A meta-analysis of the transcriptional landscape of end stage heart failure with reduced ejection fraction

 

During heart failure (HF) the myocardium undergoes ventricular remodeling, which is accompanied by changes in gene expression. Transcriptomic studies have contributed to fundamental knowledge of this remodeling. However many studies do not agree on the differentially expressed marker genes. We hypothesized that a comprehensive meta-analysis of available studies would help to address this incongruence.

We curated and uniformly processed 14 public transcriptomic data sets consisting of left ventricular samples from 265 healthy and 642 failing hearts. We assessed their comparability by applying transfer learning based classifiers. We then combined all datasets to extract a consensus gene signature. Combining this consensus signature with biological prior knowledge, we estimated transcription factor activities with DoRothEA and pathway activities by footprint analysis with PROGENy.

Although single studies reported highly dissimilar marker genes, transfer knowledge based approaches revealed that disease patterns are conserved across studies. We derived a gene ranking that reflects consistent molecular hallmarks of HF. The ranking is strongly enriched in fibrosis related gene sets and contains significant (all p-values <0.05) footprints of numerous transcription factors including Nanog, Sox2, Pbx3, Mef2; pathways including Jak-Stat and miRNAs including MIR-206, MIR-514.

We demonstrated the feasibility of combining transcriptional studies from different technologies, years and centers. We extracted a consensus gene signature as a valuable resource to understand common molecular patterns in HF. To our knowledge, this report represents the largest meta-analysis of transcriptional HF studies to date.

Selected transcription factor (TF) activities derived via footprint analysis from the consensus gene ranking TF NES Size P-value SOX2 6.3 179 2.59E-10 MYNN −5.7 347 8.14E-09 MTA2 −5.3 29 9.1E-08 ZBTB7A 4.8 66 1.25E-06 BL3 −4.5 26 5.46E-06 ZEB2 −3.9 46 8.99E-05 NANOG 3.81 34 0.00047 PBX3 3.4 41 0.0005 MEF2C 3.1 55 0.001602 MEIS2 2.7 718369 0.00656 NES, normalized enrichment score; size, regulon size.

Graphical summary

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Klaus Tschirer Stiftung

Volume-of-interest imaging with dynamic fluence modulation using multiple aperture devices

Volume-of-interest (VOI) imaging is a strategy in computed tomography (CT) that restricts x-ray fluence to particular anatomical targets via dynamic beam modulation. This permits dose reduction while retaining image quality within the VOI. VOI-CT implementation has been challenged, in part, by a lack of hardware solutions for tailoring the incident fluence to the patient and anatomical site, as well as difficulties involving interior tomography reconstruction of truncated projection data. We propose a general VOI-CT imaging framework using multiple aperture devices (MADs), an emerging beam filtration scheme based on two binary x-ray filters. Location of the VOI is prescribed using two scout views at anterior-posterior (AP) and lateral perspectives. Based on a calibration of achievable fluence field patterns, MAD motion trajectories were designed using an optimization objective that seeks to maximize the relative fluence in the VOI subject to minimum fluence constraints. A modified penalized-likelihood method is developed for reconstruction of heavily truncated data using the full-field scout views to help solve the interior tomography problem. Physical experiments were conducted to show the feasibility of noncentered and elliptical VOI in two applications-spine and lung imaging. Improved dose utilization and retained image quality are validated with respect to standard full-field protocols. We observe that the contrast-to-noise ratio (CNR) is 40% higher compared with low-dose full-field scans at the same dose. The total dose reduction is 50% for equivalent image quality (CNR) within the VOI.

Dynamic fluence field modulation in computed tomography using multiple aperture devices

A novel beam filter consisting of multiple aperture devices (MADs) has been developed for dynamic fluence field modulation (FFM) in CT. Each MAD achieves spatial modulation of x-ray through fine-scale, highly attenuating tungsten bars of varying widths and spacings. Moiré patterns produced by relative motions between two MADs provide versatile classes of modulation profiles. The dual-MAD filter can be designed to achieve specific classes of target profiles. The designed filter was manufactured through a laser-sintering process and integrated to an experimental imaging system that enables linear actuation of the MADs. Dynamic FFM was achieved through a combination of beam shape modulation (by relative MAD motion) and amplitude modulation (by view-dependent mAs). To correct for gains associated with the MADs, we developed an algorithm to account for possible focal spot changes during/between scans and spectral effects introduced by the MADs. We performed FFM designs for phantoms following two imaging objectives: (1) to achieve minimum mean variance in filtered backprojection (FBP) reconstruction, and (2) to flatten the fluence behind the phantom. Comparisons with conventional FFM strategies involving a static bowtie and pulse width modulation were performed. The dual-MAD filter produced modulation profiles closely matched with the design target, providing varying beam widths not achievable by the static bowtie. The entire range of modulation profiles was achieved by 0.373 mm of MAD displacement. The correction algorithm effectively alleviated ring artifacts as a result of MADs while preserving phantom details such as wires and tissue boundaries. Dynamic FFM enabled by the MADs were effective in achieving the imaging objectives and demonstrated superior FFM capabilities compared to the static bowtie. In an ellipse phantom, the FFM of objective 1 achieved the lowest mean variance in all cases investigated. The FFM of objective 2 produce nearly isotropic local noise power spectrum and homogeneous noise magnitude. The dual-MAD filter provides an effective tool for fluence control in CT to overcome limitations of conventional static bowties and to further enable patient-specific FFM studies for a wide range of dose and image quality objectives.

Dynamic fluence field modulation for miscentered patients in computed tomography

Traditional CT image acquisition uses bowtie filters to reduce dose, x-ray scatter, and detector dynamic range requirements. However, accurate patient centering within the bore of the CT scanner takes time and is often difficult to achieve precisely. Patient miscentering combined with a static bowtie filter can result in significant increases in dose, reconstruction noise, and CT number variations, and consequently raise overall exposure requirements. Approaches to estimate the patient position from scout scans and perform dynamic spatial beam filtration during acquisition are developed and applied in physical experiments on a CT test bench using different beam filtration strategies. While various dynamic beam modulation strategies have been developed, we focus on two approaches: (1) a simple approach using attenuation-based beam modulation using a translating bowtie filter and (2) dynamic beam modulation using multiple aperture devices (MADs)-an emerging beam filtration strategy based on binary filtration of the x-ray beam using variable width slits in a high-density beam blocker. Improved dose utilization and more consistent image performance with respect to an unmodulated baseline (static filter) are demonstrated for miscentered objects and dynamic beam filtration in physical experiments. For a homogeneous object miscentered by 4 cm, the dynamic filter reduced the maximum regional noise and dose penalties (compared with a centered object) from 173% to 16% and 42% to 14%, respectively, for a traditional bowtie, 29% to 8% and 24% to 15%, respectively, for a single MAD, and 275% to 11% and 56% to 18%, respectively, for a dual-MAD filter. The proposed methodology has the potential to relax patient centering requirements within the scanner, reduce setup time, and facilitate additional CT dose reduction.

Experimental evaluation of dual Multiple Aperture Devices for Fluence Field Modulated X-Ray Computed Tomography

Acquisition of CT images with comparable diagnostic power can potentially be achieved with lower radiation exposure than the current standard of care through the adoption of hardware-based fluence-field modulation (e.g. dynamic bowtie filters). While modern CT scanners employ elements such as static bowtie filters and tube-current modulation, such solutions are limited in the fluence patterns that they can achieve, and thus are limited in their ability to adapt to broad classes of patient morphology. Fluence-field modulation also enables new applications such as region-of-interest imaging, task specific imaging, reducing measurement noise or improving image quality. The work presented in this paper leverages a novel fluence modulation strategy that uses "Multiple Aperture Devices" (MADs) which are, in essence, binary filters, blocking or passing x-rays on a fine scale. Utilizing two MAD devices in series provides the capability of generating a large number of fluence patterns via small relative motions between the MAD filters. We present the first experimental evaluation of fluence-field modulation using a dual-MAD system, and demonstrate the efficacy of this technique with a characterization of achievable fluence patterns and an investigation of experimental projection data.

Design of dual multiple aperture devices for dynamical fluence field modulated CT

A Multiple Aperture Device (MAD) is a novel x-ray beam modulator that uses binary filtration on a fine scale to spatially modulate an x-ray beam. Using two MADs in series enables a large variety of fluence profiles by shifting the MADS relative to each other. This work details the design and control of dual MADs for a specific class of desired fluence patterns. Specifically, models of MAD operation are integrated into a best fit objective followed by CMA-ES optimization. To illustrate this framework we demonstrate the design process for an abdominal phantom with the goal of uniform detected signal. Achievable fluence profiles show good agreement with target fluence profiles, and the ability to flatten projections when a phantom is scanned is demonstrated. Simulated data reconstruction using traditional tube current modulation (TCM) and MAD filtering with TCM are investigated with the dual MAD system demonstrating more uniformity in noise and illustrating the potential for dose reduction under a maximum noise level constraint.

Fluence-Field Modulated X-ray CT using Multiple Aperture Devices

We introduce a novel strategy for fluence field modulation (FFM) in x-ray CT using multiple aperture devices (MADs). MAD filters permit FFM by blocking or transmitting the x-ray beam on a fine (0.1-1 mm) scale. The filters have a number of potential advantages over other beam modulation strategies including the potential for a highly compact design, modest actuation speed and acceleration requirements, and spectrally neutral filtration due to their essentially binary action. In this work, we present the underlying MAD filtration concept including a design process to achieve a specific class of FFM patterns. A set of MAD filters is fabricated using a tungsten laser sintering process and integrated into an x-ray CT test bench. A characterization of the MAD filters is conducted and compared to traditional attenuating bowtie filters and the ability to flatten the fluence profile for a 32 cm acrylic phantom is demonstrated. MAD-filtered tomographic data was acquired on the CT test bench and reconstructed without artifacts associated with the MAD filter. These initial studies suggest that MAD-based FFM is appropriate for integration in clinical CT system to create patient-specific fluence field profile and reduce radiation exposures.

Significance of enhanced cerebral gray-white matter contrast at 80 kVp compared to conventional 120 kVp CT scan in the evaluation of acute stroke

We aimed to determine whether 80 kVp conventional nonenhanced head CT scans have better gray-white matter contrast than standard 120 kVp scans performed on the same patients. Thirty head CT scans acquired at 80 kVp (CT dose index [CTDI]vol 46) were compared to prior studies in the same patients performed at 120 kVp (CTDIvol 59). Signal (Hounsfield units [HU]), noise (sd HU), and contrast-to-noise ratio per dose (CNRD) were assessed in multiple cerebral gray and white matter regions of interest. A noise correction factor was used to compensate for scanning at different CTDIvol values. Average gray matter signal at 80 kVp and 120 kVP was 33.9 ± 3.5 HU and 29 ± 4.6 HU, respectively (p<0.0001); the averages for white matter were 22.5 ± 3.1 HU and 21.6 ± 4.6 HU, respectively (p=0.11). Corrected noise was 3 ± 0.6 and 2.7 ± 0.6, respectively, for gray matter (p=0.0001), and 2.8 ± 0.6 and 2.6 ± 0.5, respectively, for white matter (p=0.00001). The gray-white matter CNRD was 4.0 ± 1.2 at 80 kVp and 2.8 ± 1 at 120 kVp (p<0.00001). Cerebral gray-white matter CNRD is increased by 40% at 80 kVp compared to conventional 120 kVp CT scans. These findings justify further clinical evaluation in the acute stroke setting.

Normal p21Ras/MAP kinase pathway expression and function in PBMC from patients with polycystic ovary disease

Polycystic ovary disease (PCOD) is associated with insulin resistance and increased prevalence of type II diabetes mellitus (T2DM). The p21Ras/MAP kinase is a major intracellular signaling pathway mediating insulin signaling in insulin responsive tissues. The expression, regulation and function of the p21Ras/MAP kinase pathway in PCOD patients were examined. Peripheral blood mononuclear cells (PBMC) were isolated from ten patients with PCOD and ten controls. The expression of p21Ras and its regulatory proteins; hSOS1 and p120GAP were studied. The basal and phytohemaglutinin (PHA) or insulin stimulated phosphorylation of MAP kinase was determined. Expression of p21Ras, and its regulatory proteins hSOS1 and p120GAP were similar in PCOD patients and controls. Basal, PHA and insulin stimulated phosphorylation of MAP kinase, were also comparable in the two groups as well as their PBMC proliferative response. These data indicate that the expression and overall function of the p21Ras/MAP kinase pathway remain intact in non-diabetic patients with PCOD.

[Sepsis associated cholestasis in adults]

Hepatic injury presenting as jaundice, hypglycemia, encephalopathy, coagulation disturbances and a significant increase in transaminases in a late well recognized complication of sepsis. Less known is a cholestatic liver injury, which can precede sepsis. This type of early liver injury is characterized by a rise of direct bilirubin and less prominent increase in liver enzymes. Experimental work in animal models demonstrates that sepsis associated cholestasis is mediated by a variety of gram negative bacterial endotoxins and cytokines which interfere with the function of bile acid intracellular transporters. Although sepsis associated cholestasis is quite common, its clinical and prognostic characteristics are not widely appreciated. This often results in performance of unnecessary procedures and delayed diagnosis. Here we review the relevant updated literature regarding the pathophysiological basis of this phenomenon and its clinical presentation and implications.

Centers for Disease Control and Prevention partnerships with external behavioral and social scientists. Roles, extramural funding, and employment

The Centers for Disease Control and Prevention (CDC) must have strong external partnerships with behavioral and social scientists to refine and carry out its research and programmatic mission. This article examines funding, employment, and other mechanisms used to develop and foster such partnerships. The authors describe in detail funding mechanisms (especially the often-used cooperative agreement and contracting mechanisms) and identify specific sources of information about funding opportunities. Furthermore, they describe several different long- and short-term employment mechanisms that can be used to link CDC staff and external behavioral scientists. Finally, external behavioral and social scientists can serve in important roles as members of CDC advisory committees, peer reviewers of funding applications, and consultants; examples of these opportunities are also provided.

Physical activity of public housing residents in Birmingham, Alabama

OBJECTIVES

Because few data are available concerning physical activity among minority and low-income persons, we characterized physical activity patterns among public housing residents.

METHODS

Two separate cross-sectional surveys were conducted 1 year apart of randomly selected residents of eight rental communities administered by the housing authority of Birmingham, Ala. Indigenous interviewers completed 687 interviews in survey 1 and 599 in survey 2.

RESULTS

In both surveys, respondents were most frequently young adult African-American women, reflecting the predominance of women in these communities. Participants were generally poorly educated and either unemployed or working in service occupations. Thirty percent of the respondents in both surveys reported no participation in any of 13 physical activities in the previous year; approximately half reported activity levels equivalent to or less than walking 4 hours per week for 8 months of the year. Respondents who were younger and male were significantly more likely to have higher activity levels.

CONCLUSIONS

A sedentary life-style is common among this low-income minority group, and, thus, interventions to promote exercise in these communities are needed.

Noise pollution in the operating room: a hazard to surgeons, personnel, and patients

Noise levels up to 118 dB--a level that is potentially damaging to the hearing--were measured in the operating room, notably during the use of high-speed gas turbine bone-cutting drills. Suction tips, which had trapped tissue "whistles" inside, yielded noise levels of up to 96 dB. Surgeons, staff, and patients should be cautioned against such noises and shielded in prolonged cases. We offer a review of acoustical criteria for various practical noises and duration of safe exposure.

Identification of the active site residues in the nsP2 proteinase of Sindbis virus

The nonstructural polyproteins of Sindbis virus are processed by a virus-encoded proteinase which is located in the C-terminal domain of nsP2. Here we have performed a mutagenic analysis to identify the active site residues of this proteinase. Substitution of other amino acids for either Cys-481 or His-558 completely abolished proteolytic processing of Sindbis virus polyproteins in vitro. Substitutions within this domain for a second cysteine conserved among alphaviruses, for four other conserved histidines, or for a conserved serine did not affect the activity of the enzyme. These results suggest that nsP2 is a papain-like proteinase whose catalytic dyad is composed of Cys-481 and His-558. Since an asparagine residue has been implicated in the active site of papain, we changed the four conserved asparagine residues in the C-terminal half of nsP2 and found that all could be substituted without total loss of activity. Among papain-like proteinases, the residue following the catalytic histidine is alanine or glycine in the plant and animal enzymes, and the presence of Trp-559 in alphaviruses is unusual. A mutant enzyme containing Ala-559 was completely inactive, implying that Trp-559 is essential for a functional proteinase. All of these mutations were introduced into a full-length clone of Sindbis virus from which infectious RNA could be transcribed in vitro, and the effects of these changes on viability were tested. In all cases it was found that mutations which abolished proteolytic activity were lethal, whether or not these mutations were in the catalytic residues, indicating that proteolysis of the nonstructural polyprotein is essential for Sindbis replication.

Erythropoietin has a mitogenic and positive chemotactic effect on endothelial cells

Erythropoietin is known to be a hematopoietic growth factor with a singularly specific action on the proliferation and differentiation of erythroid progenitor cells. We have observed a dose-dependent proliferative action of human recombinant erythropoietin on human umbilical vein endothelial cells and bovine adrenal capillary endothelial cells. Binding studies with radioiodinated recombinant human erythropoietin revealed a large number (approximately 27,000) of an apparent single class of receptors with an affinity in the 10(-9) M range. Linkage of the radiolabeled ligand to its receptor via a bifunctional crosslinking agent allowed us to identify an endothelial cell protein of 45 kDa as the principal receptor associated with this mitogenic effect of erythropoietin. Recombinant human erythropoietin also enhanced the migration of endothelial cells.

Evaluation of a diffusion strategy for school-based hypertension education

The purpose of this research was to evaluate the effectiveness of hypertension (HBP) education within a population of sixth grade students (n = 1204) and their parents (n = 1446). The "3Rs and HBP" curriculum attempts to diffuse the HBP information from teachers, to pupils and then to parents using the sixth grade son/daughter as a "health messenger." This curriculum was tested with and without a home blood pressure measurement component versus controls in 21 schools randomly assigned to the three conditions. Postintervention data were collected from students at school and from their parents at home interviews. Students were compared for knowledge, blood pressure measurement skill, and home diffusion activities. Parents were compared for knowledge, risk factor reduction, blood pressure, care-seeking, and compliance behaviors. Student self-esteem and family interactions were investigated as possible intervening variables in the diffusion process. Student knowledge, BP measurement skills, and diffusion to parents was increased by the 3Rs and HBP curriculum with the home component. Parental effects beyond the diffusion process were limited to knowledge improvement in certain groups. Family interaction (level and style) was found to be a significant intervening variable in the diffusion process.

Analysis of contraceptive behavior of sexually active female adolescents in the United States

Drawing on a theoretical model of adolescent contraceptive behavior, we examined the relationships between various social and behavioral variables and contraceptive use by sexually active female adolescents. Hypotheses were tested with the use of a national random sample of sexually active female adolescents (n = 1426), aged 15 to 20 years, from Cycle III of the National Survey of Family Growth. The data were analyzed with Pearson correlation coefficients and multiple regression analysis. Noncompliance with the initial birth control method was the strongest predictor of the adolescents' contraceptive behavior at the time of the interview. Not acquiring birth control at the initial family planning visit and the frequency of family planning visits during the previous 12 months were the second and third best predictors of subjects' contraceptive use. Coital frequency and the length of time between first coitus and the initiation of birth control each explained a small amount of additional variation in the regression model. When combined, these five variables explained 40% of the variation in the contraceptive behavior of this representative sample of sexually active female adolescents. The findings could be useful for clinicians in providing more effective birth control counseling to adolescent patients.

Prolongation of skin allograft survival by pretreatment of allograft with monoclonal antibody and steroids

Treatment of large burns would be simplified by the development of a nonsensitizing allograft which would survive permanently. In our hands, in vitro immune modification of the allograft has prolonged graft survival in mice across major histocompatibility barriers (H-2d to H-2b) by 36% (steroid pretreatment) and 25% (monoclonal antibody to the Iad antigen found on donor Langerhans cells). To our knowledge, monoclonal antibody has not been employed in this capacity previously. Double grafting studies suggest that neither MK-D6 nor steroids enhance graft survival by systemic immunosuppression. Moreover, MK-D6 acts upon the afferent limb of the immune response while steroids interrupt the efferent limb (and probably afferent limb). These effects are not additive. This modest improvement in allograft survival may have profound importance since allografts supported briefly by host immunosuppression have gone on to indefinite survival in burn victims without further immunologic intervention. This improvement in allograft survival is of fundamental immunologic interest. If synergistic pretreatments can be found, it may ultimately allow allografting of burn victims with the expectation of indefinite graft survival.

Nonstructural proteins nsP3 and nsP4 of Ross River and O'Nyong-nyong viruses: sequence and comparison with those of other alphaviruses

We have sequenced the nsP3 and nsP4 region of two alphaviruses, Ross River virus and O'Nyong-nyong virus, in order to examine these viruses for the presence or absence of an opal termination codon present between nsP3 and nsP4 in many alphaviruses. We found that Ross River virus possesses an in-phase opal termination codon between nsP3 and nsP4, whereas in O'Nyong-nyong virus this termination codon is replaced by an arginine codon. Previous studies have shown that two other alphaviruses, Sindbis virus and Middelburg virus, possess an opal termination codon separating nsP3 and nsP4 [E.G. Strauss, C.M. Rice, and J.H. Strauss (1983), Proc. Natl. Acad. Sci. USA 80, 5271-5275], whereas Semliki Forest virus possesses an arginine codon in lieu of the opal codon [K. Takkinen (1986), Nucleic Acids Res. 14, 5667-5682]. Thus, of the five alphaviruses examined to date, three possess the opal codon and two do not. Production of nsP4 requires readthrough of the opal codon in those alphaviruses that possess this termination codon and the function of the termination codon may be to regulate the amount of nsP4 produced. It is an open question then as to whether alphaviruses with no termination codon use other mechanisms to regulate the activity of this gene. The nsP4s of these five alphaviruses are highly conserved, sharing 71-76% amino acid sequence similarity, and all five contain the Gly-Asp-Asp motif found in many RNA virus replicases. The nsP3s are somewhat less conserved, sharing 52-73% amino acid sequence similarity throughout most of the protein, but each possesses a nonconserved C-terminal domain of 134 to 246 amino acids of unknown function.

Megavoltage radiotherapy using water bolus in the treatment of Kaposi's sarcoma

Between 1976 and 1983, 28 patients with Kaposi's sarcoma were treated in the Department of Radiation and Clinical Oncology of the Hadassah University Hospital in Jerusalem. Most of the patients (16, i.e. 57%) were Jews of European origin. Eighteen (64.2%) of the patients presented with severe leg edema in addition to multifocal, disseminated skin lesions. Only one patient was free of clinical disease in the lower extremities. Large, ulcerated masses were seen in three patients. The affected limbs were immersed in a water bath and irradiated with two-opposing portals to a total dose of 3000 rads. Total disappearance of the skin lesions was achieved in 89% of the patients, although the limb edema regressed completely in only 56% of the patients.

Chronological supplement to the Carcinogenic Potency Database: standardized results of animal bioassays published through December 1982

This paper is a chronological supplement to our earlier publication, "A Carcinogenic Potency Database of the Standardized Results of Animal Bioassays." We report here results of carcinogenesis bioassays published in Technical Reports of the National Cancer Institute/National Toxicology Program between July 1980 and December 1982, and the general literature between July 1981 and December 1982. This supplement includes results of 280 long-term, chronic experiments of 114 test compounds, and reports the same information about each experiment in the same plot format as the earlier paper: e.g., the species and strain of test animal, the route and duration of compound administration, dose level and other aspects of experimental protocol, histopathology and tumor incidence, TD50 and its statistical significance, dose response, author's opinion about carcinogenicity, and literature reference. While a number of appendices are provided to facilitate use of this supplement, we have not duplicated here the material published earlier. Instead, we refer the reader to the earlier publications (Peto et al. and Gold et al.) for a thorough description of the numerical index of carcinogenic potency (TD50), a guide to the plot of the database, and a discussion of the sources of data, the rationale for the inclusion of particular experiments and particular target sites, and the conventions adopted in summarizing the literature. For 44 of the 114 chemicals reported in this second plot, results of earlier experiments are also given in the first plot; since only 1981-1982 results are reported here, the first plot is required for these repeated compounds. In this paper we also give corrections for errors that appeared in the earlier publication.

Spectrum of deranged sodium homeostasis in essential hypertension

Essential hypertension is thought to produce a uniform exaggerated natriuresis and diuresis. Because validation of this formulation in humans is incomplete, the natriuretic and diuretic responses to acute volume expansion were characterized by using water immersion to the neck. This method provides a volume stimulus identical to that induced by 2 L of saline without plasma compositional change. Twenty-seven subjects with essential hypertension were studied on three occasions in the seated posture while in balance on a 10 mEq Na, 100 mEq K diet: during the seated control study, during 4 hours of head-out immersion, and during saline infusion (2 L/2 hours). Four subjects had exaggerated urinary Na excretion in response to neck immersion (Group 3), and 16 had a normal response (Group 2) indistinguishable from that of 15 previously studied normal subjects. The remaining seven subjects (Group 1) had blunted or absent natriuretic responses compared with that in normal subjects (p less than 0.005). Similar results were obtained with saline administration; cumulative Na excretion in Group 1 was markedly less than that in Group 2 and the normal subjects. The heterogeneity in Na excretion indicates that an exaggerated natriuresis is not a uniform concomitant of essential hypertension. The significant inverse correlation between basal plasma aldosterone level and peak urinary as well as cumulative Na excretion suggests that plasma aldosterone constitutes a determinant of the differing natriuretic responses. In contrast to findings with urinary Na excretion, the diuretic responses of Groups 1 and 2 were identical. The striking dissociation between renal Na and water handling underscores the specificity of the derangement in renal Na handling.

A carcinogenic potency database of the standardized results of animal bioassays

The preceding paper described our numerical index of carcinogenic potency, the TD50 and the statistical procedures adopted for estimating it from experimental data. This paper presents the Carcinogenic Potency Database, which includes results of about 3000 long-term, chronic experiments of 770 test compounds. Part II is a discussion of the sources of our data, the rationale for the inclusion of particular experiments and particular target sites, and the conventions adopted in summarizing the literature. Part III is a guide to the plot of results presented in Part IV. A number of appendices are provided to facilitate use of the database. The plot includes information about chronic cancer tests in mammals, such as dose and other aspects of experimental protocol, histopathology and tumor incidence, TD50 and its statistical significance, dose response, author's opinion and literature reference. The plot readily permits comparisons of carcinogenic potency and many other aspects of cancer tests; it also provides quantitative information about negative tests. The range of carcinogenic potency is over 10 million-fold.

Comparison of the effects of water immersion and saline infusion on central haemodynamics in man

1. The effects of acute intravenous infusion of 2 litres of saline/120 min on pulmonary capillary blood flow (Q̇c), diffusing capacity per unit of alveolar volume (DL/VA), functional residual capacity (FRC), and pulmonary tissue plus capillary blood volume (VTPC) were compared with the changes induced by water immersion to the neck for 4 h. Serial measurements were made at 30 min intervals in five normal subjects, utilizing a non-invasive rebreathing method with a gas mixture containing 0·5% acetylene, 0·3% C180, 10% He, 21% O2 and 68·2% N2.

2. Infusion of saline produced a rise in Q̇c which was similar to that induced by immersion. This increment in Q̇c persisted for the 3 h of observation after stopping the infusion, in contrast to the prompt decrease in Q̇c to pre-study values after cessation of immersion.

3. DL/VA was unaffected by saline administration in contrast to the marked and prompt increment induced by immersion.

4. Pulmonary tissue plus capillary blood volume was unchanged during both saline administration and immersion, suggesting that neither gradual saline administration nor immersion induces major extravasation of fluid into the pulmonary interstitial space.

5. The present data indicate that the ‘volume stimulus’ of immersion is similar to that of saline-induced extracellular fluid volume expansion in normal seated subjects. Immersion may be a preferred investigative approach for assessing the effects of volume expansion in subjects in whom rapid reversibility of the ‘volume stimulus’ is desirable.

Effects of water immersion on renal hemodynamics in normal man

Although previous studies have demonstrated that water immersion to the neck (NI) results in a significant natriuresis and diuresis, the mechanisms are incompletely delineated. Since recent studies have demonstrated that NI induces a marked increase in cardiac index, it is possible that, as a consequence, renal hemodynamics may be augmented markedly during NI thereby mediating the encountered renal changes. The present study was undertaken to delineate the effects of NI on renal plasma flow and glomerular filtration rate as assessed by the clearance of PAH (CPAH) and inulin (CIn), respectively. Nine normal male subjects were studied on two occasions, control and NI. The conditions of seated posture and time of day were identical. Immersion did not alter CIn or CPAH at a time when sodium excretion was increasing markedly. The constancy of CPAH during NI suggests that renal blood flow is unaltered and that the natriuresis of NI is mediated independently of alterations in overall renal perfusion. The sluggish decline of a naturiuresis during recovery is consistent with the presence of a humoral factor contributing to the encountered natriuresis.

Determinants of deranged sodium and water homeostasis in decompensated cirrhosis

Previous studies from this laboratory have demonstrated that the redistribution of blood volume and concomitant central hypervolemia induced by water immersion to the neck (NI) results in a significant natriuresis, kaliuresis, and diuresis. The NI model was utilized to assess the role of "effective volume" and hyperaldosteronism in the impairment of sodium and water handling in cirrhosis. Eleven cirrhotic patients were studied twice while in balance on a 10 mEq. Na, 100 mEq. K diet: control and NI. The conditions of seated posture and time of day were identical. UNaV was constant throughout C, ranging from 1 to 2 muEq per minute. During NI, UNaV increased progressively from 1 +/- 1 (S.E.M.) during the prestudy hour to 89 +/- 32 muEq per minute during hour 5 of NI (p less than 0.02), greatly exceeding the comparable value found in normal subjects on an identical diet. (See article).

Effects of water immersion to the neck on pulmonary circulation and tissue volume in man

Utilizing the rebreathing of a gas mixture containing C2H2, C180, He O2, and N2, we obtained serial measurements of the pulmonary capillary blood flow (Qc), diffusing capacity per unit of alveolar volume (DL/VA), functional residual capacity (FRC), pulmonary tissue plus capillary blood volume (VTPC), and O2 comsumption (VO2) in five normal subjects under the following conditions: 1) 6 h of sitting, 2) 4 h of sitting while immersed in thermoneutral water to the neck, and 3) 4 h of lying in thermoneutral water to the neck. Water immersion (NI) was preceded and followed by 1-h prestudy and 1-h recovery periods. The measurements were made at 30-min intervals. Seated NI produced a fourfold increase in sodium excretion (UNaV), a 25-36% increase in Qc, a 45-59% increase in DL/VA, and a 30-36% decrease in FRC. This occurred as early as the 1st h of NI and persisted throughout the 4-h period of study. Throughout the seated control and NI periods, VO2, heart rate, and VTPC remained constant. During supine NI, Qc, HR, DL/VA, FRC, and VO2 did not differ significantly from supine prestudy. These date demonstrate that seated NI causes a significant increase of Qc and DL/VA which persists throughout the immersion period. Furthermore, the lack of change of VTPC suggests that the central vascular engorgement induced by seated NI is not accompanied by extravasation of fluid into the pulmonary interstitial space.