Search PubMed⌕ Search

Biomedical subjects

P Stanley

Publications and source records attributed to P Stanley.

At least 127 records · Page 7Linked to original sources
PubMed1990

Lectin-resistant CHO cells: selection of seven new mutants resistant to ricin.

In attempts to isolate new CHO glycosylation mutants, selection protocols using plant lectins that bind galactose residues of cell surface carbohydrates were applied to mutagenized CHO populations. The lectins were used alone or in combination to obtain seven ricin-resistant phenotypes. Each mutant had distinctive properties compared with previously described ricin-resistant CHO cells. One of the new phenotypes was dominant in somatic cell hybrids, and the others were recessive. Complementation analyses between related lectin-resistant (LecR) phenotypes indicated that each new isolate represented a novel genotype. Five of the mutants had properties typical of new CHO glycosylation mutants. The remaining two mutants were not readily categorized. Although they did not appear to be ricin-internalization or protein-synthesis mutants, they also did not display the marked alterations in sensitivity to several lectins of different sugar specificity expected for glycosylation mutants. The seven new LecR mutants described in these studies brings the total number of different LecR CHO mutants isolated by this and other laboratories to about 40. Criteria for identifying new LecR mutations in CHO cells are discussed.

Animals↗
PubMed1990

Serial section-reconstruction of anomalous tracheobronchial branching patterns from CT scan images: bridging bronchus associated with sling left pulmonary artery.

The use of the technique of wax-plate serial section-reconstruction, based on contiguous axial plane CT images of the upper thorax, to prepare a replica of the central air-way (trachea and major bronchi) of an infant with sling left pulmonary artery type 2B, with bridging bronchus, abortive right main bronchus, and tracheal stenosis due to absence of the tracheal pars membranacea with "ring" tracheal cartilages is described. The technique is applicable to demonstration of the anatomic features of other abnormalities of branching pattern or caliber of the trachea and major bronchi.

Bronchi↗
PubMed1990

Plasma atrial natriuretic peptide after the Fontan procedure and total cavopulmonary connexion.

Plasma atrial natriuretic peptide was measured in 10 children undergoing the Fontan procedure and 3 children undergoing total cavopulmonary connexion. There was no significant difference in pre-operative plasma levels, but post-operative levels were significantly higher 48 hours after cardiopulmonary bypass in the Fontan group. There was no significant difference in plasma arginine vasopressin levels either pre- or post-operatively. Post-operative pleural effusions occurred in only 2 of the 10 patients undergoing the Fontan procedure, but were present in all 3 of those undergoing total cavopulmonary connexion. The release of atrial natriuretic peptide is an appropriate homeostatic response to volume loading and the impairment of this response in the early post-operative period may be of clinical importance.

Arginine Vasopressin↗
PubMed1990

Cloning and expression of N-acetylglucosaminyltransferase I, the medial Golgi transferase that initiates complex N-linked carbohydrate formation.

This laboratory has previously identified a human gene encoding N-acetylglucosaminyltransferase I (GlcNAc-TI; EC 2.4.1.101) by complementation of the glycosylation defect in the Lec1 Chinese hamster ovary (CHO) cell mutant. A phage lambda library prepared from genomic DNA of a tertiary Lec1 transfectant (3 degrees T) has now been used to obtain clones encoding an active GlcNAc-TI enzyme. A small genomic DNA fragment [approximately 4.6 kilobases (kb)], isolated from an Alupositive lambda clone, conferred human GlcNAc-TI activity upon transfection into Lec1 cells. An approximately 1.3-kb probe generated from this DNA fragment detected unique but distinct DNA fragments in human and CHO genomic DNA. The probe also hybridized to a poly(A)+ RNA of approximately 2.7 kb in human and CHO cells and allowed the isolation of a full-length cDNA encoding human GlcNAc-TI activity. The overall features of the cDNA and deduced protein sequence (445 amino acids) are typical of other Golgi transferases that are type II transmembrane proteins. Northern blot analysis with the same probe showed that Lec1 mutant cells also possessed an approximately 2.7-kb poly(A)+ RNA, indicating that the lec1 mutation is a point mutation.

Amino Acid Sequence↗
PubMed1990

Partial splenic embolization. An effective alternative to splenectomy for hypersplenism.

Splenectomy for massive splenomegaly and hypersplenism carries a significant morbidity and mortality. We have used partial splenic embolization (PSE) as an effective alternative to splenectomy. Ten PSE procedures were performed on nine patients without mortality and with minimal morbidity. The age of the patients ranged from 8 months to 32 years (mean 14 years). The causes of splenomegaly and hypersplenism included cystic fibrosis with cirrhosis (2), tyrosinemia and cirrhosis (1); thalassemia (1), hemophilia with Human Immune Deficiency Virus infection (2), chronic hepatitis with portal hypertension (1), malignant histiocytosis (1), and Wiskott-Aldrich Syndrome (1). All procedures were performed under local anesthesia with sedation. A percutaneous femoral artery approach to the splenic artery was used to deliver Ivalon sponge particles (280-800 microns) into the spleen. Splenic infarction was assessed by postembolization angiograms. All of the patients except one demonstrated improvement of hematologic parameters. In one patient, however, cytopenia improved only after a second embolization. In the total series, there was an early mean rise of 8,600/mm3 in the leukocyte count (range 2,900-14,900) and 212,000/mm3 in the platelet count (range 30,000-718,000). Follow-up ranged from 4 months to 7 years. Improvement of the blood picture has been persistent in seven of the eight patients who showed initial improvement. Transient procedural complications included fever (5), pleural effusion (2), pneumonia (1), and splenic abscess (1). One patient had paralytic ileus lasting for 10 days and one patient developed a streptococcal peritonitis 3 weeks after embolization. No patient developed pancreatitis or vascular compromise of other abdominal viscera.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Postoperative evaluation after end-to-end subclavian-left coronary artery anastomosis in anomalous left coronary artery.

In most instances of anomalous left coronary artery originating from the pulmonary artery, surgical treatment is recommended. Because establishment of a direct systemic to coronary blood flow is expected to provide the best recovery of left ventricular function, various corrective procedures have been proposed. Subclavian-left coronary artery anastomosis appears to be a logical approach. Four patients operated on at Sainte-Justine Hospital, at an average age of 33 months (27 to 44), with an end-to-end subclavian-left coronary artery anastomosis were evaluated 6 to 46 months postoperatively. The anastomosis was patent in all cases. End-diastolic volume index (74.6 +/- 24.7 versus 122.7 +/- 15.3 ml/m2) and ejection fraction (0.58 +/- 0.07 versus 0.33 +/- 0.06) were improved significantly. Subclavian-left coronary artery anastomosis appears to meet the main criteria for an optimal physiologic correction of anomalous left coronary artery: restoration of a two-coronary artery system, improvement of left ventricular function, and likelihood of long-term patency.

Anastomosis, Surgical↗
PubMed1989

Infantile hepatic hemangiomas. Clinical features, radiologic investigations, and treatment of 20 patients.

The clinical features, radiologic investigation, and treatment of 20 infants with hepatic hemangiomas are presented. Palpable abdominal mass (n = 18) and cardiac failure (n = 11) were the common presenting features. Nine patients had hyperconsumptive coagulopathy. Seven patients had other hemangiomas. Ultrasound (n = 15) showed the number and distribution of the hemangiomas within the liver. Hypoechoic and hyperechoic elements were present in addition to prominent vascular channels and diminished caliber of the distal aorta. Radionuclide sulfur colloid (n = 12) and labeled red blood cell (n = 7) studies showed the distribution and vascularity of the hemangiomas. Computed tomography (n = 8) revealed central hypointensity with marked peripheral enhancement after contrast. Arteriography now performed only as a prelude to therapeutic embolization demonstrated hypervascularity in each patient, contrast pooling in six and early draining veins in five. Magnetic resonance scanning (n = 3) showed decreased signal intensity on T1 images and high intensity signal on T2. In two patients, there was resolution or improvement of the hemangiomas without therapy. Four patients had surgery (lobectomy [2], trisegmentectomy [1], and surgical evacuation of a central hematoma [1]). Steroids and radiation were given to seven patients, and one patient also required therapeutic embolization. Steroids were the initial therapy in five patients, one of whom later required therapeutic embolization and another cyclophosphamide. Two patients were treated initially with radiation therapy, one of whom also needed emergency hepatic artery ligation. Seventeen of the 20 patients are alive and well from 6 months to 14 years after diagnosis.

Angiography↗
PubMed1989

Comparison of cardiovascular adjustments to exercise in adolescents 8 to 15 years of age after correction of tetralogy of fallot, ventricular septal defect or atrial septal defect.

Surgical correction of tetralogy of Fallot (TF) has generally been associated with a reduced maximal exercise tolerance, possibly related to the ventriculotomy inherent to the intracardiac repair procedure. This study documents the exercise hemodynamics of a group of patients operated on for TF who showed similar clinical and functional characteristics, and compares these responses to those of age-matched patients operated on for an isolated ventricular septal defect (VSD) or atrial septal defect (ASD) in an attempt to better understand the role of the ventriculotomy in the exercise limitation. Thirty patients, ages 12 to 19 years, operated on before 5 years of age for complete repair of TF (n = 13), VSD (n = 7) or ASD (n = 10) and 10 age-matched control subjects underwent a progressive maximal cycling test to determine the maximal oxygen uptake (VO2 max), and completed submaximal cycling at intensities of 33 and 66% VO2 max, respectively, to determine the cardiac output (CO2-rebreathing). No significant differences in VO2 max were observed (TF = 37.6 +/- 10; VDS = 34.0 +/- 9.2; ASD = 36.5 +/- 7; controls = 41.3 +/- 6.0 ml/kg/min). The maximal heart rate, however, remained lower in all patient groups in comparison with control subjects (p less than or equal to 0.05) (TF = 178 +/- 14; VSD = 172 +/- 17; ASD = 179 +/- 16; controls = 191 +/- 12 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1989

Molecular study of the T cell repertoire in family contacts and patients with leprosy.

The specificity of lymphocyte proliferative responses of 22 family contacts and 7 patients with leprosy were analyzed using Ag fractions from soluble extracts of Mycobacterium leprae and Mycobacterium tuberculosis. Fractions 10-100 kDa m.w. from each extract were separated by SDS-polyacrylamide gel electrophoresis, electroblotted to nitrocellulose membrane and solubilized for use in lymphocyte culture. The main immunogenic fractions for both contacts and patients had m.w. of 12,000 to 22,000, 35,000 to 40,000, and 65,000. Determinants which were either distinct or shared by the two extracts were active in each of the immunogenic fractions. Lymphocyte proliferation following stimulation with separated Ag was found also in five subjects who failed to respond to the whole soluble extracts. Stimulatory synthetic peptides were identified for the 65 kDa protein Ag. This technique has permitted the screening of the T cell immune repertoire for the identification of the immunodominant Ag which merit further purification and molecular characterization.

Adult↗
PubMed1989

Novel genetic instability associated with a developmentally regulated glycosyltransferase locus in Chinese hamster ovary cells.

LEC10 is a dominant glycosylation mutant of Chinese hamster ovary (CHO) cells that expresses a developmentally regulated glycosyltransferase (GlcNAc-TIII) not detectable in parental CHO cells. Several mutagens were found to increase the frequency of LEC10 mutants up to 10-fold over the spontaneous frequency of less than or equal to 10(-7), while 5azaC treatment had no effect. Revertants were obtained at high frequency (approximately 10(-4)) and were found to belong to two classes. Three independent revertants gave rise to new LEC10 mutants at high frequency (approximately 10(-4)) while seven others gave new LEC10 mutants at the low frequency typical of unmutagenized parental CHO cells. No evidence of a general mutator phenotype was found in the revertant lines with a high rereversion frequency. The combined data suggest a novel form of genomic instability at the LEC10 locus in CHO cells. Genetic events that affect the expression of developmentally regulated glycosyltransferases may be identified by further studies of LEC10 and other dominant CHO glycosylation mutants.

Animals↗
PubMed1989

The Lec4A CHO glycosylation mutant arises from miscompartmentalization of a Golgi glycosyltransferase.

Two CHO glycosylation mutants that were previously shown to lack N-linked carbohydrates with GlcNAc beta 1,6Man alpha 1,6 branches, and to belong to the same genetic complementation group, are shown here to differ in the activity of N-acetylglucosaminyltransferase V (GlcNAc-TV) (UDP-GlcNA: alpha 1,6mannose beta-N-acetylglucosaminyltransferase V). One mutant, Lec4, has no detectable GlcNAc-TV activity whereas the other, now termed Lec4A, has activity equivalent to that of parental CHO in detergent cell extracts. However, Lec4A GlcNAc-TV can be distinguished from CHO GlcNAc-TV on the basis of its increased sensitivity to heat inactivation and its altered subcellular compartmentalization. Sucrose density gradient fractionation shows that the major portion of GlcNAc-TV from Lec4A cells cofractionates with membranes of the ER instead of Golgi membranes where GlcNAc-TV is localized in parental CHO cells. Other experiments show that Lec4A GlcNAc-TV is not concentrated in lysosomes, or in a post-Golgi compartment, or at the cell surface. The altered localization in Lec4A cells is specific for GlcNAc-TV because two other Lec4A Golgi transferases cofractionate at the density of Golgi membranes. The combined data suggest that both lec4 and lec4A mutations affect the structural gene for GlcNAc-TV, causing either the loss of GlcNAc-TV activity (lec4) or its miscompartmentalization (lec4A). The identification of the Lec4A defect indicates that appropriate screening of different glycosylation-defective mutants should enable the isolation of other mammalian cell trafficking mutants.

Animals↗
PubMed1989

The material tensile strength of convex-faced aspirin tablets.

The material tensile strength of a range of convex-faced tablets, compacted under controlled conditions at pressures of 40 and 320 MPa from a size fraction of acetylsalicylic acid, has been assessed. The calculation of the tensile strength sigma 1, from observed fracture loads obtained in diametral compression testing, is based on the equation derived by Pitt et al (1988), namely: (formula; see text) where P is the fracture load, D is the tablet diameter, t is the overall tablet thickness and W is the central cylinder thickness. The strength of a tablet of a given shape compacted at 320 MPa was between two and four times greater than that of a similar tablet compacted at 40 MPa. For the thicker tablets (W/D greater than or equal to 0.2) the material tensile strength was practically independent of shape. For the thinner tablets (W/D = 0.1) the material tensile strength varied considerably with face-curvature, showing a maximum for each of the two compaction pressures at a D/R value of 0.67.

Aspirin↗
PubMed1989

Characterization of cell surface carbohydrate receptors for Entamoeba histolytica adherence lectin.

Binding and cytolysis of Chinese hamster ovary (CHO) cells by Entamoeba histolytica trophozoites is inhibitable by galactose (Gal) or N-acetyl-D-galactosamine (GalNAc). To better define the carbohydrate receptor for E. histolytica, we compared the binding and cytolytic target properties of 10 CHO glycosylation mutants. Each mutant expresses a uniquely altered array of N- and/or O-linked cell surface carbohydrates. Amebic adherence was reduced when lactosamine-containing N-linked carbohydrates were essentially absent (Lec1 mutant), almost undetectable when Gal and GalNAc residues were absent on both N- and O-linked carbohydrates (ldlD.Lec1 mutant), and enhanced for mutants with increased terminal Gal residues (Lec2 and Lec3). Parental CHO cells treated with neuraminidase to expose Gal residues behaved like Lec2 mutants. Binding of purified Gal or GalNAc lectin to parental, Lec1, ldlD.Lec1, and Lec2 mutant CHO cells corroborated the adherence results. The suitability of CHO cell mutants as targets for amebic cytolysis correlated with their glycosylation phenotype: the Lec1 mutants were less susceptible than parental CHO cells, the ldlD.Lec1 mutants were highly resistant, and the Lec2 mutants required higher concentrations of Gal for inhibition. The E. histolytica Gal or GalNAc adherence lectin bound preferentially to beta 1-6-branched, N-linked carbohydrates lacking terminal sialic acid or fucose residues. However, amebic lectin binding to either N- or O-linked cell surface carbohydrates was sufficient to initiate parasite cytolytic activity.

Acetylgalactosamine↗
PubMed1989

Transfection of a human gene that corrects the Lec1 glycosylation defect: evidence for transfer of the structural gene for N-acetylglucosaminyltransferase I.

Chinese hamster ovary (CHO) glycosylation mutants provide an approach to cloning mammalian glycosyltransferases by transfection and gene rescue. In this paper, complementation of the lec1 CHO mutation by human DNA is described. Lec1 transfectants expressed human N-acetylglucosaminyltransferase I (GlcNAc-TI) activity and possessed common human DNA fragments. Cloning of GlcNAc-TI should therefore be possible.

Animals↗
PubMed1989

Chinese hamster ovary cell mutants with multiple glycosylation defects for production of glycoproteins with minimal carbohydrate heterogeneity.

The production of glycoproteins with carbohydrates of defined structure and minimal heterogeneity is important for functional studies of mammalian carbohydrates. To facilitate such studies, several Chinese hamster ovary mutants that carry between two and four glycosylation mutations were developed. All of the lines grew readily in culture despite the drastic simplification of their surface carbohydrates. Therefore, both endogenous glycoproteins and those introduced by transfection can be obtained with specifically tailored carbohydrates. The lectin resistance properties of the mutants showed that each line expresses a novel array of cell surface carbohydrates useful for identifying specific roles for carbohydrates in cellular interactions. In addition, they showed that the epistatic relationships among different glycosylation mutations are not entirely predictable, providing insight into the complexity of the carbohydrate structures at the Chinese hamster ovary cell surface.

Animals↗
PubMed1989

Control of carbohydrate processing: increased beta-1,6 branching in N-linked carbohydrates of Lec9 CHO mutants appears to arise from a defect in oligosaccharide-dolichol biosynthesis.

A correlation between increased beta-1,6 branching of N-linked carbohydrates and the ability of a cell to metastasize or to form a tumor has been observed in several experimental models. Lec9 Chinese hamster ovary (CHO) mutants exhibit a drastic reduction in tumorigenicity in nude mice, and this phenotype directly correlates with their ability to attach an increased proportion of beta-1,6-branched carbohydrates to the G glycoprotein of vesicular stomatitis virus (J. Ripka, S. Shin, and P. Stanley, Mol. Cell. Biol. 6:1268-1275, 1986). In this paper we provide evidence that cellular carbohydrates from Lec9 cells also contain an increased proportion of beta-1,6-branched carbohydrates, although they do not possess significantly increased activity of the beta-1,6 branching enzyme (GlcNAc-transferase V). Biosynthetic labeling experiments show that a substantial degree of underglycosylation occurs in Lec9 cells and that this affects several classes of glycoproteins. Lec9 cells synthesize ca. 40-fold less Glc3Man9GlcNAc2-P-P-lipid and ca. 2-fold less Man5GlcNAc2-P-P-lipid than parental cells do. In addition, Lec9 cells possess ca. fivefold less protein-bound oligosaccharide intermediates, and one major species is resistant to release by endo-beta-N-acetylglucosaminidase H (endo H). Membranes of Lec9 cells exhibit normal mannosylphosphoryldolichol synthase, glucosylphosphoryldolichol synthase, and N-acetylglucosaminylphosphate transferase activities in the presence of exogenous dolichyl phosphate. However, in the absence of exogenous dolichyl phosphate, mannosylphosphoryldolichol synthase and glucosylphosphoryldolichol synthase activities are reduced in membranes of Lec9 cells, indicating that membranes of Lec9 cells are deficient in lipid phosphate. This was confirmed by analysis of lipids labeled by [3H]mevalonate, which showed that Lec9 cells have less lipid phosphate than parental CHO cells. Mechanisms by which a defect in the synthesis of dolichol-oligosaccharides might alter the degree of beta-1,6 branching in N-linked carbohydrates are discussed.

Animals↗