Nonspecific motor disorder of the esophagus: a real disorder or a manometric curiosity?

BACKGROUND

Nonspecific esophageal motility disorder (NEMD) has become a catchall term to describe abnormal esophageal manometric findings that do not meet strict criteria for established esophageal motility disorders. The aim of this study was to determine whether NEMD is a real esophageal motility disorder characterized by impairment of its motor function or simply a manometric disturbance with no clinical consequences.

METHODS

Esophageal transit of liquid and semisolids was studied using radioscintigraphic techniques in 10 symptomatic patients with manometrically diagnosed NEMD, 26 healthy control subjects, and 40 disease control subjects. The disease controls included 24 patients with achalasia, 9 with scleroderma, and 7 with diffuse esophageal spasm.

RESULTS

Patients with NEMD had no impairment of liquid emptying compared with healthy controls. Liquid emptying was markedly delayed in patients with achalasia and scleroderma. However, semisolid emptying was markedly delayed in patients with NEMD compared with healthy controls (P < 0.001), and the extent of its delayed emptying was similar to that seen in patients with achalasia, scleroderma, and diffuse esophageal spasm.

CONCLUSIONS

NEMD is not a manometric curiosity but a disorder characterized by selective impairment of semisolid emptying.

[Immunological approach for classification of free-living amoeba in Korea]

Acanthamoeba spp., free-living amoebae inhabited in moist soil, pond, freshwater, sewage, atmosphere and swimming pool, may be causative protozoa of the fatal primary amoebic meningoencephalitis in experimental animals and humans. In this study, Acanthamoeba spp., including Acanthamoeba sp. YM-4 (isolated strain from Korea) had been compared by the two-dimensional electrophoresis and hybridoma technique as well as the difference of morphological characteristics. Trophozoite of Acanthamoeba sp. YM-4 is usually uninucleate and show the hyaline filamentous projections (acanthopoda). No flagellate stage observed. Cysts have two walls, the outer wall is nearly circular, but inner wall is oval or some irregular. As results of SDS-PAGE for lysate of Acanthamoeba sp. YM-4, 16 major protein fractions are similar to those of A. culbertsoni, but different to A. royreba and A. polyphaga. Findings of two-dimensional electrophoretic patterns of Acanthamoeba sp. YM-4 are almost same to those of A. culbertsoni, The isotype of monoclonal antibodies produced from McAY 6, McAY 7, McAY 8, McAY 13 and McAY 16 clones were IgG1, and McAY 10 and McAY 11 clones were IgM. As results of the cross-reactivity among various amoebae using ELISA with monoclonal antibodies, McAY 7 monoclonal antibody (molecular weight 43 kDa by EITB) was only reacted with Acanthamoeba sp. YM-4, but McAY 6 and McAY 10 monoclonal antibodies were reacted to A. culbertsoni as well as Acanthamoeba sp. YM-4.

Measurement of serum rubella antibody titers in Korean children, female adolescents, and pregnant women

IgG antibody titers to rubella virus in serum of 322 nuchal cord blood, 1,473 children, and 1,103 reproductive and pregnant women were detected in Soonchunhyang University Hospital in Korea. Positive rate of IgG antibody to rubella virus was 86.3% (278/322) in nuchal cord blood, 68.0% (991/1,458) in children. The IgG antibody from the mother disappeared between the 7th to 11th month after birth, and then the positive rate increased as age increased. In the reproductive age group including pregnant women, positive rate of IgG antibody was 81.8% (894/1,103). Therefore, it was known that there was a possibility that 18.9% of this group would be attacked with rubella in Korea.

Preferential expression and activity of multidrug resistance gene 1 product (P-glycoprotein), a functionally active efflux pump, in human CD8 + T cells: A role in cytotoxic effector function

The multidrug resistance gene 1 (mdr 1) product, the P-glycoprotein (Pgp), is a 170-kD transmembrane transport protein, whose overexpression is associated with multidrug resistance in cancer cells and in chloroquine-resistant Plasmodium falciparum infection. In this study we show that normal freshly isolated human lymphocytes express low levels of mdr 1 mRNA and membrane Pgp. Although Pgp is expressed in both CD4+ and CD8+ T cells, it is preferentially expressed in CD8+ T cells. Activation of T lymphocytes with phytohemagglutinin leads to an amplification of both mdr 1 mRNA and membrane Pgp in T cells. P-glycoprotein in T cells is a functionally active efflux pump as demonstrated by decreased retention of rhodamine-123 and its increased accumulation by cyclosporin A, an inhibitor of Pgp function. In addition, MRK-16 antibody increased accumulation of Rh123 in CD8+ T cells. Furthermore, MRK16 anti-P-glycoprotein monoclonal antibody, in a concentration-dependent manner, inhibited T lymphocyte-mediated cytotoxicity. These data suggest a physiologic role of P-glycoprotein in cytotoxic T-lymphocyte effector function.

Probing the opioid receptor complex with (+)-trans-SUPERFIT. II. Evidence that mu ligands are noncompetitive inhibitors of the delta cx opioid peptide binding site

Previous studies delineated two classes of delta binding sites; a delta binding site not associated with the opioid receptor complex, termed the delta ncx site, and a delta site associated with the opioid receptor complex, termed the delta cx site. The delta ncx site has high affinity for [D-Pen2,D-Pen5]enkephalin, and is synonymous with what is now identified as the delta 1 binding site. Pretreatment of membranes with the delta-selective acylating agents FIT, or (+)-trans-SUPERFIT, deplete membranes of the delta ncx binding site, which permits the selective labeling of the delta cx binding site with [3H][D-Ala2,Leu5]enkephalin. The present study compared the properties of the delta cx binding site present in brain membranes pretreated with (+)-trans-SUPERFIT with the properties of the delta cx site present in untreated membranes. The major findings are: 1) pretreatment of membranes with (+)-trans-SUPERFIT decreased the IC50 values of delta-preferring drugs, and increased the IC50 values of mu-preferring drugs, for the delta cx binding site; 2) the degree of delta selectivity was highly correlated with the magnitude of the (+)-trans-SUPERFIT-induced shift in the IC50 values; 3) the ligand-selectivity patterns of the mu and delta cx sites present in (+)-trans-SUPERFIT-pretreated membranes were poorly correlated; 4) whereas mu-preferring drugs were noncompetitive inhibitors of [3H][D-Ala2,Leu5]enkephalin binding to the delta cx site, delta-preferring drugs were competitive inhibitors.(ABSTRACT TRUNCATED AT 250 WORDS)

Proteolytic modification of raw-starch-digesting amylase from Bacillus circulans F-2 with subtilisin: separation of the substrate-hydrolytic domain and the raw substrate-adsorbable domain

Raw starch-digesting amylase (BF-2A, 93,000 Da) from Bacillus circulans F-2 was converted into two components during digestion with subtilisin. The two components were separated and designated BF-2A' (63 kDa) and BF-2B (30 kDa), respectively. BF-2A' exhibited the same hydrolysis curve for soluble starch as the original amylase (BF-2A). Moreover, the catalytic activities of original and modified enzymes were indistinguishable in Km, Vmax and in their specific activity for soluble starch hydrolysis. However, its absorbability and digestibility on raw starch was greatly decreased. Furthermore, the enzymatic action pattern on soluble starch was differed greatly from that of BF-2A. The stability of the enzymes decreased below pH 5.5 and at 50 degrees C, while it was quite stable even at pH 12. On the other hand, the smaller peptide (BF-2B) could be adsorbed onto raw starch. From these results, it is suggested that the larger peptide (BF-2A') has a region responsible for the expression of the enzyme activity to hydrolyze soluble substrate, and the smaller peptide (BF-2B) plays a role on raw starch adsorption and also contributes to the original enzyme-to-enzyme stabilization. A proposed model of the raw-starch-digesting enzyme from this strain is extensively discussed.

Detection of a human intracisternal retroviral particle associated with CD4+ T-cell deficiency

A number of non-human-immunodeficiency-virus (HIV) type 1 disorders are associated with CD4+ T-cell deficiency and dysfunction. However, the etiopathogenesis of CD4+ T-cell immunodeficiency in these disease states remains unclear. Human intracisternal retroviral (HICRV) particles were detected in a lymphoblastoid cell line exposed to mononuclear cells from a patient with severe CD4+ T-cell deficiency without risk factors for HIV infection. Ultrastructurally, the HICRV is distinct from HIV-1, HIV-2, human T-lymphotropic virus (HTLV) type I, and HTLV-II. Supernatants of activated mononuclear cells showed significant reverse transcriptase activity that was predominantly Mn2+ dependent. The patient's mononuclear cells were negative for HIV-1, HIV-2, HTLV-I, and HTLV-II proviruses as demonstrated by the lack of amplification by PCR. Also, the patient's serum was negative for antibodies to HIV-1, HTLV-I, and HTLV-II and for HIV-1 p24 antigen; however, serum was positive for antibodies against the HICRV as demonstrated by Western blot. Similar HICRV particles were detected in a lymphoblastoid cell line exposed to mononuclear cells from the patient's daughter, who showed CD4+ T-cell dysfunction. The HICRV may be associated with CD4+ T-cell immunodeficiency and dysfunction in patients without risk for HIV-1, HIV-2, HTLV-I, and HTLV-II.

Mantle zone lymphoma of the colon simulating diffuse inflammatory bowel disease. Role of immunohistochemistry in establishing the diagnosis

We describe the first reported case of mantle zone lymphoma of the colon presenting as diffuse ileocolitis simulating severe inflammatory bowel disease. This case serves to illustrate the importance of immunohistochemistry in establishing the diagnosis of lymphoma in extranodal sites.

Genomic variation and segregation of equine infectious anemia virus during acute infection

Equine infectious anemia virus (EIAV) is a lentivirus that infects and persists in the monocyte/macrophage populations of blood and tissues. We employed polymerase chain reaction to investigate the distribution and the level of genome variability of EIAV DNA in different tissues of a horse infected with a highly virulent variant of the Wyoming strain of the virus. Long terminal repeat, gag, and pol primer pairs were used to direct the amplification of EIAV DNA from the peripheral blood mononuclear cells and from cells, presumably the macrophage subtypes, of the kidney, spleen, liver, lymph node, and cerebellum and periventricular regions of the brain. Polymerase chain reaction analysis of four domains within the envelope showed that viral subtypes with particular envelope domains segregated to different tissues as defined by the presence or absence of a given type of domain. Collectively, these results show that virus variants in the env gene home to different tissues, presumably because of selection for tissue-specific envelope determinants.

Leiomyosarcoma of the stomach: determinants of long-term survival

To determine factors associated with a favorable long-term prognosis in gastric leiomyosarcoma, we retrospectively reviewed the medical records of 93 Mayo Clinic patients with this biopsy-proven tumor diagnosed during the 25-year period from 1964 through 1988. Six patients who had Carney's triad (gastric epithelioid leiomyosarcoma, pulmonary chondroma, and functioning extra-adrenal paraganglioma) were excluded from data analysis. The other 87 patients participated in follow-up until death or for a median duration of 5.8 years for those who were alive at the conclusion of the study. The most common symptoms at the time of initial assessment were abdominal pain (51%), melena (36%), and weight loss (16%). Most often, the tumor was located in the greater curvature (25%), fundus (20%), or lesser curvature (16%) of the stomach. Two percent of patients had tumors at multiple sites. All 87 gastric leiomyosarcomas were histologically confirmed; 38% were grade 1, 37% were grade 2, and 25% were either grade 3 or grade 4. Metastatic involvement was noted in 15% of patients at the time of diagnosis. The 5- and 10-year survival rates were 45% and 34%, respectively, and the 5- and 10-year tumor recurrence rates were 57% and 65%, respectively. Variables that were associated with long-term survival were low histologic grade of the tumor, absence of metastatic lesions, and small tumor size (P < 0.01); variables such as site of the tumor, initial symptoms, age, and sex provided no significant additional prognostic information.

Risk of fractures in patients with pernicious anemia

In a series of postmenopausal women previously studied by our group, pernicious anemia was associated with reduced bone mineral density of the spine and with vertebral fractures. To determine whether osteoporotic fractures represent an important clinical problem for such patients, we conducted a population-based retrospective cohort study of all Rochester, Minnesota residents newly diagnosed with pernicious anemia from 1950 through 1979. These 131 individuals were followed through the inpatient and outpatient records of all medical care providers in the community for 1550 person-years. In comparison with fracture rates from the general community, patients with pernicious anemia had a 1.9-fold increase in proximal femur fractures, a 1.8-fold increase in vertebral fractures, and a 2.9-fold increase in distal forearm fractures (all p less than 0.05). Increases in the risk of proximal humerus and pelvis fractures were not statistically significant. Clinicians should be aware that pernicious anemia is associated with an increased risk of osteoporotic fractures, but the mechanism is unknown.

Severe reflux esophagitis after vertical banded gastroplasty for treatment of morbid obesity

Herein we describe two patients with medically refractory, severe reflux esophagitis after vertical banded gastroplasty for morbid obesity. Neither patient had symptoms of reflux preoperatively. Both patients underwent conversion to a vertical Roux-en-Y gastric bypass, an operation that prevents acid and peptic reflux and maintains a weight-reducing anatomy. Symptoms of gastroesophageal reflux are common (they occur in approximately 38% of patients) after vertical banded gastroplasty has been performed. Patients with unusually severe reflux may require operative management.

Gastroparesis: diagnostic and therapeutic strategies

Impairment of gastrointestinal motility is common among patients with chronic dyspepsia. Gastroparesis can lead to devastating clinical consequences including malnutrition, weight loss, metabolic acidosis and psychological dysfunction. In this article, the current concepts of gastric motor function are reviewed and the diagnostic and treatment modalities of gastroparesis are discussed in detail.

[Immunohistochemical observation on the antigens inducing IgG and IgM antibodies against sparganum]

Localization and characterization of the antigenic components of sparganum which induced IgG and IgM antibodies in the host were studied by immunohistochemical techniques and SDS-PAGE and Western blotting. The antigen recognized by IgG antibody of rats or mice which were immunized by infection or injection of crude extracts of metacestodes of Spirometra erinacei, was located in the parenchyma of sparganum, especially at the cortex and around the calcareous corpuscles. The immunoreaction was demonstrated not only in the encysted fibrous wall of host but around the arterioles or venules in the connective tissue of host. The antigen recognized by IgM antibody of rats or mice was also observed in the parenchyma of sparganum and in the connective tissue of host. By 5-20% gradient SDS-PAGE and EIBT, we detected antigenic components by IgG and IgM antibodies of the rat or mouse immunized by infection or injection of crude extract of spargana. Twenty-three antigenic bands from crude extracts of spargana were recognized by IgG antibody and 15 components by IgM antibody of immunized rats. Out of the bands recognized by IgG and IgM antibodies, 15 were cross-reacted each other. Twenty components of excretory-secretory proteins from spargana were recognized by IgG, and 5 components by IgM antibody of immunized rats. By IgG and IgM antibodies of immunized mice, 16 components of crude extracts were recognized by IgG antibody and 9 components by IgM antibody. Twenty components of excretory-secretory preparation were recognized by IgG antibody and 5 components by IgM antibody. Thirteen components of crude extracts were cross-reacted by IgG antibody of rats and mice.

Gastric leiomyosarcoma. Prognostic factors and surgical management

Information on gastric leiomyosarcoma, such as important prognostic factors, patterns of disease recurrence, and optimal methods of treatment, are derived from limited patient experience. We address these questions, with specific focus on whether an advantage could be demonstrated for radical resection compared with wide local excision, by retrospectively investigating 53 patients who underwent surgical treatment at Mayo Clinic, Rochester, Minn. Abdominal pain and/or gastrointestinal bleeding associated with an intramural or exogastric mass were typical features of this disease. Only tumor size and histologic grade were statistically significant prognostic factors. With analysis of survival curves and patterns of recurrence, neither the addition of lymphadenectomy nor the wider tumor-free margins of a radical gastrectomy seemed superior to the more conservative local excision. Therefore, wide local excision remains the preferred treatment when technically feasible.

Effect of pyridoxal phosphate on the formation of cytochrome c1-c and cytochrome c-cytochrome oxidase complexes

The cytochrome c-cytochrome oxidase complex is formed when c reacts with cytochrome oxidase (Kuboyama et al. (1962) Biochem. Biophys. Res. Commun. 9, 534) and the cytochrome c1-cytochrome c complex is formed when c reacts with cytochrome c1 in the presence of the hinge protein (Kim, C.H. and King, T.E. (1981) Biochem. Biophys. Res. Commun. 101, 607). Both complexes are considered to be possible intermediates in electron transfer reaction between these cytochromes. Triply substituted modified cytochrome c by pyridoxal phosphate at lysine residues (Lys-79, 86 and one to be identified) abolishes both complex formations and electron transfer activity with succinate cytochrome c reductase or cytochrome oxidase.

(+)-cis-3-methylfentanyl and its analogs bind pseudoirreversibly to the mu opioid binding site: evidence for pseudoallosteric modulation

Previous studies demonstrated that preincubation of membranes from the brain of the rat with 1 microM (+)-cis-3-methylfentanyl produced a wash-resistant inhibition of mu receptor binding. The present study was designed to: (1) determine the mechanism by which (+)-cis-3-methylfentanyl produced a wash-resistant inhibition of mu receptor binding, and (2) to generate a structure-activity study, using wash-resistant inhibition as the end-point. Pretreatment of membranes with 500 nM (+)-cis-3-methylfentanyl increased the Kd of binding sites for [3H]ohmefentanyl, without altering the Bmax. The increase in the Kd was only partially due to the presence of residual drug and was accompanied by an increase in the dissociation rate of the binding of [3H]ohmefentanyl. Therefore, pretreatment of membranes with (+)-cis-3-methylfentanyl resulted in a lower affinity interaction of [3H]ohmefentanyl with the mu binding site, consistent with a model postulating pseudoallosteric modulation of mu binding sites by (+)-cis-3-methylfentanyl and its analogs. The rank order of potencies for wash-resistant inhibition of the binding of [3H]6 beta-fluoro-6-desoxyoxymorphone or [3H]ohmefentanyl, was lofentanil greater than (+)-cis-3-methylfentanyl greater than ohmefentanyl greater than sufentanil. All other opioids tested (1 microM morphine, 1 microM naloxone, 1 microM fentanyl, 1 microM (+)-cyclazocine, 1 microM (-)-cis-3-methylfentanyl) did not act as wash-resistant inhibitors of mu binding sites. Although the pseudoirreversible IC50 of these agents did not correlate with their ED50 values for producing antinociception, after intravenous administration, the authors speculate that this property, termed "pseudoirreversible inhibition", might contribute to the extraordinary potency of (+)-cis-3-methylfentanyl and its analogs as antinociceptive agents.

Nutritional studies of the roles of dietary protein levels and umami in the preference response to sodium chloride for experimental animals

Previously we found that appetite or preference for sodium chloride depends not only on a genetic factor, but also on the nutritional status, i.e., dietary protein levels. To determine whether all kinds of protein had reducing effects on sodium chloride intake, the effect of dietary protein source on appetite or preference for sodium chloride was studied. It was found that the effect depended not only on protein levels, but also on the protein sources, i.e., amino acid patterns of diets. On the other hand, the turnover time of gustatory taste bud cells was measured by the pulse-labeled method using 3H-thymidine. It was found that the turnover time of gustatory cells in the taste buds of rats fed a low-protein diet was longer than in rats fed a high-protein diet. This suggested that some reduction of receptor functions may occur with low-protein diet. It was found that the dietary protein levels and umami also modified appetite or preference for alcohol solutions.

A carbohydrate-directed heterobifunctional cross-linking reagent for the synthesis of immunoconjugates

A novel, highly water-soluble, heterobifunctional cross-linking reagent, S-(2-thiopyridyl)-L-cysteine hydrazide (TPCH), was synthesized which contains a hydrazide moiety for coupling to aldehyde groups generated in the carbohydrate residues of antibodies by mild periodate oxidation, and a pyridyl disulfide moiety for coupling to molecules with a free sulfhydryl group. Since the carbohydrate moieties are distal to the antigen binding region of antibodies, derivatization with this cross-linker minimizes impairment of the antigen binding function. Derivatization of the human monoclonal IgM antibody 16-88 against human colon carcinoma cells with as many as 16 TPCH cross-linker molecules did not impair its antigen binding capability. Using mild oxidation conditions for antibody derivatization, sialic acid residues were identified as attachment sites for the cross-linker molecules, since after desialylation of antibody 16-88 by neuraminidase virtually no cross-linker molecules could be incorporated. Comparison of TPCH with S-(2-thiopyridyl)mercaptopropionic acid hydrazide and S-(2-thiopyridyl)-L-cysteine, two related cross-linking reagents, revealed that TPCH is most efficiently incorporated into periodate-treated antibody. Based on the structural differences of the cross-linkers, the more efficient incorporation of TPCH appears to be a function of the presence of a hydrazide moiety with an adjacent amino group. When three to four molecules of pyridyl disulfide-derivatized barley toxin were coupled to TPCH-derivatized antibody 16-88, the antigen binding capability remained uncompromised. In addition, no significant impairment of toxin activity upon coupling to the antibody was observed. Based on these data, TPCH may be very useful for the synthesis of immuno-conjugates with no or only minimal impairment of the antigen binding function.

Probing the opioid receptor complex with (+)-trans-superfit. I. Evidence that [D-Pen2,D-Pen5]enkephalin interacts with high affinity at the delta cx binding site

A variety of data support the existence of an opioid receptor complex composed of distinct but interacting mu cx and delta cx binding sites, where "cx" indicates "in the complex." The ability of subantinociceptive doses of [Leu5]enkephalin and [Met5]enkephalin to potentiate and attenuate morphine-induced antinociception, respectively, is thought to be mediated via their binding to the delta cx binding site. [D-Pen2,D-Pen5]Enkephalin also modulates morphine-induced antinociception, but has very low affinity for the delta cx binding site in vitro. In the present study, membranes were depleted of their delta ncx binding sites by pretreatment with the site-directed acylating agent, (3S,4S)-(+)-trans-N-[1-[2-(4-isothiocyanato)phenyl)-ethyl]-3-methy l-4- piperidyl]-N-phenylpropaneamide hydrochloride, which permits selective labeling of the delta cx binding site with [3H][D-Ala2,D-Leu5]enkephalin. The major findings of this study are that with this preparation of rat brain membranes: a) there are striking differences between the delta cx and mu binding sites; and b) both [D-Pen2,D-Pen5]enkephalin and [D-Pen2,L-Pen5]enkephalin exhibit high affinity for the delta cx binding site.

Labeling by [3H]1,3-di(2-tolyl)guanidine of two high affinity binding sites in guinea pig brain: evidence for allosteric regulation by calcium channel antagonists and pseudoallosteric modulation by sigma ligands

Equilibrium binding studies with the sigma receptor ligand [3H]1,3-di(2-tolyl)guanidine ([3H]DTG) demonstrated two high affinity binding sites in membranes prepared from guinea pig brain. The apparent Kd values of DTG for sites 1 and 2 were 11.9 and 37.6 nM, respectively. The corresponding Bmax values were 1045 and 1423 fmol/mg of protein. Site 1 had high affinity for (+)-pentazocine, haloperidol, (R)-(+)-PPP, carbepentane, and other sigma ligands, suggesting a similarity with the dextromethorphan/sigma 1 binding site described by Musacchio et al. [Life Sci. 45:1721-1732 (1989)]. Site 2 had high affinity for DTG and haloperidol (Ki = 36.1 nM) and low affinity for most other sigma ligands. Kinetic experiments demonstrated that [3H]DTG dissociated in a biphasic manner from both site 1 and site 2. DTG and haloperidol increased the dissociation rate of [3H]DTG from site 1 and site 2, demonstrating the presence of pseudoallosteric interactions. Inorganic calcium channel blockers such as Cd2+ selectively increased the dissociation rate of [3H]DTG from site 2, suggesting an association of this binding site with calcium channels.

Wash-resistant inhibition of phencyclidine- and haloperidol-sensitive sigma receptor sites in guinea pig brain by putative affinity ligands: determination of selectivity

Several putative affinity ligands, based on the structures of phencyclidine etoxadrol, 5-methyl-10,11-dihydro-5H-dibenzo[a,d] cycloheptene-5,10-imine (MK801) and 1,3-di-(2-methylphenyl)guanidine (DTG) were evaluated in vitro for their ability to produce a wash-resistant inhibition of phencyclidine and sigma receptor sites in homogenates of the brain of the guinea pig. All the phencyclidine-based ligands, including 1-[1-(3-isothiocyanatophenyl)cyclohexyl]piperidine (Metaphit) and (+/-)-N-(2-isothiocyanatoethyl) MK801 [(+/-)-MK801-NCS], produced a wash-resistant inhibition of binding sites for phencyclidine, labelled by [3H]-1-[1-(2-thienyl)cyclohexyl]piperidine ([3H]TCP) and sigma binding sites, labelled by [3H]DTG. The DTG-based ligands, 1-(4-isothiocyanato-2-methylphenyl)-3-(2-methylphenyl)guanidine (DIGIT) and 1-(4-[2-(2-isothiocyanatoethoxy)ethoxy]-2-methyl-phenyl)-3-(2- methylphenyl)guanidine (DIGIE), produced a wash-resistant inhibition of sigma sites, at concentrations as small as 1 microM and also inhibited binding sites for phencyclidine at larger concentrations (100 microM). Both 1-(3-isothiocyanatophenyl)-1-ethyl-4-(2-piperidyl)-1,3-dioxolane (ETOX-NCS) and 1-[1-(3-bromoacetyloxyphenyl)cyclohexyl]-1,2,3,6-tetrahydropyri din e (Bromoacetyl-PCP) were the most potent and selective inhibitors of the binding of [3H]TCP, while DIGIT was the most selective inhibitor of the binding of [3H]DTG. Future studies will examine the selectivity of these agents in vivo after intracerebroventricular administration.