Chemical resolution at ionic crystal surfaces using dynamic atomic force microscopy with metallic tips

We demonstrate that well prepared and characterized Cr tips can provide atomic resolution on the bulk NaCl(001) surface with dynamic atomic force microscopy in the noncontact regime at relatively large tip-sample separations. At these conditions, the surface chemical structure can be resolved yet tip-surface instabilities are absent. Our calculations demonstrate that chemical identification is unambiguous, because the interaction is always largest above the anions. This conclusion is generally valid for other polar surfaces, and can thus provide a new practical route for straightforward interpretation of atomically resolved images.

Evaluation of the anterior pituitary function in the acute phase after spontaneous subarachnoid hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) is a potential cause of hypopituitarism. Most of the studies regarding the relationship between SAH and anterior pituitary function were retrospective and hormonal assessment was performed several months after SAH.

AIM

To prospectively evaluate the prevalence of anterior pituitary hormone deficiencies in the acute phase after spontaneous SAH and their possible correlation with clinical and radiological parameters.

METHODS

Pituitary function was tested in 60 patients within 72 h after spontaneous SAH.

RESULTS

56.9% of the patients showed at least one anterior pituitary hormone deficiency: gonadotropin and GH secretion failure represented the most prevalent hormonal deficiencies (33.3 and 22.0%, respectively), whereas ACTH and TSH deficiency was less frequent (7.1 and 1.8%, respectively). With the exception of secondary hypogonadism, the prevalence of other pituitary hormone deficiencies is in agreement with previous studies, which evaluated pituitary function on longterm follow up after SAH. No correlation was found between hypopituitarism and clinical status, as assessed with Hunt-Hess and Glascow Coma Scales. Moreover, no correlation was found between hypopituitarism and bleeding severity evaluated with Fisher's scale.

CONCLUSIONS

We demonstrated a high prevalence of anterior pituitary hormone deficiencies acutely after SAH. Although part of GH and gonadotropin deficiencies might be a consequence of functional alteration due to SAH itself, the finding of low cortisol levels in this stressful condition strongly suggests the presence of true hypocortisolism. Therefore, an evaluation of pituitary function shortly after SAH might be useful to identify a subset of patients who deserve a more accurate follow-up.

The molecular phenotype of 6-week protocol biopsies from human renal allografts: reflections of prior injury but not future course

We assessed the molecular phenotype of 107 6-week protocol biopsies from human renal allografts, using Affymetrix microarrays. Transcript changes were summarized as nonoverlapping pathogenesis-based transcript sets (PBTs) reflecting inflammation (T cells, macrophages, IFNG effects) and the injury-repair response of the parenchyma, stroma and microcirculation-increased ('injury-up') and decreased ('injury-down') transcripts. The molecular changes were highly correlated with each other, even when all rejection and borderline cases were excluded. Inflammation and injury-down PBTs correlated with histologic inflammation and tubulitis, and the inflammation transcripts were greater in kidneys diagnosed as T cell-mediated or borderline rejection. Injury-up PBTs did not correlate with histopathology but did correlate with kidney function: thus functional disturbances are represented in transcript changes but not in histopathology. PBT changes correlated with prior delayed graft function. However, there was little difference between live donor kidneys and deceased donor kidneys that had not shown delayed graft function. Molecular changes did not predict future biopsies for clinical indications, rejection episodes, functional deterioration or allograft loss. Thus while detecting T cell-mediated inflammation, the molecular phenotype of early protocol biopsies mostly reflects the injury-repair response to implantation stresses, and has little relationship to future events and outcomes.

[Clinical application of computed tomography in cattle]

Computed tomography involves the use of x-rays to produce cross-sectional images of body regions. It provides non-overlapping, two-dimensional images of all desired planes as well as three-dimensional reconstruction of regions of interest. There are few reports on the clinical use of computed tomography in farm animals. Its use in cattle is limited by high cost, the application of off-label drugs and the need for general anaesthesia. In cattle computed tomography is indicated primarily for diseases of the head, e.g. dental diseases and otitis media, and neurological disorders. Less often it is used for diseases of the vertebrae and limbs. In valuable cattle, the results of computed tomography can be an important part of preoperative planning or be used to avoid unnecessary surgery when the prognosis is poor.

Quantitative sensory testing in the German Research Network on Neuropathic Pain (DFNS): somatosensory abnormalities in 1236 patients with different neuropathic pain syndromes

Neuropathic pain is accompanied by both positive and negative sensory signs. To explore the spectrum of sensory abnormalities, 1236 patients with a clinical diagnosis of neuropathic pain were assessed by quantitative sensory testing (QST) following the protocol of DFNS (German Research Network on Neuropathic Pain), using both thermal and mechanical nociceptive as well as non-nociceptive stimuli. Data distributions showed a systematic shift to hyperalgesia for nociceptive, and to hypoesthesia for non-nociceptive parameters. Across all parameters, 92% of the patients presented at least one abnormality. Thermosensory or mechanical hypoesthesia (up to 41%) was more frequent than hypoalgesia (up to 18% for mechanical stimuli). Mechanical hyperalgesias occurred more often (blunt pressure: 36%, pinprick: 29%) than thermal hyperalgesias (cold: 19%, heat: 24%), dynamic mechanical allodynia (20%), paradoxical heat sensations (18%) or enhanced wind-up (13%). Hyperesthesia was less than 5%. Every single sensory abnormality occurred in each neurological syndrome, but with different frequencies: thermal and mechanical hyperalgesias were most frequent in complex regional pain syndrome and peripheral nerve injury, allodynia in postherpetic neuralgia. In postherpetic neuralgia and in central pain, subgroups showed either mechanical hyperalgesia or mechanical hypoalgesia. The most frequent combinations of gain and loss were mixed thermal/mechanical loss without hyperalgesia (central pain and polyneuropathy), mixed loss with mechanical hyperalgesia in peripheral neuropathies, mechanical hyperalgesia without any loss in trigeminal neuralgia. Thus, somatosensory profiles with different combinations of loss and gain are shared across the major neuropathic pain syndromes. The characterization of underlying mechanisms will be needed to make a mechanism-based classification feasible.

Biopsy-diagnosed renal disease in patients after transplantation of other organs and tissues

Renal function deteriorates in about half of patients undergoing other transplants. We report the results of 105 renal biopsies from 101 nonrenal transplant recipients (bone marrow 14, liver 41, lung 30, heart 20). Biopsy indications were protracted acute renal failure (9%), creatinine increases (83%), heavy proteinuria (22%), or renal insufficiency before re-transplantation (9%). Histological findings other than nonspecific chronic changes, hypertension-related damage, and signs of chronic CNI toxicity included primary glomerular disease (17%), mostly after liver transplantation (21%) or after bone marrow transplantation (29%), and thrombotic microangiopathy (TMA) namely (10%). TMA had the most serious impact on the clinical course. Besides severe hypertension, one TMA patient died of cerebral hemorrhage, 5 had hemolytic-uremic syndrome, and 6 rapidly developed end-stage renal failure. TMA patients had the shortest kidney survival post-biopsy and, together with patients with acute tubular injury, the shortest kidney and patient survival since transplantation. Nine TMA patients had received CNI, 3 of them concomitantly received an mTOR-inhibitor. CNI toxicity is implicated in most patients with renal failure after transplant of other organs and may play a role in the development of TMA, the most serious complication. However, decreased renal function should not be routinely ascribed to CNI.

NMDA-receptor antagonist and morphine decrease CRPS-pain and cerebral pain representation

A combination therapy of morphine with an NMDA-receptor antagonist might be more effective than morphine without a NMDA-receptor antagonist for the relief of neuropathic pain in patients with complex regional pain syndrome (CRPS). In order to test the efficacy of this combination therapy we performed a double-blind randomized placebo-controlled study on patients suffering from CRPS of the upper extremity. We used functional magnetic resonance imaging during movement of the affected and unaffected upper hand before and after a treatment regimen of 49 days that contrasted morphine and an NMDA-receptor antagonist with morphine and placebo. We postulated superior pain relief for the combination therapy and concomitant changes in brain areas associated with nociceptive processing. Only the combination therapy reduced pain at rest and during movement, and disability. After treatment, activation in the contralateral primary somatosensory (cS1) and anterior cingulate cortex was significantly reduced when the affected hand was moved. Pain relief during therapy was related to decreased activation in cS1 and secondary somatosensory cortex (S2). Our data suggest that the combination of morphine with an NMDA-receptor antagonist significantly affects the cerebral processing of nociceptive information in CRPS. The correlation of pain relief and decrease in cortical activity in cS1 and S2 is in accordance with the expected impact of the NMDA-receptor antagonist on cerebral pain processing with emphasis on sensory-discriminative aspects of pain.

Miniaturized transportable evaporator for molecule deposition inside cryogenic scanning probe microscopes

Here, we present a very small evaporator unit suitable to deposit molecules onto a sample in a cryogenic environment. It can be transported in an ultrahigh vacuum system and loaded into Omicron-type cantilever stages. Thus, molecule deposition inside a low temperature force microscope is possible. The design features an insulating base plate with two embedded electrical contacts and a crucible with low power consumption, which is thermally well isolated from the surrounding. The current is supplied via a removable power clip. Details of the manufacturing process as well as the used material are described. Finally, the performance of the whole setup is demonstrated.

The monomer-to-dimer transition and bimodal growth of Co-salen on NaCl(001): a high resolution atomic force microscopy study

Molecules of Co-salen, a paramagnetic metal-organic Schiff base complex, self-assemble into two different well ordered morphologies on a NaCl(001) substrate: nanowires, which form networks, and compact nanocrystallites. Their growth can be controlled by adjusting the deposition parameters. It turns out that the nanowires are metastable. Molecular resolution images suggest that the packing in both morphologies is the same as in bulk Co-salen single crystals. Only the orientation of the c-axis with respect to the substrate is different. The origin of this intriguing bimodal growth is associated with a monomer-to-dimer transition, which probably takes place during initial nucleation at step edges.

Real-time tissue elastography versus FibroScan for noninvasive assessment of liver fibrosis in chronic liver disease

PURPOSE

Transient elastography (FibroScan, [TE]) and serum fibrosis markers such as the FibroTest (FT) are established methods for the noninvasive staging of liver fibrosis. A study using real-time elastography (HI-RTE), which is integrated in a conventional ultrasound system, was recently published with comparable results to transient elastography. The aim of the present study was to validate real-time elastography using the formulas calculated in previous studies and to compare the results to transient elastography and FibroTest for the noninvasive assessment of liver fibrosis.

MATERIALS AND METHODS

One hundred and thirty-four patients with chronic liver disease and either histological assessment of liver fibrosis (n = 112) or proven liver cirrhosis (n = 22) were included in the study. All patients received TE, HI-RTE, and biochemical evaluation on the same day as presentation. The calculation of the elasticity score of real-time elastography was performed in accordance with the two previously published studies.

RESULTS

The Spearman correlation coefficient between transient elastography, real-time elastography and FibroTest with the histological Chevallier score was statistically significant with 0.78, 0.34, and 0.67, respectively (p < 0.01). The diagnostic accuracy expressed as areas under ROC curves was 0.84, 0.69 and 0.85 for the diagnosis of significant fibrosis (F > or = 2), and 0.97, 0.65, and 0.83 for the diagnosis of cirrhosis, respectively.

CONCLUSION

Real-time elastography in its present form cannot replace transient elastography for noninvasive assessment of liver fibrosis.

Towards an understanding of the atomic scale magnetic contrast formation in NC-AFM: a tip material dependent MExFM study on NiO(001)

Recently, magnetic exchange force microscopy (MExFM) was established as a new force microscopy based technique capable of imaging arrangements of magnetic moments with atomic resolution on NiO(001). However, before this final achievement many unsuccessful experiments were performed on this particular sample system, and it is still not entirely clear which factors are important to attain an atomic scale magnetic contrast. Varying the tip's magnetic properties, we investigate the contrast formation on NiO(001). Fe-, Ni- and Gd-coated tips yielded a chemical contrast between Ni and O atoms, but a magnetic signal between Ni atoms with magnetic moments pointing in the opposite direction could only be observed with out-of-plane sensitive Fe-coated tips. Our observations suggest that three factors are crucial to obtain a sufficiently large magnetic signal: (i) a large overlap between the spin-carrying electronic states, (ii) a collinear orientation between the magnetic moments and (iii) a large magnetic moment.

[Current problems of kidney transplantation]

The long-term problems after kidney transplantation have changed considerably in recent years. While formerly immunosuppression and prevention of acute rejection were of prime concern, now attention focuses on chronic alterations of the transplanted organ and long-term survival of the patients. The transplantation procedure itself has evolved into a standardized technique with a high level of surgical quality. Problems involving organ preservation and ischemia/reperfusion damage also play a role, especially in view of chronic aspects. Monitoring of long-term complications should follow a program for the transplanted organ as well as a program for the patient. Monitoring kidney function should address the organ more precisely than has previously been the case. Serum creatinine level and proteinuria alone provide insufficient information and only change long after cellular deterioration has begun. Hence it is imperative that new testing methods be developed. One possibility is offered by protocol biopsies that allow histological and molecular analysis of the kidney at regular intervals. The patient programs concentrate on diagnostics and treatment of the cardiovascular diseases. Furthermore, the patients must be screened for occurrence of neoplasia. There are no prospective studies covering all cardiovascular risk factors after kidney transplantation. This pertains particularly to the subject of hypertension.

Probing the magnetic exchange forces of iron on the atomic scale

Applying magnetic exchange force microscopy with an Fe-coated tip, we experimentally resolve the atomic-scale antiferromagnetic structure of the Fe monolayer on W(001). On the basis of first-principles calculations, using an Fe nanocluster as a tip, we determine the distance dependence of the magnetic exchange forces. Significant relaxation of tip and sample atoms occurs, which depend sensitively on the local magnetic configuration. This shifts the onset of magnetic interactions toward larger separations and facilitates their observation. Implementing a multiatom tip in the calculations and accounting for relaxation effects are crucial to obtain the correct sign and distance dependence of the magnetic exchange interaction. By comparison with our calculations, we show that the experimentally observed contrast is due to a competition between chemical and magnetic forces.

Acute tubular injury in protocol biopsies of renal grafts: prevalence, associated factors and effect on long-term function

Acute tubular injury (ATI) is commonly observed in renal allografts, especially early after transplantation. This study analyzes prevalence and associated clinical conditions of ATI in serial protocol biopsies (pBx) and indication biopsies (iBx), and its impact on long-term graft function. 612 pBx from 204 patients taken at 6 weeks, 3 and 6 months, and 151 iBx performed within the first year of transplantation were evaluated. Prevalence of ATI in pBx was 40% (6 weeks), 34% (3 months) and 37% (6 months), and 46% in iBx. ATI was associated with delayed graft function and prolonged cold ischemia time in pBx, and with acute rejections in iBx. The GFR at 1 and 2 years after transplantation correlated inversely with the frequency of ATI in both pBx and iBx (p < 0.001). Prevalence of chronic changes at 6 months was not significantly related to ATI (patients without ATI: 36%, patients with multiple ATI findings: 54%). ATI is linked to inferior long-term graft function. While this suggests lack of recovery from ATI with permanent allograft damage, the underlying molecular mechanisms need yet to be uncovered. Prevention of the potential pathogenetic factors identified in this study might be the key point to attain good long-term graft function.