The unusual suspects: Screening for persistent, mobile, and toxic plastic additives in plastic leachates

Plastic additives are a diverse group of chemical compounds added to plastic products to give them their unique physical-chemical properties. Persistent, mobile, and toxic (PMT) plastic additives are a highly polar, environmentally stable sub-group of plastic additives with a variety of uses in plastic products. Due to their mobility into water, they can pose a significant long-term risk to the aquatic environment. Despite the potential threat, PMT plastic additives remain largely unregulated and under-studied. Notably, there is a need for dedicated analytical methodology and leaching studies to determine their potential emission from plastic products. Here we present an optimized leaching protocol and novel instrumental analysis method for the screening of 124 PMT plastic additives registered for use in Canada using high performance liquid chromatography with quantitative time-of-flight mass spectrometry (HPLC-QToF-MS). The analytical method covered a log Kow/Dow range between 0.21 and 6.02, which covered 72% of the PMT plastic additives used in Canada. A total of 52 PMT plastic additive suspects were leached in the optimization experiments, 44 of which were unique based on accurate mass and retention time. The conditions that resulted in the greatest numbers of PMT plastic additives leached were lake water, UV light exposure, and a timeframe of approximately 30 days. The analytical and leaching methods presented here offer new tools to study PMT plastic additives and assess their leaching in an environmentally relevant matrix, which can inform monitoring, threat assessment, and regulatory efforts moving forward.

Integrated surveillance of human respiratory viruses in addition to SARS-CoV-2 in a public testing facility in the Netherlands

BACKGROUND

SARS-CoV-2 prevention measures impact the circulation of other respiratory viruses. Surveillance in the network of general practitioners is hampered by widespread testing for SARS-CoV-2 in public testing facilities.

OBJECTIVES

To evaluate integrated community surveillance of SARS-CoV-2 and other respiratory viruses and describe epidemiological trends.

STUDY DESIGN

Respiratory surveillance was set up within an existing SARS-CoV-2 public testing facility. Community-dwelling (a)symptomatic persons provided consent for completion of a questionnaire and additional testing on residual material from swabs taken for SARS-CoV-2 RT-PCR (Allplex Seegene). Daily, a random subset was tested for sixteen respiratory viruses by multiplex realtime PCRs (Seegene).

RESULTS

Between October 6th (week 40) 2021 and April 22nd (week 16) 2022, 3,969 subjects were tested. The weekly median age ranged from 23 to 39 years. The prevalence of respiratory symptoms ranged from 98.5% (week 40) to 27.4% (week 1). The prevalence of detection of any respiratory virus (including SARS-CoV-2), ranged from 19.6% in week 49 to 75.3% in week 14. SARS-CoV-2 prevalence ranged from 2.2% (week 40) to 63.3% (week 14). Overall, SARS-CoV-2 was detected most frequently (27.3%), followed by rhinoviruses (14.6%, range 3.5-47.8%) and seasonal coronaviruses (3.7%, range 0-10.4%, mostly 229E and OC43). Influenzavirus was detected in 3.0% of participants from week 6 onwards.

CONCLUSIONS

Integrated respiratory viral surveillance within public testing facilities is feasible and informative. Prevalences may be affected by changes in SARS-CoV-2 prevention and testing policies. Population characteristics help to interpret trends over time. Integrated surveillance may inform policymakers and hospitals for adequate response measures during respiratory seasons.

Persistent, mobile, and toxic plastic additives in Canada: properties and prioritization

The hazards of many plastic additives on human and environmental health are well documented. However, little emphasis has been put on plastic additives that are persistent, mobile, and toxic (PMT) rather than persistent, bioaccumulative, and toxic. Due to their high mobility and stability, it is unlikely that wastewater treatment plants will effectively remove PMT plastic additives. Herein, an in silico analysis was performed to (1) assess the retention of PMT plastic additives registered for use in Canada in wastewater treatment plants; and (2) determine whether their physical-chemical properties and structural features can be used as identifiers for PMT plastic additives with particularly low retention. We identified 124 PMT plastic additives of which 52% had less than 20% removal from wastewater treatment based on predictions using the model SimpleTreat. Log K_aw, log K_ow/D_ow, and log K_oc/D_oc ranges were defined that are indicative of low retention PMT plastic additives. Furthermore, it was found that non-halogenated PMT plastic additives that contain nitrogen are most likely to be poorly retained in wastewater treatment plants. The results of this study provide screening and prioritization criteria, as well as a suspect list for PMT plastic additives.

A High-Throughput Platform for the Rapid Screening of Vitamin D Status by Direct Infusion-Tandem Mass Spectrometry

Vitamin D is an important fat-soluble prohormone with pleiotropic effects on human health, such as immunomodulation of the innate and adaptive immune system. There is an unmet clinical need for a rapid screening platform for 25-hydroxyvitamin D (25OH-D) determination without chromatographic separation that offers better precision and accuracy than immunoassays. Here, we introduce a high-throughput method for assessing vitamin D status from blood specimens based on direct infusion-MS/MS (DI-MS/MS) following click derivatization using 2-nitrosopyridine. We developed an optimized liquid-phase extraction protocol to minimize ion suppression when directly infusing serum or plasma extracts via a capillary electrophoresis system for quantitative determination of 25OH-D. Acceptable reproducibility (mean coefficient of variation = 10.9%, n = 412), recovery (mean = 102% at 15, 30, and 45 nmol/l), and linearity (R² > 0.998) were achieved for 25OH-D with lower detection limits (limit of detection ∼1.2 nmol/l, S/N ∼ 3), greater throughput (∼3 min/sample), and less bias than a commercial chemiluminescence immunoassay prone to batch effects. There was mutual agreement in 25OH-D concentrations from reference blood samples measured by DI-MS/MS as compared with LC-MS/MS (mean bias = 7.8%, n = 18). We also demonstrate that this method could reduce immunoassay misclassification of vitamin D deficiency in a cohort of critically ill children (n = 30). In conclusion, DI-MS/MS offers a viable alternative to LC-MS/MS for assessment of vitamin D status in support of large-scale studies in nutritional epidemiology as well as clinical trials to rapidly screen individual patients who may benefit from vitamin D supplementation.

Status of the UCN experiment

The neutron is the simplest nuclear system that can be used to probe the structure of the weak interaction and search for physics beyond the standard model. Measurements of neutron lifetime and β-decay correlation coefficients with precisions of 0.02% and 0.1%, respectively, would allow for stringent constraints on new physics. The UCNτ experiment uses an asymmetric magneto-gravitational UCN trap with in situ counting of surviving neutrons to measure the neutron lifetime, τn = 877.7s (0.7s)stat (+0.4/−0.2s)sys. We discuss the recent result from UCNτ, the status of ongoing data collection and analysis, and the path toward a 0.25 s measurement of the neutron lifetime with UCNτ.

Digestibilidade aparente de farinha de carne e ossos de peixe para tilápia do Nilo

Este trabalho foi realizado com o objetivo de determinar a digestibilidade aparente da proteína bruta, extrato etéreo, energia bruta, cálcio e fósforo das farinhas de carne e ossos de tilápia do Nilo (Oreochromis niloticus), do catfish (Ictalurus punctatus), do pintado (Pseudoplatystoma corruscans) e do bagre africano (Clarias gariepinus) para a tilápia do Nilo. Para tal, foi utilizado o método indireto, com o uso do óxido de cromo (III) (Cr2O3), como indicador inerte, incorporado na ração em 1 g·kg-1. Foram distribuídas 400 tilápias com 50±7,89 g (média ± DP) em 20 tanques cônicos em um delineamento experimental inteiramente ao acaso, constituído por cinco tratamentos com quatro repetições. Os tratamentos foram compostos de uma dieta referência e outras quatro dietas constituídas de 800 g·kg-1 da dieta referência e 200 g·kg-1 da farinha de carne e ossos de tilápias, catfish, pintado e bagre africano. A farinha de carne e ossos de pintado demonstrou melhor digestão para proteína bruta, cálcio e fósforo, enquanto a farinha de carne e ossos de tilápia obteve valor maior para extrato etéreo e energia digestível. Para matéria mineral, o maior resultado obtido foi para a farinha de carne e ossos de catfish. Os resultados deste estudo sugerem que a tilápia do Nilo apresenta limitada capacidade para digerir e utilizar os componentes presentes nas farinhas de ossos avaliadas. A presença de grande quantidade de colágeno estrutural nesses ingredientes e sua baixa digestibilidade pode ter causado redução na disponibilidade do cálcio e fósforo.

Human herpes virus 6 reactivation: important predictor for poor outcome after myeloablative, but not non-myeloablative allo-SCT

Hematopoietic SCT (HSCT) is often complicated by viral reactivations. In this retrospective cohort study (January 2004-August 2008), predictors for human herpes virus 6 (HHV6)-reactivation and associations between HHV6-reactivation and clinical outcomes after allogeneic HSCT were studied. HHV6 DNA load in plasma was monitored weekly by quantitative real-time PCR. Associations between the main end point HHV6-reactivation and other end points, that is, acute GVHD (aGVHD) and NRM were analyzed using Cox proportional hazard models. In total, 108 patients receiving either a myeloablative (MA; n=60) or non-myeloablative (NMA; n=48) conditioning regimen were included. Median age was 40 years (range 17-65); median follow-up was 20 months (range 3-36). In 16/60 (27%) patients with MA conditioning regimen, a HHV6 reactivation was observed (mean viral load 50 323 cp/mL) compared with 2/48 (4%) patients with a NMA conditioning regimen with low viral load (mean 1100 cp/mL). In multivariate analysis, MA conditioning was the only predictor for HHV6 reactivation (P=0.02). In addition, HHV6 reactivation was associated with grades 2-4 aGVHD (P<0.001) and NRM (P=0.03). Regular monitoring of HHV6 reactivation after HSCT might be important in MA HSCT patients to enable early initiation of antiviral treatment or to anticipate aGVHD, all of which may improve clinical outcome.

Glomerular sieving of three neutral polysaccharides, polyethylene oxide and bikunin in rat. Effects of molecular size and conformation

AIM

Polysaccharides and many other non-protein polymers generally have a more open, flexible and asymmetrical structure compared with globular proteins. For a given molecular weight (MW), the Stokes-Einstein radius (a(e)) of the following polymers increases in the order: Ficoll < dextran <or= pullulan < polyethylene oxide (PEO). We have tested the hypothesis that such an increase in 'molecular extension' will increase the molecule's glomerular permeability. Thus, we investigated the glomerular sieving coefficients (theta) of the mentioned polymers and of the negatively charged and extended protein bikunin.

METHODS

In anaesthetized Wistar rats, glomerular sieving curves were generated for each FITC-labelled polymer from their respective concentration in urine and plasma, determined by size exclusion chromatography. The theta for bikunin was measured using a tissue uptake technique.

RESULTS

For a molecule of a(e) = 55 A (cf. IgG), theta increased in the order: Ficoll (0.00035 +/- 0.000013) < dextran (0.022 +/- 0.0029) < pullulan (0.033 +/- 0.0024) < PEO (0.12 +/- 0.0055). For a(e) = 36 A (cf. albumin) the order was: Ficoll (0.076 +/- 0.0061) < dextran (0.45 +/- 0.037) = pullulan (0.45 +/- 0.021) < PEO (0.65 +/- 0.0076). theta for bikunin (0.089 +/- 0.0045) was 150 times higher than that of albumin, having an equivalent a(e) and net negative charge.

CONCLUSION

From these results it is concluded that for flexible and asymmetric macromolecules, their degree of glomerular hyperpermeability is proportional to their degree of 'molecular extension'. Thus, compared with globular proteins, the polysaccharides investigated, including Ficoll, were found to be hyperpermeable across the glomerular filter in vivo.

Evaluation of the analytical performance of the new Abbott RealTime RT-PCRs for the quantitative detection of HCV and HIV-1 RNA

BACKGROUND

Despite FDA approval and CE marking of commercial tests, manufacturer independent testing of technical aspects is important.

OBJECTIVES

To evaluate the analytical performance of the new Abbott RealTime HCV and HIV-1 viral load tests.

STUDY DESIGN

Sensitivity, specificity and inter-/intra-assay variation were investigated. The HCV and HIV-1 assays were compared with Siemens bDNA 3.0 and Roche Cobas Monitor 2.0, respectively, on diagnostic samples.

RESULTS

Lower isolation volumes on the M1000 gave minor but statistically significant lower quantitative values. Minor differences were observed in the lower limit of detection relative to the specification given by the manufacturer. Inter-/intra-assay coefficients of variations ranged from 0.31 to 4.75 between 5.0 x 10(4) and 5.0 x 10(2) copies/mL. Both the HCV and HIV-1 Abbott RealTime tests did not show a geno-/sub-type dependent under-quantification on WHO reference panels, quality control panels or clinical specimens. The Abbott RealTime HIV-1 viral load assay detected subtype O whereas several other systems failed to detect this subtype.

CONCLUSION

The technical aspects of the HCV and HIV-1 RealTime viral load assays on the M2000 system make it attractive for use in routine diagnostic settings.

Several daily measurements are necessary to reliably assess the cortisol rise after awakening: state- and trait components

The cortisol rise after awakening (CAR) is a frequently applied measure of pituitary-adrenal activity. This measure seems to reflect the acrophase of the diurnal cycle and can easily be assessed in saliva samples, collected by the proband or patient under real life conditions. Since different state and trait factors affect the CAR, we here address the questions (a) to which extent state and trait factors affect the CAR, and (b) how often cortisol measures after awakening have to be taken to obtain reliable results. In this study, we assessed the CAR on 6 consecutive days. After applying structural equation models and correlation analyses, we conclude that (a) the CAR of a single day is determined to a great extent by situational factors and only for a small proportion by trait factors and (b) from two (AUC(t)) to six (AUC(i)) days are necessary to achieve reliable trait measures, since state factors bias data from a single day.

Characterization of the interaction between tumor necrosis factor-stimulated gene-6 and heparin: implications for the inhibition of plasmin in extracellular matrix microenvironments

TSG-6, the secreted product of tumor necrosis factor-stimulated gene-6, is not constitutively expressed but is up-regulated in various cell-types during inflammatory and inflammation-like processes. The mature protein is comprised largely of contiguous Link and CUB modules, the former binding several matrix components such as hyaluronan (HA) and aggrecan. Here we show that this domain can also associate with the glycosaminoglycan heparin/heparan sulfate. Docking predictions and site-directed mutagenesis demonstrate that this occurs at a site distinct from the HA binding surface and is likely to involve extensive electrostatic contacts. Despite these glycosaminoglycans binding to non-overlapping sites on the Link module, the interaction of heparin can inhibit subsequent binding to HA, and it is possible that this occurs via an allosteric mechanism. We also show that heparin can modify another property of the Link module, i.e. its potentiation of the anti-plasmin activity of inter-alpha-inhibitor (IalphaI). Experiments using the purified components of IalphaI indicate that TSG-6 only binds to the bikunin chain and that this is at a site on the Link module that overlaps the HA binding surface. The association of heparin with the Link module significantly increases the anti-plasmin activity of the TSG-6.IalphaI complex. Changes in plasmin activity have been observed previously at sites of TSG-6 expression, and the results presented here suggest that TSG-6 is likely to contribute to matrix remodeling, at least in part, through down-regulation of the protease network, especially in locations containing heparin/heparan sulfate proteoglycans. The differential effects of HA and heparin on TSG-6 function provide a mechanism for its regulation and functional partitioning in particular tissue microenvironments.

Effects of soy lecithin phosphatidic acid and phosphatidylserine complex (PAS) on the endocrine and psychological responses to mental stress

Phosphatidylserine, derived from cow brains, has been shown previously to dampen the ACTH and cortisol response to physical stress. Further research investigated the influence of soy lecithin phosphatidylserine supplementation on mood and heart rate when faced with an acute stressor. In this study, we investigated the effects of soy lecithin phosphatidic acid and phosphatidylserine complex (PAS) supplementation on pituitary adrenal reactivity (ACTH, cortisol) and on the psychological response (Spielberger State Anxiety Inventory stress subscale) to a mental and emotional stressor. Four groups of 20 subjects were treated for three weeks with daily dosages of either 400 mg PAS, 600 mg PAS, 800 mg PAS, or placebo before exposure to the Trier Social Stress Test (TSST). Treatment with 400 mg PAS resulted in a pronounced blunting of both serum ACTH and cortisol, and salivary cortisol responses to the TSST, but did not affect heart rate. The effect was not seen with larger doses of PAS. With regard to the psychological response, 400 mg PAS seemed to exert a specific positive effect on emotional responses to the TSST. While the placebo group showed the expected increase in distress after the test, the group treated with 400 mg PAS showed decreased distress. These data provide initial evidence for a selective stress dampening effect of PAS on the pituitary-adrenal axis, suggesting the potential of PAS in the treatment of stress related disorders.

Occurrence of organophosphate esters in surface water and ground water in Germany

The present investigation was carried out to quantify the three organophosphate esters, tributyl phosphate (TBP), tris(2-chloroethyl) phosphate(TCEP) and tris(2-butoxyethyl) phosphate(TBEP), in river, rain and ground water obtained from several locations in Germany, and to compare the data with those obtained about 15 years ago. Additionally, one influent and one effluent sample of waste water from a local waste water treatment plant were investigated. The applied analytical method is based on solid phase extraction (SPE), in order to concentrate polar compounds from water samples, followed by gas chromatography-mass spectrometry (GC-MS) of the extracts. A total of 5 1 of the respective water samples was used for extraction purposes and analyte recoveries were all > or = 83%. The detection limit for the target analytes was 1 ng l(-1) and the relative standard deviations for replicate injections (n = 10) were 14.0% for TBP, 12.6% for TCEP and 9.9% for TBEP. The presence of the organophosphorus compounds, TBP, TCEP and TBEP, in Germany has resulted in water concentrations of 17-1,510 ng l(-1) in the Rhine, Elbe, Main, Oder, Nidda and Schwarzbach Rivers. The maximum value of TBP measured in the Rhine River was 17 times lower than the maximum value measured 10 years ago. The maximum value of TCEP measured in the Rhine River was 100 times lower than the maximum value measured in previous investigations. The maximum concentration of TBEP measured in the Elbe River was seven times higher than the value measured 16 years ago. Similar concentrations of TBP, TCEP and TBEP were also detected in ground water and rain water. The highest levels of these compounds were detected in samples of waste water.

[Technology integration and process management. Concept and implementation of a new platform for simultaneous diagnosis and therapy of acutely ill and injured patients and for elective computer assisted surgery (CAS)]

Modern imaging and computer technology gain more and more importance in surgery. This is true for elective and emergency diagnosis and treatment. However integration of technology and optimization of process management is severely behind. A new diagnostic-therapeutic platform should balance this deficit. The platform is composed of a fully equipped operation room environment with integrated high end computer-tomography with navigation, a digital subtraction angiography and an OR- and imaging-table particularly developed for this set-up. The platform may be used for elective diagnosis, for diagnosis and therapy in polytraumatized patients in one and the same location (one stop shop) and for computer assisted surgery (CAS). Bringing the technology to the patient and not the patient to the technology can save time consuming and potentially dangerous transports and expensive personnel can be reduced. Navigation-technology and high quality intra-operative imaging expand the spectrum of minimally invasive surgery.

Effects of filtration rate on the glomerular barrier and clearance of four differently shaped molecules

The effect of shape on the transglomerular passage of solutes has not been hitherto systematically studied. We perfused isolated rat kidneys to determine the fractional clearances (theta) at various filtration rates for four molecules of different shapes but with similar Stokes-Einstein radii (aSE = 34-36 A). The theta for hyaluronan, bikunin, and Ficoll36 A were 66, 16, and 11%, respectively, at a glomerular filtration rate (GFR) of 0.07 ml x min(-1) x g wet wt(-1) and decreased to 46, 14, and 7%, respectively, on a fivefold increase in GFR. Under the same conditions, theta for albumin increased from 0.15 to 0.74%, and similar behavior was observed for larger Ficolls (aSE >45 A). Pore analysis showed that the "apparent neutral" solute radii of Ficoll, albumin, bikunin, and hyaluronan were 35, 64, 33, and 24 A, respectively, despite similar aSE. In addition, the properties of the glomerular filter changed with increasing GFR and hydrostatic pressure. We conclude that elongated shape, irrespective of size and charge, drastically increases the transglomerular passage of a solute, an effect that is related to its frictional ratio.

Cancer prevention in rural youth: teaching goals for health: the pilot

BACKGROUND

The Goals for Health project is designed to change the cancer-related behaviors of tobacco use and dietary fat and fiber consumption. The intervention teaches health and life skills to rural, minority sixth and seventh graders in rural Virginia and New York. This article presents the results of the pilot.

METHODS

Participants were 129 sixth graders at one rural middle school who were surveyed prior to and following delivery of the pilot sixth-grade intervention.

RESULTS

Results include significant changes from pre- to post-intervention in several diet and smoking attitude and self-efficacy variables, dietary fat and fiber knowledge, high-fat snack consumption, and dietary fat scores. Multivariate analyses reveal important contributions of personal control over food choices and family and friend influence on change in dietary fat score from pre- to post-intervention.

CONCLUSIONS

These pilot program results suggest avenues for dietary and cancer prevention interventions in high-risk, rural adolescents.

The low pH in trans-Golgi triggers autocatalytic cleavage of pre-alpha -inhibitor heavy chain precursor

Pre-alpha-inhibitor is a plasma protein whose physiological function is still unknown, but in vitro studies suggest that it might be involved in inflammatory reactions. Pre-alpha-inhibitor consists of a 25- and a 75-kDa polypeptide: bikunin and heavy chain 3 (H3), respectively. H3 is synthesized with a 30-kDa C-terminal extension, which is released in the Golgi complex through cleavage between an Asp and a Pro residue. We now provide evidence that this cleavage is triggered by the low pH in the late Golgi and occurs through an intramolecular process. First, incubation in vitro of the H3 precursor (proH3) at pH 6.0 or lower results in rapid cleavage of the protein. Second, the rate of the cleavage reaction does not depend on the concentration of proH3 and is not affected by the presence of various protease inhibitors. Third, raising the pH in organelles of cells producing proH3 abolishes cleavage during secretion. The amino acid residues near the cleavage site of proH3 differ from those of previously described self-cleaving proteins, indicating that the mechanisms of scission are different.

The effect of accuracy of perceptions of dietary-fat intake on perceived risk and intentions to change

Consumption of excess fat increases risk for many health problems and diseases. In the present study, 188 undergraduate students were studied to understand self-perceptions of dietary-fat intake and the impact of those perceptions. Findings indicated that the majority of participants had inaccurate perceptions about the amount of fat in their diets. Further, compared to people who overestimated dietary-fat intake, people who underestimated fat intake had lower perceived risk of cancer, had lower intentions to change, and demonstrated less knowledge about the dietary-fat content of many foods. Findings suggest that this unrealistic underestimation of fat intake is a cognitive barrier to dietary change and people who underestimate dietary fat intake may require more intensive intervention to change their diets.

Development of a quantitative real-time detection assay for hepatitis B virus DNA and comparison with two commercial assays

A highly reproducible and sensitive real-time detection assay based on TaqMan technology was developed for the detection of hepatitis B virus (HBV) DNA and compared with two commercially available assays. The assay was validated with the Viral Quality Control panel, which also includes EUROHEP HBV DNA standards. This real-time PCR detection system had a dynamic range of 373 to 10(10) genome copies per ml and showed an excellent correlation with both the commercial HBV Digene Hybrid Capture II microplate assay (Digene Diagnostics) and the HBV MONITOR assay (Roche Diagnostics). To demonstrate its clinical utility, four chronically HBV-infected patients treated with lamuvidine were monitored using the three different assays. From the results we concluded that this assay is an excellent alternative for monitoring of HBV-infected patients in routine diagnostics and clinical practice, enabling the analysis of a large dynamic range of HBV DNA in a single, undiluted sample.

Purification, characterization, and biological compartmentalization of rat fetal antigen 1

This study has established the rat as an animal model for the analysis of the biological role of fetal antigen 1 (FA1), a protein previously described in humans and mice. FA1 was purified from rat amniotic fluid by immunospecific affinity chromatography. Immunochemical identity between mouse and rat FA1 was established by crossed tandem immunoelectrophoresis. Molecular size was analyzed by mass spectrometry (33 kDa). The amino acid composition was determined, and the amino acid sequence was analyzed. The overall amino acid composition and sequence of the 28 first N-terminal amino acids were identical to the corresponding parts of rat preadipocyte factor 1 and rat adrenal zona glomerulosa protein. Extensive sequence similarity was found between rat and mouse FA1 (86%) and between rat and human FA1 (82%). The concentration of FA1 in fetal serum, maternal serum, urine, and amniotic fluid in rats was determined using an ELISA. The highest concentrations were found in fetal serum and amniotic fluid around Day 18 of pregnancy. This is the first report on the physicochemical characteristics and compartmentalization of rat FA1.

A multicenter study evaluation of the digene hybrid capture II signal amplification technique for detection of hepatitis B virus DNA in serum samples and testing of EUROHEP standards

We have evaluated the new Digene Hybrid Capture II HBV DNA Test (HCII HBV), which is a 96-well microtiter plate-based signal amplification assay. This test uses hybrid capture technology that specifically detects RNA-DNA hybrids. HCII HBV is able to quantify hepatitis B virus (HBV) DNA at between 1.4 x 10(5) and 1.7 x 10(9) HBV copies per ml in a standard format. By using a modified sample preparation method, which allows the input of 30-fold more serum for an ultrasensitive format, the sensitivity of the assay can be increased reproducibly to approximately 8,000 copies of HBV per ml. By using a combination of these two formats, the assay can quantify over a total range of 6 logs. In our multicenter evaluation study, the mean laboratory-to-laboratory coefficients of variation were 22, 7, and 12% at the three sites, respectively, with a combined specificity of 98.4%. The linearities of both the standard test and the ultrasensitive test were excellent, with Spearman correlation coefficients of 0.997 and 0.999, respectively. Furthermore, the intra-assay reproducibility for the standard assay gave coefficients of variation of from 13 to 33, 9 to 21, and 3 to 8% at the three sites, respectively. HCII HBV was shown to be genotype independent when the EUROHEP standards for genotypes A and D were used. This assay allows the accurate measurement of HBV DNA levels in serum and can be clinically used for the monitoring of responses to antiviral agents for patients chronically infected with HBV.

Bikunin--not just a plasma proteinase inhibitor

Bikunin is a plasma proteinase inhibitor that has received little attention in the past, probably because its activity towards various proteinases was found to be relatively weak in early work. It was recently discovered, however, that bikunin effectively inhibits a proteinase that seems to be involved in the metastasis of tumour cells--cell surface plasmin--and that a fragment of bikunin inhibits two proteinases of the coagulation pathway--factor Xa and kallikrein. Furthermore, it has been found that bikunin has other properties, such as the ability to modulate cell growth and to block cellular calcium uptake. Most of the bikunin in the blood occurs as a covalently linked subunit of the proteins pre- and inter-alpha-inhibitor. In this form bikunin lacks some of its known activities, and there is evidence that its release by partial proteolytic degradation may function as a regulatory mechanism. Although the physiological function of bikunin still remains to be established, current data suggest that this protein plays a role in inflammation. Further studies could therefore lead to results of therapeutical value.

Development of a real-time quantitative assay for detection of Epstein-Barr virus

With the use of real-time PCR, we developed and evaluated a rapid, sensitive, specific, and reproducible method for the detection of Epstein-Barr virus (EBV) DNA in plasma samples. This method allowed us to screen plasma and serum samples over a range between 100 and 10(7) copies of DNA per ml using two sample preparation methods based on absorption. A precision study yielded an average coefficient of variation for both methods of less than 12%, with a coefficient of regression for the standard curve of a minimum of 0. 98. We detected EBV DNA in 19.2% of plasma samples from immunosuppressed solid-organ transplant patients without symptoms of EBV infections with a mean load of 440 copies per ml. EBV DNA could be detected in all transplant patients diagnosed with posttransplant lymphoproliferative disorder, with a mean load of 544,570 copies per ml. No EBV DNA could be detected in healthy individuals in nonimmunosuppressed control groups and a mean of 6,400 copies per ml could be detected in patients with infectious mononucleosis. Further studies revealed that the inhibitory effect of heparinized plasma could be efficiently removed by use of an extraction method with Celite as the absorbent.

Binding of Zn(2+) to the plasma protein inter-alpha-inhibitor

Inter-alpha-inhibitor (IalphaI) is a serum protein consisting of a chondroitin-sulfate-containing protein of 25 kDa (bikunin) and two other polypeptides of 75-80 kDa (heavy chains 1 and 2). The physiological function of IalphaI is unclear but recent results suggest that it is required for the formation of the extracellular matrix of certain cell types and that it has anti-inflammatory activity. It was previously reported that IalphaI isolated from serum contains bound Zn(2+), but details of this binding are lacking. Using equilibrium dialysis, we have found that when the free Zn(2+) concentration is raised from 0.3 to 50 micromol/L, the number of bound ions increases from 0.1 to 7. The concentration of free Zn(2+) in plasma is in the nanomolar range; our results therefore suggest that inter-alpha-inhibitor does not contain stoichiometric amounts of zinc ions under normal in vivo conditions.

Intracellular proteolytic processing of the heavy chain of rat pre-alpha-inhibitor. The COOH-terminal propeptide is required for coupling to bikunin

Pre-alpha-inhibitor is a serum protein consisting of two polypeptides named bikunin and heavy chain 3 (H3). Both polypeptides are synthesized in hepatocytes and while passing through the Golgi complex, bikunin, which carries a chondroitin sulfate chain, becomes covalently linked to the COOH-terminal amino acid residue of H3 via its polysaccharide. Immediately prior to this reaction, a COOH-terminal propeptide of 33 kDa is cleaved off from the heavy chain. Using COS-1 cells transfected with rat H3, we found that in the absence of bikunin, the cleaved propeptide remained bound to the heavy chain and that H3 lacking the propeptide sequence did not become linked to coexpressed bikunin. Sequencing of H3 secreted from COS-1 cells showed that part of the molecules had a 12-amino acid residue long NH2-terminal propeptide. Cleavage of this propeptide, which occurred in the endoplasmic reticulum, was found to require basic amino acid residues at P1, P2, and P6 suggesting that it is mediated by a Golgi enzyme in transit. Deletion of the NH2-terminal propeptide or blocking of its release affected neither transport nor coupling of the heavy chain to bikunin.

Structural characterization of inter-alpha-inhibitor. Evidence for an extended shape

Inter-alpha-inhibitor (IalphaI) is a 180-kDa serum protein consisting of three polypeptides. Two of these, the heavy chains 1 and 2 (H1 and H2), are of 75-80 kDa and have similar amino acid sequences. The third polypeptide, bikunin, has a molecular mass of 25 kDa and contains a 7-kDa chondroitin sulfate chain that is covalently linked to the C-terminal amino acid residues of H1 and H2. IalphaI has been shown to be required for the formation of the hyaluronan-containing extracellular matrix of certain cell types. How IalphaI exerts this function is not known, but it appears that upon interaction with cells, the heavy chains are released and become covalently linked to hyaluronan. Our results indicate that IalphaI and its heavy chains are extended molecules; thus, upon electron microscopy, IalphaI appeared to consist of two globular domains connected by a thin structure 31-nm long and the isolated heavy chains of a globular domain and a "tail" about 15-nm long. Analysis of the heavy chains by partial proteolysis showed that the C-terminal halves are particularly sensitive to hydrolysis indicating that they are loosely folded. Furthermore, electron microscopy showed that partially degraded heavy chains lacked the extended regions. Taken together, these results suggest that the N-terminal half of the heavy chains forms a globular domain, whereas the other half has an extended and loosely folded structure.

Intracellular coupling of bikunin and the heavy chain of rat pre-alpha-inhibitor in COS-1 cells

Pre-alpha-inhibitor is a serum protein consisting of two polypeptides: bikunin of 16 kDa, which carries an 8 kDa chondroitin sulphate chain, and heavy chain 3 (H3) of 74 kDa. The two polypeptides are linked through an ester bond between an internal N-acetylgalactosamine residue of the chondroitin sulphate chain and the C-terminal aspartic acid residue of H3. Both bikunin and H3 are synthesized by hepatocytes and become linked as they pass through the Golgi complex. H3 is synthesized with both N- and C-terminal extensions which are released during intracellular transport. To be able to analyse the assembly of pre-alpha-inhibitor in detail, we have cloned and sequenced the cDNA of rat H3. Upon expression of the protein in COS-1 cells, both propeptides were found to be released. Furthermore, co-expression of H3 and bikunin resulted in the two polypeptides becoming coupled, indicating that cells other than hepatocytes may have the capacity to form chondroitin sulphate-containing links.

Increase of bikunin and alpha1-microglobulin concentrations in urine of rats during pregnancy is due to decreased tubular reabsorption

Bikunin and alpha1-microglobulin are two plasma proteins of about 25 kDa which are made in the liver from a common precursor. The concentration of bikunin in human urine has been shown to increase several fold during various conditions of stress. The mechanism behind this increase is unknown. We have studied pregnant rats and found that the bikunin and alpha1-microglobulin levels in their urine increased 3-fold towards the end of the pregnancy, whereas those of albumin and orosomucoid did not. There were no significant changes in either the bikunin/alpha1-microglobulin mRNA level or the concentrations of the two proteins in serum. These findings imply that the synthesis and the clearance rates of bikunin and alpha1-microglobulin are normal during pregnancy but that the tubular reabsorption of these proteins is decreased.

Alpha1-microglobulin and bikunin in rats with collagen II-induced arthritis: plasma levels and liver mRNA content

The plasma proteins alpha1-microglobulin (alpha1-m) and bikunin are synthesized in the liver as a common precursor which is cleaved just before secretion. Half of plasma alpha1-m is covalently linked to fibronectin and alpha1-inhibitor-3, and more than 95% of bikunin is part of pre-alpha-inhibitor, inter-alpha-inhibitor and related large molecules. Both alpha1-m and bikunin have been shown to be involved in inflammation, but the regulation of their synthesis is not clear. The authors have measured the plasma and urinary concentrations of alpha1-m and bikunin as well as their hepatic mRNA levels in rats during the development of collagen-induced arthritis. Also, the plasma concentrations of acknowledged acute-phase proteins were measured. The results suggested a biphasic inflammatory reaction: an early response after 1 week, represented by an elevated fibronectin level; and a late response after 3 weeks, represented by elevated alpha1-acid glycoprotein and decreased albumin and alpha1-inhibitor-3 levels. The alpha1-m-bikunin mRNA content in liver was slightly reduced after 1 week and elevated after 3 weeks, but the total concentrations of free and bound alpha1-m and bikunin in plasma were unchanged. The free bikunin fraction as well as the fibronectin/alpha1-m complex in plasma, however, were elevated after 1 week. Urinary bikunin levels were also elevated after 1 week, whereas urinary alpha1-m levels remained unchanged. The results thus suggest that free bikunin in plasma is increased and excreted in the urine at an early stage during the development of collagen-induced arthritis. Later, when the synthesis rate of alpha1-m-bikunin is elevated, both proteins are most likely directed to other locations in the body.

Widely used, commercially available Chlamydia pneumoniae antigen contaminated with mycoplasma

Mycoplasma contamination was detected in a widely used commercially available Chlamydia pneumoniae antigen preparation. Contamination was studied with a mycoplasma group-specific 16S rRNA polymerase chain reaction (PCR) and sequence analysis. Several lots of the purified C. pneumoniae antigen from the Washington Research Foundation appeared to be contaminated with the same Mycoplasma species, which appeared to be closely related to M. arginini. Antigen slides prepared for the detection of chlamydia antibodies by MRL Diagnostics were contaminated with the same Mycoplasma sp. Chlamydia antigen slides from Labsystems OY and two chlamydia complement fixation reagents (Virion International Distribution Ltd and Behring Werke) were not contaminated. It is concluded that commercially available C. pneumoniae antigens may contain mycoplasma antigens as well. Although the impact of such mycoplasma contamination on the results of chlamydia serology may not be significant, routine screening of all antigen preparations obtained by tissue culture before their distribution and use is recommended.

High glomerular permeability of bikunin despite similarity in charge and hydrodynamic size to serum albumin

Bikunin is a chondroitin-sulphate containing serum protein with a Stokes-Einstein radius and a negative net charge close to those of serum albumin. The plasma half life of bikunin is about 10 minutes, and approximately half of its clearance occurs in the kidneys. The quantitative role of glomerular filtration in the renal clearance of this protein has not been determined. To assess the glomerular permeability of bikunin we used isolated rat kidneys that were perfused with an albumin solution. The metabolic activities of the tubuli were inhibited by low temperature (8 degrees C). The clearances of radiolabeled bikunin and albumin were repeatedly determined under identical conditions. The fractional clearance of bikunin was found to be 80 times higher than that of albumin: 15% +/- 1% versus 0.18% +/- 0.02%. This value for bikunin can fully account for its renal clearance in vivo. It has previously been shown that uncharged flexible solutes, such as dextrans, have higher renal clearances than globular molecules with similar radii. The high glomerular permeability of bikunin is therefore probably due to its elongated and flexible configuration. Moreover, the observed clearance value of the anionic molecule bikunin is close to that of a neutral flexible dextran of similar size, indicating that the charge of bikunin is of little importance for its glomerular permeability.

The feasibility of a proactive stepped care model for worksite smoking cessation

Worksite smoking cessation interventions have achieved some success, but until recently have only intervened on those smokers at a stage of readiness to volunteer to participate in cessation programs. The present study assesses whether a sustained, proactive smoking cessation program based on a stepped care model that targets all smoking employees in the worksite can actually be delivered. In one worksite in Seattle (N = 273), a worksite-wide survey with a 99.3% response rate identified 53 smokers; subsequent new-hires added an additional 14 smokers to the worksite. This study delivered increasingly intensive intervention to those smoking employees who failed to quit smoking during the study period of 1.5 years. Telephone contacts (every 3 months) provided motivational messages tailored to the smokers' stage of cessation. Subsequent more intensive steps included self-help manuals and referrals to formal programs. The intervention also used community organization strategies, such as employee guided worksite activities to complement the individual and stepped strategies. In the study period, 18% of the smokers quit smoking. Participation rates in activities were good and on average worksite smokers moved over one stage of change from baseline toward quitting smoking.

Posttranslational folding of alpha 1-inhibitor 3. Evidence for a compaction process

alpha 1-inhibitor 3 (alpha 1 I3) is a rodent-specific proteinase inhibitor of about 190 kDa belonging to the alpha 2-macroglobulin family. It consists of five globular domains, three of which are connected by disulfide bridges, and contains an intramolecular thiol ester which can react with attacking proteinases. To explore the folding of newly synthesized alpha 1 I3, we have used rat hepatocytes and pulsechase experiments. In one of the analyses, the radiolabeled protein was isolated from cell lysates by immunoprecipitation and its Asp-Pro bonds cleaved by treatment with formic acid. The size of the major fragment, as assessed by electrophoresis under nonreducing conditions, was found to increase from 100 to 150 kDa upon the chasing. This result, together with knowledge of the positions of the cleavage sites and the disulfide arrangement, indicates that one of the interdomain disulfide bonds is formed after the synthesis of the polypeptide. Analysis of the same material by limited proteolysis and by velocity centrifugation showed that the folded regions became larger and that the protein became more compact; the thiol ester was found to be formed after these conformational changes. These results suggest that the domains of alpha 1 I3 are only partially developed directly after the synthesis of the polypeptide and that they acquire their final structure as the protein condenses and the domains interact with one another.

Plasma clearance of rat bikunin: evidence for receptor-mediated uptake

Bikunin is a chondroitin sulphate-containing protease inhibitor with a molecular mass of 25 kDa. It is secreted into the blood by hepatocytes, and recent observations indicate that it may have an extravascular function. Here we have studied the plasma clearance of bikunin in rats and mice. On intravenous injection, radiolabelled bikunin was found to have a half-life of 10 min; in rats with ligated renal arteries, the clearance time was twice as long, implying that the kidneys account for half the uptake. As judged by gel filtration, the size of bikunin is similar to that of albumin. Autoradiographic analysis of kidneys removed 2 min after the injection of radiolabelled bikunin indicated that, despite its size, bikunin is cleared by glomerular filtration. On ligation of the renal arteries, the plasma concentration of bikunin increased linearly to at least four times normal. This finding shows that the non-renal uptake system is saturated and therefore presumably receptor-mediated. Most of the non-renal uptake of injected bikunin was found to occur in non-visceral tissues such as the skin. Analysis of skin samples by autoradiography after injection of radiolabelled bikunin suggested that bikunin had been transferred from the plasma to the interstitial space.

Physician recommendations for dietary change: their prevalence and impact in a population-based sample

A random-digit-dialing survey to examine the prevalence, content, and impact of physician dietary recommendations in a representative population-based sample of Washington State residents was administered to 1972 persons aged 18 years and older. Twenty percent of those surveyed received a physician's recommendation for dietary change in the previous year. The most common recommendations were to decrease intake of cholesterol, calories, and red meat and to increase intake of vegetables and fiber. Respondents receiving recommendations were more likely to report decreased use of high-fat foods and increased use of high-fiber foods and to be in the maintenance stage of dietary change. Results suggest that physicians can play a limited role in promoting dietary change.

Inter-alpha-inhibitor is required for the formation of the hyaluronan-containing coat on fibroblasts and mesothelial cells

Cultured cells of various origins have been shown to be surrounded by a hyaluronan-containing coat, a structure that can be visualized by its ability to exclude large particles such as erythrocytes. When cultured in medium with no or low concentrations of serum, the cells lose their coats, although they still produce hyaluronan; upon the addition of serum, the coats are formed again. Here, we show that the serum protein inter-alpha-inhibitor can replace whole serum as an inducer of the formation of the coats on fibroblasts and mesothelial cells. The physiological role of inter-alpha-inhibitor has so far been unclear; our findings, together with those obtained with cumulus cell-oocyte complexes (Chen, L., Mao, S.J., and Larsen, W. J. (1992) J. Biol. Chem. 267, 12380-12386), suggest that inter-alpha-inhibitor and related proteins have a general function as stabilizers of hyaluronan-containing pericellular coats.

Effects of dietary fat feedback on behavioral and psychological variables

This paper reports on the immediate and delayed reactions to dietary fat consumption feedback. Subjects in our study received (1) personalized dietary fat feedback and (2) information about how to alter their fat consumption. Fat consumption was measured using a brief fat assessment instrument. Subjects were categorized into three risk groups: at or below, above, and significantly above the recommended level. Emotional, cognitive, and behavioral reactions were measured immediately after receiving feedback and at 1 month postfeedback. Subjects who received high fat feedback showed greater negative emotional distress in response to the feedback and stated that they knew less about high-fat foods than subjects receiving lower feedback. By the 1-month follow-up, subjects in the highest feedback condition were least likely to report intentions to lower their dietary fat. Interventions designed to alter dietary fat consumption should take into account the emotional and cognitive consequences of risk factor feedback.

Bikunin in rat plasma, lymph and bile

Bikunin is a protease inhibitor consisting of a 16 kDa polypeptide and an 8 kDa chondroitin sulphate chain which has an apparent molecular mass of 60-70 kDa upon gel filtration. It is synthesized by hepatocytes and occurs in plasma, both in free form, and in complex with other polypeptides--mainly as the 180 kDa protein inter-alpha-inhibitor. Bikunin binds to proteases less avidly than other plasma inhibitors, making its role in the blood unclear. However, some observations indicate that bikunin has important functions outside the blood system. To assess its capacity to reach extravascular spaces, we have determined the total concentration of bikunin in plasma (0.17 mg/ml), lymph (31 micrograms/ml) and bile (0.2 microgram/ml). Quantitation after removal of complexed bikunin (inter-alpha-inhibitor) by acid precipitation showed that the concentration of free bikunin in those fluids was 3, 1.4 and 0.05 micrograms/ml, respectively. These values yield a lymph/plasma ratio of free bikunin of 0.5, which is higher than expected for a protein of the hydrodynamic size and charge of bikunin. The bile/plasma ratio (0.02), however, is similar to that of other proteins of comparable size. The corresponding values for inter-alpha-inhibitor, 0.16 and 0.001, respectively, indicate that its capacity to pass through the vascular endothelium is relatively high whereas transfer to bile is restricted. Furthermore, we have found that in a perfusate of an isolated rat liver, the ratio of free to complexed bikunin was 30-40 times higher than in plasma, consistent with previous observations showing that free bikunin is cleared from the blood stream much more rapidly than inter-alpha-inhibitor.

Proteolytic cleavage of haptoglobin occurs in a subcompartment of the endoplasmic reticulum: evidence from membrane fusion in vitro

The primary translation product of haptoglobin mRNA is a 45-kD polypeptide which is proteolytically cleaved shortly after its synthesis. Previous studies have indicated that the cleavage of this proform of haptoglobin occurs in the ER. In an attempt to characterize the cleaving enzyme, we found that upon incubation of microsomes from rat hepatocytes pulse labeled with [35S]methionine, little cleavage of labeled prohaptoglobin occurred. In contrast, when cells whose cytoplasmic proteins had been released by saponin treatment were incubated, 30-40% of the prohaptoglobin was cleaved. The addition of GTP caused a twofold stimulation, which was abolished by the nonhydrolyzable analog GTP gamma S. With a homogenate of the cells, the addition of GTP resulted in a fourfold stimulation of the degree of cleavage--from 15 to 60%. Differential centrifugation revealed that most of the cleaving activity resided in membranes sedimenting similarly to mitochondria and to a small fraction of the ER. These rapidly sedimenting membranes were therefore prepared from a rat liver homogenate. Upon treatment with high salt, light membranes were released which, when incubated with microsomes of pulse-labeled hepatocytes in the presence of detergent (and in the absence of GTP), induced specific cleavage of prohaptoglobin. The cleaving enzyme had an alkaline pH optimum indicating that it was not of lysosomal origin. These results suggest that cleavage of prohaptoglobin occurs in a subcompartment of the ER. Apparently, the connection between this compartment and the bulk of the ER is broken upon saponin treatment or homogenization but can be reestablished through a process requiring GTP hydrolysis.

Stereotypes associated with a low-fat diet and their relevance to nutrition education

Two experiments and one correlational study were conducted to examine the nature and consequences of stereotypes of persons who eat either low-fat or high-fat diets. In Study 1, 132 college students were asked to describe the personal characteristics of a typical male or female peer who was associated with one of three diet characteristics (high-fat diet, low-fat diet, or no diet description). For Study 2, personal characteristics attributed to persons who eat either a low-fat or a high-fat diet that were obtained in Study 1 were converted into rating scales. In the second study, 164 participants were asked to rate one of six target personalities that were created by combining the three diet and two gender conditions (eg, a man who eats high-fat foods). These two studies revealed that both desirable and undesirable personal characteristics are attributed to individuals who eat high-fat diets and to those who eat low-fat diets. Persons eating low-fat diets were described and rated as being self-centered and fastidious students, whereas persons eating high-fat diets were described as being more easy going and more likely to attend parties. However, persons who eat low-fat foods were also described more favorably as being physically fit and attractive. In Study 3, we examined the relationship between stereotypes of persons who eat low-fat diets and reactions to a widely used cancer prevention booklet in a group of 177 undergraduates.(ABSTRACT TRUNCATED AT 250 WORDS)

Racial misclassification of Native Americans in a surveillance, epidemiology, and end results cancer registry

BACKGROUND

The cancer incidence for all sites has been reported to be lower in Native Americans than in White Americans. Concerns have been expressed, however, that the observed low incidence may be a result of inaccurate reporting of race.

PURPOSE

The objective of this study was to investigate the extent to which racial misclassification may contribute to the observed low cancer incidence among Native Americans.

METHODS

A registry of individuals eligible to receive medical services funded by the Indian Health Service was linked by computer to the Puget Sound Surveillance, Epidemiology, and End Results (SEER) cancer registry.

RESULTS

Only 137 (60%) of the patients with invasive cancer registered with the Indian Health Service and for whom race was recorded were identified as Native Americans in the SEER registry. Similarly, 55 (69%) of 80 in situ cervical cancer case patients were classified as Native American. A strong association was observed between Native-American blood quantum level and racial misclassification.

CONCLUSION

The results of this study indicate that the observed low cancer incidence in Native Americans relative to Whites in the northwest United States is at least partially attributable to racial misclassification in the SEER cancer registry.

Biosynthesis of bikunin (urinary trypsin inhibitor) in rat hepatocytes

One of the major sulfated proteins secreted by rat hepatocytes contains a low-sulfated chondroitin sulfate chain and its apparent molecular mass upon sodium dodecyl sulfate/polyacrylamide gel electrophoresis shifts from 40 to 28 kDa upon chondroitinase ABC treatment (E. M. Sjöberg and E. Fries, 1990, Biochem. J. 272, 113-118). These properties suggest that this protein is the rat homologue of the major trypsin inhibitor of human urine which was recently named bikunin. In serum, bikunin occurs mainly as a subunit of the pre-alpha-inhibitor and the inter-alpha-inhibitor; in these proteins it is covalently linked to the other polypeptides through its chondroitin sulfate chain. Bikunin has been shown to be synthesized by liver cells as a 42-kDa precursor, in which it is linked to alpha 1-microglobulin by two basic amino acids. We have isolated bikunin from rat urine and prepared antibodies against it. In rat hepatocytes pulse-labeled with [35S]methionine, these antibodies precipitated a labeled protein of 42 kDa. Upon chase, three different labeled proteins were recognized by the antibodies in the medium: one protein of 40 kDa (free bikunin), one of 125 kDa (presumably pre-alpha-inhibitor), and one greater than 240 kDa (possibly a protein related to the inter-alpha-inhibitor). Pulse-chase experiments with [35S]sulfate showed that these proteins occurred intracellularly as precursors containing alpha 1-microglobulin. These results demonstrate that the completion of the chondroitin sulfate chain and its coupling to other polypeptide chains occur before the cleavage of the alpha 1-microglobulin/bikunin precursor.

Synthesis of alpha 1-microglobulin in cultured rat hepatocytes is stimulated by interleukin-6, leukemia inhibitory factor, dexamethasone and retinoic acid

The secretion of alpha 1-microglobulin by primary cultures of rat hepatocytes was found to increase upon the addition of interleukin-6 or leukemia inhibitory factor, two mediators of acute phase response. This stimulatory effect was further enhanced by dexamethasone. alpha 1-Microglobulin is synthesized as a precursor also containing bikunin, and the precursor protein is cleaved shortly before secretion. Our results therefore suggest that both alpha 1-microglobulin and bikunin are acute phase reactants in rat hepatocytes. Furthermore, we found that retinoic acid, previously shown to be involved in the regulation of cell differentiation and development, also stimulated alpha 1-microglobulin synthesis. Only free, uncomplexed alpha 1-microglobulin (28,000 Da) was detected in the hepatocyte media, suggesting that the complex between alpha 1-microglobulin and alpha 1-inhibitor 3, found in rat serum, is formed outside the hepatocyte.

Accumulation of Golgi-processed secretory proteins in an organelle of high density upon reduction of ATP concentration in rat hepatocytes

We have previously shown that when rat hepatocytes are incubated with 4 mM azide, which reduces the intracellular ATP concentration to about 30% of its normal level, secretory proteins are reversibly arrested within the cell. Analysis of haptoglobin after 150 min of azide incubation shows that its carbohydrates have been processed by Golgi enzymes (Persson, R., Ahlström, E., and Fries, E. (1988) J. Cell Biol. 107, 2503-2510). Here, we have further characterized the site of arrest. Subcellular fractionation by density gradient centrifugation showed that albumin and haptoglobin fractionated like a marker for the endoplasmic reticulum. Localization of albumin by immunoelectron microscopy showed, however, that it occurred in flattened cisternae and that the endoplasmic reticulum was devoid of the protein. A possible explanation for these results is that the azide treatment blocks transport through the Golgi complex, leading to an accumulation of secretory proteins in a pre- or early Golgi compartment of high density. This compartment could contain sufficient amounts of Golgi enzymes to carry out the observed carbohydrate processing upon prolonged incubation or possibly acquire them as an effect of the azide treatment.