Efficient purification and rigorous characterisation of a recombinant gp120 for HIV vaccine studies

A recombinant HIV-1 gp120 (rgp120) was expressed in a permanent Chinese Hamster Ovary (CHO) cell line (L761h) that constitutively secretes the product of clone p4 derived from the env gene of HIV-1 isolate GB8. The rgp120 was isolated from cell culture supernatants by a simple, rapid, non-denaturing and efficient purification procedure based on a novel combination of lectin affinity and FPLC ion-exchange chromatography. The purity of the isolated glycoprotein was rigorously confirmed by SDS-PAGE, capillary electrophoresis, laser desorption mass spectrometry, total amino acid analysis and N-terminal amino acid sequencing. The retention of biological activity by the purified rgp120 was assessed by determining the dissociation constant of rgp120 binding to sCD4. After formulation of this highly purified and biologically active rgp120 with "conventional" adjuvants, including types already used in clinical trials of candidate gp120-based HIV vaccines, antibody responses in immunised rabbits were analysed using panels of overlapping synthetic peptides. The consequences of using currently available adjuvants to deliver highly specialised and perhaps conformation-dependent molecules, like HIV gp120, are presented and discussed in the context of HIV vaccine development.

Structure of a 14-3-3 protein and implications for coordination of multiple signalling pathways

A broad range of organisms and tissues contain 14-3-3 proteins, which have been associated with many diverse functions including critical roles in signal transduction pathways, exocytosis and cell cycle regulation. We report here the crystal structure of the human T-cell 14-3-3 isoform (tau) dimer at 2.6 A resolution. Each monomer (Mr 28K) is composed of an unusual arrangement of nine antiparallel alpha-helices organized as two structural domains. The dimer creates a large, negatively charged channel approximately 35 A broad, 35 A wide and 20 A deep. Overall, invariant residues line the interior of this channel whereas the more variable residues are distributed on the outer surface. At the base of this channel is a 16-residue segment of 14-3-3 which has been implicated in the binding of 14-3-3 to protein kinase C.

Isoforms of 14-3-3 protein can form homo- and heterodimers in vivo and in vitro: implications for function as adapter proteins

14-3-3 proteins play a role in many cellular functions: they bind to and regulate several proteins which are critical for cell proliferation and differentiation. 14-3-3 proteins exist as dimers, and in this study we have shown that diverse 14-3-3 proteins can form both homo- and heterodimers in vitro (by cross-linking studies) and in vivo (by coimmunoprecipitation and Western blot analysis); this interaction is mediated solely through the N-terminal domain of the proteins. The composition of 14-3-3 dimers within a cell may play a key part in the role of this family of proteins as modulators or adapters which facilitate the interaction of distinct components of signalling pathways.

The epidemiology of nonfatal injuries among US children and youth

OBJECTIVES

National data are not routinely available regarding the incidence of and associated risk factors for nonfatal injuries in children and youth. The Child Health Supplement to the 1988 National Health Interview Survey provided an opportunity to determine accurate national estimates of childhood injury morbidity by demographic factors, location, external cause, nature of injury, and other factors.

METHODS

The closest adult for 17,110 sampled children was asked whether the child had had an injury, accident, or poisoning during the preceding 12 months and about the cause, location, and consequences of the event. An analysis for potential underreporting from 12 months of recall provided adjustments of annual rates to those for a 1-month recall period.

RESULTS

On the basis of 2772 reported injuries, the national estimated annual rate for children 0 to 17 years of age was 27 per 100 children after adjustment to 1-month recall. Boys experienced significantly higher rates than girls (risk ratio [RR] = 1.52, 95% confidence interval [CI] = 1.37, 1.68), and adolescents experienced the highest overall rate (38 per 100 children) and proportion of serious injuries.

CONCLUSIONS

Approximately one fourth of US children experience a medically attended injury each year, but the risks vary considerably depending on the characteristics of subgroups and the injury cause.

A molecular and serologic study of the envelope gene of the British isolate: HIV-1 GB8

The entire envelope gene of a British HIV-1 isolate, GB8, was cloned, sequenced and aligned with those of the reference strains MN, SF2 and IIIB/LAI. Three of the viruses (MN, IIIB/LAI, GB8) and their recombinant gp120s, were then characterised using an extensive panel of human HIV-1 positive sera and mapped neutralising monoclonal antibodies (MAbs). Overall, the GB8 env-gene translation product shares 84% homology with those of the reference strains. Across the V3 region homology was greater between GB8 and SF2/MN (74.3-88.6%) than IIIB/LAI (63.9-66.7%). Accordingly, GB8 was sensitive to V3-specific MAbs which neutralise MN/SF2 and resistant to those that neutralize IIIB/LAI. In the CD4 binding region the central MWQEVGKAMYAPPI was conserved in all viruses but homology in the N-terminus was greater between GB8 and SF2 and IIIB/LAI than MN. GB8 and IIIB/LAI were sensitive to all MAbs raised against the CD4 binding site whereas MN was resistant to 3 of 4 tested. Human sera obtained from a London-based cohort did not differentiate between GB8 and MN in neutralisation assays, whereas IIIB/LAI titres were significantly lower at all stages of disease. These results show that GB8 carries a consensus-like V3 loop and is as representative as MN of HIV-1 viruses circulating in the UK. To our knowledge, GB8 is the only British HIV-1 isolate which has been characterised to date.

Treatment of extramammary Paget's disease by radiotherapy

Extramammary Paget's disease (EMPD) is a rare cutaneous malignancy, which usually occurs in the elderly. Wide local excision is the recommended treatment, although this may not always be feasible. We report our experience of EMPD treated by radiotherapy in five patients. The radiotherapy was well tolerated in each case, and there were no signs of recurrence during follow-up (6 months-8 years). This study shows that radiotherapy is a useful alternative therapy for EMPD, and should be considered particularly in elderly patients who may not tolerate surgery.

Protection of mice from Bordetella pertussis respiratory infection using microencapsulated pertussis fimbriae

Conditions have been established which allow the efficient entrapment of Bordetella pertussis fimbriae in poly(lactide-co-glycolide) microspheres. Fimbriae released from the matrix were found to have retained some degree of conformational structure, as determined by assessing the capacity of fimbrial protein to bind to antibodies mapping to either conformational or denatured structures on the fimbriae, either encapsulated in microspheres with a mean diameter of 24 microns and an estimated in vitro protein release rate of approximately 42 days, or conventionally adjuvanted with alhydrogel, elicited vigorous immune responses in mice. The encapsulated fimbriae appear to elicit marginally lower serum antibody levels than those induced by equivalent amounts of alhydrogel-adjuvanted fimbriae. Mice immunised with both preparations were, however, protected against intranasal infection with live B. pertussis as evidenced by the significant reduction in levels of bacterial colonisation observed in the lungs and tracheas of immunised animals when compared to the immunologically naive controls.

Expression and structural analysis of 14-3-3 proteins

The 14-3-3 family of proteins plays a role in a wide variety of cellular functions including regulation of protein kinase C and exocytosis. Using antisera specific for the N termini of 14-3-3 isoforms described previously and an additional antiserum specific for the C terminus of epsilon isoform, protease digestion of intact 14-3-3 showed that the N-terminal half of 14-3-3 (a 16 kDa fragment) was an intact, dimeric domain of the protein. Two isoforms of 14-3-3, tau and epsilon, were expressed in E. coli and their secondary structure was shown by circular dichroism to be identical to wild-type protein, and expression of N-terminally-deleted epsilon 14-3-3 protein showed that the N-terminal 26 amino acids are important for dimerization. Intact 14-3-3 is a potent inhibitor of protein kinase C, but the N-terminal domain does not inhibit PKC activity. Site-specific mutagenesis of several regions in the tau isoform of 14-3-3, including the mutation of a putative pseudosubstrate site to a potential substrate sequence, did not alter its inhibitory activity. Intact 14-3-3 proteins are phosphorylated by protein kinase C with a low stoichiometry, but truncated isoforms are phosphorylated much more efficiently by this kinase. This may imply that the proteins may adopt a different structural conformation, possibly upon binding to the membrane, which could modulate their activity. 14-3-3 proteins are found at high concentration on synaptic plasma membranes and this binding is mediated through the N-terminal 12 kDa of 14-3-3.

Oligosaccharide behavior of complex natural glycosphingolipids in multicomponent model membranes

Wideline 2H NMR of model membranes was used to consider the molecular consequences of factors often suggested as modulators of complex glycosphingolipid oligosaccharide arrangement and motional characteristics at cell surfaces. GM1, asialo-GM1, and globoside were studied as examples of plasma membrane recognition sites. The experimental approach involved substitution of deuterons (D) for protons at specific locations within the carbohydrate chains. Deuterated glycolipids were then dispersed at 7-10 mol% in unsonicated bilayers of 1-palmitoyl-2-oleoylphosphatidylcholine. Factors tested for their significance to carbohydrate chain conformation and dynamics included glycolipid natural alkyl and acyl chain variability, membrane fluidity, and the presence of cholesterol and a charged sugar residue (neuraminic acid). Effects of Ca2+ and membrane-associated protein were briefly considered. Two distinct strategies were employed in substituting deuterons for selected protons of carbohydrate residues. Neither approach necessitated alteration of the glycolipid natural fatty acid composition. (i) Protons of the exocyclic hydroxymethyl group on the terminal Gal residue of GM1 and asialo-GM1, and on the terminal N-acetylgalactosamine (GalNAc) residue of globoside, were replaced with deuterium (producing -CDHOH) by an enzymatic oxidation/reduction cycle. This represents the first application of such an approach to deuteration of complex neutral glycolipids. Spectral results were compared to those obtained for the similarly-deuterated monoglycosyl lipid, galactosylceramide (GalCer), with natural fatty acid composition. Efficacy of this labeling method may in principle be influenced by structural variations within a given glycolipid family. Also, asymmetric rotation of the deuterated group made it less attractive than the second method for relating spectral features to receptor geometry. (ii) A general synthetic, nonenzymatic method was investigated for replacing amino sugar N-acetyl groups with deuterated acetate (-COCD3). The acetate group of the GalNAc residue of globoside, GM1, and asialo-GM1, as well as that on neuraminic acid in GM1, was replaced with -COCD3. This second method afforded better signal-to-noise--an important consideration for 2H NMR. The NMR technique employed had the potential for detecting changes of as little as 10% in oligosaccharide orientation or motional order. Each glycolipid demonstrated clear evidence of preferred average oligosaccharide conformations in all (fluid) membrane environments examined. The most striking observation was that, in fluid matrices, conformation and motional order of the complex oligosaccharide chains were only modestly influenced by factors tested, including natural variation in the glycolipid hydrocarbon chains, membrane fluidity, temperature, and the presence of cholesterol or the N-acetylneuraminic acid (NeuAc) residue on GM1.(ABSTRACT TRUNCATED AT 400 WORDS)

Molecular analysis of the operon which encodes the RNA polymerase sigma factor sigma 54 of Escherichia coli

The rpoN gene (encoding the sigma factor sigma 54) of Escherichia coli was cloned and its nucleotide sequence determined. Promoter probe analysis confirmed the presence of a promoter in a 350 bp fragment covering the start of rpoN. The likely promoter was identified. The nucleotide sequence of the region extending 2.1 kb downstream of rpoN was also determined. This region contained four open reading frames encoding potential polypeptides of 10750, 17959, 32492 and 9810 Da; maxicell and T7 promoter studies showed that four polypeptides of similar molecular masses were expressed from this region. The amino acid sequence of the 17959 Da polypeptide showed homology to the enzyme IIA domains of several proteins of the bacterial sugar phosphotransferase system (PTS), and the 9810 Da polypeptide showed homology to the HPr proteins of the bacterial PTS. The proteins encoded downstream of rpoN are known to negatively regulate sigma 54 activity. The homologies therefore suggest that this effect on sigma 54 may be mediated by sequential protein phosphorylation and suggest that there is a link between signal transduction and transcription of sigma 54-dependent genes.

Production of a vector to facilitate DNA mutagenesis and recombination

Most methods for the generation of site-specific mutants and recombinant constructs require primer extension in vitro. These methods include the Kunkel method and PCR-based methods. Such methods to manipulate DNA are prone to sequence error because they take place outside the complex in vivo mechanisms that increase sequence fidelity during plasmid replication in Escherichia coli. Sequence errors are of particular concern when using PCR-based methods. We have constructed two new plasmids that facilitate the generation of site-specific mutants and recombinant constructs. The plasmids we have constructed are designed to maximize the number of unique restriction enzyme recognition sites in inserts that have been cloned into either plasmid. This was accomplished by eliminating extraneous sequence and many restriction enzyme recognition sites. New recombinant circle and recombination PCR protocols for multiplex site-specific plasmid mutagenesis were used to make these plasmids. These plasmids permit small portions of an insert sequence to be readily removed by restriction enzyme digestion. A small DNA segment, containing the targeted sequence alteration, can subsequently be ligated into a plasmid construct that has not been subjected to primer extension in vitro, diminishing the probability of encountering a sequence error and reducing the amount of DNA sequencing necessary to assess for errors.

The effects of recall on estimating annual nonfatal injury rates for children and adolescents

OBJECTIVES

This study used a recent national population survey on childhood and adolescent non-fatal injuries to investigate the effects of recall bias on estimating annual injury rates. Strategies to adjust for recall bias are recommended.

METHODS

The 1988 Child Health Supplement to the National Health Interview Survey collected 12-month recall information on injuries that occurred to a national sample of 17,110 children aged 0 through 17 years. Using information on timing of interviews and reported injuries, estimated annual injury rates were calculated for 12 accumulative recall periods (from 1 to 12 months).

RESULTS

The data show significantly declining rates, from 24.4 per 100 for a 1-month recall period to 14.7 per 100 for a 12-month recall period. The largest declines were found for the 0- through 4-year-old age group and for minor injuries. Rates of injuries that caused a school loss day, a bed day, surgery, or hospitalization showed higher stability throughout recall periods.

CONCLUSIONS

Varying recall periods have profound effects on the patterns of childhood injury epidemiology that emerge from the data. Recall periods of between 1 and 3 months are recommended for use in similar survey settings.

Purification and characterization of simian immunodeficiency virus (SIVmac) envelope glycoprotein gp130 from virus-infected cells

A non-denaturing method has been developed for the purification of the envelope glycoprotein gp130 of the simian immunodeficiency virus (SIV) using infected cells as starting material. The procedure involves solubilization of cells infected with SIV (SIVmac251), enrichment of glycoproteins by lectin affinity chromatography, fractionation by reverse phase chromatography and purification by immunoaffinity chromatography. This procedure results in a greater than 95% purification of gp130 as assessed by polyacrylamide gel electrophoresis. There is no evidence for the presence of other virus-derived proteins after Western blot analysis using antibodies specific for virus proteins. Lectin-binding studies suggest that carbohydrate groups on the infected-cell-derived gp130 may differ from those on recombinant counterparts expressed in Chinese hamster ovary cells and Baculovirus-infected insect cells. The purified gp130 is highly immunogenic in rabbits and maintains the capacity to bind the CD4 receptor. A sufficient quantity of the infected-cell-derived gp130 has been prepared for immunization studies and subsequent live virus challenge studies in macaques.

Caring for hospice patients. In a nursing facility

Hospices across the nation have successfully developed hospice programs to serve residents in nursing facilities. Three major principles have been identified as key to the programs' success: the nursing facility is considered to be the patient's own home, the nursing facility's staff are the patient's extended family, and that same staff are members of the expanded hospice team.

A method for the amplification of unknown flanking DNA: targeted inverted repeat amplification

A new method has been developed that permits the rapid amplification of unknown DNA flanking a known site so that one can walk into an uncharacterized region of DNA. This method eliminates the steps and sequence artifacts associated with cloning and permits genome walking into unclonable regions of DNA. In this method, human genomic DNA is restriction enzyme digested and then ligated to the 3' end of a 5'-phosphorylated oligonucleotide using a short bridging oligonucleotide using a short bridging oligonucleotide as a splint. The phosphorylated oligonucleotide is designed to create 5'-end extensions that are complementary to the known sequence. Following denaturation and reannealing under dilute conditions that promote intra-strand annealing and under high stringency, only those DNA strands that contain the known sequence will form a stem-loop structure with a recessed and phosphorylated 5' end. This stem-loop renders a substrate for a subsequent heat-stable ligation reaction to another oligonucleotide that anneals to the known sequence immediately adjacent to the phosphorylated oligonucleotide high-stringency annealing site. The oligonucleotide appended to the phosphorylated oligonucleotide by the heat-stable ligase can, when present in its free, non-ligated form, prime DNA polymerase-mediated amplification of those strands modified by site-specific ligation to this same oligonucleotide. This is followed by one or two nested DNA amplifications, with the final amplification primed by the phosphorylated oligonucleotide in its free, non-ligated form. We successfully applied this method to the specific amplification of 2.2 kb of DNA flanking the 5' end of the cystic fibrosis transmembrane conductance regulator cDNA using primers that anneal to the cDNA sequence and to the specific amplification of 2.2 kb of human genomic beta-globin DNA flanking the primer annealing sites.

Relative mitogenic activities of wild-type and retinoblastoma binding-defective SV40 T antigens in serum-deprived and senescent human diploid fibroblasts

A novel gene transfer approach was used to investigate whether the retinoblastoma (Rb)-binding domain of simian virus 40 (SV40) T antigen is required for efficient T antigen-mediated stimulation of DNA synthesis is quiescent or senescent human embryo fibroblasts. In senescent cells, comparison between wild-type T antigen and a mutant defective in Rb binding (Glu-107-->Lys) revealed the latter to have approximately 15-fold lower activity. In contrast, comparison of wild-type and Rb- T antigens in serum-deprived quiescent cells revealed a much smaller (1.8-fold) difference. Surprisingly, an 18-fold differential could be induced by treating quiescent cells with the differentiating agent sodium butyrate. These results suggest that the role of Rb in control of the cell cycle is strongly dependent on the physiological state of the cell and the mechanism of growth arrest.

Peptide YY ameliorates cerulein-induced pancreatic injury in the rat

Peptide YY (PYY), a known inhibitor of both pancreatic secretion and the release of cholecystokinin (CCK), may play a role in the pathophysiology of acute pancreatitis (AP). Supramaximal stimulation of the pancreas with CCK, or its analogue cerulein, induces edematous AP. We previously documented significant decreases in plasma PYY in sodium taurocholate-induced AP in the anesthetized pig, with exogenous PYY suppressing plasma amylase activity. We hypothesized that PYY may ameliorate cerulein-induced pancreatic injury in a conscious animal model. Thirty-two male Sprague-Dawley rats underwent chronic cannulation of the jugular vein and carotid artery for drug infusion and blood sampling. The animals were allowed to recover from anesthesia for a minimum of 16 hours, after which they were randomized to one of four (n = 8) treatment groups (cerulein 10 micrograms/kg/h, PYY 400 pmol/kg/h, cerulein+PYY, and control-saline 2 mL/kg/h). All treatments were administered by intravenous infusion over the first 6 hours of the experiment. Blood samples were taken prior to infusion and at 1, 3, 6, 9, and 24 hours into the study; the rats were then killed and the pancreata removed for weighing and histologic examination. All pancreatic specimens were graded in a blinded fashion for vacuolization, edema, inflammation, and necrosis. The mean basal plasma amylase level for all animals was 1,171 +/- 100 U/L and was not significantly different between groups. Infusion of cerulein resulted in significant increases in plasma amylase levels at 3, 6, 9, and 24 hours (4,827 +/- 1,022 U/L at 24 hours). In the group receiving both cerulein and PYY, the hyperamylasemia was attenuated with a return to basal values at 24 hours (1,206 +/- 103 U/L). There was significant pancreatic weight gain (1.99 +/- 0.07 g versus 1.03 +/- 0.07 g) and a worsened histologic picture in cerulein-treated animals compared with control animals (worsened edema, necrosis, and vacuolization). The addition of PYY to cerulein resulted in significantly lower pancreatic weight (1.27 +/- 0.11 g) than in the non-PYY-treated rats receiving cerulein. Pancreatic weight was not significantly different in this group compared with the control group. In addition, pancreatic histologic findings were significantly improved in those rats receiving PYY (decreased vacuolization and necrosis). Amylase levels, pancreatic weight, and morphologic findings were not significantly changed compared with basal values in the control or PYY alone treated groups. e conclude that as an inhibitor of pancreatic exocrine secretion, PYY ameliorates cerulein-induced pancreatic injury in the conscious rat.

Lingual tonsillar hypertrophy causing failed intubation and cerebral anoxia

Hypertrophy of the lingual tonsils is an unusual condition that may cause complications such as airway obstruction, abscess, sleep apnea, and recurrent epiglottitis. There have been reports of difficult anesthesic intubation in children with enlarged lingual tonsils. We describe a 24-year-old woman whose markedly hypertrophied lingual tonsils prevented intubation after anesthesic relaxation during preparation for appendectomy.

Recent trends in the identification and treatment of high blood cholesterol by physicians. Progress and missed opportunities

OBJECTIVE

To investigate recent trends in the percentage and characteristics of patients being treated by a physician for high blood cholesterol (HBC) and to assess missed clinical opportunities to screen for HBC.

DESIGN, SETTING, PARTICIPANTS

Telephone interviews of 154,735 adults in 37 states that participated in the Behavioral Risk Factor Surveillance System during 1988-1990 to assess trends in the percentage of patients treated for HBC by a physician. An opportunity was considered missed if a person did not report being screened for HBC despite seeing a physician for preventive care in the last 2 years.

RESULTS

Between the first quarter of 1988 and the last quarter of 1990, the percentage of persons treated by a physician for HBC increased from 7.6% to 11.7% (P < .001). However, since an estimated 36% of US adults need treatment for HBC, fewer than one third of persons who need treatment are receiving it. Persons with two or more cardiac risk factors were more likely to be treated, while men, blacks, persons in lower socioeconomic groups, and persons between 20 and 34 years of age were less likely to be treated. Among the 126,571 persons who had seen a physician for preventive care within the last 2 years, missed opportunities to screen for HBC were most common among persons aged 20 through 34 years (59%) and among women who had seen obstetricians/gynecologists for preventive care (43%).

CONCLUSIONS

Fewer than one third of persons who need treatment for HBC as estimated by data from the second National Health and Nutrition and Nutrition Examination Survey are receiving treatment. Better use of clinical opportunities to screen for HBC could substantially accelerate the progress in identifying persons, young adults in particular, who are likely to benefit from cholesterol reduction.