SEPN1-related myopathies: clinical course in a large cohort of patients

OBJECTIVE

To assess the clinical course and genotype-phenotype correlations in patients with selenoprotein-related myopathy (SEPN1-RM) due to selenoprotein N1 gene (SEPN1) mutations for a retrospective cross-sectional study.

METHODS

Forty-one patients aged 1-60 years were included. Clinical data including scoliosis, respiratory function, and growth measurements were collected by case note review.

RESULTS

Mean age at onset was 2.7 years, ranging from birth to the second decade of life. All but 2 remained independently ambulant: one lost ambulation at age 5 years and another in his late 50s. The mean age of starting nocturnal noninvasive ventilation (NIV) was 13.9 years. One child required full-time NIV at the age of 1 year while in 2 cases NIV was started at 33 years. Two patients died from respiratory failure at the age of 10 and 22 years, respectively. The mean age at scoliosis onset was 10 years, in most cases preceded by rigidity of the spine. Fourteen patients had successful spinal surgery (mean age 13.9 years). Twenty-one were underweight; however, overt feeding difficulties were not a feature.

CONCLUSIONS

This study describes the largest population affected by SEPN1-RM reported so far. Our findings show that the spectrum of severity is wider than previously reported. Respiratory insufficiency generally develops by 14 years but may occur as early as in infancy or not until the fourth decade. Motor abilities remain essentially static over time even in patients with early presentation. Most adult patients remain ambulant and fully employed.

A pilot randomised controlled trial of a home-based exercise programme aimed at improving endurance and function in adults with neuromuscular disorders

AIM

To investigate the feasibility and effect of a home-based exercise programme on walking endurance, muscle strength, fatigue and function in people with neuromuscular disorders (NMDs).

METHODS

20 adults with NMDs recruited to a control (n = 11) or exercise (n = 9) group were assessed by blinded assessors at baseline and at week 8. Walking and strengthening exercises were given to the exercise group in an 8-week home exercise programme. A 2-min walk distance was the main outcome measurement; isometric muscle strength, fatigue and function were secondary measurements.

RESULTS

2-min walk distances were not found to change in either group (p>0.05; control: mean 14.50 (SD 22.06) m; exercise: mean 2.88 (SD 20.08) m), and no difference was observed in the change scores between groups (p>0.05). Leg muscle strength increased in the exercise group (p<0.05) but not in the control group (p>0.05). Significance was reached between the groups with respect to the difference in change in muscle strength scores in the right quadriceps (p<0.05; control: mean -2.82 (SD 4.87) kg; exercise: mean -7.08 (SD 2.82) kg). No change was observed in fatigue or function scores (p<0.05).

CONCLUSIONS

A home-based approach aimed at improving endurance in adults with NMDs is feasible and further investigation on a larger sample is warranted.

Application of Maximum Entropy reconstruction to PISEMA spectra

Maximum Entropy reconstruction is applied to two-dimensional PISEMA spectra of stationary samples of peptide crystals and proteins in magnetically aligned virus particles and membrane bilayers. Improvements in signal-to-noise ratios were observed with minimal distortion of the spectra when Maximum Entropy reconstruction was applied to non-linearly sampled data in the indirect dimension. Maximum Entropy reconstruction was also applied in the direct dimension by selecting sub-sets of data from the free induction decays. Because the noise is uncorrelated in the spectra obtained by Maximum Entropy reconstruction of data with different non-linear sampling schedules, it is possible to improve the signal-to-noise ratios by co-addition of multiple spectra derived from one experimental data set. The combined application of Maximum Entropy to data in the indirect and direct dimensions has the potential to lead to substantial reductions in the total amount of experimental time required for acquisition of data in multidimensional NMR experiments.

Biosynthesis and purification of a hydrophobic peptide from transmembrane domains of G-protein-coupled CB2 receptor

A major challenge for the structural study of the seven-transmembrane G-protein-coupled receptors is to obtain a sufficient amount of purified protein at the milligram level, which is required for either nuclear magnetic resonance (NMR) spectroscopy or X-ray crystallography. In order to develop a high-yield and cost-effective method, and also to obtain preliminary structural information for the computer modeling of the three-dimensional receptor structural model, a highly hydrophobic peptide from human cannabinoid subtype 2 receptor CB2(65-101), was chosen to develop high-yield membrane protein expression and purification methods. The peptide included the second transmembrane helix with the associated loop regions of the CB2 receptor. It was over-expressed in Escherichia coli, with a modified TrpDelta LE1413 (TrpLE) leading fusion sequence and a nine-histidine tag, and was then separated and purified from the tag in a preparative scale. An experimental protocol for the chemical cleavage of membrane protein fragment was developed using cyanogen bromide to remove the TrpLE tag from the hydrophobic fusion protein. In addition, protein uniformly labeled with isotopic 15N was obtained by expression in 15N-enriched minimum media. The developed and optimized preparation scheme of expression, cleavage, and purification provided a sufficient amount of peptide for NMR structure analysis and other biophysical studies that will be reported elsewhere. The process of fusion protein cleavage following purification was monitored by high-performance liquid chromatography (HPLC) and mass spectrometry (MS), and the final sample was validated by MS and circular dichroism experiments.

NMR experiments on aligned samples of membrane proteins

NMR methods can be used to determine the structures of membrane proteins. Lipids can be chosen so that protein-containing micelles, bicelles, or bilayers are available as samples. All three types of samples can be aligned weakly or strongly, depending on their rotational correlation time. Solution NMR methods can be used with weakly aligned micelle and small bicelle samples. Solid-state NMR methods can be used with mechanically aligned bilayer and magnetically aligned bicelle samples.

Linear sebaceous naevus syndrome and resistant rickets

The association between vitamin-D-resistant rickets and linear sebaceous naevus syndrome is extremely rare. Only eight cases have been described in the English literature and in none were the skeletal aspects addressed. We present three new cases and describe the musculoskeletal features. The details and outcome of surgery for correction of the deformities are discussed. The disturbances of metabolism of vitamin D and the effects of pharmacological treatment are also described.

Recombinant pre-pro-Concanavalin A (jack bean) is stable but of low solubility

The cDNA for pre-pro-Concanavalin A (pre-pro-ConA) was cloned into the cytoplasmic expression vector pKK233-2 to give rise to pCONEXP2 which was used to express the lectin precursor. Pre-pro-ConA is stable and is not transposed and ligated to form the mature protein. No signal peptide removal is observed. The solubility of pre-pro-ConA could not be increased by guanidine hydrochloride denaturation/dilution treatment.

A new surgical technique for keratoglobus-tectonic lamellar keratoplasty followed by secondary penetrating keratoplasty

PURPOSE

To develop a technique that achieves satisfactory visual rehabilitation in keratoglobus, without the problems of re-epithelialization failure and with minimal risk of graft rejection.

METHODS

A patient with bilateral keratoglobus and visual acuities of light perception in the right eye and 6/60 in the left underwent a tectonic lamellar keratoplasty to the right eye. The cornea was first trephined to the depth of the anterior stroma within the limbus. A lamellar dissection technique then was used to tunnel into sclera under the limbus to preserve stem cells. The host corneal epithelium was completely débrided, and a donor corneoscleral button, denuded of its endothelium, was laid on top. A paracentesis was made, and aqueous was aspirated until the anterior chamber had collapsed enough to take up a more physiologic shape. The donor corneoscleral graft was sutured into the prefashioned scleral bed with long, interrupted sutures. Once in situ, the donor graft was débrided of epithelium, and the host limbus was sutured on to it, covering its scleral component. Six months later, a penetrating keratoplasty was performed. The same procedure was performed on the left eye 2 years later.

RESULTS

The right eye maintained a best-corrected visual acuity of 6/60 for 16 months after the penetrating graft until the graft decompensated, leaving a final acuity of counting fingers. The left eye maintained a best-corrected visual acuity of 6/18.

CONCLUSION

Tectonic lamellar keratoplasty to preserve the host limbus, followed by secondary penetrating keratoplasty, is a realistic alternative to other procedures for the surgical management of keratoglobus.

The mouse Na+-K+-ATPase gamma-subunit gene (Fxyd2) encodes three developmentally regulated transcripts

The Na(+)-K(+)-ATPase is understood to function as a hetero-oligomer of alpha- and beta-subunits, but a third subunit, gamma, has been proposed to influence the enzyme's catalytic function. Recently, two variants of the gamma-subunit have been described in kidney, raising the possibility of multiple gamma-subunits with diverse functions. We now report the cloning and sequencing of the mouse gamma-subunit gene (Fxyd2). Analysis of the structure of the gene shows that it encodes three mRNAs that have distinct NH(2)-terminal (extracellular) encoding sequences but common transmembrane and COOH-terminal-encoding sequences resulting from differential splicing and, probably, alternate promoter usage. The three mRNAs have tissue-specific expression patterns. The existence of three different extracellular domains of the gamma-variants and how they may interact with the sodium pump to alter its cation transport properties must now be taken into account for future understanding of the modulation of the Na(+)-K(+)-ATPase by its gamma-subunit.

A novel microencapsulated peptide vaccine against hepatitis B

A 48 amino acid synthetic peptide (S121/48) representing residues 121-167 of the major envelope protein of hepatitis B virus (HBsAg) was successfully encapsulated into polylactide co-glycolide microspheres. A single immunization of the microspheres in BALB/c (H-2d) mice resulted in the production of high-titre anti-HBs antibodies (IgG1-type). The response was long lasting and was superior to that obtained using the same peptide adjuvanted with Freund's complete adjuvant. A T-cell memory response was detected 10 weeks after a booster immunization (approximately 35 weeks after initial immunization) as measured by in-vitro re-stimulation of splenocytes. This study illustrates the feasibility of a single dose vaccine for hepatitis B and is, to our knowledge, the first demonstration of a synthetic peptide immunogen inducing anti-native protein antibodies of comparable titre to those obtained with conventional vaccines for hepatitis B. The suitability of a synthetic peptide vaccine for hepatitis B is discussed.

Menjugate (Chiron)

Chiron has developed and launched Menjugate, a vaccine for the treatment for meningococcus C infections caused by the pathogen Neisseria meningitidis [177064]. In August 1999, Chiron filed with the UK MCA for a license to market Menjugate. The licence was granted in March 2000 [339082], [344773], [357897] and as of April 2000, a vaccination program was underway in the UK [362152]. Menjugate is indicated for children of 12 months and older, but Chiron was expecting approval in the US for infants younger than 12 months by the end of 2000. The company will also pursue mutual recognition in Europe [376204]. In August 2000, Chiron received marketing clearance for Menjugate from the Irish Medicines Board as a conjugate against meningococcal C disease [378353]. The vaccine employs CRM-conjugate technology, whereby a diphtheria toxoid is used as a carrier protein for the meningitis C-specific antigens. The vaccine is being developed for its potential to provide protection against meningitis in both adults and infants. In July 2000, Chiron entered into a comarketing and co-promotion agreement with Aventis Pasteur under which Aventis will assist Chiron in marketing and sales efforts for Menjugate in the UK [374760].

Tetracel (American Home Products)

American Home Products (AHP) is developing Tetracel as a vaccine for children (aged 12 to 18 months) against diphtheria, tetanus, pertussis and Haemophilus influenzae type B (Hib) [275146]. The components are contained in AHP's two currently marketed vaccines. ACEL-Immune contains diphtheria and tetanus toxoids with acellular pertussis vaccine adsorbed, and HibTITER contains the Haemophilus influenzae B conjugate vaccine (diphtheria CRM197 protein conjugate) [239655]. As of January 2000, Lehman Brothers predicted Tetracel to be approved in the US during 2000 [354434].

Panhandle PCR for cDNA: a rapid method for isolation of MLL fusion transcripts involving unknown partner genes

Identifying translocations of the MLL gene at chromosome band 11q23 is important for the characterization and treatment of leukemia. However, cytogenetic analysis does not always find the translocations and the many partner genes of MLL make molecular detection difficult. We developed cDNA panhandle PCR to identify der(11) transcripts regardless of the partner gene. By reverse transcribing first-strand cDNAs with oligonucleotides containing coding sequence from the 5' MLL breakpoint cluster region at the 5' ends and random hexamers at the 3' ends, known MLL sequence was attached to the unknown partner sequence. This enabled the formation of stem-loop templates with the fusion point of the chimeric transcript in the loop and the use of MLL primers in two-sided PCR. The assay was validated by detection of the known fusion transcript and the transcript from the normal MLL allele in the cell line MV4-11. cDNA panhandle PCR then was used to identify the fusion transcripts in two cases of treatment-related acute myeloid leukemia where the karyotypes were normal and the partner genes unknown. cDNA panhandle PCR revealed a fusion of MLL with AF-10 in one case and a fusion of MLL with ELL in the other. Alternatively spliced transcripts and exon scrambling were detectable by the method. Leukemias with normal karyotypes may contain cryptic translocations of MLL with a variety of partner genes. cDNA panhandle PCR is useful for identifying MLL translocations and determining unknown partner sequences in the fusion transcripts.

The new hospice compliance plan: defining and addressing risk areas. Part 3

The recently released OIG guidelines to ensure compliance with federal and state statutes, rules, and regulations, and private-payor health care program requirements provide a blueprint for developing such programs. This is the last of three installments that focus specifically on the 28 risk areas identified in the guidance and offer strategies for incorporating them in a hospice compliance program. The authors have organized the 28 risk areas under 9 topic domains to simplify the task of tackling the guidance. This article covers the areas of nursing home care, marketing, and Conditions of Participation.

Differential involvement of Na(+),K(+)-ATPase isozymes in preimplantation development of the mouse

Na(+),K(+)-ATPase plays an essential role in mammalian blastocoel formation (cavitation) by driving trans-epithelial sodium transport. Previously, the alpha1 and beta1 subunit isoforms of this enzyme were identified in preimplantation mouse embryos and were assumed to be responsible for this function. Here we show that mRNAs encoding an additional alpha subunit isoform (alpha3) and the remaining two beta subunit isoforms are also present in preimplantation embryos. Whereas alpha3 mRNA accumulates between the four-cell and the blastocyst stages and thus results from embryonic transcription, the same could not be demonstrated for beta2 and beta3 mRNAs. Immunoblot analyses confirmed that these subunits are present in cavitating embryos. Using confocal immunofluorescence microscopy we found that alpha1 and beta1 subunits are concentrated in the basolateral membranes of the trophectoderm while being equally distributed in plasma membranes of the inner cell mass. In contrast, alpha3, beta2, and beta3 subunits were not detected in plasma membranes. Our current assessment, therefore, is that as many as six isozymes of Na(+),K(+)-ATPase could be involved in preimplantation development although it is primarily the alpha1beta1 isozyme that is responsible for blastocoel formation. Our findings imply that the regulation of sodium transport within the preimplantation mouse embryo is more complex than had been appreciated.

The new hospice compliance plan: defining and addressing risk areas. Part 2

The Department of Health and Human Services' (HHS) Office of the Inspector General (OIG), has advised hospices and other health care providers to formulate effective controls to ensure compliance with federal and state statutes, rules, and regulations, and private-payor health care program requirements. This is the second of three installments that focus specifically on the 28 risk areas identified in the guidance and offer strategies for incorporating them in a hospice compliance program. This article covers the areas of Expensive Care, Documentation, Interdisciplinary Group, and Kickbacks.

Type I phosphatidylinositol 4-phosphate 5-kinase directly interacts with ADP-ribosylation factor 1 and is responsible for phosphatidylinositol 4,5-bisphosphate synthesis in the golgi compartment

Phosphatidylinositol (PtdIns) 4,5-bisphosphate is involved in many aspects of membrane traffic, but the regulation of its synthesis is only partially understood. Golgi membranes contain PI 4-kinase activity and a pool of phosphatidylinositol phosphate (PIP), which is further increased by ADP-ribosylation factor 1 (ARF1). COS7 cells were transfected with alpha and beta forms of PI 4-kinase, and only membranes from COS7 cells transfected with PI 4-kinase beta increased their content of PIP when incubated with ARF1. PtdIns(4, 5)P(2) content in Golgi membranes was nonexistent but could be increased to a small extent upon adding either cytosol or Type I or Type II PIP kinases. However, when ARF1 was present, PtdIns(4,5)P(2) levels increased dramatically when membranes were incubated in the presence of cytosol or Type I, but not Type II, PIP kinase. To examine whether ARF1 could directly activate Type I PIP 5-kinase, we used an in vitro assay consisting of phosphatidycholine-containing liposomes, ARF1, and PIP 5-kinase. ARF1 increased Type I PIP 5-kinase activity in a guanine nucleotide-dependent manner, identifying this enzyme as a direct effector for ARF1.

The new hospice compliance plan: defining and addressing risk areas

The Department of Health and Human Services' (HHS) Office of the Inspector General (OIG), has advised hospices and other health care providers to formulate effective controls to ensure compliance with federal and state statutes, rules, and regulations, and private-payor health care program requirements. The recently released guidelines provide a blueprint for developing such programs. This is the first of four installments that focus specifically on the 28 risk areas identified in the guidance and offer strategies for incorporating them in a hospice compliance program. The authors have organized the 28 risk areas under 9 topic domains to simplify the task of tackling the guidance. This article covers the first two areas: Admission/Certification/Recertification and Billing.

Detection of leukemia-associated MLL-GAS7 translocation early during chemotherapy with DNA topoisomerase II inhibitors

Leukemias with MLL gene translocations are a complication of primary cancer treatment with DNA topoisomerase II inhibitors. How early translocations appear during primary cancer treatment has not been investigated. We tracked the leukemic clone with an MLL gene translocation during neuroblastoma therapy in a child who developed acute myeloid leukemia. The karyotype of the leukemic clone showed del(11)(q23). We used panhandle PCR-based methods to isolate the breakpoint junction involving MLL and an unknown partner gene. Marrow DNA from neuroblastoma diagnosis and DNA and RNA from serial preleukemic marrows were examined for the translocation. The karyotypic del(11)(q23) was a cryptic t(11;17). GAS7, a growth arrest-specific gene at chromosome band 17p13, was the partner gene of MLL. Two different MLL-GAS7 fusion transcripts were expressed. The translocation was already detectable by 1.5 months after the start of neuroblastoma treatment. The translocation was not detectable in the marrow at neuroblastoma diagnosis or in peripheral blood lymphocyte DNAs of six normal subjects. GAS7 is a new partner gene of MLL in treatment-related acute myeloid leukemia. MLL gene translocations can be present early during anticancer treatment at low cumulative doses of DNA topoisomerase II inhibitors. Although MLL has many partner genes and most have not been characterized, panhandle PCR strategies afford new means for detecting MLL gene translocations early during therapy when the partner gene is unknown.

Expression and membrane assembly of a transmembrane region from Neu

Transmembrane domains of receptor tyrosine kinases are increasingly seen as key modulatory elements in signaling pathways. The present work addresses problems surrounding expression, isolation, secondary structure recovery, and assembly into membranes, of the relatively large quantities of transmembrane peptides needed to investigate these pathways by NMR spectroscopy. We demonstrate significant correspondence between SDS-PAGE behavior of such peptides and their (2)H NMR spectra in lipid bilayer membranes. A 50-residue peptide, Neu(exp), containing the transmembrane portion of the receptor tyrosine kinase, Neu, was designed for expression in Escherichia coli. The sequence also contained 11-12 amino acids from each side of the transmembrane domain. The common problem of low expressivity of transmembrane peptides was encountered-likely associated with membrane toxicity of the desired gene product. This difficulty was overcome by expressing the peptide as a TrpE fusion protein in a pATH vector to target expression products to inclusion bodies, and subsequently removing the TrpE portion by cyanogen bromide cleavage. Inclusion bodies offered the additional benefits of reduced proteolytic degradation and simplified purification. The presence of a hexa-His tag allowed excellent recovery of the final peptide, while permitting use of denaturing solvents and avoiding the need for HPLC with its attendant adsorption losses. Isolated expressed peptides were found to be pure, but existed as high oligomers rich in beta-structure as evidenced by CD spectroscopy and SDS-PAGE behavior. Dissolution in certain acidic organic solvents led to material with increased alpha-helix content, which behaved in detergent as mixtures of predominantly monomers and dimers-a situation often considered to exist in cell membranes. For purposes of NMR spectroscopy, peptide alanine residues were deuterated in high yield during expression. The same acidic organic solvents used to dissolve and dissociate expressed transmembrane peptides proved invaluable for their assembly into lipid bilayers. Analogous transmembrane peptides from the human receptor tyrosine kinase, ErbB-2, demonstrated related phenomena.

Subthalamic nucleus microinjections of 5-HT2 receptor antagonists suppress stereotypy in rats

The subthalamic nucleus (STN) is an important mediator of basal ganglia output. We studied the effects of STN microinjections of the serotonin-2 (5-HT2) antagonists clozapine, mesulergine and M100,907 on apomorphine-induced stereotypic activity in the rat. Each compound profoundly decreased the expression of stereotypic behavior, with particularly strong effects to reduce gnawing behavior. Because M100,907 does not have appreciable affinity for dopamine D1 and D2 receptors, and since all three agents are 5-HT2 antagonists, the current data suggest that basal ganglia output related to orofacial movements can be significantly modified by 5-HT2 receptors. The results suggest that antipsychotics with serotonergic properties may have direct actions on the STN that influence their potential to produce orofacial and other motor side effects.

Induction of cytotoxic T-cell responses following oral immunization with synthetic peptides encapsulated in PLG microparticles

CTL responses play a critical role in clearing viral infections. We have investigated the potential of poly(lactide-co-glycolide) (PLG) microparticles as an oral delivery system for peptides representing CTL epitopes from measles virus nucleoprotein. Oral administration of CTL epitopes encapsulated in 50:50 PLG microparticles, resulted in vivo priming of splenic peptide-specific CTL responses. However, the observed CTL lysis was low and cofeeding of encapsulated peptide with cholera toxin as a mucosal adjuvant did not result in any significant enhancement of the observed CTL responses. The pronounced immunostimulatory effect of microparticles, combined with their excellent tissue compatibility and biodegradability makes them a valuable delivery system for synthetic peptide immunogens. However, further work is needed to improve their efficiency via the oral route.

ADP ribosylation factor 1 mutants identify a phospholipase D effector region and reveal that phospholipase D participates in lysosomal secretion but is not sufficient for recruitment of coatomer I

The small GTP-binding protein, ADP-ribosylation factor 1 (ARF1) is essential for the formation of coatomer-coated vesicles from the Golgi and is also an activator of phospholipase D (PLD). Moreover, ARF1-regulated PLD is part of the signal-transduction pathway that can lead to secretion. In this study, substitution and deletion mutants of ARF1 were tested for their ability to activate PLD. These map the PLD effector region of ARF1 to the alpha2 helix, part of the beta2-strand and the N-terminal helix and its ensuing loop. ARF mutants with an increased or decreased ability to activate PLD showed similar characteristics when tested for their ability to stimulate secretion from HL60 cells. ARF1, deleted of the N-terminal 17 amino acid residues (Ndel17), did not support PLD activity or secretion, and neither did it inhibit the activity of wild-type myristoylated ARF1 (myrARF1). In contrast, Ndel17 effectively competed with wild-type myrARF1 to prevent coatomer binding to membranes. This appears to define a structural role for Ndel17, as it can bind a high-molecular mass complex in cytosol. In addition, ethanol has no effect on recruitment of coatomer to membrane. We conclude that the function of ARF-regulated PLD is in the signal-transduction pathway leading to secretion of lysosomal granules, and not as an essential component of ARF1-mediated coatomer binding.

Immune responses and protection obtained by oral immunization with rotavirus VP4 and VP7 DNA vaccines encapsulated in microparticles

Protective immune responses in mice were obtained after oral immunization with rotavirus DNA vaccines encapsulated in poly(lactide-co-glycolide) (PLG) microparticles. The DNA vaccines used encoded outer capsid proteins VP4 and VP7; proteins that are the basis for rotavirus serotyping and the generation of virus neutralizing antibodies. One dose of vaccine was given to BALB/c mice by oral gavage (75 microg DNA/mouse). Rotavirus-specific serum antibodies and intestinal IgA antibodies were detectable by 6 weeks postimmunization. After challenge with homologous murine rotavirus at 12 weeks postimmunization, fecal rotavirus antigen was reduced significantly in immunized mice compared with controls. Protective immunity also was generated by oral delivery of unencapsulated VP 7 DNA vaccine but to a lesser degree. These results demonstrate that the oral route is effective for generating protective immune responses with rotavirus DNA vaccines targeting neutralization antigens.

Tibial fracture during removal of a tibial intramedullary nail

SUMMARY

As tibial intramedullary nailing becomes the preferred treatment for tibial shaft fracture, removal of tibial nails will become more common. Removal of tibial intramedullary nails is not without complications, but a review of the literature found only one recent report of a fracture of the tibia during removal. A case report of a tibial fracture during removal of an Alta tibial nail is presented.

A Strategy for Improvement in Care at the End of Life: The VA Faculty Leaders Project

Given the commitment of the Veterans Health Administration (VA) to excellent, compassionate end-of-life and palliative care and the VA's extensive system of academic affiliations with the nation's medical schools, there may exist an opportunity to accelerate acceptance of state-of-the-art training for improved care for dying patients. Accordingly, the VA has initiated a project to develop strategies for implementation of benchmark curricula for end-of-life and palliative care. With the support of the Robert Wood Johnson Foundation, this initiative has been implemented in 30 internal medicine residency training programs affiliated with the VA nationally.

Spontaneous mutation, oxidative DNA damage, and the roles of base and nucleotide excision repair in the yeast Saccharomyces cerevisiae

The OGG1 gene of Saccharomyces cerevisiae encodes a DNA glycosylase that excises 7,8-dihydro-8-oxoguanine (8-OxoG). When compared to wild-type, ogg1 mutants show an increase in the frequency of GC to TA transversions, indicating a role for Ogg1 in the repair of 8-OxoG. Here we report an increased frequency of forward mutation to canavanine resistance in mutants defective in the nucleotide excision repair (NER) gene RAD14. This was not increased further in strains additionally defective in OGG1. However, when compared to strains solely defective in OGG1, ogg1radl4 mutants displayed an increase in spontaneous GC to TA transversions. Intriguingly, reversion of the lys1-1 ochre allele was not increased in rad14 mutants, suggesting that oxidative base damage may only represent a substrate for NER in certain regions of the genome. We also examined repair of oxidative DNA damage by transforming mutant strains with plasmid DNA treated with methylene blue plus visible light. Mutants defective in OGG1 showed no significant reduction in transformation efficiency compared with wild-type strains. In contrast, disruption of RAD14 reduced the efficiency of transformation, yet there was no further decrease in an ogg1rad14 mutant. This strongly supports a role for NER in the repair of oxidative base damage in yeast, and differs from similar experiments carried out in E. coli, where transformation efficiency is only reduced in mutants defective in both fpg and uvrA. Finally, the repair of Fpg-sensitive sites was examined at the MATalpha and HMLalpha mating type loci, and NER was found to play a role in their removal.

Epidermal growth factor receptor transmembrane domain: 2H NMR implications for orientation and motion in a bilayer environment

As part of a study of receptor tyrosine kinase behavior in membranes, we have collected extensive NMR data from three well-defined probe locations within the transmembrane region of the human EGF receptor. Spectra were obtained for selectively deuterated alanine residues in a series of peptides corresponding to the putative transmembrane domain (with short extramembranous extensions). Peptides were incorporated into fluid unsonicated liposomes of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) and POPC containing 33 mol % cholesterol to mimic common lipid composition of cell plasma membranes. The peptide concentration was in the range of 1-6 mol % relative to that of phospholipid. Data acquired at 35 degreesC have been analyzed quantitatively to determine their implications to receptor spatial orientation and dynamics. If it is presumed that the single transmembrane portion approximates an alpha-helix of 3.6 residues per turn, this helix was found to be tilted away from the membrane perpendicular, about which there was rapid axial diffusion. However, rotation about the peptide long axis was static on the NMR time scale of 10(-)4 s, and the peptide appeared to have a preferred direction(s) of lean. The results for this peptide, whose hydrophobic length is greater than the membrane hydrophobic thickness, were very similar between membranes of POPC and membranes of POPC containing 33 mol % cholesterol, despite considerable host matrix differences in thickness and order. Allowed values of peptide tilt occupied a narrow range: between 10 and 14 degrees in POPC and between 10 and 12 degrees in POPC/cholesterol. Although the existence of some preferred direction(s) of lean was demanded by the results, the direction of lean was not uniquely determined. We have interpreted these results, which were essentially unchanged at 65 degreesC, as reflecting the behavior of peptide monomers undergoing rapidly reversible peptide-peptide interactions. For transmembrane monomers, interference with rotation about the peptide long axis might be understood to arise from an energy benefit (in a tilted peptide) to prevention of particular amino acid side chains near the membrane surfaces from moving in and out of hydrophobic or hydrophilic environments. It will be desirable to test the conclusion of preferential lean of a monomeric receptor since such behavior could provide a mechanism for modulating monomer association with other species (i.e., signal transduction).

Protective immunity induced by oral immunization with a rotavirus DNA vaccine encapsulated in microparticles

DNA vaccines are usually given by intramuscular injection or by gene gun delivery of DNA-coated particles into the epidermis. Induction of mucosal immunity by targeting DNA vaccines to mucosal surfaces may offer advantages, and an oral vaccine could be effective for controlling infections of the gut mucosa. In a murine model, we obtained protective immune responses after oral immunization with a rotavirus VP6 DNA vaccine encapsulated in poly(lactide-coglycolide) (PLG) microparticles. One dose of vaccine given to BALB/c mice elicited both rotavirus-specific serum antibodies and intestinal immunoglobulin A (IgA). After challenge at 12 weeks postimmunization with homologous rotavirus, fecal rotavirus antigen was significantly reduced compared with controls. Earlier and higher fecal rotavirus-specific IgA responses were noted during the peak period of viral shedding, suggesting that protection was due to specific mucosal immune responses. The results that we obtained with PLG-encapsulated rotavirus VP6 DNA are the first to demonstrate protection against an infectious agent elicited after oral administration of a DNA vaccine.

Contributions of Na+/H+ exchanger isoforms to preimplantation development of the mouse

Previous work provided evidence of Na+/H+ exchanger activity in the apical domain of mouse trophectodermal plasma membranes that provides a route for entry of extracellular Na+ (Manejwala et al., 1989). This activity was hypothesized to contribute to the trans-trophectodermal Na+ flux that is required for blastocoel expansion. In the present work, we have used reverse transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemistry to identify members of the Na+/H+ exchanger (NHE) family that are likely to participate in this process. When cDNA preparations from ovulated oocytes and several stages of preimplantation development were tested with PCR primers specific for the NHE-1, -2, -3, and -4 isoforms of the exchanger, only amplicons representing the NHE-1 and NHE-3 isoforms were detected. The identity of these amplicons was confirmed by direct sequencing. NHE-1 mRNA is present in oocytes and in all preimplantation stages, increasing threefold on a per embryo basis between the 4-cell and blastocyst stages. NHE-3 mRNA, on the other hand, was only detected in oocytes. Immunocytochemical analysis of blastocysts revealed that NHE-1 is localized in the basolateral domain of the trophectoderm, whereas NHE-3 is localized in the apical domain, a situation like that in epithelia of adult organs. We conclude that NHE-3, an oogenetic product that persists into the blastocyst stage, is the Na+/H+ exchanger isoform most likely to be involved in blastocoel expansion.

Panhandle PCR: a technical advance to amplify MLL genomic translocation breakpoints

Translocations involving a breakpoint cluster region of the MLL gene at chromosome band 11q23 are the most common molecular abnormalities in acute leukemias of infants and acute leukemias related to chemotherapy with DNA topoisomerase II inhibitors. Molecular cloning of MLL genomic breakpoints by PCR has previously been difficult because MLL has many translocation partners and several breakpoints involve unknown partner genes. We review a new approach to MLL genomic breakpoint cloning called panhandle PCR. By adding an oligonucleotide sequence to the unknown 3' partner gene that is complementary to a known 5' MLL sequence, we have been able to generate a genomic template with an intrastrand loop for PCR schematically shaped like a pan with a handle. The intrastrand loop contains the translocation breakpoint and unknown partner DNA, while the handle contains the known 5' sequence from MLL and a complement to that sequence. Primers both derived from MLL are used to amplify the breakpoint by panhandle PCR. Panhandle PCR offers the advantage of having specificity for the strand of interest at both primer annealing sites without requiring specific primers for the many partner genes of MLL. Panhandle PCR is a straightforward method that represents a technical advance in MLL genomic breakpoint cloning.

Sequence-related behaviour of transmembrane domains from class I receptor tyrosine kinases

2H NMR spectroscopy and freeze-fracture electron microscopy were used to compare the transmembrane domains of two Class I protein receptor tyrosine kinases (the EGF receptor and Neu/erbB-2) regarding overall behaviour in fluid lipid bilayer membranes. The 34-residue peptide, EGFRtm, was synthesised to contain the 23 amino acid hydrophobic stretch (Ile622 to Met644) thought to span the membrane of the human EGF receptor, plus the first 10 amino acids (Arg645 to Thr654) of the cytoplasmic domain. Deuterium probes replaced selected 1H nuclei at sites corresponding to Ala623, Met644, and Val650. The 38-residue peptide, Neutm, was synthesised having the 21 residue hydrophobic stretch (Ile660 to Ile680) calculated to span the membrane in rat Neu/erbB-2, plus residues Lys681 to Thr691 of the contiguous cytoplasmic domain. Deuterium probes replaced selected 1H nuclei at Ala661, Leu667, and Val676. A third peptide, Neutm*, was also prepared, corresponding to the transmembrane domain of a constitutively-activating Neu/erbB-2 transformant in which Val664 is replaced by Glu: it was deuterated in a manner identical to Neutm. Peptides were studied by 2H NMR spectroscopy at 1 mol% and 6 mol% in unsonicated fluid bilayers of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) and in POPC containing 33 mol% cholesterol, over the range 12 degrees to 65 degreesC. Overall motion was found to be different for each of the three peptides under a given set of conditions. EGFRtm spectra were characteristic of axially symmetric motion in membranes of POPC alone, and in POPC/cholesterol at 35 degreesC and above. In contrast, spectra of the transmembrane peptides, Neutm and Neutm*, were characteristic of significantly axially asymmetric motion under all conditions studied (and regardless of sample preparation method). Addition of 33% cholesterol to membranes was accompanied by spectral changes consistent with increased formation of peptide dimers/oligomers in all cases. The transformant peptide, Neutm*, showed greater spectral evidence of immobilisation than did the wild type - probably reflecting a greater tendency to form large oligomers. Sequence-related details within the transmembrane domains of Class I receptor tyrosine kinases appear to exert important control over their associations within membranes. Freeze-fracture electron microscopy of the NMR samples demonstrated their liposomal nature. Peptide-related intramembranous particles (IMPs) were present which likely represent oligomers of the transmembrane peptide. IMP size and distribution were similar under a given set of conditions for all three peptides, suggesting that the differences seen by NMR spectroscopy reflect structures smaller than the 2 nm resolution limit of freeze-fracture EM and peptide relationships within its 20 nm accuracy of identifying lateral position.

t(11;22)(q23;q11.2) In acute myeloid leukemia of infant twins fuses MLL with hCDCrel, a cell division cycle gene in the genomic region of deletion in DiGeorge and velocardiofacial syndromes

We examined the MLL genomic translocation breakpoint in acute myeloid leukemia of infant twins. Southern blot analysis in both cases showed two identical MLL gene rearrangements indicating chromosomal translocation. The rearrangements were detectable in the second twin before signs of clinical disease and the intensity relative to the normal fragment indicated that the translocation was not constitutional. Fluorescence in situ hybridization with an MLL-specific probe and karyotype analyses suggested t(11;22)(q23;q11. 2) disrupting MLL. Known 5' sequence from MLL but unknown 3' sequence from chromosome band 22q11.2 formed the breakpoint junction on the der(11) chromosome. We used panhandle variant PCR to clone the translocation breakpoint. By ligating a single-stranded oligonucleotide that was homologous to known 5' MLL genomic sequence to the 5' ends of BamHI-digested DNA through a bridging oligonucleotide, we formed the stem-loop template for panhandle variant PCR which yielded products of 3.9 kb. The MLL genomic breakpoint was in intron 7. The sequence of the partner DNA from band 22q11.2 was identical to the hCDCrel (human cell division cycle related) gene that maps to the region commonly deleted in DiGeorge and velocardiofacial syndromes. Both MLL and hCDCrel contained homologous CT, TTTGTG, and GAA sequences within a few base pairs of their respective breakpoints, which may have been important in uniting these two genes by translocation. Reverse transcriptase-PCR amplified an in-frame fusion of MLL exon 7 to hCDCrel exon 3, indicating that an MLL-hCDCrel chimeric mRNA had been transcribed. Panhandle variant PCR is a powerful strategy for cloning translocation breakpoints where the partner gene is undetermined. This application of the method identified a region of chromosome band 22q11.2 involved in both leukemia and a constitutional disorder.

The EGF receptor transmembrane domain: 2H NMR study of peptide phosphorylation effects in a bilayer environment

Phosphorylation events are considered to be key control points in receptor tyrosine kinase function. We have used wide-line 2H NMR spectroscopy to look for physical effects of phosphorylating a threonine residue within the cytoplasmic domain of the human EGF receptor, as sensed at a distant site in the transmembrane portion. Modifications were made to Thr654 (a cytoplasmic residue suggested to be involved in regulation of EGF binding and of cytoplasmic domain function), and effects were sought at Ala623 (near the extracellular membrane surface but within the membrane-spanning region). The study was carried out on synthetic peptides corresponding to the EGF receptor transmembrane domain plus 10 or 11 residues of the cytoplasmic domain, assembled into lipid bilayer membranes. Three peptides were compared that differed only at Thr654. This residue was alternately: nonphosphorylated but left as a (-)-charged C-terminus (-Thr654COO-), nonphosphorylated and with a neighboring amidated glycine residue as the C-terminus (-Thr654GlyCONH2), or phosphorylated and with a neighboring amidated glycine residue as the C-terminus (-Thr654PO4-GlyCONH2). Bilayer membranes were composed of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) or 2:1 POPC/cholesterol, containing 6 mol % peptide relative to phospholipid. The deuterated site, Ala623, was intrinsically conformationally sensitive; yet spatial orientation and motional order of the probe location were found not to be obviously influenced by phosphorylation.

Comparison of the immunological and protective responses elicited by microencapsulated formulations of the F1 antigen from Yersinia pestis

Purified native F1 antigen from Yersinia pestis was used to assess controlled-release vaccine delivery systems in poly(lactide-co-glycolide) (PLG) microparticles and liposomes. Antigen encapsulated in PLG microparticles induced high serum titres when injected i.p. in mice: mucosal IgA was also detected. Mice immunized with F1 in Alhydrogel or PLGs were protected against subcutaneous challenge with Y. pestis. F1 antigen surface-labelled onto liposome vesicles stimulated high serum titres in Balb/c mice and also induced a mucosal response: F1-labelled liposomes protected mice against challenge with up to 1 x 10(5) organisms. These findings indicate that a significant immune response is induced by immunizing with F1 formulated in PLGs and liposomes and that protection was achieved after only one dose.

Triggering in the mucopolysaccharidoses

Upper limb dysfunction, particularly in relation to skeletal dysplasia and median nerve dysfunction, is well recognized in the mucopolysaccharidoses and mucolipidoses. This is of increasing importance because bone marrow transplantation has dramatically improved survival without changing the musculoskeletal manifestations. Triggering at the A1 pulley and more distally has been described in these patients. We report two such cases and four other patients who were noted to have triggering at the carpal tunnel in association with carpal tunnel syndrome. Five of the six patients consented to surgical intervention with favorable outcomes.

Teledermatology in the Highlands of Scotland

A pilot study of telemedicine consultations of 51 dermatology patients showed that the technology worked well, with the diagnosis being able to be made in most patients and over half of the patients being able to be dealt with through this medium only. It could therefore have a valuable screening role. However, many of the patients, in spite of the obvious advantage of an immediate consultant opinion, felt it would be more appropriately used as a review technique.