Biomedical subjects

B Bertram

Publications and source records attributed to B Bertram.

At least 73 records · Page 4Linked to original sources

PubMed1991

Retinal blood flow in diabetic children and adolescents.

A total of 209 diabetic children and adolescents aged 6-17 years (mean, 12.6 +/- 2.3 years) were examined by ophthalmoscopy, video fluorescein angiography and hemoglobin (HbA1c) test. Microaneurysms were found in 26% of the children (ophthalmoscopy, 11%; angiography, 23%). The prevalence of retinopathy was 16% in patients aged 6-10 years, 27% in those aged 11-13 years and 36% in those aged 14-17 years. Only five diabetics aged 11-17 years showed lesions other than microaneurysms (hard exudates, intraretinal hemorrhages or retinal capillar leakage). Retinal blood flow was quantified using video fluorescein angiography. The arm-retina time (ART) and the arteriovenous passage time (AVP) as parameters of the retinal microcirculation were obtained using an image analysing system. The mean value for ART was 9.7 +/- 2.5 s and that for AVP was 1.43 +/- 0.52 s. AVP was significantly shorter in diabetic children and adolescents with good glycemic control (HbA1c, less than 7%; AVP, 1.35 +/- 0.44 s) than in those with bad glycemic control (HbA1c, greater than or equal to 9%; AVP, 1.65 +/- 0.51 s).

Adolescent↗

PubMed1991

Metabolism of debrisoquine and susceptibility to breast cancer.

There may exist an association between the genetically determined oxidation status of the antihypertensive agent debrisoquine (DEB) and the propensity to develop tumours. The metabolism of DEB is extensive in 90% of healthy subjects (metabolic ratio = MR = 0-12.6; MR = % DEB excreted divided by % 4-hydroxy-DEB excreted) and poor in 10% (MR greater than 12.6). In patients with cancer of the lung, urinary bladder, and gastrointestinum, the percentage of high metabolizers is increased to greater than 98%. The poor metabolizer mode is almost devoid of cancer patients. It was investigated whether breast cancer patients show a similar association with respect to the oxidative status of DEB. 108 breast cancer patients and 123 women with benign gynecologic disorders received 1 tablet of 10 mg DEB orally in the evening. Urine was collected for the subsequent 8 hrs and analysed for its content of DEB and its main urinary metabolite 4-OH-DEB by means of HPLC. No decreased amount of poor metabolizers was seen in the cancer group.

Breast Neoplasms↗

PubMed1991

Retinal capillary blood flow measurement with a scanning laser ophthalmoscope. Preliminary results.

The scanning laser technique in combination with digital image analysis allows direct objective measurement of flow velocities in perimacular capillaries. In addition, the complete macular network of capillaries can be observed. By means of digital frame-to-frame picture analysis of digital recordings, blood flow velocities and morphologic data have been measured. The mean flow velocity in perimacular capillaries observed with the scanning laser ophthalmoscope in healthy subjects (n = 21) amounted to 3.28 +/- 0.45 mm/second. In patients (n = 13) with diabetes mellitus (no or background retinopathy), the mean flow velocity was significantly reduced (2.89 +/- 0.57 mm/seconds) compared with healthy subjects. Morphologic data of the perifoveal capillary bed showed a significant reduction of capillaries in patients with diabetes mellitus when compared with healthy subjects.

Adult↗

PubMed1991

[Hemodynamic findings in patients with retinitis pigmentosa].

The hemodynamic status of 26 patients with retinitis pigmentosa was examined using video fluorescein angiography. The hemorheological parameters hematocrit, plasma viscosity, erythrocyte aggregation and erythrocyte rigidity were determined. The results were compared to a matched pairs-group. Video angiography showed for retinitis pigmentosa patients a normal arm-retina time and a significant increase of the arteriovenous passage time. The rheological parameters for both groups were within the reference range. Interestingly the hemodynamic disturbance of microcirculation could be demonstrated already in early stages with no ophthalmoscopic symptoms and no atrophy of retinal vessels detectable at the time. The results indicate that disturbance of the retinal hemodynamics in early stages of retinitis pigmentosa may play a role in the pathogenesis of the disease.

Adolescent↗

PubMed1991

[Video fluorescein angiography studies in acute anterior ischemic optic neuropathy].

Acute anterior ischemic optic neuropathy (AION) is a circulatory disorder of the short posterior ciliary arteries and their branches. 74 patients with AION were examined with video fluorescein angiography for disturbance of the retinal circulation. The armretina time (ART) was slightly (15%, p less than 0.01) increased in patients with AION (12.9 +/- 3.9 s) as compared to healthy persons (11.2 +/- 3.3 s). The prolonged ART was more prominent in the 26 (35.1%) diabetic patients (14.2 +/- 3.9 s). Because of the ART being only moderately prolonged and since the Doppler ultrasonography of the carotid arteries showed in only 3 patients an occlusion or a hemodynamically relevant stenosis of greater than or equal to 50%, prolonged ART may play a considerable role in the course of AION in only few patients. The retinal arteriovenous passage time (AVP) is considerably (77%, p less than 0.01) increased in AION (2.57 +/- 0.89 s) as compared to healthy persons (1.45 +/- 0.40 s). In patients with duration of symptoms less than 10 days (2.78 +/- 0.96 s) the AVP was increased (p less than 0.01) as compared to patients with duration of symptoms between 11 and 30 days (2.11 +/- 0.46 s). The comparison between the eye with AION and the not affected eye showed no difference in ART but an increase of AVP in the eye with AION. The AVP in AION patients without and with diabetes was not different. No differences in ART and in AVP were found between arteriitic and non-arteriitic patients with AION. The results indicate that the retinal microcirculation is disturbed in patients with arteriitic and non-arteriitic AION. This condition may worsen the in AION affected microcirculation of the optic nerve head through the mechanism of decreased blood flow in the retinociliary anastomoses.

Aged↗

PubMed1991

Retinal circulation times in diabetes mellitus type 1.

Video fluorescein angiography was performed in 124 patients between 18 and 65 years of age (mean 35.0, SD 12.3 years) with juvenile-onset, insulin-dependent diabetes mellitus (type 1). The arm-retina time (ART) and the retinal arteriovenous passage time (AVP) were measured by means of a picture analysis system to quantify the retinal microcirculation. Glucose metabolism was assessed by the blood level of haemoglobin A1c. The ART 11.5, SD 3.4 s) was similar to that in normal persons (11.2, SD 3.3 s), while the AVP was significantly longer in the diabetics (AVP = 2.35, SD 0.87 s) than in normal persons (AVP = 1.45, SD 0.40 s). The patients with severe diabetic retinopathy showed the most impressive change in AVP. The diabetics with good glycaemic control, that is, with glycosylated haemoglobin (HbA1c) less than or equal to 8.0 g/dl, had a shorter AVP than patients with bad glycaemic control (HbA1c greater than or equal to 9.5 g/dl). The group with a history of diabetes for less than five years showed circulation parameters similar to those of normal persons. The AVP in this group was significantly shorter than in groups with a history of diabetes for five or more years.

Adolescent↗

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

Newly synthesized dithiocarbamates inhibit the metabolism and toxicity of N-nitrosodimethylamine.

Several dithiocarbamates (DTC) of secondary amines and secondary amino acids were tested for their stability in aqueous solution and for their effect on nitrosamine metabolizing enzymes and on the acute toxicity of N-nitrosodimethylamine (NDMA) in rats. The following results were found: (i) All DTC tested were stable in alkaline solution; in acidic milieu, only DTC derived from secondary amino acids were moderately stable. (ii) The activity of NDMA-demethylase in rat liver microsomes was inhibited completely by all DTC tested. (iii) The excretion of unmetabolized NDMA in rat urine over 24 h increased from 0.1% without pretreatment to 3.6% of the given NDMA dose when combined with a single dose of DTC. (iv) The acute toxicity of NDMA was reduced by dihydroxyethyldithiocarbamate; when the sulfur compound was administered simultaneously and 24 h after the nitrosamine, lethality was almost completely inhibited. (v) The stability of a compound in aqueous solutions did not affect its activity in the enzyme tests.

Animals↗

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

Influence of dithiocarbamates on the metabolism and toxicity of N-nitrosodimethylamine in rats.

Five secondary amines and secondary amino acids were reacted with carbon disulfide to yield dithiocarbamates. These compounds were tested for their influence on biochemical parameters and on some biological effects of N-nitrosodimethylamine (NDMA). The following results were found. (i) All dithiocarbamates tested reduced the activity of N-nitrosodiethylamine-deethylase and completely inhibited the N-nitrosodimethylamine-demethylase in the rat liver. A striking influence on the glutathione content and on the activity of glutathione-S-transferase and glutathione-reductase was not observed. (ii) The excretion of unmetabolized N-nitrosodimethylamine in rat urine during 24 h increased from 0.1% without pretreatment to 3.6% of the given dose on combination with a single dose of dithiocarbamate. (iii) The acute toxicity of NDMA could be reduced with diethanol-dithiocarbamate. After a single simultaneous application of the inhibitor with NDMA, the LD50 was increased from 40 to 66 mg/kg. When the sulfur compound was administered twice, both simultaneously and 24 h after the nitrosamine, lethality was almost completely inhibited. We conclude from these results that dithiocarbamates may be suitable compounds for chemoprevention of nitrosamine-induced tumors.

Animals↗

PubMed1990

New mixed disulfides of L-cysteine derivatives and of glutathione with diethyldithiocarbamic acid and 2-mercaptoethanesulfonic acid.

It is generally assumed that thiol anticarcinogens like disulfiram (DSF) or sodium 2-mercaptoethane-sulfonate (mesna) after in vivo administration react rapidly with serum protein sulfhydryl groups forming mixed disulfides. Different methods have been established for the synthesis of mixed disulfides between cysteine or glutathione and diethyldithiocarbamate (DDTC) or mesna in order to elucidate their chemical and biological effects. A short summary is given of pilot biochemical experiments carried out with two mixed disulfides.

Antineoplastic Agents↗

PubMed1989

[Video fluorescein angiography follow-up of patients with retinal artery occlusion].

Forty patients (age 67 +/- 9 years) with acute central artery obstruction (CAO; n = 20) or branch artery occlusion (BAO; n = 20) of the retina were examined in a prospective study. All patients received a hypervolemic or isovolemic hemodilution, depending on their hematocrit values, for a period of ten days. Clinical, hemodynamic, and rheological data of these patients were recorded before therapy, after ten days, and after six weeks. Under this therapy the central vision of 24 patients (CAO: n = 10; BAO: n = 14) improved by two or more stages. The extent of the circulatory disturbance was determined by arteriovenous passage time and dye bolus velocity. Compared with a control group, a significantly increased arteriovenous passage time and decreased dye bolus velocity were observed initially. The values after ten days of therapy and after six weeks were significantly improved (P less than 0.01) as compared to the initial values. Patients with longer latency showed almost normal retinal hemodynamics, even without therapy, after some weeks. However, in most cases the spontaneous improvement occurred too late. Therefore, it appears important to achieve early reperfusion by therapy.

Adult↗

PubMed1989

[Effect of beta blockers on retinal hemodynamics. A double-blind study in healthy probands].

In a randomized double-blind study the effect of topically applied Timolol (Chibro-Timoptol 0.5%) on the retinal circulation was investigated. In order to quantify the retinal hemodynamics 20 healthy volunteers were examined twice using video fluorescein angiography. The arteriovenous passage time (AVP) and the dye bolus velocity (MDV) were quantified using an image-analyzing system. Following administration of Timolol, IOP decreased from 14.5 +/- 1.9 mm Hg to 9.4 +/- 1.7 mm Hg (P less than 0.010). The study also showed that there was a significant reduction in AVP from 1.75 +/- 0.5 s to 1.56 +/- 0.3 s (P less than 0.05) and an increase in MDV following local application of Timolol. No effect on systemic blood pressure or pulse rate was observed. The results indicate that in addition to its pressure-lowering effect, timolol also leads to increased retinal perfusion.

Adult↗