Lysosomes in Cancer-At the Crossroad of Good and Evil

Although it has been known for decades that lysosomes are central for degradation and recycling in the cell, their pivotal role as nutrient sensing signaling hubs has recently become of central interest. Since lysosomes are highly dynamic and in constant change regarding content and intracellular position, fusion/fission events allow communication between organelles in the cell, as well as cell-to-cell communication via exocytosis of lysosomal content and release of extracellular vesicles. Lysosomes also mediate different forms of regulated cell death by permeabilization of the lysosomal membrane and release of their content to the cytosol. In cancer cells, lysosomal biogenesis and autophagy are increased to support the increased metabolism and allow growth even under nutrient- and oxygen-poor conditions. Tumor cells also induce exocytosis of lysosomal content to the extracellular space to promote invasion and metastasis. However, due to the enhanced lysosomal function, cancer cells are often more susceptible to lysosomal membrane permeabilization, providing an alternative strategy to induce cell death. This review summarizes the current knowledge of cancer-associated alterations in lysosomal structure and function and illustrates how lysosomal exocytosis and release of extracellular vesicles affect disease progression. We focus on functional differences depending on lysosomal localization and the regulation of intracellular transport, and lastly provide insight how new therapeutic strategies can exploit the power of the lysosome and improve cancer treatment.

Imidacloprid Induces Lysosomal Dysfunction and Cell Death in Human Astrocytes and Fibroblasts-Environmental Implication of a Clinical Case Report

Imidacloprid (IMI), a neonicotinoid insecticide, has potential cytotoxic and genotoxic effects on human and experimental models, respectively. While being an emerging environmental contaminant, occupational exposure and related cellular mechanisms are unknown. Herein, we were motivated by a specific patient case where occupational exposure to an IMI-containing plant protection product was associated with the diagnosis of Bell's palsy. The aim was to investigate the toxic effects and cellular mechanisms of IMI exposure on glial cells (D384 human astrocytes) and on human fibroblasts (AG01518). IMI-treated astrocytes showed a reduction in cell number and dose-dependent cytotoxicity at 24 h. Lower doses of IMI induced reactive oxygen species (ROS) and lysosomal membrane permeabilisation (LMP), causing apoptosis and autophagic dysfunction, while high doses caused significant necrotic cell death. Using normal fibroblasts, we found that IMI-induced autophagic dysfunction and lysosomal damage, activated lysophagy, and resulted in a compensatory increase in lysosomes. In conclusion, the observed IMI-induced effects on human glial cells and fibroblasts provide a possible link between IMI cytotoxicity and neurological complications observed clinically in the patient exposed to this neonicotinoid insecticide.

Screening for Inflammatory Markers Identifies IL-18Rα as a Potential Link between Exenatide and Its Anti-Inflammatory Effect: New Results from the Combat-JUDO Randomized Controlled Trial

INTRODUCTION

Obesity is associated with chronic inflammation. Chronic inflammation has also been linked to insulin resistance and type 2 diabetes, metabolic associated fatty liver disease, and cardiovascular disease. Glucagon-like peptide-1 (GLP-1) receptor analogs (GLP-1RA) are clinically used to treat obesity, with known anti-inflammatory properties. How the GLP-1RA exenatide effects inflammation in adolescents with obesity is not fully investigated.

METHODS

Forty-four patients were randomized to receive weekly subcutaneous injections with either 2 mg exenatide or placebo for 6 months. Plasma samples were collected at baseline and at the end of the study, and 92 inflammatory proteins were measured.

RESULTS

Following treatment with exenatide, 15 out of the 92 proteins were decreased, and one was increased. However, after adjustment for multiple testing, only IL-18Rα was significantly lowered following treatment.

CONCLUSIONS

Weekly injections with 2 mg of exenatide lowers circulating IL-18Rα in adolescents with obesity, which may be a potential link between exenatide and its anti-inflammatory effect in vivo. This contributes to exenatide's pharmaceutical potential as a treatment for obesity beyond weight control and glucose tolerance, and should be further studied mechanistically.

Lysosomal Function and Intracellular Position Determine the Malignant Phenotype in Malignant Melanoma

Lysosomes are central in cell homeostasis and participate in macromolecular degradation, plasma membrane repair, exosome release, cell adhesion/migration, and apoptosis. In cancer, alterations in lysosomal function and spatial distribution may facilitate disease progression. In this study, we show enhanced lysosomal activity in malignant melanoma cells compared with that in normal human melanocytes. Most lysosomes show perinuclear location in melanocytes, while they are more dispersed in melanoma, with retained proteolytic activity and low pH also in the peripheral population. Rab7a expression is lower in melanoma cells than in melanocytes, and by increasing Rab7a, lysosomes are relocated to the perinuclear region in melanoma. Exposure to the lysosome-destabilizing drug L-leucyl-L-leucine methyl ester causes higher damage in the perinuclear subset of lysosomes in melanomas, whereas differences in subpopulation susceptibility cannot be found in melanocytes. Interestingly, melanoma cells recruit the endosomal sorting complex required for transport-III core protein CHMP4B, involved in lysosomal membrane repair, rather than initiate lysophagy. However, when the perinuclear lysosomal position is promoted by Rab7a overexpression or kinesore treatment, lysophagy is increased. In addition, Rab7a overexpression is accompanied by reduced migration capacity. Taken together, the study emphasizes that alterations in lysosomal properties facilitate the malignant phenotype and declares the targeting of lysosomal function as a future therapeutic approach.

Real-Time Monitoring of Lysosomal Membrane Permeabilization Using Acridine Orange

Loss of lysosomal membrane integrity results in leakage of lysosomal hydrolases to the cytosol which might harm cell function and induce cell death. Destabilization of lysosomes often precede apoptotic or necrotic cell death and occur during both physiological and pathological conditions. The weak base acridine orange readily enters cells and accumulates in the acidic environment of lysosomes. Vital staining with acridine orange is a well-proven technique to observe lysosomal destabilization using fluorescence microscopy and flow cytometry. These analyses are, however, time consuming and only adapted for discrete time points, which make them unsuitable for large-scale approaches. Therefore, we have developed a time-saving, high-throughput microplate reader-based method to follow destabilization of the lysosomal membrane in real-time using acridine orange. This protocol can easily be adopted for patient samples since the number of cells per sample is low and the time for analysis is short.

Restoration of lysosomal function after damage is accompanied by recycling of lysosomal membrane proteins

Lysosomes are central organelles for cellular degradation and energy homeostasis. In addition, lysosomal membrane permeabilization (LMP) and subsequent release of lysosomal content to the cytosol can initiate programmed cell death. The extent of LMP and available repair mechanisms determine the cell fate after lysosomal damage. In this study, we aimed to investigate the premises for lysosomal membrane repair after LMP and found that lysosomal membrane damage initiated by L-leucyl-L-leucine methyl ester (LLOMe) caused caspase-dependent apoptosis in almost 50% of the cells, while the rest recovered. Immediately after LLOMe addition, lysosomal proteases were detected in the cytosol and the ESCRT-components ALIX and CHMP4B were recruited to the lysosomal membrane. Next, lysophagic clearance of damaged lysosomes was evident and a concentration-dependent translocation of several lysosomal membrane proteins, including LAMP2, to the cytosol was found. LAMP2 was present in small vesicles with the N-terminal protein chain facing the lumen of the vesicle. We conclude that lysophagic clearance of damaged lysosomes results in generation of lysosomal membrane protein complexes, which constitute small membrane enclosed units, possibly for recycling of lysosomal membrane proteins. These lysosomal membrane complexes enable an efficient regeneration of lysosomes to regain cell functionality.

Extracellular vesicles released by melanocytes after UVA irradiation promote intercellular signaling via miR21

Skin pigmentation is controlled by complex crosstalk between melanocytes and keratinocytes and is primarily induced by exposure to ultraviolet (UV) irradiation. Several aspects of UVA-induced signaling remain to be explored. In skin cells, UVA induces plasma membrane damage, which is repaired by lysosomal exocytosis followed by instant shedding of extracellular vesicles (EVs) from the plasma membrane. The released EVs are taken up by neighboring cells. To elucidate the intercellular crosstalk induced by UVA irradiation, EVs were purified from UVA-exposed melanocytes and added to keratinocytes. Transcriptome analysis of the keratinocytes revealed the activation of TGF-β and IL-6/STAT3 signaling pathways and subsequent upregulation of microRNA (miR)21. EVs induced phosphorylation of ERK and JNK, reduced protein levels of PDCD4 and PTEN, and augment antiapoptotic signaling. Consequently, keratinocyte proliferation and migration were stimulated and UV-induced apoptosis was significantly reduced. Interestingly, melanoma cells and melanoma spheroids also generate increased amounts of EVs with capacity to stimulate proliferation and migration upon UVA. In conclusion, we present a novel intercellular crosstalk mediated by UVA-induced lysosome-derived EVs leading to the activation of proliferation and antiapoptotic signaling via miR21.

Impact of high cholesterol in a Parkinson's disease model: Prevention of lysosomal leakage versus stimulation of α-synuclein aggregation

Parkinson's disease is characterized by accumulation of intraneuronal cytoplasmic inclusions, Lewy bodies, which mainly consist of aggregated α-synuclein. Controversies exist as to whether high blood cholesterol is a risk factor for the development of the disease and whether statin treatment could have a protective effect. Using a model system of BE(2)-M17 neuroblastoma cells treated with the neurotoxin 1-methyl-4-phenylpyridinium (MPP⁺), we found that MPP⁺-induced cell death was accompanied by cholesterol accumulation in a lysosomal-like pattern in pre-apoptotic cells. To study the effects of lysosomal cholesterol accumulation, we increased lysosomal cholesterol through pre-treatment with U18666A and found delayed leakage of lysosomal contents into the cytosol, which reduced cell death. This suggests that increased lysosomal cholesterol is a stress response mechanism to protect lysosomal membrane integrity in response to early apoptotic stress. However, high cholesterol also stimulated the accumulation of α-synuclein. Treatment with the cholesterol-lowering drug lovastatin reduced MPP⁺-induced cell death by inhibiting the production of reactive oxygen species, but did not prevent lysosomal cholesterol increase nor affect α-synuclein accumulation. Our study indicates a dual role of high cholesterol in Parkinson's disease, in which it acts both as a protector against lysosomal membrane permeabilization and as a stimulator of α-synuclein accumulation.

Analysis of Lysosomal pH by Flow Cytometry Using FITC-Dextran Loaded Cells

The acidic environment of the lysosomal lumen provides an optimal milieu for the acid hydrolases and is also essential for fusion/fission of endo-lysosomal compartments and sorting of cargo. Evidence suggests that maintaining lysosomal acidity is essential to avoid disease. In this chapter, we describe a protocol for analyzing the lysosomal pH in cultured cells using the fluorescent probe fluorescein isothiocyanate (FITC)-dextran together with a dual-emission ratiometric technique suitable for flow cytometry. Fluorescence-labeled dextran is endocytosed and accumulated in the lysosomal compartment. FITC shows a pH-dependent variation in fluorescence when analyzed at maximum emission wavelength and no variation when analyzing at the isosbestic point, thereby the ratio can be used to determine the lysosomal pH. A standard curve is obtained by equilibrating intralysosomal pH with extracellular pH using the ionophore nigericin. The protocol also includes information regarding procedures to induce lysosomal alkalinization and lysosomal membrane permeabilization.

Extracellular vesicles are transferred from melanocytes to keratinocytes after UVA irradiation

Ultraviolet (UV) irradiation induces skin pigmentation, which relies on the intercellular crosstalk of melanin between melanocytes to keratinocytes. However, studying the separate effects of UVA and UVB irradiation reveals differences in cellular response. Herein, we show an immediate shedding of extracellular vesicles (EVs) from the plasma membrane when exposing human melanocytes to UVA, but not UVB. The EV-shedding is preceded by UVA-induced plasma membrane damage, which is rapidly repaired by Ca(2+)-dependent lysosomal exocytosis. Using co-cultures of melanocytes and keratinocytes, we show that EVs are preferably endocytosed by keratinocytes. Importantly, EV-formation is prevented by the inhibition of exocytosis and increased lysosomal pH but is not affected by actin and microtubule inhibitors. Melanosome transfer from melanocytes to keratinocytes is equally stimulated by UVA and UVB and depends on a functional cytoskeleton. In conclusion, we show a novel cell response after UVA irradiation, resulting in transfer of lysosome-derived EVs from melanocytes to keratinocytes.

Abstract 173: Proprotein Convertase Subtilisin/Kexin Type 6 is a Key Protease in the Control of Smooth Muscle Cell Function in Vascular Disease

Proprotein convertases (PCSKs) process matrix metalloproteases (MMPs) and cytokines. Apart from PCSK9, the role of these enzymes in vascular disease is largely unknown. Previously, we demonstrated upregulation of PCSK6 in carotid atherosclerosis, primarily localized to smooth muscle cells (SMCs) and positively correlated to inflammation, extracellular matrix remodeling and cytokines. Here, we extended these findings to determine the role of PCSK6 in vascular development and disease. Increased expression of PCSK6 in vascular disease was validated by microarrays from two non-overlapping cohorts of carotid plaques vs. non-atherosclerotic arteries (n=50 patients and n=32 patients, p<0.0001), as well as abdominal (AAA, n=14, p<0.0001) and thoracic aortic aneurysms (TAA, n=244, p=0.012). By eQTL, variants in the PCSK6 gene were found to influence it’s expression in both plaques and aneurysms. Among these, rs6598465 also showed association with maximum progression of carotid intima-media thickness in high-risk coronary artery disease subjects (n=3388, p=0.037). By IHC, PCSK6 localized mainly to SMCs in the fibrous cap and neovessels in atherosclerotic, AAA and TAA tissues. In mouse-, rat-, and human intimal hyperplasia, PCSK6 was expressed in proliferating SMCs. By microarrays, after rat carotid balloon injury there was an early downregulation of PCSK6 followed by an upregulation in later phases during SMC activation, as well as positive correlation to PDGFB and IGF1 (Spearman r>0.7, p<0.0001) and to MMP2 and MMP14 (r>0.5, p<0.0001). In zebrafish embryos, PCSK6 localized to heart and vasculature and its ablation caused defective peripheral vascular patterning with cerebral and myocardial hemorrhage. PCSK6 -/- mice did not present an obvious vascular phenotype but showed reduced intimal hyperplasia compared to wild-type mice after carotid artery ligation (p=0.015). In vitro, PCSK6 overexpression markedly increased SMC migration upon PDGFBB stimulation (p<0.0001). The present study establishes PCSK6 as a key modulator of SMC function in vascular disease and demonstrates a functional link between PCSK6 expression and SMC migration in vascular remodeling.

What Protects Youths From Externalising and Internalising Problems? A Critical Review of Research Findings and Implications for Practice

Problems in childhood and adolescence, such as pronounced externalising and internalising problems, are associated with a relatively high risk for long-lasting psychosocial difficulties. Therefore, it is essential to understand what protects youth from externalising and internalising problems. The present article has three purposes: (1) To review previous research reviews concerning which factors that have been identified as protecting youth from externalising and internalising problems, (2) to identify and suggest key areas of focus for future research, and (3) to discuss implications of this knowledge for practice. From the 29 included reviews, it can be concluded that an extensive list of factors have been identified as being potentially protective in youths. These factors exist in the individual and the family, as well as outside the family. However, from this review of reviews, it is also evident that many important questions remain unanswered. Answers to these questions would help make interventions for youths at risk more effective. How to use the existing research results concerning protective factors in guidance and counselling with youths is discussed.

Sunbathing: What've lysosomes got to do with it?

Solar radiation is an important risk factor for skin cancer, the incidence of which is increasing, especially in the fair-skinned populations of the world. While the ultraviolet (UV)B component has direct DNA damaging ability, UVA-induced effects are currently mainly attributed to the production of reactive oxygen species. In our recent study, we compared the effects of UVA and UVB radiation on human keratinocytes and found that UVA-induced plasma membrane damage was rapidly repaired by lysosomal exocytosis, which was detected based on the expression of lysosomal membrane associated protein-1 (LAMP-1) on the plasma membrane of non-permeabilized cells. Later, the keratinocytes died through caspase-8 mediated apoptosis. In contrast, the plasma membranes of keratinocytes exposed to UVB showed no LAMP-1 expression, and, although the cells died by apoptosis, no initial caspase-8 activity was detected. We have also demonstrated the occurrence of UVA-induced lysosomal exocytosis in reconstructed skin and shown the relocation of lysosomes from the center of cells to the vicinity of the plasma membrane. Thus, we suggest that lysosomal exocytosis also occurs in keratinocytes covered by the stratum corneum following exposure to UVA. Our findings provide new insight into the mechanism of UVA-induced skin damage.

Lysosomal exocytosis and caspase-8-mediated apoptosis in UVA-irradiated keratinocytes

Ultraviolet (UV) irradiation is a major environmental carcinogen involved in the development of skin cancer. To elucidate the initial signaling during UV-induced damage in human keratinocytes, we investigated lysosomal exocytosis and apoptosis induction. UVA, but not UVB, induced plasma membrane damage, which was repaired by Ca(2+)-dependent lysosomal exocytosis. The lysosomal exocytosis resulted in extracellular release of cathepsin D and acid sphingomyelinase (aSMase). Two hours after UVA irradiation, we detected activation of caspase-8, which was reduced by addition of anti-aSMAse. Furthermore, caspase-8 activation and apoptosis was reduced by prevention of endocytosis and by the use of cathepsin inhibitors. We conclude that lysosomal exocytosis is part of the keratinocyte response to UVA and is followed by cathepsin-dependent activation of caspase-8. The findings have implications for the understanding of UV-induced skin damage and emphasize that UVA and UVB initiate apoptosis through different signaling pathways in keratinocytes.

Quantification of kinetic changes in protein tyrosine phosphorylation and cytosolic Ca2+ concentration in boar spermatozoa during cryopreservation

Protein tyrosine phosphorylation in sperm is associated with capacitation in several mammalian species. Although tyrosine phosphorylated proteins have been demonstrated in cryopreserved sperm, indicating capacitation-like changes during cryopreservation, these changes have not yet been quantified objectively. We monitored tyrosine phosphorylation, intracellular calcium and sperm kinematics throughout the cryopreservation process, and studied the relationships among them in boar spermatozoa. Sperm kinetics changed significantly during cryopreservation: curvilinear velocity, average path velocity and straight line velocity all decreased significantly (P < 0.05). While the percentage of sperm with high intracellular calcium declined (P < 0.05), global phosphorylation increased significantly (P < 0.01). Specifically, cooling to 5°C induced phosphorylation in the spermatozoa. After cooling, a 32-kDa protein not observed in fresh semen appeared and was consistently present throughout the cryopreservation process. While the level of expression of this phosphoprotein decreased after addition of the second extender, frozen–thawed spermatozoa showed an increased expression. The proportion of sperm cells with phosphorylation in the acrosomal area also increased significantly (P < 0.05) during cryopreservation, indicating that phosphorylation might be associated with capacitation-like changes. These results provide the first quantitative evidence of dynamic changes in the subpopulation of boar spermatozoa undergoing tyrosine phosphorylation during cryopreservation.

TNF-α-stimulated macrophages protect A549 lung cells against iron and oxidation

Previously, we have shown that TNF-α protects iron-exposed J774 macrophages against iron-catalyzed oxidative lysosomal disruption and cell death by increasing reduced glutathione and H-ferritin in cells. Because J774 cells are able to harbor large amounts of iron, which is potentially harmful in a redox-active state, we hypothesized that TNF-α-stimulated J774 macrophages will prevent iron-driven oxidative killing of alveolar epithelial A549 cells in co-culture. In the present study, iron trichloride (which is endocytosed by cells as hydrated iron-phosphate complexes) was mainly deposited inside the lysosomes of J774 macrophages, while A549 cells, equally iron exposed, accumulated much less iron. When challenged by oxidants, however, reactive lysosomal iron in A549 cells promoted lysosomal disruption and cell death, particularly in the presence of TNF-α. This effect resulted from an elevation in ROS generation by TNF-α, while a compensatory upregulation of protective molecules (H-ferritin and/or reduced glutathione) by TNF-α was absent. A549 cell death was particularly pronounced when iron and TNF-α were present in the conditioned medium during oxidant challenge; thus, iron-driven oxidative reactions in the culture medium were a much greater hazard to A549 cells than those taking place inside their lysosomes. Consequently, the iron chelator, deferoxamine, efficiently prevented A549 cell death when added to the culture medium during an oxidant challenge. In co-cultures of TNF-α-stimulated lung cells, J774 macrophages sequestered iron inside their lysosomes and protected A549 cells from oxidative reactions and cell death. Thus, the collective effect of TNF-α on co-cultured lung cells was mainly cytoprotective.

Determination of the detective quantum efficiency of gamma camera systems: a Monte Carlo study

The purpose of the present work was to investigate the validity of using the Monte Carlo technique for determining the detective quantum efficiency (DQE) of a gamma camera system and to use this technique in investigating the DQE behaviour of a gamma camera system and its dependency on a number of relevant parameters. The Monte Carlo-based software SIMIND, simulating a complete gamma camera system, was used in the present study. The modulation transfer function (MTF) of the system was determined from simulated images of a point source of (99m)Tc, positioned at different depths in a water phantom. Simulations were performed using different collimators and energy windows. The MTF of the system was combined with the photon yield and the sensitivity, obtained from the simulations, to form the frequency-dependent DQE of the system. As figure-of-merit (FOM), the integral of the 2D DQE was used. The simulated DQE curves agreed well with published data. As expected, there was a strong dependency of the shape and magnitude of the DQE curve on the collimator, energy window and imaging position. The highest FOM was obtained for a lower energy threshold of 127 keV for objects close to the detector and 131 keV for objects deeper in the phantom, supporting an asymmetric window setting to reduce scatter. The Monte Carlo software SIMIND can be used to determine the DQE of a gamma camera system from a simulated point source alone. The optimal DQE results in the present study were obtained for parameter settings close to the clinically used settings.

Microbiological evaluation of a commercial transport system for urine samples

The aim of this study was to evaluate a commercial tube prepared with boric acid, sodium formate and sorbitol (Hemogard Vacutainer tubes, Becton-Dickinson, HG tubes). Fourteen bacterial strains were incubated in urine in HG tubes and conventional tubes. During a 24-h period, most of the microorganisms grew readily in conventional tubes at room temperature, whereas the bacterial counts were comparatively unchanged when chilled or kept in HG tubes. The bacterial counts of Alcaligenes faecalis and lactobacilli decreased by two 10 logarithms in the HG tubes, at room temperature. Experiments were also performed with the addition of various antibiotics. Ciprofloxacin caused a decrease in E. coli counts regardless of type of tube used, while the HG tubes and the conventional tubes kept chilled conserved bacterial counts upon challenge with fosfomycin, trimethoprim or mecillinam. Bedside cultures from 154 outpatients were sampled and divided into three tubes. One conventional tube was sent to our laboratory by ordinary chilled transport. Another conventional tube and one HG tube were transported to the laboratory without chilling. Cultures were performed upon arrival at the laboratory and then 24, 48 and 72 h after primary sampling. Within 24 h of sampling, no significant differences in bacterial counts were observed between chilled conventional tubes and the HG tubes at room temperature. However, in the HG tubes a significant change in enterococcal counts was noted within 48 h.

Self-rated health. Comparisons between three different measures. Results from a population study

BACKGROUND

Self-rating of health is among the most frequently assessed health perceptions in epidemiological research. The aim of this study was to compare different measures of global self-rated health (SRH) with respect to differences in age and sex groups and relations to hypothesized determinants.

METHOD

Three single-question measures of SRH were included in a health questionnaire administered to 8200 randomly chosen men and women. Two SRH measures were non-comparative, one with seven (SRH-7) and one with five response options (SRH-5), while the third measure included a comparison with others of the same age (SRH-age). SRH-7 had specified response options only at the ends of the scale, while the other two measures gave specified statements for each option. Comparisons between the SRH assessments were studied with respect to response frequencies, frequency distributions, age and gender differences and differences in associations with hypothesized determinants.

RESULTS

The differences between the SRH measures were in most cases marginal. Some diversities may, however, be worth considering: a high drop-out rate for the SRH-7 measure in the oldest age group; a trend that SRH-7 correlated most strongly with the independent variables; SRH-age showed improved health ratings with increasing age but a less skewed frequency distribution compared to the non-comparative measures.

CONCLUSIONS

The results imply that non-comparative measures are more appropriate in longitudinal studies and that measures without specified response options might be less suitable for an older study group. The overall impression is, however, that the different measures represents parallel assessments of subjective health.

Gastric cancer and human leukocyte antigen: distinct DQ and DR alleles are associated with development of gastric cancer and infection by Helicobacter pylori

DNA and sera from 130 cases of gastric cancer and 263 population-based controls were analyzed to study the association of HLA class II DR-DQ alleles with Helicobacter pylori (Hp) infection and the risk for gastric cancer. Presence of the DQA1*0102 allele was inversely and significantly associated with Hp seropositivity (P = 2 x 10(-5)), which is an independent replication of previous findings. However, this inverse relationship with Hp did not correspond with a reduced risk of gastric cancer. At the DRB1 locus, the *1601 allele was significantly associated with an increased gastric cancer risk with an odds ratio (95% confidence interval) of 8.7 (range, 2.7-28.0). The effect of *1601 was more pronounced among Hp-negative subjects, and the association was stronger with the diffuse, rather than with the intestinal, histological type of gastric cancer. Because none of the HLA alleles were associated with both Hp infection and gastric cancer, the HLA DR-DQ alleles are linked with gastric cancer risk through other mechanisms than an increased susceptibility to Hp infection.

Defective heparan sulfate biosynthesis and neonatal lethality in mice lacking N-deacetylase/N-sulfotransferase-1

Heparan sulfate is a sulfated polysaccharide present on most cell surfaces and in the extracellular matrix. In vivo functions of heparan sulfate can be studied in mouse strains lacking enzymes involved in the biosynthesis of heparan sulfate. Glucosaminyl N-deacetylase/N-sulfotransferase (NDST) catalyzes the first modifying step in the biosynthesis of the polysaccharide. This bifunctional enzyme occurs in several isoforms. We here report that targeted gene disruption of NDST-1 in the mouse results in a structural alteration of heparan sulfate in most basement membranes as revealed by immunohistochemical staining of fetal tissue sections using antibodies raised against heparan sulfate. Biochemical analysis of heparan sulfate purified from fibroblast cultures, lung, and liver of NDST-1-deficient embryos demonstrated a dramatic reduction in N-sulfate content. Most NDST-1-deficient embryos survive until birth; however, they turn out to be cyanotic and die neonatally in a condition resembling respiratory distress syndrome. In addition, a minor proportion of NDST-1-deficient embryos die during the embryonic period. The cause of the embryonic lethality is still obscure, but incompletely penetrant defects of the skull and the eyes have been observed.

Overexpression of different isoforms of glucosaminyl N-deacetylase/N-sulfotransferase results in distinct heparan sulfate N-sulfation patterns

Functional interactions of heparan sulfate (HS) with selected proteins depend on distinct saccharide sequences which are generated during biosynthesis of the polysaccharide. Glucosaminyl N-deacetylase/N-sulfotransferases (NDSTs) catalyze both the N-deacetylation and N-sulfation reactions that initiate the modification of the (GlcNAc-GlcA)(n) polysaccharide backbone. The N-acetyl/N-sulfate exchange is restricted to certain regions of the polysaccharide chains, and only these can be further modified by glucuronyl C5-epimerization and O-sulfation at various positions. To investigate whether NDST isoforms influenced differently the structure of HS, murine NDST-1 was overexpressed in human kidney 293 cells, and the structure of the HS produced was compared to HS from NDST-2 overexpressing cells [Cheung, W. F., Eriksson, I., Kusche-Gullberg M., Lindahl, U., and Kjellén, L. (1996) Biochemistry 35, 5250-5256]. The level of N-sulfation increased from 40% in control cells to 60% and 80%, respectively, in NDST-1 and NDST-2 transfected cells. Interestingly, the increase in N-sulfation was accompanied by an increased chain length, while no effect on IdoA content or O-sulfation was seen. The most extended N-sulfated domains were found in HS synthesized by NDST-2 transfected cells. Since both the N-deacetylase and the N-sulfotransferase activities were lower in these cells than in the NDST-1 overexpressing cells, we conclude that, in addition to the level of enzyme expression, the NDST isoform also is important in determining the N-sulfation pattern in HS.

Minimally invasive treatment of infection staghorn stones with shock wave lithotripsy and chemolysis

We report the results in 118 patients with infection staghorn stones treated with an anaesthesia-free minimally invasive method that combined repeated shock-wave lithotripsy (SWL) sessions (unmodified Dornier HM3 lithotripter) and percutaneous chemolysis with Renacidin. The stone-free rate was 60%. In 27 consecutive patients with infection staghorn stones representative of patients with this stone type in the population, a stone-free rate of 77% was recorded. The latter figure is comparable with results reported for open surgery, percutaneous surgery and sandwich therapy, and superior to that recorded with SWL alone. During the study period, no patient referred to us with an infection staghorn stone was treated with percutaneous, ureteroscopic or open surgery, and all treatments were carried out without regional or general anaesthesia. The described treatment concept had a very low complication rate, but required a fairly long hospital stay, with a mean of 32 days (range: 5-82). The long period necessary for completing the treatment in the most complicated cases might render the procedure less attractive as a standard method, but it is nevertheless an excellent option in high-risk patients and in all those patients in whom other procedures are impossible.

Abnormal mast cells in mice deficient in a heparin-synthesizing enzyme

Heparin is a sulphated polysaccharide, synthesized exclusively by connective-tissue-type mast cells and stored in the secretory granules in complex with histamine and various mast-cell proteases. Although heparin has long been used as an antithrombotic drug, endogenous heparin is not present in the blood, so it cannot have a physiological role in regulating blood coagulation. The biosynthesis of heparin involves a series of enzymatic reactions, including sulphation at various positions. The initial modification step, catalysed by the enzyme glucosaminyl N-deacetylase/N-sulphotransferase-2, NDST-2, is essential for the subsequent reactions. Here we report that mice carrying a targeted disruption of the gene encoding NDST-2 are unable to synthesize sulphated heparin. These NDST-2-deficient mice are viable and fertile but have fewer connective-tissue-type mast cells; these cells have an altered morphology and contain severely reduced amounts of histamine and mast-cell proteases. Our results indicate that one site of physiological action for heparin could be inside connective-tissue-type mast cells, where its absence results in severe defects in the secretory granules.

High resolution genetic typing of the class II HLA-DRB1 locus using group-specific amplification and SSO-hybridisation in microplates

The HLA-DRB1 locus is one of the most polymorphic HLA class II loci and rapid and accurate typing of this polymorphism is important both in bone-marrow transplantation, analysis of disease association and in forensic medicine. The allelic variation at DRB1 is characterized by combinations of a limited number of amino-acid motifs, reducing the resolution of a typing strategy based on a single PCR and subsequent analysis of polymorphic motifs. In the present paper we describe a strategy for typing of DRB1 based on eight allele-specific PCRs followed by sandwich hybridization to immobilized probes in a microplate format. The combined approach results in a rapid typing system with very high resolution. Using a rapid DNA extraction protocol, a complete HLA-DRB1 typing can be performed in less than a day.

An experimental head restraint concept for primary prevention of head and neck injuries in frontal collisions

The Experimental Head Restraint Concept (EHRC), a 'safety belt' for the head, is designed to reduce forces to the head and neck, in frontal car crashes. The EHRC was evaluated experimentally in frontal collision for a crash severity of 11 m/s, and numerically in frontal collision for a crash severity of 11 and 15 m/s. Experimental data obtained from a frontal barrier test (11 m/s) showed a 67% reduction of the HIC value from 411 (without EHRC) to 136 (with EHRC). The same level of reduction was also obtained for the higher speed in the numerical simulation. The moment in the neck was shown in experimental configuration to increase a few percent using the EHRC, but as presented in a numerical analysis, the moment was reduced by stiffening the EHRC. The EHRC clearly has a potential role in the search for primary prevention of neurotrauma injuries in frontal related car crashes. However, there is a strong need for more advanced injury criteria for the neck in order to optimize such complex safety systems.

Identification and expression in mouse of two heparan sulfate glucosaminyl N-deacetylase/N-sulfotransferase genes

The biosynthesis of heparan sulfate/heparin is a complex process that requires the coordinate action of a number of different enzymes. In close connection with polymerization of the polysaccharide chain, the modification reactions are initiated by N-deacetylation followed by N-sulfation of N-acetylglucosamine units. These two reactions are carried out by a single protein. Proteins with such dual activities were first purified and cloned from rat liver and mouse mastocytoma. The mouse mastocytoma enzyme is encoded by an approximately 4-kilobase (kb) mRNA, whereas the rat liver transcript contains approximately 8 kb. In the present study, the primary structure of the enzyme encoded by the mouse 8-kb transcript is described. It is demonstrated that both the 4-and 8-kb transcripts have a wide tissue distribution and that they are encoded by separate genes. Characterization of the gene encoding the 4-kb transcript demonstrates that it spans a region of about 8 kb and that it contains at least 14 exons. The similarity of this gene and the previously characterized human gene for the 8-kb transcript is discussed.

Mitochondrial sequence variants in patients with schizophrenia

To investigate whether mitochondrial mutations underly susceptibility to schizophrenia, we sequenced the mtDNAs of two unrelated Swedish patients with schizophrenia and low cytochrome oxidase activity and two maternally related Scottish patients from a family with suspected maternal inheritance of the disease. We found five substitutions in coding regions that have not previously been described as polymorphisms. These new substitutions were studied in 81 schizophrenic patients and five control groups from Sweden and Scotland and found to differ in frequency between populations, emphasizing the importance of using large and well-defined control materials for evaluating the association of mtDNA mutations with disease. The results do not lend strong support to the association of a particular mtDNA substitution with increased risk for schizophrenia. However, the trend towards a higher frequency of substitutions in the patients deserves further attention.

Detection of serum interferon-alpha by dissociation-enhanced lanthanide fluoroimmunoassay. Studies of patients with acute viral and bacterial infections

A sensitive dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA) was evaluated for ability to detect interferon-alpha (IFN-alpha) in serum of patients with acute infectious disease of less than one week's duration and a fever of > 38 degrees C. None of 36 patients with confirmed or probable bacterial disease was IFN-alpha positive. In contrast, 13/26 patients with viral infections had detectable levels of IFN-alpha in serum, all clearly positive (> or = 10 U/ml). The IFN-alpha positive serum samples were obtained early after onset of clinical disease, after a mean of 2.4 days. The IFN-alpha positive samples were obtained from 10 of the 12 patients with influenza or flu-like infection, and 3 of the 5 patients with varicella or herpes zoster. The IFN-alpha negative patients with viral disease (n = 9) included five patients with mononucleosis. The DELFIA should be useful in further studies of the value of IFN-alpha determinations in the identification of acute viral infections.

Mouse mastocytoma cells synthesize undersulfated heparin and chondroitin sulfate in the presence of brefeldin A

In order to study the subcellular localization and organization of the enzymes involved in the glycosylation of the hybrid proteoglycan serglycin, mouse mastocytoma cells were metabolically labeled with [35S]sulfate or [3H]glucosamine in the absence or presence of brefeldin A. This drug is known to induce a disassembly of the proximal part of the Golgi complex, resulting in a redistribution of cis-, medial-, and trans-Golgi resident enzymes back to the endoplasmic reticulum, and to block the anterograde transport of proteins to the trans-Golgi network. Although the total incorporation of [3H]glucosamine into glycosaminoglycan chains was reduced to about 25% in brefeldin A-treated cells compared to control cells, both control cells and cells treated with brefeldin A synthesized heparin as well as chondroitin sulfate chains. Therefore, enzymes involved in the biosynthesis of both types of glycosaminoglycan chains seem to be present proximal to the trans-Golgi network in these cells. Chondroitin sulfate and heparin synthesized in cells exposed to brefeldin A were undersulfated, as demonstrated by ion-exchange chromatography, compositional analyses of disaccharides, as well as by a lower [35S]sulfate/[3H]glucosamine ratio compared to controls. In heparin biosynthesis, both N- and O-sulfation reactions were impaired, with a larger relative decrease in 2-O-sulfation than in 6-O-sulfation. Despite undersulfation, the heparin chains synthesized in the presence of brefeldin A were larger (30 kDa) than the heparin synthesized by control cells (20 kDa). The reduced [3H]glucosamine incorporation in brefeldin A-treated cells was partly due to decreased number of glycosaminoglycan chains synthesized, but also to the biosynthesis of chondroitin sulfate chains of smaller molecular size (8 versus 15 kDa in control cells). Brefeldin A had no effect on the glycosaminoglycan synthesis when used in a cell-free, microsomal fraction, indicating that brefeldin A does not interfere directly with the enzymes involved in the biosynthesis of glycosaminoglycans.

Idiotype-specific T lymphocytes in monoclonal gammopathies: evidence for the presence of CD4+ and CD8+ subsets

Tumour-specific CD4+ T helper (Th) and CD8+ T cytotoxic (Tc) cells may participate in the control and eradication of tumour cells. In the present study, idiotype-specific stimulation of CD4+ and CD8+ blood T cells from patients with monoclonal gammopathy of undetermined significance and patients with untreated multiple myeloma stage I was examined. Activation was measured in the CD4+ and CD8+ subsets enriched by magnetic microbeads as the incorporation of 3H-thymidine and the secretion of interferon (IFN)-gamma, interleukin (IL)-2 and IL-4 by single cells using the enzyme-linked immunospot assay. Idiotype-specific T cells were found in four of seven patients. Stimulation was mainly confined to the CD4+ subset in three of the four responding patients. This type of response was major histocompatibility complex (MHC) class II restricted as it could be inhibited by monoclonal antibodies against MHC class II (HLA-DR), but not against class I (HLA-ABC) molecules. Idiotype-specific CD8+ T cells were also demonstrated in these patients although at a lower frequency. One patient showed a strong and dominating activation of CD8+ T cells which could be blocked by antibodies against HLA-ABC but not against HLA-DR. Idiotype-specific CD4+ or CD8+ T cells were mainly of the type-1 subsets as judged by their secretion of IFN-gamma and IL-2. Thus, this study provides evidence for the presence of idiotype-specific and MHC-restricted CD4+ and CD8+ T cells of the type-1 subsets in patients with monoclonal gammopathies. Such T cells with the potential to control the growth of tumour B cells may be a suitable target for immunotherapeutic interventions in patients.

Human brain contains high levels of heteroplasmy in the noncoding regions of mitochondrial DNA

We have analyzed the level of intraindividual sequence variability (heteroplasmy) of mtDNA in human brain by denaturing gradient gel electrophoresis and sequencing. Single base substitutions, as well as insertions or deletions of single bases, were numerous in the noncoding control region (D-loop), and 35-45% of the molecules from a single tissue showed sequence differences. By contrast, heteroplasmy in coding regions was not detected. The lower level of heteroplasmy in the coding regions is indicative of selection against deleterious mutations. Similar levels of heteroplasmy were found in two brain regions from the same individual, while no heteroplasmy was detected in blood. Thus, heteroplasmy seems to be more frequent in nonmitotic tissues. We observed a 7.7-fold increase in the frequency of deletions/insertions and a 2.2-fold increase in the overall frequency of heteroplasmic mutations in two individuals aged 96 and 99, relative to an individual aged 28. Our results show that intraindividual sequence variability occurs at a high frequency in the noncoding regions of normal human brain and indicate that small insertions and deletions might accumulate with age at a lower rate than large rearrangements.

Composite polytetrafluroethylene/vein bypass grafts: conventional distal vein segment or vein cuff?

OBJECTIVES

To determine the current status of PTFE vein composite grafts, we reviewed our experience with 205 composite reconstructions and compared the results of conventional distal vein segment to that of distal vein cuff.

DESIGN

Retrospective review.

SETTING

Department of Surgery, University Hospital.

PATIENTS AND METHODS

The series included 85 women and 102 men with a median age of 70. The indications for surgery were claudication in 30, rest pain in 71 and ulcer/gangrene in 103. The site of the distal anastomosis was the popliteal artery in 111 and crural artery in 94. The graft consisted of a proximal PTFE graft anastomosed to a distal segment of reversed saphenous vein in 169 or to a modified distal Miller cuff in 36 operations after 1992.

RESULTS

Cumulative life table primary patency rates for the whole series at 12, 24 and 36 months were 39%, 32% and 25% respectively. Limbs with good run-off demonstrated significantly better patency rates compared to limbs with poor run-off (55% and 17% at 12 months, 35% and 11% at 36 months, p = 0.04). The patency rate of femorocrural grafts with poor run-off was only 4% at 12 months. The overall limb salvage rates at 12 and 36 months were 63% and 55%, respectively. Similar results were obtained in limbs with distal reversed vein segment and distal vein cuff.

CONCLUSION

The results of this study suggest that for infrainguinal bypass grafting where the saphenous vein is unavailable, a composite PTFE-vein graft might be an acceptable alternative in limbs with good run-off. Although not a randomised study, the results using a distal reversed vein segment of a cuff were similar.

Effects of terbuthylazine on soil fauna and decomposition processes

Acute lethal and sublethal effects of terbuthylazine and the commercial herbicide preparation Gardoprim [terbuthylazine is the active ingredient (a.i.)] on soil organisms (microbes, oppioid mites, two gamasid mite species, enchytraeids, and nematodes) were studied. In the humus soil terbuthylazine had no toxic effects on soil animals tested. However, the herbicide preparation had acute toxic effects on enchytraeids [no-observed-effect level (NOEL) 1.0 g a.i. /m2] and both gamasid mites (NOEL 2.4 and 5.0 g a.i./m2). According to filter paper test, the LC50 value for oppioid mites was 14.5 g a. i./m2. In the humus soil the commercial preparation caused no dose-related mortality in Oppioidea. The preparation was more toxic to gamasid mites when the herbicide was applied on the soil surface compared to the treatment in which the chemical was mixed into the humus. Application method of the chemical did not affect the mortality of enchytraeids. In the multispecies experiment, the number of nematodes was higher in the highest concentration of the commercial preparation (50 g a.i./m2) compared to the lowest concentration (1 g a.i./m2) and the clean soil. The amount of NH+4-N in the humus tended to increase with increasing herbicide concentration. The herbicide did not affect soil respiration, microbial biomass, or water content of the humus. These results indicated that herbicides can have direct effects on soil fauna. Due to species-specific foraging strategies or different exposure routes and rates to animals, effects of herbicides on soil animals varied considerably. Single-species toxicity tests performed in humus soil were more sensitive to the effects of herbicide than ecologically relatively short-term multispecies test.

Expression of the mouse mastocytoma glucosaminyl N-deacetylase/ N-sulfotransferase in human kidney 293 cells results in increased N-sulfation of heparan sulfate

The biosynthesis of heparin and heparan sulfate involves a series of polymer-modification reactions that is initiated by N-deacetylation and subsequent N-sulfation of N-acetylglucosamine residues. These reactions are catalysed by a combined N-deacetylase/N-sulfotransferase. Proteins expressing both activities have previously been purified from mouse mastocytoma, which generates heparin, and from rat liver, which produces heparan sulfate. In the present study, the mouse mastocytoma enzyme has been expressed in the human kidney cell line, 293, to investigate whether it could promote modification of the endogenous heparan sulfate precursor polysaccharide into a heparan-like molecule. The N-deacetylase activity of the stably transfected cell clones as approximately 8-fold higher, on a cell-protein basis, than that of control cells, while the N-sulfotransferase activity was increased approximately 2.5 fold. The amounts of glycosaminoglycans synthesized were the same in control and transfected cells, measured as incorporation of [3H]-glucosamine, whereas 35S-labeled glycosaminoglycans were approximately 50% increased in transfected cells, with an increased relative content of heparin sulfate. Structural analysis demonstrated the the glucosamine units of the "heparan sulfate" from transfected cells were almost exclusively N-sulfated, as expected for heparin, whereas more than half of the glucosamine units of the control polysaccharide remained N-acetylated. Notably, the increased N-sulfation was not accompanied by increased O-sulfation, not by C-5 epimerization of D-glucuronic to L-iduronic acid units. The implications of these findings are discussed with regard to the regulation of the biosynthetic process.

Structural features of an arabinan fragment isolated from the water-soluble fraction of dehulled rapeseed

A water-soluble polysaccharide fraction was prepared from dehulled rapeseed meal (winter rapeseed variety Casino). Further purification yielded two major fractions having a high content of arabinose and galactose residues, with Ara/Gal ratios of 5.4 (G1) and 1.8 (G2). The Ara/Gal ratio of the high molecular weight fraction G1 was stable over the whole gel filtration peak, indicating that the arabinose and galactose residues are part of the same polysaccharide. The high molecular weight fraction G1 was studied further by methylation analysis and several NMR techniques. Structural studies showed G1 to consist mainly of arabian fragments, which have terminal alpha-L-arabinofuranosyl groups with anomeric carbons bound (1-->5) (A) or (1-->2) (B), and 2,5-substituted arabinosyl residues with anomeric carbons bound (1-->5) (D) or (1-->2) (C) to adjacent arabinosyl residues. The A:B:C:D ratios were 2:1:1:1 according to results from NMR and methylation analysis.

Heparin proteoglycans synthesized by mouse mastocytoma contain chondroitin sulphate

Proteoglycans (PGs), biosynthetically labelled with [35S]sulphate, were isolated from mouse mastocytoma tissue. Chromatography on antithrombin (AT)-Sepharose resulted in the separation of the 35S-labelled PGs into three fractions: PGs with no affinity for the gel (NA-PGs), PGs with low affinity (LA-PGs), and PGs with high affinity (HA-PGs) for antithrombin. Whereas NA-PGs contained almost exclusively chondroitin sulphate (CS), the AT-binding PGs contained 80-85% heparin and 15-20% CS. [35S]CS-containing macromolecules obtained from the HA-PG fraction after removal of the heparin polysaccharide chains were rechromatographed on AT-Sepharose. A majority of these 35S-labelled macromolecules no longer showed affinity for AT. These experiments indicate that the [35S]CS recovered in the AT-binding PGs is present in hybrid PGs. Polysaccharide chain-length determination demonstrated that the heparin chains were somewhat larger (M(r) approximately 30,000) than the CS chains in the NA-PGs (M(r) approximately 25,000). CS chains in the hybrid PGs were slightly smaller (M(r) approximately 20,000). Characterization of the sulphated CS disaccharides from NA- and HA-PGs showed that they contained similar amounts (20%) of disulphated disaccharides of [GlcA-GalNAc(4,6-di-OSO3)] type. The monosulphated CS-disaccharides were O-sulphated at C-4 of the galactosamine units. Analysis by gel chromatography of the [35S]CS components isolated from HA-PGs after heparinase treatment showed that a major portion of these contained one CS chain only. Calculations of the number of CS and heparin chains in AT-binding PGs, based on polysaccharide composition and polysaccharide chain length, indicate that all heparin-containing PGs are hybrids.

Decreased cytochrome-c oxidase activity and lack of age-related accumulation of mitochondrial DNA deletions in the brains of schizophrenics

Defects in mitochondrial energy production have been implicated in several neurodegenerative disorders, such as Parkinson disease and amyotrophic lateral sclerosis. To study the contribution of mitochondrial defects to Alzheimer disease and schizophrenia, cytochrome-c oxidase (COX) activity and levels of the mtDNA4977 deletion in postmortem brain tissue specimens of patients were compared with those of asymptomatic age-matched controls. No difference in COX activity was observed between Alzheimer patients and controls in any of five brain regions investigated. In contrast, schizophrenic patients had a 63% reduction of the COX activity in the nucleus caudatus (P < 0.0001) and a 43% reduction in the cortex gyrus frontalis (P < 0.05) as compared to controls. The average levels of the mtDNA4977 deletion did not differ significantly between Alzheimer patients and controls, and the deletion followed similar modes of accumulation with age in the two groups. In contrast, no age-related accumulation of mtDNA deletions was found in schizophrenic patients. The reduction in COX activity in schizophrenic patients did not correlate with changes in the total amount of mtDNA or levels of the mtDNA4977 deletion. The lack of age-related accumulation of the mtDNA4977 deletion and reduction in COX activity suggest that a mitochondrial dysfunction may be involved in the pathogenesis of schizophrenia.

Retrospective analysis of the efficacy of cefotaxime sodium dosed twice daily. The Swedish experience

In a Swedish multicenter, comparative, retrospective study, patients with different types of infections--bacteremia-septicemia, genitourinary, intra-abdominal, central nervous system, and lower respiratory tract infections--were randomly selected from the hospital records. Patients treated with cefotaxime twice or three times a day as monotherapy (excluding metronidazole) for at least 1 day (240 cases) were analyzed in terms of clinical and bacteriologic outcome, these results were correlated with the dosing regimen. Similarly high success rates (cure and improvement) at hospital discharge were observed in both group initially treated with cefotaxime 1 g twice daily and 2 g twice daily (97 and 96%, respectively). A total of 73% of patients were initially treated with cefotaxime for only 3 days at most before changing to a lower dose regimen, an alternate intravenous treatment, or oral drug follow-up. Clinical evaluation at hospital discharge revealed a clinical success rate between 87 and 100%, depending on the type of infection.

Biosynthesis of heparin. Different molecular forms of O-sulfotransferases

O-Sulfotransferases involved in heparin biosynthesis were purified > or = 10,000-fold from detergent extracts of mouse mastocytoma tissue by sequential chromatographies on DEAE-Sephacel, heparin-agarose, blue Sepharose, and 3',5'-ADP-Sepharose. The resultant preparation catalyzed the transfer of 35S from 3'-phosphoadenosyl-5'-phospho-[35S]sulfate into N,O-desulfated, re-N-sulfated heparin. Anion-exchange high performance liquid chromatography of disaccharides obtained by deaminative cleavage of the 35S-labeled polysaccharide product revealed O-35S-sulfation at C-2 of L-iduronic acid and at C-6 of D-glucosamine units. SDS-polyacrylamide gel electrophoresis of semipurified enzyme followed by extraction of gel segments and renaturation of proteins consistently showed two distinct fractions of O-sulfotransferase activity, corresponding to proteins of approximately 20 and approximately 60 kDa. The approximately 60-kDa enzyme(s) catalyzed both the 2-O- and 6-O-sulfotransferase reactions, whereas the approximately 20-kDa fraction promoted iduronosyl 2-O-sulfation only. These results are discussed in relation to previous findings, indicating that some of the enzymes involved in heparin biosynthesis catalyze more than one reaction.

Lipid lowering through work stress reduction

Swedish civil servants, who reported considerable stress while working in larger government authorities, were randomized into either a work stress reduction intervention or a control group. Four work units constituted the intervention group (n = 94). and one unit formed the control group (n = 35). Participants in the two groups were of similar age and two thirds were women. Psychosocial, lifestyle, and physiological assessments were made before, during, and after the 8-month intervention period. A significant decrease in apolipoprotein B/apolipoprotein A I ratio (p < 0.05) occurred in the intervention group but not in the control group. No changes were seen in either group in smoking, eating. exercise, relative weight, or other lifestyle factors. which could explain the lipid profile changes. Stimulation from and autonomy over work increased in the intervention group (p < 0.01) hut remained the same in the control group. Results have implications for the efficacy of work stress interventions in decreasing coronary risk.