Oral delivery of micro-encapsulated DNA vaccines

Oral delivery of vaccines is an attractive alternative to injection. It is a non-invasive procedure which allows access to the gut-associated lymphoid tissues (GALT). Immunisation at GALT results in mucosal immune responses, which may be of particular importance in protection against infection at mucosal surfaces, as well as systemic immune responses. Vaccine antigens can be protected in the gut by encapsulation in poly(DL-lactide-co-glycolide) (PLG) microparticles. Their uptake into the immune inductive tissues of the GALT is mediated by M cells, which selectively phagocytose particles less than 10 microns in diameter. We have developed a method for the PLG encapsulation of plasmid DNA. Encapsulated DNA, expressing the insect protein luciferase under the transcriptional control of the human cytomegalovirus immediate early promoter, was administered to mice by intraperitoneal injection or oral gavage. Intraperitoneal injection of encapsulated DNA elicited good serum IgG and IgM responses and a modest IgA response. Oral administration stimulated good serum antibody titres in all three classes, and in addition, significant levels of mucosal IgA. PLG encapsulation thus has the ability to protect plasmid DNA against degradation after administration, and to facilitate its uptake into appropriate cells for the subsequent expression and presentation of antigen, in such a way as to elicit both systemic and mucosal antibody responses. This may have major implications for the design of novel vaccines and delivery strategies.

Embryonic expression of the putative gamma subunit of the sodium pump is required for acquisition of fluid transport capacity during mouse blastocyst development

The sodium/potassium pump, Na+,K+-ATPase, is generally understood to function as a heterodimer of two subunits, a catalytic alpha subunit and a noncatalytic, glycosylated beta subunit. Recently, a putative third subunit, the gamma subunit, was cloned. This small protein (6.5 kD) coimmunoprecipitates with the alpha and beta subunits and is closely associated with the ouabain binding site on the holoenzyme, but its function is unknown. We have investigated the expression of the gamma subunit in preimplantation mouse development, where Na+, K+-ATPase plays a critical role as the driving force for blastocoel formation (cavitation). Using reverse transcriptase-polymerase chain reaction, we demonstrated that the gamma subunit mRNA accumulates continuously from the eight-cell stage onward and that it cosediments with polyribosomes from its time of first appearance. Confocal immunofluorescence microscopy revealed that the gamma subunit itself accumulates and is localized at the blastomere surfaces up to the blastocyst stage. In contrast with the alpha and beta subunits, the gamma subunit is not concentrated in the basolateral surface of the polarized trophectoderm layer, but is strongly expressed at the apical surface as well. When embryos were treated with antisense oligodeoxynucleotide complementary to the gamma subunit mRNA, ouabain-sensitive K+ transport (as indicated by 86Rb+ uptake) was reduced and cavitation delayed. However, Na+, K+-ATPase enzymatic activity was unaffected as determined by a direct phosphorylation assay ("back door" phosphorylation) applied to plasma membrane preparations. These results indicate that the gamma subunit, although not an integral component of Na+,K+-ATPase, is an important determinant of active cation transport and that, as such, its embryonic expression is essential for blastocoel formation in the mouse.

Panhandle polymerase chain reaction amplifies MLL genomic translocation breakpoint involving unknown partner gene

We used a new approach called panhandle polymerase chain reaction (PCR) to clone an MLL genomic translocation breakpoint in a case of acute lymphoblastic leukemia of infancy in which karyotype analysis was technically unsuccessful and did not show the translocation partner. Panhandle PCR amplified known MLL sequence 5' of the breakpoint and 3' sequence from the unknown partner gene from a DNA template with an intrastrand loop schematically shaped like a pan with a handle. The 7-kb panhandle PCR product contained the translocation breakpoint in MLL intron 8. The partner DNA included unique nonrepetitive sequences, Alu and mammalian apparent LTR-retrotransposon (MaLR) repetitive sequences, and a region of homology to expressed sequence tags. MaLR sequences have not been found before near leukemia-associated translocation breakpoints. The nonrepetitive sequences were not homologous to known partner genes of MLL. Screening of somatic cell hybrid and radiation hybrid lines by PCR and fluorescence in situ hybridization analysis of normal metaphase chromosomes mapped the partner DNA to chromosome band 4q21. Reverse transcriptase-PCR identified an MLL-AF-4 chimeric mRNA, indicating that panhandle PCR identified a fusion of MLL with a previously uncharacterized AF-4 intronic sequence. Panhandle PCR facilitates cloning translocation breakpoints and identifying unknown partner genes.

Socioeconomic and racial/ethnic factors affecting non-fatal medically attended injury rates in US children

OBJECTIVE

Using a representative survey of US children, the purpose was to evaluate separate effects of socioeconomic and racial/ethnic factors, including access to care, on medically attended non-fatal injury rates.

METHODS

Multivariate linear regression models were used to determine associations between injuries and health care coverage (insurance or Medicaid), having a place to go for care, race/ethnicity, maternal education, number of adults and children in the household, poverty, and urbanicity. The 1988 Child Health Supplement to the National Health Interview Survey included questions on medically attended injuries, and their cause, location, and effects on the child. Injury categories included total, consequential, occurrence at home or school, falls, and being struck or cut.

RESULTS

Lack of health care coverage was consistently associated with lower medically attended injury rates in non-Hispanic blacks or whites and Mexican-Americans, but affected total rates for each group differently due to unequal distribution of health care coverage. Injuries occurred about 40% more frequently to children and adolescents living in single adult households compared with two adult homes for all injury categories except for injuries occurring at school.

CONCLUSIONS

Preventive interventions targeted to specific populations based on assumptions that poverty, lack of education, or minority status result in greater risks for injuries require a closer look. Efficient targeting should address underlying factors such as differences in exposures and environments associated with single adult homes or recreational activities. Data sources used to target high risk populations for interventions need to address bias due to access to care.

Issues & trends affecting the nation's hospices

As the hospice industry has grown and moved from isolation into the health care system, it necessarily faces new issues. Some are definite, such as budget considerations; others are more theoretical--for instance, physician-assisted suicide--and thus may remain up for debate as hospice matures into an as-yet-unseen status.

Pilin C-terminal peptide binds asialo-GM1 in liposomes: a 2H-NMR study

Wideline 2H-NMR observations are described demonstrating the interaction of a synthetic peptide (PAK), representing residues 128-144 of the binding domain of pilin surface protein from Pseudomonas aeruginosa, with a complex glycosphingolipid thought to be its natural receptor. The receptor glycolipid (asialo-GM1) carried 2H probe nuclei on the terminal and next-to-terminal carbohydrate residues and was present as a minor component in fluid phosphatidylcholine liposomes. The peptide induced spectral changes that could be understood as arising from receptor motional changes, without receptor immobilization on the NMR time scale of 10(4) s-1. Spectral effects were reversed by reduction of the single peptide disulfide bond--a structural feature previously shown to be a determinant of PAK conformation (Campbell AP, McInnes C, Hodges RS, Sykes BD. 1995. Biochemistry 34:16255-16268). This is the first demonstration of PAK interaction with its epithelial cell receptor in liposomes.

Panhandle PCR strategy to amplify MLL genomic breakpoints in treatment-related leukemias

Panhandle PCR amplifies genomic DNA with known 5' and unknown 3' sequences from a template with an intrastrand loop schematically shaped like a pan with a handle. We used panhandle PCR to clone MLL genomic breakpoints in two pediatric treatment-related leukemias. The karyotype in a case of treatment-related acute lymphoblastic leukemia showed the t(4;11)(q21;q23). Panhandle PCR amplified the translocation breakpoint at position 2158 in intron 6 in the 5' MLL breakpoint cluster region (bcr). The karyotype in a case of treatment-related acute myeloid leukemia was normal, but Southern blot analysis showed a single MLL gene rearrangement. Panhandle PCR amplified the breakpoint at position 1493 in MLL intron 6. Screening of somatic cell hybrid and radiation hybrid DNAs by PCR and reverse transcriptase-PCR analysis of the leukemic cells indicated that panhandle PCR identified a fusion of MLL intron 6 with a previously uncharacterized sequence in MLL intron 1, consistent with a partial duplication. In both cases, the breakpoints in the MLL bcr were in Alu repeats, and there were Alu repeats in proximity to the breakpoints in the partner DNAs, suggesting that Alu sequences were relevant to these rearrangements. This study shows that panhandle PCR is an effective method for cloning MLL genomic breakpoints in treatment-related leukemias. Analysis of additional pediatric cases will determine whether breakpoint distribution deviates from the predilection for 3' distribution in the bcr that has been found in adult cases.

Oligomerization of the EGF receptor transmembrane domain: a 2H NMR study in lipid bilayers

During the course of a previous study by wideline 2H NMR, we noted spectral features suggesting the possibility of monitoring homodimer/oligomer interactions between transmembrane domains of the EGF receptor in lipid bilayers [Rigby, A. R., Shaw, G. S., Barber, K. R., & Grant, C. W. M. (1996) Biochemistry 35, 12591-12601]. In the present work this possibility was explored using the 34-residue peptide EGFRtm. The peptide sequence included the 23 amino acid hydrophobic stretch thought to span the membrane (Ile622-Met644 of the EGF receptor), plus the first 10 amino acids of the receptor's cytoplasmic domain (Arg645-Thr654). Selective deuteration was carried out at sites corresponding to Ala623, Met644, and Val650. Samples were studied from 12 to 65 degrees C by 2H NMR in fluid membranes having low peptide concentration (1 mol %) or high peptide concentration (6 mol %). Methyl groups proved to be technically particularly attractive probe locations. Reversible homodimer/oligomer interactions were detected in membranes of the common natural phospholipid 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), without cholesterol. Effects on the EGF receptor transmembrane domain included alterations in peptide backbone motional order and/or conformation at the site of Ala623 within the membrane, and alterations in motional properties of the Val650 side chain in the cytoplasmic domain. There was little spectral evidence of stable oligomer formation except at the lowest temperature studied. Addition of 33% cholesterol to these membranes was accompanied by spectral changes consistent with the formation of more stable peptide oligomers, and by evidence that peptide-peptide interactions were sensed at all three probe locations. Peptide-peptide interactions remained easily reversible, particularly at higher temperatures. Freeze-fracture electron microscopy of the NMR samples demonstrated peptide-related intramembranous particles traversing the membranes. To our knowledge, this is the first electron microscopy description of receptor tyrosine kinases or their fragments in model membranes. In the presence of cholesterol, the peptide-related particles were generally larger, more sharply demarcated, and showed a tendency to cluster. These observations relate to models of receptor lateral association as an aspect of signal transduction, and to forces that may determine protein sorting and organization in cell membranes. We suggest that the cholesterol effects reflect a general phenomenon rather than one specific to the EGF receptor.

Globoside as a membrane receptor: a consideration of oligosaccharide communication with the hydrophobic domain

Recognition of macromolecules by glycosphingolipids is closely correlated with the nature of the glycolipid carbohydrate; however, it is also thought to be secondarily modulated by the structure of the single fatty acid. In the present work, we sought insight into what physical effect a change in this fatty acid has on the extramembranous portion of globosides at liposomal surfaces mimicking systems for which modulated receptor function has been recorded in the past. Protons of the exocyclic hydroxymethyl group on the terminal Gal residue of globotriaosylceramide (Gb3) were replaced with deuterium. In this location, the nonperturbing probe nuclei sampled cumulative conformational and orientational characteristics of the oligosaccharide chain at a sugar residue that is critical in specific binding of verotoxins. Deuterated Gb3 having 18:1 fatty acid was compared to the same species having 22:1 fatty acid, at 6.3 mol % in unsonicated bilayers of dipalmitoylphosphatidylcholine/cholesterol. Both produced narrow, apparently axially asymmetric 2H NMR spectra over a wide temperature range. Motional properties of the terminal sugar were measurably influenced by the fluidity of the host matrix; however, evidence was not found for conformational or orientational variation in this sugar brought about by the fatty acid alteration. In related experiments, acetate protons on the terminal N-acetyl galactosamine (GalNAc) residue of globotetraosylceramide (Gb4) were substituted with deuterium, and the natural fatty acid was replaced with 18:0 or 24:0 species deuterated at C2. Once again, species with short vs long fatty acid were examined for evidence of headgroup differences. Spectra of Gb4 were compared at 10 mol % in unsonicated fluid bilayers of 1-palmitoyl-2-oleoylphosphatidylcholine, and at 5 mol % in membranes containing 33 mol% cholesterol. Spectral splittings reflecting cumulative effects on conformation and order at the terminal deuterated sugar remained unchanged between species having 18:0 vs 24:0 fatty acid in POPC/cholesterol. In a pure POPC host matrix, there was clear evidence of a motional difference between the two--the longer chain Gb4 demonstrating spectral asymmetry--but the spectral width was unchanged. Transverse relaxation times, T2, were measured. Our findings appear to help correlate the conclusions of a number of workers dealing with the molecular basis of crypticity. We suggest that changes in glycolipid receptor function based on ceramide fatty acid variation have a major origin in the fatty acid's ability to determine the thermodynamics of interaction with the host matrix, as reflected in such parameters as glycolipid motional properties, local membrane curvature, and likely glycolipid time-dependent lateral associations. The result at low concentrations of glycolipid may often be only a subtly altered collective surface epitope, best detected by a specific recognition event.

Amplification of 4-9-kb human genomic DNA flanking a known site using a panhandle PCR variant

We present a method for the in vitro amplification of > 6.0 kb of DNA flanking a known site. This is accomplished by ligating an oligonucleotide to create an inverted repeat of a portion of the known sequence, followed by single-primer polymerase chain reaction (PCR) amplifications. This method generates a panhandle template following primer extension on the strand of interest. It does not involve template-directed extension from the ligated oligonucleotide, and it is carried out without DNA extractions. We have used this method to amplify 4.5-9.4 kb of DNA flanking the original primer annealing sites directly from human genomic DNA.

Carpal tunnel syndrome in the mucopolysaccharidoses and mucolipidoses

Children with a mucopolysaccharidosis or mucolipidosis suffer progressive disability of the hands, particularly in relation to dysfunction of the median nerve. This is an increasing problem because bone-marrow transplantation has dramatically improved survival without apparently changing the musculoskeletal manifestations. We have reviewed 48 children with these syndromes who required carpal tunnel decompression, recording symptoms, signs, radiological, electrophysiological and operative findings, histology and upper-limb function. In these children the carpal tunnel syndrome differs from that seen in adults. Symptoms are rare but signs such as decreased sweating, pulp atrophy, thenar wasting and manual clumsiness are much more common. At operation, the flexor retinaculum was thickened and a mass of white tenosynovium engulfed the flexor tendons. Most patients had some definite nerve constriction with a thickened epineurium. Functional improvement was seen after early decompression, with some benefit from simultaneous tendon release. Regular physiotherapy helped to maintain increased hand movement. We describe our assessment protocol, the physiotherapy and operative regime and the standard functional review which helps to maximise function in the hands and upper limbs of these children.

Poly(DL-lactide-co-glycolide)-encapsulated plasmid DNA elicits systemic and mucosal antibody responses to encoded protein after oral administration

We have developed a method for the encapsulation of plasmid DNA in poly(DL-lactide-co-glycolide) microparticles. Encapsulated DNA, expressing the insect protein luciferase under the transcriptional control of the human cytomegalovirus immediate early promoter, was administered to mice by intraperitoneal injection or oral gavage. Intraperitoneal injection of encapsulated DNA elicited good serum IgG and IgM responses, and a modest IgA response. Oral administration stimulated good serum antibody responses in all three classes, and in addition, significant levels of mucosal IgA. PLG encapsulation thus has the ability to protect plasmid DNA against degradation after administration, and to facilitate its uptake into appropriate cells for the subsequent expression and presentation of antigen, in such a way as to elicit both systemic and mucosal antibody responses. These findings may have major implications for the design of novel vaccines and delivery strategies.

An iterative and regenerative method for DNA sequencing

This paper presents, to our knowledge, the first iterative DNA sequencing method that regenerates the product of interest during each iterative cycle, allowing it to overcome the critical obstacles that impede alternative iterative approaches to DNA sequencing: loss of product and the accumulation of background signal due to incomplete reactions. It can sequence numerous double-stranded (ds) DNA segments in parallel without gel resolution of DNA fragments and can sequence DNA that is almost entirely double-stranded, preventing the secondary structures that impede sequencing by hybridization. This method uses ligation of an adaptor containing the recognition domain for a class-IIS restriction endonuclease and digestion with a class-IIS restriction endonuclease that recognizes the adaptor's recognition domain. This generates a set of DNA templates that are each composed of a short overhang positioned at a fixed interval with respect to one end of the original dsDNA fragment. Adaptor ligation also appends a unique sequence during each iterative cycle, so that the polymerase chain reaction can be used to regenerate the desired template-precursor before class-IIS restriction endonuclease digestion. Following class-IIS restriction endonuclease digestion, sequencing of a nucleotide in each overhang occurs by template-directed ligation during adaptor ligation or through a separate template-directed polymerization step with labeled ddNTPs. DNA sequencing occurs in strides determined by the number of nucleotides separating the recognition and cleavage domains for the class-IIS restriction endonuclease encoded in the ligated adaptor, maximizing the span of DNA sequenced for a given number of iterative cycles. This method allows the concurrent sequencing of numerous dsDNA segments in a microplate format, and in the future it can be adapted to biochip format.

Activity of L-phenylalanine ammonia-lyase in organic solvents

L-Phenylalanine ammonia-lyase (EC 4.3.1.5), (PAL) was shown to be active in a monophasic non-aqueous medium for the first time. Ultraviolet absorbance spectra of trans-cinnamic acid were shown to be similar in both water and n-octanol. High catalytic rates were observed only when the enzyme was placed in solvents containing high concentrations of water. PAL forward reaction was observed only when the water concentration in n-octanol exceeded 2.0% (v/v), which corresponds to a value of 0.8 in thermodynamic water activity (aw) terms. In n-octanol containing either 2.0 or 3.5% (v/v) H2O (and 2 mM L-phenylalanine), lyophilized and aw = 0.113 pre-equilibrated PAL powder exhibited catalytic rates 0.02 and 1.75% of the value observed in aqueous solution respectively. A freshly lyophilized (non-equilibrated) PAL preparation incubated in water-saturated n-octanol (measured [H2O] = 3.6% (v/v), L-phenylalanine concentration approximately 6.8 mM) gave catalytic activity values 17% of those observed in aqueous solution. This is the first demonstration of catalytic activity of an amino acid ammonia-lyase in monophasic organic solvent.

Displaced stress fracture of the femoral neck in an active amenorrhoeic adolescent

Female athletes in endurance sports are at risk of osteoporosis which predisposes them to femoral neck stress fractures. These require early diagnosis and treatment to avoid catastrophic consequences.

Oral delivery of poly(lactide-co-glycolide) encapsulated vaccines

The induction of mucosal immune responses by oral delivery of vaccines is highly desirable. However vaccines to be used in this context will require protection from degradation in the gut and the use of specialised vehicles for their delivery and presentation. Using the biodegradable and biocompatible polymer, poly(lactide-co-glycolide), we have encapsulated bacterial and viral proteins, synthetic peptides and plasmid DNA in microparticles, and compared the immune responses resulting from their oral and parenteral administration to mice. The successful induction of specific systemic and mucosal humoral immune responses, as well as cell-mediated immune responses, demonstrates the potential of this polymer formulation as a vehicle for the oral delivery of vaccines.

Epitope mapping and tagging by recombination PCR mutagenesis

We describe a rapid PCR method that directly inserts an epitope tag into an open reading frame (ORF) to facilitate protein detection. This project was performed within a varicella-zoster virus (VZV) system. In earlier work, we produced a monoclonal antibody (MAb 3B3) to one VZV ORF called gE. MAb 3B3 bound to its epitope under extreme denaturing conditions. To further characterize the epitope, we devised a technique that identified the epitope by its insertion into another protein of interest. The 3B3 epitope was mapped to 11 residues (residues 151-161; QRQYGDVFKGD) in the gE ectodomain by using the technique of recombination PCR. At the same time, the 3B3 epitope was inserted in-frame into another VZV protein for which no MAb was available. The end result, VZV gL3B3.11, was a unique construct possessing a 33-bp insertion that expresses gL-3B3 protein recognized by the MAb 3B3. The 3B3 epitope was verified to be both highly functional and stable. An important advantage of this recombination PCR method of epitope mapping and tagging is that the epitope sequence can be inserted anywhere along the nucleotide sequence of an ORF, regardless of existing restriction sites.

Mucosal immunization with a measles virus CTL epitope encapsulated in biodegradable PLG microparticles

The immunogenicity of a cytotoxic T cell epitope (CTL) representing residues 52-60 from measles virus (MV) nucleoprotein, encapsulated in poly(lactide-co-glycolide) (PLG) microparticles was evaluated after mucosal immunization. After intranasal administration of the encapsulated CTL epitope linked at the carboxyl terminus of two copies of a T-helper epitope (TT-NP6), peptide-specific and MV-specific CTL responses were detected in splenocytes. However, these responses were lower than the responses observed when the TT-NP6 peptide was administered intranasally in saline or using CTB as an adjuvant. Intranasal coadministration of the encapsulated TT-NP6 peptide with CTB did not result in any significant potentiation of the CTL responses. The effectiveness of biodegradable PLG microparticles for mucosal delivery of CTL epitopes, combined with their excellent tissue compatibility and biodegradability suggests that they represent a valuable delivery system for synthetic immunogens. However, further work is needed to define the requirements for effective absorption by the nasal epithelium.

Recurring digital fibroma of childhood

A case of recurring digital fibroma of childhood is presented. The natural history of this condition over several years is documented. The literature is reviewed, with particular reference to the management of the condition. Surgeons should be aware of the clinical features and the principles of management of this condition, as patients may be referred because of associated finger or toe deformities.

Minor influence of sialic acid on conformation of a membrane-bound oligosaccharide recognition site

Wideline 2H NMR spectroscopy was used to assess the conformational and orientational effects of N-acetylneuraminic acid (NeuAc) (sialic acid) as a component of a particular oligosaccharide chain at a bilayer membrane surface. For this purpose, three glycosphingolipids, sharing a neutral core tetrasaccharide and differing only in the number of sialic acid residues, were compared. The starting compound was GD1A, which has terminal sialic acid attached to the second and fourth sugars of its neutral tetrasaccharide core. GD1A was probe-labeled in a non-perturbing fashion on both of these sialic acid residues and on its single GalNAc residue by replacement of -COCH3 with -COCD3 giving [(d3NeuAc)2,d3-GalNAc]GA1a. This represents the most complex glycolipid to have been studied by 2H NMR spectroscopy at a bilayer membrane surface. The sialic acid residue on the fourth sugar from the membrane was subsequently removed to produce the glycolipid [d3NeuAc,d3GalNAc]GM1, deuterated at the two remaining amino sugars. The neutral glycolipid [d3GalNAc]asialo-GM1 was then generated by removal of the second sialic acid residue, leaving an uncharged species deuterated at one (internal) oligosaccharide chain site (GalNAc). The effect of sialic acid was futher examined by selective deuteration of GM1 and asialo-GM1 at C6 of the terminal Gal residue, giving [d2Gal]GM1 and [d2Gal]asialo-GM1. Spectra of the three glycosphingolipids were compared at 7.7 mol % in unsoncicated fluid bilayers of 1-palmitoyl-2-oleoylphosphatidylcholine containing 23 mol % cholesterol. For liposomes suspend in buffered salt solutions with 2 mM Ca2+, 2H NMR spectra demonstrated the presence of well defined average conformation for each oligosaccharide chain. This preferred average conformation persisted over a wide temperature range, consistent with there being a single major oligosaccharide conformer in each case. Spectral features arising from both deuterated amino sugar (GalNAc) of asialo-GM1 could be identified, little changed, in spectra of GM1 and GD1A. Similarly, deuterons in the terminal Gal residue of asialo-Gm1 produced the same spectrum seen for this residue in GM1. Our findings indicate that certain major conformational and orientational features of this complex oligosaccharide recognition site are preserved, within maximum angular deviation + or -5 degrees or less upon addition or removal of a sialic acid residue.

Biodegradable microparticles as a delivery system for measles virus cytotoxic T cell epitopes

Cytotoxic T-cell (CTL) responses are likely to be important for the clearance of a measles virus (MV) infection. To induce CTL responses. replicating vectors have generally been used but the use of such vectors in humans mav be problematic, and immunization with synthetic peptides may be more appropriate. We have investigated the potential of poly(lactide-co-glycolide)(PLG) microparticles as a delivery system for a CTL epitope representing residues 51-59 from MV nucleoprotein. After a single intraperitoneal injection in saline of the encapsulated epitope, CTL responses to the homologous peptide and MV were detected over a period of 4 months. Responses reached a maximum 30 days after priming and were maintained at high levels for 120 days. These responses were higher than those observed when the CTL epitope was administered in saline or as an emulsion in Incomplete Freund's Adjuvant. The pronounced immunostimulatory effect of microparticles, combined with their excellent tissue compatibility and biodegradability suggests that they represent a valuable delivery system for synthetic peptide immunogens.

Orally administered microencapsulated Bordetella pertussis fimbriae protect mice from B. pertussis respiratory infection

Fimbriae from Bordetella pertussis have been encapsulated in poly(lactide-co-glycolide) microparticles of a size appropriate for uptake by the immune inductive tissues of the gastrointestinal tract. Mice were immunized by oral gavage with a single dose of 10 micrograms of microencapsulated fimbriae. The resulting immune responses were compared with those resulting from intraperitoneal injection of mice with equivalent amounts of fimbriae absorbed onto alhydrogel. The examination of serum and mucosal secretions, collected over a 6-week period, for specific antifimbrial antibodies clearly demonstrated that only orally immunized animals mounted measurable immune responses in external secretions. Six weeks after immunization, all immunized animals were protected against intranasal challenge with live B. pertussis.

Poly(lactide-co-glycolide) microencapsulation of vaccine antigens

Fimbriae from Bordetella pertussis have been encapsulated in poly(lactide-co-glycolide) (PLG) microspheres of a size appropriate for oral administration. The binding of antibodies which react with conformational or linear fimbrial epitopes, to fimbriae released from microspheres, suggested that the process of was not detrimental to the native integrity of the protein. Mice were immunised by oral gavage with a single dose of microencapsulated fimbriae, or with fimbriae adsorbed onto alhydrogel and administered by intraperitoneal injection. The resulting immune responses in serum were comparable but only oral administration of microencapsulated fimbriae elicited specific immune responses in external secretions. Six weeks after immunisation, both groups of immunised animals were protected against challenge with live B. pertussis.

Multiple members of the connexin gene family participate in preimplantation development of the mouse

The connexin gene family, of which there are at least 12 members in rodents, encodes the protein subunits intercellular membrane channels (gap junction channels). Because of the diverse structural and biophysical properties exhibited by the different connexins, it has been proposed that each may play a unique role in development or homeostasis. We have begun to test this hypothesis in the preimplantation mouse embryo in which de novo gap junction assembly is a developmentally regulated event. As a first step, we have used reverse transcription-polymerase chain reaction (RT-PCR) to determine the connexin mRNA phenotype of mouse blastocysts, and have identified transcripts of connexins 30.3, 31, 31.1, 40, 43, and 45. Quantitative measurements indicated that all six of these connexin genes are transcribed after fertilization. They can be divided into two groups with respect to the timing of mRNA accumulation: Cx31, Cx43, and Cx45 mRNAs accumulate continuously from the two- or four-cell stage, whereas Cx30.3, Cx31.1, and Cx40 mRNAs accumulate beginning in the eight-cell stage. All six mRNAs were found to co-sediment with polyribosomes from their time of first appearance, indicating that all six are translated. The expression of Cx31.1 and Cx40 was examined by confocal immunofluorescence microscopy; whereas both could be detected in compacting embryos, only Cx31.1 could be seen in punctate membrane foci indicative of gap junctions. Taken together with other results (published or submitted), our findings indicate that at least four connexins (Cx31, 31.1, 43 and 45) contribute to gap junctions in preimplantation development. The expression of multiple connexin genes during this early period of embryogenesis (when there are only two distinct cell types) raises questions about the functional significance of connexin diversity in this context.

Microencapsulation of vaccines

Despite obvious successes in controlling most serious childhood infections, there is constant pressure to develop cheaper, safer, and more effective infant vaccination programs. However, any improvements to pediatric vaccines in the foreseeable future are likely to arise through the introduction of better adjuvants and delivery systems. For example, a single injection comprising primary and booster doses of vaccine would improve compliance in a cost-effective way by reducing the number of visits to clinics or medical centers. Equally, administering existing vaccines orally would remove the trauma of injection and the reliance on medical staff to perform the injections. Many vaccines are dependent on a cold chain; improving the stability of vaccines would help to reduce the cost of vaccination, To tackle such issues, researchers are borrowing ideas from other areas of the pharmaceutical industry to try to improve the performance of vaccines and reduce the cost of these important health-care interventions.

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.