Prostate cancer treatment costs increase more rapidly than for any other cancer-how to reverse the trend?

According to GLOBOCAN, about 1.41 million new prostate cancer (PCa) cases were registered in the year 2020 globally. The corresponding socio-economic burden is enormous. Anti-cancer mRNA-based therapy is a promising approach, the principle of which is currently applied for anti-COVID-19 vaccination, undergoing a detailed investigation in populations considering its short- and long-term effectiveness and potential side effects. Pragmatically considered, it will take years or even decades to make mRNA therapy working for any type of cancers, and if possible, for individual malignancy sub-types which are many specifically for the PCa. Actually, the costs of treating PCa are increasing more rapidly than those of any other cancer. The trend has to be reversed now, not in a couple of years. In general, two main components are making currently applied reactive (management of clinically manifested disease) PCa treatment particularly expensive. On one hand, it is rapidly increasing incidence of the disease and metastatic PCa as its subtype. To this end, rapidly increasing PCa incidence rates in young and middle-aged male sub-populations should be taken into account as a long-term contributor to the metastatic disease potentially developed later on in life. On the other hand, patient stratification to differentiate between non-metastatic PCa (no need for an extensive and costly treatment) and particularly aggressive cancer subtypes requiring personalised treatment algorithms is challenging. Considering current statistics, it becomes obvious that reactive medicine got at its limit in PCa management. Multi-professional expertise is unavoidable to create and implement anti-PCa programmes in the population. In our strategic paper, we exemplify challenging PCa management by providing detailed expert recommendations for primary (health risk assessment), secondary (prediction and prevention of metastatic disease in PCa) and tertiary (making palliative care to the management of chronic disease) care in the framework of predictive, preventive and personalised medicine.

Making a complex dental care tailored to the person: population health in focus of predictive, preventive and personalised (3P) medical approach.

An evident underestimation of the targeted prevention of dental diseases is strongly supported by alarming epidemiologic statistics globally. For example, epidemiologists demonstrated 100% prevalence of dental caries in the Russian population followed by clinical manifestation of periodontal diseases. Inadequately provided oral health services in populations are caused by multi-factorial deficits including but not limited to low socio-economic status of affected individuals, lack of insurance in sub-populations, insufficient density of dedicated medical units. Another important aspect is the "participatory" medicine based on the active participation of population in maintaining oral health: healthcare will remain insufficient as long as the patient is not motivated and does not feel responsible for their oral health. To this end, nearly half of chronically diseased people do not comply with adequate medical services suffering from severely progressing pathologies. Noteworthy, the prominent risk factors and comorbidities linked to the severe disease course and poor outcomes in COVID-19-infected individuals, such as elderly, diabetes mellitus, hypertension and cardiovascular disease, are frequently associated with significantly altered oral microbiome profiles, systemic inflammatory processes and poor oral health. Suggested pathomechanisms consider potential preferences in the interaction between the viral particles and the host microbiota including oral cavity, the respiratory and gastrointestinal tracts. Since an aspiration of periodontopathic bacteria induces the expression of angiotensin-converting enzyme 2, the receptor for SARS-CoV-2, and production of inflammatory cytokines in the lower respiratory tract, poor oral hygiene and periodontal disease have been proposed as leading to COVID-19 aggravation. Consequently, the issue-dedicated expert recommendations are focused on the optimal oral hygiene as being crucial for improved individual outcomes and reduced morbidity under the COVID-19 pandemic condition. Current study demonstrated that age, gender, socio-economic status, quality of environment and life-style, oral hygiene quality, regularity of dental services requested, level of motivation and responsibility for own health status and corresponding behavioural patterns are the key parameters for the patient stratification considering person-tailored approach in a complex dental care in the population. Consequently, innovative screening programmes and adapted treatment schemes are crucial for the complex person-tailored dental care to improve individual outcomes and healthcare provided to the population.

Dietary phytochemicals in breast cancer research: anticancer effects and potential utility for effective chemoprevention.

Cancerous tissue transformation developing usually over years or even decades of life is a highly complex process involving strong stressors damaging DNA, chronic inflammation, comprehensive interaction between relevant molecular pathways, and cellular cross-talk within the neighboring tissues. Only the minor part of all cancer cases are caused by inborn predisposition; the absolute majority carry a sporadic character based on modifiable risk factors which play a central role in cancer prevention. Amongst most promising candidates for dietary supplements are bioactive phytochemicals demonstrating strong anticancer effects. Abundant evidence has been collected for beneficial effects of flavonoids, carotenoids, phenolic acids, and organosulfur compounds affecting a number of cancer-related pathways. Phytochemicals may positively affect processes of cell signaling, cell cycle regulation, oxidative stress response, and inflammation. They can modulate non-coding RNAs, upregulate tumor suppressive miRNAs, and downregulate oncogenic miRNAs that synergically inhibits cancer cell growth and cancer stem cell self-renewal. Potential clinical utility of the phytochemicals is discussed providing examples for chemoprevention against and therapy for human breast cancer. Expert recommendations are provided in the context of preventive medicine.

Engineering of clinical glioma treatment: prediction of pro-invasive molecular events in treated gliomas.

The diffusely infiltrative nature of malignant gliomas is the main obstacle to successful treatment approaches. Advanced simulation models of the in vivo response to therapy conditions are expected to improve malignant glioma treatment substantially. In parallel experiments, human malignant glioma cells underwent either radiation or chemotherapy treatment (chemotreatment) with temozolomide alone, or combined chemoradiation. Cells were treated according to diverse, clinically relevant, therapeutic algorithms. Quantitative 'real-time' polymerase chain reaction (PCR) measurements were performed for target genes, namely vascular endothelial growth factor, p53, and cyclooxygenase-2, which allow a comparative evaluation of pro-invasive molecular events in treated gliomas. The proof-of-principle study simulated variable intratumoural regional conditions. Pro-invasive molecular patterns were strongly dependent on the treatment algorithm, cellular density, and drug delivery. The highest pro-invasive potential was demonstrated for simulated peripheral regions under continued chemoradiation. This result strongly supports the clinical observations of increased aggressiveness and relatively poor response to second-line therapies in post-operatively chemoradiation-treated malignant gliomas at the time of relapse. Individualized and potentially the most effective treatment algorithms can be designed using established gene expression patterns applied on primary cell cultures obtained from individual patients. Individual drug toxicity and response to anti-cancer therapy can be predicted.

Comet assay analysis of single-stranded DNA breaks in circulating leukocytes of glaucoma patients.

PURPOSE: To investigate the amount of single-stranded DNA breaks in circulating leukocytes of primary open-angle glaucoma (POAG) patients. METHODS: A comparative quantification of DNA breaks was performed in circulating leukocytes of POAG patients and healthy controls. The following groups of subjects were compared: (1) POAG patients having primary vascular dysregulation (PVD), (2) POAG patients without PVD, (3) healthy controls with PVD, and (4) healthy controls without PVD. The damage to DNA resulting in single-stranded breaks was assessed by means of the alkaline comet assay in which the damaged DNA migrates out of the nucleus forming a tail, which can be quantified using image analysis. Damage was quantified as the comet tail moment, which represents the extent of DNA damage in individual cells. RESULTS: Leukocytes of POAG patients exerted a significantly higher amount of comet tails, which are indicative of DNA damage, in comparison to control leukocytes (p<0.001). DNA breaks occurred particularly in the subgroup of POAG patients with PVD in comparison to glaucoma patients without PVD (p=0.002). In the control group, there was no significant difference between controls with PVD and controls without PVD (p=0.86). CONCLUSIONS: POAG patients with PVD have a significantly higher rate of DNA breaks than both POAG patients without PVD and healthy controls with and without PVD.

Could activated tissue remodeling be considered as early marker for progressive valve degeneration? Comparative analysis of checkpoint and ECM remodeling gene expression in native degenerating aortic valves and after bioprosthetic replacement.

OBJECTIVES: Aortic stenosis is the leading cause of heart valve disease in elderly. Little is known about molecular mechanisms leading to altered left ventricular geometry generally and, particularly, to remodeling of degenerating aortic valve. Alterations in native degenerating aortic valves and valvular tissue after replacement might result from a stage specific tissue remodeling protein core induced by stress responsible factors. Here we were looking for a possible stage specificity of tissue remodeling and stress responsive checkpoint gene activation in native degenerating human aortic valves and bioprosthetic valvular tissue after replacement. MATERIALS AND METHODS: Specimens of native degenerating aortic valves as well as bioprosthetic valves after replacement were tested for their morphological properties. Native degenerating valves were selected for two groups: non-calcified (7 samples) and calcified (5 samples) one; the third group (5 samples) was consisting of bioprosthetic valve samples after replacement. Individual mRNA-pools were isolated from each tissue sample, and semi-quantitative RT-PCR was performed. Target transcripts of p21(waf1/cip1), MT1-MMP, MMP-2, MMP-9 and TIMP-1 were measured. The specificity was controlled by restriction analysis of PCR products. RESULTS AND CONCLUSIONS: According to the abundant expression of p21(waf1/cip1), a highly activated stress response was found in non-calcified native degenerating aortic valves, whereas no stress response was monitored in valvular tissue after replacement. Whereas MT1-MMP expression was almost equally induced in all three groups investigated, MMP-9 was higher expressed in non-calcified versus calcified native valves, and was not expressed after replacement. An induced expression of MMP-2 was detected in non-calcified native degenerating aortic valves only. An abundant expression of tissue inhibitor of metalloproteinases TIMP-1 was observed in all three groups tested. Apparently, the ECM degradation potential is specifically enhanced in non-calcified native degenerating aortic valves e.g. at the early degeneration stages. In contrast, the replaced valves were found to be actively resorbing tissue with no detectable stress response, where both MT1-MMP and TIMP-1 might play the key role in geometry remodeling.

Non-sufficient cell cycle control as possible clue for the resistance of human malignant glioma cells to clinically relevant treatment conditions.

OBJECTIVES: Human gliomas have a catastrophic prognosis with a median survival in the range of one year even after therapeutic treatment. Relatively high resistance towards apoptotic stimuli is the characteristic feature of malignant gliomas. Since cell cycle control has been shown to be the key mechanism controlling both apoptosis and proliferation, this study focuses on DNA damage analysis and protein expression patterns of essential cell cycle regulators P53 and P21waf1/cip1 in glioma under clinically relevant therapeutic conditions. MATERIAL AND METHODS: U87MG cell line, characterised by wild p53-phenotype relevant for the majority of primary malignant glioblastomas, was used. Glioma cells underwent either irradiation or temozolomide treatment alone, or combined radio/chemo treatment. DNA damage was analysed by the "Comet Assay". Expression rates of target proteins were analysed using "Western-Blot" technique. RESULTS AND CONCLUSIONS: "Comet Assay" demonstrated extensive DNA damage caused by temozolomide treatment alone and in combination with irradiation, correlating well with the low survival rate observed under these treatment conditions. In contrast, irradiation alone resulted in a relatively low DNA damage, correlating well with a high survival rate and indicating a poor therapeutic efficiency of irradiation alone. Unusually low up-regulation of P53 and P21waf1/cip1 expression patterns was produced by the hereby tested stressful conditions. A deficit in cell cycle control might be the clue to the high resistance of malignant glioma cells to established therapeutic approaches.

Cell cycle checkpoints: the role and evaluation for early diagnosis of senescence, cardiovascular, cancer, and neurodegenerative diseases.

Maintenance of genomic integrity is critical for prevention of a wide variety of adverse cellular effects including apoptosis, cellular senescence, and malignant cell transformation. Under stress conditions and even during an unperturbed cell cycle, checkpoint proteins play the key role in genome maintenance by and mediating cellular response to DNA damage, and represent an essential part of the "cellular stress response proteome". Intact checkpoint signal transduction cascades check the presence of genome damage, trigger cell cycle arrest, and forward the information to the protein core of cell cycle machinery, replication apparatus, repair, and/or apoptotic protein cores. Genetic checkpoint defects lead to syndromes that demonstrate chromosomal instability, increased sensitivity to genotoxic stress, tissue degeneration, developmental retardation, premature aging, and cancer predisposition that is most extensively studied for the ATM-checkpoint mutated in Ataxia telangiectasia. Tissue specific epigenetic control over the function of cell cycle checkpoints can be, further, misregulated by aberrant DNA methylation status. The consequent checkpoint dysregulation may result in tissue specific degenerative processes such as degeneration and calcification of heart aortic valves, diabetic cardiomyopathy, hyperhomocysteinemic cerebrovascular, peripheral vascular and coronary heart diseases, neurodegenerative disorders (Alzheimer and Parkinson diseases, amyotrophic lateral sclerosis, glaucoma), and accelerated aging frequently accompanied with cancer. This review focuses on the checkpoints shown to be crucial for unperturbed cell cycle regulation, dysregulation of which might be considered as a potential molecular marker for early diagnosis of and therapy efficiency in neurodegenerative, cardiovascular and cancer diseases. An application of the most potent detection technologies such as "Disease Proteomics and Transcriptomics" also considered here, allows a most specific selection of diagnostic markers.

p21WAF1/CIP1 and 14-3-3 sigma gene expression in degenerated aortic valves: a link between cell cycle checkpoints and calcification.

The mechanisms underlying aortic valve degeneration are largely unknown. Cardiac tissue responds to a variety of stimuli by hypertrophic growth. Molecular mechanisms resulting in the hypertrophic response indicate similarity and overlap with those involved in both cell growth and death. We hypothesized cell cycle control to be the key event in progression regulation of heart valve degeneration followed by tissue mineralization. Human post-operative tissue samples of native non-rheumatic stenosed aortic valves were categorized according to absence (group 1) or presence of calcification (group 2). The samples were ex vivo examined for cell density and presence of macrophage (CD68), as well as expression of two checkpoint genes, p21WAF1/CIP1 and 14-3-3 sigma, arresting the G1 and G2 cell cycle phases, respectively. Expression rates were measured by "Real-Time"-PCR on transcriptional level. Target protein expression was measured and their co-localization in different kinds of valvular cells was tested using immunohistochemical analysis. Whereas macrophages were localized predominantly in sub-endothelial layer of valvular fibrosis, p21WAF1/CIP1 and 14-3-3 sigma expression was observed also in the valvular spongiosa co-localized with alpha-actin positive cells. Significantly higher cell density and inflammation grade were observed in group 2 versus group 1. Accordingly, p21WAF1/CIP1 and 14-3-3 sigma expression was several fold higher in group 1 versus group 2 on both transcription and translation levels. The present findings on degenerated aortic valves show that increased cell density accompanied with consequent calcification might be attributed to the down-regulation of both G1 and G2 checkpoint genes.

Molecular imaging system for possible prediction of active retinopathy in patients with Diabetes mellitus.

OBJECTIVE: The deposition of advanced glycation end products is enhanced in Diabetes mellitus (DM) and has been linked to diabetic complications such as a microvascular disease. Glycated proteins have receptors on mononuclear blood cells (MBCs) and have been shown to generate reactive oxygen species altering gene expression and modifying cellular targets, such as endothelial cells. Retinal angiopathy is a frequently observed microvascular complication in DM-patients. Because of the central role of activated MBCs, we hypothesised a functional link between specific alterations in gene expression of MBCs, an increased activity of matrix proteases in serum, and the extent of retinal angiopathy in DM. MATERIAL AND METHODS: An appearance and proliferation index of diabetic retinopathy was evaluated in 38 DM-patients using fluorescein angiography. Alterations of gene transcription levels in MBCs were investigated using hybridisation of individual mRNA-pools to Atlas Array with a concomitant quantification of specific cDNAs by "Real-Time"-PCR. The activity of matrix metalloproteinases MMP-2 and MMP-9 in individual serum samples was measured by zymography combined with densitometric imaging system. RESULTS AND CONCLUSIONS: Hybridisation to Atlas Array of mRNA-pools isolated from MBCs revealed an enhanced expression of recoverin in DM-patients compared to the control group. "Real-Time"-PCR showed the highest recoverin levels in the DM-subgroup with a high proliferation index. MMP-2 activity was highly increased in 36% of all patients, and in 44, 44, and 19% of patients with proliferative retinopathy, advanced proliferative retinopathy, and no detectable proliferation respectively. In those 3 groups MMP-9 activity was highly increased in 56, 67, and 31% of patients respectively, and in 44% of all DM-patients. In contrast to patients with active proliferation, the simultaneous high activation of all three genes was not observed in patients without active proliferation. The ex vivo molecular imaging system developed in this work may be helpful for the prediction of active proliferative retinopathy in DM.

Expression of ABC-1 transporter is elevated in human glioma cells under irradiation and temozolomide treatment.

OBJECTIVE: Chemo-therapeutic treatment of glioma patients has minor success. Little is known about mechanisms of a pronounced resistance of gliomas towards actual therapies, yet. ABC-1 belongs to the group of transporters known to be involved in the export of hydrophobic substances and vascular regulation. This study investigates an effect of both temozolomide (TMZ) treatment and/or irradiation on the expression of the ABC-1 transporter in human U87-MG glioma cells. MATERIAL AND METHODS: In parallel experiments U87-MG cells underwent either irradiation (RT), chemo-treatment (CT) using TMZ, and combined chemo/radiation-treatment (CT/RT). After each treatment the cells were incubated either 2 or 24 hours at 37 degrees C and counted before protein analysis using Western-Blot technique. RESULTS AND CONCLUSIONS: An exponential growth of cellular density was observed for both untreated and irradiated cells being, however, about 2-times slower in irradiated compared to untreated cells. In contrast the density increase of chemo-treated cells as well as that of cells, which underwent the combined CT/RT treatment was of linear nature. ABC-1 expression was detected in untreated as well as treated cells. Increasing cell density and all kinds of treatment resulted in a considerably enhanced ABC-1 expression. CT treatment resulted in highly up-regulated ABC-1 expression especially in non-confluent cultures compared to untreated cells. Irradiation had a comparable or even higher inducible effect on the ABC-1 expression rates depending, however, on cell density. The highest expression rates were observed in cultures with high cellular density 2 hours after application of the combined treatment. Strong up-regulation of ABC-1 expression under both irradiation and chemo-treatment might be a clue to multidrug and irradiation cross-resistance mechanisms of malignant glioma cells converting the ABC-1 transporter into an attractive pharmacological target for a clinical breakthrough in the therapy of malignant gliomas.

Combined analysis of biochemical parameters in serum and differential gene expression in circulating leukocytes may serve as an ex vivo monitoring system to estimate risk factors for complications in Diabetes mellitus.

OBJECTIVE: Oxidative stress plays a crucial role in the development of complications in Diabetes mellitus (DM). Individual sensitivity against stress, however, varies among DM-patients and results, therefore, in differential severity of consequent complications. To allow more complex interpretation of a delicate antioxidant/free radicals balance and its effect on cellular functions in individual DM-patients, we analysed a correlation between total antioxidant status (TAS), antioxidant gap (AtxGap), level of free radicals (FR), routine clinical biochemical parameters in blood and differential gene expression in circulating leukocytes of DM-patients versus non-diabetic individuals. RESULTS AND CONCLUSIONS: Positive correlation was found between TAS and creatinine (p=0.05), AtxGap and iron (p=0.025), and between AtxGap and anti-streptolysin O (p=0.025). Whereas no correlation was found between FR and any of the routine clinical parameters tested, a negative correlation was observed between AtxGap and glucose content (p=0.025) and between AtxGap and gamma-glutamyltransferase (p=0.05). An increased content of FR was shown to influence significantly an expression of selected stress responsible genes in leukocytes. Transcription levels of NF-kappaB, XRCC1 and 90-kDa heat-shock protein A were increased in all DM-patients compared to non-diabetic individuals. In contrast, an expression of XIAP and cytochrome P450 reductase was up-regulated in patients with decreased levels of both FR and TAS and increased body mass index. This differential expression of the stress responsible genes might be further considered as a potential risk factor for diverse DM-complications helping also in reliable monitoring of supplemental antioxidant therapy and more complex interpretation of delicate antioxidant/free radicals balance.

An enhanced expression of ABC 1 transporter in circulating leukocytes as a potential molecular marker for the diagnostics of glaucoma.

OBJECTIVE: Glaucoma is a neurodegenerative disease. Since vascular dysregulation is supposed to be a risk factor for the development of glaucomatous damage, the preventive treatment might slow down the disease development. The efficiency of the therapeutic treatment depends particularly on a drug efflux pump regulated by ABC transporters. ABC 1 is also known to participate on the vascular regulation. This study was focused on the comparative analysis of ABC 1 expression levels in circulating leukocytes of non-glaucomatous individuals and glaucoma patients. RESULTS AND CONCLUSIONS: The expression rates of ABC 1 were significantly increased in leukocytes of glaucoma patients compared to non-glaucomatous individuals. The expression level of ABC 1 was, furthermore, highly homogeneous in glaucoma patients. In contrast, these expression levels in non-glaucomatous individuals were extremely heterogeneous. This transporter acts as the energy-dependent unidirectional transmembrane cholesterol efflux pump and can export a wide range of hydrophobic drugs. Additionally an observed enhanced ABC 1 expression in circulating leukocytes may be implicated in the vascular regulation mechanisms of glaucoma. We proposed the enhanced expression of ABC 1 in leukocytes as a potential marker for the diagnostics and ex vivo molecular monitoring of glaucoma.

Increased DNA breaks and up-regulation of both G(1) and G(2) checkpoint genes p21(WAF1/CIP1) and 14-3-3 sigma in circulating leukocytes of glaucoma patients and vasospastic individuals.

OBJECTIVE: Vascular disorder leading to local ischemia/reperfusion has been shown to play an important role in the glaucomatous damage. A decreased expression level of XPGC-gene has been found in circulating leukocytes of normal-tension glaucoma patients. Although decreased activity of XPGC-gene leads to insufficient DNA-repair, no leukopenia has been observed in glaucoma. Molecular mechanisms ensuring cell survival have not been elucidated yet for glaucoma with vascular disorder. MATERIAL AND METHODS: Using the ex vivo optical imaging method of alkaline "comet assay" comparative quantification of DNA breaks was performed in circulating leukocytes of non-glaucomatous non-vasospastic and vasospastic individuals as well as both normal-tension and high-tension glaucoma patients. Relative expression levels of the anti-apoptotic factors P21(WAF1/CIP1) and 14-3-3 sigma were investigated in all groups tested. RESULTS AND CONCLUSIONS: The quantification of P21(WAF1/CIP1) showed the highest expression rates in high-tension glaucoma patients which were significantly higher than those in all other groups tested. The highest expression rates of 14-3-3 sigma were found in both groups of glaucoma patients. These expression levels correlated well with DNA breaks measured. Since the expression of P21(WAF1/CIP1) in leukocytes was shown to be crucial for their survival under stress conditions, we suppose further that the up-regulation of this gene is the key event in the survival mechanisms of leukocytes in glaucoma accompanied with vascular disorder. The p21(WAF1/CIP1) gene should be further taken into consideration as a potential marker, the up-regulation of which in circulating leukocytes of vasospastic individuals may indicate an increased risk for the developing glaucoma.

Molecular imaging of perfusion disturbances in glaucoma.

Ocular ischemia resulting from perfusion disturbances may play a major role in initiation of glaucoma. Possibly secondary to ischemia autoimmunogenic events are activated in glaucoma patients with increased prevalence of systemic autoimmune diseases. The determination of potential molecular markers in blood leukocytes could be useful for early noninvasive diagnostics of glaucoma. Our study using subtractive hybridization showed altered gene expression in leukocytes of glaucoma patients in comparison to age and sex matched healthy subjects. Subtracted genes encoding lymphocyte IgE receptor (Fc epsilon RII/CD23), T cell-specific tyrosine kinase, thromboxan A2 receptor, alkaline phosphatase and Na(+)/K(+)-ATPase are differentially expressed in circulating leukocytes of glaucoma patients. These genes show expression profiles characteristic for adherent leukocytes which could be an important contributor to blood-brain barrier breakdown which has been found in glaucoma patients.

Early molecular events in the development of the diabetic cardiomyopathy.

UNLABELLED: Oxidative damage to DNA has been well documented in cardiac cells isolated from diabetic patients and rats with streptozotocin-induced diabetes mellitus (DM). This study evaluates possible molecular mechanisms for early events in the development of DM-induced cardiomyopathy. METHODS: To analyze the mechanism of overexpression of p21(WAF1/CIP1) and inhibition of cyclin D(1) expression in cardiomyocytes of diabetic rats we examined the methylation status of these genes by MS-PCR and assessed the possibility of epigenetic control of their expression. RESULTS: We found that the steady-state expression of both genes is influenced by their methylation status, as an epigenetic event, of their 5'-flanking regions upon development of diabetes. CONCLUSIONS: Oxidative damage contributes to the development of cardiomyopathy via p53-dependent activation of cardiac cell death. This pathway includes de novomethylation of the P53-inducible p21(WAF1/CIP1)-gene encoding a protein which binds to and inhibits a broad range of cyclin-cyclin-dependent kinase complexes.

Effects of dietary deficiency of selective amino acids on the function of the cornea and lens in rats.

Effects of dietary deficiencies of tryptophan and methionin on the transparency of cornea and lens were investigated in young rats (Brown-Norway, BN; Sprague-Dawley, SD) over 3 months. Transparency of the cornea and lens were evaluated in weekly intervals using a photo-slitlamp microscope. After sacrifice and lens fresh weight determination the lenses were prepared for histopathology. Methionin deficiency had no effect on the parameters investigated. Tryptophan deficiency caused severe loss of body weight in both strains, with additional loss of hair in SD rats. These developed corneal neovascularisations and cataracts. BN rats showed an enhanced zone of discontinuity in the lens. Diet intermission arrested the pathological processes in the eye which restarted when feeding the diet again. This observation is supported by lens fresh weight data. DNA staining evidenced that tryptophan deficiency arrested lens fiber maturation in both strains but stimulated corneal neovascularisation only in SD rats.