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Biomedical subjects

J F Thompson

Publications and source records attributed to J F Thompson.

At least 217 records · Page 12Linked to original sources
PubMed1992

Donor factors and liver transplantation.

There are thus many factors that may affect the suitability of a donor liver for transplantation, and a reliable, objective method of determining whether or not a liver is likely to function adequately after transplantation is urgently required. At the present time, however, the decision to use a particular donor liver remains a matter of clinical judgement. This decision will inevitably be influence both by the general availability of donor organs and by the urgency of recipient need at the time the liver becomes available, but should nevertheless be based primarily on an appreciation of the donor factors described above.

ABO Blood-Group System↗
PubMed1992

Vascular surgical training in the UK and Ireland.

Fifty-six vascular surgical trainees and 31 recently appointed consultants with an interest in vascular surgery replied to a postal questionnaire about their training. The majority fulfilled the guidelines recommended by the Vascular Advisory Committee of the Vascular Surgical Society of Great Britain and Ireland, which are--a minimum two years of higher surgical training in units with an interest in vascular surgery and a substantial and comprehensive experience of (operative) vascular surgery. However, the operative experience during training was very variable, ranging between 10 and 574 operations reported by new consultants. Minimum standards of operative experience may need to be defined. The survey also identified that training in carotid endarterectomy is sometimes deficient and noted that as much as one-third of operative experience may be gained 'out of hours' on emergency cases. To obtain this experience trainees have to work very long hours, two-thirds of senior registrars have vascular on call rotas of 1:2 or less. Imminent changes in the structure of higher surgical training and the reduction in hours worked by junior doctors may seriously affect vascular surgical training.

Education, Medical, Graduate↗
PubMed1992

Structured and unstructured grid generation.

Current techniques in composite-block-structured grid generation and unstructured grid generation for general 3D geometries are summarized, including both algebraic and elliptic generation procedures for the former and Delaunay tessellations for the latter. Citations of relevant theory are given. Examples of applications for several geometries are included.

Algorithms↗
PubMed1991

Autotransfusion.

Explore the source record for details and available documents.

Blood Loss, Surgical↗
PubMed1991

Modulation of firefly luciferase stability and impact on studies of gene regulation.

Two of the reporter enzymes most commonly used in studies of eukaryotic gene expression are chloramphenicol acetyl-transferase (CAT) and firefly luciferase (Luc). CAT has a half-life of about 50 h in mammalian cells, making it useful for transient transfection assays but less suitable for assays with stable cell lines. Luc has a half-life of only 3 h in mammalian cells, making it much more responsive in stable cell lines. Luc instability arises from its sensitivity to proteolysis both in vivo and in vitro. Compounds that resemble its natural substrate, luciferin, act as effective competitive inhibitors in vitro. When these compounds (e.g., phenylbenzothiazole) are added to either prokaryotic or eukaryotic cells, more than tenfold increases in Luc activity can be observed. This increased activity results from a lower rate of degradation of the enzyme in vivo and can be mimicked in vitro as phenylbenzothiazole protects Luc from trypsin digestion while it has no effect on the rate of digestion of alkaline phosphatase.

Alkaline Phosphatase↗
PubMed1991

Acute and subacute fulminant hepatic failure: the role of liver transplantation.

OBJECTIVES: To report the experience of the Australian National Liver Transplant Unit with patients with fulminant hepatic failure and to describe the role of liver transplantation. PATIENTS: Twenty-seven patients presented with acute or subacute fulminant hepatic failure during the period from January, 1986, to March, 1990. Twenty-two had acute and five had subacute fulminant hepatic failure. The causes were hepatitis B in 10 patients, presumed non-A, non-B (NANB) hepatitis in eight patients, drug-induced hepatic damage in five patients, and Wilson's disease in four patients. There were 13 males and 14 females. Ages were 2-43 years (mean, 23). Twenty patients (74%) were in grade IV encephalopathy on presentation. RESULTS: Six patients (22%) began to improve soon after admission and went on to full recovery. Spontaneous recovery was more frequent in patients with drug-induced hepatic damage (four patients [80%]) and was less frequent in those with hepatitis B (one patient [10%]) and NANB hepatitis (one patient [12%]). The other 21 patients (78%) were considered for orthotopic liver transplantation. Eight (30%) were judged to be unsuitable and went on to early death. Thirteen (48%) were suitable for transplantation. Of these five (19%) died before a liver donor became available and eight (30%) received liver grafts and went on to full recovery. Overall, 14 patients (52%) survived and 13 (48%) died. Patients with Wilson's disease (four [100%]) were most suitable for orthotopic liver transplantation whereas eight (44%) of those with hepatitis B or NANB hepatitis were unsuitable. Of the eight patients receiving liver grafts one had hepatitis B, three had NANB hepatitis and four had Wilson's disease. Five were in grade IV encephalopathy at the time of operation. The mean waiting time for transplantation was 6.4 days. Five patients received ABO blood group compatible grafts and three received ABO incompatible grafts. Of the latter group, two subsequently required secondary orthotopic liver transplantation with ABO compatible grafts. All eight patients who received transplants are alive and well 3-24 months after the operation. No patient has any neurological sequelae. CONCLUSIONS: Orthotopic liver transplantation is a preferred option for patients with fulminant hepatic failure whose condition is not responding to conservative management. ABO incompatible livers transplanted in emergency circumstances may prove life-saving either by functioning successfully or by providing time during which ABO compatible grafts become available.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute Disease↗
PubMed1991

Experience with 998 cutaneous melanomas of the head and neck over 30 years.

Between 1960 and 1990, a total of 998 patients were treated at the Sydney Melanoma Unit for cutaneous melanoma of the head and neck. There were 595 male and 403 female patients, with a median age of 53 years. The most common primary lesion site was the face (47%), followed by the neck (29%), scalp (14%), and ear (10%). Histologic types were as follows: superficial spreading 30%, nodular melanoma 28%, lentigo maligna melanoma 16%, and other 26%. All patients underwent surgical treatment. Primary closure of wounds was achieved in 52% of patients, and excision margins were 2 cm or less in 45%. A total of 152 patients had therapeutic neck dissections, and 234 had elective neck dissections. The overall local recurrence rate was 13%, and this was significantly influenced by increasing tumor thickness and Clark level. The recurrence rate in the neck after neck dissection was 24%, and the rate of parotid recurrences was 14%. Melanoma-specific survival was 77% at 5 years and 66% at 10 years for the entire group. By univariate analysis, survival varied significantly with age, tumor thickness, ulceration, anatomic sub-site, histologically positive nodes, and the presence of distant metastases. A diagnosis of lentigo maligna melanoma and elective lymph node dissection both appeared to improve survival. With multivariate analysis, all of these factors remained significant prognostic factors except elective node dissection, which lost its beneficial influence.

Female↗
PubMed1991

The Allen Brown shunt: a useful option for vascular access.

This study analyzes the performance of 273 Allen Brown arteriovenous shunts inserted in the thigh and anastomosed to the superficial femoral artery and either the superficial femoral vein or the long saphenous vein. The median duration of shunt function was 9 weeks (range: 0 to 175 weeks). A significantly longer median function time of 22 weeks was found in patients who had had more than five previous access procedures (p less than 0.02). No other independent variable affecting shunt function time was identified. There were 84 complications (56 due to infection) and 2 deaths in the series. The infection rate was not improved by the use of perioperative antibiotics, with most infections occurring more than 6 weeks after insertion. Since the complication rate for Allen Brown shunts was no greater than that reported for subclavian catheters, and their function no less reliable than that reported for Quinton-Scribner shunts, the Allen Brown shunt is a useful option for short- and medium-term vascular access. It may also be useful for longer-term access in the patient in whom failure of multiple previous access procedures has occurred.

Adolescent↗
PubMed1991

Influence of water deficit on maize endosperm development : enzyme activities and RNA transcripts of starch and zein synthesis, abscisic Acid, and cell division.

In maize (Zea mays L.), drought during the post-pollination stage decreases kernel growth and often leads to grain yield losses. Kernels in the apical region of the ear are more severely affected than basally positioned kernels. We hypothesized that water deficit during early endosperm development might inhibit kernel growth by decreasing endosperm cell division, and that this response might be mediated by changes in endosperm abscisic acid (ABA) levels. Greenhouse-grown maize, cultivar Pioneer 3925, was subjected to water limitation from 1 to 15 days after pollination (DAP), spanning the period of endosperm cell division and induction of storage product accumulation. Water deficit decreased the number of endosperm nuclei during the treatment period; the most substantial effect was in the apical region of ears. Correspondingly, endosperm fresh weight, starch accumulation and dry mass at maturity were decreased by water limitation. Abscisic acid concentrations in endosperm were quantified by enzyme-linked immunosorbent assay. Water deficit increased ABA concentration in apical-region endosperm by four-fold compared to controls. ABA concentrations were also increased in middle and basal regions of the ear, but to a lesser extent. Two key enzymes in the starch synthesis pathway, sucrose synthase and granule-bound ADP-glucose starch synthase, and zein, the major storage protein in maize endosperm, were studied as markers of storage product synthesis. Water deficit did not affect sucrose synthase enzyme activity or RNA transcript abundance relative to total RNA. However, ADP-glucose starch synthase activity and RNA transcript abundance decreased slightly in apical-region endosperm of water-limited plants by 15 DAP, compared with well-watered controls. In contrast to starch, there was no treatment effect on the accumulation of zein, evaluated at either the polypeptide or RNA level. We conclude that under the conditions tested, the establishment of starch and zein synthetic potential in endosperm was only slightly affected by plant water deficit during the early phase of kernel growth, and that capacity for growth and starch accumulation was affected by the extent to which cell division was inhibited. Based on correlative changes in ABA concentration and cell division we suggest that ABA may play a role in inhibiting endosperm cell division during water limitation.

Journal Article↗
PubMed1991

The role of medications in geriatric sexual function.

Geriatric patients take proportionately more drugs than do their younger counterparts. This, along with an aging sexual physiology, places them at greater risk for experiencing adverse drug reactions affecting sexual function. The major therapeutic categories implicated in drug-induced geriatric sexual dysfunction are the psychotherapeutic agents, such as the antidepressants and the neuroleptics, and the cardiovascular agents, predominantly the antihypertensives. There are limited drug therapies available for the treatment of sexual dysfunction in the elderly. Therapies associated with some limited clinical success include the use of testosterone and bromocriptine for impotence associated with androgen deficiencies, intracavernosal injection of vasoactive drugs, and yohimbine. Women with inadequate maintenance of vaginal lubrication may benefit from topical lubricants or estrogens and orally or transdermally administered estrogens.

Aged↗
PubMed1990

The initial characterization of the iron environment in lipoxygenase by Mössbauer spectroscopy.

The incorporation of 57Fe into two lipoxygenase isoenzymes from soybeans has been achieved making possible the first observations of the iron environment in these proteins using Mössbauer spectroscopy. Immature soybean seeds were grown in tissue culture medium supplied with 57Fe. The iron in the active lipoxygenases that were isolated from the cultured seeds was readily detected in Mössbauer measurements. It was unequivocally demonstrated that the native enzyme contains high-spin Fe(II). Based on the sign of the electric field gradient, the most likely ligand sphere for the iron in native lipoxygenase consists of oxygen and nitrogen ligands in a roughly octahedral field of symmetry. It was possible to detect Mössbauer signals in highly concentrated samples of native lipoxygenases containing 57Fe at natural abundance. The spectra obtained for enriched and natural abundance native enzyme had the same high-spin Fe(II) Mössbauer parameters. This confirmed that the environment of the iron in enzymes isolated from cultured seeds and dry soybeans were the same. The Mössbauer spectra (4.2-250 K) for samples of both isoenzymes after oxidation of the iron in native enzyme by the product of lipoxygenase catalysis were extremely broad (20 mm/s) with no obvious narrow resonance lines. This was the result of the existence of paramagnetically broadened spectra for such samples even at relatively high temperature as evidenced by the appropriate EPR signal. A small molecule containing an iron site sharing many of these Mössbauer and electron paramagnetic resonance properties with lipoxygenase was identified: Fe(II)/(III).diethylenetriaminepentaacetic acid.

Binding Sites↗
PubMed1990

Noise pollution in the operating theatre.

Sound levels during a typical major operation were measured to identify the main sources of noise in the operating theatre. Although overall sound levels were within the recommended levels for a satisfactory working environment, loud intermittent noises of up to 108 dB were emitted from sources such as suckers, "intercoms", and alarms on anaesthetic monitoring devices. The noisiest time was usually during the preparation period of the operation; during surgery, noise levels were much higher than levels of normal speech between staff. Preferred speech interference levels were often exceeded which made communication difficult and sometimes impossible. Communication and concentration were also disrupted by unnecessary background conversation.

Anesthesiology↗