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Symmetric transcription of bacteriophage T4 base plate genes.

Dot-blot and Northern-blot experiments, using strand-specific RNA probes, show that part of the bacteriophage T4 DNA that codes for six of the base plate structural genes (gp 51, 27, 28, 29, 48 and 54), is transcribed in vivo from both DNA strands. The r DNA strand transcripts contain sequences which are translated into structural proteins. Antisense l strand RNA is about 100 fold less abundant than RNA molecules transcribed from the r DNA strand.

Blotting, Northern↗

Quantitative EEG analysis of depth electrode recordings from several brain regions of mutant hamsters with paroxysmal dystonia discloses frequency changes in the basal ganglia.

Computerized EEG spectral analyses of depth electrode recordings from striatum (caudate/putamen; CPu), globus pallidus (GP), and parietal cortex (pCtx) were performed before and after dystonic attacks in freely moving mutant dt(sz) hamsters with paroxysmal dystonia. In these hamsters, sustained attacks of abnormal movements and postures can be reproducibly induced by stress, such as placing the animals in a new environment. Data recorded from mutant hamsters were compared with recordings from age-matched nondystonic control hamsters. The predominant EEG changes in CPu and GP of dystonic hamsters were significant decreases in the high-frequency beta2 range and there was a tendency to increase in delta and theta activities. These changes were seen both before and after onset of dystonic attacks, indicating a permanent disturbance of neural activities in the basal ganglia of dystonic animals. No such changes were seen in the pCtx. Furthermore, no epileptic or epileptiform activity was seen in any of the recordings, substantiating a previous notion from cortical and hippocampal recordings that paroxysmal dystonia in these mutant hamsters has no epileptogenic basis. The present finding of abnormal synchronization of neural activity in the CPu and GP of dystonic hamsters adds to the belief that the striatopallidal-thalamocortical circuit is the most likely site in which to search for the unknown defect in primary (idiopathic) dystonia. As suggested by this study, quantitative EEG analysis can increase the likelihood of detecting subtle EEG abnormalities in different types of idiopathic dystonia and thereby improves our understanding of the pathogenetic mechanisms of this movement disorder.

Animals↗

Platelet signal transduction pathways: could we organize them into a 'hierarchy'?

Platelet activation results in shape change, release of granule contents, aggregation and clot retraction. An intense intracellular 'machinery' is engaged to achieve these functions. Thrombin is one of the most important agonists for platelet recruitment and aggregation which is mediated by the binding of fibrinogen to its adhesive receptor: the glycoprotein (GP) IIb/IIIa complex or integrin alphaIIbbeta(3). The numerous biological processes consecutive to thrombin binding to platelet membrane are mainly controlled by phosphorylation mechanisms organized into signalling pathways. Schematically, the phospholipase Cbeta pathway activated by G protein coupled to the seven transmembrane thrombin receptors, provides the first intracellular relay and would generate regulators such as protein kinase C, phosphorylated pleckstrin but also modifications of the intracellular domain of beta(3). This inside-out signalling would lead to some changes in the extracellular domain of GPIIb/IIIa increasing access of fibrinogen to the receptor. Ligand interaction with GPIIb/IIIa induced reorganization of the cytoskeleton and would mediate the outside-in signals which involve a series of intracellular events including tyrosine kinases, phosphatidylinositol 3 kinases, MAP kinases and phosphatases. Some of these pathways and/or signalling metabolites could be associated to some well-characterized platelet functions: cortactin phosphorylation is involved in platelet shape change, phosphatidylinositol 3 kinase (p85) in the stabilisation of platelet aggregates and MAP kinase (p44) in postaggregation events. But in fact the sequence of events which has been described has to be viewed as integrated networks. At least three biochemical processes govern the highly integrated organization to send just the appropriate quanta of signal for a specific need: the reorganisation of the cytoskeleton following the binding of fibrinogen to alphaIIbbeta(3), the structure of the signal transducers that contain SH2, SH3, and PH domains leading to the formation of macromolecules of signalling and the crosstalk phenomena between the different pathways. Elucidating the mechanisms of such networks becomes an increasingly exciting project.

Animals↗

Comparison of the structural characteristics of cell-CAM 105 from hepatocytes with those of an altered form expressed by rat transplantable hepatocellular carcinomas.

The structural features of the adult rat hepatocyte (ARH) forms of cell-CAM 105, a Mr 105,000 cell adhesion molecule, were compared using a variety of immunochemical and biochemical techniques with altered forms of more basic pI present on two transplantable hepatocellular carcinomas (THC 1682c and THC AS-30D). Immunoprecipitation analysis with polyclonal (anti-gp 105-2) and monoclonal (MAb) antibodies specific for cell-CAM 105 (MAb 362.50) demonstrated that ARH and THC cell-CAM 105 were indistinguishable in several respects including: (a) binding to wheat germ agglutinin; (b) labeling with NaIO4/NaB3H4; (c) susceptibility to digestion with endoglycosidases (endoglycosidase H and F and peptide N-glycosidase F N-glycanase); (d) rate of turnover on the cell surface; and (e) differential resistance of upper and lower forms to trypsin digestion in the presence or absence of calcium. Digestion with Clostridium perfringens or Vibrio cholerae neuraminidase did not equalize pI but instead decreased the size and increased the pI of both ARH and THC cell-CAM 105. Comparison of two-dimensional tryptic peptide maps, however, revealed five unique peptides in the THC AS-30D map and one peptide in the THC 1682c map, peptides which were only apparent in maps of deglycosylated ARH cell-CAM 105. Based on these results, it was concluded that there were significant differences in the glycosylation of ARH and THC cell-CAM 105. Biosynthetic labeling with 32PO4 and 35SO4 showed that both ARH and THC molecules were phosphorylated but not sulfated. Comparison of 32P-labeled peptides produced by digestion with V-8 protease revealed significant differences in the phosphorylation of the upper and lower forms from ARH and showed that the pattern of phosphorylation on THC cell-CAM 105 most closely resembled ARH upper form. Pulse-chase analysis of ARH cell-CAM 105 further indicated that only a subpopulation of the molecules labeled with [35S]methionine were phosphorylated.

Alkaline Phosphatase↗

Expression and functional analysis of a hyperglycosylated glucoamylase in a parental host, Aspergillus awamori var. kawachi.

A modified glucoamylase gene (glaA) with an extra Thr- and Ser-rich Gp-I domain (T. Semimaru, M. Goto, K. Furukawa, and S. Hayashida, Appl. Environ. Microbiol. 61:2885-2890, 1995) was introduced into a mutant parental host, Aspergillus awamori var. kawachi, in which the original glaA gene had been completely deleted and replaced with the hygromycin phosphotransferase gene. The modified glaA was successfully expressed and secreted. The modified glucoamylase possessed higher digestibility of raw corn starch and higher stabilities in response to heat and extreme pH.

Aspergillus↗

Motor subcircuits mediating the control of movement velocity: a PET study.

The influence of changes in the mean velocity of movement on regional cerebral blood flow (rCBF) was studied using positron emission tomography (PET) in nine healthy right-handed adults while they performed a smooth pursuit visuomanual tracking task. Images of relative rCBF were obtained while subjects moved a hand-held joystick to track the movement of a target at three different rates of a sinusoidal displacement (0.1, 0.4, and 0.7 Hz). Significant changes in rCBF between task conditions were detected using analysis of variance and weighted linear contrasts. The kinematics of arm and eye movements indicated that subjects performed tasks in a similar manner, particularly during the faster two tracking conditions. Significant increases in rCBF during arm movement (relative to an eye tracking only control condition) were detected in a widespread network of areas known for their involvement in motor control. The activated areas included primary sensorimotor (M1S1), dorsal and mesial premotor, and dorsal parietal cortices in the left hemisphere and to a lesser extent the sensorimotor and superior parietal cortices in the right hemisphere. Subcortically, activations were found in the left putamen, globus pallidus (GP), and thalamus, in the right basal ganglia, and in the right anterior cerebellum. Within the cerebral volume activated with movement, three areas had changes in rCBF that correlated positively with the rate of movement: left M1S1, left GP, and right anterior cerebellum. No movement-related sites had rCBF that correlated negatively with the rate of movement. Regressions of mean percent change (MPC) in rCBF onto mean hand velocity yielded two nonoverlapping subpopulations of movement-related loci, the three sites with significant rate effects and regression slopes steeper than 0.17 MPC.cm-1.s-1 and all other sites with nonsignificant rate effects and regression slopes below 0.1 MPC.cm-1. s-1. Moreover, the effects of movement per se and of movement velocity varied in magnitude independently. These results confirm previous reports that movement-related activations of M1S1 and cerebellum are sensitive to movement frequency or some covarying parameter of movement. The activation of GP with increasing movement velocity, not described in previous functional-imaging studies, supports the hypothesis that the basal ganglia motor circuit may be involved preferentially in controlling or monitoring the scale and/or dynamics of arm movements. The remaining areas that were activated equally for all movement rates may be involved in controlling higher level aspects of motor control that are independent of movement dynamics.

Aged↗

GP-2/THP gene family encodes self-binding glycosylphosphatidylinositol-anchored proteins in apical secretory compartments of pancreas and kidney.

A family of homologous genes is shown to encode GP-2, the major glycosylphosphatidylinositol (GPI)-linked glycoprotein of pancreatic zymogen granule membranes, and Tamm-Horsfall protein (THP), a GPI-linked glycoprotein associated with apical vesicles in kidney thick ascending limb of Henle (TALH) cells. The C-terminal regions of GP-2 (Asp54-Phe530) and THP (Asp175-His644) from rat show 53% identity, 86% similarity, and 26 conserved cysteine residues including one epidermal growth factor motif. The unique N-terminal domain of rat THP (unique-THP, Pro29-Gln174) shows four conserved epidermal growth factor motifs, three in tandem and one in reverse orientation. GP-2 homologues are observed in a wide variety of epithelial cells, several of which contain highly regulated secretory processes. GP-2 released from zymogen granule membranes with phosphatidylinositol phospholipase C reacts with anti-cross-reactive determinant antibody (anti-CRD), confirming the GPI nature of the pancreatic homologue. In contrast, GP-2 and THP, released endogenously from pancreas and kidney, respectively, do not react with anti-cross-reactive determinant antibody, suggesting alternative enzymatic mechanisms for their physiological release. Globular domains of GP-2 and THP, but not albumin, show pH- and ion-dependent self-association in vitro. The GP-2/THP family appears to represent a newly discovered class of GPI-anchored proteins, which may utilize pH- and ion-dependent self-association mechanisms for establishing membrane (micro)domains targeted to intracellular secretory compartments.

Amino Acid Sequence↗

Parkinsonian rigidity, dopa-induced dyskinesia and chorea--dynamic studies on the basal ganglia-thalamocortical motor circuit using PET scan and depth microrecording.

Regional cerebral glucose metabolism (rCMRGlu-18FDG) was measured in 6 cases with rigid type Parkinson's disease (PD) (2 cases with dopa-induced dyskinesia = DID), 6 cases with chorea (Ch), 5 cases with essential tremor (EssT) and 2 cases with normal subjects (N). The effects of L-Dopa on rCMRGlu was studied in 3 cases with PD. With the aid of depth microrecording study, stereotactic pallidotomy was performed in all cases with PD. Thalamotomy was performed in 3 cases with Ch. In the EssT and N group, the metabolic pattern was high in the frontal cortex (FCx) but low in the lenticular nucleus (LN). In contrast, all cases with a rigid type PD showed lower rCMRGlu in FCx (premotor, prefrontal area). However, 4 out of 6 cases were higher in LN than the control group. Administration of L-Dopa shifted rCMRGlu toward the normal pattern in this group. Five out of 6 cases with Ch represented higher rCMRGlu in FCx (3 focal, 2 diffuse) but lower in LN. Moreover, when DID occurred, it showed almost the same pattern as in Ch. Electrophysiological studies showed high background neuronal activity (BNA) in the medial segment of the globus pallidus (GP) but low BNA in the lateral segment of the GP in the rigid type of PD. In cases with Ch, irregular burst discharges were often encountered in ventro-oral thalamus. From these results, the on-going changes of basal ganglia-thalamocortical motor circuit in cases with a rigid type PD, DID and Ch are discussed. The underlying mechanisms of Parkinsonian rigidity was considered to contrast with those of DID and Ch within the same motor circuit.

Antiparkinson Agents↗

Opioid-induced feeding: localization of sensitive brain sites.

These experiments were designed to identify brain sites at which opioids might act to influence ingestive behavior and to determine which opioid receptor types are involved. After food deprivation, rats were given microinjections of naloxone into several brain regions and food intake was measured. Injections into or near the paraventricular (PVN) or ventromedial (VMH) hypothalamic nuclei or the globus pallidus (GP) reduced food intake; injections into the striatum or lateral hypothalamus (LH) were ineffective. A second study examined the ingestive effects of roughly equimolar doses (1.43-1.75 nmol) of dynorphin A (DYN), beta-endorphin (beta-END), and D-Ala2,D-Leu5-enkephalin (DADLE) when injected into 4 different brain regions. Only DYN significantly increased food intake, and this effect was seen only with injections into the PVN and VMH. Beta-END stimulated water intake when injected into the PVN, VMH and GP but not the LH. Further studies indicated that with PVN injections, DYN was effective at a dose as low as 0.47 nmol, and that a higher dose of DADLE (4.39 nmol) did stimulate food intake. These studies support an important role for dynorphin and the kappa opioid receptor in the regulation of feeding and suggest that the opioid regulation of food and water intake can be differentiated both by sites of action and by effective agonists.

Animals↗

Recent changes in the prevalence of diseases presenting for health care.

BACKGROUND: Practice-based morbidity surveys inform on the prevalence of diseases presenting for health care. The last major survey in England and Wales was conducted in 1991. AIM: To reveal changes in disease prevalence between 1991 and 2001. DESIGN OF STUDY: Population-based analysis of persons presenting to GPs. Annual prevalence of diseases reported in the Weekly Returns Service (WRS) of the Royal College of General Practitioners in 2001 was compared with prevalence reported in Morbidity Statistics from General Practice, Fourth National Study (MSGP4). SETTING: Thirty-eight general practices contributing to the WRS, monitoring a population of 326,000 in 2001. METHOD: Prevalence was determined from Read codes for morbidity entered in the respective survey years. Diseases and disease groups were defined from Read codes mapping to the chapters, major sub-groups and 3-digit codes of the International Classification of Disease version 9 (ICD9). Age-standardised prevalence rates per 10,000 registered persons and 99% confidence intervals (CIs) were calculated using the national census population for 2001 as the standard. Survey differences in prevalence were identified from non-overlapping CIs. RESULTS: There was a general reduction in the prevalence of disease caused by infection and an increase of degenerative disorders. The prevalence of mental disorders, skin disease and musculoskeletal disorders showed little change. Particular increases were noted for other malignant and benign neoplasms of the skin, hypothyroidism and diabetes. There were marked reductions for disorders of the conjunctiva, ear infections, acute myocardial infarction and heart failure, respiratory infections and injuries. CONCLUSIONS: The role of the GP continues to change. These results confirm the importance of the management of chronic diseases as the dominant (though not the sole) role of the GP. The results demonstrate the use of the WRS as a source of data on disease prevalence.

Adolescent↗

Safe use of platelet GP IIb/IIIa inhibitors.

The platelet membrane glycoprotein IIb/IIIa receptor inhibitor abciximab is used for the treatment of patients undergoing high-risk percutaneous coronary interventions and is used in approximately one third of coronary interventions in the United States and a growing number of procedures in Europe. Recent clinical trials have shown that this potent antiplatelet agent significantly reduces the incidence of death and nonfatal myocardial infarction and the need for revascularization. With expanding experience since the commercial release of abciximab in February 1995, several strategies to enhance the safety of abciximab have emerged. In particular, new data confirm that the risk of bleeding--identified as a concern in the original EPIC trial--can be substantially reduced through the use of low-dose adjunctive heparin, early sheath removal, and fastidious postprocedure vascular access site care. Other recommendations for enhancing the safety of potent antiplatelet agents in a variety of clinical situations are provided. The following article reflects insights regarding the safety of glycoprotein IIb/IIIa inhibitors expressed by a group of international experts convened in Davos, Switzerland, February 16, 1997. This report attempts to review clinical progress to date, formulate recommendations, and map out potentially fruitful lines of inquiry for future investigation.

Abciximab↗

Radiosynthesis and evaluation of 11C-labeled diaryl-substituted imidazole and indole derivatives for mapping cyclooxygenase-2.

11C-labeled analogs of 4-chloro-5-(3-fluoro-4-methoxyphenyl)-1-(4-methylsulfonylphenyl)imidazole ([11C]1), 4-[4-chloro-5-(3-fluoro-4-methoxyphenyl)imidazol-1-yl]benzenesulfonamide ([11C]2) and 2-(4-aminosulfonylphenyl)-3-(4-methoxyphenyl)indole ([11C]3), which have been shown to have excellent potency and high selectivity for cyclooxygenase isoform 2 (COX-2) inhibiting activity, were prepared and evaluated in rats as potential radiopharmaceuticals for imaging the COX-2 enzyme by positron emission tomography. These 11C-labeled COX-2 inhibitors were synthesized in high radiochemical yields by O-[11C]methylation of phenolic precursors with [11C]methyl triflate in acetone containing NaOH as a base. In vivo evaluation in rats bearing AH109A hepatoma showed no specific binding of any tracer to COX-2 in any tissue such as the brain, heart, lung, kidney, and AH109A hepatoma. In ex vivo autoradiography, [11C]1 showed regionally different distribution in the brain, while [11C]2 and [11C]3 were not substantially taken up by the brain. In in vitro monolayer efflux assays, compound 3 was found to be a substrate for the P-glycoprotein (P-gp) efflux pump, but pretreatment of rats with the potent P-gp inhibitor, cyclosporine A, did not have any significant influence on the cerebral uptake of [11C]3. These results indicate that all three tracers were not suitable for in vivo imaging of COX-2. There seem to be some obstacles to finding a useful candidate for in vivo imaging application of COX-2 selective inhibitors only by standard consideration of in vitro affinity and selectivity, and the lipophilicity of the compound.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Safe use of platelet GP IIb/IIIa inhibitors.

The platelet membrane glycoprotein IIb/IIIa receptor inhibitor abciximab is used for the treatment of patients undergoing high-risk percutaneous coronary interventions and is used in approximately one third of coronary interventions in the United States and a growing number of procedures in Europe. Recent clinical trials have shown that this potent antiplatelet agent significantly reduces the incidence of death and nonfatal myocardial infarction and the need for revascularization. With expanding experience since the commercial release of abciximab in February 1995, several strategies to enhance the safety of abciximab have emerged. In particular, new data confirm that the risk of bleeding-identified as a concern in the original EPIC trial-can be substantially reduced through the use of low-dose adjunctive heparin, early sheath removal, and fastidious postprocedure vascular access site care. Other recommendations for enhancing the safety of potent antiplatelet agents in a variety of clinical situations are provided. The following article reflects insights regarding the safety of glycoprotein IIb/IIIa inhibitors expressed by a group of international experts convened in Davos, Switzerland, February 16, 1997 This report attempts to review clinical progress to date, formulate recommendations, and map out potentially fruitful lines of inquiry for future investigation.

Abciximab↗

The autoreactive T cell population in experimental allergic encephalomyelitis: T cell receptor beta-chain rearrangements.

T cell receptor beta-chain gene rearrangements were examined in myelin basic protein (MBP)-reactive T cell lines and hybridomas from Lewis (Lew) rats. Nearly 75% of the cloned hybrids were specific for the major encephalitogenic determinant residues 68-88 of guinea pig (GP) MBP; three fine specificities could be distinguished. Southern blot analysis of receptor beta-chain genes revealed polyclonality and shared rearrangements not seen in non-68-88-specific clones. Generation of short-term, encephalitogenic Lew T cell lines revealed rearrangements shared with the 68-88-specific hybrids, indicating that the hybrids were representative of the whole antigen-specific population and suggesting restricted V beta gene usage within this polyclonal population.

Animals↗

Human Zn-alpha 2-glycoprotein: complete genomic sequence, identification of a related pseudogene and relationship to class I major histocompatibility complex genes.

The human gene (AZGP1) encoding Zn-alpha 2-glycoprotein (Zn-alpha 2-gp), a protein present in several biological fluids and produced by a subtype of breast carcinomas, has been cloned and its complete nucleotide sequence determined. The gene spans over 9.7 kb, and its overall organization and nucleotide sequence are very similar to those of the first four exons of class I MHC genes. However, the Zn-alpha 2-gp gene differs from these genes in several significant ways. It lacks the coding information for the transmembrane and cytoplasmic domains typical of MHC genes, which is consistent with its presence as a soluble protein in different physiological and pathological fluids. In addition, it contains a high density of repetitive sequences, including Alu, MER, and MIR elements, which are not present at equivalent positions in class I MHC genes. Finally, its 5'-flanking region lacks the class I MHC regulatory complex and the interferon consensus sequence characteristic of class I MHC genes. These findings may explain the different expression pattern of Zn-alpha 2-gp and class I MHC genes in human tissues. Southern blot hybridization of DNA from several species with a cDNA probe indicated that Zn-alpha 2-gp genes are present in a wide variety of animal species, including monkey, rat, mouse, dog, cow, and rabbit. The human genome also contains a putative Zn-alpha 2-gp pseudogene that has been isolated and partially characterized. This pseudogene has an intron-exon organization identical to that of the functional gene, but it presents two deleterious mutations in the third exon that lead to the appearance of premature stop codons. Finally, considering the lack of polymorphism in the Zn-alpha 2-gp gene in comparison with MHC genes, putative roles for this human glycoprotein in the transport of nonpolymorphic substances or in intercellular recognition processes are proposed.

Amino Acid Sequence↗

Specific inhibition of HIV-1 coreceptor activity by synthetic peptides corresponding to the predicted extracellular loops of CCR5.

We used synthetic peptides to the extracellular loops (ECLs) of CCR5 to examine inhibitory effects on HIV infection/fusion with primary leukocytes and cells expressing recombinant CCR5. We show for the first time that peptides derived from the first, second, or third ECL caused dose-dependent inhibition of fusion and infection, although with varying potencies and specificities for envelope glycoproteins (Envs) from different strains. The first and third ECL peptides inhibited Envs from the R5 Ba-L strain and the R5X4 89.6 strain, whereas the second ECL peptide inhibited Ba-L but not 89.6 Env. None of the peptides affected fusion mediated by Env from the X4 LAV strain. Fusion mediated by Envs from several primary HIV-1 isolates was also inhibited by the peptides. These findings suggest that various HIV-1 strains use CCR5 domains in different ways. Experiments involving peptide pretreatment and washing, modulation of the expression levels of Env and CCR5, analysis of CCR5 peptide effects against different coreceptors, and inhibition of radiolabeled glycoprotein (gp) 120 binding to CCR5 suggested that the peptide-blocking activities reflect their interactions with gp120. The CCR5-derived ECL peptides thus provide a useful approach to analyze structure-function relationships involved in HIV-1 Env-coreceptor interactions and may have implications for the design of drugs that inhibit HIV infection.

Amino Acid Sequence↗

Synthetic peptide strategy for the detection of and discrimination among highly divergent primate lentiviruses.

We developed a simple, rapid, inexpensive, and highly sensitive and specific strategy for the detection and lineage differentiation of primate lentiviruses (PIV-ELISA). It is based on the use of two indirect ELISA methods using synthetic peptides mapping the gp41/36 region (detection component) and the V3 region (differentiation component) of four lentivirus lineages, namely SIVcpz/HIV-1 (groups M, O, N, and SIVcpz-gab), SIVmnd, SIVagm, and SIVsm/SIVmac/HIV-2. This strategy was evaluated with panels of sera originating from both humans and nonhuman primates. The human reference panel consisted of 144 HIV Western blot (WB)-positive sera in which the corresponding virus had been genotyped (HIV-1: 72 group M, 28 group O, and 6 group N; HIV-2: 21 subtype A and 10 subtype B; and 7 HIV-1+2) and 105 HIV WB-negative samples. The nonhuman primate reference panel consisted of 24 sera from monkeys infected by viruses belonging to the four lineages included in the PIV-ELISA strategy (5 chimpanzees, 5 macaques, 8 mandrills, and 6 vervets) and 42 samples from seronegative animals. Additional field evaluation panels consisted of 815 human sera from Gabon, Cameroon, and France and 537 samples from 25 nonhuman primate species. All the samples from the two reference panels were correctly detected and discriminated by PIV-ELISA. In the human field evaluation panel, the gp41/36 component correctly identified all the test samples, with 98% specificity. The V3 component discriminated 206 HIV-1 group M, 98 group O, 12 group M+O, and 128 HIV-2 sera. In the primate field evaluation panel, both gp41/36 and V3 detected and discriminated all the WB-positive samples originating from monkeys infected with SIVcpz, SIVagm-ver, SIVmnd-1, SIVmnd-2, SIVdrl, or SIVsun. These results were confirmed by genotyping in every case. Four SIV-infected red-capped mangabeys (confirmed by PCR) were correctly identified by gp41/36, but only two reacted with the V3 peptides in the absence of a specific SIVrcm V3 peptide. Addition of a V3 SIVrcm peptide discriminated all the SIVrcm-positive samples. Fourteen Papio papio samples were positive for SIVsm gp 36 and by WB, but negative by PCR, whereas three Papio cynocephalus samples were positive by gp41/36 but indeterminate by WB and negative by PCR. This combined ELISA system is thus highly sensitive and specific for antibodies directed against HIV and SIV. In addition, the V3-based serotyping results always agreed with genotyping results. This method should prove useful for studies of lentivirus prevalence and diversity in human and nonhuman primates, and may also have the potential to detect previously undescribed SIVs.

Amino Acid Sequence↗

Anomalies in the translocation and processing of glycophorin precursors in murine erythroleukemia cells.

Analogues of human glycophorins have been identified in many species, including mouse. In murine erythroleukemia cells three mature glycophorins (gp-2, gp-3, 34K) and four putative precursors (21K, 23K, 26K, and 27K) are expressed. Pulse-chase labeling experiments suggest that 21K and 23K are the precursors of the gp-3 doublet of proteins 29K and 30K. Precursor-product relationships were not found for 26K, 27K, 34K, and gp-2. Two experimental approaches, i.e. cell-free translation and subcellular distribution, have identified processing anomalies in the glycophorins. First, signal sequences, if present, are apparently not cleaved upon translocation across the endoplasmic reticulum membrane; second, the 26K and 27K putative precursors are inefficiently translocated. The majority accumulates in the cytosol or associates with the endoplasmic reticulum membrane without acquiring protection against V8 protease. Only a minority (approximately 10%) is properly translocated.

Animals↗