Quantitative proteomics and single-nucleus transcriptomics of the sinus node elucidates the foundation of cardiac pacemaking

The sinus node is a collection of highly specialised cells constituting the heart’s pacemaker. The molecular underpinnings of its pacemaking abilities are debated. Using high-resolution mass spectrometry, we here quantify >7,000 proteins from sinus node and neighbouring atrial muscle. Abundances of 575 proteins differ between the two tissues. By performing single-nucleus RNA sequencing of sinus node biopsies, we attribute measured protein abundances to specific cell types. The data reveal significant differences in ion channels responsible for the membrane clock, but not in Ca²⁺ clock proteins, suggesting that the membrane clock underpins pacemaking. Consistently, incorporation of ion channel expression differences into a biophysically-detailed atrial action potential model result in pacemaking and a sinus node-like action potential. Combining our quantitative proteomics data with computational modeling, we estimate ion channel copy numbers for sinus node myocytes. Our findings provide detailed insights into the unique molecular make-up of the cardiac pacemaker.

The sinus node generates rhythmic heartbeat but the molecular basis of pacemaking is still under debate. Here, the authors combine quantitative proteomics and single-nucleus transcriptomics to characterize the molecular composition of the sinus node and provide insights into the underpinnings of pacemaking.

Integrating the Epigenome to Identify Drivers of Hepatocellular Carcinoma

Disruption of epigenetic mechanisms has been intimately linked to the etiology of human cancer. Understanding how these epigenetic mechanisms (including DNA methylation [5mC], hydroxymethylation [5hmC], and histone post-translational modifications) work in concert to drive cancer initiation and progression remains unknown. Hepatocellular carcinoma (HCC) is increasing in frequency in Western countries but lacks efficacious treatments. The epigenome of HCC remains understudied. To better understand the epigenetic underpinnings of HCC, we performed a genome-wide assessment of 5mC, 5hmC, four histone modifications linked to promoter/enhancer function (H3K4me1, H3K27ac, H3K4me3, and H3K27me3), and transcription across normal, cirrhotic, and HCC liver tissue. Implementation of bioinformatic strategies integrated these epigenetic marks with each other and with transcription to provide a comprehensive epigenetic profile of how and when the liver epigenome is perturbed during progression to HCC. Our data demonstrate significant deregulation of epigenetic regulators combined with disruptions in the epigenome hallmarked by profound loss of 5hmC, locus-specific gains in 5mC and 5hmC, and markedly altered histone modification profiles, particularly remodeling of enhancers. Data integration demonstrates that these marks collaborate to influence transcription (e.g., hyper-5hmC in HCC-gained active enhancers is linked to elevated expression) of genes regulating HCC proliferation. Two such putative epigenetic driver loci identified through our integrative approach, COMT and FMO3, increase apoptosis and decrease cell viability in liver-derived cancer cell lines when ectopically re-expressed. Conclusion: Altogether, integration of multiple epigenetic parameters is a powerful tool for identifying epigenetically regulated drivers of HCC and elucidating how epigenome deregulation contributes to liver disease and HCC.

Myeloid translocation genes differentially regulate colorectal cancer programs

Myeloid translocation genes (MTGs), originally identified as chromosomal translocations in acute myelogenous leukemia, are transcriptional corepressors that regulate hematopoietic stem cell programs. Analysis of The Cancer Genome Atlas (TCGA) database revealed that MTGs were mutated in epithelial malignancy and suggested that loss of function might promote tumorigenesis. Genetic deletion of MTGR1 and MTG16 in the mouse has revealed unexpected and unique roles within the intestinal epithelium. Mtgr1^−/− mice have progressive depletion of all intestinal secretory cells, and Mtg16^−/− mice have a decrease in goblet cells. Furthermore, both Mtgr1^−/− and Mtg16^−/− mice have increased intestinal epithelial cell proliferation. We thus hypothesized that loss of MTGR1 or MTG16 would modify Apc^1638/+-dependent intestinal tumorigenesis. Mtgr1^−/− mice, but not Mtg16^−/− mice, had a 10-fold increase in tumor multiplicity. This was associated with more advanced dysplasia, including progression to invasive adenocarcinoma, and augmented intratumoral proliferation. Analysis of ChIP-seq datasets for MTGR1 and MTG16 targets indicated that MTGR1 can regulate Wnt and Notch signaling. In support of this, immunohistochemistry and gene expression analysis revealed that both Wnt and Notch signaling pathways were hyperactive in Mtgr1^−/− tumors. Furthermore, in human colorectal cancer (CRC) samples MTGR1 was downregulated at both the transcript and protein level. Overall our data indicates that MTGR1 has a context dependent effect on intestinal tumorigenesis.

Canine subcutaneous mast cell tumors: cellular proliferation and KIT expression as prognostic indices

Molecular assays are widely used to prognosticate canine cutaneous mast cell tumors (MCT). There is limited information about these prognostic assays used on MCT that arise in the subcutis. The aims of this study were to evaluate the utility of KIT immunohistochemical labeling pattern, c-KIT mutational status (presence of internal tandem duplications in exon 11), and proliferation markers--including mitotic index, Ki67, and argyrophilic nucleolar organizing regions (AgNOR)--as independent prognostic markers for local recurrence and/or metastasis in canine subcutaneous MCT. A case-control design was used to analyze 60 subcutaneous MCT from 60 dogs, consisting of 24 dogs with subsequent local recurrence and 12 dogs with metastasis, as compared to dogs matched by breed, age, and sex with subcutaneous MCT that did not experience these events. Mitotic index, Ki67, the combination of Ki67 and AgNOR, and KIT cellular localization pattern were significantly associated with local recurrence and metastasis, thereby demonstrating their prognostic value for subcutaneous MCT. No internal tandem duplication mutations were detected in exon 11 of c-KIT in any tumors. Because c-KIT mutations have been demonstrated in only 20 to 30% of cutaneous MCT and primarily in tumors of higher grade, the number of subcutaneous MCT analyzed in this study may be insufficient to draw conclusions on the role c-KIT mutations in these tumors.

The LionHeart LVD-2000: a completely implanted left ventricular assist device for chronic circulatory support

Management of patients with end-stage cardiac disease remains a vexing problem. Limitations in medical management and a fixed supply of donor organs for cardiac transplant have a continued impact on this growing population of patients. Mechanical circulatory support has proved very successful as a means of bridging patients to cardiac transplant when all medical options have been exhausted. The development of a chronic system of circulatory support has been underway at the Pennsylvania State University for nearly 30 years. These efforts have been recently merged with the industrial partnership with Arrow International toward the development of the LionHeart LVD-2000 (Arrow International, Reading, PA) completely implanted left ventricular support system. We present an overview of the system, details of implantation, a review of preclinical studies, and a synopsis of the first European implants. Early results have demonstrated the system to be safe, effective, and reliable. Transcutaneous energy transmission and the compliance chamber have been validated.

Viral induction, transmission and apoptosis among cells infected by a Human Intracisternal A-type retrovirus

Sjogren's Syndrome, a systemic autoimmune disease, is characterized by lymphocytic infiltration of the salivary or lacrimal glands, producing xerostomia or xerophthalmia. Although definitive proof of viral etiology has not been established, a cell line containing viral particles termed Human Intracisternal A-type Particles (HIAP) resulted from co-culture with patient lip biopsies. We stimulated these chronically infected cells with phorbol myristate acetate (PMA) in an effort to enhance production of viral particles for further characterization. We report that the virus present in the HIAP cell line can be induced to become lytic when subjected to PMA and that there is a difference in the effects of PMA on H9 and HIAP cell groups, with apparent protection from apoptosis due to PMA being exerted by viral presence. Delayed apoptosis may prolong exposure of the foreign/self complex, thus enhancing an autoimmune response. Polyacrylamide gel electrophoresis (PAGE) revealed the presence of new peptides in pellets of supernatants of PMA-stimulated HIAP cells, with prominent bands at 55 and 43 kDa, and several fainter ones. HIAP infection was transferred by cell-free filtered supernatants from stimulated cells to H9 cells, which became identical to parent HIAP cells by PAGE and fluorescence activated cell sorter.

Reactivity of sera from systemic lupus erythematosus and Sjögren's syndrome patients with peptides derived from human immunodeficiency virus p24 capsid antigen

We have previously demonstrated that about one-third of patients with either Sjögren's syndrome (SS) or systemic lupus erythematosus (SLE) react to human immunodeficiency virus (HIV) p24 core protein antigen without any evidence of exposure to, or infection with, HIV itself. Herein, we further characterize the specificity of this reaction using enzyme-linked immunosorbent assay to peptides representing fragments of p24. Characteristic epitope-specific profiles were seen for SS and SLE patients. SS patients had significantly increased responses to peptides F (p24 amino acids 69 to 86) and H (amino acids 101 to 111) and diminished reactivity to peptides A (amino acids 1 to 16) and P (amino acids 214 to 228). SLE patients had increased reactivity to peptides E (amino acids 61 to 76), H, and P. Utilization of peptide P hyporeactivity as the criterion to select for SS patients results in a screen that is moderately sensitive (64%) and specific (79.3%). Adding hyperreactivity to one other peptide (F or H) as an additional criterion yields an expected decrease in sensitivity (to 41%) while increasing specificity (to 93.1%). All sera-reactive peptides from regions of known structure of HIV p24 were located in the apex of the p24 molecule. Thus, the specificity of the peptide reactivities described here indicates a specific pattern of a nonrandom cross-reactivity between HIV type 1 p24 and autoimmune sera which may be partially syndrome specific. The future focus of our work will be to optimize assays of the peptide as diagnostic tools.

Identification of cryptic peanut agglutinin-reactive sites in human lipoprotein(a)

After treatment of human lipoprotein(a) (Lp(a)) with neuraminidase, formerly cryptic sites became available for binding to peanut agglutinin (PNA) lectin and a Thomsen-Friedenreich antigen (T-antigen)-specific monoclonal antibody. The PNA-reactive sites were localized to the apo(a) moiety of Lp(a) and O-specific carbohydrate side chains. Lp(a) with larger isoforms of apo(a) contained more potential PNA reactivity per molecule of Lp(a) apoB than did smaller isoforms. Very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high density lipoproteins (HDL) did not contain comparable amounts of the cryptic PNA-reactive sites.

Delayed hypersensitivity skin tests and subsequent renal transplant outcome

BACKGROUND

Some studies in the literature have supported, while others have denied, the relationship between results of delayed hypersensitivity skin tests (DHST), renal allograft and patient survival rates. Several factors contribute to the unreliability of these studies. For example, most of these studies were performed in the precyclosporine era, furthermore, other variables which influence renal allografts and patient survival rates were not controlled in those studies.

OBJECTIVE

The purpose of this study was to investigate the relationship between results of DHST performed in the pretransplant period with the subsequent renal transplant outcome in the cyclosporine era.

METHODS

The study included 103 first cadaveric renal transplant recipients. DHST were performed during pretransplant evaluation by intradermal injections of a battery of recall antigens. Based on skin-test results, the patients were assigned to two groups--those with a positive skin test (STP+) and those with a negative (anergic) skin test. These two groups were compared with each other regarding allograft survival, patient survival, and other variables known to influence survival rates.

RESULTS

The mean age, sex and racial distribution, degree of HLA matches between recipients and donors, number of acute rejection episodes, and number of patients with acute tubular necrosis were similar between the two groups. Renal allograft survival rates in the anergic group at 6 months, 1 year, 2 years, and 3 years were 97%, 90%, 84%, and 57%, respectively. The survival rate for renal allografts in the STP+ group for the same time points was 90%, 86%, 80%, and 72%, respectively. Patient survival rates for the anergic group at 6 months, 1 year, 2 years, and 3 years were 95%, 94%, 89%, and 85%, respectively, while those for the STP+ group were 98%, 98%, 98%, and 97% respectively. Differences between the STP+ and anergic groups, with regard to patient and allograft survival rates, were not significant.

CONCLUSION

We conclude that DHST is not helpful in predicting outcome of patient or renal allograft survival rates over a 3-year time period.

Identifying and comparing competencies for social work management: a practice driven approach

The study explicates a competency-based model of contemporary social work management practice and compares this model with frameworks derived from earlier studies. Using a purposive sample of 184 social work managers throughout the country, an exploratory factor analysis yielded twelve sets of competencies required of today's social work manager. A comparison of the present model to earlier management frameworks reveals that substantive changes in the nature, scope, complexity, and priorities assigned to management competencies and skills have transformed the role of the social work manager over the last decade. Implications for social work manager education are reviewed and future research directions are proposed.

Determination of ultratrace levels of lead in infant formula by isotope dilution inductively coupled plasma mass spectrometry

A simple method was developed for the accurate and precise determination of low- and sub-ppb (ng/g) concentrations of lead in infant formula by isotope dilution inductively coupled plasma mass spectrometry using ultrasonic nebulization. After addition of a known amount of 207Pb, samples were microwave digested and the ratio 207Pb/208Pb was measured in the digests. Agreement with certified values for lead in milk powder standard reference materials was good, and isotope dilution analysis using 206Pb yielded identical results for the standard reference materials. Lead concentrations determined for several infant nutritional products were verified by an independent method. Typically, relative standard deviations of < 4% were obtained with this method for lead concentrations above 2 ppb. The recovery of 2 ng of lead from an aqueous standard carried through the microwave digestion was 104 +/- 4%. Infant formula (containing 0.6 ppb lead) to which 0.4 ng of natural-abundance lead had been added, to simulate a formula containing 0.9 ppb lead, was analyzed by isotope dilution, and the result was 96 +/- 18% of the theoretical value. Thus, differences of 0.3 ppb lead could be clearly distinguished, and the detection limit was estimated to be 0.1 ng lead per gram of infant formula. The keys to accuracy for this method are minimizing contamination and accurately determining the concentration of lead in the isotopically enriched standard.

Analysis of apolipoprotein size distribution by electroimmunoblotting from non-denaturing composite gels

An exponential gradient gel with 0-35% acrylamide and 0.5% agarose was developed for electrophoresis of intact lipoproteins with subsequent electroimmunoblotting. The system resolved in a single gel lipoprotein-associated proteins of sizes from 'free' apoproteins to VLDL. Reproducibility between gels was good (coefficient of variation < 8%). Examination of the effect of mild glutaraldehyde fixation on immunodetection showed variable results (lack of effect on apos (a), AII, and AIV; inhibition of apoB; enhancement of apos AI and E). The composite gel system described here will simplify analysis of apolipoprotein distributions in both health and disease and therefore will likely be useful in future clinical applications.

Patterns of shorebird abundance in eastern Moreton Bay, Queensland

An indirect census method was developed to enable the first large-scale censuses of shorebirds in eastern Moreton Bay, Queensland. The method used the number of bar-tailed godwits counted on high-tide roosts, and the proportion of species on associated intertidal feeding areas, to estimate the abundance of all species. Shorebirds tended to be more abundant at the time of the northward migration, while fluctuations in numbers suggested that shorebirds staged in eastern Moreton Bay during both the southward and northward migrations. Census results highlighted the large number of grey-tailed tattlers, eastern curlews and bar-tailed godwits using eastern Moreton Bay, and provided further evidence that Moreton Bay is a site of international significance for shorebirds.

Optimization and characterization of capture ELISA methodology for Lp(a) lipoprotein quantification

In order to better characterize and optimize a typical capture ELISA system for Lp(a) lipoprotein, we have analysed kinetic details of the reaction. Plate coating with polyclonal antibody, recognition of captured analyte with monoclonal antibody, and detection of monoclonal antibody with alkaline phosphatase-labeled antiglobulin were essentially complete after one hour, probably being driven forward by a relative excess of reagent. However, complete capture of the Lp(a) analyte required about 6 h at low input concentrations. Shorter time periods for capture might therefore result in decreased sensitivity and reproducibility. Deviations from linearity in the assay dose response were associated with incomplete capture of Lp(a) and significant depletion of the monoclonal recognition antibody. With the final reaction conditions described, no significant differences in immunochemical reactivity between samples were found by analysis of dose response slopes. Finally, interferences from plasminogen, -20 degrees C storage, anticoagulants, LDL, haemolysis, and bilirubin were minimal.

Characterization of "modified-self"-induced specific antibody hyporesponsiveness to herpes simplex virus

Pretreatment of mice iv with syngeneic spleen cells modified with soluble HSV envelope antigens induced an anti-HSV antibody hyporesponsiveness following challenge with infectious virus. The epitope density on the HSV-modified spleen cells was quantitated using a photon-counting spectrofluorimeter so that observed immunological results could be correlated with the HSV antigen dose on the splenocytes. The degree of anti-HSV antibody hyporesponsiveness was found to be related to the epitope density on the HSV-modified spleen cells, but not the number of modified cells used in the pretreatment over the 16-fold range tested. Anti-HSV antibody hyporesponsiveness was induced if 7, but not 3, days had elapsed between pretreatment and challenge. This antibody hyporesponsiveness could be adoptively transferred with T cells. Only mice that had induced an anti-HSV antibody hyporesponsiveness following pretreatment with HSV-modified splenocytes were able to survive an LD50 challenge with infectious virus.

Human lipoprotein(a) quantified by 'capture' ELISA

Plasma lipoprotein(a), Lp(a), is the most important known genetically controlled independent risk factor for the prediction of early atherosclerosis (AS) and coronary artery disease (CAD) in a significant subpopulation of Caucasians. A sensitive, specific 'capture' enzyme linked immunosorbent assay (ELISA) is reported for the assay of human plasma Lp(a). There is no interference from low density lipoprotein (LDL), plasminogen, or from endogenous lipids, hemoglobin, or bilirubin. An immobilized polyclonal rabbit antibody 'captures' the Lp(a) ligand, and then a monoclonal murine antibody 'recognizes' it. Alkaline phosphatase conjugated rabbit antimouse IgG and para-nitrophenyl phosphate substrate 'detect' and 'indicate' colorimetrically the amount of Lp(a) bound. Quantitation is relative to a commercially available secondary clinical standard. The frequency distribution for a predominantly Caucasian reference population is highly skewed toward the higher concentrations. The median plasma Lp(a) concentration for healthy Caucasians is 80 mg per 1. Relative risk for early myocardial infarction (MI) increases as plasma Lp(a) levels increase above 300 mg per 1. Approximately 20 percent of Caucasians have plasma Lp(a) values above 300 mg per 1. The frequency distributions of plasma Lp(a) in Blacks and Caucasian type II diabetics are different from the healthy Caucasian reference population. The percentiles of Lp(a) values greater than 300 mg per 1 in these latter groups is three times higher. Thorough epidemiologic and clinical studies where groups are segregated by race and ethnic origin are needed for accurate clinical interpretation of plasma Lp(a) results. Only neomycin and niacin are shown to lower plasma Lp(a) levels therapeutically, although anabolic steroid medication causes lower plasma Lp(a) concentrations. Endocrine malfunction also may influence plasma Lp(a) levels.

Divergent efficacy of antibody to tumor necrosis factor-alpha in intravascular and peritonitis models of sepsis

The role of tumor necrosis factor-alpha (TNF alpha) in the lethal consequences of intravascular lipopolysaccharide (LPS) or Escherichia coli sepsis was compared with that in bacterial peritonitis. Intravenous administration of E. coli LPS or E. coli (live or dead) resulted in large transient increases in serum TNF alpha levels, peaking at 90 min at 10,000-30,000 units/ml. In contrast, the serum TNF alpha response following the induction of bacterial peritonitis was substantially less, peaking at 200-500 units/ml. Sterile peritonitis (essentially nonlethal) and bacterial peritonitis (greater than 60% lethal) elevated TNF alpha levels to 1000-2000 units/lavage within the peritoneal cavity 2 h after challenge. Passive immunization with neutralizing goat anti-TNF alpha IgG improved survival from 8% to 75% in rats administered LPS intravenously but was completely ineffective in protecting rats from lethal E. coli peritonitis. Thus significant differences exist in the role TNF alpha plays in systemic intravascular models of sepsis and bacterial peritonitis.

Effect of low zinc intake on absorption and excretion of zinc by infants studied with 70Zn as extrinsic tag

The effect of low dietary intake of zinc was studied in six normal infants with the use of 70Zn as an extrinsic tag. Of the two study formulas, one provided a zinc intake similar to that of customary infant formulas ("high" intake), whereas the other provided a "low" zinc intake. Two zinc absorption studies were performed with each formula (sequence: high-low-low-high). Extrinsically labeled formula was fed for 24 h and excreta were collected for 72 h. Zinc isotope ratios were determined by inductively coupled plasma mass spectrometry (ICP/MS). When zinc intake was high, net zinc absorption was 9.1 +/- 8.7% (mean +/- SD) of intake and net zinc retention was 74 +/- 91 micrograms/(kg.d). True zinc (70Zn) absorption was 16.8 +/- 5.8% of intake and fecal excretion of endogenous zinc was 78 +/- 56 micrograms/(kg.d). When zinc intake was low, net absorption of zinc increased significantly (P less than 0.001) to 26.0 +/- 13.0% of intake, but net retention was not significantly different at 42 +/- 33 micrograms/(kg.d). True absorption of zinc also increased significantly (P less than 0.001) to 41.1 +/- 7.8% of intake, whereas fecal endogenous zinc decreased (P less than 0.05) to 34 +/- 16 micrograms/(kg.d) during low zinc intake. Thus, infants maintain zinc balance in the face of low zinc intake through increased efficiency of absorption and decreased excretion of endogenous zinc.

Efficient electroblotting of human very-low-density lipoproteins and low-density lipoproteins from composite gradient gels to nylon membranes

Rinsing of gradient composite acrylamide/agarose gels with 1% Triton X-100 permits the efficient electrotransfer of very-low-density and low-density lipoproteins from the gels and does not appear to interfere with subsequent capture of the lipoproteins by charged nylon membranes. Overall efficiency of the transfer/capture process can approach 95% and does not appear to be significantly affected by total lipoprotein concentrations up to 5000 mg/dl. Direct immunoquantification of transferred apolipoproteins on the membrane is feasible as well. The nylon membranes used, however, must be pretested to ensure capture efficiency.

Temporal response of lipoprotein lipase-suppressing mediator and tumor necrosis factor in lipopolysaccharide -injected and -infused rats

This study was initiated to compare the temporal response of serum lipoprotein lipase-suppressing mediator (LSM) and tumor necrosis factor (TNF) in lipopolysaccharide (LPS) -infused or -injected rats. Serial blood samples were obtained over a 5-day period from rats implanted with vascular catheters. Control rats infused with saline exhibited no detectable LSM activity during the 5-day observation period. LPS administered either by injection or infusion (6 h or 5 d) resulted in detection of serum LSM and TNF activities during the early period of observation with the LSM temporal response (8 h) outlasting the TNF response (3 h). The LSM response lasted a little longer in LPS-infused rats than it did in injected rats, but in each case LSM activity was not detected in serum samples collected at or after 12 h post-LPS. Neither the duration nor the magnitude of the TNF response differed between LPS-infused vs. -injected rats. Despite similarities in the LSM and TNF pattern in all rats receiving LPS, lethality was greater in LPS-infused animals than it was in LPS-injected rats. The results indicate that differences in lethality between LPS-injected and -infused rats cannot be explained solely by a differential response of serum TNF.

Intrahepatic assembly of very low density lipoproteins: immunologic characterization of apolipoprotein B in lipoproteins and hepatic membrane fractions and its intracellular distribution

Monoclonal antibodies, prepared against rat apoB, were used to examine apoB structure in serum lipoproteins and characterize the forms and localization of apoB in liver membrane fractions and cultured hepatocytes. Of the several antibodies obtained, four, having separate epitopes, were characterized. Western blot analysis showed that three (DB11, F4, and LB14) antibodies recognized both apoBL and apoBS. One antibody (HB41) recognized only apoBL. This antibody showed unusual properties. Competition ELISA assays showed that the epitope recognized by HB41 was more effectively expressed on low density lipoproteins (LDL) compared to very low density lipoproteins (VLDL). In addition, treatment of lipoproteins with detergents and sulfhydryl reducing agents also increased the expression of the HB41 epitope. Since HB41 has been found to inhibit LDL binding to hepatocyte receptors, these data indicate that the HB41 epitope is located on the carboxy-terminal side of the apoBS junction (probably within the LDL receptor binding domain). Western blotting hepatic microsomal subfractions showed that in the rough and smooth microsomes, HB41 recognized only apoBL, while in the Golgi it recognized both apoBL and a protein having a molecular weight slightly smaller. In contrast, Western blotting with a polyclonal antibody known to recognize both apoBL and apoBS showed that, in rough and smooth microsomes, proteins in addition to apoBL and apoBS having molecular weights between 120,000 and 30,000 were recognized. These proteins, likely to be proteolytic fragments of apoB, were barely detectable in the Golgi. Additional biosynthetic studies show that the [35S]methionine-labeled proteins smaller than apoB were immunoprecipitated from the rough microsome subfraction. Pulse-chase experiments show that these are produced with the same kinetics as full-size apoBL and apoBS, indicating that they are not incomplete nascent chains. Finally, immunofluorescence microscopy was used to determine the localization of monoclonal epitopes. ApoB monoclonal antibodies that recognized exclusively apoBL (HB41) and apoBL and apoBS (DB11) produced an immunofluorescence pattern characteristic of the endoplasmic reticulum, but not the Golgi. These data suggest that, in cultured rat hepatocytes, the majority of both molecular weight forms of apoB are localized in the endoplasmic reticulum, the initial site of VLDL assembly. The additional finding that proteolytic fragments of apoB are enriched in the microsomal fraction suggests that if the proteolysis occurs during subcellular fractionation, immature apoB is susceptible to proteolysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Compartmentalization of intraalveolar and systemic lipopolysaccharide-induced tumor necrosis factor and the pulmonary inflammatory response

Tumor necrosis factor-alpha (TNF), a monokine produced by lipopolysaccharide (LPS)-stimulated macrophages, is an activator of phagocytic functions and may modulate host responses during infection. To determine the effects of LPS on TNF activity and the pulmonary inflammatory response in vivo, we challenged rats systemically or intratracheally with LPS. Intravenous LPS significantly increased serum TNF content from nondetectable levels in control specimens to peak levels at 90 min, which declined to baseline by 3 h. In response to intratracheal LPS, levels of TNF both in bronchoalveolar lavage fluid and associated with alveolar macrophages increased significantly from near nondetectable levels in control animals. Increases in TNF levels were confined to the LPS-challenged compartment. Intravenous LPS resulted in a decrease in the number of peripheral blood neutrophils and in sequestration of these cells within the pulmonary vasculature. In contrast, intratracheal LPS elicited a marked intraalveolar inflammatory response.

Gradient acrylamide/agarose gels for electrophoretic separation of intact human very low density lipoproteins, intermediate density lipoproteins, lipoprotein a, and low density lipoproteins

An exponential gradient gel with 0-10% acrylamide and 0.5% agarose was developed for electrophoresis of intact high molecular weight lipoproteins. This system resolves very low density lipoproteins, intermediate density lipoproteins, lipoprotein a, and low density lipoproteins in a size-dependent fashion. The characteristic relative mobility of these species can be determined in relation to protein and colloidal gold reference materials. Electron microscopy of selected lipoprotein fractions confirmed that relative mobility was related to apparent lipoprotein diameter. The composite gel medium can be used with prestained lipoproteins and permits immunoelectroblotting for qualitative analysis of apolipoprotein constituents.

Lipoprotein lipase-suppressing mediator in serum of endotoxin-treated rats

The conditions under which lipoprotein lipase-suppressing mediator is present in serum of endotoxin-treated rats was determined in this study. The suppression of lipoprotein lipase activity in 3T3-L1 cells was used as a bioassay for mediator in serum. Endotoxin (0.1-10 micrograms/ml) and serum from control rats did not suppress lipoprotein lipase activity. Maximum suppression of cell lipoprotein lipase activity (70%) by serum from endotoxic rats required a cell exposure time of 5 h. At the highest dose of endotoxin used (1 mg/100 g), significant suppression was achieved when cells were incubated with 0.5% serum from endotoxic rats (P less than 0.05). Serum obtained 2-3 h after endotoxin injection possessed the maximal ability to suppress lipase activity, but suppressing activity was not present in serum collected 8 h after endotoxin. Rats rendered tolerant to endotoxin by 5 daily injections (0.1 mg/100 g) did not contain detectable levels of mediator in serum after endotoxin injection. The results demonstrate that the presence of lipoprotein lipase activity-suppressing mediator is transitory after in vivo exposure of naive rats to endotoxin, but does not appear in serum of endotoxin tolerant rats.

Juvenile periodontitis. I. Demonstration of local immunoglobulin synthesis

The purpose of this investigation was to determine the presence and quantity of immunoglobulin G (IgG) and albumin (ALB) in specified periodontal tissues and serum from patients diagnosed as having juvenile periodontitis (JP), using an immunoelectrophoresis technique and to determine which portion of the lesion generated the greatest local immunoglobulin production. Serum and tissue samples were obtained from 19 patients (ages 13-21 years) who were diagnosed as having JP; 18 were female; 16 were black. Normal, diseased, and granulomatous gingival/periodontal tissues were collected during full thickness flap surgery, then minced, homogenized, and centrifuged. Supernatants containing the gingival/periodontal protein and the serum were electrophoresed against rabbit antihuman IgG and ALB. The relative IgG/ALB ratios in each specimen were plotted against known concentrations of IgG using a least squares analysis to provide evidence for local synthesis. In comparing mean IgG/ALB ratios for all tissue types, it was noted that normal gingiva did not differ significantly from serum. Diseased and granulomatous tissues, taken together or separately, had significantly higher IgG/ALB ratios than normal gingiva or serum, demonstrating that 73.6% of the IgG present was due to local synthesis. However, the greatest amounts of locally produced IgG were found in the granulomatous tissue from the deepest areas of the defects.

Identification of a mouse monoclonal antibody, LHLP-1, specific for human Lp(a)

Heretofore, immunologic reagents used to define and quantify human Lp(a) have been polyclonal in origin and therefore heterogeneous in antigenic specificity. We report here the isolation of a mouse monoclonal antibody, LHLP-1, monospecific for Lp(a). The antigen reactive with LHLP-1 was expressed in both lipoprotein Lp(a) as well as apolipoprotein Lp(a) delipidated by SDS treatment; however, disulfide reduction of apolipoprotein Lp(a) inhibited LHLP-1 reactivity. The antigen reactive with LHLP-1 on Lp(a), therefore, appears not to require lipid for expression of its conformationally dependent (disulfide-inhibitable) epitope. Antigen reactivity was virtually absent in the apoB and other proteins contained in very low density, low density, and high density lipoprotein particles. Immunologic quantification of Lp(a) in individual serum samples with a rabbit reference antiserum or LHLP-1 showed good correlation. We conclude that the monoclonal antibody LHLP-1 identifies an antigen unique to Lp(a) and that this antibody may therefore be useful in the further characterization and measurement of human Lp(a).

Production and characterization of a monoclonal antibody to dog hepatic lipase

Partially purified dog hepatic lipase was used as antigen to produce monoclonal antibodies in mice. In addition to enzyme-linked immunosorbent assay (ELISA), a reliable and efficient procedure for screening antibodies reacting to hepatic lipase has been developed. A method to distinguish antibodies directing to active site or non-active site epitopes has also been described. We obtained three positive clones that survived after subcloning and expansion. All three monoclonal antibodies possess gamma one (gamma 1) heavy chains and kappa (kappa) light chains. Specificity of monoclonal antibody LDHL No. 537 to dog hepatic lipase was demonstrated by passing post-heparin plasma through its immunoaffinity column. Only dog hepatic lipase was removed by LDHL No. 537 from post-heparin plasma. The immunoaffinity chromatography also demonstrated the co-existence of three enzyme activities (mono- and triacylglycerol lipase and phospholipase A1) on the dog hepatic lipase molecule. The subunit weight of dog hepatic lipase has been estimated at 57500 +/- 600 (n=3) by using immunoaffinity chromatography and the combination of immunoprecipitation and autoradiography methods.

Local immunoglobulin synthesis in juvenile periodontitis: initial findings

An electro-immunoassay technique was used to determine simultaneously immunoglobulin G (IgG) and albumin concentrations in serum and extracts of gingival tissue comprising the pocket wall. Assays of samples obtained from seven patients with juvenile periodontitis (mean age, 18 years) indicated that local synthesis accounted for 72% of the IgG found in the gingiva.

Adenocarcinoma of the esophagus: relationship to Barrett mucosa

Primary adenocarcinoma of the esophagus is thought to be a rare lesion. However, pathologic records at our institution from 1979 to 1982 show that adenocarcinoma accounted for 17 of 89 (19%) of all primary malignant tumors in the esophagus. All 17 cases arose in Barrett mucosa. In eight cases, there was surgically proved involvement of the gastric cardia or fundus. In six of these cases, there was evidence of esophageal dysplasia and/or carcinoma in situ adjacent to or remote from the proximal margin of the tumor. The pathologic findings therefore strongly suggest an esophageal origin of these lesions with subsequent spread into the stomach. Clinical and radiographic findings at presentation were indistinguishable from those of squamous cell carcinoma. However, 10 patients had long-standing reflux symptoms, and Barrett esophagus had presumably been present for some time prior to the development of malignancy. Since adenocarcinoma evolves through a sequence of dysplasia and carcinoma in situ in pre-existing Barrett epithelium, the best hope for improving survival may be periodic endoscopic surveillance of asymptomatic individuals who have this condition.

Barrett esophagus: reticular pattern of the mucosa

Barrett esophagus is an acquired condition with progressive columnar metaplasia of the esophagus due to chronic reflux esophagitis. The premalignant nature of this entity is well recognized. However, radiologic diagnosis has been limited by the nonspecificity of findings associated with the condition. We recently reviewed 29 cases of pathologically proved Barrett esophagus. Radiologic examinations revealed hiatal hernias, gastroesophageal reflux, esophagitis, and strictures. None of these findings are diagnostic of Barrett esophagus. In seven cases, however, double-contrast radiography also revealed a delicate reticular pattern in the esophagus. In all but one case, there was an adjacent stricture, and this reticular appearance extended distally a short but variable distance from the stricture. To our knowledge, this unusual reticular pattern has not been described previously, and it represents a valuable radiologic sign of Barrett esophagus. The etiology of this finding is uncertain, but correlation with the gross surgical specimen in one case suggests that it results specifically from areas of "villous" metaplasia in Barrett epithelium. This delicate reticular pattern appears to be a specific radiologic criterion for the diagnosis of Barrett esophagus.

Ileocecal endometriosis presenting with abdominal pain and gastrointestinal bleeding

A 26-year-old woman with enteric endometriosis presenting with cecocolic intussusception, a cecal mass on barium enema, and gastrointestinal hemorrhage is described. Laparotomy revealed cecocolic intussusception, ileocecal endometrial implants, and cecal mucosal ulceration presumed secondary to ischemia of the intussuscepted bowel. Histopathology showed serosal and subserosal endometrial implants without mucosal invasion. A review of the literature of endometrial bowel disease is presented.

Adenocarcinoma of the esophagus in patients with scleroderma

Three cases of patients with esophageal involvement by scleroderma, chronic reflux esophagitis, and adenocarcinoma of the distal esophagus are presented. An underlying columnar metaplasia (Barrett esophagus) was identified in two patients and postulated in the third. It is believed that scleroderma patients with symptomatic chronic gastroesophageal reflux should be investigated for Barrett epithelium. If it is present, these patients should be followed and considered as having an increased risk for development of adenocarcinoma of the esophagus.

Carcinoma of the gastric cardia in young people

Carcinoma of the gastric cardia is usually considered a disease of middle-aged or elderly patients and is rarely suspected in young individuals. However, six cases are reported in patients under 45 years of age. The youngest was 26. A review of patient records revealed no obvious predisposing factor to account for the development of cancer at an early age. In four cases, double-contrast upper gastrointestinal examinations revealed a polypoid mass at the cardia. In two cases, however, the true origin of a tumor arising at the cardia was only recognized by obliteration of the normal anatomic landmarks at the cardia associated with irregular areas of ulceration. In all six cases, the tumor extended into the distal esophagus. Five patients presented with dysphagia. Careful radiographic evaluation of the cardia and fundus is therefore essential to rule out an underlying carcinoma of the cardia in all patients with dysphagia, regardless of age.

Barrett's metaplasia and adenocarcinoma of the esophagus and gastroesophageal junction

Most previous studies of Barrett's metaplasia have used biopsy material to document cell, gland, and architectural types, leading to inaccurate or incomplete conclusions. The present study presents data from eight esophagogastrectomy specimens of Barrett's metaplasia with associated neoplasia, which were evaluated topologically by use of dissecting microscopy, specimen radiography, scanning electron microscopy, and routine histologic examination. Barrett's metaplasia was found to be mosaic of cell, gland, and architectural types, showing variable degrees of atrophy and maturation toward intestinal and gastric epithelium. Zonation was not found. Surface mucous, goblet, absorptive, mucous neck, mucous gland, and neuroendocrine cells were found in all cases; Paneth, chief, and parietal cells were found in approximately half. The presence of villar architecture with lining goblet and absorptive cells is unique and can be used to make a biopsy diagnosis. In one case, only a minute residual focus of Barrett's metaplasia was found, suggesting that the pathogenesis of some cases of adenocarcinoma of the lower esophagus and gastric cardia unassociated with Barrett's metaplasia may be the same. Nine cases of adenocarcinoma of the gastroesophageal junction unassociated with Barrett's metaplasia, studied during the same time period, had similar epidemiologic characteristics including mean age, age range, and sex distribution. Multifocal dysplasia and carcinoma in situ were found in all but one case. In two of eight cases adenomatous change was present; one of these resembled a villous adenoma of the colon with malignant degeneration. Barrett's metaplasia thus appears to be important as a precursor of adenocarcinoma in the region of the lower esophagus and gastroesophageal junction. The significance of these findings in relation to previous reports is discussed.

Evidence for local immunoglobulin synthesis in periodontitis

Periodontitis lesions are characterized by an increased plasma cell infiltrate. These cells have been shown to increase in number with the severity of the disease and in vitro synthesis of immunoglobulins by gingival plasma cells has been shown in tissue culture. This study correlated gingival and serum immunoglobulin levels to reflect the in vivo production of immunoglobulin. An electroimmunoassay technique was employed to determine serum and gingival IgG concentrations simultaneously relative to reference albumin levels in 16 patients with periodontitis. Results indicated that local immunoglobulin synthesis and accumulation occurs at the gingival site. Data obtained demonstrated that an average of 74.56% of the IgG found in gingiva from periodontitis patients was of local origin.

Use of monoclonal antibodies in detection of melanoma-associated antigens in intact human tumors

The use of antimelanoma monoclonal antibodies on tissue sections using a two-step indirect immunoperoxidase technique is reported. Antibodies 691-13-17 and 691-I5-Nu4B reacted with dysplastic nevus cells and all melanomas tested, but not with normal skin melanocytes, intradermal nevi, or lentigines. Antibody 691-13-17, directed against DR antigen, reacted also with Langerhan's cells, macrophages, and a subpopulation of lymphocytes. Antibody 691-I5-Nu4B reacted only with melanomas. The technique allows analysis of the expression of antigens by tumor cells in situ.

Double-contrast enema in pelvic endometriosis

The radiographic findings on barium enema in 42 patients with endometriosis were reviewed and correlated with those at surgical and laparoscopic examination. Radiographic abnormalities were detected in 27 patients. In nine patients, purely extrinsic mass effect was identified; bowel wall involvement in these patients was not present at laparoscopy. In 16 of 18 patients subsequently shown to have bowel wall involvement, mass effect with fine mucosal crenulation was identified. Annular or polypoid involvement was also noted. Mass effect with crenulation, although not entirely specific, appears to be a characteristic finding in patients with bowel wall involvement due to endometriosis.

Expression of DR antigens in freshly frozen human tumors

DR antigens are thought to function as differentiation antigens and to restrict immune recognition between T cells and B cells, monocyte/macrophages, Langerhan's cells, and endothelial cells. These antigens are commonly found on tissue culture lines from metastatic melanomas and tumors of lymphocyte derivation but are notably uncommon on cell lines from other malignancies. Using frozen tissue sections, a monoclonal antibody (WI 691-13-17) known to detect an epitope common to all DR alloantigens on the beta (light) chain of DR antigens, and a two-step indirect immunoperoxidase technique, DR antigens were found on all metastatic lesions tested and on many primary tumors and their histogenetic precursors. The technique of using monoclonal antibodies in indirect immunoperoxidase staining of freshly frozen tissue allows individual cells to be assessed for antigen expression and presumably more accurately reflects in vivo antigen expression than results obtained from cells selected by tissue culture methods.

Adenocarcinoid tumor of the colon arising in preexisting ulcerative colitis

Patients with ulcerative colitis are at increased risk of developing adenocarcinoma of the colon. The authors describe a patient whose colonic neoplasm demonstrated histologic characteristics of both an adenocarcinoma and a carcinoid tumor and which was pathologically identical to a appendiceal adenocarcinoid. Because individual tumor cells stained positively for both mucin and argentaffin granules, the histologic picture is unique among the malignancies seen in patients with ulcerative colitis and cannot be explained as a composite of two independent neoplasms that have grown together. Since the tumor discussed seems to have originated from a single cell line, the theory that carcinoids develop from neural crest cells which have migrated to embryonic gut endoderm must be regarded with considerable doubt.