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SummaryThere is evidence to suggest that platelet activation occurs in Raynaud’s syndrome. We evaluated the effect of prostacyclin (PGI2) a potent antiplatelet and vasodilator agent in 5 female patients with Raynaud’s syndrome. Outpatient visits were made at weekly intervals for 4 weeks. At the first visit buffer solution (Wellcome Laboratories) was infused intravenously for 5 hrs, thereafter three five hr infusions of PGI2 at a peak dose of 10 ng/ Kg/min were given. Six weeks after the infusions patients were reviewed. Symptomatic improvement, including healing of ischaemic ulcers, occurred in 4 out of 5 patients. Thermography confirmed an increase in hand temperature after PCI2. Subjective and objective improvement has persisted for at least 6 weeks after the last treatment.

A previous paper (Newman & Wolstencroft, 1960) described a fall in arterial blood pressure and increased respiration which were produced by heating the carotid blood in the anaesthetized cat. Since this effect was present in the decerebrate but not in the spinal animal, the effect of localized heating of the lower brain stem was then investigated. A region was found where heating produced changes in blood pressure and respiration similar to those produced by heating the carotid blood. These experiments are described in this paper; preliminary reports have been given by Newman & Wolstencroft (1957) and Holmes, Newman & Wolstencroft (1958). METHODSExperiments were performed on twenty-eight cats of either sex weighing between 2 and 4*5 kg and anaesthetized with sodium pentobarbital (45 mg/kg). Six cats were decerebrated at the level of the superior colliculi. Blood pressure was recorded from the femoral artery by means of a mercury manometer. Respiration was recorded by a method previously described (Newman & Wolstencroft, 1960).The pons and medulla were exposed by a ventral approach through the soft structures of the neck followed by removal of the overlying bone. Localized heating was effected by an electrode held in a stereotaxic instrument and connected to the output of a high-frequency (1500 kcfs) oscillator. The heating electrode consisted of silver wire, 0-2 mm diameter, insulated except at the tip. The other electrode was a saline pad applied to one limb. The temperature 2-3 mm from the electrode tip was recorded by a thermocouple inserted into the brain by means of forceps. Thermocouples were made by brazing together 40 s.w.G. copper and Constantan wires. Owing to electrostatic pick-up the thermocouple may have given readings which were 1°C higher than the true temperature (Huntoon, 1937).Electrode placements were determined by histological study after fixing the brain stem in formalin and embedding in celloidin or paraffin wax. Serial sections were cut at 25-100 , and stained with toluidin blue or thionine. The track of the electrode could easily be recognized in these sections. RESULTS Effect of heatingThe temperature recorded by the thermocouple before heating began was usually about 380 C. At responsive points in the medulla the following effects were observed when the heating current was turned on: Respiration increased with the rise in temperature, but the arterial blood pressure

Summary. Measurements of transcutaneous oxygen tension were made on the foot and arm in 16 Type 1 (insulin-dependent) diabetic patients with no evidence of vascular or neurological disease on simple clinical examination and in 30 nondiabetic subjects. The mean transcutaneous oxygen tension measured at 45 ~ on the foot was significantly lower in the diabetic patients than in the non-diabetic subjects. The hyperaemic response in the arm after cuff occlusion (measured by transcutaneous oxygen tension at 37 ~ was also significantly lower in the diabetic patients. These results may reflect abnormal capillary blood flow in diabetic patients. As the methods are simple and non-invasive, they may prove useful in the early assessment and subsequent monitoring of peripheral vascular problems in diabetes.Key words: Transcutaneous oxygen tension, vascular response, Type 1 diabetes, capillary blood flow.The technique of transcutaneous oxygen tension (TcPO2) measurement can provide a non-invasive method of estimating both arterial PO2 and tissue perfusion [1]. If the vascular bed is maximally dilated by heating to 45 ~ and adequately perfused, there is a good correlation between TcPO2 values and arterial PO2 in healthy adults [2]. With the electrode operating at a lower temperature (usually 37 ~ the TcPO2 reading is then related to skin perfusion and the technique can be used to assess reactive hyperaemia in the skin [3].We have reported previously a reduction in TcPO2 values at 45 ~ in patients with peripheral vascular disease [4], but whether such abnormalities in TcPO2 can be detected in diabetic patients with no clinical evidence of vascular disease is unknown. Reduction in vascular reactivity in diabetic children has been reported [5] and we have, therefore, investigated a group of adult Type 1 (insulin-dependent) diabetic patients to determine whether there are any differences in TcPO2 or in vascular reactivity compared with normal subjects. Patients and MethodsSixteen Type 1 diabetic patients, eight females and eight males, mean +SD age 28_6years (range 18-39years) were studied (Tablet). None had any symptoms of leg pain or claudication and all had palpable lower limp pulses including dorsalis pedis and posterior tibial pulses. Lower limb reflexes, pin prick and touch sensation and ankle vibration sense using a tuning fork (128 Hz) were also normal in all patients. Thirty normal subjects (11 females and 19 males) aged from 20 to 63 years were also studied. Twenty-two of this group (11 females and It males) were aged < 40 years (mean + SD: 28.4 + 6.1 years) and were used as control subjects. All gave informed consent. Six of the diabetic patients and 11 of the control subjects were regular smokers of 20-40 cigarettes daily. All subjects refrained from smoking for a minimum of 1 h before the procedure and were studied supine. The left arm and left foot were exposed and clothing loosened around the arm and leg to prevent any obstruction to blood flow. The examination room was maintained close to 26 ~ to prevent vasoconstri...