N-acetyl-L-aspartyl-L-glutamate peptidase-like 2 is overexpressed in cancer and promotes a pro-migratory and pro-metastatic phenotype

N-acetyl-L-aspartyl-L-glutamate peptidase-like 2 (NAALADL2) is a member of the glutamate carboxypeptidase II family, best characterized by prostate-specific membrane antigen (PSMA/NAALAD1). Using immunohistochemistry (IHC), we have shown overexpression of NAALADL2 in colon and prostate tumours when compared with benign tissue. In prostate cancer, NAALADL2 expression was associated with stage and Grade, as well as circulating mRNA levels of the NAALADL2 gene. Overexpression of NAALADL2 was shown to predict poor survival following radical prostatectomy. In contrast to PSMA/NAALAD1, NAALADL2 was localized at the basal cell surface where it promotes adhesion to extracellular matrix proteins. Using stable knockdown and overexpression cell lines, we have demonstrated NAALADL2-dependent changes in cell migration, invasion and colony-forming potential. Expression arrays of the knockdown and overexpression cell lines have identified nine genes that co-expressed with NAALADL2, which included membrane proteins and genes known to be androgen regulated, including the prostate cancer biomarkers AGR2 and SPON2. Androgen regulation was confirmed in a number of these genes, although NAALADL2 itself was not found to be androgen regulated. NAALADL2 was also found to regulate levels of Ser133 phosphorylated C-AMP-binding protein (CREB), a master regulator of a number of cellular processes involved in cancer development and progression. In combination, these data suggest that changes in expression of NAALADL2 can impact upon a number of pro-oncogenic pathways and processes, making it a useful biomarker for both diagnosis and prognosis.

scAAV-mediated gene transfer of interleukin-1-receptor antagonist to synovium and articular cartilage in large mammalian joints

With the long-term goal of developing a gene-based treatment for osteoarthritis (OA), we performed studies to evaluate the equine joint as a model for adeno-associated virus (AAV)-mediated gene transfer to large, weight-bearing human joints. A self-complementary AAV2 vector containing the coding regions for human interleukin-1-receptor antagonist (hIL-1Ra) or green fluorescent protein was packaged in AAV capsid serotypes 1, 2, 5, 8 and 9. Following infection of human and equine synovial fibroblasts in culture, we found that both were only receptive to transduction with AAV1, 2 and 5. For these serotypes, however, transgene expression from the equine cells was consistently at least 10-fold higher. Analyses of AAV surface receptor molecules and intracellular trafficking of vector genomes implicate enhanced viral uptake by the equine cells. Following delivery of 1 × 10(11) vector genomes of serotypes 2, 5 and 8 into the forelimb joints of the horse, all three enabled hIL-1Ra expression at biologically relevant levels and effectively transduced the same cell types, primarily synovial fibroblasts and, to a lesser degree, chondrocytes in articular cartilage. These results provide optimism that AAV vectors can be effectively adapted for gene delivery to large human joints affected by OA.

Construction of a virtual EPR and automated contextual linkage to multiple sources of support information on the Oxford Clinical Intranet

We have used internet-standard tools to provide access for clinicians to the components of the electronic patient record held on multiple remote disparate systems. Through the same interface we have provided access to multiple knowledgebases, some written locally and others published elsewhere. We have developed linkage between these two types of information which removes the need for the user to drill down into each knowledgebase to search for relevant information. This approach may help in the implementation of evidence-based practice. The major problems appear to be semantic rather than technological. The intranet was developed at low cost and is now in routine use. This approach appears to be transferable across systems and organisations.

Serum S-100 protein concentration after cardiac surgery: a randomized trial of arterial line filtration

INTRODUCTION

Embolization of gaseous and particulate matter is incriminated in the neuropsychological morbidity of CPB and can be reduced by membrane oxygenators and arterial line filtration. It is not known if the use of arterial line filtration in conjunction with membrane oxygenators might have an additive effect in reducing cerebral injury.

METHODS

Forty patients undergoing elective coronary artery surgery were prospectively randomized to a 43 microns heparin coated arterial line filter (Cobe Sentry) or to no filtration (control group). All operations were performed by one surgeon (DPT) using intermittent ischaemia with nonpulsatile CPB, a COBE CML membrane oxygenator and alpha-stat paCO2 management. Flow rates were maintained between 2.0 and 2.4 l-1 m2 per min with a perfusion pressure of 50-80 mmHg and a systemic temperature of 34 degrees C. Cerebral injury was defined by careful neurological examination and serial measurement of the serum concentration of S-100 protein (a highly specific astroglial cell derivative, elevated serum levels of which correlate with proven cerebral injury).

RESULTS

There was no difference [mean (S.D.)] in the control and filter groups with respect to age [61(9) vs. 62(9) years], ejection fraction, number of grafts [2.8(0.6) vs. 2.6(0.7)] or CPB times [55(19) vs. 57(18) min]. Preoperatively, no patient had detectable S-100. In the postoperative period 23 of 40 patients (58%) showed elevated S-100 levels. At 1, 5 and 24 h the respective number of patients in the control and filter groups with elevated S-100 was (14 vs. 9), (4 vs. 0), (4 vs. 0)) (P < 0.05). No patient had overt cerebral injury.

CONCLUSIONS

This study suggests that (i) subclinical cerebral injury is common (58% of patients in this study) even after apparently uncomplicated surgery with short CPB times; (ii) serum S-100 protein is a valuable marker for investigating potentially cerebral protective innovations during CPB; and (iii) arterial line filtration significantly reduces but does not eliminate cerebral injury.

Comparison of serum S-100 beta levels during CABG and intracardiac operations

BACKGROUND

The risk of overt and subtle cerebral injury may be higher in intracardiac operation (ICO) rather than coronary artery bypass grafting (CABG). S-100 protein is a specific astroglial protein whose serum level increases after cerebral injury. Elevated serum levels of S-100 have been detected after adult cardiac operations and correlated with neurologic injury.

METHODS

The level of S-100 protein was measured serially over 24 hours in 40 patients (27 undergoing aortic valve replacement, 9 mitral valve replacement, 4 closure of atrial septal defect) undergoing ICO and 20 patients undergoing CABG.

RESULTS

The groups were similar with respect to age and cardiopulmonary bypass times. The S-100 level was not elevated before operation in any patient. Peak S-100 levels were reached at skin closure, when 35 of the ICO patients (88%) and 13 of the CABG patients (65%) had elevated S-100 levels. At skin closure peak S-100 levels were significantly greater in the ICO group (median [interquartile range], 0.76 [0.44-1.16] versus 0.3 [0-0.55] microgram/L; p < 0.01). At 5 hours S-100 levels were still elevated in 22 patients in the ICO group compared with 1 patient in the CABG group (p < 0.01), and at 24 hours 17 ICO patients had persistently elevated S-100 levels in comparison with 2 in the CABG group (p < 0.01). One valve patient had a stroke 24 hours after operation accompanied by a secondary increase in the S-100 level. There was no significant difference in postoperative S-100 levels between 5 patients in the ICO group with a prior history of stroke and those without. The peak S-100 level correlated with patient age (r = 0.59; p < 0.001) but not with the duration of cardiopulmonary bypass or core temperature during the operation.

CONCLUSIONS

Intracardiac operation results in a significantly greater elevation in S-100 levels than CABG. Elevated S-100 levels correlate with increasing patient age but not with the duration of cardiopulmonary bypass or intraoperative core temperature. These findings raise the possibility that ICO patients may be more vulnerable to even subtle levels of cerebral injury than CABG patients.

Using decision analysis to compare policies for antenatal screening for Down's syndrome

OBJECTIVE

To compare different screening policies for Down's syndrome across a broad range of outcomes, using decision analysis, with particular reference to the role of maternal serum testing.

DESIGN

A decision tree was used to combine data from local sources and the medical literature to predict the likely frequency of several outcomes. Sensitivity analyses were used to test the robustness of the conclusions drawn.

SETTING

Oxfordshire Health Authority.

MAIN OUTCOME MEASURES

Live births with and without Down's syndrome; miscarriages with Down's syndrome; cases of Down's syndrome detected antenatally; amniocenteses performed (and associated miscarriages); direct NHS screening costs; number of women offered screening.

RESULTS

Screening policies for Down's syndrome that include serum testing can produce better population outcomes than programmes that do not. Each option for screening for Down's syndrome that we considered had significant drawbacks. In Oxfordshire, offering serum testing to women of all ages would prevent the birth of approximately one more baby with Down's syndrome per year than would a policy of screening for women aged 30 years or more. The cost of preventing this one extra Down's birth would be one or two normal babies lost after amniocentesis, 4500 blood tests for young women (with the associated anxiety and counselling), approximately 200 false positive serum test results and amniocenteses (with the associated anxiety and distress), and 90,000 pounds for the extra tests, counselling, and amniocenteses. Opinions are divided as to which policy is the better option for the population.

CONCLUSIONS

Decision analysis is a useful tool for determining the likely consequences of different policy options across a broad range of outcomes. This focuses debate and decision making on outcomes of care, which in turn makes it clear that the choice of screening programme for Down's syndrome depends on the relative importance ascribed to the different outcomes. If individuals' values vary widely it may be impossible to find one screening policy that meets the needs of all pregnant women.

Urinary excretion and clearance of insulin in diabetic and normal children and adolescents

Seventy-two diabetic (38 males) and 86 normal (41 males) children provided timed overnight urine collections. Fourteen of the diabetic and 33 of the normal children had concurrent overnight plasma insulin profiles. Urinary insulin clearance in the diabetic subjects was compared with excretion of albumin, growth hormone, retinol-binding protein, and N-acetyl-beta-D-glucosaminidase. In the normal subjects, urinary insulin excretion correlated with mean overnight plasma levels in the boys (r = 0.82, p < 0.001) but not in the girls (r = 0.32), and varied with puberty stage in the boys. Insulin clearance was greater in boys than girls during puberty, and fell in both sexes with advancing puberty. Insulin excretion was greater in diabetic than normal children in both sexes at all puberty stages. Insulin clearance was also greater in diabetic than normal subjects (1.05 +/- 0.1 ml min-1 1.73 m-2 vs 0.48 +/- 0.05 ml min-1 1.73 m-2, p < 0.001). Insulin excretion as a percentage of the filtered load was also greater in diabetic than normal subjects (1.9 +/- 0.27% vs 0.85 +/- 0.09%, p < 0.01). In the diabetic children, there was a correlation between urinary insulin and growth hormone excretion (r = 0.52, p < 0.02), and retinol-binding protein in those (n = 10) with higher retinol binding protein excretion (r = 0.76, p = 0.01). The value of urinary insulin excretion as a measure of free plasma insulin levels in normal and diabetic children may be limited by sex differences in renal insulin clearance, and by proximal renal tubular dysfunction in children with diabetes.

Prevalence and outcome of renal impairment at prostatectomy

Of 382 patients undergoing prostatectomy in Oxford in 1985 the prevalence of renal impairment (defined as plasma urea > 14 mmol/l or plasma creatinine > 200 mumol/l) was 8%; prostatectomy patients had significantly higher plasma ureas than age-matched patients undergoing herniorrhaphy and cholecystectomy in the same hospitals in the same year. A review of the case records of men with renal impairment showed that case history could not predict renal impairment. Although few case notes gave follow-up information, it was evident from the information available that recovery of renal function after prostatectomy did not occur invariably. Renal impairment in men undergoing prostatectomy represents substantial and unrecognised morbidity.

Porcine thyroid cytosolic, latent alkaline ribonuclease: resistance to protein denaturants

1. A ribonuclease isolated from porcine thyroid cytosol using phenol: sodium dodecylsulfate treatment was associated with RNA and identical to latent alkaline ribonuclease. 2. Distribution of activity between aqueous and phenolic phases depended on pH, RNA, and ribonuclease inhibitor. 3. The ribonuclease was totally resistant to urea, guanidinium: HCl, chloroform:isoamyl alcohol, ethanol, heating at 100 degrees C for 10 min or at 80 degrees C plus 100 mM NaCl. It was highly resistant to hydrolysis by proteinase K except in the presence of detergent. 4. The extreme stability and other properties of latent alkaline ribonuclease could be the result of its association with RNA.

Measurement of glomerular filtration rate in homozygous sickle cell disease: a comparison of 51Cr-EDTA clearance, creatinine clearance, serum creatinine and beta 2 microglobulin

Glomerular filtration rates (GFR) were measured with 51Cr-EDTA in 38 patients (aged 40-75 years) with homozygous sickle cell disease and compared with serum beta 2 microglobulin concentrations in 38 patients and with creatinine clearance in 21 patients. GFR estimated with 51Cr-EDTA was closely correlated with single serum creatinine measurements and the inverse of serum beta 2 microglobulin. Creatinine clearance was also found to be correlated, but values were, on average, 32% below those obtained by the 51Cr-EDTA method, and this difference was significant. It is concluded that measurements of beta 2 microglobulin, single serum creatinine, and creatinine clearance are valuable indicators of GFR in homozygous sickle cell disease. Measurement of beta 2 microglobulin was a useful and reliable method of estimating GFR from single plasma measurements and is therefore a useful means of screening the population.

Inhibition by salicylates of urea synthesis by isolated rat hepatocytes and citrulline synthesis by isolated rat mitochondria: an effect independent of uncoupling

1. Acetylsalicylate and salicylate inhibited urea synthesis by isolated rat hepatocytes and citrulline synthesis by isolated rat mitochondria. The effects were dose-dependent and occurred at drug concentrations seen in salicylate induced hepatoxicity. 2. Although ATP concentration was decreased in the hepatocytes the effect of the salicylates on citrulline synthesis remained after treatment with oligomycin and carbonyl cyanide m-chlorophenyl hydrazone. This suggests that the effect is independent of uncoupling of oxidative phosphorylation. 3. This in vitro inhibition of urea synthesis by salicylates is similar to that produced by valproate and endogenous organic acids, which are also associated with hyperammonaemic clinical toxicity, and is a possible mechanism for the action of salicylates in the hyperammonaemia of Reye's syndrome.

Effect of partial ornithine carbamoyltransferase deficiency on urea synthesis and related biochemical events

The biochemical response to an intravenous alanine load of 0.25 g/kg was studied in nine adult female relatives of children with ornithine carbamoyltransferase deficiency. Six were classified as affected by partial deficiency and three as unaffected. The plasma ammonium concentration showed no change after the alanine load in the unaffected group, but marked increases occurred in all but one of the affected groups. The maximum rate of urea synthesis after the alanine load was decreased by 37% (P = 0.02) and delayed by 43% (P = 0.02) in the affected group. In the affected group a low rate of urea synthesis was associated with high urinary orotate excretion, high maximum plasma ammonium concentration and delay in the time taken to reach the maximum rate of urea synthesis (Kendall concordance W = 0.55, P less than 0.05). The effects of a higher dose of alanine and of oral protein were compared. The alanine load of 0.25 g of alanine/kg body weight was shown to provide an adequate stimulus to urea synthesis with a more rapid return of ammonium concentration to the pre-load level than with the protein load. The implication of these results in determining the distribution of flux control of urea synthesis, the discrepancy between them and predicted results and the necessary modifications to quantitative simulations are discussed.

Validation of a method for measuring the short-term rate of urea synthesis after an amino acid load

The response of the plasma concentration of urea to the oral and intravenous administration of alanine was studied in healthy adult humans. The instantaneous rate of urea synthesis was calculated by using a model-dependent procedure. The errors in this procedure were calculated and it was shown that analytical precision and sampling frequency, and the estimates of the distribution volume and elimination fluxes, were adequate to determine the synthesis parameters. A direct test of the compartmental model was made by the intravenous injection of exogenous urea. The one-compartment model with first-order elimination gave a good fit to the experimental results at times greater than 8 min after the injection. Both oral and intravenous loads of alanine had dose-dependent effects on the rate of urea synthesis. There was no evidence of a limit to the maximum possible rate of urea synthesis in these experiments and the values obtained were similar to published results for different stimuli and methods of measurement. The rate of synthesis increased more rapidly after intravenous loads and subjective side-effects were less severe. The intravenous administration of alanine appears to be a suitable stimulus for urea synthesis.

Determination of the rate of urea synthesis from serial measurements of plasma urea concentration after an alanine load: theoretical and methodological aspects

A method is described by which the rate of synthesis of urea can be calculated from the change of plasma concentration of urea after an alanine load. The results can be expressed in terms of f, the maximum increase in the rate of urea synthesis, and t, the time at which urea synthesis reaches its maximum. These parameters are calculated by an algebraic curve-fitting technique which is suitable for a desk computer. The method removes the need for isotopic analysis and urine collections. The effect of various errors and experimental conditions on the calculated synthesis parameters is investigated.

Haemorrhagic shock and encephalopathy: a new syndrome with a high mortality in young children

In the past year, ten infants have been admitted to hospital with a new or previously unrecognised disorder, characterised by an acute onset of encephalopathy, fever, shock, watery diarrhoea, severe disseminated intravascular coagulation, and renal and hepatic dysfunction. Seven of the infants died. No specific causative agent has been identified, but preliminary studies suggest that the pathophysiology of the disease may involve release of proteolytic enzymes (such as trypsin) into the circulation, with destruction of the microcirculation.

Breathing in man during steady-state exercise on the bicycle at two pedalling frequencies, and during treadmill walking

1. The breathing pattern, that is the changes in tidal volume (VT), and in inspiratory (TI) and expiratory (TE) durations, has been studied as ventilation increases in exercise. 2. Five healthy subjects were studied in steady-state exercise on a bicycle ergometer, breathing air, at two speeds of pedalling and at six different loads. The pattern was recorded for single breaths. Two of the subjects were also studied while walking on a treadmill with four combinations of speed and gradient. 3. In bicycle exercise, as the CO2 output increased mean VT increased, and mean TI and TE decreased, the absolute decrease in TI being small. The pedalling speed did not affect these relationships. 4. Individual breath durations showed no tendency to group around multiples of the period of rotation of the pedals. 5. In treadmill exercise, no clear influence of stride rate on respiratory rate could be found. The pattern was similar to that found in bicycle exercise. Again no grouping could be found. 6. No evidence of an effect of frequency of limb movement on breathing pattern in submaximal exercise has been found. The selection of breathing pattern seems to be unrelated to the nature of the stimulus but closely geared to the metabolic needs of the body.

Mean and breath-by-breath pattern of breathing in man during steady-state exercise

1. The breathing pattern, that is the relation between tidal volume (VT) and the inspiratory (TI) and expiratory (TE) durations, has been studied for individual breaths (forty in each steady state). 2. Five healthy subjects were studied in steady-state exercise on a bicycle ergometer breathing air; three of them were also studied in hypercapnia, at rest and during exercise, and two of them also during exercise on a treadmill. 3. Tidal volume and respiratory frequency both increased with work load. The increase in frequency was largely due to a progressive decrease in TE; TI also decreased. 4. At any constant level of respiratory drive (constant work load or chemical load) VT was positively correlated with both TI and TE in more than 95% of cases. 5. A simple model of the respiratory cycle which fits both the observed mean and breath-by-breath patterns and which involves no new assumptions is presented.