Target direction rather than position determines oculomotor expectation in repeating sequences

Saccadic latencies to targets appearing to the left and right of fixation in a repeating sequence are significantly increased when a target is presented out of sequence. Is this because the target is in the wrong position, the wrong direction, or both? To find out, we arranged for targets in a horizontal plane occasionally to appear with an unexpected eccentricity, though in the correct direction. This had no significant effect on latency, unlike what is observed when targets appeared in the unexpected direction. That subjects learnt sequences of directions rather than simply positions was further confirmed in an experiment where saccade direction was a repeating sequence, but eccentricity was randomised. Latency was elevated when a target was episodically presented in an unexpected direction. Latencies were also elevated when targets appeared in the correct hemifield but at an unexpected direction (35° polar angular displacement from the horizontal, a displacement roughly equivalent in collicular spacing to our unexpected eccentricity), although this elevation was of a smaller magnitude than when targets appeared in an unexpected direction along the horizontal. Finally, we confirmed that not all changes in the stimulus cause disruption: an unexpected change in the orientation or colour of the target did not alter latency. Our results show that in a repeating sequence, the oculomotor system is primarily concerned with predicting the direction of an upcoming eye movement rather than its position. This is consistent with models of oculomotor control developed for randomly appearing targets in which the direction and amplitude of saccades are programmed separately.     

Allogeneic haemopoietic stem cell transplantation for multiple myeloma or plasma cell leukaemia using fractionated total body radiation and high-dose melphalan conditioning

We have evaluated the outcome of allogeneic haemopoietic stem cell transplantation for multiple myeloma using a conditioning regimen comprising fractionated total body irradiation and high-dose melphalan (110 mg/m2). The study comprised 25 patients (median age 49 years) who had been transplanted by either bone marrow (n = 13) or G-CSF mobilized peripheral blood stem cells (n = 12). Overall transplant-related mortality was 30% but was lower for patients < 50 years of age at transplant (21%). The main cause of treatment-related mortality was viral infection. Of the 19 patients evaluable post-transplant, 17 have so far achieved complete remissions. Currently, with a median follow-up of 3.4 years, 18 out of 25 patients are alive, of whom 15 are in continuing complete remission (CR) and 2 in second remission after suffering localized relapses, which were treated with radiotherapy and donor leucocyte infusions. Patients transplanted after 1 line of previous therapy, < 50 years of age and receiving peripheral blood stem cells (PBSC) rather than bone marrow (BM) had a superior outcome, although there was no statistically significant factor. We conclude that allogeneic transplantation should be considered as a potentially curative option for younger patients with myeloma and that the regimen using fractionated total body irradiation and melphalan has a high CR rate and a relatively low risk of treatment-related mortality, particularly in younger patients.     

Effects of food on the central and peripheral haemodynamic response to upright exercise in normal volunteers

The central and peripheral haemodynamic effects of a modest meal were investigated in healthy volunteers at rest and in response to submaximal exercise. The meal increased heart rate, cardiac output, oxygen consumption, carbon dioxide production, and minute ventilation at rest and during exercise. The effects of food were additive to those induced by the exercise. Food had no effect on limb blood flow and lowered total systemic vascular resistance suggesting that there were no compensatory changes in regional blood flow to help redirect blood to the gut. An increase in cardiac output, and therefore myocardial work, is the predominant cardiovascular response to eating and this may help explain the postprandial deterioration in symptoms of some patients with cardiovascular disorders.     

Traumatic dental injuries and Alpine skiing

Abstract – The purpose of this study was to determine the occurrence and type of traumatic dental injuries after maxillofacial injuries as a result of Alpine skiing. During an 8‐year period (from January 1991 to December 1998) 7600 patients with facial injuries were registered at the Department of Oral and Maxillofacial Surgery, University of Innsbruck, Austria. Of 784 patients with skiing‐related facial injuries (524 males, 260 females) 326 (41.6%) sustained injuries to 639 teeth. The age groups predominantly affected were between 7 and 32 years. Luxation injuries occurred in 338 (53%) teeth, fractures accounted for 270 tooth injuries (42%), and only 35 (5%) were lost at the place of the accident. Of skiers with traumatic dental injuries 58% had concomitant soft tissue injuries, while 23.3% had associated facial bone fractures. The most common causes of injury were falls in 42% (329 patients) and collisions with other persons in 24.1% (189 patients). Being hit by one's own sports equipment (11%) was the third most common cause. Collisions with obstacles accounted for 9% and lift accidents for 5.6% of injuries. The probability of suffering dentoalveolar trauma during skiing varied depending on the injury mechanism. There was a 2–fold risk for dentoalveolar trauma when colliding with objects, a 3.5‐fold risk when hit by one's own equipment and a 8.5‐fold risk during lift accidents. Dental injuries occurred in about 2% of all injured skiers. Dental health professionals should be aware of the high incidence and the distribution of dental trauma and facial injuries caused by skiing.     

Exercise tolerance in patients with heart failure--how should it be measured?

The exercise capability of 12 patients with heart failure was investigated by a variety of different methods before and after treatment with the vasodilator flosequinan. Two treadmill protocols were used, a modified Bruce with incremental workloads and a fixed workload protocol. On placebo, mean exercise time was greater with the Bruce protocol, 526 (64) s, than with the fixed protocol, 359 (59) s, P less than 0.005. Flosequinan increased exercise time more with the fixed protocol, so after 5 weeks' treatment exercise time was the same with both protocols; 680 (64) s with the Bruce and 673 (147) s with the fixed protocol. When the results are expressed as work, the patients achieved less with the Bruce protocol, 7.8 (1.9) kJ, than with the fixed protocol 12.5 (1.5) kJ on placebo, P less than 0.01. After flosequinan, the respective values were 14.5 (2.8) and 25.3 (5.1) kJ. Flosequinan improved corridor walk test times but there was no relationship between this and either treadmill test. Pedometer scores of customary activity were unchanged by flosequinan and were not correlated with any other exercise test. Different methods of assessing exercise capability provide different measures of patients' incapacity.     

STEM CELL MOBILIzATION IN NORMAL DONORS FOR ALLOGENEIC TRANSPLANTATION: ANALYSIS OF SAFETY AND FACTORS AFFECTING EFFICACY

The use of peripheral blood stem cells instead of bone marrow as the source of haemopoietic cells for allogeneic transplantation is being increasingly explored. We have analysed data from 17 normal donors who underwent stem cell mobilization for allogeneic transplantation with an identical protocol using G-CSF at a dose of 10 μg/kg/d, with the first leukapheresis (LP) on the day following the fourth dose of G-CSF. Both G-CSF administration and leukapheresis were well tolerated. Donors underwent a median of two leukaphereses (range one to three) and a median of 6.80 × 10⁶ CD34⁺ cells/kg recipient weight (range 2.4–15.6 × 10⁶) were collected. The median number of CD34⁺ cells per kg donor weight was 6.05 × 10⁶, when corrected for a 12 litre leukapheresis, this gave a median total of 3.89 × 10⁶ CD34⁺ cells/kg donor weight. When analysed with respect to factors which might influence the efficacy of mobilization, male donors were associated with a superior yield. The median number of CD34⁺ cells/kg/LP harvested was 4.96 × 10⁶ in males and 2.79 × 10⁶ in females ( P <0.05). The results suggested that, given a recipient of 75 kg, in a male donor a single 12 litre leukapheresis should yield sufficient CD34⁺ cells (4 × 10⁶/kg), whereas a female donor would be likely to need two leukaphereses. Age was not found to affect donor yield. In summary, these data confirm that leukapheresis is a safe procedure in normal donors and suggest that males may be more efficient mobilizers of stem cells than females.     

Abnormalities of the peripheral circulation and respiratory function in patients with severe heart failure

To investigate the peripheral circulatory and respiratory abnormalities which occur in patients with heart failure, forearm and calf blood flow were measured before and after upright exercise, and respiratory gas exchange was measured during exercise in 26 patients with severe heart failure. Compared with a group of normal subjects the patients had reduced limb blood flow at rest and the response of limb blood flow to upright exercise was also abnormal. The increase in calf blood flow after exercise and the reduction in blood flow in the non-exercising forearm were both smaller in patients than in controls. There was a significant correlation between the maximum exercise duration of the patients and calf blood flow both after exercise and at rest. Compared with another group of control subjects the patients had a higher minute ventilation during exercise and a reduced oxygen consumption. The respiratory exchange ratio during exercise was also higher in patients than in controls. This suggests that there is early onset of anaerobic metabolism during exercise in patients with severe heart failure.     

Effects of food on the central and peripheral haemodynamic response to upright exercise in normal volunteers.

The central and peripheral haemodynamic effects of a modest meal were investigated in healthy volunteers at rest and in response to submaximal exercise. The meal increased heart rate, cardiac output, oxygen consumption, carbon dioxide production, and minute ventilation at rest and during exercise. The effects of food were additive to those induced by the exercise. Food had no effect on limb blood flow and lowered total systemic vascular resistance suggesting that there were no compensatory changes in regional blood flow to help redirect blood to the gut. An increase in cardiac output, and therefore myocardial work, is the predominant cardiovascular response to eating and this may help explain the postprandial deterioration in symptoms of some patients with cardiovascular disorders.     

Intraocular lysozyme in experimental uveitis in rabbits: aqueous and vitreous assay.

We determined normal aqueous and vitreous lysozyme levels in rabbit eyes and induced experimental uveitis to record the uppermost aqueous and vitreous lysozyme levels. The normal aqueous humor of the rabbit eye contained 1.05 mug per milliliter lysozyme and the normal vitreous humor contained 0.45 mug per milliliter. After the intravitreal administration of a foreign protein, the aqueous and vitreous lysozyme levels rose within one day, reaching maximum values of 38.4 mug per milliliter and 114 mug per milliliter, respectively, at 14 days, and subsequently declining to minimal values by 28 days after injection.