Immuno-priming durvalumab with bevacizumab in HER2-negative advanced breast cancer: a pilot clinical trial.

BACKGROUND: Preclinical research suggests that the efficacy of immune checkpoint inhibitors in breast cancer can be enhanced by combining them with antiangiogenics, particularly in a sequential fashion. We sought to explore the efficacy and biomarkers of combining the anti-PD-L1 durvalumab plus the antiangiogenic bevacizumab after bevacizumab monotherapy for advanced HER2-negative breast cancer. METHODS: Patients had advanced HER2-negative disease that progressed while receiving single-agent bevacizumab maintenance as a part of a previous chemotherapy plus bevacizumab regimen. Treatment consisted of bi-weekly durvalumab plus bevacizumab (10 mg/kg each i.v.). Peripheral-blood mononuclear cells (PBMCs) were obtained before the first durvalumab dose and every 4 weeks and immunophenotyped by flow-cytometry. A fresh pre-durvalumab tumor biopsy was obtained; gene-expression studies and immunohistochemical staining to assess vascular normalization and characterize the immune infiltrate were conducted. Patients were classified as "non-progressors" if they had clinical benefit (SD/PR/CR) at 4 months. The co-primary endpoints were the changes in the percentage T cell subpopulations in PBMCs in progressors versus non-progressors, and PFS/OS time. RESULTS: Twenty-six patients were accrued. Median PFS and OS were 3.5 and 11 months; a trend for a longer OS was detected for the hormone-positive subset (19.8 versus 7.4 months in triple-negatives; P = 0.11). Clinical benefit rate at 2 and 4 months was 60% and 44%, respectively, without significant differences between hormone-positive and triple-negative (P = 0.73). Non-progressors' tumors displayed vascular normalization features as a result of previous bevacizumab, compared with generally abnormal patterns observed in progressors. Non-progressors also showed increased T-effector and T-memory signatures and decreased TREG signatures in gene expression studies in baseline-post-bevacizumab-tumors compared with progressors. Notably, analysis of PBMC populations before durvalumab treatment was concordant with the findings in tumor samples and showed a decreased percentage of circulating TREGs in non-progressors. CONCLUSIONS: This study reporting on sequential bevacizumab+durvalumab in breast cancer showed encouraging activity in a heavily pre-treated cohort. The correlative studies agree with the preclinical rationale supporting an immunopriming effect exerted by antiangiogenic treatment, probably by reducing TREGs cells both systemically and in tumor tissue. The magnitude of this benefit should be addressed in a randomized setting. TRIAL REGISTRATION: (www.clinicaltrials.gov): NCT02802098 . Registered on June 16, 2020.

Diacylglycerol kinase ζ limits IL-2-dependent control of PD-1 expression in tumor-infiltrating T lymphocytes.

BACKGROUND: The inhibitory functions triggered by the programmed cell death-1 (PD-1) receptor following binding to its ligand (PD-L1) protect healthy organs from cytotoxic T cells, and neutralize antitumor T cell attack. Antibody-based therapies to block PD-1/PD-L1 interaction have yielded notable results, but most patients eventually develop resistance. This failure is attributed to CD8+ T cells achieving hyporesponsive states from which recovery is hardly feasible. Dysfunctional T cell phenotypes are favored by a sustained imbalance in the diacylglycerol (DAG)- and Ca2+-regulated transcriptional programs. In mice, DAG kinase ζ (DGKζ) facilitates DAG consumption, limiting T cell activation and cytotoxic T cell responses. DGKζ deficiency facilitates tumor rejection in mice without apparent adverse autoimmune effects. Despite its therapeutic potential, little is known about DGKζ function in human T cells, and no known inhibitors target this isoform. METHODS: We used a human triple parameter reporter cell line to examine the consequences of DGKζ depletion on the transcriptional restriction imposed by PD-1 ligation. We studied the effect of DGKζ deficiency on PD-1 expression dynamics, as well as the impact of DGKζ absence on the in vivo growth of MC38 adenocarcinoma cells. RESULTS: We demonstrate that DGKζ depletion enhances DAG-regulated transcriptional programs, promoting interleukin-2 production and partially counteracting PD-1 inhibitory functions. DGKζ loss results in limited PD-1 expression and enhanced expansion of cytotoxic CD8+ T cell populations. This is observed even in immunosuppressive milieus, and correlates with the reduced ability of MC38 adenocarcinoma cells to form tumors in DGKζ-deficient mice. CONCLUSIONS: Our results, which define a role for DGKζ in the control of PD-1 expression, confirm DGKζ potential as a therapeutic target as well as a biomarker of CD8+ T cell dysfunctional states.

Pure platelet-rich plasma and supernatant of calcium-activated P-PRP induce different phenotypes of human macrophages.

AIM: This study aimed to evaluate the effect of two platelet preparations used in the clinic, pure platelet-rich plasma (P-PRP) and the supernatant of calcium-activated P-PRP (S-PRP), on the phenotype of human macrophages. MATERIALS & METHODS: Surface markers and cytokine production of human monocyte-derived macrophages were analyzed after 24 h stimulation with P-PRP or S-PRP. RESULTS: P-PRP and S-PRP present no difference in the expression of CD206, a M2 tissue-repair macrophage-related marker. However, these same macrophages presented different levels of CD163, CD86 as well as different IL-10 secretion capacities after 24 h incubation. CONCLUSION: These platelet preparations do not have an equivalent biological effect over macrophages, which suggest that they may present different clinical regenerative potentials.

Class-modeling analysis reveals T-cell homeostasis disturbances involved in loss of immune control in elite controllers.

BACKGROUND: Despite long-lasting HIV replication control, a significant proportion of elite controller (EC) patients may experience CD4 T-cell loss. Discovering perturbations in immunological parameters could help our understanding of the mechanisms that may be operating in those patients experiencing loss of immunological control. METHODS: A case-control study was performed to evaluate if alterations in different T-cell homeostatic parameters can predict CD4 T-cell loss in ECs by comparing data from EC patients showing significant CD4 decline (cases) and EC patients showing stable CD4 counts (controls). The partial least-squares-class modeling (PLS-CM) statistical methodology was employed to discriminate between the two groups of patients, and as a predictive model. RESULTS: Herein, we show that among T-cell homeostatic alterations, lower levels of naïve and recent thymic emigrant subsets of CD8 cells and higher levels of effector and senescent subsets of CD8 cells as well as higher levels of exhaustion of CD4 cells, measured prior to CD4 T-cell loss, predict the loss of immunological control. CONCLUSIONS: These data indicate that the parameters of T-cell homeostasis may identify those EC patients with a higher proclivity to CD4 T-cell loss. Our results may open new avenues for understanding the mechanisms underlying immunological progression despite HIV replication control, and eventually, for finding a functional cure through immune-based clinical trials.

Concerted regulation of renal plasma flow and glomerular filtration rate by renal dopamine and NOS I in rats on high salt intake.

Under high sodium intake renal dopamine (DA) increases while NOS I expression in macula densa cells (MD) decreases. To explore whether renal DA and NOS I, linked to natriuresis and to the stability of the tubuloglomerular feedback, respectively, act in concert to regulate renal plasma flow (RPF) and glomerular filtration rate (GFR). Male Wistar rats were studied under a normal sodium intake (NS, NaCl 0.24%) or a high sodium intake (HS, NaCl 1% in drinking water) during the 5 days of the study. For the last two days, the specific D1-like receptor antagonist SCH 23390 (1 mg kg bwt-1 day-1, sc) or a vehicle was administered. HS intake increased natriuresis, diuresis, and urinary DA while it decreased cortical NOS I expression (P < 0.05 vs. NS), Nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) activity in MD (P < 0.001 vs. NS) and cortical nitrates+nitrites (NOx) production (NS 2.04 ± 0.22 vs. HS 1.28 ± 0.10 nmol mg protein-1, P < 0.01). Treatment with SCH 23390 to rats on HS sharply decreased hydroelectrolyte excretion (P < 0.001 vs. HS) while NOS I expression, NADPH-d activity and NOx production increased (P < 0.05 vs. HS for NOS I and P < 0.001 vs. HS for NADPH-d and NOx). SCH 23390 increased RPF and GFR in HS rats (P < 0.01 HS+SCH vs. HS). It did not cause variations in NS rats. Results indicate that when NS intake is shifted to a prolonged high sodium intake, renal DA through the D1R, and NOS I in MD cells act in concert to regulate RPF and GFR to stabilize the delivery of NaCl to the distal nephron.

The Role of Endothelin System in Renal Structure and Function during the Postnatal Development of the Rat Kidney.

Renal development in rodents, unlike in humans, continues during early postnatal period. We aimed to evaluate whether the pharmacological inhibition of Endothelin system during this period affects renal development, both at structural and functional level in male and female rats. Newborn rats were treated orally from postnatal day 1 to 20 with vehicle or bosentan (Actelion, 20 mg/kg/day), a dual endothelin receptor antagonist (ERA). The animals were divided in 4 groups: control males, control females, ERA males and ERA females. At day 21, we evaluated renal function, determined the glomerular number by a maceration method and by morphometric analysis and evaluated possible structural renal alterations by three methods: 〈alpha〉-Smooth muscle actin (α-SMA) immunohistochemistry, Masson's trichrome and Sirius red staining. The pharmacological inhibition of Endothelin system with a dual ERA during the early postnatal period of the rat did not leads to renal damage in the kidneys of male and female rats. However, ERA administration decreased the number of glomeruli, the juxtamedullary filtration surface area and the glomerular filtration rate and increased the proteinuria. These effects could predispose to hypertension or renal diseases in the adulthood. On the other hand, these effects were more pronounced in male rats, suggesting that there are sex differences that could be greater later in life. These results provide evidence that Endothelin has an important role in rat renal postnatal development. However these results do not imply that the same could happen in humans, since human renal development is complete at birth.

Asma bronquial y Medicinas complementarias-alternativas / Bronchial Asthma and Complementary-Alternative Medicines

La frecuencia y patrones de uso de Medicinas Complementarias-Alternativas (MCA) entre pacientes con asma bronquial es desconocida en nuestro país. El objetivo de este trabajo fue evaluar el uso de MCA entre pacientes con asma y comparar sus características con quienes no usaban esos recursos. Materiales y métodos: Entre 30-6-2005 y 30-6-2012, 635 pacientes mayores de 16 años con diagnóstico de asma fueron evaluados mediante entrevistas cara a cara con su médico en tres centros de las ciudades de Buenos Aires y General Rodríguez. La encuesta tuvo el carácter de anónima y voluntaria e incluyó variables demográficas, el tiempo de evolución de la enfermedad, la obstrucción al flujo aéreo medido por espirometria, parámetros de severidad y niveles control del asma. Se interrogó sobre el uso de al menos una vez por el lapso de un mes de alguna MCA, el tiempo de uso, la utilización simultánea o no de medicina alopática (MA), el tipo de MCA elegida y el resultado obtenido. Resultados: No se registraron rechazos a participar en el estudio; 246/635 (38.7%) de los pacientes usaron MCA con un valor de mediana de 12 meses (rango 0-359); entre ellos, un 39% habían abandonado la MA y un 15% todavía recurrían a alguna MCA. En el grupo con MCA había pacientes de mayor edad, mayor presencia de mujeres, tiempos de evolución más prolongados, niveles más altos de severidad y menor frecuencia de asma controlada, frente al grupo sin uso de MCA. Los resultados principales fueron mejoría o sin cambios (46% cada uno). Las MCA más frecuentemente elegidas fueron hierbas, homeopatía, acupuntura y yoga, encontrándose diferencias significativas según características demográficas, el uso simultáneo de MA y el reporte de resultados. Conclusiones: El uso de MCA entre nuestros pacientes con asma se asemeja a otras experiencias internacionales. Sin embargo, se requieren nuevas encuestas multicéntricas para alcanzar un estudio más profundo sobre los patrones regionales y nacionales de uso de MCA.

The frequency and patterns of Complementary-Alternative Medicines (CAM) use among asthmatic patients are unknown in our country. The objective of this work was to evaluate the CAM use in asthmatic patients and to compare their characteristics with those of asthmatic patients who are not CAM users. Materials and methods: Between 30 June 2005 and 30 June 2012, 635 patients with a diagnosis of asthma older than 15 years were evaluated through face-to-face interviews carried out by their own physicians in three clinics of Buenos Aires and General Rodriguez cities. The interviews were anonymous and free, and included the registry of variables such as demographic characteristics, evolution time from onset, airway obstruction by spirometry, levels of severity and control measures. Patients were asked if they had used any CAM at least once by a minimum period of a month, time of the intervention, simultaneous or not use of allopathic medicine (AM), type of CAM chosen and self-reported results. Results: All patients agreed to co-operate, and 246/635 (38.7%) referred having used CAM for a median period of 12 months (range 0-359); while using the alternative treatment, 39% of them had abandoned the AM and 15% were still using any kind of CAM. In comparison with non users, alternative users tended to be older and females, and to have longer time from the onset of symptoms, higher levels of severity and lower periods of controlled asthma. The main reported results were improvement and no change (46% each). The mainly CAM chosen were herbs, homeopathy, acupuncture and yoga. Significant differences were found according to demographic characteristics, simultaneous use of AM and self-reported results. Conclusions: Use of CAM among our asthmatic patients appears to be similar to that reported in other international experiences. However, new multicenter surveys are needed to reach a deeper insight into both regional and national patterns of use.

Asma bronquial y Medicinas complementarias-alternativas

La frecuencia y patrones de uso de Medicinas Complementarias-Alternativas (MCA) entre pacientes con asma bronquial es desconocida en nuestro país. El objetivo de este trabajo fue evaluar el uso de MCA entre pacientes con asma y comparar sus características con quienes no usaban esos recursos. Materiales y métodos: Entre 30-6-2005 y 30-6-2012, 635 pacientes mayores de 16 años con diagnóstico de asma fueron evaluados mediante entrevistas cara a cara con su médico en tres centros de las ciudades de Buenos Aires y General Rodríguez. La encuesta tuvo el carácter de anónima y voluntaria e incluyó variables demográficas, el tiempo de evolución de la enfermedad, la obstrucción al flujo aéreo medido por espirometria, parámetros de severidad y niveles control del asma. Se interrogó sobre el uso de al menos una vez por el lapso de un mes de alguna MCA, el tiempo de uso, la utilización simultánea o no de medicina alopática (MA), el tipo de MCA elegida y el resultado obtenido. Resultados: No se registraron rechazos a participar en el estudio; 246/635 (38.7%) de los pacientes usaron MCA con un valor de mediana de 12 meses (rango 0-359); entre ellos, un 39% habían abandonado la MA y un 15% todavía recurrían a alguna MCA. En el grupo con MCA había pacientes de mayor edad, mayor presencia de mujeres, tiempos de evolución más prolongados, niveles más altos de severidad y menor frecuencia de asma controlada, frente al grupo sin uso de MCA. Los resultados principales fueron mejoría o sin cambios (46% cada uno). Las MCA más frecuentemente elegidas fueron hierbas, homeopatía, acupuntura y yoga, encontrándose diferencias significativas según características demográficas, el uso simultáneo de MA y el reporte de resultados. Conclusiones: El uso de MCA entre nuestros pacientes con asma se asemeja a otras experiencias internacionales. Sin embargo, se requieren nuevas encuestas multicéntricas para alcanzar un estudio más profundo sobre los patrones regionales y nacionales de uso de MCA.(AU)

The frequency and patterns of Complementary-Alternative Medicines (CAM) use among asthmatic patients are unknown in our country. The objective of this work was to evaluate the CAM use in asthmatic patients and to compare their characteristics with those of asthmatic patients who are not CAM users. Materials and methods: Between 30 June 2005 and 30 June 2012, 635 patients with a diagnosis of asthma older than 15 years were evaluated through face-to-face interviews carried out by their own physicians in three clinics of Buenos Aires and General Rodriguez cities. The interviews were anonymous and free, and included the registry of variables such as demographic characteristics, evolution time from onset, airway obstruction by spirometry, levels of severity and control measures. Patients were asked if they had used any CAM at least once by a minimum period of a month, time of the intervention, simultaneous or not use of allopathic medicine (AM), type of CAM chosen and self-reported results. Results: All patients agreed to co-operate, and 246/635 (38.7%) referred having used CAM for a median period of 12 months (range 0-359); while using the alternative treatment, 39% of them had abandoned the AM and 15% were still using any kind of CAM. In comparison with non users, alternative users tended to be older and females, and to have longer time from the onset of symptoms, higher levels of severity and lower periods of controlled asthma. The main reported results were improvement and no change (46% each). The mainly CAM chosen were herbs, homeopathy, acupuncture and yoga. Significant differences were found according to demographic characteristics, simultaneous use of AM and self-reported results. Conclusions: Use of CAM among our asthmatic patients appears to be similar to that reported in other international experiences. However, new multicenter surveys are needed to reach a deeper insight into both regional and national patterns of use.(AU)

Renal response to L-arginine in diabetic rats. A possible link between nitric oxide system and aquaporin-2.

The aim of this study was to evaluate whether L-Arginine (L-Arg) supplementation modifies nitric oxide (NO) system and consequently aquaporin-2 (AQP2) expression in the renal outer medulla of streptozotocin-diabetic rats at an early time point after induction of diabetes. Male Wistar rats were divided in four groups: Control, Diabetic, Diabetic treated with L-Arginine and Control treated with L-Arginine. Nitric oxide synthase (NOS) activity was estimated by [14C] L-citrulline production in homogenates of the renal outer medulla and by NADPH-diaphorase staining in renal outer medullary tubules. Western blot was used to detect the expression of AQP2 and NOS types I and III; real time PCR was used to quantify AQP2 mRNA. The expression of both NOS isoforms, NOS I and NOS III, was decreased in the renal outer medulla of diabetic rats and L-Arg failed to prevent these decreases. However, L-Arg improved NO production, NADPH-diaphorase activity in collecting ducts and other tubular structures, and NOS activity in renal homogenates from diabetic rats. AQP2 protein and mRNA were decreased in the renal outer medulla of diabetic rats and L-Arg administration prevented these decreases. These results suggest that the decreased NOS activity in collecting ducts of the renal outer medulla may cause, at least in part, the decreased expression of AQP2 in this model of diabetes and constitute additional evidence supporting a role for NO in contributing to renal water reabsorption through the modulation of AQP2 expression in this pathological condition. However, we cannot discard that another pathway different from NOS also exists that links L-Arg to AQP2 expression.

Expression and activity of SGLT2 in diabetes induced by streptozotocin: relationship with the lipid environment.

BACKGROUND/AIMS: Diabetes mellitus may impact on the regulation of renal Na+-glucose cotransporter type 2 (SGLT2), however, previous studies have yielded conflicting results on the effects of streptozotocin (STZ)-induced diabetes on SGLT-mediated glucose transport. METHODS: Diabetes was induced in male Wistar rats. The studies were performed at 3 (D3), 7 (D7) and 14 (D14) days after a single i.p. injection of STZ. SGLT2 activity was measured using alpha-14C-methyl glucose uptake in brush-border vesicles (BBV) from renal cortex, and SGLT2 expression was assessed by immunoblotting. Phospholipids were quantified by a modification of Fiske-Subarow's method after being separated by thin-layer chromatography. RESULTS: Glucose uptake was reduced in all groups of diabetic rats. SGLT2 expression decreased in D3 and D7. There was a decrease in sphingomyelin (SM) content and an increase in phosphatidylcholine (PC) content in BBV from D14 versus control, without differences in phosphatidylinositol (PI), phosphatidylserine (PS) and phosphatidylethanolamine (PE). CONCLUSION: The downregulation of SGLT2 activity during STZ-induced diabetes may be a protective mechanism to control the excess of circulating glucose and could be a consequence of a decrease in SGLT2 expression in D3 and D7, whereas altered activity of SGLT2 in D14 could be a consequence of changes in membrane lipid composition. However, we cannot discard the possibility that the decrease in SGLT2 activity could be due to a covalent modification of the active site of the protein.

Characteristics of smokers accessing the Puerto Rico Quitline.

BACKGROUND: In 2004, the Puerto Rico Department of Health implemented the Puerto Rico Quitline (PRQ), a proactive, telephone-based smoking cessation counseling program. This study examines the demographic and smoking-related characteristics of the individuals served by the PRQ. METHODS: Analyses included PRQ participants registered from December 2004-December 2005. PRQ call rates and rate ratios (RR) were calculated overall, among smokers, and stratified by relevant covariates. Associations between sex and relevant characteristics of PRQ participants were compared using regression models. RESULTS: Call rates per 100,000 smokers in PR were lower among men than women (RR = 0.50, 95% CI = 0.44-0.56), and higher among all age groups > or = 25 years of age as compared to those aged 15-24 years (RRs = 4.34-8.14) and among smokers living in the San Juan metropolitan area relative to smokers residing outside the metropolitan area (RR = 1.45, 95% CI = 1.29-1.63). Mass media was the most common way in which participants learned about the PRQ (> 70%), with only 2-3% of callers reporting a physician's referral as the source of their information about the PRQ. With respect to reasons for quitting, men were less likely than women to report concern about a child's health (OR = 0.62, 95% CI = 0.46-0.84) and cigarette odor (OR = 0.64, 95% CI = 0.41-0.99). Meanwhile, men were more likely (OR = 1.39, 95% CI = 1.01-1.91) to report the influence of other smokers as a barrier during quitting. CONCLUSIONS: PRQ promotion and outreach efforts should target populations underserved by the PRQ including male, young adult, and non-metropolitan area smokers. Initiatives that link the PRQ with primary care providers in promoting smoking cessation should be encouraged.

Effects of chronic L-NAME on nitrotyrosine expression and renal vascular reactivity in rats with chronic bile-duct ligation.

In liver cirrhosis, elevated levels of NO and ROS (reactive oxygen species) might greatly favour the generation of peroxynitrite. Peroxynitrite is a highly reactive oxidant and it can potentially alter the vascular reactivity and the function of different organs. In the present study, we evaluated whether peroxynitrite levels are related to the progression of renal vascular and excretory dysfunction during experimental cirrhosis induced by chronic BDL (bile-duct ligation) in rats. Experiments were performed at 7, 15 and 21 days after BDL in rats and in rats 21 days post-BDL chronically treated with L-NAME (N(G)-nitro-L-arginine methyl ester). Sodium balance, BP (blood pressure), basal RPP (renal perfusion pressure) and the renal vascular response to PHE (phenylephrine) and ACh (acetylcholine) in isolated perfused kidneys were measured. NO levels were calculated as 24-h urinary excretion of nitrites, ROS as TBARS (thiobarbituric acid-reacting substances), and peroxynitrite formation as the renal expression of nitrotyrosine. BDL rats had progressive sodium retention, and decreased BP, RPP and renal vascular responses to PHE and ACh in the time following BDL. They also had increasing levels of NO and ROS, and renal nitrotyrosine accumulation,especially in the medulla. All of these changes were either prevented or significantly decreased by chronic L-NAME administration. In conclusion, these results suggest that the increasing levels of peroxynitrite might contribute to the altered renal vascular response and sodium retention in the development of the experimental biliary cirrhosis. Moreover, the beneficial effects of decreasing NO synthesis are, at least in part, mediated by anti-peroxinitrite-related effects.

Renal sodium-glucose cotransporter activity and aquaporin-2 expression in rat kidney during chronic nitric oxide synthase inhibition.

BACKGROUND/AIMS: The renal sodium glucose cotransporter (SGLT2) and the water channel aquaporin-2 (AQP2) play a critical role in tubular sodium and water reabsorption and in the regulation of extracellular fluid volume both in physiologic and pathophysiologic conditions. However, there is little information about SGLT2 and AQP2 expression and/or activity in hypertension and there are no reports during hypertension induced by chronic nitric oxide synthase (NOS) inhibition. METHODS: Hypertension was induced in rats by oral administration of N(G)-nitro-L-arginine methyl ester (L-NAME) (20 mg/kg/24 h) for 6 (H6) or 12 (H12) weeks. SGLT2 activity was measured using alpha-(14)C-methylglucose active uptake. The expression level of transporters was assessed by immunohistochemistry and/or immunoblotting. RESULTS: SGLT2 activity was reduced in both H6 and H12; this was due neither to a decrease in SGLT2 expression nor to a change in membrane phospholipid composition. In H6, AQP2 expression diminished only in the inner medulla (IM), while in H12 it diminished in both outer (OM) and IM. This reduced expression of AQP2 may partially account for the increased urinary volume and decreased urinary osmolality in H12, since we obtained a strong correlation between AQP2 expression and these urinary parameters in both OM and IM. CONCLUSION: We propose that in rats in which hypertension is induced by NOS inhibition, SGLT2 activity and AQP2 expression are modified to compensate for the elevated arterial pressure. However, we cannot discount the possibility that the observed changes are due to the decrease in NO production itself.

The use of microcomputed tomography to study microvasculature in small rodents.

Appropriate nephron function is dependent on the intrarenal arrangement of blood vessels. The preferred and primary means to study the architecture of intrarenal circulation has been by filling it with opaque substances such as india ink, radio-opaque contrast material, or various polymers for study by light or scanning electron microscopy. With such methodologies, superficial vessels may obscure deep vessels and little quantitative information may be obtained. Serial-section microtomy has not been practical because of problems relating to alignment and registration of adjacent sections, lost sections, and preparation time and effort. Microcomputed tomography (micro-CT) overcomes such limitations and provides a means to study the three-dimensional architecture of filled vessels within an intact rodent kidney and to obtain more quantitative information. As an example of micro-CT's capabilities, we review the use of micro-CT to study the alterations in renal microvasculature caused by the development of liver cirrhosis after chronic bile duct ligation. In this example, micro-CT evidence shows a selective decrease in cortical vascular filling in the kidney, with a maintenance of medullary vascular filling. These changes may contribute to the salt and water retention that accompanies cirrhosis. These results indicate that micro-CT is a promising method to evaluate renal vascular architecture in the intact rodent kidney relative to physiological and pathological function.