Biomedical subjects

K Messmer

Publications and source records attributed to K Messmer.

At least 37 records · Page 2Linked to original sources

PubMed2002

Orthogonal polarisation spectral imaging as a new tool for the assessment of antivascular tumour treatment in vivo: a validation study.

Tumour angiogenesis plays a key role in tumour growth, formation of metastasis, detection and treatment of malignant tumours. Recent investigations provided increasing evidence that quantitative analysis of tumour angiogenesis is an indispensable prerequisite for developing novel treatment strategies such as anti-angiogenic and antivascular treatment options. Therefore, it was our aim to establish and validate a new and versatile imaging technique, that is orthogonal polarisation spectral imaging, allowing for non-invasive quantitative imaging of tumour angiogenesis in vivo. Experiments were performed in amelanotic melanoma A-MEL 3 implanted in a transparent dorsal skinfold chamber of the hamster. Starting at day 0 after tumour cell implantation, animals were treated daily with the anti-angiogenic compound SU5416 (25 mg kg x bw(-1)) or vehicle (control) only. Functional vessel density, diameter of microvessels and red blood cell velocity were visualised by both orthogonal polarisation spectral imaging and fluorescence microscopy and analysed using a digital image system. The morphological and functional properties of the tumour microvasculature could be clearly identified by orthogonal polarisation spectral imaging. Data for functional vessel density correlated excellently with data obtained by fluorescence microscopy (y=0.99x+0.48, r2=0.97, R(S)=0.98, precision: 8.22 cm(-1) and bias: -0.32 cm(-1)). Correlation parameters for diameter of microvessels and red blood cell velocity were similar (r2=0.97, R(S)=0.99 and r2=0.93, R(S)=0.94 for diameter of microvessels and red blood cell velocity, respectively). Treatment with SU5416 reduced tumour angiogenesis. At day 3 and 6 after tumour cell implantation, respectively, functional vessel density was 4.8+/-2.1 and 87.2+/-10.2 cm(-1) compared to values of control animals of 66.6+/-10.1 and 147.4+/-13.2 cm(-1), respectively. In addition to the inhibition of tumour angiogenesis, tumour growth and the development of metastasis was strongly reduced in SU5416 treated animals. This new approach enables non-invasive, repeated and quantitative assessment of tumour vascular network and the effects of antiangiogenic treatment on tumour vasculature in vivo. Thus, quantification of tumour angiogenesis can be used to more accurately classify and monitor tumour biologic characteristics, and to explore aggressiveness of tumours.

Angiogenesis Inhibitors↗

PubMed2002

Intravital fluorescence microscopy and phototocicity: effects on leukocytes.

The purpose of this investigation was to clarify whether the light exposure of fluorescently marked leukocytes and/or plasma influences the leukocyte behavior (rolling and firm adhesion). Anaesthetized Balb/c mice were laparotomized to expose the mesentery of the terminal ileum. Animals were randomly assigned to 5 experimental groups. One group was studied in trans-illumination mode, the other four groups received iv-bolus injections of either FITC-dextran (FITC-dx) 150 kD, rhodamine 6 G (rh6G), a combination of FITC-dx and rh6G, or acridine orange, respectively, and were then studied in epi-illumination mode. In each animal, eight vessels (6 venules, 2 arterioles) were exposed five times for 60 sec. to continuous light of the appropriate excitation wavelength with a 20-min. interval between exposures. The vessel diameters and leukocyte-endothelial cell interactions were quantified using intravital fluorescence microscopy. The diameters of arterioles and postcapillary venules remained unchanged in all groups studied. Rolling and adherent leukocytes were observed in postcapillary venules only and there were no significant differences between all groups. Under these conditions, the exposure of fluorescently labeled leukocytes and/or plasma to standard light levels for up to 300 seconds has no significant impact on leukocyte-endothelial cell interactions in mesenteric postcapillary venules.

Acridine Orange↗

PubMed2002

Inhibition of the alpha-nu integrins with a cyclic RGD peptide impairs angiogenesis, growth and metastasis of solid tumours in vivo.

Anti-angiogenetic cancer therapy is a potential new form for treatment of solid tumours. The alpha(v)-integrins (alpha(v)beta3, alpha(v)beta5) mediate the contact of activated endothelial cells to proteins of the extracellular matrix during tumour angiogenesis as a prerequisite for survival of endothelial cells. The aim of this study was to investigate the effects of application of a methylated cyclic RGD-peptide as an alpha(v)-integrin antagonist on angiogenesis, microcirculation, growth and metastasis formation of a solid tumour in vivo. Experiments were performed in the dorsal skinfold preparation of Syrian Golden hamsters bearing the amelanotic hamster melanoma A-Mel-3. Animals were injected intraperitoneally with a methylated cyclic RGD-peptide every 12 h, the control group received an inactive peptide. Microcirculatory parameters of tumour angiogenesis including functional vessel density, red blood cell velocity, vessel diameter and leucocyte-endothelium interaction were analysed using intravital microscopy. In an additional study the effects on growth and metastasis of subcutaneous A-Mel-3 were quantified. Functional vessel density was markedly reduced on day 3 in treated animals compared to controls (37.2 +/- 12.1 vs 105.2 +/- 11.2 cm(-1); mean +/- s.e.m.; P<0.05) and increased subsequently in both groups. Red blood cell velocity at day 3 was below values of controls (0.026 +/- 0.01 vs 0.12 +/- 0.03 mm x s(-1); P<0.05). No differences were observed in vessel diameters and leucocyte-endothelium interaction was almost absent in both groups. Furthermore, growth and metastasis of subcutaneous tumours after administration of the cyclic RGD-peptide was significantly delayed in comparison to controls (P<0.05). Inhibition of alpha(v)-integrins by a cyclic RGD-peptide resulted in significant reduction of functional vessel density, retardation of tumour growth and metastasis in vivo. Taken together, these results implicate RGD-peptides as agents which have anti-tumour and anti-metastatic activity in vivo.

Animals↗

PubMed2002

Small-volume resuscitation: from experimental evidence to clinical routine. Advantages and disadvantages of hypertonic solutions.

BACKGROUND: The concept of small-volume resuscitation (SVR) using hypertonic solutions encompasses the rapid infusion of a small dose (4 ml per kg body weight, i.e. approximately 250 ml in an adult patient) of 7.2-7.5% NaCl/colloid solution. Originally, SVR was aimed for initial therapy of severe hypovolemia and shock associated with trauma. METHODS: The present review focuses on the findings concerning the working mechanisms responsible for the rapid onset of the circulatory effect, the impact of the colloid component on microcirculatory resuscitation, and describes the indications for its application in the preclinical scenario as well as perioperatively and in intensive care medicine. RESULTS: With respect to the actual data base of clinical trials SVR seems to be superior to conventional volume therapy with regard to faster normalization of microvascular perfusion during shock phases and early resumption of organ function. Particularly patients with head trauma in association with systemic hypotension appear to benefit. Besides, potential indications for this concept include cardiac and cardiovascular surgery (attenuation of reperfusion injury during declamping phase) and burn injury. The review also describes disadvantages and potential adverse effects of SVR: CONCLUSION: Small-volume resuscitation by means of hypertonic NaCl/colloid solutions stands for one of the most innovative concepts for primary resuscitation from trauma and shock established in the past decade. Today the spectrum of potential indications involves not only prehospital trauma care, but also perioperative and intensive care therapy.

Fluid Therapy↗

PubMed2002

Initial reperfusion with magnesium after cardioplegic arrest attenuates myocardial reperfusion injury.

BACKGROUND: Magnesium's effect on calcium ion concentrations may attenuate myocardial reperfusion injury. The aim of this study was therefore to investigate the effects on the recovery of myocardial function of initial reperfusion with varying Mg(2+) concentrations following cardioplegic arrest. METHODS: Isolated guinea pig hearts underwent 3.5 hours of cardioplegic arrest in St. Thomas Hospital II solution (STH) or Bretschneider HTK solution (HTK) at 24 degrees C. Control hearts were reperfused with normal Krebs-Henseleit solution (KHS). In the therapy groups, hearts were initially reperfused with 5, 10, or 20 mM Mg(2+) for 15 minutes, followed by 30 minutes of perfusion with KHS. RESULTS: During initial reperfusion, elevated Mg(2+) concentrations markedly reduced rate-pressure product, dP/dt and O 2 demand. Release of LDH and CK was reduced in the therapy groups pretreated with Bretschneider HTK. After Mg(2+) washout, left ventricular function recovery and compliance was improved after HTK but not after STH cardioplegia. Following both STH and HTK cardioplegia, Mg(2+) reperfusion reduced reperfusion arrhythmias. CONCLUSIONS: The combination of HTK cardioplegia with 15 min initial Mg(2+) (5 and 10 mM, but not 20 mM) reperfusion was clearly superior to HTK followed by immediate Krebs-Henseleit reperfusion as well as STH cardioplegia with or without initial Mg(2+) reperfusion. The high Mg(2+) concentrations in the STH solution might mask beneficial effects of Mg(2+) reperfusion.

Animals↗

PubMed2002

Differential function of nitric oxide in murine antigen-induced arthritis.

BACKGROUND: The aim of our study was to investigate the role of inducible nitric oxide synthase (iNOS)-derived nitric oxide (NO) production in different stages of murine antigen-induced arthritis (AiA). METHODS: Clinical, histological and microcirculatory parameters (measured by intravital fluorescence microscopy) were assessed in the knee joint during acute and chronic AiA after inhibition of iNOS with L-N(6)-(1-iminoethyl)lysine (L-NIL). Plasma concentrations of and were evaluated by the Griess reaction and the expression of iNOS, P- and E-selectin, intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) by immunohistochemistry. RESULTS: In both stages of the disease, plasma concentrations of and were increased and iNOS was expressed. In the acute phase, swelling, leucocyte adhesion, leucocyte infiltration and expression of adhesion molecules were increased in arthritic animals treated with L-NIL in comparison with untreated arthritic animals. In the chronic phase, no change in the disease parameters could be detected after L-NIL treatment. CONCLUSION: Increased NO production induced by iNOS during the acute phase of AiA can be regarded as a protective response in the prevention of further leucocytic infiltration and joint destruction, whereas it seems to play a subordinate role in chronic AiA.

Acute Disease↗

PubMed2002

Orthogonal polarization spectral imaging versus intravital fluorescent microscopy for microvascular studies in wounds.

The aim of this study was to validate orthogonal polarization spectral (OPS) imaging against intravital fluorescence microscopy (IFM) for microvascular measurements in normal skin and during wound healing. Experiments were performed on the ears of hairless mice (N = 8). The diameter of arterioles and venules, red blood cell velocity in venules, and the functional capillary density were assessed under normal conditions using OPS imaging and IFM. After creation of a circular wound, these observations were repeated at the identical microvascular regions on days 4, 7, 10, and 15. Images were videotaped, and CapImage was used for off-line computer-assisted analysis. Using OPS imaging, the microcirculation of wounded skin in hairless mice could be observed successfully. The regression analyses against standard IFM revealed a significant (p < 0.001) correlation for measurements of all microcirculatory parameters investigated (venular diameter: r(2) = 0.98, N = 345; red blood cell velocity: r(2) = 0.51, N = 326; functional capillary density: r(2) = 0.44, N = 156). However, for diameter as well as for functional capillary density measurements, OPS imaging yielded lower absolute values compared with IFM. The authors were able to validate OPS imaging against IFM for the measurement of microvascular parameters in an animal model of skin wound healing. Such a device should now help to study the role of microcirculation in physiology and pathophysiology during wound healing in patients. First clinical investigations are promising.

Animals↗

PubMed2002

Characterization of microcirculatory disturbance in a novel model of pancreatic ischemia-reperfusion using intravital fluorescence-microscopy.

INTRODUCTION: Microcirculatory disturbances caused by ischemia-reperfusion injury (IRI) are the crucial hallmarks of pancreatitis following pancreas transplantation. AIMS: To develop a novel rodent model of normothermic in situ ischemia of a pancreatic tail-segment that simulates the clinical situation of pancreas transplantation by flushing the organ via an inserted microcatheter and thus enables selective treatment of the organ via this access. METHODOLOGY: Four experimental groups were investigated (n = 7 Wistar rats/group): sham animals without ischemia and dissection of the pancreas; control animals with dissection of a pancreatic tail segment pedunculated on the splenic vessels and flushing od this segment with saline via a microcatheter; and two groups of animals treated like controls with a pancreatic ischemia time of 1 hour or 2 hours. With use of intravital epifluorescence microscopy, the microcirculatory damage was characterized by investigation of functional capillary density (FCD) and leukocyte adherence in postcapillary venules (LAV) before ischemia and during a reperfusion time of 2 hours. Dry:wet ratio determinations, light microscopy, and electron microscopic investigations were performed to characterize the histologic organ damage. RESULTS: FCD decreased significantly (p < 0.05) 2 hours after reperfusion in the groups of 1-hour (-29.21%) and 2-hour ischemia (-42.73%), in comparison with baseline values. LAV increased significantly (p < 0.05), 4.3- and 5.8-fold, after 1-hour and 2-hour ischemia during the observation time. The histologic damage was similar to posttransplantation pancreatitis in humans 1 hour after reperfusion. In sham and control animals these alterations were not significant. CONCLUSIONS: The rodent in situ model of pancreatic IRI showed standardized microcirculatory damage dependent on the ischemia time. Offering the possibility of selective treatment by the direct artery access to the ischemic pancreatic area, the model enables investigations of questions related to human pancreas transplantation.

Animals↗

PubMed2002

Validation of OPS imaging for microvascular measurements during isovolumic hemodilution and low hematocrits.

Orthogonal polarization spectral (OPS) imaging is a new technique that can be used to visualize the microcirculation with reflected light. It uses hemoglobin absorption to visualize the red blood cells (RBCs). Thus the method could fail at low hematocrit (Hct). The aim of this study was to validate OPS imaging for quantitative measurements of diameter and functional capillary density (FCD) under conditions of hemodilution of varying degrees to achieve a wide range of Hcts. The validation was performed in the dorsal skinfold chamber of nine awake Syrian golden hamsters. Measurements of vessel diameter and FCD were performed off-line using Cap-Image on video sequences captured using OPS imaging and standard intravital fluorescence microscopy at baseline, 85, 70, 55, and 40% of the initial Hct. For hemodilution, isovolumic exchange of blood for 6% Dextran 60 was performed. Bland-Altman plots for the vessel diameter and FCD show good agreement between the two methods for both parameters at all studied Hcts. As expected, there was a systematic bias of approximately 4 microm in the diameter measurements since the RBC column was measured and not the intravascular diameter. In conclusion, OPS imaging can be used to measure diameter and FCD at a wide range of Hcts.

Animals↗

PubMed2002

Effects of confinement (110 and 240 days) on neuroendocrine stress response and changes of immune cells in men.

The aim of the study was to evaluate the effects of long-term confinement on stress-permissive neuroendocrine and immune responses in humans. Two groups of four male subjects were confined 240 days (group 240) or 110 days (group 110) in two space modules of 100 or 200 m3, respectively. During confinement, none of the volunteers developed psychic stress as could be examined and verified by a current stress test. However, in group 240 but not in group 110, the diurnal rhythm of cortisol secretion was slightly depressed and the urine excretion of norepinephrine significantly increased. The innate part of the immune system became activated as seen by a rise in the number of circulating granulocytes and the enhanced expression of beta2-integrins. In contrast, the ratio of T-helper to T-suppressor cells decreased. All these effects, observed during confinement, were even more pronounced in both groups when values of endocrinological and immunological parameters were compared between before and 1 wk after the end of the confinement period. Hence, return to normal life exerts pronounced effects to a much higher degree, irrespective of how long or under which conditions individuals were confined. Because the delayed-type hypersensitivity skin reaction against recall antigens remained unaffected, it is to be presumed that confinement appears to induce distinct sympathoadrenergic activation and immunological changes but no clinically relevant immunosuppression.

Adult↗

PubMed2002

[Direct visualization of microcirculation in burn wounds with OPS imaging--is determination of depth of burns possible?].

Adjunct diagnostic techniques might help surgeons to accurately analyse the depth of a burn. However, despite all technical innovations an ideal device for such an application has not been established for routine use as yet. OPS imaging implemented into the CYTOSCAN A/R is a new, recently introduced technique which allows to obtain high contrast images of the microcirculation without the necessity for fluorescent dyes. The aim of the study was to validate OPS imaging as a tool to study microcirculation in skin after burn injury. OPS imaging was applied by no-touch technique and capillary blood flow was videotaped. Subsequent measurements of the microcirculation were performed at the identical site of the burn. Quantitative analysis of the microcirculation was performed off-line using CapImage. OPS imaging produces high quality images of the microcirculation in a burn wound. Data is given as the number of perfused capillaries per observation area (functional capillary density; FCD) [n/cm2]. OPS imaging allows for direct in vivo visualization and quantification of the microcirculation in burned skin. Our preliminary results of the use of OPS imaging in assessing the microcirculation in burns appear promising, and we hope that this novel technique will allow to improve the knowledge of the dynamics of the microcirculation in the pathophysiology of thermal injury.

Blood Flow Velocity↗

PubMed2001

In vivo assessment of colon microcirculation: comparison of the new OPS imaging technique with intravital microscopy.

BACKGROUND: The Orthogonal Polarization Spectral (OPS) imaging technique has been introduced for in vivo assessment of microcirculation in humans. Unclear remains, whether the new technique would allow for accurate investigations of the colon microcirculation with respect to the unique conditions of the microvasculature in that particular tissue. Therefore, the aim of this study was to validate the new technique against intravital fluorescence microscopy (IFM) for the visualization of colon microcirculation in a murine model of inflammatory bowel disease (IBD). METHOD: IBD was induced in Balb/c mice by dextran sulfate sodium (DSS), controls received normal water. In each animal, both the CYTO-SCAN A/R and IFM were used to image the microcirculation (n = 7 in each group). Postcapillary venular diameter, venular red blood cell velocity (RBC-V) and functional capillary density (FCD) were analyzed on the colon muscularis and mucosa and compared to each other using linear regression analysis and Bland-Altman plots. RESULTS: All parameters correlated significantly between the both methods. The venular diameters and the RBC-V were significantly different between control and colitis group in contrast to FCD; these results were present while using both methods. CONCLUSION: Our study demonstrates that the new technique for visualization of microcirculation without use of fluorescent dyes, the OPS-imaging, allows for quantitative measurement of the key microcirculatory parameters of the mouse colon.

Animals↗

PubMed2001

Microcirculatory failure after rat liver transplantation is related to Kupffer cell-derived oxidant stress but not involved in early graft dysfunction.

BACKGROUND: Microcirculatory failure, activation of Kupffer cells (KC), and the formation of reactive oxygen species (ROS) are considered pivotal mechanisms of reperfusion injury after orthotopic liver transplantation. However, the sequence of these events and their impact on early graft function remain controversial. We therefore investigated whether KC induce microcirculatory disturbances through ROS release and whether microcirculatory failure contributes to early graft function after liver transplantation. METHODS: Donor livers of Lewis rats were pretreated either with saline or with gadolinium chloride (GdCl3), an inhibitor of KC function (n=8 each). Syngeneic OLT was performed after 24 hr of hypothermic preservation in University of Wisconsin solution. RESULTS: Intravital microscopy revealed significantly higher sinusoidal perfusion rates in GdCl3-treated allografts (92+/-1.1% vs. 75.7+/-0.8%; P<0.001) compared with untreated controls; permanent leukocyte sticking in sinusoids (23.5+/-2.1 vs. 62.6+/-3.3 cells/lobule, P<0.001) and in postsinusoidal venules (153.1+/-10.4 vs. 446.6+/-46.4 cells/mm(2), P<0.001) were markedly attenuated in GdCl3-treated allografts. Improvement of microcirculatory parameters in GdCl3-treated livers was correlated with a significant reduction of plasma glutathione disulfide formation by KC-derived ROS (0.96+/-0.1 microM vs. 1.79+/-0.5 microM; P<0.01). Despite these beneficial effects, GdCl3-pretreatment failed to improve postischemic alanine aminotransferase release and bile flow. CONCLUSIONS: Microcirculatory failure after liver transplantation is related to KC-derived oxidant stress but not involved in early graft dysfunction.

Animals↗

PubMed2001

The influence of organ temperature on hepatic ischemia-reperfusion injury: a systematic analysis.

BACKGROUND: Although hepatic ischemia-reperfusion (I/R) injury can be reduced by cooling of the ischemic organ, a systematic in vivo analysis of the influence of organ temperature in I/R injury is missing. The aim of this study was to systematically investigate the impact of defined temperatures of the ischemic liver tissue on microvascular I/R injury. METHODS: Ischemia of the left liver lobe was induced in C57BL/6 mice for 90 min. The ischemic lobe was placed in a polyethylene well and the temperature was adjusted to 37 degrees C, 26 degrees C, 15 degrees C, and 4 degrees C by superfusion with cooled/warmed saline solution. The ischemia groups (n=7 each) were compared with a sham-operated group (n=7). The sinusoidal perfusion index and the number of leukocytes firmly adherent to the endothelium of postsinusoidal venules were assessed using intravital fluorescence microscopy at 30 min, 120 min, and 240 min of reperfusion, respectively. At the end of the experiment, serum activities of the liver enzymes aspartate aminotransferase/alanine aminotransferase were determined, and tissue specimens were examined by electron microscopy. RESULTS: Core body temperature did not differ significantly between the groups. In the 37 degrees C group, the sinusoidal perfusion index was significantly reduced and the number of adherent leukocytes was significantly increased compared with the sham group. In all hypothermia groups, however, the microcirculatory parameters did not differ from the sham group. Serum activities of aspartate aminotransferase/alanine aminotransferase were significantly increased and hepatocellular integrity was severely affected in the 37 degrees C group as compared with all other groups. CONCLUSIONS: These findings demonstrate that in the mouse liver the known protective effect of hypothermia is already encountered at 26 degrees C. Further reduction of temperature did not generate additional protection from I/R injury.

Alanine Transaminase↗

PubMed2001

Assessing the microcirculation in a burn wound by use of OPS imaging.

We report on the use of OPS imaging to visualize the microcirculation in a burn wound. This novel technique produces high quality images of the microcirculation and quantitative analysis of functional capillary density (FCD) was possible. FCD measured at day 3 following the injury was 11.2 +/- 4.6 (n/mm superset2; mean +/- SEM). During the initial phase of healing microcirculatory changes were characterized by a moderate but steady increase of FCD, which showed marked increase beginning from day 12 following the burn (16.6 +/- 6.9). Maximal FCD measured at day 23 (48.2 +/- 19.7) decreased from this point in time to finally reach 25.2 +/- 10.3 n/mm superset2 at the end of observation. OPS imaging allows for direct in vivo visualization and quantification of the microcirculation in burned skin. Our results of the use of OPS imaging in assessing the microcirculation in a burn wound appear promising, and we hope that this novel technique will allow to improve the knowledge of the dynamics of the microcirculation in the pathophysiology of thermal injury.

Adult↗

PubMed2001

Orthogonal polarization spectral imaging as a tool for the assessment of hepatic microcirculation: a validation study.

BACKGROUND: Quantitative analysis of liver microcirculation using intravital fluorescence microscopy in animals has increased our knowledge about ischemia-reperfusion injury. However, because of the size of the instrumentation and the necessity of fluochromes for contrast enhancement, human liver microcirculation cannot be observed. Orthogonal Polarization Spectral (OPS) imaging is a recently introduced technique that can be used to visualize the microcirculation without the need for fluorescent dyes. It is a small, hand-held device and could potentially be used to study the microcirculation of the human liver in a clinical setting. However, before implementation into clinical use its ability to quantitatively measure microcirculatory parameters must be validated. METHODS: The livers of Spraque-Dawley rats (n=9) were exteriorized, and images were obtained using OPS imaging and intravital fluorescence microscopy of the identical microvascular regions before and after the induction of a 20-min warm lobar ischemia. Images were videotaped for later computer-assisted off-line analysis. RESULTS: OPS imaging can be used to accurately quantify the sinusoidal perfusion rate, vessel diameter, and venular red blood cell velocity. Correlation parameters were significant and Bland-Altman analyses showed good agreement for data obtained from the two methods at baseline as well as during reperfusion. CONCLUSION: OPS imaging can be used to quantitatively measure microcirculatory parameters in the rat liver under both physiological and pathophysiological conditions. Thus, OPS imaging has the potential to be used to make quantitative measurements of the microcirculation in the human liver.

Animals↗

PubMed2001

Heparin protects local skin microcirculation in 210 minutes-long intravital microscopy observations under general anaesthesia.

UNLABELLED: Prolonged immobilization of severely ill, bed-ridden patients results in formation of pressure ulcers following inappropriate tissue blood perfusion, and local activation of leukocyte - endothelial cell interactions (L/EC). Various treatment modalities were implemented to improve local microcirculation with controversial results. The aim of our study was to investigate the influence of heparin and buflomedil, drugs improving the microcirculation, on local skin blood perfusion using intravital fluorescent microscopy (IVM) technique. MATERIAL AND METHODS: Experiments were carried out on 24 male hairless mice under inhalatory isofluran anaesthesia. Intravenous injection of FITC-dextran (150 kD, 5%) allowed to visualize capillaries during IVM, after immobilisation of hind limb, in an observation chamber. Observations were performed after i.v. injection of heparin (66 IU/kg b.w., n = 8) or buflomedil (6 mg/kg b.w., n = 8) 30, 120 and 210 minutes after chamber installation. Observations were recorded in 30 sec sequences on S-VHS tapes and evaluated using special software. Functional capillary density (FCD), defined as a total length of red cells perfused capillaries per observation field (expressed in cm/cm(2)), postcapillary venule diameters, and number of sticking leukocytes per 0.2 mm vessel length during 30 sec observation time, served as parameters of skin blood perfusion and activation of L/EC interactions. RESULTS: A statistically significant decrease of FCD from 152.7 +/- 38.5 to 100.7 +/- 36.7 cm/cm (2) (p<0.05) was observed in control animals during 210 min lasting observation. Administration of heparin prevented decrease in FCD occurring in control animals during intravital microscopy, whereas buflomedil was found ineffective. Both drugs induced a nonsignificant reduction in the number of sticking leukocytes, whereas no changes in postcapillary venule diameters could be observed. CONCLUSION: The results suggest a protective effect of heparin in clinical therapeutic doses against impairment of skin perfusion during IVM. This observation may justify a trial on the effects of heparin in prevention of development of pressure ulcers.

Animals↗

PubMed2001

Exacerbation of antigen-induced arthritis in inducible nitric oxide synthase-deficient mice.

OBJECTIVE: Inhibition of nitric oxide (NO) produced by inducible NO synthase (iNOS) is suggested to be beneficial in experimental arthritis. Although NO is important for the integrity of the microcirculation, the effects of inhibition of iNOS on the synovial microcirculation are not currently known. This study investigated the synovial microcirculation and leukocyte-endothelial cell interactions in iNOS-deficient mice with antigen-induced arthritis (AIA) and compared these findings with disease severity. METHODS: Fourteen homozygous iNOS-/- and 14 iNOS+/+ mice were used. The severity of AIA was assessed by measuring knee joint swelling and by histologic scoring. The number of rolling and adherent leukocytes was quantitatively analyzed in synovial microvessels using intravital microscopy of intraarticular synovial tissue. Nitrite/nitrate concentrations were measured, and the expression of iNOS, E- and P-selectin, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 (VCAM-1) was assessed by immunohistochemistry. RESULTS: In iNOS+/+ animals with AIA, the plasma concentration of nitrite/nitrate was increased 3-fold and iNOS expression was detected in cells of the joint. Swelling of the knee joint as well as leukocyte infiltration were enhanced in the iNOS-/- arthritic animals compared with iNOS+/+ mice with AIA. AIA-associated leukocyte-endothelial cell interaction in synovial postcapillary venules was more pronounced in iNOS-/-, compared with iNOS+/+, arthritic mice. A strong expression of P-selectin and VCAM-1 was observed in the iNOS-/- arthritic mice only. CONCLUSION: These data suggest that NO production by iNOS in vivo has antiinflammatory effects in experimental arthritis, by mediating a reduction in leukocyte adhesion and infiltration.

Animals↗