Pedal and distal lower leg bypasses with a distal arteriovenous fistula

In forty patients 41 feet were revascularised by means of distal tibial (the distal 10 cm of the lower leg) (17) or pedal bypasses (24). Angiographically the preoperative state was best defined as a lower leg block (LLB); All three arteries showing occlusions at several levels, leaving only isolated functioning arterial segments in the distal leg or foot with relatively good femoral and popliteal arteries. As might be expected this condition was mainly found in diabetics (75%). Only feet with severe rest pain (4) or rest pain with gangrene (37) were operated upon. To improve the distal outflow a side-to-side arteriovenous fistula (AVF) was added to the distal anastomosis. With a mean follow-up of 21 months (1-40 months) the limb salvage rate was 79% and the patency rate 67%. Special problems were experienced with cellulitis of the foot, causing the loss of three feet despite an open bypass and sufficient revascularisation. Furthermore, occlusion of the bypass after healing of the lesion did not necessarily mean a recurrence of gangrene. As this series shows, even in angiographically apparently hopeless cases, a bypass to the foot can prevent an otherwise unavoidable amputation.     

Survey of chemical exposures in a viscose rayon plant.

Measurements of carbon disulphide and hydrogen sulphide in a Belgian viscose rayon plant, using personal monitoring with charcoal tubes for carbon disulphide and impingers for hydrogen sulphide, showed considerable differences in the average exposure for the different jobs (3-147 mg m-3 for carbon disulphide and 0-9 mg m-3 for hydrogen sulphide). Air pollutants such as mercury and sulphuric acid, which have been reported in some other studies, were not present. The lead in blood concentration found in four plumbers ranged from 28 to 49 micrograms 100 ml-1. The implications of these findings for industrial hygiene and epidemiology are discussed.     

Electrophysiological aspects of the middle ear muscle reflex in the rat: latency, rise time and effect on sound transmission

The latency, the rise time and the influence of the acoustic reflex on sound transmission were investigated in the adult rat during ketamin anesthesia. This was done by recordings of the cochlear microphonics (CM) and electromyographic (EMG) recordings of the reflex responses of the tensor tympani muscle. The acoustic reflex was elicited by contralateral acoustic stimuli of which the intensity and frequency was varied. Ipsilaterally, the effect on sound transmission was determined by estimating the change in amplitude of the CM's of ipsilateral administered subliminal stimuli. It was shown that both the tensor tympani muscle and the stapedius muscle contribute in the reflex. The latency as well as the rise time of the reflex determined by CM recordings showed to be short (minimal values: 12 and 7 ms respectively). The mean latency of the tensor tympani muscle reflex, measured by EMG, was about 7 ms. The attenuation of 0.25-8 kHz tone bursts upto 115 dB SPL is limited to a mean maximum of 15 dB SPL. The maximal attenuation was shown to occur at 1 kHz. Frequencies above 2 kHz appeared to be the best elicitor of the middle ear muscle reflex.     

Female sex hormones and platelet/endothelial cell interactions

The effects of estradiol and progesterone added to the growth medium of human umbilical vein endothelial cells for 72 h on the formation and release of prostacyclin were investigated. The influence on collagen-induced platelet aggregation and on the platelet formation of thromboxane A2 following aggregation, of the growth medium collected before and after thrombin stimulation of the endothelial cells, was studied simultaneously. Under basal conditions, endothelial cells grown with progesterone released significantly less prostacyclin into the growth medium than did controls (p less than 0.05). Following thrombin stimulation, endothelial cells grown with estradiol (p less than 0.05) or a combination of estradiol and progesterone (p less than 0.01) contained significantly less prostacyclin than controls. No significant effects on the platelet aggregation or platelet thromboxane formation could be found. This study indicates a lowering effect of both female sex hormones on the endothelial cell prostacyclin formation and release. This may be of significance for the increased risk of vascular disease in pregnant women and oral contraceptive users, but can hardly explain the consequences of the hormonal loss occurring at the menopause.