Age-related bias in function of natural killer T cells and granulocytes after stress: reciprocal association of steroid hormones and sympathetic nerves

Stress-associated immune responses were compared between young (8 weeks of age) and old (56 weeks) mice. Since stress suppresses the conventional immune system (i.e. T and B cells) but inversely activates the primordial immune system (i.e. extrathymic T cells, NKT cells, and granulocytes), these parameters were analysed after restraint stress for 24 h. The thymus became atrophic as a function of age, and an age-related increase in the number of lymphocytes was seen in the liver. Although the number of lymphocytes in both the thymus and liver decreased as the result of stress, the magnitude was much more prominent in the thymus. To determine stress-resistant lymphocyte subsets, two-colour immunofluorescence tests were conducted in the liver and spleen. NKT cells were found to be such cells in the liver of young mice. On the other hand, an infiltration of granulocytes due to stress was more prominent in the liver of old mice than in young mice. Liver injury as a result of stress was prominent in young mice. This age-related bias in the function of NKT cells and granulocytes seemed to be associated with a difference in the responses of catecholamines (high in old mice) and corticosterone (high in young mice) after stress. Indeed, an injection of adrenaline mainly induced the infiltration of granulocytes while that of cortisol activated NKT cells. The present results suggest the existence of age-related bias in the function of NKT cells and granulocytes after stress and that such bias might be produced by different responses of sympathetic nerves and steroid hormones between young and old mice.

Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector

Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon neutrinos. This search yielded no excess events above those expected from background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux measured at the earth. For an assumed E-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E2Phi(E)=8.4 x 10(-7) cm(-2) s(-1) sr(-1) GeV (for a predominant neutrino energy range 6-1000 TeV), which is the most restrictive bound placed by any neutrino detector. Some specific predicted model spectra are excluded. Interpreting these limits in terms of the flux from a cosmological distributions of sources requires the incorporation of neutrino oscillations, typically weakening the limits by a factor of 2.

[Survey of jugular bulb with MRA in sudden sensorineural hearing loss]

To evaluate the correlation between the size and position of the jugular bulb and the sudden sensorineural hearing loss(SSHL), the diameter and height of all jugular bulbs were measured with magnetic resonance angiography and analysed with statistics in 15 cases with SSHL and 35 cases without SSHL(as control). The ipsilateral and the contralateral bulbs of the SSHL were more asymmetrical than that of the control. The mean diameter and height of the ipsilateral bulbs of SSHL were larger than that of the dominant side bulbs of the control. It indicates that the heteroplasia of jugular bulbs which were greatly enlarged and bulgy upward might be related to SSHL.

Biosynthesis of the linkage region of glycosaminoglycans: cloning and activity of galactosyltransferase II, the sixth member of the beta 1,3-galactosyltransferase family (beta 3GalT6)

A family of five beta1,3-galactosyltransferases has been characterized that catalyze the formation of Galbeta1,3GlcNAcbeta and Galbeta1,3GalNAcbeta linkages present in glycoproteins and glycolipids (beta3GalT1, -2, -3, -4, and -5). We now report a new member of the family (beta3GalT6), involved in glycosaminoglycan biosynthesis. The human and mouse genes were located on chromosomes 1p36.3 and 4E2, respectively, and homologs are found in Drosophila melanogaster and Caenorhabditis elegans. Unlike other members of the family, beta3GalT6 showed a broad mRNA expression pattern by Northern blot analysis. Although a high degree of homology across several subdomains exists among other members of the beta3-galactosyltransferase family, recombinant enzyme did not utilize glucosamine- or galactosamine-containing acceptors. Instead, the enzyme transferred galactose from UDP-galactose to acceptors containing a terminal beta-linked galactose residue. This product, Galbeta1,3Galbeta is found in the linkage region of heparan sulfate and chondroitin sulfate (GlcAbeta1,3Galbeta1,3Galbeta1,4Xylbeta-O-Ser), indicating that beta3GalT6 is the so-called galactosyltransferase II involved in glycosaminoglycan biosynthesis. Its identity was confirmed in vivo by siRNA-mediated inhibition of glycosaminoglycan synthesis in HeLa S3 cells. Its localization in the medial Golgi indicates that this is the major site for assembly of the linkage region.

Light-emitting diode treatment reverses the effect of TTX on cytochrome oxidase in neurons

Light close to and in the near-infrared range has documented benefits for promoting wound healing in human and animals. However, mechanisms of its action on cells are poorly understood. We hypothesized that light treatment with a light-emitting diode array at 670 nm (LED) is therapeutic in stimulating cellular events involving increases in cytochrome oxidase activity. LED was administered to cultured primary neurons whose voltage-dependent sodium channels were blocked by tetrodotoxin. The down-regulation of cytochrome oxidase activity by TTX was reverted to control levels by LED. LED alone also up-regulated enzyme activity. Thus, the results are consistent with our hypothesis that LED has a stimulating effect on cytochrome oxidase in neurons, even when they have been functionally silenced by TTX.

The generation and characterization of a cell line derived from a sporadic renal angiomyolipoma: use of telomerase to obtain stable populations of cells from benign neoplasms

Angiomyolipomas are benign tumors of the kidney derived from putative perivascular epithelioid cells, that may undergo differentiation into cells with features of melanocytes, smooth muscle, and fat. To gain further insight into angiomyolipomas, we have generated the first human angiomyolipoma cell line by sequential introduction of SV40 large T antigen and human telomerase into human angiomyolipoma cells. These cells show phenotypic characteristics of angiomyolipomas, namely differentiation markers of smooth muscle (smooth muscle actin), adipose tissue (peroxisome proliferator-activator receptor gamma, PPARgamma), and melanocytes (microophthalmia, MITF), thus demonstrating that a single cell type can exhibit all of these phenotypes. These cells should serve as a valuable tool to elucidate signal transduction pathways underlying renal angiomyolipomas.

Enhanced 3-O-sulfation of galactose in Asn-linked glycans and Maackia amurensis lectin binding in a new Chinese hamster ovary cell line

We report the characterization of two Chinese hamster ovary cell lines that produce large amounts of sulfated N-linked oligosaccharides. Clones 26 and 489 were derived by stable transfection of the glycosaminoglycan-deficient cell mutant pgsA-745 with a cDNA library prepared from wild-type cells. Peptide:N-glycanase F released nearly all of the sulfate label, indicating that sulfation had occurred selectively on the Asn-linked glycans. Hydrazinolysis followed by nitrous acid treatment at pH 4 and borohydride reduction yielded reduced sulfated disaccharides that comigrated with standard Gal3SO4beta1-4anhydromannitol. The disaccharides were resistant to periodate oxidation but became sensitive after the sulfate group was removed by methanolysis, indicating that the sulfate was located at C3 of the galactose residues. Maackia amurensis lectin bound to the sulfated glycopeptides on the cell surface and in free form, even after sialidase treatment. This finding indicates that the lectin requires only a charged group at C3 of the galactose unit and not an intact sialic acid. Growth of cells with chlorate restored sialidase sensitivity to lectin binding, indicating that sulfation and sialylation occurred largely at the same sites. The enhanced sulfation was due to elevated sulfotransferase activity that catalyzed transfer of sulfate from phosphoadenosine-5'-phosphosulfate to Galbeta1-4(3)GlcNAcbeta-O-naphthalenemethanol.

The effect of precursor structures on the action of glucosaminyl 3-O-sulfotransferase-1 and the biosynthesis of anticoagulant heparan sulfate

To understand how 2-O-sulfation of uronic acid residues influences the biosynthesis of anticoagulant heparan sulfate, the cDNA encoding glucosaminyl 3-O-sulfotransferase-1 (3-OST-1) was introduced into wild-type Chinese hamster ovary cells and mutant pgsF-17 cells, which are defective in 2-O-sulfation. 3-OST-1-transduced cells gained the ability to bind to antithrombin. Structural analysis of the heparan sulfate chains showed that 3-OST-1 generates sequences containing GlcUA-GlcN(SO(3))3(SO(3)) and GlcUA-GlcN(SO(3))3(SO(3))6(SO(3)) in both wild-type and mutant cells. In addition, IdoUA-GlcN(SO(3))3(SO(3)) and IdoUA-GlcN(SO(3))3(SO(3))6(SO(3)) accumulate in the mutant chain. These disaccharides were also observed by tagging [6-(3)H]GlcN-labeled pgsF-17 heparan sulfate in vitro with [(35)S]PAPs and purified 3-OST-1. Heparan sulfate derived from the transduced mutant also had approximately 2-fold higher affinity for antithrombin than heparan sulfate derived from the transduced wild-type cells, and it inactivated factor Xa more efficiently. This study demonstrates for the first time that (i) 3-O-sulfation by 3-OST-1 can occur independently of the 2-O-sulfation of uronic acids, (ii) 2-O-sulfation usually occurs before 3-O-sulfation, (iii) 2-O-sulfation blocks the action of 3-OST-1 at glucosamine residues located to the reducing side of IdoUA units, and (iv) that alternative antithrombin-binding structures can be made in the absence of 2-O-sulfation.

Characterization of the caspase inhibitor IDN-1965 in a model of apoptosis-associated liver injury

Previous studies have shown that caspase inhibitors are effective at protecting against anti-Fas antibody (alpha-Fas)-mediated liver injury/lethality. The purpose of these experiments was to characterize more fully the efficacy of a broad-spectrum, irreversible caspase inhibitor, IDN-1965 (N-[(1,3-dimethylindole-2-carbonyl)valinyl]-3-amino-4-oxo-5-fluoropentanoic acid), in this model and the role of caspase inhibition in long-term protection. The ED(50) for IDN-1965 by i.p. administration, based on alanine aminotransferase activities, was 0.14 mg/kg. The caspase inhibitor was also efficacious when administered intravenously and orally (ED(50) values of 0.04 and 1.2 mg/kg, respectively). Histologically, marked reduction in Fas-induced apoptosis with IDN-1965 (1 mg/kg, i.p.) was apparent at 6 h. Also, caspase 3-like activities were decreased in a dose-dependent manner, but the inhibition of caspase activity was transient. Immunohistochemical studies demonstrated that IDN-1965 greatly reduced the activation of caspase 3. In survival studies, a single i.p. treatment of 1 mg/kg IDN-1965 or continuous i.p. infusion via osmotic pumps completely blocked lethality measured up to 7 days after alpha-Fas administration. IDN-1965 was also effective in inhibiting liver injury when administered as long as 3 h after or 1 h before alpha-Fas administration. Lastly, Western blot analysis demonstrated that processing of caspases 3, 6, and 8, as well as Bid (a protein responsible for the release of mitochondrial cytochrome C and amplification of the apoptotic cascade) was inhibited by IDN-1965. In conclusion, the broad-spectrum caspase inhibitor IDN-1965 is markedly effective at inhibiting Fas-mediated apoptosis by multiple routes of administration. The therapeutic potential of caspase inhibitors appears promising for the treatment of apoptosis-mediated liver injury based on potency and postinsult efficacy.

[Expression of VEGF, bFGF and ER in endometrial carcinoma]

OBJECTIVE

To investigate the expression of VEGF, bFGF and ER in endometrial carcinoma and its relation to the clinico-pathological manifestations and prognosis.

METHODS

A total of 66 specimens of endometrial carcinoma and 19 normal endometrium was studied by immunohistological technique with polyclonal antibodies against VEGF and bFGF, and monoclonal antibody against ER.

RESULTS

Positive expression rate of VEGF in endometrial carcinoma was 80.3%. Expression of VEGF was positively correlated with tumor grade (P < 0.01). Expression of VEGF was positively correlated with that of bFGF (P < 0.05). Negative correlation was observed between ER expression and tumor grade (P < 0.05). Prognosis of patients with negative ER expression was poor. No correlation existed between ER expression and that of VEGF and bFGF.

CONCLUSION

Expression of VEGF and bFGF may indicate that both of them contribute in the angiogenesis of endometrial carcinoma. Expression of ER has prognostic significance.

Detection of soluble urokinase receptor by immunoradiometric assay and its application in tumor patients

It has recently been found that tumor cells express large amounts of urokinase receptor (uPAR) on their surface and that the blood soluble uPAR (suPAR) level in cancer patients is increased. However, the significance of suPAR in tumor progression is still unclear. To investigate the significance of suPAR in evaluating clinical status of solid tumor patients, an immunoradiometric assay (IRMA) based on using two monoclonal antibodies (McAbs) to different epitopes of uPAR was established to determine the serum levels of suPAR in normal individuals and solid tumor patients. The detectable range of this suPAR IRMA was 1.95-500 microg/l. The affinity constant was 4.75x10(9) l/mol. The mean rate of recovery was 101.3%, and the mean coefficients of variation for intra- and interassay were 6.40+/-2.57% (mean+/-S.D., n = 11) and 10.48+/-2.65% (n = 5), respectively. The serum suPAR levels were 2.71+/-1.12 microg/l in 62 normal individuals, 3.71+/-1.69 microg/l in 30 patients with benign tumors, and 5.82+/-2.27 microg/l in 124 patients with malignant tumors. The serum suPAR levels of these two types of tumor patients were increased in comparison with that of normal individuals (P values less than.01 and.001). The extent of their increase in malignant tumors was much greater than in benign tumors (P < .001). The serum suPAR levels of patients with malignant tumors were correlated with tumor invasion, metastasis, and surgical intervention. Our data suggest that IRMA for suPAR could be a sensitive and specific assay and that the serum suPAR level would be a valuable index for evaluating the condition and prognosis of tumor patients in clinic.

[Dyslipidemia-related risk factors for myocardial infarction and polymorphism of ApoE gene among myocardial infarction patients and their siblings]

OBJECTIVE

To assess the risk factors of myocardial infarction (MI) and the polymorphism of the gene Apoliprotein (ApoE) genotype among MI patients and their siblings.

METHODS

Questionnaire survey and clinical examination were conducted to 65 male MI patients, 141 "healthy" male siblings of the MI patients, and 47 healthy persons matched in age and sex.

RESULTS

(1) The medians of TC, TG, LDL-C, TC/HDL-C in MI group and sibling group were higher than those in the control group with statistical significance. (2) BMI > 25 kg/m(2), cigarette > 10/d, TC > 5.2 mmol/L, TG > 2.26 mmol/L, LDL-C > 3.4 mmol/L, TC/HDL-C > 5.0, and FBG > 5.6 mmol/L were risk factors for MI; and HDL-C > 0.9 mmol/L was a protective factor for MI. (3) Among the three genotypes of ApoE, E3/3 was the commonest one. However, no significant difference was found in the distribution frequencies of these 3 genotypes, levels of serum lipid and lipoprotein, and TC/HDL-C. (4) Among the MI patients the number of allele E4 carrier was nearly twice the number of the non-allele E4 carrier.

CONCLUSION

Dyslipidemia is an important risk factor for MI, and polymorphism of ApoE may be an indirect risk factor of coronary heart disease genetically.

Observation of high-energy neutrinos using Cerenkov detectors embedded deep in Antarctic ice

Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water or ice. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations.

[Method on ozone generation with strong ionization discharge]

This paper presents the formed methods of strong ionization discharge of dielectric barrier and plasma chemical reaction process of ozone generation. Ozone combination and decomposition are controlled by electric field intensity and electron energy. Therefore, new technologies with thinner dielectric layers (230 microns) of model alpha Al2O3 and narrow discharge gap (110 microns) are introduced, and strong ionization discharge is gained which reduced field (E) and electron average energy are more than 400Td and 10 eV respectively. Ozone concentration reaches to 200 g/m3 and ozone producing efficiency is 100 g/(kW.h). Ozone generator of big yield and miniaturization with module assembled method is realized.

[Study of C807T polymorphism of the platelet collagen receptor alpha2 gene coding sequence in Suzhou Han population]

OBJECTIVE

To study the C807T polymorphism of the platelet collagen receptor alpha(2) gene coding sequence in Suzhou Han population. This polymorphism was associated with the expression density of integrin alpha(2)beta(1) on the platelet surface.

METHODS

An amplified 1332 bp fragment of human alpha(2) gene from 110 unrelated individuals was analyzed by Bgl II and Ase I restriction assay. The resulting products were electrophoresed in 8% polyacrylamide gels and stained with ethidium bromide.

RESULTS

The allelic frequencies were 0.291:0.709 for T807 allele: C807 allele in Suzhou Han population. The total theoretical heterozygous rate was 41%. The genotypic frequencies were 0.018:0.546:0.436 for homozygous 807T allele: heterozygous 807C/T allele: homozygous 807C allele.

CONCLUSION

The C807T polymorphism of the platelet collagen receptor alpha2 gene in Suzhou Han population was different from that observed in other populations.

[Effect of lead exposure in prenatal and postnatal duration on infant growth]

The blood lead (PbB) levels of pregnant women and their babies were followed up since the third month of pregnancy until their babies were 2 years old. The general condition of delivery, family history of the pregnant women, feeding and development of infants were investigated. Prenatal and postnatal PbB levels and their effects on infant growth were analysed. The result showed a significant negative correlation of PbB level of pregnant women near delivery, and in umbilical cord with the growth of infants. Multiple regression analysis showed a negative correlation between PbB level and height, weight of infant at 1 and 2 years old.

Osteomalacia in hyp mice is associated with abnormal phex expression and with altered bone matrix protein expression and deposition

To explore how the loss of Phex function contributes to the pathogenesis of osteomalacia, we examined the abnormalities of mineralization, Phex, and bone matrix protein expression occurring in Hyp mice in vivo and in ex vivo bone marrow cell cultures. The results in vivo show that mineralization was decreased significantly in Hyp mouse bone. Phex protein was identifiable in osteoblasts and osteocytes in wild-type mice, but not in Hyp mice. In Hyp mice, osteocalcin, bone sialoprotein, and vitronectin expression were down-regulated, whereas biglycan and fibrillin-1 expression were up-regulated in osteocytes and bone matrix relative to those in their wild-type counterparts. Parallel studies ex vivo demonstrated that cells derived from 18-day Hyp mouse bone marrow cell cultures had a 3'-Phex deletion, no Phex protein expression, decreased alkaline phosphatase activity, collagen deposition, and calcium accumulation, and reduced osteocalcin, bone sialoprotein, and vitronectin at both the protein and messenger RNA levels. Furthermore conditioned medium from Hyp mouse bone marrow cultures could induce analogous defects in bone marrow cell cultures of wild-type cells. These novel findings indicate that there is an intrinsic osteogenic cell differentiation defect in addition to the known hypomineralization of bone in Hyp mice, which may be inducible by an autocrine/paracrine secreted factor. These results suggest that alterations in the Phex gene may control bone matrix mineralization indirectly by regulating the synthesis and deposition of bone matrix proteins.

[Graf's ultrasound examination method in assessment of dysplasia and congenital dislocation of infant hip]

OBJECTIVE

To discuss the application of Graf's sonographic method in assessment of developmental dysplasia and dislocation of infant hip.

METHODS

2258 infants (4516 hips) were examined and evaluated by Graf's method.

RESULTS

The analysis of data showed that type I hip accounted too 78.99%, type II 20.56%, and type III and type IV 0.45%.

CONCLUSION

Graf's method can provide qualitative and quantitative evaluation for hips of infants in 3 months after birth. It is an effective in developmental dysplasia of the hip (DDH) and is also useful for early treatment and follow-up of DDH.

[Mechanical mechanism in plastic stage of fracture union--application of bone surface remodeling theory]

In this paper is presented a discussion on the mechanical mechanism in the plastic stage of fracture union. We adopt the bone surface remodeling theory in conjunction with finite element method, choose the strain energy density as mechanical stimulus, work at a three-dimensional finite element model, and then we investigate the mechanical mechanism in the plastic stage of fracture union in three types: exterior osteotylus, interior bony defect and exterior bony defect, using long bone surface remodeling software "BRSS97" we design. The results show that osteotylus can be completely absorbed, and bony defect can recover. For all the three types, the final bone configuration resembles normal state bone configuration. It proves that long bone configuration in the plastic stage of fracture union is the result of the adaptation of bone to loading environment.

Predictive value of quantitative PCR-based viral burden analysis for eight human herpesviruses in pediatric solid organ transplant patients

Human herpesviruses can cause significant morbidity and mortality in pediatric solid organ transplant recipients. It was hypothesized that viral burden quantification by polymerase chain reaction using an internal calibration standard could aid in distinguishing between viral disease and latency. Here we report the results of a 2-year prospective study of 27 pediatric solid organ (liver, kidney, or heart) transplant recipients in which multiple samples were analyzed for levels of all eight human herpesviruses by internal calibration standard-polymerase chain reaction. Herpes simplex viruses 1 and 2, varicella-zoster virus, and Kaposi's sarcoma-associated herpesvirus were not detected in any of these samples. Human herpesvirus types 6 and 7 were detected in half of the patients, but were present at low levels, similar to those found in reference populations. Epstein-Barr virus (EBV) and cytomegalovirus (CMV) were detected in 89% and 56% of the patients, respectively. Viral burden analysis suggested distinct patient populations for CMV, with a natural cutoff of 10,000 viral targets/ml blood strongly associated with disease. In some cases, a dramatic increase in CMV levels preceded clinical evidence of disease by several weeks. EBV viral burden was relatively high in the only patient presenting with an EBV syndrome. However, two other patients without evidence of EBV disease had single samples with high EBV burden. Rapid reduction in both EBV and CMV burden occurred with antiviral treatment. These data suggest that viral burden analysis using internal calibration standard-polymerase chain reaction for CMV, and possibly other herpesviruses, is an effective method for monitoring pediatric transplant patients for significant herpesvirus infection and response to therapy.

[Effects of adenovirus-mediated p16 and p53 genes transfer on apoptosis and cell cycle of lung carcinoma cells]

OBJECTIVE

To explore the synergistic inhibition effect and apoptosis induction of p16 and p53 genes on lung carcinoma cells.

METHODS

E1-deficient and replication-defective recombinant p16 and p53 adenoviruses were generated by liposome-mediated co-transfection of recombinant plasmid pAdCMV-p16 or pAdCMV-p53 along with pJM17 and homologous recombination in 293 packaging cell. The lung cancer cell line H358, which had a homozygous deletion of p53 gene and no expression of p16 mRNA and protein, was infected with recombinant p16 and p53 adenovirus either individually or together.

RESULTS

Immunohistochemical analysis showed that recombinant adenovirus could transfer p53 gene into tumor cell with 98% efficiency. Western blot indicated that p16 and p53 proteins were expressed at a high level in infected H358 cell. Inhibition effect of p53 gene on proliferation of H358 cell was weaker than that of p16 gene, and the combined use of both genes could completely prevent the proliferation of H358 cell. In situ end-labeling and flow cytometry indicated that p16 could result in G(1) arrest of cell cycle and did not induce H358 cells to undergo apoptosis; p53 also induced apoptosis of few cells besides G(1) arrest; and the simultaneous use of p16 and p53 genes could induce marked apoptosis of H358 cells.

CONCLUSION

p16 and p53 genes possess the synergistic inhibiting effect on growth of lung cancer cells and can cooperate to induce apoptosis of H358 cell. The combined application of recombinant p16 and p53 adenoviruses can be used as a new strategy for cancer gene therapy.

Location of the glucuronosyltransferase domain in the heparan sulfate copolymerase EXT1 by analysis of Chinese hamster ovary cell mutants

Heparan sulfate formation occurs by the copolymerization of glucuronic acid (GlcA) and N-acetylglucosamine (GlcNAc) residues. Recent studies have shown that these reactions are catalyzed by a copolymerase encoded by EXT1 and EXT2, members of the exostosin family of putative tumor suppressors linked to hereditary multiple exostoses. Previously, we identified a collection of Chinese hamster ovary cell mutants (pgsD) that failed to make heparan sulfate (Lidholt, K., Weinke, J. L., Kiser, C. S., Lugemwa, F. N., Bame, K. J., Cheifetz, S., Massagué, J., Lindahl, U., and Esko, J. D. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 2267-2271). Here, we show that pgsD mutants contain mutations that either alter GlcA transferase activity selectively or that affect both GlcNAc and GlcA transferase activities. Expression of EXT1 corrects the deficiencies in the mutants, whereas EXT2 and the related EXT-like cDNAs do not. Analysis of the EXT1 mutant alleles revealed clustered missense mutations in a domain that included a (D/E)X(D/E) motif thought to bind the nucleotide sugar from studies of other transferases. These findings provide insight into the location of the GlcA transferase subdomain of the enzyme and indicate that loss of the GlcA transferase domain may be sufficient to cause hereditary multiple exostoses.