Engineering 3D Printed Microfluidic Chips for the Fabrication of Nanomedicines.

Currently, there is an unmet need to manufacture nanomedicines in a continuous and controlled manner. Three-dimensional (3D) printed microfluidic chips are an alternative to conventional PDMS chips as they can be easily designed and manufactured to allow for customized designs that are able to reproducibly manufacture nanomedicines at an affordable cost. The manufacturing of microfluidic chips using existing 3D printing technologies remains very challenging because of the intricate geometry of the channels. Here, we demonstrate the manufacture and characterization of nifedipine (NFD) polymeric nanoparticles based on Eudragit L-100 using 3D printed microfluidic chips with 1 mm diameter channels produced with two 3D printing techniques that are widely available, stereolithography (SLA) and fuse deposition modeling (FDM). Fabricated polymeric nanoparticles showed good encapsulation efficiencies and particle sizes in the range of 50-100 nm. SLA chips possessed better channel resolution and smoother channel surfaces, leading to smaller particle sizes similar to those obtained by conventional manufacturing methods based on solvent evaporation, while SLA manufactured nanoparticles showed a minimal burst effect in acid media compared to nanoparticles fabricated with FDM chips. Three-dimensional printed microfluidic chips are a novel and easily amenable cost-effective strategy to allow for customization of the design process for continuous manufacture of nanomedicines under controlled conditions, enabling easy scale-up and reducing nanomedicine development times, while maintaining high-quality standards.

Increased cerebral water content in hemodialysis patients.

Little information is available on the impact of hemodialysis on cerebral water homeostasis and its distribution in chronic kidney disease. We used a neuropsychological test battery, structural magnetic resonance imaging (MRI) and a novel technique for quantitative measurement of localized water content using 3T MRI to investigate ten hemodialysis patients (HD) on a dialysis-free day and after hemodialysis (2.4±2.2 hours), and a matched healthy control group with the same time interval. Neuropsychological testing revealed mainly attentional and executive cognitive dysfunction in HD. Voxel-based-morphometry showed only marginal alterations in the right inferior medial temporal lobe white matter in HD compared to controls. Marked increases in global brain water content were found in the white matter, specifically in parietal areas, in HD patients compared to controls. Although the global water content in the gray matter did not differ between the two groups, regional increases of brain water content in particular in parieto-temporal gray matter areas were observed in HD patients. No relevant brain hydration changes were revealed before and after hemodialysis. Whereas longer duration of dialysis vintage was associated with increased water content in parieto-temporal-occipital regions, lower intradialytic weight changes were negatively correlated with brain water content in these areas in HD patients. Worse cognitive performance on an attention task correlated with increased hydration in frontal white matter. In conclusion, long-term HD is associated with altered brain tissue water homeostasis mainly in parietal white matter regions, whereas the attentional domain in the cognitive dysfunction profile in HD could be linked to increased frontal white matter water content.

The Montreal Cognitive Assessment (MoCA) - a sensitive screening instrument for detecting cognitive impairment in chronic hemodialysis patients.

BACKGROUND: Chronic kidney disease (CKD) patients undergoing hemodialysis (HD) therapy have an increased risk of developing cognitive impairment and dementia, which are known relevant factors in disease prognosis and therapeutic success, but still lack adequate screening in clinical routine. We evaluated the Montreal Cognitive Assessment (MoCA) for suitability in assessing cognitive performance in HD patients in comparison to the commonly used Mini-Mental State Examination (MMSE) and a detailed neuropsychological test battery, used as gold standard. METHODS: 43 HD patients and 42 healthy controls with an average age of 58 years, were assessed with the MoCA, the MMSE and a detailed neuropsychological test battery, covering the domains of memory, attention, language, visuospatial and executive functions. Composite scores were created for comparison of cognitive domains and test results were analyzed using Spearman's correlation and linear regression. Cognitive dysfunction was defined using z-score values and predictive values were calculated. Sensitivity and specificity of the MoCA were determined using receiver operating characteristic (ROC) analysis. RESULTS: HD patients performed worse in all cognitive domains, especially in memory recall and executive functions. The MoCA correlated well with the detailed test battery and identified patients with cognitive impairment with a sensitivity of 76.7% and specificity of 78.6% for a cut-off value of ≤24 out of 30 points. In the detailed assessment executive functions accounted significantly for performance in the MoCA. The MMSE only discriminated weakly between groups. CONCLUSIONS: The MoCA represents a suitable cognitive screening tool for hemodialysis patients, demonstrating good sensitivity and specificity levels, and covering executive functions, which appear to play an important role in cognitive performance of HD patients.

Clinical predictors of individual cognitive fluctuations in patients undergoing hemodialysis.

BACKGROUND: Cognitive impairment in hemodialysis (HD) patients is frequent and mediated by several factors. It is unclear which patients are more susceptible to cognitive variations around the dialysis cycle and which clinical factors may play a mediator role. We aimed to answer these issues by investigating intraindividual changes within the dialysis cycle. STUDY DESIGN: Cross-sectional observational study with repeated measures. SETTING & PARTICIPANTS: 47 HD patients and 40 controls without kidney disease, both without history of neurologic disease. PREDICTORS: Dialysis vintage, disease duration, vascular risk factors, comorbidity index score, intradialytic weight change, frequency of hypotensive episodes, and biochemical levels (hemoglobin, leukocytes, urea, creatinine, sodium, and potassium). Covariates included demographics (age, education, and sex). OUTCOMES & MEASUREMENTS: Significant individual deterioration in attention and executive functions (phasic and intrinsic alertness, Stroop test, and Trail Making Test) after dialysis, as measured by a regression-based reliable change method. Regression models were used to identify clinical predictors of individual cognitive decline after dialysis. RESULTS: After dialysis, patients primarily showed prolonged reaction times and psychomotor slowing. However, individual-based analyses revealed that fluctuations in attention and executive functions were present in only a minority of patients. Significant individual fluctuations on particular attention and executive tasks were associated moderately with intradialytic hypotensive episodes, as well as with psychoactive medication, and were predicted weakly by blood leukocyte count, sodium level, dialysis vintage, and volume. LIMITATIONS: Small sample size; patient group younger and healthier than the overall HD population, limiting generalizability. CONCLUSIONS: Only a minority of patients exhibit significant individual cognitive fluctuations, predominantly showing deterioration after dialysis in attention and executive functions. Susceptibility to such fluctuations was predicted in part by both HD-dependent and -independent factors.

The quest for a model of type II diabetes with nephropathy: the Goto Kakizaki rat.

The Goto Kakakizaki (GK) rat is a moderately diabetic rat strain that was developed by repeated inbreeding of glucose-intolerant Wistar rats over several generations. In contrast to many other rodent models of non-insulin-dependent diabetes, GK rats do not exhibit hyperlipidemia or obesity. Hyperglycemia in the GK rat is associated with the development of age-dependent renal structural changes that are similar to those described in patients with prolonged non-insulin-dependent diabetes mellitus who have not developed overt renal disease. Hyperglycemia in the GK rat is, however, not associated with overt proteinuria or progressive nephropathy. In the present review the metabolic characteristics as well as renal and nonrenal changes observed in GK rats are described. Moreover the effects on renal function and morphology of secondary injurious stimuli, such as mesangioproliferative glomerulonephritis and hypertension, superimposed on type II diabetes in GK rats are discussed.

Hypertension superimposed on type II diabetes in Goto Kakizaki rats induces progressive nephropathy.

BACKGROUND: Type II diabetes in the Goto Kakizaki (GK) rats (derived from Wistar rats) is not associated with the development of obesity, hyperlipidemia, hypertension, or pronounced renal functional changes. The aim of this study was to investigate the effect of superimposed hypertension on renal function and morphology under conditions of hyper- and normoglycemia. METHODS: The evolution of biochemical and morphologic renal changes was examined in GK and Wistar rats treated with deoxycorticosterone acetate (DOCA) salt over 24 weeks. RESULTS: Blood pressure was increased from 6 weeks on in GK and Wistar rats with no difference in blood pressure levels between both groups (week 24, 183 +/- 14 mm Hg vs. 191 +/- 13 mm Hg, P = NS, vs. 144 +/- 6 mm Hg in normal controls, P < 0.01). A progressive increase in proteinuria was observed in hypertensive GK rats from 12 weeks on (week 24, 168 +/- 62 mg/day vs. 41 +/- 30 mg/day in hypertensive Wistar rats, P = 0.002). Histologic analysis at weeks 15 and 24 showed progressive glomerulosclerosis in hypertensive GK and Wistar rats (week 24, 13 +/- 4% vs. 8 +/- 1%, P = NS) but not in nonhypertensive GK controls. This was associated with evidence of podocyte damage (de novo desmin expression) in hypertensive as compared to nonhypertensive GK rats (week 24, score 1.4 +/- 0.1 vs. 0.8 +/- 0.1, P < 0.001) while no significant increase was observed in hypertensive vs. nonhypertensive Wistar rats. Tubulointerstitial damage was increased in hypertensive GK as compared to hypertensive Wistar rats (week 24, score 1.5 +/- 0.6 vs. 0.6 +/- 0.3, P = 0.01). By immunohistochemistry, this was associated with an up-regulation of tubulointerstitial type IV collagen as well as alpha-smooth muscle actin (alpha-SMA) expression, macrophage infiltration and cell proliferation in hypertensive GK rats. CONCLUSION: Our data demonstrate that long-standing type II diabetes alone is not sufficient to induce progressive nephropathy unless secondary injurious mechanisms such as hypertension are present. The hypertensive GK rat provides a novel model to investigate the mechanisms involved in diabetic nephropathy.