Proteoglycan metabolism in normal and inflammatory human macrophages

To study proteoglycan metabolism in inflammatory macrophages, primary cultures of human macrophages were cultured in the absence and presence of bacterial lipopolysaccharide (LPS). When exposed to [35S]sulfate, the cells incorporated the label almost exclusively into chondroitin sulfate proteoglycan (CSPG), which was recovered from the culture medium and the cell layer. Cells stimulated with LPS secreted approximately three times more [35]CSPG into the culture medium than control cells. Furthermore, cell adhesion was also found to promote proteoglycan secretion; when nonadherent monocytic cells were induced to adhere, the release of proteoglycan increased two times. The increased secretion seen in LPS-stimulated macrophages was partly due to increased biosynthesis, but was mostly due to increased sorting of CSPG to the secretory pathway. Only about 20% of the CSPG synthesized in unstimulated cells was secreted, whereas the corresponding figure in LPS-treated cells was 35%. In both cell types, the remaining [35S]CSPG was degraded, probably in the lysosomes. The degradation was a two-step process. First, the [35S]CSPG was rapidly cleaved to yield free glycosaminoglycan (GAG) chains (t1/2 = 15 to 30 minutes). Secondly, the GAG chains were completely depolymerized (t1/2 = 2 to 3 hours). Neither resting nor LPS-stimulated cells sorted CSPG to intracellular storage, as is evident in many hematopoietic cells. The LPS-treated cells synthesized [35S]CSPG of smaller molecular size than did control cells, with GAG chains of approximate molecular mass of 12 kD versus 16 kD in control cells. No difference was seen in the disaccharide composition of the GAG chains; both LPS-stimulated and unstimulated cells expressed a mixture of 80% to 90% chondroitin 4-sulfate and 10% to 20% chondroitin 4,6-disulfate. N-terminal sequence and Northern blot analysis indicate that the core protein of the CSPG secreted by human macrophages is serglycin.     

Intensified treatment of acute childhood lymphoblastic leukaemia has improved prognosis, especially in non-high-risk patients: the Nordic experience of 2648 patients diagnosed between 1981 and 1996

In a multinational, population-based study from the five Nordic countries (Denmark, Finland, Iceland, Norway and Sweden), 2648 children below 15 y of age were diagnosed with acute lymphoblastic leukaemia (ALL) in the years 1981-1996. The annual incidence was 3.9/100 000 children and was stable throughout the study period. The development from regional or national protocols to common Nordic treatment protocols for all risk groups was completed in 1992 through a successive intensification of therapy, based on multidrug chemotherapy including pulses of methotrexate in high doses and avoidance of cranial irradiation in most children. For children with non-B-cell ALL ( n = 2602), the event-free survival (p-EFS) increased from 0.53 ± 0.02 (diagnosed 7/81-6/86) to 0.67 ± 0.02 (7/86-12/91) to 0.78 ± 0.02 (1/92-12/96). The corresponding p-EFS values at 5 y were 0.57, 0.70 and 0.78, respectively. The main improvements were seen in the group of children with non-high risk leukaemia, with 5-y p-EFS values increasing from 0.60 to 0.76 and 0.85 for the three periods. In high-risk patients, progress has been moderate, especially in children with high white blood cell values at diagnosis. During the last 5-y period, only 10% of the patients received cranial irradiation in first remission while 90% of the patients received high doses of cytostatic infusions (methotrexate isolated or combined with cytarabinoside) and multiple intrathecal injections of methotrexate as CNS-adjusted treatment without any indication of an increased CNS relapse rate.     

Topology and order of formation of interchain disulfide bonds in von Willebrand factor

Interchain disulfide bonds between the subunits in von Willebrand factor (vWf) dimers and in vWf multimers have been studied using some unique features of the cultured human umbilical vein endothelial cell system. Ammonium chloride inhibition of multimerization of vWf allowed selective examination of vWf dimeric molecules, and monoclonal antibody against the vWf propolypeptide was used to separate pro-vWf dimers from mature dimers. After cleavage of dimers and multimers with Staphylococcus aureus V-8 protease, the location of interchain disulfide bonds in amino (N)-terminal or carboxyl (C)-terminal fragments was determined by gel electrophoresis under reduced and nonreduced conditions. The first interchain disulfide bonds formed during dimerization are in the C-terminal region of the subunits, whereas interdimer disulfide bonds are located in the N-terminal portion. These data confirm recent electron microscopic projections of disulfide bond locations and provide support to the hypothetical role of the propolypeptide in the multimerization process.     

The influence of active transport systems on morphine -6-glucuronide transport in MDCKII and MDCK-PGP cells

Background and the purpose of the study

Morphine-6-glucuronide (M6G) is a potent metabolite of morphine which has high penetration into the brain despite its high polarity, which could be the result of an active transport system involved in M6G transport through blood brain barrier. Examples of such transporters are p-glycoprotein (PGP), probenecid-sensitive transport mechanism, multidrug resistance related protein 1-3, the organic anion transporter family, and the organic anion transporter polypeptide family. The aim of present study was to elucidate the mechanisms involved in transporting morphine''s potent metabolite, M6G.

Methods

M6G permeability via two cell lines; MDCKII and MDCK-PGP, was compared with that of sucrose. M6G transport was examined in different concentrations and in the presence of inhibitors of different transport systems such as cyclosporine, digoxin and probenecid. M6G concentration was measured using ELISA assay. The method was sensitive, reliable and reproducible.

Results

The results confirmed that M6G could cross a layer of MDCK II or MDR-PGP cells more than sucrose could. It was also observed that M6G is a PGP transporter substrate. Its permeability was increased by the use of a PGP expressed cell line, and also in the presence of a strong PGP inhibitor. Digoxin related transporters such as Oatp2 may also involved in transport of M6G. M6G seemed to be a glucose transporter 1 substrate, but was not a substrate to probenecid sensitive transporters.

Major conclusion

It is concluded that different transporters are responsible for M6G transports via different membrane, which could have effects on its pharmacokinetics or pharmacodynamics.     

Selective 5-HT2 receptor blockade in exercise-induced asthma

Seven young extrinsic asthmatics participated in an open, pilot study to determine the protective effect of a selective 5-hydroxytryptamine (5-HT) blocking agent, ketanserin, on exercise induced asthma. ketanserin in a dose of 10 mg given intravenously 20 min before exercise altered the basal bronchomotor tone in only 1 of 6 subjects and offered partial protection against exercise-induced bronchoconstriction in 1 of 5 asthmatics with no overall effect in the group. All patients experienced sleepiness after administration of ketanserin and one had bradycardia with hypotension. The ineffectiveness of ketanserin suggests indirectly that serotonin has a limited role in the pathogenesis of exercise-induced asthma.