The role of the tail of the Wistar white rat in its temperature regulation was studied, and a new index of acclimatization was found. Blood flow in the tail was measured by venous-occlusion plethysmography at environmental temperatures from 17 to 33 °C. There is an abrupt vasodilation between 27 and 30° with flow rising from less than 5 ml to about 40 ml/100 ml tissue per minute. Measurement of heat loss by a gradient calorimeter on the tail showed a similar reflex vasodilation at a critical vasodilation temperature (TCVD). After vasodilation the tail can lose up to 20% of the total heat production of the rat. The skin temperature of the tail was used as an index of vasodilation to determine whether the critical temperature shifted with acclimatization to 11 °C, 20 °C, and 30 °C. There is a decrease in TCVD of about 6° after acclimatization to cold (TCVD = 20 °C for 11 °C, 26 °C for 20 °C). After acclimatization to 30 °C, no vasodilation was found at temperatures up to 33 °C. The maximum heat loss of the tail is greatly increased after cold acclimatization. The mechanism of the shift is probably a change in sensitivity of thermal receptors on the tail, due to an increased vascularity (increased thermal conductivity) of the local tissues.
To improve vascular access for hemodialysis, a new device (Dialock Hemodialysis Access System, Biolink Corporation, Middleboro, MA) has been developed. Implanted subcutaneously, the device is accessed by percutaneous puncture. Attached to the device are two catheters that are implanted into the superior vena cava or right atrium. Clinical results thus far have been promising. However, use of this device is not free from infectious complications. In the present pilot study, 25 maintenance hemodialysis patients were implanted with 26 Dialock devices. The incidence of bacteremia was 2.9/1,000 catheter days. In 14 episodes of bacteremia in 8 patients the infection was successfully treated with a combination of systemic antibiotic treatment and adjunctive antibiotic/anticoagulant lock therapy. The lock therapy entailed the instillation of both an antibiotic and an anticoagulant into the device. We believe that the antibiotic/anticoagulant lock technique is an effective, adjunctive therapeutic modality in the treatment of infections related to the use of indwelling vascular access devices.
In 52 unselected patients maintained in intermittent hemodialysis, protein calorie malnutrition was present in 10 patients (19%). Complete cutaneous anergy to four intradermal skin antigens. (Candida, tuberculin, Streptokinase-dornase, and mumps) and failure to respond to contact sensitization to dinitrochlorobenzene was present in 60% of the patients. No correlation between cutaneous anergy and protein calorie malnutrition could be demonstrated.
Exposure of human neutrophils to a conventional, acidic, lactate-containing peritoneal dialysis solution (PDS) resulted in the development of a prompt and substantial intracellular acidosis. It is possible that this intracellular acidosis contributes to cellular dysfunction.
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