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Biomedical subjects

R Strange

Publications and source records attributed to R Strange.

At least 37 records · Page 2Linked to original sources
PubMed1995

Treatment with chemopreventive agents, difluoromethylornithine and retinyl acetate, results in altered mammary extracellular matrix.

The effect of treatment with D-L-2-difluoromethylornithine (DFMO) plus retinyl acetate (RA) on the promotion stage of 1-methyl-1-nitrosourea (MNU)-induced mammary carcinogenesis was evaluated in female Sprague-Dawley rats. Combined treatment was more effective than single agent treatment in decreasing cancer incidence and multiplicity and in prolonging cancer latency. Increased efficacy was associated with reduced morphological complexity of the gland and increased mammary extracellular matrix. Using ovarian hormones to model mitogen stimulation in the mammary gland, DFMO plus RA treatment reduced mammary gland complexity in the absence of an effect on bromodeoxyuridine (BrDU) labeling index measured immunohistochemically. Morphological and biochemical evaluation of these glands revealed increased levels of extracellular matrix in rats treated with chemopreventive agents. Tenascin expression and fibronectin levels were elevated and laminin levels were decreased. The fact that matrix degrading proteinase activity was also increased indicated that tissue remodeling was modulated by these chemopreventive agents. These data provide evidence of alterations in epithelial cell-extracellular matrix interactions that could account in part for the chemopreventive effects of DFMO plus RA.

Animals↗
PubMed1995

Serum squamous cell carcinoma antigen: a potential marker for benign vulval disease?

Benign vulval disease comprises a variety of disorders and can affect women of all ages. To date, the optimal management of these conditions has been uncertain and not subjected to a systemic prospective approach. It is recognized that benign vulval disease has a potential premalignant potential. Squamous cell carcinoma antigen (SCCA) has shown in different studies to be an effective means of monitoring the course of the disease in cervical carcinoma. Elevated levels of SCCA have been found in the skin. In addition, raised SCCA levels have been found in non-carcinomatous inflammatory dermatoses, and the levels observed correlated with the extent of the disease and the response to therapy. It was thought that SCCA might prove to be a useful marker for benign vulval disease, and in our pilot study the objectives were to determine if levels of SCCA are elevated in patients with that disease and to assess whether there is an association between SCCA and clinical response to treatment.

Antigens, Neoplasm↗
PubMed1994

Expression of stromelysin-1 and TIMP-1 in the involuting mammary gland and in early invasive tumors of the mouse.

The mammary gland, during post-lactational involution, is subjected to extensive tissue reconstruction. This process is governed by the concerted expression of extracellular-matrix-degrading enzymes and their inhibitors. During carcinogenesis, the invasive growth of tumor cells is characterized by the penetration of the basement membrane and stromal invasion. We compared the expression of the tissue-remodeling enzymes stromelysin-1, a matrix metalloproteinase, and its inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), during mammary gland involution and carcinogenesis in mouse. In involuting mammary glands, stromelysin-1 was expressed in myoepithelial cells, whereas TIMP-1 was confined to the stromal tissue. To analyze the involvement of these tissue-remodeling genes in tumor development, we examined mammary tumors of transgenic mice expressing either the activated Ha-ras or c-myc oncogene under the control of a milk-protein gene promoter. In the undifferentiated and metastasizing Ha-ras-induced tumors, stromelysin-1 expression was comparable to that seen in involution, whereas TIMP-1 expression was greatly elevated. During Ha-ras-induced carcinogenesis, stromelysin-1 expression was first detected in the myo-epithelial cells surrounding preneoplastic lesions. In contrast, in the well-differentiated and non-metastatic mammary tumors induced by c-myc, no expression of either gene was observed. Thus, expression of stromelysin-1 and TIMP-1 is confined to the aggressively growing tumors and is induced in the earliest stages of carcinogenesis.

Animals↗
PubMed1994

Cloning, expression, and purification of a functional nonacetylated mammalian mitochondrial chaperonin 10.

An intact mouse mitochondrial chaperonin 10 has been cloned, sequenced, and overexpressed in Escherichia coli as a fusion protein harboring an oligohistidine tail at its COOH terminus. The latter was added to simplify protein purification. The purified protein is free of contaminating groES from the bacterial host cells. Edman degradation reveals that the initiator Met residue of the recombinant protein is removed in vivo, similar to the authentic chaperonin 10 purified from rat liver mitochondria. However, in contrast to the latter, the amino-terminal Ala residue of the recombinant protein is not acetylated; the molecular mass determined by electrospray ionization mass spectrometry is 12,350.9 +/- 2.6 daltons, in agreement with that predicted for the nonacetylated protein (12,351.2 daltons). Facilitated protein folding experiments with ribulose-biphosphate carboxylase, under "nonpermissive" in vitro conditions, demonstrate that the recombinant protein is fully functional with groEL. Thus, both the initial rates of protein folding and final yields observed with this heterologous combination are virtually identical to those obtained with groEL and groES. More important, like the authentic protein purified from mitochondria, the recombinant mitochondrial chaperonin 10, but not groES, is functionally compatible with the heptameric chaperonin 60 of mammalian mitochondria.

Acetylation↗
PubMed1993

Nucleation of the iron core occurs at the three-fold channels of horse spleen apoferritin: an EXAFS study on the native and chemically-modified protein.

Extended X-ray absorbance fine structure measurements have been carried out on the initial Fe(III)-apoferritin complex at a Fe/subunit ratio of 2 in native and modified horse spleen apoferritin. Analysis of the data indicates that in the native protein the iron forms a protein-bound polynuclear cluster (Fe-Fe distance 3.4 A) with a first coordination sphere constituted by 5-6 low-Z atoms, e.g., nitrogen atoms, carboxylate-like ligands or oxo bridges between the iron atoms. Modification of Cys-126, a residue localized on the outer surface of the hydrophilic three-fold channels, with p-chloromercuribenzoate (PMB) or phenylmercuric acetate (PMA) brings about distinctive differences. In particular, in the PMB-reacted protein the feature assigned to the iron-iron interaction disappears from the spectrum, whilst in the PMA-reacted protein the main differences with respect to the native protein are observed at the level of the first coordination sphere. These results confirm the formation of protein-Fe(III)-clusters and localize these sites at the hydrophilic three-fold channels of horse spleen apoferritin.

Animals↗
PubMed1993

Plasma protein levels in normal human fetuses: 13 to 41 weeks' gestation.

OBJECTIVES: To establish reference ranges for the levels of alpha-fetoprotein, albumin, prealbumin (transthyretin) alpha-1-antitrypsin, transferrin, ceruloplasmin and total protein in the plasma of normal human fetuses and newborn babies. DESIGN: Prospective study of individual normal cases to fulfil objectives. SETTING: Pathology laboratories of the University of Edinburgh and the biochemistry laboratories of the University of Keele. SUBJECTS: Twenty-two normal fetuses 13 to 22 weeks of gestation and 66 babies born between 24 and 41 weeks gestation. RESULTS: Albumin is the predominant plasma protein throughout gestation. The levels of alpha-fetoprotein and prealbumin fell significantly with increasing gestation, whereas the concentrations of the other proteins studied increased. The ratios of individual proteins to total protein demonstrated similar trends. CONCLUSIONS: This study provides developmental profiles of normal human fetal plasma proteins to serve as possible reference data for abnormal fetuses. Declining levels of prealbumin (transthyretin) were unexpected and suggest a functional role for this protein in early pregnancy.

Blood Proteins↗
PubMed1992

Apoptotic cell death and tissue remodelling during mouse mammary gland involution.

During post-lactational mammary gland involution, the bulk of mammary epithelium dies and is reabsorbed. This massive cell death and tissue restructuring was found to be accompanied by a specific pattern of gene expression. Northern blot analysis showed that weaning resulted in a dramatic drop in ODC, a gene involved in synthesis of a component of milk, and the nearly simultaneous induction of SGP-2, a gene associated with apoptotic cell death. These changes were followed by decreases in expression of milk protein genes to basal levels and expression of genes associated with regulation of cell proliferation and differentiation, p53, c-myc and TGF-beta 1. Subsequently, additional genes implicated in stress response, tissue remodelling, and apoptotic cell death were transiently expressed, expression peaking at about 6 days post-weaning. A non-random degradation of DNA yielding the oligonucleosomal length fragmentation pattern typical of apoptotic cell death (Wyllie, 1980; Wyllie et al., 1980) was detected in association with morphological changes and gene expression. The correlations between: (a) changes in morphology, (b) pattern of gene expression and (c) changes in DNA integrity suggest that complementary programs for cell death and tissue remodelling direct post-lactational mammary gland involution.

Animals↗
PubMed1992

Glomerular injury induced by hydrogen peroxide: modifying influence of ACE inhibitors.

The sensitivity of isolated glomeruli from normotensive (Wistar-Kyoto, WKY) and spontaneously hypertensive (SHR) strains to oxidant stress was studied by determining the incidence of pyknosis, karyohexis and karyolysis after incubation with different concentrations of hydrogen peroxide (H2O2) (4.7 x 10(-9) - 10(-3) M). Even though the proportion of glomeruli containing nuclei that demonstrated these features increased progressively with increasing concentrations of H2O2, the number of severely damaged glomeruli was relatively small even at concentrations of 4.7 x 10(-3) M. Examination of the surface epithelial cells of glomeruli using scanning electron microscopy revealed no evidence of disturbance of the macroscopic or podocyte structure or, of increased blebbing after H2O2-treatment. These data suggest damage to nuclei is an early result of ROS stress on glomeruli. Preincubation of WKY glomeruli with captopril or lisinopril resulted in a significant drop in the proportion of WKY glomeruli demonstrating structural damage after oxidant stress. In contrast, preincubation of SHR glomeruli with lisinopril had no effect on oxidant-induced changes in the morphology of SHR glomeruli, whereas captopril effected a significant increase in the proportion of glomeruli demonstrating damage at all concentration of H2O2.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1991

Developmental profile of plasma proteins in human fetal cerebrospinal fluid and blood.

Total protein, alphafetoprotein, albumin, prealbumin, alpha-1-antitrypsin, transferrin and ceruloplasmin levels were measured in samples of human fetal and neonatal cerebrospinal fluid (CSF) (97 cases), obtained between 12 and 41 weeks of gestation. In 39 of these cases (13 to 40 weeks gestation) plasma was also available for comparative analysis. CSF was collected from lateral ventricles in the first half of gestation and from the lumbar region in the second. Since these CSF samples were obtained from different sites, the protein levels in the lateral ventricle (early) samples could not be compared directly with those in the lumbar (later) samples. However, the mean protein levels in the lumbar samples were lower than those in the ventricular samples, which is in accord with the decline in CSF protein levels described in maturing animal fetuses. Despite a wide scatter of results, particularly in the first half of gestation, significant decline in the level of CSF alphafetoprotein was demonstrated during both first and second halves of gestation, and of albumin and prealbumin in the second half. No sex differences were found except for ceruloplasmin in lumbar CSF later in gestation, when males had higher levels than females. In fetal plasma, protein levels increased with increasing gestation apart from alphafetoprotein and prealbumin which both declined progressively. CSF/plasma ratios were dissimilar for different proteins, and changed with increasing gestation. These findings support the concept that the human fetal blood brain barrier matures early.

Blood Proteins↗
PubMed1991

Mammary epithelial differentiation in vitro: minimum requirements for a functional response to hormonal stimulation.

Mammary epithelial differentiation is the culmination of responses to a complex sequence of hormonal stimuli. An in vitro model for this process should retain the basic features of in vivo epithelial differentiation. The IM-2 mouse mammary cell line responds to lactogenic hormone stimulation by synthesizing the milk protein beta-casein. Epithelial and fibroblastic clones derived from IM-2 lack this ability, but cocultures of these clones regain responsiveness to lactogenic hormone stimulation. Studies of the epithelial cell clone 31E under various culture conditions reveal that the role of fibroblastic cells in supporting synthesis and secretion of beta-casein can be supplanted by culture in filter chambers without addition of exogenous extracellular matrix components. Electron microscopic and immunofluorescence studies show that, under these conditions, 31E epithelial cells exhibit the morphology and intercellular organization characteristic of mammary epithelium. Transepithelial electrical resistance measurements indicate that the cells are well polarized. Analysis of glucose metabolism is consistent with this polarization; glucose is utilized from the basal chamber, and lactate is excreted into the basal chamber. Immunoblot analysis demonstrates the vectorial protein secretion expected of polarized mammary epithelium: laminin is secreted into the basal chamber, whereas beta-casein is secreted into the apical chamber in response to lactogenic hormone stimulation from the lower chamber. Thus, the maintenance of a polarized intercellular organization that permits access of the basolateral cell surface to nutrients is sufficient for a pure culture of an established mammary epithelial cell clone to retain differentiated epithelial function in vitro.

Animals↗
PubMed1991

Viral Ha-ras mediated mammary tumor progression.

An immortal mammary epithelial cell line, Comma 1D, and primary cultures of mammary epithelial cells were used to examine the effects of vHa-ras on mammary tumor development. In culture, Comma 1D and primary cells were morphologically indistinguishable. Infection with a replication defective vHa-ras retroviral vector (psi ras) did not alter their in vitro phenotype. Uninfected Comma 1D cells implanted into gland-cleared mammary fat pads gave rise to dysplastic outgrowths, while implants of primary cells gave rise to normal gland structures. After psi ras infection, implants of Comma 1D cells progressed to adenocarcinomas and those of primary cells resulted in initiated dysplastic outgrowths. High level infection of either cell type with replication competent HaMSV (psi ras plus helper virus) resulted in in vitro transformation and undifferentiated in vivo tumors. Thus, in vivo analysis was necessary to detect the observed correlation between tumorigenic stage and level of infection. In this system, expression of vHa-ras was vital but not sufficient for mammary tumor initiation and progression, which resulted from an accumulation of events that did not need to occur in a specific order.

Animals↗
PubMed1990

The alpha and pi isoenzymes of glutathione S-transferase in human fetal lung: in utero ontogeny compared with differentiation in lung organ culture.

Polyclonal antisera to the alpha and pi isoenzymes of glutathione S-transferase have been used in immunohistochemical studies of developing human lung. In utero expression of the pi set was down-regulated in distal airway cells and the first appearance of pi-negative cells coincided with phenotypic differentiation. In contrast, in the early phase of fetal lung organ culture pi isoenzyme was detected in all differentiated epithelial cells and only as culture progressed did focal negativity develop. The alpha set showed no developmental changes in utero or in organ culture.

Down-Regulation↗
PubMed1990

Glial and neuronal differentiation in the human fetal brain 9-23 weeks of gestation.

Nineteen human fetal brains ranging from 9-23 weeks of gestation were examined immunocytochemically for evidence of glial and neuronal differentiation. Radial glia were positive for vimentin and glial fibrillary acidic protein (GFAP) throughout the age range. S100-positive cells which were presumed to be astrocytes were present from 9 weeks; they were always more widespread in the cerebrum and the brainstem than GFAP-positive mature astrocytes, which could be detected with certainty only at 14 weeks. Carbonic anhydrase II (CA II)-positive oligodendrocytes were present in the brainstem in small numbers from 17 weeks. Neuronal fibre tracts in the cerebrum were positive for 160 kD phosphorylated neurofilament protein (BF10) from 9 weeks, but negative for 200 kD phosphorylated neurofilament protein (RT97) and for 70 and 200 kD non-phosphorylated neurofilament protein (NFP) whereas most tracts in the brainstem were positive for BF10 from 9 weeks and positive for the other neurofilament proteins from 14 weeks. Corticospinal tracts differed in remaining negative for neurofilament proteins other than BF10, which showed positive reaction throughout. Perikarya of differentiated neurons in all areas of the brain were neurofilament-negative but neuron specific enolase (NSE)-positive. Germinal eminence cells were focally vimentin-positive from 15 weeks, focally GFAP-positive from 17 weeks, and negative for all NFP and for NSE. The value of a short fixation time and pretreatment with trypsin in the immunocytochemical demonstration of GFAP is stressed.

Brain↗
PubMed1989

Differential expression of alpha and pi isoenzymes of glutathione S-transferase in developing human kidney.

Polyclonal antisera to the alpha and pi isoenzymes of glutathione S-transferase have been used in immunohistochemical studies to determine the developmental expression of these isoforms in human kidney. Before 35 weeks of gestation, both isoenzymes were expressed by the collecting tubules and developing nephrons. After this time, expression of the alpha set was restricted to the proximal tubule and that of the pi set to the distal and collecting tubules and the loop of Henle.

Adult↗
PubMed1989

Harvey-ras mediated neoplastic development in the mouse mammary gland.

The role of a Harvey-ras oncogene in mammary epithelial neoplasia was examined by infecting primary cultures of normal mouse mammary epithelial cells with either the Harvey murine sarcoma virus (psi 2HaMSV) alone or with HaMSV plus a helper virus. The biological effects of expression of the Ha-ras oncogene were determined by transplanting the infected cells into gland-cleared mammary fat pads of virgin Balb/c mice. Expression of the Ha-ras oncogene was correlated with the development of mammary epithelial neoplasms. Cells infected with replication-defective HaMSV alone formed dysplastic, non-invasive mammary outgrowths. Cells infected with HaMSV plus a helper virus developed poorly-differentiated, invasive mammary epithelial tumors. Uninfected cells and cells infected with only the helper virus formed normal mammary trees. Expression of the mutant viral Ha-ras p21 was detected in dysplastic outgrowths and tumors but not in normal mammary outgrowths. Use of this transgenic organ system to genetically alter epithelium of the mouse mammary gland has permitted correlation of expression of a Ha-ras oncogene with development of mouse mammary neoplasia.

Animals↗
PubMed1988

The use of antipyrine clearance to measure liver damage in psoriatic patients receiving methotrexate.

Salivary antipyrine clearance was measured in 15 patients with psoriasis receiving methotrexate and related to liver biopsy changes and routine liver function tests, to determine whether antipyrine clearance could be used as a non-invasive method for monitoring liver function. Comparison of the salivary antipyrine clearance in the methotrexate group (mean 0.51 ml/min/kg, range 0.26-0.81) with 15 matched psoriatic controls (mean 0.54 ml/min/kg, range 0.34-0.99) showed no significant difference. Liver biopsy changes were scored for fatty change, fibrosis, liver cell necrosis and portal tract infiltrate. Total liver biopsy scores correlated significantly with antipyrine clearance/kg body weight (r = -0.72, P less than 0.05). There was no significant correlation of total liver biopsy scores with the other liver function tests. Correlation of the individual liver biopsy changes and antipyrine clearance showed a significant correlation with fatty change (r = -0.75, P less than 0.01), but not with fibrosis (r = -0.53), liver cell necrosis (r = -0.54) or infiltrate (r = -0.41).

Adult↗