Detection of group B streptococcus: comparison of an optical immunoassay with direct plating and broth-enhanced culture methods

The aim of this study was to compare the diagnostic accuracy of an optical immunoassay (STREP B OIA, Biostar) to direct plating and broth-enhanced culture for the detection of group B streptococcus (GBS) colonization of the lower genital tract in pregnant women. GBS cultures from the lower genital tract were obtained in a prospective fashion using a dual swab transport system from patients with risk factors for perinatal GBS infection. One swab was used to inoculate a trypticase soy agar plate with 5% sheep blood (TSA) and then placed in Lim broth. The other swab was used to perform the Strep B OIA. Growth of GBS by either direct plating or broth-enhanced culture was used as the gold standard for determining GBS colonization. Of the 524 women in the study, 90 women had positive cultures (either TSA or Lim broth). The sensitivity, specificity, positive predictive value, and negative predictive value of the Strep B OIA were 47% (42/90), 96% (416/434), 70% (42/60), 90% (416/464). The sensitivity, specificity, positive predictive value, and negative predictive value of the TSA were 61% (55/90), 100% (434/434), 100% (55/55), 93% (434/469). The sensitivity, specificity, positive predictive value, and negative predictive value of Lim broth were 97% (87/90), 100% (434/434), 100% (87/87), and 97% (434/437). The sensitivity of the Strep B OIA to detect light GBS colonization and heavy GBS colonization, as determined by the TSA, was 53% (19/36) and 90% (17/19), respectively. The Strep B OIA and direct agar plate culture appear to be of limited clinical value due to their poor sensitivities. This study also demonstrates the need to use a selective medium such as Lim broth when assessing for GBS colonization of the lower genital tract.

The receptor-bound conformation of H-Tyr-Tic-(Phe-Phe)-OH-related delta-opioid antagonists contains all trans peptide bonds

Two different models for the receptor-bound conformation of delta-opioid peptide antagonists containing the N-terminal dipeptide segment H-Tyr-Tic (Tic = 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid) have been proposed. Both models are based on spatial overlap of the Tyr1 and Tic2 aromatic rings and N-terminal amino group with the corresponding aromatic rings and nitrogen atom of the nonpeptide delta-antagonist naltrindole. However, in one model the peptide bond between the Tyr1 and Tic2 residues assumes the trans conformation, whereas in the other it is in the cis conformation. To distinguish between these two models, we prepared the two peptides H-Tyr(psi)[CH2NH]Tic-Phe-Phe-OH and H-Tyr(psi)[CH2NH]MeTic-Phe-Phe-OH (MeTic = 3-methyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid) in which a cis peptide bond between the Tyr and Tic (or MeTic) residues is sterically forbidden. Both compounds turned out to be moderately potent delta-opioid antagonists in the mouse vas deferens assay. A molecular mechanics study performed with both peptides resulted in low-energy conformations in which the torsional angle ("omega1") of the reduced peptide bond between Tyr and Tic (or MeTic) had a value of 180 degrees (trans conformation) and which were in good agreement with the proposed model with all trans peptide bonds. Furthermore, this study confirmed that neither of these two peptides could assume low-energy conformations in which "omega1" had a value of 0 degrees (cis conformation). Conformers with that same bond in the gauche conformation ("omega1" = -60 degrees) were also identified, but were higher in energy and showed no spatial overlap with naltrindole. On the basis of these results it is concluded that the receptor-bound conformation of delta-peptide antagonists containing an N-terminal H-Tyr-Tic-dipeptide segment must have all trans peptide bonds.

Interaction of agonist peptide [3H]Tyr-D-Ala-Phe-Phe-NH2 with mu-opioid receptor in rat brain and CHO-mu/1 cell line

Opioid receptor binding properties of [3H]Tyr-D-Ala-Phe-Phe-NH2 (TAPP) were characterized in rat brain and Chinese hamster ovary (CHO) cells expressing the rat mu-receptor. In rat brain, [3H]TAPP labeled a single class of opioid sites with a dissociation constant (Kd) of 0.31 nM and maximal number of binding sites (Bmax) of 119 fmol/mg protein. In CHO-mu/1 cell membranes, the Kd and Bmax values were 0.78 nM and 1806 fmol/mg protein, respectively. Binding to rat brain was demonstrated to be pharmacologically identical to that obtained with CHO-mu/1 cell membranes and modulated by Na+ ions and guanine nucleotides. The high affinity and selectivity of [3H]TAPP together with its low non-specific binding make this radioligand a useful tool for labeling the native and cloned mu-opioid receptor.

Changes in 1,25-(OH)2D3 synthesis and its receptor expression in spleen cell subpopulations of mice infected with LPBM5 retrovirus

This study examines the influence of chronic retroviral infection of mice with a LPBM5 virus mixture on the paracrine system involving immune cells and 1,25-(OH)2D3 in the spleen. Plasma ionized calcium, 25-(OH)D and 1,25-(OH)2D of infected mice were unchanged. In contrast, the specific binding of 1,25-(OH)2D3 to spleen cytosol and the number of monocyte/macrophages expressing 1,25-(OH)2D3 receptors (VDR) were markedly increased. The retroviral infection also influenced the local production of 1,25-(OH)2D3 in the spleen. It did not alter this production in monocyte/macrophages but increased that in isolated T cells. Isolated B cells in control mice did not produce 1,25-(OH)2D3, but they increased the ability of isolated T cells to produce this metabolite during coculture incubations. Infection altered this cell interaction as 1,25-(OH)2D3 production in infected T cells decreased when these cells were cocultured with infected B cells. Thus, chronic retroviral infection alters both the local vitamin D metabolism and VDR expression by immune cells in mice. These findings suggest close local interactions between 1,25-(OH)2D3 and immune system activation during retroviral infection.

Chemical barriers to human immunodeficiency virus type 1 (HIV-1) infection: retrovirucidal activity of UC781, a thiocarboxanilide nonnucleoside inhibitor of HIV-1 reverse transcriptase

UC781, a thiocarboxanilide nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT), inhibited RT DNA polymerase activity in vitro with marked potency. Significant inhibition was noted at a 1:1 molar ratio of UC871 to RT, characteristic of a tight-binding inhibitor. Infectivity of the HIV-1(IIIB) laboratory strain was eliminated in a concentration-dependent manner following short exposure of isolated virion particles to UC781. Neither nevirapine nor certain other carboxanilide nonnucleoside inhibitors were effective in this manner. Endogenous reverse transcription in UC781-treated virus particles was markedly reduced. Treatment of chronically HIV-1-infected H9 cells with UC781 did not alter virus production, but the infectivity of the virus produced by the cells during drug exposure was markedly reduced. Moreover, the infectivity of nascent virus produced by the UC781-treated H9 cells after removal of exogenous drug was dramatically attenuated. Similarly, pretreatment of peripheral blood lymphocytes isolated from HIV-infected patients abolished the infectivity of virus produced by these cells after removal of exogenous drug, as measured by coculture experiments with uninfected cord blood mononuclear cells, indicating the utility of UC781 against a variety of clinical HIV samples. Importantly, preincubation of uninfected MT2 cells with UC781 rendered these cells refractory to subsequent HIV infection in the absence of extracellular drug, an effect that persisted for several days following removal of exogenous drug. These unique properties of UC781 indicate that this nonnucleoside inhibitor may have considerable promise for use in retrovirucidal formulations to minimize the spread of HIV from infected to noninfected individuals.

Chorioamnionitis does not affect fetal urine production in patients with premature rupture of membranes

The objective of this study was to evaluate fetal urine production rate in patients with premature rupture of membranes in the presence or absence of chorioamnionitis and to determine its clinical usefulness. Fetal urine production was evaluated in 30 women between 24 and 39 weeks' gestational age with ruptured membranes. Fetal bladder measurements were determined every 3-5 min for 30-90 min. Chorioamnionitis was defined by both clinical criteria and histological examination of the placenta. The last determination of fetal urine production rate prior to delivery was compared in patients with and without histologic and/or clinical chorioamnionitis. Fetal urine production rate was corrected for gestational age using birth weight prior to analysis. A total of 96 assessments of fetal urine production were performed (range 1-16 per patient). Twelve subjects (40%) had no evidence of chorioamnionitis (group 1), 10 (33%) had histologic chorioamnionitis alone (group 2), and eight (27%) had both clinical and histologic chorioamnionitis (group 3). The mean (+/- SD) urine production rates in these groups were 9.43 +/- 3.15 ml/kg/hr, 10.65 +/- 3.43 ml/kg/hr, and 9.97 +/- 2.81 ml/kg/hr, respectively. The difference in fetal urine production rate between the three groups was not statistically significant. A power analysis revealed that individual group sizes were adequate to document a 50% increase in fetal urine production rate with a type II error of < 10%. There were no documented cases of fetal infection based on neonatal cultures. The presence of histologic or clinical chorioamnionitis does not significantly affect fetal urine production in patients with premature rupture of membranes. The prospective assessment of fetal urine production rate does not appear to be clinically useful as an early indicator of chorioamnionitis.

Evidence for a vitamin D paracrine system regulating maturation of developing rat lung epithelium

Rat fetal lung is a target tissue for 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25 (OH)2 D3]. We have identified the cells that respond to the hormone and tested the hypothesis that the lung is also a source of 1 alpha,25(OH)2D3. We found that 1) at the end of pregnancy (days 20-21) alveolar type II cells (ATII) bore 1 alpha,25(OH)2D3 receptors and responded to the hormone. Incubating these cells with 10(-9) M 1 alpha,25(OH)2D3 for 48 h stimulated the synthesis (87.3 +/- 9.1%) and release (61.7 +/- 6.1%) of disaturated phosphatidylcholine; 2) EB-1213, a 1 alpha,25(OH)2D3 analogue with low calcemic activity, had similar effects on ATII; 3) neither fetal lung fibroblasts nor neonatal ATII (day 2 postpartum) expressed 1 alpha,25(OH)2D3 receptors; and 4) in contrast, fetal lung fibroblasts taken on days 19-22 of gestation converted [3H]25(OH)D3 to [3H]1 alpha,25(OH)2D3, whereas ATII and skin fibroblasts did not. These findings suggest that 1 alpha,25(OH)2D3 is a local mediator of epithelial-mesenchymal cell interactions in the developing rat lung and that 1 alpha,25(OH)2D3 or EB-1213 might be therapeutically useful in treating the respiratory distress syndrome of premature neonates.

The Emery-Dreifuss muscular dystrophy protein, emerin, is a nuclear membrane protein

A large fragment of emerin cDNA was prepared by PCR and expressed as a recombinant protein in Escherichia coli. Using this as immunogen, we prepared a panel of 12 monoclonal antibodies which recognise at least four different epitopes on emerin in order to ensure that emerin can be distinguished from non-specific cross-reacting proteins. All the mAbs recognised a 34 kDa protein in all tissues tested, though minor emerin-related bands were also detected in some tissues. Immunofluorescence microscopy showed that emerin is located at the nuclear rim in all tissues examined. A muscle biopsy from an Emery-Dreifuss muscular dystrophy (EMDM) patient showed complete absence of emerin by both Western blotting and immunohistochemistry, suggesting a simple diagnostic antibody test for EDMD families. Biochemical fractionation of brain and liver tissues showed that emerin was present in nuclei purified by centrifugation through 65% sucrose and was absent from soluble fractions (post-100,000 g). From these results, together with sequence and structural homologies between emerin, thymopoietins and the nuclear lamina-associated protein, LAP2, we suggest that emerin will prove to be one member of a family of inner nuclear membrane proteins.

Utrophin-dystroglycan complex in membranes of adherent cultured cells

In skeletal muscle, dystrophin binds to an oligomeric, transmembrane complex (DAGc; dystrophin-associated glycoprotein complex) which interacts with laminin in the extracellular matrix. We now present biochemical evidence for an association between utrophin (dystrophin-related protein, DRP) and a major DAGc component, beta-dystroglycan (43DAG) in cultured cell lines which contain little if any dystrophin. We have shown also that utrophin and beta-dystroglycan co-localise at or near the plasma membrane and that they co-sediment in large complexes on sucrose density gradients. On the lower plasma membrane, in contact with the substratum, part of the utrophin and beta-dystroglycan staining co-localised with alpha-actinin in a punctate distribution outside classical vinculin-rich focal adhesions. beta-dystroglycan, utrophin, syntrophin (59DAP), and alpha-actinin were found in all adhesion-competent cell lines studied, but levels of the last three proteins were greatly reduced in myeloma cells, which cannot readily attach to substrata. Possible roles for utrophin in cultured cells are considered in the light of recent evidence for involvement of utrophin-glycoprotein complexes in muscle in signal transduction and recruitment of acetylcholine receptors to neuromuscular junctions.

Overexpression of nm23-H1 and nm23-H2 genes in colorectal carcinomas and loss of nm23-H1 expression in advanced tumour stages

Although a reduced expression of nm23 has been shown to correlate with a high metastatic potential in some human cancers, in colorectal cancers, conflicting data have been reported. As there are two homologous genes, nm23-H1 and nm23-H2, which encode the A and B subunits of nucleoside diphosphate kinase, efficient and simplified techniques were designed to selectively study nm23-H1 and -H2 expression in 35 colorectal cancers at both the protein and mRNA levels by immunoblotting, immunohistochemistry, and reverse transcription polymerase chain reaction (RT PCR) using specific antibodies and primers. Nm23-H1 and Nm23-H2 proteins were overexpressed in tumours compared with adjacent mucosa. This overexpression was lost, however, in some advanced cases: 89% and 81% of TNM (tumour, node, metastases) stages 0-II showed Nm23-H1 and -H2 overexpression, respectively, which significantly differed from 47% and 38% of stage III-IV tumours. Similar results were seen with nm23-H1 mRNA. Heterogenous labelling of tumoral cells was seen by immunohistological staining. This suggests a dichotomy: an overexpression of nm23-H1 and -H2 linked to early stages of cancer and a loss of nm23-H1 overexpression seen in more advanced stages. Therefore specific nm23-H1 determination should be evaluated as a prognostic factor in human colorectal carcinoma.

Apo-dystrophins (Dp140 and Dp71) and dystrophin splicing isoforms in developing brain

PCR studies have shown that exons 71-74 are spliced out in most dystrophin mRNA transcripts in the brain. We have prepared new monoclonal antibodies against the syntrophin-binding region of dystrophin encoded by exons 73-74 and examined three protein products of the dystrophin gene in brain; the widely distributed Dp71, the recently discovered, brain-specific Dp140 and dystrophin itself. Exon 73-74 mAbs bound to all three proteins in brain and the extent of binding suggests that alternatively spliced dystrophins are less prominent at the protein level than predicted by PCR data. Dp140, unlike Dp71, was found to be present at much higher levels in foetal brain than in adult brain. If lack of functional Dp140 is the cause of the cognitive impairment in some Duchenne muscular dystrophy patients, this result suggests that the effects may occur early in development, which would reduce the options for therapeutic intervention.

Tyrosine-iodination converts the delta-opioid peptide antagonist TIPP to an agonist

The binding properties and pharmacological activities of H-Tyr(3'-I)-Tic-Phe-Phe-OH ([Tyr(3'-I)1]TIPP) were studied. Similar to the delta-opioid receptor antagonist H-Tyr-Tic-Phe-Phe-OH (TIPP), [Tyr(3'-I)1]TIPP is a selective and potent ligand at delta-opioid receptors. The displacement curve of [3H]diprenorphine binding by [Tyr(3'-I)1]TIPP was shifted to the right in the presence of Na+ and 5'-guanylylimidodiphosphate, suggesting that it acted as a delta-opioid receptor agonist. [Tyr(3'-I)1]TIPP also behaved as a full agonist in the mouse vas deferens assay and its effect was both naloxone- and TIPP-reversible. These data show that monoiodination at the 3'-position of the N-terminal tyrosine aromatic ring of TIPP converted it from a potent and selective antagonist to a full agonist at delta-opioid receptors.

Characterization of the pancreatic hormones from the Brockmann body of the tilapia: implications for islet xenograft studies

The Brockmann body of the teleost fish, the tilapia (Oreochromis nilotica) has been considered as a potential source of islet xenograft tissue for patients with insulin-dependent diabetes. This study describes the purification from an extract of tilapia Brockmann bodies of insulin and several peptides arising from different pathways of post-translational processing of two proglucagons, two prosomatostatins and proPYY. The primary structure of tilapia insulin is similar to insulins from other teleosts (particularly the anglerfish, Lophius americanus) except that the strongly conserved glutamine residue at position 5 in the A-chain, a residue that is important in the binding of insulin to its receptor, is replaced by glutamic acid. In common with other teleosts, the tilapia Brockmann body expresses two non-allelic glucagon genes. Alternative pathways of post-translational processing lead to glucagons with 29 and 36 amino acid residues derived from proglucagon I and glucagons with 29 and 32 residues derived from proglucagon II. Glucagon-like peptides with 30 and 34 residues derived from proglucagon II were also isolated. In each case, the longer peptide is a C-terminally extended form of the shorter. Tilapia peptide tyrosine-tyrosine (PYY) was isolated in a C-terminally alpha-amidated from with 36 amino acid residues that is structurally similar (89% sequence identity) to anglerfish PYY. A 30-amino acid peptide, representing the C-terminal flanking peptide of PYY, was also isolated that shows only 53% sequence identity with the corresponding anglerfish peptide. Tilapia somatostatin-14 is identical to mammalian somatostatin but the [Tyr7, Gly10] somatostatin-containing peptide derived from prosomatostatin II contains the additional substitution (Phe11-->Leu) compared with the corresponding peptide from other teleosts.

A novel dystrophin isoform is required for normal retinal electrophysiology

Dystrophin is present in the outer plexiform layer of the retina and is required for normal retinal function as measured by electroretinography. We describe the identification of a novel isoform of dystrophin (Dp260) present in the mouse retina. The unique 5' terminus of the mRNA originates from a newly identified exon and is spliced in frame to exon 30 of the Duchenne muscular dystrophy (DMD) gene. The retinal isoform of dystrophin has 13 novel amino acids as its N-terminus followed by most of the dystrophin rod domain and the cysteine-rich C-terminal domains. Analysis of mouse tissues indicated this isoform of dystrophin is expressed in retina, brain and cardiac tissue. Comparison of retinal electrophysiology in mdx and mdxCv3 mouse suggests that Dp260 is required for normal retinal function.

The N-terminal half of dystrophin is protected from proteolysis in situ

Using a panel of "exon-specific" monoclonal antibodies, we have examined the products of degradation of dystrophin by endogenous proteases in post-mortem human muscle. Four main sites of dystrophin digestion were identified, all of them in the C-terminal half of the molecule. Two of them correspond to "hinges" in the central rod region and a third in the C-terminal domain follows the dystroglycan binding site. The results support the Koenig and Kunkel model for the tertiary structure of dystrophin (J. Biol. Chem. 265 (1990) 4560-4566), but suggest that much of the N-terminal half of dystrophin is protected from proteolysis, possibly by interaction with the sub-sarcolemmal cytoskeleton. Although the results seem inconsistent with an anti-parallel dimer model of dystrophin in which hinge 2 and hinge 3 are close together, possible ways of reconciling them with such a model are also considered.

Characterization of revertant muscle fibers in Duchenne muscular dystrophy, using exon-specific monoclonal antibodies against dystrophin

Most Duchenne muscular dystrophy (DMD) patients have genetic deletions or point mutations in the dystrophin gene that alter the reading frame of dystrophin mRNA. This causes early termination of translation, and no dystrophin (or, less commonly, a truncated N-terminal dystrophin fragment) is produced. In many DMD patients, however, a small proportion of muscle fibers show strong dystrophin staining, and these "revertant fibers" are thought to arise by a mechanism that restores the reading frame. Exon-specific monoclonal antibodies (mAbs) have now been used to determine, for the first time, which exons are removed, in order to correct the reading frame in individual muscle fibers. Thus, 15 revertant fibers in a DMD patient with a frameshift deletion of exon 45 were shown to correct the frameshift by the additional deletion of exon 44 (or perhaps exon 46 in some fibers) from the dystrophin mRNA, but not by larger deletions. This result was consistent with reverse transcription (RT)-PCR and sequencing of a minor dystrophin mRNA with an exon 43/46 junction in this biopsy. In a DMD patient with a frameshift deletion of exons 42 and 43, however, larger deletions than the minimum necessary were used to correct the frameshift. In this patient, who produces a half-size N-terminal dystrophin fragment in all fibers, we were able to show that the revertant dystrophin replaces the truncated dystrophin in revertant-fiber sarcolemma. The results are consistent with somatic mutations in revertant-fiber nuclei, which result in removal of additional exons from dystrophin mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Full-length and short forms of utrophin, the dystrophin-related protein

All previous studies of the localization of utrophin (the dystrophin-related protein) in muscle and other tissues have been performed only with antibodies against the C-terminal region of the protein. Since several short forms of dystrophin, the apo-dystrophins, are produced from the 3' end of the dystrophin gene, there is a possibility that similar short forms of utrophin exist and that these could be responsible for some of the many different localizations of 'utrophin' in muscle. We have produced a new panel of 15 mAbs against the N-terminal region of utrophin and we have used it together with mAbs against the C-terminal region to show that full-length utrophin is present at neuromuscular junctions, in nerves, blood vessels and capillaries in normal muscle and in the sarcolemma of patients with muscular dystrophy and dermatomyositis. However, two of the 15 mAbs also recognised rat/mouse utrophin and both of these detected an additional 62 kDa protein on Western blots of rat C6 glioma cells. This potential 62 kDa 'apo-utrophin' was not detected in human cerebral cortex, in rat Schwannoma cells nor in any of the non-nerve cells and tissues tested.

[Synthesis of dihydroxycholecalciferols in maternal and fetal rat organs in the last days of gestation]

The in vitro synthesis of 3H1,25(OH)2D3 and 3H24,25-(OH)2D3 in different maternal (kidney and spleen), placental (maternal and fetal sides) and fetal (kidney, intestine, liver and skeleton) tissues and the relative contribution of each of these organs to total production was studied in the last six days of gestation in rats. On day 16, synthesis of both metabolites was higher in fetal tissues than in maternal kidney, and decreased as gestation advanced. On day 16, placental contribution represented more than 50% of the total production of 3H1,25(OH)2D3, while the maternal kidneys and the fetal tissues contributed only 16% and 26%, respectively. On day 18, the synthesis of 3H1,25(OH)2D3 by maternal placenta and fetal tissues was significantly reduced in comparison with that observed on day 16. Between days 16 and 19, the plasma concentrations of 1,25(OH)2D in mothers and fetuses were associated with the magnitude of its in vitro production. Starting on day 19, however, the in vitro production remained at the same level while the plasma concentration increased, suggesting lower utilization or lower catabolism of this metabolite. Similarly, the total synthesis of 3H24,25(OH)2D3 decreased on day 19. Between days 16 and 18, a higher synthesis of 3H24,25(OH)2D3 corresponded with lower plasma concentration of this metabolite suggesting greater utilization. In contrast, between days 19 and 21, the in vitro synthesis and plasma concentration of 24,25(OH)2D increased in parallel fashion. In summary we report the following findings: a) inhibition of the in vitro synthesis of 3H1,25(OH)2D3 and 3H24,25(OH)2D3 on day 19 of gestation in the rat; b) the contribution of each of the different maternal, placental and fetal tissues to the total synthesis of these metabolites in the last six days of gestation; and c) a parallelism between in vitro production and plasma concentration of both metabolites.

Characterization of insulins and proglucagon-derived peptides from a phylogenetically ancient fish, the paddlefish (Polyodon spathula)

The North American paddlefish, Polyodon spathula (Order Acipenseriformes) is an extant representative of a group of primitive Actinopterygian (ray-finned) fish that probably shared a common ancestor with present-day teleosts. Two molecular forms of insulin which differ by a single amino acid substitution, His or Asp at position 15 of the A chain, were isolated from the pancreas of the paddlefish. Paddlefish insulins show greatest structural similarity to insulin from the garfish (order Lepisosteiformes) and resemble mammalian insulins more strongly than do insulins from teleost fish. The primary structures of several proglucagon-derived peptides, two molecular forms of glucagon which differ by the single amino acid substitution Arg18-->Ser, and glucagon-like peptide, have been less well conserved during evolution. The paddlefish glucagons contain 31 amino acid residues, rather than the usual 29, and show several structural features, such as Met5, Glu24 and Gly29, not previously observed in glucagons from other species. In spite of considerable differences in structure between paddlefish and mammalian glucagons (10 or 11 amino acid substitutions), both paddlefish glucagons are equally as effective as bovine glucagon in stimulating glycogenolysis in dispersed hepatocytes from the teleost fish Sebastes caurinus (rockfish). However, the substitution Arg18-->Ser in the paddlefish glucagon results in a 6-fold decrease in potency in this system.

Expression of the 43 kDa dystrophin-associated glycoprotein in human neuromuscular disease

The expression of the 43 kDa dystrophin-associated glycoprotein (43DAG) has been studied using immunohistochemical labelling with a monoclonal antibody, MANDAG-1, and compared with immunolabelling for dystrophin and the dystrophin-related protein, utrophin, in normal muscle and in muscle from 50 patients with neuromuscular disease. 43DAG and dystrophin were expressed in vascular smooth muscle and at the sarcolemma of normal muscle fibres, with increased labelling at neuromuscular and myotendinous junctions. 43DAG expression was reduced in Duchenne and Becker dystrophies with patchy labelling, more intense around presumptive satellite cells. In Duchenne dystrophy, there was increased 43DAG expression in "revertant" fibres. In Becker dystrophy, 43DAG expression was more extensive around individual fibres, showed more interfibre variation and was more closely related to the intensity of immunolabelling for both dystrophin and utrophin than in Duchenne dystrophy. In other neuromuscular diseases, including congenital muscular dystrophy, no abnormalities of 43DAG expression were identified. The results suggest that in the absence of dystrophin, 43DAG is synthesized but is not stabilized in the sarcolemma. Stability is greater in Becker dystrophy but a normal dystrophin molecule appears to be required for the complete and stable membrane integration of 43DAG. Utrophin may confer some additional stability to the membrane integration of 43DAG but this is incomplete where dystrophin is absent or abnormal.

TIPP[psi]: a highly potent and stable pseudopeptide delta opioid receptor antagonist with extraordinary delta selectivity

Pseudopeptide analogues of the delta opioid antagonists H-Tyr-Tic-Phe-Phe-OH (TIPP) and H-Tyr-Tic-Phe-OH (TIP) containing a reduced peptide bond between the Tic2 and Phe3 residues were synthesized. The two compounds, H-Tyr-Tic psi [CH2NH]Phe-Phe-OH (TIPP [psi]) and H-Tyr-Tic psi-[CH2NH]Phe-OH (TIP [psi]), were tested in mu-, delta-, and kappa-receptor-selective binding assays and in the guinea pig ileum (GPI) and mouse vas deferens (MVD) bioassays. In comparison with their respective parent peptides, both pseudopeptide analogues showed increased delta antagonist potency in the MVD assay, higher delta receptor affinity and further improved delta receptor selectivity. The more potent compound, TIPP [psi], displayed subnanomolar delta receptor affinity and in direct comparisons with other selective delta ligands was shown to have unprecedented delta specificity (Ki mu/Ki delta = 10,500). Furthermore, this compound turned out to be highly stable against enzymatic degradation and, unlike other delta antagonists, showed no mu or kappa antagonist properties. TIPP [psi] is likely to find wide use as a pharmacological tool in opioid research.

Monoclonal antibodies against the muscle-specific N-terminus of dystrophin: characterization of dystrophin in a muscular dystrophy patient with a frameshift deletion of exons 3-7

The first three exons of the human muscle dystrophin gene were expressed as a beta-galactosidase fusion protein. This protein was then used to prepare two monoclonal antibodies (mAbs) which react with native dystrophin on frozen muscle sections and with denatured dystrophin on western blots but which do not cross-react with the dystrophin-related protein, utrophin. Both mAbs recognized dystrophin in muscular dystrophy (MD) patients with deletions of exon 3, and further mapping with 11 overlapping synthetic peptides showed that they both recognize an epitope encoded by the muscle-specific exon 1. Neither mAb recognizes the brain dystrophin isoform, confirming the prediction from mRNA data that this has a different N-terminus. One Becker MD patient with a frameshift deletion of exons 3-7 is shown to produce dystrophin which reacts with the N-terminal mAbs, as well as with mAbs which bind on the C-terminal side of the deletion. The data suggest that transcription begins at the normal muscle dystrophin promoter and that the normal reading frame is restored after the deletion. A number of mechanisms have been proposed for restoration of the reading frame after deletion of exons 3-7, but those which predict dystrophin with an abnormal N-terminus do not appear to be major mechanisms in this patient.