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K Shaw

Publications and source records attributed to K Shaw.

At least 91 records · Page 5Linked to original sources
PubMed1990

A comparison of the sequences of segment A of four infectious bursal disease virus strains and identification of a variable region in VP2.

The nucleotide sequences of the large open reading frame (ORF) from segment A of three European strains of infectious bursal disease virus (IBDV) have been determined using cDNA clones. This ORF of 3036 nucleotides encodes the virion proteins as a polyprotein in the following order: VP2, VP4, VP3. The nucleotide sequences determined have been compared to each other and to the published sequence of an Australian strain. The four strains are closely related, the greatest difference between two strains being 7.7% at the nucleotide level and 2.7% at the amino acid level. Comparisons show that there is a tight cluster of amino acid changes in the virion protein VP2. This variable region corresponded to the region where binding of a neutralizing monoclonal antibody has previously been mapped. A region in the centre of the segment, corresponding to the N terminal of VP4, was found to be completely conserved. Amino acid changes were spread fairly evenly through VP3 and there was no indication of a variable region as found in VP2.

Amino Acid Sequence↗
PubMed1990

Failure to demonstrate a major role for Kupffer cells and radiosensitive leukocytes in immunoglobulin-mediated elimination of Trypanosoma musculi.

Previous studies have indicated that elimination of parasitemia in Trypanosoma musculi infection is brought about by immunoglobulin G2a antibodies, C3, and an effector cell. Experiments were designed to identify the putative effector cell by using several approaches. Infected C5-deficient or C5-sufficient mice treated with silica particles or given 900 rads of radiation 3 days earlier effectively eliminated trypanosomes following administration of immune plasma (IP). Silica-treated, noninfected mice given T. musculi preincubated with IP also cleared the parasites. Radiolabeling studies revealed that uptake of the cleared trypanosomes by the liver in normal mice was relatively low (24%) and fell only slightly (19%) in silica-treated mice. In contrast, uptake of radiolabeled sheep erythrocytes by the liver was normally much higher (47%) and fell drastically (7%) in silica-treated mice. Mice were then immunocompromised by 900 rads of radiation, silica particles, and anti-platelet serum combined before IP-sensitized trypanosomes were given. Leukocyte and platelet counts were both reduced by 95% and sheep erythrocyte uptake by the liver fell from 77 to 5%; however, greater than 99% of the injected trypanosomes were cleared in these mice and uptake of radiolabeled trypanosomes by the liver was similar to that of normal mice. Lastly, in anesthetized mice in which Kupffer cells were excluded surgically from the circulation, greater than 99% of the IP-sensitized trypanosomes disappeared rapidly from the blood. Only 7% of the radiolabel was found in the liver versus 60% in sham-operated mice. The results are interpreted as showing that hepatic Kupffer cells play a minor role in the immune elimination of T. musculi. Likewise, radiosensitive leukocytes and platelets are unlikely to be sole candidates for the putative effector cell that mediates a cure of murine trypanosomiasis.

Animals↗
PubMed1989

Differential effects of nef on HIV replication: implications for viral pathogenesis in the host.

Stable lymphoid cell lines expressing the human immunodeficiency virus type 1 (HIV-1) nef gene product, p27, were established. The presence of p27 in the lymphoid cells suppressed replication of some strains of both HIV-1 and HIV-2. This observation indicates that nef could be important in the establishment of HIV latency. In contrast, fast replicating and highly cytopathic HIV-1 isolates recovered from patients with advanced disease states were not affected by the negative effect of nef present in these lymphoid cell lines. This lack of response to nef appears to constitute another viral feature that correlates with disease progression. Thus, manipulating expression of the nef gene in vivo might influence pathogenesis in the host.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Biochemical studies on the release of catecholamines from the rat carotid body in vitro.

The effects of hypoxia and carbachol on the release of newly synthesized catecholamines from superfused rat carotid bodies have been examined. Hypoxic superfusion medium was found to evoke catecholamine release which was dependent on the extracellular calcium concentration and was reduced by nitrendipine and atropine. Superfusion with the muscarinic agonist, carbachol, stimulated catecholamine release independently of the oxygen tension of the medium. The effect of carbachol on catecholamine release was abolished by atropine, suggesting that it was mediated by activation of cholinergic receptors of the muscarinic type. Both hypoxia and carbachol stimulated the release of 45Ca from carotid bodies prelabelled with 45Ca. The release of 45Ca with either stimulus was reduced by atropine and nitrendipine. These results suggest that although extracellular calcium plays an important role in the exocytotic secretory process of the carotid body, the mobilization of intracellular calcium pools may also contribute to the secretory response.

Animals↗
PubMed1988

Reliability of intrapartum fetal heart rate monitoring in the postterm fetus with meconium passage.

Fifty-six postterm fetuses with intrapartum meconium passage underwent routine scalp stimulation and scalp blood sampling. Fetal heart rate (FHR) patterns were compared with blood pH. Nine fetuses (16%) had a scalp pH less than 7.20. Twenty-nine fetuses (54%) demonstrated spontaneous or induced FHR accelerations; none were acidemic. Acidemia with normal variability was found only in conjunction with severe variable decelerations, and may represent respiratory acidosis. In this group, two of nine acidemic fetuses demonstrated no decelerations (pH 7.04) or mild variable decelerations only (pH 7.19). The absence of late decelerations was not as reliable as the presence of accelerations in the prediction of fetal well-being. Thirty-three percent of the fetuses who failed to exhibit spontaneous or provoked FHR accelerations were acidemic. These findings suggest that in this high-risk group of fetuses, the absence of spontaneous FHR accelerations should be followed by an attempt to induce accelerations, scalp pH assessment, or cesarean section.

Acidosis↗
PubMed1988

Scanning probe microscopy of biological samples and other surfaces.

Scanning probe microscopes derived from the scanning tunnelling microscope (STM) offer new ways to examine surfaces of biological samples and technologically important materials. The surfaces of conductive and semiconductive samples can readily be imaged with the STM. Unfortunately, most surfaces are not conductive. Three alternative approaches were used in our laboratory to image such surfaces. 1. Crystals of an amino acid were imaged with the atomic force microscope (AFM) to molecular resolution with a force of order 10(-8) N. However, it appears that for most biological systems to be imaged, the atomic force microscope should be able to operate at forces at least one and perhaps several orders of magnitude smaller. The substitution of optical detection of the cantilever bending for the measurement by electron tunnelling improved the reliability of the instrument considerably. 2. Conductive replicas of non-conductive surfaces enabled the imaging of biological surfaces with an STM with a lateral resolution comparable to that of the transmission electron microscope. Unlike the transmission electron microscope, the STM also measures the heights of the features. 3. The scanning ion conductance microscope scans a micropipette with an opening diameter of 0.04-0.1 micron at constant ionic conductance over a surface covered with a conducting solution (e.g., the surface of plant leaves in saline solution).

Crystallization↗
PubMed1987

Retinol binding protein as a small molecular weight marker of renal tubular function in diabetes mellitus.

A radioimmunoassay has been developed for the measurement in urine of retinol-binding protein (alpha 2-microglobulin) and used as an index of renal tubular function in adult Type 1 (insulin-dependent) diabetics and to define reference ranges in non-diabetic controls. There was a significantly greater excretion (P less than 0.001) of retinol-binding protein in the diabetic group compared to the controls in both overnight and daytime samples. There was a weak positive correlation with albumin excretion (r = 0.33; P less than 0.01) but no correlation with HbA1, duration of diabetes or arterial blood pressure. The results indicate that retinol-binding protein excretion may be increased in diabetic subjects without increased albumin excretion. The possibility therefore exists that renal tubular damage may occur early in diabetic nephropathy without apparent glomerular dysfunction.

Adolescent↗
PubMed1985

The symptoms of patients treated for Parkinson's disease.

One hundred and eighty-one patients with treated Parkinson's disease completed a self-administered questionnaire on symptoms, and their responses were compared with those of 263 control subjects randomly selected from a general practice population. Nine symptoms were reported by the patients with more than a fivefold excess when compared with the controls. These included jerking of the limbs, shaking of the hands, excessive salivation, poor mental concentration, grimacing, being frozen or rooted to the spot, and hallucinations. Compared with the general control population, the patients did not have an excess of stomach or limb pain, indigestion, headache, or any decrease of interest in sex. This observational survey, unlike a randomised controlled trial, could not ensure that the different treatment groups were comparable in important respects. However, certain associations were apparent; for example, patients receiving both a decarboxylase inhibitor and levodopa tended to report fewer attacks of being frozen to the spot, fewer problems with salivation, and a reduced frequency of defaecation. Patients receiving anticholinergic drugs reported an excess of dry mouth, faintness, and dyskinesia, and fewer hot flushes.

Adult↗
PubMed1984

Prospective comparison of silver sulfadiazine 1 per cent plus chlorhexidine digluconate 0.2 per cent (Silvazine) and silver sulfadiazine 1 per cent (Flamazine) as prophylaxis against burn wound infection.

Patients with fresh full-thickness burn wounds were randomly assigned to receive wound treatment with daily applications of either 1 per cent silver sulfadiazine plus 0.2 per cent chlorhexidine digluconate cream (Silvazine) or 1 per cent silver sulfadiazine (Flamazine). Fifty-four patients treated with Silvazine were comparable to 67 treated with Flamazine with respect to extent and distribution of burn, age and all aspects of wound and associated treatment. Overall incidence of wound bacterial colonization was less in the Silvazine treated patients (65 per cent versus 88 per cent; P = 0.002). With Silvazine, wound colonization by Staphylococcus aureus was less (41 per cent versus 64 per cent; P = 0.01). Clinical wound infection with Staph, aureus developed in one Silvazine treated patient and five Flamazine treated patients (P = 0.16). Colonization by and infection due to all other organisms did not differ in the two groups. The incidence of graft failure was similar with both agents. In future increasing the concentration of chlorhexidine digluconate above 0.2 per cent might produce an improved prophylactic effect against Gram negative bacteria reported by other authors using the combined agent in in vitro and clinical trials. Silvazine was effective in reducing the incidence of Staph. aureus burn wound colonization without fostering supervening opportunistic infection.

Adolescent↗
PubMed1984

Respiratory symptoms in Tasmanian adolescents: a follow up of the 1961 birth cohort.

The 1961 birth cohort of Tasmanians (n = 8410) was initially surveyed in 1968 and was followed up in 1974 for the history and presence of respiratory symptoms and signs. The study was designed to describe and compare the natural histories of wheeze and productive cough. In 1981 a 10% stratified random sample of the original cohort was again followed up and this sample's responses were compared across the three surveys. Wheezing was found to be more persistent than productive cough. Wheezers were twice as likely as coughers to persist with their symptoms to the age of 20. These persistent wheezers represented 3.6% of the cohort available for follow-up in 1974 (n = 7132). Wheezing was also invariably associated with decreased spirometric performance, particularly FEV at 0.5 s and FEF 25-75. The new wheezers first detected in 1974 had had significantly decreased spirometry measurements in 1968 compared to those of their coughing or symptom-free peers. An early history of cough was associated with triple the incidence of wheeze in previously asymptomatic children. Hayfever and eczema were associated with persistence of wheeze. A child with either of these diagnoses was four times as likely to persist in wheezing to the age of twenty than a wheezer without atopic complaint. No significant associations could be demonstrated between wheezing and smoking.

Adolescent↗
PubMed1984

Bi-atrial myxomas presenting as recurrent pulmonary emboli in a girl.

A 14-year-old girl whose sole presenting features were symptoms of pulmonary embolism, was found to have bi-atrial myxomas. The diagnosis was made preoperatively, and the patient had a successful outcome following elective surgery. The absence of other features such as systemic embolism, atrioventricular valvular obstruction, fever and constitutional symptoms makes this a most unusual case. Right atrial myxoma should be considered in any patient presenting with pulmonary embolism for which there is no obvious source.

Adolescent↗
PubMed1983

Alterations in the transport and processing of Rous sarcoma virus envelope glycoproteins mutated in the signal and anchor regions.

The env gene of Rous sarcoma virus codes for two glycoproteins which are located on the surface of infectious virions. Subcloning of these coding sequences in the place of the late region of SV40 DNA has allowed the expression of a normally glycosylated, functionally active glycoprotein complex on the surface of monkey cells. Through the use of site-directed mutagenesis, the role of specific amino acids in the signal peptide, signal peptidase cleavage site, and membrane anchor region have been investigated. Amino-terminal mutations have shown that deletion of the signal peptidase cleavage site along with one or two amino acids of the hydrophobic signal peptide results in the synthesis of an unglycosylated, uncleaved, and presumably cytoplasmically located precursor. Nevertheless, changing the signal peptidase cleavage site from ala/asp to ala/asn does not block the translocation of the glycoprotein across the membrane or the action of the peptidase. At the other end of the molecule, carboxy-terminal mutations have shown that the deletion of the hydrophobic membrane anchor region is not sufficient for the secretion of the truncated glycoprotein. Interpretations of these results based on recent models for protein transport and secretion are discussed.

Amino Acid Sequence↗
PubMed1983

The effect of topical epinephrine hydrochloride in saline on blood loss following tangential excision of burn wounds.

Burn wounds that were excised tangentially in the first 21 days after the burn were dressed immediately following excision with either saline or epinephrine hydrochloride-saline compresses (30 mg in 1030 ml normal saline) that were then left for 30 minutes while skin was harvested and banked. Thereafter, saline compresses were applied to all patients' wounds and changed every 4 hours. Banked skin grafts were applied without the need of a second general anesthetic on the first postoperative day. In both groups of patients, blood loss exceeded 9 percent of the calculated blood volume for each 1 percent of the body surface excised (this included blood loss due to harvest of skin graft necessary to cover the excised wounds) when the excision was performed in the first 14 days after the burn. Addition of epinephrine did not reduce net blood loss. Premature ventricular contractions were not observed, although 2 of 29 patients had an elevation in pulse rate of 25 beats per minute or more. No factors were identified that would reduce the blood loss following early tangential burn excision. Before embarking on tangential excision in the early postburn period, one must be prepared to replace 10 percent of the circulating blood volume for each 1 percent of the body surface to be excised.

Administration, Topical↗