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Biomedical subjects

D Ellis

Publications and source records attributed to D Ellis.

At least 163 records · Page 9Linked to original sources
PubMed1988

Renal epithelial development in organotypic culture.

An in vitro model system for the experimental study of renal epithelial differentiation is described. Fetal murine metanephric tissue consisting of nephrogenic blastema and branched ureteric bud is isolated following 24-36 h of natural embryonic inductive interaction (13 +/- 0.4 days gestation) and cultured as an intact organ in a Trowell-type assembly. During 120 h of organ culture incubation in completely defined serum-free medium, advanced organotypic proximal tubular and glomerular epithelial differentiation proceed in the absence of vascularization, perfusion, and urine production. The system thus experimentally separates the processes of three-dimensional organ growth and post-induction renal epithelial differentiation from glomerular filtration, flow-related phenomena, endothelial or mesangial cell interactions, and the effects of growth factors or transport substrates present in mammalian serum or urine. Studies to date in the model system have defined the growth factor requirements of epithelial growth and differentiation and have demonstrated that specific hormonally induced alterations in tubular epithelial cell metabolism and function may lead to specific patterns of tubular maldevelopment. Whole organ metanephric organ culture is thus a valuable in vitro model system for future investigations into the complex processes of normal and abnormal renal epithelial differentiation.

Animals↗
PubMed1988

Regulation of glucocorticoid receptors and Na-K ATPase activity by hydrocortisone in proximal tubular epithelial cells.

The effect of hydrocortisone (HC) in modulating glucocorticoid receptors (GR) and sodium-potassium adenosine triphosphatase (Na-K ATPase) activity was studied in primary cultures of immunoisolated murine proximal tubular epithelial cells (PTEC). Utilizing monoclonal antibody against stage-specific embryonic antigen-1, a homogeneous population of PTEC was obtained in high yield. The cells were cultured to confluence and further treated for 48 h in serum-free growth medium containing no HC (control); 50 nM HC; or 50 nM HC plus 20 nM of the antiglucocorticoid, RU 38486. PTEC treated with 50 nM HC had 56% of GR binding and 160% Na-K ATPase activity as compared to controls (P less than 0.01). GR binding was abolished by incubation in RU 38486 whereas Na-K ATPase fell below control values (P less than 0.05). Brief incubations of HC-treated PTEC with 0.5 mM ouabain resulted in a fall in GR binding without a change in Na-K ATPase activity. These data indicate that in PTEC, HC regulates GR binding and they suggest that stimulation of Na-K ATPase activity is a direct biological response to this receptor-hormone interaction. Thus, primary cultures of immunoaffinity-isolated PTEC offer a good model system for investigating the molecular basis underlying the regulation of GR binding and postreceptor events influenced by glucocorticoids.

Animals↗
PubMed1988

Therapy of primary diffuse large cell lymphoma of the penis with preservation of function.

Only 7 cases of primary lymphoma of the penis have been described previously. We report a case of diffuse large cell lymphoma of the glans penis. The clinical features, histology and management of these cases are reviewed. The previously reported cases were treated with surgical resection or radiotherapy resulting in some degree of local morbidity. Our patient achieved complete remission after only 1 cycle of chemotherapy. The benefits of chemotherapy over surgery or radiotherapy for primary lymphoma of the penis are discussed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Thyroid hormone analogues. Synthesis of 3'-substituted 3,5-diiodo-L-thyronines and quantitative structure-activity studies of in vitro and in vivo thyromimetic activities in rat liver and heart.

Twenty-nine novel 3'-substituted derivatives of the thyroid hormone 3,3',5-triiodo-L-thyronine (T3) have been synthesized by using established methods and by a new route involving manipulation of a 3'-formyl intermediate. In vitro hormone receptor binding (to intact nuclei) and in vivo thyromimetic activity (induction of mitochondrial 3-phosphoglycerate oxidoreductase, GPDH) were measured in rat liver and heart for these new analogues and for the 18 previously reported 3'-substituted 3,5-diiodo-L-thyronines. Analysis of the binding data using theoretical conformational and quantitative structure-affinity methods implies that the 3'-substituent recognition site on the thyroid hormone receptor is hydrophobic and limited in depth to the length of the natural iodo substituent, but has sufficient width to accommodate a phenyl or cyclohexyl group. Receptor binding is reduced by approximately 10-fold in 3'-acyl derivatives which form strong intramolecular acceptor hydrogen bonds with the adjacent 4'-hydroxyl. The compounds studied showed no differences in their relative affinities for heart and liver nuclei, suggesting that receptors in these tissues are similar. However, the relationships between thyromimetic activity (induction of GPDH) and nuclear binding showed some tissue differences. A high correlation between activity and binding is observed for full agonists in the heart, but an equally significant correlation for the liver data is only seen when 3'-substituent bulk (molar refractivity) is included in the analysis. These results suggest the possibility that differential tissue penetration or access to receptors may occur in vivo.

Animals↗
PubMed1988

Studies of the isolation and viability of human islets of Langerhans.

Pancreas obtained from 34 adult human cadaver organ donors was divided into proximal and distal segments, and the duct to each segment was cannulated. Collagenase was injected into the proximal duct of 7 glands and into the distal duct of 7 others; the duct of the opposite segment was perfused with collagenase. The pancreas was then dispersed by teasing, trituration, and passage through filters. Perfused proximal and distal segments released 1461 +/- 287 and 2728 +/- 797 islets/g (+/- SEM) versus 710 +/- 149 (P less than 0.05) and 1950 +/- 636 after injection. Twenty other pancreases were perfused with collagenase warmed rapidly to 39 degrees C (n = 4) or warmed slowly to 37 degrees C (n = 6) or 39 degrees C (n = 10): the yield was 1625 +/- 632, 1320 +/- 116, and 2009 +/- 277 islets/g respectively. Total yields from the latter were 76 X 10(3) large (greater than 100 microns) and 85 X 10(3) small (less than 100 microns) islets with recoveries of 61% and 42%, respectively, after Ficoll density gradient purification. Histology showed highly purified islets. Perifusion with glucose elicited a biphasic release of insulin with the mean response (microU/islet/min) rising to a first peak of 0.5 and constant second phase secretion of 0.25, followed by a return to baseline. Reduced response was observed for islets from pancreas stored greater than 6 hr and tissue obtained from multiple centers. Less insulin was produced by freshly isolated islets, islets less than 100 microns, and after Ficoll separation. Secretion was similar for islets derived from proximal or distal segments. Perfusion of collagenase via the ducts of human pancreas improves islet isolation and Ficoll gradient separation yields highly purified islets. Important factors influencing insulin secretion are the source of donor tissue, cold storage of pancreas, Ficoll purification, islet size, and tissue culture.

Cell Separation↗
PubMed1987

Congenital murine polycystic kidney disease. I. The ontogeny of tubular cyst formation.

In the current study, the ontogeny of tubular cyst formation was studied in the CPK mouse, a murine strain with autosomal recessive polycystic kidney disease. Utilizing the technique of intact nephron microdissection in addition to standard light and transmission electron microscopy, the earliest morphologic alterations in CPK kidneys were localized in fetal tissue at 17 days of gestation to the distal portion of developing proximal tubules. During disease progression, from birth to 21 days of postnatal age, there was a shift in the site of cystic nephron involvement from proximal tubule to collecting tubules without involvement of other nephron segments. Cysts were enlarged tubular segments which remained in continuity with other portions of the nephron and were not associated with abnormalities in the overall pattern of nephron growth or differentiation. Analysis suggested that alterations in transtubular transport in abnormally shortened proximal tubular segments of juxtamedullary nephrons may have pathogenic importance in the early stages of cyst formation, and that epithelial hyperplasia and cytoskeletal alterations may have a role in progressive proximal tubular cystic enlargement. Cellular hyperplasia of epithelial walls of normally formed tubules was a prominent feature of cyst formation and progressive enlargement in collecting tubules. Such data form the basis for future studies into specific pathophysiological processes which may be operative in specific nephron segments during different stages of cyst formation in the CPK mouse.

Animals↗
PubMed1987

Increasing social interactions of severely handicapped autistic children.

A peer-initiation training procedure was implemented across multiple peer trainers to investigate social interactions between severely withdrawn autistic children and their nonhandicapped peers. For one subject, substantial increases in spontaneous interactions with training and nontraining peers occurred after the peer-initiation procedure was applied across two training exemplars. Spontaneous social interactions continued even after the training procedure was removed. Although experimental control was established with the second subject during training, spontaneous interactions during nontraining periods were primarily with training peers. The results contribute to an emerging data base on the social interactions of autistic and severely withdrawn handicapped children and on peer-initiation training procedures.

Autistic Disorder↗
PubMed1987

Glucocorticoids modulate renal glucocorticoid receptors and Na-K ATPase activity.

Primary cultures of mouse renal tubular epithelial cells were used to study the effect of hydrocortisone on the regulation of glucocorticoid receptors (GR) and on sodium-potassium adenosine triphosphatase (Na-K ATPase) activity. A GR assay was developed and performed directly on cell monolayers maintained in serum-free medium to which hydrocortisone at 5 nM, 50 nM, and 5 X 10(-4) M was added. Compared with control cells grown in medium without hydrocortisone, GR levels per cell decreased by 50% after 48 hours of growth in medium containing 5 nM hydrocortisone concentrations (50 nM or 5 X 10(-4) M), GR levels decreased to less than or equal to 28% of control values. In all hydrocortisone treatment groups there was an inverse relation between GR concentrations and Na-K ATPase activity. Binding of cell GR by the addition of the antiglucocorticoid RU 38486 in hydrocortisone-supplemented medium eliminated the glucocorticoid-induced stimulation of Na-K ATPase activity. These results demonstrate a time- and dose-dependent effect of glucocorticoids on GR binding activity and a direct relation between this receptor-hormone interaction and Na-K ATPase activity in intact renal tubular epithelial cells.

Animals↗
PubMed1987

The reversal of the hepatorenal syndrome in four pediatric patients following successful orthotopic liver transplantation.

Four pediatric patients are presented in whom profound renal failure (hepatorenal syndrome) developed in association with severe end-stage liver disease. All four patients had successful orthotopic liver transplantation. Special emphasis is given to the preoperative and postoperative renal function in the patients, and the criteria used to establish the diagnosis of the hepatorenal syndrome are discussed. In the initial work on liver transplantation and reversal of the hepatorenal syndrome, two of the three patients recovered renal function but died in the perioperative period. The four patients presented in this report have not only had reversal of the hepatorenal syndrome after successful orthotopic liver transplantation but have also survived long term. The four patients have been followed up for periods ranging from 18 months to 4.5 years. Three of the four patients have maintained near normal renal function, whereas the fourth patient (who had a left nephrectomy for obstruction and sepsis) has had a significant decline in renal function.

Adolescent↗
PubMed1987

Posterior vitreous fluorophotometry in diabetic patients with minimal or no retinopathy.

Vitreous fluorophotometry (VFP) using the Fluorotron Master was performed in 25 insulin-dependent diabetic patients with either minimal or no retinopathy and 22 controls. At 30 minutes, baseline corrected vitreous fluorescence values 3 mm from the retina were significantly greater in diabetic patients with minimal retinopathy than in either controls or patients with no retinopathy but were similar in patients with no retinopathy and controls. At 1 hour, vitreous fluorescence values and fluorescein permeability indexes were similar in all three groups. The absence of increased posterior vitreous fluorescein leakage in the diabetic patients with no retinopathy suggests that the alteration in permeability of the blood retinal barrier, as assessed by current VFP measures, does not precede the development of clinical diabetic retinopathy. However, the significantly increased 30-minute 3-mm fluorescence values suggest that posterior fluorescein leakage is increased in minimal background diabetic retinopathy.

Adult↗
PubMed1987

Intracellular pH in sheep Purkinje fibres and ferret papillary muscles during hypoxia and recovery.

1. The changes of intracellular pH (pHi) of papillary muscles from ferret and Purkinje fibres from sheep heart during hypoxia and recovery from hypoxia were recorded with pH-sensitive micro-electrodes filled with neutral H+ carrier. 2. Hypoxia was produced by replacement of O2 with N2 in the superfusing solutions. When oxidative phosphorylation was prevented, developed tension fell within 20 min to about 16 and 21% of its control value for papillary muscle and Purkinje fibres respectively. On restoration of O2, recovery of developed tension in ferret papillary muscle is preceded by a transient additional decrease. 3. In ferret papillary muscle, the pHi first increased by a mean value of 0.11 pH units after 3 min hypoxia, then decreased by about 0.24 pH units after 20 min. In sheep Purkinje fibres, the initial alkalosis was small or absent, and after 5-9 min, the pHi started to fall reaching 0.17 pH units after 20 min of hypoxia. On return to oxygenated solution, a transient additional intracellular acidification occurred. This acidification reached its peak of 0.31 pH units in papillary muscle and of 0.13 pH units in Purkinje fibres. In both preparations hypoxia was accompanied by a depolarization of a few millivolts. 4. The presence of cyanide (1-2 mM) or fluorodinitrobenzene (20-40 microM) prevented the additional intracellular acidification occurring on return to oxygenated solution. Removal of cyanide itself produced a transient but smaller and slower acidification. 5. On both preparations, exposure to a Tyrode solution containing 10 mM-L-lactate produced a transient intracellular acidification. After recovery from this acidification the acidification produced by hypoxia was increased without affecting the extra acidification on reintroduction of O2. 6. After reduction of the rate of glycolysis by removal of glucose and application of 2-deoxyglucose, the transient intracellular acidification, occurring on return to oxygenated solution after hypoxia, was inhibited in both preparations. In ferret papillary muscle, insulin (100 mU/ml) potentiated the changes of pHi occurring during hypoxia. 7. Using Na+-sensitive glass micro-electrodes it was found that the intracellular Na+ activity rose slightly during the later stages of hypoxia and rose transiently on readdition of O2. These results are consistent with a Na+-H+ exchange being stimulated by acidosis. 8. The origins of the pH changes during and after hypoxia are discussed as are the differences between the responses of sheep Purkinje fibres and ferret papillary muscle.

Animals↗
PubMed1987

Effects of shear stress on adhesive interaction between neutrophils and cultured endothelial cells.

The effect of hydrodynamic shear stress on the adhesive interaction between neutrophils and endothelial cells in vitro was investigated using an apparatus similar to a cone-in-plate viscometer. Isolated bovine neutrophils were labeled with 111In and incubated with monolayers of cultured bovine pulmonary arterial endothelial cells in the presence of different degrees of shear stress. Physiologically relevant shear (less than 2 dyn/cm2) was associated with marked decrease in neutrophil adherence. Stimulation with 10% bovine zymosan-activated plasma increased adherence under static conditions but failed to increase adherence conducted during the application of shear stress. Inhibition of endothelial cell prostacyclin production by meclofenamate or aspirin failed to alter the response to shear. Incubation of neutrophils under static conditions for 10, but not 5, min however, markedly enhanced subsequent resistance to shear, suggesting that a time-dependent reaction between neutrophil and endothelial cell was required to induce an increase in the strength of adherence. Analysis of neutrophil migration underneath the monolayer indicated that such migration in no way accounted for resistance to shear, particularly since shear resistance was enhanced on serum-coated plastic as well as endothelial cells. We conclude that hemodynamic factors may play an important role in modulating neutrophil adherence to endothelium in both normal and inflammatory states.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Reversible inhibition of cytosolic glucocorticoid receptors by mercurial agents. Application in the measurement of total and unoccupied receptors.

Recently developed "exchange assays" have been used to measure total cytosolic glucocorticoid receptor (GR) binding activity as compared to standard GR assays which measure unoccupied receptor. In the current study we modified these methods and extended the applications of such assays. Experiments defined the conditions whereby two sulfhydryl-binding agents, p-hydroxymercuribenzoate (PHMB) and mersalyl, completely inhibited binding of the glucocorticoid receptor to ligand in mouse renal cytosol. Reactivation of steroid-binding activity was restored by addition of dithiothreitol. The present study demonstrates 12% higher GR binding activity when this exchange assay is performed using saturated glucocorticoid-receptor complex, rather than standard cytosol. Combining the data from the standard and exchange mouse renal cytosolic GR assays, it was determined that, at physiologic tissue corticosterone levels, the respective mean concentrations of unoccupied, occupied, and total GR were 467, 89, and 556 fmol/mg cytosol protein. Measurement of receptor concentrations by the use of these methods permits precise experimental differentiation of factors which affect total, as well as unoccupied GR.

Animals↗
PubMed1987

Renal histopathology in Alagille's syndrome.

Various renal abnormalities have been reported in Alagille's syndrome (arteriohepatic dysplasia), usually as single case reports. The renal findings at autopsy of four patients with Alagille's syndrome, ranging in age from 4 1/2 months to 7 years, 2 of whom had evidence of renal dysfunction, are described and are compared with kidneys from patients with other cholestatic liver diseases of childhood. Two of the Alagille's patients had histologic findings suggestive of membranous nephropathy and special stains revealed accumulation of lipid in the glomerular and tubular basement membranes. Immunofluorescence of 1 revealed extensive accumulation of IgG and IgM. One patient had medullary cysts and mild interstitial fibrosis, and the fourth had a large subcapsular cyst and mild tubulointerstitial nephritis. All 4 cases, when examined with the electron microscope, revealed varying degrees of basement membrane thickening, splitting, and vacuolation with dense osmiophilic particles, most prominent in the patients with membranous nephropathy. These ultrastructural findings did not correlate with the degree of hyperlipidemia, but rather with the patient's age, and were also observed in other cholestatic diseases. The findings suggest that Alagille's syndrome is frequently associated with renal abnormalities, including lipid deposition, which may in some instances, lead to clinically significant renal impairment.

Basement Membrane↗
PubMed1987

Triiodothyronine-induced cyst formation in metanephric organ culture: the role of increased Na-K-adenosine triphosphatase activity.

Previous organ culture investigations into the pathogenesis of renal cyst formation have demonstrated that glucocorticoid-induced proximal tubular cyst formation is associated with increases in renal sodium-potassium adenosine triphosphatase (Na-K-ATPase) activity. To explore the relationship between cyst production and transport enzyme induction, we examined the effects of the potent inducer of Na-K-ATPase activity, L-3,5,3'-triiodothyronine (T3), on renal tubular morphologic and enzymatic development in murine metanephric organ culture. The addition of T3 (2 X 10(-8) mol/L) to completely characterized, serum-free growth medium produced striking proximal tubular cystic abnormalities. Frank cyst development was preceded by ultrastructural alterations consisting of basolateral intercellular spreading, which increased with progressive tubular dilation. Ultrastructural analysis demonstrated no abnormalities of tubular cyst wall basal laminae, and immunohistologic staining with affinity-purified antibodies to the basal lamina glycoproteins fibronectin, laminin, and entactin, revealed no differences between cystic and control tissue. With use of an enzyme-linked kinetic microassay, T3-induced cystic organ culture explants (CY) showed significant increases in Na-K-ATPase when compared with controls from 72 to 120 hours of organ culture incubation. The initial differences in CY Na-K-ATPase occurred contemporaneously with the earliest ultrastructural evidence of cyst formation, and subsequent increases paralleled progressive tubular cyst formation. Tubular cyst formation in CY could be largely prevented by daily incubation of explants with ouabain, 0.2 mmol/L (final concentration) for 120 minutes without deleterious effects on overall metanephric development. We conclude that T3 induces proximal tubular cyst formation in metanephric organ culture, and that T3-induced increases in Na-K-ATPase have a primary role in the pathogenesis of tubular cyst formation in this model system.

Animals↗