Evaluation of re-depositing hydropower trapped sediments at large rivers to improve flood protection and aquatic habitats - Case study Danube/Austria.

Sedimentation in impoundments of run-of-river hydropower plants is an ongoing and progressing management issue for hydropower operators because of its consequences for e.g., the maintenance of flood protection and waterway parameters. Current practices in sediment management are often unsustainable, associated with high costs, and can pose risks for downstream biota (e.g. during flushing). The present study elaborated a conceptual model of a novel sediment management strategy for impounded river sections consisting of a current-state and deficit analysis, and the application of a novel sediment management practice, which was practically implemented at the study site at the Austrian Danube River. This novel practice consists of (i) local dredging of gravel at locations in the impoundment, which are problematic in terms of flood protection and waterway maintenance, and (ii) the re-deposition of dredged sediments by artificial placement of gravel structures. The present study included morphological analyses of the impounded section at the study site by applying the channel profile budget technique. The knowledge of the long-term morphological development served as a basis for the evaluation of the sediment management measures and for the elaboration of the conceptual model. The combination of the morphodynamic characteristics in the impoundment with the implementation of the novel sediment management practice helped to derive generalized statements for the potential implementation of the presented conceptual model in large rivers with similar impoundment characteristics. We further defined several aspects, which are related to sediment dynamics in impounded river sections, flood protection, waterway demands, and ecological criteria that require consideration for an efficient realization of the proposed conceptual model.

Evaluation of the potential stranding risk for aquatic organisms according to long-term morphological changes and grain size in alpine rivers impacted by hydropeaking.

Hydropeaking is one of the major hydropower-related disturbances of natural processes in river systems. The artificial flow fluctuations that are caused by the on-demand production of electricity are known for their severe impacts on aquatic ecosystems. These particularly affect those species and life stages that are not able to adjust their habitat selection to rapid up- and downramping rates. To date, the stranding risk has both experimentally and numerically mainly been investigated with variable hydropeaking graphs over stable river bathymetries. There is a lack of knowledge on how single, discrete peaking events vary concerning their impact on the stranding risk when the river morphology changes in the long-term perspective. The present study precisely addresses this knowledge gap by investigating morphological changes on the reach scale over a period of 20 years and the related variability of the lateral ramping velocity as a proxy for stranding risk. Two alpine gravel bed rivers impacted by hydropeaking over decades were tested by applying a one-dimensional and two-dimensional unsteady modelling approach. Both the Bregenzerach River and the Inn River exhibit alternating gravel bars on the reach scale. The results of the morphological development, however, showed different developments in the period 1995-2015. The Bregenzerach River displayed continuous aggradation (uplift of river bed) over the various selected submonitoring periods. In contrast, the Inn River showed continuous incision (erosion of river bed). The stranding risk exhibited high variability on a single cross-sectional basis. However, on the reach scale, no significant changes in stranding risk were calculated for either river reach. In addition, the impacts of river incision on the substrate composition were investigated. Here, in line with preceding studies, the results show that the coarsening of substrate increases the stranding risk and that especially the d90 (90 % finer of the grain size distribution) must be considered. The present study reveals that the quantified stranding risk of aquatic organisms is a function of the general morphological (bar) characteristics of the impacted river and both the morphological and grain size development have an impact on the potential stranding risk of aquatic organisms and should be considered in the revision of licences in the management of multi-stressed river systems.

[Movement of a fluvial particle under the influence of coherent structures]. / Bewegung eines Einzelkorns unter dem Einfluss kohärenter Strukturen.

In a fundamental study the influence of coherent structures on the incipient motion of single fluvial grain was experimentally investigated. To fully characterize coherent structures, the three-dimensional velocity field must be known with high temporal resolution. Using a tr-3D PTV system (tr = time-resolved, PTV = particle tracking velocimetry) this could be achieved. The influence of hairpin vortices and counter-rotating longitudinal vortices (VLSM) on sediment transport has been postulated in several studies, but due to the missing 3D information, evidence has been lacking. In the present "Rolling Stones test series", the incipient motion of a single grain was investigated for smooth and rough beds. It could be shown for the first time that both hairpin vortices and VLSM trigger particle entrainment. Hairpin vortices could also be detected on rough beds, contrary to common hypotheses, and triggered particle movement. The long-term study should also find practical applications in the coming years and increase the accuracy of sediment transport calculations in rivers.

Putting patients at the center of kidney care transitions: PREPARE NOW, a cluster randomized controlled trial.

Care for patients transitioning from chronic kidney disease to kidney failure often falls short of meeting patients' needs. The PREPARE NOW study is a cluster randomized controlled trial studying the effectiveness of a pragmatic health system intervention, 'Patient Centered Kidney Transition Care,' a multi-component health system intervention designed to improve patients' preparation for kidney failure treatment. Patient-Centered Kidney Transition Care provides a suite of new electronic health information tools (including a disease registry and risk prediction tools) to help providers recognize patients in need of Kidney Transitions Care and focus their attention on patients' values and treatment preferences. Patient-Centered Kidney Transition Care also adds a 'Kidney Transitions Specialist' to the nephrology health care team to facilitate patients' self-management empowerment, shared-decision making, psychosocial support, care navigation, and health care team communication. The PREPARE NOW study is conducted among eight [8] outpatient nephrology clinics at Geisinger, a large integrated health system in rural Pennsylvania. Four randomly selected nephrology clinics employ the Patient Centered Kidney Transitions Care intervention while four clinics employ usual nephrology care. To assess intervention effectiveness, patient reported, biomedical, and health system outcomes are collected annually over a period of 36 months via telephone questionnaires and electronic health records. The PREPARE NOW Study may provide needed evidence on the effectiveness of patient-centered health system interventions to improve nephrology patients' experiences, capabilities, and clinical outcomes, and it will guide the implementation of similar interventions elsewhere. TRIAL REGISTRATION: NCT02722382.

Habitat use and tolerance levels of macroinvertebrates concerning hydraulic stress in hydropeaking rivers - A case study at the Ziller River in Austria.

Artificial flow fluctuations due to the operation of hydropower plants, frequently described as hydropeaking, result in a constant decrease of biomass of specific macrozoobenthos (MZB) taxa. For the presented case study, we assessed three reaches in the Ziller River catchment. At each sampling reach we performed the Multi-Habitat-Sampling (MHS) method with a Water Framework Directive (WFD) compliant AQEM/MHS net according to the Austrian guideline. Additionally, a hydraulic-specific sampling was conducted with a modified Box (Surber) sampler. As a basis for predictive habitat modelling of the MZB fauna, we measured abiotic parameters like mean (v40) and bottom-near (vbottom) flow rate or water depth respectively, for each box sample. In addition, the choriotope type, representing grain size classes, was determined. One of the main results is, that the national status assessment was not capable to reflect the impact of pulse release at the investigated river stretches on the basis of status classes. Moreover, we figured out that 1) habitats of stagnophilic macroinvertebrate taxa are minimized in channelized stretches affected by hydropeaking, leading to heavy quantitative losses for populations, becoming apparent in significant decreases in total individual numbers and biomass for many taxa. 2) The minor respond of the ecological status class in affected stretches by applying the WFD compliant national assessment method for macroinvertebrates owes to the tolerance of rheobiont or rheophilic taxa commonly classified as indicators for good conditions regarding saprobity or degradation score. 3) A development of a stressor-specific sampling design is required as the MHS method largely ignores vulnerable habitats. 4) The habitat suitability of selected species provides efficient expertise for impact assessment and mitigation measure design in terms of predictive habitat modelling.

Longitudinal assessment of hydropeaking impacts on various scales for an improved process understanding and the design of mitigation measures.

Hydropeaking is one of the main pressures on the aquatic ecology in alpine rivers. Beside studies on abiotic process and biotic response on the local scale there is a lack in process understanding on the reach scale. Especially longitudinal changes of hydropeaking impacts based on retention processes have not been studied yet. Thus, based on unsteady one-dimensional and two-dimensional depth averaged modelling it was targeted to investigate possible changes in vertical ramping velocity for the discussion of possible mitigation measures at the local scale. Here, we compared artificial and natural sheltering habitats in terms of peak flow. Additionally, the hydropeaking assessment on various river scales was supported by an evaluation of tributaries in an alpine river system. Based on the modelling results and the discussion of the impact assessment of hydropeaking in different case studies we state, that on the first 5km downstream of the turbine outlet a significant decrease in vertical ramping velocity occurs. In this reach, habitat improvements should focus on increasing retention processes considering the higher risk of stranding for juvenile fish and macroinvertebrates. For morphological mitigation measures at the local scale, it turned out that self-formed, near-natural morphology should be targeted in terms of mitigation measure design compared to artificial sheltering habitats. Abundance and biomass of macroinvertebrates are directly linked to substrate variability in self-formed sheltering habitats downstream of gravel bars. Moreover, we ascertained that tributaries are able to contribute to the 'ecological potential' in multi-stressed hydropeaking rivers by providing spawning and rearing habitats for fish. However, for a sustainable improvement of the aquatic environment on all relevant scales, both sediment and flood dynamics have to be considered as important drivers to establish self-formed sheltering habitats in terms of hydropeaking.

Evaluation of hydropeaking impacts on the food web in alpine streams based on modelling of fish- and macroinvertebrate habitats.

Hydropeaking as a result of peak-load electricity production has been identified as one of the most significant pressures in alpine streams. Scouring of macroinvertebrates leads to downstream transport of aquatic organisms (catastrophic drift). Additionally, invertebrates are affected by periodic drying of wetted area during the dewatering of gravel bars and exposed areas along the banks. Even though fish are physiologically better adapted to switch to suitable habitats, artificial flow fluctuations may be followed by lethal stranding and quick alteration in habitat quantity and quality. Nevertheless, the interactions between pressures on fish and macroinvertebrates in terms of hydropeaking have not been investigated so far. The aim of this paper is to evaluate effects of flow fluctuations on potential epibenthic feeding grounds. Therefore, we evaluated changes in habitat distribution resulting from rapid flow fluctuations in river reaches with different river morphological characteristics, for five different macroinvertebrate taxa. Additionally, microhabitats for brown trout at two different life stages were calculated using representative peaking events (seasonal analysis) based on mid- to long term times series. Moreover, GIS-analysis allowed the evaluation of hydropeaking impacts (interaction) on both, macroinvertebrates and fish. In this study, it could be documented that feeding from the benthos for juvenile and subadult brown trout is inhibited during peak flow and is therefore reduced to times of base flow. Moreover, potential benthic feeding areas occurring at base flow have been found to increase with the level of morphological heterogeneity within analyzed river reaches. Likewise, hydrological sensitivity testing in terms of reducing ∆Q at different levels was performed and revealed that possible positive effects required heterogeneous river morphology as a precondition. However, this approach might be applied for estimating the impacts of hydrological mitigation measures in hydropeaked rivers concerning physical condition and/or growth rate of salmonids considering the river morphology of the investigated stream.

Interrelationships among biological activity, disulfide bonds, secondary structure, and metal ion binding for a chemically synthesized 34-amino-acid peptide derived from alpha-fetoprotein.

A 34-amino-acid peptide has been chemically synthesized based on a sequence from human alpha-fetoprotein. The purified peptide is active in anti-growth assays when freshly prepared in pH 7.4 buffer at 0.20 g/l, but this peptide slowly becomes inactive. This functional change is proven by mass spectrometry to be triggered by the formation of an intrapeptide disulfide bond between the two cysteine residues on the peptide. Interpeptide cross-linking does not occur. The active and inactive forms of the peptide have almost identical secondary structures as shown by circular dichroism (CD). Zinc ions bind to the active peptide and completely prevents formation of the inactive form. Cobalt(II) ions also bind to the peptide, and the UV-Vis absorption spectrum of the cobalt-peptide complex shows that: (1) a near-UV sulfur-to-metal-ion charge-transfer band had a molar extinction coefficient consistent with two thiolate bonds to Co(II); (2) the lowest-energy visible d-d transition maximum at 659 nm, also, demonstrated that the two cysteine residues are ligands for the metal ion; (3) the d-d molar extinction coefficient showed that the metal ion-ligand complex was in a distorted tetrahedral symmetry. The peptide has two cysteines, and it is speculated that the other two metal ion ligands might be the two histidines. The Zn(II)- and Co(II)-peptide complexes had similar peptide conformations as indicated by their ultraviolet CD spectra, which differed very slightly from that of the free peptide. Surprisingly, the cobalt ions acted in the reverse of the zinc ions in that, instead of stabilizing anti-growth form of the peptide, they catalyzed its loss. Metal ion control of peptide function is a saliently interesting concept. Calcium ions, in the conditions studied, apparently do not bind to the peptide. Trifluoroethanol and temperature (60 degrees C) affected the secondary structure of the peptide, and the peptide was found capable of assuming various conformations in solution. This conformational flexibility may possibly be related to the biological activity of the peptide.

Two-domain structure of the td intron-encoded endonuclease I-TevI correlates with the two-domain configuration of the homing site.

I-TevI, the T4 td intron-encoded endonuclease, catalyzes the first step in intron homing by making a double-strand break in the intronless allele within a sequence designated the homing site. The 28 kDa enzyme, which interacts with the homing site over a span of 37 bp, binds as a monomer, contacting two domains of the substrate. In this study, limited proteolysis experiments indicate that I-TevI consists of two domains that behave as discrete physical entities as judged by a number of functional and structural criteria. Overexpression clones for each domain were constructed and the proteins were purified. The carboxy-terminal domain has DNA-binding activity coincident with the primary binding region of the homing site and binds with the same affinity as the full-length enzyme. The isolated amino-terminal domain, contains the conserved GIY-YIG motif, consistent with its being the catalytic domain. Furthermore, site-directed mutagenesis of a conserved arginine residue within the extended motif rendered the full-length protein catalytically inactive, although DNA-binding was maintained. This is the first evidence that the GIY-YIG motif is important for catalytic activity. An enzyme with an N-terminal catalytic domain and a C-terminal DNA-binding domain connected by a flexible linker is in accord with the bipartite structure of the homing site.

High level, context dependent misincorporation of lysine for arginine in Saccharomyces cerevisiae a1 homeodomain expressed in Escherichia coli.

The Saccharomyces cerevisiae a1 homeodomain is expressed as a soluble protein in Escherichia coli when cultured in minimal medium. Nuclear magnetic resonance (NMR) spectra of previously prepared a1 homeodomain samples contained a subset of doubled and broadened resonances. Mass spectroscopic and NMR analysis demonstrates that the heterogeneity is largely due to a lysine misincorporation at the arginine (Arg) 115 site. Arg 115 is coded by the 5'-AGA-3' sequence, which is quite rare in E. coli genes. Lower level mistranslation at three other rare arginine codons also occurs. The percentage of lysine for arginine misincorporation in a1 homeodomain production is dependent on media composition. The dnaY gene, which encodes the rare 5'-AGA-3' tRNA(ARG), was co-expressed in E. coli with the a1-encoding plasmid to produce a homogeneous recombinant a1 homeodomain. Co-expression of the dnaY gene completely blocks mistranslation of arginine to lysine during a1 overexpression in minimal media, and homogeneous protein is produced.

Reduction of the dose to the lens in prophylactic cranial irradiation: a comparison of three different treatment techniques and two different beam qualities.

Three treatment techniques using two beam qualities have been compared on the basis of dose to the lens in prophylactic cranial irradiation. The dose to the lens and the globe was measured with thermoluminescent crystals in an anthropomorphic phantom and calculated by a computer-assisted planning system. A comparison was made of large field and small field techniques using 60Co and 8 MV photons. Modifications to the basic techniques studied included angulation of the gantry, angulation of the couch, and placement of an additional eye block close to the surface. The dose to the lens could be reduced to four percent of the midplane dose by applying the small-field technique combined with the use of 8 MV energy photons, by placing an additional block close to the surface, and by five degree occipitally angling the gantry, as well as rotating the treatment couch to account for the divergence of the beam. The use of 60Co produced an underdosage of the posterior segment of the globe in angled treatment techniques.

Alpha-fetoprotein derived synthetic peptides: assay of an estrogen-modifying regulatory segment.

This study describes the estrogen bioassay of a synthetic peptide fashioned after an amino acid sequence from human alpha-fetoprotein (HAFP). The synthetic peptide (P149), modeled after a portion of the estrogen binding pocket of rat/human AFP chimeras, was produced via F-MOC solid phase chemistry. Bioassay of P149 in the estrogen-sensitive immature rodent uterus demonstrated an anti-estrogenic (40-50% inhibitory) activity in the 23 h but not the 3-4 h uterine response. In contrast to purified HAFP, incubation of the peptide with estrogen was not a prerequisite for inhibitory activity. The estrogen-dependent increase in uterine thrombin and tissue factor, as determined by an enzymatic esterase assay, was inhibited by 30% in rat uterine cytosols. In an in vitro bioassay of estrogen-induced focus formation in MCF-7 human breast cancer cultures, focus development was inhibited by 70% following peptide exposure. The mechanism of the AFP-derived peptide inhibition of estrogen-dependent growth remains to be determined.

Congenital sideroblastic anemia successfully treated by allogeneic bone marrow transplantation.

Allogeneic bone marrow transplantation (BMT) was carried out on a 34-month-old boy with congenital sideroblastic anemia. The patient had been red blood cell transfusion dependent since the age of 7 weeks. He did not respond to therapy with pyridoxine and developed secondary progressive hemosiderosis. The preparatory regimen consisted of busulfan (3.5 mg/kg for 4 days) and cyclophosphamide (50 mg/kg for 4 days). Full engraftment of donor bone marrow was achieved and effective hemopoiesis is still maintained 3 years after BMT.

Busulfan/cyclophosphamide plus bone marrow transplantation is not sufficient to eradicate the malignant clone in juvenile chronic myelogenous leukemia.

Bone marrow transplantation plays an essential role in the successful treatment of both juvenile and adult chronic myelogenous leukemia. Recently, it has been reported that conditioning with high doses of busulfan can successfully replace total body irradiation (TBI), in patients with acute myelogenous leukemia as well as adult chronic myelogenous leukemia. We report here the case of a 29-month-old boy with juvenile chronic myelogenous leukemia (JCML) transplanted with HLA-identical bone marrow after conditioning with busulfan, etoposide and cyclophosphamide. Successful engraftment was followed by early relapse on day 67. A second HLA-identical transplant was performed following myeloablative treatment with TBI. Engraftment was once again successful and the patient remains free of disease more than 24 months after transplantation. We conclude that busulfan is insufficient in eradicating JCML and that TBI is required prior to transplantation.

Endocrine function after bone marrow transplantation without the use of preparative total body irradiation.

Ten children who underwent allogeneic (n = 5) or autologous (n = 5) bone marrow transplantation (BMT) for chronic myelogenous leukaemia (n = 2), acute lymphoblastic leukaemia (n = 1), acute myelogenous leukaemia (n = 2), severe aplastic anaemia (n = 2), malignant histiocytosis (n = 1), neuroblastoma (n = 1) and teratoma (n = 1) were assessed for endocrinological function. Transplant preparative regimens consisted of high-dose cyclophosphamide, high-dose cyclophosphamide in combination with high-dose busulphan, high-dose melphalan as well as BACT (BCNU, cytarabine, cyclophosphamide and 6-thioguanine) chemotherapy. None of the patients received total body irradiation (TBI). Median survival following BMT was 37 months (range 7-115). Growth hormone deficiency was present in only one patient; none of the patients had abnormal thyroid or adrenocortical function. This is in contrast to previous reports in which growth hormone deficiency and abnormal thyroid and adrenocortical function occurred in a much higher percentage of patients after BMT conditioned with TBI.

Successful treatment of CMV retinitis with ganciclovir after allogeneic marrow transplantation.

Cytomegalovirus (CMV) infection of the retina is a well recognized complication in patients with the acquired immune deficiency syndrome but is rarely seen after bone marrow transplantation (BMT). Among a variety of drugs ganciclovir so far appears to be the most effective therapy for CMV retinitis, but in previous studies relapses occurred in all patients in whom ganciclovir was interrupted. We report the clinical findings in a 22-year-old BMT recipient who developed bilateral exudative CMV retinitis 64 days after BMT despite prophylactic treatment with high-titer CMV-immunoglobulins and transfusions of CMV-negative blood products and donor bone marrow. During a 12 day course of treatment with 7.5 mg/kg/day of ganciclovir the CMV retinitis improved and viruria ceased on day 4 of therapy. In contrast to the previous reports, CMV retinitis in this patient continued to improve even after ganciclovir was stopped and eventually complete healing of all intraretinal lesions as well as total reconstitution of the visual acuity was achieved. He is now free of disease and without relapse of CMV retinitis more than 1 year after transplantation.

An overall perspective of X-ray damage to a DNA oligomer mediated by reactive oxygen species.

The products produced by X irradiation of an oxygenated aqueous solution containing d(CpApTpG) were analyzed by NMR spectroscopy and mass spectrometry. Thirteen different base modifications were detected, including a novel product formed by the addition of oxygen to guanine. Seven different strand break products were identified, including strands having 5'-phosphoryl groups, 3'-phosphoryl groups and groups having 3'-phosphoglycolates as termini. The products produced in largest yield contained base modifications: Pyrimidine bases degraded to a formamido moiety, the 8-oxo-7,8-dihydroguanine (8-oxoguanine) lesion, and double base lesions in which both the 8-oxo-7,8-dihydroguanine lesion and a formamido remnant are present.

EEG mapping, psychometric, and polysomnographic studies in restless legs syndrome (RLS) and periodic limb movement disorder (PLMD) patients as compared with normal controls.

OBJECTIVES: Investigation of daytime brain function, psychopathology, and objective and subjective sleep and awakening quality in restless legs syndrome (RLS) and periodic limb movement disorder (PLMD). METHODS: Thirty-three RLS and 26 PLMD patients free of psychotropic drugs were studied as compared with age- and sex-matched normal controls, utilizing electroencephalographic (EEG) mapping and clinical evaluations by the Zung Self-Rating Depression (SDS) and Anxiety Scale (SAS), the Quality of Life Index, the Pittsburgh Sleep Quality Index (PSQI), and the Epworth Sleepiness Scale. In a subsample of 12 RLS patients, 12 PLMD patients, and 12 controls, objective and subjective sleep and awakening quality were evaluated in two sleep laboratory nights (adaptation and baseline night). RESULTS: Scores of the PSQI, SDS, and SAS were found increased in both patient groups; RLS patients showed reduced quality of life, while in the PLMD group daytime sleepiness was increased. EEG mapping demonstrated findings characteristic of major depression in RLS patients and of generalized anxiety disorder in PLMD patients. Polysomnography showed a significant deterioration of sleep efficiency only for RLS patients, while nocturnal awakenings were increased in both patient groups. Concerning sleep architecture, both groups exhibited increased S1 and stage shifts and decreased S2, while only PLMD patients showed an increase in S4. The PLM/(h TST), the PLM/(h wake) and the PLMS-arousal index were significantly increased in both patient groups as compared with controls. Subjective sleep and awakening quality and thymopsychic measures were deteriorated in RLS. Morning mental performance and fine motor activity were deteriorated in both groups, reaction time only in RLS, numerical memory and attention variability only in PLMD. CONCLUSION: EEG mapping revealed neurophysiological correlates of depression and anxiety in RLS and PLMD, respectively, which were confirmed by self-ratings of symptoms.

Restless legs syndrome (RLS) and periodic limb movement disorder (PLMD): acute placebo-controlled sleep laboratory studies with clonazepam.

Restless legs syndrome (RLS) - a common sensorimotor disorder - and periodic limb movement disorder (PLMD) are currently treated with substances of four classes: dopaminergic agents, which are considered the drugs of choice, benzodiazepines, opioids and anticonvulsants. As their effects on sleep variables differ considerably, the aim of the present placebo-controlled sleep laboratory study was to measure the acute effects of 1 mg clonazepam on objective and subjective sleep and awakening quality in ten RLS and 16 PLMD patients, utilizing polysomnography (PSG) and psychometry. Descriptive data analysis demonstrated at the confirmatory level concerning three target variables that - as compared with placebo - clonazepam significantly improved objective sleep efficiency and subjective sleep quality in both patient groups, but failed to reduce the index PLM/h of sleep. At the descriptive level, in PLMD clonazepam improved PLM during time in bed, REM and wakefulness and showed more significant changes in various sleep and awakening measures than in RLS patients, though there were no significant inter-group differences. In conclusion, in both PLMD and RLS clonazepam exhibited acute therapeutic efficacy regarding insomnia, which is quite different from the mode of action of dopamine agonists.

Prevalence of immunecomplex-associated glomerulonephritis in hypertensive subjects.

Glomerulonephritis demonstrable by immunohistochemistry may be present at post mortem in many patients without overt renal diseases. Systematic renal biopsies in severely hypertensive patients have shown a high prevalence of clinically undiagnosed glomerulonephritis. We have examined the kidneys of 423 consecutive subjects who came to post mortem and full-filled criteria for the diagnosis of hypertension. Patients were considered to be hypertensive if this had been clinically documented during life or if the heart weight/body weight ratio was > 0.005 in the absence of known other causes of cardiac hypertrophy. Normotensive controls were selected on the basis of clinically documented normal BP or a heart weight/body weight ratio of < 0.001. Kidneys were examined by immunohistology (PAP technique using human IgA, IgG, IgM antibodies). Excluding cases with liver cirrhosis, only two of the 337 patients with hypertension (= 0.6%) and none of the 49 normotensive patients had mesangial IgA deposits (P = 0.77). This finding argues against the frequent occurrence of latent glomerulonephritis in elderly patients with manifest hypertension.