Laser Doppler Blood Flowmetry Research Articles

Using dynamic analysis of Laser-Doppler blood flowmetry to measure nasal mucosa bloody flow in postural changes

Using dynamic analysis of Laser-Doppler blood flowmetry to measure nasal mucosa bloody flow in postural changes

Abstract 8572: Enhanced Angiogenesis By Transplantation Of iPS Cell-derived Flk-1 + Cell Sheet Created By A Novel Magnetic Tissue Engineering Method

Background: Therapeutic angiogenesis using cell transplantation represents a novel strategy for severe ischemic diseases, but some patients had poor response to angiogenic cell therapy. Therefore, alternative cell source and cell application strategy have been extensively searched. Induced pluripotent stem cells are expected as one of powerful tools for regenerative medicine. We investigated a therapeutic potential of iPS cell sheet created by a novel magnetite tissue engineering technology for reparative angiogenesis. Methods and Results: Flk-1 + cells, as a vascular progenitor marker were induced from mouse iPS cells after 5 day of culture. Flk-1 + cells were purified by FACS sorting, and these cells differentiated into CD31 + endothelial and α-SMA + smooth muscle cells. Sorted Flk-1 + cells incubated with magneticnanoparticle-containing liposomes (MCLs) were cultured. MCL-labeled Flk-1 + cells were mixed with diluted extracellular matrix (ECM) precursor, and a magnet was placed on the reverse side. Magnetized iPS cell-derived Flk-1 + cells formed multilayered cell sheet after 24h incubation period. Nude mice were subjected to unilateral hind limb ischemia and separated into 3 groups. The constructed Flk-1 + cells- or Flk-1 − cells- sheet placed on the ischemic adductor muscles using the Alnico magnet before skin closure. For the control group, ECM precursor gel was layered onto the ischemic tissues. Blood flow recovery and the extent of angiogenesis were assessed by a laser doppler blood flowmetry and capillary density. The Flk-1 + cell sheet group had a greater angiogenesis in ischemic tissues compared to the control and Flk-1 − cells sheet groups (p<0.05). The angiogenic and tissue-preserving effects of Flk-1 + cell sheets were attributable to an increased expression of VEGF mRNA in ischemic tissues. We did not detect formation of any tumors in Flk-1 + cells, but not in Flk-1 − cells, transplanted mice at least until post-operative day 60. Conclusions: Implantation of iPS cell-derived Flk-1 + cells has augmented ischemia-induced angiogenesis. iPS cell-derived Flk-1 + cell sheet created by the novel magnetic nanoparticle-based tissue engineering technology would represent a new modality for therapeutic angiogenesis and tissue regeneration.

Daikenchuto (TU-100) ameliorates colon microvascular dysfunction via endogenous adrenomedullin in Crohn’s disease rat model

Daikenchuto (TU-100), a traditional Japanese medicine, has been reported to up-regulate the adrenomedullin (ADM)/calcitonin gene-related peptide (CGRP) system, which is involved in intestinal vasodilatation. The microvascular dysfunction of the intestine in Crohn's disease (CD), due to down-regulation of the ADM/CGRP system, is etiologically related to the recurrence of CD. Therefore, we investigated the vasodilatory effect of TU-100 in a CD rat model. Colitis was induced by the rectal instillation of 2,4,6-trinitrobenzenesulfonic acid (TNBS) in rats. Laser Doppler blood flowmetry was used to measure colonic blood flow. ADM, CGRP, and their receptors in the ischemic colon were measured by reverse transcription polymerase chain reaction (RT-PCR) and enzyme immunoassays. Additionally, we determined whether the intestinal epithelial cell line IEC-6 released ADM in response to TU-100. TU-100 increased blood flow in ischemic segments of the colon but not in hyperemic segments. Pretreatment with an antibody to ADM abolished the vasodilatory effect of TU-100. CGRP levels and βCGRP mRNA expression were decreased in the ischemic colon, while protein and mRNA levels of ADM were unchanged. Hydroxy α-sanshool, the main constituent of TU-100, was the most active component in improving blood flow. Additionally, both TU-100 and hydroxy α-sanshool enhanced the release of ADM from IEC-6 cells. In the ischemic colon, endogenous βCGRP, but not ADM, was decreased. Thus, it was concluded that TU-100 ameliorated microvascular dysfunction by the up-regulation of endogenous ADM in the CD rat model. TU-100 may be a possible therapeutic agent for gastrointestinal ischemia-related diseases including CD.

Enhanced Angiogenesis by Transplantation of Mesenchymal Stem Cell Sheet Created by a Novel Magnetic Tissue Engineering Method

Therapeutic angiogenesis with cell transplantation represents a novel strategy for severe ischemic diseases. However, some patients have poor response to such conventional injection-based angiogenic cell therapy. Here, we investigated a therapeutic potential of mesenchymal stem cell (MSC) sheet created by a novel magnetite tissue engineering technology for reparative angiogenesis. Human MSCs incubated with magnetic nanoparticle-containing liposomes were cultured, and a magnet was placed on the reverse side. Magnetized MSCs formed multilayered cell sheets according to magnetic force. Nude mice were subjected to unilateral hind limb ischemia and separated into 3 groups. For the control group, saline was injected into ischemic tissue. In the MSC-injected group, mice received magnetized MSCs by conventional needle injections without sheet formula as a control cell group. In the MSC-sheet group, MSC sheet was layered onto the ischemic tissues before skin closure. Blood flow recovery and the extent of angiogenesis were assessed by a laser Doppler blood flowmetry and histological capillary density, respectively. The MSC-sheet group had a greater angiogenesis in ischemic tissues compared to the control and MSC-injected groups. The angiogenic and tissue-preserving effects of MSC sheets were attributable to an increased expression of vascular endothelial growth factor and reduced apoptosis in ischemic tissues. In cultured MSCs, magnetic labeling itself inhibited apoptosis via a catalase-like antioxidative mechanism. MSC sheet created by the novel magnetic nanoparticle-based tissue engineering technology would represent a new modality for therapeutic angiogenesis and tissue regeneration.

Nailfold capillaroscopy and blood flow laser-doppler analysis of the microvascular damage in systemic sclerosis: preliminary results

Systemic sclerosis (SSc) is characterized by altered microvascular structure and function. Nailfold videocapillaroscopy (NVC) is the tool to evaluate capillary morphological structure and laser-Doppler Blood flowmetry (LDF) can be used to estimate cutaneous blood flow of microvessels. The aim of this study was to investigate possible relationships between capillary morphology and blood flow in SSc. Twenty-seven SSc patients and 12 healthy subjects were enrolled. SSc microvascular involvement, as evaluated by NVC, was classified in three different patterns ("Early", "Active", "Late"). LDF analysis was performed at the II, III, IV, V hand fingers in both hands and both at cutaneous temperature and at 36 degrees C. Statistical evaluation was carried out by non-parametric procedures. Blood flow was found significantly lower in SSc patients when compared with healthy subjects (p<0.05). The heating of the probe to 36 degrees C induced a significant increase in peripheral blood flow in all subjects compared to baseline (p <0.05), however, the amount of variation was significantly lower in patients with SSc, compared with healthy controls (p <0.05). The SSc patients with NVC "Late" pattern, showed lower values of peripheral blood flow than patients with NVC "Active" or "Early" patterns (p<0.05). Moreover, a negative correlation between the tissue perfusion score and the progression of the SSc microangiopathy was observed, as well as between the tissue perfusion and the duration of the Raynaud's phenomenon (p <0.03). LDF can be employed to evaluate blood perfusion in the microvascular circulation in SSc patients. The blood flow changes observed with the LDF seem to correlate with the severity of microvascular damage in SSc as detected by NVC.

Therapeutic angiogenesis by transplantation of induced pluripotent stem cell-derived Flk-1 positive cells

BackgroundInduced pluripotent stem (iPS) cells are the novel stem cell population induced from somatic cells. It is anticipated that iPS will be used in the expanding field of regenerative medicine. Here, we investigated whether implantation of fetal liver kinase-1 positive (Flk-1+) cells derived from iPS cells could improve angiogenesis in a mouse hind limb model of ischemia.ResultsFlk-1+ cells were induced from iPS cells after four to five days of culture. Hind limb ischemia was surgically induced and sorted Flk-1+ cells were directly injected into ischemic hind limbs of athymic nude mice. Revascularization of the ischemic hind limb was accelerated in mice that were transplanted with Flk-1+ cells compared with control mice, which were transplanted with vehicle, as evaluated by laser Doppler blood flowmetry. Transplantation of Flk-1+ cells also increased expression of VEGF mRNA in ischemic tissue compared to controls.ConclusionsDirect local implantation of iPS cell-derived Flk-1+ cells would salvage tissues from ischemia. These data indicate that iPS cells could be valuable in the therapeutic induction of angiogenesis.

Laser-Doppler Examination of the Blood Supply in Pericranial Flaps

The purpose of this investigation was to determine if there is evidence suggestive of blood flow within pericranial flaps. An index of blood flow using laser-Doppler blood flowmetry was obtained in pericranial flaps from 10 patients who were undergoing a coronal flap for reconstructive procedures. The data were analyzed using fast Fourier transformation to indicate the presence or absence of blood flow. All but 1 pericranial flap showed evidence of blood flow within. Most flaps had blood flow even several centimeters distal to the origin of the flaps' pedicles. The data clearly indicate that pericranial flaps contain at least some blood flow. However, the quantity of blood flow could not be assessed using this technology.

Anti‐inflammatory activity of Pseudopterosins by laser doppler blood flow evaluation

IFSCC Magazines, 12 (2009) (1) 17–29Pseudopterosins extracted from Caribbean Sea Whip (Pseudopterogorgia elisabethae) were previously shown to inhibit phospholipase A2, an enzyme that functions in the arachidonic acid cascade of inflammation. With an objective to test its in vivo anti‐inflammatory potential, we conducted a screening clinical bioassay using randomized analysis on sixteen panelists. An emulsion containing 0.02% of sea whip extract was applied to the volar forearm of subjects prior to or after an ethyl nicotinate challenge. Blood flow rate at the application site monitored using a laser doppler blood flowmeter served as a measure of inflammation induced by ethyl nicotinate. Upon post‐challenge treatment, sea whip extract reduced blood flow by 35.04% against untreated control and also delayed the blood flow. More pronounced reduction in blood flow, as low as 59.50%, was noted upon pretreatment. This reduction was significant (P &lt; 0.0095). Pretreatment caused not only a delay in onset of inflammation but also a reduction in the peak time of blood flow. This study further substantiates the previously reported in vitro anti‐inflammatory effect of sea whip extract, demonstrating its activity in deep skin layers by affecting blood flow. The preventive application prior to induction of inflammation was more effective when compared to post‐treatment.Keywords: Anti‐inflammatory, clinical study, laser doppler blood flowmetry, pseudopterosins

OPTICAL IMAGING AND SPECTROSCOPY OF SUPERFICIAL TISSUE

An overview of three techniques developed by our group for imaging superficial tissue is presented. Firstly, a novel polarized light capillaroscope has been developed for imaging the microcirculation. The capillaroscope has been used to make in vivo measurements of sickle cell disorder sufferers with aim of monitoring the polymerization of sickled red blood cells. Secondly, hyperspectral imaging for measuring oxygen saturation is described. The accuracy of such measurements is affected by the non-linear relationship between scattering and absorption and it is demonstrated that polarization techniques can be used to make the relationship more linear, thus improving accuracy. Finally, the use of smart CMOS optical sensors for laser Doppler blood flowmetry is described. A 32 × 32 pixel imaging array with on-chip processing is described and the potential for full field laser Doppler blood flow imaging is demonstrated through measurement on blood flow of tissue before and after occlusion.

Role of Bradykinin, Nitric Oxide, and Angiotensin II Type 2 Receptor in Imidapril-Induced Angiogenesis

The angiotensin II (Ang II)-Ang II type 1 receptor pathway is proangiogenic, whereas studies showed that some angiotensin-converting enzyme inhibitors also stimulate angiogenesis in the setting of tissue ischemia, leaving a controversy of Ang II-mediated angiogenesis. We investigated whether an angiotensin-converting enzyme inhibitor imidapril-induced angiogenesis might be mediated via the tissue bradykinin pathway. To rule out the conventional effects of Ang II on angiogenesis, we used Ang II type 1a receptor knockout (AT1aKO) mice. We examined the effects of the angiotensin-converting enzyme inhibitor imidapril on angiogenesis in a hindlimb ischemia model using AT1aKO mice. After induction of hindlimb ischemia, AT1aKO mice were treated with or without imidapril (1.0 or 0.1 mg/kg per day for 21 days). Angiogenesis was quantified by laser Doppler blood flowmetry and capillary density. Angiogenesis was reduced in AT1aKO mice compared with wild-type mice. Imidapril with either low or high doses enhanced angiogenesis in AT1aKO mice (P<0.01). Ang II type 2 receptor antagonist (PD123319; 30 mg/kg per day) and B1 receptor antagonist (DesArg9-[Leu8]-bradykinin; 50 nmol/kg per day) suppressed the imidapril-induced angiogenesis in AT1aKO mice to an extent even lower than that of nontreated AT1aKO mice. B2 receptor antagonist (Hoechst 140; 100 microg/kg/d) and NO synthase inhibitor (N(G)-nitro-L-arginine methyl ester; 20 mg/kg per day) moderately attenuated the imidapril-mediated angiogenesis. RT-PCR revealed that vascular endothelial growth factor receptor 2 mRNA was reduced with PD123319, DesArg9-[Leu8]-bradykinin, or Hoechst 140, and vascular endothelial growth factor mRNA abundance was suppressed with PD123319 or DesArg9-[Leu8]-bradykinin. In conclusion, imidapril elicited angiogenesis in the setting of tissue ischemia in AT1aKO mice. This angiogenic effect might involve the Ang II-Ang II type 2 receptor pathway in addition to the bradykinin-B1 and bradykinin-B2 receptor/NO-dependent pathways.

Age-related changes of pulpal blood flow in primary teeth measured by laser Doppler blood flowmetry

The purpose of the present study was to examine age-related change of the pulpal blood flow (PBF) in human primary teeth. PBF of 21 healthy upper primary central incisors in 12 children (age: 3 years 11 months–7 years 3 months) was measured by laser Doppler flowmetry (LDF). Recordings were made with and without opaque black rubber dam application. On 10 of the examined teeth, repeated measurements were made on different occasions: twice on 4 teeth (3 subjects) and 3 times on 6 teeth (3 subjects). The results obtained were as follows: PBF with dam application was significantly decreased with increasing age of the subjects ( P < 0.05, Spearman ranks order correlation, n = 21). In the repeated measurements, PBF showed a tendency of decrease with age. These results indicate that PBF in human primary incisors is reduced with age.

Age-related changes of pulpal blood flow in primary teeth measured by laser Doppler blood flowmetry

Age-related changes of pulpal blood flow in primary teeth measured by laser Doppler blood flowmetry

Ischemia-induced angiogenesis: role of inflammatory response mediated by P-selectin

P-selectin is a 140-kDa glycoprotein expressed on endothelial cells and platelets. P-selectin mediates the tethering and rolling of leukocytes along the endothelium, an early step of leukocyte extravasation. Although inflammation is a requisite process for ischemia-induced angiogenesis, little is known regarding the role of P-selectin in angiogenesis in the setting of tissue ischemia. We examined whether ischemia-induced angiogenesis is altered in P-selectin knockout (P-selectin(-/-)) mice. Angiogenesis was evaluated in a surgically induced hind-limb ischemia model using laser Doppler blood flowmetry (LDBF) and histological capillary density (CD). After left hind-limb ischemia, the ischemic/normal limb LDBF ratio was persistently lower in P-selectin(-/-) mice compared with wild-type (WT) mice. CD was also significantly lower in P-selectin(-/-) mice than in WT mice on Postoperative Day 14. Fewer numbers of total CD45+ inflammatory leukocytes infiltrated into the ischemic tissues in P-selectin(-/-) mice than in WT mice, and immunohistochemical analysis revealed the number of infiltrated leukocytes expressing vascular endothelial growth factor was also decreased in P-selectin(-/-) mice. P-selectin mRNA expression was augmented after hind-limb ischemia in WT mice. In conclusion, P-selectin may play an important role in ischemia-induced angiogenesis by promoting early inflammatory mononuclear cell infiltration. P-selectin would become one possible target molecule for modulating inflammatory angiogenesis.

Therapeutic Angiogenesis With Intramuscular Injection of Low-Dose Recombinant Granulocyte-Colony Stimulating Factor

In vivo administration of granulocyte colony-stimulating factor (G-CSF) has been shown to facilitate regeneration of cardiovascular tissues. However, G-CSF causes marked leukocytosis that potentially induces adverse cardiovascular events. Earlier studies showed that G-CSF had direct stimulatory actions on mature endothelial cells, resulting in promotion of angiogenesis. We thus examined whether low doses of recombinant human G-CSF (rhG-CSF) locally injected into ischemic tissues would stimulate angiogenesis without inducing severe leukocytosis. Reverse-transcription polymerase chain reaction (PCR) revealed expression of G-CSF receptor in human umbilical vein endothelial cells (HUVECs). rhG-CSF (100 ng/mL) enhanced migration and tube formation but not proliferation of HUVECs in vitro. We then examined the effects of rhG-CSF on angiogenesis in a rat model of hindlimb ischemia. Nude rats received in their ischemic skeletal muscles either rhG-CSF (2, 10, 20 microg/kg per day) or saline (control) for 6 days. Laser Doppler blood flowmetry (LDBF) revealed an augmented ischemic/normal limb LDBF ratio and an increased capillary density in the rhG-CSF-treated groups compared with the control at days 14, 21, and 28 (P<0.05). These doses of rhG-CSF induced only mild leukocytosis ( approximately 1.4-fold increases versus baseline). rhG-CSF promoted endothelial migration and tube formation in vitro. Local injection of low doses rhG-CSF effectively augmented ischemia-induced angiogenesis in vivo. This treatment regimen of low-dose rhG-CSF may become a new and safe modality for therapeutic angiogenesis.

Experimental Model of Intracranial Arteriovenous Shunting in the Acute Stage

A model of intracranial arteriovenous (AV) shunting must incorporate local hypoperfusion and simulate the hemodynamics of arteriovenous malformations. In this study, the hemodynamics of an intracranial AV shunt model in the acute stage were clarified. End-to-side anastomoses with a femoral vein graft were performed between a cortical branch of the middle cerebral artery (MCA) and the superior sagittal sinus in anesthetized dogs. Local cerebral blood flow (l-CBF) was measured by laser Doppler blood flowmetry. l-CBF decreased suddenly by 34.2% when the shunt was opened in the ipsilateral MCA territory. Upon re-occlusion, l-CBF immediately equaled or exceeded the pre-opening value and returned to the pre-opening value within the next 15 minutes. Opening the shunt produced little change in l-CBF in the territory of the ipsilateral or contralateral anterior cerebral artery. The decrease in l-CBF was correlated with shunt volume only in the MCA territory. l-CBF manifested a PaCO(2)-dependent increase before shunt opening, but CO(2) reactivity was impaired after opening the shunt only in the MCA territory. This dog model features local hypoperfusion due to intracranial AV shunting and disturbance of CO(2) reactivity in the acute stage. The hemodynamics of this model will be confirmed in the chronic stage.

Derivation of Functional Endothelial Progenitor Cells from Human Umbilical Cord Blood Mononuclear Cells Isolated by a Novel Cell Filtration Device

Endothelial progenitor cells (EPCs) can differentiate from mononuclear cells (MNCs) of adult human peripheral blood, bone marrow, and cord blood during culture. Although MNCs are usually isolated by a Ficoll gradient centrifuge method, this method is time-consuming, and blood is easily contaminated. We developed a novel cell filtration device (StemQuickE, Asahi Kasei Medical, Oita, Tokyo, Japan) to isolate MNCs from human cord blood and examined whether functional EPCs could differentiate from MNCs isolated by this device. Recovery rates of MNCs, CD34(+) and CD133(+) progenitor cells, were significantly greater in the StemQuickE method than in the Ficoll method. During MNC culture, spindle-shaped attaching cells developed, and most of these cells incorporated DiI-acetylated low-density lipoprotein and showed positive binding to fluorescein isothiocyanate-lectin. Reverse transcription-polymerase chain reaction analysis revealed that attaching cells expressed various progenitor and endothelial lineage markers such as KDR, CD31, endothelial cell nitric oxide synthase, CD133, and LOX-1. Culture-expanded EPCs were isolated and labeled with a green fluorescent dye, PKH2-GL, and cocultured with human umbilical vein endothelial cells (HUVECs). EPCs formed angiogenesis-like networks together with HUVECs in 3D matrix gel. Finally, EPCs (3 x 10(5)) were implanted into ischemic hindlimb of nude rats (n = 3), and laser Doppler blood flowmetry (LDBF) revealed that the ratio of ischemic to normal limb LDBF was significantly greater in EPC-transplanted animals compared with controls receiving saline. In conclusion, the novel cell filtration device, StemQuickE, is a useful tool to isolate MNCs from human cord blood. Moreover, MNCs obtained by this filter system can give rise to functional EPCs.

Pharmacokinetic and pharmacodynamic profile of icatibant

Icatibant, a potent bradykinin (BK) antagonist specific for B2 receptors, was administered i.v. to 18 healthy males to assess its safety, pharmacokinetic, and pharmacodynamic profile for onset and duration of action. Part I (3 panels of 4 subjects) compared single 1h and 4h infusions (0.005 to 3.2 mg/kg) in ascending, double-blind, placebo-controlled design. Part II tested a 24h (0.15 mg/kg/day) vs. repeated 1h infusions (0.5 mg/kg q8h) in double-blind cross-over design. Icatibant (with 2 major metabolites) concentration was assessed by LC-MS-MS, and response by repeated i.v. bolus challenges of a BK dose selected for eliciting a 10–15 mmHg blood pressure drop with reflex tachycardia (Finapress photoplethys-mography) and facial flush (laser-Doppler blood flowmetry). BK blockade was obtained at all doses, with dose-dependent intensity and duration (Fig 1), correlating with plasma concentration and lacking hysteresis. BK dose increase (4-fold) overcame blockade, suggesting competitive inhibition. Icatib-ant has a rapid distribution and elimination (half-life 1.8h) and linear kinetics over the dose range tested. It was well tolerated up to 1.6 mg/kg but 3.2 mg/kg induced transient head/trunk flushing, itching, with one orthostatic hypo-tension. In conclusion, the ability of Icatibant to safely and sustainedly block BK effects over a wide dose range suggests an appealing therapeutic potential in conditions involving BK overproduction. Clinical Pharmacology & Therapeutics (2004) 75, P56–P56; doi: 10.1016/j.clpt.2003.11.212 Figure 1Open in figure viewerPowerPoint

A comparison of hyperalgesia and neurogenic inflammation induced by melittin and capsaicin in humans

Melittin (a main compound of bee venom) and capsaicin were injected intradermally in healthy human volunteers: (1) to study secondary mechanical hyperalgesia (static hyperalgesia and dynamic hyperalgesia) around the injection site; and (2) to correlate the sensory changes to the neurogenic inflammation assessed by laser-doppler blood flowmetry. Melittin 50 μg and capsaicin 10 μg induced comparable spontaneous pain and increased blood flow (neurogenic inflammation). Intradermal injection of melittin induced regions of secondary mechanical hyperalgesia around the injection site, however, they were not as large as the hyperalgesia induced by capsaicin. This is the first report studying mechanical hyperalgesia induced by melittin in humans, and the results were in agreement with the previous observations in rats. Melittin seems to be a valuable model to study a possible contribution of neurogenic inflammation to hyperalgesia in humans.

Gut mucosal response to food antigens in Crohn's disease.

Food antigens may contribute to gut inflammation in Crohn's disease. To assess in vivo sensitization to food antigens, ascertain whether sensitivity is gut specific, assess food sensitization in vitro, and correlate in vivo changes with histological and blood changes. Skin testing and rectal exposure to six food antigens (cereal, cabbage, citrus, milk, yeast and peanut) and control saline were assessed double-blind by immediate and 3.5-h laser Doppler blood flowmetry, and rectal biopsies were taken. Peripheral blood lymphocyte proliferation was measured in response to the same antigens. Ten patients with Crohn's disease and 10 healthy controls were studied. Blood flow increased in 24 of 60 antigen sites in Crohn's disease patients and six of 60 antigen sites in controls (P < 0.0001) after 3.5 h. The Crohn's disease group demonstrated higher rectal blood flow than controls in response to all food antigens, and this was significantly different for the responses to yeast (P = 0.036) and citrus fruits (P = 0.038). Lymphocyte proliferation occurred in 32 of 60 tests in Crohn's disease patients and eight of 60 tests in controls (P < 0.0001). There were no skin responses. Submucosal oedema corresponded to increased mucosal flow. Crohn's disease patients demonstrate in vivo and in vitro sensitization to food antigens, which is gut specific. Mucosal flowmetry allows the identification of sensitization to gut antigens.

Reflection Spectroscopy of Analgesized Skin

Analgesized skin, when subjected to heat stimuli, responds by increasing skin perfusion. This response does not originate from increased perfusion in superficial capillaries, but rather in the deeper lying vessels. The aim of this study was to assess changes in blood chromophore content, measured by reflection spectroscopy, in relation to the perfusion increase, especially regarding the chromophores oxyhemoglobin and deoxyhemoglobin. Eleven normal subjects were treated with analgesic cream (EMLA) and placebo for 20, 40, 60, 120, and 180 min. Individual reactions to local heating were classified as responses if the change in reflection data or the change in perfusion, as measured by laser Doppler blood flowmetry, exceeded 2 standard deviations of normal variation. The increase in blood perfusion or in blood content gave rise to an increased absorption, interpreted as an increase due mainly to the chromophore oxyhemoglobin. The number of responses increased with increased treatment time for EMLA-treated areas. In general, there was a good agreement between both methods; 44 of 55 classifications coincided for the two methods used. In conclusion, analgesized forearm skin, which had been exposed to local heating, responded with an elevated perfusion consisting of oxygenated blood. This strengthens the hypothesis that the flow increase occurs through dilatation of larger deeper lying skin vessels and not in the capillaries.