Search

Continuous glucose measurements provide improved glycemic control and may prevent hypoglycemia and long-term complications of diabetes. One of the most promising techniques is the short-term implantation of electrochemical glucose sensors in subcutis. However, the inflammatory reaction to these sensors may lead to bioinstability of sensor measurements. The purpose of the present investigation was to examine factors contributing to the observed subcutaneous inflammatory reaction to an enzyme-based electrochemical glucose sensor for continuous glucose measurements. The sensor biocompatibility was assessed in vitro and in vivo.A toxicological assessment was performed on sensor materials and leachables, and the endotoxin content of sensors was determined by a Limulus amoebocyte lysate (LAL) test. Moreover, as a consequence of permanent penetration of the skin by the sensor the role of bacterial migration to the tissue was investigated. In vivo biocompatibility was investigated through histological examination of implanted sensor membranes for 3 days in pigs. Additionally, the effect of needle size and type (normal vs. inserter needle) on tissue trauma at sensor insertion was evaluated, and the healing of subcutis was assessed histologically from 3 to 14 days after removal of sensors.The toxicological assessment and the LAL test showed no concerns in a 3-day implantation scenario, and bacterial migration to the subcutis could not be detected. The histological examination showed that a reduction in needle size reduced the extent of inflammation to very low levels, and that the different sensor membranes showed similar extent and type of inflammation. Additionally, the extent of subcutaneous tissue reaction after removal of sensors declined gradually over time and returned to near-normal levels after 2 weeks.The electrochemical enzyme-based glucose sensor for continuous glucose measurements in subcutis is acceptable from a biocompatibility point of view. Reducing the inserter needle in size reduces the trauma induced at sensor implantation to neglible levels. Furthermore, the tissue reaction to the sensor returns to near-normal 2 weeks after the sensor has been removed following a 3-day implantation period.

Interleukin-19, 20, and 24 are new members of the IL-10 family binding and signaling through the IL-20R1/IL-20R2 heterodimer, while IL-20 and 24 also bind to the IL-20R2/IL-22R1 heterodimer. Using in situ hybridization we have studied mRNA expression of IL-19, 20, and 24 and their related receptor chains in skin from psoriatic patients before and during short-term treatment with either oral cyclosporine A or topical calcipotriol. In untreated lesions IL-19 and IL-20 mRNA was expressed focally in epidermis above the dermal papillae, whereas IL-24 was expressed in mononuclear cells in the dermal infiltrate. The expression of IL-19 and 20 mRNA was confined to the basal and suprabasal keratinocytes. No expression of IL-19 and 20 mRNA could be detected in uninvolved psoriatic skin. Treatment with cyclosporine A and calcipotriol resulted in disappearance of the IL-19 and 20 mRNA. Expression of mRNA for the receptor chains IL-20R1 and IL-20R2 was found throughout the psoriatic epidermal layer, whereas IL-22R1 mRNA was predominantly expressed in the superficial part of the psoriatic epidermis. These findings show that IL-19 and IL-20 are synthesized by a distinct population of keratinocytes. It remains to be clarified whether IL-19 and IL-20 are implicated in the pathogenesis of psoriasis.

Udgivelsesdato: 2009-Feb BACKGROUND: Interleukin (IL)-20 is a recently discovered cytokine displaying increased levels in psoriatic lesions. Interestingly, IL-20 levels decrease with antipsoriatic treatment, correlating with clinical improvement. However, the role of IL-20 in the aetiology of psoriasis is unknown. OBJECTIVES: In this study, we investigate the effects both of blocking IL-20 signalling in psoriatic plaques and of adding IL-20 to nonlesional psoriasis skin. METHODS: We employed the human skin xenograft transplantation model in which psoriatic plaques and nonlesional keratome skin biopsies obtained from donors with moderate to severe plaque psoriasis were transplanted on to immuno-deficient mice. The transplanted mice were treated with anti-IL-20 antibodies or recombinant human IL-20. RESULTS: We demonstrate that blocking IL-20 signalling with anti-IL-20 antibodies induces psoriasis resolution and inhibits psoriasis induction. We also demonstrate that continuous IL-20 infusion, together with injection of additional nonactivated leucocytes, promotes induction of psoriasis in nonlesional skin from patients with psoriasis. CONCLUSIONS: The results suggest that IL-20 plays a critical role in the induction and maintenance of psoriasis, and IL-20 is suggested as a new possible specific target in psoriasis treatment.

Lowering blood glucose concentration slows or prevents the development of complications in diabetes. One of the tools to control glucose levels is continuous glucose measurements. A promising technique involves measurements from glucose sensors implanted directly in skin/subcutis. However, in vivo bioinstability and drift in sensor signals have been reported after implantation, suggestively caused by the infiltration of inflammatory cells and adhesion of proteins to sensor membranes. The aim of this study was to evaluate the in vivo biocompatibility of two electrochemical glucose sensors after implantation in the skin of pigs.In vivo biocompatibility of in-house fabricated electrochemical glucose sensors and a commercially available continuous glucose monitoring system (CGMS, Medtronic MiniMed, Northridge, CA) implanted 1 h, 2 h, 24 h, 3 days, or 7 days was examined by histological and immunohistochemical techniques.The extent of inflammation increased significantly as a function of time. The inflammation ranged from an acute focal fibrinous/suppurative dermatitis to a chronic fibrinous and granulating foreign body dermatitis 7 days after implantation. Immunohistochemical stainings showed that heterophilic granulocytes, macrophages, and fibrinogen/fibrinogen fragments D and E were consistent findings. Infiltration of CD3epsilon-positive T-cells was primarily confined to day 7 of implantation. In addition, the pro-inflammatory cytokines interleukin-1 and tumor necrosis factor-alpha played a role in the reaction to sensors.The reported in vivo bioinstability of sensors is likely to be caused by protein and cellular biofouling on the sensor membrane. Furthermore, the consistent finding of fibrinogen and fibrinogen fragments D and E at the sensor-tissue interface seems to play an important role in the pathogenesis as it possibly maintains the inflammation by promoting the recruitment of inflammatory cells to the implantation site.

The effects of heparin and aminoguanidine on glomerular basement membrane thickening were studied in streptozotocin diabetic Sprague-Dawley rats. A placebo-treated group and a non-diabetic group served as controls. All diabetic rats remained severely hyperglycaemic (23 mmol/l) throughout the 8-month study period. At the end of this time relative kidney weight was significantly increased in diabetic control rats (4.9 +/- 0.5 g/kg b.w.) compared with non-diabetic rats (3.3 +/- 0.3 g/kg). This increase was not affected by the intervention treatments. Glomerular basement membrane thickness increased 32% in diabetic control rats (240 +/- 24 nm) compared with non-diabetic rats (182 +/- 20 nm). This increase was prevented by s.c. treatment with both unfractionated and low molecular weight heparins, while basement membrane thickness was the same in animals treated with oral heparins and aminoguanidine and untreated diabetic rats. Macroscopic malignant kidney tumours were seen in three aminoguanidine-treated rats. In conclusion, subcutaneously administered heparin prevents diabetes-induced glomerular basement membrane thickening.

Groups of 25 rats were fed either 0, 3, 10, 20, or 40% protein diets for 2 weeks and then given a single po dose of either 0, 0.15, or 0.75 ml/kg of carbon tetrachloride (CCl 4 ). There was a larger increase in the activity of ornithine carbamyl transferase, glutamic dehydrogenase, sorbitol dehydrogenase, fructose-1-phosphate aldolase and glutamicpyruvic transaminase in plasma from CCl 4 -dosed rats fed protein-free diets than those fed 10% protein diets. The increase in the activity of GPT in plasma was larger for rats fed 40% protein diets than for those fed 10% protein diets. Centrilobular necrosis was most extensive in the liver of rats fed the protein-free diet; in rats dosed with 0.75 ml/kg, there was more liver necrosis in groups fed 0 and 40% protein diets. Rats fed 0 or 3% protein diets and dosed with CCl 4 had fewer large liver cells with hydropic degeneration than those fed higher protein diets. The group fed the protein-free diet had the fewest number of large lipid droplets. Considering all the results, the rats fed 0, 3, and 40% protein diets appeared to be more susceptible to the toxic effects of CCl 4 .

The pig has a diffuse epitheliochorial placenta. The foeto-maternal surface area (Sv(F), Sv(M)) is enlarged at three levels: level I: macroscopic folds of uterine mucosa covered by foetal membranes; level II: light microscopic folds of uterine epithelium covered by trophoblastic epithelium; level III: ultrastructural formation of both maternal and foetal microvilli in an interdigitating pattern. This study presents a morphometric method, using intersection counting, to estimate the surface area of these interdigitating, highly oriented microvilli at level III, i.e. the 'true' surface exchange area. The method is applied to different stages in pregnancy. The epithelial surfaces are enlarged by a factor 8-11 due to the formation of microvilli. This factor varies during pregnancy, being lower early in gestation and before delivery, and for the first time it is shown to be significantly different for mother and foetus. At level III the foetal surface of placenta is larger than the maternal indicating that the two opposing surfaces are not congruent at the ultrastructural level and that membrane-linked placental transport may be different in mother and foetus. A three-compartment model is suggested for placental exchange with maternal, intermicrovillous and foetal compartments.

Placentae from nine sows covering gestational stages from 33 to 112 days were examined by light and electron microscopy. Deeply stainable electron-dense histiotrophe was demonstrated in the interareolar placenta. Focal accumulations of cell debris with profiles of organelles were demonstrated in the intermicrovillous space between uterine epithelium and trophoblast. In addition, small expansions of amorphous histiotrophe were found between the microvilli. Furthermore, histiotrophe with profiles of cytomembranes was shown in intercellular spaces in columnar trophoblast between the microvillar border and tight junctions. Dense bodies were demonstrated in the uterine epithelium, and endocytic vesicles and branched tubular structures with dense contents were found in the columnar trophoblast. It is concluded that focal accumulations of cell debris are derived from degenerating epithelial cells in the endometrium and chorion, and that amorphous histiotrophe arises by secretory activity of uterine epithelium. It is further concluded that the histiotrophe is absorbed by columnar trophoblast of the chorionic fossae.

Summary A method for vascular perfusion in vivo, especially for EM fixation, was developed with theporcine placenta. The effect of fixation at varying parameters was studied. Nine multiparous Danish Landrace sows ranging in gestation from 33 to 112 days and in body weight from 160 to 257 kg were used. After general and local anaesthesia laparotomy was undertaken on the left flank and the uterine horn was perfused through a. uterina with buffered glutaraldehyde. Local perfusion through a. umbilicalis was undertaken in one case, and installation of concentrated glutaraldehyde into the allantoic cavity was performed in five cases. Perfusion-fixed and fresh tissue samples were fixed in OsO 4 and processed for electron microscopy. The osmolarity of the buffer was varied between 470 and 660 mOsm. At high tonicity the cytoplasm was well preserved but the intercellular spaces of the uterine epithelium were dilated. At about 575 mOsm the preservation was still good and the spaces were occluded. At lower tonicity damage occurred in the cytoplasm. The trophoblast was generally better preserved than the uterine epithelium. A rapid perfusion flow was beneficial for fixation.

Subcutaneously-implanted glucose sensors for continuous glucose monitoring have the potential to replace serial blood glucose measurements. The objective of the present study was to test whether continuous glucose measurements could be obtained with glucose sensors implanted in the subcutis of pigs. Moreover, the in vivo biocompatibility of the sensors was evaluated since an inflammatory reaction may lead to drift in sensor-signaling.Two types of glucose sensor were implanted for 3 days in the subcutis of hyperglycemic pigs. The plasma glucose concentration was correlated to the sensor outputs, and tissue was sampled for histological evaluation.There was a good correlation between the interstitial fluid and blood glucose levels. However, there was a statistical significantly difference in linearity from days 0 and 1 to day 2 (p0.001) and variations in the sensitivity and background current of individual sensors were observed over time. The tissue reaction caused by the sensors was a mild focal subacute fibrinous dermatitis.Continuous glucose measurement can be achieved by glucose sensors implanted in the subcutis of pigs. The observed drift in sensor signals over time may have been caused by heterophils, macrophages and/or fibrinogen at the tissue-sensor interface.