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Biomedical subjects

R E Steele

Publications and source records attributed to R E Steele.

At least 73 records · Page 4Linked to original sources
PubMed1986

Extracorporeal shock wave lithotripsy in patients with a solitary kidney.

Extracorporeal shock wave lithotripsy was used to treat 68 patients with renal calculi in a solitary kidney. Epidemiological information, including stone number, size and location, was similar to that of other patients treated with extracorporeal shock wave lithotripsy. Renal function as measured by serum creatinine changed negligibly in the majority of the patients. Three patients had transient serum creatinine elevations greater than 2 mg. per dl. that were caused by obstruction from stone fragments. There were 2 perirenal hematomas that required transfusion. One patient required retrograde manipulation of a ureteral stone before extracorporeal shock wave lithotripsy, while 6 required stone manipulations after therapy for steinstrasses. Of 59 patients evaluable after extracorporeal shock wave lithotripsy 58 (98.3 per cent) had a successful result: 38 (64.4 per cent) were completely free of stones and 20 (33.9 per cent) had clinically insignificant residual fragments. Extracorporeal shock wave lithotripsy is effective and safe in a solitary renal unit. We believe that in most patients it is the procedure of choice. Attention to fever, urine output and fragment size perioperatively is crucial.

Adolescent↗
PubMed1986

Combined percutaneous and extracorporeal shock wave lithotripsy for staghorn calculi: an alternative to anatrophic nephrolithotomy.

Combinations of percutaneous and extracorporeal shock wave lithotripsy were performed on 46 patients with 52 staghorn calculi. Of the renal units 15 per cent had minute residual fragments but only 9.7 per cent with struvite had residual stones. The morbidity of this combined approach is less than that of anatrophic nephrolithotomy. We believe that the majority of staghorn calculi can be removed in this manner. Nephrostolithotomy should be the initial procedure in most instances. This less invasive approach is especially advantageous in patients at high risk for recurrence.

Adolescent↗
PubMed1986

Extracorporeal shock wave lithotripsy: the Methodist Hospital of Indiana experience.

A total of 982 patients underwent 1,416 treatments with extracorporeal shock wave lithotripsy for upper urinary tract calculi between February 23 and December 17, 1984. A single treatment was performed in 90 per cent of the patients. Morbidity was extremely low and hospital stay was short (3.0 days). Adjunctive procedures were required in 13 per cent of the patients. Of the kidneys 72 per cent were free of stones at the 3-month followup, while 23 per cent contained small (less than 5 mm.), asymptomatic fragments believed to be passable spontaneously. Only 1 per cent of the patients required surgical removal of the calculi. Morbidity was related directly to stone burden, while results were inversely related to stone burden. Extracorporeal shock wave lithotripsy is the preferred form of management for symptomatic upper ureteral and renal calculi less than 2 cm. in diameter.

Adolescent↗
PubMed1986

Ureteral stone management: emerging concepts.

A total of 206 procedures was performed on 193 patients with ureteral calculi. The success rate was 62 per cent for stones proximal to the pelvic brim and 94 per cent for stones distal to the pelvic brim (87 per cent success over-all). Of the procedures 61 were done for fragments lodged in the ureter following extracorporeal shock wave lithotripsy. Ureteroscopy was done in 147 cases. Our current management concepts (including extracorporeal shock wave lithotripsy) for proximal and distal ureteral calculi are presented.

Adult↗
PubMed1986

Porous-bottom dishes for culture of polarized cells.

Porous-bottom dishes offer several advantages for growing and studying epithelia in culture. Many epithelia differentiate more on porous surfaces than on plastic tissue culture dishes. In addition, separate solutions can be maintained on each side of the epithelium and can be sampled easily for studies of transport and other polarized functions. We describe the fabrication of dishes with a cellulose ester filter, a collagen-coated polycarbonate filter, or a collagen membrane forming the surface for cell attachment at the bottom of the dish.

Animals↗
PubMed1985

Two divergent cellular src genes are expressed in Xenopus laevis.

Genomic and cDNA clones of the X. laevis src gene have been isolated and characterized by hybridization and DNA sequence analyses. The haploid genome of X. laevis contains two src genes, which can be distinguished from one another by virtue of sequence divergence in the 3' untranslated regions. Both of the genes are functional as indicated by the fact that oocytes contain RNAs transcribed from each of the genes. The two genes each encode an RNA which is 3.3 kb in length, or twice the length required to encode the 60,000 dalton src protein (pp60). Sequence analysis of the cDNA clones revealed that nearly all of the non-coding sequence is located at the 3' end. The availability of sequence data from cDNA clones has also made it possible for the first time to identify with certainty the carboxyl terminal sequence of a cellular pp60 molecule.

Amino Acid Sequence↗
PubMed1985

Effects of altered endocrine function on biliary metabolites of [4-14C]androst-4-ene-3,17-dione in rats. Possible utility as a model for identifying anti-atherosclerotic agents.

Atherosclerosis, coronary artery disease and elevated serum cholesterol are frequently associated with an abnormal pattern of androgen metabolites, especially an elevation of etiocholanolone (E) and/or epiandrosterone (EA) relative to androsterone (A). Therapeutic correction of these metabolic defects may lower serum cholesterol. We have attempted to reproduce this metabolic syndrome in rats by altering their endocrine status. Intact male rats excreted very little A or E in their bile; more than 80% of the [4-14C]A-dione was excreted as unknown polar compounds. Adrenalectomy, thyroidectomy or streptozotocin diabetes induced little or no change in the excretion of both E and A and did not alter the A/E ratio. Hypophysectomy (hypox), however, resulted in a huge increase in E excretion and a 10-fold decrease in the A/E ratio. Treatment of hypophysectomized males with bovine growth hormone (bGH) but not testosterone or thyroxine restored the pattern of androgen metabolites to that of intact male rats. Intact female rats excreted mainly A, and this was decreased by ovariectomy. Hypophysectomy, however, resulted in a marked increase in E and a corresponding large decrease in A excretion. Treatment of hypox females with estradiol or triiodothyronine did not correct the metabolic defects in A and E production, whereas GH resulted in a pattern of A-dione metabolism resembling that of intact males; i.e., primarily polar metabolites with low A and E. Hypophysectomy thus results in a dramatic increase in 5 beta-reductase activity in male and female rats. GH therapy restores the metabolic pathway to that seen in intact males. Our objective had been to find a model capable of detecting substances which would increase A and decrease E production. The male rat (regardless of endocrine status) has little 5 alpha-reductase activity. The intact female rat, however, has high 5 alpha-reductase activity, and retains significant 5 alpha-reductase in the absence of the ovaries. In hypox females, 5 alpha-reductase was much reduced while 5 beta-reductase was increased. Furthermore, serum cholesterol was elevated in hypox females but could be lowered by exogenous androsterone. Thus the hypox female rat appears to offer the best model for identifying non-hormonal agents which could enhance the production of A and/or decrease the production of E. Such agents might favorably influence cholesterol metabolism.

Androstenedione↗
PubMed1985

Identification of potential antiatherosclerotic/hypolipidemic agents by their effect on hepatic conversion of androst-4-ene-3,17-dione to etiocholanolone and androsterone.

Clinical observations have shown that hypercholesterolemia is associated with abnormal androgen metabolism, viz. an increased excretion of etiocholanolone (E) relative to androsterone (A). Substances which restore the A/E ratio to normal likewise lower serum cholesterol. Postulating that the abnormal steroid and sterol metabolism may be either causally related or dependent on the same metabolic defect, we have developed in vitro and in vivo models to select drugs which favorably effect the ratio of A to E produced from [4-14C]androst-4-ene-3,17-dione [4-14C]A-dione). The in vitro model employs a mixture of rat liver microsomal delta 4-3-ketosteroid-5 alpha-reductase and cytosolic 3 alpha-hydroxysteroid dehydrogenase and delta 4-3-ketosteroid-5 beta-reductase. Kinetic and mechanistic studies have been performed on active compounds using this in vitro assay. The in vivo model employs i.v. injection of [4-14C]A-dione followed by collection of bile in anesthetized, hypophysectomized female rats. Many compounds preselected in the in vitro assay likewise reduced the A/E ratio in vivo. One of these compounds (CGS 10614A) also lowered serum cholesterol and reduced the incidence and severity of atherosclerotic lesions in aortas of cholesterol-fed rabbits.

3-Hydroxysteroid Dehydrogenases↗
PubMed1985

Effects of aminoglutethimide on cervical dilatability and serum immunoreactive relaxin in pregnant rats.

Administration of aminoglutethimide (AG) at a daily sc dose of 20 mg/kg to rats from the 10th to 20th days of pregnancy resulted in fetal wastage, increased placental weights, and decreased placental alkaline phosphatase. In an effort to determine the endocrine problems relating to these abnormalities, serum relaxin (R) and progesterone (P) levels were determined by RIA and cervical distensibility was measured: All three parameters were subnormal in AG-treated rats. Therapy with estrogen (E) or (P) failed to correct any of the physiological problems associated with AG treatment, but a combination of these steroids increased fetal survival to control levels. However, cervical dilation in preparation for parturition failed to occur. Relaxin therapy alone increased cervical dilation but did not enhance fetal survival. A combination of E, P, and R maintained a normal complement of fetuses and provided normal cervical dilation. None of the treatments prevented placental enlargement but P treatment tended to maintain normal placental alkaline phosphatase.

Aminoglutethimide↗
PubMed1984

Factors affecting the differentiation of epithelial transport and responsiveness to hormones.

Under standard culture conditions, epithelial cells grow with their basal surface attached to the culture dish and their apical surface facing the medium. Morphological and functional markers are located in the appropriate plasma membrane, and transepithelial transport occurs in a variety of cultured epithelia. As a result of the polarity of the cells and the presence of tight junctions between cells, on standard tissue culture dishes there is restricted access of growth medium to the basolateral surface of the epithelium, which is the surface at which nutrient exchange normally occurs. Greater differentiation of epithelial cultures can be achieved by growing primary cultures or continuous cell lines on permeable surfaces such as porous bottom cultures dishes in which the porous bottom is formed by a filter or membrane of collagen, or on floating collagen gels. In many cultures, differentiation varies with the time after the culture was seeded. Certain chemicals that accelerate differentiation in nonepithelial cells also accelerate the differentiation of epithelial cultures. Ultimately, defined media and specific substrates for cell attachment should lead to further differentiation of epithelia in culture.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1984

Anucleolate frog embryos contain ribosomal DNA sequences and a nucleolar antigen.

Previous studies of Xenopus laevis embryos homozygous for the nucleolar deletion mutation have concluded that these embryos contain few, if any, copies of the genes for the 18 S and 28 S ribosomal RNAs. Using hybridization to restriction endonuclease digests of DNA it is found, in fact, that a small amount of ribosomal DNA is still present in such embryos. The ribosomal DNA in these embryos appears to include a few normal repeats together with a variety of unusual fragments containing either spacer or gene sequences. An antibody found in the serum of a scleroderma patient reacts with an antigen localized in the nucleoli of wild-type embryos. In anucleolate embryos this antigen is found in the so-called pseudonucleoli and in many small bodies in the nuclei.

Animals↗
PubMed1984

Plasmids containing mouse rDNA do not recombine with cellular ribosomal genes when introduced into cultured mouse cells.

We have examined the fate of plasmids containing a segment of a mouse rDNA repeat after they were introduced by transfection into cultured mouse cells. In addition to the rDNA segment, the plasmids contained the thymidine kinase gene from herpes simplex virus 1 to allow for selection of the plasmid after transfection into thymidine kinase-deficient mouse cells. Thus far, no cases of homologous recombination between transfected plasmid DNAs and host cell sequences have been documented. We reasoned that the high repetition frequency of the rRNA genes in the mouse genome (200 copies per diploid cell) might create a favorable situation for obtaining homologous recombination events between the plasmids containing rDNA and host cell rDNA sequences. The plasmids were introduced into cells in both the presence and the absence of carrier DNA and both as covalently closed circles and linear molecules. The sites of plasmid integration in the genomes of various cell lines were examined by DNA restriction digests and hybridization, molecular cloning, and nuclear fractionation. In the seven cell lines examined, there was no evidence that the plasmids had integrated into the rRNA gene clusters of the cell. Thus, the apparent absence of site-specific integration of cloned DNAs introduced into mammalian cells does not appear to be due simply to the small target presented by most host cell sequences.

Animals↗
PubMed1981

Carbon dioxide permeability of rabbit proximal convoluted tubules.

CO2 kinetics were studied under conditions in which CO2 partial pressure and either the bicarbonate or hydrogen ion concentrations were unequal in perfusate and bath. A glass pH microelectrode and microcalorimeter were used to measure pH and total CO2 in perfused and collected fluids. Luminal appearance or disappearance of CO2 was determined from the change in concentrations of CO2 and acidic moieties of the buffers between perfused and collected fluids. The pH was not measurably affected by the tubule processes of metabolism, hydrogen ion secretion, and buffer transport because of relatively high flow rates. Since CO2 appearance and disappearance were directly related to CO2 partial pressure differences across the tubule (r = 0.94), this technique provides a valid estimate of transepithelial CO2 flux in response to the driving force of a CO2 partial pressure difference. From flux per unit of driving force and from estimates of resistances to CO2 diffusion in both internal and external unstirred layers, we obtained a transepithelial CO2 permeability of approximately 10(-4) cm3 . s-1 . cm tubule length-1. This corresponds to a diffusion coefficient through the tubule epithelium about half that through an equivalent thickness of water. We conclude that rabbit proximal convoluted tubules are so highly permeable to CO2 that even if all the filtered bicarbonate were reabsorbed by the generation of CO2 in the lumen, the tubular fluid CO2 partial pressure would exceed that of the peritubular blood by less than 4 mmHg.

Absorption↗
PubMed1981

Epithelial organization and hormone sensitivity of toad urinary bladder cells in culture.

Two continuous cell lines (TB-M and TB-6c) derived from epithelial cells of the toad urinary bladder form epithelia in culture that manifest hormone-sensitive transepithelial transport. Development of transepithelial electrical resistance (R) and transport rate (ISC) are dependent on time and density of cells seeded, but steady-state ISC and R are characteristic for each cell line and independent of seeding density. Some responses of intact toad bladder are preserved in culture, whereas others are altered or absent. Neither cell line responds to vasopressin. Analogues of cAMP increase sodium transport and urea permeability in both cell lines but do not affect water permeability. The intramembrane particle aggregates associated with the vasopressin- and cAMP-induced increase in water permeability of the intact bladder could not be detected in the cell lines. Aldosterone increases sodium transport in both cell lines, and the time course and concentration dependence of the response to aldosterone are similar to those of the intact bladder. The relative effect of a series of steroids on ISC reveals corticosterone to be a more potent mineralocorticoid in cultured cells than in the intact bladder.

Animals↗
PubMed1980

Ordered distribution of modified bases in the DNA of a dinoflagellate.

In DNA of the dinoflagellate Crypthecodinium cohnii, 38% of the thymine is replaced by the modified base 5-hydroxymethyluracil, and approximately 3% of the cytosine is replaced by 5-methylcytosine. Both of the modified bases are non-randomly distributed in the DNA. Determinations of 3' nearest neighbors show that HOMeU is preferentially located in the dinucleotides HOMeUpA and HOMeUpC. Pyrimidine tract analysis shows that HOMeU is also greatly enriched in the trinucleotide purine-HOMeU-purine. As in other eukaryotes, methylcytosine in C. cohnii DNA occurs predominantly in the dinucleotide MeCpG. By analysis of restriction endonuclease digestion patterns of C. cohnii total DNA and ribosomal DNA, we have found that the central CpG dinucleotides in the sites for the enzymes Hpa II (CCGG) and Hha I (GCGC) are extensively methylated in both total DNA and ribosomal DNA. Results of digestion with Ava I, however, indicated that not all CpG dinucleotides in the sequence CCTCGGAG are methylated in C. cohnii DNA.

Animals↗
PubMed1979

Absence of cytosine methylation at C-C-G-G and G-C-G-C sites in the rDNA coding regions and intervening sequences of Drosophila and the rDNA of other insects.

Cytosine residues in C-G dinucleotides are frequently methylated in eukaryote DNA. In DNA of the dinoflagellate C. cohnii, the sequence C-MeC-G-G apparently renders Hpa II (C-C-G-G) incapable of digesting whole cell DNA in general, and rDNA in particular. Msp I, which also recognizes C-C-G-G but cleaves irrespective of methylation, degrades C. cohnii DNA and produces rDNA segments of 10.2 to 1.4 kb. We have applied this Hpa II/Msp I test to unfractionated DNA, and to rDNA and the rDNA intervening sequence of Drosophila virilis embryos and adults. There is no evidence of C-MeC-G-G sequences in either developmental stage of this species. Absence of G-MeC-G-C from coding and intervening sequences of rDNA was shown in comparisons of Hha I (G-C-G-C) cleavage patterns of unfractionated DNA and cloned (unmodified) segments of rDNA. Comparisons of Hpa II and Msp I cleavage products of DNA from the house fly, the flesh fly and a bumblebee also revealed no internal cytosine methylation in the sequence C-C-G-G. Because amounts of McC in C-G dinucleotides vary greatly among species, from apparent nonexistence to substantial proportions, no inference may yet be drawn about the role of such base modifications in DNA.

Animals↗
PubMed1979

Toad urinary bladder epithelial cells in culture: maintenance of epithelial structure, sodium transport, and response to hormones.

Epithelial cells from the toad urinary bladder have been grown in continuous culture. Many of the cells resemble the granular cell type of the urinary bladder. They form an epithelium with typical tight junctions and gap junctions. The transport properties of two cell lines have been examined. When cells of the line designated TB-M or of line TB-6c are grown on collagen-coated nucleopore filters, epithelia are formed that have transepithelial potential differences of 40 and 20 mV, resistances of 5000 and 10,000 omega-cm2, and short-circuit currents (ISC) of 8.5 and 2.5 muA/cm2, respectively. Net mucosa to serosa sodium transport accounts for all of ISC in line TB-M and for 70% of ISC in line TB-6c. Vasopressin, which stimulates adenylate cylase and ISC in the intact bladder, has no effect on the cells in culture. Cyclic AMP stimulates ISC and lowers resistance in both lines. Aldosterone stimulates ISC in both lines. This is accompanied by a fall in resistance in line TB-M and no change in resistance in line TB-6c. Amiloride inhibits ISC in TB-M cells under basal conditions and after stimulation by aldosterone. In line TB-6c amiloride has no effect under basal conditions but lowers ISC of aldosterone-treated cells to the basal level. Thus, the cells have retained the ability to form oriented, high-resistance epithelial membranes that manifest hormone-sensitive transepithelial sodium transport.

Aldosterone↗