Inhibition of lysosomal degradative functions in RPE cells by a retinoid component of lipofuscin

PURPOSE: To investigate the effect of the lipofuscin component N-retinylidene-N-retinylethanolamine (A2-E) on degradative functions of lysosomes in human retinal pigment epithelial (RPE) cells and to evaluate its mechanism of action. METHODS: A2-E was coupled to low-density lipoprotein (LDL). Human RPE cell cultures were loaded with the A2-E/LDL complex, and controls were run with medium containing LDL alone. To determine whether A2-E accumulated in lysosomes, cells were fractionated in a Percoll gradient, and protein degradation was determined by metabolic labeling and measurement of the release of low-molecular-weight radioactivity. Lysosomal degradation was distinguished from nonlysosomal degradation by inclusion of NH4Cl in the medium. The metabolism of sulfated glycosaminoglycans was studied by radiosulfate incorporation in pulse-chase experiments. Intralysosomal pH was determined using a fluorescent lysosomotropic pH indicator. RESULTS: A2-E accumulated almost exclusively in the lysosomal compartment. Lysosomal protein degradation was reduced in a dose-dependent fashion in A2-E-treated cells. The selectivity of A2-E on lysosomal function was demonstrated by its lack of effect on degradation of extralysosomal protein. Lysosomal glycosaminoglycan catabolism of RPE cells was also strongly inhibited by A2-E. Lysosomal pH was increased by A2-E. CONCLUSIONS: The findings indicate that accumulation of A2-E in RPE cells interferes with lysosomal functions as exemplified by its inhibitory effect on protein and glycosaminoglycan catabolic pathways. The quaternary amine character of the A2-E apparently causes a perturbation of the acidic intralysosomal milieu, resulting in diminished hydrolase action and consequent accumulation of undegraded material. Such mechanism could be operative in retinal diseases associated with excessive lipofuscin accumulation including age-related macular degeneration.     

Der metaphysäre Trümmerbruch

The most frequent localization of fractures in elderly patients are the metaphysis of the distal radius, the metaphysis of the proximal humerus and the metaphysis of the proximal femur. Displaced fractures of the distal radius should be reduced anatomically with a broad indication for surgery. A unilateral frame is the method of choice in multi-fragmentary and articular fractures although this procedure carries some disadvantages. Displaced proximal fractures of the head of the humerus should be reduced and fixed operatively. Minimal invasive procedures like tension band fixation lead to better results than fixation with plates. Non-reducible four-part fractures require primary prosthetic replacement. If standard procedures in the treatment of distal fractures of the humerus fail because of severe osteoporosis, tension band fixation may allow functional post-operative treatment. Fractures of the trochanteric region of the femur can be stabilized by several dynamic standard implants that permit early weight bearing. If fixations should fail, corrective osteotomies or changing of implants--in rare cases combined with bone cement--may be necessary. Each case requires an individualized procedure in order to ensure optimal restoration of function and mobility in elderly patients.     

Bilaterale diffuse uveale melanozytäre Proliferation bei metastasierendem Mammakarzinom

A 64-year-old female patient with a history of metastatic breast cancer presented with bilateral deterioration of visual acuity over a period of several weeks. Examination revealed patchy fundus pigmentation, serous retinal detachment and cataract in both eyes. After diagnosis of a bilateral diffuse uveal melanocytic proliferation (BDUMP) and due to disease progression, a course of plasmapheresis three times a week over a period of 2 weeks was initiated. Apart from the occurrence of peripheral edemas the therapy was well-tolerated by the patient. Treatment success could not be evaluated because the patient died a short time later. This is the first reported case of BDUMP due to breast cancer.     

Correction to: A guide to classify tattoo motives in Mexico as a tool to identify unknown bodies

International Journal of Legal Medicine -     

Gastric emptying in Type II (non-insulin-dependent) diabetes mellitus before and after therapy readjustment: no influence of actual blood glucose concentration

Aims/hypothesis. Hyperglycaemia that is induced short-term slows gastric emptying in healthy subjects and patients with diabetes mellitus. Little information is available on the impact of longer-lasting, naturally occurring blood glucose increases and their reduction to euglycaemic values. We studied the relation between gastric emptying and pre-prandial and postprandial blood glucose concentrations in patients with Type II (non-insulin-dependent) diabetes mellitus and secondary failure to respond to oral hypoglycaemic treatment (a) before readjusting hypoglycaemic therapy and (b) 1 week thereafter.¶Methods. We studied 9 female and 1 male patient (age 60–78 years, BMI 21.9–32.5 kg/m², diabetes duration 3–33 years, HbA_{1 c} 8.8–13.2 %). Gastric emptying of a radiolabelled semisolid 1168 kJ meal was recorded scintigraphically.¶Results. Blood glucose concentration pre-prandial and postprandial was considerably lower subsequent to than before therapy readjustment in all patients (fasting, 7.9 mmol/l ± 1.5 SD vs 11.7 ± 1.7 mmol/l; 60 min postprandial, 11.7 ± 2.0 vs 15.4 ± 2.2 mmol/l). By contrast, gastric emptying was unchanged (residual radioactivity in stomach 50 min postprandial 65.7 ± 14.1 % vs 66.5 ± 12.9 %). There was no relation between emptying and either fasting blood glucose concentration or its postprandial increase.¶Conclusion/interpretation. The data do not support a major impact of actual, longer-lasting, naturally occurring blood glucose concentrations upon the rate of gastric emptying in patients with Type II diabetes. [Diabetologia (1999) 42: 1410–1412]     

Increased gene transfer into human hematopoietic progenitor cells by extended in vitro exposure to a pseudotyped retroviral vector

Retroviral-mediated gene transfer is the most attractive modality for gene transfer into hematopoietic stem cells. However, transduction efficiency has been low using amphotropic Moloney murine leukemia virus (MoMLV) vectors. In this study, we investigated modifications of gene transfer using amphotropic MoMLV vectors in cell-free supernatant for their ability to increase the currently low transduction of both committed hematopoietic progenitors, granulocyte-macrophage colony- forming units (CFU-GMs), and their precursors, long-term culture- initiating cells (LTC-IC). First, based on the observation that bone marrow cells express more gibbon ape leukemia virus (GALV) receptor (Glvr-1) than amphotropic receptor (Ram-1), PG13/LN, which is a MoMLV vector pseudotyped with the GALV envelope, was compared with the analogous amphotropic envelope vector (PA317/LN). Second, progenitor cell transduction efficiency was compared between CD34 enriched and nonenriched progenitor populations. Third, the duration of transduction in vitro was extended to increase the proportion of progenitor cells that entered cell cycle and could thereby integrate vector cDNA. In 20 experiments, 1 x 10(6) marrow or peripheral blood mononuclear cells (PBMCs)/mL were exposed to identical titers of pseudotyped PG13/LN vector or PA317/LN vector in the presence of recombinant human interleukin-1 (IL-1), IL-3, IL-6, and stem cell factor (SCF; c-kit ligand) for 5 days. 50% of fresh vector supernatant was refed daily. Hematopoietic progenitor cells as measured by G418-resistant granulomonocytic colony (CFU-GM) formation were transduced more effectively with PG13/LN (19.35%) than with PA317/LN (11.5%, P = .012). In 11 further experiments, enrichment of CD34 antigen positive cells significantly improved gene transfer from 13.9% G418-resistant CFU-GM in nonenriched to 24.9% in CD34-enriched progenitor cells (P < .01). To analyze gene transfer after extended growth factor-supported long-term culture, 1 x 10(6) marrow cells/mL were cultured with IL-1, IL-3, IL-6, and SCF (50 ng/mL each) for 1, 2, and 3 weeks. Fifty percent of PG13/LN supernatant with growth factors was refed on 5 days per week. Five percent of marrow CFU-GM and 67% of LTC-IC were G418 resistant at 1 week (n = 4), 60% of CFU-GM and 100% of LTC-IC were resistant at 2 weeks (n = 2) and 74% of CFU-GM (n = 4) and 82% of LTC-IC (n = 2) were resistant at three weeks.(ABSTRACT TRUNCATED AT 400 WORDS)     

Age-related macular degeneration

Age-related macular degeneration is a major cause of blindness worldwide. With ageing populations in many countries, more than 20% might have the disorder. Advanced age-related macular degeneration, including neovascular age-related macular degeneration (wet) and geographic atrophy (late dry), is associated with substantial, progressive visual impairment. Major risk factors include cigarette smoking, nutritional factors, cardiovascular diseases, and genetic markers, including genes regulating complement, lipid, angiogenic, and extracellular matrix pathways. Some studies have suggested a declining prevalence of age-related macular degeneration, perhaps due to reduced exposure to modifiable risk factors. Accurate diagnosis combines clinical examination and investigations, including retinal photography, angiography, and optical coherence tomography. Dietary anti-oxidant supplementation slows progression of the disease. Treatment for neovascular age-related macular degeneration incorporates intraocular injections of anti-VEGF agents, occasionally combined with other modalities. Evidence suggests that two commonly used anti-VEGF therapies, ranibizumab and bevacizumab, have similar efficacy, but possible differences in systemic safety are difficult to assess. Future treatments include inhibition of other angiogenic factors, and regenerative and topical therapies.