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Biomedical subjects

M Barton

Publications and source records attributed to M Barton.

At least 19 recordsLinked to original sources
PubMed1992

Isolation of koala lymphoid cells and their in vitro responses to mitogens.

Baseline parameters have been established for the successful in vitro culture of mononuclear cells from the peripheral blood (PMC) of koalas. To minimise stress-related influences and allow repeated testing of cells from the same animals, most studies were performed using blood samples from captive koalas which had become accustomed to regular handling. Ficoll-Paque density gradient fractionation of whole blood was required to prepare cell suspensions which responded well to the T-lymphocyte mitogens phytohaemagglutinin, concanavalin A and pokeweed mitogen. In contrast, very low or negligible proliferative responses were induced by the B-lymphocyte mitogens lipopolysaccharide, jacalin and protein A, even when purified PMC were cultured with a wide range of concentrations of these molecules. Using the standard approaches established with T-lymphocytes of eutherian animals, it was shown that concanavalin A-stimulated PMC produced an interleukin 2-like growth factor. The significance of these findings is discussed in the context of current knowledge and understanding of similar studies carried out using the lymphoid cells of eutherian and other metatherian animals.

Animals↗
PubMed1992

Koala lymphoid cells: analysis of antigen-specific responses.

Bovine serum albumin (BSA) and ovine immunoglobulin (OvIgG) were used to induce humoral immune responses in two koalas which were also painted with 2-4-dinitrofluorobenzene (DNFB) and subsequently tested for local delayed-type hypersensitivity (DTH) reactions. The responses observed support the suggestion that the koala is 'immunologically lazy'. Antibody responses to BSA and OvIgG were not detected until 12 weeks after the initial antigen injection and antigen-specific in vitro proliferative responses by the mononuclear cells (PMC) of immunised animals could not be induced, although these cells did respond to concanavalin A and phytohaemagglutinin. Similarly, DTH responses to DNFB could be elicited in vivo, but took a relatively long time to develop and the PMC of the sensitised koalas were unresponsive to the sensitising antigen in vitro. The absence of proliferation when mixed suspensions of PMC from different koalas were cultured in vitro is consistent with these results.

Animals↗
PubMed1992

The effect of treatment duration in the local control of cervix cancer.

A significant effect of treatment duration on pelvic control was found in 830 patients with cervix cancer treated by radical radiation therapy. Using three methods of analysis, the loss of control consistently approximated 1% per day of treatment prolongation beyond 30 days, although analysis of stage subgroups showed that this effect was predominantly manifested in Stages III/IV compared with Stages I/II. In multivariate analyses using both a logistic regression and a Cox regression model, stage (p = 0.0001 for Stage I/IIA and 0.0036 for Stage IIB relative to Stage III/IV) treatment time (p = 0.0001), and age (p = 0.0067) were independently correlated with pelvic control. Exclusion from analysis of patients with delays due to tumour or treatment related complications, intercurrent illness or manifestations of poor tumour response did not significantly change the magnitude of the time effect nor the ranking of the significant covariates. These results are consistent with the occurrence of accelerated repopulation and warrant further investigation, preferably in a randomized trial of accelerated versus conventionally fractionated radiation therapy.

Actuarial Analysis↗
PubMed1992

Concurrent case note screening: failure to demonstrate benefit.

In 1991 the third of a series of trials of concurrent case note screening was conducted over a 4 month period in one surgical and one medical unit of a busy metropolitan public teaching hospital in South Australia. The conclusion reached was that there is insufficient evidence of consistent improvement to justify the continuation of this expensive method of quality assurance. Traditional monitoring of performance by consultants, perhaps with the aid of computer-assisted management information, should achieve similar results.

Concurrent Review↗
PubMed1991

Further experience with the lateral arm free flap.

Our experience with the lateral arm free flap over the last 7 years was reviewed in detail, placing emphasis on the clinical aspects and modifications of the flap. A total of 150 patients have undergone reconstructive procedures with the flap for small to medium-sized defects. This included 18 split flaps, 11 osteocutaneous flaps, 6 with vascularized triceps tendon, 5 neurosensory flaps, and 5 fascia-fat flaps. The donor-site scar was generally acceptable; only 3 patients required scar revision and 15 patients required debulking of the flaps. With use of the split flap for wide defects, tension-free primary closure of the donor site can be achieved. In most cases, a two-team approach may be adopted, thereby increasing the efficiency of this microvascular transfer.

Adolescent↗
PubMed1991

Computerising the OH department.

Many OH departments within the public and private sectors of industry are considering the need to install computer systems to record and manage their employee medical records. Michael Barton stresses that consideration has to be given to the reasons for computerisation, clarification of the its benefits and also the importance of dispelling any myths about computer systems before embarking on such a course of action.

Computer Communication Networks↗
PubMed1990

Effects of antibiotic therapy at drying off on mastitis in the dry period and early lactation.

Four strategies for selecting cows for intramammary therapy with benzathine cloxacillin at drying off were compared in 12 Victorian dairy herds. The bacteriological status of all quarters of all (1044) cows was determined just before drying off, within 2 d of calving, and again 3 to 5 months after calving. All cases of clinical mastitis (from calving to mid-lactation) were recorded. Cows not infected at drying off were allocated randomly to 2 subgroups of approximately 350 cows each: not infected, not treated (NI-NT), or not infected, all quarters treated (NI-AT). New infection rates in the dry period (3.8% for NI-NT vs 2.1% for NI-AT) and in early lactation (4.1% for NI-NT vs 3.9% for NI-AT) were low and these differences were not significant. Incidence of clinical mastitis in early lactation was almost 50% higher for the treated group of uninfected cows compared with the untreated group (0.05 less than p less than 0.1). Cows infected in one or more quarters at drying off were split randomly into 2 subgroups of approximately 170 cows each: infected, all quarters treated (I-AT), or infected quarters treated only (I-QT). The new infection rate during the dry period was nearly 4 times higher for I-QT (15.3%) due to significantly more new infections by Staphylococcus aureus and Streptococcus uberis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Traumatic aortocaval fistula: case report.

A gunshot wound to the right chest in a 21-year-old female resulted in an acute aortocaval fistula at the level of the diaphragm. An operative approach planned for maximal exposure, vascular control with intraluminal balloon catheters, and conservation of blood with an intraoperative autotransfusion system resulted in successful repair and long-term survival.

Adult↗
PubMed1986

Positive end-expiratory pressure increases plasma catecholamine levels in non-volume loaded dogs.

UNLABELLED: Positive end-expiratory pressure (PEEP) is commonly used in the treatment of critically ill patients whose sympathetic nervous system is stressed; however, PEEP's actions on sympathetic nervous system activity are unknown. We therefore measured the plasma noradrenaline response (an index of sympathetic nervous system activity) to graded doses of PEEP in nine mongrel dogs. After 30 minutes at each level of PEEP, plasma noradrenaline concentrations increased from baseline mean values of 300 (SD 108) pg/ml to 388 (SD 225) pg/ml (P less than 0.05) at 5 cm, 433 (SD 255) pg/ml (P less than 0.01) at 10 cm and 1194 (SD 882) pg/ml (P less than 0.01) at 20 cm water pressure of PEEP. The increases in plasma noradrenaline concentrations correlated inversely (r = -0.43, P less than 0.01) with PEEP-induced changes in cardiac output. Plasma adrenaline levels did not change significantly in response to 5 or 10 cm of PEEP; however, plasma adrenaline increased, while heart rate and mean arterial blood pressure fell, at 20 cm water pressure of PEEP (P less than 0.05). Within 15 minutes after discontinuation of PEEP, the plasma catecholamine concentrations returned to baseline levels. CONCLUSIONS: 1. PEEP significantly increases sympathetic nervous system activity in a rapid, dose-dependent, reversible manner; 2. the PEEP-induced increases in sympathetic activity may explain the reductions in organ blood flow which others have observed following the initiation of PEEP; 3. PEEP-related changes in sympathetic nervous system activity are a consequence of PEEP-induced reductions in cardiac output.

Animals↗
PubMed1978

alpha1-Antitrypsin: the presence of excess mannose in the Z variant isolated from liver.

The Z variant of alpha1-antitrypsin was isolated by a new technique from the liver of a patient homozygous for the Z allele of the protease inhibitor locus. The material was homogenous and antigenically competent but had no protease inhibiting capacity. An interesting correlation was found between the subcellular localization and the carbohydrate composition of the Z variant from liver. Carbohydate analysis of this glycoprotein showed an absence of galactose and sialic acid, an appreciable decrease in N-acetylglucosamine, and an almost twofold increase in mannose residues. These data indicate a considerable slowdown in the processing of the oligosaccharides of liver Z variant. In spite of the absence of sialyl residues, the liver Z varant was microheterogeneous by analytical isoelectric focusing. The isoproteins of liver Z variant coincided with those of asialo M variant in the focusing field.

Amino Acid Sequence↗
PubMed1977

The purification and properties of human alpha1-antitrypsin (alpha1-antiprotease), variant Z.

After three stages of preliminary purification, variant Z was chromatographed on a DEAE-cellulose column. Upon elution with a linearly increasing concentration of NaCl, variant Z was recovered in two separate peaks, the first of which contained 81% and the second 19% of the total. The preparation corresponding to the first peak was homogeneous by various criteria. The trypsin and chymotrypsin inhibiting capacities and the specific antigenic activity of the preparation were nearly the same as those of an authentic sample of variant M. Variant Z contained 8 or 9 more gycine residues than variant M, but no appreciable difference was found between their carbohydrate contents. By analytical isoelectrofocusing the isoinhibitors of purified variant Z overlapped with those in the plasma of the donor and were cathodal to, but partially overlapped with purified variant M. After desialysation, the overlap between the different variants became complete, but variant Z contained a larger proportion of cathodal and smaller proportion of anodal components than variant M. Both variants formed five distinct isoinhibitor-protease complexes after incubation with trypsin and chymotrypsin and the corresponding complexes in the different variants completely coincided.

Amino Acids↗