Surface plasmon polariton absorption modulator.

An electrically controlled ultra-compact surface plasmon polariton absorption modulator (SPPAM) is proposed. The device can be as small as a few micrometers depending on the required extinction ratio and the acceptable loss. The device allows for operation far beyond 100 Gbit/s, being only limited by RC time constants. The absorption modulator comprises a stack of metal/insulator/metal-oxide/metal layers, which support a strongly confined asymmetric surface plasmon polariton (SPP) in the 1.55 µm telecommunication wavelength window. Absorption modulation is achieved by electrically modulating the free carrier density in the intermediate metal-oxide layer. The concept is supported by proof-of-principle experiments.

Chronic stress-induced mechanical hyperalgesia is controlled by capsaicin-sensitive neurones in the mouse.

BACKGROUND: Clinical studies demonstrated peripheral nociceptor deficit in stress-related chronic pain states, such as fibromyalgia. The interactions of stress and nociceptive systems have special relevance in chronic pain, but the underlying mechanisms including the role of specific nociceptor populations remain unknown. We investigated the role of capsaicin-sensitive neurones in chronic stress-related nociceptive changes. METHOD: Capsaicin-sensitive neurones were desensitized by the capsaicin analogue resiniferatoxin (RTX) in CD1 mice. The effects of desensitization on chronic restraint stress (CRS)-induced responses were analysed using behavioural tests, chronic neuronal activity assessment in the central nervous system with FosB immunohistochemistry and peripheral cytokine concentration measurements. RESULTS: Chronic restraint stress induced mechanical and cold hypersensitivity and increased light preference in the light-dark box test. Open-field and tail suspension test activities were not altered. Adrenal weight increased, whereas thymus and body weights decreased in response to CRS. FosB immunopositivity increased in the insular cortex, dorsomedial hypothalamic and dorsal raphe nuclei, but not in the spinal cord dorsal horn after the CRS. CRS did not affect the cytokine concentrations of hindpaw tissues. Surprisingly, RTX pretreatment augmented stress-induced mechanical hyperalgesia, abolished light preference and selectively decreased the CRS-induced neuronal activation in the insular cortex. RTX pretreatment alone increased the basal noxious heat threshold without influencing the CRS-evoked cold hyperalgesia and augmented neuronal activation in the somatosensory cortex and interleukin-1α and RANTES production. CONCLUSIONS: Chronic restraint stress induces hyperalgesia without major anxiety, depression-like behaviour or peripheral inflammatory changes. Increased stress-induced mechanical hypersensitivity in RTX-pretreated mice is presumably mediated by central mechanisms including cortical plastic changes. SIGNIFICANCE: These are the first data demonstrating the complex interactions between capsaicin-sensitive neurones and chronic stress and their impact on nociception. Capsaicin-sensitive neurones are protective against stress-induced mechanical hyperalgesia by influencing neuronal plasticity in the brain.

[Correlation of autonomic neuropathy and retinal microangiopathy in diabetic children]. / Az autonóm neuropathia és retinális microangiopathia összefüggésének vizsgálata diabeteses gyermekekben.

The authors investigated the preclinical signs of autonomic neuropathy (resting heart rate, hyperventilatory arrhythmia, heart rate on standing/lying, orthostatic blood-pressure decrease) in 15 type I diabetic children with negative FLAG as well as a control group of 10 healthy children. In the diabetic group with negative FLAG as compared to control children the mean resting heart rate was significantly higher, the mean values of cardiovascular reflexes did not show significant differences, however in a third of these patients the narrowing of hyperventilatory arrhythmia was demonstrable. The differences of mean values of all the four investigated parameters in the group with positive FLAG comparing with the control group proved to be significant. According to their results the initial disturbances of the autonomic nervous system in childhood diabetes may appear relatively early--before the preclinical stage of retinal microangiopathy--showing the untimely dysfunction of the parasympathetic nervous system, on the other hand the signs relating to disturbance of the sympathetic nervous system (heart rate ratio on standing/lying, orthostatic blood-pressure decrease) become only in preclinical retinopathic children positive.

[Prognostic significance of retinal microaneurysm number and localization in type-1 diabetes mellitus]. / Retinalis microaneurysmák számának és lokalizációjának prognosztikai jelentósége 1-es típusú diabetes mellitusban.

The authors studied whether central retinal microaneurysm count predicts further progression of background retinopathy in juvenile onset type-1 diabetes mellitus. 94 patients (49 females and 45 males) were followed up longitudinally (8-17.5, mean 10 years) by evaluating fluorescein angiograms. Age at last examination was 17-32 years (mean age 22.4 years) and duration of diabetes was 8-22 years (mean duration 13.7 years). Microaneurysm counts and location were determined with the help of a grid consisting of three concentring circles and four radial lines (nine subfields) centered for the macula. 82% of the all microaneurysms were found inside the circle with 1500 micron radius. Participants were divided into three groups: those with no microaneurysms (1st group, n = 28) and those with 1-4 (2nd group, n = 35) and those with 5 or more microaneurysms (3rd group, n = 31) in the central circle with 600 micron radius at least one time during the whole follow up. Background retinopathy was found in 3 of 28 cases (approximately 10%) in the first group, 8 of 35 (approximately 23%) in the second group and in all the 31 patients (100%) in the third group. Proliferative retinopathy was found in the third group only. The authors suggest that the appearance of 5 or more microaneurysms in the macular area in type-1 diabetes mellitus may be sensitive indicator of the development of severe background and proliferative retinopathy. Study describes the importance of central microaneurysm count predicting further progression of background retinopathy could not be found in the available literature.

[Retinal microangiopathies in diabetic children and adolescents, occurring in cases of pubertal and prepubertal onset of diabetes]. / Cukorbeteg gyermekek és fiatalok retinalis microangiopathiájának alakulása prepubertális és pubertális betegségkezdet esetén.

The prevalence and development of retinal microvascular complications in pre-puberty and puberty onset insulin-dependent diabetes mellitus were studied in 109 young patients with an average follow-up of 6 years. The data suggest that the earlier childhood the diabetes began, the later the microvascular abnormalities could be found by fluorescein angiography. First signs of background retinopathy were seen in average 20--22 years of age, almost independently the age at onset of diabetes. Rapid progression of retinal vascular damage occurred mainly in postpubertal but not pubertal subjects. Diabetes with puberty onset meant worse prognosis in the respect of retinal vascular complications than pre-puberty onset. Good glycemic control would be achieved more difficult in subjects with puberty onset diabetes added to a changing hormonal balance. The authors suggest that psychological factors (altered behavior during and after puberty) and other problems of adolescents (changes in social, familial and working conditions) may also contribute to poor glycemic control. Though the effect of prepubertal duration on the risk of retinal complications appears to be smaller than later years, the attendant work in prepubertal years is as important as later.

[Connection between plasma thromboxane and prostacyclin levels in the metabolic control of diabetic children]. / A plazma thromboxan- és prostacyclinszint összefüggése cukorbeteg gyermekek anyagcsere kontrolljával.

Platelet poor plasma thromboxane and prostacyclin levels and the quantity of metabolic control, altogether with vascular complications were evaluated in 55 children diabetes mellitus. The control group consisted of 33 healthy children of the similar age. Thromboxane levels remained unchanged in diabetics, while prostacyclin proved to be significantly decreased, which resulted in greater thromboxane/prostacyclin ratio. No meaningful differences were found according to the presence or absence of vascular complications in this group of diabetics. A positive correlation could have been detected between glycosylated haemoglobin and thromboxane levels, while a negative one between glycosylated haemoglobin and prostacyclin levels. The alterations of prostaglandin metabolism may be regarded as a consequence of diabetic metabolic changes, rather than of vascular complications. Disturbed prostaglandin metabolism in diabetic children might have a role in the pathogenesis of vascular complications.

[Effect of puberty on the development of diabetic microangiopathy]. / Pubertás hatása a diabeteses microangiopathia alakulására.

Fluorescein angiography was used to follow the development of retinal microangiopathy at the time of puberty in 34 children with type I diabetes. When the results were compared with those for the control children who had suffered from the disease for a similar length of time, it was concluded that (in contrast with certain literature data) the process of sexual maturation does not essentially influence the development of retinal microangiopathy if the diabetes is maintained under good control for a long-lasting period. Appreciable roles in the rapid progression that is frequently observed in early adulthood are attributed to the sudden changes in the previously systematic living conditions (school, family, etc.).