Time-resolved X-ray diffraction studies of myosin head movements in live frog sartorius muscle during isometric and isotonic contractions

Summary Using the facilities at the Daresbury Synchrotron Radiation Source, meridional diffraction patterns of muscles at ca 8°C were recorded with a time resolution of 2 or 4 ms. In isometric contractions tetanic peak tension (P ₀) is reached in ca 400 ms. Under such conditions, following stimulation from rest, the timing of changes in the major reflections (the 38.2 nm troponin reflection, and the 21.5 and 14.34/14.58 nm myosin reflections) can be explained in terms of four types of time courses: K ₁, K ₂, K ₃ and K ₄. The onset of K ₁ occurs immediately after stimulation, but that of K ₂, K ₃ and K ₄ is delayed by a latent period of ca 16 ms. Relative to the end of their own latent periods the half-times for K ₁, K ₂, K ₃ and K ₄ are 14–16, 16, 32 and 52 ms, respectively. In half-times, K ₁, K ₂, K ₃ lead tension rise by 52, 36 and 20 ms, respectively. K ₄ parallels the time course of tension rise. From an analysis of the data we conclude that K ₁ reflects thin filament activation which involves the troponin system; K ₂ arises from an order-disorder transition during which the register between the filaments is lost; K ₃ is due to the formation of an acto-myosin complex which (at P ₀) causes 70% or more of the heads to diffract with actin-based periodicities; and K ₄ is caused by a change in the axial orientation of the myosin heads (relative to thin filament axis) which is estimated to be from 65–70° at rest to ca 90° at P ₀. Isotonic contraction experiments showed that during shortening under a load of ca 0.27 P ₀, at least 85% of the heads (relative to those forming an acto-myosin complex at P ₀) diffract with actin-based periodicities, whilst their axial orientation does not change from that at rest. During shortening under a negligible load, at most 5–10% of the heads (relative to those forming an acto-myosin complex at P ₀) diffract with actin-based periodicities, and their axial orientation also remains the same as that at rest. This suggests that in isometric contractions the change in axial orientation is not the cause of active tension production, but rather the result of it. Analysis of the data reveals that independent of load, the extent of asynchronous axial motions executed by most of the cycling heads is no more than 0.5–0.65 nm greater than at rest. To account for the diffraction data in terms of the conventional tilting head model one would have to suppose that a few of the heads, and/or a small part of their mass perform the much larger motions demanded by that model. Therefore we conclude either that the required information is not available in our patterns or that an alternative hypothesis for contraction has to be developed.     

Evaluation of linear registration algorithms for brain SPECT and the errors due to hypoperfusion lesions

The semiquantitative analysis of perfusion single-photon emission computed tomography (SPECT) images requires a reproducible, objective method. Automated spatial standardization (registration) of images is a prerequisite to this goal. A source of registration error is the presence of hypoperfusion defects, which was evaluated in this study with simulated lesions. The brain perfusion images measured by 99mTc-HMPAO SPECT from 21 patients with probable Alzheimer's disease and 35 control subjects were retrospectively analyzed. An automatic segmentation method was developed to remove external activity. Three registration methods, robust least squares, normalized mutual information (NMI), and count difference were implemented and the effects of simulated defects were compared. The tested registration methods required segmentation of the cerebrum from external activity, and the automatic and manual methods differed by a three-dimensional displacement of 1.4+/-1.1 mm. NMI registration proved to be least adversely effected by simulated defects with 3 mm average displacement caused by severe defects. The error in quantifying the patient-template parietal ratio due to misregistration was 2.0% for large defects (70% hypoperfusion) and 0.5% for smaller defects (85% hypoperfusion).     

New method of evaluating patient preference for different inhalation delivery systems.

In order to assess patients' preferences for different inhalation devices a questionnaire has been developed. The questionnaire consisted of items covering various aspects considered important for patients who regularly use inhalation devices. The questions were designed to be of a general character so any inhalation device could be evaluated. We evaluated the questionnaire in a multicenter, open crossover study comparing patients' opinions of MDI with and without spacer and of a dry powder inhaler, Turbuhaler. One hundred twenty-three patients with stable asthma confirmed by daily peak expiratory flow rate (PEF) measurements used for 2 weeks MDI only and MDI with spacer and for 2 weeks Turbuhaler. The order was randomized. The drugs were terbutaline inhaled via MDI and Turbuhaler and budesonide inhaled via MDI with spacer and turbuhaler. At the end of each evaluation period the patients answered a number of questions about their opinion by marking on a visual analogue scale. A factor analysis revealed that the different questions represent a few common factors important for evaluating opinion about inhalation devices. These factors are handling of the device, use, time to learn how to use the device properly, how confident the patients feel about the use of it, and taste/irritation. A standardized questionnaire of reduced size seems to be a suitable method for evaluating patient preference for different inhalation devices.     

Public opinion on the ambulance service in a rural and an urban region

Two groups of parents to schoolchildren (7 y and 15 y) were formed. The aim was to study if there were any differences in attitudes and knowledge concerning ambulance services in rural and urban areas. The results showed that knowledge about the ambulance service is good. Further, that day to day activities were considered more important than security measures to be used in emergencies. Parents living in rural parts considered the ambulance "near" but not as "near" as the parents in urban districts.     

Direct versus indirect transfer for traumatic brain injury to James Cook University Hospital: a retrospective study

IntroductionPatients with traumatic brain injury are referred to the neurosurgical unit at James Cook University Hospital, Middlesbrough, either from local accident and emergency departments (direct transfer from the scene) or from other hospitals (indirect transfer). This study looked at the outcome in both groups.Material and methodsThis was a retrospective observational study using trauma audit research network data for patients treated for traumatic brain injury at the neurosurgery department at the neurosurgical unit at James Cook University Hospital.ResultsA total of 356 patients with traumatic brain injury were admitted under the care of neurosurgeons; 143 (40%) of these patients had a neurosurgical procedure. Of the patients undergoing a neurological procedure, 111 patients were transferred directly while 32 were indirect transfers; 213 patients were managed conservatively. Of those managed conservatively, 165 were transferred directly while 48 were indirect transfers.We compared the length of hospital stay and Glasgow Outcome Scale score for the patients based on whether they were conservatively managed or required surgery in the direct and indirect transfer groups. The difference in the length of stay in the surgical and conservative groups following direct and indirect transfer was insignificant (p = 0.07). The time to the operation in direct and indirect transfer was also not statistically significant (p = 0.06).ConclusionPatients are as safe, if not safer, by reaching the nearest trauma unit with facilities for resuscitation and imaging.     

Assessing the future direction of sustainable development in public hospitals: Time-horizon,path and action

PurposeTo assess the future direction of sustainable development in public hospitals, focusing on their short- versus long-term time horizons, top-down versus bottom-up paths, and intra-organizational versus inter-organizational actions.Design/Methodology/approachThe selection of significant health care organizations was based on judgmental sampling. This study applied an inductive approach. The interviewees were identified according to their knowledge of the future direction of their organizations’ sustainable development.FindingsThe sustainable development of the studied public hospitals is aimed at the synchronization of actions with other hospitals in the public healthcare system. The public hospitals studied differ in their interconnected elements of time (short- versus long-time horizons), paths (top-down versus bottom-up) and specific actions (intra-organizational versus inter-organizational).Research limitations/implications Offers insights into how to assess the direction of sustainable development in public hospitals. We stress the importance of time, path and action in conjunction. Furthermore, this study provides a three-dimensional framework to assess the future direction of sustainable development in organizations as well as in industries. Both the former and latter characteristics are shaped by the elements of time, path and action.Managerial ImplicationsProvides a three-dimensional framework of criteria to assess the direction of sustainable development in organizations. The assessment criteria may be used by organizations to assess the direction of other organizations in their industry. Industry associations or authorities may look into the status and future direction of sustainable development in industries or sectors as a whole. The assessment criteria provide an opportunity and foundation to benchmark against others in the same industry and insights to face pandemic as Covid-19.Originality/ValueFirst study to consider a three-dimensional framework based on time, path and action to assess the future direction of sustainable development in an organization.