Anatomical study of the renal veins observed during 342 living-donor nephrectomies.

The anatomical variations of renal veins observed during 342 nephrectomies in living donors are described, 311 cases on the left side and 31 on the right. The following anatomy of the renocava veins was observed: 1. On the left side the renal vein was always unique (311/311) and had two tributaries (suprarenal and gonadal veins) in 100 per cent and one or more renolumbar veins in 65.27 per cent, encircling the aorta in 1.07 per cent, was retroaortic in 1.4 per cent; and the inferior vena cava was double in 0.64 per cent; B- on the right side the renal vein was double in 29 per cent (9/31) and had only one tributary (gonadal vein) in one case, for 3.22 per cent (1/31); three or more renal veins in 9.7 per cent (3/31). We concluded that the left renal vein is always unique, presenting variations principally in its tributaries and trajectory. On the right side, the renal vein was double or triple in 38.79 per cent.

Postnephrectomy arteriovenous fistula.

The development of the postnephrectomy arteriovenous fistula (PNAVF) between the renal vessels stumps is rare. Here we present a case report of PNAVF, and review the diagnosis, treatment and prevention. The most common clinical features include a loud murmur over the previous nephrectomy scar, and heart failure resistant to common medical treatment. A 58-year-old white woman was admitted to the hospital for a complete evaluation of an unexplained congestive heart failure with no response to common medical treatment. She had had a right nephrectomy for pyonephrosis 13 years before. The diagnosis of PNAVF was suspected because over the right lumbar region a definite trill was palpated, and on auscultation a harsh, machinery-like murmur was heard. The diagnosis was confirmed by aortogram and selective renal arteriography. In May 1989, the right arteriovenous was excised through a right subcostal transperitoneal approach. The renal vessel stumps were individually ligated and sutured separately close to aorta and vena cava. The patient's postoperative course was entirely uneventful in the following seven years. We conclude that during nephrectomy, the renal vessels should be ligated separately, and the transfixation in mass of the stumps avoided to prevent arteriovenous fistula.

Methamidophos: an anticholinesterase without significant effects on postsynaptic receptors or transmitter release.

Methamidophos (O,S-dimethyl phosphoroamidothiolate, Tamaron), an organophosphate (OP) anticholinesterase of limited toxicity, is widely used as an insecticide and acaricide. To provide additional insight into the molecular basis of its action, we have used electrophysiological and biochemical techniques to study the effects of methamidophos on the neuromuscular junction of rat and frog and on the central nervous system of rat. Methamidophos has a relatively weak inhibitory action on cholinesterases in rat diaphragm muscle, brain and hippocampal homogenates, with IC50 values on the order of 20-20 microM. An even weaker anticholinesterase activity was found in frog muscle homogenates, with the IC50 being above 300 microM. As further evidence of anticholinesterase activity, methamidophos (1-100 microM) was able to reverse the blockade by d-tubocurarine (0.5-0.7 microM) of neuromuscular transmission in rat phrenic nerve-hemidiaphragm preparations. Inhibition of cholinesterase activity by methamidophos was long lasting, which is consistent with the formation by the agent of a covalent bond with the enzyme's active serine residue. The action was also slowly reversible, which suggests spontaneous reactivation of the enzyme. electrophysiological studies at the rat neuromuscular junction showed that, due to its anticholinesterase activity, methamidophos increased the amplitude and prolonged the decay phase of nerve-evoked and spontaneous miniature end-plate potentials. In contrast to other OP compounds, e.g., paraoxon (Rocha et al., 1996a), methamidophos did not affect neurotransmitter release, nor did it interact directly with the muscle nicotinic acetylcholine receptor. Moreover, it contrast to paraoxon, methamidophos did not affect the whole-cell currents induced by application of acetylcholine, glutamate or gamma-aminobutyric acid recorded to cultured hippocampal neurons. Based on these data, methamidophos appears to have a selective effect on cholinesterase.