Biomedical subjects

J Walker

Publications and source records attributed to J Walker.

At least 253 records · Page 14Linked to original sources

PubMed1993

Prospects on clinical applications of electrical stimulation for nerve regeneration.

Regenerative capability is limited in higher vertebrates but present in organ systems such as skin, liver, bone, and to some extent, the nervous system. Peripheral nerves in particular have a relatively high potential for regeneration following injury. However, delay in regrowth or growth, blockage, or misdirection at the injury site, and growth to inappropriate end organs may compromise successful regeneration, leading to poor clinical results. Recent studies indicate that low-intensity electrical stimulation is equivalent to various growth factors, offering avenues to improve these outcomes. We present a review of studies using electric and electromagnetic fields that provide evidence for the enhancement of regeneration following nerve injury. Electric and electromagnetic fields (EMFs) have been used to heal fracture non-unions. This technology emerged as a consequence of basic studies [Yasuda, 1953; Fukada and Yasuda, 1957] demonstrating the piezoelectric properties of (dry) bone. The principle for using electrical stimulation for bone healing originated from the work of Bassett and Becker [1962], who described asymmetric voltage waveforms from mechanically deformed live bone. These changes were presumed to occur in bone during normal physical activity as a result of mechanical forces, and it was postulated that these forces were linked to modifications in bone structure. Endogenous currents present in normal tissue and those that occur after injury were proposed to modify bone structure [Bassett, 1989]. These investigators proposed that tissue integrity and function could be restored by applying electrical and/or mechanical energy to the area of injury. They successfully applied electrical currents to nonhealing fractures (using surgically implanted electrodes or pulsed currents using surface electrodes) to aid endogenous currents in the healing process.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Influence of dietary calcium on chlordecone-induced biochemical changes in serum of rat.

Male, Sprague-Dawley rats were treated with different (1, 10, 50, and 100 ppm) concentrations of chlordecone (Cd) in calcium-sufficient (Ca-S) or calcium-deficient (Ca-D) diet for 15 days. No significant changes in serum total proteins were observed. However, serum nonprotein nitrogen compounds (urea, uric acid, and creatinine) and glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, creatine kinase, and alkaline phosphatase were significantly increased at 50 and 100 ppm of Cd. Chlordecone induced more increase in these serum components of rats fed with Ca-D as compared to Ca-S diet. Increased serum nonprotein nitrogen compounds and enzymes indicate Cd-altered glomerular and hepatic functions.

Animals↗

PubMed1993

Lactoferrin co-purifies with myeloperoxidase and is recognised by anti-neutrophil cytoplasm antibodies.

Thirty-five sera with binding greater than 20% in a myeloperoxidase (MPO, Calbiochem) ELISA were tested in Western blot analyses. 5/35 blotted MPO, but 5/35 blotted lactoferrin (LF) contaminating the commercial MPO preparation. All the anti-LF positive sera, but none of the anti-MPO positive sera, also exhibited anti-nuclear binding on Hep2 cells. Three of the patients with anti-LF antibodies had vasculitis affecting areas additional to the pulmonary-renal involvement which characterised the patients with anti-MPO antibodies.

Antibodies, Antineutrophil Cytoplasmic↗

PubMed1993

Glucose-induced changes in renal haemodynamics in proteinuric type 1 (insulin-dependent) diabetic patients: inhibition by acetylsalicilic acid infusion.

The effect of hyperglycaemia on renal function in diabetic nephropathy remains poorly understood. We investigated the renal haemodynamic response to an acute plasma glucose rise from sustained euglycaemia to sustained hyperglycaemia in eight persistently proteinuric Type 1 (insulin-dependent) diabetic patients. Studies were performed in a double-blind cross-over manner after i.v. injection of 450 mg lysine acetylsalicilate (equivalent to 250 mg acetylsalicilic acid) or equal volume of 0.9% NaCl (isotonic saline). In the isotonic saline experiments hyperglycaemia produced a significant rise, by approximately 35%, in glomerular filtration rate in all patients from 41.5 +/- 5.2 to 55 +/- 6 ml.min-1.1.73 m-2 (p < 0.005) and an increase in sodium paraminohippurate clearance from 178 +/- 22.7 to 220 +/- 20.0 ml.min-1.1.73 m-2 (p < 0.05). These changes took place within the first 30 min of glucose infusion and were maintained for a 90 min hyperglycaemic period. Filtration fraction did not change significantly. Infusion of lysine acetylsalicilate lowered baseline glomerular filtration rate (isotonic saline vs lysine acetylsalicilate 41.5 +/- 5.2 vs 30.0 +/- 5.7 ml.min-1.1.73 m-2; p < 0.05) and significantly blunted the rise in glomerular filtration rate during hyperglycaemia (glomerular filtration rate increment: saline vs lysine acetylsalicilate: 13.6 +/- 2.8 vs 5.3 +/- 1.8 ml.min-1.1.73 m-2; p < 0.005). The effects on renal plasma flow were similarly blunted. In five additional patients, time- and volume-controlled isotonic saline experiments during sustained euglycaemia showed no significant changes in glomerular filtration rate and sodium paraminohippurate clearance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

A combined anterior and posterior approach to cataract surgery in patients with chronic uveitis.

Although several recent papers have focused on the results of cataract surgery in patients with uveitis, little has been published on specific surgical techniques that are most appropriate to such cases. We have found that a combined anterior and posterior approach using extracapsular techniques (usually phacoemulsification) and pars plana vitrectomy, with or without intraocular lens placement, is best suited for selected uveitis patients who have cataract, vitreous opacities, and cystoid macula edema. This paper discusses the surgical techniques that we have found to be best for the management of these cases.

Adult↗

PubMed1993

The effects of dietary calcium and chlordecone on cholinesterase, triglycerides, low density lipoproteins, and cholesterol in serum of rat.

Male, Sprague-Dawley rats were treated with 0, 1, 10, 50, 100 ppm chlordecone (Cd) mixed in calcium-sufficient (Ca-S) or calcium-deficient (Ca-D) diet for 15 days. A significant decrease in body weight gain was observed in 100 ppm of Cd-treated rats. Cholinesterase (ChE) activity was significantly decreased in serum of Ca-D rats. Chlordecone did not alter serum ChE activity in both Ca-S and Ca-D rats. However, Cd decreases serum triglycerides, low density lipoproteins (LDL) and cholesterol in both Ca-S and Ca-D rats. Rats fed with Ca-S or Ca-D diet exhibited differential sensitivity to Cd-toxicity. Decreased levels of serum triglycerides, LDL and cholesterol suggest that Cd might interfere in lipid metabolism.

Animals↗

PubMed1993

Improved performance 4 hours after cocaine.

Cocaine (2 mg/kg) was given orally to 13 healthy volunteers and physiologic, subjective, attentional and performance effects were measured over a period of 4 h. Posner's reaction time paradigm measured the effects of cocaine on performance and on attention to visual cues. Cocaine increased heart rate, systolic blood pressure and pupil diameter and reduced skin temperature. Physiologic effects, subjective rating of intoxication, and cocaine levels in saliva peaked at approximately 75 min and returned to precocaine levels within 3 h. In contrast, a reaction time measure of performance speed on the visual attention task showed improvement for 4 h after cocaine. A measure of covert attention in the cocaine condition failed to show the improvement which occurred in the placebo condition. Less fatigue was reported 4 h after cocaine than after placebo. Cocaine users may experience the drug's stimulant effects considerably longer than the euphoriant effects.

Adult↗

PubMed1993

Evidence for a G protein system in the tegumental brush border plasma membrane of Hymenolepis diminuta.

Guanine nucleotide-binding regulatory proteins (G proteins) mediate the transduction of signals from cell-surface receptors to intracellular effector enzymes. G protein alpha-subunits are routinely identified (and partially characterized) on the basis of their susceptibility to NAD(+)-dependent ADP-ribosylation NAD(+)-dependent ADP-ribosylation catalysed by cholera and/or pertussis toxins. Analysis of purified tegumental brush border plasma membrane from Hymenolepis diminuta by relevant methodologies has revealed the presence of a 42 kDa putative G protein alpha-subunit that is susceptible to ADP-ribosylation by both cholera and pertussis toxins. This polypeptide shows no definite resemblance to any of the four major mammalian G protein classes on the basis of M(r) and toxin-susceptibility. These results provide evidence for the existence of a tegumental G protein-linked signal transduction system in H. diminuta.

Animals↗

PubMed1993

Effects of chlordecone and malnutrition on immune response in rats.

Effect of Chlordecone (Cd) and malnutrition on total body and spleen weights, and plaque forming cells (PFC) were studied. Rats were fed on normal, calcium (Ca-D), protein (P-D) or Ca+P-deficient diets containing 0, 10 or 100 ppm of Cd for 2 or 4 weeks. High (95-100%) mortality was observed in malnourished rats treated with 100 ppm of Cd for 4 weeks. A slight decrease in body weight and an increase in spleen weight was observed in normal but not malnourished rats treated with 10 ppm of Cd for 4 weeks. PFC were significantly increased in both malnourished and Cd-treated rats. Similar increase in PFC was observed in rats fed on Ca-D but not P-D diet containing 10 or 100 ppm of Cd. Whereas, rats fed on Ca+P-D diet containing 100 ppm of Cd exhibited a significant decrease in PFC.

Animals↗

PubMed1993

Biochemical properties of cloned glutathione S-transferases from Schistosoma mansoni and Schistosoma japonicum.

cDNA clones encoding a 28-kDa subunit glutathione S-transferase (GST) from Schistosoma mansoni (Sm28GST) and a 26-kDa subunit GST from Schistosoma japonicum (Sj26GST) have been expressed in bacterial systems. The recombinant proteins were purified to homogeneity by batch-wash glutathione-agarose affinity chromatography and their biochemical properties investigated. Gel filtration chromatography indicated that both recombinant GSTs are homodimeric proteins. Resolution of Sm28GST and Sj26GST by chromatofocusing in the ranges pH 9-6 and pH 7-4 gave pI estimates of 7.4 and 5.0, respectively. Kinetic analyses suggested that both Sm28GST and Sj26GST operate via a sequential bisubstrate catalytic mechanism. Sm28GST and Sj26GST displayed a mosaic of mammalian Alpha-, Mu- and Pi-type substrate specificities and inhibitor sensitivities. However, multivariate analysis suggests that Sm28GST has an overall catalytic homology with mammalian Mu class GSTs, whilst the enzymatic properties of Sj26GST appear to constitute a hybridisation of Mu and Alpha class features. Both recombinant GSTs interact with a range of hydrophobic ligands including haematin and related compounds, bile acids and several anthelmintics. Sm28GST and Sj26GST possess relatively limited selenium-independent glutathione peroxidase activities, but are able to catalyse the glutathione conjugation of members of the trans,trans-alka-2,4-dienal, trans-alk-2-enal and 4-hydroxyalk-2-enal series of reactive carbonyls (known secondary products of lipid peroxidation).

Animals↗

PubMed1993

Nursing literacy.

Explore the source record for details and available documents.

Education, Nursing↗

PubMed1993

The role of the practice nurse in the management of depression in general practice: treatment adherence to antidepressant medication.

This pilot study demonstrated the feasibility of providing practice nurse support as an adjunct to standard general practitioner treatment to patients with depressive disorders prescribed antidepressant medication. With respect to the measures used and pilot study objectives identified, there were no statistically significant differences between the study groups in treatment adherence to the prescription of antidepressant medication or in the incidence and severity of adverse events to medication. Large-scale randomized controlled trials are in progress to assess the effectiveness of practice nurse interventions in the management of depressive illness in general practice.

Adult↗

PubMed1993

Eye movements in a familial vestibulocerebellar disorder.

Eye movement abnormalities consisting of poor or absent smooth pursuit and vestibulo-ocular reflex suppression, gaze-paretic and rebound nystagmus, slow build-up of optokinetic nystagmus, mildly hyperactive vestibulo-ocular reflex, and a high incidence of strabismus were inherited in an autosomal dominant fashion in 10 members of a non-consanguineous English caucasian family. The onset was in early childhood, but was not congenital. In 7 cases there was no tremor, dizziness, consistent ataxia, or other cerebellar signs that are often associated with these ocular motor deficits, and apart from strabismus, patients were asymptomatic. Magnetic resonance imaging of the propositus was normal. After childhood there appears to be no progression, with the oldest affected member being 40 years. Two members had been prone to falling in childhood, and one admitted to dizziness when tired. This condition, which is probably benign, has not been previously described and may represent a very mild variant of episodic ataxia or a new vestibulocerebellar syndrome.

Adolescent↗

PubMed1993

Degree of accuracy in perceiving graphic and representational information through touch.

Two studies are reported in which comprehension and interpretation of raised-line images and graphs by touch were investigated. Experiment 1 required blind-folded sighted subjects and blind subjects to rate the veracity of raised-line drawings in conveying the nature of an image when the complexity of the depicted object was manipulated (from simple outlines to more complex exaggeration of salient features). Results showed no effect of complexity on veracity ratings. Experiment 2 involved the assessment of blind and visually impaired subjects of line-graphs, histograms and pie charts which varied in information content and perceptible detail (textured and untextured). Histograms were easier to interpret than line-graphs, but there were no differences between histograms and pie charts. An increase in information content had little effect on comprehension.

Adolescent↗

PubMed1993

Analgesic rebound headache: experience in a community hospital.

In the past, chronic daily headaches have been attributed to many possible causes, including "tension," excessive contraction of pericranial muscles, and depression. A careful history reveals that many patients start out with fairly typical intermittent migraine attacks that evolve over the years into a pattern of daily or almost daily head pain. Overuse of analgesics is usually a part of this clinical picture, which has been termed "analgesic rebound headache." Fifty-three of the first 100 patients admitted to a community hospital's inpatient headache treatment program had chronic daily headaches and were overusing analgesics or other headache relief medications. We report our retrospective review of these patients and describe treatment of this difficult and sometimes unrecognized syndrome, primarily with intravenous dihydroergotamine (DHE). Results at hospital discharge and at follow-up several months later showed significant reduction of pain.

Adult↗

PubMed1993

The effects of olive oil, hydrogenated palm oil, and omega-3 fatty acid-enriched diets on megakaryocytes and platelets.

Unsaturated fatty acids are thought to prevent thrombotic and arteriosclerotic disease, whereas saturated fatty acids are thought to increase the incidence of these disorders. However, the effects of these diets on megakaryocytes and platelets are not well understood. We compared the effects of diets enriched with 8.4% olive oil, 8.4% hydrogenated palm oil, or 10.2% omega-3 fatty acid ethyl esters on guinea pig megakaryocytes and platelets. In plasma, changes in fatty acid composition reflected the composition of each diet. However, in platelets and megakaryocytes, hydrogenated palm oil induced a decrease in 16:0 and an increase in 18:2 while the olive oil diet caused a marked increase in 18:1 and a decrease in most other fatty acids. The differences in the effects of the diets on cellular versus plasma fatty acids suggest that megakaryocytes and platelets have an extensive capacity to regulate their fatty acid composition. Thrombocytosis occurred with the omega-3 fatty acid-enriched diet: 12.9 +/- 1.78 x 10(5) compared with 7.45 +/- 1.08 x 10(5) platelets per microliter of platelet-rich plasma in control animals. There was an increase in megakaryocyte size, ploidy, and morphological stage (cytoplasmic maturation) with the omega-3 fatty acid-enriched diet but not with the other diets. The omega-3 fatty acid-enriched diet decreased platelet thromboxane production while the other diets had no effect. Platelet hypersensitivity was suggested in collagen aggregation studies with olive oil but not with the hydrogenated palm oil diet. Although saturated fatty acid diets are thought to be atherogenic, this diet had no affect on platelet function.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Predicting length of stay, functional outcome, and aftercare in the rehabilitation of stroke patients. The dominant role of higher-order cognition.

BACKGROUND AND PURPOSE: Research in recent years has revealed factors that are important predictors of physical and functional rehabilitation: demographic variables, visual and perceptual impairments, and psychological and cognitive factors. However, there is a remaining uncertainty about prediction of outcome and a need to clinically apply research findings. This study was designed to identify the relative importance of medical, functional, demographic, and cognitive factors in predicting length of stay in rehabilitation, functional outcome, and recommendations for postdischarge continuation of services. METHODS: The influence of these factors was determined by comparing diagnostic, medical, demographic, functional, and neuropsychological information that was retrospectively obtained by reviewing the records of 86 patients admitted for comprehensive rehabilitation due to stroke (n = 36) or orthopedic injury (n = 50). Multiple linear regression with statistical adjustment to control for overprediction of variance was used to predict outcomes. RESULTS: The study revealed the primary importance of higher-order cognitive impairments (comprehension, judgment, short-term verbal memory, and abstract thinking) in extending length of stay and increasing referrals for outpatient therapies and home services after discharge for the cerebrovascular accident patients in comparison with orthopedic cohorts. CONCLUSIONS: The need is discussed for early, comprehensive assessment of deficits in cognition that affect a stroke survivor's ability to participate in a rehabilitation program and remediation that facilitates functional improvement by building on residuals of impaired abilities or teaching compensatory behaviors.

Aged↗

PubMed1993

Uterine activity in spontaneous labour and maternal peripheral plasma prostaglandin E2 and F2 alpha metabolites.

The relationship between maternal peripheral plasma concentrations of prostaglandin E2 and prostaglandin F2 alpha metabolites (bicyclo-PGEM and PGFM respectively) and the level of uterine activity in spontaneous labour was studied in 10 nulliparous and 10 multiparous women. Plasma prostaglandin metabolites were measured by radioimmunoassay. Uterine activity was quantified by computer analysis of changes in intrauterine pressure and expressed as mean active pressure (MAP). As labour progressed, both parity groups showed a significant rise in MAP which was associated with a significant increase in the levels of PGFM. However, the percentage rise in PGFM did not significantly correlate with the percentage rise in MAP. At all stages in labour PGFM and MAP levels were higher in the nulliparous group compared with the multiparous group. Bicyclo-PGEM levels showed no significant change in the nulliparous group but rose in late first stage/second stage in the multiparous group. Our observations support a role for prostaglandin F2 alpha in the generation of uterine activity in spontaneous labour. However, further study is required to elucidate the mechanisms controlling prostaglandin production by the fetal membranes and decidua in vivo, and how this relates to maternal peripheral plasma prostaglandin metabolite concentrations and the level of uterine activity.

Dinoprost↗