Structural renal changes in obesity and diabetes

[Renal involvement in systemic diseases]

BACKGROUND

Diseases of the nonneoplastic renal parenchyma occur in the context of a number of disorders that affect the organism systemically and can thus represent a differential diagnosis for autoimmunological kidney diseases.

PURPOSE

Two common autoimmunologic diseases of the kidney, namely antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and systemic lupus erythematosus (SLE), are presented and put into context of the broader field of renal diseases. Novel diagnostic and therapeutic approaches are discussed.

MATERIALS AND METHODS

A review of the recent literature and an overview of the disease presentation are provided.

Low estimated glomerular filtration rate and high body mass index are risk factors for acute kidney injury in systemic lupus erythematosus patients after cardiac surgery

Objective

The occurrence of acute kidney injury (AKI) is common following cardiac surgery, especially among patients characterized with systemic lupus erythematosus (SLE), but studies on this clinical scenario have been limited by the rarity of SLE. We aimed to explore the risk predictors and outcomes with regards to postoperative AKI among cardiac-surgical patients concomitant with SLE.

Methods

This was a single-center retrospective study performed in a tertiary hospital. Adult patients diagnosed with SLE who underwent cardiac surgery within the last 22 years were enrolled. Essential variables, including patient-, surgery- and anesthesia-related information, were collected from the medical record system. The definition of AKI was derived from the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Risk predictors suspected to be linked with post-surgical AKI were calculated using the univariable and multivariable analyses.

Results

Of all 59 SLE patients undergoing cardiac surgery, 57 were ultimately enrolled into the analysis. AKI occurred in 29 patients (50.9%), who had significantly longer extubation time (median difference 1.0 day, P < 0.001), ICU length of stay (median difference 2.0 days, P = 0.001), postoperative length of stay (median difference 5.0 days, P = 0.026), and more postoperative major complications (odds ratio 10.29, P = 0.025) than the others. Preoperative estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2 (odds ratio 5.31, P = 0.021) and body mass index (BMI) ≥ 24 kg/m2 (odds ratio 4.32, P = 0.043) were the only two factors in the multivariable analysis that were significantly correlated with the development of postoperative AKI in patients with SLE after cardiac surgery.

Conclusion

AKI in SLE patients after cardiac surgery is common and requires scrutiny, especially in overweight patients with moderate to severe preoperative renal dysfunction.

Postoperative acute kidney injury after on-pump cardiac surgery in patients with connective tissue disease

Objective

Patients with connective tissue disease have a poor prognosis after receiving cardiac surgery. This study described the clinical scenarios and investigated factors correlated with acute kidney injury (AKI) after on-pump cardiac surgery in patients with systemic lupus erythematosus (SLE) or vasculitis.

Methods

Patients with SLE or vasculitis who underwent on-pump cardiac surgery from March 2002 to March 2022 were enrolled, while patients with preoperative renal dysfunction were excluded. AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Uni- and multivariable analyses were performed to identify potential factors associated with postoperative AKI.

Results

Among 123 patients enrolled, 39 (31.7%) developed AKI within seven days after receiving on-pump cardiac surgery. Four patients died in the hospital, resulting in an overall in-hospital mortality of 3.3%, and all deaths occurred in the AKI group. Patients in the AKI group also had longer ICU stays (median difference 3.0 day, 95% CI: 1.0-4.0, P < 0.001) and extubation time (median difference 1.0 days, 95% CI: 0-2.0, P < 0.001) than those in the non-AKI group. Multivariable logistic regression revealed that BMI over 24 kg/m2 (OR: 3.00, 95% CI: 1.24-7.28) and comorbid SLE (OR: 4.73, 95% CI: 1.73-12.93) were independently correlated with postoperative AKI.

Conclusion

Factors potentially correlated with AKI following on-pump cardiac surgery in patients with connective tissue disease were explored. Clinicians should pay more attention to preoperative evaluation and intraoperative management in patients with risk factors.

A Machine Learning-Based Prediction of Diabetes Insipidus in Patients Undergoing Endoscopic Transsphenoidal Surgery for Pituitary Adenoma

BACKGROUND

Diabetes insipidus (DI) is a common complication after endoscopic transsphenoidal surgery (TSS) for pituitary adenoma (PA), which affects the quality of life in patients. Therefore, there is a need to develop prediction models of postoperative DI specifically for patients who undergo endoscopic TSS. This study establishes and validates prediction models of DI after endoscopic TSS for patients with PA using machine learning algorithms.

METHODS

We retrospectively collected information about patients with PA who underwent endoscopic TSS in otorhinolaryngology and neurosurgery departments between January 2018 and December 2020. The patients were randomly split into a training set (70%) and a test set (30%). The 4 machine learning algorithms (logistic regression, random forest, support vector machine, and decision tree) were used to establish the prediction models. Area under the receiver operating characteristic curves were calculated to compare the performance of the models.

RESULTS

A total of 232 patients were included, and 78 patients (33.6%) developed transient DI after surgery. Data were randomly divided into a training set (n = 162) and a test set (n = 70) for development and validation of the model, respectively. The area under the receiver operating characteristic curve was highest in the random forest model (0.815) and lowest in the logistic regression model (0.601). Invasion of pituitary stalk was the most important feature for model performance, closely followed by macroadenomas, size classification of PA, tumor texture, and Hardy-Wilson suprasellar grade.

CONCLUSIONS

Machine learning algorithms identify preoperative features of importance and reliably predict DI after endoscopic TSS for patients with PA. Such a prediction model may enable clinicians to develop individualized treatment strategy and follow-up management.

Delayed postoperative hyponatremia in patients with acromegaly: incidence and predictive factors

PURPOSE

Delayed postoperative hyponatremia (DPH) is a unique complication of transsphenoidal surgery (TSS) in pituitary tumors. Growth hormone (GH) enhances renal sodium reabsorption; however, the association between postoperative GH reduction and DPH in acromegaly is unclear. This study was performed to clarify the incidence of and the predictive factors for DPH in patients with acromegaly who underwent TSS.

METHODS

Ninety-four patients with active acromegaly were examined retrospectively. During the postoperative course, patients with serum sodium levels ≤ 134 mEq/L were classified into the DPH group. We compared basic clinical characteristics, tumor characteristics, and preoperative and postoperative examination findings between the DPH and non-DPH groups.

RESULTS

DPH occurred in 39 patients (41.5%), and the lowest serum sodium levels were generally observed during postoperative days (PODs) 7-9. They needed a 3-day longer hospital stay than those without DPH. The DPH group had lower preoperative body weight and body mass index. In addition, a transient increase in body weight during PODs 5-7 occurred with a transient decrease in urinary volume in the DPH group. Preoperative and postoperative GH and insulin-like growth factor-1 levels did not differ between the two groups.

CONCLUSION

The findings suggested that lower preoperative weight and a postoperative transient gain in body weight are associated with an increased risk of DPH in acromegaly patients undergoing transsphenoidal surgery.

Obesity and chronic kidney disease

The prevalence of obesity has increased dramatically during the past decades, which has been a major health problem. Since 1975, the number of people with obesity worldwide has nearly tripled. An increasing number of studies find obesity as a driver of chronic kidney disease (CKD) progression, and the mechanisms are complex and include hemodynamic changes, inflammation, oxidative stress, and activation of the renin-angiotensin-aldosterone system (RAAS). Obesity-related kidney disease is characterized by glomerulomegaly, which is often accompanied by localized and segmental glomerulosclerosis lesions. In these patients, the early symptoms are atypical, with microproteinuria being the main clinical manifestation and nephrotic syndrome being rare. Weight loss and RAAS blockers have a protective effect on obesity-related CKD, but even so, a significant proportion of patients eventually progress to end-stage renal disease despite treatment. Thus, it is critical to comprehend the mechanisms underlying obesity-related CKD to create new tactics for slowing or stopping disease progression. In this review, we summarize current knowledge on the mechanisms of obesity-related kidney disease, its pathological changes, and future perspectives on its treatment.

Surgical outcomes associated with sleep apnea syndrome in Stanford A aortic dissection patients

Background

Patients suffering from aortic dissection (AD) often experience sleep apnea syndrome (SAS), which aggravates their respiratory function and aortic false lumen expansion.

Methods

We analyzed the peri-operative data of Stanford A AD patients, with or without SAS, between January 2017 and June 2019. Subjects were separated into SAS positive (SAS⁺) and SAS negative (SAS⁻) cohorts, based on the Apnea-Hypopnea Index (AHI) and the Oxygen Desaturation Index (ODI). We next analyzed variables between the SAS⁺ and SAS⁻ groups.

Results

155, out of 198 AAD patients, were enlisted for this study. SAS⁺ patients exhibited higher rates of pneumonia (p < 0.001), heart failure (HF, p = 0.038), acute kidney injury (AKI, p = 0.001), ventilation time (p = 0.009), and hospitalization duration (p < 0.001). According to subsequent follow-ups, the unstented aorta false lumen dilatation (FLD) rate increased markedly, with increasing degree of SAS (p < 0.001, according to AHI and ODI). The SAS⁺ patients exhibited worse cumulative survival rate (p = 0.025). The significant risk factors (RF) for poor survival were: severe (p = 0.002) or moderate SAS (p = 0.008), prolonged ventilation time (p = 0.018), AKI (p = 0.015), HF New York Heart Association (NYHA) IV (p = 0.005) or III (p = 0.015), pneumonia (p = 0.005), Marfan syndrome (p = 0.010), systolic blood pressure (BP) upon arrival (p = 0.009), and BMI ≥ 30 (p = 0.004).

Conclusions

SAS⁺ Stanford A AD patients primarily exhibited higher rates of complications and low survival rates in the mid-time follow-up. Hence, the RFs associated with poor survival must be monitored carefully in SAS patients. Moreover, the FLD rate is related to the degree of SAS, thus treating SAS may mitigate FLD.

Mechanisms underlying acupuncture therapy in chronic kidney disease: A narrative overview of preclinical studies and clinical trials

Chronic kidney disease (CKD) is associated with high incidence, low awareness, and high disability rates among the population. Moreover, the disease significantly affects the physical and mental health of patients. Approximately 25% of patients with CKD develop end-stage renal disease (ESRD) within 20 years of diagnosis and have to rely on renal replacement therapy, which is associated with high mortality, heavy economic burden, and symptoms including fatigue, pain, insomnia, uremia pruritus, and restless leg syndrome. Currently, the means to delay the progress of CKD are insufficient; therefore, developing strategies for delaying CKD progression has important practical implications. In recent years, more and more people are accepting the traditional Chinese medical technique "acupuncture." Acupuncture has been shown to improve the uncomfortable symptoms of various diseases through stimulation (needling, medicinal moxibustion, infrared radiation, and acupressure) of acupoints. Its application has been known for thousands of years, and its safety and efficacy have been verified. As a convenient and inexpensive complementary therapy for CKD, acupuncture has recently been gaining interest among clinicians and scientists. Nevertheless, although clinical trials and meta-analysis findings have demonstrated the efficacy of acupuncture in reducing albuminuria, improving glomerular filtration rate, relieving symptoms, and improving the quality of life of patients with CKD, the underlying mechanisms involved are still not completely understood. Few studies explored the correlation between acupuncture and renal pathological diagnosis. The aim of this study was to conduct a literature review summarizing the currently known mechanisms by which acupuncture could delay the progress of CKD and improve symptoms in patients with ESRD. This review help provide a theoretical basis for further research regarding the influence of acupuncture on renal pathology in patients with CKD, as well as the differences between specific therapeutic mechanisms of acupuncture in different renal pathological diagnosis. The evidence in this review indicates that acupuncture may produce marked effects on blocking and reversing the critical risk factors of CKD progression (e.g., hyperglycemia, hypertension, hyperlipidemia, obesity, aging, and anemia) to improve the survival of patients with CKD via mechanisms including oxidative stress inhibition, reducing inflammatory effects, improving hemodynamics, maintaining podocyte structure, and increasing energy metabolism.

Antitoxic Effects of Curcumin against Obesity-Induced Multi-Organs' Biochemical and Histopathological Abnormalities in an Animal Model

Background

Obesity is a significant public health problem that is characterized by an increase in oxidative stress and enhanced inflammatory responses associated with immune cell invasion of adipose tissues. This study assessed several biochemical abnormalities, apoptosis, oxidative stress status, and associated histological changes in the liver, duodenum, and heart brought on by high-fat diet-induced obesity in rats. It also assessed the mechanistic benefits of curcumin in reversing these inflammatory, metabolic, and histological impairments.

Methods

Rats were assigned into three groups each including ten rats: the control group (CD), the high-fat diet group (HFD), and the high-fat diet + curcumin (HFDC) group. Serum glucose, insulin, and triglycerides (TAGs) were observed. In addition, apoptosis (indicated by hepatic DNA fragmentation) and oxidative stress status (indicated by hepatic MPO, GSH, and SOD) were assessed. Histopathological examinations included the GIT (liver and duodenum) and heart in addition to quantitative real-time polymerase chain reaction (qRT-PCR) assays of the adipose tissue genetic expressions for inflammatory signaling pathways (TLR4, IL-6, and TNF-α).

Results

The overall findings showed that the HFD group exhibited significantly higher levels of glucose, TAGs, and insulin than the control group (P < 0.01). The histological abnormalities of the studied organs in the HFD group were paralleled by these biochemical abnormalities, which were strongly associated with increased apoptosis, increased oxidative stress, and increased expression of the inflammatory signaling markers. There were significant improvements in the HFDC group in terms of biochemical, inflammatory, and histological investigations.

Conclusions

This study's findings concluded that obesity is significantly associated with biochemical and microscopic alterations in many organs. Curcumin exerted potent antitoxic, antioxidant, tissue-protective, and antiobesity effects. Curcumin is recommended to be added to various dietary regimens to prevent or delay the organs' dysfunction among obese people.

Age-dependent differences in the prognostic relevance of body composition-related variables in type A aortic dissection patients

Background

The current research is allocated to appraise the association between the parameters of body composition and findings in type A aortic dissection (TAAD) cases in diverse age groups.

Methods

Data from consecutive TAAD patients undergoing implantation of modified triple-branched stent-graft from January 2017 and December 2019 were prospectively collected and analyzed. A regression model of Cox proportional hazard was employed to assess correlations among body composition-related variables (body mass index [BMI], lean body mass [LBM], body surface area [BSA], and LBM index) as well as cumulative mortality.

Results

Overall, 258 patients (53.9 ± 11.1 years old; 72.9% male) were separated into young (n = 110) and elderly (n = 148) age groups based upon whether they were younger or older than 50 years of age. Of these patients, 247 survivors were included in subsequent analyses over an average 26.8 ± 11.6 month follow-up duration. Multivariate analyses in the elderly group instead of young group indicated that increased BMI (p = 0.042), BMI ≤ 18.5 kg/m² (p = 0.025), and lower LBM index values (p = 0.019) were significant predictors of increased total all-cause cumulative mortality. BMI was considerably positively correlated with estimated all-cause cumulative mortality in elderly but not young TAAD cases.

Conclusion

Briefly, these results suggest that BMI and LBM indices are only significant predictors of TAAD patient all-cause mortality in elderly patient cohorts, whereas they do not offer significant prognostic value for younger patients. As such, these age differences must be taken into consideration when conducting stratified risk assessments based upon TAAD patient body composition characteristics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01742-1.

Activation of AMP kinase ameliorates kidney vascular dysfunction, oxidative stress and inflammation in rodent models of obesity

BACKGROUND AND PURPOSE

Obesity is a risk factor for the development of chronic kidney disease independent of diabetes, hypertension and other co-morbidities. Obesity-associated nephropathy is linked to dysregulation of the cell energy sensor AMP-activated protein kinase (AMPK). We aimed here to assess whether impairment of AMPK activity may cause renal arterial dysfunction in obesity and to evaluate the therapeutic potential of activating renal AMPK.

EXPERIMENTAL APPROACH

Effects of the AMPK activator A769662 were assessed on intrarenal arteries isolated from ob/ob mice and obese Zucker rats and then mounted in microvascular myographs. Superoxide and hydrogen peroxide production were measured by chemiluminescence and fluorescence, respectively, and protein expression was analysed by western blotting.

KEY RESULTS

Endothelium-dependent vasodilation and PI3K/Akt/eNOS pathway were impaired in preglomerular arteries from genetically obese rats and mice, along with impaired arterial AMPK activity and blunted relaxations induced by the AMPK activator A769662. Acute ex vivo exposure to A769662 restored endothelial function and enhanced activity of PI3K/Akt/eNOS pathway in obese rats, whereas in vivo treatment with A769662 improved metabolic state and ameliorated endothelial dysfunction, reduced inflammatory markers and vascular oxidative stress in renal arteries and restored redox balance in renal cortex of obese mice.

CONCLUSION AND IMPLICATIONS

These results demonstrate that AMPK dysregulation underlies obesity-associated kidney vascular dysfunction and activation of AMPK improves metabolic state, protects renal endothelial function and exerts potent vascular antioxidant and anti-inflammatory effects. The beneficial effects of vascular AMPK activation might represent a promising therapeutic approach to the treatment of obesity-related kidney injury.

Isosteviol Sodium Attenuates High Fat/High Cholesterol-Induced Kidney Dysfunction by Inhibiting Inflammation, Oxidative Stress and Apoptosis

The sodium salt of isosteviol (STVNa) is a beyerane diterpene synthesized through acid hydrolysis of stevioside. STVNa improves multiple types of tissue injuries. However, it is not known how isosteviol sodium affects high-fat and high cholesterol diet (HFD)-induced kidney. Therefore, in this study we examined the potential molecular mechanism underlying STVNa mediated protective effect against high fat/high cholesterol-induced kidney dysfunction in HFD-induced kidney injury. Sprague-Dawley (SD) rats were allocated into six groups: the normal group, HFD group and HFD treated with three doses of STVNa, fenofibrate treatment group. The results indicated that HFD induced kidney injury evident by a 60% increase in serum creatinine (CRE) leves. In addition, there was a significant accumulation of triglycerides (approx. 60%), fatty acids (approx. 50%) and total cholesterol (approx. 2.5 fold) in the kidneys. STVNa inhibited HFD-induced kidney injury evident by reducing the increased levels of serum CRE. Specifically, STVNa attenuated HFD-induced kidney injury by inhibiting inflammation, oxidative stress, and apoptosis. These findings indicate that STVNa has a therapeutic potential for HFD-induced kidney dysfunction. The mechanisms of this pharmacological effect are through the inhibition of inflammation, oxidative stress and apoptosis.

Impact of adipose tissue in chronic kidney disease development (Review)

Obesity is a worldwide pandemic health issue. Obesity is associated with the pathogenesis of type 2 diabetes, hypertension, dyslipidemia, cardiovascular diseases, cancer, and kidney diseases. This systemic disease can affect the kidneys by two mechanisms: Indirectly through diabetes mellitus (DM) and hypertension and directly through adipokines secreted by adipose tissue. Obesity is a risk factor for chronic kidney disease (CKD), which is associated with an increased risk of morbidity and mortality among the adult population. Increased visceral adipose tissue leads to renal glomerular hyperfiltration and hyperperfusion, which may lead to glomerular hypertrophy, proteinuria, and CKD development. Adipokines are hormones produced by fat tissue. They are involved in energy homeostasis, sugar and fat metabolism, reproduction, immunity, and thermogenesis control. Hormones and cytokines secreted by adipose tissue contribute to the development and progression of CKD. Decreased serum or urinary adiponectin levels are specific in diabetic and non-diabetic CKD patients, while leptin presents increased levels, and both are associated with the development of glomerulopathy. Excessive adipose tissue is associated with inflammation, oxidative stress (OS), insulin resistance and activation of the renin angiotensin-aldosterone system (RAAS). Therefore, adipose tissue dysfunction plays an important role in the development of CKD.

Obesity, kidney dysfunction, and inflammation: interactions in hypertension

Obesity contributes 65-75% of the risk for human primary (essential) hypertension (HT) which is a major driver of cardiovascular and kidney diseases. Kidney dysfunction, associated with increased renal sodium reabsorption and compensatory glomerular hyperfiltration, plays a key role in initiating obesity-HT and target organ injury. Mediators of kidney dysfunction and increased blood pressure include (i) elevated renal sympathetic nerve activity (RSNA); (ii) increased antinatriuretic hormones such as angiotensin II and aldosterone; (iii) relative deficiency of natriuretic hormones; (iv) renal compression by fat in and around the kidneys; and (v) activation of innate and adaptive immune cells that invade tissues throughout the body, producing inflammatory cytokines/chemokines that contribute to vascular and target organ injury, and exacerbate HT. These neurohormonal, renal, and inflammatory mechanisms of obesity-HT are interdependent. For example, excess adiposity increases the adipocyte-derived cytokine leptin which increases RSNA by stimulating the central nervous system proopiomelanocortin-melanocortin 4 receptor pathway. Excess visceral, perirenal and renal sinus fat compress the kidneys which, along with increased RSNA, contribute to renin-angiotensin-aldosterone system activation, although obesity may also activate mineralocorticoid receptors independent of aldosterone. Prolonged obesity, HT, metabolic abnormalities, and inflammation cause progressive renal injury, making HT more resistant to therapy and often requiring multiple antihypertensive drugs and concurrent treatment of dyslipidaemia, insulin resistance, diabetes, and inflammation. More effective anti-obesity drugs are needed to prevent the cascade of cardiorenal, metabolic, and immune disorders that threaten to overwhelm health care systems as obesity prevalence continues to increase.

Feasibility of machine learning based predictive modelling of postoperative hyponatremia after pituitary surgery

PURPOSE

Hyponatremia after pituitary surgery is a frequent finding with potential severe complications and the most common cause for readmission. Several studies have found parameters associated with postoperative hyponatremia, but no reliable specific predictor was described yet. This pilot study evaluates the feasibility of machine learning (ML) algorithms to predict postoperative hyponatremia after resection of pituitary lesions.

METHODS

Retrospective screening of a prospective registry of patients who underwent transsphenoidal surgery for pituitary lesions. Hyponatremia within 30 days after surgery was the primary outcome. Several pre- and intraoperative clinical, procedural and laboratory features were selected to train different ML algorithms. Trained models were compared using common performance metrics. Final model was internally validated on the testing dataset.

RESULTS

From 207 patients included in the study, 44 (22%) showed a hyponatremia within 30 days postoperatively. Hyponatremic measurements peaked directly postoperatively (day 0-1) and around day 7. Bootstrapped performance metrics of different trained ML-models showed largest area under the receiver operating characteristic curve (AUROC) for the boosted generalized linear model (67.1%), followed by the Naïve Bayes classifier (64.6%). The discriminative capability of the final model was assessed by predicting on unseen dataset. Large AUROC (84.3%; 67.0-96.4), sensitivity (81.8%) and specificity (77.5%) with an overall accuracy of 78.4% (66.7-88.2) was reached.

CONCLUSION

Our trained ML-model was able to learn the complex risk factor interactions and showed a high discriminative capability on unseen patient data. In conclusion, ML-methods can predict postoperative hyponatremia and thus potentially reduce morbidity and improve patient safety.

Measures of adiposity correlate with renal filtration in young nulliparous women: An observational cohort study

OBJECTIVE

Renal hyperfiltration, which has been documented in severe obesity and obesity-associated hypertension, can occur with hypertensive disorders of pregnancy. Identification of prepregnancy risk factors for unrecognized renal hyperfiltration could inform screening and intervention strategies to protect against pregnancy complications. In young, healthy, nulliparous women, associations between associations between measures of adiposity, insulin resistance, and renal vascular resistance were thus evaluated.

METHODS

This is a secondary analysis of a prospective observational trial characterizing associations of prepregnancy and late-pregnancy maternal physiology. Seventy-nine nulligravid women aged 18-42 years without major medical conditions were assessed for percent android body fat using dual-energy X-ray absorption. Renal cortical vessel blood flow resistance index (CVRI) was determined using Doppler ultrasonography. Creatinine clearance was calculated from 24-hour urine collection.

RESULTS

Renal CVRI inversely correlates with body mass index (r = -0.23, p = 0.047), percent android fat (r = -0.30, p = 0.008), and supine pulse (r = -0.44, p < 0.001). Creatinine clearance is positively associated with BMI and HOMA-IR.In regression modeling, supine pulse (r2 = 0.22, p < 0.001) and cardiac index (r2 = 0.05, p = 0.045) predict renal CVRI, whereas HOMA-IR (r2 = 0.11, p = 0.008) and cardiac output (r2 = 0.06, p = 0.039) predict creatinine clearance. Measures of adiposity are not independently predictive of either measure.

CONCLUSIONS

In healthy young women, measures of adiposity and insulin resistance correlate positively with renal filtration. Preclinical manifestations of renal hyperfiltration may have implications for pregnancy outcomes.

The Association Between Obesity and Risk of Acute Kidney Injury After Cardiac Surgery

OBJECTIVE

To determine the relationship between obesity and the risk of AKI after cardiac surgery (CS-AKI) in a cohort study.

METHODS

A total of 1,601 patients undergoing cardiac surgery were collected and their incidence of CS-AKI was recorded. They were divided into underweight, normal weight, overweight, and obese groups. Logistic regression was used to estimate the association between BMI (body mass index) and CS-AKI risk. Then, a meta-analysis of published cohort studies was conducted to confirm this result using PubMed and Embase databases.

RESULTS

A significant association was observed in this independent cohort after adjusting age, gender, hypertension and New York Heart Association classification (NYHA) class. Compared with normal BMI group (18.5 ≤ BMI < 24.0), the individuals with aberrant BMI level had an increased AKI risk (OR: 1.68, 95% CI: 1.01-2.78) for BMI < 18.5 group and (OR: 1.43, 95% CI: 0.96-2.15) for BMI ≥ 28.0. Interestingly, the U-shape curve showed the CS-AKI risk reduced with the increasing of BMI when BMI ≤ 24.0. As BMI increases with BMI > 24.0, the risk of developing CS-AKI increased significantly. In the confirmed meta-analysis, compared with normal weight, overweight group with cardiac surgery had higher AKI risk (OR: 1.28, 95% CI: 1.16-1.41, P_{heterogeneity} = 0.49). The similar association was found in obesity subgroup (OR: 1.79, 95% CI: 1.57-2.03, P_{heterogeneity} = 0.42).

CONCLUSION

In conclusion, the results suggested that abnormal BMI was a risk factor for CS-AKI independently.

Readmission after endoscopic transsphenoidal pituitary surgery: analysis of 584 consecutive cases

OBJECTIVE

Hospital readmission is a key component in value-based healthcare models but there are limited data about the 30-day readmission rate after endonasal endoscopic transsphenoidal surgery (EETS) for pituitary adenoma. The objective of this study was to determine the incidence and identify factors associated with 30-day readmission after EETS for pituitary adenoma.

METHODS

The authors analyzed a prospectively acquired database of patients who underwent EETS for pituitary adenoma from 2005 to 2018 at NewYork-Presbyterian Hospital, Weill Cornell Medicine. Clinical, socioeconomic, and radiographic data were reviewed for cases of unplanned readmission within 30 days of surgery and, as a control group, for all other patients in the series who were not readmitted. Statistical significance was determined with an alpha < 0.05 using Pearson's chi-square and Fisher's exact tests for categorical variables and the independent-samples t-test for continuous variables.

RESULTS

Of 584 patients undergoing EETS for pituitary adenoma, 27 (4.6%) had unplanned readmission within 30 days. Most readmissions occurred within the first week after surgery, with a mean time to readmission of 6.6 ± 3.9 days. The majority of readmissions (59%) were for hyponatremia. These patients had a mean sodium level of 120.6 ± 4.6 mEq/L at presentation. Other causes of readmission were epistaxis (11%), spinal headache (11%), sellar hematoma (7.4%), CSF leak (3.7%), nonspecific headache (3.7%), and pulmonary embolism (3.7%). The postoperative length of stay was significantly shorter for patients who were readmitted than for the controls (2.7 ± 1.0 days vs 3.9 ± 3.2 days; p < 0.05). Patients readmitted for hyponatremia had an initial length of stay of 2.6 ± 0.9 days, the shortest of any cause for readmission. The mean BMI was significantly lower for readmitted patients than for the controls (26.4 ± 3.9 kg/m2 vs 29.3 ± 6.1 kg/m2; p < 0.05).

CONCLUSIONS

Readmission after EETS for pituitary adenoma is a relatively rare phenomenon, with delayed hyponatremia being the primary cause. The study results demonstrate that shorter postoperative length of stay and lower BMI were associated with 30-day readmission.

BMI, nephroangiosclerosis and glomerulonephritis: Is there any meeting point?

AIM

Overweight has been related to renal arteriolosclerosis and is able to modify intrarenal haemodynamics. Increasing evidence suggests an association between weight in excess and primary glomerulonephritis (GN). The aim of this study was to evaluate the relationship between nutritional status and intrarenal arterial stiffness in primary GN associated to arteriolosclerosis. We have considered the glomerular diameter (GD) as morphological parameter in overweight and obese patients.

METHODS

Clinical, laboratory, anthropometric data and renal Doppler ultrasound were performed immediately before kidney biopsy.

RESULTS

Primary GN was diagnosed in 92 patients. Mild arteriolosclerosis was found in 19.6% of patients, moderate in the 20.6%, severe in the 10.9% while nephroangiosclerosis was diagnosed in 8.7% of patients. A positive correlation was found between body mass index (BMI) and renal resistive index (RRI) (P < 0.01, r = 0.34). RRI were significantly higher in patients with severe arteriolosclerosis at kidney biopsy (P < 0.05). Furthermore, higher BMI (P < 0.01) was found in patients with renal arteriolosclerosis than patients without renal arteriolosclerosis (26.1 ± 4.4 kg/m² vs. 24.4 ± 4.5 kg/m² ). Finally, in overweight and obesity patients we found a positive correlation between maximal GD and BMI (P < 0.01) and maximal GD and RRI (P < 0.01).

CONCLUSION

In overweight and obese patients affected by primary GN, it might be found not only glomerular but also renal vascular lesions. Finally, we believe that nephroangiosclerosis, in combination with weight in excess, is able to modify intrarenal haemodynamic parameters. Moreover, in response to these changes, the renal tissue morphologically promotes a GD increase regardless of the underlying GN.

Influence of Body Mass Index on Outcomes of Patients Undergoing Surgery for Acute Aortic Dissection: A Propensity-Matched Analysis

To determine whether body mass index ≥30 kg/m² affects morbidity and mortality rates in patients undergoing surgery for type A acute aortic dissection, we conducted a retrospective study of 201 patients with type A dissection. Patients were divided into 2 groups according to body mass index (BMI): nonobese (BMI, <30 kg/m²; 158 patients) and obese (BMI, ≥30 kg/m²; 43 patients). Propensity score matching was used to reduce selection bias. The overall mortality rate was 19% (38/201 patients). The perioperative mortality rate was higher in the obese group, both in the overall cohort (33% vs 15%; P=0.01) and in the propensity-matched cohort (32% vs 12%; P=0.039). In the propensity-matched cohort, patients with obesity had higher rates of low cardiac output syndrome (26% vs 6%; P=0.045) and pulmonary complications (32% vs 9%; P=0.033) than those without obesity. The overall 5-year survival rates were 52.5% ± 7.8% in the obese group and 70.3% ± 4.4% in the nonobese group (P=0.036). In the propensity-matched cohort, the 5-year survival rates were 54.3% ± 8.9% in the obese group and 81.6% ± 6.8% in the nonobese group (P=0.018). Patients with obesity (BMI, ≥30 kg/m²) who underwent surgery for type A acute aortic dissection had higher operative mortality rates and an increased risk of low cardiac output syndrome, pulmonary complications, and other postoperative morbidities than did patients without obesity. Additional extensive studies are needed to confirm our findings.

Coagonist of glucagon-like peptide-1 and glucagon receptors ameliorates kidney injury in murine models of obesity and diabetes mellitus

AIM

To investigate the role of glucagon-like peptide-1 (GLP-1)/glucagon receptors coagonist on renal dysfunction associated with diabetes and obesity.

METHODS

Chronic high-fat diet fed C57BL/6J mice, streptozotocin-treated high-fat diet fed C57BL/6J mice and diabetic C57BLKS/J db/db mice were used as models of diabetes-induced renal dysfunction. The streptozotocin-treated high-fat diet fed mice and db/db mice were treated with the GLP-1 and glucagon receptors coagonist (Aib2 C24 Chimera2, 150 μg/kg, sc) for twelve weeks, while in chronic high-fat diet fed mice, coagonist (Aib2 C24 Chimera2, 150 μg/kg, sc) treatment was continued for forty weeks. Kidney function, histology, fibrosis, inflammation, and plasma biochemistry were assessed at the end of the treatment.

RESULTS

Coagonist treatment decreased body weight, plasma lipids, insulin resistance, creatinine, blood urea nitrogen, urinary albumin excretion rate and renal lipids. In kidney, expression of lipogenic genes (SREBP-1C, FAS, and SCD-1) was decreased, and expression of genes involved in β-oxidation (CPT-1 and PPAR-α) was increased due to coagonist treatment. In plasma, coagonist treatment increased adiponectin and FGF21 and decreased IL-6 and TNF-α. Coagonist treatment reduced expression of inflammatory (TNF-α, MCP-1, and MMP-9) and pro-fibrotic (TGF-β, COL1A1, and α-SMA) genes and also improved histological derangement in renal tissue.

CONCLUSION

Coagonist of GLP-1 and glucagon receptors alleviated diabetes and obesity-induced renal dysfunction by reducing glucose intolerance, obesity, and hyperlipidemia.

Obesity as a Disease

Obesity is a complex disease with many causal factors, associated with multiple comorbidities that contribute to significant morbidity and mortality. It is a highly prevalent disease that poses an enormous health and economic burden to society. This article reviews the mechanisms of obesity and its related comorbidities.

Hypertension in Obesity and the Impact of Weight Loss

PURPOSE OF REVIEW

Several interrelated mechanisms promote the development of hypertension in obesity, often contributing to end organ damage including cardiovascular disease and chronic kidney disease.

RECENT FINDINGS

The treatment of hypertension in obesity is complicated by a high prevalence of resistant hypertension, as well as unpredictable hemodynamic effects of many medications. Weight loss stabilizes neurohormonal activity and causes clinically significant reductions in blood pressure. While lifestyle interventions can improve blood pressure, they fail to consistently yield sustained weight loss and have not demonstrated long-term benefits. Bariatric surgery provides more permanent weight reduction, corresponding with dramatic declines in blood pressure and attenuation of long-term cardiovascular risk. Hypertension is closely linked to the prevalence, pathophysiology, and morbidity of obesity. There are multiple barriers to managing hypertension in obesity. Surgical weight loss offers the most promise in reducing blood pressure and decreasing end organ damage in this patient population.

Lung function and impaired kidney function in relation to metabolic syndrome

PURPOSE

This study aimed to assess the relationships between abnormal lung function and indicators of chronic kidney disease in relation to metabolic syndrome (MetS) by using data from the 2011-2013 Korea National Health and Nutrition Examination Survey.

METHODS

Using the data of 8551 Korean adults (3798 men, 4753 women, ≥40 years), lung function categories [obstructive lung disease (OLD), restrictive lung disease (RLD), and non-obstructive/non-restrictive lung disease (reference group)] were defined for each gender. Albuminuria and low estimated glomerular filtration rate (eGFR) were defined as urine albumin-to-creatinine ratio ≥30 mg/g and eGFR < 60 mL/min/1.73 m². Gender-specific logistic regression analysis was performed after adjusting for age, educational level, smoking, alcohol use, physical activity, and medication use for chronic diseases.

RESULTS

Compared to the reference group, low eGFR was associated with higher odds for RLD in men and RLD or OLD in women when they did not have MetS. In those with MetS, low eGFR was associated with higher odds for OLD in men and RLD or OLD in women. Albuminuria was associated with higher odds for RLD in men who did not have MetS, while it was associated with higher odds for RLD or OLD in men and women who had MetS.

CONCLUSIONS

Abnormal lung function was associated with increased odds for chronic kidney disease indicators, when combined with MetS in both gender. Even in those without MetS, RLD in men was associated with increased odds for low eGFR or albuminuria, while RLD or OLD in women was associated with increased odds for low eGFR.

Obesity: A Perspective from Hypertension

The prevalence of obesity-related hypertension is high worldwide and has become a major health issue. The mechanisms by which obesity relates to hypertensive disease are still under intense research scrutiny, and include altered hemodynamics, impaired sodium homeostasis, renal dysfunction, autonomic nervous system imbalance, endocrine alterations, oxidative stress and inflammation, and vascular injury. Most of these contributing factors interact with each other at multiple levels. Thus, as a multifactorial and complex disease, obesity-related hypertension should be recognized as a distinctive form of hypertension, and specific considerations should apply in planning therapeutic approaches to treat obese individuals with high blood pressure.

Involvement of Endoplasmic Reticulum Stress, Autophagy, and Apoptosis in Advanced Glycation End Products-Induced Glomerular Mesangial Cell Injury

Advanced glycation end-products (AGEs)-induced mesangial cell death is one of major causes of glomerulus dysfunction in diabetic nephropathy. Both endoplasmic reticulum (ER) stress and autophagy are adaptive responses in cells under environmental stress and participate in the renal diseases. The role of ER stress and autophagy in AGEs-induced mesangial cell death is still unclear. Here, we investigated the effect and mechanism of AGEs on glomerular mesangial cells. AGEs dose-dependently decreased mesangial cell viability and induced cell apoptosis. AGEs also induced ER stress signals in a time- and dose-dependent manner. Inhibition of ER stress with 4-phenylbutyric acid effectively inhibited the activation of eIF2α and CHOP signals and reversed AGEs-induced cell apoptosis. AGEs also activated LC-3 cleavage, increased Atg5 expression, and decreased p62 expression, which indicated the autophagy induction in mesangial cells. Inhibition of autophagy by Atg5 siRNAs transfection aggravated AGEs-induced mesangial cell apoptosis. Moreover, ER stress inhibition by 4-phenylbutyric acid significantly reversed AGEs-induced autophagy, but autophagy inhibition did not influence the AGEs-induced ER stress-related signals activation. These results suggest that AGEs induce mesangial cell apoptosis via an ER stress-triggered signaling pathway. Atg5-dependent autophagy plays a protective role. These findings may offer a new strategy against AGEs toxicity in the kidney.

Obesity, Renin-Angiotensin System Blockade and Risk of Adverse Renal Outcomes: A Population-Based Cohort Study

BACKGROUND

Obesity substantially increases the risk of the development of chronic kidney disease. Adipose tissue expresses all of the components of the renin-angiotensin system (RAS), contributing to the high prevalence of hypertension in obese patients and driving renal hyperfiltration and subsequent glomerular injury.

METHODS

We performed a retrospective cohort study using a United Kingdom primary care database, evaluating the effect of time-updated exposure to RAS blockade versus all other antihypertensive medications in obese, hypertensive, non-diabetic patients. We used Cox proportional hazards modeling with and without marginal structural modeling to assess the hazards of developing a primary outcome of 50% reduction in estimated glomerular filtration rate (eGFR) (across 2 consecutive values), end stage renal disease or death.

RESULTS

A total of 219,701 patients met inclusion criteria, with a median 7.2 years of follow-up. Median baseline eGFR was 72.6 ml/min/1.73 m2. Compared to other antihypertensive medications, patients treated with RAS blockade had a modestly elevated hazard of adverse renal outcomes using traditional Cox regression (hazard ratio (HR) 1.04, 95% CI 1.01-1.07) and no significantly increased hazard by marginal structural modeling (HR 1.02, 95% CI 0.97-1.08). Patients treated with RAS blockade had a significantly reduced hazard of incident diabetes, but no significant difference in mortality.

CONCLUSION

This study, conducted in a large real-world cohort, provides evidence that RAS blockade may not provide benefit with regard to longitudinal renal outcomes in obese, hypertensive patients. Further research is needed to elucidate the hemodynamic and renoprotective role of antihypertensive medications in obese patients.

Metabolic Syndrome and Decreased Estimated Glomerular Filtration Rate in Relation to Muscle Mass

BACKGROUND

This study aimed to evaluate the association between decreased estimated glomerular filtration rate (eGFR <60 mL/min/1.73 m²) and metabolic syndrome (MetS) according to muscle mass.

METHODS

Body composition was measured in 3351 men and 4394 women aged between 19 and 97 years using the 2010-2011 Korea National Health and Nutrition Examination Survey data using dual-energy X-ray absorptiometry and low and high muscle mass. Groups were identified using the mean sex-specific appendicular muscle mass/height². eGFR was computed using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation; MetS was defined by the Harmonized definition and International Diabetes Federation criteria.

RESULTS

When stratified by muscle mass and adjusted for covariates, MetS was not associated with decreased eGFR in men with high muscle mass, but was associated in men with low muscle mass (odds ratio 3.19-3.87). MetS was associated with decreased eGFR in women with high (odds ratio 2.41-2.68) and low (odds ratio 2.45-2.55) muscle mass. Men with MetS and low muscle mass, women with MetS and high muscle mass, and women with MetS and low muscle mass had 2.95-3.21, 2.23-2.59, and 2.75-2.76 times higher odds for decreased eGFR, respectively, compared with their MetS-free and high muscle mass counterparts, after adjusting for covariates. The odds ratio was not significant for men with high muscle mass and MetS.

CONCLUSIONS

MetS was associated with decreased eGFR in women, regardless of muscle mass, and in men with low muscle mass. High muscle mass in men may attenuate the association.

Cardiovascular and renal effects of weight reduction in obesity and the metabolic syndrome

Obesity is a critical public health issue worldwide. Patients with obesity have markedly increased morbidity and mortality compared to the general population. The increased health risks of obesity in part are due to its close association with each of the other components of the metabolic syndrome, including hypertension, dyslipidemia, and insulin resistance. Accordingly, obese individuals are at particularly increased risk of cardiovascular disease and chronic kidney disease. Modest weight loss results in improvements in serum cholesterol levels, blood pressure, and glycemic profiles. Lifestyle interventions for weight loss have long been the mainstay of treatment in obesity. However, the existing literature demonstrates limited weight loss sustainability and inconsistent cardiovascular and renal benefits using these modalities. In addition to improvements in intermediate risk factors, surgical interventions provide a more lasting impact on long-term cardiovascular and renal outcomes, though carry higher short-term risks due to perioperative complications.

Ellagic acid inhibits non-enzymatic glycation and prevents proteinuria in diabetic rats

The formation of advanced glycation end products (AGEs) is a characteristic feature of diabetic tissues and accumulation of AGEs been implicated in the pathogenesis of diabetic nephropathy (DN). Ellagic acid prevented the accumulation of AGEs and in turn ameliorated proteinurea in diabetic rats.

A Review of the Toxicologic Implications of Obesity

The increasing prevalence of obesity in developed nations has far-reaching implications for medical toxicology. The management of obese patients is complicated by comorbid illnesses, changes in cardiovascular and respiratory physiology, alterations in pharmacokinetics, and a lack of studies to identify appropriate dosing for current therapeutics and antidotes. In this review article, we examine obesity-associated physiologic and pharmacokinetic changes that may increase the vulnerability of obese patients to overdose. Further research is needed to characterize the relationship between drug toxicity and obesity.

Impact of Lifestyle Modification on Diabetic Kidney Disease

Kidney disease is common in patients with type 1 and type 2 diabetes mellitus and is associated with adverse health outcomes, including progression to end-stage renal disease. In the general population, adherence to a healthy lifestyle is known to reduce the risk of cardiovascular events and death. Among individuals with diabetic kidney disease, modifications in lifestyle factors, including diet, physical activity, smoking habits, and body mass index, represent a promising cost-effective therapeutic adjunct to pharmacologic treatment of kidney disease incidence and progression.

Diabetic Kidney Disease: A Syndrome Rather Than a Single Disease

The term "diabetic kidney" has recently been proposed to encompass the various lesions, involving all kidney structures that characterize protean kidney damage in patients with diabetes. While glomerular diseases may follow the stepwise progression that was described several decades ago, the tenet that proteinuria identifies diabetic nephropathy is disputed today and should be limited to glomerular lesions. Improvements in glycemic control may have contributed to a decrease in the prevalence of glomerular lesions, initially described as hallmarks of diabetic nephropathy, and revealed other types of renal damage, mainly related to vasculature and interstitium, and these types usually present with little or no proteinuria. Whilst glomerular damage is the hallmark of microvascular lesions, ischemic nephropathies, renal infarction, and cholesterol emboli syndrome are the result of macrovascular involvement, and the presence of underlying renal damage sets the stage for acute infections and drug-induced kidney injuries. Impairment of the phagocytic response can cause severe and unusual forms of acute and chronic pyelonephritis. It is thus concluded that screening for albuminuria, which is useful for detecting "glomerular diabetic nephropathy", does not identify all potential nephropathies in diabetes patients. As diabetes is a risk factor for all forms of kidney disease, diagnosis in diabetic patients should include the same combination of biochemical, clinical, and imaging tests as employed in non-diabetic subjects, but with the specific consideration that chronic kidney disease (CKD) may develop more rapidly and severely in diabetic patients.

Obesity and kidney disease: differential effects of obesity on adipose tissue and kidney inflammation and fibrosis

PURPOSE OF REVIEW

To provide a perspective by investigating the potential cross-talk between the adipose tissue and the kidney during obesity.

RECENT FINDINGS

It is well established that excessive caloric intake contributes to organ injury. The associated increased adiposity initiates a cascade of cellular events that leads to progressive obesity-associated diseases such as kidney disease. Recent evidence has indicated that adipose tissue produces bioactive substances that contribute to obesity-related kidney disease, altering the renal function and structure. In parallel, proinflammatory processes within the adipose tissue can also lead to pathophysiological changes in the kidney during the obese state.

SUMMARY

Despite considerable efforts to better characterize the pathophysiology of obesity-related metabolic disease, there are still a lack of efficient therapeutic strategies. New strategies focused on regulating adipose function with respect to AMP-activated protein kinase activation, NADPH oxidase function, and TGF-β may contribute to reducing adipose inflammation that may also provide renoprotection.

Interaction of thrombospondin1 and CD36 contributes to obesity-associated podocytopathy

Obesity is associated with podocyte injury and the development of proteinuria. Elevated plasma free fatty acid is one of the characteristics of obesity and has been linked to podocyte dysfunction. However, the mechanisms remain unclear. In the current study, we examined the effect of saturated free fatty acid (FFA) on human podocyte apoptosis and function in vitro. The mechanism and its in vivo relevance were also determined. We found that FFA treatment induced human podocyte apoptosis and dysfunction, which was associated with increased expression of a matricellular protein-thrombospondin1 (TSP1). FFA stimulated TSP1 expression in podocytes at the transcriptional levels through activation of MAPK pathway. Addition of purified TSP1 to cell culture media induced podocyte apoptosis and dysfunction. Tis effect is though a TGF-β independent mechanism. Moreover, peptide treatment to block TSP1 binding to its receptor-CD36 attenuated FFA induced podocyte apoptosis, suggesting that TSP1/CD36 interaction mediates FFA-induced podocyte apoptosis. Importantly, using a diet-induced obese mouse model, in vivo data demonstrated that obesity-associated podocyte apoptosis and dysfunction were attenuated in TSP1 deficient mice as well as in CD36 deficient mice. Taken together, these studies provide novel evidence that the interaction of TSP1 with its receptor CD36 contributes to obesity--associated podocytopathy.

The association of urine arsenic with prevalent and incident chronic kidney disease: evidence from the Strong Heart Study

BACKGROUND

Few studies have evaluated associations between low to moderate arsenic levels and chronic kidney disease (CKD). The objective was to evaluate the associations of inorganic arsenic exposure with prevalent and incident CKD in American Indian adults.

METHODS

We evaluated the associations of inorganic arsenic exposure with CKD in American Indians who participated in the Strong Heart Study in 3,851 adults ages 45-74 years in a cross-sectional analysis, and 3,119 adults with follow-up data in a prospective analysis. Inorganic arsenic, monomethylarsonate, and dimethylarsinate were measured in urine at baseline. CKD was defined as estimated glomerular filtration rate ≤ 60 ml/min/1.73 m, kidney transplant or dialysis.

RESULTS

CKD prevalence was 10.3%. The median (IQR) concentration of inorganic plus methylated arsenic species (total arsenic) in urine was 9.7 (5.8, 15.7) μg/L. The adjusted odds ratio (OR; 95% confidence interval) of prevalent CKD for an interquartile range in total arsenic was 0.7 (0.6, 0.8), mostly due to an inverse association with inorganic arsenic (OR: 0.4 [0.3, 0.4]). Monomethylarsonate and dimethylarsinate were positively associated with prevalent CKD after adjustment for inorganic arsenic (OR: 3.8 and 1.8). The adjusted hazard ratio of incident CKD for an IQR in sum of inorganic and methylated arsenic was 1.2 (1.03, 1.41). The corresponding HRs for inorganic arsenic, monomethylarsonate, and dimethylarsinate were 1.0 (0.9, 1.2), 1.2 (1.00, 1.3), and 1.2 (1.0, 1.4).

CONCLUSIONS

The inverse association of urine inorganic arsenic with prevalent CKD suggests that kidney disease affects excretion of inorganic arsenic. Arsenic species were positively associated with incident CKD. Studies with repeated measures are needed to further characterize the relation between arsenic and kidney disease development.

Obesity-induced hypertension: interaction of neurohumoral and renal mechanisms

Excess weight gain, especially when associated with increased visceral adiposity, is a major cause of hypertension, accounting for 65% to 75% of the risk for human primary (essential) hypertension. Increased renal tubular sodium reabsorption impairs pressure natriuresis and plays an important role in initiating obesity hypertension. The mediators of abnormal kidney function and increased blood pressure during development of obesity hypertension include (1) physical compression of the kidneys by fat in and around the kidneys, (2) activation of the renin-angiotensin-aldosterone system, and (3) increased sympathetic nervous system activity. Activation of the renin-angiotensin-aldosterone system is likely due, in part, to renal compression, as well as sympathetic nervous system activation. However, obesity also causes mineralocorticoid receptor activation independent of aldosterone or angiotensin II. The mechanisms for sympathetic nervous system activation in obesity have not been fully elucidated but may require leptin and activation of the brain melanocortin system. With prolonged obesity and development of target organ injury, especially renal injury, obesity-associated hypertension becomes more difficult to control, often requiring multiple antihypertensive drugs and treatment of other risk factors, including dyslipidemia, insulin resistance and diabetes mellitus, and inflammation. Unless effective antiobesity drugs are developed, the effect of obesity on hypertension and related cardiovascular, renal and metabolic disorders is likely to become even more important in the future as the prevalence of obesity continues to increase.

Prevalence and control of hypertension and albuminuria in South Korea: focus on obesity and abdominal obesity in the Korean National Health and Nutrition Examination Survey, 2011-2012

BACKGROUND

Albuminuria is associated with cardiovascular disease, and the relationship between albuminuria and hypertension is well established in many studies. So the control of hypertension is critical for decreasing cardiovascular events and albuminuria. Obesity and abdominal obesity are also associated with hypertension and albuminuria. Therefore, we analyzed the relationship between albuminuria and the prevalence and control of hypertension in the general Korean population according to obesity status.

METHODS

We analyzed data from the 2011-2012 Korea National Health and Nutrition Examination Survey, and 9,519 subjects were included. Subjects were divided into four groups: non-obese/normal waist circumference, non-obese/high waist circumference, obese/normal waist circumference, and obese/high waist circumference.

RESULTS

Systolic blood pressure and diastolic blood pressure were positively associated with albumin-creatinine ratio in all groups (all p values <0.005). Non-obese/normal waist circumference group were more likely to have hypertension (odds ratios [95% confidential intervals (CIs)] were 3.20 [2.21-4.63] in microalbuminuria level and 3.09 [1.05-9.14] in macroalbuminuria level), and less likely to have controlled hypertension (odds ratios <1 for both albuminuria levels) after adjusting for all covariates. Obese/normal waist circumference group were also more likely to have hypertension (odds ratio [95% CI] were 3.10 [1.56-6.15] in microalbuminuria level and 21.75 [3.66-129.04] in macroalbuminuria level), and less likely to have controlled hypertension in macroalbuminuria level (odds ratio [95% CI], 0.04 [0.01-0.15]).

CONCLUSIONS

Non-obese and normal waist circumference subjects have an increased prevalence and decreased control of hypertension in microalbuminuria and macroalbuminuria levels. Screening for albuminuria may provide helpful information about hypertension and blood pressure control, particularly in the non-obese and normal waist circumference subjects.

Obesity in kidney disease: A heavyweight opponent

Obesity is an important worldwide challenge that must be faced in most developed and developing countries because of unhealthy nutritional habits. The consequences of obesity and being overweight are observed in different organs, but the kidney is one of the most affected. Excess adipose tissue causes hemodynamic alterations in the kidney that can result in renal disease. However, obesity is also commonly associated with other comorbidities such as chronic inflammation, hypertension and diabetes. This association of several aggravating factors is still a matter of concern in clinical and basic research because the pathophysiologic mechanisms surrounding chronic kidney disease development in obese patients remain unclear. This review will discuss the consequences of obesity in the context of renal injury.

Body mass index as a predictor of complications and mortality after lumbar spine surgery

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

A national population-based database was analyzed to characterize the risks of postoperative complications and mortality associated with the patient's body mass index (BMI) after lumbar spinal surgery.

SUMMARY OF BACKGROUND DATA

Obesity has been associated with greater perioperative complications and worsened surgical outcomes after lumbar spinal surgery. However, the stratified BMI risks of postoperative complications relative to normal weight patients have not been well characterized.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database was queried to identify patients who underwent lumbar spinal surgery between 2006 and 2011. Patients were stratified into BMI cohorts: normal (18.5-24.99 kg/m), overweight (25.00-29.99 kg/m), class 1 (30.00-34.99 kg/m), class 2 (35.00-39.99 kg/m), and class 3 (≥40 kg/m) obesity. Preoperative patient characteristics and perioperative outcomes were assessed. The relative risks of 30-day postoperative complications and mortality for each BMI cohort were calculated in reference to the normal weight cohort using a 95% confidence interval.

RESULTS

A total of 24,196 patients underwent lumbar spine surgery between 2006 and 2011 of which 19,195 (79.3%) were overweight or obese. The risk for deep vein thrombosis increased beginning with overweight patients and compounded for the subsequent obesity classes. The risk for superficial wound infection and pulmonary embolism increased beginning with the class 1 obesity cohort. Furthermore, the relative risk increase for urinary tract infection, acute renal failure, and sepsis was significantly increased only among class 3 obesity patients. Lastly, there was no relative risk increase in 30-day mortality in any cohort after lumbar spine surgery.

CONCLUSION

Overweight and obese patients demonstrated an increased risk of postoperative complications relative to normal weight patients. Despite these findings, a BMI 25 kg/m or more was not associated with a greater risk of mortality. Further studies are warranted to characterize the impact of postoperative complications associated with overweight and obese patients on hospital resource utilization and costs after lumbar spine surgery.

Clinical challenges in diagnosis and management of diabetic kidney disease

Diabetic kidney disease (DKD) is a major and increasing worldwide public health issue. There is a great need for implementing treatments that either prevent or significantly slow the progression of DKD. Although there have been significant improvements in management, the increasing numbers of patients with DKD illustrate that current management is not wholly adequate. The reasons for suboptimal management include the lack of early diagnosis, lack of aggressive interventions, and lack of understanding about which interventions are most successful. There are a number of challenges and controversies regarding the current management of patients with DKD. Understanding of these issues is needed in order to provide the best care to patients with DKD. This article describes some of the clinically important challenges associated with DKD: the current epidemiology and cost burden and the role of biopsy in the diagnosis of DKD. Treatment controversies regarding current pharmacologic and nonpharmacologic approaches are reviewed and recommendations based on the published literature are made.

High glucose-induced O-GlcNAcylated carbohydrate response element-binding protein (ChREBP) mediates mesangial cell lipogenesis and fibrosis: the possible role in the development of diabetic nephropathy

Carbohydrate response element-binding protein (ChREBP) is a transcription factor responsible for carbohydrate metabolism in the liver. However, the role of ChREBP in diabetic nephropathy has not been elucidated. Thus, we investigated the role of ChREBP in mesangial cells in diabetic nephropathy. Treatment with 25 mM glucose (high glucose; HG) increased cellular O-GlcNAc and O-GlcNAcylated ChREBP in mesangial cells compared with normal 5.5 mM glucose. O-(2-acetamido-2-deoxy-D-glucopyranosylidene) amino N-phenylcarbamate (PUGNAc), a drug that increases O-GlcNAc, augmented the expression of ChREBP targets, whereas DON, a drug that decreases O-GlcNAc and O-GlcNAcase overexpression, mitigated the increase with HG. O-GlcNAc augmented the protein stability, transcriptional activity, and nuclear translocation of ChREBP. HG treatment also stimulated lipid accumulation and the contents of triglyceride and cholesterol in mesangial cells. In addition, HG triggered expression of hypoxia-inducible factor 1-α, vascular endothelial growth factor, and extracellular matrix components related to nephrosclerosis. The ChREBP mutant, W130A, did not exhibit HG-induced lipid accumulation and fibrotic proteins, suggesting that the Trp-130 residue in the MCR3 domain is important in the development of glomerulosclerosis. O-GlcNAcylated ChREBP was elevated in mesangium cells of streptozotocin-induced diabetic rats. In conclusion, HG increased the O-GlcNAcylated ChREBP level, which resulted in lipid accumulation and up-regulation of fibrotic proteins in mesangial cells. These effects may lead mesangial cells to an ultimately pathological state.

Effects of Toll-like receptor antagonist 4,5-dihydro-3-phenyl-5-isoxasole acetic acid on the progression of kidney disease in mice on a high-fat diet

BACKGROUND

Obesity-related metabolic disorders are closely associated with inflammation induced by innate immunity. Toll-like receptors (TLRs) play a pivotal role in the innate immune system by activating proinflammatory signaling pathways. GIT27 (4,5-dihydro-3-phenyl-5-isoxasole acetic acid) is an active immunomodulatory agent that primarily targets macrophages and inhibits secretion of tumor necrosis factor α [as well as interleukin (IL)-1β, IL-10, and interferon γ]. However, the effect of TLR antagonist on kidney diseases has rarely been reported. We investigated whether the TLR antagonist GIT27 has beneficial effects on the progression of kidney disease in obese mice on a high-fat diet (HFD).

METHODS

Six-week-old male C57BL/6 mice were divided into three groups: mice fed with normal chow diet (N=4); mice fed with a HFD (60% of total calories from fat, 5.5% from soybean oil, and 54.5% from lard, N=4); and GIT27-treated mice fed with a HFD (N=7).

RESULTS

Glucose intolerance, oxidative stress, and lipid abnormalities in HFD mice were improved by GIT27 treatment. In addition, GIT27 treatment decreased the urinary excretion of albumin and protein in obesity-related kidney disease, urinary oxidative stress markers, and inflammatory cytokine levels. This treatment inhibited the expression of proinflammatory cytokines in the kidneys and adipose tissue, and improved extracellular matrix expansion and tubulointerstitial fibrosis in obesity-related kidney disease.

CONCLUSION

TLR inhibition by administering GIT27 improved metabolic parameters. GIT27 ameliorates abnormalities of lipid metabolism and may have renoprotective effects on obesity-related kidney disease through its anti-inflammatory properties.

Delayed postoperative hyponatremia after transsphenoidal surgery: prevalence and associated factors

Object

Transient delayed postoperative hyponatremia (DPH) after transsphenoidal surgery (TSS) is common and can have potentially devastating consequences. However, the true prevalence of transient symptomatic and asymptomatic DPH has not been studied in a large patient cohort with close and accurate follow-up.

Methods

A retrospective analysis of a single-institution prospective database was conducted; all patients undergoing TSS for lesions involving the pituitary gland were followed up in a multidisciplinary neuroendocrine clinic, and demographic, imaging, and clinical data were prospectively collected. Patients were examined preoperatively and followed up postoperatively in a standardized fashion, and their postoperative sodium levels were measured at Weeks 1 and 2 postoperatively. Levels of hyponatremia were rated as mild (serum sodium concentration 130–134 mEq/L), moderate (125–129 mEq/L), or severe (< 125 mEq/L). Routine clinical questionnaires were administered at all postoperative office visits. Postoperative hyponatremia was analyzed for correlations with demographic and clinical features and with immediate postoperative physiological characteristics.

Results

Over a 4-year interval, 373 procedures were performed in 339 patients who underwent TSS for sellar and parasellar lesions involving the pituitary gland. The mean (± SD) age of patients was 48 ± 18 years; 61.3% of the patients were female and 46.1% were obese (defined as a body mass index [BMI] ≥ 30). The overall prevalence of DPH within the first 30 days postoperatively was 15.0%; 7.2% of the patients had mild, 3.8% moderate, and 3.8% severe hyponatremia. The incidence of symptomatic hyponatremia requiring hospitalization was 6.4%. The Fisher exact test detected a statistically significant association of DPH with female sex (p = 0.027) and a low BMI (p = 0.001). Spearman rank correlation detected a statistically significant association between BMI and nadir serum sodium concentration (r = 0.158, p = 0.002) and an inverse association for age (r = −0.113, p = 0.031). Multivariate analyses revealed a positive correlation between postoperative hyponatremia and a low BMI and a trend toward association with age; there were no associations between other preoperative demographic or perioperative risk factors, including immediate postoperative alterations in serum sodium concentration. Patients were treated with standardized protocols for hyponatremia, and DPH was not associated with permanent morbidity or mortality.

Conclusions

Delayed postoperative hyponatremia was a common result of TSS; a low BMI was the only clear predictor of which patients will develop DPH. Alterations in immediate postoperative sodium levels did not predict DPH. Therefore, an appropriate index of suspicion and close postoperative monitoring of serum sodium concentration should be maintained for these patients, and an appropriate treatment should be undertaken when hyponatremia is identified.

Abdominal obesity is associated with albuminuria in women: the 2011 Korea National Health and Nutrition Examination Survey

BACKGROUND

The effects of obesity on the kidney, apart from diabetes or hypertension, have not drawn much attention. Moreover, only a few studies have reported the relationship between obesity status and albuminuria in Asian countries, including South Korea. Therefore, this study aimed to investigate the association between obesity status and albuminuria in Korean adults.

METHODS

We analyzed data from the 2011 Korea National Health and Nutrition Examination Survey. Of the 4,979 subjects included in the general-population group, 3,274 were sorted into a nondiabetic and nonhypertensive population group. Obesity status was measured by body mass index and waist circumference. Albuminuria was defined as a urine albumin-to-creatinine ratio ≥30 mg/g.

RESULTS

Abdominally obese women were at higher risk for albuminuria than were women without abdominal obesity both in the general population (odds ratio [OR], 95% confidence interval [CI]: 2.08 [1.04-4.16]) and in the nondiabetic and nonhypertensive population (OR [95% CI]: 6.96 [2.34-20.64]) after further adjustment for confounders. Among generally nonobese women, abdominally obese women were at higher risk for albuminuria than were women without abdominal obesity both in the general population (OR [95% CI]: 2.82 [1.51-5.29]) and in the nondiabetic and nonhypertensive population (OR [95% CI]: 5.32 [1.47-19.22]).

CONCLUSION

Abdominal obesity is associated with an increased risk for albuminuria in Korean women, independently of diabetes or hypertension. Screening for abdominal obesity, especially in women, may therefore provide earlier identification of individuals at risk for developing renal disease and cardiovascular disease, even those who are nondiabetic and nonhypertensive.

Plasma adiponectin level is inversely correlated with albuminuria in overweight and obese nondiabetic individuals

OBJECTIVE

To explore the relationship between adiponectin and albuminuria in a large group of overweight and obese nondiabetic individuals after controlling for potential confounders.

MATERIAL AND METHODS

Detailed anthropometry, computed tomography-measured visceral abdominal adipose tissue, 24-h albuminuria, adiponectin and a series of biochemical parameters were assessed. Four hundred forty patients, predominantly of Caucasian origin, were included (80.2% female). A multiple linear regression model was developed, with albuminuria as the dependent variable and potential predictors as independent variables.

RESULTS

The mean age was 40±13 years, the mean body mass index was 35.7±6.6 kg/m2, and the median visceral abdominal adipose tissue was 142.4 (92.3-194.0) cm2. 10.9% of subjects exhibited microalbuminuria. The median adiponectin level was 9.08 (6.23-12.94) μg/ml, and the median fasting serum glucose level was 83 (77-89) mg/dl. The strongest significant univariate correlations with albuminuria were visceral abdominal adipose tissue (r=0.258, p<0.001), adiponectin (r=-0.265, p<0.001), waist circumference (r=0.250, p<0.001), waist-to-hip ratio (r=0.236, p<0.001) and high-density lipoprotein cholesterol (r=-0.211, p<0.001). The multiple linear regression model revealed a significant positive independent correlation between visceral abdominal adipose tissue and albuminuria (r=0.134, p=0.033), between fasting glucose levels and albuminuria (r=0.390, p=0.029) and between gender and albuminuria (r=0.107, p=0.038). A significant independent negative correlation was identified between adiponectin and albuminuria (r=-0.255, p=0.022).

CONCLUSIONS

We observed an independent inverse relationship between adiponectin and albuminuria in overweight and obese nondiabetic individuals. Further investigations are needed to confirm this finding and to clarify whether adiponectin is a risk marker or plays a causative role in developing obesity-induced nephropathy.

Obese locus in WNIN/obese rat maps on chromosome 5 upstream of leptin receptor

WNIN/Obese (WNIN/Ob) rat a new mutant model of metabolic syndrome was identified in 1996 from an inbred Wistar rat strain, WNIN. So far several papers are published on this model highlighting its physical, biochemical and metabolic traits. WNIN/Ob is leptin resistant with unaltered leptin or its receptor coding sequences - the two well-known candidate genes for obesity. Genotyping analysis of F₂ progeny (raised from WNIN/Ob × Fisher - 344) in the present study localized the mutation to a recombinant region of 14.15cM on chromosome 5. This was further corroborated by QTL analysis for body weight, which narrowed this region to 4.43 cM with flanking markers D5Rat256 & D5Wox37. Interval mapping of body weight QTL shows that the LOD score peak maps upstream of leptin receptor and shows an additive effect suggesting this as a novel mutation and signifying the model as a valuable resource for studies on obesity and metabolic syndrome.