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Biomedical subjects

A G Johnson

Publications and source records attributed to A G Johnson.

At least 91 records · Page 5Linked to original sources
PubMed1996

The role of the radiologist in surgical management: an audit of clinico-radiological conferences.

A prospective analysis of the radiological findings and final diagnoses of 342 patients discussed at joint surgical/radiological conferences over a seven-month period was undertaken in an attempt to define the role of the radiologist in the clinical management of surgical patients. Although the diagnosis had already been correctly made on clinical or radiological grounds in 38% (130/342) of patients presented at the X-ray conferences, careful review of the films resulted in an immediate firm diagnosis in a further 9% (31/342), or promoted further radiological investigations which were responsible for an eventual definitive diagnosis in 20% of the remainder (32/169). The input of the radiologist in selecting the most appropriate additional investigation was particularly valuable in the management of more complex clinical problems.

Critical Pathways↗
PubMed1996

Determinants of migration values and expectations in rural Thailand.

"Based on the argument that values and expectations underlie behavioral motives, this study explores the determinants of migration-related values and expectations, and whether they are intervening factors in explaining intentions to move among residents of rural northeast Thailand. Data from the 1992 National Migration Survey of Thailand identify four migration-related value-expectancy dimensions: income, affiliation, stimulation, and comfort. Logistic regression analysis shows that landownership and being married are associated with higher expectations, while a diversified village economy, a village economy development program, and a younger and extended household structure are associated with lower expectations of attaining valued goals in the local rural village. The analysis also shows that value-expectancy concepts are only partial intervening explanations for intentions to move or stay."

Asia↗
PubMed1996

I/D polymorphism of the angiotensin-converting enzyme gene does not predict isolated systolic or systolic-diastolic hypertension in the elderly.

To determine whether insertion/deletion (I/D) polymorphism (intron 16) of the angiotensin converting-enzyme (ACE) gene is associated with isolated systolic hypertension (ISH: systolic blood pressure (BP) > or = 160, diastolic BP < 90 mm Hg) or systolic-diastolic hypertension (S-D hypertension: diastolic BP > or = 90 +/- systolic BP > or = 160 mm Hg) compared with normotensive controls (systolic BP < 160, diastolic BP < 90 mm Hg), we conducted a case-control study of 733 non-institutionalised, elderly (> or = 60 years) residents of Dubbo, NSW. Individuals were classified as: ISH (n = 167), S-D hypertension (n = 207) and normotensive control (n = 359) with age and sex matching. II, DD and ID genotypes were determined by a nested PCR strategy using DNA extracted from serum. The frequencies of D and I alleles in the control population (0.70 and 0.30 respectively) were not significantly different in the ISH group or the S-D hypertension group (chi 2: 1.7, P = 0.42). After adjustment for several potential confounders, neither genotype nor allele predicted ISH (II vs DD: odds ratio (OR): 1.06, 95% confidence interval (CI): 0.55-2.03; I vs D: 1.09, 0.82-1.46) or S-D hypertension (II vs DD: 1.19, 0.67-2.10; I vs D: 1.16, 0.89-1.52) in this elderly cohort. The I/D polymorphism of the ACE gene is not a marker for either form of hypertension in this large elderly sample.

Aged↗
PubMed1996

Potential mechanisms by which nonsteroidal anti-inflammatory drugs elevate blood pressure: the role of endothelin-1.

To determine whether endothelin-1 (ET-1) contributes to hypertension associated with non-steroidal anti-inflammatory drug (NSAID) usage in healthy, elderly, normotensive individuals a randomised, double-blind, placebo-controlled, crossover trial of indomethacin was undertaken in 41 healthy, elderly individuals with stable normotension or controlled hypertension (blood pressure (BP) < or = 160/90 mm Hg). The main outcome measures were systolic and diastolic BP, heart rate, cardiac output, weight, creatinine clearance, plasma renin activity, aldosterone, endothelin-1 and arginine vasopressin concentrations and 24 h urinary endothelin-1 and 6 keto prostaglandin F1 alpha outputs. Analysis of covariance was used to evaluate the effect of indomethacin on BP and related parameters. Indomethacin treatment for 1 month increased systolic (+/- s.e.m.: 4.1 +/- 2.2 mm Hg; 95% confidence interval 0 to 8.3 mm Hg) and diastolic BP (2.7 +/- 1.1 mm Hg; 0.4 to 4.9 mm Hg) without altering cardiac output (P = 0.59), implying an increase in total peripheral resistance. Indomethacin treatment produced a small increase in weight (1.4 +/- 0.4 kg; 0.6 to 2.2 kg), a small reduction in renal function (creatinine clearance: 6.8 +/- 1.8 mis/min; 3.3 to 10.3 mis/min) but a significant (83%) increase in daily urinary endothelin-1 production (13.1 +/- 3.4 ng/ml; 6.4 to 19.8 ng/ml) without altering plasma ET-1 concentration, suggesting increased renal synthesis. In conclusion, renal paracrine effects of ET-1 may contribute to NSAID-induced blood pressure elevation in humans.

Aged↗
PubMed1995

Non-steroidal anti-inflammatory drugs.

The elderly are at higher risk of adverse reactions from non-steroidal anti-inflammatory drugs (NSAIDs), including those due to drug interactions, than younger people. Before prescribing oral NSAIDs in the elderly, the clinician should consider other forms of therapy and topical NSAIDs. When an oral NSAID is used, the dose should be minimised and the need for treatment reviewed periodically to reduce duration of therapy. NSAIDs with a high risk of toxicity (such as phenylbutazone, salicylates, piroxicam and indomethacin) should be avoided in the elderly.

Administration, Oral↗
PubMed1995

Effects of piezoelectric lithotripsy on human DNA.

Genomic DNA was extracted from excised gallbladder mucosa, obtained shortly after a single treatment piezoelectric lithotripsy. Control samples were obtained from age and sex-matched patients who had received no lithotripsy. No DNA fragmentation was demonstrable on agarose gel electrophoresis. Suspensions of cultured lymphoblasts were subjected to different shock wave doses and the percentage of cells surviving the treatment was assessed immediately and the rate of cell death monitored over the following 7 h. The proportion of cells surviving the treatment decreased with increasing shock wave doses, but subsequent rate of cell death was no different from controls. DNA, extracted from the intact surviving cells, again showed no evidence of fragmentation on electrophoresis, but the DNA extracted from the supernatant showed extensive fragmentation.

Cell Survival↗
PubMed1995

Applied potential tomography in the measurement of gastric emptying in infants.

The aim of this study was to investigate the feasibility of using applied potential tomography (APT), a noninvasive and nonradioactive method, to measure the rate of gastric emptying in preterm babies and infants < 3 months old. APT, a form of electrical impedance tomography, creates tomographic images of tissue resistivity to a small electrical current and has been used to study gastric emptying in adults. The rate of gastric emptying of 53 preterm infants and 29 term infants was measured. The test feed was either milk (formula milk or expressed breast milk) or Dioralyte (a commercial rehydration solution). When a nasogastric tube was present, the results obtained by APT were validated by comparing the volume of feed estimated to be present with the volume that could be aspirated. All infants completed the investigation without any problems. APT demonstrated a slower rate of emptying of milk feeds than Dioralyte and showed that milk and Dioralyte feeds in preterm babies emptied at a similar rate to feeds in term infants. In validation studies, gastric emptying has been observed in 44 of 47 studies, and this finding was confirmed by aspiration of the nasogastric tube. Applied potential tomography is a safe, noninvasive method for measuring gastric emptying in small infants.

Bottle Feeding↗
PubMed1995

Evaluation and comparison of the TDxII, Stratus, and OPUS digoxin assays.

Three automated immunoassays for digoxin in serum were evaluated--Abbott TDxII, Baxter Stratus, and Behring OPUS. The accuracy and precision of the assays were assessed by weighed-in controls and an external quality control program. Coefficients of variation of all methods in serum were < or = 10% at weighed-in concentrations of digoxin of 1 and 2.5 micrograms/L. Accuracy relative to weighed-in concentrations of 1 and 2.5 micrograms/L ranged from 98 to 126% for all methods. Comparative results from patient samples showed little difference between the TDxII and Stratus and a greater difference observed between the TDxII and OPUS assays. The detection of digoxin-free samples containing digoxin-like immunoreactive substances (DLIS) in neonatal cord blood, pregnant patients, and liver and renal recipients by each assay was then assessed. The TDxII exhibited the highest incidence of DLIS. This is evident in neonatal cord blood in which 40.4% of samples tested positive. In comparison, the extent of DLIS detected by Stratus was less and OPUS exhibited no DLIS in any of the groups studied. A case study of a patient treated with anti-digoxin Fab fragments (Digibind) also was included for analysis by each method. Fourteen hours after Digibind administration, the TDxII registered a digoxin concentration of 49.5 micrograms/L compared with 3.73, 1.80, and 2.49 micrograms/L for Stratus, OPUS, and ultrafiltered TDxII methods, respectively. The results indicate that to determine the concentration of digoxin after the administration of Digiband, the OPUS or fluorescence polarization immunoassay (FPIA)-ultrafiltered samples by TDxII are the assays of choice.

Adult↗
PubMed1995

Reversal of lipopolysaccharide-analog-induced antibody suppression by anti-transforming growth factor beta and indomethacin.

Monophosphoryl lipid A and a synthetic, nontoxic monosaccharide analog of lipid A, termed GLA 60, both strongly suppressed antibody production when administered 1 to 2 days prior to antigen. Evidence is presented that this suppression was mediated by two cytokines, prostaglandin E and transforming growth factor beta, because it was reversed by multiple injections of the cyclooxygenase inhibitor indomethacin and by in vitro addition of antibody to transforming growth factor beta.

Animals↗
PubMed1995

Conflicting demands in surgical practice.

975 Fellows of the Association of Surgeons of Great Britain and Ireland were circulated with a questionnaire which was designed to assess the extent to which they experienced conflicts between personal, clinical and administrative demands. Seventy-one per cent of the 305 respondents indicated that they had experienced such conflicts within the previous three weeks. When a conflicts between administrative and clinical demands was experienced, surgeons gave priority to each in similar proportions, but when personal or family needs conflicted with clinical or administrative demands, their personal lives were almost always given a lower priority. The surgeons reported that these types of conflict often affected the quality of patient care and 60 per cent indicated that they were considering early retirement.

Adult↗
PubMed1995

The value of abdominal exploration during cholecystectomy.

With the advent of 'minimal access' cholecystectomy patients no longer have an exploratory laparotomy at the time of the operation and it is possible that relevant pathology may be missed as a result. This study analyses the findings at exploratory laparotomy in 223 patients undergoing open cholecystectomy. Forty-two patients (19%) were found to have incidental pathology but in only three (1.3%) did this lead to additional operative procedures. We therefore conclude that the loss of exploratory laparotomy at cholecystectomy does not have a significant detrimental effect on patient care.

Adenocarcinoma↗
PubMed1994

Surgery as a placebo.

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Attitude of Health Personnel↗
PubMed1994

Do nonsteroidal anti-inflammatory drugs affect blood pressure? A meta-analysis.

PURPOSE: A meta-analysis of randomized trials studying the effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on blood pressure. DATA SOURCES AND STUDY SELECTION: Eight databases were searched, yielding 38 randomized, placebo-controlled trials and 12 randomized but not placebo-controlled trials (comparing two or more NSAIDs). DATA EXTRACTION: Pooled mean treatment effects were computed in each trial for blood pressure, weight, creatinine clearance, plasma renin activity, and daily urinary excretion of sodium and prostaglandins. Meta-analyses of these variables were done for all randomized, controlled trials; for all randomized, uncontrolled trials; and for several subgroups. DATA SYNTHESIS: When pooled, NSAIDs elevated supine mean blood pressure by 5.0 mm Hg (95% CI, 1.2 to 8.7 mm Hg) but had no effect on variables other than blood pressure. Nonsteroidal anti-inflammatory drugs antagonized the antihypertensive effect of beta-blockers (blood pressure elevation, 6.2 mm Hg; CI, 1.1 to 11.4 mm Hg) more than did vasodilators and diuretics. Among NSAIDs, piroxicam produced the most marked elevation in blood pressure (6.2 mm Hg; CI, 0.8 to 11.5 mm Hg), whereas sulindac and aspirin had the least hypertensive effect. CONCLUSIONS: Nonsteroidal anti-inflammatory drugs may elevate blood pressure and antagonize the blood pressure-lowering effect of antihypertensive medication to an extent that may potentially increase hypertension-related morbidity. Although certain NSAIDs and antihypertensive agents could be more likely to produce these effects, the underlying mechanisms require further study.

Adult↗