Disorders of Lipid Metabolism in Chronic Kidney Disease

Cardiovascular disease (CVD) is the leading cause of death in chronic kidney disease (CKD). One of the most important pathophysiological mechanisms for CVD in patients with CKD is the widespread and possibly accelerated formation of atherosclerotic plaques due to hyperlipidemia, uremic toxins, inflammation, oxidative stress, and endothelial dysfunction. Recent studies showed that the level of oxidized low-density lipoprotein cholesterol increases, and that high-­density lipoprotein cholesterol dysfunction occurs as kidney function declines and inflammation becomes more prevalent. In this review, we aimed to discuss the effect of kidney dysfunction, oxidative stress, and inflammation on lipid ­profile.

Capillary rarefaction from the kidney point of view

Capillary rarefaction is broadly defined as a reduction in vascular density. Capillary rarefaction in the kidneys is thought to promote hypoxia, impair hemodynamic responses and predispose to chronic kidney disease (CKD) progression and hypertension development. Various mechanisms have been suggested to play a role in the development of capillary rarefaction, including inflammation, an altered endothelial-tubular epithelial cell crosstalk, a relative deficiency in angiogenic growth factors, loss of pericytes, increased activity of Transforming growth factor -β1 and thrombospondin-1, vitamin D deficiency, a link to lymphatic neoangiogenesis and INK4a/ARF (Cylin-dependent kinase inhibitor 2a; CDKN2A). In this review, we summarize the tools available to monitor capillary rarefaction noninvasively in the clinic, the contribution of capillary rarefaction to CKD and hypertension, the known mechanisms of capillary rarefaction, and potential future strategies to attenuate capillary rarefaction and reduce its negative impact. Therapeutic strategies to be explored in more detail include optimization of antihypertensive therapy, vitamin D receptor activators, sirtuin 1 activators, Hypoxia inducible factor prolyl hydroxylase inhibitors and stem cell therapy.

Acute effects of salt on blood pressure are mediated by serum osmolality

It is classically thought that it is the amount of salt that is critical for driving acute blood pressure responses. However, recent studies suggest that blood pressure responses, at least acutely, may relate to changes in serum osmolality. Here, we test the hypothesis that acute blood pressure responses to salt can be altered by concomitant water loading. Ten healthy patients free of any disease and medication underwent 4 interventions each a week apart in which they took 300 mL of lentil soup with no salt (visit 1), lentil soup with 3 g salt (visit 2), or lentil soup with 3 g salt and 500 mL water (visit 3) or 750 mL water (visit 4). At each visit, hourly blood measurements and blood pressure measurements (baseline, 1st, 2nd, 3rd, and 4th hour) were performed and plasma osmolarity, sodium and copeptin levels were measured. Patients receiving the 3 g salt showed a 6 mOsm/L change in osmolality with a 2.5 mmol/L change in plasma sodium and 10 mm Hg rise in systolic blood pressure at 2 hours. When the same patients drank salty soup with water, the changes in plasma osmolarity, plasma sodium, and blood pressure were prevented. The ability to raise blood pressure acutely with salt appears dependent on changes in plasma osmolality rather than the amount of salt. Our findings suggest that concurrent intake of water must be considered when evaluating the role of salt in blood pressure.

The Speed of Ingestion of a Sugary Beverage Has an Effect on the Acute Metabolic Response to Fructose

BACKGROUND

The consumption of sweetened beverages is associated with increased risk of metabolic syndrome, cardiovascular disease, and type 2 diabetes mellitus.

OBJECTIVE

We hypothesized that the metabolic effects of fructose in sugary beverages might be modulated by the speed of ingestion in addition to the overall amount.

DESIGN

Thirty healthy subjects free of any disease and medication were recruited into two groups. After overnight fasting, subjects in group 1 drank 500 mL of apple juice over an hour by drinking 125 mL every 15 min, while subjects in group 2 drank 500 mL of apple juice over 5 min. Blood samples were collected at time zero and 15, 30, 60, and 120 min after ingestion to be analyzed for serum glucose, insulin, homeostatic model assessment (HOMA-IR) score, fibroblast growth factor 21, copeptin, osmolarity, sodium, blood urea nitrogen (BUN), lactate, uric acid, and phosphate levels.

RESULTS

Serum glucose, insulin, HOMA-IR, fibroblast growth factor 21, copeptin, osmolarity, sodium, BUN, and lactate levels increased following apple juice ingestion. The increases were greater in the fast-drinking group, which were more significant after 15 min and 30 min compared to baseline. The changes in uric acid were not statistically different between the groups. Phosphate levels significantly increased only in the fast-drinking group.

CONCLUSION

Fast ingestion of 100% apple juice causes a significantly greater metabolic response, which may be associated with negative long-term outcomes. Our findings suggest that the rate of ingestion must be considered when evaluating the metabolic impacts of sweetened beverage consumption.

Fluvastatin Decreases Oxidative Stress in Kidney Transplant Patients

OBJECTIVE

Oxidative stress has been suggested to have a pivotal role in the development of cardiovascular disease in kidney transplant patients (KTPs). The effects of fluvastatin on oxidative status in KTPs have not been well evaluated. The aim of the present study was to evaluate the effects of fluvastatin on oxidative status by investigating erythrocyte superoxide dismutase (SOD), erythrocyte glutathione peroxidase (GPx), serum paraoxonase (PON1), and serum arylesterase (ARE), along with lipid peroxidation products, serum malonldialdehyde, and apolipoprotein B malondialdehyde (ApoB MDA).

METHODS

Eighteen KTPs were included in the present study. Blood samples were obtained after 1 night's fast. Erythrocyte SOD, erythrocyte GPx, serum PON1, serum ARE, serum MDA, and ApoB MDA were measured using methods described previously. Paired-sample t test was used for comparing the changes from week 0 to week 4 of parameters that might be associated with fluvastatin treatment.

RESULTS

The present study has shown that erythrocyte SOD and GPx, and serum PON1 and ARE activities increased at the fourth week of the statin treatment. Furthermore an increase in the antioxidant enzymes following fluvastatin may be a clue for the antioxidant effects of this drug. Four weeks of fluvastatin long-acting tablets 80 mg/day led to a decrease in plasma Apo-MDA and MDA levels.

CONCLUSION

The findings of the present study demonstrate that fluvastatin 80 mg long-acting tablets may be used safely for 4 weeks and decrease atherogenic lipoproteins in KTPs. Furthermore, after 4 weeks of fluvastatin treatment, the levels of antioxidant parameters increased and oxidative parameters decreased. Further placebo-controlled treatment studies would be helpful to evaluate the effects of fluvastatin on oxidant and antioxidant parameters including PON1 in patients with KT.

Elevation in serum uric acid levels predicts favourable response to erlotinib treatment in patients with metastatic non-small-cell lung cancer

WHAT IS KNOWN AND OBJECTIVE

Erlotinib is a small molecule tyrosine kinase inhibitor which blocks the activation of epidermal growth factor receptor (EGFR), a transmembrane receptor that is upregulated in many cancer types. Inhibition of angiogenesis with consequent impairments in intratumoral microcirculation is one of the mechanisms through which EGFR inhibition halts the progression of cancer. A consequence of impaired microcirculation is intratumoral hypoxia, which results in increases in serum uric acid levels. The goal of this study was to investigate the relationship between serum uric acid levels and response to erlotinib in metastatic non-small-cell lung cancer (NSCLC).

METHODS

A total of 56 patients with metastatic non-small-cell lung cancer who received erlotinib for a duration of at least 3 months were included in this retrospective cohort study. Demographic characteristics, progression status, baseline serum uric levels and 3-month serum uric acid levels were recorded and analysed.

RESULTS AND DISCUSSION

Of the study population, 21 (37.5%) were female and 35 (62.5%) were male patients. No significant difference in above demographic characteristics was observed among exitus, survivor with progression and survivor without progression groups. Patients who responded favourably to erlotinib with no progression of their disease had significantly increased uric acid levels at 3-month follow-up (P = .01). Such a correlation was not observed if the patient was exitus (P = .47) or had progressed on erlotinib therapy (P = .19).

WHAT IS NEW AND CONCLUSION

In conclusion, this study is the first to demonstrate significant increases in serum uric acid levels in patients with metastatic NSCLC who responded favourably to erlotinib and had no progression under erlotinib therapy. Further studies are required to confirm and characterize serum uric acid as a novel biomarker in predicting the outcome in those with metastatic NSCLC.

Effects of adenosine triphosphate, Lacidipine, and Benidipine on 5-fluorouracil-induced kidney damage in rats

OBJECTIVE

In the present study, the protective effects of adenosine triphosphate (ATP), Benidipine, and Lacidipine on potential kidney damage induced by 5-fluorouracil (5-FU) were investigated in rats.

MATERIALS AND METHODS

Totally 48 rats were divided into 8 groups: healthy (HG), 5-FU (FUG), ATP+5-FU (AFU), Benidipine+5-FU (BFU), Lacidipine+5-FU (LFU), ATP+Benidipine+5-FU (ABFU), ATP+Lacidipine+5-FU (ALFU) and Benidipine+Lacidipine+5-FU (BLFU). In a 10-day period, ATP (4 mg/kg) was administered intraperitoneally, and Benidipine (4 mg/kg) and Lacidipine (4 mg/kg) were administered orally once a day. On days 1, 3, and 5, 5-FU (100 mg/kg) was administered intraperitoneally one hour after the drug was administered. Afterward, the rats were euthanized, and kidney tissues were removed. An analysis of malondialdehyde, total glutathione, superoxide dismutase, and catalase was performed on tissues, as well as a histopathological examination. A creatinine and blood urea nitrogen analysis were performed on blood samples.

RESULTS

It was revealed that 5-FU decreased the amount of total glutathione, superoxide dismutase, and catalase activities in rat kidney tissues and increased malondialdehyde. Further, increased serum creatinine and blood urea nitrogen levels, as well as histopathological examination of kidney tissues, were found in the 5-FU group. ATP+Benidipine and ATP treatments were the most effective in preventing both biochemical and histopathological changes induced by 5-FU. A treatment with Benidipine improved biochemical and histopathologic data, but not to the same extent as a treatment with ATP+Benidipine and ATP. As a result of Lacidipine+ATP combination, 5-FU-induced biochemical changes in kidney tissue were partially inhibited, but the degree of histopathologic damage remained unchanged. Neither Benidipine+Lacidipine nor Lacidipine showed a protective effect on both biochemical changes and histopathologic damage.

CONCLUSIONS

It may be possible to prevent nephrotoxicity by adding ATP + Benidipine or ATP to 5-FU treatment.

Hyperthermic intraperitonal chemotherapy is an independent risk factor for development of acute kidney injury

PURPOSE

Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (HIPEC) or hyperthermic intrapleural chemotherapy (HIC) has been established as the new treatment modality for selected patients with peritoneal and pleural malignancies. The purpose of the study was to compare the development of acute kidney injury (AKI) in patients who received intravenous cisplatin alone, HIPEC and underwent surgery.

METHODS

This retrospective study included 104 patients who underwent different therapeutic procedures including systemic cisplatin, surgery and HIPEC or HIC using cisplatin for the treatment of peritoneal carcinomatosis from a variety of primary tumors at Koc University Hospital and American Hospital between January 2015 to December 2017.

RESULTS

AKI developed in 18 (17.3%) patients. Baseline creatinine was significantly increased in 3 groups after therapies. The development of AKI was highest in patients treated with HIPEC compared to patients treated with intravenous cisplatin and patients who underwent surgery. AKI developed 31.2% in the HIPEC group (10 of 32 patients), 11.7% in the surgery group (4 of 34 patients) and 10.5% in intravenous cisplatin group (4 of 38 patients), respectively (p 0.04).

CONCLUSION

HIPEC may not be so safe with regard to kidney function. Every attempt should be taken to decrease kidney damage during this procedure.

Can Incidental Vascular Calcifications at Mammography be Used as a Screening Biomarker for Heart and Kidney Disease?

Mammography is a screening test with extensive international application and financial infrastructure promoting accessibility and affordability. Designed specifically to detect microcalcifications, mammography is powered to detect calcifications in vessel walls. Breast arterial calcifications (BAC) are one of the most common incidental findings documented by mammography. This review considers the literature regarding BAC in relation to cardiovascular disease (CVD) and its risk factors. The aim is to assess the possibility of using BAC as an early surrogate imaging biomarker of CVD.