Effect of dipyridamole on microaggregate formation in the pump oxygenator

Breast cancer associated with neurofibromatosis type 1: a case series and review of the literature

INTRODUCTION

Neurofibromatosis type 1, also known as Von Recklinghausen's disease, is a rare neuroectodermal disease that mainly affects the skin and the nervous system. Patients with neurofibromatosis type 1 have a higher risk of developing various types of cancers, especially tumors derived from the embryogenic neural crest. However, its association with breast cancer has seldom been reported.

CASE PRESENTATION

We report the cases of three white Arabic women diagnosed with neurofibromatosis type 1, with a median age of 40-years-old (range: 39 to 43), who sought treatment at our centre for breast cancer.

CONCLUSIONS

The association between neurofibromatosis type 1 and breast cancer is uncommon. In our case series we readdress this association through a literature review.

Portosystemic shunt for the treatment of portal vein thrombosis following orthotopic liver transplantation

The efficacy of the portosystemic shunt operation for the treatment of portal vein thrombosis following orthotopic liver transplantation was demonstrated. From 1 July 1988 to 31 December 1991 42 portosystemic shunt operations were performed at our centre. In six of these cases portal vein thrombosis after orthotopic liver transplantation (OLT) was the indication for the procedure. All the patients retained adequate liver function but they demonstrated manifestations of significant portal hypertension, mainly variceal rebleeding. Two of the patients were children. Three patients underwent distal splenorenal shunt (DSRS), one mesocaval and one side-to-side splenorenal shunt and the last one side-to-side splenorenal shunt which was converted to DSRS 2 weeks later. All these patients were doing well after 30 months mean follow-up time without rebleeding or other signs of portal hypertension and none had so far required retransplantation.

Glucagon metabolism in normal subjects and in cirrhotic patients before and after portasystemic venous shunt surgery

The effect of portasystemic shunt surgery on basal immunoreactive glucagon (IRG) levels, metabolic clearance rate (MCR) and t 1/2 for glucagon decay, and basal systemic delivery rate (BSDR) of glucagon was investigated in paired studies in ten cirrhotic subjects. The degree of hepatocellular dysfunction and extent of portasystemic venous shunting was also recorded. Basal IRG levels were highest in the post-shunt (mean +/- SEM, 382 +/- 73 pg/ml) as compared to the pre-shunt (213 +/- 27 pg/ml; P less than 0.05) cirrhotic and control (53 +/- 13 pg/ml; P less than 0.005) groups. The MCR of glucagon was similar in control (13.0 +/- 1.3 ml/kg/min) and pre-shunt cirrhotic patients (13.3 +/- 1.7 ml/kg/min) but was significantly (P less than 0.02) decreased in the post-shunt cirrhotics (7.6 +/- 1.3 ml/kg/min). The t 1/2 for glucagon decay was similar in the control and cirrhotic groups. The BSDR, an estimate of pancreatic A cell secretion, was increased four-fold (P less than 0.01) in the pre-shunt (3042 +/- 454 pg/kg/min) and post-shunt (2518 +/- 535 pg/kg/min) cirrhotic groups, as compared to controls (750 +/- 244 pg/kg/min). It is concluded that (a) in the presence of cirrhosis, the magnitude of portasystemic shunting is important in determining the degree of hyperglucagonaemia; (b) in preshunt cirrhotics raised basal IRG levels are principally due to A cell hypersecretion of glucagon whereas in post-shunt cirrhotics riased IRG levels reflect both A cell hypersecretion and delayed clearance of glucagon; and (c) acute shunting of splanchnic venous blood away from the liver reduces the clearance of glucagon, suggesting that, in man, the liver contributes to the clearance of circulating glucagon.

The effect of shear, specific surface, and air interface on the development of blood emboli and hemolysis

Heparinized dog blood was exposed to shear and foreign surfaces in conicylindrical test cells. The cells were injection molded from polycarbonate and were filled using a technique that avoided contact of the blood with air. Particulate-matter formation was measured and was found to be dominated by the surface-to-blood-volume ratio and to be independent of shear rate. Hemolysis was also measured and was found to vary linearly with shear rate and to increase with increasing surface-to-blood volume ratio. Thus, at low shear rates and high specific surface conditions, the degree of hemolysis was found to be minimal while particulate-matter formation was high. The results suggest that the safety of extracoporeal perfusion procedures cannot be inferred from hemolysis measurements alone. In one series of tests, a gas-blood interface was generated at a rate equivalent to the rate of surface renewal in conventional disc oxygenators. The gas-blood interface failed to contribute significantly to the damage indices, which suggests that the apparent superiority of membrane oxygenators may be a result of factors other than the absence of a blood-gas interface.

Haemostasis disorders in open heart surgery with extracorporeal circulation. Importance of the platelet function and the heparin neutralization

The main haemostasis changes observed in a screening study performed in 40 patients who underwent an open heart surgery with extracorporeal circulation (ECC) are: a significant drop in platelet count from the onset of the ECC to the third postoperative day, a decrease of platelet retention and aggregation during ECC with an 8-day persistently increased heparin-neutralizing activity in plasma but not in serum, a moderate decrease of plasma factors I, II, VII-X, X and XIII and a more important drop in factor V which disappears 24 h after ECC, a transitory increase of fibrinolysis during ECC and the lack of FDP elevation in the serum. These disorders require a very good neutralization of the heparin used during ECC. The ratio protamine/heparin can be established by a titration clotting time test. Protamine chloride seems to be more efficacious and to act more quickly than protamine sulfate for the neutralization. An overload in protamine can enhance the hemostatic, biological and clinical disorders. The preventive administration of platelet concentrate immediately after the heparin neutralization contributes to reduce the bleeding disorders related to the quantitative and qualitative platelet defects.

Cellular aggregation and destruction during blood circulation and oxygenation

Platelet and leucocyte aggregation and severe haemolysis may occur in blood during the preparation of an extracorporeal circuit for open-heart surgery. Experiments with dog blood showed that both processes result from bubble oxygenation but not from circulation of diluted blood and that they appear to be inhibited by the presence of acid citrate dextrose and heparin, or citrate phosphate dextrose and heparin, but not by heparin alone.

Cerebrovascular blockade associated with thoracotomy and its prevention with a platelet inhibitor

Dogs subjected to a thoracotomy in which a rib-spreading retractor was employed developed filling defects in the cerebral microcirculation attributable to obstruction by microemboli. These changes were not observed in control groups and could be prevented in the experimental group by pretreatment with RA233, a platelet inhibitor. It is possible that microembolic-related complications of operations and trauma, such as pulmonary insufficiency, might be ameliorated by the use of platelet inhibitors.

Prevention of intraoperative myocardial injury by pretreatment with pharmacological agents

Pharmacological agents administered prior to the institution of myocardial anoxia or ischemia may protect the myocardium by preventing ATP depletion, structural damage to cell membranes and organelles, and postanoxic disturbances in coronary microcirculation. Propranolol, dipyridamole, nitroglycerin, and mannitol all have the potential to protect the myocardium in one or more of these ways and thus have promise for clinical use.

Platelets, thrombosis and drugs

The development of thrombosis involves 4 main factors: the vessel wall, the formed elements of the blood, blood coagulation, and blood flow. In venous thrombosis, however, the major part in both the initiation and growth of thrombi is played by the platelets. In selecting drugs which inhibit platelet function it is helful to know which of the platelet reactions that contribute to thrombus formation can be inhibited by various agents. Platelets adhere to the damaged vessel wall, collagen being probably the most important constituent involved. They are then stimulated to release the contents of their storage granules. Release-inducing agents promote the discharge of adenosine diphosphate (ADP) which causes platelets in the vicinity to swell to a more spherical shape, extend pseudopods and adhere to each other. Platelet aggregation is reversible, and a number of drugs have been shown to be capable of inhibiting platelet function at various stages, both in vitro and in vivo. Adrenaline, noradrenaline, oestrogens and nicotine enhance aggregation. Drugs which inhibit platelet function include the non-steroidal anti-inflammatory drugs, the pyrimido-pyrimidines (e.g. dipyridamole), hydroxychloroquine, clofibrate, and dextran. In this review the effects of drugs which inhibit platelet function are outlined and the extent to which they can be used to influence the course of thromboembolic disease in man is discussed. It is suggested that combination of anti-platelet drugs with anticoagulants could prove clinically useful.