Biomedical subjects

A Wessing

Publications and source records attributed to A Wessing.

At least 37 records · Page 2Linked to original sources

PubMed1996

Long-term results of pars plana vitrectomy in the management of intermediate uveitis.

Pars plana vitrectomy is a useful tool for the management of certain complications in chronic intermediate uveitis. Media opacities obscuring the visual axis, vitreous membranes causing tractional retinal detachment, macular puckers, and ciliary traction leading to hypotony are clear indications for this approach. Furthermore, it has been suggested that vitrectomy may have a favorable long-term effect on the course of disease. The procedure may achieve regression of inflammation, tapering of immunosuppression, and improvement of cystoid macular edema. However, randomized prospective trials are still needed to define the role of vitrectomy in altering the course of uveitis.

Chronic Disease↗

PubMed1996

[Long-term outcome of radiotherapy of choroid hemangioma].

The usual therapeutic approach to circumscribed choroidal hemangiomas of the posterior pole consists of scatter photocoagulation of the tumor surface. This may often require repetitive treatment or additional invasive measures prior to coagulation due to massive exudative detachment of the retina. In this study, external beam irradiation with high-energy photons (total absorbed dose: 20 Gy) was applied to 36 symptomatic patients. The indication for treatment was exudative retinal detachment including or threatening the fovea. The mean duration of follow-up was 4.5 years (4 months to 24 years, median 4 years). In 23 cases (63.8%) complete resolution of the subretinal fluid could be achieved; 13 cases (36.2%) showed residual serous detachment at some distance from the fovea. The visual acuity improved by two or more lines in 14 cases (38.9%), remained stable in 14 cases and decreased in only 8 cases (22.2%). The functional success was dependent on the interval between onset of first subjective symptoms and treatment. External beam irradiation is a successful form of treatment for choroidal hemangiomas.

Adult↗

PubMed1996

[Retinal angiomatosis. Long-term follow-up].

UNLABELLED: Meyer-Schwickerath reported his first results with light coagulation in 1959. This report on the results of treatment in this disease is based on more than 34 years experience at the university eye hospital in Essen. Important prognostic factors are the number of retinal hemangiomas and secondary retinal lesions, such as exudative retinal detachment, lipid deposits, vitreous hemorrhages, preretinal membranes and traction retinal detachment. PATIENTS: Treatment was performed in 156 patients, with 220 involved eyes. The median follow-up was 8.9 years and the average age before treatment, 27.5 years. RESULTS: A positive family history was found in 36.5% and extraocular hemangiomas in 24% of all cases. There were 64 patients with bilateral hemangiomas. In 64.5% of cases the tumor was destroyed without further recurrences. Xenon light coagulation was the only treatment applied in 70%. The other patients received combined procedures with light coagulation, cryocoagulation, Ru 106 plaque and proton beam. Salvage of 90% of all treated eyes was achieved. CONCLUSION: Treatment at an early stage of the disease, before any secondary retinal damage has developed, seems to be crucial for satisfactory results. Light coagulation is extremely effective at this stage. However, the treatment options for advanced cases have also become better recently.

Adult↗

PubMed1996

[Late vision loss after focal hemorrhagic chorioretinopathy].

Prospective clinical studies about photocoagulation of extrafoveolar choroidal neovascularizations in focal hemorrhagic chorioretinopathy (CR) have demonstrated that the risk of visual loss years after successful treatment is related to the development of retinal pigment epithelium (RPE) atrophy around the laser scar. The reason for this event was thought to be late damage of RPE cells due to the laser treatment. However, because RPE atrophy can also be seen in untreated patients, a prospective study was started to test this pathogenetic hypothesis and to analyze the pathogenetic factors and prognostic importance of RPE atrophy in focal hemorrhagic CR. Eighty-eight patients (52 women, 36 men, 15-45 years old; mean follow-up 62 months; 26 patients treated by photocoagulation) with focal hemorrhagic CR were reexamined. Fifty-two patients (15 treated by photocoagulation and 37 untreated) showed clinically visible RPE atrophy. In these 52 patients the initial and final visual acuity, the amount of initial subretinal fluid (34.6% < 500 microns, 50% 500-750 microns, 15.4% > 750 microns) and the amount RPE atrophy (23.2% < 500 microns, 53.6% 500-750 microns, 23.2% > 750 microns) were analyzed. The development of RPE atrophy was dependent on the time of follow-up (36 patients without RPE atrophy, mean follow-up 29 months; 52 patients with RPE atrophy, mean 84 months, P < 0.001). Of the 52 patients with RPE atrophy, 15 were treated by photocoagulation. The distribution of RPE atrophy was similar to what was found in the 37 untreated patients (P = 0.4). With pronounced RPE atrophy, a decrease in final visual acuity was seen (RPE atrophy < 500 microns, mean visual acuity 0.5; 500-750 microns mean visual acuity 0.3; > 750 microns, mean visual acuity 0.1; P = 0.005). Increased RPE atrophy was also associated with a higher incidence of visual loss (p = 0.009). The amount of RPE atrophy was not dependent on the time of follow-up (P = 0.3), but only correlated with the initial amount of subretinal fluid (atrophy < 500 microns: subretinal fluid < 500 microns 15.4%, 500-750 microns 7.7%, > 750 microns 0%; atrophy 500-750 microns: subretinal fluid < 500 microns 19.2%, 500-750 microns 32.7%, < 750 microns 1.9%; atrophy > 750 microns: subretinal fluid < 500 microns 0%, 500-750 microns 9.6%, > 750 microns 13.5%; P < 0.0001). Because RPE atrophy in focal hemorrhagic CR was seen in patients both with and without photocoagulation therapy, laser treatment cannot be the causative factor. With increased follow-up the risk of the development of RPE atrophy increases in all patients. The resulting amount of RPE atrophy was only dependent on the initial amount of subretinal fluid. If the fovea is included in the exudative detachment, there is a higher risk of long-term visual loss.

Adolescent↗

PubMed1996

The importance of the Golgi complex for epithelial ion transport in Drosophila Malpighian tubules, studied by electron microscopy, cytochemistry and X-ray microanalysis.

The distribution of potassium in the cells of Drosophila Malpighian tubules is not homogeneous. In the microvilli of the apical part of the cell the cytoplasmic potassium content was found to be 2 to 3 times higher than in the neighboring intermediate cytoplasm. Data obtained by electron microscopy, histochemistry and electron probe X-ray microanalysis indicate that glucosaminoglycans (GAGs), synthesized by the Golgi-ER complex, are responsible for potassium accumulation in the apical microvilli. Vesicles bud from the Golgi complex and then move to the apical cell region, where they discharge their contents into the cytoplasm or into the lumen. Budded vesicles also discharge their contents into the hemolymph space between the folds of the basal plasma membrane. GAGs, transformed to proteoglycans (PGs), were identified on the folds of the basal cell surface including basal lamina by reaction with alcian blue. Brefeldin A (BFA) was found to disintegrate Golgi-ER structures to vesicles, whereas budded vesicles vanished. Within the microvilli the K+-content decreased to 32%, the water content to 77%. These data provide evidence that the ER-Golgi complex is involved in the delivery of GAGs (and PGs) into the luminal space and the hemolymph. After disintegration of the Golgi complex, GAGs are missing as temporary ion stores from the vicinity of the membrane transporters.

Animals↗

PubMed1994

Intracellular pH regulation by the plasma membrane V-ATPase in Malpighian tubules of Drosophila larvae.

The functional significance of the apical vacuolar-type proton pump (V-ATPase) in Drosophila Malpighian tubules was studied by measuring the intracellular pH (pHi) and luminal pH (pHlu) with double-barrelled pH-microelectrodes in proximal segments of the larval anterior tubule immersed in nominally bicarbonate-free solutions (pHo 6.9). In proximal segments both pHi (7.43 +/- 0.20) and pHlu (7.10 +/- 0.24)) were significantly lower than in distal segments (pHi 7.70 +/- 0.29, pHlu 8.09 +/- 0.15). Steady-state pHi of proximal segments was much less sensitive to changes in pHo than pH of the luminal fluid (delta pHlu/delta pHo was 0.49 while delta pHi/delta pHo was 0.18; pHo 6.50-7.20). Re-alkaliniziation from an NH4Cl-induced intracellular acid load (initial pHi recovery rate 0.55 +/- 0.34 pH.min-1) was nearly totally inhibited by 1 mmol.l-1 KCN (96% inhibition) and to a large degree (79%) by 1 mumol.l-1 bafilomycin A1. In contrast, both vanadate (1 mmol.l-1) and amiloride (1 mmol.l-1) inhibited pHi recovery by 38% and 33%, respectively. Unlike amiloride, removal of Na+ from the bathing saline had no effect on pHi recovery, indicating that a Na+/H+ exchange is not significantly involved in pHi regulation. Instead pHi regulation apparently depended largely on the availability of ATP and on the activity of the bafilomycin-sensitive proton pump.

Acids↗

PubMed1994

[Ocular involvement in Whipple disease].

PATIENTS AND METHODS We present a 57-year-old white man with progressive deterioration of vision, who had a prolonged history of weakness, migratory arthralgias and loss of weight. Bilateral panuveitis, with iritis, inflammatory vitreous opacities associated with small, round, grayish retinal lesions. The duodenum showed a swollen mucosa, which was flecked over with pinpoint grayish grains. A small-bowel biopsy disclosed PAS-positive granules in the macrophages of the lamina propria mucosa, pathognomonic of Whipple's disease. RESULTS After antibiotic treatment with trimethoprim and sulfamethoxazole there was no relapse of the panuveitis during the follow-up period of 18 months.

Humans↗

PubMed1994

Long-term results of pars plana vitrectomy in the management of complicated uveitis.

This retrospective study evaluates the long term efficacy of pars plana vitrectomy on the preservation of vision in complicated chronic uveitis, including endogenous intermediate uveitis and other entities. Combined vitrectomy-lensectomy was performed in 10 eyes with complicated cataracts, and 18 vitrectomies were done without lensectomies. The mean follow up was 45 months. Additional retinal surgery (for example, scleral buckling) was performed in five eyes. Visual acuity improved in 23 eyes (82.8%) following surgery, with 16 eyes (57%) achieving a vision better than 6/24. The main causes for vision less than 6/24 were persistent cystoid macular oedema (three eyes), macular puckers (one eye), retinal vascular obliterations (four eyes), optic atrophy (five eyes), and chorioretinal scars (seven eyes). Postoperative complications were cataract formation (seven eyes), cystoid macular oedema (one eye), and tractional retinal detachments (three eyes). The surgical intervention resulted in a remarkable reduction of the severity of inflammation or frequency of exacerbations, and allowed significant tapering (11 eyes) or withdrawal (11 eyes) of the topical steroids, or oral corticosteroids (10 cases). Pre-existent cystoid macular oedema resolved in three eyes. Pars plana vitrectomy, eventually combined with lensectomy, may visually rehabilitate eyes with chronic uveitis and media opacities, and may reduce the activity of disease postoperatively.

Adolescent↗

PubMed1994

Electron probe X-ray microanalysis of epithelial cells: aspects of cryofixation.

Content and distribution of diffusible ions in epithelial cells were studied by scanning transmission electron microscopy and energy dispersive electron probe X-ray microanalysis of freeze-dried cryosections from trout kidney, rat liver and Malpighian tubules of Drosophila larvae. Cryofixation of small excised kidney and liver samples by rapid immersion into liquid propane resulted in intracellular K/Na-ratios < 1. In contrast, K/Na-ratios > 7 were obtained after in situ cryofixation by means of a cryopunching device which allows tissue pieces to be frozen during excision from the intact organ. Isolated hepatocytes cryofixed in a small droplet of culture medium had a K/Na-ratio of 3.7. After culturing the hepatocytes, the K/Na-ratio increased to 24. Effects of extracellular media of different composition on the intracellular element content were studied. Malpighian tubules of Drosophila larvae were cryofixed by rapid immersion into liquid propane, and the distribution of K across the cells forming the tubules from the basal to the apical cell membrane was measured. An increasing K gradient was found from the intermediate to the apical cytoplasm. The intracellular K distribution was dependent on ions and transport inhibitors present in the fluid surrounding the Malpighian tubules within the larvae. Content and distribution of ions in epithelial cells sensitively depend on the physiological state immediately before cryofixation. Thus, electron probe X-ray microanalysis of cells and cell functions requires careful selection and control of the cell system to be studied.

Animals↗

PubMed1994

Histopathologic findings in large uveal melanomas after brachytherapy with iodine 125 ophthalmic plaques.

Eyes of 25 patients among a series of 100 consecutive patients who underwent iodine 125 brachytherapy for extremely large uveal melanomas measuring more than 7-8 mm in height had to be enucleated after an average interval of 1.4 years. The dose delivered to the tumor apex was 120-150 Gy. Indications for enucleation were most frequently radiation-induced alterations in the anterior segment with loss of fundus visibility. Eight cases showed insufficient tumor regression, and two cases were suspicious for growth. Microscopically complete tumor necrosis was found in ten eyes. Six cases were classified as "uncertain tumor regression." Apparently "viable" tumor cells were seen in nine eyes. This group of eyes showed a significantly shorter interval between therapy and enucleation. One specimen showed extraocular tumor extension. Brachytherapy with iodine 125 may result in complete tumor necrosis, even in large uveal melanomas. The morphologic extent of tumor necrosis seems to be positively correlated with the interval after therapy.

Aged↗

PubMed1994

[Biochemical and histochemical analysis of age related lipid deposits in Bruch's membrane].

In histochemical studies the age-related deposition of different lipids in Bruch's membrane has been seen. This is important for the pathogeneses of age-related macular degeneration due to changes in diffusion characteristics. Because the specificity of histochemical results is limited, a correlation of histochemical lipid analysis with biochemical methods was performed. The macular Bruch's membrane of 27 donors (age 1-97 years) was analyzed. The results of this analysis demonstrated that the increasing histochemical staining for lipids in Bruch's membrane corresponded with an increasing amount of lipids extracted from Bruch's membrane in biochemical analysis. This lipid deposition progressed exponentially with age. However, a large variation in the type of lipid deposited could be observed, with predominant deposition of phospholipids in some eyes and of neutral lipids in others. Furthermore, the phospholipids extracted were differentiated into 50% phosphatidylcholine, 30% phosphatidylethanolamine and 20% phosphatidylinositol and phosphatidylserin. The deposition of lipids, especially neutral lipids, in Bruch's membrane may change its diffusion characteristics. This appears to be important for the pathogenesis of age-related pigment epithelium detachments. The composition of the phospholipids extracted from Bruch's membrane supports, furthermore, the concept that the material deposited is the result of metabolic limitations in the degradation of photoreceptor outer segment material.

Adolescent↗

PubMed1994

[Focal hemorrhagic chorioretinopathy. Clinical differentiation and visual prognosis].

Macular choroidal neovascularization in young adults without any known underlying diseases is referred to under the general term of focal hemorrhagic chorioretinopathy. In endemic areas of the USA an infection with Histoplasma capsulatum is thought to be the causative agent, but in Europe the pathogenesis of this condition is unknown. With the aim of finding how European patients with this disease might be detected by clinical examination and to estimate the prognosis for sight in the affected eye and the fellow eye, a follow-up examination (follow up 1-24 years, mean 7 years) of 88 patients (age 15-48 years, mean 33.6 years) was undertaken. Most patients were between 20 and 40 years of age and mildly myopic. The number of chorioatrophic scars associated with the choroidal neovascularization in particular varied widely between patients. Therefore, this characteristic is most useful for clinical differentiation between patients. In contrast, the development of an atrophic conus at the optic disc was predominantly correlated with worsening myopia. One-third of all patients experienced decreased vision during follow-up. In two-thirds of the group, however, the final vision was still 0.1 or better. The initial visual prognosis in the eye affected was predominantly dependent upon the location of the neovascular membrane in relation to the fovea and therefore upon the possibility of photocoagulation treatment. Long-term follow up in these patients revealed visual acuity decreased further only in eyes with increasing atrophy of the retinal pigment epithelium surrounding the disciform or laser scar. One-fifth of the patients also developed choroidal neovascularization in the fellow eye.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

Heterogeneous distribution of elemental contents in the larval Malpighian tubules of Drosophila hydei: X-ray microanalysis of freeze-dried cryosections.

The elements Na, Cl and K are distributed heterogeneously in the larval cells of the four Malpighian tubules of Drosophila hydei. Elemental gradients are steeper when they are related to the dry weight in comparison to the weight of water. The high contents of Na, Cl and K in the cytoplasm close to the basal plasma membrane differ significantly from the low values found in the neighboring basal "labyrinth" and in the intermediate cytoplasm. Elemental contents (K, Cl) increase from the intermediate cytoplasm to the apical microvilli and further to the lumen. The K/Na-ratio changes across the cells from 0.9 in the hemolymph to 2 in the basal cytoplasm close to the plasma membrane, to 27 in the microvilli, and 89 in the fluid phase of the lumen. In the lumen, K is accumulated in proteoglycan containing type-II concretions. The water content increases from the distal to the proximal segments of anterior and posterior tubules.

Animals↗

PubMed1993

Effects of bafilomycin A1 and amiloride on the apical potassium and proton gradients in Drosophila Malpighian tubules studied by X-ray microanalysis and microelectrode measurements.

The intracellular distribution of potassium in Malpighian tubules from Drosophila larva was measured by electron probe X-ray microanalysis of freeze-dried cryosections. Application of amiloride alone to the haemolymph space had no effect on the intracellular potassium concentration in the region of intermediate cytoplasm (between the basal region of basal membrane infoldings and the apical brush border), whereas a potassium increase as well as a chloride increase was observed after simultaneous blocking of the potassium conductance of the basal membrane with barium. Injected bafilomycin and amiloride applied in the haemolymph caused an increase of the potassium content in the basal cytoplasm but not in the microvilli. In addition, the intracellular water portion was decreased by bafilomycin. pH measurements in isolated larval anterior tubules with proton-selective microelectrodes showed that bafilomycin added to the bathing solution caused a decrease in intracellular pH. Addition of amiloride had no significant effect on intracellular pH, but the pH of the luminal fluid was decreased within 1 min by 0.5 pH units. The amiloride-induced luminal pH decrease could be inhibited by the metabolic blocker KCN as well as by bafilomycin. Furthermore, removing potassium from the bathing saline caused a slow luminal acidification, which could be blocked by KCN. Our results support the hypothesis of a functionally coupled transport system in the apical membrane consisting of a bafilomycin-sensitive V-ATPase and a K(+)-dependent, amiloride-sensitive K+/H+ exchange system.

Amiloride↗

PubMed1993

[Therapy of cystoid diffuse macular edema after uveitis and cataract surgery with the carbonic anhydrase inhibitor acetazolamide (Diamox)].

BACKGROUND: Observations made by Cox, Bird et al. (1988), who first used acetazolamide (Diamox) for treatment of macular edema of various origin in a higher number of patients, let assume a positive effect of this therapy on fluid accumulation specifically inside the inner retinal layers. Based on these studies 15 patients (20 eyes) with cystoid or cystoid-diffuse macular edema were treated with acetazolamide in a pilot-study. MATERIALS AND METHODS: Eleven patients (fifteen eyes) had postuveitic macular edema, four other patients (five eyes) had cystoid edema following cataract surgery. Patients with additional diseases causing macular edema of retinal vascular origin were excluded. The initial dose was 500 mg daily. In one patient responding to therapy the dose was gradually reduced after three weeks down to a minimum of 125 mg every second day. For evaluation of the therapeutical results fluorescein angiography and visual acuity were taken into account. RESULTS: Eleven patients (fourteen out of twenty eyes) showed a distinct therapeutical effect with decrease of macular edema in repeatedly controlled fluorescein angiography. All these patients had a subjective improvement of vision which correlated with an increase of visual acuity in exactly one half of all patients. Therapy was stopped, when the macular edema had still appeared unchanged in angiography after three weeks or when--in spite of fluid reduction in angiography--no improvement of visual acuity could be obtained in the next two months. The maintenance dose showed large individual variation with a minimum of 125 mg every second day and a maximum of 250 mg per day. Attempts to stop therapy resulted in a early reappearance of the edema of original extension with corresponding deterioration of visual acuity and sensitivity of central visual field. In a few patients even the reduction of the dose below the individual maintenance dose could be demonstrated angiographically. All patients were under continuous internal medical control, permanent side-effects of acetazolamide with the doses used in this study were not seen. CONCLUSIONS: The results show that acetazolamide is a basically effective agent against cystoid macular edema and that a therapeutical trial is justified based on the treatment criteria of this study. The factors limiting the therapeutical effect of acetazolamide cannot yet be evaluated on the basis of the small amount of patients in this pilot-study. Considering the patient data a time factor depending on the period between onset of edema-related symptoms and begin of treatment is likely. In the group of unsuccessfully treated cases we had the patients with the longest period of preexisting edema (more than one year) of the study.

Acetazolamide↗

PubMed1993

Hexadecylphosphocholine may produce reversible functional defects of the retinal pigment epithelium.

Hexadecylphosphocholine is a synthetic phospholipid derivative that has antitumor activity due to its interference with membrane functions. Animal experiments have shown photoreceptor and retinal pigment epithelium (RPE) degeneration after its systemic application. In a phase II trial of hexadecylphosphocholine therapy in 23 patients with advanced metastatic colorectal or lung cancer, visual acuity and color vision testing, slit-lamp examination, tonometry, fundoscopy (including photodocumentation), visual field testing, electrooculography (EOG), and electroretinography (ERG) were performed. A baseline examination was carried out prior to therapy. Patients were reexamined after 2 months and after 5 months. In all, 71% of the patients had a reduced light peak in the EOG during therapy. After the end of therapy the light peak improved again and became normal in most patients. The statistical analysis showed that the light-peak values during therapy were significantly lower than the baseline and posttreatment values. This indicates that hexadecylphosphocholine might be capable of producing a partly reversible functional defect of the RPE. Apart from this finding, no other functional or morphological ocular side effect was detected. The functional changes observed in our patients as well as the morphological changes found in animal experiments are similar to those reported for known diseases of the RPE-photoreceptor complex. Therefore, hexadecylphosphocholine-induced retinopathy might become useful as an animal model for such diseases.

Adenocarcinoma↗

PubMed1993

[Ocular complications of long-term survival of bone marrow transplantation. A prospective study with 21 patients].

BACKGROUND: Survival time after bone marrow transplantation is getting increasingly longer and secondary ocular complications need to be identified and deserve more attention as so far. PATIENTS AND METHODS: We evaluated the ocular complications of 21 not selected, long-term survivors after bone marrow transplantation in a prospective study. The ophthalmological examination consisted of visual acuity, slit lamp examination, tonometry and ophthalmoscopy. It included also determination of tears break-up-time, Jones-test, rose bengal staining and impression cytology of the conjunctiva. RESULTS: The major ocular complication was the development of a keratoconjunctivitis sicca syndrome in 14 of the 21 patients. This complication is probably due to the total-body irradiation in the preparative before and to the development of a chronic Graft-versus-Host-Disease after transplantation. 13 of the 21 patients developed a cataract. This might be a result of the total-body irradiation and a prolonged high steroid intake. CONCLUSION: The frequency and severity of ocular complications suggest that detailed ocular examinations should be performed routinely in patients after bone marrow transplantation.

Anemia, Aplastic↗

PubMed1992

Severe visual loss associated with retinal telangiectasis and facioscapulohumeral muscular dystrophy.

Facioscapulohumeral (FSH) muscular dystrophy is known to be associated with retinal telangiectasis. However, there are only few reports of severe visual loss due to exudative complications, so the risk to vision has not been established. Because of the possible therapeutic implications, we have described two cases of young girls who developed FSH muscular dystrophy and exudative retinal detachment due to telangiectasis. In the first patient, the severity of the disease precluded visual recovery despite extensive photo- and cryotherapy. In the other, visual acuity in both affected eyes was retained after treatment. Fundus examinations in young children at risk of having the gene for FSH muscular dystrophy may be justified so that retinal vascular disease can be detected before it becomes untreatable.

Blindness↗