Tubular Membrane Research Articles

CO2 capture using superhydrophobic ceramic membrane: Preparation and performance analysis

The application of membrane absorption for CO2 capture has been limited by membrane wetting. In this paper, tubular Al2O3 ceramic membranes (marked as M1 and M2) are hydrophobically modified by sol-gel and dip-coating method and then used for CO2 capture. The surface morphology, surface composition, wettability and flux are characterized in detail. The mass transfer performance of M1 and M2 is studied at different gas and liquid Reynolds numbers. After modification, the surface contact angle can reach as high as 170.7°. The carbon capture performance of the modified M1 and M2 is significantly improved. Under laminar flow condition, CO2 mass transfer coefficient increased from the initial 1.03 × 10−4 m/s to 14.59 × 10−4 m/s, and the CO2 capture efficiency increased from the initial 28.55%–98.55%. The mass transfer resistance of ceramic membrane contactor is also analyzed. The resistance of liquid phase plays a leading role in the mass transfer performance in laminar flow state. For non-wetting membrane, membrane thickness has little effect on the mass transfer performance. In addition, it is shown that the superhydrophobic M1 and M2 exhibit excellent corrosion resistance. The research in this paper shows that superhydrophobic ceramic membrane is more suitable for CO2 capture in industrial production.

Tubular basement membrane deposits after allogeneic hematopoietic stem cell transplantation

BackgroundExtraglomerular immune complex deposition is rare and only a few membranous nephropathy cases with tubular basement membrane deposits have been reported following allogeneic hematopoietic stem cell transplantation.Case presentationWe reported a 56-year-old man with increased serum creatinine after allogeneic hematopoietic stem cell transplantation who underwent a renal biopsy. Tubular interstitial nephritis was identified on light microscope. The unique histologic features were diffuse tubular basement membrane immune complex deposition detected by both immunofluorescence and electron microscopy, while the glomerular involvement was inconspicuous. The differential diagnosis from other forms of tubular basement membrane deposition is discussed.ConclusionDiffuse granular tubular basement membrane immune complex deposition with minimal glomerular involvement is also a manifestation of renal complication in hematopoietic stem cell transplantation recipient. However, the exact mechanism and target antigen remains unknown.

Thermo-economic and performance analysis of a novel tubular hybrid high-temperature proton exchange membrane fuel cell and thermoelectric generator

This paper proposes a novel tubular design for a hybrid high-temperature proton exchange membrane fuel cell (HT-PEMFC) and thermoelectric generator (TEG) system. The wasted heat from the fuel cell is captured by a thermoelectric generator to generate more electricity. Hence, the primary objective of the research is to determine the waste heat recovery performance of the TEG for thermal management of the tubular HT-PEMFC. A validated 3D numerical approach was employed to evaluate the performance of the tubular hybrid system with a tubular TEG integrated into the HT-PEMFC. A parametric study evaluates the impact of various TEG geometrical configurations and operational parameters on the system's performance. The results indicate that boosting the cell voltage improves the fuel cell efficiency, while decreasing the thermoelectric sizing has a notable impact on the TEG's performance. The TEG's conversion efficiency and output power are significantly impacted by changes in the angle ratio and the temperature of the cold side. Increasing the inlet temperature has a positive impact on thermoelectric power generation but leads to a reduction in fuel cell power and efficiency. Overall, the study highlights the importance of optimizing the operating conditions of hybrid tubular HT-PEMFC/TEG to achieve optimal performance and provides valuable insights for the design and development of hybrid energy systems that can potentially contribute to meet the increasing demand for sustainable energy solutions.

Slug flow in tubular membrane in which air and activated sludge flow: A CFD study

Air bubbles have been widely applied to alleviate membrane fouling of tubular membranes in membrane bioreactors. However, the impact of the air bubbles on the flow at the membrane surface as well as the removal of membrane foulant are not well understood. Therefore, a theoretical computational fluid dynamics model was established to address this. In the model, air and activated sludge flowed at the superficial velocities of 0.7 m/s and 0.3 m/s, respectively. Furthermore, sludge concentrations were 5 g/L and 10 g/L, respectively. The model showed that the activated sludge did not flow downwards in the film zone and eddies were not observed in the zone below the tail of a bubble. The viscosity of sludge varied significantly in the film zone. Mass transfer capacities at membrane surface gradually decreased from the nose to the end of a bubble. Moreover, a lower sludge concentration resulted in a higher mass transfer capacity. The highest shear stress at membrane surface was 14 and 11 Pa, which were significantly higher than the shear stress achieved in submerged membranes being aerated. Microparticles (3–10 µm) at membrane surface could be shifted towards the filtrated bulk solution and sucked at the membrane surface alternatively when a gas slug flowed nearby. Furthermore, the bubbles are not effective in shifting microparticles (<3 µm) toward a bulk solution.

Production of retroviral vectors in continuous high cell density culture

Retroviral vectors derived from murine leukemia virus (MLV) are used in somatic gene therapy applications e.g. for genetic modification of hematopoietic stem cells. Recently, we reported on the establishment of a suspension viral packaging cell line (VPC) for the production of MLV vectors. Human embryonic kidney 293-F (HEK293-F) cells were genetically modified for this purpose using transposon vector technology. Here, we demonstrate the establishment of a continuous high cell density (HCD) process using this cell line. First, we compared different media regarding the maximum achievable viable cell concentration (VCC) in small scale. Next, we transferred this process to a stirred tank bioreactor before we applied intensification strategies. Specifically, we established a perfusion process using an alternating tangential flow filtration system. Here, VCCs up to 27.4E + 06 cells/mL and MLV vector titers up to 8.6E + 06 transducing units/mL were achieved. Finally, we established a continuous HCD process using a tubular membrane for cell retention and continuous viral vector harvesting. Here, the space-time yield was 18-fold higher compared to the respective batch cultivations. Overall, our results clearly demonstrate the feasibility of HCD cultivations for high yield production of viral vectors, especially when combined with continuous viral vector harvesting.Key points• A continuous high cell density process for MLV vector production was established• The tubular cell retention membrane allowed for continuous vector harvesting• The established process had a 18-fold higher space time yield compared to a batch

Reusability of Discarded Tubular Ceramic Membranes for CO2 Removal: A Case Study for Membrane Circularity.

Discarded polymeric or ceramic membranes are currently in need of appropriate and sustainable management. In the present study, the direct reuse of discarded ceramic membranes in membrane contactor (MC) systems for CO2 removal was investigated for the first time. The hydrophobic surface modification of the discarded ceramic membrane was done by using macromolecule additive coating. The influence of operational parameters (absorbent liquid flow rate (QL), feed gas flow rate (Qg), and different NaOH concentrations) of the MC on CO2 removal was investigated to prove the technical feasibility of reused ceramic membranes. The CO2 absorption flux was 7.9 × 10-4 mol/m2 s at optimal conditions of 2 M NaOH, QL (20 mL/min), and Qg (300 mL/min) with a removal efficiency of 98%, which lasted for 8 h. This study demonstrates a potential alternative for the reuse of discarded ceramic membranes and avoids their disposal in landfills. The proposed approach will also bring membrane technology into the circular economy and achieve sustainability goals by reducing the amount of waste from discarded ceramic membranes in the future and combating global warming by absorbing CO2.

Development of integrated volatile organic compound purification system using tubular NaA zeolite membrane: Experimental and theoretical insights into vapor permeation and pervaporation process

This study experimentally and theoretically investigated the dehydration performance of vapor permeation (VP) and pervaporation (PV) processes using tubular NaA zeolite membranes. The effects of the key operating conditions (e.g., feed flow rate, concentration, temperature, and permeate pressure) on the dehydration performance of each process were experimentally investigated using a binary mixture of isopropanol and water. In addition, detailed mathematical models were developed to investigate the separation behavior in the VP and PV processes. The prediction results were validated using experimental results from the VP and PV processes (relative error < 5%). Additionally, based on the developed VP and PV processes, an integrated system for the purification of volatile organic compounds (VOCs) was proposed and evaluated. The integrated VOCs purification system consisted of a two-stage VP process (once-through mode) and single-stage PV process (recycling mode). The isopropanol from the binary mixture (74 wt% isopropanol and 26 wt% water) was recovered at a rate of 99.9% via the two-stage VP process, with an isopropanol concentration of 96.67%. Moreover, the isopropanol recovered from the VP process was upgraded to 99.23 wt% via the PV process. The simulation results showed that the integrated system obtained isopropanol with a concentration of 99.97 wt% with a recovery of 97.10% from the binary VOCs mixture.; this was in good agreement with the experimental results (relative error < 3%).

Compact tubular carbon-based membrane bioreactors for the anaerobic decolorization of azo dyes

This research investigates a highly efficient compact tubular ceramic-supported carbon-based membrane reactor integrated with anaerobic biodegradation to decolorize the azo dyes. Two carbon-based membranes, produced using Matrimid 5218 polyimide and graphene oxide solutions, are evaluated for the comparative color removal of three structurally different azo dyes, Acid Orange 7 (AO7), Reactive Black 5 (RB5), and Direct Blue 71 (DB71). Based on FESEM microscopic images, the average pore size of the tubular ceramic-supported carbonized membrane (TCSCM) was approximately 25 nm, while for the tubular ceramic-supported graphene oxide membrane (TCSGOM), it was 12 nm. Additionally, TCSCM had a thinner layer at only 1.10 µm, while TCSGOM was slightly thicker at 2.11 µm. These features influenced the permeate flux of the membrane, in which the TCSGOM exhibited lower permeate flux (18.2 L·m−2·h−1) than the TCSCM (45.6 L·m−2·h−1). However, the anaerobic decolorization results indicated that the TCSGOM bioreactor (B-TCSGOM) was more efficient and effective at removing color from all dye solutions than the TCSCM bioreactor (B-TCSCM) over a wide range of feed concentrations. In both reactors, the highest decolorization was achieved at low feed concentration (50 mg·L−1), and removal was 94 % for AO7, 90 % for RB5, and 88 % for DB71 in B-TCSGOM, whereas 88 %, 85 %, and 69 %, respectively, in B-TCSCM. These suggest that the robust conductive nanoporous surface of B-TCSGOM makes it more effective at removing different azo dye solutions from wastewater.

Peptide location fingerprinting identifies structural alterations within basement membrane components in ageing kidney

During ageing, the glomerular and tubular basement membranes (BM) of the kidney undergo a progressive decline in function that is underpinned by histological changes, including glomerulosclerosis and tubular interstitial fibrosis and atrophy. This BM-specific ageing is thought to result from damage accumulation to long-lived extracellular matrix (ECM) protein structures. Determining which BM proteins are susceptible to these structure-associated changes, and the possible mechanisms and downstream consequences, is critical to understand age-related kidney degeneration and to identify markers for therapeutic intervention. Peptide location fingerprinting (PLF) is an emerging proteomic mass spectrometry analysis technique capable of identifying ECM proteins with structure-associated differences that may occur by damage modifications in ageing. Here, we apply PLF as a bioinformatic screening tool to identify BM proteins with structure-associated differences between young and aged human glomerular and tubulointerstitial compartments. Several functional regions within key BM components displayed alterations in tryptic peptide yield, reflecting potential age-dependent shifts in molecular (e.g. laminin-binding regions in agrin) and cellular (e.g. integrin-binding regions in laminins 521 and 511) interactions, oxidation (e.g. collagen IV) and the fragmentation and release of matrikines (e.g. canstatin and endostatin from collagens IV and XVIII). Furthermore, we found that periostin and the collagen IV α2 chain exhibited structure-associated differences in ageing that were conserved between human kidney and previously analysed mouse lung, revealing BM components that harbour shared susceptibilities across species and organs.

Protective effects of melatonin against oxidative stress induced by metabolic disorders in the male reproductive system: a systematic review and meta-analysis of rodent models.

Male infertility is a multifaceted issue that has gained scientific interest due to its increasing rate. Studies have demonstrated that oxidative stress is involved in male infertility development. Furthermore, metabolic disorders, including obesity, diabetes, hypo- and hyperthyroidism, are risk factors for male infertility, and oxidative stress is believed to contribute to this association. Melatonin, functioning as an oxidative scavenger, may represent a promising therapeutic approach for the prevention and treatment of metabolic disorder-associated male infertility. We systematically searched three online databases (PubMed, Scopus, and Web of Science) for studies that evaluated the effects of melatonin therapy on metabolic disorders-induce infertility in male rodents. The favorable outcomes were histopathological parameters of testicular tissue, reproductive hormones, and markers of oxidative stress. Then, meta-analyses were done for each outcome. The results are reported as standardized mean difference (Cohen's d) and 95% confidence interval. 24 studies with 31 outcomes were included. Rats and mice were the subjects. Studies have employed obesity, diabetes, hypothyroidism, hyperthyroidism, hyperlipidemia, and food deprivation as metabolic disorders. To induce these disorders, a high-fat diet, high-fructose diet, leptin, streptozotocin, alloxan, carbimazole, and levothyroxine were used. The outcomes included histopathologic characteristics (abnormal sperm morphology, apoptotic cells, apoptotic index, Johnsen's testicular biopsy score, seminiferous epithelial height, tubular basement membrane thickness, tubular diameter, sperm count, and motility), weight-related measurements (absolute epididymis, testis, and body weight, body weight gain, epididymal adipose tissue weight, and relative testis to body weight), hormonal characteristics (androgen receptor expression, serum FSH, LH, and testosterone level), markers of oxidative stress (tissue and serum GPx and MDA activity, tissue CAT, GSH, and SOD activity), and exploratory outcomes (serum HDL, LDL, total cholesterol, triglyceride, and blood glucose level). The overall pooled effect sizes were statistically significant for all histopathological characteristics and some markers of oxidative stress. Melatonin can reduce damage to male rodents' gonadal tissue and improve sperm count, motility, and morphology in metabolic diseases. Future clinical studies and randomized controlled trials are needed to evaluate the safety and effectiveness of melatonin for male infertility in patients with metabolic diseases.

Force dipole interactions in tubular fluid membranes

We construct viscous fluid flow sourced by a force dipole embedded in a cylindrical fluid membrane, coupled to external embedding fluids. We find analytic expressions for the flow in the limit of infinitely long and thin tubular membranes. We utilize this solution to formulate the in-plane dynamics of a pair of pusher-type dipoles along the cylinder surface. We find that a mutually perpendicular dipole pair generically moves together along helical geodesics. Since the cylindrical geometry breaks the in-plane rotational symmetry of the membrane, there is a difference in flows along the axial (ẑ) and transverse (θ̂) directions of the cylinder. This in turn leads to anisotropic hydrodynamic interaction between the dipoles and is remarkably different from flat and spherical fluid membranes. In particular, the flow along the compact θ̂ direction of the cylinder has a local rigid rotation term (independent of the angular coordinate but decays along the axis of the cylinder). Due to this feature of the flow, we observe that the interacting dipole pair initially situated along the axial direction ẑ exhibits an overall “drift” along the compact angular direction θ̂ of the tubular fluid membrane. We find that the drift for the dipole pair increases linearly with time. Our results are relevant for non-equilibrium dynamics of motor proteins in tubular membranes arising in nature, as well as in vitro experiments.

Design and Calculation of an Effective Tubular Electric Membrane Apparatus with an Increased Membrane Area for Separating Process Solutions

Design and Calculation of an Effective Tubular Electric Membrane Apparatus with an Increased Membrane Area for Separating Process Solutions

Model of membrane deformations driven by a surface pH gradient.

Many cellular organelles are membrane-bound structures with complex membrane composition and shape. Their shapes have been observed to depend on the metabolic state of the organelle and the mechanisms that couple biochemical pathways and membrane shape are still actively investigated. Here, we study a model coupling inhomogeneities in the lipid composition and membrane geometry via a generalized Helfrich free energy. We derive the resulting stress tensor, the Green's function for a tubular membrane, and compute the phase diagram of the induced deformations. We then apply this model to study the deformation of mitochondria cristae described as membrane tubes supporting a pH gradient at its surface. This gradient in turn controls the lipid composition of the membrane via the protonation or deprotonation of cardiolipins, which are acid-based lipids known to be crucial for mitochondria shape and functioning. Our model predicts the appearance of tube deformations resembling the observed shape changes of cristea when submitted to a proton gradient.

New Onset Nephrotic - Range Proteinuria in a Patient with Chronic Kidney Disease - Not Always What it Seems

Light chain deposition disease (LCDD) is a rare condition that is characterized by the deposition of monoclonal immunoglobulin light chains in glomerular and tubular basement membranes. We report the case of a 72-year-old male with long-standing and stable chronic kidney disease (CKD) presumably due to hypertension.

Development of Membrane Reactor Coupling Hydrogen and Syngas Production.

Simultaneous syngas and pure hydrogen production through partial oxidation of methane and water splitting, respectively, were demonstrated by using mixed ionic-electronic conductors. Tubular ceramic membranes prepared from La0.5Sr0.5FeO3 perovskite were successfully utilized in a 10 M lab scale reactor by applying a radial arrangement. The supply of methane to the middle area of the reaction zone was shown to provide a uniform distribution of the chemical load along the tubes' length. A steady flow of steam feeding the inner part of the membranes was used as oxidative media. A described configuration was found to be favorable to maintaining oxygen permeability values exceeding 1.1 mL∙cm-2∙min-1 and long-term stability of related functional characteristics. Methane's partial oxidation reaction assisted by 10%Ni@Al2O3 catalyst proceeded with selectivity values above 90% and conversion of almost 100%. The transition from a laboratory model of a reactor operating on one tubular membrane to a ten-tube one resulted in no losses in the specific performance. The optimized supply of gaseous fuel opens up the possibility of scaling up the reaction zone and creating a promising prototype of a multitubular reaction zone with a simplified sealing procedure.

Vascular, valvular and kidney calcification manifested in mouse models of adenine-induced chronic kidney disease

Background Ectopic calcification (EC) involves multiple organ systems in chronic kidney disease (CKD). Previous CKD-animal models primarily focused on a certain histological abnormality but did not show the correlation with calcified development among various tissues. This study compared calcified deposition in various tissues during CKD progression in mice. Methods Male 8-week-old C57BL/6J mice were randomly allocated to the seven groups: a basic, adenine, high-phosphorus, or adenine and high-phosphorus diet for 12–16 weeks (Ctl16, A12, P16, or AP16, respectively); an adenine diet for 4–6 weeks; and a high-phosphorus or adenine and high-phosphorus diet for 10–12 weeks (A6 + P10, A4 + P12, or A4 + AP12, respectively). Results Compared to the Ctl16 mice, the P16 mice only displayed a slight abnormality in serum calcium and phosphorus; the A12 mice had the most serious kidney impairment; the A4 + P12 and A6 + P10 mice had similar conditions of CKD, mineral abnormalities, and mild calcification in the kidney and aortic valves; the A4 + AP12 and AP16 groups had severe kidney impairment, mineral abnormalities and calcification in the kidneys, aortic valves and aortas. Furthermore, calcium-phosphate particles were deposited not only in the tubulointerstitial compartment but in the glomerular and tubular basement membrane. The elemental composition of EC in various tissues matched the calcification of human cardiovascular tissue as determined by energy dispersive spectroscopy. Conclusions The severity of CKD was unparalleled with the progression of mineral metabolism disorder and EC. Calcification was closely related in different tissues and observed in the glomerular and tubular basement membranes.

An indigenous tubular ceramic membrane integrated bioreactor system for biodegradation of phthalates mixture from contaminated wastewater.

Endocrine-disrupting phthalates (EDPs) are widely used as plasticizers for the manufacture of different plastics and polyvinyl chloride by providing flexibility and mechanical strength. On the other hand, they are categorized under priority pollutants list due to their threat to human health and the environment. This study examined biodegradation of a mixture of dimethyl, diethyl, dibutyl, benzyl butyl, di-2-ethylhexyl, and di-n-octyl phthalates using a CSTB (continuous stirred tank bioreactor) operated under batch, fed-batch, continuous, and continuous with biomass recycle operation modes. For operating the CSTB under biomass recycle mode, microfiltration using an indigenous tubular ceramic membrane was employed. Ecotoxicity assessment of the treated water was carried out to evaluate the toxicity removal efficiency by the integrated bioreactor system. From the batch experiments, the EDPs cumulative degradation values were 90 and 75% at 1250 and 1500mg/L total initial concentration of the mixture, respectively, whereas complete degradation was achieved at 750mg/L. In the fed-batch study, 93% degradation was achieved at 1500mg/L total initial concentration of the mixture. In continuous operation mode, 94 and 85% degradation efficiency values were achieved at 43.72 and 52.08mg/L⋅h inlet loading rate of phthalate mixture. However, continuous feeding with 100% biomass recycle revealed complete degradation at 41.67mg/L⋅h inlet loading rate within the 84h operation period. High seed germination index and low mortality percentage of brine shrimps observed with phthalate degraded water from the integrated bioreactor system revealed its excellent potential in the treatment and toxicity removal of phthalates contaminated environment.

Scalable production of chitosan sub-micron particles by membrane ionotropic gelation process

Ionotropic gelation (IG) is a highly attractive method for the synthesis of natural water-soluble polymeric nanoparticles (NPs) and sub-micron particles (sMP) due to its relatively simple procedure and the absence of organic solvents. The method involves the electrostatic interaction between two ionic species of opposite charge. Although it is well studied at the laboratory scale, the difficulty to achieve size control in conventional bench-top process is actually a critical aspect of the technology. The aim of this work is to study the membrane dispersion technology in combination with IG as a suitable scalable method for the production of chitosan sub-micron particles (CS-sMPs).The two phases, one containing chitosan (CS) and the other containing sodium tripolyphosphate (TPP), were put in contact using a tubular hydrophobic glass membrane with a pore diameter of 1 μm. TPP (dispersed phase) was permeated through the membrane pores into the lumen side along which the CS solution (the continuous phase) flowed in batch recirculation or continuous single-pass operation mode. The influence of chemical variables (i.e. pH, concentration and mass ratio of polyelectrolyte species, emulsifier) and fluid-dynamic parameters (i.e. polyelectrolyte solution flow rate and their relative mass ratio) was studied to precisely tune the size of CS-Ps.

MgO-Al2O3-SiO2- ZrO2 system ceramic glass as sintering aids to fabricate Al2O3 ceramic membrane with high acid corrosion resistance

The shortcoming of ceramic membranes is the high cost caused by high sintering temperatures. Sintering aids can be chosen to reduce the sintering temperature. However, it results in the low corrosion resistance, especially in corrosive wastewater treatment and membranes’ chemical cleaning processes. Glass phase generated in the sintering is the main factor. In the present work, MgO-Al2O3-SiO2-ZrO2 system ceramic glass is chosen as sintering aids with a crystallinity of 89.63 %. The bending strength of the alumina membrane can be increased from 46.79 MPa of pure alumina to 111.02 MPa with 4.8 wt% ceramic glass addition. The sintering temperature of pure Al2O3 membrane is much higher than 1600 °C when the equal bending strength is obtained. The bending strength loss rate of the tubular ceramic membrane is only 5.13 % and 3.85 % after the static stage and dynamic separation for 36 h acid corrosion. MgAl2O4, Mg2SiO4, and ZrO2 crystals locate on alumina particles’ necks and provide the membrane with excellent mechanical properties and outstanding corrosion resistance. The Al2O3 membrane has a porosity of 34.06 % and a mean pore size of 1.42 μm, besides, acid corrosion can promote the permeability of membranes.

#3271 EXPRESSION OF THE COLLAGEN IV α345 MOLECULE ALONG THE RENAL TUBULE IN HEALTH AND DISEASE

Abstract Background and Aims Patients suffering from Alport Syndrome (AS) have a high life time risk of kidney failure and hearing loss. The underlying molecular cause is a germline mutation in one of the COL4A3/4/5 genes, whose gene products collectively form an important component of the glomerular basement membrane and the inner ear. Recent genetic studies have shown that the AS is much more prevalent than clinically recognized, suggesting that atypical clinical cases are frequent. Thus, patients with AS may phenocopy other kidney diseases. To date, pathomechanistic studies of the AS have focused exclusively on the glomerular membrane, yet equally strong expression of collagen IV can be found along the distal renal tubule. Structural disintegration of the distal tubular membrane may induce inflammation and fibrosis, thus progression of kidney disease. We hypothesize that genetic loss of the tubular collagen IV molecule contributes to kidney failure and may drive atypical phenotypes. Method Immunohistochemistry (IHC) and in situ hybridization (ISH, RNAscope) for COL IV α5, where IHC was performed on healthy human tissues as well as biopsies from patients with AS. Tubular marker staining for localization of COL IV α5 expression as well as spatial changes on consecutive sections. Human urinary primary tubular cells (huPTC) from healthy probands and patients with AS were generated and cultivated in cell culture, with analysis of COL IV mRNA by qPCR and detection of specifically expressed proteins by immunoblotting. Results COL IV α5 was detected within the tubular basement membrane (TBM) of the distal segments of renal tubules by IHC, including the thick ascending limb (TAL) of Henle (Tamm-Horsfall Protein), the distal convoluted tubule (11ß-Hydroxysteroid-Dehydrogenase) and the collecting duct (aquaporin 2). Spacial vicinity of these areas showed a predominance of interstitial fibrosis and inflammation in patient samples with AS, but not control samples with primary proteinuric diseases. Collagen IV protein is lost along the TBM of patients with AS, even in the hemizygous male and heterozygous female carriers of the hypomorphic but frequent COL4A5 mutation G624D. By ISH, COL4A5 expression was mainly observed in the glomerulus (most likely podocytes) and broadly in tubular epithelial cells, with only few tubulointerstitial cells showing mRNA expression. Likewise, the huPTC showed COL IV expression in qPCR, as well as COL IV α5 protein in immunoblotting. Conclusion Our studies show that the COL IV molecule is situated within the TBM of the complete distal tubule, starting from the TAL throughout the distant collecting duct. Although the epithelial cells have no detectable protein, in situ hybridization and primary cell cultures clearly suggest that tubular cells are a major source of the COL IV α345 molecule within the TBM. Renal biopsies of AS patients with diagnostic genetic COL IV variants indicate that tubulointerstitial fibrosis and inflammation starts in the vicinity of the distal tubule. Therefore, we postulate that the pathogenesis of AS may in part stem from the (distal) tubular apparatus, which is already known from other diseases such as ADTKD and nephronophthisis.