Variation in 24 hemostatic genes and associations with non-fatal myocardial infarction and ischemic stroke

BACKGROUND

Arterial thrombosis involves platelet aggregation and clot formation, yet little is known about the contribution of genetic variation in fibrin-based hemostatic factors to arterial clotting risk. We hypothesized that common variation in 24 coagulation-fibrinolysis genes would contribute to risk of incident myocardial infarction (MI) or ischemic stroke (IS).

METHODS

We conducted a population-based, case-control study. Subjects were hypertensive adults and postmenopausal women 30-79 years of age, who sustained a first MI (n = 856) or IS (n = 368) between 1995 and 2002, and controls matched on age, hypertension status, and calendar year (n = 2,689). We investigated the risk of MI and IS associated with (i) global variation within each gene as measured by common haplotypes and (ii) individual haplotypes and single nucleotide polymorphisms (SNPs). Significance was assessed using a 0.2 threshold of the false discovery rate q-value, which accounts for multiple testing.

RESULTS

After accounting for multiple testing, global genetic variation in factor (F) VIII was associated with IS risk. Two haplotypes in FVIII and one in FXIIIa1 were significantly associated with increased IS risk (all q-values < 0.2). A plasminogen gene SNP was associated with MI risk. All are new discoveries not previously reported. Another 24 tests had P-values < 0.05 and q-values > 0.2 in MI and IS analyses, 23 of which are new and hypothesis generating.

CONCLUSIONS

Apart from the association of FVIII variation with IS, we found little evidence that common variation in the 24 candidate fibrin-based hemostasis genes strongly influences arterial thrombotic risk, but our results cannot rule out small effects.

Association between neonatal blood microtransfusions in the 1960s and hepatitis C virus infection

In the 1960s, a common practice in Italy was to give a few mL of blood or plasma to underweight or preterm newborns. We postulated that this practice might be the cause of hepatitis C virus (HCV) infections seen today in adults with a negative history, and no recall of such transfusions. We examined the transfusion files of children admitted to the Department of Paediatrics during 1968-74, and found that 613 children had been transfused within the first year of life. Of 57 traceable patients, 28 are now positive for antibodies to HCV, 17 of whom received at least one microtransfusion from a common donor who is also positive.

[Proposal for update of Bassini's procedure in the treatment of inguinal hernia under local anesthesia]

Inconvenience due to tension along the suture, a relative high recurrence rate, the availability of optimal prosthetic materials and the tendency to reduce hospital stay are the motivations which induced many surgeons to adopt alternative techniques instead of the traditional ones for inguinal hernia repair. Among these latter it is worthwhile to add a personal update of the Bassini's technique: the plasty tailored upon the polypropylene mesh performed in local anesthesia. Thanks to the use of the prosthetic mesh, the plasty is performed using only four stitches tied loosely without much high tension on the conjoined tendon. Such technical expedients reduced postoperative pain and give better warrant for the plasty and allow hernia repair in local anesthesia and on a daily basis.

[Plasma levels of atriopeptin and hemodynamics during major vascular surgery: comparison between isoflurane and propofol+fentanyl]

Atrial natriuretic factor (ANF) is a peptide hormone released from atrial cardiocytes in response to atrial stretch. It has potent and selective effects on vascular smooth muscle, fluid and electrolyte balance, and may interact with other vasoactive substances. The influence of anaesthesia and major vascular surgery on the release and circulation of ANF is unknown. Therefore the relationships between haemodynamic variables, volume expansion and plasma ANF were studied in patients undergoing resection of abdominal aortic aneurysm, randomly assigned to receive isoflurane or propofol+fentanyl anaesthesia. The end point of anaesthetic regimens was the stabilization of mean arterial pressure between +/- 33% from baseline. Haemodynamic parameters and plasma ANF levels were measured preoperatively, after intubation, following aortic cross-clamping, 24 and 48 hours postoperatively. Because of well-known large degree in interpatient pharmacodynamic variability, anaesthesia with propofol and fentanyl did not ensure, usually, the established end point in dose ranges that did not produce unacceptable morbidity. ANF plasma levels were elevated during surgery and in the immediate postoperative period in both groups. A significant correlation was found between ANF levels and mean right atrial pressure. We concluded that anaesthetic drugs do not affect ANF release. Volume expansion for prevention of declamping shock increased, ANF from basal values, during surgery. Inadequacy of postoperative analgesia or persisting atrial stretch could explain the finding of high plasma levels during the immediate postoperative period.

Experimental study of argon laser-induced microthrombosis during PGI2 infusion

In order to evaluate the Argon laser-induced microthrombogenesis during prostacyclin (PGI2) infusion on newly formed microcirculation in the rabbit ear chamber, time-space parameters have been calculated in 118 observations subdivided into 4 groups according to the type and size of the vessels irradiated. The observations were carried out without drug treatment, with continuous infusion of pH 10.5 glycine buffer and with continuous infusion of PGI2 at the dosage of 125 ng X kg-1 X min-1 diluted in the glycine buffer. The results indicated that during PGI2 infusion the size of the thrombus, measured by maximal thrombus area, was always significantly less extended than in untreated animals. Moreover, the number of emboli detached during the first 5 min after laser exposure, measured by rate of embolization, during PGI2 infusion in venules and in the larger arterioles was smaller than in untreated animals. The vasoconstriction which usually takes place in the arteriolar vessels--upstream and downstream from the irradiated site--was in no way modified by the infusion of PGI2. Finally, it was noted that glycine buffer infusion showed an unforeseen activity on laser-induced vascular reactivity.

Hemoglobin Legnano (alpha2 141 (HC3) Arg replaced by Leu beta2): a new abnormal human hemoglobin with high oxygen affinity

An abnormal, fast moving hemoglobin was noted in a 34-yr-old male patient living in Legnano (northern Italy) affected with renal failure and iron deficiency anemia, not related to the presence of the Hb variant. Structural studies have demonstrated a previously undescribed amino acid substitution, alpha 141 Arg replaced by Leu. This new variant has been named Hb Legnano, and is characterized by an increased oxygen affinity and a low cooperativity, at least as far as preliminary functional studies carried out on whole blood have indicated. Family studies are reported: three other heterozygous carriers were observed among the relatives of the propositus, all showing a mild polycythemia which, however, does not seem to produce appreciable clinical consequences.