Titanium Dioxide/Graphene Oxide Composite Coatings for 316 Stainless Steel Dental Implants.

Stainless steel has been used in orthopedics and orthodontic fields. However, it cannot be used for fabrication of dental implants due to its inertness, low biocompatibility and weak resistance to corrosion. A composite coating of titanium oxide /graphene oxide has been prepared for stainless steel to improve its biological properties. Stainless steel discs were polished, cleaned and pre-treated with a mixture of HNO3 and HF acid for 15 min. The composite coating composed of TiO2 produced by sol-gel technique and doped with 0.75 wt% graphene oxide. XRD, SEM-EDX and AFM were employed to characterize the composite coating. The anti-bacterial action of the composite coating was investigated against S. aureus and E. coli. The corrosion resistance of coated and noncoated samples was assessed in SBF using electrochemical technique. Cytotoxicity was assessed using osteoblast-like cells. The wettability was determined by contact angle, and bioactivity assessed by immersion in SBF. The results revealed that the composite coating was dense with few micro-cracks, and was not cytotoxic to osteoblast-like cells. The composite coating reduced bacterial colonies and the corrosion rate of the steel was improved. The wettability of the sample was increased with the composite coating and apatite formation appeared after 21 days.

How to carry out microbiological sampling of healthcare environment surfaces? A review of current evidence.

There is increasing evidence that the hospital surface environment contributes to the spread of pathogens. However, evidence on how best to sample these surfaces is inconsistent and there is no guidance or legislation in place on how to do this. The aim of this review was to assess current literature on surface sampling methodologies, including the devices used, processing methods, and the environmental and biological factors that might influence results. Studies published prior to March 2019 were selected using relevant keywords from ScienceDirect, Web of Science, and PubMed. Abstracts were reviewed and all data-based studies in peer-reviewed journals in the English language were included. Microbiological air and water sampling in the hospital environment were not included. Although the numbers of cells or virions recovered from hospital surface environments were generally low, the majority of surfaces sampled were microbiologically contaminated. Of the organisms detected, multidrug-resistant organisms and clinically significant pathogens were frequently isolated and could, therefore, present a risk to vulnerable patients. Great variation was found between methods and the available data were incomplete and incomparable. Available literature on sampling methods demonstrated deficits with potential improvements for future research. Many of the studies included in the review were laboratory-based and not undertaken in the real hospital environment where sampling recoveries could be affected by the many variables present in a clinical environment. It was therefore difficult to draw overall conclusions; however, some recommendations for the design of routine protocols for surface sampling of healthcare environments can be made.

Changes in bone mineral and matrix in response to a soft diet.

Alterations in the magnitude of habitual mechanical loads upon the skeleton may not only affect bone architecture, but also influence the nature of the bone matrix. We tested the hypothesis that changing the mechanical consistency of the diet affects both the mineral and non-mineralized moieties of bone matrix. Female rats were fed a soft diet (powdered chow as a paste), while control animals were fed the standard chow. After 8 or 20 wks, animals were killed. Cranial (mandible, maxilla, parietal, and frontal) bones and ulnae were analyzed for mineralization density by quantitative backscattered electron microscopy, and sulphated glycosaminoglycan levels with alcian blue staining were measured by microdensitometry. The soft diet group showed a significant increase in mineralization density distribution at almost all cranial sites and a reduction in alcian blue staining in alveolar bone. Altering the consistency of the diet significantly affects mineral concentration and glycosaminoglycan content of alveolar bone.

Ovariectomy vs. hypofunction: their effects on rat mandibular bone.

Previous studies have suggested that the mandible may be more influenced by mechanical loading than by circulating hormone levels. We tested the hypothesis that hypofunction has a greater influence than ovariectomy on mandibular bone. Two-month-old rats were ovariectomized (OVX) or had maxillary molars removed from one side to induce unilateral mandibular hypofunction. Control animals remained untreated. After 5 months, animals were killed, and bones were assessed by micro-tomography (muCT), quantitative back-scattered electron analysis in an SEM (qBSE-SEM), and light microscopy. Mineralization density was reduced in calvarial, maxillary, and mandibular alveolar bone following OVX, yet was increased in lingual mandibular alveolar bone of the hypo-function animals compared with controls. OVX caused a reduction in osteocyte density in alveolar bone, while hypofunction showed an increase compared with controls. Hypofunction led to alveolar bone becoming more highly mineralized and more cellular, while ovariectomy caused a reduction in both mineralization density and osteocyte numbers.

Identifying the cellular basis for reimplantation failure in repair of the rotator cuff.

We examined cultured osteoblasts derived from paired samples from the greater tuberosity and acromion from eight patients with large chronic tears of the rotator cuff. We found that osteoblasts from the tuberosity had no apparent response to mechanical stimulation, whereas those derived from the acromion showed an increase in alkaline phosphatase activity and nitric oxide release which is normally a response of bone cells to mechanical strain. By contrast, we found that cells from both regions were able to respond to dexamethasone, a well-established promoter of osteoblastic differentiation, with the expected increase in alkaline phosphatase activity. Our findings indicate that the failure of repair of the rotator cuff may be due, at least in part, to a compromised capacity for mechanoadaptation within the greater tuberosity. It remains to be seen whether this apparent decrease in the sensitivity of bone cells to mechanical stimulation is the specific consequence of the reduced load-bearing history of the greater tuberosity in these patients.

The representation of anaesthesia in children's literature.

Hospital admission for an operation can be a frightening and bewildering experience for a child. Effective communication is a prerequisite for all those who anaesthetise children, and good pre-operative preparation reduces anxiety and improves the child's ability to cope. Books are familiar to children and their use in providing information is an established practice in paediatric nursing. By searching web-based bookshops, we identified 19 books whose subject was admission to hospital for an operation. These books were analysed according to the accuracy of their description of the anaesthetic element of the surgical experience. Seven of these books can be recommended as useful descriptions of the key elements involved in general anaesthesia. These books provide a simple, effective and cheap resource to help children and their parents prepare for anaesthesia. They may also provide a useful tool for trainee anaesthetists by giving an insight into the child's level of understanding.

Spinal projection of spindle afferents of the longissimus lumborum muscles of the cat.

The connections and monosynaptic projections of muscle spindle afferents of individual heads of the longissimus lumborum have been studied in cats by natural stimulation, by electrical stimulation and by spike-triggered averaging from single identified afferents. The spindle afferents were classified by sensitivity to vibration and by the effect of succinylcholine on their response to ramp-and-hold muscle stretches. Axonal conduction and synaptic effects were recorded as field potentials and focal synaptic potentials during systematic exploration of the spinal cord in segments L1 to L4 with extracellular metal microelectrodes, singly and in linear arrays. Ascending branches of afferent axons within the cord had a significantly higher mean conduction velocity (CV: 56.5 m s(-1)) than descending branches (40.8 m s(-1)). The CV of ascending branches was significantly positively correlated with a measure of the strength of intrafusal bag(2) muscle fibre contacts, but not to a measure of bag(1) contacts. Two sites of monosynaptic excitatory projection in the cord were identified, namely to the intermediate region (laminae V, VI and VII) and to ventral horn region (laminae VIII and IX). In tests of 154 single afferents, signs of central projection were detected for 60, providing 122 regions of maximum negative focal synaptic potentials (FSPs) of mean amplitude 7.51 microV. Their longitudinal spacing indicated that axons gave off descending collaterals at intervals of 1.5-3.5 mm. Based on the amplitude of FSPs, the projection of secondary afferents is stronger than that of primaries in the intermediate region and possibly also in the ventral horn region. Evidence is also presented that spindle afferent input from different heads of the longissimus converges into any given spinal segment and that input in one spinal root projects to adjacent segments. It is concluded that the organization of the longissimus monosynaptic spindle input favours relatively tonic and diffuse stretch reflexes.

Classification of longissimus lumborum muscle spindle afferents in the anaesthetized cat.

Recordings have been made from 127 single muscle spindle afferents from the longissimus lumborum muscles of anaesthetized cats. They have been characterized by their responses to passive muscle stretch and the effects of succinylcholine (SCh) and by their sensitivity to vibration. The use of SCh permitted the assessment for each afferent of the influence of bag1 (b1) and bag2 (b2) intrafusal muscle fibres. From this, on the assumption that all afferents were affected by chain (c) fibres, they were classified in four groups: b1b2c (41.9%), b2c (51.4%), b1c (1.3%) and c (5.4%). All the afferents with b1 influence were able to respond one to one to vibration at frequencies above 100 Hz and were considered to belong to primary endings. On the basis of the vibration test, 64% of the b2c type afferents appeared to be primaries and 36% secondaries. Of the units classified as primaries, 41% were designated as b2c and would not therefore be able to respond to dynamic fusimotor activity. The significance of this relatively high proportion of b2c-type spindle primary afferents is discussed in relation to the specialized postural function of the back muscles.

Static and dynamic gamma-motor output to ankle flexor muscles during locomotion in the decerebrate cat.

In locomotion, the flexor muscles of the leg are mainly concerned with the relatively constant task of raising the foot, whereas the extensors have the more variable task of support and propulsion at different speeds. This suggests that the way in which the fusimotor system works may differ between the two muscle groups. Observations previously made of the static and dynamic gamma-motor firing patterns in the ankle extensor medial gastrocnemius (MG) have therefore been repeated in the flexor tibialis anterior (TA). One or more single gamma-motor axons, dissected from a small filament of TA nerve, were recorded simultaneously with a number of single spindle afferents in dorsal rootlets. Cats were decerebrated and locomoted spontaneously on a treadmill. Identification of each gamma-motor axon depended on relating the changes in firing caused by midbrain stimulation to the changes in static and dynamic behaviour of the spindle afferents in response to repetitive ramp and hold stretches. Static gamma axons all showed a smooth modulation in frequency, increasing in phase with muscle shortening, superimposed on a minimum frequency of about 20-30 impulses s(-1). Dynamic gamma axons showed interrupted firing with the frequency rising abruptly from zero at the onset of shortening, and falling again to zero shortly after the onset of lengthening. The frequency during the active periods was relatively constant, even when movement amplitudes varied. The basic similarity in the static and dynamic gamma discharge patterns for the two muscles suggests that the strategy of gamma-motor control is common to both flexors and extensors. The static gamma pattern is thought to be a 'temporal template' of the expected movement, effectively expanding the dynamic response range of the spindles in active movements. The dynamic gamma pattern sensitizes the primary afferents to detect the onset of muscle lengthening and to detect departures from the intended movement trajectory.

The influence of bag2 and chain intrafusal muscle fibers on secondary spindle afferents in the cat.

Static gamma-motor activity is strongly modulated by a particular phase relationship to the cyclic movements of locomotion, and this has a profound effect on the firing patterns of muscle spindle afferents. Whilst primary afferents are affected by both static and dynamic gamma-motor output,secondary afferents are affected significantly only by the static system acting via the intrafusal bag2 and chain fibres. It is therefore important to know how fluctuating patterns of static gamma-motor activity affect secondary afferents and to relate this to the actions of bagt and chain fibres. We have studied the action of single static gamma axons on secondary afferents in cat hindlimb muscles. Various physiological methods were explored to identify which of the intrafusal muscle fibres were being activated in each case, including the use of random stimulation and ramp frequency stimulation. The effects were also recorded of I Hz sinusoidally frequency-modulated gamma-axon stimuli and the amplitude and phase of the resulting afferent modulation related to the involvement of the bag2 and chain fibres. It was found that bag2 fibres are effective in biasing the secondary discharge, but their modulating action is relatively weak and involves a marked phase lag. Chain fibres acting alone cause strong modulation with very little phase lag. Mixed bag2 and chain-fibre action is most effective in modulating afferent discharge and causes intermediate values of phase lag. The results are discussed in relation to the control of natural movements and it is concluded that an important function of the static gamma motor system is to provide a signal to sum algebraically with the length-related signal. The results do not suggest that it could also usefully control stretch sensitivity.

Static fusimotor action during locomotion in the decerebrated cat revealed by cross-correlation of spindle afferent activity.

Cross-correlation of the discharges of muscle spindle afferents in ankle extensor and flexor muscles has been used to reveal the activity of static gamma (gammaS) motoneurones innervating chain intrafusal muscle fibres during locomotion. In the anaesthetised cat, the cross-correlation of spindle afferents, jointly innervated by a gammaS-efferent with chain fibre contacts, showed short duration synchrony (2-8 ms) when the efferent was stimulated repetitively. In pre-mammillary decerebrated cats, the cross-correlograms of discharges of some pairs of spindle afferents showed similar short duration peaks of synchronisation and these were interpreted as being due to a common gammaS drive to chain intrafusal muscle fibres. The incidence of synchrony was low, and was similar at rest (5 % of pairs) and during treadmill locomotion (7 % of pairs). Phase dependence of synchrony was evident during locomotion in the flexor muscle. The synchrony of muscle spindle afferent discharge is discussed in relation to estimates of the numbers of spindles contacted by individual gammaS-efferents.

Spinal anaesthesia for caesarean section in a patient with Cockayne syndrome.

Cockayne syndrome is a rare inherited disorder with photosensitivity, dysmorphism, short stature and neurological deficits. Sufferers with this condition rarely survive into reproductive life. We report the successful delivery of a woman in her second pregnancy with Cockayne syndrome, her first pregnancy having resulted premature labour, caesarean section under spinal anaesthesia with considerable hypotension, and neonatal death. On this occasion she was hospitalised at 19 weeks' gestation and delivered by elective caesarean section at 34 weeks. She had a Mallampatti score of 3, so spinal anaesthesia using 1.8 mL of hyperbaric bupivacaine was given with good effect and mother and baby did well. The aetiology and clinical symptoms of this rare congenital syndrome, together with the anaesthetic implications and management, are described and discussed.

Mechanical strain and fluid movement both activate extracellular regulated kinase (ERK) in osteoblast-like cells but via different signaling pathways.

Extracellular regulated kinases (ERKs)-1 and -2 are members of the MAPK family of protein kinases involved in the proliferation, differentiation, and apoptosis of bone cells. We have shown previously that ROS 17/2.8 cells show increased activation of ERK-1 or -2, which is sustained for 24 h, when the strips onto which they are seeded are subjected to a 10 min period of cyclic four point bending that produces physiological levels of mechanical strain along with associated fluid movement of the medium. Movement of the strips through the medium without bending causes fluid movement without strain. This also increases ERK-1/2 activation, but in a biphasic manner over the same time period. Our present study investigates the role of components of signaling pathways in the activation of ERK-1/2 in ROS 17/2.8 cells in response to these stimuli. Using a range of inhibitors we show specific differences by which ERK-1 and ERK-2 are activated in response to fluid movement alone, compared with those induced in response to strain plus its associated fluid movement. ERK-1 activation induced by fluid movement was markedly reduced by nifedipine, and therefore appears to involve L-type calcium channels, but was unaffected by either L-NAME or indomethacin. This suggests independence from prostacyclin (PGI(2)) and nitric oxide (NO) production. In contrast, ERK-1 activation induced by application of strain (and its associated fluid disturbance) was abrogated by TMB-8 hydrochloride, L-NAME, and indomethacin. This suggests that strain-induced ERK-1 activation is dependent upon calcium mobilization from intracellular stores and production of NO and PGI(2). ERK-2 activation appears to be mediated by a separate mechanism in these cells. Its activation by fluid movement alone involved both PGI(2) and NO production, but its activation by strain was not affected by any of the inhibitors used. The G protein inhibitor, pertussis toxin, did not cause a reduction in the activation of ERK-1 or -2 in response to either stimulus. These results are consistent with earlier observations of ERK activation in bone cells in response to both strain (with fluid movement) and fluid movement alone, and further demonstrate that these phenomena stimulate distinct signaling pathways.

Quality improvement report: Effect of a formal education programme on safety of transfusions.

PROBLEM: Failure of correct identification and insufficient monitoring of patients receiving transfusions continue to be appreciable and avoidable causes of morbidity and mortality. DESIGN: A study by a regional transfusion service and a transfusion nurse specialist of the effects of an education programme based on the current national guidelines on identification and monitoring of patients receiving transfusions. SETTING: A large United Kingdom teaching hospital which houses the headquarters of the regional transfusion service. KEY MEASURES FOR IMPROVEMENT: Improvement in compliance with published national guidelines on the prescription and administration of blood transfusions. STRATEGY FOR CHANGE: An audit of current compliance followed by dissemination by a transfusion nurse specialist of a clinical skills package (based on the best practice for transfusion) to all staff involved in giving transfusions. This was supported by trained instructors and the display of standard operating procedures for transfusion in all clinical areas. EFFECT OF CHANGE: An improvement in compliance with the national guidelines to over 95% in six out of seven of the recommendations on best practice was seen 18 months after the initial intervention. LESSONS LEARNT: The study shows that education of those who prescribe and administer transfusions, as recommended by bodies concerned with the hazards of transfusion, can improve the safety of transfusions.

Modulation of primary afferent discharge by dynamic and static gamma motor axons in cat muscle spindles in relation to the intrafusal fibre types activated.

1. Recordings were made from muscle spindle primary afferents from medial gastrocnemius and soleus muscles of the cat to study the modulating effects of varying gamma-motor stimulation frequency at constant muscle length. Stimulus trains had a mean frequency of 50 Hz and were sinusoidally frequency modulated at 1 Hz, with an amplitude of modulation of +/- 5 to +/- 30 Hz. 2. When dynamic gamma-axons (gamma(d)) were selected for their pure effect on bag(1) fibres, they were found to have very little modulating effect on afferent firing. 3. Static gamma-axons (gamma(s)) were tested with a random stimulus and correlation method to determine whether they acted purely on bag(2) fibres, purely on chain fibres or on both together. Pure bag(2) gamma(s)-axons had weak modulating effects with large values of phase lag. Pure chain connections were effective in modulating with very little phase lag, but their mean gain was low. Mixed bag(2) and chain axons were most effective and showed phase shifts proportional to gain. 4. The effects of muscle length changes recorded previously from locomotor movements were also tested, with and without accompanying stimulation of mixed gamma(s)-axons with pulse trains recorded from gamma(s)-axons. This gamma(s) stimulation had a powerful effect in increasing afferent discharge during muscle shortening. The difference in afferent firing between the stimulated and non-stimulated conditions accurately predicted the profile of the gamma(s) stimulation. 5. The results are discussed in relation to the ways in which the gamma-motor system may be used in natural movements.

Distinctive patterns of static and dynamic gamma motor activity during locomotion in the decerebrate cat.

Simultaneous recordings were made from gamma (gamma) motor axons and from muscle spindle afferents of the medial gastrocnemius (MG) muscle during locomotion in decerebrate cats. The gamma-neurons were identified as static or dynamic (gammas or gammad) by correlating their behaviour during midbrain stimulation with changes in muscle spindle afferent responses to muscle stretch. On the basis of their behaviour during locomotion, gammas neurons could be divided into two groups. One group (type-1) showed strongly and smoothly modulated discharge increasing in parallel with the active muscle shortening in ankle extension, but with phase advance. The other group (type-2) also showed a modulated pattern, but with increased firing centred on the flexion phase. The proportions of the two were 13 type-1 and 7 type-2. The type-1 firing pattern accurately predicted the difference in firing frequency for secondary afferents obtained by subtracting from the recordings made during active movements the response of the same units to the movements repeated passively in the absence of fusimotor activity. The type-2 pattern also became consistent with the difference signal, when operated on by a phase lag appropriate to the effects of bag2 intrafusal fibres. These results suggest that there may be some degree of separate control of chain and bag2 intrafusal fibres. The discharge of gammad axons was also found to fluctuate with the locomotor cycle, with a pattern very distinct from that of the gammas records. The gammad firing frequency rose very suddenly from zero to a maximum at the onset of muscle shortening and continued into the beginning of lengthening. The term 'interrupted' discharge is suggested as a useful description. The timing of this discharge was shown to be appropriate for sensitising the primary afferents to detect the onset of stretch.