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Biomedical subjects

P Barker

Publications and source records attributed to P Barker.

At least 91 records · Page 5Linked to original sources
PubMed1994

A critique: Watson's caring ideology. The proper focus of psychiatric nursing?

1. Watson's (1989) conceptualization of care possesses limited clinical utility in psychosocial contexts, given that there already exists an extensive lineage of human concepts of helping, within various psychotherapeutic traditions. 2. Watson's (1989) use of language delimits any utility that the "caring" construct might possess, Watson's conceptualization of caring is an inappropriate focus for psychiatric nursing, and historical precedents exist for many of the propositions upon which the science of caring is based. 3. Four decades of psychiatric nursing practice research and education render Watson's notion of a "science of caring" redundant.

Empathy↗
PubMed1994

Iodine-131 in breast milk following therapy for thyroid carcinoma.

UNLABELLED: This study evaluates breast milk secretion of 131I following therapeutic administration of 4000 MBq of 131I-iodide during lactation. METHODS: Breast milk 131I activity concentration was measured over a 32-day period. Dosimetry calculations were undertaken to estimate the period for discontinuation of breast feeding and the equivalent dose to the breasts. RESULTS: To achieve an infant effective dose < 1 mSv and an infant thyroid dose < 10 mSv, breast feeding would need to be discontinued for at least 52 days. The estimated equivalent dose to the breasts was 1.6 Gy. CONCLUSION: It is suggested that 131I-iodide administration is not undertaken during lactation and that breast feeding is discontinued several days prior to administration.

Adenocarcinoma, Follicular↗
PubMed1993

Molecular cloning and sequencing of coat protein-encoding cDNA of rice tungro spherical virus--a plant picornavirus.

Rice tungro spherical virus (RTSV) was shown to have three coat protein (CP) species by high resolution NaDodSO4-PAGE and Western blot analyses. The sequence of a coat protein-expressing cDNA clone that was identified and selected from a RTSV cDNA library showed that the insert was composed of 2823 bp with only one large open reading frame (ORF) coding for 941 amino acids. The positions of the three coat proteins were located in the putative polyprotein by N-terminal microsequencing and were shown to start at amino acids 287, 495, and 698 for CP-1, CP-2, and CP-3, respectively. The coat proteins are expressed as a polyprotein at the 5' region of the viral RNA genome, and all are cleaved at glutamine carboxy termini, presumably by picornavirus 3C-type of protease(s). Sequence comparisons of coat proteins revealed that there are high amino acid homologies between CP-2 of RTSV and VP3s of encephalomyocarditis virus (EMCV) and Theiler's murine encephalomyelitis virus (TMEV). These results indicate that RTSV is a plant picornavirus.

Amino Acid Sequence↗
PubMed1993

Purification and properties of the Clostridium thermocellum bglB gene product expressed in Escherichia coli.

The Clostridium thermocellum beta-glucosidase B was purified to homogeneity in its recombinant form from Escherichia coli. The purification protocol included ion exchange, hydrophobic interaction and hydroxyapatite chromatography. The polypeptide was found to have a molecular mass of 84,000 daltons and a pI of 4.4. There was a differential effect of temperature on the aryl-beta-glucosidase and cellobiase activities of the purified protein. The cellobiase activity had an optimum of 45 degrees C, and aryl-beta-glucosidase 60 degrees C. Both activities had an optimum pH of 5.6, although the aryl-beta-glucosidase had a secondary peak at 7.0. Both activities were stimulated by divalent cations and DTT, but inhibited by thiol reagents. The enzyme was found to have a broad substrate specificity. Using cellobiose as substrate and a temperature of 45 degrees C, the Km and Vmax values were 1.6 mM and 5.5 U mg-1 respectively. The aryl-beta-glucosidase when assayed against pNP glucopyranoside and a temperature of 60 degrees C had Km and Vmax of 2.9 mM and 1.1 U mg-1 respectively. The enzyme was very stable at 45 degrees C, but rapidly inactivated at 60 degrees C.

Carbohydrate Sequence↗
PubMed1993

Measurement of the sensitivity of upper airway reflexes.

We describe a method for measurement of the sensitivity of upper airway reflexes. The technique is based upon delivery of an irritant chemical stimulus (dilute concentrations of ammonia vapour) to the upper airway. The technique is non-invasive and uses equipment which is portable, allowing measurements to be made in the clinical environment.

Adult↗
PubMed1993

Effect of oral diazepam on the sensitivity of upper airway reflexes.

In a double-blind, cross-over study, we have investigated the effect of oral diazepam 20 mg and placebo on the sensitivity of upper airway reflexes in 10 male volunteers (aged 25-35 yr). Upper airway reflex sensitivity (UARS) was assessed using small concentrations of ammonia vapour as a stimulus to upper airway receptors. A threshold concentration of ammonia, at which reflex glottic closure occurred in response to the ammonia stimulus, was used as a measure of UARS. With diazepam, there was significant depression of UARS from 30 to 150 min after administration.

Adult↗
PubMed1992

Visualization of diagnostic heteroduplex DNAs from cystic fibrosis deletion heterozygotes provides an estimate of the kinking of DNA by bulged bases.

Previous studies (Hsieh, C.-H., and Griffith, J. D. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 4833-4837) of DNAs containing extra or bulged bases on one of the two strands of a duplex showed that they exhibit slower electrophoretic mobility than non-bulged DNAs, indicating that bulges create stiff kinks in the DNA. Here we paired a 97-base single-stranded DNA from the intact cystic fibrosis (CF) gene with a complementary 94-base strand containing a central 3-base deletion (delta F508), common to many CF patients. This produced a 94-base pair DNA with a central 3-base bulge. Visualization of these DNAs by electron microscopy showed that twice as many bulge-containing DNAs had a central kink as compared with the non-bulged controls. Examination of the distribution of kinking angles showed that the bulged population contained 5-7-fold more molecules with a central kink of 80 +/- 10 degrees than did the control molecules. When the 3-base bulge was replaced by a 3-base gap, the resulting duplex DNA showed central kinks with a somewhat lower frequency but greater range of kinking angles.

Base Sequence↗
PubMed1992

Movements of the vocal cords on induction of anaesthesia with thiopentone or propofol.

Using a fibreoptic laryngoscope, we have recorded on video tape the movements of the vocal cords after induction of anaesthesia with either propofol or thiopentone. The angle formed by the vocal cords decreased after induction of anaesthesia in both groups. This reduction in angle was significantly greater in the thiopentone group. The vocal cords closed completely in four patients in the thiopentone group and one patient in the propofol group. This difference may be explained by greater depression of laryngeal reflexes by propofol and this may account for the lower incidence of laryngospasm after induction of anaesthesia with propofol in comparison with thiopentone.

Adult↗
PubMed1992

Regurgitation of gastric contents during general anaesthesia using the laryngeal mask airway.

We have investigated the incidence of regurgitation of gastric contents during general anaesthesia administered via a laryngeal mask airway (LMA) or face mask and Guedel airway in 56 patients with no risk factors for regurgitation. Patients swallowed a gelatin capsule containing methylene blue 10 min before induction of anaesthesia. Fibreoptic laryngoscopy in the LMA group or conventional laryngoscopy in the face mask group was performed at the end of surgery. Dye was observed within the laryngeal mask in seven of 28 patients (25%). No patients in the face mask-Guedel airway group regurgitated dye (P = 0.005). There was no evidence of aspiration of dye.

Adult↗
PubMed1992

Effect of the laryngeal mask airway on lower oesophageal sphincter pressure in patients during general anaesthesia.

We have studied the tone of the lower oesophageal sphincter (LOS) in 40 adults undergoing routine body surface surgery and allocated randomly to receive anaesthesia either by face mask and Guedel airway or by laryngeal mask airway. In the laryngeal mask group there was a mean (SEM) decrease in barrier pressure (LOS minus gastric pressure) of 3.6 (1.4) cm H2O, compared with a mean increase of 2.2 (1.2) cm H2O in the face mask group (P < 0.005).

Adult↗
PubMed1992

A comparison of gastric emptying rate after cimetidine and ranitidine measured by applied potential tomography.

Gastric emptying was measured using applied potential tomography (APT) after crossover administration of 800 mg cimetidine and 300 mg ranitidine orally. Ten volunteers were studied, each on two occasions. Two hours after taking ranitidine or cimetidine, the volunteer was given a liquid and gastric emptying was measured over 60 min. There was a small but statistically significant delay in gastric emptying following ranitidine compared with cimetidine (P less than 0.04). The median (range) time to 50% emptying (t50) was 24 (15-60) min after ranitidine compared with 22 (15-46) min after cimetidine.

Administration, Oral↗
PubMed1992

Spatiotemporal increases in epidermal growth factor receptors following peripheral nerve injury.

Non-neuronal cells of peripheral nerve respond to axonal injury with a series of cellular changes that facilitate neuronal regeneration. To characterize the potential role of the epidermal growth factor (EGF) family of proteins in this response, we monitored the expression of EGF receptor mRNA and protein in the injured rat sciatic nerve. EGF receptor mRNA is synthesized in both primary cultured fibroblasts and Schwann cells, and Schwann cells express EGF receptor-like immunoreactivity. In situ hybridization and immunocytochemistry revealed that EGF receptor mRNA and protein are expressed in Schwann cells and fibroblasts of the sciatic nerve in vivo, and that receptor levels increase following nerve injury. Thirty-six hours postlesion, EGF receptors were expressed in gradients along the nerve both proximal and distal to the lesion, with the highest levels localized adjacent to the transection site. By 72 hr, receptor levels were maintained in a gradient in the proximal segment, but were uniformly increased throughout the portions of the distal segment that were analyzed. These changes were similar to those observed for low-affinity NGF receptor mRNA and protein, with transection causing increased expression in both Schwann cells and fibroblasts. Northern blots confirmed that primary cultured fibroblasts express low-affinity NGF receptor mRNA. To determine whether spatiotemporal gradients were a general characteristic of the nerve injury response, we monitored expression of the mRNA encoding the major myelin protein P0. Levels of P0 mRNA decreased initially in cells immediately adjacent to the transection site and, by 72 hr, were uniformly decreased throughout the distal segment. These data suggest that members of the EGF family of proteins may play a role in the peripheral nerve response to injury, and demonstrate a generalized gradient of cellular responses that commence at the transection site and progress distally in the nerve in the absence of intact axons.

Animals↗
PubMed1992

A study of the effect of Picolax on body weight, cardiovascular variables and haemoglobin concentration.

This study compared the effect of Picolax when administered for large bowel preparation in combination with preoperative fasting on body weight, haemoglobin concentration, haematocrit, and cardiovascular variables with matched subjects who were fasted before surgery. Picolax resulted in significantly greater weight loss, increases in haemoglobin concentration combined with cardiovascular changes suggesting hypovolaemia in the Picolax group. Intravenous fluid replacement is recommended in patients receiving Picolax.

Adult↗