Search PubMed⌕ Search

Biomedical subjects

S Wolf

Publications and source records attributed to S Wolf.

At least 253 records · Page 14Linked to original sources
PubMed1991

Retinal microcirculation in patients with diabetes mellitus: dynamic and morphological analysis of perifoveal capillary network.

The new scanning laser technique allows one to quantify the retinal microcirculation. A digital image analysing system was used to study capillary blood flow velocities and morphological parameters of perifoveal intercapillary areas and foveal avascular zones in normal and diabetic subjects. Diabetic patients showed a significant reduction in capillary blood cell velocities in comparison with normal subjects. Perifoveal intercapillary areas and foveal avascular zones were significantly increased in all stages of diabetic retinopathy, and both parameters increased with progressing diabetic retinopathy. Significant changes in the perifoveal intercapillary areas were observed between normal subjects and patients with no retinopathy.

Adult↗
PubMed1991

[Hemodilution in patients with central retinal vein thrombosis. A placebo-controlled randomized study].

A randomized placebo-controlled study was conducted in 40 patients with acute retinal vein occlusion, 19 of whom received iso-(Hct greater than or equal to 42%) or hypervolemic (Hct less than 42%) hemodilution over 10 days with daily infusion of 250 ml hydroxyethyl-starch (MW 200,000/0.5, 10% HAES-steril) in combination with pentoxifylline (oral: 1200 mg/day; i.v.: 300 mg/day; Trental). After this 10-day trial of hemodilution rheological therapy was continued with pentoxifylline (oral: 1200 mg/day; Trental). The control group of 21 patients received no hemodilution or rheological therapy. After 10 days 35 patients underwent laser coagulation. Clinical, hemodynamic and rheological data of all patients were recorded before therapy, after 10 days but before laser coagulation, and after 6 weeks. In the group treated with hydroxyethyl-starch in combination with pentoxifylline, 10 patients had an improvement of central vision by two or more lines after 6 weeks. In the control group only 4 patients showed central vision improved by two or more lines after 6 weeks. In the treated group the retinal circulation and rheological data were significantly improved after 10 days of hemodilution therapy.

Adult↗
PubMed1991

[Hemodilution in acute arterial circulatory disorders of the retina].

20 patients (age: 68 +/- 9 years) with an acute central artery obstruction of the retina were examined in a prospective study. All patients received a hyper- or isovolemic hemodilution depending on the haematocrit value for a period of 10 days. Clinical, hemodynamical and rheological data of these patients were recorded before therapy, after 10 days and after 6 weeks. Under this therapy, 10 patients presented an improved central vision by 2 or more stages. The degree of the distributed circulation can be determined by means of the arteriovenous passage time (AVP) and the dye bolus velocity (MDV). Compared to a control group, a significantly increased arterious-venous passage time and decreased dye bolus velocity can be observed initially. The values after 10 days of therapy and after 6 weeks were significantly improved (p less than 0.01) compared to the initial values.

Aged↗
PubMed1991

[Retinopathy as the first symptom of hairy cell leukemia].

Hairy cell leukemia is a seldom non-Hodgkin-lymphoma of the B-cells. The case of a 39 year old male with loss of vision as first sign of hairy cell leukemia is presented. The decrease of vision was caused by intraretinal bleeding into the macula. By means of ophthalmoscopy and angiography we found intraretinal bleedings, soft exudates, microaneurysms and capillary occlusions. The examination of blood cells showed leucocytosis (48.900/microliter), anemia (hemoglobin 8.7 g/l), thrombocytopenia (67.000/microliter) and hairy cells in peripheral blood and in bone marrow. Under treatment with alpha-Interferon visual acuity became normal and the fundus lesions decreased. This case points out that a retinopathy with bleedings and soft exudates can be caused by leukemia which should therefore be excluded by differential blood count.

Adult↗
PubMed1991

[Rheologic findings in patients with diabetic retinopathy].

The rheological parameters hematocrit, plasma viscosity, red blood cell aggregation and blood cell rigidity were measured in 256 adult-onset (type II) diabetics. The stage of diabetic retinopathy was graded by means of ophthalmoscopy and videofluorescein angiography. The mean values of hematocrit (men 45 +/- 5%, women 42 +/- 5%) and red blood cell rigidity (1.01 +/- 0.08) were equal to those in normal subjects. Plasma viscosity (1.40 +/- 0.10) mPas, normals: 1.24 +/- 0.05 mPas) and red blood cell aggregation (16.0 +/- 4.2, normals: 14.6 +/- 3.2) were increased over the values in normals. The groups with different stages of diabetic retinopathy showed no difference in all rheological parameters. Plasma viscosity and red blood cell aggregation were determined partly by the levels of the large plasma proteins. In the type II diabetics fibrinogen was the most markedly elevated large plasma protein (4.1 +/- 1.2 g/l, normals: 3.2 +/- 0.6 g/l). Significant correlations were found between plasma viscosity and fibrinogen (0.49); plasma viscosity and alpha-2-macroglobulin (0.33); red blood cell aggregation and alpha-2-macroglobulin (0.28); and red blood cell aggregation and immunoglobulin M (0.25). The elevation of red blood cell aggregation and plasma viscosity may be one of the reasons for disturbed microcirculation and fundus changes in diabetic retinopathy.

Adult↗
PubMed1991

[Conjunctival microcirculation and hemorheology in patients with venous occlusions of the retina].

Forty-two patients with branch vein or central retinal vein occlusion were enrolled in this randomized placebo-controlled study. We studied the influence of hemodilution therapy with hydroxyethyl-starch (HAES-steril) combined with pentoxifylline (Trental) for 6 months. In the bulbar conjunctiva, capillary red blood cell (RBC) velocities and vessel diameters and rheological parameters of hematocrit, erythrocyte aggregation and plasma viscosity were examined. In the hemodilution group we observed no changes in vessel diameter and a significant increase in RBC velocity after therapy. After 6 weeks the RBC velocity showed 30% higher values but there was no statistically significant difference. After hemodilution therapy hematocrit, erythrocyte aggregation and plasma viscosity were significantly different from those in the control group. After 6 weeks we observed significant differences only in erythrocyte aggregation. This examination verifies the positive influence of hemodilution therapy on microcirculation and hemorheology.

Adult↗
PubMed1991

[Thrombolytic treatment of retinal arterial occlusions with plasminogen activator].

Tissue-type plasminogen activator (rt-PA), a gene-technologically manufactured fibrinolytic compound, has been employed successfully for treatment of cardial and peripheral arterial vascular occlusions. The advantage of this compound is its lytic effect. It selectively displays its effect in therapeutic dosage on fresh thrombuses, showing only minimal influence on physiological clotting as such. Two patients with stop of the retinal arterial bloodflow in videofluorescence angiography were treated with short term lysis with 100 mg rt-PA, the onset of therapy was 7 and 6.5 hours after loss of vision. Already during the infusion of the compound reperfusion was achieved. Inspite of the relatively late onset of treatment, the visual fields of both patients improved. We assume lytic therapy with rt-PA to be an effective therapy for patients with retinal arterial occlusion, if applied within the first eight hours after acute loss of vision. The number of patients who could potentially benefit from this therapy is limited considering the high rate of spontaneous reperfusion before the first eye exam in 84% of the cases and considering the manifold contraindications for this therapy: 35% of the patients above 70 years of age, 56% of the patients with arterial hypertension (RR 160/100 and above) as well as 10% of the patients treated with Coumarine-derivatives should not undergo lysis. Only 43% of the patients with occlusion of central retinal artery and 21% of the patients with occlusion of retinal branch arteries received the first eye exam within the first 8 hours after the occlusion.

Adult↗
PubMed1990

Retinal circulation times in quantitative fluorescein angiography.

We tried to obtain an overview of the quantitative state of the retinal circulation. Optical density measurements by an image analyzer were performed on video fluorescein angiograms for the determination of dyedilution curves. To ensure that curves with a sharp peak were obtained, 1 ml sodium fluorescein 10% was flushed with 20 ml physiological saline. From dilution curves of a retinal circulation times, T(x) (x = 1, 25, 50, 75, and 100) and Tm, were calculated. T(1) corresponds to the difference in the time of initial dye appearance; T(50), to the so-called half-maxim time difference; T(100), to the difference in the time to peak intensity; and Tm, to the mean circulation time. T(50) showed the best reproducibility when it was examined at 49 retinal regions of 10 healthy volunteers with a double video-fluorescein angiogram that was obtained within 1 min. Normal values (mean +/- SD) at the temporal superior region of 37 healthy volunteers were as follows: T(1) = 0.87 +/- 0.66 s, T(25) = 1.52 +/- 0.48 s, T(50) = 1.83 +/- 0.50 s, T(75) = 2.12 +/- 0.56 s, T(100) = 2.73 +/- 0.76 s, and Tm = 2.69 +/- 1.25 s. We believe that these values give a general overview of the quantitative state of normal retinal circulation.

Adolescent↗
PubMed1990

[Coincidence of hypertensive changes of the eye fundus and regulation disorders of peripheral microcirculation: I--Skin].

In cases of arterial hypertension, funduscopy is an established method of estimating systemic vascular lesions. In this study the relation between the extent of retinal vascular changes and dynamic processes in the microcirculation of the skin was investigated by nailfold capillaroscopy in 88 patients. With increasing vascular changes a progressive loss of vasodilator reserve and transcutaneous partial pressure was observed (no morphologic changes--fundus hypertonicus II--fundus hypertonicus III). It thus appears possible to evaluate the functional state of the macro- and microcirculation by funduscopy.

Adult↗
PubMed1990

[Coincidence of hypertensive fundus changes and regulatory disorders of peripheral microcirculation. II--Skeletal muscles].

In patients with hypertensive fundus changes considerable morphologic changes of the entire vascular system may be assumed. In the present study, the effects of these processes on the partial oxygen pressure of the skeletal musculature were investigated in 62 patients via a macro puncture electrode placed in the tibial muscle. The extent of fundus changes and the reduction in muscular partial oxygen pressure were found to be correlated. With advancing stages of fundus changes, blood flow measured in the common carotid artery decreased. Vascular changes which are clearly recognizable in the hypertensive fundus thus appear to be accompanied by a deterioration in partial oxygen pressure in muscular tissue and restriction of flow in the macrocirculation.

Aged↗
PubMed1990

Molecular characterization and biological function of the movement protein of tobacco mosaic virus in transgenic plants.

We previously demonstrated, in transgenic tobacco plants, that the role of the movement protein (MP) of tobacco mosaic virus is to facilitate the cell-to-cell spread of viral progeny during infection. An analysis of different tissues of these transgenic plants indicated that the MP accumulated in leaf, stem, and root tissue. The highest levels were detected in older leaves. The relative levels of MP in leaf tissue from transgenic plants were equivalent to, or higher than, the levels of MP in tobacco mosaic virus-infected leaf tissue. Results of subcellular fractionation of homogenates of transgenic leaf tissue showed that the MP was most abundant in the cell wall fraction of older leaves and that the protein remained at high levels in the cell wall fraction as the leaves continued to age. Significant levels of the MP were detected in a crude membrane/organelle fraction and a soluble fraction in younger leaves but decreased to low levels in older leaves. These results suggest that the MP accumulates and is stable in cell walls. We have previously shown that the MP modifies the molecular exclusion limit of plasmodesmata, which is consistent with the hypothesis that plant viruses move from cell to cell through altered plasmodesmata. We show here that the ability of the tobacco mosaic virus MP to modify the molecular exclusion limit of plasmodesmata in tobacco depends on the developmental stage of the leaf. The implications of these findings on understanding virus movement and how plasmodesmata function are discussed.

Capsid Proteins↗
PubMed1990

[Error analysis, biological modification factors and variance of peri-ungual video-capillary microscopy].

Error analysis or the evaluation of the precision of microscopic measurements must distinguish between technical errors inherent in the measuring system, and biological variability. The technical error inherent in the overall system in the case of linear measurements is smaller than the lengths to be measured by 1 or 2 orders of magnitude. Thus, the erythrocyte column lengths can be correctly, reproducibly and linearly quantified over the entire measuring range. The biological influencing factors can largely be taken into account or excluded by suitable standardisation of the measuring process. Despite a considerable individual fluctuation in the erythrocyte velocity, there is, on average, no significant dependence of the measuring parameter within the daily profile or from day to day. Differences in capillary perfusion in the presence of diseases associated with microcirculatory disorders or a therapeutic influence on erythrocyte velocity can thus be reliably demonstrated.

Capillaries↗
PubMed1990

[Effect of hemodilution on systemic and capillary hematocrit].

In a cross-over study including 10 clinically healthy male volunteers, the hematocrit in the macro- and microcirculation was investigated prior to and 1 h, 3 h, 6 h and 24 h after iso- or (3 months later) hypervolemic hemodilution using 500 ml hydroxyethyl starch. The dilution effect observed after isovolemic hemodilution is more pronounced than after hypervolemic hemodilution. While isovolaemic hemodilution with 500 ml medium molecular weight hydroxyethyl starch leads to a reduction in the systemic hematocrit by 8.5% by volume, the capillary hematocrit at the time of the most marked dilution (1 h after hemodilution) decreases by only 1.3 hematocrit points in the cutaneous capillaries. After hypervolemic hemodilution, the systemic hematocrit decreases significantly by maximally 5.4% by volume, while the capillary hematocrit does not change significantly.

Adult↗
PubMed1990

Interdisciplinary perspectives on mechanisms and management of low back pain.

Chronic low back pain (CLBP) is one of the most pervasive and costly problems facing medicine today. In addition to personal suffering, CLBP accounts for a greatly disproportionate amount of consumer health care over-utilization, employee absenteeism, lowered work productivity, disability and compensation payments. Recent research in the area has called attention to the complex nature of the problem and the need for an interdisciplinary approach to identification and management. Toward this end, a panel of health care professionals with skill in the assessment and treatment of chronic pain was convened on November 17, 1988. Sponsored by the Institute for Behavioral Medicine in Providence and with funding from the National Institute for Neurological Disorders and Stroke, Stroke and Trauma Program, the purpose of the panel discussion was to bring together clinicians and researchers from distinctly different specialties but who all work with CLBP patients. Topics of discussion included etiology, current status of medical diagnostics and treatments for chronic pain, conceptual and systems issues, and directions for future research.

Back Pain↗