Comparison of adrenoceptor subtype expression in porcine and human bladder and prostate

We have quantified and characterized ₁-, ₂-and -adrenoceptor subtypes in porcine bladder detrusor and bladder neck, human bladder detrusor, and porcine and human prostate. ₁-, ₂- and -adrenoceptor were identified in radioligand binding studies using [³H]prazosin, [³H]RX 821002 and [¹²⁵I]iodocyanopindolol, respectively, as the radioligands. In porcine male and female detrusor and bladder neck and male prostate, adrenoceptors were detected in the order of abundance > _{2 1} (not detectable), with no major differences between the sexes or between detrusor and bladder neck. In human detrusor and prostate the order of abundance was > _{2 1} (not detectable) and ₁ > ₂. respectively. The ₂-adrenoceptors in all tissues were homogeneously of the _2A-subtype as evidenced by competition binding studies with yohimbine, prazosin, ARC 239 and oxymetazoline. The -adrenoceptors represented a mixed population with a dominance of the ₂-subtype in all tissues as demonstrated by competition binding with ICI 118,551 and CGP 20,712A. We conclude that pigs may be a suitable model for studies of detrusor function with respect to adrenoceptor expression. They may be less suitable for studies of bladder neck or prostate function.     

Identification of α1-adrenoceptor subtypes in the dog prostate

Summary The ₁-adrenoceptor subtypes of dog prostate were characterized in binding and functional experiments. In saturation experiments, [³H]prazosin bound to ₁-adrenoceptors with high affinity. In the displacement experiments, unlabelled prazosin and WB4101 biphasically inhibited the binding of 400 pM [³H]prazosin, suggesting the presence of at least two distinct affinity sites for prazosin or WB4101. The proportion of high-affinity sites was approximately 10%. HV723 also recognized two distinct affinity sites but the proportion of high-affinity sites was approximately 20%. From these results the presence of three distinct ₁-adrenoceptor subtypes was suggested: presumably subtypes _1A (high affinity for prazosin and WB4101), _1N (high affinity for only HV723) and _1L (low affinity for the three antagonists) according to the recently proposed ₁-adrenoceptor subclassification. The density of subtype _1L was much higher than that of subtypes _1A and _1N subtypes. In the functional experiments, prazosin, WB4101 and HV723 competitively antagonized the contractile response to noradrenaline with low affinities close to those estimated for the _1L subtypes. These results suggest that the contractile response to noradrenaline in the dog prostate is mediated predominantly through _1L subtype -adrenoceptors.     

TNFα-stimulated gene product (TSG-6) and its binding protein, IαI, in the human intervertebral disc: new molecules for the disc

Inflammation and irritation of the nerve roots has been indicated as an important factor in the pain associated with symptomatic disc herniations. Tumour necrosis factor (TNF) is now believed to be involved in this pathway. TNF causes connective tissue cells in culture to synthesise a glycoprotein, TNF-stimulated gene-6 (TSG-6). TSG-6 is found in inflammatory diseases of related connective tissues, such as articular cartilage in rheumatoid arthritis, but is not present in unaffected individuals. In order to determine if TSG-6 occurred in intervertebral disc (and cartilage endplate), we have investigated the presence of TSG-6 and its binding protein, inter--inhibitor (II), in 58 herniated and 15 non-herniated discs. Immunostaining for the cytokines, IL-1, IL-1 and TNF, has also been carried out. We have demonstrated that both TSG-6 and II occur commonly in human intervertebral disc matrix with at least some TSG-6 in 98% of discs studied and II in all of them. Staining for TSG-6 was greatest in herniated discs, particularly close to blood vessels. II immunostaining was frequently widespread throughout the disc but there was little in the cartilage endplate. It has been proposed that these molecules have widespread effects, including extracellular matrix stabilisation, down-regulation of the protease network and reduction of inflammation. Hence, the occurrence of TSG-6 and II in disc tissue could have implications in the aetiopathogenesis and future therapeutics of intervertebral disc disease.     

Extracellular matrix and integrin composition of the normal bladder wall

Summary We performed an immunohistochemistry study of the normal human bladder so as to understand the interactions of extracellular matrix (ECM) components and the integrins of cell adhesion that accommodate the volume changes and maintain an impermeable barrier to reabsorption of urine in the bladder. The normal human urothelial cell and/or its plasma membrane contained integrins 3, V, 1, and 4 but did not contain integrin 3. The urothelial basement membrane (UBM) contained collagen type IV and laminin. Fibronectin and integrins 3 and 4 were found in or near the UBM area, with types I and III collagen and tenascin abutting the area. The patterns of collagen, laminin, tenascin, vitronectin, fobronectin, and the 3, V, 1, and 3 integrins in the lamina propria, vessels, nerves, and smooth-muscle layers are described. These findings detail the normal anatomical ECM/integrin relationship that provides the cellular basis for bladder-wall relationships responsible for its impermeable state and other functions.     

An immunohistochemical study of glucagonoma conducted on the metastatic lymph nodes from a patient with recurrent metastatic glucagonoma: Report of a case

In this report, we briefly present the case of a 67-year-old woman who developed recurrent glucagonoma with lymph node metastasis. An immunohistochemical study of the metastatic tumor revealed immunoreactivity of glucagon and protein kinase C (PKC)-, -, and - in the tumor cells, two types of which were seen by electron microscopy. One type had abundant secretory granules and mitochondria, while the other had few granules and mitochondria. Some granules were similar to typical A cell granules and others were atypical. An immunoelectron microscopic demonstration revealed PKC-, -, and - immunostaining in the cytoplasm of all the tumor cells, while some secretory granules had PKC immunostaining, and others had no immunostaining. Thus, it appears that metastatic glucagonoma and its associated granules are composed of two types of mature and immature cells or granules. As immunoreactivity of PKC- and - was found in the tumor cells, but not in the normal A cells of the islets of Langerhans, the PKC subspecies and , which are not present in normal pancreatic A cells, may exist in human glucagonoma cells.     

Elevated concentrations of the β-subunit of S100 protein in renal cell tumors in rats

Concentrations of and -subunits of S100 protein (S100- and S100-) in rat kidney neoplasms, including renal cell and mesenchymal tumors, were determined using a highly sensitive enzyme immunoassay, and both types immunohistochemically localized in tissue sections. Concentration of S100- in each histological type of rat tumor were lower than in normal kidney, whereas levels of S100- (mean±SE: 29.7±14.2 ng/mg protein, n=15) in renal cell tumors were significantly higher than in normal kidneys (0.55±0.06 ng/mg protein, n=7), or mesenchymal tumors (1.21±0.43 ng/mg protein, n=9). In normal rat kidney tissues S100- was immunohistochemically positive in epithelial cells of the distal tubules, the thin limbs of loops of Henle, and the collecting ducts. No appreciable immunostaining for S100- was found in any nephron segment. Both S100- and S100- were positive for renal cell tumors, indicating new appearance of the latter during renal carcinogenesis in rats.     

The expression of cytoskeletal proteins (α-SMA,vimentin, desmin) in kidney tissue: A comparison of fetal,normal kidneys,and glomerulonephritis

Background: The aim of the study is a comparison of the expression of cytoskeletal proteins, alpha smooth muscle actin (-SMA), vimentin, and desmin in fetal, normal kidney and proliferative (diffuse proliferative and membranoproliferative glomerulonephritis) and nonproliferative (membranous glomerulonephritis) glomerulonephritis.Methods: We have studied the expression of cytoskeletal proteins (-SMA, vimentin, desmin) in the paraffin embedded tissue sections from the kidneys of 10 normal kidney (adults and infants), 13 fetal kidney, 12 membranous glomerulonephritis (MGN), 8 membranoproliferative glomerulonephritis (MPGN), 8 diffuse proliferative glomerulonephritis (DPGN). Interstitial and glomerular positive stainings were evaluated.Results: Vimentin expression was similar in normal infant and adult kidneys with positive staining in glomeruli and negative staining in interstitium. In fetal kidneys, glomerular mesangial and epithelial cells and blastematous areas showed positive reactivity with vimentin. -SMA staining was different among the groups. In fetal kidney, -SMA expression was found in glomerular mesangial cells and blastematous areas. -SMAstaining was positive in peritubular area and glomerular mesangial cells in infant kidney. In adult kidneys, glomerular staining with -SMA disappeared but peritubular positivity continued. Interstitial staining with -SMA was positive in fibrotic areas of proliferative (MPGN, DPGN) and non-proliferative (MGN) glomerulonephritis, but positive glomerular staining with -SMA was found only proliferative glomerulonephritis. Desmin expression was negative in all groups.Conclusions: Desmin is not expressed in early stages of kidney growth, infant and adult kidneys, and proliferative and nonproliferative glomerulonephritis. Interstitial staining of vimentin in the diseased kidney tissues revealed increased fibrosis. -SMA revealed important differences in different stages of nephrogenesis. Glomerular mesangial staining with -SMA in developing (fetal and infant kidneys) and proliferative glomerulonephritis suggest that it may be a marker of proliferation. In addition, it shows myofibroblastic differentiation in interstitium in diseased kidneys.     

Renal α-adrenergic receptors and genetic hypertension

The hypothesis has been proposed that an increase in the number of renal -adrenergic receptors may contribute to the pathogenesis of genetic hypertension. Herein we review recent findings regarding expression of renal ₁ (_{1 a},_{1 b})- and ₂ (_{2 a},_{2 b})-adregenergic subtypes and we provide an updated revision of the above-stated hypothesis. Enhancement in receptor number or in post-receptor components responsible for ₁- and ₂-adregenergic mediated sodium reabsorption in proximal tubule may contribute to sodium retention and an elevation in blood pressure. Perhaps such changes contribute to the increase in blood pressure in genetically determined hypertension in humans, although direct tests of this notion have not yet been performed.     

Proteins of the periodontium

Summary Cyanogen bromide (CNBr) peptides were prepared of the insoluble collagen of bovine dental cementum. Following chromatographic separation, the peptides were identified by their amino-acid composition. Type I collagen ([1(I)]₂2) accounted for more than 90% of the organic matrix, while Type III collagen ([1(III)]₃) was present at a level of approximately 5%. Amino-acid analyses revealed that the CNBr peptides from 1(I) and 2 chains of cementum closely resembled the corresponding peptides from calf skin. The only systematic difference was a higher level of hydroxylation of prolyl and lysyl residues of the cementum peptides.     

Cytotoxic effect of diphtheria toxin used alone or in combination with other agents on human renal cell carcinoma cell lines

Treatment of renal cell carcinoma (RCC) by conventional chemotherapy and immunotherapy has resulted in minimal remissions. Alternative forms of therapy are therefore being sought. The present study investigated the sensitivity of RCC cell lines to several toxins used alone and in combination with other agents. RCC lines were relatively sensitive to the direct cytotoxic effect of diphtheria toxin (DTX), Pseudomonas aeruginosa exotosin A (PEA) and ricin. Furthermore, DTX in combination with tumor necrosis factor- (TNF-) resulted in synergistic cytotoxic activity. The mechanism of synergy was examined. A possible mechanism of resistance to TNF- in tumor cells is the expression of TNF- mRNA or protein. R11 cells did not constitutively express mRNA for TNF-, however, treatment of R11 cells with TNF- induced the expression of TNF- mRNA. When DTX was used in combination with TNF-, the level of TNF- mRNA induced by TNF- was markedly reduced. These studies suggest that DTX in combination with TNF- can overcome the resistance of RCC lines and that the marked downregulation of TNF- mRNA by DTX may play a role in the enhanced cytotoxicity seen with the combination of DTX and TNF-. Furthermore, the combination treatment might also potentiate the antitumor host responses. The implications of these findings in clinical therapy are discussed.     

Natural human IgG inhibits the production of tumor necrosis factor-α and interleukin-1α through the Fc portion

The overproduction of cytokines such as the tumor necrosis factor- (TNF-) and interleukin-1 (IL-1) may cause further deterioration in the already critical condition of patients with shock, sepsis, and acute inflammation. The effectiveness of infusion therapy of natural human IgG to such patients is suggested to depend partly upon the inhibition of the productivity of these cytokines. In this study, we investigated the modulation effects of IgG and its fragments on the production of TNF- and IL-1, on human peripheral blood mononuclear cells (PBMC). The production of TNF- and IL-1 was found to be dose-dependently inhibited by IgG when stimulated by lipopolysaccharide (LPS), phytohemagglutinin (PHA), concanavalin A (Con A), and interleukin-2 (IL-2). However, no inhibition was seen when stimulated by phorbormyristate acetate (PMA). The F(ab)₂ fragment showed enhancing effects on cytokine production by LPS, while the Fc fragment showed not as much inhibitory effect as whole intact IgG. IgG showed no direct cytotoxic effect on PBMC. These data suggest that natural human IgG inhibits TNF- and IL-1 production by PBMC through the Fc portion. The results of this study led us to conclude that whole intact IgG may be the best form of therapeutic delivery.     

Neue Einblicke in die Rolle der Östrogene und ihrer Rezeptoren im Prostatakarzinom

Zusammenfassung In der vorliegenden Übersicht werden neue Befunde über die differenzielle Expression von Östrogenrezeptoren und östrogenregulierter Zielgene in der Prostata und im Prostatakarzinom zusammengefasst und ihre Bedeutung für die Tumorentstehung und Androgenresistenz diskutiert. Die beiden Östrogenrezeptoren und (ER, ER) werden in funktionell unterschiedlichen Kompartimenten des Prostataepithels exprimiert; der ER im Proliferationskompartiment (Basalzellschicht), der ER im Differenzierungskompartiment (sekretorisches Epithel).Bei der malignen Transformation des Prostataepithels (high-grade-prostatische intraepitheliale Neoplasie, HGPIN) verlagert sich die ER-Expression in das Differenzierungskompartiment und vermittelt als Onkogen kanzerogene Effekte auf das Prostataepithel. Der ER, ein potenzieller Tumorsuppressor, geht in der HGPIN partiell verloren, wodurch die protektive Wirkung der Phytoöstrogene auf das transformierte Prostataepithel abgeschwächt wird. Das Prostatakarzinom zeigt unabhängig von Grading und Staging hohe Expressoinsraten des ER. Erst im Stadium der Androgenresistenz geht der androgenregulierte ER partiell verloren. Im Gegensatz zum Mammakarzinom ist die Expression des klassischen ER und des Progesteronrezeptors im Prostatakarzinom ein spätes Ereignis in der Tumorprogression und ist maximal in Metastasen und hormonrefraktären Tumoren ausgeprägt. Etwa 30% der metastasierten und androgeninsensitiven Prostatakarzinome zeigen hohe Expressionsraten des ER regulierten Progesteronrezeptors. Das Antiöstrogen Raloxifen wirkt in androgeninsensitiven Prostatakarzinomzelllinien wachstumsinhibitorisch und induziert dosisabhängig den programmierten Zelltod.Aufgrund dieser Befunde sind Patienten mit androgeninsensitiven Prostatakarzinomen potentielle Kandidaten für eine Antiöstrogen- bzw. Antigestagentherapie. Klinische Studien müssen die Effizienz einer solchen Therapie prüfen.     

The dynamic pressure response to rapid dilatation of the resting urethra in healthy women: an in vivo evaluation of visco-elastic properties

Summary The urethral pressure response to a sudden forced dilatation was studied at the bladder neck, in the high-pressure zone and in the distal urethra in ten healthy female volunteers. The pressure response was fitted with a duoble exponential function of the form P _t = P _equ + P e^–t / + P e^–t /, where P _equ, P and P are constants, and and are time constants; this equation has previously been demonstrated to describe the pressure decay following dilatation. On the basis of a theoretical model the elastic and viscous constants for the urethral tissues were computed. The results showed significant differences along the urethra, with the high-pressure zone showing the highest maximum and equilibrium pressures, fastest pressure decay and highest elastic coefficient. The pressure response represents an integrated stress response from the surrounding structures, which reflects the viscoelastic properties of the tissues involved. The findings seem therefore to correlate well with the anatomical findings, which have shown a high fibre density of the horseshoe-shaped rhabdosphincter in the mid-portion of the urethra. The method permits a detailed assessment of static and dynamic urethral responses to dilatation which can be applied as an experimental simulation of urine ingression, and is therefore presumed to be of value in the evaluation of normal and pathological urethral sphincter function.     

Use of a pericardial fat pad flap for preventing bronchopleural fistula: An experimental study focusing on the angiogenesis and cytokine production of the fat pad

An experimental study was conducted to determine whether pericardial fat tissue could induce neovascularization and produce cytokines related to tissue repair. Neovascularization was examined using chick chorioallantoic membranes. Pieces of pericardial fat tissue, omentum, and intercostal muscle were individually placed on a number of chorioallantoic membranes and neovascularization induced by each material was assayed 6 days after the implantation. The intensity of neovascularization was in the order of pericardial fat omentum > muscle. Cytokines, such as interleukin 1 (IL-1) and , tumor necrosis factor- (TNF), interferon- (IFN-), and interleukin 6 (IL-6) were assayed in a culture supernatant of pericardial fat tissue. The latter was obtained 24h after the addition of lipopolysaccharide (LPS) following various incubation times. All cytokines other than IFN are known to play a part in tissue repair, whereas IFN is negatively related to tissue repair because it inhibits fibroblast growth. The pericardial fat tissue incubated with LPS produced a certain amount of IL-1 on day 1, and TNF on days 1 and 8, whereafter these values decreased to an undetectable level. Irrespective of the addition of LPS, a large amount of IL-6 was observed in the supernatant of pericardial fat tissue and it was detectable until day 29. On the contrary, INF was not detected at any assay time. These observations suggest that a pericardial fat pad flap could possibly be beneficial in the prevention of bronchopleural fistula after pulmonary resection.     

Role of endogenous interferon gamma in murine tumor growth and tumor necrosis factor alpha antitumor efficacy

Background: The anticancer role of tumor necrosis factor-alpha (TNF-) has been limited by toxicity. These experiments evaluate blocking endogenous interferon-gamma (IFN-) activity to abrogate TNF- toxicity. Methods: C57Bl/6 mice bearing MCA 105 tumor were treated with TNF- and anti-IFN- antibody (Ab) to evaluate the effect on the acute lethality of TNF- and their efficacy as evaluated by tumor growth rate, tumor histology, and survival. Results: Anti-IFN- Ab decreased TNF- lethality. Anti-IFN- Ab alone increased tumor growth significantly more than did nonimmune IgG (p₂<0.0001). Tumor-bearing mice that received nonimmune IgG and TNF- had slower tumor growth (p₂<0.02) and a trend toward improved survival (p=0.07) compared with saline-treated controls. Anti-IFN- Ab abrogated the antitumor effect of TNF-, prevented acute tumor necrosis histologically, and resulted in tumor growth rate and host survival similar to that of controls. The findings in mice that received anti-IFN- Ab and high-dose TNF- were comparable with those in mice that received a lower, equitoxic dose of TNF- alone. Conclusions: Blocking endogenous IFN- accelerates tumor growth in this model and partially abrogates the toxic and antitumor activity of exogenous TNF- equally. This suggests that blocking endogenous IFN- activity is not a useful strategy for limiting TNF- treatment toxicity.Presented in part at the 45th Annual Cancer Symposium of The Society of Surgical Oncology, New York, New York, March 15–18, 1992.     

Serum α1-microglobulin and β2-microglobulin for the estimation of fetal glomerular renal function

As proteins cannot cross the placenta levels of the microproteins ₁-microglobulin (₁MG) and ₂-microglobulin (₂MG) can be used to assess fetal glomerular renal function. ₁MG, ₂MG and creatinine were routinely determined in cord and maternal blood of 133 newborns [gestational age (GA) 25–42 weeks]. Twenty-nine patients with suspected impaired maternal or fetal renal function were studied separately and two fetuses were studied in utero. The mean fetal ₂MG concentration fell from 3.87±0.56 mg/l in the 25–31 weeks GA group to 2.60±0.50 mg/l in the mature newborn group. ₁MG concentration fell from 3.10±0.51 to 2.25±0.49 mg/dl. In contrast, the mean maternal ₁MG concentration rose from 1.73±0.69 mg/l in the 25–31 weeks GA group to a mean of 1.83±0.48 mg/l in the mature newborn group; ₁MG rose from 3.96±0.58 to 4.33±1.6 mg/dl. Maternal and fetal creatinine levels were identical. Fetal microprotein levels fall during intra-uterine development as glomerular filtration rate (GFR) rises. There is no correlation between cord blood and maternal ₁MG or ₂MG concentrations. In 13 children with urological anomalies only 1 had elevated microprotein levels and he later developed renal insufficiency. Determination of microprotein levels in fetal serum can be used to detect severe renal function disturbances and to estimate GFR independently of maternal renal function.     

Hypophosphatemic osteomalacia: a report of five cases and evaluation of bone markers

In this study, we analyzed the changes in biochemical markers of bone turnover in five patients with hypophosphatemic osteomalacia. The following bone markers were evaluated: among bone formation markers, total alkaline phosphatase (TAP), bone alkaline phosphatase (BAP), osteocalcin (bone Gla protein, BGP) and procollagen type I N propeptide (PINP); among bone resorption markers, serum C-terminal cross-linked telopeptide of type I collagen (s-CTx), urinary hydroxyproline (HYP), and N-terminal and and C-terminal cross-linked telopeptides of collagen (NTx and - and -CTx). In addition, the /-CTx ratio was evaluated. TAP and BAP were the markers with the highest increase in both frequency and magnitude. Conversely, BGP values were low in all patients. Collagen-related markers were slightly increased in nearly half of the patients. Among them, PINP showed the highest proportion of increased values. The /-CTx ratio was within normal values in all patients. In conclusion, TAP and BAP seem to be the best bone markers in the diagnostic evaluation of hypophosphatemic osteomalacia. In addition, their high values associated with low levels of BGP provide an even more reliable biochemical profile of this disorder, when associated with the classic mineral and skeletal homeostasis abnormalities.     

Altered Integrin Expression and the Malignant Phenotype: The Contribution of Multiple Integrated Integrin Receptors

The integrins are a family of cell surfaceadhesion receptors that mediate adhesion to eithercomponents of the extracellular matrix or to othercells. The ₁ family of integrinsrepresent the major class of cell substrate receptors withspecificities primarily for collagens, laminins, andfibronectins. The role of the integrin family of cellsurface adhesion receptors in normal mammary glandmorphogenesis and the contributions of altered integrinreceptor expression to the invasive and metastaticphenotype have been the primary focus of our lab, aswell as a number of other laboratories. The_{2 1} integrin is expressed at high levels by normaldifferentiated epithelial cells including those of thenormal breast. Using breast cancer as a model, weevaluated changes in integrin expression in malignancy. We and other investigators made the keyobservation that _{2 1}integrin expression is decreased in adenocarcinoma ofthe breast in a manner that correlates with the stage ofdifferentiation. Studies of other adenocarcinomas have yielded similarresults. When the _{2 1}integrin was reexpressed in a poorly differentiatedmammary carcinoma that expressed no detectable₂ integrin subunit, a dramatic reversion of malignant phenotype to adifferentiated epithelial phenotype was observed,indicating a critical role for₂₁ expression inmammary gland differentiation. Other laboratories using monoclonal antibodies to competitivelyinhibit _{2 1} integrinadhesion or oncogenic transformation using c-erb2 haveconfirmed the important role of that ₂₁ integrin in mammary gland morphogenesis. Re-expression of the_{2 1} integrin alsoresults in upregulation of both the ₆and ₄ integrin subunits. To determinethe contribution of enhanced ₆ and₄ integrin expression to the abrogation of the malignantphenotype by _{2 1}integrin expression, we have now separately re-expressedthe human ₆ or ₄integrin subunit in the breast cancer model.     

Plasma proteins present in human cortical bone: Enrichment of theαHS-glycoprotein

The spectrum of plasma proteins present in human cortical bone and permanent dentine has been determined. One plasma glycoprotein, theHS-glycoprotein, was found to be present at a high concentration in both bone and dentine and was shown to be concentrated in the mineralized tissues with respect to the other plasma proteins by factors of between 30 and 100. In this respect theHS-glycoprotein is analogous to the G2B-glycoprotein and -glycoprotein of bovine and rabbit b one, respectively. The binding ofHS-glycoprotein and albumin to calcium phosphates generated within serum samples has been studied at different serum: precipitate ratios. In each case all theHS-glycoprotein was removed from the samples and theHS-glycoprotein was concentrated with respect to albumin by factors ranging from 370 at the highest serum: precipitate ratio to 25 at the lowest ratio. The plasmaHS-glycoprotein concentrations of patients with Paget's disease of bone were shown to be substantially lower than the normal range, with significant negative correlation between theHS-glycoprotein concentration and the plasma alkaline phosphatase activity.     

The reducing end of αGal oligosaccharides contributes to their efficiency in blocking natural antibodies of human and baboon sera

Synthetic galactosyl oligosaccharides were tested for their ability to inhibit the cytotoxic reaction of human and baboon natural antibodies on PK15 cells in culture. Methyl--Gal gave weak inhibition, Gal1-3Gal substantially inhibited the reaction (400 M), and Gal1-3Gal2-4GlcNAc was ten times more efficient (30 M). The modification from to anomeric configuration of the nonreducing end resulted in a complete loss of activity, while substitutions at the reducing end induced only a partial loss of activity. These observations suggest that natural anti-Gal antibodies recognize the epitope from its nonreducing end, but that substitutions at the reducing terminus can modify the antibody-binding capacity. Modified tri- and tetrasaccharides are better inhibitors than the disaccharide but not as good as Gal1-3Gal1-4GlcNAc. The reducing terminus therefore contributes some energy to the reaction, indicating that certain oligosaccharides will be of more potential clinical use than others.