[Accelerated atherosclerosis in rheumatic systemic diseases as an example of systemic lupus erythematosus--what is the consequence?]

Large increases in mortality related to premature atherosclerosis with coronary artery disease and stroke have been reported during the last few years in patients with systemic lupus erythematosus (SLE). Studies found relative risks of 5 to 7 for myocardial infarction in SLE patients. The traditional risk factors fail to fully account for accelerated atherosclerosis in SLE and APS, in addition prolonged glucocorticoid therapy and long duration of SLE seem to be of importance. The disease SLE per se is an independent risk factor. The current pathogenic hypothesis for atherosclerosis involves an inflammatory response, autoantibodies, immune complexes (containing antibodies to phospholipids, to oxidized LDLs, and to endothelial cells), CD40/CD40 ligand interactions, and bacterial or viral infections responsible for an immune response. The determination of classic and new risk factors, together with specific autoantibody titers and the use of Doppler carotid ultrasound, are useful methods to detect early atherosclerosis. Therapeutic strategies, including early risk factor intervention and effective control of inflammation, are essential to reduce morbidity and mortality and should be incorporated into the management of connective tissue disease with the goal of protecting patients against atherosclerosis.

[Preventing type 2 diabetes complications: from evidence-based recommendations to patient-based reality]

The vascular complications of type 2 diabetes count for the principal causes of morbidity, hospitalisation and mortality in this population. Therefore, preventing these complications is the cornerstone of the management of these patients. This prevention is through multifactorial interventions aiming at controlling the parameters of the metabolic syndrome in order to prevent or slow down these vascular complications. This prevention is also through a regular and exhaustive screening performed early enough in the disease. Above all, the management of these patients implies involving them as the main actors of their disease and treatments. This necessitates to take into account the beliefs and to actively seek the obstacles to therapeutic adherence.

Escalating immunotherapy of multiple sclerosis--new aspects and practical application

Recent clinical studies in multiple sclerosis (MS) provide new data on the treatment of clinically isolated syndromes, on secondary progression, on direct comparison of immunomodulatory treatments and on dosing issues. All these studies have important implications for the optimized care of MS patients. The multiple sclerosis therapy consensus group (MSTCG) critically evaluated the available data and provides recommendations for the application of immunoprophylactic therapies. Initiation of treatment after the first relapse may be indicated if there is clear evidence on MRI for subclinical dissemination of disease. Recent trials show that the efficacy of interferon beta treatment is more likely if patients in the secondary progressive phase of the disease still have superimposed bouts or other indicators of inflammatory disease activity than without having them. There are now data available, which suggest a possible dose-effect relation for recombinant beta-interferons. These studies have to be interpreted with caution, as some potentially important issues in the design of these studies (e. g. maintenance of blinding in the clinical part of the study) were not adequately addressed. A meta-analysis of selected interferon trials has been published challenging the value of recombinant IFN beta in MS. The pitfalls of that report are discussed in the present review as are other issues relevant to treatment including the new definition of MS, the problem of treatment failure and the impact of cost-effectiveness analyses. The MSTCG panel recommends that the new diagnostic criteria proposed by McDonald et al. should be applied if immunoprophylactic treatment is being considered. The use of standardized clinical documentation is now generally proposed to facilitate the systematic evaluation of individual patients over time and to allow retrospective evaluations in different patient cohorts. This in turn may help in formulating recommendations for the application of innovative products to patients and to health care providers. Moreover, in long-term treated patients, secondary treatment failure should be identified by pre-planned follow-up examinations, and other treatment options should then be considered.

Detection of myocardial infarctions by acquisition-weighted 31P-MR spectroscopy in humans

PURPOSE

To determine whether the recently applied technique of acquisition-weighted 31P-MR spectroscopy (AW-MRS) allows for the detection of depressed energy metabolism in patients with inferior wall myocardial infarctions.

MATERIALS AND METHODS

Eight patients with subacute myocardial infarction and wall motion abnormalities restricted to the inferior wall were examined with a 1.5-T MR scanner. Global and regional left ventricular (LV) function was assessed by cine MRI, and the size and extent of myocardial infarction was assessed by late enhancement (LE). MRS was performed with an AW three-dimensional chemical shift imaging sequence. Phosphocreatine/ATP ratios were determined with the postprocessing model AMARES for four voxels positioned in the anterior, lateral, inferior, and septal parts of the LV.

RESULTS

The LV ejection fraction (EF) was reduced to 37.5%+/-9.0%. Seven of eight patients had transmural LE in the inferior wall, and one patient showed subendocardial enhancement in the inferior-lateral parts. Phosphocreatine/ATP ratios of the inferior wall were significantly reduced (P <0.05) compared to all other parts of the LV (1.03 +/- 0.39 (inferior), 1.67 +/- 0.81 (lateral), 1.73 +/- 0.29 (anterior), and 1.49 +/- 0.31 (septal)). The ratios in five of seven patients with transmural enhancement were <1.00 in the inferior wall.

CONCLUSION

Acquisition weighting allows for the detection of inferior wall infarctions in patients. Transmural signal enhancement is associated with significant depression of phosphocreatine/ATP ratios.

Quantification of Uhthoff's phenomenon in multiple sclerosis: a magnetic stimulation study

OBJECTIVE

To quantify temperature induced changes (=Uhthoff phenomenon) in central motor conduction and their relation to clinical motor deficits in 20 multiple sclerosis (MS) patients.

METHODS

Self-assessment of vulnerability to temperature and clinical examination were performed. We used motor evoked potentials to measure central motor conduction time (CMCT) and applied the triple stimulation technique (TST) to assess conduction failure. The TST allows an accurate quantification of the proportion of conducting central motor neurons, expressed by the TST amplitude ratio (TST-AR).

RESULTS

Temperature induced changes of TST-AR were significantly more marked in patients with prolonged CMCT (P=0.037). There was a significant linear correlation between changes of TST-AR and walking velocity (P=0.0002). Relationships were found between pronounced subjective vulnerability to temperature and (i) abnormal CMCT (P=0.02), (ii) temperature induced changes in TST-AR (P=0.04) and (iii) temperature induced changes in walking velocity (P=0.04). CMCT remained virtually unchanged by temperature modification.

CONCLUSIONS

Uhthoff phenomena in the motor system are due to varying degrees of conduction block and associated with prolonged CMCT. In contrast to conduction block, CMCT is not importantly affected by temperature.

SIGNIFICANCE

This is the first study quantifying the Uhthoff phenomenon in the pyramidal tract of MS patients. The results suggest that patients with central conduction slowing are particularly vulnerable to develop temperature-dependent central motor conduction blocks.

[School nutrition and nutrition lessons]

Nutrition behavior usually becomes manifest during childhood and once learned food patterns and eating habits are often maintained for the rest of life. Therefore, imparting knowledge early about food composition, food habits, nutritional physiology, and connections between health and nutrition as well as instilling competence in dealing with food are of particular importance. In the EiS project, it was recently shown that fewer students than ever obtain less and less nutrition education in German schools. Promoting healthy eating is not only a matter of nutritional knowledge. It is also very much about creating a healthy environment and providing proper food, drinks, and meal service in schools. Therefore, both aspects will be discussed in the following article.

Withdrawal of cerivastatin induces monocyte chemoattractant protein 1 and tissue factor expression in cultured vascular smooth muscle cells

OBJECTIVE

The withdrawal of 3-hydroxy-3-methylglutaryl-coenzyme A-reductase inhibitors (statins) deteriorates endothelial function. We determined in vascular smooth muscle cells whether statin withdrawal leads to the expression of proinflammatory genes involved in the development and progression of arteriosclerosis.

METHODS AND RESULTS

The withdrawal of cerivastatin from pretreated vascular smooth muscle cells induced an increase in monocyte chemoattractant protein 1 (MCP-1) and tissue factor (TF) mRNA expression and enhanced MCP-1 secretion as well as cell surface TF activity. In the presence of cerivastatin, this effect was mimicked by geranylgeranyl pyrophosphate or mevalonate. Withdrawal-induced MCP-1 expression was sensitive to PD98059, SB203580, and diphenylene iodonium, suggesting an involvement of extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, and the NADPH oxidase. Withdrawal increased the activity of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase and enhanced radical generation. Because the latter effect may result from an Rac-mediated activation of the NADPH oxidase, the effect of withdrawal on Rac translocation was studied. Statin treatment induced an increase in Rac-1 content in the cytoplasm. On withdrawal, however, an "overshoot" translocation of Rac to the plasma membrane occurred.

CONCLUSIONS

These observations suggest that statin withdrawal results in the activation of Rac and enhanced oxidative stress. The subsequent activation of redox-activated signal-transduction cascades results in the expression of MCP-1 and TF.

Administration of testosterone is associated with a reduced susceptibility to myocardial ischemia

This study investigated the impact of testosterone on myocardial ischemia-reperfusion injury and corresponding intracellular calcium ([Ca2+]i) metabolism. Nonorchiectomized mature male Wistar rats were randomly assigned to placebo, a single dose of testosterone undecanoate, or 5alpha-dihydrotestosterone. In a further series, orchiectomized rats were treated with placebo. After 2 wk of treatment, the hearts were removed and placed in a Langendorff setup. The isolated, buffer-perfused hearts were subjected to 30 min of no-flow ischemia and 30 min of reperfusion. Recovery of myocardial function was measured by analyzing pre- and postischemic left ventricular (LV) systolic/diastolic pressure and coronary perfusion pressure simultaneously, together with [Ca2+]i handling (aequorin luminescence). Calcium regulatory proteins were analyzed by Western blotting. LV weight/body weight ratio was increased after administration of testosterone vs. orchectomized rats. The recovery of contractile function was improved in testosterone-treated rats: at the end of the reperfusion, LV systolic pressure was higher and end-diastolic pressure was lower in testosterone-treated rats. End-ischemic [Ca2+]i and [Ca2+]i overload upon reperfusion was significantly lower in testosterone vs. orchiectomized rats, too. However, levels of calcium regulatory proteins remained unaffected. In conclusion, administration of testosterone significantly improves recovery from global ischemia. These beneficial effects are associated with an attenuation of reperfusion induced [Ca2+]i overload.

Testosterone undecanoate: a useful tool for testosterone administration in rats

A major obstacle of testosterone (T) treatment in experimental animals is the difficulty of maintaining long-term physiologic/anabolic steady serum levels after exogenous T administration. In two complementary studies we investigated the pharmacokinetic properties of different T formulations in male rats. Study I. Mature male Wistar rats (> 380 g, n = 4 - 7/group) were divided into four treatment groups: (1) sham-operated non orchiectomised (non-ORX) and placebo; (2) orchiectomised (ORX) and subcutaneous testosterone pellets (TP) (15, 25, 75 mg/60 days release or placebo pellets); (3) ORX and a single injection of testosterone undecanoate (TUD) (31, 62.5 or 125 mg/kg body weight subcutaneously (s.c.) or vehicle; (4) ORX and testosterone propionate (Tprop) (10, 20, 40 mg/month) or vehicle as a single injection s.c. Serum T was measured at baseline and in weekly intervals for 4 weeks. Study II. Mature male Wistar rats (180 - 200 g) were randomly assigned to one of 5 experimental groups (n = 5 - 6/group): (1) normal untreated rats (controls); (2) ORX untreated rats, and non-ORX rats receiving one of three treatment options; (3) 250 mg/kg body weight TUD i.m. (TUD 250); (4) 500 mg/kg body weight TUD i.m. (TUD 500); (5) 100-mg testosterone pellet/90 days release s.c. (TP 100). Serum T was measured at baseline and in intervals for 6 weeks after T administration. In both studies, the kinetic profile of TUD showed favourable continuous steady state levels over several weeks. In contrast, testosterone release by subcutaneous pellets resulted in a shorter than expected duration of elevated serum T levels with high inter-individual variability. Tprop administration led to only a short-lasting serum T increase with low serum T levels already 14 days after injection. In conclusion, a single injection of TUD (100 mg/kg body weight s.c.) is effective in inducing physiological testosterone levels in ORX rats for a minimum of four weeks. High dose TUD (500 mg/kg body weight i.m.) given as a single injection results in supraphysiological anabolic testosterone concentrations for up to six weeks in non-ORX rats. TUD was superior to other T release preparations and represents a convenient and effective tool for T administration in experimental animals.

Effect of testosterone on post-myocardial infarction remodeling and function

BACKGROUND

Men and women are differently affected by coronary artery disease, suggesting an important role of sex steroids. Moreover, testosterone (T) treatment is increasingly used in elderly males. Therefore, we examined effects of chronic anabolic T administration on left ventricular (LV) remodeling after myocardial infarction (MI).

METHODS

Adult male rats were treated with intramuscular placebo, testosterone undecanoate (T), or were orchiectomized. After 2 weeks, animals underwent sham-operation (sham) or left coronary artery ligation. Left ventricular remodeling and function was assessed by serial magnetic resonance imaging (MRI) at weeks 2 and 8 and hemodynamic investigation at week 8.

RESULTS

In sham operated animals T administration increased serum T levels and led to cardiac hypertrophy, but not to an upregulation of ANP mRNA. The alpha/beta-MHC ratio was significantly higher after T treatment due to an increase in alpha-MHC. As a potential mechanism for this "physiologic" form of hypertrophy, IGF-1 mRNA expression was significantly increased in T treated animals. After coronary artery ligation, infarct size and mortality were similar among the groups. Left ventricular hypertrophy was enhanced by T treatment. However, in vivo LV end-diastolic pressure and wall stress were decreased by T, whereas other hemodynamic parameters (mean arterial pressure, cardiac output, etc.) remained unchanged.

CONCLUSION

Chronic anabolic T treatment led to a specific "physiologic" pattern of myocardial hypertrophy with a significant increase in LV weight, but without differences in ANP and with an upregulation in alpha/beta-MHC, possibly mediated by IGF-1. Testosterone treatment had no detrimental effects following MI. Reduced wall stress and LVEDP may even improve long-term outcome.

Susceptibility to cardiac ischemia/reperfusion injury is modulated by chronic estrogen status

The purpose of this study was to test whether the susceptibility of the heart to ischemia/reperfusion injury is modulated by the chronic estrogen status, i.e., increased with estrogen deficiency and attenuated by pharmacologic estrogen supplementation. In addition, the study tested whether estrogen-dependent changes in mechanical function are associated with alterations of cardiac high-energy phosphate metabolism. Rats were ovariectomized, not ovariectomized, or ovariectomized and treated with subcutaneous estrogen pellets (1.5 mg/21 d) (n = 8-11 per group). Three weeks later, hearts were isolated and perfused isovolumically under constant perfusion pressure conditions. Hearts were subjected to 15 min of total global ischemia (37 degrees C) and 30 min of reperfusion. Simultaneous [31P] nuclear magnetic resonance spectra were recorded throughout this protocol to monitor changes in ATP, phosphocreatine, and inorganic phosphate content. Whereas preischemic values for heart rate, end-diastolic pressure, and coronary flow were not different among groups, left ventricular developed pressure was slightly but significantly decreased in the estrogen-treated group (p < 0.05). However, treated hearts showed improved recovery of left ventricular developed pressure on reperfusion (89 +/- 4% in control rats, 70 +/- 8% in ovariectomized hearts, and 114 +/- 9% of preischemic values in estrogen-treated rats). However, changes in ATP, phosphocreatine, and inorganic phosphate during ischemia were as previously described and were unaffected by chronic estrogen status. In conclusion, in the isolated buffer-perfused rat heart, estradiol treatment caused improved functional recovery after ischemia/reperfusion injury. This improvement, however, did not include preservation of high-energy phosphate metabolism. Other potential mechanisms include an anti-oxidant activity of 17beta-estradiol-and estrogen-induced alterations in glucose metabolism.

Impact of neurorehabilitation on disability in patients with acutely and chronically disabling diseases of the nervous system measured by the Extended Barthel Index

To study the impact of rehabilitation on disability in an unselected patient group with acutely and chronically disabling neurologic diseases, the Extended Barthel Index (EBI) was determined at the beginning and at the end of the rehabilitation stay in all patients admitted to our Neurorehabilitation Centre in Valens, Switzerland. Patients who reached the highest possible EBI score at entry ("ceiling effect"), with a short stay (<1 week), or with a deterioration due to other medical complications were excluded. Finally EBI data of 743 patients could be analyzed. The mean EBI at entry was 45 and 51 at discharge. The mean increase of the EBI score per week was 1.1 (SD, 1.7). The change of the EBI score was analyzed independently in patients with acute neurologic diseases admitted in the postacute phase (acute group) and patients with chronically disabling neurologic diseases (chronic group). As expected, the increase of the EBI score was higher in the acute group than in the chronic group; 80.8% of the acute group patients and 42.5% of the chronic group patients showed an increase of the EBI score at discharge. Both groups showed a significant EBI gain with a marked shift to higher EBI scores at discharge. The mean gain per week was 1.6 in the acute group and 0.5 in the chronic group, respectively. Analysis of EBI changes considering the different underlying diseases showed the highest increase in patients with stroke and traumatic brain injury.

Molecular cloning and characterization of a novel SH3 protein (SLY) preferentially expressed in lymphoid cells

A novel full-length cDNA was isolated from a murine T-cell lymphoma library that has an open reading frame encoding 381 amino acids. The predicted protein (termed SLY) contains a Src homology 3 domain and a sterile alpha motif, suggesting that it functions as a signaling adaptor protein in lymphocytes. Northern blot and in situ hybridization analysis showed a preferential expression in lymphoid tissues. The sly gene is located on the X-chromosome in close proximity to genes involved in various immune disorders. This is consistent with an additional role of SLY in immune pathology.

Quantitative real-time PCR assay for determining transgene copy number in transformed plants

The development of transgenic events can be limited by many factors. These include expression levels, insert stability and inheritance, and the identification of simple insertion events. All of the factors can be related to the copy number of the transgene. Traditionally, copy number has been determined by laborious blotting techniques. We have developed an alternative approach that utilizes the fluorogenic 5' nuclease (TaqMan) assay to quantitatively determine transgene copy level in plants. Using this assay, hundreds of samples can be analyzed per day in contrast to the low throughput encountered with traditional methods. To develop the TaqMan copy number assay, we chose to utilize our highly efficient Agrobacterium-mediated transformation system of maize. This transformation procedure generates predominantly low copy number insertion events, which simplified assay development. We have also successful applied this assay to other crops and transformation systems.

Thrombin-induced MCP-1 expression involves activation of the p22phox-containing NADPH oxidase in human vascular smooth muscle cells

Activation of vascular smooth muscle cells (VMSC) by thrombin induces the expression of the chemokine, monocyte chemoattractant protein-1 (MCP-1). We investigated in cultured human and rat VSMC whether reactive oxygen species (ROS) derived from the vascular NADPH oxidase contribute to this effect. Exposure of cultured VSMC to thrombin rapidly increased ROS formation, phosphorylation of p38 MAP kinase as well as the expression of MCP-1. Specific inhibition of the p22phox subunit of the vascular NADPH oxidase using either p22phox neutralizing antibody or p22phox antisense oligonucleotides attenuated thrombin-induced ROS generation. Furthermore, thrombin-induced p38 MAP kinase activation as well as MCP-1 expression were impaired by antioxidants as well as by p22phox antisense oligonucleotides. Inhibition of p38 MAP kinase diminished the thrombin-induced expression of MCP-1.

CONCLUSION

Thrombin, by activating a p22phox-containing NADPH oxidase, elicits ROS generation and activation of p38 MAP kinase in VSMC. The subsequent induction of MCP-1 expression highligts the crucial role of the p22phox-containing NADPH oxidase in thrombin-induced signal transduction in VSMC.

The impact of different response alternatives on responders' reporting of health-related behaviour in a postal survey

Previous experimental research in other topic areas has shown that the choice of response alternatives can influence respondents' reporting of the frequency of vaguely defined events and that the set of response alternatives is treated as information in the interpretation of the question. The aim of this study was to examine whether such affects would occur in the context of respondents reporting of health-related events using high and medium frequency closed format response categories, which might be used interchangeably by researchers. The study consisted of a postal survey of n = 518 patients aged > or = 18 years randomly selected from the patient list of a diabetes centre and who were equally and randomly allocated to one of three conditions (Condition A: high frequency response alternatives/horizontal orientation; condition B: medium frequency response alternatives/horizontal orientations; condition C: high frequency response alternatives/vertical orientation). Testing for the effect of response alternatives for the combined responses of five vaguely defined questions between conditions A and B was chi 2 = 5.5, p = 0.019, for the difference in proportions, indicating that overall, those respondents presented with response alternatives discriminating at medium frequency, reported significantly fewer target events than those presented with high frequency response alternatives. Testing for the effect of orientation of the combined question responses between conditions A and C, differences in proportions between conditions, did not reach statistical significance (p > 0.05). Findings from this and previous studies indicate that response alternatives provide information on the interpretation of vaguely defined questionnaire items and that their choice should not be left to intuition alone when designing questionnaire items.

[Anterior interosseous nerve syndrome as differential diagnosis of closed isolated flexor tendon lesion]

Lesions of the anterior interosseus nerve can result in a variety of clinical manifestations, depending on location and degree of axonal damage. Clinical presentation with an isolated palsy of the flexor pollicis longus muscle is difficult to distinguish from a closed tendon rupture, especially when a trauma occurred. We would like to present five of our cases and discuss the diagnostic and therapeutic modalities.

The use of phosphomannose-isomerase as a selectable marker to recover transgenic maize plants (Zea mays L.) via Agrobacterium transformation

A new selectable marker system has been adapted for use in Agrobacterium-mediated transformation of maize. This selection system utilizes the pmi gene encoding for phosphomannose-isomerase that converts mannose-6-phosphate to fructose-6-phosphate. Only transformed cells are capable of utilizing mannose as a carbon source. Agrobacterium-mediated transformation of immature embryos followed by a pre-selection of 10-14 days prior to selection at a level of 1% mannose and 0.5% sucrose led to the recovery of trangenic lines of a frequency of as high as 30% in about 12 weeks. Molecular and genetic analysis showed that selected plants contained the pmi gene and that the gene was transmitted to the progeny in a Mendelian fashion.

Detection of anterior horn lesions by MRI in central European tick-borne encephalomyelitis

We report a case of central European tick-borne encephalitis with cervical myelitis presenting clinically as a lower motor neuron syndrome of the upper limbs with proximal asymmetrical pareses and atrophies. There were no sensory deficits nor signs of lesions of the spinal pathways or signs of encephalitis or meningitis. The affected motor fibers of the upper limbs were electrically inexcitable, but sensory findings were normal. Electromyography of the paralyzed muscles revealed pathological denervation activity without voluntary activation. The initial magnetic resonance imaging (MRI) showed a large hyperdense lesion in the anterior part of the cervical cord from C3 to T1. Despite the fact that MRI changes disappeared completely within 6 weeks the patient showed only little improvement in the paralyzed muscles after 6 months. To our knowledge, these MRI changes in patients with tick-borne encephalitis, consistent with an isolated anterior horn lesion, have never been reported previously. The course may have been aggravated by an initial antibiotic treatment with cephalosporins.

Integrin and neurocan binding to L1 involves distinct Ig domains

The cell adhesion molecule L1, a 200-220-kDa type I membrane glycoprotein of the Ig superfamily, mediates many neuronal processes. Originally studied in the nervous system, L1 is expressed by hematopoietic and many epithelial cells, suggesting a more expanded role. L1 supports homophilic L1-L1 and integrin-mediated cell binding and can also bind with high affinity to the neural proteoglycan neurocan; however, the binding site is unknown. We have dissected the L1 molecule and investigated the cell binding ability of Ig domains 1 and 6. We report that RGD sites in domain 6 support alpha5beta1- or alphavbeta3-mediated integrin binding and that both RGD sites are essential. Cooperation of RGD sites with neighboring domains are necessary for alpha(5)beta(1). A T cell hybridoma and activated T cells could bind to L1 in the absence of RGDs. This binding was supported by Ig domain 1 and mediated by cell surface-exposed neurocan. Lymphoid and brain-derived neurocan were structurally similar. We also present evidence that a fusion protein of the Ig 1-like domain of L1 can bind to recombinant neurocan. Our results support the notion that L1 provides distinct cell binding sites that may serve in cell-cell or cell-matrix interactions.

Metalloproteinase-mediated release of the ectodomain of L1 adhesion molecule

The L1 adhesion molecule is an approx. 200–220 kDa type I membrane glycoprotein belonging to the immunoglobulin (Ig) superfamily. L1 can bind in a homotypic fashion and was shown to support integrin-mediated binding via RGDs in the 6th Ig-like domain. In addition to its cell-surface expression, L1 can occur in the extracellular matrix (ECM). Here we demonstrate that L1 is constitutively released from the cell surface by membrane-proximal cleavage. L1 shed from B16F10 melanoma cells remains intact and can serve as substrate for integrin-mediated cell adhesion and migration. The release of L1 occurs in mouse and human cells and is blocked by the metalloproteinase inhibitor TAPI (Immunex compound 3). This compound has been shown previously to block release of L-selectin and TNF-alpha which is mediated by the membrane-bound metalloproteinase TNF-alpha converting enzyme (TACE). Using CHO cells that are low in TACE expression and do not release L-selectin we demonstrate that L1 release is distinct from L-selectin shedding. We propose that cell-surface release may be necessary for the conversion of L1 from a membrane into an ECM protein.