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Biomedical subjects

M Perkins

Publications and source records attributed to M Perkins.

67 records · Page 4Linked to original sources
PubMed1981

Characterization and localization of human renal kininogen.

Kininogen was isolated from human urine by batch adsorption with immobilized antibody to the immunologically identical heavy (H) chains of both high molecular weight (HMW) and low molecular weight (LMW) human plasma kininogens. All releasable kinin in the guanidinium chloride eluate was associated with kininogen antigen in gel filtration fractions. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the eluate gave major stained and antigenic bands corresponding to the major form of plasma LMW kininogen. Also, the staining patterns and antigenic profiles obtained upon alkaline disc gel electrophoresis of the urinary and plasma LMW kininogens were strikingly similar. When antibody to H chain was used in an indirect immunofluorescence technique, cytoplasmic staining was observed in cells of distal tubules and c cortical and medullary collecting ducts of human kidneys. No fluorescence was observed using antibody to the unique light (L) chain of plasma HMW kininogen and no intact HMW kininogen was found in urine by radioimmunoassay. We conclude that the kidney is a source of urinary kininogen, while the L chain antigen in urine probably represents filtered degradation products of plasma HMW kininogen.

Humans↗
PubMed1981

Inhibitory effects of erythrocyte membrane proteins on the in vitro invasion of the human malarial parasite (Plasmodium falciparum) into its host cell.

The intracellular development of the erythrocytic stage of the malarial parasite (merozoite) is initiated by the attachment of the parasite to the erythrocyte surface. This paper describes an assay system to investigate Plasmodium falciparum merozoite entry into the host cell and reports on three observations regarding this interaction. (a) Merozoites do not invade human erythrocytes treated with either trypsin or neuraminidase, and both enzymes partially cleave glycophorin A, the major erythrocyte surface sialoglycoprotein. (b) A membrane protein fraction containing glycophorin A will, at low concentrations, inhibit the invasion of isolated merozoites into erythrocytes; no other fractions of membrane proteins have appreciable effects on the reinvasion. (c) Merozoites do not reinvade erythrocytes preincubated with F ab' fragments of antibody prepared against glycophorin A. Together, these three observations imply a role for glycophorin A in the attachment of the malarial parasite to the erythrocyte surface.

Animals↗
PubMed1976

A microplate enzyme-immunoassay for toxoplasma antibody.

A new test for the detection and measurement of toxoplasma antibody is described. Test sera are reacted with antigen-sensitized wells in micro-haemagglutination plates. Any attached antibody is shown by the addition of an enzyme-labelled antiglobulin followed by assay of the enzyme reaction with its substrate. The test is easy to carry out on a large scale, and there is a positive correlation between the results and dye test and haemagglutination test titres.

Alkaline Phosphatase↗
PubMed1973

Biogenesis of mitochondria. The effects of physiological and genetic manipulation of Saccharomyces cerevisiae on the mitochondrial transport systems for tricarboxylate-cycle anions.

1. Kinetic and equilibrium parameters for the uptake of l-malate, succinate, citrate and alpha-oxoglutarate by fully functional mitochondria of Saccharomyces cerevisiae were determined. 2. The uptake of l-malate and succinate is mediated by a common carrier, and two other distinct carriers mediate the uptake of citrate and alpha-oxoglutarate. 3. The properties of the carrier systems for l-malate, succinate and citrate closely resemble those of mammalian mitochondria, but the alpha-oxoglutarate carrier differs from the mammalian system in minor respects. 4. The composition of the yeast mitochondria was extensively manipulated by (a) anaerobiosis, (b) catabolite repression, (c) inhibition of mitochondrial protein synthesis and (d) elimination of mitochondrial DNA by mutation. 5. The carrier systems for l-malate, succinate, citrate and alpha-oxoglutarate are essentially similar in the five different types of mitochondria. 6. It is concluded that all the protein components of the carrier systems for l-malate, succinate, citrate and alpha-oxoglutarate are coded by nuclear genes and synthesized extramitochondrially by cell-sap ribosomes.

Anaerobiosis↗
PubMed1973

Biogenesis of mitochondria. A requirement for mitochondrial protein synthesis for the formation of a normal adenine nucleotide transporter in yeast mitochondria.

1. Parameters of ATP uptake by fully functional Saccharomyces cerevisiae mitochondria, including kinetic constants, binding constants and sensitivity to atractylate, closely resemble those of mammalian mitochondria. Scatchard plots of atractylate-sensitive adenine nucleotide binding indicate two distinct sites of high affinity (binding constant, K(D)'=1mum), and low affinity (binding constant, K(D)''=20mum) in the ratio 1:3. Uptake has high Arrhenius activation energies (+35 and +57kJ/mol), above and below a transition temperature of 11 degrees C. Atractylate-insensitive ATP uptake is apparently not saturable and has a low Arrhenius activation energy (6kJ/mol), suggesting a non-specific binding process. 2. Kinetic and binding constants for ATP uptake are not significantly changed in catabolite-repressed or anaerobic mitochondrial structures. 3. Inhibition of the mitochondrial protein-synthesizing system by growth of cells in the presence of erythromycin, or loss of mitochondrial DNA by mutation profoundly alters the adenine nucleotide transporter. ATP uptake becomes completely insensitive to atractylate, and the high-affinity binding site is lost. However, the adenine nucleotide transporter does not appear to be totally eliminated, as a moderate amount of saturable low-affinity ATP binding remains. 4. It is concluded that products of the mitochondrial protein-synthesizing system, probably coded by mitochondrial DNA, are required for the normal function of the adenine nucleotide transporter.

Adenine Nucleotides↗
PubMedDate not supplied

Hyperalgesia in rats following intracerebroventricular administration of endotoxin: effect of bradykinin B1 and B2 receptor antagonist treatment.

The present study investigated the development of thermal and mechanical hyperalgesia following intracerebroventricular (i.c.v.) injections of E. coli lipopolysaccharide (LPS). Hind paw withdrawal to von Frey filament stimulation and thermal withdrawal latencies were measured before and up to 24 or 48 h following an i.c.v. injection of LPS (dose range: 0.02--200 micrograms). Thermal and mechanical hyperalgesia were evident by 6 h after LPS injection. LPS-induced hyperalgesia was reversed by the B2 receptor antagonist, HOE 140 (10--30 pmol), when administered i.c.v. but not systemically (0.01--1 mmol/kg, i.v.). Central co-administration of the B1 receptor antagonists, des-Arg9-Leu8 Bk (0.1--1 nmol) or des-Arg10 HOE 140 (0.1--1 nmol) had no effect on thermal or mechanical hyperalgesia. LPS-induced hyperalgesia was also inhibited by indomethacin administered either i.c.v. (10 nmol) or i.v. (1 mumol/kg). These results indicate that administration of endotoxin to the CNS induces the development of hyperalgesia and that this response involves the activity of kinins, via the stimulation of centrally located B2 receptors, and the formation of prostanoids.

Analysis of Variance↗
PubMedDate not supplied

Lesions and inactivation implicate dorsolateral hindbrain in MFB self-stimulation.

Two experiments explored the role of the motor nucleus of the trigeminal nerve (Mo5) and surrounding area in the rewarding effects of medial forebrain bundle (MFB) stimulation. In the first, eight rats received serial bilateral lesions of the target region. The reward value of MFB stimulation was assessed at 200, 400, and 800 microA using the rate-frequency curve shift paradigm. In five rats, no lesions affecting the motor nucleus or its surrounding area affected the frequency required to maintain half-maximal response rate at any current. One rat with a relatively ventrally placed lesion showed substantial enhancement of stimulation reward value at two currents, while two rats with lesions affecting the area around the descending fibers of the superior cerebellar peduncle (scp) showed substantial increases in required frequency. In the second experiment, six rats received uni- and bilateral injections of lidocaine to temporarily inactivate the target area. Two rats with injections centered near the descending fibers of the scp showed substantial increases in required frequency, as great as 0.30 log(10) units. Two rats with injections slightly rostral to these showed little change in required frequency. Two rats with injections in the ventral cerebellum, just lateral to the fastigial nucleus, showed increases in required frequency, particularly following injections contralateral to the MFB stimulation site. These data are interpreted to imply a role for the area around the lateral pole of the scp, perhaps including axons arising from the cerebellum, in MFB stimulation reward.

Anesthetics, Local↗
PubMedDate not supplied

Quality care in an era of retrenchment.

UNLABELLED: SOURCE AND PURPOSE: Constraints in the healthcare delivery system are resulting in unprecedented challenges to quality nursing care. In response to concerns expressed by readers in a JSPN survey, we solicited input from prominent SPN members. CONCLUSIONS: Quality care can be sustained through nurses' creativity, flexibility, leadership, and collaboration. The context for quality care is an organizational environment with attention to critical analysis, careful resource utilization, and improved outcomes. PRACTICE IMPLICATIONS: Nurses can not only maintain premium standards of quality care but, by assuming leadership, help shape the future of health care.

Cooperative Behavior↗