An evaluation of the Chesapeake Bay management strategy to improve water quality in small agricultural watersheds

Chesapeake Bay water quality has been a concern since 1970. In rural areas, agriculture is the dominant N and P source, and the voluntary application of best management practices (BMPs) is the primary management tool. Here we test the hypothesis that the current management approach of primarily voluntary, untargeted BMP implementation is insufficient to create detectable, widespread reductions in N, P, and total suspended solid (TSS) concentrations in agricultural watersheds of the Choptank basin, a tributary of Chesapeake Bay. To test this hypothesis, we assessed BMP implementation and sampled water quality on participating farms, at intermediate streams within each watershed, and at watershed outlets of four watersheds from 2013 to 2014. We also present water quality data from 2003 to 2014 at the outlets of 12 additional agricultural and one forested watershed and survey-directed interviews of farmers. By the end of 2014, large numbers of BMPs, both structural and cultural, had been implemented. Of the 16 agricultural watersheds, 50% showed significant decreases in baseflow N, 37.5% showed no changes, and 12.5% showed increasing TN. Baseflow P significantly decreased at just one watershed, increased at one, and remained stable at 14. Stormflow N was similar to baseflow, but stormflow P was 5 times higher than baseflow. These data partially support our hypothesis. Surveys suggested farmers considered themselves responsible for the quality of water leaving their farms, but out-of-pocket cost was the major impediment to further BMP adoption. We suggest that greater outreach and more financial support for farmers to implement BMPs is required to increase the types and densities of BMPs needed to achieve regional water quality goals.

Multichannel deconvolution of vibrational signals: A state-space inverse filtering approach

Deconvolution of noisy measurements, especially when they are multichannel, has always been a challenging problem. The processing techniques developed range from simple Fourier methods to more sophisticated model-based parametric methodologies based on the underlying acoustics of the problem at hand. Methods relying on multichannel mean-squared error processors (Wiener filters) have evolved over long periods from the seminal efforts in seismic processing. However, when more is known about the acoustics, then model-based state-space techniques incorporating the underlying process physics can improve the processing significantly. The problems of interest are the vibrational response of tightly coupled acoustic test objects excited by an out-of-the-ordinary transient, potentially impairing their operational performance. Employing a multiple input/multiple output structural model of the test objects under investigation enables the development of an inverse filter by applying subspace identification techniques during initial calibration measurements. Feasibility applications based on a mass transport experiment and test object calibration test demonstrate the ability of the processor to extract the excitations successfully.

Transient recovery problem in acoustics: A multichannel model-based deconvolution approach

Critical acoustical systems operating in complex environments contaminated with disturbances and noise offer an extreme challenge when excited by out-of-the-ordinary, impulsive, transient events that can be undetected and seriously affect their overall performance. Transient impulse excitations must be detected, extracted, and evaluated to determine any potential system damage that could have been imposed; therefore, the problem of recovering the excitation in an uncertain measurement environment becomes one of multichannel deconvolution. Recovering a transient and its initial energy has not been solved satisfactorily, especially when the measurement has been truncated and only a small segment of response data is available. The development of multichannel deconvolution techniques for both complete and incomplete excitation data is discussed, employing a model-based approach based on the state-space representation of an identified acoustical system coupled to a forward modeling solution and a Kalman-type processor for enhancement and extraction. Synthesized data are utilized to assess the feasibility of the various approaches, demonstrating that reasonable performance can be achieved even in noisy environments.

Multichannel spectral estimation in acoustics: A state-space approach

Spectral estimation is a necessary methodology to analyze the frequency content of noisy data sets especially in acoustic applications. Many spectral techniques have evolved starting with the classical Fourier transform methods based on the well-known Wiener-Khintchine relationship relating the covariance-to-spectral density as a transform pair culminating with more elegant model-based parametric techniques that apply prior knowledge of the data to produce a high-resolution spectral estimate. Multichannel spectral representations are a class of both nonparametric, as well as parametric, estimators that provide improved spectral estimates. In any case, classical nonparametric multichannel techniques can provide reasonable estimates when coupled with peak-peaking methods as long as the signal levels are reasonably high. Parametric multichannel methods can perform quite well in low signal level environments even when applying simple peak-picking techniques. In this paper, the performance of both nonparametric (periodogram) and parametric (state-space) multichannel spectral estimation methods are investigated when applied to both synthesized noisy structural vibration data as well as data obtained from a sounding rocket flight. It is demonstrated that for the multichannel problem, state-space techniques provide improved performance, offering a parametric alternative compared to classical methods.

Vibrational processing of a dynamic structural flight system: A multichannel spectral estimation approach

Dynamic testing of large flight vehicles (rockets) is not only complex, but also can be very costly. These flights are infrequent and can lead to disastrous effects if something were to fail during the flight. The development of sensors coupled to internal components offers a great challenge in reducing their size, yet still maintaining their precision. Sounding rockets provide both a viable and convenient alternative to the more costly vehicular flights. Some of the major objectives are to test various types of sensors for monitoring components of high interest as well as investigating real-time processing techniques. Signal processing presents an extreme challenge in this noisy multichannel environment. The estimation and tracking of modal frequencies from vibrating structures is an important set of features that can provide information about the components under test; therefore, high resolution multichannel spectral processing is required. The application of both single channel and multichannel techniques capable of producing reliable modal frequency estimates of a vibrating structure from uncertain accelerometer measurements is discussed.

Multichannel processing of vibrational measurements: A constrained subspace application

Monitoring mechanical systems operating in uncertain environments contaminated with both environmental disturbances and noise lead directly to low signal-to-noise-ratios, creating an extremely challenging processing problem, especially in real-time. In order to estimate the performance of a particular system from uncertain vibrational data, it is necessary to identify its unique resonant (modal) frequency signature. The monitoring of structural modes to determine the condition of a device under investigation is essential, especially if it is a critical entity of an operational system. The development of a model-based scheme capable of the on-line tracking of the inherent structural modal frequencies by applying both constrained subspace identification techniques to extract the modal frequencies and state estimation methods to track the evolution is discussed. An application of this approach to a cylindrical structural device (pipe-in-air) is analyzed based on theoretical simulations along with controlled validation experiments, including injected anomalies illustrate the approach and performance. Statistics are gathered to bound potential processors for real-time performance employing these constrained techniques.

The ACHRU-CPP versus usual care for older adults with type-2 diabetes and multiple chronic conditions and their family caregivers: study protocol for a randomized controlled trial

BACKGROUND

Many community-based self-management programs have been developed for older adults with type-2 diabetes mellitus (T2DM), bolstered by evidence from randomized controlled trials (RCTs) that T2DM can be prevented and managed through lifestyle modifications. However, the evidence for their effectiveness is contradictory and weakened by reliance on single-group designs and/or small samples. Additionally, older adults with multiple chronic conditions (MCC) are often excluded because of recruiting and retention challenges. This paper presents a protocol for a two-armed, multisite, pragmatic, mixed-methods RCT examining the effectiveness and implementation of the Aging, Community and Health Research Unit-Community Partnership Program (ACHRU-CPP), a new 6-month interprofessional, nurse-led program to promote self-management in older adults (aged 65 years or older) with T2DM and MCC and support their caregivers (including family and friends).

METHODS/DESIGN

The study will enroll 160 participants in two Canadian provinces, Ontario and Alberta. Participants will be randomly assigned to the control (usual care) or program study arm. The program will be delivered by registered nurses (RNs) and registered dietitians (RDs) from participating diabetes education centers (Ontario) or primary care networks (Alberta) and program coordinators from partnering community-based organizations. The 6-month program includes three in-home visits, monthly group sessions, monthly team meetings for providers, and nurse-led care coordination. The primary outcome is the change in physical functioning as measured by the Physical Component Summary (PCS-12) score from the short form-12v2 health survey (SF-12). Secondary client outcomes include changes in mental functioning, depressive symptoms, anxiety, and self-efficacy. Caregiver outcomes include health-related quality of life and depressive symptoms. The study includes a comparison of health care service costs for the intervention and control groups, and a subgroup analysis to determine which clients benefit the most from the program. Descriptive and qualitative data will be collected to examine implementation of the program and effects on interprofessional/team collaboration.

DISCUSSION

This study will provide evidence of the effectiveness of a community-based self-management program for a complex target population. By studying both implementation and effectiveness, we hope to improve the uptake of the program within the existing community-based structures, and reduce the research-to-practice gap.

TRIAL REGISTRATION

ClinicalTrials.gov, Identifier: NCT02158741 . Registered on 3 June 2014.

Model-based failure detection for cylindrical shells from noisy vibration measurements

Model-based processing is a theoretically sound methodology to address difficult objectives in complex physical problems involving multi-channel sensor measurement systems. It involves the incorporation of analytical models of both physical phenomenology (complex vibrating structures, noisy operating environment, etc.) and the measurement processes (sensor networks and including noise) into the processor to extract the desired information. In this paper, a model-based methodology is developed to accomplish the task of online failure monitoring of a vibrating cylindrical shell externally excited by controlled excitations. A model-based processor is formulated to monitor system performance and detect potential failure conditions. The objective of this paper is to develop a real-time, model-based monitoring scheme for online diagnostics in a representative structural vibrational system based on controlled experimental data.

Successful treatment of Staphylococcus aureus bacterial endocarditis in a renal transplant recipient

We report the successful treatment of Staphylococcus aureus endocarditis in a renal transplant recipient with preservation of his renal allograft. A 44-year-old man presented to the emergency room with sudden onset of fevers and rigors 7 weeks after renal transplantation. Infective endocarditis was diagnosed by Duke's Criteria (Durack et al. New criteria for the diagnosis of infective endocarditis. Am J Med 1994: 96: 200-209) with multiple positive blood cultures for S. aureus and a mitral valve vegetation on transesophageal echocardiogram. He was treated with intravenous antibiotics for 6 weeks with continuation of his immunosuppression. He has remained clinically stable for over 5 years. Although the treatment of S. aureus endocarditis in immunosuppressed transplant patients has traditionally resulted in loss of their allograft, prompt diagnosis and appropriate antibiotics with continued immunosuppressive therapy resulted in a successful outcome and allograft preservation in this case.

Pediatric IgA nephropathy: clinical features at presentation and outcome for African-Americans and Caucasians

AIM

To determine the disease severity at onset and outcome for African-American and Caucasian pediatric patients with IgA nephropathy diagnosed at the Le Bonheur Children's Medical Center since 1990.

DESIGN/METHODS

The study population included all patients diagnosed with IgA nephropathy at the Le Bonheur Children's Medical Center from January 1990 through February 2004. All were below age 18 at biopsy. Clinical features assessed at diagnosis were age, gender, presence of hypertension, history of macroscopic hematuria, degree of proteinuria, severity of renal histology and pattern for immunofluorescent reactants.

STATISTICS

Student's t-test was used to compare age at biopsy and length of follow-up between the 2 groups. Fisher's exact test was used to compare features at presentation and patterns of immunofluorescence. Kidney survival was predicted by the Kaplan-Meier method.

RESULTS

Forty-seven patients (17 African-American, 29 Caucasian) were studied. Clinical features at diagnosis and pattern for all immunofluorescent reactants did not differ significantly between the 2 groups. Mesangial deposition of C1q occurred in 4/17 African-Americans as compared to 1/27 Caucasians (p = 0.06). Four patients (2 African-Americans, 2 Caucasians) progressed to end-stage renal disease. Predicted kidney survival was 96% (94% in African-Americans and 97% in Caucasians) at 1 year and 91% (94% in African-Americans and 89% in Caucasians) at 5 years from diagnosis. Mean time from diagnosis to end-stage renal disease or last follow-up was 3.3 years (3.8 for African-Americans, 3.0 for Caucasians). Macroscopic hematuria occurred prior to diagnosis for 90% of the Caucasian as compared to 61% of the African-American patients (p = 0.03). Urinalysis was normal at last follow-up visit for 24% of African-American patients and 32% of Caucasian patients.

CONCLUSION

In a relatively small sample from a single center, except for the difference in macroscopic hematuria, clinical features at diagnosis and outcome of IgA nephropathy appear similar for African-American and Caucasian pediatric patients.

Regulation of proximal tubule sodium/hydrogen antiporter with chronic volume contraction

We developed a model of volume contraction in rabbits by using a furosemide/low-salt diet to follow changes, if any, in proximal tubule Na+/H+ exchanger 3 (NHE3) mRNA and brush-border protein. The rabbits' plasma renin, aldosterone, and urine sodium content confirmed the volume-contracted state. RNase protection assays demonstrated increases in treated-animal NHE3 mRNA as a percentage of control with 172 +/- 23, 154 +/- 15, 153 +/- 14, and 141 +/- 7 (SE) % (P < 0.05) at 1, 5, 10, and 31 days, respectively. Western analysis of brush-border membrane with NHE3 antibody revealed increased immunoreactivity in treated animals as a percentage of control with 120 +/- 30, 190 +/- 59, 307 +/- 72, and 427 +/- 41% (P < 0.05) at 1, 5, 10, and 31 days, respectively. There was no significant difference in serum potassium, bicarbonate, and cortisol in control vs. experimental animals. These data suggest that there is chronic upregulation of NHE3 in the volume-contracted state.

Lovastatin-induced rhabdomyolysis possibly associated with clarithromycin and azithromycin

OBJECTIVE

To describe two cases of rhabdomyolysis in patients taking lovastatin that were precipitated by the use of the newer macrolide antibiotics clarithromycin and azithromycin.

CASE SUMMARIES

In each case, the patients were treated over 5 years with lovastatin and developed rhabdomyolysis that coincided with the completion of a prescribed regimen of a newer macrolide antibiotic. Following intravenous hydration and administration of bicarbonate, the patients' condition resolved without permanent' sequelae.

DISCUSSION

Rhabdomyolysis is a clinical syndrome resulting from the destruction of skeletal muscle that may progress to renal failure Several drugs have been associated with rhabdomyolysis, including lovastatin, a hydroxymethylglutaryl-coenzyme A reductase inhibitor. Erythromycin is a macrolide antibiotic that may increase the risk of lovastatin-induced rhabdomyolysis. To our knowledge, these cases are the first published reports of lovastatin-induced rhabdomyolysis associated with azithromycin and clarithromycin.

CONCLUSIONS

The risk of drug-induced rhabdomyolysis due to the potential interaction between lovastatin and azithromycin or clarithromycin should be considered before the concomitant use of these agents.

Ultrastructural, protein, and lipid changes in liver associated with chlordecone treatment of mice

Pretreatment of mice with chlordecone (CD) reduced hepatic accumulation of a subsequent dose of [14C]CD without significantly changing [14C]CD biotransformation. To determine if CD-induced changes in hepatic [14C]CD accumulation were coincident with altered cell composition, we examined the effects of CD on hepatic protein and lipid content, on fatty acid profiles of liver and kidney, and on the ultrastructure of hepatocytes. SDS-polyacrylamide gel electrophoresis detected an apparent CD dose-related increase in a microsomal protein with a molecular weight of about 23 kDa. Total liver or kidney lipid contents were not altered by CD but relative amounts of several hepatic fatty acids were changed. CD caused marked hepatic mitochondrial swelling, increased amounts of endoplasmic reticulum, apparently increased numbers of peroxisome-like structures, and decreased numbers of lipid droplets in cytoplasm of hepatocytes. Numbers of lipid droplets were not decreased in perisinusoidal fat storage cells. In addition, the numbers of cytoplasmic lipoprotein vesicles were apparently increased in some hepatocytes. Overall these changes indicated an increased hepatocyte secretory activity and suggested that CD changed hepatocellular lipid transport, storage, and metabolism pathways.

Cochlear nerve activity after intense sound exposure in neonatal chicks

1. Single-neuron behavior in the cochlear nerve of neonatal (3-day-old) chicks was examined after exposure to a 120-dB SPL pure tone (0.9 kHz) for 48 h. Exposed animals were tested after 0 days or 12 days of recovery. Nonexposed chicks, age-matched to the exposed animals, formed two control groups. 2. Spectral response plots were obtained from each cell. These plots described the neuron discharge rates in response to 1,767 tone burst stimuli, each with a unique frequency-intensity combination. The tone bursts were presented at frequencies between 0.1 and 4.5 kHz and for intensities between 0 and 100 dB SPL. From these plots the characteristic frequency (CF), CF threshold, and sharpness of tuning (Q10 dB) were derived for each cell. Frequency response-area functions at selected stimulus levels and rate-intensity functions at the CF were also constructed from the spectral response plots. In addition, spontaneous activity was determined. Data were obtained from 903 cells. 3. Neuron activity in the control cells revealed no differences between CF thresholds, Q10 dB, or spontaneous activity in the two age groups. However, age differences at all frequencies were noted in the rate-intensity functions. 4. A frequency-dependent loss in CF threshold was observed in the 0-day recovered cells. The threshold shift (relative to age-matched control cells) was 55-65 dB between 0.8 and 1.5 kHz, but only 10-15 dB between 0.1-0.4 kHz and 2.5-3.5 kHz. The exposed cells showed no loss in frequency selectivity (Q10 dB) at < 0.5 kHz, whereas above this frequency an increasing deterioration in tuning was noted. Spontaneous activity in the 0-day cells was suppressed across the entire range of CFs. The rate-intensity function of exposed cells had a steeper growth rate than that of control cells. 5. At 12 days of recovery, CF threshold, Q10 dB, and spontaneous activity all recovered to the levels exhibited by age-matched control cells. However, the rate-intensity function for cells with CFs between 0.8 and 1.0 kHz showed abnormal growth and higher discharge rates at saturation than the control cells. Outside of this frequency range the rate-intensity functions of control and exposed cells were similar to each other. 6. Recovery of function in the sound-damaged chick ear is accompanied by almost complete repair of the basilar papilla. The tectorial membrane, however, retains a major defect and only the lower layer of this membrane regenerates. An important observation in this presentation was the abnormal rate-intensity functions (in the 12-day recovered cells) reported for frequencies served by that region of the sensory epithelium where the tectorial membrane defect was found. This observation may be related to sustained structural damage to the short hair cell region of the papilla and/or alterations in the efferent control of papilla function mediated by the short hair cells.

Gentamicin inhibits carrier-mediated dipeptide transport in kidney

The effect of gentamicin on transport of pyroglutamylhistidine (pGlu-His) was examined in rabbit renal brush-border membrane vesicles (BBMV). Gentamicin, an aminoglycoside antibiotic, is limited in its usage because of nephrotoxicity characterized in part by transport defects in the proximal tubule. Since there is no information regarding the effects of gentamicin on renal peptide carriers, uptake of [3H]pGlu-His was measured in BBMV following either in vivo or in vitro exposure to the antibiotic. One hour after in vivo administration, the maximal rate (Vmax) for pGlu-His transport was significantly reduced in isolated membrane vesicles washed free of the drug, but the apparent Michaelis constant (Km) was unaltered. Coincubation of membranes with gentamicin during measurements of pGlu-His uptake had a similar effect, causing a significant decrease in the Vmax but not the Km of transport. The addition of 5 mM magnesium to the uptake medium prevented the in vitro but not the in vivo effect. The data indicate that high doses of gentamicin inhibit the capacity but not the affinity of dipeptide transport in the kidney, prior to morphological changes which typify acute tubular necrosis. The in vitro effect is rapid and involves a direct action of gentamicin on the brush-border membrane. The in vivo experiments show that toxicity may be prolonged and remains following removal of the drug from the renal brush border.

Nephrotic syndrome and acute renal failure associated with hepatitis A virus infection

Acute renal failure has been documented in association with hepatitis A virus (HAV) infection. This report describes a temporal relationship between HAV infection and immune complex mesangial proliferative glomerulonephritis associated with nephrotic syndrome. Animal experimental data have already shown that this is indeed a histological lesion associated with HAV infection. This case report is the first English documentation associating HAV infection with immune complex mesangial proliferative glomerulonephritis.

Activation of proximal tubular Na(+)-H+ exchange by angiotensin II

Stimulation of Na(+)-H+ exchange by angiotensin II (ANG II) was characterized in renal proximal tubular cells. Rabbit proximal nephron segments were incubated in the presence or absence of ANG II (5 x 10(-10) M), after which brush-border membrane vesicles (BBMV) were isolated and assayed for Na(+)-H+ antiporter activity using the acridine orange technique. Both the affinity (for sodium) and capacity of the carrier were elevated significantly (P less than 0.05) within 15 min of incubation with ANG II. To determine whether the stimulation of transport capacity involved a change in Na(+)-H+ antiporter density in the luminal membrane, binding of tritiated 5-(N-methyl-N-isobutyl)amiloride ([3H]MIA) was measured in BBMV derived from control and ANG II-treated nephron segments, following maximal stimulation. This demonstrated a significant (P less than 0.05) increase in the maximal specific binding (Bmax) of [3H]MIA binding in the ANG II-treated group compared with control, of a magnitude sufficient to account for the observed change in maximal velocity (Vmax). The data indicate that the Vmax effect is caused by an apparent increase in the number (density) of active Na(+)-H+ carriers present in the luminal membrane. Finally, to test the possibility that the observed kinetic change involves an exocytic mechanism, the effect of colchicine on ANG II-stimulated antiporter activity was examined. The increase in Vmax due to ANG II was blocked by the addition of 0.5 mM colchicine to the incubation medium, whereas colchicine alone had no significant effect on the Vmax of Na(+)-H+ kinetics.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hypertonic peritoneal dialysis solutions on neutrophil superoxide production

Superoxide produced by neutrophils plays an important role in the killing of bacterial pathogens. The effects of glucose-containing peritoneal dialysis solutions on superoxide production by canine and human neutrophils were studied. A significant decrement in superoxide generation was noted with the 2.27% and 3.86% glucose solutions. The results suggest that hypertonic peritoneal dialysis solutions curtail neutrophil superoxide generation.

Scanning tunneling microscopy of planar biomembranes

We combined planar membrane monolayer techniques with scanning tunneling microscopy (STM) to measure the thickness of metal-coated purple membrane (PM) isolated from Halobacterium halobium. Although the metal coating precluded obtaining high-resolution lateral information, it facilitated obtaining high-resolution vertical information. For example, the apparent mean thickness of planar PM and variations in thickness of enzyme-treated PM could be detected and quantified at sub-nanometer resolution.

Long-term neurologic outcome in psychogenic water drinkers with severe symptomatic hyponatremia: the effect of rapid correction

PURPOSE

The purpose of our study was to ascertain the safety of rapidly correcting acute symptomatic hyponatremia in psychogenic water drinkers, particularly in regard to any delayed adverse neurologic sequelae.

PATIENTS AND METHODS

We reviewed the medical records of all known psychogenic water drinkers (34) in our hospital from 1977 to 1989. Using seizure as a marker of severity, we identified 13 patients having a total of 27 episodes associated with severe hyponatremia. We evaluated the charts of those patients in detail to assess the mode of treatment, rate of correction, and long-term neurologic outcome. None of the patients experienced respiratory arrest before treatment, which was initiated within 2 hours of seizure.

RESULTS

For all 27 episodes, the initial serum sodium level (mean +/- SE) was 110.9 +/- 1.2 mmol/L, and the rate of correction (mean +/- SE) was 1.65 +/- 0.2 mmol/L/hour. All but one episode were corrected "rapidly" (initial correction rate of 0.7 or more mmol/L/hour) to 120 to 130 mmol/L within 12 hours. The absolute change in the serum sodium level was 15.1 +/- 1.2 mmol/L in 12 hours, 21.6 +/- 1.4 mmol/L in 24 hours, and 25.9 +/- 1.4 mmol/L in 48 hours. In no instance did therapy induce hypernatremia. All patients recovered immediately after treatment. There was no clinical or radiologic evidence of adverse neurologic sequelae immediately after treatment or after 6 years of follow-up.

CONCLUSION

In this series of male psychogenic water drinkers, early "rapid" correction of acute symptomatic hyponatremia by raising the serum sodium level 15 mmol/L in 12 hours while maintaining an absolute change in the serum sodium level of 26 mmol/L within 48 hours produced no long-term neurologic sequelae.

Measuring changes in membrane thickness by scanning tunneling microscopy

We investigated the feasibility of using the scanning tunneling microscope (STM) as a morphometric tool to measure the thickness of biomembranes. Planar monolayers of oriented purple membrane (PM) were prepared, nitrogen-dried or freeze-etched, and coated with metal. PM thickness was quantified by STM and transmission electron microscopy. STM calibration and the effect of contamination-mediated surface deformation on measurements of PM thickness were evaluated. The thickness of PM attached to mica and glass and the effect of papain on PM thickness were also examined. The apparent thickness of enzymatically modified PM increased after papain treatment. The mean thickness of both nitrogen-dried PM on mica and freeze-etched PM on glass was 4.6 nm. After papain treatment PM thickness on mica increased to 4.8 nm and on glass to 5.4 nm. These results demonstrate that STM analysis of metal-coated planar membrane monolayers can be used to measure changes in average membrane thickness at sub-nanometer resolution.

Monolayer freeze-fracture and scanning tunneling microscopy

This article reviews research on planar monolayer methods, application of the methods to analyses of transmembrane signaling, and the combination of these methods with scanning tunneling microscopy (STM). Past research has involved the development of monolayer freeze-fracture methods. These include monolayer freeze-fracture autoradiography (MONOFARG), an electron microscopic cytochemical method to analyze in-plane distributions of radioisotopes, and double-labeled membrane splitting (DBLAMS) and single-membrane monolayer splitting (SMMS), methods to analyze transmembrane distributions of native and radiolabeled proteins and lipids. Present research has focussed on using these methods to investigate mechanisms of transmembrane signaling mediated by protein kinase C (PKC), including the transbilayer distribution of the tumor promoter TPA, a lipophilic activator of PKC, and the transbilayer distribution of peripheral membrane proteins phosphorylated by PKC. Future work will involve the combination of planar sample preparation with STM. The principles and applications of biological STM are briefly reviewed and a low-resolution STM image of a planar purple-membrane monolayer is included. The combination of planar methods and STM can provide the chemical information lacking in STM images enabling microscopists to investigate biochemical phenomena at nanometer resolution.

Transmembrane signaling: tumor promoter distribution

Diacylglycerol plays a critical role in transmembrane signaling by activating protein kinase C (PKC). The tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) mimics that action, and in the human erythrocyte, TPA-activated PKC phosphorylates membrane proteins. Although molecular aspects of this process have been investigated, details of the interaction of TPA with plasma membranes remain elusive. Because TPA is hydrophobic, it has been assumed that it associates with the lipid bilayer. However, there is no direct evidence for its transbilayer distribution. Because knowledge of its location would limit molecular models proposed to explain its mode of action, we have used membrane-splitting techniques, based on freeze-fracture of planar cell monolayers, to quantify transmembrane partitioning of [3H]TPA. Under conditions where PKC-mediated phosphorylation was stimulated by [3H]TPA and where more than 90% of the [3H]TPA was associated with the human red cell plasma membrane, two-thirds of the TPA partitioned with the cytoplasmic leaflet after bilayer splitting. This represents the first direct topographic localization of TPA in a biological membrane and supports the hypothesis that the mechanism of TPA activation requires its association with the cytoplasmic leaflet of the bilayer.

Topography of protein kinase C substrates analyzed by membrane splitting

We have used the methods of planar cell and membrane monolayer formation and monolayer splitting to study structural details of the transmembrane signaling process mediated by protein kinase C. We analyzed human red cell membrane proteins phosphorylated by phorbol ester activation of protein kinase C. Planar single membrane preparations, extraction procedures, and gel electrophoresis coupled with silver staining and autoradiography confirmed that two bands in the 100 kDa region, and bands 4.1, and 4.9, were peripheral and phosphorylated by treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA). TPA also stimulated minor incorporation of [32 P]Pi into most integral membrane proteins, including band 3, glycophorin A, the band 4.5 region (glucose transporter) and band 7. Planar cell and membrane-splitting methods revealed that neither integral nor peripheral phosphorylated polypeptides were cleaved by freeze fracture, that all phosphorylated peripheral proteins partitioned intact with the cytoplasmic side of the membrane, and that the percentages of [32P]Pi-labeled peripheral proteins were the same in split membrane cytoplasmic leaflets as in intact membranes. As a unique approach to examining protein topographies membrane splitting provides strong evidence that the major phosphorylated products of the polyphosphatidylinositide pathway are topographically associated with the cytoplasmic leaflet of the human erythrocyte plasma membrane. We further conclude that TPA-induced phosphorylation of red cell peripheral proteins does not significantly alter their transbilayer partitioning patterns after membrane splitting.

Malignant mesothelioma with occupational and environmental asbestos exposure in an Illinois community hospital

Clinical, radiologic, pathologic, and epidemiologic data on 32 patients with diffuse malignant mesothelioma (DMM) diagnosed between 1968 and 1984 at a 427-bed community hospital in Berwyn, Ill, were reviewed. Independent pathologists' review of light microscopy, supported by electron microscopy, immunoperoxidase staining, or autopsy, confirmed 29 pleural and three peritoneal DMMs. Clinical and radiologic characteristics were similar to those in published case series. Median age at diagnosis was 67 years, and median survival after diagnosis, seven months. Fourteen patients were women. Exposure histories were obtained through 22 interviews supplemented by hospital charts and death certificates. Thirty patients (94%) had a history of asbestos exposure through work (15 [47%]) and/or residence near an asbestos facility (27 [84%]). Medical records and death certificates underreported asbestos exposure and DMM.

Correlation of mammalian cell killing by heat shock to intramembranous particle aggregation and lateral phase separation using fluorescence-activated cell sorting

Heat shock induces a dose-dependent increase in the fraction of Chinese hamster ovary cells that stain the fluorescent membrane probe N-epsilon-dansyl-L-lysine (DL). Dansyl lysine has previously been shown to select for cholesterol-free membrane domains in phospholipid liposomes. We found that the fraction of cells excluding DL could be closely correlated to cell survival as assayed by 37 degrees C incubation following heat treatment. Fluorescence-activated cell sorting indicated that essentially all of the DL-staining cells were nonviable. Freeze fracture electron microscopy of sorted cells showed that all the cells that stained with DL also had highly suggested intramembranous particle (IMP) aggregation while DL-excluding cells did not. Furthermore, IMP aggregation was shown to occur immediately after heat shock and to precede DL staining. Treatment with other membrane-active agents such as ethanol, amphotericin B, filipin, procaine, and lidocaine (i) induced DL staining that was closely correlated to survival, (ii) induced dramatic cytotoxic sensitization when combined with heat, and (iii) induced aggregated IMPs at relevant cytotoxic concentrations. Several nonmembrane-active agents were examined; none induced DL staining, dramatic cytotoxic sensitization, or IMP aggregation. These results raise the possibility that heat shock inactivates mammalian cells primarily via nonspecific aggregation and denaturation of membrane proteins resulting in a lateral phase separation of membrane components, including the generation of phospholipid domains.

Effect of membrane splitting on transmembrane polypeptides

We investigated the effect of membrane splitting on the primary structure of human erythrocyte membrane polypeptides. Monolayers of intact, chemically unmodified cells were freeze-fractured and examined by one-dimensional SDS PAGE. Silver-stained gels revealed all major polypeptides that stain with Coomassie Blue as well as all bands that stain with periodic acid Schiff's reagent. Both nonglycosylated and glycosylated membrane polypeptides could be detected at concentrations of only a few nanograms per band. Membrane splitting had no effect on the position or number of bands. Monolayers of intact erythrocytes that had been enzymatically radioiodinated with lactoperoxidase were examined by electrophoresis, fluorography, and liquid scintillation counting. Radioactivity was quantified before and after monolayer formation and splitting, and at several stages of gel staining, drying, and fluorography. Although overexposed fluorographs revealed several minor radioiodinated bands in addition to band 3 and the glycophorins, no new bands were detected in split membrane samples derived from intact cells. These observations support the conclusion that neither the band 3 anion channel nor the glycophorin sialoglycoproteins are fragmented during freeze-fracturing. Although both band 3 and glycophorin partition to the cytoplasmic side of the membrane, preliminary quantitative observations suggest an enrichment of glycophorin in the split extracellular "half" membrane. We conclude that the process of membrane splitting by planar monolayer freeze-fracture does not cleave the covalent polypeptide backbone of any erythrocyte membrane protein, peripheral or integral.

Bactericidal activity of ascitic fluid in patients with nephrotic syndrome

Patients with nephrotic syndrome are unusually susceptible to infections, including primary peritonitis. In this study, we have evaluated nine adult patients with nephrotic syndrome and ascites for ascitic fluid bactericidal activity, complement and immunoglobulin concentrations. Eight of nine patients had diminished ascitic fluid bactericidal activity while twelve control peritoneal fluids had normal bactericidal activity. Complement (C3 and C4) and immunoglobulin (IgG and IgM) concentrations were significantly lower in nephrotic syndrome ascitic fluid than peritoneal fluid from normal subjects. These findings may explain the high occurrence rate of primary peritonitis in nephrotic patients with ascites.

Two-dimensional electrophoretic analysis of human erythrocyte cylindrin

Cylindrin, a macromolecule isolated from the human erythrocyte, and the band 7 proteins of the erythrocyte membrane were analyzed by one- and two-dimensional electrophoresis. Cylindrin was recovered from both the cytosol and cell membranes of hypotonically lysed erythrocytes, and its identity was confirmed by electrophoresis and transmission electron microscopy. Cylindrin from either source produced eight bands on one-dimensional SDS gels, and seventeen spots on two-dimensional gels, revealing a more complex composition than previously reported. It is unlikely that this complexity was due to proteolysis, since preparations of cylindrin with various protease inhibitors gave the same electrophoretic patterns. Mixing experiments showed that the polypeptide subunits of the cylindrin complex are distinct from the band 7 proteins of the erythrocyte membrane. This finding failed to support a role for the cylindrin macromolecule in the permeability disorders of the erythrocyte membrane associated with a missing band 7 protein.

Hypertension in pregnancy

Blood pressure; extracellular fluid volume; renal plasma flow; glomerular filtration rate; plasma concentrations of renin, angiotensin, aldosterone, desoxycorticosterone, and prostaglandins; responses to infused angiotensin; and many other factors are altered during normal and hypertensive gestation. The diagnosis of the exact disease process responsible for hypertension in pregnancy in an individual patient is extremely difficult if based solely on clinical criteria. The American College of Obstetricians and Gynecologists has suggested the following clinical classifications: (1) preeclampsia-eclampsia, (2) chronic hypertension of whatever cause, (3) chronic hypertension with superimposed preeclampsia, and (4) late or transient hypertension. The three broad categories of renal disease responsible for these clinical syndromes are: (1) preeclampsia-eclampsia, (2) hypertensive changes, and (3) various primary renal diseases. Controversy abounds regarding the aggressiveness of therapy in this syndrome. We prefer a middle-of-the-road approach, bringing blood pressure down to the range of 95 to 100 mm Hg. Hydralazine and Aldomet are the usual drugs of choice. Any intervening nervous system hyperexcitability suggests impending eclampsia and should be immediately treated with magnesium sulfate. The long-term prognosis for the mother with pure preeclampsia appears to be excellent. Most infants born of hypertensive gestations are small for date, with a prognosis that is also affected by the underlying disease of the mother.

Monolayer freeze-fracture autoradiography: origins and directions

Monolayer freeze-fracture autoradiography (MONOFARG) is a product of two earlier methods: freeze-fracture autoradiography (FARG) and cell monolayer freeze-fracture. MONOFARG incorporates many of the basic principles and cytochemical goals of FARG while exploiting the technical advantages of monolayer freeze-fracturing. The latter method offers the opportunity to process freeze-dried 'half' membranes at room temperature. Although the feasibility of MONOFARG has been shown for qualitative analyses of split membranes, it's quantitative feasibility for transmembrane and in-plane analyses has just begun to be documented. An example of one aspect of that documentation is included in this report. The distribution of 125I-FITC-Concanavalin-A in the plane of split plasma membranes, human erythrocyte extracellular fracture faces, was examined and found to be homogeneous. The relevance of this finding to recently described double labelled membrane splitting experiments is discussed. The future of MONOFARG appears promising, especially in the application of the technique to biologically significant questions.

Monolayer freeze-fracture autoradiography: quantitative analysis of the transmembrane distribution of radioiodinated concanavalin A

The technique of monolayer freeze-fracture autoradiography (MONOFARG) has been developed and the principles, quantitation, and application of the method are described. Cell monolayers attached to polylysine-treated glass were freeze-fractured, shadowed, and coated with dry, Parlodion-supported Ilford L4 photographic emulsion at room temperature. Quantitative aspects of MONOFARG were examined using radioiodinated test systems. Background was routinely less than 2.5 X 10(-4) grains/microns 2/day, the highest overall efficiency was between 25% and 45%, and grain density and efficiency were dependent on radiation dose for iodine-125 and D-19 development. Corrected grain densities were linearly proportional to iodine-125 concentration. The method was applied to an examination of the transmembrane distribution of radioiodinated and fluoresceinated concanavalin A (125I-FITC-Con-A). Human erythrocytes were labeled, column-purified, freeze-dried or freeze-fractured, autoradiographed, and examined by electron microscopy. The number of silver grains per square micrometer of unsplit single membrane was essentially identical to that of split extracellular membrane "halves." These data demonstrate that 125I-FITC-Con-A partitions exclusively with the extracellular "half" of the membrane upon freeze-fracturing and can be used as a quantitative marker for the fraction of extracellular split membrane "halves." This method should be able to provide new information about certain transmembrane properties of biological membrane molecules and probes, as well as about the process of freeze-fracture per se.

In vitro activity of N-formimidoyl thienamycin and other beta-lactam antibiotics against methicillin-resistant Staphylococcus aureus

Of 43 isolates of methicillin-resistant Staphylococcus aureus, 90% were inhibited by 8 micrograms or less of N-formimidoyl thienamycin per ml by the agar-dilution technique. Cefamandole, cefotaxime, cefoperazone, moxalactam, and cefsulodin showed relatively poor activity. Vancomycin was the most active compound by weight, inhibiting 93% of strains at 1 microgram/ml.

Spectroscopic assays for measuring quantities of erythrocyte membrane "halves"

The quantities of outer and inner"halves" produced by freeze-fracturing human erythrocyte membranes have been measured by visible and fluorescence spectroscopy. Assays have been developed that are based on the use of two membrane surface markers: hemoglobin (Hb), a native marker for the cytoplasmic side of the membrane, and fluoresceinated concanavalin A (FITC-Con-A), a marker for the extracellular side. Hb absorbance is proportional to the fraction of cytoplasmic "half" membranes, and FITC fluorescence is proportional to the fraction of extracellular "halves." A procedure is described for the preparation of surface-labeled, intact erythrocytes suitable for the formation of homogeneous, planar cell monolayers of square-centimeter dimensions on polylysine-treated glass (PL-glass). Cell monolayers were frozen and fractured, and the fractions of absorbance and fluorescence in each of the two split portions determined. The PL-glass portion of membrane contained a substantially higher ratio of fluorescence to absorbance than unsplit controls, and its paired portion, a complementary lower ratio, demonstrating that the PL-glass portion was significantly enriched in extracellular "half" membrane. Experiments investigating split membrane recovery show that the double labeled membrane splitting technique is well suited to analysis of the transmembrane distribution of membrane lipids and polypeptides using methods that do not require quantitation by electron microscopy.

Contaminated breast milk: A source of Klebsiella bacteremia in a newborn intensive care unit

Five patients in a newborn intensive care unit (NICU) developed primary bacteremia due to Klebsiella during a 12-day period, May 2 through June 2, 1979, after feeding for 24-96 hr with contaminated breast milk. All patients had been fed via nasoduodenal tube with milk obtained from a single donor. The donor milk collected via electric suction pump was positive by gram stain for gram-negative rods and by culture for Klebsiella pneumoniae. A culture of hand-expressed milk was negative for gram-negative rods. The breast-pump tubing and safety trap were grossly contaminated with K. pneumoniae. Institution of proper sterilization to the pump equipment controlled the outbreak. This outbreak is the first documentation of nosocomial bacteremia as a major infectious complication of feedings of premature infants with contaminated breast milk.

Pseudomonas cepacia: implications and control of epidemic nosocomial colonization

In the 19-month period January 1979-July 1980, 56 patients became colonized or infected with Pseudomonas cepacia. Three groups of patients were identified. In group I, six otolaryngology patients became colonized when contaminated aqueous cocaine was used as a topical anesthetic. In group II, 24 patients became colonized from contaminated lidocaine normal-saline solutions that had been drawn into syringes in advance (setups) and used during bronchoscopy in the internal medicine department. In group III, the source of colonization of infection for 26 patients with sputum, wound, blood, or urine cultures positive for P. cepacia was not determined. However, contaminated aqueous cocaine, found in the pharmacy, had been given to several of these patients. Since most patients were colonized rather than infected with P. cepacia, there was an apparent disparity in the case count based on data obtained from microbiology records and data obtained from ongoing surveillance of nosocomial infections. Several patients who were merely colonized with P. cepacia were inappropriately treated with chloramphenicol. Successful control measures included sterilizing cocaine solutions in the otolaryngology department and in the pharmacy and eliminating contaminated set-ups in the internal medicine department.

Comparative studies of keratins isolated from psoriasis and atopic dermatitis

Keratin proteins were extracted from scales of normal skin, clinically active psoriatic lesions, and atopic dermatitis. Filaments prepared by in vitro assembly upon dialysis of the proteins against a low ionic strength buffer were comparatively characterized by electron microscopy, SDS gel electrophoresis, and amino acid analysis. Filaments formed using keratin obtained from the skin of normal individuals were thin and wavy, whereas those formed using keratin isolated from the scales of psoriatic patients were straight and showed a tendency to assemble side by side. Filaments of atopic dermatitis were indistinguishable from those of normal individuals. Filaments of both normal and atopic dermatitis contained the protein band of 67,000 daltons, which was absent in filaments of psoriasis. In contrast, 2 protein bands of 54,000 and 57,000 daltons were only detectable in psoriasis. Amino acid analysis of these filaments further demonstrated that filaments of psoriasis differ from those of normal individuals in that they have a glycine content that is 60% of normal.

Calcific stenosis of the porcine heterograft

We have encountered two cases of late calcification of the porcine heterograft. A patient in chronic renal failure died of sepsis and endocarditis fifteen months after replacement of the mitral and tricuspid valves. At postmortem examination, both heterograft valves exhibited severe calcification and thrombosis. A second patient with rheumatic heart disease and sickle cell disease underwent mitral valve replacement for severe regurgitation. Thirty months later, cardiac catheterization revealed prosthetic valve stenosis. The valve was replaced successfully, and the excised heterograft exhibited severe calcification with restriction of leaflet motion. Although calcification of the porcine heterograft is known to occur in patients with infection or disorders of calcium metabolism, dysfunction of the heterograft is rare in our experience.

Molecular orientation of bacteriorhodopsin within the purple membrane of Halobacterium halobium

The direction of orientation of the protein bacteriorhodopsin within the purple membrane of Halobacterium halobium has been determined by selected-area electron diffraction of membranes preferentially oriented by adsorption to polylysine. Purple membrane is known to adsorb preferentially to polylysine by its cytoplasmic surface at neutral pH and by its extracellular surface at low pH. To maintain the adsorbed membranes in a well-ordered state in the electron microscope, an improved technique of preparing frozen specimens was developed. Large areas of frozen-hydrated specimens, devoid of bulk water, were obtainable after the specimen was passed through a Ca stearate film at an air-water interface. High-resolution microscopy was used to relate the orientation observed in the electron diffraction patterns to the orientation of the projected structure that is obtained from images. We have found that the three-dimensional structure determined by Henderson and and Unwin [Henderson, R. & Unwin, P.N.T. (1975) Nature 257, 28--32] is oriented with the cytoplasmic side uppermost--i.e., the helices fan outward on the cytoplasmic side of the membrane.

Oriented adsorption of purple membrane to cationic surfaces

We have investigated the orientation of isolated fragments of Halobacterium halobium purple membrane (PM) adsorbed to poly-L-lysine-treated glass (PL-glass), by quanitative electron microscopy. Three lines of evidence support the conclusion that the cytoplasmic side of the membrane is preferentially absorbed. First, monolayer freeze-fracture reveals nonrandom orientation; more fracture faces (89%) are particulate than smooth. Second, the amount of each membrane surface present can be assayed using polycationic ferritin; 90% of all adsorbed membrane fragments are labeled. Third, it is possible to distinguish two surfaces, "cracked" (the extracellular surface) and "pitted" (the cytoplasmic surface) , in slowly air-dried, platinum-carbon-shadowed membranes. When applied under standard conditions, more than 80% appear cracked. Selection for the cytoplasmic by the cationic substrate suggests that the isolated PM, buffered at pH 7.4 and in the light, has a higher negative charge on its cytoplasmic surface than on its extracellular surface. Nevertheless, cationic ferritin (CF) preferentially adsorbs to the extracellular surface. Orientation provides a striking example of biomembrane surface asymmetry as well as the means to examine the chemical reactivity and physical properties of surfaces of a purified, nonvesicular membrane fragment.

Intramembranous particle distribution in human erythrocytes: effects of lysis, glutaraldehyde, and poly-L-lysine

Freeze-fracture combined with quantitative electron microscopy of the intact human erythrocyte (RBC) and ghost revealed significant differences in their intramembranous particle coefficients. External (E) fracture-faces of unfixed ghost membranes were found to contain 40% fewer particles than those of intact unfixed RBC. The particle distribution of the intact RBC membrane depended on the use of glutaraldehyde fixation and glycerol cryoprotection. Whereas glutaraldehyde- and glycerol-treated cells disclosed 70% fewer E-face particles than did intact unfixed cells, poly-L-lysine-treated, intact, unfixed RBC showed no such differences. Treatment with a combination of poly-L-lysine and glutaraldehyde, however, increased the amount of E-face particles while reducing those of the protoplasmic (P) face. The poly-L-lysine effect varied with its concentration and was unaffected by previous application of neuraminidase. Nor did the lectin phytohemagglutinin induce particle rearrangement in intact cells. Our data demonstrate that the processes of glutaraldehyde fixation and glycerol cryoprotection modify the RBC membrane by decreasing the number of E-face particles present. In addition, the combination of poly-L-lysine and glutaraldehyde alters the affinity of some particles for one half of the membrane, suggesting that in freeze-fractured RBC, chemical bonds formed at the extracellular surface of the membrane can influence particle partitioning.

Nephrotic proteinuria with pre-eclampsia

During a retrospective study of 100 patients who underwent renal biopsy because of pregnancy complicated by hypertension, we found 19 patients whom proteinuria exceeded 5.0 Gm. per 24 hours and an additional eight patients in whom excretion ranged between 3.5 and 5 Gm. per day. Of these 27 patients, 23 had the kidney lesion of pre-eclampsia, and three of them had superimposed hypertensive changes in the vasculature. The remaining four had other renal diseases. We located and re-examined 10 of the 23 pre-eclamptic women, 12 to 104 (mean, 36) months after delivery. Serum creatinine levels were normal in all but one, who was discovered to have polycystic kidney disease. During the same time period, we located the records of six women who had heavy proteinuria during gestation but were normotensive. Thus, at our institution, pre-eclampsia is the most common cause of the nephrotic syndrome in pregnancy. The frequency of nephrotic proteinuria in pre-eclampsia appears higher than previously suspected, but, despite this fact, recovery was complete in most instances.

Freeze-fractured purple membrane particles: protein content

Optical diffraction and image reconstruction can be used to correlate the electron microscope image of the biological membrane with its electron density projection. Such correlation shows that a single purple membrane particle contains 9 to 12 protein molecules--63 to 84 transmembrane alpha helices--a complexity two to ten times greater than that previously suggested for membrane particles.