Segmental Diffuse Inflammatory Pseudopolyps Associated With Diverticulitis

Introduction/Objective

Inflammatory pseudopolyps (IPs) often develop in response to chronic active inflammation in patients with inflammatory bowel disease (IBD). IPs can be diffuse and numerous in severe IBD. IPs can also occur from other chronic active injuries, such as ulcers, persistent infection, ischemic colitis, anastomotic site and diverticulitis. IPs arising from diverticulitis is uncommon and generally few in numbers.

We report a rare case of a patient with segmental diffuse IPs associated with diverticulitis in the absence of IBD.

Methods

A 59-year-old male patient with a history of sigmoid diverticulitis presented with abdominal pain and was treated with antibiotics. Three months later he had severe recurrent diverticulitis. CT scan showed wall thickening of the sigmoid colon and multiple sigmoid diverticula. Colonoscopy showed extremely severe inflammatory colitis in the area of diverticulitis between 25.0 and 35.0 cm from the anal verge. Biopsies revealed cryptitis, crypt abscesses, crypt architecture distortion and Paneth cell metaplasia. The patient underwent laparoscopic left colectomy.

Results

The rectosigmoid colon specimen is 18.0 cm in length and 6.0 cm in diameter. There was a 7.5 cm segment with numerous polyps. Multiple diverticula with diverticulitis were also identified in this region. The rest of the colon was unremarkable. Microscopic examination revealed numerous IPs and multiple diverticulitis. No evidence of IBD was identified.

Conclusion

To our knowledge, this is the first time that segmental and diffuse IPs are described with associated diverticulitis in the absence of IBD. The pathogenesis of IPs in non-inflammatory bowel disease is not well described. Previously, it was reported that diverticulosis and subsequent diverticulitis has no significant impact on the development of IPs, and IPs may arise independent of location and time of diverticulitis. Sporadic IPs may also appear without any underlying pathology. In the current case, there were multiple diverticula and diffuse diverticulitis, which may have contributed to the diffuse IPs. Further clinical inquiries revealed no clinical signs and symptoms of IBD.

Extravascular administration of interferon alfa-N3 increases serum exposure and 2-5(A) synthetase activity

The objective of this study was to evaluate the pharmacokinetics, pharmacodynamic response, and safety of single intravenous (i.v.), intramuscular (i.m.), and subcutaneous (SQ) doses of interferon alfa-n3. Six healthy adults received 10 million units of i.v., i.m., and SQ interferon alfa-n3 in a randomized three-period crossover fashion. Serum interferon alfa-n3 concentrations and 2'-5'-oligoadenylate synthetase (2-5[A] synthetase) activity in peripheral blood mononuclear cells were determined after each dose. Extravascular administration significantly increased mean serum interferon alfa-n3 AUC values (1152 +/- 214, 944 +/- 209, and 576 +/- 188 U.h/mL, p < 0.001, with SQ, i.m., and i.v. administration, respectively) and 2-5(A) synthetase activity at 36 and 48 hours after dosing. Mild to moderate flu-like symptoms were reported by all 6 subjects, with no route-related difference in type or incidence. Interferon alfa-n3 is generally well tolerated by the i.v., i.m., and SQ routes, with i.m. and SQ administration maximizing serum exposure and 2-5(A) synthetase activity.

A new contained human immunodeficiency virus type 1 host cell system for evaluation of antiviral activities of interferons and other agents in vitro

HIV-host infection systems in vitro are important in the pre-clinical assessment of anti-retroviral drug activity. The present report describes the development of a new HIV-host model comprised of an epithelial cell line of HeLa lineage (HeLa-1), transfected with expression vectors bearing tat and rev (TART) genes of HIV-1 as well as the CD4 receptor gene, and HIV-1(delta Tat/Rev), a biologically contained strain of HIV-1 deleted in tat and rev. Measurement of infectivity, by syncytium formation and reverse transcriptase assay, revealed that HeLa-1 is infected with HIV-1(deltaTat/Rev). This virus failed to productively infect the TART-deficient CD4-positive HeLa cells, confirming its contained, non-infectious nature. The HeLa-1/HIV-1deltaTat/Rev system was used to measure the anti-retroviral activity of a human leukocyte-derived interferon (IFN-alphan3) preparation, several nucleoside analogs, and protease inhibitors. The HeLa-1/ HIV-1(deltaTat/Rev model provides a biologically contained system for the study of the HIV pathogenesis and the relative and combined therapeutic effects of anti-retroviral agents in vitro.

Inhibitory effect of interleukin-10 on human leukocyte interferon-alpha production by Sendai virus

Treatment of human peripheral blood leukocytes (hPBL) with Sendai virus induces significant production of human interferon-alpha (IFN-alpha). Addition of human recombinant interleukin-10 (IL-10) to hPBL in vitro prior to treatment with Sendai virus resulted in considerable inhibition of IFN-alpha production. Downregulation of IFN-alpha production was IL-10 concentration-dependent and observed at IL-10 concentrations of as low as 0.05 ng/ml, with a median effective dose (ED50) of about 5 ng/ml. Inhibition of IFN-alpha production by IL-10 occurred at an early stage of Sendai virus induction. The inhibitory effect of IL-10 on leukocyte interferon production was specific and blocked by pretreatment with neutralizing polyclonal anti-IL-10 antibody. This downregulatory effect is at the transcriptional level, since IL-10 inhibits IFN-alpha mRNA accumulation upon Sendai virus treatment. These data suggest that leukocyte IFN-alpha production is a highly regulated process that is modulated by cytokines such as IL-10 during early immunological response to infection.

Interferon-alpha neutralizing antibodies in HIV and chronic HCV patients treated with natural-source human leukocyte-derived interferon-alpha n3

Human leukocyte-derived IFN-alpha n3 (Alferon N Injection) was administered subcutaneously to treat 20 patients with asymptomatic human immunodeficiency virus type 1 (HIV-1) and 141 patients with chronic hepatitis C virus (HCV) infections. The treatment of HIV-1 and HCV patients, previously untreated with any IFN preparations, did not result in development of neutralizing antibodies to IFN-alpha n3. Among 69 HCV refractory patients who were unresponsive to previous treatment with rIFN-alpha 2b, 2 had neutralizing antibodies to rIFN-alpha 2b prior to IFN-alpha n3 therapy, with no or limited cross-reactivity to IFN-alpha n3. After retreatment with IFN-alpha n3, both patients had detectable neutralizing titers to IFN-alpha n3. Additionally, 2 other patients developed low and transient neutralizing titers to IFN-alpha n3. Interferon subtype specificity of these antibodies was tested against RP-HPLC purified fractions of IFN-alpha n3, as well as rIFN-alpha 2b and rIFN-alpha 8b. Sera from patients previously treated with rIFN-alpha 2b with high antibody titers to rIFN-alpha 2b strongly reacted with the natural IFN-alpha 2b, and to a limited extent with other iFN-alpha subtypes. Neutralizing activity against IFN-alpha 2b was significantly competed out by the presence of a small amount of other interferon subtypes present in IFN-alpha n3. One patient with prior presence of antibodies to IFN-alpha 2b developed a high antibody titer to IFN-alpha 8b with limited reactivity to IFN-alpha n3. Two of the HCV refractory patients with prior neutralizing antibodies to rIFN-alpha 2b responded to IFN-alpha n3 therapy. These data suggest that the presence of neutralizing antibodies to individual IFN-alpha species will not significantly diminish the biological activity and the clinical efficacy of multi-species IFN-alpha n3.

Cytokines induced by Sendai virus in human peripheral blood leukocytes

Human peripheral blood leukocytes (hPBL) are a rich source of natural leukocyte interferon (IFN-alpha) when treated with Sendai virus. Sendai virus treatment of hPBL will also result in significant production of several chemokines and cytokines such as macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, RANTES, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-8, in a time-dependent way. A significant amount of MCP-1 is constitutively produced in overnight culture of leukocytes. The most abundant cytokine is IFN-alpha, which is induced to its maximum level approximately 11-15 h after addition of Sendai virus. The amount of IFN-alpha induced at 15 h after Sendai virus treatment is more than 16-fold higher than those of MIP-1alpha, MIP-1beta, and RANTES. IFN-alpha is also induced more than 60-fold higher than TNF-alpha and IL-8. The amount of IL-6 induced is approximately 400-fold less than IFN-alpha. Limited amounts of other cytokines such as IL-1alpha, IL-1beta, macrophage colony-stimulating factor, TNF-beta, and IFN-gamma are also induced in Sendai virus-treated hPBL. No measurable amount of granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor, leukemia inhibitory factor, IL-2, IL-3, IL-4, IL-5, IL-7, IL-10, IL-11, or IL-12 was induced in the supernatant of Sendai virus-treated hPBL.

Competitor internal standards for quantitative detection of mycoplasma DNA

Homologous internal controls were used as competitor DNA in the polymerase chain reaction for the quantitative detection of mycoplasma DNA. PCR primer sets were designed on the basis of the most conserved nucleotide sequences of the 16S rRNA gene of mycoplasma species. Amplification of this gene was examined in five different mycoplasma species: Mycoplasma orale, M. hyorhinus, M. synoviae, M. gallisepticum and M. pneumoniae. To evaluate the primers, a number of different cell lines were assayed for the detection of mycoplasma infections. All positive cell lines showed a distinct product on agarose gels while uninfected cells showed no DNA amplification. Neither bacterial nor eukaryotic DNA produced any cross-reaction with the primers used, thus confirming their specificity. Internal control DNA to be used for quantitation was constructed by modifying the sizes of the wild-type amplified products and cloning them in plasmid vectors. These controls used the same primer binding sites as the wild-type and the amplified products were differentiated by a size difference. The detection limits for all the mycoplasma species by competitive quantitative PCR were estimated to range from 4 to 60 genome copies per assay as determined by ethidium bromide-stained agarose gels. These internal standards also serve as positive controls in PCR-based detection of mycoplasma DNA, and therefore accidental contamination of test samples with wild-type positive controls can be eliminated. The quantitative PCR method developed will be useful in monitoring the progression and significance of mycoplasma in the disease process.

Radiation inactivation of human gamma-interferon: cellular activation requires two dimers

gamma-Interferon (IFN-gamma) is a 17-kDa broad-spectrum cytokine which exerts its effects on a variety of target cells through its interaction with the IFN-gamma receptor. Although physicochemical studies of Escherichia coli-derived IFN-gamma, as well as its crystal structure, demonstrate that it is a homodimer in solution (M(r) 34,000), previous radiation inactivation studies yielded a functional size for IFN-gamma of 63-73 kDa in an antiviral assay. To understand the relationship between the solution form of IFN-gamma and the moiety that actually binds to the cellular receptor and activates cells, we examined irradiated nonradioactive and 32P-labeled IFN-gamma for its migration in SDS/polyacrylamide gels (to determine its physical integrity), its binding to cells, its reactivity in an ELISA, and its antiviral activity. The functional size of IFN-gamma differed in the assays, being 22 +/- 2 kDa for the physical destruction of IFN-gamma, 56 +/- 2 kDa for the cellular binding assay, 45-50 kDa for reactivity in the ELISA, and 72 +/- 6 kDa for antiviral activity. The results from the binding assays constitute direct evidence that IFN-gamma binds to its cellular receptor as a dimer. However, for antiviral activity, the functional mass is equivalent to a tetramer. This is consistent with models involving ligand-induced receptor dimerization, whereby two dimers acting in concert (equivalent to the target size of a tetramer) are required to activate cells in the antiviral assay.

Sublocalization on chromosome 21 of human interferon-alpha receptor gene and the gene for an interferon-gamma response protein

The cellular responses to alpha and beta interferons (IFN-alpha and -beta) are mediated through the IFN-alpha/beta (type I) receptor, while the response to IFN-gamma is mediated through the IFN-gamma (type II) receptor. The receptors for IFN-alpha/beta and IFN-gamma are encoded by genes on human chromosomes 21 and 6q, respectively. The presence of chromosome 21q confers both ligand binding and responsiveness to human IFN-alpha/beta, whereas chromosome 6q confers binding of Hu-IFN-gamma, but not cellular responsiveness on somatic cell hybrids. Chromosome 6q (i.e., the Hu-IFN-gamma receptor gene) and chromosome 21q are both necessary for the cellular response of somatic cell hybrids (from fibroblasts) to Hu-IFN-gamma. It is conceivable that the factor mediating activity through the IFN-gamma receptor is, in fact, the IFN-alpha receptor, or that the two genes are distinct but part of an "interferon response" region. Here we more precisely localize on human chromosome 21 the genes for the IFN-alpha receptor and for the factor(s) mediating the action of IFN-gamma through the chromosome 6-encoded receptor. Hamster-human somatic cell hybrids containing various fragments of human chromosome 21 were used. The presence of the human IFN-alpha/beta receptor was determined by binding 32P-labeled human IFN-alpha to cells, covalently cross-linking the [32P]IFN-alpha-receptor complex, and analyzing it by SDS-polyacrylamide gel electrophoresis. The presence of the IFN-gamma receptor-related factor mediating cellular responsiveness was determined by HLA induction in hybrid cells containing the IFN-gamma receptor (chromosome 6q), a transfected copy of the human HLA-B7 gene, and various portions of chromosome 21. In all hybrids examined, the two genes cosegregate. Specifically, both genes are localized to the region of chromosome 21 containing the markers D21S58, D21S65, and GART and appear to be proximal to D21S58. The implications for IFN action are discussed.

Chromosome mapping of biological pathways by fluorescence-activated cell sorting and cell fusion: human interferon gamma receptor as a model system

Human chromosome 6 encodes both the interferon gamma receptor as well as the class I major histocompatibility complex antigens, HLA-A, -B, and -C. However, the presence of chromosome 6 in somatic cell hybrids is insufficient to confer sensitivity to human interferon gamma (Hu-IFN-gamma) as assayed by class I HLA induction; it is necessary for both human chromosomes 6 and 21 to reside in the hybrid to generate a response to Hu-IFN-gamma. Treatment of such a hamster-human hybrid, Q72-18, with Hu-IFN-gamma induces the class I HLA antigens. Q72-18 cells selected by fluorescence-activated cell sorting for the loss of class I HLA induction also lost human chromosome 21. Fusions of such cells to a hybrid that contains only human chromosome 21 reconstitutes HLA antigen induction by Hu-IFN-gamma. Furthermore, fusions of hybrids containing a translocated human chromosome 6q and the HLA-B7 gene to a line containing only human chromosome 21 or a translocated 21q also reconstitutes HLA-B7 mRNA and antigen induction by Hu-IFN-gamma. Thus the segregation of cells on the basis of a biological effect by fluorescence-activated cell sorting and reconstitution by hybrid fusion provides a strategy by which some biological pathways can be mapped at a chromosomal level.

Immune interferon receptor: chemical and enzymatic sensitivity

Human immune interferon-gamma (HuIFN-gamma) labeled with 32P was used to study the structure of IFN-gamma receptor. When [32P]HuIFN-gamma was bound and crosslinked to IFN-gamma the receptor of human cells with a bifunctional crosslinker disuccinimidyl suberate (DSS), a single diffused 32P-labeled band corresponding to the IFN-gamma.receptor complex was visualized by SDS-polyacrylamide gel electrophoresis and autoradiography. The size of the [32P]-HuIFN-gamma.receptor complex was about 100-120 kD. Separation of crosslinked complex in reducing and nonreducing gels showed no size differences, suggesting the absence of interchain disulfide linkage. However, binding and formation of the crosslinked IFN-gamma. receptor complex on cells was diminished in the presence of the disulfide reducing agent dithiothreitol (DTT). The reduction was DTT-dose-dependent, suggesting that intramolecular disulfides of the receptor are important for binding. Also, [32P]HuIFN-gamma did not bind if cells were pretreated with and then washed free of DTT, suggesting an irreversible reduction of intrachain disulfide bonds, presumably of the receptor. [32P]HuIFN-gamma also specifically binds to human placental membranes. Each placenta has about 170 ng of IFN-gamma receptors. Covalent attachment of [32P]HuIFN-gamma to placental plasma membranes via DSS produced 2 crosslinked complexes with the molecular sizes of 100-120 kD and 60-70 kD. The IFN-gamma.receptor complex of placental membranes was solubilized with NP-40 after DSS treatment and partially purified with immobilized antibody to the carboxyl terminus of IFN-gamma. Treatment of the receptor complex with trypsin and papain was used to demonstrate its differential proteolytic sensitivity.

Direct nanogram quantitation of nucleic acid and protein with a continuous-flow microcell

A simple method for rapid nanogram measurement of nucleic acids and proteins is described. It requires only 5 to 10 microliter of sample solution which is injected into the postcolumn flow stream of a high-performance liquid chromatograph. Samples are analyzed by uv detection at 260 nm for nucleic acids and 280 nm for proteins with a diode array detector. Analyzing speed is two samples per minute and the amount to be analyzed ranges from 3 ng to 80 micrograms for nucleic acids and 10 ng to 80 micrograms for bovine serum albumin, irrespective of the sample volume. The method is particularly useful for fast, accurate, and trace amount measurement of purified DNA, RNA, and protein samples in small volumes.

Human chromosomes 6 and 21 are required for sensitivity to human interferon gamma

The human interferon gamma receptor has previously been assigned to chromosome 6. Chromosome 6 also encodes HLA, the human class I major histocompatibility antigens. However, the presence of chromosome 6 in hamster-human hybrids is by itself insufficient to confer sensitivity to human immune interferon as measured by the induction of human HLA. Human chromosome 21 was found to be the second chromosome essential for HLA inducibility. Similar results were found with mouse-human somatic cell hybrids. Thus, at least two steps are involved in the action of human interferon gamma: the binding of interferon gamma to its receptor coded by chromosome 6 and the linkage of this binding event through a factor coded by chromosome 21 to trigger biological action. Both of these steps are species-specific.

Preparation of 32P-labeled murine immune interferon and its binding to the mouse immune interferon receptor

Murine immune interferon (Mu-IFN-gamma) can be radiolabeled with [gamma-32P]ATP by the catalytic subunit of cAMP-dependent protein kinase. The resulting 32P-labeled Mu-IFN-gamma (32P-Mu-IFN-gamma) with high radiological specific activity (60-260 muCi/micrograms) retains biological activity. Acid hydrolysis of 32P-Mu-IFN-gamma or 32P-labeled human IFN-gamma leads to the release of [32P]phosphoserine but not phosphothreonine or phosphotyrosine. With 32P-Mu-IFN-gamma, we have demonstrated that there are 5 X 10(3) to 1.5 X 10(4) receptors per-cell on several murine cell lines of diverse origin and that the Kd at 24 degrees C for these cells is in the range of 1 X 10(-10) to 1 X 10(-9) M. Covalent binding of 32P-Mu-IFN-gamma to its receptor results in the formation of several specific high-molecular weight products, the major one of which has an apparent molecular weight of 90,000-100,000. If this represents a 1:1 complex of Mu-IFN-gamma and its receptor (or its binding subunit), the murine interferon gamma receptor has a molecular weight of 75,000-85,000.

The gene for the human immune interferon receptor is located on chromosome 6

When 32P-labeled human recombinant immune interferon gamma (Hu-[32P]IFN-gamma) is crosslinked to human cells with disuccinimidyl suberate, a complex with a molecular size of approximately equal to 117,000 Da was identified by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The formation of this complex is inhibited when the binding is performed in the presence of excess unlabeled Hu-IFN-gamma. The specific formation of the 117,000-Da complex is not observed in mouse L cells or Chinese hamster ovary cells. This complex shows all of the criteria that identify it as the Hu-IFN-gamma receptor or its binding subunit. The same complex can be formed following binding and covalent crosslinking of Hu-[32P]IFN-gamma to some hamster-human or mouse-human somatic cell hybrids. The presence of human chromosome 6 in the hybrids is necessary and sufficient for the formation of this complex. More specifically, the long arm of chromosome 6 seems sufficient. Therefore, we have localized the gene for the Hu-IFN-gamma receptor (or its binding subunit) to the long arm of human chromosome 6. The presence of this chromosome in the somatic cell hybrids is not adequate, however, to confer antiviral resistance to the hybrids in the presence of Hu-IFN-gamma.

Characterization of receptors for immune interferon in U937 cells with 32P-labeled human recombinant immune interferon

Recombinant human immune interferon (HuIFN-gamma) was labeled with [gamma-32P]ATP and cyclic-AMP-dependent protein kinase from bovine heart to a specific radioactivity of 11,000 Ci/mmol. At least two molecules of phosphate were incorporated per molecule of interferon. The binding of [32P]HuIFN-gamma to human U937 histiocytic lymphoma cells was time dependent, and displaceable by HuIFN-gamma but not by HuIFN-alpha A or HuIFN-beta. The specific binding was saturable with less than 10% nonspecific binding. The dissociation constant of [32P]HuIFN-gamma for U937 interferon receptors was calculated to be 1.5 X 10(-10) M with a total of 1,800 binding sites/cell. Dissociation of bound [32P]IFN-gamma at 24 degrees C exhibited two distinct rates. A fast dissociation with a specific rate constant of 0.141 min-1, and a slow dissociation with a specific rate constant of 0.0027 min-1. The Kd for [32P]HuIFN-gamma was calculated from kinetic constants to be 5.4 X 10(-10) M.

Rapid vesicle reconstitution of alprenolol-Sepharose-purified beta 1-adrenergic receptors. Interaction of the purified receptor with N

beta-Adrenergic receptors from turkey erythrocyte membranes have been purified 1000-4000-fold using alprenolol-Sepharose affinity chromatography. Addition of deoxycholate solubilized egg phosphatidylcholine to the beta-adrenergic receptor, that is 5-10% pure and in 0.1% digitonin, followed by Sephadex G-50 gel filtration in buffers containing 30 mM MgCl2 results in 65-70% of the receptor being incorporated into phospholipid vesicles. The beta-adrenergic receptor as detected by photoaffinity labeling using [125I]azidobenzylpindolol in membranes and after alprenolol-Sepharose chromatography is a Mr = 40,000 peptide. Addition of deoxycholate extracts of human erythrocyte membranes, which contain the guanine nucleotide stimulatory regulatory protein of adenylate cyclase (Ns) but not beta-adrenergic receptor, were used to reconstitute a guanine nucleotide-mediated change in agonist affinity for the receptor. These results demonstrate that the alprenolol-Sepharose affinity purified beta-adrenergic receptor is functional in both ligand binding and coupling to Ns. The procedure is rapid, efficient and should be generally applicable to beta-adrenergic receptor and Ns from several different membrane systems.

Use of photolabels to probe the Na,K-ATPase and the beta-adrenergic receptor

Radioactive photoaffinity labels have been used to probe the cardiac glycoside-binding site of Na,K-ATPase and the catecholamine-binding site of the beta-adrenergic receptor. For the Na,K-ATPase, a systematic positioning of the photoactive group on the first, second, and third digitoxoses of digitoxin showed that the specific radioactivity in the alpha subunit decreased 5- to 20-fold as the photoactive group was extended further away from the steroid nucleus, whereas the beta subunit is positioned very close to the alpha subunit in the region of the cardiac glycoside-binding site. For the beta-adrenergic receptor, a new class of orthoiodophenylazide derivatives of pindolol was prepared with carrier-free 125I. Photolysis of the beta-adrenergic receptor of duck, turkey, pigeon, and frog erythrocyte membrane with one of these compounds (iodoazidobenzylpindolol) allowed identification of the receptor polypeptides. It was found that the size of the polypeptides and the number of polypeptides varied.

Photoaffinity labeling of the beta-adrenergic receptor from cultured lymphoma cells with [125I]iodoazidobenzylpindolol: loss of the label with desensitization

The beta-adrenergic antagonist [125I]iodoazidobenzylpindolol ( [125I]IABP) specifically photolabeled two polypeptides in membrane preparations from wild-type (WT) and coupling protein-deficient cyc- cultured lymphoma cells. The molecular weights of the two polypeptides determined by sodium dodecyl sulfate/polyacrylamide gel electrophoresis were 65,000 and 55,000. They were labeled in a ratio of approximately 1:1. Pretreatment of intact WT or cyc- cells with 1.0 microM epinephrine for 15 min (desensitization) resulted in a greater loss of the 55,000 Mr polypeptide (40-60%) relative to the 65,000 Mr peptide (10-30% loss). An 18- to 24-hr pretreatment of WT cells with terbutaline (down-regulation) led to a greater than 90% reduction of the photolabeling of both polypeptides, whereas a similar pretreatment of cyc- cells resulted in no further loss of labeled receptor than that observed after only a 15-min pretreatment with epinephrine. There was no indication of a change in the electrophoretic mobility of the [125I]IABP-labeled receptors after either short- or long-term agonist pretreatment. These data provide direct evidence for heterogeneity of the beta-adrenergic receptor in lymphoma cells. The differential loss of the [125I]IABP labeling in the two polypeptides suggests a functional heterogeneity as well.

Synthesis and characterization of iodoazidobenzylpindolol

A high affinity beta-adrenergic ligand, iodoazidobenzylpindolol, was synthesized and characterized. The absorption spectrum of this compound changed markedly upon photolysis, consistent with decomposition of the azide group. This compound has a KD of 5--7 x 10(-10) M for the duck erythrocyte ghost beta-adrenergic receptor when measured in a competitive binding assay.

Iodoazidobenzylpindolol, a photoaffinity probe for the beta-adrenergic receptor

A high-affinity pindolol derivative, (+/-)-1-(indol-4-yloxy)-3-[1-(p-azido-m-iodophenyl)-2-isobutylamine]-2-propanol (IABP), has been prepared; it contains an iodide and an azide functional group and acts as a photoaffinity label for the beta-adrenergic receptor. When [125I]IABP (specific activity 1300 Ci/mmol) was photolyzed with crude duck erythrocyte membrane preparations, which contain beta-adrenergic receptor binding sites highly specific labeling of two polypeptides was observed upon electrophoresis on sodium dodecyl sulfate/polyacrylamide gels. These two polypeptides, A (Mr approximately 45,000) and B (Mr approximately 48,500), and B (Mr approximately 48,500), were photolabeled in a ratio of approximately 4:1 A/B. Binding of [125I]IABP and covalent derivatization of the beta receptor was at least 70% specific. The data indicate that [125I]IABP is a very effective compound for identification of polypeptides containing the beta-receptor binding site even in crude membrane preparations. The beta receptor of the duck erythrocyte plasma membrane may be composed of more than one subunit.

Synthesis and antibacterial and antifungal activities of alkyl and polyhalophenyl esters of benzo[b]-3-methyl-2-furancarbamic acid

Several alkyl and polyhalophenyl esters of benzo[b]-3-methyl-2-furancarbamic acid were prepared and tested for antifungal activity against Candida albicans, Penicillium notatum, and Aspergillus niger. The pentachlorophenyl ester was the most active substance and the only compound to show antibacterial activity against Staphylococcus aureus.