Ischemic preconditioning ameliorates spinal cord ischemia-reperfusion injury by triggering autoregulation

OBJECTIVE

The mechanism underlying ischemic preconditioning (IPC) protection against spinal cord ischemia-reperfusion (I/R) injury is unclear. We investigated the role of spinal cord autoregulation in tolerance to spinal cord I/R injury induced by IPC in a rat model.

METHODS

Sprague-Dawley rats were randomly assigned to four groups. IPC (P) group animals received IPC by temporary thoracic aortic occlusion (AO) with a 2F Fogarty arterial embolectomy catheter (Baxter Healthcare, Irvine, Calif) for 3 minutes. The I/R injury (I/R) group animals were treated with blood withdrawal and temporary AO for 12 minutes, and shed blood reinfusion at the end of the procedures. The P+I/R animals received IPC, followed by 5 minutes reperfusion, and then I/R procedures for 12 minutes. Sham (S) group animals received anesthesia and underwent surgical preparation, but without preconditioning or I/R injury. Neurologic function on postprocedure days 1, 3, 5, and 7 was evaluated by Tarlov scoring. Lumbar segments were harvested for histopathologic examination on day 7. To evaluate the role of autoregulation in IPC, spinal cord blood flow and tissue oxygenation were continuously monitored throughout the procedure duration.

RESULTS

The Tarlov scores in the I/R group were significantly lower than those in the S, P, and P+I/R groups on days 1, 3, 5, and 7 (P < .001). No significant differences were noted between the S, P, and P+I/R groups. The numbers of surviving motor neurons in the S, P, and P+I/R groups were significantly higher than those in the I/R group (P < .001); however, the number of surviving motor neurons did not differ between the S, P, and P+I/R groups. The P group exhibited higher spinal cord blood flow (P = .001-.043) and tissue oxygenation (P = .032-.043) within the first 60 minutes after reperfusion than the S group. The P+I/R group exhibited higher spinal cord blood flow (P = .016-.045) and tissue oxygenation (P = .001-.038) within the first 60 minutes after reperfusion than the I/R group.

CONCLUSIONS

IPC ameliorates spinal cord I/R injury in rats, probably mediated by triggering spinal cord autoregulation and improving local spinal cord blood flow and tissue oxygenation. This concept may be the new therapeutic targets in patients requiring aortic surgery.

Variations in the point spread function characteristics of wavelengths for a wavefront coding imaging system

The point spread function (PSF) characteristics of wavelengths for a wavefront coding imaging system are investigated. Although the phase delayed by the mask changes with wavelength, the shape of the PSF is nearly invariant with respect to wavelength. However, the position of the PSF shifts with axial chromatic aberration. If the wideband light is separated into several channels and separated channel images are restored using the same filter, then color traces may be observed in the recombined color images.

Molecular biomarker of inflammatory response is associated with rebleeding in spontaneous intracerebral hemorrhage

BACKGROUND AND PURPOSE

Rebleeding in spontaneous intracerebral hemorrhage (ICH) is a major cause of morbidity and mortality among stroke survivors. Due to the links between inflammation and rebleeding, we hypothesized that the biomarkers of inflammation are associated with the pathogenesis of rebleeding in ICH. We sought to investigate whether these biomarkers and clinical variables on admission can provide prognostic information on the risk of rebleeding.

METHODS

This prospective study enrolled 59 consecutive patients with spontaneous ICH. We determined the concentrations of interleukin-10 (IL-10), intercellular adhesion molecule-1, and complement 3 in blood samples obtained on admission.

RESULTS

Univariate analysis indicated that hematoma volume, leukocyte count, hydrocephalus, and plasma IL-10 levels were associated with rebleeding. Multivariate logistic regression analysis indicated that hydrocephalus (95% CI of OR, 1.6-26.7) and IL-10 (95% CI of OR, 1.03-1.22) were independently associated with an increased probability of rebleeding.

CONCLUSION

These data suggest that IL-10, a molecular biomarker of inflammatory response in the early acute phase of ICH, is associated with subsequent rebleeding.

Chronic treatment with a glucagon receptor antagonist lowers glucose and moderately raises circulating glucagon and glucagon-like peptide 1 without severe alpha cell hypertrophy in diet-induced obese mice

AIMS/HYPOTHESIS

Antagonism of the glucagon receptor (GCGR) represents a potential approach for treating diabetes. Cpd-A, a potent and selective GCGR antagonist (GRA) was studied in preclinical models to assess its effects on alpha cells.

METHODS

Studies were conducted with Cpd-A to examine the effects on glucose-lowering efficacy, its effects in combination with a dipeptidyl peptidase-4 (DPP-4) inhibitor, and the extent and reversibility of alpha cell hypertrophy associated with GCGR antagonism in mouse models.

RESULTS

Chronic treatment with Cpd-A resulted in effective and sustained glucose lowering in mouse models in which endogenous murine Gcgr was replaced with human GCGR (hGCGR). Treatment with Cpd-A also led to stable, moderate elevations in both glucagon and glucagon-like peptide 1 (GLP-1) levels, which were completely reversible and not associated with a hyperglycaemic overshoot following termination of treatment. When combined with a DPP-4 inhibitor, Cpd-A led to additional improvement of glycaemic control correlated with elevated active GLP-1 levels after glucose challenge. In contrast to Gcgr-knockout mice in which alpha cell hypertrophy was detected, chronic treatment with Cpd-A in obese hGCGR mice did not result in gross morphological changes in pancreatic tissue.

CONCLUSIONS/INTERPRETATION

A GRA lowered glucose effectively in diabetic models without significant alpha cell hypertrophy during or following chronic treatment. Treatment with a GRA may represent an effective approach for glycaemic control in patients with type 2 diabetes, which could be further enhanced when combined with DPP-4 inhibitors.

Delayed subdural hematoma after epidural blood patching in a patient with spontaneous intracranial hypotension--case report

A 51-year-old woman presented with a rare case of spontaneous intracranial hypotension (SIH) complicated by a delayed subdural hematoma (SDH) that required surgical evacuation 2 months after epidural blood patching (EBP). Subdural fluid collections are common among patients with SIH. These fluid collections vary in appearance from thin subdural hygromas to rare large SDHs associated with significant mass effect. Most subdural fluid collections can be safely managed by conservative treatment or EBP. The present clinical course and imaging findings illustrate the possible sequential complications of EBP in patients with SIH.

[The characteristics of multicolor imaging system for logarithmic wavefront coding]

The wavefront coding extension the depth of field (DOE) of an imaging system is by insert a phase plate into the pupil plane of a spatially incoherent imaging system, the encoded image can be digitally restored to produce a final image with improved depth dependent detail. To study the multicolor imaging performance of a logarithmic wavefront coding system, the phase and chromatic aberration variation with wavelength are analyzed, and characteristics such as shape, distribution and width of two wavelengths' PSF are compared. The research results show that if the chromatic aberration is excellently corrected then the technology can be used for multicolor even broadband spectrum DOE imaging system. Otherwise, the encode image can not be effectively decoded.

Sacroiliac joint pain after lumbar and lumbosacral fusion: findings using dual sacroiliac joint blocks

OBJECTIVE

The present study was performed to ascertain whether sacroiliac joint (SIJ) pain represents a potential source of pain in patients who have undergone lumbar or lumbosacral fusions.

DESIGN

Prospective cohort study.

PATIENTS AND METHODS

Between June 2007 and June 2009, 130 patients who underwent lumbar or lumbosacral fusions were evaluated for SIJ pain. Fifty-two patients for whom positive findings were obtained on at least three of the provocating tests for SIJ pain were selected to receive dual diagnostic blocks.

OUTCOME MEASURES

A positive response was defined as characteristic pain reduction of 75% for 1-4 hours following the SIJ blocks. Predictive factors for a positive response to the SIJ blocks were also investigated.

RESULTS

Among the 52 patients, 21 were considered to have SIJ pain on the basis of two positive responses to diagnostic blocks. Univariate analysis revealed that the predictive factors related to positive responses were unilateral pain (P = 0.002), more than three positive responses to provocating maneuvers (P = 0.02), and postoperative pain with characteristics different from those of preoperative pain (P = 0.04).

CONCLUSIONS

SIJ pain is a potential source of pain after lumbar and lumbosacral fusion surgeries. Provocating SIJ maneuvers represent reliable tests for SIJ pain. The characteristics of postoperative SIJ pain frequently differ from those of preoperative pain.

Fabrication and Nanostructured Surface Layers of Al Alloy by Surface Vibrational Mechanical Attrition

Nanograins were introduced into the surface layers of an Al-alloy during surface vibrational mechanical attrition. Transmission electron microscopy revealed that microstructures developed with an increase in strain, in the following sequence, i.e., lamellar microbands of elongated subgrains, equiaxed submicro-, and nano-grains respectively. The grain subdivision into the subgrains was found to be the main mechanism responsible for grain refinement. The simultaneous evolution of high boundary misorientations was ascribed to the boundary rotation for accommodating further strains. Results showed that the grains could refine remarkably into the nanometer regime (<100 nm) within the outer surface of the layer. The depth of the nanocrystal layers increased and the grain size decreased with the extension of processing time. The nanocrystal layers evidenced an increase in hardness.