Tests for presynaptic modulation of corticospinal terminals from peripheral afferents and pyramidal tract in the macaque

The efficacy of sensory input to the spinal cord can be modulated presynaptically during voluntary movement by mechanisms that depolarize afferent terminals and reduce transmitter release. It remains unclear whether similar influences are exerted on the terminals of descending fibres in the corticospinal pathway of Old World primates and man. We investigated two signatures of presynaptic inhibition of the macaque corticospinal pathway following stimulation of the peripheral nerves of the arm (median, radial and ulnar) and the pyramidal tract: (1) increased excitability of corticospinal axon terminals as revealed by changes in antidromically evoked cortical potentials, and (2) changes in the size of the corticospinal monosynaptic field potential in the spinal cord. Conditioning stimulation of the pyramidal tract increased both the terminal excitability and monosynaptic fields with similar time courses. Excitability was maximal between 7.5 and 10 ms following stimulation and returned to baseline within 40 ms. Conditioning stimulation of peripheral nerves produced no statistically significant effect in either measure. We conclude that peripheral afferents do not exert a presynaptic influence on the corticospinal pathway, and that descending volleys may produce autogenic terminal depolarization that is correlated with enhanced transmitter release. Presynaptic inhibition of afferent terminals by descending pathways and the absence of a reciprocal influence of peripheral input on corticospinal efficacy would help to preserve the fidelity of motor commands during centrally initiated movement.

Do cerebral blood volume and contrast transfer coefficient predict prognosis in human glioma?

INTRODUCTION

Noninvasive measurements of cerebral blood volume (CBV) and contrast transfer coefficient (K(trans)) have potential benefits in the diagnosis and therapeutic management of adult glioma. This study examines the relationship between CBV, K(trans), and overall survival.

METHODS AND MATERIALS

Twenty-seven adult patients with glioma underwent T1-weighted dynamic contrast-enhanced MR imaging, and parametric maps of CBV and K(trans) were calculated. The relationship of histologic grade, CBV, K(trans), age, sex, surgical resection, and use of adjuvant therapy to survival were analyzed by using the logrank method and Cox regression analysis. The Kaplan-Meier method for displaying survival curves was used. The relationship of factors such as comorbidity, elevated intracranial pressure, size of nonenhancing tumor, and peritumoral edema were not considered.

RESULTS

Both CBV (P < .01) and K(trans) (P < .01) show a significant relationship to histologic grade. CBV (P = .004), K(trans) (P = .008), and histologic grade (P < .001) all demonstrate a significant association with patient survival when analyzed individually. Cox regression analysis identified only histologic grade (P < .01) and K(trans) (P < .05) as independent significant prognostic indicators. Examination of survival data from high-grade (III and IV) tumors demonstrated a linear relationship between K(trans) and patient survival (P < .01).

CONCLUSION

This study suggests a direct relationship between K(trans) and length of survival in high-grade gliomas, which could be of clinical importance. CBV relates directly to histologic grade but provides no independent prognostic information over and above that provided by grade. Further large prospective studies should be planned to test whether this observation holds true.

Relationship of deep white matter hyperintensities and cerebral blood flow in severe carotid artery stenosis

Leukoaraiosis (LA) has been associated with abnormalities of both large and small blood vessels. This study attempts to clarify the pathogenesis of LA by testing the hypothesis that increased frequency of LA with occlusive extra-cranial arterial disease results directly from global reduction in cerebral blood flow (CBF). Thirty-five normal subjects and 55 patients with carotid stenosis (>70%) were studied using MR. CBF was measured using phase contrast MR angiography and LA was scored using previously validated scoring system. Patients were divided into those with evidence of previous infarction on MRI and those without. LA was more severe in patients than in normal subjects (P<0.01) and correlated with age in normal subjects but not in patients. CBF in patients with (809+/-214 ml/min) and without infarction (mean 792+/-181 ml/min) was significantly lower than in normal subjects (mean 1073+/-194 ml/min). There was no correlation between the severity of LA and measured CBF in any group. The severity of LA is greater in patients with severe carotid stenosis but is not correlated to reductions in CBF. This suggests that microvascular abnormality is the dominant pathogenetic factor in LA even in the presence of severe stenotic/occlusive large vessel disease.

Balance marks cognitive changes in old age because it reflects global brain atrophy and cerebro-arterial blood-flow

In healthy old age biomarkers such as Balance robustly correlate with measures of mental abilities such as scores on tests of intelligence, reaction times and memory. A plausible explanation is that balance reflects general physiological fitness and so also neurophysiological integrity, but direct evidence is lacking. Brain scans measured age-associated loss of brain volume and cerebro-arterial blood flow (CBf) in 69 volunteers aged from 62 to 81 years who also took the Tinetti Balance test battery, 3 tests of fluid intelligence, 3 tests of decision speed and a memory test. Balance, but not atrophy or CBf, predicted intelligence test scores. Balance, atrophy, and CBf all independently predicted speed and memory scores but, after variance in atrophy and CBf had been considered, predictions from Balance were no longer significant. It appears that in these tests Balance marks cognitive performance in old age because it reflects gross age-related neurophysiological changes.

Gender differences in response to lorazepam in a human drug discrimination study

Gender differences in the discriminative stimulus properties of drugs of abuse have sometimes been reported, although we have previously found no differences in subjective or discriminative responses in human subjects acquiring an alcohol discrimination. The aim of the present work was to determine if there were gender differences in the effects of lorazepam, a benzodiazepine-receptor agonist which substituted for the alcohol stimulus in trained social drinkers. Volunteers who had already acquired an alcohol (0.2g/kg) placebo discrimination were administered (double-blind) either placebo (nine females, nine males) or lorazepam 2mg (six females, six males). They then sampled a series of five drinks and rated each one for likeness to the training stimulus (the generalization response). In addition they completed rating scales for subjective effects and the Digit Symbol Substitution Test (DSST). Lorazepam substituted for the alcohol stimulus equally in both sexes and increased associated scores for lightheadedness. Females however, showed a much greater DSST performance impairment following lorazepam, compared with males. This effect was independent of body weight differences and sedation. These results are discussed in the light of current knowledge of gender differences in response to drugs of abuse and suggest that the stimulus and cognitive effects of benzodiazepine-receptor agonists are modulated by different brain mechanisms.

Comparison of shuttle walk with measured peak oxygen consumption in patients with operable lung cancer

BACKGROUND

The relationship between the shuttle walk test and peak oxygen consumption in patients with lung cancer has not previously been reported. A study was undertaken to examine this relationship in patients referred for lung cancer surgery to test the hypothesis that the shuttle walk test would be useful in this clinical setting.

METHODS

125 consecutive patients with potentially operable lung cancer were prospectively recruited. Each performed same day shuttle walking and treadmill walking tests.

RESULTS

Shuttle walk distances ranged from 104 m to 1020 m and peak oxygen consumption ranged from 9 to 35 ml/kg/min. The shuttle walk distance significantly correlated with peak oxygen consumption (r = 0.67, p<0.001). All 55 patients who achieved more than 400 m on the shuttle test had a peak oxygen consumption of at least 15 ml/kg/min. Seventy of 125 patients failed to achieve 400 m on the shuttle walk test; in 22 of these the peak oxygen consumption was less than 15 ml/kg/min. Nine of 17 patients who achieved less than 250 m had a peak oxygen consumption of more than 15 ml/kg/min.

CONCLUSION

The shuttle walk is a useful exercise test to assess potentially operable lung cancer patients with borderline lung function. However, it tends to underestimate exercise capacity at the lower range compared with peak oxygen consumption. Our data suggest that patients achieving 400 m on the shuttle walk test do not require formal measurement of oxygen consumption. In patients failing to achieve this distance we recommend assessment of peak oxygen consumption, particularly in those unable to walk 250 m, because a considerable proportion would still qualify for surgery as they had an acceptable peak oxygen consumption.

Single centre experience of umbilical cord stem cell transplantation for primary immunodeficiency

Primary immunodeficiencies (PID) are an important cause of childhood mortality. Haematopoietic stem cell transplantation (HSCT) is the best treatment for many PID. Umbilical cord stem cells are an alternative source of HSC. There is little data regarding outcome of umbilical cord stem cell transplantation (UCSCT) for PID. Our single centre experience is reported. A retrospective study of 14 of 148 patients transplanted for PID, who have received 15 UCSCT was performed, with specific regard to graft-versus-host disease (GvHD) and immune reconstitution. Eight patients with severe combined immunodeficiency (SCID), and six with other combined immunodeficiencies were treated. Of the patients, 12 received unrelated cords, and two had sibling transplants. Median age at transplant was 3.5 months, median nucleated cell dose was 0.8 x 10(8)/kg. All engrafted. Median time to neutrophil engraftment was 22 days, median time to platelet engraftment was 51 days. One developed significant grade III GvHD post transplantation. In total, 11 patients had full donor T and six full donor B-cell chimerism, six of nine patients >1 year post-BMT had normal IgG levels and specific antibody responses to tetanus and Hib vaccines; two are being assessed. Two patients died of multi-organ failure related to pre-existing infection and inflammatory complications respectively. UCSCT should be considered for patients requiring stem cell therapy for PID.

Participation of disadvantaged parents in child care research

AIM

To assess the level to which parents from deprived and socially dysfunctional families collaborate in complex and time-consuming research.

DESIGN

Home-based study, of early physiological development in infants from a severely deprived area. Overnight continuous recordings of deep-body temperature with twice daily urine collection, parental daily diary of life-events and completion of child care social and psychological assessment by interview questionnaire. Measurements taken between age 6-12 weeks, each lasted 8-12 h per night, averaging four nights per baby. Level of parental participation assessed in relation to ongoing lifestyle pressures. Setting Home based. Inner city deprived estate.

PARTICIPANTS

Random sample of mothers with newborn healthy infants.

MEASUREMENTS

A total of 87 overnight deep body temperature recordings were made on 22 infants each lasting 8-12 h; 174 urine samples were taken; and 22 sets of questionnaires were completed.

RESULTS

Of 62 inner city deprived parents, 39 (62%) agreed to participate. 22 (35%) completed the study. Ongoing lifestyle pressures were high including incidents of burglary, fire and family violence. Family and partner pressures and life crises overwhelmed 10 non-participations.

CONCLUSIONS

Research partnerships can be developed with underprivileged families facing severe life-events. Parents were highly motivated to complete what they perceived as important infant care research.

Processing of radical prostatectomy specimens for correlation of data from histopathological, molecular biological, and radiological studies: a new whole organ technique

AIMS

To develop a method of processing non-formalin fixed prostate specimens removed at radical prostatectomy to obtain fresh tissue for research and for correlating diagnostic and molecular results with preoperative imaging.

METHODS/RESULTS

The method involves a prostate slicing apparatus comprising a tissue slicer with a series of juxtaposed planar stainless steel blades linked to a support, and a cradle adapted to grip the tissue sample and receive the blades. The fresh prostate gland is held in the cradle and the blades are moved through the cradle slits to produce multiple 4 mm slices of the gland in a plane perpendicular to its posterior surface. One of the resulting slices is preserved in RNAlater. The areas comprising tumour and normal glands within this preserved slice can be identified by matching it to the haematoxylin and eosin stained sections of the adjacent slices that are formalin fixed and paraffin wax embedded. Intact RNA can be extracted from the identified tumour and normal glands within the RNAlater preserved slice. Preoperative imaging studies are acquired with the angulation of axial images chosen to be similar to the slicing axis, such that stained sections from the formalin fixed, paraffin wax embedded slices match their counterparts on imaging.

CONCLUSIONS

A novel method of sampling fresh prostate removed at radical prostatectomy that allows tissue samples to be used both for diagnosis and molecular analysis is described. This method also allows the integration of preoperative imaging data with histopathological and molecular data obtained from the prostate tissue slices.

The assessment of antiangiogenic and antivascular therapies in early-stage clinical trials using magnetic resonance imaging: issues and recommendations

Vascular and angiogenic processes provide an important target for novel cancer therapeutics. Dynamic contrast-enhanced magnetic resonance imaging is being used increasingly to noninvasively monitor the action of these therapeutics in early-stage clinical trials. This publication reports the outcome of a workshop that considered the methodology and design of magnetic resonance studies, recommending how this new tool might best be used.