Renin-angiotensin system activation: may it increase frequency of obstructive sleep apnea in patients with autosomal dominant polycystic kidney disease?

PURPOSE

Renin-angiotensin system (RAS) hyperactivity is a common entity in both autosomal dominant polycystic kidney disease (ADPKD) and obstructive sleep apnea (OSA). We aimed to investigate the frequency of OSA in adults with ADPKD either with stages 3-4 or stages 1-2 chronic kidney disease (CKD) and evaluate the effect of RAS blockade on OSA in these patients.

METHODS

This is a comparative, prospective, two-center clinical study. Eligible patients with ADPKD were enrolled in a polysomnography (PSG) study. Presence of OSA in patients with ADPKD was compared with individuals who underwent polisomnography study due to OSA symptoms. A subgroup analysis was performed in terms of the presence of OSA in ADPKD with eGFR values lower or higher than 60 ml/min/1.73 m2 (stages 3-4 and stages 1-2 CKD, respectively).

RESULTS

Frequency of OSA (65%) was higher than in the general population and similar between the two groups (p = 0.367). Patients with ADPKD and eGFR ≥ 60 ml/min/1.73 m2 presented a similar frequency of OSA to the control group (p = 0.759). However, OSA was significantly more frequent in ADPKD with eGFR < 60 ml/min/1.73 m2 (p = 0.018). Subgroup analysis revealed that presence of OSA also was significantly higher in ADPKD with lower eGFR levels (eGFR < 60 ml/min/1.73 m2 and eGFR > 60 ml/min/1.73 m2) 14/17 (82%) and 12/23 (52%), respectively (p: 0.048).

CONCLUSION

As kidney disease progresses, uremia and related factors of renal failure rather than RAS activation seem to play a more important role for the development of OSA in patients with ADPKD.

Prevalence of metabolic dysfunction-associated fatty liver disease in kidney transplant recipients: A cross-sectional study using FibroScan

BACKGROUND AND AIM

Metabolic dysfunction-associated fatty liver disease (MAFLD) is expected to be prevalent among kidney transplant recipients (KTRs). In this study, we evaluated the prevalence of MAFLD among KTRs, data that have not been investigated by any clinical study to date.

MATERIALS AND METHODS

We included a total of 52 KTRs and 53 age-, sex-, and BMI-matched individuals as the control group through prospective consecutive recruitment. We detected the presence of hepatic steatosis and liver fibrosis using the controlled attenuation parameter (CAP) and liver stiffness measurement (LSM) defined by FibroScan.

RESULTS

Among the KTRs, 18 (34.6%) had metabolic syndrome. The prevalence of MAFLD among the KTRs and controls was 42.3% and 51.9%, respectively (p=0.375). The CAP and LSM values did not differ significantly between the KTRs and controls (p=0.222 and p=0.119). Among the KTRs, patients with MAFLD had significantly higher age, BMI, waist circumference, LDL, and total cholesterol levels (p<0.001, p=0.011, p=0.033, p=0.022, and p=0.029, respectively). In multivariable analysis, age was the only independent factor for MAFLD among the KTRs (OR: 1.120, 95% confidence interval (CI): 1.039-1.208).

CONCLUSION

MAFLD among KTRs did not show a significantly higher prevalence compared to the normal population. Further clinical studies with larger populations are needed.

A prospective study of living kidney donors: 6 years follow-up from a cardiovascular disease risk perspective

OBJECTIVE:

The purpose of this prospective study was to evaluate the clinical, laboratory, and donation-specific outcomes of living kidney donors 6 years after donation.

METHODS:

We included a total of 93 kidney donors and 54 age- and sex-matched individuals as control group through a type 2 cohort consecutive recruitment. We detected kidney function abnormalities and the presence of hypertension, diabetes, and cardiovascular events during the 6 years follow-up period.

RESULTS:

The mean serum creatinine levels were higher (p<0.001), and the estimated glomerular filtration rate levels were lower (p<0.001) in living kidney donors 6 years after donation when compared with controls. The protein/creatinine ratio of the study population was also higher (p=0.014). There was no difference in outcomes between the groups for end-stage kidney disease and cardiovascular mortality. A higher rate of new-onset hypertension (6.4 vs. 32.9%), diabetes mellitus (0.0 vs. 4.3%), chronic kidney disease (0.0 vs. 2.1%), and cardiovascular disease (0.0 vs. 2.1%) was demonstrated among donors 6 years after donation (p<0.001, respectively).

CONCLUSION:

Our data have demonstrated that the reduction in Glomerular filtration rate induced by kidney donation might cause an increase in adverse renal and cardiovascular events.

Clinical predictors of incipient vertebral fractures and bone mineral density in kidney transplant patients

PURPOSE

Kidney transplant recipients are prone to metabolic bone diseases and consequent fractures. This study aimed to evaluate the incidence of incipient vertebral fractures, osteopenia, osteoporosis, and the clinical factors associated with incipient vertebral fractures in a group of kidney transplant patients.

METHODS

Two hundred sixty-four patients (F/M 124/140, 45.3 ± 13 years) who had undergone kidney transplantation in tertiary care centers were included. Vertebral fractures were assessed semiquantitatively using conventional thoracolumbar lateral radiography in 202 of the patients.

RESULTS

Vertebral fractures were observed in 56.4% (n = 114) of the study group. The frequency of osteoporosis was 20.0% (53 of 264 patients), and osteopenia was 35.6% (94 of 264 patients). Bone mineral density (BMD) levels were in the normal range in 40.3% (n = 46) of the subjects with vertebral fractures. It was in the osteoporotic range in 20.1% (n = 23) and the osteopenic range in 40.3% (n = 46). Vertebral fractures were associated with age, duration of hemodialysis, BMI, and femoral neck Z score (R² 37.8%, p = 0.027).

CONCLUSION

As incipient vertebral fractures can be observed in patients with normal BMD levels in kidney transplant recipients, conventional X-ray screening for vertebral fractures may be beneficial for a proper therapy decision of metabolic bone disease in kidney transplant recipients.

COVID-19 in kidney transplant recipients: A multicenter experience in Istanbul

INTRODUCTION

Management of COVID-19 in kidney transplant recipients should include treatment of the infection, regulation of immunosuppression, and supportive therapy. However, there is no consensus on this issue yet. This study aimed to our experiences with kidney transplant recipients diagnosed with COVID-19.

MATERIAL AND METHODS

Kidney transplant recipients diagnosed with COVID-19 from five major transplant centers in Istanbul, Turkey, were included in this retrospective cohort study. Patients were classified as having moderate or severe pneumonia for the analysis. The primary endpoint was all-cause mortality. The secondary endpoints were acute kidney injury, the average length of hospital stay, admission to intensive care, and mechanical ventilation.

RESULTS

Forty patients were reviewed retrospectively over a follow-up period of 32 days after being diagnosed with COVID-19. Cough, fever, and dyspnea were the most frequent symptoms in all patients. The frequency of previous induction and rejection therapy was significantly higher in the group with severe pneumonia compared to the moderate pneumonia group. None of the patients using cyclosporine A developed severe pneumonia. Five patients died during follow-up in the intensive care unit. None of the patients developed graft loss during follow-up.

DISCUSSION

COVID-19 has been seen to more commonly cause moderate or severe pneumonia in kidney transplant recipients. Immunosuppression should be carefully reduced in these patients. Induction therapy with lymphocyte-depleting agents should be carefully avoided in kidney transplant recipients during the pandemic period.

P0431TRENDS OF PRIMARY GLOMERULAR DISEASE IN TURKEY FROM 2009 TO 2017: A REGIONAL REGISTRY REPORT FROM TSN-GOLD WORKING GROUP

Background and Aims

Several glomerular disease registries in Europe, and they shared their data; however, there was a lack of current data on trends of primary glomerulopathy in Turkey. Glomerular disease patterns can change geographical areas and populations decade by decade. Our aim is to present Turkey's primary glomerular disease pattern from 2009 to 2017.

Method

3878 native kidney biopsy records were assessed in the Turkish Society of Nephrology Glomerulopathy (TSN-GOLD) Working Group Registry. Secondary disease (lupus, etc.) and transplant biopsies do not enroll in the registry. These records divided into four periods, before 2009, 2009 to 2013, 2013 to 2017, and 2017 to current.

Results

A total of 3858 patients (M = 2173, K = 1685) were examined. There was no difference in the distribution of number of patients according to periods (Q1 = 968, Q2 = 960, Q3 = 968, Q4 = 962). Nephrotic syndrome was the most common biopsy indication in all quarters (58.6%, 53%, 44.1%, 51.6%, respectively). Glomerulopathy types; Membranous GN (29.9%, n = 290) was the first in Q1 and IgA nephropathy (17.7%, n = 172) was the second. IgA nephropathy (28.5%, n = 274) was the most common glomerulopathy in Q2, while Membranous GN (25.5%, n = 245) was the second most common. IgA nephropathy (29.9%, n = 285) was the most common glomerulopathy in Q3, followed by FSGS (22.9%, n = 222) and Membranous GN. In Q4, FSGS (26.8, n = 258) was the most common glomerulopathy, followed by IgA nephropathy (26.7%, n = 257) and Membranous GN (24.5%, n = 236) (Figure 1).

Conclusion

While biopsy indications did not change over the years, the incidence of FSGS and IgA nephropathy gradually increased.

Fabry Disease Prevalence in Renal Replacement Therapy in Turkey

BACKGROUND

Fabry disease (FD) is an X-linked lysosomal storage disorder resulting from lack of alpha-galactosidase A (AGALA) activity in lysosomes.

OBJECTIVE

In this multicenter study, we aimed to evaluate the prevalence of FD in renal transplant (Tx) recipients in Turkey. We also screened dialysis patients as a control group.

METHODS

All Tx and dialysis patients were screened regardless of the presence of a primary disease. We measured the AGALA activity in all male patients as initial analysis. Mutation analysis was performed in male patients with decreased AGALA activity and in female patients as the initial diagnostic assay.

RESULTS

We screened 5,657 patients. A total of 17 mutations were identified. No significant difference was observed between the groups regarding the prevalence of patients with mutation. We found FD even in patients with presumed primary kidney diseases. Seventy-one relatives were analyzed and mutation was detected in 43 of them. We detected a patient with a new, unknown mutation (p.Cys223) in the GLA gene.

CONCLUSIONS

There are important implications of the screening. First, detection of the undiagnosed patients leads to starting appropriate therapies for these patients. Second, the transmission of the disease to future generations may be prevented by prenatal screening after appropriate genetic counseling. In conclusion, we suggest screening of kidney Tx candidates for FD, regardless of etiologies of chronic kidney disease.

A randomized study to assess the efficacy of herbal product to prevent cisplatin-induced nephrotoxicity in a rat model

OBJECTIVES

This study aimed to investigate the protective effect and antioxidant activity of an herbal product that made from multiple plants in a rat model of kidney dysfunction induced by intraperitoneal cisplatin.

MATERIALS AND METHODS

Twenty-four rats were divided into four different groups namely: Group 1 - control healthy animals without any specific medication, Group 2 - Herbal product only 5 mg/kg, Group 3 - cisplatin only and Group 4 - Herbal product 5 mg/kg + cisplatin.

RESULTS

Evaluation of our findings demonstrated a significant (p = 0.017) reduction in Catalase activities and a significant increase (p = 0.001) in renal tissue Malondialdehyde levels in cisplatin- treated rats when compared with the control group. Also, Glutathion and Glutathione peroxidase content revealed significant (p = 0.031) reduction in renal tissues of cisplatintreated rats compared with the control group. Pre-treatment of rats with the herbal product ameliorated these cisplatininduced changes of the antioxidant enzymes. No statistically significant changes were demonstrated in Superoxide dismutase activities in the tissue specimens of any group.

CONCLUSIONS

This potent antioxidant herbal medicine was found to have potential antioxidant activity, which may in turn to be effective in the protection of kidney tissue resulting from cisplatin application. Therefore, much attention should be given to the possible role of natural dietary antioxidants for protecting the kidney.

Association between serum pregnancy-associated plasma protein-A and bicarbonate in hemodialysis patients

BACKGROUND

Acidosis is associated with protein-energy malnutrition, inflammation, and bone disease, and low bicarbonate levels have been implicated in higher mortality rates in chronic kidney disease. Recently, the concentration of serum pregnancy-associated plasma protein-A (PAPP-A) has become accepted as a prognostic marker in hemodialysis patients. This study determined the relationship between PAPP-A and bicarbonate levels in these patients.

METHODS

The study enrolled 65 hemodialysis patients (41 males, 24 females) and 26 control subjects (11 males, 15 females). Serum PAPP-A, intact parathormone (iPTH), calcium, phosphorus (P), and bicarbonate levels were measured. Correlations between PAPP-A and bicarbonate, iPTH, calcium, and phosphorus were evaluated.

RESULTS

Median PAPP-A levels were significantly higher in hemodialysis patients [15.1 (<0.03-158.8) ng/ml] than in control subjects [6.6 (<0.03-16.4) ng/ml] (P < 0.05). There were statistically significant correlations between serum PAPP-A and bicarbonate, iPTH, and P in hemodialysis patients but not in control subjects.

CONCLUSION

Elevation of serum PAPP-A has been found in hemodialysis patients and its significant correlation with bicarbonate suggests that it may be a prognostic factor.

Look-up table (LUT) method for inverse halftoning

In this paper we propose look-up table (LUT) based methods for inverse halftoning of images. The LUT for inverse halftoning is obtained from the histogram gathered from a few sample halftone images and corresponding original images. The method is extremely fast (no filtering is required) and the PSNR and visual image quality achieved is comparable to the best methods known for inverse halftoning. The LUT inverse halftoning method does not depend on the specific properties of the halftoning method, and can be applied to any halftoning method. Then, an algorithm for template selection for LUT inverse halftoning is introduced. We demonstrate the performance of the LUT inverse halftoning algorithm on error diffused images and ordered dithered images. We also extend LUT inverse halftoning to color halftones.

Optimized halftoning using dot diffusion and methods for inverse halftoning

Unlike the error diffusion method, the dot diffusion method for digital halftoning has the advantage of pixel-level parallelism. However, the image quality offered by error diffusion is still regarded as superior to most of the other known methods. We show how the dot diffusion method can be improved by optimization of the so-called class matrix. By taking the human visual characteristics into account we show that such optimization consistently results in images comparable to error diffusion, without sacrificing the pixel-level parallelism. Adaptive dot diffusion is also introduced and then a mathematical description of dot diffusion is derived. Furthermore, inverse halftoning of dot diffused images is discussed and two methods are proposed. The first one uses projection onto convex sets (POCS) and the second one uses wavelets. Of these methods, the wavelet method does not make use of the knowledge of the class matrix. Embedded multiresolution dot diffusion is also discussed, which is useful for rendering at different resolutions and transmitting images progressively.