Nanoscale LiZnN - Luminescent Half-Heusler Quantum Dots

Colloidal semiconductor quantum dots are a well-established technology, with numerous materials available either commercially or through the vast body of literature. The prevalent materials are cadmium-based and are unlikely to find general acceptance in most applications. While the III-V family of materials is a likely substitute, issues remain about its long-term suitability, and other earth-abundant materials are being explored. In this report, we highlight a nanoscale half-Heusler semiconductor, LiZnN, composed of readily available elements as a potential alternative system to luminescent II-VI and III-V nanoparticle quantum dots.

Patient Characteristics and Variables Influencing Acute Medical Flow

Waiting times are the most widely used indicator of patient flow. This project aims to analyse 24-hour variation in referrals and waiting times for patients referred to the Acute Medical Service (AMS). A retrospective cohort study was conducted at the AMS of Wales' largest hospital. Collected data included patient characteristics, referral times, waiting times and adherence to Clinical Quality Indicators (CQIs). Peak referral times were found between 11:00-19:00. Peak waiting times occurred between 17:00-01:00, which was longer on weekdays in comparison to weekends. Referrals between 17:00-21:00 had the longest waiting times with > 40% of patients failing both junior and senior CQIs. Mean and median age and NEWS were higher between 17:00-09:00. Weekday evening and nights are problematic for acute medical patient flow. Interventions, including workforce, should be targeted towards these findings.

Referral rates of patients with diabetes to secondary care are inversely related to the prevalence of diabetes in each primary care practice and confidence in treatment, not to HbA1c level

AIMS

To determine the factors affecting the referral rates of patients with diabetes from primary care to secondary care.

METHODS

A study based on 66 GP surgeries in the Cardiff and Vale University Health Board (population: 515,581) was conducted. We included patients who had an established clinical diagnosis of diabetes (type 1 and type 2) from September 2017 to September 2018. HbA1c outcome data of GP surgeries were obtained from the Quality and Outcomes Framework (QOF) database published for 2018. Referral rates were obtained from the electronic referral database of Cardiff and Vale University Health Board over the same period, and this was adjusted according to the number of patients with diabetes in each GP surgery. Confidence level on the treatment of diabetes among GPs was assessed as a sub-study conducted in nine GP surgeries in the same area, using a self-administered questionnaire. Linear regression was undertaken to assess the relationship between adjusted referral rate and key factors which might influence prescribing rate.

RESULTS

The average adjusted referral rate to secondary care in one year was 4.23% of patients with diabetes in each GP surgery, with a wide variation of 1.24% to 16.28%. The average percentage of patients with diabetes with HbA1c<59mmol/mol was 63.17% (range: 43.19-76.23%). The average confidence score of GPs in treating diabetes was 67% and ranged from 50-85% in the sub-study. Referral rates correlated inversely with the numbers of patients with diabetes in each practice β=-0.32; (95% CI -0.57, -0.08) p=0.01, but there was no significant correlation with the HbA1c outcome β=-0.13; (95% CI -0.39, 0.12); p=0.30. Borderline significant negative correlation was observed between referral rates and overall practice size β=-0.23; (95% CI -0.48, 0.02) p=0.07.

CONCLUSIONS

Referral rates of patients with diabetes to secondary care are determined by the number of patients with diabetes in each practice and confidence level in treatment, not by the overall practice size or HbA1c level. Ensuring quality training in diabetes care for primary care teams as well as the development of integrated diabetes care may be the best way to optimise the volume and appropriateness of referrals to secondary care.

TetraGrip - a four channel upper limb FES device for people with C5/C6 tetraplegia: device design and clinical outcome

The TetraGrip is an inertial measurement unit-controlled surface upper limb FES device developed for improving hand functions of people with tetraplegia. The reliability of the control system and the repeatability and reproducibility of the device were assessed by analysing the results obtained when 14 able-bodied volunteers used the device. These volunteers were able to generate the control signals effectively once they had sufficient training. The two tetraplegic volunteers participated in a 12-week long clinical study (exercise, 4 weeks; functional tasks, 8 weeks), where they used the device to perform functional tasks. Outcome measures used were the grasp release test, the grip strength test, and the box and block test. Both tetraplegic volunteers showed improvement in performing the tasks specified in all outcome measures. The TetraGrip performed as intended when the able-bodied volunteers used it, and it improved the hand functions of both volunteers with tetraplegia. However, a larger clinical study is necessary to assess the performance of the device with a wider range of people with tetraplegia such as those with C5 complete/incomplete.

Iodine supplementation in pregnancy - is it time?

Iodine is essential for the synthesis of thyroid hormone and optimal foetal neurological development. Pregnant women living in borderline or moderate-severe iodine deficient areas are at particularly high risk of being iodine deficient, and this may have important clinical consequences, particularly for the neurocognitive development of the offspring. It is a substantial problem and many countries including the United Kingdom are mild-moderately iodine deficient. Although the detrimental effects of severe iodine deficiency are well recognized, the benefits of correcting mild-to-moderate iodine deficiency are unclear due to a lack of randomized controlled trials in this area. However, observational data increasingly indicate that there may be substantial health and economic benefits from correcting iodine deficiency in pregnancy. There is now a growing trend from learned societies that iodine supplementation should be utilized in pregnancy in countries with mild-to-moderate iodine deficiency. The dose of iodine supplement needs to reflect local iodine status and iodization policies and will need careful monitoring at the population level to ensure doses to prevent under/excess dosing which would undermine the potential benefits. National tailored guidance is therefore essential.

Thyroxine replacement: a clinical endocrinologist's viewpoint

BACKGROUND

Hypothyroidism affects 2-5% of the general population. Patients with uncorrected disease suffer significant morbidity and have an increased risk of cardiovascular disease and neurocognitive impairment. Levothyroxine, the treatment of choice, is inexpensive, easy to administer and in most cases restores well-being while normalizing thyroid function. However, 30-50% of individuals on levothyroxine are either over-treated or under-treated and others remain dissatisfied with treatment despite achieving thyroid hormone concentrations within the laboratory reference interval.

METHODS

This review is based on a systematic search of the literature for controlled trials, systematic reviews, guideline papers and cohort studies addressing best practice in thyroid hormone replacement.

RESULTS

Recent decades have seen improvements in patient management strategies driven by a better appreciation of levothyroxine pharmacokinetics. However, aspects of therapy such as the optimal timing of medication, strategies to overcome treatment non-adherence and target thyroid stimulating hormone concentrations in pregnancy and in patients with differentiated thyroid cancer remain challenging. Furthermore, there is now a substantial body of literature on common genetic variations in the deiodinases and thyroid hormone transporters and their role in the local regulation of thyroid hormone delivery. The benefits of combination therapy with liothyronine and levothyroxine are uncertain, and while it is theoretically probable that subsets of genetically predisposed individuals will benefit from combination therapy the existing evidence is as yet limited.

CONCLUSION

Despite the availability of thyroid hormone replacement for more than a century, there are still substantial challenges in practice and opportunities to improve treatment outcomes.

HYPOTHYROXINAEMIA AND BRAIN DEVELOPMENT

The aim of this review is to indicate the current position on the role of thyroxine (T4) and fetal brain development with particular relevance to the human situation. Adequate maternal iodine nutrition and maternal circulating thyroxine (T4) concentrations are essential to ensure optimum T4 placental passage which in turn will ensure transport of T4 into fetal brain cells. These processes are discussed and the role of thyroid hormone transporters is considered. The emphasis on isolated maternal hypothyroxinaemia (IH) as an important factor affecting brain development is discussed from the animal experimental point of view as well as in the clinical setting. There is evidence of neurocognitive impairment as assessed by different modalities in children up to the age of 8 years and some suggestion of increased psychiatric disorder in older persons whose mothers had IH during gestation. Although international guidelines have not in general recommended thyroxine therapy for IH the recent demonstration of adverse obstetric outcomes in women with isolated maternal hypothyroxinaemia may warrant a revision of this strategy.

Upper limb functional electrical stimulation devices and their man-machine interfaces

Functional Electrical Stimulation (FES) is a technique that uses electricity to activate the nerves of a muscle that is paralysed due to hemiplegia, multiple sclerosis, Parkinson's disease or spinal cord injury (SCI). FES has been widely used to restore upper limb functions in people with hemiplegia and C5-C7 tetraplegia and has improved their ability to perform their activities of daily living (ADL). At the time of writing, a detailed literature review of the existing upper limb FES devices and their man-machine interfaces (MMI) showed that only the NESS H200 was commercially available. However, the rigid arm splint doesn't fit everyone and prevents the use of a tenodesis grip. Hence, a robust and versatile upper limb FES device that can be used by a wider group of people is required.

Impact on activities of daily living using a functional electrical stimulation device to improve dropped foot in people with multiple sclerosis, measured by the Canadian Occupational Performance Measure

Background: Dropped foot is a common problem following multiple sclerosis. Functional electrical stimulation can elicit an active muscle contraction providing dorsiflexion and eversion.

Objective: To determine if the Odstock dropped foot stimulator (ODFS), improved Activities of Daily Living for people with multiple sclerosis.

Method: 64 people with unilateral dropped foot due to secondary progressive multiple sclerosis took part in a randomized controlled trial. Research volunteers were assigned to a group using the ODFS or a group who received physiotherapy exercises for 18 weeks. Outcome measures were the Canadian Occupational Performance Measure (COPM) and a falls diary.

Results: Results of 53 research volunteers are reported. Improvements in performance and satisfaction scores were greater in the ODFS group than the exercise group; ( p < 0.05). Use of the ODFS was also perceived as effective in reducing tripping and increasing walking distance. The median number of falls were 5 in the ODFS group and 18 in the exercise group ( p = 0.036) over the study period.

Conclusion: The study shows that people with multiple sclerosis using the ODFS increased their COPM performance and satisfaction scores of their identified problems of Activities of Daily Living more than a matched group who received physiotherapy exercises. ODFS users also experienced fewer falls.

A randomized trial to investigate the effects of functional electrical stimulation and therapeutic exercise on walking performance for people with multiple sclerosis

Background

Functional electrical stimulation (FES), is a means of producing a contraction in a paralyzed or weak muscle to enable function through electrical excitation of the innervating nerve.

Objective

This two-group randomized trial assessed the effects of single channel common peroneal nerve stimulation on objective aspects of gait relative to exercise therapy for people with secondary progressive multiple sclerosis (SPMS).

Methods

Forty-four people with a diagnosis of SPMS and unilateral dropped foot completed the trial. Twenty patients were randomly allocated to a group receiving FES and the remaining 24 to a group receiving a physiotherapy home exercise program for a period of 18 weeks.

Results

The exercise group showed a statistically significant increase in 10 m walking speed and distance walked in 3 min, relative to the FES group who showed no significant change in walking performance without stimulation. At each stage of the trial, the FES group performed to a significantly higher level with FES than without for the same outcome measures.

Conclusion

Exercise may provide a greater training effect on walking speed and endurance than FES for people with SPMS. FES may provide an orthotic benefit when outcome is measured using the same parameters. More research is required to investigate the combined therapeutic effects of FES and exercise for this patient group.

The functional form of the lognormal distribution as a sum of decaying exponential and sinusoidal terms applied to the isometric pinch force of human fingers

The transient data of the pinch force produced between the human forefinger and thumb have been shown to fit the functional form of the well-known lognormal density function. Isometeric force generation is achieved by the stochastic recruitment of individual motor units, which sum together. Evidence from animal and human experiments demonstrates that the force generation can be modelled by underdamped terms. It is shown that a lognormal time series (distribution) can be fitted to a sum of exponential decaying sinusoidal terms.

A microcontroller system for investigating the catch effect: functional electrical stimulation of the common peroneal nerve

Correction of drop foot in hemiplegic gait is achieved by electrical stimulation of the common peroneal nerve with a series of pulses at a fixed frequency. However, during normal gait, the electromyographic signals from the tibialis anterior muscle indicate that muscle force is not constant but varies during the swing phase. The application of double pulses for the correction of drop foot may enhance the gait by generating greater torque at the ankle and thereby increase the efficiency of the stimulation with reduced fatigue. A flexible controller has been designed around the Odstock Drop Foot Stimulator to deliver different profiles of pulses implementing doublets and optimum series. A peripheral interface controller (PIC) microcontroller with some external circuits has been designed and tested to accommodate six profiles. Preliminary results of the measurements from a normal subject seated in a multi-moment chair (an isometric torque measurement device) indicate that profiles containing doublets and optimum spaced pulses look favourable for clinical use.

Electrical stimulation of abdominal muscles for control of blood pressure and augmentation of cough in a C3/4 level tetraplegic

OBJECTIVES

Evaluation of a FES (Functional Electrical Stimulation) device for the relief of postural hypertension and augmentation of cough in a C3 ventilator-dependent tetraplegic.

STUDY DESIGN

A single case study.

SETTING

A supra regional spinal unit in the UK.

METHOD

A dual channel stimulator was designed that allowed selection and initiation of two predetermined stimulation intensities using a chin controlled joystick. Two sets of 70 mm diameter electrodes were placed either side of the abdomen. Approximately 80 mA, 300 micros, 40 Hz was required for assisted cough while about 40 mA was required for maintenance of blood pressure. After eating, the lower level stimulus is self-administered every 3 to 5 min gradually increasing the time between groups of burst to once every hour after 90 min.

RESULTS

Following eating, a blood pressure of 60/45 mmHg was recorded. After five 1 s bursts of stimulation in quick repetition, this was increased to 133/92 mmHg. After 2 min blood pressure had fallen to 124/86 mmHg and to 93/66 after a further 4 min. The electrical stimulation was then repeated, returning the blood pressure to the previous higher level. Measurement of peak expiratory flow showed an increase from 275 l/min for an unassisted cough to 425 l/min when using the device.

CONCLUSION

The device is used every day. The user is now independent in coughing function and no longer requires suction or manual assistance. Maintenance of blood pressure has significantly improved his quality of life.

Restoration of tetraplegic hand function by use of the neurocontrol freehand system

Nine tetraplegic patients with C5 or C6 level spinal cord lesions had the Freehand System, an eight channel Functional Electrical Stimulation device, implanted to allow of hand opening and grasp. This paper describes the surgical implementation of the system and the challenges encountered. Seven of the subjects are currently daily users of the device. One subject is unable to use the system due to disruption of bowel function when the system is used. A second subject suffered a lesion of the posterior interosseous nerve, but this was not thought to be related to system use. Additionally, one subject exhibited symptoms of autonomic dysreflexia, which were alleviated by reduction of the strength of the stimulus. Despite such problems, the Freehand system can significantly improve the functional ability of C5 and C6 lesion tetraplegics.

Indices to describe different muscle activation patterns, identified during treadmill walking, in people with spastic drop-foot

This study was concerned with individuals who were unable to effectively dorsiflex their ankle when walking, as a result of a lesion of the central nervous system (CNS). Indices that categorise and quantify different patterns of calf and anterior tibial muscle activation patterns during treadmill walking have been derived from a sample of fifteen individuals with established hemiplegia following stroke and twelve age-matched individuals without impairment. As subjects walked on a treadmill, force sensitive foot-switches under the heel and first metatarsal head allowed EMG signals from the calf and anterior tibial muscles to be related to phases of the gait cycle. Normal activation periods for each muscle group were identified as percentiles of the gait cycle and indices for muscle activation periods were derived using ratios of integrated EMG during selected periods. Indices were derived that identified statistically significant differences, between normal and hemiplegic subjects, in calf activation during both push-off phase (P<0.001) and early stance phase (P<001), but not activation of tibialis anterior during swing (P=0.325) Observation suggested that integrated tibialis anterior activity during swing phase in hemiplegic subjects was not dissimilar to normal subjects, but the profile in hemiplegic subjects tended to lack the normal second peak of activity at initial foot contact. The reasons for drop-foot were shown to be varied and complex. The indices defined may be useful for directing therapy and measuring outcome.

Clinical use of the Odstock dropped foot stimulator: its effect on the speed and effort of walking

OBJECTIVE

To assess the clinical effectiveness of the Odstock dropped foot stimulator by analysis of its effect on physiological cost index (PCI) and speed of walking. This functional electrical stimulation (FES) device stimulates the common peroneal nerve during the swing phase of gait.

DESIGN

A retrospective study of patients who had used the device for 4 1/2 months.

SUBJECTS

One hundred fifty-one patients with a dropped foot resulting from an upper motor neuron lesion.

SETTING

A medical physics and biomedical engineering department of a district general hospital specializing in the clinical application of FES and a neurophysiotherapy department at a separate hospital.

MAIN OUTCOME MEASURES

Changes in walking speed and effort of walking, as measured by PCI over a 10-meter course.

RESULTS

There was a 92.7% compliance with treatment. Stroke patients showed a mean increase in walking speed of 27% (p<.01) and reduction in PCI of 31% (p<.01) with stimulation, and changes of 14% (p<.01) and 19% (p<.01), respectively, while not using the stimulator. Multiple sclerosis patients gained similar orthotic benefit but no "carry-over."

CONCLUSIONS

The measured differences in walking with and without stimulation were statistically significant in the stroke and multiple sclerosis groups. In this study use of the stimulator improved walking. Those with stroke demonstrated a short-term "carry-over" effect.

Patients' perceptions of the Odstock Dropped Foot Stimulator (ODFS)

OBJECTIVE

To determine the perceived benefit, pattern and problems of use of the Odstock Dropped Foot Stimulator (ODFS) and the users' opinion of the service provided.

DESIGN

Questionnaire sent in a single mailshot to current and past users of the ODFS. Returns were sent anonymously.

SETTING

Outpatient-based clinical service.

SUBJECTS

One hundred and sixty-eight current and 123 past users with diagnoses of stroke (CVA), multiple sclerosis (MS), incomplete spinal cord injury (SCI), traumatic brain injury (TBI) and cerebral palsy (CP).

INTERVENTION

Functional electrical stimulation (FES) to correct dropped foot in subjects with an upper motor neuron lesion, using the ODFS.

MAIN OUTCOME MEASURES

Purpose-designed questionnaire.

RESULTS

Return rate 64% current users (mean duration of use 19.5 months) and 43% past users (mean duration of use 10.7 months). Principal reason cited for using equipment was a reduction in the effort of walking. Principal reasons identified for discontinuing were an improvement in mobility, electrode positioning difficulties and deteriorating mobility. There were some problems with reliability of equipment. Level of service provided was thought to be good.

CONCLUSION

The ODFS was perceived by the users to be of considerable benefit. A comprehensive clinical follow-up service is essential to achieve the maximum continuing benefit from FES-based orthoses.

Long pulse biphasic electrical stimulation of denervated muscle

In recent years a number of studies have employed long pulse biphasic stimulation as a treatment for denervated muscle to improve tissue quality and in some cases to improve contractile capability sufficient to restore function. However, in the U.K., this treatment is yet to be widely adopted clinically. A 5 subject, case based pilot study of long pulse biphasic direct stimulation of peripheral limb denervated muscle is being conducted and its effect on the tissue evaluated by measurement of muscle bulk, limb blood flow, and skin temperature. In cases of partial denervation. trapezoidal shaped pulses are used to minimize sensory and motor nerve fiber recruitment.

Selecting candidates for a lower limb stimulator implant programme: a patient-centred method

OBJECTIVE

To develop an effective selection procedure for lower limb functional neurostimulation (LLFNS) for standing in paraplegia.

DESIGN

The selection procedure and exclusion criteria were based on the previous experience for two clinical centres with experience of LLFNS.

SETTING

Two Regional Spinal Injuries units in southern England.

SUBJECTS

254 fully rehabilitated paraplegics living in the community.

INTERVENTION

Patients were invited to participate in the programme, and if suitable to subject themselves to a rigorous staged selection procedure from which they could withdraw at any time.

OUTCOME MEASURE

Functionally successful home standing using closed-loop surface electrical stimulation.

RESULTS

57/254 patients were suitable on paper and were accessible. 19 of these (CI = 10-28) were interested in the project and attended one of the spinal centres for details. Twelve (CI = 5-19) of these fulfilled the selection criteria and started on the training programme; and 10 of them completed the muscle training programme successfully. Seven patients (CI = 2-12) achieved closed-loop standing in the laboratory and four patients (CI = 1-8) did so at home.

A fluorescence double-quenching study of native lipoproteins in an animal model of manganese deficiency

Iodide and acrylamide were applied simultaneously in a double-quenching experiment to compare acrylamide quenching constants for internal and external fluorophores of high-density lipoproteins (HDL1 and HDL2) from manganese-adequate (MnA) and deficient (MnD) rats, free of the electrostatic effects associated with iodide. In MnA HDL1 compared to MnD HDL1, the acrylamide quenching constant for external fluorophores was different (P < 0.1). In MnA HDL2, there were two populations of fluorophores accessible to acrylamide, whereas in MnD HDL2, all fluorophores were accessible to both quenchers. We concluded that there were structural (local environmental) differences, possibly charge-related, around the external fluorophores, and a slightly larger population of buried fluorophores in the MnD HDL1 compared with MnA HDL1. In MnA HDL2, one-third of the fluorophores were accessible to iodide, and all external and internal fluorophores were accessible to acrylamide, whereas in MnD HDL2, all fluorophores were accessible to both quenchers.

The effects of common peroneal stimulation on the effort and speed of walking: a randomized controlled trial with chronic hemiplegic patients

OBJECTIVE

To measure the effect of the Odstock Dropped Foot Stimulator (ODFS), a common peroneal stimulator, on the effort and speed of walking.

DESIGN

A randomized controlled trial.

SUBJECTS

Hemiplegic patients who had suffered a single stroke at least six months prior to the start of the trial whose walking was impaired by a drop-foot.

INTERVENTIONS

The treatment, functional electrical stimulation (FES) group, used the stimulator and received a course of physiotherapy; the control group received physiotherapy alone.

MAIN OUTCOME MEASURES

Changes in walking speed measured over 10 m and the effort of walking measured by physiological cost index (PCI).

RESULTS

Thirty-two subjects completed the trial, 16 in the FES group and 16 in the control group. Mean increase in walking speed between the beginning and end of the trial was 20.5% in the FES group (when the stimulator was used), and 5.2% in the control group. Improvement was also measured in PCI with a reduction of 24.9% in the FES group (when the stimulator was used) and 1% in the control group. No improvement in these parameters was measured in the FES group when the stimulator was not used.

CONCLUSION

Walking was statistically significantly improved when the ODFS was worn but no 'carry-over' was measured. Physiotherapy alone, in this group of subjects with established stroke, did not improve walking.

Lumbar root stimulation for restoring leg function: results in paraplegia

We have implanted an intradural array of 12 tripolar electrodes on the anterior roots L2-S2, left and right, at cauda equina level, in a 33-year-old woman with a complete T9 cord lesion of 3 years' duration. They are driven by an implanted multiplexed stimulator system using radio frequency (RF) power and control signals. All channels generate movements, in patterns that might be predicted from the known anatomy of the cauda equina. In particular, stimulation of L2 and L3 gives hip adduction; L3, L4, and L5 gives quadriceps femoris movements; L5, S1, and S2 gives hamstrings movement; and S1 and S2 give plantar flexion. Stimulation of L5 gives mixed movements at the ankle. Surprisingly, stimulation of the L2 roots has not given strong hip flexion. Responses have been stable. Some thresholds have varied, probably as a result of tissue encapsulation. The moment generated within each degree of freedom of the legs has been measured for each root, using a specially designed multimoment measurement apparatus. For several roots, a movement of lower threshold may be accompanied by a second movement of higher electrical threshold, suggesting that different muscles may have fiber populations that differ in their diameter or their location in the root. The use of stimulus forms that enable selective anodal block may, in the future, enable separation of two distinct movements from a single motor root.

Correlation of ATP/citrate lyase activity with lipid accumulation in developing seeds of Brassica napus L

The temporal distribution of ATP/citrate lyase (ACL) activity in developing seeds of Brassica napus L. closely paralleled both that of acetyl-CoA carboxylase and the overall rate of lipid biosynthesis. Maximum ACL activities (250 nmol acetyl-CoA formed min-1.g fresh seed) were recorded between 35 to 42 d after pollination and, if the in vitro data could be extrapolated to the situation in vivo, could account for half of the acetyl-CoA required for the measured rate of fatty acid biosynthesis during seed development. The enzyme appeared to be localized in a subcellular compartment, which was clearly separated from mitochondria on a sucrose gradient and by differential centrifugation, and which corresponded to the chloroplast organelle.

Between-site comparison of freshwater bacterioplankton by DNA hybridization

Natural assemblages of freshwater bacterioplankton in enriched lowland rivers had greater cell-specific metabolic activity than those in gravel-pit ponds. Similarly, cell-specific activity and mean cell Size in calcareous headstreams tended to be greater than in intermittently-acid headstreams on millstone grit. DNA was extracted and purified from bacterioplankton assemblages, and between-site comparisons were made in terms of percentage similarity as indicated by DNA hybridization. Cluster analysis, using percentage-similarity matrices, placed bacterioplankton assemblages from different site types into distinct groups. This suggested that between-site physiological differences were related to intrinsically different bacterial composition rather than to different physiological response to different environmental conditions by essentially similar bacterial assemblages.

Limb blood flow, cardiac output and quadriceps muscle bulk following spinal cord injury and the effect of training for the Odstock functional electrical stimulation standing system

As part of the assessment of the Odstock functional electrical stimulation (FES) standing system for mid to low thoracic lesion spinal cord injured (SCI) subjects, cardiac output, high blood flow and quadriceps muscle thickness were measured before and following an electrical stimulation muscle retraining programme. The same parameters were also measured in a group of uninjured subjects and in SCI subjects. It was found that there was no difference in cardiac output between the groups. However thigh blood flow was found to be around 65% of normal values in the spinally injured group. This returned to normal values following the retraining programme. The quadriceps muscle wasted to approximately 50% of its original thickness in the first 3 weeks following spinal cord injury. The retraining programme increased the muscle thickness to near normal values.

Characterisation of saporin genes: in vitro expression and ribosome inactivation

A. Saponaria (soapwort) genomic library was screened with a PCR-derived saporin-specific gene probe. The nucleotide sequences of three saporin genomic clones were determined. One of the clones contained a full-length saporin coding sequence whilst the other two were truncated. A hybrid full-length saporin coding sequence was constructed using the two truncated clones. An SP6 promoter sequence and in-frame initiation codon was added to each of the coding sequences using PCR. In vitro translation of saporin coding sequence transcripts in rabbit reticulocyte lysates resulted in the specific depurination of 28S RNA. This indicated that the saporin sequences encoded functional polypeptides with RNA N-glycosidase activity.

Use of air in double contrast barium enema--is it still acceptable?

There is conflicting evidence regarding the benefit of using carbon dioxide in a double contrast barium enema. In a double blind prospective study, 200 patients undergoing out-patient double contrast barium enemas (DCBE) were randomly allocated to receive either air or carbon dioxide (CO2) insufflation. After 24 h they were requested to complete and return a questionnaire regarding abdominal pain and distension experienced following the examination. The use of CO2 reduced the incidence of severe post-DCBE pain from 27% to 7%. There was a higher incidence of severe pain in younger patients, regardless of which gas was used. The incidence of severe pain following DCBE was unrelated to the presence or absence of abdominal pain as part of the patient's symptomatology. In the light of these findings we advocate the routine use of CO2 in DCBE.

Practical low cost stand/sit system for mid-thoracic paraplegics

The use of functional electrical stimulation (FES) to enable paraplegics to stand is not new or indeed difficult to undertake under laboratory conditions. However, there are substantial problems to overcome before such systems can be used routinely by patients without professional supervision. The overriding consideration has to be one of safety, i.e. the system must be 'fail safe'. Secondly, the system must be quick and easy to use in a wide variety of locations, otherwise it will not provide any increase in function. Finally, it must be inexpensive enough to be available to a large number of paraplegics. The primary aim of our work was to provide such a system to enable mid-thoracic lesion paraplegics to stand wherever they wish. This involved the development of a microprocessor-based stimulator to enable the stimulating envelope to be individually tailored to a given patient's requirements and the provision of closed loop control to minimize fatigue. A folding standing frame was also designed which replaces the arm rests on a standard wheelchair. Using this system, the user is able to stand within 30 s of stopping and can remain standing for up to 10 min. Cosmetic calipers (knee-ankle-foot orthoses) are also being used for paraplegics who require to stand for longer periods. It is hoped that such a system will provide stable standing for a large number of paraplegics at a unit cost of approximately 750 pound.