Serum prolidase activity and oxidative status in patients with diabetic neuropathy

Evaluation of betulinic acid effects on pain, memory, anxiety, catalepsy, and oxidative stress in animal model of Parkinson's disease

Parkinson's disease (PD) is known for motor impairments. Betulinic acid (BA) is a natural compound with antioxidant activity. The present study addresses the question of whether BA affects motor and non-motor dysfunctions and molecular changes in the rat model of PD. The right medial forebrain bundle was lesioned by injection of 6-hydroxydopamine in Male Wistar rats (10-12 weeks old, 270-320 g). Animals were divided into Sham, PD, 3 treated groups with BA (0.5, 5, and 10 mg/kg, IP), and a positive control group received L-dopa (20 mg/kg, P.O) for 7 days. rigidity, anxiety, analgesia, and memory were assessed by bar test, open-field, elevated plus-maze (EPM), tail-flick, and shuttle box. Additionally, the malondialdehyde (MDA), Superoxide dismutase (SOD), glutathione peroxidase (GPx) activity, Brain-derived neurotrophic factor (BDNF) and Interleukin 10 (IL10) levels in the whole brain were measured. BA significantly reversed the 6-hydroxydopamine-induced motor and memory complication in the bar test and shuttle box. It modified anxiety-like behavior neither in open-field nor in EPM. It only decreased the time spent in open arms. Moreover, no significant changes were found in the tail-flick between treatment and sham groups. On the other hand, the level of MDA & IL10 were decreased, while the activity of GPx levels of SOD & BDNF in the rats' brains was increased. Our results showed that BA as a free radical scavenger can account for a possible promise as a good therapeutic agent for motor and non-motor complications in PD however further studies may be needed.

THE RELATIONSHIP BETWEEN OXIDATIVE STRESS AND SERUM PROLIDASE ACTIVITY IN PATIENTS WITH DIABETIC NEPHROPATHY, RETINOPATHY AND NEUROPATHY

Amaç: Diyabetin mikrovasküler komplikasyonlarında oksidatif stresin belirteçlerini incelemek, prolidazın oksidatif stres göstergeleriyle ilişkisini incelemek, prolidazın prediktif değer olarak kullanılabilirliliğini araştırmaktır. Gereç ve Yöntemler: Çalışmaya 112 tip 2 Diyabetes Mellitusu (DM) olan hasta ve 44 sağlıklı kontrol birey alındı. Hastaların ayrıntılı anamnezleri alınıp fizik muayeneleri yapıldı. Açlık plazma glukozu (APG), hemoglobin A1c (HbA1C), kreatinin, spot idrarda mikrototal protein düzeyleri bakıldı. Göz dibi muayenesi ile diyabetik retinopati varlığı araştırıldı. Nöropati varlığı açısından nörolojik muayeneleri yapıldı. Ayrıca tüm hastaların sabah alınan kan örneğinde oksidatif stress için katalaz (CAT), superoksit dismutaz(SOD), glutatyon peroksidaz (GPx), malondialdehit (MDA), nitrik oksit(NO), serum prolidaz aktivitesi ölçümü yapıldı. Bulgular: Tip 2 DM olan hastaların 80’inde (%71,42) komplikasyon mevcut iken 41’inde (%28,58) komplikasyon yoktu. Açlık plazma glukozu diyabetik komplikasyonu olan grupta diğer gruplara anlamlı olarak yüksekti (p

Inflammatory Mechanisms in the Pathophysiology of Diabetic Peripheral Neuropathy (DN)-New Aspects

The pathogenesis of diabetic neuropathy is complex, and various pathogenic pathways have been proposed. A better understanding of the pathophysiology is warranted for developing novel therapeutic strategies. Here, we summarize recent evidence from experiments using animal models of type 1 and type 2 diabetes showing that low-grade intraneural inflammation is a facet of diabetic neuropathy. Our experimental data suggest that these mild inflammatory processes are a likely common terminal pathway in diabetic neuropathy associated with the degeneration of intraepidermal nerve fibers. In contrast to earlier reports claiming toxic effects of high-iron content, we found the opposite, i.e., nutritional iron deficiency caused low-grade inflammation and fiber degeneration while in normal or high non-heme iron nutrition no or only extremely mild inflammatory signs were identified in nerve tissue. Obesity and dyslipidemia also appear to trigger mild inflammation of peripheral nerves, associated with neuropathy even in the absence of overt diabetes mellitus. Our finding may be the experimental analog of recent observations identifying systemic proinflammatory activity in human sensorimotor diabetic neuropathy. In a rat model of type 1 diabetes, a mild neuropathy with inflammatory components could be induced by insulin treatment causing an abrupt reduction in HbA1c. This is in line with observations in patients with severe diabetes developing a small fiber neuropathy upon treatment-induced rapid HbA1c reduction. If the inflammatory pathogenesis could be further substantiated by data from human tissues and intervention studies, anti-inflammatory compounds with different modes of action may become candidates for the treatment or prevention of diabetic neuropathy.

The Serum Prolidase Enzyme Activity as a Biomarker for Evaluation of the Subclinical Vascular Damage in Children with Epilepsy

Backgroud:

Epilepsy is a chronic medical condition requiring long term or even lifelong therapy. Various researches have shown that epilepsy patients have vascular risk factors such as abnormal lipids, insulin, elevated oxidative stress, chronic inflammation, and subclinical atherosclerosis.

Objectives:

The purpose of the present study was to determine serum prolidase enzyme activity as a biomarker in children taking antiepileptic drug treatment through comparison with control cases.

Materials and Methods:

The present study group consists of 61 children (20 females, 41 males) with epilepsy and a control group was formed of 32 healthy individuals (14 females, 18 males). Aspectrophotometric method was used to measure serum prolidase enzyme activity.

Results:

The epilepsy group demonstrated statistically significantly higher prolidase enzyme activity values when compared with the control group (P = 0.003). It was measured that the serum TOS and OSI values were significantly elevated in patients with epilepsy compared to controls (P < 0.001). However, serum TAS values were significantly lower in the epilepsy group than in the control group (P = 0.032).

Conclusions:

These results supported that epileptic patients taking the antiepileptic treatment had increased serum prolidase enzyme activity, suggesting that it may show an increased risk of subclinical vascular damage related to both chronic inflammation and fibrotic process associated with degenerated collagen turnover. Therefore, serum prolidase enzyme activity could be considered a useful biomarker for evaluation of the subclinical vascular damage in children with epilepsy on some antiepileptic drugs.

Evaluation of the Oxidative Stress Level and Serum Prolidase Activity in Patients with Sleep Bruxism

Aims and Objective:

Sleep bruxism is a complicated disease, and its cause remains controversial. If the etiology of bruxism is resolved, the treatment can be adjusted to the prevailing aetiological factor. Thus, the aim of this study was to evaluate the oxidative stress level and serum prolidase activity in patients with sleep bruxism.

Materials and Methods:

Seventy healthy subjects and 51 patients with sleep bruxism were included in this study, and blood samples from all patients were collected. Serum samples were analyzed for total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), and prolidase activity.

Results:

The prolidase, TOS, and OSI levels were significantly higher in patients with bruxism than in the healthy controls (p = 0.001, p = 0.001, p = 0.001, respectively). The TAS level was significantly lower in bruxism patients than in healthy controls (p = 0.003).

Conclusion:

The increased TOS, OSI, and prolidase levels and decreased TAS levels could be assumed to result in oxidative injury in patients with sleep bruxism. However, the study could not determine whether oxidative imbalance and increased serum prolidase levels could be a cause or a result of bruxism.

Serum prolidase activity in patients with cardiac syndrome X

OBJECTIVE:

Although the underlying mechanism is not yet fully understood, Cardiac Syndrome X (CSX) is defined as microvascular dysfunction. Prolidase plays a role in collagen synthesis. Increased serum prolidase activity (SPA) has been shown to correlate with collagen turnover. Augmented collagen turn-over may be associated with vascular fibrosis and microvascular dysfunction. In this study, we assessed whether there was a correlation between CXS and prolidase activity.

METHODS:

This case-control study included 45 consecutive CSX patients (mean age 50.7±6.5 years, 27 women) and 40 healthy controls (mean age 51.2±6.5 years, 25 women). Prolidase activity was determined with the Human Xaa-Pro Dipeptidase/Prolidase enzyme-linked immunosorbent assay kit (Cusabio Biotech Co. Ltd, China).

RESULTS:

Mean prolidase activity was 898.8±639.1 mU/mL in the CSX group and 434.1±289.8 mU/mL in the control group (p<0.001). In ROC analysis, it was found that the SPA value above 350 mU/mL sympathizes with the diagnosis of CSX.

CONCLUSION:

Increased SPA in CXS patients may play an essential role in the pathophysiology of CSX, leading to augmented oxidative stress and vascular fibrosis, endothelial dysfunction, and increased microvascular resistance.

Prolidase - A protein with many faces

Prolidase is a metal-dependent peptidase specialized in the cleavage of dipeptides containing proline or hydroxyproline on their C-termini. Prolidase homologues are found in all kingdoms of life. The importance of prolidase in human health is underlined by a rare hereditary syndrome referred to as Prolidase Deficiency. A growing number of studies highlight the importance of prolidase in various other human conditions, including cancer. Some recent studies link prolidase's activity-independent regulatory role to tumorigenesis. Furthermore, the enzyme or engineered variants have some applications in biotechnology. In this short review, we aim to highlight different aspects of the protein the importance of which is increasingly recognized over the last years.

Relationship between diabetic polyneuropathy, serum visfatin, and oxidative stress biomarkers

BACKGROUND

Diabetic polyneuropathy is a very common complication of diabetes. Numerous studies are available in terms of pathogenesis. But examination methods with low reliability are still not standardized and generally time consuming. High-sensitive, easy-to-access methods are expected. Biochemical markers are one of the subjects of research. We aimed to discover a potential biomarker that can be used for this purpose in patients with diabetes who have not yet developed symptoms of neuropathy.

AIM

To determine the place and availability of visfatin and thiol-disulfide homeostasis in this disorder.

METHODS

A total of 392 patients with type 2 diabetes mellitus were included in the study. The polyneuropathy clinical signs were evaluated with the Subjective Peripheral Neuropathy Screen Questionnaire and Michigan Neuropathy Screening Instrument questionnaire and examination. The biochemical parameters, oxidative stress markers, visfatin, and thiol-disulfide homeostasis were analyzed and correlated with each other and clinical signs.

RESULTS

Subjective Peripheral Neuropathy Screen Questionnaire and Michigan Neuropathy Screening Instrument questionnaire with examination scores were correlated with each other and diabetes duration (P < 0.005). Neuropathy related symptoms were present in 20.7% of the patients, but neuropathy related findings were observed in 43.9% of the patients. Serum glucose, glycated hemoglobin, and visfatin were positively correlated with each other. Also, these parameters were positively correlated with the total oxidative stress index. Total and native thiol was positively correlated with total antioxidant status and negatively with oxidant status. Inversely thiol-disulfide positively correlated with higher glucose and oxidant status and negatively with total antioxidant status (P < 0.005). There was no correlation between visfatin and thiol-disulphide (P = 0.092, r = 0.086). However, a significant negative correlation was observed between visfatin and total with native thiol (P < 0.005, r = -0.338), (P < 0.005, r = -0.448).

CONCLUSION

Diagnosis of neuropathy is one of the issues studied in patients with diabetes. Visfatin and thiol-disulfide balance were analyzed for the first time in this study with inspiring results.

The Role of Oxidative Stress in Peripheral Neuropathy

Peripheral neuropathy (PN) is a common disease affecting about 5% of the general population after the age of 50. Causes of PN are numerous and include genetic, diabetes, alcohol, vitamin deficiencies, and gluten sensitivity among others. This systematic review aimed to study the association between oxidative stress and PN in an attempt to better understand PN pathogenesis. A computer-based, systematic search was conducted on the PubMed database, and ensuing data from included articles was analyzed and discussed in this review. Sixty-nine papers were eligible and were used for this review. Peripheral neuropathy is associated with an increase of reactive oxygen species and a decrease in endogenous antioxidants. Genetic predisposition to oxidative damage may be a factor. Antioxidant treatment is promising regarding treatment. Though further research is necessary to better understand the underlying mechanism, it is evident that oxidative stress is implicated in the pathogenesis of - or is at least systematically present in - PN.

Oxidative Stress And Prolidase Enzyme Activity In The Pathogenesis Of Primary Varicose Veins

Objectives Vascular endothelial dysfunction leads to the emerging of free oxygen radicals, deficiency of antioxidant system, forming of oxidative stress, inflammatory processes and release of proinflammatory cytokines. These things play big role in the development of primary varicose veins. Prolidase has been reported as an indicator of oxidative stress in diabetes, diabetic neuropathy, non-ulcerous dyspepsia, osteoporosis, polycystic over syndrome and many other diseases. The aim of this study is to evaluate the oxidative stress at venous insufficiency and to provide preliminary knowledge about the role of prolidase enzyme in varicose vein formation. Methods Ninety patients aged between 22 and 80 (47.35 ± 17.69) were included in the study and divided into 3 groups. Group1(n:30)(Serum control group): Patients without venous insufficiency. Group 2(n:30)(Tissue control group(healthy vein group): Patients underwent coronary artery bypass surgery (the remaining portion of great saphenous vein used as coronary artery bypass graft used as normal tissue) . Group 3(n:30)(Varicose vein group): Patients underwent varicose vein surgery (varicose vein and serum of these patients were used for study). Total Oxidant Status (TOS), Total Antioxidant Status (TAS), Oxidative Stress Index (OSI) and Prolidase enzyme levels were detected in tissue and serum samples. Results No significant changes were detected between three groups' serum samples in oxidative stress parameters and in the prolidase enzyme activity. The tissue TOS and OSI were higher in varicose vein group according to normal vein group and this was found statistically significant. And TAC levels in varicose vein group were significantly lower than normal vein group. Prolidase enzyme activity in varicose vein group was found higher according to normal vein group. Conclusion Oxidative stress plays a role at the development of primary varicose veins at biochemical level. Prolidase enzyme related with oxidative stress may play an important role in the pathogenesis of primary varicose veins.

Diabetic Microvascular Disease: An Endocrine Society Scientific Statement

Both type 1 and type 2 diabetes adversely affect the microvasculature in multiple organs. Our understanding of the genesis of this injury and of potential interventions to prevent, limit, or reverse injury/dysfunction is continuously evolving. This statement reviews biochemical/cellular pathways involved in facilitating and abrogating microvascular injury. The statement summarizes the types of injury/dysfunction that occur in the three classical diabetes microvascular target tissues, the eye, the kidney, and the peripheral nervous system; the statement also reviews information on the effects of diabetes and insulin resistance on the microvasculature of skin, brain, adipose tissue, and cardiac and skeletal muscle. Despite extensive and intensive research, it is disappointing that microvascular complications of diabetes continue to compromise the quantity and quality of life for patients with diabetes. Hopefully, by understanding and building on current research findings, we will discover new approaches for prevention and treatment that will be effective for future generations.

Circulating Prolidase Activity in Patients with Myocardial Infarction

Background

Collagen is a major determinant of atherosclerotic plaque stability. Thus, identification of differences in enzymes that regulate collagen integrity could be useful for predicting susceptibility to atherothrombosis or for diagnosing plaque rupture. In this study, we sought to determine whether prolidase, the rate-limiting enzyme of collagen turnover, differs in human subjects with acute myocardial infarction (MI) versus those with stable coronary artery disease (CAD).

Methods

We measured serum prolidase activity in 15 patients with stable CAD and 49 patients with acute MI, of which a subset had clearly defined thrombotic MI (n = 22) or non-thrombotic MI (n = 12). Prolidase activity was compared across study time points (at cardiac catheterization, T0; 6 h after presentation, T6; and at a quiescent follow-up, Tf/u) in acute MI and stable CAD subjects. We performed subgroup analyses to evaluate prolidase activity in subjects presenting with acute thrombotic versus non-thrombotic MI.

Results

Although prolidase activity was lower at T0 and T6 versus the quiescent phase in acute MI and stable CAD subjects (p < 0.0001), it was not significantly different between acute MI and stable CAD subjects at any time point (T0, T6, and Tf/u) or between thrombotic and non-thrombotic MI groups. Preliminary data from stratified analyses of a small number of diabetic subjects (n = 8) suggested lower prolidase activity in diabetic acute MI subjects compared with non-diabetic acute MI subjects (p = 0.02).

Conclusion

Circulating prolidase is not significantly different between patients with acute MI and stable CAD or between patients with thrombotic and non-thrombotic MI. Further studies are required to determine if diabetes significantly affects prolidase activity and how this might relate to the risk of MI.

Serum Prolidase Activity as a Biomarker for Choroid Plexus Calcification

The choroid plexus (CP) performs multiple functions such as secretion and reabsorption. CP also acts as the blood-cerebrospinal fluid barrier. Prolidase plays an important role in collagen metabolism by degrading imidodipeptides, in which proline or hydroxyproline residue is located at the C-terminal end. Serum prolidase activity (SPA) may reflect the degree of fibrosis and inflammation. Choroid plexus calcification (CPC) is considered as the physiological calcification of the brain, and CPC is diagnosed by the presence of calcification in the anatomical region on computed tomography (CT). Here, CPC and non-calcified CP were defined by Hounsfield Units (HU) values of > 150 and < 50, respectively. We aimed to measure SPA in subjects with CPC and those with non-calcified CP. This study included 89 subjects who were admitted to the neurology clinic and underwent CT: 44 subjects with CPC and 45 subjects with non-calcified CP. The neurological examination of all subjects was normal; namely, the subjects with CPC were asymptomatic. The SPA level was significantly higher in the CPC group than that in the non-calcified CP group (p < 0.002), and there was a significant positive correlation between vitamin D and SPA levels in the CPC group. In contrast, the vitamin D and parathyroid hormone levels were higher in the CPC group, but the difference was not statically significant (p > 0.05). These findings indicate that SPA is a biomarker for CPC that may be predictive of future brain disease.

The relationships among the levels of oxidative and antioxidative parameters, FEV1 and prolidase activity in COPD

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a progressive condition characterized by poorly reversible airflow limitations associated with an abnormal inflammatory response of the lung.

METHODS

We investigated whether prolidase levels in serum, total antioxidant status, total oxidative status (TOS), and the oxidative stress index (OSI) were associated with the etiopathogenesis of COPD, and whether there is a relationship between prolidase activity and oxidative parameters and carotid artery intima-media thickness (CIMT) in patients with COPD. This study included 91 patients with COPD and 15 control cases. Routine haematological and biochemical parameters were determined in all patients. All subjects were fully informed about the study and provided consent.

RESULTS

The mean age of the patients with COPD was 61.3 ± 10.5 years and that of the control group was 56.2 ± 12.1 years. The control group had a significantly higher plasma prolidase level than that in the COPD group. TOS and OSI levels in the control group were significantly lower than those in the COPD group. However, no significant differences were found in TALs or CIMT levels between the COPD and control groups. A negative correlation was detected between prolidase activity and age; however, no significant difference in age was observed between the two groups.

CONCLUSION

These results indicate that prolidase activity decreases in patients with COPD.

Oxidative Stress and Antioxidant Status in Patients with Bell's Palsy

Background

Bell's palsy (BP) is the most common acute mononeuropathy of unilateral facial paralysis. Immune, infective and ischaemic mechanisms are potential contributors to the development of BP, but the precise cause remains unclear. Recently, oxidative stress has been proposed as a risk factor of various idiopathic diseases. The aim of this study was to investigate the possible role of oxidative stress in patients with BP.

Methods

Thirty-two patients with BP and 30 healthy controls were included in this study. Serum total oxidant status (TOS), total antioxidant status (TAS) and oxidative stress index (OSI) were measured by the Erel method.

Results

Serum TOS activities and OSI values were significantly higher in patients with BP compared with the control group (P <0.003 for all comparisons), whereas there was no significant difference between the groups in terms of TAS levels (P >0.05).

Conclusions

The data suggest that oxidative stress is increased in BP. These results of high oxidative stress in patients with BP may be helpful to clarify the etiopathogenesis of BP and contribute to improvement in the management or prevention of the disease.

Potential impact of sitagliptin on collagen-derived dipeptides in diabetic osteoporosis

It is known that diabetes coincides with an increased risk of osteoporosis. While a disturbed collagen metabolism is proposed as a possible cause, much remains unknown about the enzymes involved and changes in the collagen-derived dipeptides and amino acids. Therefore, we sought to study this intricate pathway and the effect of dipeptidyl peptidase 4 (DPP4) inhibitors. Control and streptozotocin-nicotinamide-induced diabetic rats were treated for 12 weeks with vehicle or sitagliptin, a DPP4 inhibitor (Con/VH, Con/SG, DM/VH and DM/SG). The activities of four key enzymes involved in collagen breakdown were determined in serum (DPP4, matrix metalloproteinase 2 and 9 and prolidase). Dipeptide (Ala-Pro, Gly-Pro, Pro-Pro and Pro-Hyp) and amino acid (Pro and Hyp) concentrations were measured by liquid chromatography coupled to mass spectrometry. We found three-fold higher MMP9 activities in DM/VH than in controls, while in DM/SG this rise was attenuated. MMP2 and prolidase did not differ in the investigated groups. Furthermore, we are the first to report on two-fold higher Ala-Pro and Pro-Pro levels in diabetes compared to controls. In contrast, Pro-Hyp concentrations were lower in diabetes (DM/VH and DM/SG). DPP4 inhibition does not seem to have a direct influence on the collagen metabolism in streptozotocin-nicotinamide-induced diabetic rats. Instead, it probably acts through its effect on osteoprotective substrates. In diabetes, increased MMP9 activities seem to favour the production of Ala-Pro and Pro-Pro containing collagen fragments. The high Pro-Hyp levels in untreated controls might have a bone-stimulating effect. Nevertheless, the biological significance of these dipeptides is not yet clear and should be further investigated.

Plasma Prolidase Activity and Oxidative Stress in Patients with Parkinson's Disease

Prolidase deficiency has been related to mental retardation and oxidative stress. The study aimed to observe plasma prolidase activity (PPA), total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) in patients with Parkinson's disease (PD). 240 subjects with PD and 150 healthy volunteers were considered as cases and controls, respectively. PPA, TOS, TAS, and OSI were measured spectrophotometrically. PPA and TAS in cases were more significantly decreased than controls (P < 0.01), while TOS and OSI were significantly increased (P < 0.001). In cases, nonsignificant, positive correlation was observed between PPA and TOS and OSI while significant, negative correlation was observed between PPA and TAS (P = 0.047). PPA in cases was nonsignificantly decreased with increased duration of PD (P = 0.747) while TAS was significantly decreased (P < 0.001) and TOS and OSI were significantly increased (P < 0.001). It was observed that higher age groups had decreased PPA, and TAS and increased TOS and OSI compared to lower age groups in cases. In summary, patients with PD have decreased PPA and increased oxidative stress compared to healthy volunteers. PPA was associated with oxidative stress markers in patients with PD. Decreased PPA and TAS and increased TOS and OSI were associated with progression of disease and higher age.

Oxidant/antioxidant status, paraoxonase activity, and lipid profile in plasma of ovariectomized rats under the influence of estrogen, estrogen combined with progesterone, and genistein

INTRODUCTION

The aim of this study was to investigate whether estradiol (E2), E2 combined with progesterone (Prog) (E2/Prog), and genistein (Gen) treatment had antioxidative and anti-hyperlipidemic effects in the plasma of ovariectomized (OVX) rats.

MATERIALS AND METHODS

Adult female Sprague-Dawley rats were divided into five groups. Rats in all groups, except for those in a sham group, underwent bilateral ovariectomy under general anesthesia. The groups were as follows: sham group; control OVX group; group treated with estrogen (0.014 mg/kg 17-β E2); group treated with a combination of E2 and Prog (0.014 mg/kg 17-β E2 plus 0.028 mg/kg drospirenone), and group treated with Gen (10 mg/kg/day). Plasma of rats of each treatment group was analyzed to determine the total antioxidant status, total oxidant status, paraoxonase activity, lipid profile, high-density lipoprotein (HDL-chol), low-density lipoprotein (LDL-chol), total cholesterol (Total-C), triacylglycerols, lipoprotein (a), and oxidative stress index.

RESULTS

Plasma Total-C levels and body weight increased in all the OVX groups compared with the sham group (P<0.005). The group treated with E2 had significantly elevated total oxidant status, oxidative stress index, LDL-chol, and Total-C compared with the control group (P<0.005). Gen treatment might lead to lower LDL-chol and Total-C levels compared with E2 treatment.

CONCLUSIONS

Gen treatment might be preferred to E2 treatment for treatment of menopausal symptoms in patients at risk for cardiovascular diseases. However, considering the small sample size of this study, larger studies are needed in this area.

Oxidative stress predicts progression of peripheral and cardiac autonomic nerve dysfunction over 6 years in diabetic patients

Oxidative stress is implicated in the pathogenesis of experimental diabetic neuropathy, but prospective studies in diabetic patients are lacking. We aimed to evaluate whether the plasma levels of various biomarkers of oxidative stress predict the progression of diabetic neuropathy and mortality over 6 years. We followed 89 diabetic patients aged 54 ± 14 years (59 % with polyneuropathy), 72 of whom underwent nerve function reassessment after 6.2 ± 0.8 years, whereas 17 died after 4.2 ± 1.0 years. Plasma markers of oxidative stress at baseline included superoxide anion, hypochlorous acid, peroxynitrite, 8-iso-prostaglandin F2α, vitamin E/lipid ratio, and vitamin C. Neuropathy was assessed by symptoms and deficits, motor and sensory nerve conduction velocity (MNCV, SNCV), vibration perception thresholds (VPT), thermal detection thresholds, and heart rate variability (HRV). Despite a reduction in HbA1c by 1.4 ± 1.6 % (p < 0.001), median SNCV, sural SNCV, peroneal MNCV, malleolar VPT, and warm TDT deteriorated after 6 years (all p < 0.05). In multivariate models, increased superoxide generation was associated with a decline in median SNCV (β = -0.997; p = 0.036) and deterioration in HRV at rest (OR 1.63 [95 % CI 1.09-2.44]; p = 0.017) over 6 years. Low vitamin E/lipid ratio tended to predict a decrease in peroneal MNCV (β = 0.781; p = 0.057) and an increase in malleolar VPT (β = -0.725; p = 0.077). Plasma superoxide generation was associated with an increased risk of mortality (HR 23.2 [95 % CI 1.05-513]; p = 0.047). In conclusion, increased plasma superoxide generation predicted the decline in sensory and cardiac autonomic nerve function and mortality over 6 years in diabetic patients, but larger studies are required for confirmation.

Serum prolidase activity and oxidative stress in diabetic nephropathy and end stage renal disease: a correlative study with glucose and creatinine

Association of oxidative stress and serum prolidase activity (SPA) has been reported in many chronic diseases. The study was aimed at evaluating the correlation of glucose and creatinine to SPA and oxidative stress in patients with diabetic nephropathy (DN) and end stage renal disease (ESRD) concerned with T2DM. 50 healthy volunteers, 50 patients with T2DM, 86 patients with DN, and 43 patients with ESRD were considered as control-1, control-2, case-1, and case-2, respectively. Blood glucose, creatinine, SPA, total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) were measured by colorimetric tests. SPA, TOS, and OSI were significantly increased in case-1 and case-2 than control-1 and control-2, while TAS was significantly decreased (P < 0.001). Blood glucose was linearly correlated to SPA, TOS, TAS, and OSI in control-2, case-1 and case-2 (P < 0.001). Serum creatinine was linearly correlated with SPA, TOS, TAS and OSI in control-2 and case-1 (P < 0.001). In case-2, serum creatinine was significantly correlated with SPA only (P < 0.001). Thus, the study concluded that SPA and oxidative stress significantly correlated with blood glucose and creatinine. SPA, TOS, TAS, and OSI can be used as biomarkers for diagnosis of kidney damage.

Serum prolidase enzyme activity and oxidative stress levels in patients with diabetic neuropathy

Previous studies have suggested that prolidase and nitric oxide (NO) regulate many processes, such as collagen synthesis and matrix remodeling. Oxidative stress plays an important role in the development of microvascular complications in diabetic patients. Data on serum prolidase activity in patients with diabetes mellitus or diabetic neuropathy (DN) are limited and conflicting. The aim of this study was to measure serum prolidase activity, NO, total antioxidant status (TAS), and malondialdehyde (MDA) levels in patients with DN. Forty-five patients with DN and 40 healthy controls were enrolled. Serum prolidase activity, TAS, MDA, and NO levels were determined. Serum MDA and NO levels were significantly higher in DN patients than controls (p = 0.002, p = 0.001, respectively), while prolidase activity and TAS levels were lower (p = 0.003, p = 0.001, respectively). Prolidase activity was negatively correlated with NO and MDA (r = -0.911, p < 0.001; r = -0.905, p < 0.001, respectively), while positively correlated with TAS (r = 0.981, p < 0.001) in DN patients. The current study is the first showing the decreased serum prolidase enzyme activity. Our results suggest that decreased collagen turnover may occur in DN patients, who have increased oxidative stress and increased NO levels. Decreased prolidase activity seems to be associated with increased NO levels and oxidative stress along with decreased antioxidant levels in DN. Therefore, decreased prolidase activity may play a role in pathogenesis of DN. Prospective clinical studies are necessary to confirm these findings.

Serum prolidase activity is associated with non-diabetic metabolic syndrome

OBJECTIVE

The aim of this study was to determine the role of serum prolidase activity and the possible association with oxidative stress parameters in non-diabetic metabolic syndrome.

METHODS

30 obese patients without metabolic syndrome (MetS), 34 non-diabetic obese patients with MetS, and 23 volunteer control subjects were enrolled in the study. Fasting plasma glucose (FPG), plasma glucose following 75 g glucose administration, high-density lipoprotein- cholesterol (HDL-C), high-density lipoprotein- cholesterol (LDL-C), total cholesterol, triglyceride (TG), total antioxidant status (TAS), total oxidative status (TOS), oxidative stress index (OSI), and prolidase activities of all subjects were analyzed.

RESULTS

Prolidase levels was significantly higher in MetS group compared to both obese and control groups (p < 0.001 and p < 0.05 respectively). Prolidase was also higher in the obese group than in the control group (p < 0.05). Prolidase was negatively correlated with TAS and HDL-C (r = -0,362, p < 0.001; r = -0.320, p < 0.01, respectively) and positively correlated with BMI, weight, waist-c, SBP, DBP, TG, TC, LDL-C.

CONCLUSION

Prolidase activity may have a role in the pathogenesis of metabolic syndrome.

Serum prolidase activity in diabetic foot ulcers

Impaired wound healing is an important problem in diabetes mellitus; however, its pathogenesis remains unclear. We aimed to evaluate serum prolidase activity (SPA), an important marker of collagen turnover, in subjects with and without diabetic foot ulcers as compared with healthy controls. Twenty-seven patients with diabetic foot ulcers (foot ulcer group), 27 patients without diabetic foot ulcers (diabetic control group) and 27 healthy controls were enrolled. The study groups had similar age, sex distribution and body mass index. Metabolic and inflammatory parameters as well as SPA were determined. The diabetic foot ulcer group had significantly higher SPA (both p < 0.001) when compared with the diabetic and the healthy control groups. SPA showed a positive correlation with high-sensitive C-reactive protein and a negative correlation with high-density lipoprotein cholesterol levels (r = 0.313, p = 0.021 and r = -0.233, p = 0.036, respectively). No correlation was detected between SPA and glycaemic parameters. SPA appears to be higher in patients with diabetic foot ulcers when compared with patients without diabetic foot ulcers and healthy controls. The underlying mechanisms of elevated SPA and its clinical significance in predicting the natural course of wound healing in diabetic foot ulcers needs to be further evaluation.

Prolidase, matrix metalloproteinases 1 and 13 activity, oxidative-antioxidative status as a marker of preterm premature rupture of membranes and chorioamnionitis in maternal vaginal washing fluids

OBJECTIVE

Etiology of premature preterm rupture of membranes (PPROM) is not yet completely known and chorioamnionitis is one of the most important complications of its. We aimed to evaluate whether prolidase, matrix metalloproteinases, oxidative-antioxidative status, and inflammation markers in vaginal washing fluid (VWF) were associated with etiology of PPROM and whether these markers could be used to predict chorioamnionitis in PPROM.

STUDY DESIGN

This prospective case control study enrolled fifty pregnant women with PPROM and 50 healthy pregnant women. The VWF samples were taken at the time of admission in the PPROM group and patients were followed for chorioamnionitis. Prolidase, matrix metalloproteinases, oxidative-antioxidative status, and inflammation markers in VWF were assayed.

RESULTS

VWF levels of prolidase, matrix metalloproteinases 1-13 (p< 0.001), oxidative stress parameters, total oxidative stress (TOS) (p < 0.001) and oxidative stress index (OSI) (p = 0.002), and hs-CRP (p = 0.045) were significantly higher in the PPROM group than in the controls. Antioxidative status parameters, levels of paroxanase (PON-1) (p < 0.001) and total antioxidant capacity (TAC) (p < 0.001), were significantly lower in the PPROM group than in the controls. Mean VWF levels of prolidase (p < 0.001), metalloproteinases (p<0.05), and oxidative-antioxidative status parameters (p<0.05) were significantly different in women with versus women without chorioamnionitis in the PPROM group. Prolidase, MMP-13, TOS, TAC, and PON-1 were found as important predictors for chorioamnionitis in the PPROM group by the multivariate logistic regression analysis. When the ROC curve analysis for prolidase, MMP-13, TOS, TAC, and PON-1 were performed, all of them were statistically significant for area under the curve (areas under the curve were 0.94, 0.90, 0.80, 0.25, and 0.19, respectively).

CONCLUSIONS

This study showed that collagen turnover mediators, especially prolidase, and increased oxidative stress are significantly associated with PPROM. Also, chorioamnionitis can be predicted with prolidase, MMP-13, TOS, TAC, and PON-1 in PPROM patients.

Maternal plasma prolidase, matrix metalloproteinases 1 and 13, and oxidative stress levels in pregnancies complicated by preterm premature rupture of the membranes and chorioamnionitis

OBJECTIVE

This study aimed to investigate the role of various biochemical markers in preterm premature rupture of membranes (PPROM) and in prediction of chorioamnionitis in patients with PPROM.

MATERIAL AND METHODS

This case-control study included a total of 100 pregnant women at 26-34 gestational weeks. Of these women, 50 were healthy and 50 had PPROM. The biochemical markers in the maternal plasma including prolidase, matrix metalloproteinase (MMP) 1 and 13, total oxidative status (TOS), total antioxidant capacity (TAC), glutathione peroxidase (GPx), catalase (CAT), paraoxonase-1 (PON-1), tumor necrosis factor alpha (TNF-α), and high sensitive C-reactive protein (hs-CRP) were assayed. These levels were compared between the PPROM and control groups and between women with or without chorioamnionitis in the PPROM group.

RESULTS

Compared to the control group, the levels of prolidase, MMP-13, and TOS were significantly higher (p values <0.001, 0.020, and 0.035, respectively) and those of TAC and PON-1 were significantly lower in the maternal plasma of the PPROM group (p values=0.012 and <0.001, respectively). The plasma prolidase and TOS levels were significantly higher (p values=0.033 and 0.005, respectively) and the plasma TAC and PON-1 levels were significantly lower in women with chorioamnionitis as compared with the corresponding values in women without chorioamnionitis in the PPROM group (p values =0.041 and 0.048, respectively). The multivariate logistic regression analysis observed that prolidase, TAC, and PON-1 were important markers for the presence of PPROM and prolidase and TOS were important markers for predicting chorioamnionitis.

CONCLUSION

This study suggested that maternal plasma prolidase, TAC, and PON-1 may be useful for the diagnosis of PPROM, and prolidase and TOS may be used to predict chorioamnionitis in patients with PPROM.