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Biomedical subjects

R W Allen

Publications and source records attributed to R W Allen.

At least 37 records · Page 2Linked to original sources
PubMed1991

Attenuation of the pressor response to tracheal intubation in hypertensive proteinuric pregnant patients by lignocaine, alfentanil and magnesium sulphate.

The pressor response to intubation is known to be exaggerated in patients with gestational proteinuric hypertension (GPH). The effect of pretreatment with lignocaine 1.5 mg kg-1, magnesium sulphate 40 mg kg-1 or alfentanil 10 micrograms kg-1 on this pressor response was studied in 69 patients with moderate to severe GPH. Systolic arterial pressure exceeded baseline values for the first 5 min after tracheal intubation in the lignocaine group, with a peak increase of 31.6 (SEM 3.6) mm Hg at 2 min after intubation, but no mean increase in pressure occurred in the two other groups. Following intubation, six of 24 mothers in the alfentanil group, six of 21 in the lignocaine group and one of 24 in the magnesium group (P less than 0.05) exhibited a systolic arterial pressure (SAP) greater than 180 mm Hg sustained for 2 min or more. Alfentanil caused the least change in heart rate, but resulted in significant fetal depression.

Alfentanil↗
PubMed1990

Anaesthetic hazards of the 'passion gap'. A case report.

Dental abnormalities cause problems for both dentist and anaesthetist. The anaesthetic hazards associated with the 'passion gap'--a term used in the western Cape Province for removal of the top four incisor teeth, a practice widespread among members of the Cape Coloured community--are discussed. Recommendations are made to assist the anaesthetist when dealing with such a patient.

Adult↗
PubMed1987

Identification of the 37-kDa protein displaying a variable interaction with the erythroid cell membrane as glyceraldehyde-3-phosphate dehydrogenase.

In previous studies from this laboratory we isolated and characterized a 37-kDa protein that was associated with the membrane of erythroid cells. The polypeptide appeared to undergo a lineage-specific alteration in its interaction with the membrane during erythroid development and migrated as a family of isoelectric focusing variants during analyses on two-dimensional gels. We report here that the 37-kDa protein is homologous to the enzyme glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12). This conclusion was reached from the results of several experimental approaches comparing the biochemical and genetic properties of the 37-kDa protein (p37) with authentic glyceraldehyde-3-phosphate dehydrogenase. Peptide maps of highly purified p37 and glyceraldehyde-3-phosphate dehydrogenase, generated with Staphylococcus V8 protease, were identical. The nucleotide sequence of a cDNA clone encoding p37 was nearly identical to the published sequence for genes encoding glyceraldehyde-3-phosphate dehydrogenase. These results suggest that the interaction of the enzyme with the red cell membrane is more complex than previously envisioned. The existence of subpopulations of glyceraldehyde-3-phosphate dehydrogenase molecules is envisioned that exhibit different levels of enzyme activity and bind to the red cell membrane with varying affinities.

Base Sequence↗
PubMed1986

Isolation and characterization of a 37,000-dalton protein associated with the erythrocyte membrane.

We have purified a 37,000-dalton polypeptide (p37) from the red cell membrane that was found in previous studies to undergo a lineage-specific alteration in its membrane association. Our data suggest that p37 associates with the red cell membrane through electrostatic interactions that are resistant to 0.5 M NaCl or 10 mM EDTA. Conditions found to elute p37 from red cell ghosts include H2O at pH 12, 0.1 N NaOH + 1 mM ethanol and 1.0% Triton X-100. p37 was purified substantially from ghosts by Triton X-100 solubilization followed by sequential DEAE-Sephadex and CM-Sephadex chromatography. When p37 was analyzed by two-dimensional gel electrophoresis, a family of isoelectric focusing variants was detected ranging in pI from 7.0 to 7.8. All of the isoelectric focusing variants showed homology to one another when compared serologically with anti-p37 antibodies or by limited peptide mapping using Staphylococcus aureus V8 protease. The isoelectric focusing variants appear to represent distinct, yet related polypeptides rather than degrees of post-translational modifications to a single species, inasmuch as all of the variants are present in anti-p37 immunoprecipitates prepared from in vitro translations programmed with p37 mRNA.

Cell Line↗
PubMed1985

Quantitation of membrane glycoprotein IIIa on intact human platelets using the monoclonal antibody, AP-3.

A murine monoclonal antibody specific for glycoprotein (GP)IIIa was prepared by immunization with a GPIIb- and GPIIIa-enriched Triton X-114 extract of platelet membranes. This antibody, designated AP-3, was shown by indirect immunoprecipitation to react solely with GPIIIa derived from either P1A1-positive or -negative individuals. The epitope on GPIIIa recognized by AP-3 is expressed on dissociated GPIIIa as well as on Ca+2-dependent complexes of GPIIb and GPIIIa, as shown by crossed immunoelectrophoresis in the presence or absence of EDTA. A previously described monoclonal antibody specific for the GPIIb/IIIa complex (AP-2) inhibited platelet aggregation induced by ADP, thrombin, collagen, or arachidonic acid (Pidard et al, J Biol Chem 258:12582-12586, 1983). In contrast, AP-3 had no effect on aggregation induced by any of these reagents, a finding similar to that previously reported for the GPIIb-specific monoclonal antibody, Tab (McEver et al, J Clin Invest 66:1311-1318, 1980). At saturation, 40,200 AP-3 molecules were bound per platelet, a value similar to that obtained for AP-2 or Tab. Thus, data derived using AP-3 indicate that significant amounts of free GPIIIa are not present, thereby supporting the hypothesis that GPIIb and GPIIIa exist complexed in a 1:1 stoichiometry in the plasma membrane of intact, nonactivated platelets.

Animals↗
PubMed1985

Characterization of the processed form of a ubiquitous protein displaying a variable membrane organization in erythroid cells.

We recently identified a group of proteins that are present in all hematopoietic cells but are organized in the cell membrane of erythrocytes in a lineage-specific fashion (Blood 61:803, 1983). One of these polypeptides has a mol wt of approximately 37,000 (p37T) when translated in vitro from messenger RNA (mRNA) extracted from the erythroleukemic K562 cell line. The membrane-associated form of the p37 translation product has been analyzed in detail here. When detergent lysates prepared from biosynthetically labeled K562 cells were reacted with an antiserum containing anti-p37T antibodies, one of the proteins immunoprecipitated had a nominal mol wt of 36,000 to 37,000 (p37M). Several results suggest that this protein is homologous to the p37 translation product: (1) the protein, like the mRNA coding for the p37 translation product, was expressed in cell lines with diverse differentiated phenotypes; (2) the antigenic determinant(s) on p37M and p37T are oriented to the inner surface of the erythrocyte membrane while being oriented to the outer surface of erythroleukemic cells; and (3) one-dimensional peptide maps show homology between p37M and p37T. P37M does not appear to possess an N-terminal leader sequence that is proteolytically cleaved as the molecule is inserted into the membrane. In addition, p37M is not glycosylated.

Cell Line↗
PubMed1983

Reorientation of membrane polypeptides during erythrocyte maturation.

Messenger RNA extracted from the erythroleukemic cell line K562 was translated in vitro and the translation products reacted with an antiserum raised against human erythrocyte ghosts. Polypeptides immunoprecipitated by the antiserum were characterized by SDS-polyacrylamide gel electrophoresis and fluorography. The antiserum immunoprecipitated polypeptides with nominal molecular weights of 37,000 (p37), 20,000 (p20), 19,000 (p19), 18,000 (p18), 14,000 (p14), 13,000 (p13), and 11,000 (p11) daltons. Since the antiserum was raised against antigenic determinants present on both the inner and outer surface of the red cell membrane, differential absorption of antiserum with intact red cells, or ghosts, was used to localize the translation products to the inner or outer membrane surface. Absorption was also used to determine if any of the immunoprecipitated translation products represented membrane markers for the erythroid lineage. Absorption of the antiserum with red cell ghosts removed all antibodies reacting with in vitro translation products. Absorption with intact cells from various lineages removed anti-p20 antibodies and did not absorb anti-p19 or anti-p18 antibodies. Absorption with intact cells from all lineages except mature erythrocytes absorbed anti-p37, anti-p14, and anti-p13 antibodies, suggesting that these antigens are expressed on the outer membrane surface. Mature erythrocytes were incapable of absorbing these antibody populations, suggesting a lineage-specific reorientation of these antigens in the membrane during erythropoiesis.

Absorption↗
PubMed1982

Characterization of antigens on human lymphocytes coded by messenger RNA translated in vitro.

Translation and immunoprecipitation were used to identify messenger RNAs (mRNAs) coding for surface antigens expressed on human lymphoblastoid cells. The mRNAs were extracted from several human lymphoid cell lines as well as from fibroblastoid lines. These mRNAs were translated in vitro, and the translation products were reacted with xenoantisera raised against the antigens on human lymphoid cells. Products immunoprecipitated by these antisera were analysed by electrophoresis and fluorography. Four antisera immunoprecipitated a polypeptide with a mol. wt (MW) of approximately 32,000 (p32) from translations programmed with mRNA extracted from all the cell lines. Two antisera immunoprecipitated, in addition to p32, another polypeptide with a MW of approximately 25,000 (p25) only from translations programmed with RNA from lymphoid cell lines. p25 mRNA in the different lymphoid cell lines fell into three basic abundance classes as determined by in vitro translation and immunoprecipitation. Cells from two Burkitt's lymphomas (Raji and Daudi) did not express detectable p25 mRNA. Two T-lymphoblastoid lines (Molt-4 and 1301) contained five- to 10-fold less p25 mRNA than the B-lymphoid cell lines (Victor, RPMI-8866, RPMI-6410, RPMI-8226 and RPMI-1788). Both p32 and p25 were expressed on the cell surface inasmuch as lymphoblastoid cells adsorbed antibodies to both polypeptides. Human fibroblast, Raji or Daudi cells adsorbed anti-p32 antibodies from the antiserum but not anti-p25. Quantitative absorptions of the antiserum with T- or B-lymphoblastoid cells was used to determine the relative amounts of p32 and p25 expressed on the cell surface. B-lymphoblastoid cells were found to express two- to five-fold more p25 on the cell surface then T-lymphoblastoid cells. p25 does not represent an immunoglobulin light-chain precursor inasmuch as a 1000-fold excess of unlabeled human Ig did not compete with p25 translated in vitro for binding by its respective antibody.

Antibodies, Monoclonal↗
PubMed1982

Anti-RNP monoclonal antibodies derived from a mouse strain with lupus-like autoimmunity.

systemic lupus erythematosus (SLE) and related rheumatic and connective-tissue diseases are often associated with the production of antibodies directed against a variety of specific cellular components. Recent evidence indicates that two such autoantigens, the Sm and RNP antigens recognized by SLE sera, exist in small ribonucleoprotein complexes found in the nuclei of higher eukaryotes. Studies of the structure and function of these autoantigenic particles with human sera used as probes have been limited because of the multiplicity of autoantibodies often found in an individual serum. Through this communication, we report that MRL/Mp-+/+ (MRL/n) mice, which spontaneously develop a disease exhibiting many of the characteristics of human SLE, possess anti-RNP antibodies in addition to anti-Sm and anti-DNA as previously reported. Spleen cells from one such autoimmune mouse were used to produce a stable hybridoma secreting antibodies that react simultaneously with a protein of Mr 40,000 and a doublet of approximately 70,000, a pattern of reactivity identical to and characteristic of human SLE anti-RNP autoantibodies.

Animals↗
PubMed1981

Effectiveness of chest tube evacuation of pneumothorax in neonates.

This is a retrospective review of the effectiveness of 149 chest tubes placed in attempts to evacuate 91 pneumothoraces among 57 infants. Forty-four percent of initial evacuation attempts were ineffective; 42% of total chest tubes throughout the clinical courses were ineffective. The largest number of these ineffective chest tubes lay posterior in the pleural cavity. Fifty-six percent of posterior tubes were ineffective whereas only 4% of anterior tubes were ineffective. Other causes for failure included tubes which had perforated the lung, diaphragm, or mediastinum or were lying subcutaneously. On some occasions, chest tubes were mistakenly used to evacuate intrathoracic air which was actually a pulmonary pseudocyst or pneumomediastinum. Two thoracostomy sites were chosen: the superior and lateral. Eighty-five percent of chest tubes inserted through the superior approach lay anteriorly in the pleural cavity whereas only 47% of the laterally inserted tubes lay anteriorly. Superior thoracostomy tubes were significantly more effective than lateral tubes because of their more frequent anterior location. There were also fewer complications with superior thoracostomy tubes. Whereas only 10% of superiorly inserted tubes encroached upon the mediastinum, 32% of lateral tubes did so. To be effective, chest tubes should be placed anteriorly in the pleural space; this location is more often achieved via the superior thoracostomy approach.

Female↗
PubMed1981

Antepartum diagnosis and intrapartum management of lethal renal defects.

Bilateral renal agenesis (Potter syndrome) in the neonate is incompatible with life. Unfortunately, these infants are often delivered by cesarean section, as premature labor and breech presentation are commonly associated with the condition. In reviewing the obstetric course of 6 women who recently delivered such babies, the authors have found that antepartum diagnosis is possible in most cases. specifically, vaginal delivery should be strongly considered for patients in premature labor with intact membranes and breech presentation when there is ultrasound evidence of an abnormally shaped fetal head, absence of the fetal bladder, and severe oligohydramnios.

Breech Presentation↗
PubMed1980

Fetal hydantoin syndrome, neuroblastoma, and hemorrhagic disease in a neonate.

This is the first patient report of maternal ingestion of anticonvulsants associated with the triad of fetal hydantoin syndrome, neuroblastoma, and hemorrhagic disease. The neuroblastoma, a neural crest tumor, is the fourth of such origin reported after in utero exposure to phenytoin, suggesting that phenytoin is a transplacental carcinogen. Infants of epileptic mothers receiving anticonvulsants should be closely examined at birth for the fetal hydantoin syndrome and monitored for hemorrhagic problems. The neural crest tumor may be found at birth or later in childhood.

Abnormalities, Drug-Induced↗