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R Addison

Publications and source records attributed to R Addison.

At least 37 records · Page 2Linked to original sources
PubMed1986

Primary structure of the Neurospora plasma membrane H+-ATPase deduced from the gene sequence. Homology to Na+/K+-, Ca2+-, and K+-ATPase.

The gene for the Neurospora crassa plasma membrane H+-ATPase has been cloned and sequenced. The gene encodes for a protein of 920 amino acids with a molecular weight of 100,002. The coding region is interrupted by four introns: three near the amino terminus and one near the carboxyl terminus. The deduced amino acid sequence of the N. crassa plasma membrane H+-ATPase exhibits 75% homology to the amino acid sequence of the Saccharomyces cerevisiae plasma membrane H+-ATPase. Also, an amino acid comparison with the Na+/K+-ATPase from sheep kidney, Ca2+-ATPase from rabbit muscle, and K+-ATPase from Escherichia coli reveals that certain regions are highly conserved and suggest that these regions may serve essential functions which are common to the various cation-motive ATPases. This observation suggests that the phosphorylatable, cation-motive ATPases may function via a similar energy transduction mechanism.

Adenosine Triphosphatases↗
PubMed1986

Interactions of Neurospora crassa plasma membrane H+-ATPase with N-(ethoxycarbonyl)-2-ethoxy-1,2-dihydroquinoline.

The carboxyl group activating reagent N-(ethoxycarbonyl)-2-ethoxy-1,2-dihydroquinoline (EEDQ) interacts with the Neurospora plasma membrane H+-ATPase in at least three different ways. This reagent irreversibly inhibits ATP hydrolysis with kinetics that are pseudo-first-order at several concentrations of EEDQ, and an appropriate transform of these data suggests that 1 mol of EEDQ inactivates 1 mol of the H+-ATPase. Inhibition probably involves activation of an ATPase carboxyl group followed by a nucleophilic attack by a vicinal nucleophilic functional group in the ATPase polypeptide chain, resulting in an intramolecular cross-link. The enzyme is protected against EEDQ inhibition by MgATP in the presence of vanadate, a combination of ligands that has previously been shown to "lock" the H+-ATPase in a conformation that presumably resembles the transition states of the enzyme phosphorylation and dephosphorylation reactions, but is not protected by the substrate analogue MgADP, which is consistent with the notion that one or both of the residues involved in the EEDQ-dependent inhibitory intramolecular cross-linking reaction normally participate in the transfer of the gamma-phosphoryl group of ATP, or are near those that do. The ATPase is also labeled by the exogenous nucleophile [14C]glycine ethyl ester in an EEDQ-dependent reaction, and the labeling is diminished in the presence of MgATP plus vanadate. However, peptide maps of [14C]glycine ethyl ester labeled ATPase demonstrate that the labeling is not related to the EEDQ inhibition reaction in any simple way.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Membrane↗
PubMed1984

On the subunit composition of the Neurospora plasma membrane H+-ATPase.

The resolution-reconstitution approach has been employed in order to gain information as to the subunit composition of the Neurospora plasma membrane H+-ATPase. Proteoliposomes prepared from sonicated asolectin and a highly purified, radiolabeled preparation of the 105,000-dalton hydrolytic moiety of the H+-ATPase by a freeze-thaw procedure catalyze ATP hydrolysis-dependent proton translocation as indicated by the extensive 9-amino-6-chloro-2-methoxyacridine fluorescence quenching that occurs upon the addition of MgATP to the proteoliposomes, and the reversal of this quenching induced by the H+-ATPase inhibitor, vanadate, and the proton conductors, carbonyl cyanide m-chlorophenylhydrazone and nigericin plus K+. ATP hydrolysis is tightly coupled to proton translocation into the liposomes as indicated by the marked stimulation of ATP hydrolysis by carbonyl cyanide m-chlorophenylhydrazone and nigericin plus K+. The maximum stimulation of ATPase activity by proton conductors is about 3-fold, which indicates that at least two-thirds of the hydrolytically active ATPase molecules present in the reconstituted preparation are capable of translocating protons into the liposomes. Furthermore, as estimated by the extent of protection of the reconstituted 105,000-dalton hydrolytic moiety against tryptic degradation by vanadate in the presence of Mg2+ and ATP, the fraction of the total population of ATPase molecules that are hydrolytically active is at least 91%. Taken together, these data indicate that at least 61% of the ATPase molecules present in the reconstituted preparation are able to catalyze proton translocation. This information allows an estimation of the amount of any polypeptide in the preparation that must be present in order for that polypeptide to qualify as a subunit that is required for proton translocation in addition to the 105,000-dalton hydrolytic moiety, and an analysis of the radiolabeled ATPase preparation by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and urea rules out the involvement of any such polypeptides larger than 2,500 daltons. This indicates that the Neurospora plasma membrane H+-ATPase has no subunits even vaguely resembling any that have been found to be associated with other transport ATPases and that if this enzyme has any subunits at all other than the 105,000-dalton hydrolytic moiety, they must be very small.

Carbonyl Cyanide m-Chlorophenyl Hydrazone↗
PubMed1983

Isolation and characterization of plasma membranes from strains of Neurospora crassa with wild type morphology.

A variety of commercially available cell wall hydrolytic enzyme preparations were screened alone and in various combinations for their ability to degrade the cell wall of Neurospora crassa wild type strain 1A. A combination was found which causes complete conversion of the normally filamentous germinated conidia to spherical structures in about 1.5 h. Examination of these spheroplasts by scanning electron microscopy indicated that, although they are spherical, they retain a smooth coat that can only be removed upon prolonged incubation in the enzyme mixture (about 10 h). The 10-h incubation in the enzyme mixture appears to have no obvious detrimental effects on the integrity of the plasma membrane since the activity and regulatory properties of the glucose active transport system in 10-h spheroplasts are essentially unimpaired. Importantly, plasma membranes can be isolated from the 10-h spheroplasts by an adaptation of the concanavalin A method developed previously in this laboratory for cells of the cell wall-less sl strain, which is not the case for the 1.5-h spheroplasts. The yield of plasma membrane vesicles isolated by this procedure is 18-36% as indicated by surface labeling with diazotized [125I]iodosulfanilic acid, and the preparation is less than 1% contaminated with mitochondrial protein. The chemical composition of the wild type plasma membranes is similar to that previously reported for membranes of the sl strain of Neurospora. The isolated wild type plasma membrane vesicles also exhibit all of the functional properties that have previously been demonstrated for the sl plasma membrane vesicles. The wild type vesicles catalyze MgATP-dependent electrogenic proton translocation as indicated by the concentrative uptake of [14C]SCN- and [14C]imidazole under the appropriate conditions, which indicates that they contain the plasma membrane H+-ATPase previously shown to exist in the sl plasma membranes and that they possess permeability barrier function as well. The vesicles also contain a Ca2+/H+ antiporter as evidenced by their ability to catalyze protonophore-inhibited MgATP-dependent 45Ca2+ accumulation. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analyses of the isolated vesicles indicate that the protein composition of the wild type vesicles is roughly similar to that of the sl plasma membranes with the H+-ATPase present as a major band of Mr approximately 105,000. The wild type plasma membrane ATPase forms a phosphorylated intermediate similar to that of the sl ATPase, and the specific activity of the H+-ATPase in both wild type and sl membranes is approximately 3 mumol of Pi released/mg of protein/min.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphatases↗
PubMed1981

Solubilization and purification of the Neurospora plasma membrane H+-ATPase.

The electrogenic proton-translocating ATPase in the plasma membrane of Neurospora has been solubilized with lysolecithin and purified using a combination of gel filtration and density gradient centrifugation. Isolated plasma membrane vesicles are solubilized with lysolecithin in the presence of MgATP, vanadate, and chymostatin. The MgATP and vanadate are required to maintain the ATPase in an active form and the chymostatin prevents proteolytic degradation. Optimal solubilization of the H+-ATPase (approximately 70%) occurs at a lysolecithin/protein ratio of 3 (mg/mg). The lysolecithin extract is then passed through a Sepharose CL-6B column in the presence of lysolecithin, deoxycholate, MgATP, vanadate, dithiothreitol, and chymostatin. The bulk of the H+-ATPase activity elutes from this column as a relatively broad peak near the void volume. Sodium dodecyl sulfate-polyacrylamide gel analysis of the column fractions indicates that the H+-ATPase present in the first half of this peak is substantially separated from all other membrane proteins whereas the H+-ATPase in the second half of the peak is still significantly contaminated. Isopycnic glycerol density gradient centrifugation of the pooled fractions from each half of the column peak results in further purification of the H+-ATPase. Gradient fractions containing the H+-ATPase from the first half of the column peak are virtually free of any other membrane proteins and those from the second half of the column peak are only slightly contaminated. The overall yield of the H+-ATPase is at least 24% based upon enzyme activity, and the specific activity is approximately 10 mumol of Pi liberated/mg of protein/min.

Adenosine Triphosphatases↗
PubMed1981

Bilateral multifocal intraocular cysticercosis.

A 47-year-old male from India was treated for the rare condition of bilateral multifocal intraocular infestation with Cysticercus cellulosae, the larval form of Taenia solium. The intravitreous parasite in the left eye was removed via pars plana vitrectomy. A subretinal cysticercus in the right eye, which caused a rhegmatogenous retinal detachment, was removed via sclerotomy during the scleral buckling procedure. An additional peripapillary subretinal cyst could not be removed. A subconjunctival cysticercus was incidentally found and removed at the time of surgery. The patient returned to India six weeks after surgery and is doing well.

Conjunctival Diseases↗
PubMedDate not supplied

Trunk strengths in patients seeking hospitalization for chronic low-back disorders.

Trunk strengths of 16 male and 17 female patients with chronic low-back disorders were measured. The patients sought hospitalization for four weeks in a pain clinic. Maximum voluntary trunk strengths in the standing position were measured during attempted flexion, extension, and lateral bending. The trunk strengths of these patients were then compared with those of health subjects and with those of patients with low-back disorders who sought treatment as outpatients of a general orthopaedic office practice. In making the comparisons, intra-individual trunk-strength ratios were used to overcome problems due to the effects of patients' general weakness and any psychologic factors. When compared with healthy subjects, the patients seeking hospitalization had significantly smaller strengths during attempted extension relative to their strengths during attempted flexion or lateral bending. Their trunk-strength ratios did not differ significantly from those of the outpatient group.

Adult↗
PubMedDate not supplied

The changing role of the continence adviser.

The role of the continence adviser is evolving and developing within today's health service. Research evidence is available to define the role and its principal functions. Since the inception of the role in the early 1980s, there is still wide variation in interpretation, lack of uniformity and wide variance of service provision across the country. It is time to remove the title of continence adviser as it no longer portrays the role as it has developed. In addition, the taboo nature of the word, incontinence, has to be considered as a potential barrier to progress and development. An ENB course has now been established to ensure that continence advisers can take their rightful place alongside their colleagues in other specialist areas of nursing. As these develop, aspects of the continence adviser's role may be under threat. Continence advisers will therefore have to sell their services in the marketplace and move away from pad-oriented activities.

Counseling↗
PubMedDate not supplied

Nocturia, nocturnal polyuria and secondary nocturnal voiding.

Getting up once to the toilet at night is normal. Getting up more than once may be abnormal. Potential causes include: nocturia, which is bladder related; nocturnal polyuria, which is cardiac in origin; and being awake for a variety of reasons that are not linked to the bladder. Bladder problems, therefore, are not always the reason for frequency in micturition at night and treatment will only be effective if the correct cause and/or causes are identified. The most useful investigation to help with diagnosis is a frequency volume chart linked to an assessment identifying causes of secondary nocturnal voiding and nocturnal polyuria. Getting up to the toilet at night will not always be successfully treated by anticholinergics. Charting is the key to diagnosis, appropriate interventions and successful outcomes. This article will focus on working definitions, prevalence, causes, investigations and treatment options for nocturia, nocturnal polyuria and secondary nocturnal voiding.

Diagnosis, Differential↗
PubMedDate not supplied

Catheter valves: a special focus on the Bard Flip-Flo catheter.

This article examines catheter valves with a special focus on the Bard Flip-Flo. Catheter valves were first introduced into the UK in 1986. Ten years later, seven catheter valves were available of which three, including Flip-Flo, were available on prescription. Catheter valves are suitable for both males and females and both short- and long-term urethral or suprapubic catheters. Catheter valves can combine with urinary drainage bags to form link systems. The benefits of catheter valve usage, many of which are perceived but not well researched, include reduced urinary tract infection and maintenance of bladder tone and capacity. Current opinion indicates that patients with detrusor instability, impaired bladder sensation or confusion may find catheter valves unsuitable. Catheter care, including health education and monitoring, are required for catheter valve patients as well as conventional leg bag users. The Bard Flip-Flo catheter valve offers many benefits and is an established product within the UK.

Equipment Design↗
PubMedDate not supplied

Risk assessment in suprapubic catheterisation.

There are certain risk factors surrounding suprapubic bladder drainage and catheterisation. This article considers clinical indications and contraindications to suprapubic catheterisation. The advantages and disadvantages are discussed along with general care issues.

Contraindications↗