Search PubMed⌕ Search

Biomedical subjects

A Bollinger

Publications and source records attributed to A Bollinger.

317 records · Page 18Linked to original sources
PubMedDate not supplied

A triple electrode for simultaneous investigations of transcutaneous oxygen tension, laser-Doppler flowmetry and dynamic fluorescence video microscopy.

A newly designed triple probe is introduced for measurements of transcutaneous oxygen tension, laser Doppler flowmetry (LDF) and microangiodynamics of skin capillaries by dynamic video microscopy with and without fluorochromes. The performance of the triple probe was checked in 9 healthy volunteers (6 women, 3 men; mean age: 34 years) and 9 patients (5 women, 4 men; mean age: 67 years) with peripheral arterial occlusive disease (PAOD). The mean Doppler ankle/arm pressure ratio was 0.54 +/- 0.30. Six patients suffered from severe claudication, 2 from rest pain and 1 patient had toe and forefoot necrosis. The foot dorsum was selected as measuring site. After recording baseline values of skin surface PO2 (ssPO2) at 37 degrees C, LDF and capillary images, a suprasystolic compression at the ankle level was performed for 4 min. Thirty seconds before cuff opening 0.2 ml/1 l blood volume of 20% sodium fluorescein was injected in an antecubital vein. Sodium fluorescein arrival times, filling times and maximum fluorescent light intensity times were measured, and ssPO2 and LDF were recorded continuously during postocclusive reactive hyperemia (PORH). The results indicate an adequate function of the triple probe. The mean resting ssPO2 was 2.0 +/- 1.9 mm Hg in PAOD patients and 4.0 +/- 3.9 mm Hg in controls (p = 0.185). Maximum ssPO2 during PORH was significantly reduced (p = 0.008) in patients (3.1 +/- 2.1 mm Hg) compared to healthy subjects (11.8 +/- 7.7 mm Hg). Resting LDF values were 6.5 +/- 6.4 perfusion units (PU) in PAOD patients versus 10.3 +/- 8.2 AU in controls (p = 0.295). Peak LDF during PORH was significantly reduced (p = 0.005) in patients (19.5 +/- 6.4 PU) versus healthy subjects (33.8 +/- 11.5 PU.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Effects of subcutaneous insulin-like growth factor-I infusion on skin microcirculation.

When healthy volunteers were treated with human insulin-like growth factor-I (IGF-I), mild generalized edema often developed. In the present study, the effect of IGF-I on cutaneous capillary permeability and microvascular skin blood flow was investigated using fluorescence videomicroscopy and laser Doppler fluxmetry. Transcapillary diffusion of intravenously injected sodium fluorescein (NaF) was quantitated by videodensitometry in terms of fluorescent light intensities (FLIs) 5, 10, 20, 30, 60, 120, 180 and 300 s after the first appearance of the dye. Laser Doppler fluxmetry was performed at rest (LDFrest) and during postocclusive reactive hyperemia (LDFpeak). Eight healthy subjects (3 women, 5 men; mean age 28 years, range 24-30 years) were investigated. The sensing site was the skin on the right dorsal wrist. Measurements were performed after 4 days of subcutaneous infusion of 0.9% saline (control) and of IGF-I. Mean values for the FLI were significantly higher after IGF-I than after saline infusion (p < 0.05), when the FLIs were expressed in arbitrary units. As percentages of their individual maxima, the differences were significant (p = 0.05) after 60 s (23.6 +/- 6.6% with NaCl and 31.9 +/- 7.6% with IGF-I). LDFrest and LDFpeak tended to be higher after IGF-I treatment without achieving statistical significance (p = 0.176). The mean appearance time of the dye after injection was significantly shorter (p = 0.016) in the IGF-I group than in the control group (32.0 +/- 8.4 s with IGF-I, 42.4 +/- 8.3 s with NaCl).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Simultaneous assessment of muscle and skin blood fluxes with the laser-Doppler technique.

The laser-Doppler technique was used to assess local muscle and skin blood fluxes at the lower limb in 20 healthy volunteers. After puncturing the anterior tibial muscle with a steel cannula, a single-fibre probe with a diameter of 0.5 mm was inserted into the muscle. Simultaneously, the skin blood flux was measured at calf and foot. The muscle blood flux at rest was 3.5 to 4 times higher than the skin blood flux at calf or foot. The spatial variability of the muscle blood flux at three different sites of measurement was considerable and tended to be higher than in the skin of the calf. After an arterial occlusion lasting 3 min, peak flux was reached in the muscle after 18.7 +/- 9.8 s, in the skin of the calf after 16.8 +/- 9.3 s, and in the skin of the foot after 22.9 +/- 14.6 s (NS). The relative flux increase during reactive hyperaemia was significantly lower in the muscle (2.7 +/- 1.3) than in the skin of the calf (3.9 +/- 1.9; p<0.05) or the foot (5.1 +/- 3.5; p<0.005). The reproducibility of reactive hyperaemia response in muscle was excellent with unchanged probe position, but exhibited a marked variability on different days. The laser-Doppler technique provides the possibility for simultaneous measurement of flow dynamics in muscle and skin with a high temporal resolution. Methodological problems include differences in probe geometry of the single-fibre compared to standard probes and differences in optical properties of the tissues. Direct comparison of flux values may, therefore, be subject to criticism, but not the comparative analysis of relative flux changes. The influence of tissue trauma on muscle blood flux has to be considered for the analysis of flux data.

Adult↗
PubMedDate not supplied

Skin capillary aneurysms detected by indocyanine green in type I diabetes with and without retinal microaneurysms.

Functional diabetic microangiopathy of skin vessels is well known (decreased reactivity of arterioles to various stimuli, increased capillary pressure and permeability). In contrast to conventional capillaroscopy, recently introduced infrared fluorescence videomicroscopy with indocyanine green allows one to depict capillary aneurysms, even when filled with plasma alone. Seventeen healthy volunteers (mean age 37.7 years), 14 patients with type I diabetes without (31.3 years) and 17 with retinal microaneurysms (46.8 years) were studied. The mean duration of diabetes in patients without retinal microaneurysms was 14.2 years (4-36 years) and in those with retinal microaneurysms 21.5 years (8-49 years). Nailfold capillary aneurysms were present in 3 of 17 healthy controls, in 7 of 14 patients without and in 10 of 17 patients with retinopathy. Patients with type I diabetes with and without retinopathy exhibited significantly more skin microaneurysms (p < 0.05 and < 0.005, respectively) than the controls. The prevalence in the patients with retinal microaneurysms tended to be even higher. Skin capillary aneurysms, which may be depicted in vivo by sophisticated infrared fluorescence videomicroscopy, even when filled by plasma alone, are an important morphological feature of diabetic microangiopathy.

Adult↗
PubMedDate not supplied

Local blood flux in skin and muscle during voluntary hyperventilation in healthy controls and patients with hyperventilation syndrome.

Laser Doppler fluxmetry was used to analyze local blood flux in the anterior tibial muscle and the skin of the calf simultaneously during 3 min of hyperventilation. Examinations were performed in 10 controls and 10 patients with a hyperventilation syndrome in order to evaluate a possible different vascular response to the provocation test. During hyperventilation, mean muscle blood flux increased in both groups. In controls, flux augmented from 23.4 +/- 12.3 arbitrary units (AU) to 51.6 +/- 28.3 AU (p < 0.05) and in patients from 21.6 +/- 10.8 AU to 45.0 +/- 26.4 AU (p < 0.05). The changes of skin blood flux during hyperventilation were not significant. The flux response did not differ significantly in controls and patients. Using the laser Doppler technique we were able to confirm muscular vasodilatation previously reported during short-term hyperventilation. Possible mechanisms include release of vasoactive substances and/or a stimulation of the autonomic nervous system.

Adult↗
PubMedDate not supplied

Flow velocity of cutaneous lymphatic capillaries in patients with primary lymphedema.

For the first time measurements of lymph flow velocities in cutaneous microlymphatics of patients with lymphedema were performed and compared with healthy subjects. Flow velocity in single lymphatic skin capillaries was measured using fluorescence video microscopy after subepidermal microinjection of FITC-dextran 150,000 in 15 healthy volunteers and 16 patients with primary lymphedema. Initial filling of the lymphatic capillary network was fast with significantly higher mean velocities in patients with primary lymphedema than in healthy controls (890 +/- 43 vs. 550 +/- 390 microns/s, p < 0.05). The resting velocities were not significantly different between controls and patients (10.3 +/- 4.1 vs. 16.6 +/- 13.9 microns). In 12 out of the 16 lymphedema patients cutaneous backflow of the fluorescent contrast medium from deeper invisible lymphatics was observed. In 4 of these patients rhythmic reflux with a mean frequency of 1.4 +/- 0.5 cycles/min was measured by video densitometry in microlymphatics with a significantly (p < 0.01) enhanced diameter. Mean flow velocity (Vp) in these precollectors was significantly increased compared to the resting velocities (p < 0.01). On the basis of these results the hypothesis is advanced that rhythmic cutaneous backflow originates from intrinsic contractions of deeper lymph collector segments and is transmitted to the superficial microlymphatics through incompetent connecting channels. This newly recognized mechanism appears to be an important factor for the pathophysiology of lymphedema.

Adult↗
PubMedDate not supplied

Fluorescence microlymphography in chronic venous incompetence.

In severe chronic venous incompetence there is not only microangiography of the blood capillaries, but the superficial lymphatic skin capillaries at the medial ankle region are damaged also. The network visualized after subepidermal injection of FITC-dextran 150,000 is interrupted by obliterations or is even completely destroyed. In addition, lymphatic microangiopathy may be diagnosed by increased leakage of the dye out of the capillaries (enhanced permeability) and by phenomena of cutaneous reflux (parts of the network filling from deeper invisible channels). It is concluded that formation of indurated edema in chronic venous insufficiency arises at least in part from lymphatic microangiopathy.

Capillaries↗
PubMedDate not supplied

Microvascular dynamics at the nailfold in rheumatoid arthritis.

Conventional and fluorescence videomicroscopy using Na-fluorescein as tracer was performed in 13 patients with rheumatoid arthritis (RA) and Waaler Rose titers less than 1: 112, 10 patients with titers greater than or equal to 1: 112 and 11 patients with osteoarthritis (OA) (control group). At the nailfold different microvascular diameters, capillary flow pattern, red blood cell velocity and transcapillary diffusion of Na-fluorescein were determined. Mean red blood cell velocity was significantly (p less than 0.02) decreased in patients with RA and high titers (0.23 +/- 0.21 0.21 mm/s) when compared to OA patients (0.59 +/- 0.20 mm/s). Abnormal flow patterns, in 2 cases even a reversal of flow direction, were only observed in RA patients and not in controls. Mean transcapillary and interstitial diffusion of Na-fluorescein was not enhanced at the nailfold in RA-patients. These findings do not exclude increased microvascular permeability in synovial membranes or in RA patients with vasculitis.

Adult↗
PubMedDate not supplied

Microangiopathy of cutaneous blood and lymphatic capillaries in chronic venous insufficiency (CVI).

The severity of microangiopathy in patients with chronic venous insufficiency (CVI) determines the extent of the trophic disturbances of the skin. Resulting from valvular incompetence of deep and/or perforating veins and the accompanying venous outflow obstruction caused by deep venous thrombosis (DVT), the increased ambulatory venous pressure heads are transmitted retrograde into the microvasculature of the skin at the ankle region. In the present study, we have assessed the changes in the cutaneous microvasculature by dynamic fluorescence video microscopy, fluorescence microlymphography, and transcutaneous oxygen tension (tcPO2) measurements. In mild forms of CVI, capillary density, morphologic characteristics, and tcPO2 are still normal. Fluorescent light intensity is, however, significantly increased, indicating an increased transcapillary diffusion of sodium fluorescein (NaF) as a marker for enhanced leakage of the capillaries in the early stage of the disease. The pericapillary halo diameters are significantly enlarged, compared to controls (p < 0.01). In the severe stages of CVI and in patients with venous ulcers, capillary thromboses, probably caused by endothelium-blood cell interactions, may lead to a reduced capillary density. In order to enlarge the exchange surface area, the remaining skin capillaries become tortuous (capillary tufts). Parallel to the reduced capillary number, tcPO2 decreases and can be extremely low at the ulcer rim or at white atrophy spots. Fibrin cuffs are not a specific finding for venous ulceration and do not significantly impair oxygen diffusion. Fluorescence microlymphography permits visualization of the lymphatic capillaries of the superficial skin. In severe stages of CVI, the lymphatic capillary network at the medial ankle area is destroyed, and the remaining lymphatic capillary fragments have an increased permeability to FITC-dextran with a molecular weight of 150,000. These findings demonstrate a special lymphatic microangiopathy in CVI, suggesting an additional lymphatic component in the edema formation.

Adult↗