The ultimate Aberdeen knot

INTRODUCTION

The Aberdeen knot has been shown to be stronger and more secure than a surgeon''s knot for ending a suture line. No data exist as to the ideal configuration of the Aberdeen knot. The Royal College of Surgeons of England in their Basic Surgical Skills Course, 2002 recommended six throws. The aim of this experiment is to find the ideal combination of throws and turns.

MATERIALS AND METHODS

Aberdeen knots of various configurations were tied in O-PDS suture (Ethicon, Johnson and Johnson). Each configuration was tied 10 times. A materials testing machine was used to test the knots to destruction in a standardised manner.

RESULTS

The knots were seen to behave in two ways. They either slipped and unravelled, or broke. Knots tied with fewer than three throws were unreliable. Knots tied with three throws and two turns appear to be the strongest configuration. Adding further throws and turns does not increase the strength of an Aberdeen knot.

CONCLUSIONS

An Aberdeen knot tied with three throws and two turns is the ultimate Aberdeen knot.     

Side effects of using nitrates to treat heart failure and the acute coronary syndromes, unstable angina and acute myocardial infarction

Nitrates are potent venous dilators and anti-ischemic agents. They are widely used for the relief of chest pain and pulmonary congestion in patients with acute coronary syndromes and heart failure. Nitrates, however, do not reduce mortality in patients with acute coronary syndromes. Combination of nitrates and hydralazine when given in addition to beta-blockers and angiotensin-converting enzyme (ACE) inhibitors reduce mortality and heart failure hospitalizations in patients with heart failure due to left ventricular systolic dysfunction who are of African-American origin. Side effects during nitrate therapy are common but are less well described in the literature compared with the reported side effects in patients with stable angina pectoris. The reported incidence of side effects varies highly among different studies and among various disease states. Headache is the most commonly reported side effect with an incidence of 12% in acute heart failure, 41-73% in chronic heart failure, 3-19% in unstable angina and 2-26% in acute myocardial infarction. The reported incidence of hypotension also differs: 5-10% in acute heart failure, 20% in chronic heart failure, 9% in unstable angina and < 1-48% in acute myocardial infarction, with the incidence being much higher with concomitant nitrate therapy plus angiotensin-converting enzyme inhibitors. Reported incidence of dizziness is as low as 1% in patients with acute myocardial infarction to as high as 29% in patients with heart failure. Severe headaches and/or symptomatic hypotension may necessitate discontinuation of nitrate therapy. Severe life threatening hypotension or even death may occur when nitrates are used in patients with acute inferior myocardial infarction associated with right ventricular dysfunction or infarction, or with concomitant use of phosphodiesterase-5 inhibitors or N-acetylcysteine. Despite the disturbing observational reports in the literature that continuous and prolonged use of nitrates may lead to increased mortality and recurrent myocardial infarction in patients with stable coronary artery disease, no such adverse effects of nitrates have been reported in the large randomized trials in patients with acute myocardial infarction or chronic heart failure.     

Granulocyte colony-stimulating factor crosses the placenta and stimulates fetal rat granulopoiesis

We studied the effect of recombinant human granulocyte colony- stimulating factor (rhG-CSF) administration to pregnant rats upon fetal and neonatal myelopoiesis. Pregnant rats were treated with rhG-CSF twice daily for 2, 4, and 6 days before parturition. rhG-CSF crossed the placenta and reached peak fetal serum concentrations 4 hours after administration. Peak fetal serum levels were 1,000-fold lower than levels detected in the dam. Hematopoietic effects of rhG-CSF were assessed by cytologic analysis of the newborn blood, spleen, bone marrow, thymus, and liver. White blood cell counts were increased twofold to fourfold in newborns. This increase was due to circulating numbers of polymorphonuclear cells (PMN). rhG-CSF induced a myeloid hyperplasia in the newborn marrow consisting of immature and mature myeloid cells in the day-2 and day-4 treated pups. Bone marrow of pups treated for 6 days contained mostly hyper-segmented PMN with little or no increase in myeloid precursors. An increase in the number of postmitotic (PMN, bands, and metamyelocytes) and mitotic (promyeloblasts, myeloblasts, and metamyeloblasts) myeloid cells in the spleen of neonates was observed. No change was detected in splenic lymphocytes or monocytes. No effect of rhG-CSF was noted in the newborn liver or thymus. These results demonstrate that maternally administered rhG-CSF crosses the placenta and specifically induces bone marrow and spleen myelopoiesis in the fetus and neonate. The significant myelopoietic effects of rhG-CSF at low concentrations in the fetus suggest an exquisite degree of developmental sensitivity to this cytokine and may provide enhanced defense mechanisms to the neonate.     

Valsartan in chronic heart failure

OBJECTIVE: To evaluate the evidence for valsartan in the treatment of heart failure and determine its need for formulary inclusion. DATA SOURCES: OVID and PubMed databases were searched (1983-June 2004) using the key words angiotensin-receptor blocker, heart failure, valsartan, Diovan, and angiotensin-converting enzyme inhibitor. Only English-language literature was selected. STUDY SELECTION AND DATA EXTRACTION: Pharmacology and pharmacokinetic evaluations for valsartan were selected. Prospective, randomized clinical trials investigating the use of valsartan and other angiotensin-receptor blockers (ARBs) in chronic heart failure were evaluated. DATA SYNTHESIS: Valsartan, a selective antagonist for angiotensin receptor subtype 1, is the first ARB to be approved for use in chronic heart failure. Clinical trial data support valsartan as an alternative to angiotensin-converting enzyme (ACE) inhibitors in ACE inhibitor-intolerant patients with chronic heart failure. Valsartan is generally well tolerated, with renal impairment, elevated serum creatinine and potassium levels, and dizziness being the most common adverse effects; consequently, patients experiencing those adverse events while taking ACE inhibitors are likely to experience them with valsartan. Although further study is needed, differences in effectiveness among races may exist with use of valsartan; however, at this time, valsartan is recommended as an alternative to ACE inhibitors regardless of race. Candesartan and losartan have been studied in similar settings. Candesartan's data support its use in heart failure; however, losartan's data have been less consistent. CONCLUSIONS: Valsartan is a safe and effective alternative for heart failure patients intolerant of ACE inhibitors. Valsartan has not been shown to be safe and effective when used in combination with ACE inhibitors.