Amphiphilic derivatives of sodium alginate and hyaluronate for cartilage repair: rheological properties

Various amphiphilic derivatives of sodium alginate and hyaluronate were prepared by covalent fixation of long alkyl chains (dodecyl and octadecyl) with various ratios on the polysaccharide backbones via ester functions. In the semidilute regime, aqueous solutions of the resulting compounds exhibited the typical rheological properties of hydrophobically associating polymers: tremendous enhancement of zero shear rate Newtonian viscosity, steep shear-thinning behavior, and formation of physically cross-linked gel-like networks. The influence of the alkyl chain length, its content on the polysaccharide and of the polymer concentration in the solution was well identified. All obtained results are discussed with respect to the schedule of conditions related to materials, which could be used for cartilage repair, such as in synovial fluid viscosupplementation as well as in cartilage replacement. In particular, it is seen that HA-C(12)-5 (hyaluronate substituted with 5% of dodecyl chains) and HA-C(18)-1 (hyaluronate substituted with 1% of octadecyl chains) in a 0.15N NaCl solution at 8 g/L have rheological properties quite similar to those of healthy synovial fluid. On the other hand, the rheological parameters of solutions at 8 g/L in 0.15N NaCl of some of derivatives, such as, for example, AA-C(12)-8 (alginate substituted with 8% of dodecyl chains) or HA-C(18)-2, are well fitted for a use in cartilage repair.

Functional cross-talk between the cyclic AMP and Jak/STAT signaling pathways in vascular smooth muscle cells

Angiotensin II (Ang II), the primary effector of the renin-angiotensin system, is a multifunctional hormone that plays an important role in vascular function. In addition to its classical vasoconstrictor action, more recent studies demonstrated that Ang II stimulates the growth of a number of cell types, including vascular smooth muscle cells (SMC) (reviewed in [1-3]). In vivo studies have shown that chronic infusion of Ang II leads to the development of vascular hypertrophy in rats, whereas administration of angiotensin-converting enzyme (ACE) inhibitors or Ang II receptor antagonists prevents or regresses vascular hypertrophy in models of genetic and experimental hypertension [4]. Consistent with in vivo data, several laboratories have shown that Ang II stimulates protein synthesis and induces cellular hypertrophy, but not cell proliferation, in cultured aortic SMC [5-9]. Ang II also induces directed migration (chemotaxis) of vascular SMC [10, 11], although its effect is less prominent than that of platelet-derived growth factor (PDGF). The cellular mechanisms underlying these diverse actions of Ang II are not clearly understood but are likely to involve the activation of distinct signaling pathways.

Hydrophobically Associating Alginate Derivatives: Surface Tension Properties of Their Mixed Aqueous Solutions with Oppositely Charged Surfactants

The comparative study of the interfacial properties of an anionic polysaccharide, sodium alginate (Alg), and its hydrophobically modified derivative (Alg-C(12)), covalently substituted by dodecyl chains (12% mol/mol saccharide unit), was carried out in the absence or in the presence of an oppositely charged surfactant, dodecyltrimethylammonium bromide (DTAB). The drastically different behaviors which were observed are interpreted in terms of the arrangement and mobility of the hydrophobic long alkyl chains, depending on the nature of their fixation, covalent or ionic, on the polysaccharide backbone. Copyright 2000 Academic Press.

Features of polymyositis and dermatomyositis in the elderly: a case-control study

OBJECTIVE

Polymyositis (PM) and dermatomyositis (DM) are uncommon idiopathic inflammatory myopathies (IIM). Little is known about these diseases in the elderly. We attempted to define the characteristics of PM/DM in the elderly by a case-control study involving the retrospective review of medical files of PM/DM patients.

METHODS

We drew from among 200 PM/DM patients being followed in our Internal Medicine Department 21 patients (14 F/7 M), aged > or = 65 years at the onset of myositis (17 PM/4 DM) (mean: 69.9 +/- 4.8 yrs.). They were compared with 21 (15 F/6 M) randomly selected younger patients with IIM: PM (14) and DM (7) (mean: 46.4 +/- 12.4 yrs). Clinical, biological, electrophysiological and pathologic features, treatment regimens and side-effects in the 2 groups were collected.

RESULTS

Clinical features were similar for the 2 groups. Elderly patients tended to have a higher frequency of cancer (24% vs 9.5%, p = 0.06), particularly of rectal adenocarcinoma. The time from disease onset to diagnosis was significantly longer in older patients (26 +/- 37 months vs 9 +/- 15 months; p = 0.02), normal CK levels were more frequent (40% vs 5%; p = 0.02) and serum CK levels were lower than for the population as the whole (11.5 N vs 22 N, p < 0.03). Electromyography features were more frequently suggestive of a chronic form of the disease in elderly patients. Treatment regimens and short-term side-effects were similar for the 2 groups.

CONCLUSION

PM and DM are often diagnosed late in the elderly. Biological data and electromyography features argue for a chronic form of the disease in this age group. Clinical and endoscopic rectal examinations should be carried out in elderly patients with PM/DM.

Adenosine induces cyclic-AMP formation and inhibits endothelin-1 production/secretion in guinea-pig tracheal epithelial cells through A(2B) adenosine receptors

1. The adenosine receptor subtype mediating adenosine 3' : 5'-cyclic monophosphate (cyclic AMP) formation and the effect of its activation on endothelin-1 (ET-1) secretion were studied in primary cultures of tracheal epithelial cells. 2. Adenosine analogues showed the following rank order of potency (pD(2) value) and intrinsic activity on the generation of cyclic AMP by tracheal epithelial cells: 5'-N-ethylcarboxyamidoadenosine (NECA, A(1)/A(2A)/A(2B), pD(2): 5.44+/-0.16)>adenosine (ADO, non selective, pD(2): 4.99+/-0. 09; 71+/-9% of NECA response) >/=2-Cl-adenosine (2CADO, non selective, pD(2): 4.72+/-0.14; 65+/-9% of NECA response)>>>CGS21680 (A(2A); inactive at up to 100 microM). 3. Cyclic AMP formation stimulated by NECA in guinea-pig tracheal epithelial cells was inhibited by adenosine receptor antagonist with the following order of apparent affinity (pA(2) value): Xanthine amine congeners (XAC, A(2A)/A(2B), 7.89+/-0.22)>CGS15943 (A(2A)/A(2B), 7.24+/-0. 26)>ZM241385 (A(2A), 6.69+/-0.14)>DPCPX (A(1), 6.51+/-0. 14)>3n-propylxanthine (weak A(2B), 4.30+/-0.10). This rank order of potency is typical for A(2B)-adenosine receptor. 4. Adenosine decreased basal and LPS-stimulated irET production in a concentration-dependent manner. Moreover, NECA but not CGS21680 inhibited LPS-induced irET production. 5. The inhibitory effect of NECA on LPS-induced irET production was reversed by XAC (pA(2)=8.84+/-0. 12) and DPCPX (pA(2)=8.10+/-0.22). 6. These results suggested that adenosine increased cyclic AMP formation and inhibited irET production/secretion by guinea-pig tracheal epithelial cells through the activation of a functional adenosine receptor that is most likely the A(2B) subtype. This adenosine receptor may be involved in the regulation of the level of ET-1 production/secretion by guinea-pig tracheal epithelial cells in physiological as well as in pathophysiological conditions.

Involvement of bradykinin B1 and B2 receptors in pulmonary leukocyte accumulation induced by Sephadex beads in guinea pigs

The effects of selected bradykinin receptor antagonists on leukocyte infiltration into the lungs were studied in a model of guinea pig lung inflammation induced by the intravenous injection of Sephadex beads. The bradykinin B1 receptor antagonist, [Leu8]desArg9-BK (40 mg kg(-1) 24 h(-1)) and the bradykinin B2 receptor antagonist, DArg[Hyp3,Thi5,DTic7,Oic8]BK (code name HOE 140; 4 mg kg(-1) 24 h(-1)), administered intravenously by osmotic pumps, significantly reduced eosinophil counts by 33% and 42% in bronchoalveolar fluid, respectively. HOE 140 decreased neutrophil counts by 35%. LysLys[Hyp3,Igl5,D-Igl7,Oic8]desArg9BK+ ++ (code name B 9858), a newly described bradykinin B1 receptor antagonist, administered intraperitoneally (1 mg kg(-1)), decreased eosinophil and neutrophil counts by 45% in bronchoalveolar fluid. D-Arg[Hyp3,Igl5,D-Igl7,Oic8]BK (code name B 9430), a non-selective bradykinin B1/B2 receptor antagonist, also administered intraperitoneally (1 mg kg(-1)), decreased eosinophil and macrophage counts by 62% and 80% in bronchoalveolar fluid. These results suggest that bradykinin B1 and B2 receptors are involved in leukocyte recruitment in our model of lung inflammation.

Evidence for the activation of blood complement in Sephadex beads-induced lung inflammation in guinea pigs

OBJECTIVE AND DESIGN

This study evaluated the complement activation in guinea pigs that were given an intravenous injection of Sephadex and its correlation with markers of the development of inflammation.

MATERIALS AND METHODS

Dunkin Hartley guinea pigs (250-300 g) were used. Whole blood was collected by heart puncture in a sodium citrate solution (0.315 g/ml) for complement measurements. Complement activation was measured using a colorimetric haemolytic assay. Bronchoalveolar lavages (BAL) were performed to monitor cell infiltration and inflammation was monitored by measurements of eosinophil peroxidase (EPO), histamine, beta-glucuronidase, albumin and total proteins in the BAL fluid.

TREATMENT

Guinea pigs were pre-treated with aprotinin (40000 IKU/kg) 30 min before they were given an intravenous injection of Sephadex beads (24 mg/kg). Carboxymethyl (CM)-Sephadex (24 mg/kg) was administered alone.

RESULTS

Sephadex beads activated the complement system in vitro (14.12+/-2.29 U/ml) and in vivo (9.95+/-0.08 U/ml) reaching a peak 6 h after the injection. This activation was accompanied by other characteristic features of inflammation such as leukocyte infiltration and activation. Both CM-Sephadex and aprotinin reduced the blood complement activation and eosinophil infiltration/activation observed.

CONCLUSIONS

Our results strongly suggest that complement is involved in the cascade of events leading to the inflammatory state observed in guinea pig following the intravenous injection of Sephadex beads.

Cerebral Erdheim-Chester disease: report of two cases with progressive cerebellar syndrome with dentate abnormalities on magnetic resonance imaging

Two patients with Erdheim-Chester disease with progressive cerebellar dysfunction and pyramidal signs are reported on. Cerebral MRI showed bilateral increased signal intensity in peridentatal regions on T2 weighted sequences. Both patients had kidney and bone involvement, established on bone biopsy for one. One patient improved with steroid therapy. This contrasts with previous reports, which describe rare neurological manifestations and the failure of different therapeutic approaches.

Effects of dual endothelin-converting enzyme/neutral endopeptidase inhibitors, CGS 26303 and CGS 26393, on lipopolysaccharide or interleukin-1 beta-stimulated release of endothelin from guinea pig tracheal epithelial cells

A number of studies using endothelin (ET) receptor antagonists support the participation of ETs in a variety of cardiovascular, renal, and other disorders. It has also been established that a number of cytokines, which are released in such diseases, modulate the expression and production of ETs and thus activate the ET system. This effect may represent one pathway by which these inflammatory mediators operate. By regulating endothelin-converting enzyme (ECE) activities, and thus ET synthesis, one can potentiate or attenuate the production of ETs and the receptor affinity/density in such pathologic conditions. Here, the stimulated (lipopolysaccharide or interleukin-1 beta) production of ET-1 from guinea pig tracheal epithelial cells was abolished by CGS 26303 or CGS 26393, two ECE/neutral endopeptidase (NEP) inhibitors, but was unaffected by CGS 24592, a specific NEP inhibitor. Therefore, such dual, and eventually selective ECE inhibitors are effective agents to prevent the stimulated production of ETs.

Adenosine-induced inhibition of basal endothelin-1 production from guinea-pig tracheal epithelial cells: a mechanism involving the release of cAMP

Guinea-pig tracheal epithelial cells, like other pulmonary cells in various species, have been reported to synthesize and release endothelins (ET). Their production is inducible by many agents and inhibited by ET-converting enzyme inhibitors, corticosteroids and beta agonists. Here, we studied the effect of adenosine on (1) the formation of adenosine 3', 5'-cyclic monophosphate (cAMP) and (2) concomitant effect on the basal release of ET from primary cultured tracheal epithelial cells isolated from guinea-pigs (GPTEpC). Adenosine (10(-7)-10(-3) M), the endogenous non-selective purinergic receptor agonist, induced the production of cAMP in a concentration-dependent manner (pD2=4.99+/-0.09). Concomitantly, adenosine decreased by a maximum of 39% ET-1-production over the same concentration range (with a 96% correlation). The inhibitory effect over ET-1-production was abolished by CGS15943 (10(-4) M), a non-selective A1/A2A receptor antagonist, and a xanthine amine congener (10(-4) M), a selective A1 receptor antagonist. Thus, these results suggest that adenosine attenuates the production of ET-1 from GPTEpC by stimulating the release of cAMP via the direct activation of adenosine receptors.

Different immune effects on cardiac allografts and xenografts induced by neonatal intrathymic inoculation with allogeneic and xenogeneic antigens

BACKGROUND

In a previous study we demonstrated that intrathymic exposure of neonatal rats to both alloantigens and xenoantigens produced tolerance only to subsequent cardiac allografts and not to xenografts implanted when the animals were 6 weeks old. Interestingly, graft recipients were not sensitized to the xenografts as observed in the adult model. This study was designed to investigate whether earlier grafting would produce tolerance to cardiac xenografts in animals pretreated by neonatal intrathymic inoculation with allogeneic and xenogeneic cells.

METHODS

All recipient animals were Lewis rats. Donors were either Lewis Brown Norway rats or Golden Syrian hamsters. Lewis Brown Norway rat and hamster splenocytes (25 x 10(6) cells in a volume of 0.01 ml) were inoculated percutaneously into the thymus of neonatal recipients (n = 22). At age 4 weeks, five pretreated recipients underwent cervical heterotopic heart transplantation with rat hearts, and 2 weeks later abdominal heterotopic transplantation was done with hamster donors. A second group ( n = 6) received hamster hearts as the first graft and then grafts from rat donors. The third group underwent rat followed by hamster heart transplantation at age 6 to 7 weeks.

RESULTS

Mean rat allograft survival time for groups 1,2, and 3, respectively was 49.8 days with 4 of 5 surviving indefinitely, 4.3 days with 2 of 3 surviving indefinitely, and 42 days with 7 of 11 surviving indefinitely (p < 0.01 versus untreated control animals, 7.8 days, n = 5). In rats undergoing transplantation at 4 weeks, cardiac xenografts were rejected in 2.5 days 2.3 days, which was significantly shorter than xenograft survival (3.3 days) in rats that underwent transplantation at an older age (p < 0.02), in naive rats (p < 0.05), and in rats treated with hamster cells alone (p < 0.05). Mixed lymphocyte reaction showed a diminished proliferative response to Lewis Brown Norway rat cells in pretreated rats, which retained the ability to respond in culture to hamster cells (p < 0.05).

CONCLUSIONS

Earlier grafting in rats pretreated as neonates produces allograft tolerance but may accelerate rejection of xenografts. Preliminary mixed lymphocyte reaction results suggest that only the alloimmune cellular proliferative response is abrogated by this pretreatment.

Antiphospholipid syndrome as the second cause of non-tumorous Budd-Chiari syndrome

In a prospective study of 22 patients with non-tumorous Budd-Chiari syndrome, four were found to have the antiphospholipid syndrome with no other cause of hepatic vein thrombosis. All four patients were young women. The antiphospholipid syndrome was secondary to systemic lupus in one case, to a "lupus-like disease" in another, and apparently primary in the remaining two cases. Two patients died. The other two are in good health on chronic oral anticoagulation. In our experience, the antiphospholipid syndrome is a frequent cause, after myeloproliferative disorders, of non-tumorous Budd-Chiari syndrome. In such patients, long-term anticoagulation may prevent recurrence or extension of thrombosis.

[Exudative enteropathy in disseminated lupus erythematosus]

We present the case of a young woman with a protein-losing enteropathy occurring in the context of systemic lupus erythematosus. This rare complication has limited gastro-intestinal manifestations and must be systematically looked for when hypoalbuminemia occurs in the absence of a lupus nephritis. High dose corticosteroids therapy (> or = 1 mg/kg/day of prednisone) usually leads to recovery, and should be the first treatment attempted. If this treatment is ineffective, bolus injections of methylprednisolone (1 g/day for three days) may be recommended. Immunosuppressive therapy should be given only if the above treatments are ineffective, or in case of cortico-dependency.

[Pancreatic endocrine tumor with metastases and increase of alpha-fetoprotein. A case report]

The authors report the case of a 48 years old man presenting a pancreatic islet cell carcinoma (gastrinoma) with liver, nodes and peritoneal metastases, associated with an elevated alpha-fetoprotein (AFP) concentration. Incomplete remission was first obtained with a chemotherapy using Streptozotocin combined with 5-Fluorouracil, in association with a Somatostatin analogue (SMS 201-995). But when relapses occur, another chemotherapy was not so effective. Serum gastrin and AFP levels had the same evolution and appear to have the same interest to follow the course of the disease.