SSCP analysis of paraffin wax embedded tissues in a family with an atypical form of Fabry disease

To investigate the distribution of a single base pair mutation within a family with one known case of Fabry disease, DNA from paraffin wax embedded necropsy material was studied using single-strand conformation polymorphism (SSCP) analysis. The proband, who presented with an atypical form of Fabry disease, had a G to A transition in exon 6 of the alpha-galactosidase A gene. This patient had mainly cardiac symptoms and late onset disease. Further cases of coronary disorders occurred in this family, including the proband's brother who died at 42 years of age of a cardiac disorder. Formalin fixed, paraffin wax embedded material from the brother and two more distant relatives was available for analysis. SSCP analysis showed that the proband's brother also carried the G to A transition. Thus, the atypical form of Fabry disease and unrelated cardiac diseases with similar clinical symptoms occurred within a single family. The variant form is rare but may account for a few of the numerous cases of cardiac disease in men and should be considered when clusters of cases of cardiac disease occur within a single family.

Influence of ET(B) receptor antagonism on pregnancy outcome in rats

OBJECTIVE

To determine the effect of endothelin-B (ET(B))-selective receptor antagonism on pregnancy outcome in normal rats.

METHODS

ET(B) receptor antagonist (A-192621; 5.0, 10.0, and 15.0 mg/kg per day) or vehicle was infused subcutaneously for 7 days by osmotic pump. Infusion was begun on day 14 of a 22-day gestation. Nonpregnant animals were treated similarly, and blood pressure (BP) responses and plasma antagonist levels were compared to those in pregnant animals. Mean arterial pressure (MAP) was measured on days 1, 4, and 7 of the infusion. Plasma ET(B) antagonist levels were measured on day 7 of infusion. On gestational day 21, fetal and placental weights and viability were evaluated at hysterotomy. Data were analyzed by analysis of variance and are presented as mean +/- standard error of the mean.

RESULTS

Fetal and placental weights were significantly lower at doses of 10 and 15 mg/kg per day of the ET(B) antagonist compared with vehicle-treated controls (P <.001); these effects were less severe at 15 than at 10 mg/kg per day despite a fourfold higher plasma level of antagonist. Mean arterial pressure was significantly higher at 10 and 15 mg/kg per day compared with controls, but only on infusion day 1 (P <.05). In contrast, MAPs for nonpregnant rats were elevated throughout the infusion at all doses of the ET(B) antagonist (P <.05).

CONCLUSIONS

ET(B) receptor antagonism inhibited fetal growth and increased maternal MAP in a dose-dependent manner, although the effect on BP was not sustained in pregnant animals. ET(B) receptor antagonism is detrimental to pregnancy outcome in the rat.

Risk and patterns of bacteraemia after splenectomy: a population-based study

During a period in which vaccination of splenectomized patients has been recommended, we analysed the patterns of severe post-splenectomy infections (i.e. bacteraemia or meningitis) in a defined population-based cohort. A total of 561 patients undergoing splenectomy were identified during 1984-93 in a Danish county, and the 538 eligible patients were followed for 1731 person-years. After splenectomy, 38 patients contracted a bacteraemia, of which 45% occurred within 30 d (i.e. during the postoperative period). No cases of meningitis were found. Among splenectomized patients the incidence rate of bacteraemia was 2.3 per 100 person-years at risk. Beyond the postoperative period we found an 8-fold increased risk of bacteraemia. Enterobacteria were the predominant cause (45%), and only 1 case due to Streptococcus pneumoniae was recorded. 89 (17%) died during the postoperative period, and the overall mortality rate was 18.4 per 100 person-years at risk. In all, 60% of the patients had been given a pneumococcal vaccination, and a Cox proportional hazard regression model showed that vaccination significantly reduced the risk of bacteraemia of any cause beyond the postoperative period. We conclude that splenectomy increases the risk of severe infections, and that vaccinated patients carry a lower risk of infection than non-vaccinated ones.

Fetal growth and blood pressure in a Danish population aged 31-51 years

During the past decade, studies have shown an inverse association between birth weight and blood pressure and risk of coronary heart disease in adult life. From old public archives we were able to trace the birth records of 545 out of 905 persons (60.2%) aged 31-51 years who participated in the Ebeltoft Health Promotion Project in Denmark. We examined the associations between birth weight, length at birth, Ponderal Index and systolic and diastolic blood pressure. No associations were found for women. For men, the mean systolic blood pressure fell from 131.1 mmHg with a birth weight of less than 3300 g to 129.6 mmHg with a birth weight of more than 4000 g, and for diastolic blood pressure 81.6 mmHg to 80.3 mmHg, respectively. For men, the mean systolic blood pressure fell from 135.7 mm Hg with a birth length of 30-51 cm to 131.6 with a birth length of 55-62 cm, and for diastolic blood pressure 83.0 mmHg to 78.8 mmHg, respectively. The associations may reflect organ programming in fetal life.

[Use of antiretroviral chemoprophylaxis after occupational HIV exposure]

The study describes the use of postexposure antiretroviral prophylaxis (PEP) after occupational exposure to HIV in Denmark in the period 1/1 1997-31/12 1998. Forty-seven accidentally exposed persons received PEP in this period, of whom 14 were nurses, 13 physicians and 11 were not employed in the health care system. In 23 cases side effects to PEP were described. In 18 cases the index person was i.v. drug abuser and in 11 cases homosexual/bisexual men. In 18 cases the HIV status of the index person was unknown at the time of exposure. Ten of these index persons were subsequently tested and all found HIV-negative. It is concluded, that the frequency of occupational exposure to HIV is unacceptably high. Further it is emphasised that in cases where the HIV status of the index person is unknown, PEP should only be instituted if the index person is at risk of being HIV infected and has signs of HIV infection.

Developmental expression of aquaporin 1 in the rat renal vasculature

Aquaporin 1 (AQP-1) is a water channel protein that is constitutively expressed in renal proximal tubule and descending thin limb cells as well as in endothelial cells of the descending vasa recta. Studies in the developing rat kidney have demonstrated that AQP-1 is expressed in renal tubules before birth. However, nothing is known about the expression of AQP-1 in the renal vasculature during kidney development. The purpose of this study was to establish the distribution of AQP-1 in the renal vasculature of the developing rat kidney and follow the differentiation of the vascular system during kidney development. Kidneys from 16-, 17-, 18-, and 20-day-old fetuses and 1-, 4-, 7-, 14-, 21-, and 28-day-old pups were preserved and processed for immunohistochemical studies using a preembedding immunoperoxidase procedure. AQP-1 immunoreactivity was detected using affinity-purified rabbit polyclonal antibodies to AQP-1. AQP-1 was expressed throughout the arterial portion of the renal vasculature of the fetal and neonatal kidney from gestational age 17 days to 1 wk after birth. AQP-1 immunoreactivity gradually disappeared from the renal vasculature between 1 and 2 wk of age and remained only in the descending vasa recta. In contrast, AQP-1 immunoreactivity was not observed in lymphatic vessels until 3 wk of age and persisted in the adult kidney. AQP-1 was also expressed in a population of interstitial cells in the terminal part of the renal papilla at 3 wk of age as well as in the adult kidney. The transient expression of AQP-1 in the arterial portion of the renal vasculature in the developing rat kidney suggests that AQP-1 is important for fluid equilibrium and/or drainage in the developing kidney or, alternatively, plays a role in the regulation of growth and/or branching of the vascular tree during kidney development.

Angiotensin II-stimulated nitric oxide release from porcine pulmonary endothelium is mediated by angiotensin IV

In this study, a nitric oxide (NO) sensor was used to examine the ability of angiotensin II (AngII), AngIV, and bradykinin (Bk) to stimulate NO release from porcine pulmonary artery (PPAE) and porcine aortic endothelial (PAE) cells and to explore the mechanism of the AngII-stimulated NO release. Physiologic concentrations of AngII, but not Bk, caused release of NO from PPAE cells. In contrast, Bk, but not AngII, stimulated NO release from PAE cells. AngIII-stimulated NO release from PPAE cells required extracellular L-arginine and was inhibited by L-nitro-arginine methyl ester. AT1 and AT2 receptor inhibition had no affect on AngII-mediated NO release or activation of NO synthase (NOS). AngIV, an AngII metabolite with binding sites that are pharmacologically distinct from the classic AngII receptors, stimulated considerably greater NO release and greater endothelial-type constitutive NOS activity than the same amount of AngII. The AngIV receptor antagonist, divalinal AngIV, blocked both AngII- and AngIV-mediated NO release as well as NOS activation. The results demonstrate that AngIV and the AngIV receptor are responsible, at least in part, for AngII-stimulated NO release and the associated endothelium-dependent vasorelaxation. Furthermore, these results suggest that differences exist in both AngII- and Bk-mediated NO release between PPAE and PAE cells, which may reflect important differences in response to these hormones between vascular beds.

Secular trends in incidence and mortality of bacteraemia in a Danish county 1981-1994

We estimated the incidence and mortality of bacteraemia in the County of North Jutland and examined factors that could explain the changes observed. A population-based survey of bacteraemia was conducted in the Danish County of North Jutland during 1981-1994. Data were retrieved from a regional bacteraemia register. The mortality was determined through linkage to the Danish Civil Registration System. A total of 7198 bacteraemias were detected, and the annual incidence increased from 76 per 100,000 person-years in 1981 to 153 in 1994. One major determining factor was a change in blood culture system with a higher volume of blood per sample, but annual numbers of blood cultures also increased. The 30-day mortality rate increased from 17 to 40 per 100,000 person-years during the study period, whereas the case-fatality rate remained constant (23.6%; 95% confidence intervals 22.6%-24.6%). The number of bacteraemias increased significantly. This observation could be explained only partly by changes in demography, in blood culture system, and in diagnostic activity. The case fatality rate remained constant despite the fact that more people were diagnosed with bacteraemia; this indicates that, with recent blood culture practice, more clinically significant bacteraemias are diagnosed.

Intercalated cell subtypes in connecting tubule and cortical collecting duct of rat and mouse

At least two populations of intercalated cells, type A and type B, exist in the connecting tubule (CNT), initial collecting tubule (ICT), and cortical collecting duct (CCD). Type A intercalated cells secrete protons via an apical H+-ATPase and reabsorb bicarbonate by a band 3-like Cl-/HCO3-exchanger, AE1, located in the basolateral plasma membrane. Type B intercalated cells secrete bicarbonate by an apical Cl-/HCO3- exchanger that is distinct from AE1 and remains to be identified. They express H+-ATPase in the basolateral plasma membrane and in vesicles throughout the cytoplasm. A third type of intercalated cell with apical H+-ATPase, but no AE1, has been described in the CNT and CCD of both rat and mouse. The prevalence of the third cell type is not known. The aim of this study was to characterize and quantify intercalated cell subtypes, including the newly described third non A-non B cell, in the CNT, ICT, and CCD of the rat and mouse. A triple immunolabeling procedure was developed in which antibodies to H+-ATPase and band 3 protein were used to identify subpopulations of intercalated cells, and segment-specific antibodies were used to identify distal tubule and collecting duct segments. In both rat and mouse, intercalated cells constituted approximately 40% of the cells in the CNT, ICT, and CCD. Type A, type B, and non A-non B intercalated cells were observed in all of the three segments, with type A cells being the most prevalent in both species. In the mouse, however, non A-non B cells constituted more than half of the intercalated cells in the CNT, 39% in the ICT, and 22% in the CCD, compared with 14, 7, and 5%, respectively, in the rat. In contrast, type B intercalated cells accounted for only 8 to 16% of the intercalated cells in the three segments in the mouse compared with 26 to 39% in the rat. It is concluded that striking differences exist in the prevalence and distribution of the different types of intercalated cells in the CNT, ICT, and CCD of rat and mouse. In the rat, the non A-non B cells are fairly rare, whereas in the mouse, they constitute a major fraction of the intercalated cells, primarily at the expense of the type B intercalated cells.

Trend in incidence and case fatality of meningococcal disease over 16 years in Northern Denmark

The incidence and case fatality rates of meningococcal disease were assessed in the county of Northern Jutland, Denmark, during the 16-year period from 1980 to 1995. A total of 320 patients were identified from the Meningococcal Research Database, which comprises information from the following sources: (i) the Department of Public Health, to whom notification of meningococcal disease is obligatory; (ii) the Regional Hospital Discharge Registry; and (iii) the register of the regional department of clinical microbiology. In order to assess prognostic indicators assessable at admission, information was collected for each patient from hospital records regarding contacts, symptoms and signs on arrival, laboratory data, and course of disease. The mean incidence was 4.3 cases per 100000 persons per year (range, 2.7-7.7). The incidence increased slightly during the period studied. Overall, the case fatality rate was 9.7%, with a significant rise occurring during the period (P=0.016) and a peak occurring in 1992. Advanced age (> or = 50 years), seizures, impaired consciousness, and skin bleeding on arrival at hospital were predictors of death.

The risk of bacteremia in patients with monoclonal gammopathy of undetermined significance

We estimated the risk of bacteremia in patients with monoclonal gammopathy of undetermined significance (MGUS) compared with the general population; 1237 cases of MGUS were identified by linking information on detected monoclonal components in the North Jutland County with the Danish Cancer Registry. We evaluated the risk of bacteremia in the MGUS cohort during the 13-yr period from 1981 to 1993 by linkage to the Bacteremia Registry in the County. Follow-up for the occurrence of bacteremia started 30 d after detection of the M-component and continued until malignant transformation, death or until 31 December 1993, whichever came first. The expected numbers of bacteremia was based upon county, age, sex and period-specific incidence rates. The median follow-up period was 3.8 yr. Forty episodes of bacteremia occurred during 5500 person-years versus 18 expected. The crude standardized incidence ratio of bacteremia was 2.2 (95% confidence interval, 1.6-3.0). There was no distinct pattern of bacterial etiology in the MGUS cohort. Although we found an association between MGUS and risk of bacteremia, the overall risk is small and this finding hardly affects the clinical handling of MGUS patients.

Can hospital discharge diagnosis be used for surveillance of bacteremia? A data quality study of a Danish hospital discharge registry

OBJECTIVE

To assess the data quality of septicemia and sepsis registration in a hospital discharge registry in the County of Northern Jutland, Denmark.

DESIGN

Comparison of data from the discharge registry of an 880-bed, public, urban hospital in the County of Northern Jutland with data from a computerized bacteremia database at the regional department of clinical microbiology.

SETTING

Urban hospital with approximately 45,000 admissions per year.

PATIENTS

The study included 406 episodes of bacteremia in the bacteremia database and 83 discharges with the diagnosis of septicemia registered in the hospital discharge registry between January 1, 1994, and December 31, 1994.

INTERVENTIONS

None.

RESULTS

Eighteen episodes were registered in both the hospital discharge registry and the bacteremia database. Using the bacteremia database as reference standard, the sensitivity for the diagnosis of septicemia in the hospital discharge registry was 4.4% (18/406; 95% confidence intervals [CI95, 2.4%-6.4%]). By review of hospital records, we estimated the positive predictive value of septicemia registration in the hospital discharge registry as 21.7% (18/83; CI95, 12.8%-30.5%). No blood culture had been obtained in 44.4% (36/81; CI95, 33.6%-55.3%) of the cases with a discharge diagnosis of septicemia. In 33.3% (27/81; CI95, 23.1%-43.6%), the discharge diagnosis of septicemia was given, although blood cultures were negative.

CONCLUSIONS

The hospital discharge registry revealed numerous misclassifications, and the system was found not suited for surveillance of, or research in, bacteremia at present.

Short Communication - Continued increase in prevalence of obesity in Danish young men

BACKGROUND

Previous studies of Danish young men showed a steep increase of obesity since the birth years of the early 1940s with a levelling off in the 1950s.

OBJECTIVE

To study the current prevalence of obesity and its recent changes in Danish young men.

DESIGN

Cross-sectional study based on weight and height measured at the military board for the birth cohorts 1955, 1965 and 1973-75.

SUBJECTS

We obtained information from the old paper files comprising the two cohorts of men born in 1955 (6549 adults) and 1965 (6404 adults) and prospectively examined 4300 from the birth cohorts 1973-75 in a conscription district in Denmark during the period 1 August 1993 to 31 July 1994.

RESULTS

The prevalence of obesity (defined as body mass index (BMI) > or = 30 kg/m2) was 1.5% in 1955, 2.1% in 1965 and 4.6% in 1973-75 birth cohorts. The median BMI has increased during the period from 21.7-22.8 kg/m2.

CONCLUSION

Obesity is relatively common and has increased among Danish young men.

Ultrastructural localization of osteopontin in the kidney: induction by lipopolysaccharide

Osteopontin is a secreted phosphoprotein that is expressed in the normal kidney and induced during various pathologic conditions associated with tubulointerstitial injury. However, the exact cellular location of osteopontin in the kidney has been a matter of controversy, and little is known about the role of osteopontin in the kidney. The purpose of this study was to establish the cellular and intracellular distribution of osteopontin in the rat kidney under normal conditions and after injection of a bacterial endotoxin lipopolysaccharide (LPS). Animals received injections of LPS or vehicle at different time intervals from 4 to 20 h before sacrifice. Kidneys were preserved by in vivo perfusion with paraformaldehyde-lysine-periodate (PLP) and processed for light and electron microscope immunocytochemistry using monoclonal antibodies to rat osteopontin. By light microscopy, immunostaining was observed in the descending thin limb and the papillary surface epithelium of both control and LPS-treated animals. After injection of LPS, osteopontin immunostaining was observed throughout the distal nephron and was also present in segments of the proximal tubule, where it was distributed in a punctate pattern. Staining was already present 4 h after injection of LPS and was maximal 6 h after injection. Electron microscopy revealed that osteopontin immunoreactivity in the descending thin limb and distal tubule cells was located in the Golgi apparatus and in small cytoplasmic vesicles, whereas in the proximal tubule labeling was observed in the vacuolar-lysosomal system. Western blot analysis demonstrated a band at approximately 70 kD and confirmed the increase in osteopontin expression after administration of LPS. These results demonstrate that osteopontin is constitutively expressed in cells of the descending thin limb and papillary surface epithelium and is induced throughout the distal tubule after administration of LPS.

Axial distribution of band 3-positive intercalated cells in the collecting duct of control and ammonium chloride-loaded rabbits

Recent studies have suggested that less than 10% of intercalated cells in the rabbit outer cortical collecting duct (CCD) [1, 2] and less than 3% in the connecting segment (CNT) [3] are identifiable by functional criteria as acid-secreting (type A or alpha) intercalated cells. Other studies, using peanut lectin-binding and the absence of apical endocytic activity to identify bicarbonate-secreting (type B or beta) intercalated cells, have suggested that acid-loading increases the percentage of alpha intercalated cells in the CCD. Because our preliminary observations of band 3 immunoreactivity suggest that the percentages of alpha intercalated cells in the rabbit outer CCD and the CNT are underestimated by physiologic studies and are not altered by chronic acid-loading, we quantified the percentage of alpha intercalated cells in various segments of the collecting duct using light microscopic immunohistochemistry in kidneys of rabbits receiving tap water (control) or 75 mM NH4Cl for 12 days plus 8 daily gavages of 2 to 6 mEq NH4Cl/kg body wt. Mean urine pH values were 5.96 in acid-loaded animals versus 8.47 in controls. Kidneys were preserved by in vivo perfusion with periodatelysine-paraformaldehyde fixation and processed for immunohistochemical colocalization using sequential labeling with monoclonal antibodies and peanut lectin, followed by immunoperoxidase detection. Colocalization of band 3 and carbonic anhydrase II immunoreactivity revealed the following percentages of band 3-positive intercalated cells in control versus NH4Cl rabbits: CNT, 49.0 versus 52.8; initial collecting tubule (ICT), 27.2 versus 34.5; outer CCD, 33.5 versus 30.3; inner CCD, 38.2 versus 41.8; corticomedullary CD, 67.9 versus 58.8. There were no differences between the groups for all comparisons. Similar results were obtained using band 3 protein immunoreactivity and peanut lectin-binding to identify intercalated cell subtypes. However, in NH4Cl-loaded rabbits, peanut lectin-binding was observed in band 3 positive intercalated cells in the outer medullary CD. We conclude that: (1) the percentage of alpha intercalated cells in rabbit CCD subsegments are approximately 50% in the CNT, 30% in the ICT and the outer CCD, 40% in the inner CCD, and 60% in the corticomedullary CD; (2) the percentage of alpha intercalated cells is not altered by chronic NH4Cl-loading; (3) peanut lectin is not a specific marker of beta intercalated cells.

Role of apoptosis in development of the ascending thin limb of the loop of Henle in rat kidney

At birth, the rat renal papilla has the structural composition of the mature inner stripe of the outer medulla. All loops of Henle have the configuration of short loops, and there are no ascending thin limbs. This study examines the role of apoptosis in the differentiation of the loop of Henle and the development of the ascending thin limb in the rat kidney. Kidneys of 20-day-old fetuses and 1-, 3-, 5-, 7-, 14-, and 21-day-old pups were preserved for immunohistochemistry and electron microscopy. Using a preembedding immunoperoxidase method, we identified thick ascending limbs by labeling with antibodies to the serotonin receptor, 5-HT1A, and descending thin limbs were identified by labeling with antibodies to aquaporin-1. Three methods were used to identify apoptotic cells as follows: 1) in situ nick end labeling using the ApopTag kit, 2) toluidine blue staining on plastic sections followed by etching, and 3) transmission electron microscopy. At birth, tubules with 5-HT1A immunoreactivity were present throughout the renal papilla, and there were no ascending thin limbs. From 1 to 14 days of age, staining for apoptosis was observed in numerous cells in the 5-HT1A-positive epithelium, beginning at the papillary tip and ascending to the border between outer and inner medulla. This was associated with transformation from a cuboidal to a squamous epithelium and subsequent disappearance of 5-HT1A immunostaining from the transformed cells. Electron microscopy confirmed the presence of apoptotic cells and phagocytosed apoptotic bodies in the thick ascending limb in the renal papilla. We conclude that the ascending thin limb is derived from the 5-HT1A-positive thick ascending limb by apoptotic deletion of thick ascending limb cells and transformation of the remaining tubule cells into the 5-HT1A-negative ascending thin limb.

The utility of single-strand conformation polymorphism (SSCP) analysis: results obtained in families with Fabry's disease

Single-strand conformation polymorphism (SSCP) analysis is a widely used and relatively simple method for detection of sequence polymorphisms in DNA fragments. We have used this technique to screen the alpha-galactosidase gene, with the aim of identifying the disease causing mutations in families with Fabry's disease. Five single-base shift mutations were found, but a single base-pair deletion could not be recognized by SSCP. The risk of mistaking a neutral polymorphism for a mutation is illustrated, and the utility as well as the limitations of SSCP in screening and diagnostic use are discussed.

Effects of chronic hypokalemia on renal expression of the "gastric" H(+)-K(+)-ATPase alpha-subunit gene

Chronic potassium restriction leads to active potassium reabsorption in the late distal nephron and collecting duct, segments known to express "gastric" H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase) alpha-subunit mRNA. In this study, the cellular distribution and relative abundance of mRNA encoding this isoform were examined in kidneys of normal and potassium-deprived (2 wk) rats. In situ hybridization with isoform-specific cRNA probes demonstrated prominent expression of this gene in the connecting segment (CNT), entire collecting duct, and renal papillary surface epithelium in a comparable distribution in both groups of rats. Hypertrophy of the outer medullary collecting ducts in the inner stripe of potassium-restricted rats was observed. Competitive polymerase chain reaction analysis revealed twofold greater levels of gastric H(+)-K(+)-ATPase alpha-subunit mRNA (normalized to the level of beta-actin mRNA) in the cortex, but roughly comparable levels in the outer and inner medulla, of potassium-restricted rats compared with controls. These data suggest that chronic potassium restriction results in modestly enhanced renal cortical expression of the gastric H(+)-K(+)-ATPase alpha-subunit gene and that this isoform may participate in potassium conversation by the CNT and cortical collecting duct during potassium deprivation.

Role of apoptotic and nonapoptotic cell death in removal of intercalated cells from developing rat kidney

In the developing rat kidney, both type A and type B intercalated cells are present throughout the medullary collecting duct (MCD), as well as the papillary surface epithelium. After birth, intercalated cells gradually disappear from the papillary surface epithelium and the terminal MCD, and type B cells disappear from the entire MCD. The purpose of this study was to establish the mechanism(s) by which intercalated cells are deleted from the MCD during development. Kidneys from 14-, 16-, 18-, and 20-day-old fetuses and 1-, 3-, 7-, and 14-day-old pups were preserved for light microscopic immunohistochemistry and electron microscopy. Intercalated cells were identified by immunostaining for H(+)-adenosinetriphosphatase (H(+)-ATPase) and band 3 protein. Apoptosis was identified by nick end labeling of DNA fragments, staining with the vital dye toluidine blue, and transmission electron microscopy. Two distinct mechanisms of elimination of intercalated cells were detected. Cells with apical labeling for H(+)-ATPase and basolateral labeling for band 3 protein protruded into the lumen of the MCD as if they were being extruded from the epithelium, and many had lost contact with the basement membrane. Extrusion of the cells with basolateral H(+)-ATPase or with no labeling for H(+)-ATPase was never observed. Apoptosis was observed in the MCD from shortly before birth to 7 days after birth, gradually progressing from the papillary tip toward the outer medulla. Staining for apoptosis was present in H(+)-ATPase-positive apoptotic bodies, located in cells that were negative for H(+)-ATPase. Staining was also occasionally observed in apoptotic cells with basolateral H(+)-ATPase but never in cells with apical H(+)-ATPase. Electron microscopy confirmed the presence of apoptotic intercalated cells in the MCD and demonstrated that apoptotic bodies were located in inner medullary collecting duct (IMCD) cells and principal cells. These results demonstrate that intercalated cells are deleted from the MCD by two distinct mechanisms, one involving apoptosis and subsequent phagocytosis by neighboring principal cells or IMCD cells. Elimination by extrusion affects only type A intercalated cells, whereas deletion by apoptosis appears to occur only in type B intercalated cells.

Identification of distinct subpopulations of intercalated cells in the mouse collecting duct

Structurally and functionally distinct populations of intercalated cells have been described in the collecting duct of both rat and rabbit. However, little is known about these cells in the mouse kidney. The study presented here examines ultrastructural and immunological characteristics of different types of intercalated cells in the mouse. Kidneys of two strains of normal female mice, C57BL/6 and IBR, were preserved by in vivo perfusion with 1% glutaraldehyde or paraformaldehyde-picric acid fixatives and processed for morphological evaluation or light and electron microscopic immunohistochemistry, respectively. The avidin-biotin-horseradish peroxidase procedure was performed on was sections using antibodies against carbonic anhydrase II, H+ -ATPase and Band 3 protein. Immunogold cytochemistry was performed on Lowicryl sections using antibodies to H+ -ATPase and Band 3 protein. Colocalization of H+ -ATPase and Band 3 protein was performed by double labeling using an immunogold technique with silver enhancement. Intercalated cells identified by positive staining for H+ -ATPase and carbonic anhydrase II constituted 35% to 40% of all cells in the connecting tubule (CNT), cortical collecting duct (CCD), and outer medullary collecting duct (OMCD). Type A intercalated cells identified by positive Band 3 staining constituted 16%, 24%, and 33% of the total cell population in the CNT, CCD, and OMCD, respectively. Electron microscopy and immunogold cytochemistry demonstrated three distinct populations of intercalated cells. Type A intercalated cells with apical H+ -ATPase and basolateral Band 3 immunoreactivity were present in all segments examined, and had prominent apical microprojections and characteristic tubulovesicular structures beneath the apical surface, both coated with studs on the cytoplasmic face. Type B intercalated cells with basolateral and cytoplasmic H+-ATPase and no Band 3 immunoreactivity were most frequently observed in the initial collecting tubule, but were present also in the CNT and early CCD. Type B intercalated cells had a fairly smooth apical surface, a gray zone free of organelles beneath the apical plasma membrane, and small cytoplasmic vesicles without studs throughout the cell. A third type of intercalated cell with apical and cytoplasmic H+-ATPase, but no basolateral Band 3 protein, was observed exclusively in the CNT and the initial collecting tubule. This type of cell was large, with numerous mitochondria, and vesicles coated with studs were present throughout the cell. It resembled a third type of intercalated cell described previously in the rat. It is concluded that three morphologically and immunologically distinct types of intercalated cells are present in the mouse kidney.

Expression of immunoreactive nitric oxide synthase isoforms in rat kidney. Effects of dietary salt and losartan

Immunohistochemical studies have shown expression of two different isoforms of NOS in the juxtaglomerular apparatus (JGA). Antibodies to a Ca(++)-calmodulin dependent isoform purified from rat brain (B-NOS) label the macula densa cells whereas antibodies to an isoform purified from rat aortic smooth muscle cells in culture (VSM-NOS) induced with lipopolysaccharide and interferon gamma label the afferent arteriole. Since dietary salt intake and angiotensin II (Ang II) are determinants of renal NO generation, we have tested the hypothesis that salt intake can regulate the immunohistochemical expression of these NOS isoforms through an effect of Ang II. In 4 of 5 paired studies, the immunostaining for both B-NOS and VSM-NOS was more intense in rats that had received a low salt (LS), compared to a high salt (HS), diet. Infusion of the Ang II type 1 (AT1) receptor antagonist, losartan, enhanced the intensity of immunoreactive staining for both isoforms. In conclusion, the immunohistochemical expression of NOS isoforms in the JGA is increased by dietary salt restriction; this effect cannot be ascribed to Ang II acting on type 1 receptors.

Angiotensin II regulates H(+)-ATPase activity in rat cortical collecting duct

Angiotensin II (ANG II) plays an important role in the regulation of solute transport in the kidney, and its effect on proximal tubule sodium and fluid transport has been studied extensively. Although there is evidence that ANG II receptors are present also in the distal nephron and collecting duct, little is known about the physiological role of ANG II in these segments of the renal tubule. Preliminary studies in our laboratory suggest that ANG II may have both structural and functional effects on intercalated cells in the cortical collecting duct (CCD). Therefore, the present study examines the effect of ANG II on H(+)-adenosinetriphosphatase (H(+)-ATPase) and H(+)-K(+)-ATPase activity in individual CCD segments microdissected from collagenase-treated rat kidneys. The H(+)-ATPase was measured as bafilomycin-sensitive ATPase activity, and H(+)-K(+)-ATPase was measured as Sch-28080-sensitive ATPase activity, by a fluorometric microassay. Preincubation of CCD segments with ANG II, 10(-10)-10(-5) M, caused a dose-dependent decrease in H(+)-ATPase activity with maximum inhibition at 10(-8) M of ANG II. The inhibitory effect of ANG II was abolished when tubules were incubated with ANG II in the presence of 10(-6) M losartan, indicating that the inhibition was mediated via specific AT1 receptors. The AT2-receptor antagonist, PD-123319, had no effect on the ANG II-mediated inhibition of H(+)-ATPase activity. Preincubation of CCD segments with 10(-10) or 10(-7) M ANG II had no effect on H(+)-K(+)-ATPase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

In situ hybridization localization of mRNA encoding inducible nitric oxide synthase in rat kidney

We used in situ hybridization with a digoxigenin-labeled cRNA for inducible nitric oxide synthase (iNOS) to characterize the intrarenal distribution of iNOS transcripts in normal and lipopolysaccharide (LPS)-treated rats. In normal rats, the S3 segment of the proximal tubule, the cortical and medullary thick ascending limb, the distal convoluted tubule, and the cortical and inner medullary collecting duct were intensely labeled, whereas the thin limbs of Henle, proximal convoluted tubule, outer medullary collecting duct, and medullary interstitial cells were weakly labeled. LPS-treated rats exhibited a similar labeling pattern, but with increased staining of mesangial cells, medullary interstitial cells, and papillary surface epithelium. The renal vasculature, including the afferent arteriole, was not labeled in either group. No cellular labeling was observed when the sections were hybridized with the sense iNOS probe. These results indicate that iNOS mRNA is tonically and differentially expressed along the normal rat nephron and that LPS induces iNOS gene expression in normally quiescent mesangial cells, medullary interstitial cells, and papillary surface epithelium.

Nitric oxide inhibits bafilomycin-sensitive H(+)-ATPase activity in rat cortical collecting duct

Nitric oxide (NO) is a messenger molecule that is produced from L-arginine by NO synthase (NOS). Some NOS isoforms are present in cells constitutively, whereas others can be induced by cytokines. Recent evidence suggests that NO inhibits intracellular pH regulation by the vacuolar H(+)-adenosinetriphosphatase (ATPase) in macrophages, which contain an inducible form of NOS. The vacuolar H(+)-ATPase is involved in proton secretion in intercalated cells in the collecting duct. We have therefore examined the effect of NO on bafilomycin-sensitive H(+)-ATPase activity in individual cortical collecting ducts (CCD) microdissected from collagenase-treated kidneys of normal rats using a fluorometric microassay. Incubation of CCD with the NO donors, sodium nitroprusside (0.1 and 1 mM) or 3-morpholino-sydnonimine hydrochloride (SIN-1, 30 microM), caused a dose-dependent decrease in H(+)-ATPase activity. Incubation of CCD with lipopolysaccharide (LPS) and interferon-gamma, which induces NOS in macrophages, decreased H(+)-ATPase activity by 85%. This effect was prevented by simultaneous incubation with N omega-nitro-L-arginine, a competitive inhibitor of NOS, indicating that the decrease in H(+)-ATPase activity was caused by NO production. Incubation with 8-bromo-guanosine 3',5'-cyclic monophosphate (cGMP) also inhibited H(+)-ATPase activity, suggesting that NO may exert its effect in the CCD via activation of guanylyl cyclase and production of cGMP. Immunohistochemistry using antibodies to the macrophage-type NOS revealed strong labeling of intercalated cells in the CCD, confirming the presence of NOS in these cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Dissociation of ammoniagenic enzyme adaptation in rat S1 proximal tubules and ammonium excretion response

We measured ammonium production rates, phosphate-dependent glutaminase (PDG) activity, and glutamate dehydrogenase (GDH) activity in microdissected S1 proximal tubules of rats to investigate the role of adaptations of PDG activity and GDH activity in response to a step increase in acid intake. In vivo ammonium excretion increased much more rapidly than did single-tubule ammonium production in vitro or ammoniagenic enzyme activities measured in microdissected tubules, manifesting an 85-fold increase in the first 24 h. In vitro ammonium production rates in microdissected tubules rose only twofold in the first 24 h, fourfold by day 2, and fivefold by day 4 of acid loading. The adaptation of PDG activity paralleled the increase in single-tubule ammoniagenic capacity measured in vitro. GDH activity, on the other hand, did not change significantly even after 4 days of acid loading. From these observations, we conclude that 1) the adaptation of in vitro ammoniagenic capacity in S1 proximal tubules is temporally associated with an adaptation in PDG activity and not GDH activity, and 2) a major portion of the increased ammonium excretion seen in the first 24 h is due to factors other than an adaptive increase in ammoniagenic enzyme activity.

Differentiation of intercalated cells in developing rat kidney: an immunohistochemical study

Intercalated cells are present in both the collecting duct, which is derived from the ureteric bud, and the connecting tubule (CNT), which is part of the nephron and thus is developed from the metanephric blastema. However, the embryologic origin of the intercalated cells has not been established. Two populations of intercalated cells, type A and type B, exist in the CNT and the cortical collecting duct (CCD). It is uncertain, however, whether these cells represent truly distinct cell types or whether one is derived from the other. In this study we have used specific antibodies to carbonic anhydrase II (CA II), H(+)-adenosinetriphosphatase (H(+)-ATPase), and band 3 protein to identify subpopulations of intercalated cells, to determine the site and time of their appearance, and to follow their differentiation in the developing rat kidney. Prenatal kidneys from 16-, 17-, 18-, and 20-day-old fetuses, and postnatal kidneys from 0-, 3-, 7-, 14-, and 21-day-old pups were preserved for immunohistochemical studies. Immunostaining for CA II and H(+)-ATPase appeared simultaneously in a subpopulation of cells in the CNT and the medullary collecting duct (MCD) of the 18-day-old fetus, suggesting that intercalated cells differentiate from separate foci, one in the nephron and one in the collecting duct. Cells with apical and cells with basolateral labeling for H(+)-ATPase appeared in the CNT and MCD at 18 days of gestation, indicating that type A and type B cells differentiate simultaneously during renal development. Band 3 immunostaining was very weak in the fetal kidney, but a striking increase in labeling was observed in the 3-day-old kidney, suggesting that there is an activation of acid-secreting cells shortly after birth. In the fetal kidney, immunostaining for CA II and H(+)-ATPase was observed in cells throughout the MCD and on the papillary surface. After birth, immunostaining gradually disappeared from both the papillary surface and the terminal inner MCD, and cells with basolateral labeling for H(+)-ATPase gradually disappeared from the outer MCD. The results of this study suggest that type A and type B intercalated cells represent distinct cell types that derive from undifferentiated cells at two separate foci, one in the nephron and one in the collecting duct. Our results also suggest that entire populations of intercalated cells are eliminated from the collecting duct during normal renal development.

Activation of acid-secreting intercalated cells in rabbit collecting duct with ammonium chloride loading

In normal rabbit, immunolabeling of intercalated cells in the outer medullary collecting duct (OMCD) demonstrates band 3-like protein in the basolateral plasma membrane (15) and H(+)-adenosinetriphosphatase (H(+)-ATPase) in the apical plasma membrane and cytoplasmic vesicles (30). However, in type A intercalated cells in the cortical collecting duct (CCD), band 3-like protein is located primarily in multivesicular bodies and cytoplasmic vesicles (15), whereas H(+)-ATPase is present in cytoplasmic vesicles only in most intercalated cells (30). In this study, we observed the effect of chronic acid loading on immunolocalization of these transporters in the collecting duct. Adult New Zealand White rabbits received either normal tap water (controls) or 75 mM NH4Cl for 12 days plus eight daily gavages of 2-6 meq NH4Cl/kg body wt. At time of death, mean urine pH of acid-loaded animals was 5.96 (SD = 0.69), vs. 8.47 (SD = 0.07) in controls. Kidneys were fixed by in vivo perfusion and processed for light and electron microscopic immunoperoxidase localization of band 3-like protein and immunogold localization of H(+)-ATPase. In controls, band 3-like protein was largely confined to multivesicular bodies in the majority of positive-staining intercalated cells in the CCD and to the basolateral plasma membrane of intercalated cells in the OMCD. In acid-loaded rabbits, band 3 protein-positive intercalated cells in the inner CCD and the in the outer stripe of the OMCD (OMCDo) were strikingly stellate in form. Basolateral plasma membrane label was intensified, while the number of labeled multivesicular bodies was diminished. Morphometric analysis demonstrated an increase in the amount of basolateral plasma membrane in these intercalated cells. In control rabbits, H(+)-ATPase immunoreactivity in intercalated cells in the CCD was located predominantly over cytoplasmic vesicles. A minority of intercalated cells exhibited basolateral plasma membrane label, and only an occasional cell displayed apical plasma membrane label. In acid-loaded rabbits, H(+)-ATPase immunoreactivity was enhanced along the apical plasma membrane of intercalated cells in the inner CCD, and morphometric analysis demonstrated increased apical plasma membrane in band 3-positive intercalated cells in this segment. These results suggest that rabbits respond to acid loading via enhancement of both electrogenic proton secretion and Cl-/HCO3- exchange in intercalated cells in the inner CCD and the OMCDo.

Ultrastructural localization of H+ATPase in rabbit cortical collecting duct

In contrast to results obtained in the rat kidney, studies of H+ATPase localization in the rabbit kidney have failed to demonstrate basolateral plasma membrane H+ATPase immunoreactivity in intercalated cells in the cortical collecting duct (CCD). Previous studies have relied on light microscopic immunofluorescence techniques, which have limited resolution. Therefore, the immunogold procedure was used to localize H+ATPase in rabbit collecting ducts at the ultrastructural level. Rabbit kidneys were preserved in vivo with periodate-lysine-paraformaldehyde or glutaraldehyde solutions, and samples of cortex were embedded in Lowicryl K4M. Thin sections were labeled for H+ATPase by the immunogold procedure with a rabbit polyclonal antibody against the 70-kd subunit of bovine brain H+ATPase. Three patterns of localization of H+ATPase were observed. The majority of intercalated cells in the CCD exhibited label over cytoplasmic vesicles only. In these cells, no label was associated with either the apical or basolateral plasma membranes. In a second group of cells, label for H+ATPase was observed along the basolateral plasma membrane and over cytoplasmic vesicles throughout the cell. Rarely, intercalated cells with H+ATPase label along the apical plasma membrane and over the apical cytoplasmic vesicles were observed in the CCD. In the initial collecting tubule and connecting segment, intercalated cells with either pronounced apical or basolateral plasma membrane label prevailed, whereas few cells exhibited label restricted to the cytoplasmic vesicles. In summary, in the rabbit CCD, three patterns of H+ATPase distribution exist in intercalated cells, two of which conform to published models of type A and type B intercalated cells.

Immunocytochemical localization of distinct isoforms of nitric oxide synthase in the juxtaglomerular apparatus of normal rat kidney

Nitric oxide (NO) is a messenger molecule that functions as a vasodilator and accounts for the biologic activity of endothelium-derived relaxing factor (EDRF). The enzyme responsible for NO production, NO synthase (NOS), exists in different isoforms. Some are expressed constitutively in various tissues, whereas others require induction by endotoxin and cytokines. There is evidence that NO plays an important role in the regulation of basal renal vascular resistance and in the tubuloglomerular feedback response. Specific antibodies to a constitutive NOS isolated from rat brain (B-NOS) and an inducible NOS isolated from rat aortic smooth muscle (VSM-NOS) were used to establish the cellular and subcellular distribution of NOS in the kidney. Kidneys from normal rats were preserved and processed for light and electron microscopic immunohistochemical studies using both a preembedding and a postembedding horseradish peroxidase technique. By light microscopy, strong immunostaining for B-NOS was observed in the juxtaglomerular apparatus, where it was located in cells of the macula densa. In contrast, immunostaining for VSM-NOS was specifically located in the terminal afferent arteriole and occasionally also in the initial efferent arteriole in the juxtaglomerular apparatus. In addition, faint immunostaining was present in the entire distal tubule. There was no labeling of arcuate or interlobular arteries. The injection of lipopolysaccharide was associated with increased immunostaining for VSM-NOS in the afferent arteriole but had no effect on B-NOS staining. By electron microscopy, B-NOS immunostaining was present throughout the cytoplasm of the macula densa cells, where it appeared to be associated mainly with small vesicles. Immunostaining for VSM-NOS in the afferent arteriole exhibited a patchy distribution in some cells, whereas other cells were stained throughout the cytoplasm. These results indicate that two distinct isoforms of NOS are present in the juxtaglomerular apparatus and support the hypothesis that NOS is involved in the regulation of tubuloglomerular feedback and glomerular capillary pressure.

Differential expression and cellular distribution of mRNAs encoding alpha- and beta-isoforms of Na(+)-K(+)-ATPase in rat kidney

We have used in situ hybridization histochemistry with isoform-specific, digoxigenin-labeled cRNA probes to characterize systematically the cellular distribution of mRNAs encoding alpha- and beta-subunit isoforms of the Na(+)-K(+)-adenosinetriphosphatase (Na(+)-K(+)-ATPase) in the normal rat kidney. Transcripts encoding the alpha 1-, alpha 2-, alpha 3-, beta 1-, and beta 2-subunits were detected in virtually all of the nephron segments, with prominent hybridization signal in the S3 segment of the proximal tubule, the cortical and medullary thick ascending limb of Henle's loop, the distal convoluted tubule, the cortical collecting duct along its entire length, and the renal pelvic epithelium. Several differences in the cell-specific pattern of expression of the various isoforms were observed. Among the alpha-isoforms, the alpha 3-subunit appeared to be preferentially expressed in the glomerular podocytes and mesangial cells, papillary interstitial cells, and renal pelvic epithelium. The beta-isoforms also differed in their distribution pattern, with the beta 1-subunit expressed to a greater degree in the glomerulus and renal pelvic epithelium and the beta 2-subunit preferentially expressed in the papillary interstitial cells and papillary surface epithelium. The detection and expression pattern of alpha- and beta-subunit mRNAs in structures throughout the kidney is compatible with the possibility of six structurally unique Na(+)-K(+)-ATPase isozymes and suggests a potentially greater role for isozymes comprised of the alpha 2-, alpha 3-, and beta 2-subunits in renal sodium and potassium transport.

Intracellular band 3 immunostaining in type A intercalated cells of rabbit kidney

Intercalated cells (ICs) in the collecting duct and the connecting tubule (CNT) are involved in H+ secretion and HCO3- reabsorption. H+ secretion is mediated by an H(+)-adenosinetriphosphatase in the apical plasma membrane, whereas a band 3-like Cl(-)-HCO3- exchanger in the basolateral membrane is responsible for HCO3- reabsorption. Recent studies have reported that a band 3-like protein is also present in mitochondria in rabbit ICs. The purpose of this study was to establish the subcellular location of the band 3-like Cl(-)-HCO3- exchanger in rabbit ICs by electron microscopic immunocytochemistry using a monoclonal antibody, IVF12, against erythrocyte band 3 protein. Rabbit kidneys were preserved by in vivo perfusion with a paraformaldehyde-lysine-periodate solution and processed for immunocytochemistry using a horseradish peroxidase preembedding technique. Band 3 immunostaining was observed on the basolateral plasma membrane of ICs in the outer medullary collecting duct and type A cells in the cortical collecting duct (CCD) and CNT. In addition, distinct staining for band 3 was present in numerous small vesicles and in multivesicular bodies in type A ICs in the CCD and CNT. However, there was no evidence of band 3 immunostaining of mitochondria or of the apical plasma membrane in any cells of the collecting duct. These observations suggest that basolateral Cl(-)-HCO3- exchangers in type A ICs in the rabbit kidney are stored in intracellular vesicles and possibly degraded in the vascular-lysosomal system when these cells are in a resting state. The previously reported band 3 immunolabeling of mitochondria could not be confirmed.

Immunocytochemical response of type A and type B intercalated cells to increased sodium chloride delivery

Two populations of intercalated cells, type A and type B, are present in the rat cortical collecting duct (CCD). Type A cells are involved in proton secretion and contain an apical H(+)-adenosinetriphosphatase (ATPase) and a basolateral Cl(-)-HCO3- exchanger. Type B cells are believed to be involved in HCO3- secretion, which is mediated by a Cl(-)-HCO3- exchange process and is Cl- dependent. The aim of this study was to examine the morphological and immunocytochemical response of type B intercalated cells in the rat to increased delivery of Cl- to the CCD. This was accomplished by chronic infusion of a loop diuretic, bumetanide (30 mg.kg body wt-1.day-1), via an osmotic minipump, and simultaneous administration of 0.9% sodium chloride in the drinking water for 6 days. The kidneys were preserved by in vivo perfusion with a periodate-lysine-paraformaldehyde fixative and processed for horseradish peroxidase and protein A gold immunocytochemistry, using rabbit polyclonal antibodies against carbonic anhydrase II, proton ATPase, and band 3 protein. Chronic infusion of bumetanide in combination with a high salt intake was associated with significant changes in the intercalated cells. Type B cells were increased in size and exhibited numerous apical microvilli, increased basolateral membrane area, and marked cytoplasmic and basolateral labeling for H(+)-ATPase. In contrast, type A cells were small and had sparse apical microprojections. H(+)-ATPase immunolabeling was observed primarily over apical tubulovesicles, and there was decreased basolateral immunolabeling for band 3 protein and occasional labeling for band 3 in lysosome-like structures. These observations support the hypothesis that increased delivery of Cl- to the CCD is associated with stimulation of type B intercalated cells to secrete HCO3-. The observations in type A cells are consistent with the cells being in a resting or inactivated state.

Response of intercalated cells to chloride depletion metabolic alkalosis

We examined the effect of Cl- depletion metabolic alkalosis (CDA) on H(+)-ATPase and band 3 protein localization in intercalated cells (IC) of the rat cortical collecting duct (CCD) and the outer medullary collecting duct (OMCD). After 30 min of peritoneal dialysis against 0.15 M NaHCO3 to produce CDA, or Ringer bicarbonate to serve as controls (CON), both groups were infused intravenously with an 80 mM Cl- solution for 90 min. For CDA vs. CON, physiological parameters were as follows: plasma total CO2, 38.0 +/- 1.1 vs. 27.8 +/- 0.6 meq/l (P less than 0.001); urinary total CO2 excretion, 141 +/- 89 vs. 20 +/- 3 neq.min-1.100 g body wt-1; and urinary Cl- excretion, 20 +/- 10 vs. 486 +/- 144 neq.min-1.100 g body wt-1 (P less than 0.001). H(+)-ATPase was localized in thin sections using a rabbit polyclonal antibody against the 70-kDa subunit of bovine brain H(+)-ATPase. Band 3 protein was localized using a polyclonal antibody against the 43-kDa subunit of the cytoplasmic domain of human erythrocyte band 3 protein. In CON rats, H(+)-ATPase localized along the apical plasma membrane and over the apical cytoplasmic vesicles of type A ICs in the CCD and ICs of the OMCD. H(+)-ATPase was observed along the basolateral plasma membrane and over cytoplasmic vesicles throughout type B ICs. In CDA rats, H(+)-ATPase was only observed over apical cytoplasmic vesicles in type A ICs and in the majority of OMCD ICs. In type B ICs, H(+)-ATPase staining was intensified along the basal plasma membrane in CDA. Band 3 protein was consistently localized in the basolateral plasma membrane of all type A cells in the CCD and ICs of the OMCD in both CON and CDA. In summary, stimulation of HCO3- secretion in rats caused withdrawal of H(+)-ATPase from the apical plasma membrane and storage in apical cytoplasmic vesicles of ICs of the OMCD and type A ICs of the CCD. H(+)-ATPase appeared to be inserted into the basal plasma membrane of type B ICs. These findings suggest that, during correction of CDA, proton secretion by type A and OMCD ICs is suppressed and proton transport across the basolateral plasma membrane of type B ICs is stimulated.

Postprandial gastro-oesophageal reflux demonstrated by radiology

An investigation to detect food-stimulated gastro-oesophageal (GE) reflux was carried out in 54 consecutive fasting patients, 35 of whom experienced reflux while 19 did not. All patients then received a standard meal (566 kcal), and the investigation was repeated 1 h later. Out of the 35 with GE reflux in the fasting state, 33 also had GE reflux in the postprandial state, and 17 of the 19 patients with no GE reflux while fasting also had none in the postprandial state. It is concluded that the radiological method can identify most patients in whom food-stimulated GE reflux could be of clinical significance.

H-K-ATPase immunoreactivity in cortical and outer medullary collecting duct

Biochemical and physiologic studies in individual segments of the cortical collecting duct (CCD) and outer medullary collecting duct (OMCD) have provided evidence for the presence of an H-K-ATPase which is involved in the reabsorption of potassium in exchange for protons. The present study was designed to determine the cellular distribution of H-K-ATPase immunoreactivity in the CCD and OMCD of the rat and rabbit using mouse monoclonal antibodies against hog gastric H-K-ATPase. Kidneys of normal rats and rabbits were preserved for light microscopic immunohistochemistry and embedded in paraffin. Sections were incubated with the primary antibody followed by the avidin-biotin-horseradish peroxidase procedure. Sections incubated without primary antibody or with a non-specific mouse Ig served as controls. Light microscopy revealed diffuse cytoplasmic staining indicating H-K-ATPase immunoreactivity in intercalated cells in the CCD and OMCD in both rat and rabbit. In all segments studied except the rat CCD, the percentage of H-K-ATPase immunoreactive cells corresponded to the percentage of intercalated cells. In the rat CCD only 23% of the cells were reactive with H-K-ATPase antibodies, which is less than the percentage of intercalated cells in this region. It is possible that only type A intercalated cells possess H-K-ATPase immunoreactivity or that some intercalated cells did not have sufficient activity to be detected by our method. These results demonstrate H-K-ATPase immunoreactivity in the intercalated cells of the CCD and OMCD of rat and rabbit, suggesting that these cells are involved in potassium reabsorption in exchange for proton secretion in the mammalian collecting duct.

Ultrastructural localization of carbonic anhydrase II in subpopulations of intercalated cells of the rat kidney

At least two configurations of intercalated cells, type A and type B, are present in the cortical collecting duct. Intercalated cells are rich in carbonic anhydrase. However, it is not known whether there are differences in the level and subcellular distribution of this enzyme between type A and type B intercalated cells. The purpose of this study was to determine the relative content and intracellular distribution of carbonic anhydrase II in the various subpopulations of intercalated cells in the rat collecting duct. A rabbit polyclonal antibody directed against mouse erythrocyte carbonic anhydrase II was employed to localize carbonic anhydrase, II by light and electron microscopy by an indirect immunoperoxidase method. A Western immunoblot analysis of homogenates of rat kidney cortex and medulla with the carbonic anhydrase II antibody revealed a single polypeptide band at 29 kDa corresponding to the molecular size of carbonic anhydrase II. By both light and electron microscopy, carbonic anhydrase II immunoreactivity was present in all intercalated cells but the intensity of staining was much greater in type A than in type B cells. In addition, immunostaining in type A cells was especially pronounced in the apical cytoplasm and apical microprojections whereas in type B cells, immunostaining was more diffuse throughout the cytoplasm. A third configuration of intercalated cell with diffuse immunostaining for carbonic anhydrase II was occasionally observed in the connecting segment. Very weak immunostaining was present in principal cells, whereas connecting tubule cells and inner medullary collecting duct cells were negative for carbonic anhydrase II.(ABSTRACT TRUNCATED AT 250 WORDS)

[Tuberculous cysts of the mediastinum]

A 71-year-old woman was admitted to the hospital with polycystic deformations in the left pulmonary hilus in the mediastinum, found in a routine chest X-ray. The patient had earlier been treated for pulmonary tuberculosis. Mediastinotomia was performed and thin-walled cysts with a creamy type of pus were found. Microbiological examinations revealed evidence of tubercle bacilli. Medical treatment for tuberculosis was begun, which led to recovery with regression of the cysts.

Immunocytochemical localization of intracellular acidic compartments: rat proximal nephron

There is evidence that components of the endosomal-lysosomal system of most cells have an acidic interior. The weak base, N-(3-[(2,4-dinitrophenyl)amino]propyl)-N-(3-aminopropyl)methylamine dihydrochloride (DAMP) has been shown to accumulate in acidic compartments in cultured cells and in isolated perfused proximal tubules. We infused DAMP intravascularly in vivo and used colloidal gold immunocytochemistry to identify acidic compartments in cells of the rat glomerulus and proximal tubule. Sprague-Dawley rats were infused intra-arterially with DAMP. The kidneys were fixed by intravascular perfusion with 1% glutaraldehyde and embedded in Lowicryl K4M. Sections were exposed to a mouse anti-dinitrophenol (DNP) monoclonal antibody that cross-reacts with DAMP, followed by gold-conjugated goat anti-mouse immunoglobulin G. Transmission electron microscopy revealed positive labeling of the lysosome-like structures of the various cells of the glomerulus and lysosomes, endosomes, and numerous endocytic vesicles of all segments of the proximal tubule. We conclude that 1) DAMP can be used in vivo to identify acidic compartments in the kidney and 2) lysosomes, endosomes, and many endocytic vesicles of the rat proximal tubule as well as lysosome-like structures in cells of the glomerulus have an acidic interior.

[Salpingo-enteric fistula demonstrated by hysterosalpingography (HSG)]

A case of fistula between the right salpinx and appendix, most probably caused by untreated appendicitis, is presented. The patient was admitted to hospital because of involuntary infertility.

Morphologic heterogeneity along the rat inner medullary collecting duct

The qualitative and quantitative morphologic features of the cells lining the inner medullary collecting duct (IMCD) in the outer (IMCD1), middle (IMCD2) and inner (IMCD3) segments were investigated. Kidneys of male rats were fixed by in vivo vascular perfusion with glutaraldehyde and processed for light microscopy and scanning and transmission electron microscopy. The IMCD1 consisted of both principal cells and intercalated cells similar to those present in the outer medullary collecting duct. The principal cells were covered with small microvilli and a single cilium. Most of the IMCD2 and the entire IMCD3 contained one cell type (IMCD cell). When compared with the principal cells, the IMCD cells were taller, had fewer basal infoldings and a lighter staining cytoplasm containing numerous free ribosomes and small electron-dense cytoplasmic bodies in the basal region. The luminal surface was covered with prominent microvilli, but had no cilia. Morphometric analysis demonstrated that the surface density of apical and basal plasma membranes decreased from IMCD1 to IMCD3. However, because of an overall increase in tubule volume from IMCD1 to IMCD3, there were no significant differences in the absolute area of apical or basal membranes between the three segments. In contrast, the absolute area of lateral membranes increased significantly from IMCD1 to IMCD3. This study demonstrates that the IMCD1 consists of principal cells and intercalated cells similar to those in the outer medullary collecting duct, whereas the cells in most of the IMCD2 and the entire IMCD3 appear to represent a distinct and separate cell type which we choose to call the IMCD cell. Thus, both morphologic and functional heterogeneity appear to exist along the IMCD.

Immunocytochemical localization of band 3 protein in the rat collecting duct

Band 3 protein is the major anion transport protein of the erythrocyte cell membrane where it catalyzes the exchange of HCO3- for Cl-. There is evidence that band 3 protein is present in the collecting duct of both the rat and rabbit kidney. We used colloidal-gold immunocytochemistry to determine the ultrastructural location of band 3 protein in the rat cortical (CCD) and outer medullary collecting ducts (OMCD). Kidneys of normal Sprague-Dawley rats were fixed by intravascular perfusion with 1% glutaraldehyde and embedded in Lowicryl K4M. Two polyclonal antibodies raised in rabbits were used as the primary antibody in separate experiments, one against the 43-kDa fragment of the cytoplasmic domain of human erythrocyte band 3 protein and the other against rat erythrocyte band 3 protein. This was followed by exposure to gold-conjugated goat anti-rabbit immunoglobulin G. Transmission electron microscopy revealed gold particles along the basal and lateral plasma membranes of all intercalated cells of the OMCD. In the CCD, the basal and lateral plasma membranes of the type A intercalated cells only were labeled with gold particles. The type B intercalated cells and principal cells were devoid of gold particles, as were all cells of the proximal tubule, the distal convoluted tubule, and the thick ascending limb of the loop of Henle. We conclude that a Cl(-)-HCO3- transporter is present in the basal and lateral plasma membranes of the intercalated cells in the OMCD and the type A intercalated cells in the CCD. These findings provide further evidence that these intercalated cells are involved in H+ secretion in the OMCD and CCD of the rat. We have no evidence for the presence of band 3 protein in the type B intercalated cells of the CCD, which supports the hypothesis that type B cells are functionally and structurally distinct from type A cells.

Relationship between structure and function in distal tubule and collecting duct

The relationship between structure and function in the distal tubule and collecting duct has been studied with morphologic and physiologic techniques, including morphometric analysis, to identify functionally distinct cell populations. The distal tubule, including the thick ascending limb (TAL) and the distal convoluted tubule (DCT), is involved in active reabsorption of sodium chloride. It is characterized by extensive invaginations of the basolateral plasma membrane, numerous mitochondria, and high Na-K-ATPase activity, features characteristic for an epithelium involved in active transport. Between the distal tubule and the collecting duct is a transition region, the connecting segment or the connecting tubule (CNT), which exhibits species differences with respect to both structure and function. The collecting duct includes the cortical (CCD), the outer medullary (OMCD), and the inner medullary (IMCD) collecting ducts. Principal cells are present throughout the collecting duct, whereas intercalated cells are located mainly in the CCD and OMCD. Morphometric analysis combined with micropuncture and microperfusion studies has provided evidence that the CNT and principal cells are responsible for potassium secretion in the connecting segment and the CCD. The OMCD is a main site of hydrogen ion secretion, and morphometric studies have provided evidence that the intercalated cells in this segment secrete hydrogen ion at least in the rat. Two configurations of intercalated cells exist in the CCD--a type A and a type B. The A cells are similar in ultrastructure to the intercalated cells in the OMCD and are believed to be involved in hydrogen ion secretion. The function of the B cells remains to be established. The inner two-thirds of the IMCD corresponds to the papillary collecting duct, which has a high permeability to urea. The relationship between structure and function in the IMCD has not been studied in detail. This review emphasizes the role of morphometric analysis in establishing the relationship between structure and function in the distal nephron.

Axial heterogeneity in the handling of albumin by the rabbit proximal tubule

Morphologic and physiologic studies have established that filtered proteins are absorbed in the proximal tubule by endocytosis and transported to the lysosomes for degradation. The tubular absorption, hydrolysis and accumulation of albumin were examined in all three segments of the rabbit proximal tubule. S1, S2 and S3 segments were dissected and perfused in vitro with tritiated albumin at a physiologic concentration of 0.0364 mg/ml, and with [14C]inulin to determine fluid reabsorption. In addition, the three segments were fixed for ultrastructural examination after perfusion under conditions similar to those in the physiologic studies. The fluid reabsorption was similar in S1 and S2 but lower in S3. Albumin absorption was unexpectedly similar in the three segments. A lower percentage of absorbed albumin was hydrolyzed in the S3 segment compared with the earlier segments. The values were 70 +/- 15%, 61 +/- 11%, and 30 +/- 4% for S1, S2, and S3, respectively. The cellular accumulation of protein was highest in the S3 segment. The ultrastructure of the three segments was similar to that described in in vivo preserved kidneys, and no abnormalities were observed in the endocytic-lysosomal compartment. These results reveal axial heterogeneity in the hydrolysis of absorbed albumin by the rabbit proximal tubule and suggest that under normal physiologic conditions the S3 segment has a lower lysosomal proteolytic activity. Although the S3 segment maintains a high capacity for protein absorption, the earlier proximal segments likely have a greater role in protein degradation.