Vasopressin-induced changes in splanchnic blood flow and hepatic and portal venous pressures in liver resection.

BACKGROUND: To minimize blood loss during hepatic surgery, various methods are used to reduce pressure and flow within the hepato-splanchnic circulation. In this study, the effect of low- to moderate doses of vasopressin, a potent splanchnic vasoconstrictor, on changes in portal and hepatic venous pressures and splanchnic and hepato-splanchnic blood flows were assessed in elective liver resection surgery. METHODS: Twelve patients were studied. Cardiac output (CO), stroke volume (SV), mean arterial (MAP), central venous (CVP), portal venous (PVP) and hepatic venous pressures (HVP) were measured, intraoperatively, at baseline and during vasopressin infusion at two infusion rates (2.4 and 4.8 U/h). From arterial and venous blood gases, the portal (splanchnic) and hepato-splanchnic blood flow changes were calculated, using Fick's equation. RESULTS: CO, SV, MAP and CVP increased slightly, but significantly, while systemic vascular resistance and heart rate remained unchanged at the highest infusion rate of vasopressin. PVP was not affected by vasopressin, while HVP increased slightly. Vasopressin infusion at 2.4 and 4.8 U/h reduced portal blood flow (-26% and -37%, respectively) and to a lesser extent hepato-splanchnic blood flow (-9% and -14%, respectively). The arterial-portal vein lactate gradient was not significantly affected by vasopressin. Postoperative serum creatinine was not affected by vasopressin. CONCLUSION: Short-term low to moderate infusion rates of vasopressin induced a splanchnic vasoconstriction without metabolic signs of splanchnic hypoperfusion or subsequent renal impairment. Vasopressin caused a centralization of blood volume and increased cardiac output. Vasopressin does not lower portal or hepatic venous pressures in this clinical setting.

Microbiological quality of Icelandic cooked-peeled shrimp (Pandalus borealis).

Iceland is a major producer of cold water shrimp, Pandalus borealis. In recent years considerable attention has been given to improve hygiene in the factories producing cooked, peeled and frozen shrimp. To keep track of the bacteriological status of the end product, shrimp from most of the factories is routinely analysed bacteriologically by the request of shrimp exporters. This paper reports on the results of a bacteriological analysis of 7913 samples of shrimp from 26 Icelandic factories over a 6-year period. The results showed that the geometric mean of APC (at 35 degrees C) was 1718 per g and 57% of the samples had APC under 1000 per g. Some 70% of the samples had less than one coliform per g and 99.9% of the samples had less than one faecal coliform per g. Staphylococcus aureus was detected in less than 0.2% of the samples. The results show improvement in bacterial profiles, mainly total coliforms, over the 6-year period. Overall, the results show acceptable bacterial numbers in the finished product, indicating a high level of hygiene. Listeria spp. were, however, found in 270 of 3331 samples examined or 8.1%. Species identification was done on 49 of the 270 positive samples. The proportion of L. monocytogenes was found to be 26.5%.

Biopreservation of Brined Shrimp (Pandalus borealis) by Bacteriocins from Lactic Acid Bacteria.

In brined shrimp (ca. 3% NaCl), the effects of three different lactic acid bacteria bacteriocins (crude [6.54 x 10(sup10) U of bacteriocin activity {BU}/g] and purified [8.13 x 10(sup23) BU/g] nisin Z, carnocin UI49 [2.32 x 10(sup4) BU/g], and crude bavaricin A [2.78 BU/g]) on bacterial growth and shelf life were compared with those of a benzoate-sorbate solution (0.1% each [wt/wt]) and a control with no preservatives. The shelf life of shrimp subjected to the control treatment was found to be 10 days. Carnocin UI49 did not extend the shelf life, while crude bavaricin A (a cell-free supernatant of Lactobacillus bavaricus MI 401) resulted in a shelf life of 16 days, as opposed to 31 days with nisin Z for both its crude and purified forms. The benzoate-sorbate solution preserved the brined shrimp for the whole storage period (59 days). In the control, carnocin UI49, and crude bavaricin A treatments, a gram-positive flora dominated towards the end of the storage period while in the nisin Z treatment a gram-negative flora was more pronounced.

Evaluation of a predictive model for the shelf life of cod (Gadus morhua) fillets stored in two different atmospheres at varying temperatures.

The shelf life of fish and food in general is difficult to predict especially if stored at varying temperatures. Shelf life models were constructed (Einarsson, 1992) for cod fillets stored at constant temperatures. The aim of this study was to evaluate if these models could be used to predict spoilage and bacterial growth in cod fillets stored in air and modified atmosphere at constant and varying temperatures. Fresh fillets were packed and stored at constant or varying temperatures between -2 degrees C and 5 degrees C. Samples were taken at regular intervals for bacteriological and sensory evaluation. The results showed that fish stored at +0.6 degrees C in air had a shelf life (assessed by sensory analysis) of 11 days which is close to what could be expected and predicted. The increase in bacterial number observed was generally less than predicted. For fish fillets, stored in air at +5 degrees C for 3 days, then at +0.6 degrees C for 3 days and finally at -2 degrees C, the shelf life was found to be 7 days which was in good agreement with the predicted shelf life. The shelf life of fillets stored at same the temperatures in modified atmosphere was found to be 9 days but by prediction 11 to 12 days. The models for predicting changes in sensory score were more accurate than those predicting changes in bacterial numbers.

Inhibitory mechanisms of Maillard reaction products.

In order to determine the inhibitory mechanism of antibacterial Maillard reaction products (MRP), heated mixtures containing arginine and xylose (AX) or histidine and glucose (HG) were studied for their mutagenic effect, using the Salmonella mutagenic test system ('Ames test'), with regard to their effect on the uptake of serine, glucose and oxygen and for their effect on iron solubility. It was found that the MRPs tested had little or no mutagenic effect, while an inhibitory effect on the uptake of serine, glucose and oxygen was observed. The MRPs also had an effect on the solubility of iron in nutrient broth and in phosphate buffer. While the AX mixture reduced the solubility of iron it was increased by the HG mixture. The reduction of iron solubility in the presence of the AX mixture was much greater at pH 8 than at pH 5. The present data suggest that the antibacterial effect of the MRPs tested is primarily due to the interaction between MRPs and iron, resulting in reduced oxygen uptake.

Niacin assay by monitoring changes in electrical conductance caused by microbial growth.

A computerized Malthus 128 H Growth Analyser was used to determine the changes in conductance produced by growth of a niacin-dependent strain of Lactobacillus plantarum ATCC 8014 in different concentrations of niacin in the growth medium. Changes in conductance varied linearly with the niacin concentration in the range 5-50 ng/ml. The time required to complete a test is inversely related to the inoculum size, and results can be obtained after 6 h.