Keratin 17 mutation in pachyonychia congenita type 2 with early onset sebaceous cysts

BACKGROUND

Pachyonychia congenita (PC) is a group of autosomal dominant ectodermal dysplasias caused by mutations in four differentiation-specific keratin genes. Two major clinical subtypes of PC have been generally recognized. Symmetrically thickened fingernails and toenails are the defining characteristic of PC type 2 (PC-2) with onset at infancy. Pilosebaceous cysts are the best hallmark of PC-2, but they usually occur at puberty.

OBJECTIVES

To report a Chinese pedigree of PC-2 with unusually early onset sebaceous cysts and to explore the genetic mutation and its phenotype.

METHODS

Exon 1 of keratin 17 was amplified by polymerase chain reaction (PCR) from genomic DNA from the three patients in the pedigree, the proband, his half-sister and his younger son, two unaffected members in the pedigree and 50 unrelated and unaffected people. PCR products were directly sequenced to detect the mutation.

RESULTS

Direct sequencing of the PCR products revealed a heterozygous 275A-->G mutation in all three affected members. This mutation predicts the substitution of asparagine by serine in codon 92 (N92S) located in the 1A domain of keratin 17.

CONCLUSIONS

Mutation in the 1A domain of keratin 17 underlies the affected members' phenotype, PC-2 with early onset sebaceous cysts and late-onset thickened fingernails and toenails. The onset of the cysts is very early in some people within this family and the age at onset of thickened fingernails and toenails is variable within the family, implying the existence of modifying factors.

Discovery and development of anticancer agents from plants

A novel in vitro assay for the discovery of anticancer agents was used to examine aqueous and organic extracts from 1847 plants collected mainly in the U.S. Southwest and West. The assay results were separated into 5 categories: inactive (62%), equally active (36%), equally active and potent (0.5%), solid tumor selective (1.4%), and human selective (0.8%). Extracts from the latter three categories were fractionated using the in vitro assay to biodirect each step. Psorothamnus emoryi extracts were solid tumor selective and yielded two active compounds upon fractionation: dalrubone and 5-methoxydalrubone. Calocedrus decurrens was equally active and potent and yielded deoxypodophyllotoxin as the active compound. Linanthus floribundus was human selective and yielded strophanthidin as the active compound. The potential of this assay to discover novel anticancer agents from the active extracts is discussed.

Sub-Angstrom high-resolution transmission electron microscopy at 300 keV

Sub-Angstrom transmission electron microscopy has been achieved at the National Center for Electron Microscopy (NCEM) by a one-Angstrom microscope (OAM) project using software and enhanced hardware developed within a Brite-Euram project (Ultramicroscopy 64 (1996) 1). The NCEM OAM provides materials scientists with transmission electron microscopy at a resolution better than 1 A by using extensive image reconstruction to exploit the significantly higher information limit of an FEG-TEM over its Scherzer resolution limit. Reconstruction methods chosen used off-axis holograms and focal series of underfocused images. Measured values of coherence parameters predict an information limit of 0.78 A. Images from a [1 1 0] diamond test specimen show that sub-Angstrom resolution of 0.89 A has been achieved with the OAM using focal series reconstruction.

Glutamine metabolism in sepsis and infection

Severe infection causes marked derangements in the flow of glutamine among organs, and these changes are accompanied by significant alterations in regional cell membrane transport and intracellular glutamine metabolism. Skeletal muscle, the major repository of glutamine, exhibits a twofold increase in glutamine release during infection, which is associated with a significant increase in endogenous glutamine biosynthesis. Despite an increase in glutamine synthetase activity in skeletal muscle, the intracellular glutamine pool becomes depleted, indicating that release rates exceed rates of synthesis. Simultaneously, the circulating pool of glutamine does not increase, indicating accelerated uptake by other organs. The liver appears to be the major organ of glutamine uptake in severe infection; studies in endotoxemic rodents have shown net hepatic glutamine uptake to increase by as much as 8- to 10-fold. This increase is due partially to increases in liver blood flow, but also to a three- to fourfold increase in hepatocyte System N activity in the liver. Cytokines and glucocorticoids mediate the increased uptake of glutamine by the liver in septic states as well as other compounds. Sepsis does not appear to induce an increase in System N gene expression, indicating that the increase in hepatic glutamine transport observed during severe infection is probably regulated at the protein level. The bowel displays a decrease in glutamine utilization during sepsis, a response that may be related to the decrease in circulating insulin-like growth factor-1 (IGF-1) levels that is characteristic of sepsis. Recent studies suggest that IGF-1 has a direct effect on stimulating glutamine transport across the gut lumen and thus may represent a therapeutic avenue for improving gut nutrition during severe infection. The cells of the immune system (lymphocytes, macrophages) are also major glutamine consumers during inflammatory states in which cell proliferation is increased. Under these conditions, glutamine availability can become rate limiting for key cell functions, such as phagocytosis and antibody production.

The triple threat to nascent apolipoprotein B. Evidence for multiple, distinct degradative pathways

We previously showed that Omega-3 fatty acids reduce secretion of apolipoprotein B (apoB) from cultured hepatocytes by stimulating post-translational degradation. In this report, we now characterize this process, particularly in regard to the two known processes that degrade newly synthesized apoB, endoplasmic reticulum (ER)-associated degradation and re-uptake from the cell surface. First, we found that Omega-3-induced degradation preferentially reduces the secretion of large, assembled apoB-lipoprotein particles, and apoB polypeptide length is not a determinant. Second, based on several experimental approaches, ER-associated degradation is not involved. Third, re-uptake, the only process known to destroy fully assembled nascent lipoproteins, was clearly active in primary hepatocytes, but Omega-3-induced degradation of apoB continued even when re-uptake was blocked. Cell fractionation showed that Omega-3 fatty acids induced a striking loss of apoB100 from the Golgi, while sparing apoB100 in the ER, indicating a post-ER process. To determine the signaling involved, we used wortmannin, a phosphatidylinositol 3-kinase (PI3K) inhibitor, which blocked most, if not all, of the Omega-3 fatty acid effect. Therefore, nascent apoB is subject to ER-associated degradation, re-uptake, and a third distinct degradative pathway that appears to target lipoproteins after considerable assembly and involves a post-ER compartment and PI3K signaling. Physiologic, pathophysiologic, and pharmacologic regulation of net apoB secretion may involve alterations in any of these three degradative steps.

In situ transmission electron microscopy studies and real-time digital imaging

A newly designed CCD camera has been utilized for real-time and static image acquisitions. The performance of the camera is demonstrated for heating/cooling in-situ TEM experiments performed on a commercial high strength aluminium alloy using a double tilt heating holder. The real-time digital imaging capability of the new camera should facilitate the in-situ TEM that is now re-establishing itself as a strategic tool for materials characterization.

A role for calnexin in the assembly of the MHC class I loading complex in the endoplasmic reticulum

Heterodimers of MHC class I glycoprotein and beta(2)-microglobulin (beta(2)m) bind short peptides in the endoplasmic reticulum (ER). Before peptide binding these molecules form part of a multisubunit loading complex that also contains the two subunits of the TAP, the transmembrane glycoprotein tapasin, the soluble chaperone calreticulin, and the thiol oxidoreductase ERp57. We have investigated the assembly of the loading complex and provide evidence that after TAP and tapasin associate with each other, the transmembrane chaperone calnexin and ERp57 bind to the TAP-tapasin complex to generate an intermediate. These interactions are independent of the N:-linked glycan of tapasin, but require its transmembrane and/or cytoplasmic domain. This intermediate complex binds MHC class I-beta(2)m dimers, an event accompanied by the loss of calnexin and the acquisition of calreticulin, generating the MHC class I loading complex. Peptide binding then induces the dissociation of MHC class I-beta(2)m dimers, which can be transported to the cell surface.

Genome sequence of Halobacterium species NRC-1

We report the complete sequence of an extreme halophile, Halobacterium sp. NRC-1, harboring a dynamic 2,571,010-bp genome containing 91 insertion sequences representing 12 families and organized into a large chromosome and 2 related minichromosomes. The Halobacterium NRC-1 genome codes for 2,630 predicted proteins, 36% of which are unrelated to any previously reported. Analysis of the genome sequence shows the presence of pathways for uptake and utilization of amino acids, active sodium-proton antiporter and potassium uptake systems, sophisticated photosensory and signal transduction pathways, and DNA replication, transcription, and translation systems resembling more complex eukaryotic organisms. Whole proteome comparisons show the definite archaeal nature of this halophile with additional similarities to the Gram-positive Bacillus subtilis and other bacteria. The ease of culturing Halobacterium and the availability of methods for its genetic manipulation in the laboratory, including construction of gene knockouts and replacements, indicate this halophile can serve as an excellent model system among the archaea.

Transcatheter occlusion of complex atrial septal defects

Percutaneous device occlusion of secundum atrial septal defects (ASDs) is becoming an accepted alternative to surgical closure. This method allows us to evaluate patients with complex conditions for treatment. From a total of 70 patients with ASD evaluated for percutaneous closure, we selected for analysis 28 who had complex conditions. The mean age was 36+/-23 yr (range, 4-72). Six had heart failure, and of these six, three had atrial fibrillation. At cardiac catheterization, the pulmonary pressure was 47+/-24 mm Hg, and the QP/QS was 1.7+/-0.4; two patients had bidirectional shunt and systemic pulmonary pressure. Two patients received a buttoned device and 26 an Amplatzer septal occluder. The groups of patients with complex conditions were separated into the following groups. Group I (n = 4) underwent combined treatment of associated anomalies. Two patients had pulmonary stenosis, one had mitral stenosis, and one had an aortic root-left atrium fistula. They were treated in or during with the same procedure by combined transcatheter techniques (balloon valvuloplasty and fistula occlusion) before ASD occlusion. Group II (n = 9) had multiple defects (cribiform or two separate holes). They were treated with a single device in five instances and with two separate devices in four cases. Group III (n = 14) had large (32+/-3 mm) single defects. Nine of them underwent successful implantation using a device 33+/-3 mm in diameter; in the remaining five patients the device was removed because of instability. Group IV (n = 3) had residual defects after previous partial device occlusion. All three defects were successfully occluded with a second device. No movement or interference with the first device was observed. Group V (n = 6) had severe pulmonary hypertension (86+/-16 mm Hg). Immediately after ASD occlusion we observed significant relief in these patients (67+/-14 mm Hg; P<0.01). There were no major complications; all 23 patients with successful implants were discharged without symptoms 2-7 days later; one patient with atrial fibrillation recovered sinus rhythm. The follow-up (8+/-5 mo) Doppler echo study showed complete ASD occlusion in 22 patients and a peak pulmonary pressure of 30+/-14 mm Hg. We conclude that transcatheter occlusion of ASDs is an effective and safe treatment for patients with complex anatomic or physiopathologic conditions, as evaluated by short-term follow-up.

Inhibition of translocation of nascent apolipoprotein B across the endoplasmic reticulum membrane is associated with selective inhibition of the synthesis of apolipoprotein B

In HepG2 cells, inhibition of apolipoprotein B100 (apoB) translocation across the endoplasmic reticulum by an microsomal triglyceride transfer protein (MTP) inhibitor (CP-10447) in the presence of N-acetyl-leucinyl-norleucinal, a proteasomal inhibitor, results in accumulation of newly synthesized apoB in the translocation channel. Here we demonstrated that such accumulation led to a specific reduction of apoB synthesis. ApoB mRNA levels remained unchanged, but we observed reduced rates of elongation of nascent apoB in puromycin-synchronized cells pretreated with MTP inhibitor. This observation was consistent with a longer half-ribosome transit time for the synthesis of apoB in MTP-inhibited cells. Initiation of translation of apoB mRNA was not impaired by MTP inhibition. Overall, these findings suggest that translocation arrest of apoB in the endoplasmic reticulum channel can exert a selective and negative effect on the synthesis of apoB at the stage of elongation.

[Multivariate analysis of prognostic factors in renal cell carcinoma]

OBJECTIVE

To assess the effect of prognostic factors on renal cell carcinoma (RCC).

METHODS

316 cases of RCC were reviewed retrospectively. Their survival rates were calculated by Kaplan-Meier method and statistical differences were determined by Log-rank test. Significant prognostic factors were evaluated by Cox's multivariate proportional hazard model.

RESULTS

After 40.3 +/- 18.5 month follow-up, the overall 5-year survival rate was 62.3%. By multivariate analysis, nine factors were included in Cox's multivariate proportional hazard model. M was the most important prognostic factor in RCC (P = 0.0013), and the others in turn were T (P = 0.0182), age (P = 0.0347), performance status (P = 0.0423), N (P = 0.0471), lymphadenectomy (P = 0.0542), grade (P = 0.0775), serum albumin (P = 0.1536), and serum creatinine (P = 0.4543).

CONCLUSIONS

The significant prognostic factors in RCC were T, N, and M. Age and performance status showed the effect on prognosis of RCC. Lymph-node dissection also revealed a meaningful effect on relative lower stage of RCC.

[Evaluation of side-effects after 131I-therapy for differentiated thyroid carcinoma]

The purpose of this study was to evaluate the side-effects of differentiated thyroid carcinoma after treatment with 3.7-7.4 GBq of 131I. A total of 342 patients were treated with 131I from May, 1989 to January, 1999. The acute side-effects, the short-term and long-term side-effects were analyzed. The follow-up lasted 1-10 years with an average of 5.4 years. The results showed that thyroiditis occurred predominantly in the patients with a rate of 131I uptake > 30%, whereas sialoadenitis occurred more prevalently in the patients with a rate of 131I uptake < 30% (P < 0.001). The rates of nausea, vomiting, diarrhea and gastralgia were 12.2%, 5.2%, 3.5% and 2.7% respectively. There were no significant changes in the hemogram after treatment, compared against that before treatment. The overall rates of transient platelet abnormalities and leukopenia were 10.4% and 4.0% respectively, but the rates of the abnormalities in the patients with cumulative doses of 131I > 18.5 GBq were significantly higher than those in patients with cumulative doses of 131 I < 18.5 GBq. The lower rate of acute and short-term side-effects and the absence of long-term side-effects in this study indicate that 131I can be safely used to treat differentiated thyroid carcinoma.

Effects of deprivation of neonatal nerve growth factor on the expression of neurotrophin receptors and brain-derived neurotrophic factor by dental pulp afferents of the adult rat

The dental pulp is richly innervated by peptidergic nociceptive neurones that are of special interest because of their central role in dental pain and because they have some features that are not typical of other somatic nociceptors. Here, (35)S-riboprobes were used to determine whether pulpal afferents of adult (2-month-old) rats express the nerve growth-factor (NGF) receptors, p75(NTR) and trkA, which are characteristic of peptidergic nociceptors, and additionally, whether these cells express receptors (trkB and trkC) for other members of the neurotrophin family. In order to begin characterizing the postnatal role of NGF in regulating these neurones, the susceptibility of pulpal afferents to antiserum-mediated early postnatal NGF depletion spanning the period of pulpal innervation development was also examined. In control animals, about 200 trigeminal ganglion cells were labelled after application of the retrograde tracer Fluoro-gold to the first maxillary molar. Among the labelled cells, 79% had positive hybridization signals for p75(NTR), 72% for trkA, 34% for trkB, 1% for trkC, and 77% for BDNF. Neonatal NGF depletion reduced the number of retrogradely labelled pulpal afferents by 33%, with numbers of smaller neurones being most strikingly subnormal. This reduction could be attributed to a partial depletion of the neurone population that expressed p75(NTR) and trkA. Consistent with reports that NGF-responsive neurones also express BDNF, NGF deprivation resulted in a reduction in the number of pulpal afferents that expressed BDNF to an extent similar to that seen for trkA. In contrast, anti-NGF exposure had little effect on the number of pulpal afferents that expressed trkB. These findings indicate that most pulpal afferents in the adult express the NGF receptors p75(NTR) and trkA, and thus have a continuing potential susceptibility to NGF-mediated regulation of functions such as neuropeptide and BDNF synthesis. However, only a subpopulation of this group of neurones requires NGF in order to develop connections to the pulp during the neonatal period. Few, if any, pulpal afferents express the high-affinity neurotrophin-3 (NT3) receptor trkC, although many have large cell bodies typical of NT3-responsive sensory neurones. A small subpopulation of pulpal afferents seems to express no neurotrophin receptors, yet it is unlikely that these cells belong to the class of small sensory cells known to bind isolectin IB4.

Percutaneous balloon-expandable stents for sealing of acute aortic dissection

Acute aortic dissection is a highly lethal disease. When dissection involves only the descending aorta and there are no ischemic complications, medical management may be the treatment of choice. However, a high risk of expansion or rupture of the dissection remains. When renal or limb ischemic complications do appear, surgery has been the only option, despite high mortality and morbidity. Percutaneous placement of stents for sealing an acute aortic dissection might be an alternative to surgical treatment. We treated 2 patients with acute type B aortic dissection by stent-fixation of the proximal and distal descending aorta. In both patients, there was evidence of persistent flap fixation at midterm follow-up.

Course and composition of the nerves that supply the mandibular teeth of the rat

The rodent dentition has become an important model for investigations of interactions between dental tissues and peripheral neurons. Although experimental nerve injury has been widely used for such studies, there is uncertainty about the courses of nerve fibers supplying the mandibular teeth. In order to clarify this, we used a mixture of monoclonal antibodies against neurofilament proteins to enhance demonstration of nerve fibers so that small nerves could be readily traced in serial frozen sections of mandibles of Sprague Dawley rats ranging in age from embryonic day (E) 18 to postnatal day (P) 90. The 1st molar and anterior portion of the 2nd molar were innervated by small nerves that emerged as distinct branches of the IAN trunk at or near the mandibular foramen. In contrast, the nerve supply to the 3rd molar and posterior part of the 2nd molar was a branch of the lingual nerve that bypassed the mandibular canal altogether. The IAN trunk split into the mental nerve and a large branch to the incisor about 2 mm anterior to the mandibular foramen. Thick branches of the incisor nerve descended into the incisor socket to form a dense plexus of nerve fiber bundles extending along the length of the incisor periodontium. The sparse pulpal innervation of the incisor was provided by a few thin fascicles that emerged from the caudal portion of the periodontal plexus to enter the incisor apex. The dental branches of the IAN and lingual nerve seen in the adult were well established and readily identifiable at age E18 even though their targets were limited to the follicles of the developing teeth. These studies show that the trigeminal branches that supply the mandibular teeth can be identified at a wide range of ages as distinct nerves at a considerable distance proximal to their targets. This detailed information on the courses taken by the dental nerves can provide an anatomical basis for increased precision in characterization and perturbation of neural pathways from the molars and incisor.

Simple and complex stent strategies for bifurcated coronary arterial stenosis involving the side branch origin

Coronary lesions located in major bifurcations constitute a challenge for the use of stents. Although the occlusion of a side branch covered by a stent is infrequent, the maintenance of a patent, stenosis-free bifurcation may result in a complex procedure. Between September 1994 and April 1998, 70 patients were treated by stent implantation for coronary bifurcation stenosis. The side branch always had a diameter >2 mm. The pairs of treated arteries were: left anterior descending (LAD)/diagonal artery in 32 patients, circumflex/obtuse marginal in 26, right coronary/posterior descending artery in 5, and LAD/circumflex in 7. We applied 2 different techniques of stent implantation: (1) deployment of 1 stent in the parent vessel covering the takeoff of the side branch and subsequent angioplasty of the side branch across the metallic structure (group A, n = 47 patients), and (2) implantation of 1 stent at the ostium of the side branch and complete reconstruction of the entire bifurcation with additional implantation of 1 or 2 stents at the parent vessel (group B, n = 23 patients). There were no significant differences between groups at baseline variables. Procedural success was similar in both groups: 42 (89%) in group A versus 21 (91%) in group B. However, major cardiac events at 18 months follow-up were higher in group B (event-free probability 44% vs 75%, p <0.05). Selected patients with coronary stenosis at major bifurcations can be treated with an acceptable rate of primary and late success. Complex techniques providing radical stent reconstruction of the bifurcation seems to provide no advantages over the simpler stent jail followed by ostial side branch balloon dilation.

[Coronary angioplasty: always a stent in arteries larger than 2.5 mm? The arguments pro]

Coronary stenting has provided better results than balloon angioplasty in terms of primary success and restenosis in previous randomized studies. These studies only included short coronary lesions located in vessels larger than 3 mm. Thus, these results can not be applied to complex lesions or those located in small vessels. In the present article we summarize our points of view regarding the current indications of coronary stenting in these types of lesions, where the use of this device may be still controversial. In all these situations the results of the stent seem to be better to those previously reported with balloon angioplasty. However, there is a percentage of patients treated by balloon angioplasty in whom a good immediate and long-term result can be obtained. The identification of patients with optimal result after balloon angioplasty need a postprocedure study of coronary flow reserve. The comparison of optimal balloon angioplasty (by angiographic and coronary flow reserve criteria) and stent, is the main objective of 2 studies that are currently under process. We will have to wait the results of these clinical trials to answer to the question if the implant of stents in all kind of lesions located in vessel larger than 2.5 mm is of proper use. Our current opinion is that coronary stenting is a safe and fast method of coronary transcatheter therapy in many types of coronary lesions and it may be considered the more efficient technique of percutaneous revascularization.

Immediate and follow-up findings after stent treatment for severe coarctation of aorta

Experimental studies have shown that stents implanted at the aorta become incorporated within the aortic wall and can be further expanded in growing animals. Few clinical studies have shown that the stent repair of severe coarctation of aorta provides excellent initial results, and little is known on the follow-up of these patients. We assessed the immediate and follow-up results obtained in a series of 48 patients (mean age 14+/-12 years) with severe coarctation of the aorta who were treated by Palmaz stent implantation; 30 of them (63%) underwent angiographic follow-up studies at a mean of 25+/-11 months after treatment. Quantitative serial analysis of the aortogram (baseline, after treatment, and at follow-up) was performed. Significant relief (mean residual gradient 3+/-4 mm Hg) was always obtained after stent implantation. The isthmus, when hypoplastic (60%), was always expanded with the stent. One associated aneurysm became occluded after the implant. Complications included aortic disruption, stent migration, and decreased or absent femoral pulses. At angiographic follow-up, the stent remained always in place, without recoil. In 22 patients (73%), there were no detectable neointimal proliferation at late angiogram; however, 8 patients (27%) had some degree of intimal thickening (1 to 5 mm), causing mild restenosis in 3 patients treated at early age, and nonsignificant lumen reduction in 5. The serial aortogram analysis revealed a minor but significant increase in nonstented aortic diameters that seemed related to the normal growth of children. No need for stent reexpansion was observed at 2-year follow-up (mean). Two patients (7%) developed late small aneurysm formation at the stented wall; both were occluded by the insertion of coils through the stent orifices. We conclude that stent treatment for severe coarctation of aorta provides excellent immediate and long-term results in young adults and children. However, at early age, restenosis by intimal growth may develop.

Neurotrophin receptor expression is induced in a subpopulation of trigeminal neurons that label by retrograde transport of NGF or fluoro-gold following tooth injury

Tissue responses to injury are regulated by neurotrophins and neurotrophin receptor levels and can involve both retrograde and paracrine/autocrine trophic signaling. To determine how neurotrophins may contribute to the injury response, the timing and the extent of the up-regulation of neurotrophins and their receptors was examined in a model system which is particularly well suited for the analysis of trophic signaling pathways in response to injury. Injury to the occlusal surfaces of rat molar cusps induces a localized increase in nerve growth factor (NGF) expression in the dental pulp within 4-6 h. Radiolabeled NGF was transported in a receptor-mediated fashion from the teeth to a subset of neurons in the trigeminal ganglion within 15 h, indicating that these neurons possess NGF receptors (trk A and/or p75NTR). To test for NGF responses in the tooth sensory afferent neurons, levels of expression of neurotrophins and their receptors were examined by in situ hybridization in the trigeminal ganglion at 0, 4, 12, 20, 28 and 52 h post-injury. Within the maxillary division of the trigeminal ganglion, trk A expression was elevated at 4 h post-injury, with a maximum increase (2-fold) after 52 h. p75NTR was increased by 28 h post-injury and was increased 1.35-fold by 52 h. BDNF mRNA was increased 12 h after injury (1.8-fold), and 2.5-3-fold at 52 h post-injury. The trk B expression was increased only late after injury (28 and 52 h). To determine the receptor/neurotrophin phenotype of trigeminal neurons with projections to the molar teeth, these neurons were double-labeled with the retrograde tracer fluoro-gold and probes for either BDNF or trk B. The results show that tooth-innervating trigeminal neurons express BDNF, but not trk B. The timing of mRNA expression after injury and the phenotype of identified trigeminal neurons suggests a complex signaling cascade in which NGF at the injury site regulates NGF receptor expression at the levels of the cell body as well as increases in BDNF expression. Upregulated BDNF may act in a paracrine fashion on neighboring trigeminal cells expressing trk B. This signaling cascade may be a common feature of the response to mild peripheral inflammatory injuries within nociceptive pathways.

The tetraspan protein CD82 is a resident of MHC class II compartments where it associates with HLA-DR, -DM, and -DO molecules

In specialized APCs, MHC class II molecules are synthesized in the endoplasmic reticulum and transported through the Golgi apparatus to organelles of the endocytic pathway collectively called MHC class II compartments (MIICs). There, the class II-associated invariant chain is degraded, and peptides derived from internalized Ag bind to empty class II in a reaction that is facilitated by the class II-like molecule HLA-DM. An mAb raised to highly purified, immunoisolated MIICs from human B lymphoblastoid cells recognized CD82, a member of the tetraspan family of integral membrane proteins. Subcellular fractionation, immunofluorescence microscopy, and immunoelectron microscopy showed that CD82 is highly enriched in MIICs, particularly in their internal membranes. Coprecipitation analysis showed that CD82 associates in MIICs with class II, DM, and HLA-DO (an inhibitor of peptide loading that binds DM). Similar experiments showed CD63, another tetraspan protein found in MIICs, also associates with these molecules in the compartment and that CD82 and CD63 associate with each other. Preclearing experiments demonstrated that both CD82 and CD63 form complexes with DM-associated class II and DM-associated DO. The ability of CD82 and CD63 to form complexes with class II, DM, and DO in MIICs suggests that the tetraspan proteins may play an important role in the late stages of MHC class II maturation.

Intracellular formation and cell surface expression of a complex of an intact lysosomal protein and MHC class II molecules

The generation of invariant chain-free MHC class II molecules and their association with endocytically generated peptides are thought to occur in specialized lysosome-like compartments called MIICs (MHC class II compartments). A number of in vitro studies have shown that large denatured proteins can bind to class II molecules, and that class II association can protect the bound segment of protein from proteolytic degradation. In this work, we present what we believe is the first example of an intact endogenous protein (IP30) binding in an allele-dependent fashion to class II molecules in vivo. IP30 is an IFN-gamma-inducible 35-kDa glycoprotein that localizes in MIICs. In this study, we show that intact IP30 binds to certain HLA-DR alleles via an N-terminal prosequence. The association takes place in the endocytic pathway following removal of invariant chain from class II molecules and before their cell surface expression. We also show that DR-IP30 complexes are SDS stable. The potential precursor-product relationship between DR-IP30 complexes and the DR-peptide complex is discussed.

[Autologous endothelial cell transplantation in meacacos]

OBJECTIVE

To lay a theoretical foundation for the clinical application of autologous endothelial cell transplantation.

METHODS

Macaco endothelial cells derived from superficial veins were cultivated in vitro for 13.89 +/- 1.36 days. The multiplied cells were lined in vitro onto the luminal surface of expanded polytetrafluoroethylene (ePTFE) grafts precoated with fibrin glue and fibronectin, then cultivated further for 9 days. 15 macacos were divided randomly into two groups. The common iliac arteries of the exper mental animals (n = 10) were replaced with endothelialized grafts, those of control (n = 5) with untreated ones.

RESULTS

The amount of endothelial cells increased for 147.93 +/- 88.68 folds. All the cells were diploid cells with a purity of 99%. The content of both 6-keto-PGF1a and vWF in the supernatant of primary and subcultured passages didn't have significant difference. Two hours and 9 days after cell seeding, the luminal surface of grafts were covered completely by a prominent, spindle-like endothelial monolayer underneath an even fibrin glue matrix could be seen. Nine days after seeding, the dense condensation of cytoskeleton on the luminal and basal side of cells increased apparently. Four weeks after grafts implantation 8/10 of experimental grafts, with a thickness of intima 80 +/- 12 microns, were patent; while the 5 control grafts were occluded.

CONCLUSION

The endothelial cell transplantation could effectively increase the patency rate of synthetic blood vessel prosthesis.

In-laboratory removal of femoral sheath following protamine administration in patients having intracoronary stent implantation

Two hundred twenty-eight patients with successful coronary stent implantation were randomized either to protamine administration and femoral sheath removal (group I, n = 117) or no heparin neutralization and delayed sheath removal (group II, n = 111). The hospital stay after treatment was shorter in patients receiving protamine; therefore, protamine use for neutralizing circulating heparin may be safely administered immediately after stent implantation.

Identification of nonprotein amino acids from cycad seeds as N-ethoxycarbonyl ethyl ester derivatives by positive chemical-ionization gas chromatography-mass spectrometry

Nonprotein amino acids from nine species of cycad seeds were analyzed as N-ethoxycarbonyl ethyl ester (ECEE) derivatives by positive chemical-ionization gas chromatography-mass spectrometry. Based on the retention times and mass spectrometry analyses, 12 nonprotein amino acids were identified in these seeds. In addition to the excitatory and putative neurotoxin beta-N-methylamino-L-alanine (BMAA), the known neurotoxin beta-N-oxalylamino-L-alanine (BOAA) was detected from the seeds of Macrozamia moorei and M. communis, and delta-N-oxalyl-ornithine was obtained from the Cycas revoluta seeds. A novel nonprotein amino acid named cycasindene, previously reported from C. revoluta, was also found in the seeds of members of the C. angulata and C. rumphii complex. Eight additional known nonprotein amino acids were also identified. This is the first report of the neurotoxin BOAA from cycad seeds.

Obliteration of femoral pseudoaneurysm complicating coronary intervention by direct puncture and permanent or removable coil insertion

We report on percutaneous obliteration of femoral pseudoaneurysm complicating percutaneous coronary interventions in 6 patients. Our findings suggest that permanent or transient direct coil insertion may be an useful alternative in the treatment of pseudoaneurysm in patients who do not respond to mechanical compression.

Nonprotein amino acids from Cycas revoluta

Two nonprotein amino acids, cycasindene and cycasthioamide, along with eight known nonprotein amino acids, were isolated from the seeds of Cycas revoluta Thunb. The structures of cycasindene and cycasthioamide were elucidated as 3-[3'-amino-indenyl-2]-alanine (1) and N-[glycinyl-alaninyl-11-thio]-5-one-pipecolic acid (2) by chemical and spectral methods.

Characterization of glutamine and glutamate transport in rat lung plasma membrane vesicles

Insufficient glutamine for the lungs during sepsis may contribute to an impairment in lung function. Lung glutamine metabolism is supported by both blood glutamine uptake and de novo biosynthesis using circulating glutamate as a precursor. Information regarding the specific plasma membrane carriers involved in this uptake is lacking. Furthermore, the effect of sepsis on amino acid transport in whole lung has not been studied. We isolated lung plasma membrane vesicles (LPMVs) from control and LPS-treated rats and assayed glutamine and glutamate transport activity in LPMVs. Vesicle purity and functionality were confirmed by time-dependent concentrative amino acid uptake in the presence of Na+, impoverishment of microsomal enzymes, and a 25-fold enrichment in the plasma membrane marker 5'-nucleotidase. Eighty percent of glutamine uptake in lung vesicles was mediated via the high affinity Na(+)-dependent carrier System ASC (Vmax = 80 +/- 10 pmole/mg protein/15 sec; Km = 224 +/- 30 microM) while 19% occurred via the Na(+)-independent System ASC (Vmax = 11 +/- 2 pmole/mg/15 sec; Km = 141 +/- 23 microM). Ninety percent of glutamate transport was mediated by the Na(+)-independent System XAG-. Treatment of rats with LPS resulted in a decrease in both glutamine and glutamate transport in LPMVs. LPMVs offer a novel method for characterizing lung amino acid transport and studying the effects of catabolic states on this activity. The effects of endotoxin on System ASC and XAG- activity may contribute to reduced lung glutamine availability during septic states which may impair cellular metabolism and function.

[Differential display analysis of human fetal brain mRNAs and isolation of brain-specific novel ESTs]

Using the differential display technique (DDRT-PCR) originally developed by Liang and Pardee, we tried to isolate the stage-specific or tissue-specific genes in the developing human neural system (brain). With about fifty sets of arbitrary primers and anchored primers, DDRT-PCR was carried out to analyze the differentially expressed mRNAs between human fetal brains of different developmental stage or different parts of human fetal brain at the same developmental stage. About one hundred bands containing cDNA fragments of differential interest were cut out from the polyacrylamide gel, thirty-four of which were cloned and sequenced. They were accepted as novel cDNA sequences by GeneBank. In order to check the feasibility of DDRT-PCR, three of the thirty-four cDNA sequences were randomly chosen as probes for further analysis by dot blot RNA hybridization, and two proved to be specifically expressed in human brain.

Angiographic predictors of neointimal thickening after successful coronary wall healing following percutaneous revascularization

This study was undertaken to characterize, by intracoronary ultrasound technique, the neointimal thickening at follow-up of treated coronary segments after successful arterial wall repair and to compare the findings with serial angiographic studies. We selected for study 81 patients with single-vessel coronary disease successfully treated by percutaneous revascularization who were angiographically and ultrasonically reevaluated at a mean follow-up time of 22 +/- 21 months; 23 had been treated by balloon angioplasty, 27 by directional atherectomy, and 31 by elective Palmaz-Schatz stent implantation. The late maximal neointimal thickness varied between 0.1 and 1.5 mm (mean 0.65 +/- 0.31 mm), and the neointimal area ranged between 0.97 and 14.9 mm2 (mean 5.19 +/- 3.14 mm2). The neointimal repair was thinner in patients who obtained a better acute angiographic result immediately after treatment and in stented (3.4 +/- 1.8 mm2) versus dilated (7.8 +/- 4.1 mm2) or resected (5 +/- 1.6 mm2, p < 0.001) segments. On the contrary, the repaired neointimal layer was thicker in those patients who angiographically exhibited less late luminal loss or even expansion and in those evaluated after a longer time since treatment. The acute gain and the time influence resulted in independent predictors of the degree of neointimal thickness. These findings suggest that two reparative mechanisms of the coronary wall may operate in close relation.

[Primary stent treatment in the acute phase of myocardial infaction]

INTRODUCTION

Although direct balloon angioplasty has emerged as an alternative to thrombolytic therapy in patients with acute myocardial infarction, reocclusion and restenosis rates are limiting factors. We postulated that these limitations could be partly overcome by primary stenting of the responsible lesion.

MATERIAL AND METHODS

Since January/94 we have studied 59 patients with acute myocardial infarction who were treated in the early phase (3.1 +/- 2 hours since the onset of symptoms) by elective Palmaz-Schatz stent implantation. No adjunctive thrombolytic therapy was associated. Two patients were in cardiogenic shock and were treated under percutaneous cardiopulmonary support. At cardiac catheterization a left ventriculography and coronary angiograms were obtained. Then, mechanical recanalization of the responsible lesion was performed. If the angiographic anatomy was considered suitable, a stent was implanted at the lesion.

RESULTS

The infarct related artery was the left anterior descending in 29 patients, the circumflex in 14 and the right coronary artery in 16. At baseline conditions, 40 patients had a totally occluded artery and 19 showed a TIMI-grande 1 antegrade flow. One patient had an early clinical recurrence 4 days later, which required an additional divided Palmaz-Schatz stent at the distal portion of the lesion, in order to seal a residual dissection. All remaining patients had a favourable clinical course without major complications. Immediately after treatment the minimal lumen diameter was 3.2 +/- 0.4 mm and no residual stenosis was detectable at the treated segment. Six-month angiographic reevaluation was performed in all 29 (49%) eligible patients. Restenosis (> 50% stenosis) was detected in 6 out of the 29 evaluated patients (21%).

CONCLUSIONS

Primary stent implantation in selected patients with an evolving myocardial infarction provides good initial and 6-month results.

Reduction of thrombotic and hemorrhagic complications after stent implantation

This study compared two consecutive antithrombotic strategies after Palmaz-Schatz stent implantation and involved 918 patients. Patients treated between May 1991 and May 1994 (group 1; n = 379) received aspirin, dipyridamole, and intravenous unfractionated heparin until oral anticoagulation was effective, between June 1994 and August 1995, 539 patients (group 2) were treated for 1 month with subcutaneous low-molecular-weight heparin (Fragmin), ticlopidine, and aspirin. There were no differences between the groups in terms of sex, clinical condition, vessel diameter, and severity and location of stenosis. Patients in group 1 were younger than those in group 2 (4% were > 70 years old compared with 12%, respectively; p < 0.01). Group 1 patients had more frequent unplanned stenting (48% vs 18%, respectively; p < 0.01) and fewer endoprostheses in the same artery than those in group 2 (1.1 +/- 0.5 vs 1.2 +/- 0.5, respectively; p < 0.01). Among group 2 patients, there was a significant reduction in thrombotic and hemorrhagic complications compared with group 1 patients. No subacute thrombosis occurred in patients in group 2 in contrast with a 5.8% incidence in patients in group 1 (p < 0.01). In addition, a lower incidence of groin and systemic bleeding was observed in patients in group 2 compared with patients in group 1 (2.6% vs 15%, respectively; p < 0.01). The association of low-molecular-weight heparin and antiplatelets provides a simpler antithrombotic strategy in patients treated with intracoronary stents and reduces the incidence of stent thrombosis and hemorrhagic complications. Our findings suggest that this antithrombotic regimen may prevent or completely avoid stent thrombosis.

[Directional coronary atherectomy in ostial lesions of the anterior descending coronary artery]

INTRODUCTION AND OBJECTIVES

Coronary stenoses at ostial level, when treated by balloon angioplasty, show a primary success rate much lower than those located in other parts of the coronary tree. Balloon dilation of lesions located at the left anterior descending ostium is associated with a high degree of restenosis, elastic recoil and the possibility of retrograde dissection to the left main coronary artery. Simpson atherectomy may be considered a percutaneous alternative in this particular location, since this technique produces fewer incidents of elastic recoil than balloon dilation. The purpose of the present study is to evaluate directional atherectomy in the treatment of patients with symptoms deriving from severe to stenosis at the origin of the left anterior descending artery.

MATERIAL AND METHODS

From a total number of 302 patients treated by Simpson atherectomy, we have analyzed 45 with severe stenosis at the left anterior descending ostium (less than 3 mm from its origin). The mean age was 54 +/- 12 years. Eighty two percent of the patients were male. The clinical condition was stable in unstable in 34; eleven had had a previous myocardial infarction. Six had multivessel coronary disease, all of them underwent combined balloon angioplasty of other segments. The treated lesion was native in 41 patients and previously dilated by balloon (restenosis) in 4. Two patients needed balloon predilation with 2 and 2.5 mm to facilitate the pass of the atherocatheter. The size of the Simpson atherocatheter was mainly 7F (78%). The weight of the resected arteriosclerotic material was 11 +/- 7 mg.

RESULTS

Primary success (residual stenosis < 40% without major complications) was obtained in 42 out of 45 patients (93%); 3 patients (7%) had major complications (1 death, 1 emergency surgery, and 1 non-Q wave myocardial infarction). A follow-up angiography study was available in 31 patients 7 +/- 8 months later. Restenosis was evidenced in 12 (39%).

CONCLUSIONS

Simpson atherectomy for left anterior descending artery ostial lesions is an effective transluminal alternative in selected patients providing a high rate of primary success (93%) and an acceptable restenosis rate (39%).

[Addison's disease in pregnancy: a report of six cases]

OBJECTIVE

To review six cases of pregnancy with Addison's disease at Obstetrics and Gynecology Hospital, Shanghai Medical University from 1949 to 1994.

METHOD

This is a clinical retrospective analysis. Five of the 6 patients were treated with hormone replacement therapy, and the remaining one received no hormone treatment due to lack of symptoms during pregnancy and neglect of previous adrenal surgery by obstetricians.

RESULTS

The patient received no treatment occurred Addisonian crisis and died soon after delivery. The other five patients had smooth course of delivery and postpartum period.

CONCLUSIONS

Hormone replacement therapy is important for patients with Addison's disease in pregnancy especially for acute decompensation of adrenal function. Pregnant women with history of adrenal surgery should be monitored carefully even without any symptoms and hormone treatment is necessary. Vaginal delivery is encouraged unless there is obstetric indication.

Trafficking of major histocompatibility complex class II molecules through intracellular compartments containing HLA-DM

The endosomal site(s) where MHC class II molecules become competent to bind antigenic peptide has not been completely characterized. We identified endocytic compartments through which newly synthesized MHC class II molecules move prior to their expression on the plasma membrane. The compartments co-sediment with lysosomes in the most dense regions of Percoll gradients. The appearance of proteolytic fragments of the invariant chain (I chain), namely leupeptin-induced proteins (LIPs) and class-II-associated invariant chain peptides (CLIP), in this region of the gradient suggests that the release of MHC class II molecules from I chain association occurs within these vesicles. The formation of SDS-stable alpha beta dimers indicated that MHC class II molecules contained within these compartments are receptive to peptide binding. A majority of the HLA-DM protein was found in the same region of the Percoll gradient, consistent with its established function in MHC class-II-restricted antigen presentation. Immunoelectron micrographs of dense-sedimenting compartments indicated that I chain, MHC class II, and DM molecules are contained within both multivesicular and multilamellar vesicles. The final stages of I chain dissociation from MHC class II molecules and DM-mediated peptide loading probably occur in these compartments.

Lipopolysaccharide and tumor necrosis factor stimulate lung microvascular arginine uptake, a response attenuated by dexamethasone

BACKGROUND

Lipopolysaccharide (LPS), tumor necrosis factor-alpha, (TNF), and glucocorticoids can modulate endothelial nitric oxide (NO) production. L-Arginine is the exclusive precursor for NO biosynthesis, suggesting that NO generation and arginine transport are intimately linked.

METHODS

To further study this relationship, we examined the effects of LPS, TNF, and dexamethasone (DEX) on arginine uptake by rat lung microvascular endothelial cells. The transport of radiolabeled arginine was assayed in confluent cells grown in 24-well plates.

RESULTS

The bulk (> 90%) of arginine transport was mediated by the Na(+)-independent carriers System y+ and System b0,+. Arginine transport was stimulated independently by LPS and TNF, a response first observed at 10 hours. Together, both agents exerted an additive effect on carrier-mediated uptake. The LPS- and TNF-induced increase in arginine transport activity was blocked by cycloheximide and actinomycin D, indicating the requirement for RNA and protein synthesis. The enhancement in transport activity was primarily due to an increase in Systems y+ maximal transport capacity (Vmax) with no change in transporter affinity and little change in System b0,+ activity. Treatment of cells with dexamethasone inhibited arginine transport activity in a time- and dose-dependent manner, an event that was abrogated by both actinomycin D and cycloheximide. The combination of DEX and LPS and TNF abrogated each other's antagonistic effects.

CONCLUSIONS

These data indicate that LPS and TNF additively stimulate arginine transport in lung microvascular endothelial cells via a pathway that requires de novo protein synthesis (possibly of the transporter protein itself) and that this response is attenuated by DEX.

Inhibition of pulmonary microvascular endothelial glutamine transport by glucocorticoids and endotoxin

BACKGROUND

During septic states, the lungs produce increased amounts of glutamine, an event that is mediated by both endotoxin and glucocorticoid hormones and is presumed to be due to accelerated intracellular glutamine biosynthesis. Because enhanced net glutamine release in vivo could also be due to a decrease in cellular uptake, we assayed glutamine transport in cultured rat microvascular pulmonary endothelial cells.

METHODS

The effect of Escherichia coli endotoxin (LPS, 1 microgram/mL), various cytokines, and dexamethasone (DEX, 0.1 mumol/L) on glutamine transport activity was studied in rat lung microvascular endothelial cells grown in varying glutamine concentrations (0, 0.1, 0.5, and 2 mmol/L). Experiments were also performed in cells treated with cycloheximide, actinomycin D, or chelerythrine chloride.

RESULTS

More than 90% of glutamine transport was mediated by the Na+ -dependent transport system ASC. DEX and LPS inhibited endothelial glutamine uptake in a time- and dose-dependent manner, a response that was only observed with incubation medium contained the lower concentrations of glutamine. Neither DEX nor LPS altered transport activity in cells cultured in medium containing 2 mmol glutamine/L. There was no synergistic or additive effect when both compounds were added together. The cytokines tumor necrosis factor alpha, interleukin (IL) 1, IL-2, and IL-6 did not alter glutamine transport. both DEX and LPS inhibited glutamine transport by decreasing transporter maximal transport velocity (Vmax) without affecting transporter affinity (Km). Cycloheximide and actinomycin D abrogated the inhibition of transport activity that was observed in DEX- or LPS-treated cells, whereas the protein kinase C inhibitor chelerythrine chloride had no effect on either control or stimulated glutamine transport.

CONCLUSIONS

These data suggest that DEX and LPS "down-regulate" glutamine uptake by lung microvascular endothelial cells by inducing the synthesis of an inhibitory protein that modulates the activity of the system ASC protein. This response in vitro appears to be influenced by the extracellular glutamine concentration. This decrease in microvascular endothelial glutamine transport may be one mechanism by which net lung glutamine release is enhanced during critical illness.

Protein kinase C-dependent regulation of L-arginine transport activity in Caco-2 intestinal cells

The regulation of plasma membrane L-arginine transport activity was investigated in differentiated and undifferentiated states of the human intestinal cell line, Caco-2. The sodium-independent, leucine-insensitive uptake of L-arginine measured in this study has been assigned by us previously to system y+ in Caco-2 cells. Treatment of cells with serum-free media containing epidermal growth factor (EGF), transforming growth factor alpha (TGF alpha), or the protein kinase C (PKC) activator 12-O-tetradecanoylphorbol 13-acetate (TPA), stimulated system y+ arginine transport activity in Caco-2 cells. Transport upregulation by these growth factors or by TPA was blocked by cycloheximide or the PKC inhibitor chelerythrine. Arginine uptake was diminished during the course of differentiation, attributable to a reduction in the transport system y+ capacity (Vmax) with no change in apparent affinity (Km). TPA stimulated arginine uptake required at least 3 h of continual exposure, and increased the membrane's transport capacity (Vmax) in both undifferentiated and differentiated cells. TPA elevated the diminished transport Vmax of differentiated cells TPA to the elevated Vmax value associated with undifferentiated cells. We conclude that upregulation of arginine transport is part of a pleiotropic response to EGF/TGF alpha, and that this involves PKC and de novo synthesis of polypeptides associated with system y+ transport activity.

Amino acid metabolism and the vascular endothelium: regulation and disease implications

Amino acid metabolism by the vascular endothelium is a complex process that often begins with the carrier-mediated uptake of circulating amino acids into the endothelial cytoplasm. Amino acids are essential for maintaining intact endothelial functions, which include cell proliferation, regulation of blood flow and vascular tone, coagulation and fibrinolysis, and metabolism of a variety of macromolecules. The disturbances in endothelial amino acid transport and metabolism that occur during infection and inflammation are due, in part, to changes in substrate availability and to the local and/or systemic elaboration of specific mediators. An improved understanding of endothelial amino acid metabolism will not only provide new knowledge regarding disease mechanisms and regulation, but may also lead to new treatment strategies that may include the clinical use of specific nutritional formulas.

Protein kinase C activation inhibits glutamate transport by endothelial cells

The role of protein kinase C (PKC) in regulating endothelial cell glutamate transport was investigated. Glutamate transport studies were performed in confluent human umbilical vein endothelial cells which were treated with the phorbol ester 12-myristate 13-acetate (TPA, 0-1000 nM), a compound which directly activates PKC. TPA inhibited Na(+)-independent System xAG- glutamate transport by 70% but only slightly reduced Na(+)-dependent activity. The TPA-mediated reduction in transport activity was dose-dependent, beginning at 5 min and lasting for at least 24 hr. TPA inhibition of glutamate transport had two distinctive phases: an acute phase (< 1 hr, not affected by either cycloheximide or actinomycin D) in which TPA decreased System xAG- glutamate transporter affinity (TPA Km = 522 +/- 25 microM vs control Km = 329 +/- 85 microM, P < 0.01) but did not alter transporter capacity (TPA Vmax = 4426 +/- 230 pmole/mg/min vs control Vmax = 4535 +/- 750 pmole/mg/min, P = NS) and a chronic phase (4-24 hr) in which TPA inhibition of glutamate transport was due to a reduced transporter capacity (Vmax = 2895 +/- 570 pmole/mg/min) without altering transporter affinity (Km = 370 +/- 60 microM glutamate) and was abrogated by cycloheximide or actinomycin D. The protein kinase C inhibitor chelerythrine chloride abrogated TPA's inhibition effect in both the acute and chronic phases. These data indicate that protein kinase C activation decreases glutamate transport in human umbilical vein endothelial cells via protein synthesis dependent and independent mechanisms.

Tumor necrosis factor stimulates system XAG- transport activity in human endothelium

System xAG- is responsible for the carrier-mediated Na(+)-independent transport of anionic amino acids such as glutamate and aspartate across the plasma membrane of cells. In order to examine a possible role for cytokines in regulating System xAG- activity, the effect of TNF on [3H]glutamate transport in cultured human umbilical vein endothelial cells (HUVECs) was studied. Carrier-mediated glutamate uptake was accomplished by two high-affinity carriers, predominantly by a Na(+)-independent carrier (System xAG-, 75% of total glutamate uptake) and, to a lesser extent by a Na(+)-dependent carrier (System XAG-, 24% of total uptake). TNF treatment (10 ng/ml for 10 hr) resulted in an 80% increase in Na(+)-independent glutamate transport activity with no change in System XAG- activity. The TNF stimulatory effect was blocked by actinomycin D and cycloheximide. TNF treatment increased System xAG- glutamate transporter Vmax by 51% (control Vmax = 2359 +/- 345 pmole/mg protein/min vs TNF Vmax = 3569 +/- 436 pmole/mg protein/min, P < 0.01) without altering transporter affinity (control Km, 229 +/- 40 microM glutamate vs TNF Km = 224 +/- 60 microM glutamate, P = NS). The protein kinase C (PKC) inhibitor chelerythrine chloride had no effect on the TNF-stimulated glutamate transport, indicating that the augmented glutamate transport was not mediated by PKC activation. These data indicate that the TNF-stimulated glutamate transport in HUVECs requires do novo protein synthesis, possibly of the System xAG- transporter protein itself. Accelerated glutamate transport provides a precursor for the biosynthesis of macromolecules and glutamine.