Straight Tubules Research Articles

The ultrastructure of peroxisomes in the kidney of the camel (Camelus dromedarius).

Dromedary camels can survive and reproduce in desert areas. The unique anatomical structure of the kidney enables the camel to prevent water loss. The present study aimed to investigate the ultrastructure of the peroxisomes in the normal kidney of the adult dromedary camel. Tissue samples were taken from the cortex and outer medulla of the kidney of eight camels. The samples were then processed for histological and ultrastructural investigations. The epithelial cells of the proximal tubules displayed peroxisomes with varying sizes and shapes. The peroxisomes were observed in either dispersed or clustered arrangement. Each peroxisome exhibited a homogenous matrix enveloped by a single membrane. Several peroxisomes exhibited one or more dark marginal plates that were always strongly associated with the smooth endoplasmic reticulum. The intensity of the peroxisomal matrix differed significantly, either within the same cell or across different cells. The intensity was light or dark, with a few peroxisomes presenting a similar intensity to that of the mitochondria. Some peroxisomes contained nucleoids within their matrix. The peroxisomes in the first and second sections of proximal convoluted tubules were scattered and primarily located in the region between the microvilli and the underlying mitochondria. The peroxisomes in the third region were abundant and frequently aggregated in clusters throughout the cytoplasm. In the fourth region, the number of peroxisomes was low. The proximal straight tubule had a limited quantity of peroxisomes. In conclusion, peroxisomes in the proximal tubule in kidney of normal dromedary camel were similar in shape and size to other mammals; however, heterogeneity exists as a result of differences in species-specific peroxisomal proteins. Peroxisomes are suggested to be a major source of metabolic energy and act as hydrogen peroxide (H2O2) scavengers, resulting in the release of water and oxygen.

Species-specific histological characterizations of renal tubules and collecting ducts in the kidneys of cats and dogs.

The histomorphological features of normal kidneys in cats and dogs have been revealed despite the high susceptibility of cats to tubulointerstitial damage. Herein, the histological characteristics of the two species were compared. Cytoplasmic lipid droplets (LDs) were abundant in the proximal convoluted tubules (PCTs) of cats aged 23-27 months but scarce in dogs aged 24-27 months. LDs were rarely observed in the distal tubules (DTs) and collecting ducts (CDs) of either species, as visualized by the expression of Tamm-Horsfall protein 1, calbindin-D28K, and aquaporin 2. The occupational area ratio of proximal tubules (PTs) in the renal cortex was higher, but that of DTs or CDs was significantly lower in adult cats than in dogs. Single PT epithelial cells were larger, but PCT, DT, and CD lumens were significantly narrower in adult cats than in dogs. Unlike adults, young cats at 6 months exhibited significantly abundant cytoplasmic LDs in proximal straight tubules, indicating lipid metabolism-related development. Histochemistry of the 21 lectins also revealed variations in glycosylation across different renal tubules and CDs in both species. Sodium-glucose cotransporter 2 was expressed only in PTs, excluding the proximal straight tubules with few LDs in adult cats or the PCTs of young cats and adult dogs. These findings are crucial for understanding species-specific characteristics of renal histomorphology and pathogenesis.

The SLC6A18 Transporter Is Most Likely a Na-Dependent Glycine/Urea Antiporter Responsible for Urea Secretion in the Proximal Straight Tubule: Influence of This Urea Secretion on Glomerular Filtration Rate.

Urea is the major end-product of protein metabolism in mammals. In carnivores and omnivores, a large load of urea is excreted daily in urine, with a concentration that is 30-100 times above that in plasma. This is important for the sake of water economy. Too little attention has been given to the existence of energy-dependent urea transport that plays an important role in this concentrating activity. This review first presents functional evidence for an energy-dependent urea secretion that occurs exclusively in the straight part of the proximal tubule (PST). Second, it proposes a candidate transmembrane transporter responsible for this urea secretion in the PST. SLC6A18 is expressed exclusively in the PST and has been identified as a glycine transporter, based on findings in SLC6A18 knockout mice. We propose that it is actually a glycine/urea antiport, secreting urea into the lumen in exchange for glycine and Na. Glycine is most likely recycled back into the cell via a transporter located in the brush border. Urea secretion in the PST modifies the composition of the tubular fluid in the thick ascending limb and, thus, contributes, indirectly, to influence the "signal" at the macula densa that plays a crucial role in the regulation of the glomerular filtration rate (GFR) by the tubulo-glomerular feedback. Taking into account this secondary active secretion of urea in the mammalian kidney provides a new understanding of the influence of protein intake on GFR, of the regulation of urea excretion, and of the urine-concentrating mechanism.

#1914 Comprehensive single-cell sequencing and lipidomics identify diverse injury states and cholesterol dynamics of the PTs in AKI-to-CKD transition

Abstract Background and Aims The underlying cellular events and metabolic dysfunction of acute kidney injury (AKI) transformed to chronic kidney disease (CKD) is still largely unclear. Previous studies have suggested lipids and metabolites have a profound impact on acute and chronic inflammation. One of the main sites of renal lipid accumulation is the proximal tubule cells (PTs). Here we demonstrated the injury states and cholesterol dynamics of PTs and its potential function in AKI to CKD in unilateral ischemia-reperfusion injury (UIR) mice model. Method We employed single-cell combinatorial indexing lipidomics to analyze 15 mouse kidneys from a mouse model of failed repaired UIR at five time points. We identified cell types through unsupervised clustering analysis. Differential gene expression, enrichment analysis and main function scoring were applied to define functional heterogeneity and injury states of PTs. Next, pseudotime analysis of differentiation transitions was performed to create the diverse PT lineages. Finally, using SCENIC analysis, we identified the key transcription factors that drive the differentiation of PTs. Results We identified 13 main cell clusters and the dynamic changes in the process of AKI to CKD transition were analysed. A remarkable decrease in PTs after injury at day 1 followed with a recovery at day 3 post AKI were observed. Spatiotemporal profiling of the main cell types showed that the most injured areas in the acute stages of kidney injury are primarily concentrated in the outer stripe, specifically the region where the proximal straight tubules (PSTs) are located. In order to gain a higher resolution of the dynamics of PST subtypes during AKI to CKD, we performed sub-clustering analysis specifically on PSTs, partitioning them into 10 subclusters. Single-cell analysis identified maladaptive PSTs (PST-5) with the highest apoptosis and ferroptosis scores. Notably, pseudotime analysis revealed that PST-5 differentiated from PST-4, which has the highest lipid metabolism score. Indeed, among all the cells in the kidney, the PTs exhibited the most active metabolic reprogramming due to their differentiation and redifferentiation early after AKI. Lipid omics profiling reveals an abnormal elevation of the cholesterol metabolites 27-hydroxycholesterol (27-OH) and 25-hydroxycholesterol (25-OH) following AKI. Interestingly, the PST-4-specific expression of Cyp7b1 served as a key enzyme regulating the concentration of 27-OH. This gene has been found to be significantly absent after AKI. Moreover, the binding of 27HC, a natural ligand, to endogenous estrogen receptor alpha (ERα) leads to the upregulation of heme oxygenase 1 (Hmox1), thereby promoting ferroptosis. Finally, SCENIC analysis revealed that Cyp7b1-mediated accumulation of 27-HC is dependent on the transcription factor Atf3. Conclusion Our results indicate that Cyp7b1 deficiency confers ferroptosis, which are primarily dependent on the upregulation of cellular cholesterol homeostasis and 27-HC secretion, leading to the progression of AKI. These findings suggest that the Cyp7b1/Hmox1/Atf3/27-HC axis may serve as a potential therapeutic target for preventing the development of CKD.

Isotope-guided metabolomics dissects kidney arginine metabolism

Background: L-arginine is a key amino acid for detoxification, protein metabolism, and kidney and cardiovascular health. In the urea cycle, ammonia is incorporated into urea through the transformation of arginine to ornithine and urea, a reaction that occurs mostly in the liver but also in the kidneys. Hypothesis: An imbalance of kidney arginine metabolism can be associated with kidney injury. Aim: To detect the arginine uptake and its metabolic fate in kidney in vivo and ex vivo models by metabolic flux analysis. Method: Healthy C57BL/6 mice (n=22) were fed with normal and 13C6-15N4-arginine diet for 1, 2 and 8 weeks. Extracted metabolites from kidney cortex and medulla were analyzed with UHPLC/QQQ-based mass spectrometry targeting arginine-related metabolic pathways: the urea cycle, polyamines, the nitric oxide pathway, arginine/proline/glutamate interconversion, as well as modified forms of arginine. Additionally, micro-dissected nephron segments (glomeruli, proximal convoluted tubules (PCT), proximal straight tubules (PST), thin ascending limb of the loop of Henle (TAL), distal convoluted tubules (DCT), collecting ducts (CD)) from 4 healthy C57BL/6 mice, were incubated with 13C6-arginine and analyzed accordingly. Results: Isotope tracing allowed us to follow the fate of arginine in the kidney cortex and medulla of the 13C6-15N4-arginine-fed animals. The ex vivo experiments confirmed that all nephron segments take up and metabolize arginine, except for the TAL. More specifically, ornithine was found in all segments apart from the CD. Agmatine was formed in the PST and the CD, whereas arginine contributed to the proline and glutamine formation in the glomeruli, the PCT and the CD. Methylated forms of arginine were observed in the PST and the DCT. Conclusion: This study enabled the detection of arginine-related metabolites inside the kidney and showed that the metabolic fate of arginine differs along the nephron. The detailed isotope-based arginine metabolic flux and its role in kidney disease models will be determined next. This work is supported by the Young Investigator Award from the Novo Nordisk Foundation (grant number NNF19OC0056043), awarded to Markus Rinschen. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

3D autofluorescence imaging of hydronephrosis and renal anatomical structure using cryo-micro-optical sectioning tomography.

Rationale: Mesoscopic visualization of the main anatomical structures of the whole kidney in vivo plays an important role in the pathological diagnosis and exploration of the etiology of hydronephrosis. However, traditional imaging methods cannot achieve whole-kidney imaging with micron resolution under conditions representing in vivo perfusion. Methods: We used in vivo cryofixation (IVCF) to fix acute obstructive hydronephrosis (unilateral ureteral obstruction, UUO), chronic spontaneous hydronephrosis (db/db mice), and their control mouse kidneys for cryo-micro-optical sectioning tomography (cryo-MOST) autofluorescence imaging. We quantitatively assessed the kidney-wide pathological changes in the main anatomical structures, including hydronephrosis, renal subregions, arteries, veins, glomeruli, renal tubules, and peritubular functional capillaries. Results: By comparison with microcomputed tomography imaging, we confirmed that IVCF can maintain the status of the kidney in vivo. Cryo-MOST autofluorescence imaging can display the main renal anatomical structures with a cellular resolution without contrast agents. The hydronephrosis volume reached 26.11 ± 6.00 mm3 and 13.01 ± 3.74 mm3 in 3 days after UUO and in 15-week-old db/db mouse kidneys, respectively. The volume of the cortex and inner stripe of the outer medulla (ISOM) increased while that of the inner medulla (IM) decreased in UUO mouse kidneys. Db/db mice also showed an increase in the volume of the cortex and ISOM volume but no atrophy in the IM. The diameter of the proximal convoluted tubule and proximal straight tubule increased in both UUO and db/db mouse kidneys, indicating that proximal tubules were damaged. However, some renal tubules showed abnormal central bulge highlighting in the UUO mice, but the morphology of renal tubules was normal in the db/db mice, suggesting differences in the pathology and severity of hydronephrosis between the two models. UUO mouse kidneys also showed vascular damage, including segmental artery and vein atrophy and arcuate vein dilation, and the density of peritubular functional capillaries in the cortex and IM was reduced by 37.2% and 49.5%, respectively, suggesting renal hypoxia. In contrast, db/db mouse kidneys showed a normal vascular morphology and peritubular functional capillary density. Finally, we found that the db/db mice displayed vesicoureteral reflux and bladder overactivity, which may be the cause of hydronephrosis formation. Conclusions: We observed and compared main renal structural changes in hydronephrosis under conditions representing in vivo perfusion in UUO, db/db, and control mice through cryo-MOST autofluorescence imaging. The results indicate that cryo-MOST with IVCF can serve as a simple and powerful tool to quantitatively evaluate the in vivo pathological changes in three dimensions, especially the distribution of body fluids in the whole kidney. This method is potentially applicable to the three-dimensional visualization of other tissues, organs, and even the whole body, which may provide new insights into pathological changes in diseases.

Bisphenol A impairs renal function by reducing Na+/K+-ATPase and F-actin expression, kidney tubule formation in vitro and in vivo

The kidney proximal tubule is responsible for reabsorbing water and NaCl to maintain the homeostasis of the body fluids, electrolytes, and nutrients. Thus, abnormal functioning of the renal proximal tubule can lead to life-threatening imbalances. Bisphenol A (BPA) has been used for decades as a representative chemical in household plastic products, but studies on its effects on the kidney proximal tubule are insufficient. In this study, immunocytochemical and cytotoxicity tests were performed using two- and three-dimensional human renal proximal tubular epithelial cell (hRPTEC) cultures to investigate the impact of low-dose BPA (1–10 μM) exposure. BPA was found to interfere with straight tubule formation as observed by low filamentous actin formation and reduced Na+/K+-ATPase expression in the tubules of hRPTEC 3D cultures. Similar results were observed in rat pup kidneys following oral administration of 250 mg/kg BPA. Moreover, the expression of HO-1 and 8-OHdG, key markers for oxidative stress, was increased in vitro and in vivo following BPA administration, whereas that of OAT1 and OAT, important transporters of the renal proximal tubules, was not altered. Overall, no-observed-adverse-effect-level (NOAEL)-dose BPA exposure can decrease renal function by promoting abnormal tubular formation both in vitro and in vivo. Therefore, we propose that although it does not exhibit life-threatening toxicity, exposure to low levels of BPA can negatively affect homeostasis in the body by means of long-term deterioration of renal proximal tubular function in humans.

Emx2is Required for Nephron Segment Development in the Zebrafish Pronephros

The empty spiracles homeobox gene 2 (emx2)encodes a transcription factor that is expressed during neuronal, auditory, olfactory, and renal development, but its role in the latter has not yet been fully elucidated. Here, our objective is to utilize the zebrafish animal model to investigate the functions of emx2 during the development of nephrons, which are the structural and functional units of the kidney. Using whole mount in situ hybridization (WISH), we detected emx2transcript beginning at the 6 somite‐stage in renal progenitors and this expression continued throughout the process of forming discrete proximal convoluted tubule (PCT) and proximal straight tubule (PST) segment regions at 24 hours post fertilization (hpf). Based on this spatiotemporal pattern of emx2 expression in renal progenitors, we hypothesized that emx2is essential for segmentation of the nephron into discrete proximal and distal regions. To investigate this, we generated emx2‐deficient embryos and compared them to wild‐type (WT) controls at various time points from 24‐96 hpf. Knockdown of emx2resulted in head necrosis and diminished yolk sac extension at 24 hpf, as well as development of smaller head, eye and body, pericardial edema, abnormal fin growth, yolk ball inflammation and vascular hemorrhage in the central nervous system from 2‐5 days post fertilization. We used WISH to stain for each nephron segment in fixed animals and then quantified segment length and cell number. WISH analysis revealed a significantly reduced podocyte area, diminished PCT and reduced multiciliated cell numbers in emx2‐deficient embryos compared to WT embryos. WISH results also revealed secondary phenotypes, such as reduced fin bud area and somite in emx2‐deficient embryos. Additionally, Alcian Blue staining at 96 hpf revealed jaw abnormalities and pharyngeal arch malformation in emx2‐deficient embryos. O‐Dianisidine staining showcased vascular hemorrhage in the eyes and head of emx2deficient embryos. We concluded that emx2is essential for kidney segmentation in zebrafish, especially in podocyte and PCT formation. Additionally, emx2deficiency causes secondary jaw, fin, cartilage blood accumulation and muscle phenotypes. Future studies will delineate the cellular defects in nephron development in emx2 deficient embryos and determine the relationship between Emx2 and pathways which are essential for proximal segment ontogeny, such as retinoic acid signaling.

ANATOMICAL AND HISTOLOGICAL STRUCTURE OF THE KIDNEYS IN THE WHITE STORK (CICONIA CICONIA)

With the help of the methodological complex, the anatomical, histological, and morphometric parameters of the kidneys of the white stork (Ciconia ciconia), a representative of birds of prey in Belarus, were studied. When studying the kidneys of the white stork, there was found a relatively thin connective tissue capsule of the organ, a low density of renal (malpighian) bodies and the glomeruli in the cortical substance, the presence of areas with pathological processes in the form of granular, vacuolar and macro vesicular fatty renal dystrophy, as well as changes in the structure of cells that form distal straight tubules from cuboidal to polymorphic. These transformations in the structure of the organ can both bear an individual character and depend on environmental factors, lifestyle, behavior, and the nature of diet of the bird.

Hypothetical Mechanism of Exercise-Induced Acute Kidney Injury Associated with Renal Hypouricemia.

Renal hypouricemia (RHUC) is a hereditary disease that presents with increased renal urate clearance and hypouricemia due to genetic mutations in the urate transporter URAT1 or GLUT9 that reabsorbs urates in the renal proximal tubule. Exercise-induced acute kidney injury (EIAKI) is known to be a complication of renal hypouricemia. In the skeletal muscle of RHUC patients during exhaustive exercise, the decreased release of endothelial-derived hyperpolarization factor (EDHF) due to hypouricemia might cause the disturbance of exercise hyperemia, which might increase post-exercise urinary urate excretion. In the kidneys of RHUC patients after exhaustive exercise, an intraluminal high concentration of urates in the proximal straight tubule and/or thick ascending limb of Henle’s loop might stimulate the luminal Toll-like receptor 4–myeloid differentiation factor 88–phosphoinositide 3-kinase–mammalian target of rapamycin (luminal TLR4–MyD88–PI3K–mTOR) pathway to activate the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome and may release interleukin-1β (IL-1β), which might cause the symptoms of EIAKI.

SGLT2 Inhibition for Diabetic and Non-diabetic Kidney Disease

Chronic kidney disease (CKD) can be progressive, and its prognosis is worse because of increased mortality when it is associated with diabetes and cardiac disease. The outcomes of diabetic kidney disease (DKD) need to be improved, despite multifactorial interventions including glucose and blood pressure (BP) control, and the use of renin-angiotensin system (RAS) inhibitors, statins, and aspirin. Recent clinical trials suggest that sodium-glucose cotransporter-2 (SGLT2) inhibitors offer additional cardiorenal protection in DKD and non-diabetic CKD on top of RAS inhibition. The action of SGLT2 inhibitors is derived from the proximal tubule of the kidney, but their systemic effects beyond glucose-lowering involve hemodynamic and non-hemodynamic mechanisms. First, SGLT2 inhibitors restore tubuloglomerular feedback and relieve glomerular hypertension and albuminuria. Second, natriuresis and renal glycosuria lead to fluid and weight loss, resulting in BP lowering and prevention of heart failure. Third, SGLT2 inhibitors have anti-inflammatory and anti-oxidative actions that can reduce renal and cardiac inflammation and fibrosis, probably via adenosine monophosphate-activated protein kinase and sirtuin-1 activation. Finally, the proximal tubular workload is relieved, accompanied by increased erythropoiesis. Hypoxia-inducible factor 1 may be stimulated by renal outer medullary hypoxia when tubular sodium transport shifts from the proximal convoluted tubule to the proximal straight tubule and thick ascending limb, due to SGLT2 inhibition. These effects may also be beneficial in non-diabetic CKD, and we anticipate that SGLT2 inhibitors will prove effective for albuminuria reduction and preservation of kidney function in primary kidney diseases, including glomerulonephritis.

English

Hematocele with blunt scrotal trauma is an uncommon cause of the testicular pain. Elastography is the new recent advance in the field of ultrasound. USG and elastography findings of the acute hematocele is described in this aricle. Testicular trauma is the third most common cause of acute scrotal pain,1 and high-frequency ultrasonography (USG) with a linear array transducer is the first preferred modality for testicular trauma evaluation. Extra testicular haematoceles or blood collections inside the tunica vaginalis are the most common findings in the scrotum after blunt injury.2 On clinical assessment, haematocele appears as a hard mass like swelling and causes pain in the scrotum. In the majority of cases, spontaneous resolution occurs with the support of conservative therapy,3 even if treated conservatively, may result in infection, discomfort, or atrophy in undiagnosed broad hematoceles and testicular hematomas over time.4 A testis with its coverings, epididymis, and spermatic cord are all contained in each hemiscrotum. A typical testis is 5 x 3 x 2 cm in diameter and has an intermediate echogenicity. The tunica albuginea is a fibrous covering that protects the testis from damage from the external injuries. It is located on top of the tunica vasculosa, which is made up of capsular arteries. A testis with its coverings, epididymis, and spermatic cord are all contained in each hemiscrotum. With its high tensile strength, the tunica albuginea plays an important role in shielding the testis from trauma. It can withstand a force of up to 50 kg without bursting. The testicular parenchyma is made up of several lobules, each of which is made up of several seminiferous tubules that lead to dilated spaces inside the mediastinum called the rete testis through the tubuli recti. The epididymis is made up of a head, neck, and tail that protects the superolateral part of the testis. The epididymis' tail ends in the spermatic cord as the vas deferens. The epididymal head is a 5 – 12 mm pyramidal structure that sits atop the testis' superior pole. The head is almost isoechoic to the testis. The epididymis has a 2 – 4 mm thick body.5 The patient lies in a supine position with the scrotum covered by a towel positioned between the thighs during scrotal ultrasound. A high-frequency lineararray transducer with a frequency range of 7 – 14 MHz is preferred. The scrotum is always soft to the touch after trauma, making scanning difficult. It should be attempted to examine both the testes and the epididymis in their entirety, as well as any extra testicular lesions. The testes are assessed in two planes: longitudinal and transverse. Each testis and epididymis should be compared to the contralateral testis and epididymis in terms of size and echogenicity. Transverse scrotal imaging is important for depicting both testes and comparing their gray-scale and colour Doppler appearances.

Gldc is essential for embryonic development and kidney organogenesis

Glycine is a simple amino acid that is vital to the proper functioning of the body, but its roles during ontogeny are not well understood. Glycine levels are precisely regulated through the glycine cleavage system (GCS), a complex molecular machine that produces one-carbon units for later metabolism and folate production. Elevated glycine levels due to congenital mutations in GCS components, such as glycine dehydrogenase (gldc), cause devastating human birth defects and the rare disease nonketotic hyperglycinemia (NKH). The exact pathological implications of glycine accumulation are unknown, but NKH patients suffer from pleiotropic symptoms including seizures, apnea, lethargy, severe mental retardation, and early death. Animal models utilizing mice and zebrafish have shown increased ventriculomegaly and motor dysfunction in gldc deficient animals, but have not analyzed organogenesis. Here, we have utilized zebrafish as a genetic platform to explore the roles of gldc during early development. Whole mount in situ hybridization revealed that gldc transcripts were highly expressed in multiple tissues, including the central nervous system and embryonic kidney, recapitulating both mouse and human expression studies. gldc deficiency caused hydrocephalus and pericardial edema, suggesting defects in brain and renal ontogeny. Elevated apoptosis was detected in locations within the brain, kidney, and cloaca. Furthermore, formation of nephron cell populations in the kidney was disrupted in gldc deficient embryos, where the proximal straight tubule was increased at the expense of the distal tubule. Morphological and expression studies revealed severe alterations in brain patterning and morphogenesis as well. Taken together, these studies indicate that gldc has essential roles during early development and have revealed novel functions for pattern formation and cell survival in tissues such as the brain and kidney. Our evidence further emphasizes the zebrafish as a faithful model to examine NKH. Ongoing work with the zebrafish model is poised to expand our medical understanding about the developmental defects consequent to NKH and can be used to perform chemical screens to identify potential therapeutic interventions.

A Mathematical Model of the Rat Kidney: Ammonia Transport

Ammonia generated within the kidney is partitioned into a urinary fraction (the key buffer for net acid excretion), and an aliquot delivered to the systemic circulation. The physiology of this partitioning has yet to be examined in a kidney model, and that is undertaken in this work. This involves explicit representation of the cortical labyrinth, so that cortical interstitial solute concentrations are computed, rather than assigned. A detailed representation of cortical vasculature has been avoided by making the assumption that solute concentrations within interstitium and peritubular capillaries are likely to be identical, and that there is little to no modification of venous composition as blood flows to the renal vein. The model medullary ray has also been revised to include a segment of proximal straight tubule, which supplies ammonia to this region. The principal finding of this work is that cortical labyrinth interstitial ammonia concentration is likely to be several-fold higher than systemic arterial ammonia. This elevation of interstitial ammonia enhances ammonia secretion in both PCT and DCT, with uptake by Na,K-ATPases of both segments. Model prediction of urinary ammonia excretion is concordant with measured values, but at the expense of greater ammoniagenesis, with high rates of renal venous ammonia flux. This derives from a limited capability of the model medulla to replicate the high interstitial ammonia concentrations that are required to drive collecting duct ammonia secretion. Thus, renal medullary ammonia trapping appears key to diverting ammonia from renal vein to urine, but capturing the underlying physiology remains a challenge.

Single-cell analysis of angiotensin-converting enzyme II expression in human kidneys and bladders reveals a potential route of 2019 novel coronavirus infection.

Background:Since 2019, a novel coronavirus named 2019 novel coronavirus (2019-nCoV) has emerged worldwide. Apart from fever and respiratory complications, acute kidney injury has been observed in a few patients with coronavirus disease 2019. Furthermore, according to recent findings, the virus has been detected in urine. Angiotensin-converting enzyme II (ACE2) has been proposed to serve as the receptor for the entry of 2019-nCoV, which is the same as that for the severe acute respiratory syndrome. This study aimed to investigate the possible cause of kidney damage and the potential route of 2019-nCoV infection in the urinary system.Methods:We used both published kidney and bladder cell atlas data and new independent kidney single-cell RNA sequencing data generated in-house to evaluate ACE2 gene expression in all cell types in healthy kidneys and bladders. The Pearson correlation coefficients between ACE2 and all other genes were first generated. Then, genes with r values larger than 0.1 and P values smaller than 0.01 were deemed significant co-expression genes with ACE2.Results:Our results showed the enriched expression of ACE2 in all subtypes of proximal tubule (PT) cells of the kidney. ACE2 expression was found in 5.12%, 5.80%, and 14.38% of the proximal convoluted tubule cells, PT cells, and proximal straight tubule cells, respectively, in three published kidney cell atlas datasets. In addition, ACE2 expression was also confirmed in 12.05%, 6.80%, and 10.20% of cells of the proximal convoluted tubule, PT, and proximal straight tubule, respectively, in our own two healthy kidney samples. For the analysis of public data from three bladder samples, ACE2 expression was low but detectable in bladder epithelial cells. Only 0.25% and 1.28% of intermediate cells and umbrella cells, respectively, had ACE2 expression.Conclusion:This study has provided bioinformatics evidence of the potential route of 2019-nCoV infection in the urinary system.

Sevoflurane sedation and nephrogenic diabetes insipidus in patients affected with severe acute respiratory syndrome coronavirus 2.

Sevoflurane sedation and nephrogenic diabetes insipidus in patients affected with severe acute respiratory syndrome coronavirus 2.

Microscopic changes in the organs of broiler chickens with Ornithobacterium rhinotra-cheale infection

Nowadays ornithobacteriosis is widespread among industrial poultry in Ukraine and the world. The disease leads to significant economic losses. The large variation in the serotypes of the bacteria complicates the treatment of the disease. The study of microscopic changes that occur in organs during ornithobacteriosis will help to better understand the pathogenesis of the disease development. Ornithobacteriosis was diagnosed in clinically sick broiler chickens by bacteriological studies using Maldi Tof mass-spectrometry. As a result of the antibiotic sensitivity test, the pathogen was found to be sensitive to doxycycline, tilmicosin, rifampicin, cefazolin, amoxiclav and benzylpenicillin. Histological studies of internal organs – trachea, lungs, heart, kidneys, liver and spleen – were carried out. It was found that with spontaneous ornithobacteriosis of broiler chickens, the most expressive microscopic changes occur in the respiratory organs – the lungs and trachea and are characterized by a decrease in the lumen of the parabronchials due to edema of their walls and infiltration with lymphocytes, the absence of epithelium on the surface of the parabronchials, narrowing of the air capillaries of the parabronchial complexes, hemorrhages in the parenchyma of the parabronchial complexes, vasodilatation of the lung vessels and overflow of their blood vessels with blood cells, edema around the epithelium trachea, destruction of part of the tracheal mucosa epithelial cells, edema of its submucosa, expansion and overflow of blood vessels of the mucous membrane with blood cells. In the spleen there was a uniform diffuse edema of the parenchyma and a decrease in the number of lymphocytes in the lymphoid follicles; in the kidneys – expansion and overflow of the stroma blood vessels, uneven edema of the glomeruli of one part of the renal corpuscles and destruction of the glomeruli of another, granular degeneration of the convoluted and straight tubules of the kidneys; in the liver – edema, hemorrhage, violation of the hepatic lobules’ structure, expansion of the hepatic veins, granular degeneration of hepatocytes or their destruction; in the heart – edema of the myocardial interstitium, muscle fibers’ granular dystrophy, fragmentation of muscle fibers as a result of their rupture. Histological research of ORT infected chickens will lead to a better understanding the mechanism of pathological changes at the microscopic level, which will facilitate the development of more effective methods of treatment and prevention of the disease.

Histological Features of Kidney Observed Through Conventional Microscope and Paper Microscope, A Comparative Study

Introduction: Paper microscope (Foldscope), one of the latest inventions in the field of science is an ultra-low cost, portable, versatile, and water proof microscope which does not require electricity. The aim of this research was to compare histological features of kidney observed in the normal microscope and foldscope. This research is focused on the comparison of the histological features of kidney observed in the conventional microscope and foldscope under 100X.
 Method: This comparative study was conducted in Department of Anatomy, Nepalese Army Institute of Health Sciences, Nepal. All histological slides of kidneys present at Department of Anatomy during June 2019-September 2019 were included in this study.
 Result: A total of 25 samples were viewed under the conventional laboratory microscope (C x L and Paper Microscope (Foldscope). Foldscope observers were able to distinguish the histological features of the cortex and the medulla of the kidney along with the difference in the luminal size and the staining of the cells in the cortex and the medulla of the kidney. In comparison to conventional microscope, 5 (20%) of samples, observers were able to distinguish the features of the cells lining the tubules of the cortex and in 6 (24%) of samples, observers were able to distinguish the features of the cell lining collecting duct and straight tubules of loop of Henle of medulla using Foldoscope.
 Conclusion: Paper microscope can be a useful alternative of conventional microscope in low resource settings for the identification of the histological samples.

Effects of Oil Type on Sterol-Based Organogels and Emulsions

The present study investigates the effect of oil type on the formation, morphology and mechanical properties of phytosterol-based organogels. The formation of organogels can be satisfactorily predicted with a criterion based on Hansen Solubility Parameters (HSPs), provided that the sterol and sterol ester in these systems assemble as tubules. When structures other than tubules are formed, the predictability of the HSP-based criterion becomes void. In cases where organogelling occurred, the morphology and mechanical properties of the tubular network of the gels and water-in-oil emulsions were investigated. The findings revealed that the structure of the tubular network formed in oils with different compositions, could be grouped based on the dielectric constants of the oils. Curly and bundled tubules which formed networks, were observed in gels prepared with low dielectric constant oils (i.e. decane and limonene). For oils with a moderate dielectric constant (i.e. castor oil and sunflower oil), the tubules became less curly and straighter. Upon increasing the dielectric constant of the oil (eugenol), individual tubules were observed next to the bundled tubules. The results showed that straighter, bundled tubules are associated with firmer gels, whereas less straight (i.e. curly) tubules rendered weaker gels. The tubular network of the water-in-oil emulsions obtained for oils with a low dielectric constant appeared more open with straighter tubules. For oils with relatively high dielectric constant, the water-in-oil emulsions lost most of their tubular structure and only a few tubules could be observed. In the presence of emulsion droplets fewer tubules are formed, resulting in weaker networks.

Single-cell RNA sequencing analysis of human kidney reveals the presence of ACE2 receptor: A potential pathway of COVID-19 infection.

BackgroundA novel coronavirus called SARS‐Cov‐2, which shared 82% similarity of genome sequence with SARS‐CoV, was found in Wuhan in late December of 2019, causing an epidemic outbreak of novel coronavirus‐induced pneumonia with dramatically increasing number of cases. Several organs are vulnerable to COVID‐19 infection. Acute kidney injury (AKI) was reported in parts of case‐studies reporting characteristics of COVID‐19 patients. This study aimed at analyzing the potential route of SARS‐Cov‐2 entry and mechanism at cellular level.MethodSingle‐cell RNA sequencing (scRNA‐seq) technology was used to obtain evidence of potential route and ACE2 expressing cell in renal system for underlying pathogenesis of kidney injury caused by COVID‐19. The whole process was performed under R with Seurat packages. Canonical marker genes were used to annotate different types of cells.ResultsTen different clusters were identified and ACE2 was mainly expressed in proximal tubule and glomerular parietal epithelial cells. From Gene Ontology (GO) & KEGG enrichment analysis, imbalance of ACE2 expression, renin‐angiotensin system (RAS) activation, and neutrophil‐related processes were the main issue of COVID‐19 leading kidney injury.ConclusionOur study provided the cellular evidence that SARS‐Cov‐2 invaded human kidney tissue via proximal convoluted tubule, proximal tubule, proximal straight tubule cells, and glomerular parietal cells by means of ACE2‐related pathway and used their cellular protease TMPRSS2 for priming.