was unaltered. Fetal liver IGFBP-2 mRNA and plasma IGFBP-2 levels were reduced in SHR on fetal d 20 and 22 (p < 0.01). Differences in growth and endocrine and metabolic parameters suggest abnormal perinatal physiology in the SHR, which may influence the later development of hypertension.

Animals↗

PubMed1996

The movement of IGF-I into the brain parenchyma after hypoxic-ischaemic injury.

The movement of peptides from CSF into the parenchyma is thought to be slow and diffusion limited. However IGF-I can reduce neuronal loss at distal sites when given centrally 2 h after hypoxic-ischaemic (HI) injury. The present study determined the distribution of [3H]IGF-I given into the lateral ventricle after unilateral HI injury in adult rats. Radioactivity in the injured cortex peaked immediately after administration then rapidly declined. Autoradiography demonstrated radioactivity in the perivascular spaces and in the corpus callosum and external capsule of the injured hemisphere. HPLC and radioimmunoassay confirmed a rise in intracerebral IGF-I levels (from 159 +/- 9 to 401 +/- 88 ng g-1). These data suggest that injury can enhance the movement of IGF-I into the cerebrum via the white matter tracts and perivascular spaces.

Adult↗

PubMed1996

Cloning of novel kinectin splice variants with alternative C-termini: structure, distribution and evolution of mouse kinectin.

The analysis of cDNA clones encoding novel variant forms of mouse kinectin, an endoplasmic reticulum (ER)-bound receptor for the motor protein kinesin, is reported. Kinesin and cytoplasmic dynein are involved in mediating the anterograde and retrograde movements of intracellular vesicles along the microtubule network. The amino acid sequence deduced from kinectin cDNA isolated from mouse spleen cell and testis libraries revealed a long signal peptide or transmembrane sequence, and a 328 amino acid residue globular N-terminal domain adjacent to a much larger 858-999-residue C-terminal coiled-coil rod domain. The C-terminal domain was composed of 18 coiled-coil regions formed from multiple contiguous heptad repeats which undergo alternative splicing as evidenced by the presence of at least five small (23-33 amino acid residue) insertion sequences scattered throughout. The inserts are present in any one of a number of combinations, generating an array of novel kinectin variants. Insert 5 contains a termination codon, producing a C-terminus that is highly homologous to that of human kinectin. Three out of five mouse kinectin clones lack insert 5, generating a novel eleven amino acid C-terminus encoded by sequence that extends past the insertion site. The existence of alternative C-termini may have functional relevance given that the C-termini are exposed for interaction with kinesin, whereas the globular N-terminus is embedded in the ER membrane. Alternative C-termini represent candidate modifications that could determine specificity of binding to kinesin or cytoplasmic dynein, and the switching of directionality of movement. The cDNA hybridized to 4.5 kb transcripts expressed in all mouse cell lines and tissues examined, which provides the first indication that the kinectins are very widely distributed. Mouse kinectin is 42% similar over a 203 amino acid region to the chicken extracellular cardiac morphogen ES/130, whose canine homologue containing an inserted sequence of 10 amino acids repeated 54 times in tandem, is a ribosome receptor expressed on the ER. Mouse kinectin shares 64 and 83% identity, respectively, with its M(r) 160000 chicken and human kinectin homologues. There is a two-fold molar excess of kinectin over kinesin in unextracted vesicles, suggesting that kinectin might be a dimer. The electrostatic properties of the coiled-coil region of mouse kinectin, together with the relative frequencies of residues in particular positions within the heptad repeats support this notion.

Alternative Splicing↗

PubMed1996

Response of airway smooth muscle cells to TGF-beta 1: effects on growth and synthesis of glycosaminoglycans.

Transforming growth factor-beta (TGF-beta) is formed in the airways and may have a role in airway remodeling in asthma. We have studied the effects of TGF-beta on bovine airway smooth muscle cells (BASMC) in vitro. Thymidine incorporation by BASMC was inhibited after a 24-h incubation with TGF-beta 1. In contrast, thymidine incorporation by BASMC was stimulated (35.1 +/- 11.2%) after a 48-h incubation with 1 ng/ml TGF-beta 1. Cell number was also increased (25.9 +/- 7.6%) after a 72-h incubation with 3 ng/ml TGF-beta 1. TGF-beta 1 also increased cell size at 72 h, with a 24.3 +/- 6.2% increase in cell, diameter. Increases in BASMC size were accompanied by increased [3H]proline incorporation into cell protein. In cells from any individual animal, there was a strong inverse correlation (r = -0.97) between changes in cell number and cell size. In cells from some animals, the main effect of TGF-beta 1 was to promote an increase in cell number, whereas in others the predominant effect was cell hypertrophy. In contrast epidermal growth factor (EGF) led to an increase in thymidine incorporation and cell number in all preparations but did not increase cell size. TGF-beta 1 also promoted secretion of glycosaminoglycans into culture medium by BASMC with a preferential increase in hyaluronan secretion (4.5-fold) after 24 h. Latent TGF-beta (0.89 +/- 0.06 ng/ml) was also detected in conditioned medium from cultured BASMC, and TGF-beta 1 expression was demonstrated with RNA extracts from BASMC. Varying degrees of both smooth muscle cell hypertrophy and hyperplasia occur in asthma. These results obtained with airway smooth muscle cells indicate that TGF-beta could play a role in the structural changes seen in asthma.

Animals↗

PubMed1996

The effects of insulin-like growth factor (IGF)-1, IGF-2, and des-IGF-1 on neuronal loss after hypoxic-ischemic brain injury in adult rats: evidence for a role for IGF binding proteins.

Insulin-like growth factor (IGF)-1, IGF binding protein (IGFBP)-2, and IGFBP-3 are expressed in the rat brain in regions of neuronal loss by 3 days after hypoxic- ischemic (HI) brain injury and IGF-2 somewhat later. Central administration of rh-IGF-1 after HI injury reduces neuronal loss in vivo. To clarify the mode of action of IGF-1 and the potential role of IGFBPs, the effects of IGF-1, IGF-2, des(1-3)-N-IGF-1 (des-IGF-1), an analogue of IGF-1 with low affinity for IGFBPs, and IGF-1 combined with IGF-2 were compared 2 h after administration into the lateral cerebral ventricle after an HI injury. Unilateral HI was induced in adult rats by right carotid artery ligation followed by 10- min exposure to 6%O2. The extent of neuronal loss was determined in the cortex, striatum, hippocampus, dentate gyrus, and thalamus 5 days later. Central administration of 20 micrograms IGF-1 (n = 17) reduced neuronal loss in all regions (P < 0.01). Neither 20 micrograms IGF-2 (n = 17), 2 micrograms des-IGF-1 (n = 10), nor 20 micrograms des-IGF-1 (n = 17) reduced neuronal loss. There was a trend towards a reduction in neuronal loss after 150 micrograms des-IGF-1 (n = 20). IGF-2 alone increased neuronal loss in the hippocampus and dentate gyrus compared with the same regions in vehicle-treated animals (P < 0.05). Coadministration of 30 micrograms IGF-2 blocked the neuroprotective effects of 20 micrograms IGF-1 (n = 18, P < 0.05) and reduced the accumulation of [3H]IGF-1 in the injured hemisphere (n = 4) (P < 0.05). These observations suggest a role for IGFBPs in targeting the neuroprotective actions of IGF-1. IGF-2 may antagonize the protective effect of IGF-1 by displacing it from IGFBPs.

Animals↗

PubMed1995

Effects of glucocorticoids and beta-adrenoceptor agonists on the proliferation of airway smooth muscle.

An increase in airway smooth muscle is a characteristic feature of asthma. Because beta-adrenoceptor agonists and corticosteroids are commonly used in the treatment of asthma we have studied the effects of these medicines on the growth of airway smooth muscle. These agents were incubated with bovine airway smooth muscle cells for 40 h for measurement of thymidine incorporation and 64 h for measurement of cell counts. Salbutamol inhibited thymidine incorporation (IC50 = 60 nM) and led to a reduction in cell number (IC50 = 10 nM). At 10 microM there was a 14.6 +/- 2.6% reduction in cell number. Salmeterol also inhibited the growth of the airway smooth muscle cells but the effect did not plateau at 10 microM. At this concentration there was an 89.5 +/- 3.6% reduction in thymidine incorporation and a 44.1 +/- 5.2% reduction in cell number. Cortisol and beclomethasone dipropionate were more potent than salbutamol in inhibiting thymidine incorporation with IC50 values of 5 nM and 0.2 nM respectively. Cortisol 100 nM led to a 16.6 +/- 6.5% reduction and beclomethasone dipropionate 3 nM led to a 17.8 +/- 5.8% reduction in cell number. If similar effects occur in man and in vivo, these medicines could act directly on airway smooth muscle to inhibit the development of hyperplasia.

Adrenergic beta-Agonists↗

PubMed1995

Developmental changes in the expression patterns of IGFs, type 1 IGF receptor and IGF-binding proteins-2 and -4 in perinatal rat lung.

The insulin-like growth factors (IGF-I and IGF-II), their receptors and binding proteins (IGFBPs) are endogenously expressed in a number of tissues including the lung during fetal and neonatal development. This endogenous autocrine/paracrine IGF 'system', together with endocrine sources, contributes to the regulation of lung cell proliferation. We investigated the expression of the mRNAs encoding IGF-I, IGF-II, the type 1 IGF receptor (IGF-T1R) and two IGF-binding proteins (IGFBP-2 and IGFBP-4) in rat lung during the perinatum. These were compared in lung with surfactant apoprotein A (Sp-A) mRNA levels. mRNA in extracts of fetal tissues collected between day 17 of gestation (17f) and day 9 after birth (9d) was estimated by Northern blot or RNase protection analysis. At day 20 of gestation IGF-I, IGF-T1R and IGFBP-4 mRNA levels were higher in lung than liver (all P < 0.01), whereas IGF-II and IGFBP-2 mRNA levels were higher in liver than lung (each P < 0.02). The expression of IGF-1, IGFBP-2 and IGFBP-4 in lung was high before birth (days 17-20f) but decreased to low levels at days 21f, 22f or at birth (1d) but increased in the neonatal lung. IGF-II expression in lung was high at 17f but decreased before birth and remained low after birth. The IGF-T1R was expressed at moderate levels before birth, decrease before birth but peaked at days 2-5 after birth. The decrease in expression of these growth regulators before birth expression of these growth regulators before birth was matched by an increased in Sp-A expression which was clearly seen at day 20f, peaked at 1d and then was clearly seen at day 20f, peaked at 1d and then was maintained at high levels after birth. Primary cell cultures of 18f lung epithelia express IGFBP-2 while fibroblasts from the same animals express only IGFBP-4. Cells grown from 22f lung tissue express IGFBP-2 and IGFBP-4 at lower levels, behaving in vitro as they do in vivo. The contrasting levels of expression of different components of the IGF system in the fetal lung and liver indicate organ-specific regulation. IGFBP-2 and IGFBP-4 expression in different cell types within lung but with similar temporal changes suggests cell-specific regulation, perhaps by a common agent. The patterns by a common agent. The patterns of expression of IGF-I, IGF-T1R, IGFBP-2 and IGFBP-4, but not IGF-II, in developing lung correspond to previously described phasic changes in lung cell proliferation rates. The nadir in expression of these four major components of the lung IGF system occurs in the saccular phase when the lung begins to differentiate, probably under the influence of certain endocrine agents.

Aging↗

PubMed1994

The relationship of urinary and plasma androgens to steroid receptors and menopausal status in breast cancer patients and their influence on survival.

The relationships between urinary 11-desoxy-17-oxo steroids (11-DOS), the ratio of 11-DOS to urinary 17-hydroxycorticosteroids (urinary discriminant ratio), plasma levels of the adrenal androgens dehydroepiandrosterone (DHA), DHA sulphate (DHAS), and 7 alpha-hydroxy DHA (7 alpha DHA), and tumour oestrogen receptor (ER) and progesterone receptor (PR) status were examined in pre, peri-, and postmenopausal women with breast cancer. Androgenic steroids and their metabolites decreased with age in women with breast cancer. In perimenopausal women there was a significant association of PR positive tumours and high androgen levels, whereas in postmenopausal women high androgen levels were associated with ER negative tumours. Survival was significantly related to plasma DHA level and tumour steroid receptor status. Thus, adrenal androgen levels below the group mean were associated with significantly decreased survival in women with postmenopausal receptor-positive tumours, and the association was particularly apparent in those who were axillary node negative. Since the number of patients studied was small these results should be regarded as provisional in nature. Nonetheless, the identification of this subgroup of node negative breast cancer women with reduced survival may be important when considering node negative patients for adjuvant therapy.

17-Hydroxycorticosteroids↗

PubMed1992

The effects of mechanical stretching on fetal rat lung cell prostacyclin production.

A model system was used to determine the effect of stretch on prostacyclin (PGI) production by organotypic fetal rat lung cultures grown on gelatin foam in vitro, measured by RIA of 6-keto-PGF1 alpha (6KF) in the culture medium. The stretching apparatus was programmable for stretch of varying frequency and duration. The effective stimuli for PGI production were: continuous pulsatile stretch greater than intermittent pulsatile stretch greater than permanent stretch (p less than 0.05). The rate of PGI production was greatest in the first 15 min of pulsatile stretch and was associated with a 70% increase in cAMP production (p less than 0.05). When the effect of magnitude of stretch was compared (15% vs 28% extension), there was a significant increase with a maximum in the 28% stretch group double that of the 15% stretch group (p less than 0.01). PGI production in response to pulsatile stretching was inhibited by indomethacin but not by pretreatment with cortisol. These results suggest that the production of PGI by lung cells may be significantly affected by the frequency and magnitude of pulsatile stretching.

Animals↗

PubMed1992

Stimulation of fetal rat lung cell proliferation in vitro by mechanical stretch.

On the basis of in vivo animal studies and on experiments of nature, it has been suggested that fetal breathing movements are essential for normal lung growth in utero. To study this hypothesis in vitro, we examined the effect of mechanical stretch on proliferation of fetal rat lung cells maintained in organotypic culture to provide a three-dimensional matrix. Initial studies demonstrated that stretch-mediated effects on cell division and DNA synthesis in such cultures were influenced by cell inoculation density, fetal calf serum concentration, and by the amplitude, frequency, periodicity, and duration of the applied stretch. After a 48-h exposure to an intermittent stretch pattern (5% elongation, 60 stretches/min for 15 min of each hour), cell number increased 10% (P less than 0.05), cell doubling time was reduced from 71 to 55 h (P less than 0.05), [3H]thymidine incorporation into DNA increased 61% (P less than 0.01), and the [3H]thymidine-labeling index increased 2.8-fold (P less than 0.001) compared with nonstretched controls. This effect did not appear to be mediated by prostaglandins or leukotrienes because the prostaglandin synthase inhibitors ibuprofen (2.5-50 microM) or BW 755C (5 microM), leukotriene biosynthesis inhibitors BW 755C (5 microM) or MK-886 (0.3 microM), and leukotriene D4 receptor antagonist MK-571 (0.3 microM) did not block stretch-mediated effects. We conclude that mechanical forces act directly to stimulate fetal rat lung cell growth and that these results are compatible with a significant role for fetal breathing in normal fetal lung growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗