Impact of laparotomy and liver resection on the peritoneal concentrations of fibroblast growth factor 2, vascular endothelial growth factor and hepatocyte growth factor

PURPOSE

Some data have suggested that major surgery is associated with the post-operative growth of residual tumour masses but the mechanism of this is unknown. This study was designed to determine the relationship between intraperitoneal (IP) cytokine levels, and laparotomy in benign and malignant settings.

METHODS

Intraperitoneal fluid specimens were obtained at the start and at the end of laparotomy in patients with benign conditions (n=10) and in others undergoing resection of hepatic metastases from colorectal cancer (n=10). Using ELISA the concentration of the angiogenic cytokines, HGF, VEGF-A, VEGF-C, VEGF-D and FGF-2 was determined.

RESULTS

The data show that in 16 of 20 patients there was a significant increase (P=0.006) in the IP concentration of hepatocyte growth factor (HGF) but not in the other growth factors by the end of the operation. The mean increase in HGF concentration was 821.5 pg/ml (95% CI: 11.0-6,426.0). Neither the groups (malignant and non-malignant) nor the length of operation correlated with greater or lesser increases in HGF.

CONCLUSION

The observation that the increase in HGF occurred in both the cancer and non-cancer groups suggests that it is the surgery rather than the disease that is associated with the increased cytokine concentration. As HGF is a potent endothelial, epithelial and mesenchymal mitogen the data highlight HGF as a potential target for anti-cancer treatments in the peri-operative period. However, investigators should closely monitor wound healing as this may be compromised by this new class of drugs.

A falling HbA1c is not necessarily an indicator of improving diabetes control

The finding of a very low haemoglobin A1c (HbA1c) (1.4%) in a diabetic patient with fairly high plasma glucose levels prompted haematological investigations, which revealed auto-immune haemolysis and a Hb concentration of 7.7 g/L. Following treatment, both Hb and HbA1c concentrations increased roughly in parallel until, 4 months later, Hb was 13.8 g/L, HbA1c 5.2% and plasma glucose was 6.8 mmol/L. This case illustrates that a falling HbA1c cannot always be attributed to improving glucose control in diabetic patients.

Age does not influence levels of HbA1c in normal subject

To resolve whether haemoglobin A1c(HbA1c) levels in normal subjects increase with age, we measured HbA1c in 399 patients undergoing routine oral glucose tolerance test (OGTT). The OGTT results categorized the patients into 127 normal, 94 impaired glucose tolerance (IGT) and 178 diabetic. None of these groups showed a significant correlation between HbA1c and age and we cannot, therefore, see a need for age-specific reference ranges for HbA1c. Some of the confusion in the literature may have arisen from less rigorous categorization of subjects than we used, resulting in the inclusion of some individuals with IGT or diabetes in the 'normal' groups of other studies. The prevalence of such abnormality would be expected to be greater amongst older subjects, falsely suggesting a correlation between HbA1c and age, and we were able to demonstrate this with our own data when insufficiently rigorous criteria were applied for the selection of normal subjects.

The relative merits of haemoglobin A1c and fasting plasma glucose as first-line diagnostic tests for diabetes mellitus in non-pregnant subjects

HbA1c was measured by high-performance ion-exchange chromatography in 401 non-pregnant patients undergoing oral glucose tolerance tests (OGTT). All those with HbA1c>6.2% (reference range 3.8-5.5%) had diabetic OGTT (sensitivity 41%, specificity 100%). Although a fasting plasma glucose (FPG) cut-off > or =7.0 mmol l(-1), as recommended by the American Diabetes Association (ADA), had greater sensitivity (78%), false positives (12%) limited its usefulness, so more diagnostic confidence could be placed in a positive HbA1c. In agreement with the ADA, we found FPG gave only slightly lower diabetes prevalence than the OGTT, but this masked a significant number of individual discrepancies (false positives and negatives) cancelling out each other. The new ADA category of impaired fasting glucose did not correlate well with impaired glucose tolerance. HbA1c is insufficiently sensitive as a direct substitute for the OGTT. A third of subjects diabetic on OGTT had normal HbA1c values, so it cannot exclude diabetes as currently defined, but HbA1c screening could make sufficient positive diagnoses to reduce our non-pregnant OGTTs by one-fifth. If a 'risk threshold' for diabetic complications could be applied to HbA1c, it could replace the OGTT as a more pragmatic diagnostic/prognostic test.

Fasting plasma glucose as a diagnostic indicator of diabetes mellitus

Among 233 patients referred for glucose tolerance test (GTT), 36.4% of 129 non-pregnant subjects were classified as diabetic, compared with only 2.9% of 104 pregnant subjects. Preliminary screening using a fasting plasma glucose upper cut-off of 7.0 mmol/l, above which the subject was classified as diabetic and a lower one of 4.4 mmol/l, below which he or she was considered normal, would have eliminated the need for 30% of GTTs and positively identified 60% of the diabetics in the non-pregnant group. Only one patient would have been significantly misclassified, possibly owing to inadequate fasting. However, little benefit would result from applying an upper cut-off to low-prevalence populations such as the pregnant group. Like other recent surveys, this study suggests that World Health Organisation diagnostic figures for fasting plasma glucose could be revised downwards to 7.0 mmol/l. Conversely, to be fairly certain that an individual is not diabetic, fasting plasma glucose must be below about 4.4 mmol/l.

Important characteristics of warning displays on alcohol containers

Four studies examined the federally mandated warning on alcohol containers, which is required by law to be "located in a conspicuous and prominent place." In all four studies few of the drinkers could recall the main parts of the warnings, even though the warning had been required on all alcohol containers for over two years. In Study 1, 44 adults looked at the warning on various beer containers and 77% thought that the warning was not conspicuous but could be made conspicuous through various changes, such as by printing the warning horizontally (parallel to the brand name) rather than vertically. In Study 2, 50 adults looked at the warning placed horizontally on one beer can and vertically on a similar can and rated the horizontal warning significantly more conspicuous. In Study 3, 44 adults spent several minutes in a simulated drinking atmosphere. Half the subjects had beer cans with a horizontal warning and half had a vertical warning. The subjects with the horizontal warning later showed significantly better awareness/recall of the warning. In Study 4, with 75 adult subjects in a bar, the half of the subjects prompted to notice the alcohol warning drank less thereafter in the bar than the other subjects. The findings of the series of studies suggest that the conspicuousness of health warnings on alcohol containers tends to influence their possible effectiveness.

An assessment of the effect of haematocrit on the HemoCue blood glucose analyser

The HemoCue blood glucose analyser was investigated with particular respect to its susceptibility to influence by the haematocrit of the blood specimen. The red cells and plasma of fresh blood samples were separated and then recombined in proportions to give a range of haematocrit values and the resulting specimens assayed for glucose. The HemoCue exhibited no appreciable influence of haematocrit. The instrument was easy to use, stable and had good precision (CV 1.8%). However, results tended to be a little higher than those produced by a conventional laboratory analyser on whole blood and it is understood that the factory calibration of newer HemoCue instruments has been modified to correct for this.

The effect of haematocrit on reagent strip tests for glucose

Four blood glucose reagent strips (BM-Test 1-44, Glucostix, Hypoguard GA, and Exactech), used in conjunction with measuring devices produced by the same manufacturer, were investigated with respect to the influence of haematocrit. The erythrocytes and plasma of fresh blood samples were separated, then remixed in different proportions to achieve a range of haematocrit values and the resulting specimens subjected to glucose assay. All the strip tests showed some influence of haematocrit, low haematocrits producing higher glucose results and vice versa, but some were much more affected than others. The Hypoguard GA was most affected and the BM-Test 1-44 least. In the worst case, glucose results differed by 49% from one end of the normal adult haematocrit range to the other.

The oral glucose tolerance test--an assessment of the quality of its performance

By means of a questionnaire, an attempt was made to assess the quality of performance and interpretation of the oral glucose tolerance test by laboratories participating in the UK External Quality Assessment Scheme for Clinical Chemistry. The results showed a general awareness of current recommendations in terms of both protocol for the test and criteria for interpretation of results, but some deficiencies were observed in both these areas and in some case deviations in protocol may have been sufficient to invalidate comparison of results with currently recommended criteria for interpretation of the test.

Minimisation of salicylate interference in the Glynn and Kendal paracetamol procedure

The Glynn and Kendal technique for plasma paracetamol assay was investigated in an attempt to eliminate its susceptibility to interference from salicylate. Modification of the nitrating reaction so as to produce milder conditions by omission of hydrochloric acid, reduction of nitrite concentration, and limiting the time of reaction to 2 minutes resulted in far less interference. A further improvement was achieved by reading at 450 nm. The proposed modification reduces the interference from a salicylate concentration of 100 mg/dl to the equivalent paracetamol concentration of 12 mg/l, compared with about 70 mg/l in the unmodified method.

Pathology measurements closer to the patient?

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Experiences with a regional quality control scheme for salicylate and paracetamol over a period of two years

The organisation of a regional quality control scheme for salicylate and paracetamol estimations in plasma is described. The results show considerable variation in both bias and precision between laboratories, with some overall improvement in performance during the second year of the scheme. No method can be singled out as producing better results than the others. The major factor seems to be the care with which the analyses are performed.