Developing 3D SEM in a broad biological context

When electron microscopy (EM) was introduced in the 1930s it gave scientists their first look into the nanoworld of cells. Over the last 80 years EM has vastly increased our understanding of the complex cellular structures that underlie the diverse functions that cells need to maintain life. One drawback that has been difficult to overcome was the inherent lack of volume information, mainly due to the limit on the thickness of sections that could be viewed in a transmission electron microscope (TEM). For many years scientists struggled to achieve three-dimensional (3D) EM using serial section reconstructions, TEM tomography, and scanning EM (SEM) techniques such as freeze-fracture. Although each technique yielded some special information, they required a significant amount of time and specialist expertise to obtain even a very small 3D EM dataset. Almost 20 years ago scientists began to exploit SEMs to image blocks of embedded tissues and perform serial sectioning of these tissues inside the SEM chamber. Using first focused ion beams (FIB) and subsequently robotic ultramicrotomes (serial block-face, SBF-SEM) microscopists were able to collect large volumes of 3D EM information at resolutions that could address many important biological questions, and do so in an efficient manner. We present here some examples of 3D EM taken from the many diverse specimens that have been imaged in our core facility. We propose that the next major step forward will be to efficiently correlate functional information obtained using light microscopy (LM) with 3D EM datasets to more completely investigate the important links between cell structures and their functions.

Screening cervical spine CT in the emergency department, Phase 2: A prospective assessment of use

BACKGROUND AND PURPOSE

The National Emergency X-Radiography Utilization Study Low-Risk Criteria were established to identify patients with a low probability of cervical spine injury in whom imaging of the cervical spine was unnecessary. The purpose of this study was to ascertain the number of unnecessary cervical spine CT studies on the basis of proper application of established clinical guidelines and, secondarily, to determine indications for ordering studies in the absence of guideline criteria.

MATERIALS AND METHODS

All patients presenting to a level I trauma center for whom a screening cervical spine CT was ordered in the setting of blunt trauma were eligible for enrollment. For each study, the requesting clinician completed a survey regarding study indications. CT examinations were evaluated by a board-certified radiologist blinded to survey data to determine the presence or absence of cervical spine injury.

RESULTS

Of 507 CT examinations, 5 (1%) were positive and 497 (98.0%) were negative for acute cervical spine injury. Five studies (1%) were indeterminate for acute injury but demonstrated no abnormality on subsequent imaging and clinical follow-up. Of the 502 studies without cervical spine injury, 81 (16.1%) were imaged despite meeting all 5 NEXUS criteria for nonimaging. Of these, the most common study indication was dangerous mechanism of injury (48.1%) followed by subjective neck pain (40.7%).

CONCLUSIONS

Strict application of NEXUS criteria could potentially reduce the number of screening cervical spine CT scans in the setting of blunt trauma; this change would avoid a considerable amount of unnecessary radiation and cost.

Noncollinear magnetization structure at the thickness-driven spin-reorientation transition in epitaxial Fe films on W(110)

An in-plane spin-reorientation transition occurring during the growth of epitaxial Fe films on W(110) was studied in situ by using the nuclear resonant scattering of synchrotron radiation. The spin-reorientation transition originates at the Fe/W(110) interface and proceeds via a noncollinear spin structure resembling a planar domain wall that propagates towards the surface with increasing film thickness.

Therapeutic hypothermia after out-of-hospital cardiac arrest with the target temperature 34-35 degrees C

BACKGROUND

The objective of this study was to evaluate the impact of mild hypothermia (34-35 degrees C) on the final neurological outcome in patients after resuscitation from out-of-hospital cardiac arrest.

METHODS

Forty three patients, admitted at University Hospital Brno after the out-of-hospital cardiac arrest, were included in the cohort study. The inclusion criteria were out-of-hospital cardiac arrest resulting from ventricular fibrillation or non-perfusing ventricular tachycardia as well as recovery of spontaneous circulation within 60 minutes after first symptoms. Blanketrol II (Cinncinnatti Sub Zero, USA) water mattresses were used for cooling the patients. The temperature was maintained at 34-35 degrees C for 24 hours. Favorable neurological outcome was defined as a Pittsburgh cerebral-performance category 1 (good recovery) or 2 (moderate disability) on five-category scale.

RESULTS

The required temperature was reached in all patients; the cooling rate was 0.8 +/- 0.3 degrees C/hour. The time between the restoration of circulation and reaching the temperature of 35 degrees C was 119 +/- 32 minutes. The time induce the hypothermia (with the core body temperature below 35 degrees C) was 26 +/- 2 hours. Good outcome at hospital discharge was achieved in 21 out of 43 (49%) patients. Ten patients died in the hospital and two patients died after the discharge from the hospital, with the overall 6 months mortality being 28%.

CONCLUSION

The study confirmed feasibility, safety and possible efficacy of the mild hypothermia (34-35 degrees C) patients after the cardiac arrest. To evaluate whether the target temperature 34-35 degrees C is as beneficial as 32-34 degrees C; a randomised controlled trial design should be used (Tab. 4, Fig. 2, Ref. 17). Full Text (Free, PDF) www.bmj.sk.

Tailoring of the perpendicular magnetization component in ferromagnetic films on a vicinal substrate

We have engineered the magnetic properties of 1-8 nm Co films epitaxially grown on an Au-buffered bifacial W(110)/W(540) single crystal. The surface of Au/W(110) was atomically flat, whereas the Au/W(540) followed the morphology of the vicinal W surface, showing a regular array of monoatomic steps. For Co grown on Au/W(540), the existence of the out-of-plane magnetization component extended strongly to a thickness d of about 8 nm, which was accompanied by an anomalous increase of the out-of-plane switching field with increasing d. In addition, the process of up-down magnetization switching could be realized with both a perpendicular and in-plane external magnetic field.

Phonons at the Fe(110) surface

The in-plane density of phonon states of clean Fe(110) surface was measured separately for the first, second, and further atomic monolayers using nuclear inelastic scattering of synchrotron radiation. The results show that atoms of the first layer vibrate with frequencies significantly lower and amplitudes much larger than those in the bulk, and that vibrational spectra along two perpendicular in-surface directions are different. The vibrations of the second layer are already very close to those of the bulk. The good agreement of the experimental results and the first-principles calculations allows for detailed understanding of the observed phenomena.

[Radical and conservative methods in the surgical treatment of brain abscesses]

In the light of own experience with 50 patients with brain abscesses and a survey of the literature the authors discuss the values of the surgical methods of treatment in this disease. When the radical methods are used the mortality is lowest and the incidence of recurrent abscesses is lowest, but of this treatment is likely to produce considerable neurological deficit it is better to apply conservative methods, such as puncture and drainage of the abscess. The sparing operation as a method of choice may be the first stage of treatment before radical operation in acute abscess and in patients in serious clinical condition.