RESUMO
Oxidative stress is related to the development of central nervous system diseases involving memory processes. Cholinergic system and memory processes are disrupted by ozone exposure. In rats, ozone induces motor disturbances and memory deficits as well as biochemical changes in brain regions related to memory processes. In this work, we analyzed the effect of chronic tibolone (TIB) administration in central nervous system, specifically the content of choline acetyltransferase, acetylcholinesterase, acetylcholine and oxidative stress markers in the hippocampus of male rats exposed to ozone. Our results reveal a neuroprotective effect of TIB treatment on neuronal damage induced by chronic ozone exposure. Furthermore, we suggest that TIB can prevent memory deficits by providing a protective effect against oxidative stress and the cholinergic system disruption induced by ozone exposure. Together, these findings present a potential neuroprotective effect of TIB in processes linked to memory deficits induced by aging or neurodegenerative diseases.
Assuntos
Neurônios Colinérgicos/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Norpregnenos/farmacologia , Ozônio/toxicidade , Animais , Masculino , Oxirredução , Estresse Oxidativo , Ratos , Ratos WistarRESUMO
Laparoscopic hernioplasty techniques have been developed in the recent years to avoid the recurrence of inguinal hernias and to spare the testicles for breeding purposes in stallions. However, there have been no previous comprehensive and systematic studies of the reproductive outcomes and prognoses for stallions after inguinal hernioplasty. Therefore, the objective of this study was to assess the possible effects of one of these techniques (standing laparoscopic peritoneal flap hernioplasty) on the sperm production and motility characteristics of six healthy stallions that received this procedure based on 1-year follow-ups. There were no significant differences in the measured sperm variables (assessments based on the DSO, MOT, PMOT, VSL, VCL and VAP) during 1-year follow-ups.
Assuntos
Herniorrafia/veterinária , Cavalos/fisiologia , Cavalos/cirurgia , Análise do Sêmen/veterinária , Espermatogênese/fisiologia , Animais , Herniorrafia/métodos , Masculino , Sêmen/fisiologia , Motilidade dos Espermatozoides/fisiologia , Espermatozoides/fisiologiaRESUMO
Streptococcus parauberis is known as an etiological agent of mastitis in cows and for producing streptococcosis in farmed fish, although its presence in foods has seldom been reported. In this work, two bacterial isolates were recovered from a spoiled vacuum-packaged refrigerated seafood product. Both isolates were identified by 16S rRNA gene sequencing, exhibiting 99% homology with respect to S. parauberis. Both isolates were also characterized by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS). Genetic analysis revealed the clonal homogeneity of the isolates and their grouping together with other S. parauberis strains in a different cluster with respect to Streptococcus uberis strains. Proteomic analysis by MALDI-TOF MS allowed for the identification of five mass peaks in the range of 2200-6000 m/z that resulted to be specific to the species S. parauberis and allowed its rapid and direct identification with respect to other pathogenic and spoilage bacteria potentially present in seafood and other food products. This study represents, to our knowledge, the first report of S. parauberis in seafood in general and in vacuum-packed food products in particular. Moreover, it provides a rapid method based on MALDI-TOF MS for the identification of S. parauberis.
Assuntos
Contaminação de Alimentos/análise , Embalagem de Alimentos/métodos , Alimentos Marinhos/microbiologia , Streptococcus/classificação , Streptococcus/isolamento & purificação , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , Microbiologia de Alimentos/métodos , Genótipo , Fenótipo , Proteômica , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Streptococcus/genética , VácuoRESUMO
BACKGROUND: To report two cases of eyelash loss in Frontal Fibrosing Alopecia, providing microscopic description of the eyelashes and possible association with Demodex folliculorum. CASE PRESENTATION: We present two cases of postmenopausal women diagnosed with frontal fibrosing alopecia who consulted the ophthalmology department for eyelid itching and eyelash loss. On examination, there were no signs of blepharitis, but loss of lashes was observed, and the remaining eyelashes detached easily from the eyelid. The eyelashes were examined microscopically. The bulbs were small and narrow, and the caliber of the lashes was irregular, with thinner and thicker areas. The pigment distribution was irregular; there were portions with greater or lesser accumulation. In the second case, clusters of Demodex folliculorum were observed near the eyelash root. CONCLUSION: This is the first microscopic description of eyelash loss in frontal fibrosing alopecia in the published literature. We describe small, narrow bulbs, irregular caliber of the eyelashes and irregular pigment distribution. In the second case, in which we found Demodex folliculorum infestation, there was eyelash loss even though the disease was not very advanced. We suggest that there might be an association whereby Demodex infestation might accelerate autoimmune inflammation, leading to premature eyelash loss.
Assuntos
Blefarite , Pestanas , Infestações por Ácaros , Alopecia/diagnóstico , Feminino , Humanos , InflamaçãoRESUMO
Stress is a state of vulnerable homeostasis that alters the physiological and behavioral responses. Stress induces oxidative damage in several organs including the brain, liver, kidney, stomach, and heart. Preliminary findings suggested that the magnetic stimulation could accelerate the healing processes and has been an effective complementary therapy in different pathologies. However, the mechanism of action of static magnetic fields (SMFs) is not well understood. In this study, we demonstrated the effects of static magnetic fields (0.8 mT) in a restraint stressed animal model, focusing on changes in different markers of oxidative damage. A significant increase in the plasma levels of nitric oxide (NO), malondialdehyde (MDA), and advanced oxidation protein products (AOPP), and a decrease in superoxide dismutase (SOD), glutathione (GSH), and glycation end products (AGEs) were observed in restraint stress model. Exposure to SMFs over 5 days (30, 60, and 240 min/day) caused a decrease in the NO, MDA, AGEs, and AOPP levels; in contrast, the SOD and GSH levels increased. The response to SMFs was time-dependent. Thus, we proposed that exposure to weak-intensity SMFs could offer a complementary therapy by attenuating oxidative stress. Our results provided a new perspective in health studies, particularly in the context of oxidative stress.
Assuntos
Produtos da Oxidação Avançada de Proteínas/metabolismo , Glutationa/metabolismo , Produtos Finais de Glicação Avançada/metabolismo , Campos Magnéticos , Malondialdeído/metabolismo , Óxido Nítrico/metabolismo , Estresse Oxidativo , Superóxido Dismutase/metabolismo , Animais , Biomarcadores/metabolismo , Ratos , Ratos Wistar , Restrição FísicaRESUMO
The antioxidant effectiveness of two different families of phenolic compounds, hydroxycinnamic acids and catechins, added as a power (0.001% w/w) to chilled minced horse mackerel muscle was evaluated. Caffeic acid, chlorogenic acid, o-coumaric acid, and ferulic acid were selected as hydroxycinnamic acids with similar molecular structures. Commercial catechins with different numbers of hydroxylic groups, including catechin, gallocatechin, catechin gallate, and gallocatechin gallate, were also tested. The effectiveness found was individually discussed for each family as a function of the molecular structure. The capacity of hydroxycinnamic acids for donating electrons seems to play the most significant role for retarding the development of rancidity in fish muscle. Conversely, the properties related to the ability for chelating metals and the distribution between oily and aqueous phases were not correlated with the inhibitory activities. Among hydroxycinnamic acids, the results highlighted the potent antioxidant activity of 10 ppm caffeic acid in inhibiting lipid oxidation in fish muscle. Its antioxidant efficacy was similar to that of propyl gallate. Among catechins, catechin showed the highest antioxidant activity. There was an increment of efficacy in fish muscle using concentrations ranging between 10 and 100 ppm of both caffeic acid and catechin.
Assuntos
Antioxidantes/química , Antioxidantes/farmacologia , Catequina/farmacologia , Ácidos Cumáricos/farmacologia , Peixes , Músculos/efeitos dos fármacos , Animais , Catequina/química , Temperatura Baixa , Ácidos Cumáricos/química , Carne/análise , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
PURPOSE: Cataract surgery rates have dramatically increased in the last two decades. However, clinical practice variation in cataract surgery has not been thoroughly studied. The aim of this review is to analyze clinical practice variation, including the causes and consequences of this phenomenon. Then, its role in health care planning and health care quality is focused, emphasizing the importance of reducing it and providing several practical strategies to accomplish it. RECENT FINDINGS: The latest researches are presented in this article. They identify the development and implementation of clinical practice guidelines as the best tool to standardize care processes. CONCLUSION: Managing unwarranted or unwanted variation would improve quality of care and may lead to a significant saving in health care spending.
Assuntos
Extração de Catarata , Padrões de Prática Médica , Extração de Catarata/métodos , Extração de Catarata/estatística & dados numéricos , Saúde Global , Planejamento em Saúde , Necessidades e Demandas de Serviços de Saúde , Humanos , Guias de Prática Clínica como Assunto , Padrões de Prática Médica/estatística & dados numéricos , Qualidade da Assistência à Saúde , Resultado do TratamentoRESUMO
Frozen sections of normal Balb/c corneas and corneas from Balb/c mice with Klebsiella keratoconjunctivitis were examined for the expression of class I, class II H-2 antigens and MAC-1 antigens using monoclonal antibodies in an immunoperoxidase technique. Class I antigens were readily detected, in both normal and diseased corneas, mainly in the epithelium. Class II (Ia) and MAC-1 antigens were not detected in the normal corneas. However, these two antigens were found mainly in the epithelium and to a lesser extent in the stroma of corneas from keratoconjunctivitis mice. Both normal and diseased corneas were furthermore shown to be peroxidase-. Since Langerhans cells (LC) are Ia+, MAC-1+, and peroxidase- cells, we conclude that although the normal mouse cornea is devoid of these cells, under bacterial infection LC infiltrate the corneal epithelium.
Assuntos
Córnea/patologia , Ceratoconjuntivite/etiologia , Infecções por Klebsiella , Células de Langerhans/patologia , Animais , Antígenos/análise , Ceratoconjuntivite/imunologia , Ceratoconjuntivite/patologia , Complexo Principal de Histocompatibilidade , Camundongos , Camundongos Endogâmicos BALB CRESUMO
We describe a case of laryngeal amyloidoma in a 39-year-old man in whom CT examination disclosed a calcifield soft-tissue mass arising in the epiglottis. The presence of focal calcifications suggested a cartilaginous tumor.
Assuntos
Amiloidose/diagnóstico por imagem , Calcinose/diagnóstico por imagem , Doenças da Laringe/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Adulto , Condrossarcoma/diagnóstico , Diagnóstico Diferencial , Epiglote/diagnóstico por imagem , Humanos , Neoplasias Laríngeas/diagnóstico , Laringoscopia , Imageamento por Ressonância Magnética , MasculinoRESUMO
We present a patient with acute and severe abdominal pain, fever and mild tenderness elicited on deep palpation in the right lower quadrant. X-ray films of the chest and abdomen were normal. The ultrasonographic study, barium enema examination and colonoscopic study avoided a diagnostic laparotomy. A purified protein skin test (PPD) and the cultures on Lowestein medium were negative. The final diagnosis was ulcero-hipertrophic tuberculosis of the ascending colon, and was confirmed by the finding of positive acid fast facilli and granulomas with Langerhans cells in the colonic biopsy material. The colonic lesions disapplared at the end of the antituberculous treatment.
Assuntos
Doenças do Colo/diagnóstico , Colonoscopia , Tuberculose Gastrointestinal/diagnóstico , Idoso , Humanos , MasculinoRESUMO
The study innovatively pinpoints target proteins of carbonylation, a key PTM induced by oxidative stress, in the SHROB (genetically obese spontaneously hypertensive) rat model of metabolic syndrome (MetS). Protein carbonylation was assessed by a fluorescence-labeling proteomics approach, and complemented with biometric and biochemical markers of MetS. SHROB and healthy Wistar rats were fed two diets, soybean and linseed oil supplementations, in order to distinguish intrinsic carbonylation of SHROB animals from diet-modulated carbonylation unrelated to MetS. First exploratory data showed similar carbonylation patterns and metabolic conditions in SHROB rats fed soybean and linseed, but different from Wistar animals. A total of 18 carbonylated spots in liver, and 12 in skeletal tissue, related to pathways of lipid (29.6%), carbohydrate (25.9%) and amino acid (18.5%) metabolisms, were identified. In particular, SHROB animals present higher carbonylation in four liver proteins belonging to lipid metabolism, redox regulation and chaperone activity (ALDH2, PDI, PDIA3, PECR), and in the skeletal muscle ALDOA that is involved in muscle dysfunction. Conversely, SHROB rats display lower carbonylation in liver albumin, AKR1C9, ADH1 and catalase. This investigation provides a novel perspective of carbonylation in the context of metabolic disorders, and may be a starting point to characterize new redox pathways exacerbating MetS. BIOLOGICAL SIGNIFICANCE: Oxidative stress is a concomitant factor in the pathogenesis of MetS that induces oxidative PTM as carbonylation. Through the use of a redox proteomics approach, we have thoroughly mapped the occurrence of protein targets of carbonylation in the genetically-induced MetS model SHROB rat. The present research brings a new insight of MetS pathogenesis and it may provide valuable information to understand the biological impact of oxidative stress in patients with MetS.
Assuntos
Síndrome Metabólica/metabolismo , Estresse Oxidativo , Carbonilação Proteica , Animais , Antioxidantes/metabolismo , Carbono/metabolismo , Catalase/metabolismo , Cromatografia Líquida , Biologia Computacional , Eletroforese em Gel de Poliacrilamida , Feminino , Linho , Resistência à Insulina , Metabolismo dos Lipídeos , Fígado/metabolismo , Músculo Esquelético/metabolismo , Obesidade/metabolismo , Oxirredução , Oxigênio/metabolismo , Proteômica , Ratos , Ratos Endogâmicos SHR , Ratos Wistar , Glycine max , Espectrometria de Massas em TandemRESUMO
OBJECTIVE: To assess the intra- and interobserver reproducibility of musculoskeletal ultrasonography (US) in detecting inflammatory shoulder changes in patients with rheumatoid arthritis, and to determine the agreement between US and the Shoulder Pain and Disability Index (SPADI) and the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire, using magnetic resonance imaging (MRI) as a gold standard. METHODS: Eleven rheumatologists investigated 10 patients in 2 rounds independently and blindly of each other by US. US results were compared with shoulder function tests and MRI. RESULTS: The positive and negative predictive values (NPVs) for axillary recess synovitis (ARS) were 0.88 and 0.43, respectively, for posterior recess synovitis (PRS) were 0.36 and 0.97, respectively, for subacromial/subdeltoid bursitis (SASB) were 0.85 and 0.28, respectively, and the NPV for biceps tenosynovitis (BT) was 1.00. The intraobserver kappa was 0.62 for ARS, 0.59 for PRS, 0.51 for BT, and 0.70 for SASB. The intraobserver kappa for power Doppler US (PDUS) signal was 0.91 for PRS, 0.77 for ARS, 0.94 for SASB, and 0.53 for BT. The interobserver maximum kappa was 0.46 for BT, 0.95 for ARS, 0.52 for PRS, and 0.61 for SASB. The interobserver reliability of PDUS was 1.0 for PRS, 0.1 for ARS, 0.5 for BT, and 1.0 for SASB. P values for the SPADI and DASH versus cuff tear on US were 0.02 and 0.01, respectively; all other relationships were not significant. CONCLUSION: Overall agreements between gray-scale US and MRI regarding synovitis of the shoulder varied considerably, but excellent results were seen for PDUS. Measures of shoulder function have a poor relationship with US and MRI. Improved standardization of US scanning technique could further reliability of shoulder US.
Assuntos
Artrite Reumatoide/diagnóstico por imagem , Sinovite/diagnóstico por imagem , Ultrassonografia Doppler , Adulto , Braço/diagnóstico por imagem , Braço/patologia , Artrite Reumatoide/patologia , Bursite/diagnóstico por imagem , Bursite/patologia , Feminino , Mãos/diagnóstico por imagem , Mãos/patologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Reprodutibilidade dos Testes , Ombro/diagnóstico por imagem , Ombro/patologia , Sinovite/patologia , Tenossinovite/diagnóstico por imagem , Tenossinovite/patologiaRESUMO
We present the case of a patient presenting at the emergency department with subacute low back pain radiating to both lower limbs in whom ultrasonography and abdominal computed tomography diagnosed a retroperitoneal adenopathic mass compressing the inferior vena cava. Magnetid resonance imagin of the lumbar spine showed the retroperitoneal mass and also showed dilatation and tortuosity of the vessels of the lumbar epidural venous plexus, which was considered responsible for the radiating low back pain. Histological study defined the retroperitoneal mass as follicular non-Hodgkin's lymphoma. The dilatation of the lumbar epidural venous plexus can cause lumbar and radicular pain.
Assuntos
Dor Lombar/etiologia , Linfoma não Hodgkin/complicações , Neoplasias Retroperitoneais/complicações , Veia Cava Inferior , Dilatação Patológica , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
We report 2 cases of trichinosis in which the clinical features resembled dermatomyositis. In both cases, however, the diagnosis was established histologically by demonstrating trichina larvae in the patients' muscle biopsies. Indirect immunofluorescence and counterimmunoelectrophoresis techniques were used to confirm the diagnosis serologically.
Assuntos
Dermatomiosite/etiologia , Triquinelose , Adulto , Dermatomiosite/patologia , Feminino , Humanos , Masculino , Músculos/microbiologia , Músculos/patologia , Síndrome , Trichinella/isolamento & purificação , Triquinelose/microbiologiaRESUMO
Textile plants are very important sources of toxic discharges. The purpose of the research described in this paper was to use bioassays with daphnids to determine the LC50 values of textile wastewater samples taken from different stages of the finishing textile industry. Toxicity due to dyeing, chlorination, and the absence of adequate physicochemical conditions for daphnid survival were considered. Wastewater samples corresponding to each process stage were collected at five finishing textile industries and assayed according to previously published procedures. The sensitivity of daphnids to chemicals was assayed using sodium dodecyl sulfate and was similar to other reports (14.6+/-6.8 vs 14.5+/-2.3 mg/L). All effluents from the five company samples were toxic in terms of LC50 and exhibited very high toxicity with acute toxicity unit (ATU) levels between 2.2 and 960, indicating that the five textile industries produced toxic water. The sensory characteristics indicated that the dyes contributed to overall sample toxicity at all process stages. The most toxic contaminant seemed to be ClO- at levels between 0.2 and 6.8 mg/L, suggesting that further research is needed on the economic costs of stage-by-stage and total effluent treatments.
Assuntos
Monitoramento Ambiental/métodos , Indústria Têxtil , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/toxicidade , Animais , Cloro/toxicidade , Corantes/toxicidade , Daphnia/efeitos dos fármacos , Daphnia/fisiologia , Dose Letal Mediana , Testes de ToxicidadeRESUMO
The Merluccidae family comprises marine species, some of them of high commercial value and others less appreciated, whose commercialization in Europe under the generic name of "hake" is highly remarkable. The potential of proteomics was employed in this study with the aim of achieving the differential characterization of five different hake species: Merluccius merluccius (European hake), M. australis (Southern hake), M. hubbsi (Argentinian hake), M. gayi (Chilean hake), and M. capensis (Cape hake), some of them very closely related. Species-specific polypeptides were observed for the five hake species studied in isoelectric focusing (IEF) and/or two-dimensional electrophoresis (2-DE) high-resolution gels. The peptide mass maps of two polypeptide groups, previously selected by 2-DE analysis as potentially species-specific, were obtained by "in-gel" tryptic digestion, followed by matrix assisted laser desorption/ ionization-time of flight-mass spectrometry (MALDI-TOF-MS). Analysis of group A polypeptides (with pI in the range of 5.0-5.5 and molecular mass of 17 kDa), allowed the differential classification of the hake species into two groups: the East Atlantic coast group and the West Atlantic coast group. Moreover, the peptide mass-maps from the heat-resistant parvalbumin fraction (pI below 4.5; molecular mass <12 kDa) allowed the detection of a peptide characteristic of M. australis not present in the other four hake species tested. A specific 17 kDa protein from M. merluccius was also partially sequenced by nanospray-ion trap-tandem MS, revealing a high homology with rat nucleoside diphosphate kinase A (NDKA). This work opens the way to the application of proteomics to the differential characterization of commercial hake species at the molecular level.
Assuntos
Peixes , Proteínas Musculares/análise , Núcleosídeo-Difosfato Quinase/análise , Peptídeos/análise , Retículo Sarcoplasmático/química , Sequência de Aminoácidos , Animais , Eletroforese em Gel Bidimensional/métodos , Peixes/classificação , Dados de Sequência Molecular , Análise de Sequência , Especificidade da Espécie , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodosRESUMO
The effects of cooking and sterilization at several temperatures on the free amino acids (FAA) content in albacore (Thunnus alalunga) muscle were studied during the processing of canned tuna. FAAs were derivatized with o-phthalaldehyde, separated on a C18 column by HPLC and detected by both fluorescence and ultra-violet detectors. After cooking the loss of FAAs was not significant. However, in the final product sterilized at 115 degrees C and 110 degrees C (throughout the whole process) there were significant losses with regard to the start material, but not at 118 degrees C (all temperatures leading to the same lethal F-value). The influence of the thermal process time at 115 degrees C was evaluated for 60 and 100 min. Significant losses were found between both canned products (approximately 25%) and between the raw fish and the final product (approximately 12% and approximately 34%, process time 60 and 100 min, respectively). The determination of the content of FAA present in canned albacore may be a useful indication of the severity of the thermal processing.
Assuntos
Aminoácidos/análise , Peixes , Manipulação de Alimentos , Conservação de Alimentos , Músculos/análise , Atum , Animais , Cromatografia Líquida de Alta Pressão , Temperatura AltaRESUMO
The state-of-the-art and future trends of the application of proteomics to seafood and other marine products are reviewed. Consumers' demands for seafood products have increased in the recent years and this situation has underlined the need to guarantee the safety, traceability, authenticity, and health benefits of such products. The increasing presence of commercially available aquaculture products has also prompted the seafood industry to face newer challenges. In this sense, a review of the present status and perspectives of the application of proteomics in the development of newer biotechnology products of marine origin is given.
Assuntos
Biologia Marinha/métodos , Proteômica/métodos , Alimentos Marinhos/análise , Alérgenos/análise , Controle de Qualidade , Alimentos Marinhos/normas , Toxinas Biológicas/análiseRESUMO
The kinetics of thermal degradation of thiamine and surface colour (lightness measured as Hunter L-value) in canned white tuna were determined using an unsteady-state experimental procedure. Kinetic parameters were calculated by weighted non-linear regression considering a first-order kinetic model with a dependence of the kinetic coefficient (D) with temperature of the Thermal Death Time (TDT) type. Mass-average retentions of thiamine were calculated using a mathematical model which takes into account the non-uniform and unsteady distribution of temperature inside the container during thermal processing. The high correlation obtained between the predicted and the observed retention values and the small confidence intervals found for the kinetic parameters indicate a high statistical reliability. The kinetic model thus determined permits the simulation and optimization of the process resulting in a better quality of the final product.
Assuntos
Conservação de Alimentos , Temperatura Alta/efeitos adversos , Tiamina/metabolismo , Atum , Animais , Simulação por Computador , Cinética , Modelos Químicos , Pigmentação , Análise de Regressão , SoftwareRESUMO
We prepare an extract of dog urine (DLU) that, when applied to monolayers of MDCK cells (epithelial, derived from a normal dog), enhances the transepithelial electrical resistance (TER) in a dose-dependent manner. This increase is not reflected in variations of the linear amount of TJ nor in changes of the pattern of junctional strands as observed in freeze fracture replicas, nor in the distribution of claudin 1 (a membrane protein of the TJ) nor ZO-1 (a TJ-associated protein). A preliminary characterization of the active component of DLU indicates that it weighs 30-50 kDa, bears a net negative electric charge, and is destroyed by type I protease but not by 10-min boiling. DLUs prepared from human, dog, rabbit and cat are effective on MDCK cells. However, dog DLU increases TER in MDCK (dog) as well as LLCPK1 (pig) monolayers, but not in other epithelial cell lines such as LLCRK1 (rabbit), PTK2 (kangaroo) and MA-104 (monkey), nor in the endothelial cell line CPA47 (cow). Given that in its transit from the glomerulus to the urinary bladder the filtrate increases its concentration by more than two orders of magnitude, the substance(s) we report may act at increasingly higher concentrations in each segment, and afford a potential clue to the progressive increase of TER across the walls of the nephron from the proximal to the collecting duct.