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Biomedical subjects

J A Hart

Publications and source records attributed to J A Hart.

At least 19 recordsLinked to original sources
PubMed1998

The surgeon and casemix.

Casemix funding has markedly increased surgeons' awareness of the economies of the activities they undertake. Surgery has become a major focus at all large public hospitals, because of its high earning potential, and this pressure to maximise funding could influence surgical practice. Casemix funding's emphasis on length of hospital stay has encouraged forward planning for earlier discharge after surgical procedures. Patients are now assessed in pre-admission clinics, educated about their condition and their hospital stay, and a plan formulated for their discharge and rehabilitation. Funding for major surgical procedures of long duration in patients with complex conditions should reflect the higher level of resource utilisation. Tertiary referral centres, because of their commitment to training and research and their more severely ill patient population, are less cost-effective and require funding to ensure their viability. The improved information that casemix generates should be used to evaluate outcomes and improve patient care; efficiency must not take precedence over quality of care and compassion.

Australia↗
PubMed1997

The efficacy of intra-articular morphine for postoperative knee arthroscopy analgesia.

This article describes two prospective, randomized, double-blind clinical trials designed to investigate this. Trial 1 compared a conventional local anaesthetic agent (100 mg bupivacaine) injected intra-articularly (i.a.) with a control (normal saline) and 1 mg of i.a. morphine. No significant difference was noted in the first 4 hours between the groups with respect to visual analogue pain (VAS) scores. However, at 6 and 24 hours, the group of patients who received 1 mg i.a. morphine recorded lower pain scores and required less supplementary analgesia. Trial 2 assessed the dose response relationship for i.a. morphine comparing 5 mg intravenous (i.v.) morphine (control) with 1 mg and 5 mg i.a. morphine. At early time points (1, 2, and 4 hours) similar VAS pain scores were recorded for both 5 mg i.v. morphine and 5 mg i.a. morphine, both significantly lower than the group receiving 1 mg i.a. morphine. At 6 and 24 hours, 5 mg of i.a. morphine produced significantly lower pain scores, less analgesic requirement, and less sleep disturbance on the first postoperative night than the other groups. It can be concluded from these two studies that 5 mg i.a. was the most effective analgesic following knee arthroscopy.

Adult↗
PubMed1996

L-trans-2,3-pyrrolidine dicarboxylate: characterization of a novel excitotoxin.

This study investigated the in vitro and in vivo excitotoxic properties of a novel conformationally constrained analogue of L-glutamate, L-trans-2,3-pyrrolidine dicarboxylate (L-trans-2,3-PDC). When tested for excitotoxic activity in rat cortical cultures, L-trans-2,3-PDC mimicked the action of NMDA in both acute (30 min) and chronic (24 h) exposure paradigms. This neurotoxicity was attenuated by co-addition of MK-801 (10 microM). Microinjections of L-trans-2,3-PDC into the dorsal hippocampus of male rats also induced a selective pattern of pathology indicative of an NMDA receptor excitotoxin. In contrast to the equipotency observed in vitro, 100 nmol of L-trans-2,3-PDC were needed to produce cellular damage comparable to that induced by 25 nmol of NMDA. Consistent with an action at NMDA receptors, L-trans-2,3-PDC-induced damage could be significantly reduced by co-administration of MK-801 (3 mg/kg i.p.), but not by NBQX (25 nmol). In radioligand binding assays L-trans-2,3-PDC inhibited the binding of 3H-L-glutamate to NMDA receptors (IC50 1 microM), although it also exhibited some cross reactivity with KA and AMPA receptors. L-trans-2,3-PDC was also identified as a competitive inhibitor (Ki = 33 microM) of 3H-D-aspartate uptake into rat forebrain synaptosomes. In contrast to the action of a transported substrate, such as L-glutamate, L-trans-2,3-PDC did not exchange with 3H-D-aspartate that had been previously loaded into the synaptosomes.

Animals↗
PubMed1995

Treatment outcome of major fractures of the talus.

Twenty-six patients with major fractures of the talus were studied to assess the long-term outcome. The patients were admitted to a university teaching hospital and major trauma center from 1983 to 1991. The study excluded isolated fractures of the talar dome and posterior tubercle. Fifteen patients were treated using internal fixation and 11 patients were treated using nonsurgical methods. Avascular necrosis was detected in only four of the 26 patients. Subtalar osteoarthritis was a significant problem in 61%. Seven of these patients have come to secondary fusion procedures, with another three contemplating fusion procedures at the time of review. Only one patient developed significant avascular necrosis requiring a fusion procedure. Only three of 26 patients had not returned to work at a mean 6 years after their injury. Eleven of the 26 (42%) had not returned to their premorbid activity level. The majority of these patients (25/26) had sustained multiple injuries, which compromised the functional recovery from the talar injury. Early accurate diagnosis and anatomical reduction gave the best results. The low incidence of avascular necrosis in this study has been attributed to early anatomical stabilization of the fracture. We believe an early CT scan can more accurately assess the severity of the talar fracture and offers the best information for an appropriate treatment plan.

Adult↗
PubMed1993

Preoperative autologous blood donation. Linkage of the public and private hospital sectors.

OBJECTIVE: To evaluate the safety and efficacy of a preoperative autologous blood donation (PABD) program with liberal patient exclusion criteria. DESIGN: Prospective patient accrual from September 1990 to May 1992. SETTING: A PABD program in a public tertiary care hospital linked with a specialist orthopaedic practice in a private hospital. PATIENTS: One hundred and twenty patients consecutively scheduled for orthopaedic surgery were referred for PABD. There were 77 women (median age, 63 years) and 43 men (median age, 62 years). One-third of patients were 70 or more years old. Coexistent medical disease, mainly cardiovascular, was present in 46% of patients and 3% were excluded because of coexisting morbidity. Total hip or total knee replacement was performed in a private hospital with intraoperative or postoperative blood salvage in 37% of the patients. OUTCOME MEASURES: Adverse effects of PABD, autologous blood collected and used and homologous blood transfused. RESULTS: One hundred and sixteen patients donated 267 units of autologous blood. In 70 patients undergoing total hip replacement, 78% donated three and 20% donated two units, with 95% of autologous blood being used. In 38 patients undergoing total knee replacement, 42% donated two units and 55% donated one unit, with 87% of autologous blood being transfused. Seventy-eight per cent of all patients only received autologous blood. In the remaining patients, homologous blood use was confined to two units or less in 80%. Hypotensive episodes associated with phlebotomy occurred in 3% of patients, and 13% of patients had preoperative haemoglobin levels ranging from 85-100 g/L without adverse clinical effects. CONCLUSION: A hospital-based PABD program with less strict patient exclusion criteria does not prejudice the clinical status of the donors. Its linkage to private hospitals can significantly reduce the use of homologous blood in selected elective surgery.

Adult↗
PubMed1985

The urethral catheter--a review of its implication in urinary-tract infection.

The research into acquisition of urinary-tract infection over the last few decades has established three ways in which organisms may gain access to the urinary tract of the catheterized patients: Firstly, during the process of passing the catheter into the bladder should complete asepsis not be observed; secondly by travelling along the urethra in the small, fluid-filled cavity between catheter and mucosa; Thirdly following contamination of the drainage system, along the inside of the catheter directly into the bladder. The relative importance of each route is not clear and is still the subject of much controversy but it would seem that all these routes have a part to play in allowing infection to develop. The risk of catheterized patients acquiring urinary-tract infection is so great that where possible catheterization should be avoided. The most important preventive measure which may be taken is to limit the duration of indwelling catheterization. In addition, a considerable amount of research has attempted to distinguish other factors which might affect the rate at which urinary-tract infection in the catheterized patient becomes established so that high-risk patients may be identified. The evidence indicates that the risk increases with duration of catheterization, age, length of hospital stay, immunosuppressant treatment, that it is greater in female than male patients and that a patient with a serious or fatal underlying disease is also more likely to develop bacteriuria. Finally, properties of the urine and the host defence mechanisms may affect the susceptibility of the individual to urinary-tract infection. Identification of the routes of infection and patients at risk is only part of the problem. The next stage is to formulate criteria for the care of catheterized patients which reduce the risk of infection to the absolute minimum and will hopefully go some way towards diminishing the unsatisfactory high levels of urinary-tract infection that are currently associated with indwelling catheterization.

Age Factors↗
PubMed1985

A study of the relationship between the pharmacokinetics and the pharmacodynamics of the 4-hydroxycoumarin anticoagulants warfarin, difenacoum and brodifacoum in the rabbit.

The pharmacokinetics and pharmacodynamics of the 4-hydroxycoumarin anticoagulants, brodifacoum, difenacoum, and warfarin have been studied in the rabbit. Sensitive (50 ng ml-1) and specific high performance liquid chromatography assays have been developed for the determination of plasma concentrations of warfarin, brodifacoum and difenacoum. After administration of a single intravenous dose (20 mumol kg-1), plasma concentrations of warfarin underwent mono-exponential decay, with a terminal half-life of 5.6 +/- 0.7 h (mean +/- s.e. mean), whereas plasma concentrations of brodifacoum and difenacoum underwent bi-exponential decay with terminal half-lives of 60.8 +/- 1.9 h and 83.1 +/- 10.3 h respectively. The plasma half-life of brodifacoum in a single patient poisoned with the compound was 487 h. The pharmacological response to the anticoagulants was measured as changes in prothrombin complex activity, from which the rate of clotting factor synthesis was determined. Clotting factor synthesis recovered in a monophasic fashion after a single intravenous dose of warfarin, compared with a more complex biphasic, pattern of recovery of clotting factor synthesis after administration of either brodifacoum or difenacoum. The slope (m) of the intensity of effect-log (amount of drug in the body) curve was derived for each anticoagulant. There was no significant difference in the value of m after single intravenous doses of racemic, R-, and S-warfarin, difenacoum and brodifacoum, which is consistent with the hypothesis that all the 4-hydroxycoumarin anticoagulants produce their anticoagulant effect by acting at the same receptor site, vitamin K epoxide reductase. Determination of the minimum plasma concentration of each anticoagulant that corresponded with the complete inhibition of clotting factor synthesis indicated that racemic warfarin, R-warfarin and brodifacoum have similar potencies in the rabbit and are less potent than S-warfarin and difenacoum.

4-Hydroxycoumarins↗
PubMed1984

A study of factors which determine the pharmacological response to vitamin K in coumarin anticoagulated rabbits.

The pharmacological response to vitamin K has been determined by measuring prothrombin complex activity (P.C.A.) in male New Zealand White rabbits anticoagulated (P.C.A. less than 20%) with the long acting 4-hydroxycoumarin brodifacoum, at a dose (10 mg/kg) which produces maximum antagonism of vitamin K1. Thus, according to current concepts, this animal model may be used to assess vitamin K requirements in the absence of a functional vitamin K-epoxide reductase. After intravenous administration of vitamin K1 (1 mg/kg) P.C.A. reached a maximum (64 +/- 19%) at 3 hr and then declined at a rate which corresponds to complete inhibition of clotting factor synthesis. Vitamin K2 (1 mg/kg) stimulated clotting factor synthesis for 2 hr, while cis-vitamin K1, vitamin K3, vitamin K1 2,3-epoxide and oral administration of vitamin K1 were ineffective. Plasma concentrations of vitamin K1 fell steeply during the 12 hr following administration of a pharmacological dose, and then declined with a terminal half-life of 18.9 +/- 9.0 hr. Comparison of the pharmacodynamic and pharmacokinetic data indicated that plasma concentrations in the range 0.4-1.0 microgram/ml are required for clotting factor synthesis in the limiting situation of maximum antagonism of vitamin K by coumarin anticoagulants. These findings explain why frequent and repeated administration of vitamin K1 may be necessary during coumarin poisoning.

Animals↗
PubMed1982

Closed Küntscher nailing: a clinical review after 20 years.

A long-term study of patients treated by primary closed Küntscher nailing of fractures of the femoral shaft was carried out. Minimal reaming allowed nails of only 9.5-11 mm diameter to be used. One hundred and sixteen patients with 120 fractures treated in this way from 1959 to 1978 attended for clinical examination. Primary bony union was achieved in 98 per cent and the infection rate was less than 1 per cent. Full, unsupported weight bearing was possible at an average of 15.6 weeks. Symptoms and residual deformity were minimal. These results support the use of this technique in adults with most types of fracture of the femoral shaft.

Adolescent↗
PubMed1981

The ethnobotany of the Northern Cheyenne Indians of Montana.

The Northern Cheyenne Indians of eastern Montana recognized at least 138 species of plants. The collection, preparation, utilization and names of these plants are described, and their role in Cheyenne culture for food, technology, medicine and religion are discussed. Cheyenne plant medicines, though combined with ritualistic healing practices, included the use of many herbal teas which they drank for internal problems, and powders and poultices which they applied externally; many of these were combined to form medicinal mixtures. Certain plants, believed to possess benevolent powers, were employed in various religious ceremonies. Though Cheyennes once cultivated crop plants, their more recent nomadic existence encouraged the use of wild food plants, especially fruits and roots which they sun-dried and stored for winter use.

History, 19th Century↗