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Biomedical subjects

A R Jackson

Publications and source records attributed to A R Jackson.

At least 19 recordsLinked to original sources
PubMed1997

Pre-operative localization of breast microcalcification using high-frequency ultrasound.

AIM: To determine whether high-frequency ultrasound (US) can be used to reliably localize breast microcalcification preoperatively in the absence of any associated mass lesion or distortion. PATIENTS AND METHODS: Seventeen patients, found to have microcalcification at mammography, the majority screen detected, were studied using high-frequency (10 or 13 MHz) US to visualize the calcified particles. The approximate site of the microcalcifications was first determined from the mammograms. Once the calcifications had been localized, the skin overlying the site was marked with an indelible marker and the depth of the calcifications recorded for the surgeon. Successful excision of microcalcifications was confirmed with postbiopsy specimen X-ray. RESULTS: Fifteen of the 17 patients (88%) underwent successful removal of the microcalcifications. The mean microcalcification cluster size was 160 mm with a mean number of calcifications of 20 at a mean depth of 15 mm. The mean size of the individual calcifications was 0.29 mm. CONCLUSION: Our results show that high-frequency US is an effective non-invasive method of identifying and localizing breast microcalcification, and can be used as an alternative to hook wire stereotaxic localization in the majority of patients.

Adult↗
PubMed1996

Characterization of cadherins expressed by murine thymocytes.

Thymocytes develop in close apposition to the stromal cells of the thymus. The ontogeny of thymocytes is dependent on intimate interactions between these cells and the stromal cells. The molecular mechanisms involved in regulating thymocyte-stromal cell interactions remain to be clearly defined. In this study, we utilized a polymerase chain reaction strategy to identify members of the cadherin family of cell adhesion molecules that are expressed by CD4+ CD8+ thymocytes, the major cell type in the thymus. One classical cadherin (E-cadherin), three atypical cadherins (OB-cadherin) K-cadherin, and cadherin-8), and two novel cadherins (T1-cadherin and T2-cadherin) were found to be expressed by the CD4+ CD8+ thymocytes. The discovery that these cells display multiple cadherins opens a new area of investigation concerning the adhesive mechanisms involved in modulating thymocyte-stromal cell interactions. We speculate that cadherins will prove to play an essential role in the ontogeny of thymocytes.

Amino Acid Sequence↗
PubMed1992

Quality and interpretation of operative cholangiography in a district general hospital.

The quality and interpretation of operative cholangiography were assessed in 128 patients undergoing cholecystectomy. The quality of each cholangiogram was assessed by calculating a cholangiogram score according to the anatomical structure visualized. Out of a maximum possible score of 5, 26% of cholangiograms achieved a score of less than or equal to 3 and were considered as technical failures. The sensitivity, specificity and negative predictive values regarding the surgeon's interpretation of the cholangiograms were high and compared well with the radiologist's assessment. However, the positive predictive value for the surgeon's assessment of the cholangiograms was 74% compared with 95% for the radiologist (P less than 0.02). Improvement in cholangiography can only be achieved by greater attention to detail and perseverance. After an adequate examination, the only criteria for common bile duct exploration should be the presence of filling defect(s).

Adult↗
PubMed1991

A waiting time survey in general practice.

Keeping patients waiting unnecessarily can be a cause of stress for both patient and doctor. Waiting time is a tangible aspect of your practice that patients will use to judge you, even more than your knowledge and skill. Determine your own actual waiting time, and see if you 'measure up'.

Appointments and Schedules↗
PubMed1991

Small business, cash budgets and general practice.

In practice management, general practice falls into the category of small business with all its attendant generic problems. Disciplined planning and good financial management are not often seen in small business. These are required if general practitioners are to continue (or return to) the provision of high quality medical services. An effective budget process, especially cash-flow budgeting, is the key to successful planning and financial management. Budgeting will bring Control, Co-ordination, and Credibility to your practice. It will enable you to set goals and to achieve them.

Budgets↗
PubMed1989

Nutritional myopathy in goats.

A nutritional myopathy in unweaned fibre goats aged 2 to 4 mths is described in 3 flocks from the tablelands of New South Wales. Clinically affected animals were illthrifty and in circulatory failure prior to being found dead. At necropsy, there was pronounced ascites, pulmonary congestion and marked mottling of the liver. Chalky white streaks and patches were obvious in the myocardium, particularly in the right ventricular wall. Skeletal muscles varied from grossly normal to generally pale. Histologically, the myocardium exhibited areas of severe acute myonecrosis with mineralisation and adjoining areas of phagocytosis and fibrosis. In 2 of 3 flocks, some skeletal muscles showed a mild subacute myopathy. Marked hepatic congestion extended to periacinar haemorrhage and necrosis in some areas. Dietary imbalances of selenium, vitamin E and polyunsatured fatty acids were probable factors in the pathogenesis of the condition.

Animals↗
PubMed1989

How to assess the business performance of your practice.

The objective of this article is to provide motivation and practical guidance to those general practitioners who wish to assess the performance of their practice in the business and financial sense, but who believe that they lack the necessary training and resources.

Family Practice↗
PubMed1988

Toxicity of the cyanobacterium Nodularia spumigena Mertens.

The bloom forming cyanobacterium (blue-green alga) Nodularia spumigena produced a peptide hepatotoxin with an LD50 of 70 micrograms/kg i.p. in mice. The livers of lethally poisoned mice were haemorrhagic and enlarged, the weight doubling to about 10% of total body weight. Histologically there was centrilobular to midzonal disruption and lysis of hepatocytes resulting in haemorrhage and formation of blood lakes. Death occurred approximately 1 hr after i.p. injection. By 30 min significant increases had occurred in the plasma levels of lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase and glucose paralleling degeneration and necrosis of centrilobular hepatocytes. In vitro the toxin caused rapid dose-dependent deformation of freshly isolated rat hepatocytes, which was accompanied by the activation of phosphorylase a; 125 ng/ml of toxin being sufficient to cause these changes in 10(6) cells. This work demonstrates that, both in vivo and in vitro, Nodularia toxin shares many similarities in its action to the well characterized peptide toxins of another cyanobacterium, Microcystis aeruginosa.

Animals↗
PubMed1988

Toxicity to mice and sheep of a bloom of the cyanobacterium (blue-green alga) Anabaena circinalis.

A bloom of Anabaena circinalis shown to be lethal to mice (i.p. LD50 17.0 +/- 0.6 mg/kg) was tested for lethal potency when given orally to mice and intraruminally and intraperitoneally to sheep. The lethal oral dose in mice was at least 170 times the parenteral dose. The bloom was lethal when given i.p. to sheep but lethality was not observed when given intraruminally in doses up to 1710 mg/kg, equivalent to drinking 8.5 litres of thick algal bloom, a volume far in excess of that likely to be consumed naturally. In vivo testing of lethal potency by i.p. inoculation of mice is therefore an unreliable method for judging potential oral toxicity in livestock of blooms of Anabaena.

Acetylcholinesterase↗
PubMed1988

Oral toxicity of a bloom of the Cyanobacterium microcystis Aeruginosa administered to mice over periods up to 1 year.

Cyanobacterial blooms in lakes have been reported causing livestock deaths and liver injury to human populations. In this study bloom material consisting of Microcystis aeruginosa was collected from a farm water storage after the death of sheep drinking from it. The cyanobacterial cells were lysed and a cell-free extract was provided to mice at a series of dilutions as their only source of drinking water. Mice of both sexes, with controls, were killed at intervals up to 1 yr of administration. Autopsies, histopathological examination, and analyses of plasma lactate dehydrogenase and alanine aminotransferase were carried out. Increased mortality was observed, particularly among males, together with chronic active liver injury and elevated alanine aminotransferase in blood. In control mice and those receiving lower concentrations of extract, hepatic amyloidosis with neutrophil infiltration, and bronchopneumonia, were seen with increasing age. The bronchopneumonia appeared earlier among mice receiving cyanobacterial extract. Four tumors were seen in 71 mice receiving a high concentration of extract for up to 1 yr, none in 150 mice receiving lower concentrations, and 2 in 73 control mice. No effects on male or female fertility, embryonic mortality, neonatal viability, or skeletal development were observed, but 7 out of 73 neonatal mice born to parents given cyanobacterial extract showed reduced brain size. No cases were seen in controls. We conclude that the major toxicity exhibited is liver injury. Further attention is needed for evaluation of carcinogenicity and embryonic damage.

Administration, Oral↗
PubMed1988

BCG emulsion immunotherapy of equine sarcoid.

Of 61 horses with sarcoids treated with intralesional injection of a double emulsion incorporating inactivated bacillus Calmette Guérin organisms, 36 (59 per cent) showed complete regression and 11 (18 per cent) showed partial regression. The majority of cases required only one treatment. Not all sarcoids were responsive to this therapy; those not responding were usually large or on horses with multiple sarcoids.

Animals↗
PubMed1987

Kikuyu poisoning of cattle in New South Wales and its relationship to pasture fungi on kikuyu grass (Pennisetum clandestinum).

In the late summer and autumn of 1980 kikuyu poisoning of cattle was diagnosed on 9 farms in New South Wales resulting in 213 deaths among 1370 cattle at risk. Clinical, autopsy and histopathological findings are described and are consistent with those previously recorded. Kikuyu grass samples from 5 paddocks in which deaths were occurring were examined for the presence of fungi. Myrothecium spp were not present. Fusarium semitectum, F. moniliforme var subglutinans, Penicillium spp and a Phoma sp were the most common fungi isolated but with the exception of F. semitectum were not consistently present. F. semitectum was present in adjacent kikuyu grass paddocks in which deaths were not occurring. Two of the farms had army caterpillar (Mythimna convecta) infestations. Army caterpillar faeces present in these paddocks did not contain Myrothecium spp; the fungi present reflected the population present on the kikuyu grass. These findings do not suggest a mycotic cause for kikuyu poisoning.

Animal Feed↗
PubMed1986

Lethal potency and tissue distribution of 125I-labelled toxic peptides from the blue-green alga Microcystis aeruginosa.

Toxic heptapeptides from a water bloom of the cyanobacterium Microcystis aeruginosa were purified by HPLC. The unoxidised fraction was iodinated with 125I plus 127I by the lactoperoxidase/H2O2 method, further purified by HPLC, and the non-iodinated and three iodinated fractions administered i.p. to male mice. All iodinated fractions were toxic, with symptoms and pathological lesions of the liver identical with those caused by non-iodinated peptide. Radioactivity was concentrated in the liver of mice at death.

Animals↗
PubMed1985

Severe hepatotoxicity caused by the tropical cyanobacterium (blue-green alga) Cylindrospermopsis raciborskii (Woloszynska) Seenaya and Subba Raju isolated from a domestic water supply reservoir.

Cylindrospermopsis raciborskii, a tropical blooming species of cyanobacterium (blue-green alga), was isolated from the domestic water supply reservoir on Palm Island, a continental island off the tropical northeast coast of Australia. This species, not previously known to be toxic, was shown to be severely hepatotoxic for mice. The 50% lethal dose at 24 h after injection was found to be 64 +/- 5 mg of freeze-dried culture per kg of mouse. The principal lesion produced was centrilobular to massive hepatocyte necrosis, but various degrees of injury were also seen in the kidneys, adrenal glands, lungs, and intestine. The possible implication of this finding in relation to an incident of hepatoenteritis in humans living on the island is discussed.

Animals↗
PubMed1984

Disseminated fat necrosis mimicking gout.

A case of disseminated fat necrosis in pancreatic disease which presented as an apparent arthritis is reported. The intravenous administration of aprotinin as a form is described.

Amylases↗