Incident Cancer Risk of Patients with Prevalent Type 2 Diabetes Mellitus in Hungary (Part 2).

(1) Background: Among the chronic complications of type 2 diabetes mellitus, cancer has become the leading cause of death in several countries. Our objective was to determine whether prevalent type 2 diabetes mellitus is associated with a higher incidence of cancer. (2) Methods: This study comprised a nationwide analysis conducted in Hungary. The study population was divided into two groups: a type 2 diabetes mellitus group vs. a non-diabetic group. The primary outcome was the risk related to overall cancer incidence; a key secondary outcome was the overall incidence of cancer in distinct study years; and a further outcome was the annual percent changes. (3) Results: The odds ratio related to the overall incidence of cancer was 2.50 (95% confidence interval: 2.46-2.55, p < 0.0001) in patients with diabetes as related to non-diabetic controls. The odds ratio was higher in males than in females [ORmales: 2.76 (2.70-2.82) vs. ORfemales: 2.27 (2.22-2.33), p < 0.05 for male-to-female comparison]. The annual cancer incidence rate declined in non-diabetic controls, but not in patients with diabetes [-1.79% (-2.07--1.52%), p < 0.0001] vs. -0.50% (-1.12-+0.10%), p = 0.0991]. Several types of cancer showed a decreasing tendency in non-diabetic controls, but not in patients with type 2 diabetes. (4) Conclusions: Type 2 diabetes is associated with a higher risk of cancer. While the cancer incidence decreased for non-diabetic individuals with time, it remained unchanged in patients with T2DM.

Incident Cancer Risk in Patients with Incident Type 2 Diabetes Mellitus in Hungary (Part 1).

(1) Background: Patients with type 2 diabetes mellitus (T2DM) are at higher risk of cancer but how these two diseases associate is still debated. The goal of this study was the assessment of the overall incidence of cancer among patients with newly diagnosed T2DM in Hungary. (2) Methods: A nationwide, retrospective, longitudinal study was performed using a Hungarian database. After exclusion of cases of age < 18 years, with gestational diabetes, with polycystic ovary syndrome, and with type 1 and prevalent type 2 diabetes mellitus, the incident T2DM (approx. 50,000 cases yearly) and for comparison, the diabetes-free Hungarian adult population (approx. 7,000,000 cases yearly) was included in the study. The primary endpoints were the overall and site-specific incidence and annual percentage change of the incidence of cancer in both populations. (3) Results: The overall incidence of cancer in patients amounted to 29.4/1000 and 6.6/1000 with or without T2DM, respectively, and the OR (95%CI) of cancer of the T2DM group was 4.32 (4.14-4.53), p < 0.0001. The risk of having cancer was age dependent. The incidence of cancer was declining in the non-diabetic but was unchanged in the T2DM population. The average lag time of diagnosing cancer after the detection of T2DM was 3.86 months. (4) Conclusions: Incident T2DM is associated with a significantly higher overall risk of incident cancer, with a reverse correlation of age. Newly registered T2DM patients were suggested to be screened for cancer within 6 months.

Risk of morbidity and mortality in patients with type 2 diabetes treated with sodium-glucose cotransporter-2 inhibitor and/or dipeptidyl peptidase-4 inhibitor: a nationwide study.

INTRODUCTION: Mortality and disability in diabetes mellitus are determined mostly by cardiovascular complications and cancer. The impact of dipeptidyl peptidase-4 inhibitor (DPP-4i) and sodium-glucose cotransporter-2 inhibitor (SGLT2i) monotherapy or combination on long-term complications of type 2 diabetes mellitus was studied. RESEARCH DESIGN AND METHODS: Patients with type 2 diabetes treated with DPP-4i or SGLT2i during a 3-year period were identified in the database of the National Institute of Health Insurance Fund in Hungary. All-cause mortality, acute myocardial infarction, stroke, hospitalization for heart failure (HHF), lower limb amputation (LLA) and cancer were assessed. Outcomes of add-on SGLT2i to DPP-4i treatment in comparison with switching DPP-4i therapy to SGLT2i were also evaluated. After propensity score matching, survival analysis was performed with a Cox proportional hazards model. RESULTS: After propensity score matching, both SGLT2i and DPP-4i groups included 18 583 patients. All-cause mortality (HR, 0.80; 95% CI 0.68 to 0.94; p=0.0057), HHF (HR, 0.81; 95% CI 0.71 to 0.92; p=0.0018), and risk of cancer (HR, 0.75; 95% CI 0.66 to 0.86; p<0.0001) were lower in the SGLT2i population compared with DPP-4i. Risk of LLA was higher in the SGLT2i group (HR, 1.35; 95% CI 1.03 to 1.77; p=0.0315). SGLT2i in combination with DPP-4i results in lower all-cause mortality (HR, 0.46; 95% CI 0.31 to 0.67; p=0.0001), with a lower trend in stroke, LLA, HHF and cancer, but without any statistical difference. CONCLUSIONS: SGLT2i treatment leads to a lower risk of overall mortality, HHF and cancer when compared with DPP-4i treatment. Adding SGLT2i to DPP-4i instead of switching from DPP-4i to SGLT2i further lowers the risk of all-cause mortality.

Exenatide induces aortic vasodilation increasing hydrogen sulphide, carbon monoxide and nitric oxide production.

BACKGROUND: It has been reported that GLP-1 agonist exenatide (exendin-4) decreases blood pressure. The dose-dependent vasodilator effect of exendin-4 has previously been demonstrated, although the precise mechanism is not thoroughly described. Here we have aimed to provide in vitro evidence for the hypothesis that exenatide may decrease central (aortic) blood pressure involving three gasotransmitters, namely nitric oxide (NO) carbon monoxide (CO), and hydrogen sulphide (H2S). METHODS: We determined the vasoactive effect of exenatide on isolated thoracic aortic rings of adult rats. Two millimetre-long vessel segments were placed in a wire myograph and preincubated with inhibitors of the enzymes producing the three gasotransmitters, with inhibitors of reactive oxygen species formation, prostaglandin synthesis, inhibitors of protein kinases, potassium channels or with an inhibitor of the Na+/Ca2+-exchanger. RESULTS: Exenatide caused dose-dependent relaxation of rat thoracic aorta, which was evoked via the GLP-1 receptor and was mediated mainly by H2S but also by NO and CO. Prostaglandins and superoxide free radical also play a part in the relaxation. Inhibition of soluble guanylyl cyclase significantly diminished vasorelaxation. We found that ATP-sensitive-, voltage-gated- and calcium-activated large-conductance potassium channels are also involved in the vasodilation, but that seemingly the inhibition of the KCNQ-type voltage-gated potassium channels resulted in the most remarkable decrease in the rate of vasorelaxation. Inhibition of the Na+/Ca2+-exchanger abolished most of the vasodilation. CONCLUSIONS: Exenatide induces vasodilation in rat thoracic aorta with the contribution of all three gasotransmitters. We provide in vitro evidence for the potential ability of exenatide to lower central (aortic) blood pressure, which could have relevant clinical importance.

Association of plasma ortho-tyrosine/para-tyrosine ratio with responsiveness of erythropoiesis-stimulating agent in dialyzed patients.

Objectives Patients with end-stage renal failure (ESRF) treated with erythropoiesis-stimulating agents (ESAs) are often ESA-hyporesponsive associated with free radical production. Hydroxyl free radical converts phenylalanine into ortho-tyrosine, while physiological isomer para-tyrosine is formed enzymatically, mainly in the kidney. Production of 'para-tyrosine' is decreased in ESRF and it can be replaced by ortho-tyrosine in proteins. Our aim was to study the role of tyrosines in ESA-responsiveness. Methods Four groups of volunteers were involved in our cross-sectional study: healthy volunteers (CONTR; n = 16), patients on hemodialysis without ESA-treatment (non-ESA-HD; n = 8), hemodialyzed patients with ESA-treatment (ESA-HD; n = 40), and patients on continuous peritoneal dialysis (CAPD; n = 21). Plasma ortho-, para-tyrosine, and phenylalanine levels were detected using a high performance liquid chromatography (HPLC)-method. ESA-demand was expressed by ESA-dose, ESA-dose/body weight, and erythropoietin resistance index1 (ERI1, weekly ESA-dose/body weight/hemoglobin). Results We found significantly lower para-tyrosine levels in all groups of dialyzed patients when compared with control subjects, while in contrast ortho-tyrosine levels and ortho-tyrosine/para-tyrosine ratio were comparatively significantly higher in dialyzed patients. Among groups of dialyzed patients the ortho-tyrosine level and ortho-tyrosine/para-tyrosine ratio were significantly higher in ESA-HD than in the non-ESA-HD and CAPD groups. There was a correlation between weekly ESA-dose/body weight, ERI1, and ortho-tyrosine/para-tyrosine ratio (r = 0.441, P = 0.001; r = 0.434, P = 0.001, respectively). Our most important finding was that the ortho-tyrosine/para-tyrosine ratio proved to be an independent predictor of ERI1 (ß = 0.330, P = 0.016). In these multivariate regression models most of the known predictors of ESA-hyporesponsiveness were included. Discussion Our findings may suggest that elevation of the ratio of ortho-tyrosine/para-tyrosine could be responsible for decreased ESA-responsiveness in dialyzed patients.

Salivary proteomic analysis of diabetic patients for possible oral squamous cell carcinoma biomarkers.

Since oral squamous cell carcinoma (OSCC) is one of the most important causes of death worldwide, the prevention and early detection plays a crucial role. Recent epidemiological studies have incriminated diabetes as a risk factor for the development of OSCC, as well as oral premalignant lesions. As for the last 20 years diabetes and oral squamous cell carcinoma rates have been increasing rapidly, therefore a reliable detection method of major saliva proteins as possible biomarkers for OSCC is of key priority. In this study we collected whole saliva samples from patients with diabetes and from healthy subjects. To reduce the risk of failure and to keep the investigation good reproducible, we proposed an examination and saliva collecting technique. The proteins were analyzed using SDS-PAGE and MALDI TOF/TOF mass spectrometry. Our findings show that the expression of Annexin A8, Peroxiredoxin-2 and Tyrosine kinase is elevated by patients having diabetes. All these proteins have been previously described in cancer saliva samples also in OSCC. Our current findings showed that testing saliva may be an effective and reliable method for detecting oral cancer in early stages.

Histological diagnosis determines complications of percutaneous renal biopsy: a single-center experience in 353 patients.

BACKGROUND: We studied the connection between complication occurrence related to renal biopsies and histological diagnoses of the biopsy specimen. We also analyzed the distribution of diagnoses in our population. METHODS: We retrospectively studied 353 patients undergoing renal biopsy at the same center. Biopsies were performed after marking the site of puncture by ultrasound imaging. Connection of complications with diagnoses and clinical parameters was evaluated. RESULTS: Complication rate was 44.5% in our study. There was a significantly lower rate of complications in patients with diabetic nephropathy (likelihood ratio, LR = 0.44) or acute tubular necrosis (LR = 0.38), while patients with thin basement membrane syndrome had a more than 6-fold higher risk for development of intrarenal hemorrhage than others. Patients with vasculitis (LR = 2.88) and acute interstitial nephritis (LR = 3.18) have a more than doubled risk for arteriovenous shunts, while in patients with severe arteriosclerosis the prevalence of this complication was lower (LR = 0.46). Arteriovenous shunts developed also at a significantly higher rate in patients with rapidly progressive glomerulonephritis. CONCLUSION: Patients with thin basement membrane syndrome, vasculitis, rapidly progressive glomerulonephritis or acute interstitial nephritis should be observed more carefully after renal biopsy due to the significantly higher risk for certain complications.

Resveratrol improves insulin sensitivity, reduces oxidative stress and activates the Akt pathway in type 2 diabetic patients.

Although resveratrol has widely been studied for its potential health benefits, little is known about its metabolic effects in humans. Our aims were to determine whether the polyphenol resveratrol improves insulin sensitivity in type 2 diabetic patients and to gain some insight into the mechanism of its action. After an initial general examination (including blood chemistry), nineteen patients enrolled in the 4-week-long double-blind study were randomly assigned into two groups: a resveratrol group receiving oral 2 × 5 mg resveratrol and a control group receiving placebo. Before and after the second and fourth weeks of the trial, insulin resistance/sensitivity, creatinine-normalised ortho-tyrosine level in urine samples (as a measure of oxidative stress), incretin levels and phosphorylated protein kinase B (pAkt):protein kinase B (Akt) ratio in platelets were assessed and statistically analysed. After the fourth week, resveratrol significantly decreased insulin resistance (homeostasis model of assessment for insulin resistance) and urinary ortho-tyrosine excretion, while it increased the pAkt:Akt ratio in platelets. On the other hand, it had no effect on parameters that relate to ß-cell function (i.e. homeostasis model of assessment of ß-cell function). The present study shows for the first time that resveratrol improves insulin sensitivity in humans, which might be due to a resveratrol-induced decrease in oxidative stress that leads to a more efficient insulin signalling via the Akt pathway.

Cigarette smoke elicits relaxation of renal arteries.

BACKGROUND: Epidemiological studies suggest that cigarette smoking - probably by eliciting hyperperfusion - increases glomerular filtration rate; thus, we hypothesized that cigarette smoke affects the vasomotor tone of renal arteries. MATERIALS AND METHODS: Acute changes in the resistance index of a segmental renal artery were measured in healthy individuals during smoking. In addition, the effects of water-soluble components of cigarette smoke on the isometric tension of isolated rat renal arteries were investigated in various conditions. RESULTS: In humans, cigarette smoking transiently reduced the resistance index of the renal artery segments (83·25 ± 5·67% of the baseline, P < 0·05). In the experimental model, water-soluble components of cigarette smoke (wCS) - either nicotinic or nicotine-free - elicited dose-dependent relaxations of rat isolated renal arteries (1% solution of nicotinic wCS: 41·18 ± 14·86% relaxation, 5% nicotinic wCS: 79·28 ± 8·91% relaxation, 10% nicotinic wCS 90·3 ± 6·1% relaxation, P < 0·05), which were not affected by removal of the endothelium, or by the soluble guanylate cyclase inhibitor oxadiazolo-quinoxalin-1, or the non specific potassium channel blocker tetraethylammonium, or the K(ATP) channel blocker glibenclamide. However, relaxations were reduced by catalase (1000 U mL⁻¹ catalase + 5% nicotinic wCS: 49·71 ± 18·4%, P < 0·05) and enhanced by superoxide dismutase (200 U mL⁻¹ SOD + 5% nicotinic wCS: 95·7 ± 2·3%, P < 0·05). CONCLUSIONS: On the basis of these findings, we propose that cigarette smoking could contribute to the increased glomerular filtration rate observed in healthy smokers. In addition, cigarette smoke via hydrogen peroxide mediation reduces vasomotor tone of renal arteries, which could lead to hyperperfusion of kidneys.

Potential urinary biomarkers of disease activity in Crohn's disease.

OBJECTIVE: Measurement of the immunoreactive urinary albumin (ir-uAlb) concentration by immunological methods was found to be an effective method to identify disease activity in Crohn's disease (CD). Recently a size-exclusion (SE) high performance liquid chromatography (HPLC) method was developed to measure both ir-uAlb and non-immunoreactive urinary albumin (total, t-uAlb). We aimed to follow-up one of our CD patients with frequent remissions and exacerbation phases comparing the changes of disease activity parameters and the concentration of ir-uAlb and t-uAlb. The surprising results led us to perform measurements in greater depth. MATERIAL AND METHODS: Concentration of ir-uAlb was measured by immunoturbidimetry (IT) and t-uAlb by SE-HPLC. Albumin peak of SE-HPLC was collected and applied to a reversed-phase (RP) HPLC and to gel-electrophoresis. Eluted peaks of RP-HPLC and identified bands of gel-electrophoresis were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). RESULTS: The concentration of t-uAlb was 15 times higher than that of the ir-uAlb during active state. The RP-HPLC and the gel-electrophoresis separation proved that albumin peak by size-exclusion consists of three different peaks. MALDI-TOF/MS measurements identified α1-acid-glycoprotein and Zn-α2-glycoprotein as major, and albumin as minor protein. CONCLUSIONS: Peak of albumin of SE-HPLC contains a significant amount of glycoprotein during the active phase of CD, which could not be detected in remission. Urinary α1-acid-glycoprotein and/or Zn-α2-glycoprotein could be an ideal disease activity biomarker of CD.

Evidence of O-linked N-acetylglucosamine in diabetic nephropathy.

AIMS: There is increasing evidence that O-linked N-acetylglucosamine (O-GlcNAc) plays an important role in cell signaling pathways. It has also been reported that increases in O-GlcNAc contribute to the development of diabetes and diabetic complications; however, little is known about O-GlcNAc levels in diabetic nephropathy (DNP). Therefore the goal of this study was to determine whether O-GlcNAc could be detected in human kidney biopsy specimens, and if so to examine whether O-GlcNAc levels were increased in the kidneys of patients with DNP compared to the non-diabetic individuals. MAIN METHODS: Kidney biopsy specimens were obtained from type-2 diabetic patients (n=6) and patients diagnosed with thin basement membrane nephropathy (n=7) were used as non-diabetic controls. O-GlcNAc levels were assessed by immunohistochemistry using the anti-O-GlcNAc antibody CTD110.6. KEY FINDINGS: We show that O-GlcNAc modification of proteins can be detected in the human kidney biopsy specimens. Furthermore, in diabetic patients, we found significantly increased numbers of O-GlcNAc positive cells in the glomeruli and significantly elevated staining in the tubuli (both in the nucleus and in the cytosol). In addition we also observed an intense, granular O-GlcNAc staining specifically in diabetic tubuli. SIGNIFICANCE: In light of the increase in O-GlcNAc staining in the diabetic patients, we propose that increased O-GlcNAc levels might contribute to the development of diabetic nephropathy.

Effects of pentoxifylline and pentosan polysulphate combination therapy on diabetic neuropathy in type 2 diabetes mellitus.

Vascular dysfunction, including impaired perfusion has a pivotal role in the pathogenesis of microvascular complications in diabetes mellitus. Both pentoxifylline (PF) and pentosan polysulphate (PPS) are known to improve microcirculation. Antioxidant and antiproteinuric effects of PF are also known. In a placebo-controlled study, we determined the possible efficacy of PF-PPS combination therapy on diabetic neuropathy and nephropathy in type 2 diabetic patients. Patients in Verum group (n = 77) received PF-PPS infusions (100-100 mg/day) for 5 days. Control diabetics (Placebo group; n = 12) were given only saline infusions. Specialized cardiovascular autonomic reflex tests, vibration threshold values and urinary albumin excretion were assessed before and after therapy. In Verum group, autonomic score, indicating the severity of cardiac autonomic dysfunction, decreased after therapy (p < or = 0.001). Of the reflexes, deep breath and handgrip tests also improved after therapy (p < or = 0.001). Vibration threshold values, an indicator of the loss of sensory nerve function, were increased after therapy (p < or = 0.001). Results of cardiac autonomic tests and vibration threshold values remained unaltered in Placebo group. Majority of patients had normalbuminuria, which was not affected by PF-PPS. In conclusion, short-term PF-PPS therapy was effective on cardiovascular autonomic function and vibration perception, whereas it failed to reduce albuminuria within normal range in type 2 diabetic patients.

Glucocorticoid-related signaling effects in vascular smooth muscle cells.

Mineralocorticoid receptor blockade protects from angiotensin II-induced target-organ damage. 11beta-Hydroxysteroid dehydrogenase type 2 protects the mineralocorticoid receptor from activation by glucocorticoids; however, high glucocorticoid concentrations and absent 11beta-hydroxysteroid dehydrogenase type 2 in some tissues make glucocorticoids highly relevant mineralocorticoid receptor ligands. We investigated the effects of corticosterone (10(-6) to 10(-12) mol/L) on early vascular mineralocorticoid receptor signaling by Western blotting, confocal microscopy, and myography. Corticosterone initiated extracellular signal-regulated kinase 1/2 phosphorylation in rat vascular smooth muscle cells at > or =10(-11) mol/L doses. Protein synthesis inhibitors had no effect, indicating a nongenomic action. Corticosterone also stimulated c-Jun N-terminal kinase, p38, Src, and Akt phosphorylation at 15 minutes and enhanced angiotensin II-induced signaling at 5 minutes. A specific epidermal growth factor receptor blocker, AG1478, as well as the Src inhibitor PP2, markedly reduced corticosterone-induced extracellular signal-regulated kinase 1/2 phosphorylation, as did preincubation of cells with the mineralocorticoid receptor antagonist spironolactone. Silencing mineralocorticoid receptor with small interfering RNA abolished corticosterone-induced effects. Corticosterone (10(-9) mol/L) enhanced phenylephrine-induced contraction of intact aortic rings. These effects were dependent on the intact endothelium, mineralocorticoid receptor, and mitogen-activated protein kinase kinase 1/extracellular signal-regulated kinase signaling. We conclude that corticosterone induces rapid mineralocorticoid receptor signaling in vascular smooth muscle cells that involves mitogen-activated protein kinase kinase/extracellular signal-regulated kinase-dependent pathways. These new mineralocorticoid receptor-dependent signaling pathways suggest that glucocorticoids may contribute to vascular disease via mineralocorticoid receptor signaling, independent of circulating aldosterone.

Serum carboxymethyllysine predicts mortality in hemodialysis patients.

BACKGROUND: Hemodialysis patients show markedly elevated serum levels of advanced glycation end products (AGEs). AGEs have been implicated in the pathogenesis of vascular damage and are regarded as a class of uremic toxins. However, to date, serum AGE level could not be identified as an independent predictor of mortality. The aim of the present study is to test whether serum level of the AGE carboxymethyllysine (CML) predicts all-cause or cardiovascular mortality in hemodialysis patients. METHODS: Serum total CML concentration was measured by means of enzyme-linked immunosorbent assay in 154 patients receiving long-term hemodialysis. Patients were divided into groups with serum CML levels less and greater than the median (23.8 ng/mg protein). All-cause and cardiovascular mortality were registered during a follow-up of 51 months. The relationship between serum CML level and mortality was tested by using Kaplan-Meier and Cox regression analyses. RESULTS: In the group with low serum CML levels, 38% of patients died during the follow-up period; 23% had a cardiovascular cause of death. However, in the group with high CML levels, 58% died (P < 0.01) and 36% had a cardiovascular cause of death (P < 0.05). The following parameters proved to be independent risk factors of all-cause mortality: age (hazard ratio, 1.056; P < 0.001), preexisting vascular disease (hazard ratio, 2.53; P < 0.05), smoking (hazard ratio, 3.03; P < 0.005), high serum CML level (hazard ratio, 1.776; P < 0.05), and C-reactive protein level (hazard ratio, 1.017; P < 0.001). CONCLUSION: The AGE CML may contribute to increased mortality in patients with uremia.

Accumulation of the hydroxyl free radical markers meta-, ortho-tyrosine and DOPA in cataractous lenses is accompanied by a lower protein and phenylalanine content of the water-soluble phase.

Post-translational modifications of lens proteins play a crucial role in the formation of cataract during ageing. The aim of our study was to analyze protein composition of the cataractous lenses by electrophoretic and high-performance liquid chromatographic (HPLC) methods. Samples were obtained after extracapsular cataract surgery performed by phacoemulsification technique from cataract patients with type 2 diabetes mellitus (DM CAT, n = 22) and cataract patients without diabetes (non-DM CAT, n = 20), while non-diabetic non-cataractous lenses obtained from cadaver eyes served as controls (CONTR, n = 17). Lens fragments were derived from the surgical medium by centrifugation. Samples were homogenized in a buffered medium containing protease inhibitor. Soluble and insoluble protein fractions were separated by centrifugation. The electrophoretic studies were performed according to Laemmli on equal amounts of proteins and were followed by silver intensification. Oxidized amino acid and Phe content of the samples were also analyzed by HPLC following acid hydrolysis of proteins. Our results showed that soluble proteins represented a significantly lower portion of the total protein content in cataractous lenses in comparison with the control group (CONTR, 71.25%; non-DM CAT, 32.00%; DM CAT, 33.15%; p < 0.05 vs CONTR for both). Among the proteins, the crystallin-like proteins with low-molecular weight can be found both in the soluble and insoluble fractions, and high-molecular weight aggregates were found mainly in the total homogenates. In our HPLC analysis, oxidatively modified derivatives of phenylalanine were detected in cataractous samples. We found higher levels of m-Tyr, o-Tyr and DOPA in the total homogenates of cataractous samples compared to the supernatants. In all three groups, the median Phe/protein ratio of the total homogenates was also higher than that of the supernatants (total homogenates vs supernatants, in the CONTR group 1102 vs 633 micromol/g, in the DM CAT group 1187 vs 382 micromol/g and in the non-DM CAT group 967 vs 252 micromol/g; p < 0.05 for all). In our study we found that oxidized amino acids accumulate in cataractous lenses, regardless of the origin of the cataract. The accumulation of the oxidized amino acids probably results from oxidation of Phe residues of the non-water soluble lens proteins. We found the presence of high-molecular weight protein aggregates in cataractous total homogenates, and a decrease of protein concentration in the water-soluble phase of cataractous lenses. The oxidation of lens proteins and the oxidative modification of Phe residues in key positions may lead to an altered interaction between protein and water molecules and thus contribute to lens opacification.