Neural correlates of temporal summation of second pain in the human brainstem and spinal cord

Temporal summation of second pain (TSSP) occurs when painful stimuli are presented repetitively (≥0.33 Hz) and results from a C‐fibre evoked enhancement (or “wind‐up”) of the dorsal horn neurons. Based on electrophysiological studies in intact animals, windup is considered a purely central phenomenon. With advancements in functional MRI (fMRI), we can now probe the central mechanisms of this pain response in humans. The aim of this study is to characterize the fMRI responses in the healthy human brainstem and spinal cord that correspond to TSSP. Functional MRI of healthy female adults (N = 15) was conducted while brief, repetitive heat pain stimuli were applied to the right thenar eminence (C6 dermatome), and TSSP (0.33 Hz) and control (0.17 Hz) heat pain paradigms were employed. The stimulus intensity was adjusted to each participant's heat pain sensitivity. Data were analyzed by means of a general linear model, and region‐of‐interest analyses. As predicted, participants demonstrated significant behavioural summation of pain in the TSSP condition. FMRI results identified enhanced activity in the spinal cord dorsal horn at C6 in response to the TSSP condition. Additionally, multiple areas of the brainstem (RVM and PAG) showed greater responses with the TSSP condition. These results suggest that, in humans, increased pain perception in the TSSP condition is reflected by greater responses in the dorsal horn and in regions known to play a role in the descending modulation of pain, which may modulate the spinal cord response. Hum Brain Mapp 36:5038–5050, 2015. © 2015 Wiley Periodicals, Inc.     

Immunization With Homologous Oxidized Low Density Lipoprotein Reduces Neointimal Formation After Balloon Injury in Hypercholesterolemic Rabbits

Objectives. In this study we tested the hypothesis that immunization with homologous oxidized low density lipoprotein (oxLDL) would inhibit the neointimal response to balloon injury in hypercholesterolemic rabbits.

Background. Immunization with homologous oxLDL has been shown to markedly reduce aortic atherosclerosis in LDL receptor-deficient as well as cholesterol-fed rabbits; however, the effect of this strategy on the balloon injury-induced neointimal lesion is unknown.

Methods. New Zealand White rabbits were immunized with 280 μg of homologous native LDL (n = 5), copper-oxidized LDL (n = 5) or phosphate buffer as control (n = 5) and fed a 1% cholesterol diet. Rabbits were reimmunized after 3 weeks, and balloon injury of the right ileofemoral artery was performed 1 week later. Four weeks after balloon injury, rabbits were killed, and the neointimal lesion area was measured by computerized morphometry after perfusion fixation of the arteries. Circulating antibodies against oxLDL were measured by enzyme-linked immunosorbent assay.

Results. In comparison with the control animals, those immunized with oxLDL had a 58% reduction in the neointimal area (0.53 ± 0.13 vs. 1.27 ± 0.26 mm²; p = 0.01). The group immunized with native LDL had a 19% reduction in the neointimal area compared with the control group (p = NS). Circulating cholesterol levels and antibody titers against oxLDL were comparable in the three groups. There was a trend toward reduced immunoreactivity for T cells and oxLDL in the neointima of oxLDL-immunized animals.

Conclusions. Hypercholesterolemic rabbits immunized with homologous oxLDL have a markedly reduced neointimal area after balloon injury despite severe hypercholesterolemia. Together with previous work, these data suggest that an immunization strategy (vaccination) against atherosclerosis and restenosis warrants further investigation.     

Calcified left ventricular aneurysm and non-atherosclerotic myocardial infarction in a child.

A 14-year-old boy, admitted with intractable chest pain, was found to have an enlarged heart and calcification in the apical region, with electrocardiographic features of massive inferolateral myocardial infarction. Left ventricular angiography revealed a large left ventricular aneurysm. He died following resection of the aneurysm and post mortem examination showed changes of a non-specific chronic myocarditis. A vasculitis involving small coronary arterioles was also found in the vicinity of the aneurysm, and the possibility of a rheumatic vasculitis was suggested by a transient episode of an erythema marginatum-like eruption. It is concluded that the association of infarction pattern on the electrocardiogram together with calcification of the heart in children is highly suggestive of a ventricular aneurysm secondary to a myocarditis or a vasculitis involving small, intramyocardial branches of the coronary arteries.     

Prenatal diagnosis of renal developmental anomalies associated with an empty renal fossa

Fetal kidneys are evaluated on routine obstetric ultrasounds; therefore, fetal renal developmental anomalies are frequently encountered with prenatal screening. Absence of the fetal kidney from its expected location generates a differential diagnosis that originates from the knowledge of the developmental origins of the kidneys. Many of the renal developmental anomalies demonstrate overlapping features in both symptoms and imaging appearance. We illustrate the pertinent findings of selected fetal renal anomalies in the setting of a unilateral empty renal fossa and suggest an algorithm for differentiating between the diagnoses. Discussed anomalies include horseshoe kidney, pelvic kidney, crossed fused renal ectopia, and renal agenesis.     

Delayed ileal-ileocystoplasty fistula formation: an unusual complication of augmentation enterocystoplasty

Augmentation enterocystoplasty is a successful treatment for patients with neurogenic bladder dysfunction. Delayed spontaneous bladder rupture is a serious recognised complication of the procedure; however, to our knowledge, delayed fistula formation between the neobladder and the gastrointestinal tract has not been reported in the literature. We report the case of a 21-year-old male who presented with chronic diarrhoea resulting from an ileal-ileocystoplasty fistula 10 years following a successful augmentation enterocystoplasty. Fistula formation is a possible complication of this procedure, and a high index of suspicion is required for patients presenting with diarrhoea who have previously undergone bladder augmentation surgery.     

Effects of rare non-target stimuli on brain electrophysiological activity and performance

In order to assess the effects of non-target stimuli on task performance and electrophysiological activity, 16 subjects performed reaction time (RT) experiments under 3 conditions. In all conditions, subjects had to press a button upon detection of rare (15%) target stimuli (1600 Hz) presented among frequent (85%) non-target stimuli. The 3 conditions differed based on their non-target stimuli. In one condition, the non-targets consisted of 'standard' stimuli (900 Hz). In the two other conditions, rare and deviant non-target stimuli were randomly added to the standard stimuli. These deviant non-target stimuli consisted of either constant (700-Hz tones) or novel (buzzes, filtered noises and other unusual sounds) stimuli. Both the rare target and non-target stimuli elicited P300, responses. Behavioral (RT) and electrophysiological (event-related potential) data showed that stimuli that followed standard stimuli were processed differently compared to stimuli that followed deviant non-target stimuli. In the conditions containing deviant non-target stimuli, the P3b to the target stimuli was smaller and later, and the mean RT longer than in the condition with no deviant stimuli. These behavioral and electrophysiological changes induced by the deviant non-target stimuli were discussed with reference to two factors, distraction and increased level of task difficulty. It was suggested that each of these factors were differentially sensitive to the novelty of the rare deviant stimuli.     

Gyriform infiltration as imaging biomarker for molecular glioblastomas

Journal of Neuro-Oncology - Molecular glioblastomas (i.e. without the histological but with the molecular characteristics of IDH-wild-type glioblastoma) frequently lack contrast enhancement, which...     

Intravenous digital subtraction arteriography in the evaluation of vascular grafts

Between 1982 and 1986 intravenous digital subtraction arteriography was used to evaluate vascular grafts in 97 patients (54 males, 43 females). Indications included recurrent symptoms, absent or diminished pulses, a drop in Doppler pressure measurements, and clinical uncertainty with respect to graft patency. Problems identified included graft stenosis, stenosis of the anastomosis or its distal vessels, false aneurysm, arteriovenous fistula and emboli. Forty-eight operations were carried out following intravenous digital subtraction arteriography, and radiographic findings were verified surgically. Twice, intravenous digital subtraction arteriography did not show significant graft findings which were discovered at surgery. Thus intravenous digital subtraction arteriography showed a sensitivity of 95.8% and specificity of 100%. Complications following intravenous digital subtraction arteriography were: two patients developed urticaria, and one superficial thrombophlebitis. There were no cases of pulmonary edema or death. In conclusion intravenous digital subtraction arteriography is very useful in the diagnosis of graft-related problems if done on a selective basis looking at graft and anastomosis site only, intravenous digital subtraction arteriography is done on an outpatient basis, has high sensitivity and specificity, good patient acceptance, is safe, fast and is less expensive than conventional arteriography.     

The influence of central haemodynamics on transcutaneous oxygen (TcpO2) measurements

Transcutaneous oxygen measurements (TcpO2) have been shown to be an index of tissue perfusion and it has been suggested that the main haemodynamic variable influencing tissue perfusion is cardiac output, assuming that inspired oxygen remains constant. To investigate this hypothesis we studied 23 consecutive patients in order to identify if changes in cardiac output correlated with similar changes in TcpO2 measurements. No correlation was found to suggest that cardiac output was the main haemodynamic determinant of TcpO2 measurements.