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Biomedical subjects

M J Thompson

Publications and source records attributed to M J Thompson.

At least 55 records · Page 3Linked to original sources
PubMed1995

High-performance liquid chromatographic assay for the measurement of melphalan and its hydrolysis products in perfusate and plasma and melphalan in tissues from human and rat isolated limb perfusions.

A sensitive, specific and rapid reversed-phase high-performance liquid chromatographic (HPLC) assay was developed for the quantitation of melphalan and its hydrolysis products in samples from the isolated perfusion of human and rat limbs. Samples of perfusate, plasma and tissue were analysed, following methanol precipitation, using a phenyl column and fluorescence detection. Dansyl-arginine (38 micrograms ml-1) was employed as the internal standard. Good resolution was observed allowing quantitation of melphalan, monohydroxymelphalan (MOH) and dihydroxymelphalan (DOH) in perfusate and plasma were all 100 +/- 10%. The recovery of melphalan in tissue was 93.5%. A linear response was demonstrated for melphalan in the concentration range 1.8 - 56.8 micrograms ml-1, for DOH in the concentration range 0.5 - 30.0 micrograms ml-1 and for MOH in the range 1.4-25.1 micrograms ml-1, in perfusate and plasma. The lower limits of quantitation of melphalan, MOH and DOH in perfusate and plasma were 1.4, 2.4 and 1.2 ng on column, respectively, and 7.2 ng of melphalan on column in tissue. Intra-assay coefficients of variation (C.V.) for melphalan, MOH and DOH, at low and high concentrations were all less than 5% and the inter-assay C.V.s were less than 9%. An ultra-filtration study to determine the protein binding of melphalan and the hydrolysis products showed that the unbound fractions (fu) of melphalan in buffer containing dextran and bovine serum albumin were 0.873 and 0.521, respectively. The assay was used to quantitate melphalan and its hydrolysis products in samples from isolated perfusions in the human limb and rat hindlimb.

Adipose Tissue↗
PubMed1995

Promoter analysis of Zfp-36, the mitogen-inducible gene encoding the zinc finger protein tristetraprolin.

The gene encoding the putative zinc finger protein tristetraprolin (TTP), Zfp-36, is rapidly induced by a variety of mitogens and growth factors. We show here that 77 base pairs 5' of the transcription start site are sufficient for full serum inducibility of the mouse Zfp-36 promoter. This region of the promoter includes consensus sequences for the binding of the transcription factors EGR-1, AP2, and Sp1. In addition, we have identified a previously undescribed element, TTP promoter element 1 (TPE1); this 10-base pair sequence includes a palindrome and is identical in the human, bovine, and mouse genes. Each of the three binding elements, EGR-1, AP2, and TPE1, contribute to the serum induction of Zfp-36 and can confer serum-inducible expression on a heterologous minimal promoter. Gel mobility shift assays demonstrated the formation of complexes consisting of this region of the promoter and cellular nuclear proteins and demonstrated that the extent of complex formation could be altered by treatment of the cells with serum or insulin. These results suggest that the response of Zfp-36 to serum and other mitogens is mediated by a series of cis-acting elements acting in concert to confer full inducible transcription of this gene.

Animals↗
PubMed1995

Phosphorylation of tristetraprolin, a potential zinc finger transcription factor, by mitogen stimulation in intact cells and by mitogen-activated protein kinase in vitro.

Tristetraprolin (TTP) is a potential transcription factor that contains three PPPPG repeats and two putative CCCH zinc fingers. TTP is encoded by the early response gene Zfp-36, which is highly expressed in response to growth factors and in several hematopoietic cell lines. In the present studies, we investigated the possibility that TTP is phosphorylated in intact cells. In NIH/3T3 cells that were made to overexpress TTP constitutively, we found that the protein was phosphorylated on serine residues, and that this phosphorylation was rapidly (within 10 min) stimulated by several mitogens. In cell-free assays, recombinant mouse TTP was a substrate for the mitogen-activated protein (MAP) kinase. By a combination of protease digestion experiments and site-directed mutagenesis strategies, we found that serine 220 was phosphorylated by p42 MAP kinase in vitro. Expression of mutant TTP in fibroblasts confirmed that serine 220 was one of the major, mitogen-stimulated phosphorylation sites on the protein in intact cells. These results suggest that TTP may be phosphorylated by MAP kinases in vivo and that this phosphorylation may regulate its function.

3T3 Cells↗
PubMed1995

The glycosylceramides of the nematode Caenorhabditis elegans contain an unusual, branched-chain sphingoid base.

Caenorhabditis elegans was cultured in semi-defined medium containing yeast extract, soy peptone, glucose, hemoglobin, Tween 80, and sitosterol. Monoglycosylceramides were chromatographically purified from nematode extracts. Their structures were elucidated with mass spectrometry, nuclear magnetic resonance spectroscopy, and analysis of methanolysis products of the parent cerebrosides. The glycosylceramides were unusual in that the only long-chain sphingoid base detected was an iso-branched compound with a C-4 double bond (i.e., 15-methyl-2-aminohexadec-4-en-1,3-diol). Glucose was the only sugar moiety detected. The fatty acids consisted of a series of primarily straight-chain, saturated, 2-hydroxylated C20-C26 acids; some iso-branched analogs also occurred. The sphingomyelins of C. elegans were also hydrolyzed, and the same iso-branched C17 compound was the only sphingoid base detected. This is the first structural analysis of a nematode glycosphingolipid and the first report of an organism in which the long-chain sphingoid bases are entirely iso-branched.

Animals↗
PubMed1995

The Edinburgh Cardiac Surgery Score survival prediction in the long-stay ICU cardiac surgical patient.

Predictors of outcome in long-stay patients following cardiac surgery have hitherto been ill defined. The aims of this study were to test the Parsonnet pre-operative scoring system and to define a scoring system for inhospital mortality applicable post-operatively to strengthen the clinical decision-making process. Following case note review of 262 consecutive patients who stayed 7 days or more in intensive care, a total of 110 pre-, intra- and post-operative factors were documented. In this long-stay group the Parsonnet score was confirmed to be predictive of 30 day mortality. Univariate analysis identified significant association between mortality in the Intensive Care Unit (ICU) and the following: inotrope days, (defined as number of inotropes times number of days) ventilation, units of platelets (P = < 0.00001), chest reopening, fresh frozen plasma units (P < 0.002), total parenteral nutrition, noradrenaline, Parsonnet score (P = 0.005), dopamine, bypass time, vasodilators, intra-aortic balloon counterpulsation, enteral nutrition and other major surgery (P < 0.05). Stepwise logistic regression on these significant factors was used to produce the Edinburgh Cardiac Surgery Score (ECS) applicable from Day 10 onwards in the intensive care unit: ECS Score = (Inotrope days) +2 (Ventilation) + (Platelets) + (Parsonnet) -3. The ECS score may be a useful predictor of ICU mortality probability for cardiac surgical patients requiring 10 days or more intensive care and is presently undergoing prospective evaluation in our centre.

Adult↗
PubMed1994

Insulin and other growth factors induce binding of the ternary complex and a novel protein complex to the c-fos serum response element.

Rapid, transient induction of c-fos transcription follows treatment of cells with insulin and other growth factors. This is mediated through the serum response element (SRE), which binds the serum response factor (SRF), as well as accessory factors such as p62 ternary complex factor. Using a gel shift assay we found that formation of the ternary complex increased transiently within 2 min of insulin or phorbol ester treatment of several insulin-sensitive cell lines. However, mutations that prevented formation of this ternary complex did not inhibit insulin- or phorbol ester-stimulated induction of c-fos transcription in these cell lines. We also identified a novel SRF-containing multiprotein complex that forms on the SRE within 2 min following insulin, phorbol ester, or other growth factor treatment. Formation of this novel complex, called band 3, occurred rapidly and transiently, with a time course parallel to the induction of c-fos transcription. Band 3 also formed with gamma-actin and zif268/3 SRE probes. Methylation and carboxy ethylation interference analysis, as well as extensive SRE mutagenesis, suggest that only the SRF directly contacts the SRE in forming band 3. Formation of this novel complex appears to involve protein-protein interactions between SRF and other nuclear protein(s) that may play a role in growth factor stimulation of c-fos transcription.

3T3 Cells↗
PubMed1993

LC studies on the potential interaction of paraben preservatives with sorbitol and glycerol.

Pharmaceutical formulations often contain one or more paraben preservatives in conjunction with a polyol such as sorbitol or glycerol. In one of these experimental formulations a number of unknown polar peaks have been detected near the solvent front by reversed-phase LC. These degradation products were not attributable to the active drug component or a hydrolysis product. The possibility of an interaction between the polyols and paraben preservatives has been explored using a three-variable, two-level, factorial design to determine the relative significance of the factors involved in the formation of these unknown peaks. The factors examined were pH, temperature and the ratio of polyol to paraben. This study has shown that pH and temperature are key factors affecting the formation of these unknown peaks. On the basis of these results suitable conditions can be suggested for minimizing the production of these unknown peaks. It seems clear that a number of pharmaceutical formulations containing a polyol and a paraben would present potential problems for assay validation on storage owing to the formation of these degradation products, particularly if the drug component is polar and elutes near the solvent front.

Chromatography, Liquid↗
PubMed1992

Percutaneous transluminal angioplasty for transplant renal artery stenosis.

A recent report has challenged the efficacy and safety of percutaneous transluminal angioplasty (PTA) for the treatment of transplant renal artery stenosis (TRAS). From January 1983 to December 1990, 24 PTA procedures were performed for TRAS in 18 patients. The stenoses were anastomotic in two cases, in the main renal artery in 14, and segmental in eight. After PTA, the residual stenosis was less than 20% in 14 (58%), 20%-50% in four (17%), and greater than 50% in six (25%). The mean diastolic blood pressure decreased from 106 mm Hg 1 day prior to PTA to 82 mm Hg 1 day after PTA. Long-term follow-up mean diastolic blood pressure (at 2-32 months) was 93 mm Hg (P less than .01). Eleven of the 18 patients (63%) had a 10% or greater reduction in diastolic blood pressure on long-term follow-up. Major complications occurred in two patients; one groin hematoma required surgical evacuation, and one polar infarct led to hypertension that was difficult to control. No surgical revisions of the transplant renal artery were necessary. The authors' data indicate that PTA should remain the treatment of choice for nonanastomotic TRAS.

Adult↗
PubMed1991

Contradictory correlations between derived scales.

In a clinical trial one scale of pain relief is scored backwards relative to another (high on one corresponding to low on the other), with a consequent large negative correlation. But two derived scales of total pain, obtained by multiplying average pain relief on each scale by duration of pain (common to both pain relief measurements) gave an almost zero correlation. This apparent contradiction is explained by the inverse relationship between the pain relief scales and the large differences in duration of pain experienced by the patients.

Clinical Trials as Topic↗
PubMed1990

Percutaneous treatment of urine leaks in renal transplantation patients.

The data on post-renal transplantation urine leaks in 23 patients were retrospectively reviewed to assess the role of percutaneous urine-diverting procedures in their treatment. The leaks were confirmed by means of antegrade pyelography, and either a nephrostomy catheter or a nephroureteral stent was placed. Nephrostography was performed frequently to evaluate leak closure. Urinary diversion was continued for an average of 68 days. Leak closure was documented in 20 of 23 (87%) cases. In four patients, concomitant infection or multiorgan failure precluded adequate therapy. One patient developed a ureteral stricture after the urine-diverting procedure and required surgical correction. The results suggest that percutaneous urine-diverting procedures are a definitive treatment for post-renal transplantation urine leaks.

Adult↗
PubMed1989

Reaction of 3-dehydroecdysone with certain n.m.r. solvents.

Synthetically prepared 3-dehydroecdysone shows by n.m.r. spectroscopy a mixture of two and three components in 2H2O and [2H4]methanol respectively; only 3-dehydroecdysone is indicated in [2H5]pyridine. Although 3-dehydroecdysone is the sole component in [2H5]pyridine, it represents only 62% and 55% in 2H2O and [2H4]methanol respectively. Evidence indicates that the other component in 2H2O is a 3-[2H2]hydrate of 3-dehydroecdysone, and that in [2H4]methanol the other two components are isomeric [2H3]hemiacetals of 3-dehydroecdysone.

Ecdysone↗
PubMed1989

Effects of potential inhibitors on Brugia pahangi in vitro: macrofilaricidal action and inhibition of microfilarial production.

A series of compounds that apparently disrupt hormonally regulated processes in insects have been examined for effects on the viability and microfilarial production of adult Brugia pahangi cultured in vitro. The azasteroids, 25-azacoprostane and 25-azacholestane, inhibited the production of microfilariae at 5 ppm, the former also exhibiting macrofilaricidal activity at this concentration. The brassinosteroids examined inhibited microfilarial production at 5 ppm but did not affect worm viability. Azadirachtin also proved to be a significant inhibitor of microfilarial release without effect on worm motility or viability. Of all the compounds tested, the non-steroidal amines appeared to be the most promising as potential filaricides, several of them proving to be macrofilaricidal at 1 ppm and affecting microfilarial production at even lower concentrations.

Amines↗
PubMed1989

Decreased pulmonary distensibility in fibrosing alveolitis and its relation to decreased lung volume.

The relation between pulmonary distensibility, lung volume, and elastic recoil pressure was examined in 45 patients (38 men) with cryptogenic fibrosing alveolitis (mean age 61 (SD 14) years). Exponential analysis of static pressure-volume data obtained during deflation of the lungs gave the exponent K, an index of the distensibility of the remaining inflatable lung tissue. Total lung capacity (TLC) was measured in a body plethysmograph or by nitrogen washout. The results were compared with values obtained in 147 healthy subjects (95 men), of mean age 39 (SD 16) years. Fibrosing alveolitis decreased K by 0.62 (SEM 0.04) kPa-1. This decrease was approximately equal to 2 SD of the regression of log K on age in healthy subjects. TLC was decreased to a mean of 70% (SD 14%) predicted in the patients with fibrosing alveolitis. Lung recoil pressure at maximum inspiration was about twice the expected value and regression analysis showed that most of this increase was related to the decreased K rather than to the decreased TLC. In the men with fibrosing alveolitis the regression of height standardised TLC (TLC/Ht3) on K was significant (p less than 0.02); the regression slope was similar to that for 95 healthy men, but was displaced to a smaller lung volume. The dependence of TLC/Ht3 on K is consistent with the close relation between K and peripheral airspace size found in normal lungs. In fibrosing alveolitis decreased pulmonary distensibility probably reflects a decrease in airspace size, whereas most of the decrease in lung volume reflects the loss of inflatable tissue in the fibrotic process.

Aged↗
PubMed1989

Rapid resolution of acute cor pulmonale with recombinant tissue plasminogen activator.

A case of massive pulmonary embolism complicated by acute cor pulmonale and shock is presented. The IV administration of recombinant tissue-type plasminogen activator (rt-PA) was associated with prompt reversal of clinical, ECG, and nuclear radiographic findings. The role of thrombolytic therapy with rt-PA for massive pulmonary embolism associated with hemodynamic decompensation deserves further investigation.

Acute Disease↗
PubMed1989

Evaluation of cardiopulmonary devices on chest radiographs: digital vs analog radiographs.

We compared digital and analog radiographs of the chest for use in detecting and evaluating a variety of cardiopulmonary devices in 40 patients. The devices included 23 endotracheal tubes, 21 Swan-Ganz catheters, 14 central venous pressure catheters, 11 prosthetic valves, 10 chest tubes, six pacemaker wires, and five intraaortic balloon pumps. Each patient had at least one device, with a maximum of five devices (average, 2.3). Forty digital/analog film pairs were compared by five radiologists, who assigned confidence levels for various judgments about each device. The results showed that there were no statistically significant differences in the identification of the devices except for prosthetic valves (all valves were detected on digital radiographs, compared with 62% on analog radiographs). The devices were detected on 96% of the digital radiographs and 90% of the analog radiographs. Although digital and analog radiographs were comparable for detection of most devices, the digital radiographs allowed greater confidence in the identification of the devices and in the identification of the tip and course of Swan-Ganz and central venous pressure catheters.

Catheterization↗
PubMed1987

A sampling study of bedside nursing activity in a cardiac surgical intensive care unit. Part 2. The effect of time and shift on the nursing workload.

For a selected group of 17 patients following cardiac surgery, 33 discrete elements of nursing workload have been defined, and the nurse's bedside activities logged at 1 min intervals throughout the 24 h immediately following the patient's return from the operating theatre. It is possible to identify three broad types of activity undertaken by the bedside nurse; technical nursing care (Type 1), intermittent nursing care (Type 2), and the balance of the nurse's time, largely concerned with observation and liaison with other staff--learning activities (Type 3). The time devoted to technical nursing care reduces significantly over the patient's first 24 h in the ward. On the other hand the time devoted to intermittent nursing care and learning activities is shown to be shift dependent. The effect of the efficient utilisation of computer technology is estimated, and it is demonstrated that the implementation of such technology would result in the expansion of the time available for the nurse to observe the patient. The potential benefits and drawbacks of this are discussed.

Adult↗