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Biomedical subjects

L Berry

Publications and source records attributed to L Berry.

At least 55 records · Page 3Linked to original sources
PubMed1992

Properties of redox-inactivated bleomycins. In vitro DNA damage and inhibition of Ehrlich cell proliferation.

Blenoxane, bleomycin A2, bleomycin B2, and demethyl bleomycin A2 and products of their reactions with Fe2+ and oxygen were used to explore the relationship between their capacity to carry out in vitro DNA strand scission and their growth inhibitory activity against Ehrlich cells. Reaction of Fe2+, bleomycin and O2 in the absence of DNA decreased the subsequent effectiveness of various bleomycin congeners to degrade DNA in the presence of Fe2+ and oxygen. In comparison with controls, this loss of strand scission activity was not paralleled by equivalent decreases in growth inhibition. Demethyl bleomycin A2 retained full biological activity relative to bleomycin A2, despite being only 30% as effective as bleomycin A2 in its ability to cleave DNA in vitro. Prior reaction of bleomycins with Fe2+ did not alter their capacity to reduce oxygen or affect their ability to generate the activated intermediate which, for native bleomycin structures, is competent to cleave DNA in vitro.

Animals↗
PubMed1992

Microfibrillar components in dental pulp: presence of both type VI collagen- and fibrillin-containing microfibrils.

Microfibrillar elements were isolated from developing and formed bovine dental pulp by a procedure involving bacterial collagenase tissue digestion and chromatography on Sepharose CL-2B. Two microfibrillar assemblies could be demonstrated. Type VI collagen microfibrils with a characteristic periodicity of about 100 nm appeared as long, thin, flexible filaments. In a number of cases these structures aggregated by lateral association. Microfibrils of 10-14 nm dia were identified as containing fibrillin on the basis of their distinctive, periodic, beaded morphology. In addition to long, single strands there were instances of chains coalescing to give amorphous aggregates. No differences in the type of microfibrillar assemblies were evident between developing and formed pulp, although fibrillin-containing microfibrils were more abundant in formed pulp.

Actin Cytoskeleton↗
PubMed1992

Refractory hypoxaemia after pneumonectomy: diagnosis by transoesophageal echocardiography.

A patient with normal oxygenation before operation became very breathless and hypoxaemic after a right pneumonectomy. Transoesophageal echocardiography showed right to left interatrial shunting due to a patent foramen ovale. Transoesophageal echocardiography should be included in the assessment of patients who became inappropriately dyspnoeic after pneumonectomy.

Cardiac Catheterization↗
PubMed1992

An anticoagulant dermatan sulfate proteoglycan circulates in the pregnant woman and her fetus.

Investigation of the in vitro ability of plasma from pregnant women to inhibit exogenous thrombin (25 nM) demonstrated that heparin cofactor II inhibited more thrombin (3.0 +/- 0.7 nM, mean +/- SD) than plasma from women 3-5 d postpartum (1.9 +/- 0.5 nM) or plasma from nonpregnant adults (1.5 +/- 0.4 nM). Levels of heparin cofactor II were only slightly increased over normal in both pregnant and postpartum women and did not account for the observed increase in thrombin bound to heparin cofactor II. Assay of pregnancy plasma for dermatan sulfate anticoagulant activity demonstrated the presence of activity equivalent to 0.23 +/- 0.02 micrograms/ml of porcine mucosal dermatan sulfate. This activity could not be demonstrated in normal adult plasma or plasma from women on the contraceptive pill. The mass of dermatan sulfate in pregnancy and umbilical cord plasmas was increased over adult control plasma by 0.20 micrograms/ml (53%) and 0.29 micrograms/ml (76%), respectively. The glycosaminoglycan-containing fraction of plasma was isolated and an assay for anticoagulant dermatan sulfate confirmed its presence in both pregnancy and cord plasmas but minimal activity in adult plasma. Gel chromatography of isolated fractions from both pregnancy and cord plasmas revealed a polydisperse, active species with apparent Mr 150,000 D. Reductive elimination decreased the apparent Mr of the active species on gel chromatography to 31,000 D for cord and 21,000 D for pregnancy products. This confirmed the presence of an anticoagulant active dermatan sulfate proteoglycan circulating in the plasmas of pregnant women at term and fetuses at delivery.

Anticoagulants↗
PubMed1992

Bone-marrow-derived chondrogenesis in vitro.

Bone marrow stromal cells from embryonic, neo-natal and adult chickens were grown in vitro over a 21-day period. Marrow stromal cells from embryonic and neonatal chicks produced clonally derived chondrocytic colonies. The cells within the colonies were surrounded by a refractile, Alcian-blue-positive matrix and their cartilagenous nature was shown biochemically and immunocytochemically by the synthesis of collagen types II and X. The ability of chick bone marrow cells to form chondrocytic colonies decreased during development and was lost by adulthood. In addition to chondrocytic colonies, fat cells and fibroblasts were also observed in the cultures. Our data demonstrate that chick bone marrow stroma contains cells that are capable of differentiating along different pathways within the same culture, providing further evidence for the presence in bone marrow of a stromal stem cell.

Aging↗
PubMed1992

Sonographic assessment of late proliferative phase endometrium during ovulation induction.

Late proliferative phase endometrium was assessed sonographically in 400 patients undergoing ovulation monitoring or stimulation. Endometrial evaluation was classified in relation to its widest diameter (quantity) and by the presence or absence of a double-layered (outer echogenic/inner hypoechoic) pattern (quality). No patient conceived if the endometrium was totally echogenic and less than 8 mm in diameter. All patients who conceived had an endometrium that was double-layered or greater than 9 mm in diameter. Positive, double-layered patterns correlated with correction of hormonal aberrations such as hypoestrogenism, hyperprolactinemia or hyperandrogenism. Such a positive pattern was also accomplished after discontinuation of clomiphene citrate in certain low-body weight/low-body fat women and administration of human menopausal gonadotropins to those patients. Application of the principles described to ensure the development of an adequate, double-layered (follicular phase) endometrium at midcycle were found to coincide with a higher incidence of pregnancy and viable gestation.

Chorionic Gonadotropin↗
PubMed1991

Heparin sensitivity and resistance in the neonate: an explanation.

Based on in vitro tests, newborns are reported to be both sensitive and resistant to standard heparin (SH) compared to adults. The sensitivity to SH occurs in assays based on de novo thrombin generation, and SH resistance occurs in systems where exogenous thrombin is added to newborn plasma. We hypothesized that this apparent paradox is related to the antithrombin III to (pro) thrombin ratio associated with each test. Since SH catalyses the activity of antithrombin III, any imbalance in the antithrombin III/(pro)thrombin ratio in newborns compared to adults would be amplified by SH. If the ratio of antithrombin III/(pro)thrombin is defined as 1 in adults, in comparison newborns have a ratio of 1.5. We compared how various doses of SH (0.1 to 0.6 u/ml) inhibited the generation of endogenous thrombin in defibrinated newborn (N) and adult (A) plasma. Following contact activation and recalcification of each plasma, thrombin activity was measured using a chromogenic substrate and quantitated by measuring the area under the curve. In the presence of SH, newborn plasma was more sensitive to SH than adult plasma and generated relatively less thrombin (N:6.1 vs A:9.1% sec/u/ml; p less than 0.01). When the ratio of antithrombin III/(pro)thrombin in newborns was altered to 2.5 by exogenous antithrombin III, the SH sensitivity was increased. This plasma now generated no detectable thrombin in the presence of only 0.1 u/ml of SH. In contrast, when the ratio of antithrombin III/(pro) thrombin of the newborn was altered by exogenous prothrombin to 0.6, this plasma now became resistant to SH and generated more thrombin than adults in the presence of SH (N:11.6 vs A:9.1; p less than 0.01). Because of the potential use of low molecular weight heparins (LMWH) in newborns, a LMWH, Choay 222, was also tested in a similar fashion and gave similar results to SH. Thus, the ratio of antithrombin III/(pro)thrombin likely determines the in vitro sensitivity or resistance of newborn plasma to SH and LMWH. There are no clinical studies that determine if newborns require more or less SH than the adult to successfully treat thrombotic complications. Current practice is a simple extrapolation of therapeutic ranges from adults. We speculate that the efficacy and safety of SH in the newborn in vivo can be improved by altering the antithrombin III/(pro)thrombin ratio.

Adult↗
PubMed1991

Influence of fetal pulmonary epithelium on thrombin activity.

Epithelial injury and intra-alveolar fibrin are present in lung injury. To determine whether healthy fetal and neonatal lung epithelium could regulate thrombin activity (hence fibrin formation) we collected amniotic and postnatal endotracheal tube fluids from humans and directly sampled lung and amniotic fluids from fetal guinea piglets, rabbit pups, and lambs. The coagulant properties of the cell surface and media conditioned by rat fetal type II alveolar epithelium were assessed. All fluids contained glycosaminoglycans (GAGs), but mass and biological assays demonstrated only some (heparan sulfate and to a lesser extent dermatan sulfate) had antithrombin activity. The presence of proteoglycans (greater than 1,000 kDa) yielding active GAGs with less than 100 kDa after base elimination were demonstrated by Sepharose CL4B chromatography. Epithelial-derived fluids contained a factor VII-dependent procoagulant activity, but concentrated conditioned media overlying primary cultures of type II epithelium demonstrated a net antithrombin effect. These studies demonstrate that the lungs of human and nonprimate mammalian fetuses and fetal type II epithelium secrete GAGs, some of which possess antithrombin activity, which would oppose intra-alveolar fibrin formation.

Amniotic Fluid↗
PubMed1991

A549 lung epithelial cells synthesize anticoagulant molecules on the cell surface and matrix and in conditioned media.

To investigate mechanisms regulating intra-alveolar coagulation, we studied monolayers of the A549 human lung epithelial cell line. The surface of A549 cells delayed the onset of prothrombin-to-thrombin conversion and prevented total prothrombin consumption in normal plasma compared to plastic cell-free wells. Similar results were achieved with bovine pulmonary endothelial (CPAE) and rat intestinal epithelial (IEC-6) cell lines, whereas Madin-Darby canine kidney renal epithelial cell line accelerated thrombin formation. The A549 surface catalyzed antithrombin III-thrombin complex formation with no significant increase in thrombin inactivation from heparin cofactor II. The A549 cell surface effects were largely, but not completely, reversed to values obtained for plastic when protein C-deficient plasma was used. Pretreatment of the cell surface with chondroitinase ABC plus heparitinase prior to thrombin generation experiments had no effect on the total prothrombin consumed but decreased the initial delay. Heparan sulfate as well as dermatan sulfate and other chondroitin sulfates were detected on the A549 surface using alcian blue staining. Conditioned media from A549, CPAE, and IEC-6 cells delayed the clot time of recalcified plasma. Use of chondroitinase ABC and heparitinase were both required to obliterate the A549 conditioned media activity. After growing A549 cells in 35SO(2-)4-containing medium, the resultant conditioned medium was found to contain 2,000 kD and 300- to 1,000-kD proteoglycans that yielded chains of less than or equal to 100 kD on reductive elimination with base.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Population change and environment in central and eastern Kenya.

"This paper, in compiling a case-study of six districts in Central and Eastern Provinces of Kenya, addresses the two poles of theory regarding population, environment, and economy--restricted growth and degradation versus induced change and intensification. The paper presents data on population change, and explores its relevance for changing patterns of resource use and economic opportunity.... Changes in population density between the 1969 and 1979 censuses are compiled, using regions of agroclimatic potential as surrogates for indicators of economic development.... Trends in urbanization are also analysed, to illuminate the dynamics of rural-urban linkages."

Africa↗
PubMed1989

Expression of the chondrogenic phenotype by mineralizing cultures of embryonic chick calvarial bone cells.

Cells released by sequential enzymatic digestion of 18-day chick calvariae were cultured over a 4-5 week period in Alpha modified Eagles medium. In some cultures the medium was supplemented with ascorbate and/or Na-beta-glycerophosphate. Microscopic examination of these cultures showed both polygonal and spindle-shaped cells. The biochemical nature of these cells was investigated by incubating the cultures with radiolabelled proline and subsequently analysing the medium and cell layer proteins by SDS/PAGE and fluorography. Osteoblast and chondrocyte-containing cultures were clearly distinguished in this way as the former cells secreted type I collagen while the latter secreted types II and X collagens as the major medium macromolecules. Type X collagen synthesis occurred after 14 days, but only in cultures supplemented with both ascorbate and Na-beta-glycerophosphate, and was maintained for the duration of the culture period. Unsupplemented cultures and those containing either ascorbate alone or Na-beta-glycerophosphate alone failed to synthesize type X collagen after 28 days. Isolated cells pulsed with radiolabelled proline at confluence and organ cultures of embryonic chick calvaria synthesized types I and V collagens only. These data demonstrate that the expression of phenotype by heterogeneous populations of bone cells could be modulated by a combination of culture conditions including the length of time in culture and conditions favourable for the formation of a mineralized matrix.

Animals↗
PubMed1988

Antiproteinases protect cultured lung endothelial cells from endotoxin injury.

To determine whether the effects of endotoxin on cultured lung endothelium involve proteolytic mechanisms, we incubated bovine pulmonary arterial endothelial cells with endotoxin in medium 199 + 10% fetal bovine serum (FBS) in the presence and absence of several proteinase inhibitors. Three chloromethyl ketone (CK) derivatives [N-tosyl-L-lysine (CK)-(TLCK), N-tosyl-L-phenylalanine CK(TPCK), methoxysuccinyl-Ala-Ala-Pro-Val CK(SPCK)] and a single synthetic proteinase substrate [N-alpha-p-tosyl-L-arginine methyl ester hydrochloride (TAME)] attenuated endotoxin-induced cytotoxicity (lactate dehydrogenase release) and prostacyclin production in a dose-related fashion. The most effective inhibitors of endotoxin-induced cytotoxicity were TLCK and TPCK. TLCK and TAME most effectively attenuated endotoxin-stimulated prostacyclin production. Two chemically unrelated substances, soybean trypsin inhibitor and alpha 1 proteinase inhibitor also attenuated the endotoxin response. In the absence of FBS or in the presence of 10% heat-inactivated FBS, antiproteases attenuated endotoxin-induced prostacyclin production but had less effect on cytotoxicity than with 10% FBS. We also measured the capacity of the CK inhibitors to scavenge superoxide radicals generated in a cell-free xanthine/xanthine oxidase system by measuring inhibition of cytochrome c reduction. Percent scavenging of superoxide by these inhibitors was as follows: TLCK, 62.7 +/- 5.8 (SE); TPCK, 83.9 +/- 7.7; TAME, 24.5 +/- 6.4; SPCK, 0. We conclude that certain proteinase inhibitors attenuate endotoxin-induced endothelial cytotoxicity and prostacyclin production and that direct scavenging of superoxide radicals fails to explain the protective effects of proteinase inhibition. We speculate that the effects of endotoxin on lung endothelium may involve proteolytic mechanisms even in the absence of neutrophils.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Attenuation of endotoxin-induced cytotoxicity and prostacyclin production in cultured bovine pulmonary artery endothelial cells by phosphodiesterase inhibition.

Exposure of cultured bovine pulmonary endothelial cells to endotoxin (lipopolysaccharide, LPS) causes cytotoxicity and increased prostacyclin production. Since cyclic nucleotides have been proposed as modulators of inflammation, we wondered whether they were involved in LPS-induced endothelial damage. Bovine pulmonary endothelial cells were exposed for 24 h to LPS and the effects of 1-methyl-3-isobutylxanthine (MIX), a phosphodiesterase inhibitor, dibutyryl cyclic AMP (db-cAMP), forskolin (an adenylate cyclase activator), and sodium nitroprusside (an agent known to stimulate intracellular cyclic GMP generation) on LPS-induced injury were determined. Injury was assessed by measurement of lactate dehydrogenase (LDH) (activity) and prostacyclin (6-keto-PGF1 alpha) in the bathing medium. Incubation with MIX attenuated LPS-induced endothelial cytotoxicity and prostacyclin production in a dose-dependent manner (ANOVA, p less than 0.001). Dibutyryl cyclic AMP also inhibited LPS-stimulated LDH release from the endothelial cells but did not suppress increased prostacyclin production. The combinations of MIX and dibutyryl cyclic AMP produced protection similar to that of MIX alone. Neither nitroprusside nor forskolin affected LPS-induced endothelial injury. Measurements of intracellular cyclic nucleotide concentrations showed that MIX caused marked increases in both cyclic AMP and cyclic GMP within 30 min of incubation, while forskolin and nitroprusside failed to cause such early elevations. Thus, phosphodiesterase inhibition protects endothelial cells from the effects of LPS. Increased intracellular concentrations of cyclic AMP also protect endothelial cells from LPS-induced cytotoxicity but do not alter the prostanoid response. We conclude that increased intracellular concentrations of cyclic AMP protect against LPS-induced endothelial cytotoxicity if present early in the exposure. We further conclude that LPS-mediated endothelial cytotoxicity can be separated from increased prostacyclin production.

1-Methyl-3-isobutylxanthine↗
PubMed1988

Bacterial collagenase and collagen identification.

A method is described for the cleavage of collagenous molecules by bacterial collagenase in the presence of sodium dodecyl sulphate (SDS) and urea. Comparison of three commercially available preparations of bacterial collagenase showed that the most efficient cleavage under these conditions was by the enzyme isolated from Achromobacter iophagus (E.C. 3.4.24.8). No non-specific proteinase activity was apparent in conditions where all collagen types showed some susceptibility to attack. This method represents a simple one-stage identification of collagenous molecules in complex mixtures of proteins and where limited amounts of a protein are available.

Alcaligenes↗
PubMed1986

Type VI collagen and glycoprotein MFPI are distinct components of the extracellular matrix.

Two collagenous glycoproteins, Mr 140,000 and Mr 150,000, are synthesized and secreted into the medium of cultured fibroblasts. The glycoprotein of Mr 140,000 is identical with the 140K(VI) component of type VI collagen by both immunological and physicochemical criteria. The glycoprotein of Mr 150,000 is immunologically distinct and exhibits the physicochemical characteristics of the putative elastic microfibrillar glycoprotein MFPI.

Animals↗