Epigenetic targeting in the mouse zygote marks DNA for later methylation: a mechanism for maternal effects in development

The transgenic sequences in the mouse line TKZ751 are demethylated on a DBA/2 inbred strain background but become highly methylated at postimplantation stages in offspring of a cross with a BALB/c female. In the reciprocal cross the transgene remains demethylated suggesting that imprinted BALB/c methylation modifiers or egg cytoplasmic factors are responsible for this striking maternal effect on de novo methylation. Reciprocal pronuclear transplantation experiments were carried out to distinguish between these mechanisms. The results indicate that a maternally-derived oocyte cytoplasmic factor from BALB/c marks the TKZ751 sequences at fertilization; this mark and postzygotic BALB/c modifiers are both required for de novo methylation of the target sequences at postimplantation stages. Using genetic linkage analyses we mapped the maternal effect to a locus on chromosome 17. Moreover, seven postzygotic modifier loci were identified that increase the postimplantation level of methylation. Analysis of interactions between the maternal and the postzygotic loci shows that both are needed for de novo methylation in the offspring. The combined experiments thus reveal a novel epigenetic marking process at fertilization which targets DNA for later methylation in the foetus. The most significant consequence is that the genotype of the mother can influence the epigenotype of the offspring by this marking process. A number of parental and imprinting effects may be explained by this epigenetic marking.

Property rights and privacy principles

Healthcare consumers own their medical information. As paper medical folders become digital, protection of this private and confidential information falls to information specialists rather than the traditional care givers. On the basis of a nationwide market assessment study, the authors identify the key issues regarding protecting this personal digital property and outline the federal requirements stemming from the Health Insurance Portability and Accountability Act (HIPAA). Consumer informed consent over the use of specific medical data is a basic requirement, and is a concept supported by physicians and care givers who rely on consent to approve surgeries and treatment. The article concludes with a solution outline that places the patient in control of his or her personal information, meets security and privacy concerns, and facilitates the critical exchange of patient information among care givers.

A dominant modifier of transgene methylation is mapped by QTL analysis to mouse chromosome 13

The single-copy hepatitis B virus transgene in the E36 transgenic mouse strain undergoes methylation changes in a parent-of-origin, tissue, and strain-specific fashion. In a C57BL/6 background, the paternally transmitted transgene is methylated in 30% of cells, whereas it is methylated in more than 80% of cells in (BALB/c x C57BL/6) F1 mice. We established previously that several genetic factors were likely to contribute to the transgene methylation profile, some with demethylating and some with de novo methylating activities. Using quantitative trait loci (QTL) mapping, we have now localized one major modifier locus on chromosome 13 (Mod13), which explains a 30% increase in the methylation level of this transgene with no effect on the flanking endogenous sequences. No other QTL could be identified, except for a demethylating activity of low significance located on chromosome 12. Recombinant inbred mice containing a BALB/c allele of Mod13 were then used to show that the presence of Mod13 is sufficient to induce de novo methylation. A segregation between de novo methylation and repression of transgene expression was uncovered, suggesting that this genetic system is also useful for the identification of factors that interpret methylation patterns in the genome.

Maternal methylation imprints on human chromosome 15 are established during or after fertilization

Prader-Willi syndrome (PWS) is a neurogenetic disorder that results from the lack of transcripts expressed from the paternal copy of the imprinted chromosomal region 15q11-q13 (refs. 1,2). In some patients, this is associated with a deletion of the SNURF-SNRPN exon 1 region inherited from the paternal grandmother and the presence of a maternal imprint on the paternal chromosome. Assuming that imprints are reset in the germ line, we and others have suggested that this region constitutes part of the 15q imprinting center (IC) and is important for the maternal to paternal imprint switch in the male germ line. Here we report that sperm DNA from two males with an IC deletion had a normal paternal methylation pattern along 15q11-q13. Similar findings were made in a mouse model. Our results indicate that the incorrect maternal methylation imprint in IC deletion patients is established de novo after fertilization. Moreover, we found that CpG-rich regions in SNURF-SNRPN and NDN, which in somatic tissues are methylated on the maternal allele, are hypomethylated in unfertilized human oocytes. Our results indicate that the normal maternal methylation imprints in 15q11-q13 also are established during or after fertilization.

Early revisit, hospitalization, or death among older persons discharged from the ED

The purpose of this study to determine predictors of revisit, hospital admission, or death among older patients discharged from the emergency department (ED). We performed a prospective study of patients aged 65 or older in an urban ED. The primary outcomes were ED revisit, hospital admission, or death 30 or 90 days after discharge from an index ED visit. Of the 463 eligible patients, 75 (16%) experienced ED revisit, hospitalization, or death within 30 days, and 125 (27%) within 90 days. In multivariate proportional hazards models, physical functioning and mental health in the lowest tertile, and lack of supplemental insurance predicted revisit, hospitalization, or death within 30 days after ED discharge. Poor physical functioning, missing mini-mental state examination, comorbidity, and ambulance transport to the initial ED visit predicted 90-day outcome. Problems with physical functioning, mental health and supplemental insurance are potentially remediable precursors of early morbidity among older patients after ED discharge. Future research should examine whether addressing these issues among the elderly population will lessen ED return visits, hospitalization, and mortality.

Designing families and solid citizens: the dialectic of modernity and the Matrimonial Causes Bill, 1959

Policy-makers in the 1940s and 50s were intent on designing families which would produce solid citizens to engage in nation building. Historians offamilism treat it as an expression of modernism: a unifying, oppressive discourse now to be countered by the destabilising project of postmodernism. But this is not the whole story, for it omits the dialectical essence of 'the modern', which promises both 'progress' through technical rationality and individual achievement/self fulfilment. The other side of the dialectic has been avoided by dismissing individualism as a process of interpellation closely tied to the interests of technocratic elites. Out of the discontinuities within modernism there emerged opportunities for agency, the chance for people to make their own lives. The public controversy over the Matrimonial Causes Bill, 1959-at the height of what we are encouraged to think of as the familist decade-is explored as one instance.

Genomic imprinting: parental influence on the genome

Genomic imprinting affects several dozen mammalian genes and results in the expression of those genes from only one of the two parental chromosomes. This is brought about by epigenetic instructions--imprints--that are laid down in the parental germ cells. Imprinting is a particularly important genetic mechanism in mammals, and is thought to influence the transfer of nutrients to the fetus and the newborn from the mother. Consistent with this view is the fact that imprinted genes tend to affect growth in the womb and behaviour after birth. Aberrant imprinting disturbs development and is the cause of various disease syndromes. The study of imprinting also provides new insights into epigenetic gene modification during development.

Methylation profiles of DXPas34 during the onset of X-inactivation

X chromosome inactivation is controlled by the cis-acting X-inactivation centre (Xic). In addition to initiating inactivation, Xic, which includes the XIST: gene, is involved in both a counting process that senses the number of X chromosomes and the choice of X chromosome to inactivate. Controlling elements lying 3' to XIST: include the DXPas34 locus. Deletion of DXPas34 in undifferentiated embryonic stem (ES) cells eliminates expression of both XIST: and the antisense transcript TSIX:, thought to initiate from a CpG island lying close to, but telomeric to, the DXPas34 locus itself. Deletion of DXPas34 leads to non-random inactivation on ES cell differentiation and disrupts imprinted X-inactivation in vivo. In order to investigate the role of methylation at DXPas34 in the initial steps of X-inactivation, we studied its methylation status during pre- and post-implantation embryonic development and ES cell differentiation, using the bisulphite sequencing technique. Analysis of the methylation status of both the DXPas34 locus and the associated downstream CpG island shows that extensive hypermethylation of the DXPas34 locus is a relatively late event in differentiation and embryogenesis. We conclude that methylation of DXPas34 cannot be the X chromosome imprint, nor can it be involved in the parent-of-origin effects associated with deletion of the DXPas34 locus and the neighbouring CpG island.

A loss of function mutant of the presenilin homologue SEL-12 undergoes aberrant endoproteolysis in Caenorhabditis elegans and increases abeta 42 generation in human cells

The familial Alzheimer's disease-associated presenilins (PSs) occur as a dimeric complex of proteolytically generated fragments, which functionally supports endoproteolysis of Notch and the beta-amyloid precursor protein (betaAPP). A homologous gene, sel-12, has been identified in Caenorhabditis elegans. We now demonstrate that wild-type (wt) SEL-12 undergoes endoproteolytic cleavage in C. elegans similar to the PSs in human tissue. In contrast, SEL-12 C60S protein expressed from the sel-12(ar131) allele is miscleaved in C. elegans, resulting in a larger mutant N-terminal fragment. Neither SEL-12 wt nor C60S undergo endoproteolytic processing upon expression in human cells, suggesting that SEL-12 is cleaved by a C. elegans-specific endoproteolytic activity. The loss of function of sel-12 in C. elegans is not associated with a dominant negative activity in human cells, because SEL-12 C60S and the corresponding PS1 C92S mutation do not interfere with Notch1 cleavage. Moreover, both mutant variants increase the aberrant production of the highly amyloidogenic 42-amino acid version of amyloid beta-peptide similar to familial Alzheimer's disease-associated human PS mutants. Our data therefore demonstrate that the C60S mutation in SEL-12 is associated with aberrant endoproteolysis and a loss of function in C. elegans, whereas a gain of misfunction is observed upon expression in human cells.

Sequence and functional comparison in the Beckwith-Wiedemann region: implications for a novel imprinting centre and extended imprinting

The clustered organization of most imprinted genes in mammals suggests coordinated genetic and epigenetic control mechanisms. Comparisons between human and mouse will help in elucidating these mechanisms by identifying structural and functional similarities. Previously we reported on such a comparison in the central part of the mouse imprinting cluster on distal chromosome 7 with the homologous Beckwith-Wiedemann syndrome (BWS) gene cluster on human chromosome 11p15.5. Here we focus on the adjacent sequences of 0.5 Mb including the KCNQ1/Kcnq1 and CDKN1C/Cdkn1c genes, which are implicated in BWS, and on one of the proposed boundary regions of the imprinting cluster. As in the previously analysed central region, this part of the cluster exhibits a highly conserved arrangement and structure of genes. The most striking similarity is found in the 3' part of the KCNQ1/Kcnq1 genes in large stretches of mostly non-coding sequences. The conserved region includes the recently identified KCNQ1OT1/Kcnq1ot1 antisense transcripts, flanked by a strikingly conserved cluster of LINE/Line elements and a CpG island which we show to carry a maternal germline methylation imprint. This region is likely to be the proposed second imprinting centre (IC2) in the BWS cluster. We also identified several novel genes inside and outside the previously proposed boundaries of the imprinting cluster. One of the genes outside the cluster, Obph1, is imprinted in mouse placenta indicating that at least in extra-embryonic tissues the imprinting cluster extends into a larger domain.

Histone H4 acetylation of euchromatin and heterochromatin is cell cycle dependent and correlated with replication rather than with transcription

Reversible acetylation of nucleosomal histones H3 and H4 generally is believed to be correlated with potential transcriptional activity of eukaryotic chromatin domains. Here, we report that the extent of H4 acetylation within euchromatin and heterochromatic domains is linked with DNA replication rather than with transcriptional activity, whereas H3 acetylation remains fairly constant throughout the cell cycle. Compared with euchromatin, plant nucleolus organizers were more strongly acetylated at H4 during mitosis but less acetylated during S phase, when the nucleolus appeared to be (at least transiently) devoid of nucleosomes. Deposition-related acetylation of lysines 5 and 12 of H4 seems to be conserved in animals and plants and extended to K16 in plants. A possibly species-specific above-average acetylation at lysines 9/18 and 14 of H3 appeared in 4',6-diamidino-2-phenylindole (DAPI)-stained heterochromatin fractions. These results were obtained by combining immunodetection of all acetylatable isoforms of H3 and H4 on mitotic chromosomes and nuclei in G1, early S, mid-S, late S, and G2 phases of the field bean with identification of specific chromatin domains by fluorescence in situ hybridization or DAPI staining. In addition, the histone acetylation patterns of distinct domains were compared with their replication and transcription patterns.

Histone H4 acetylation of euchromatin and heterochromatin is cell cycle dependent and correlated with replication rather than with transcription

Reversible acetylation of nucleosomal histones H3 and H4 generally is believed to be correlated with potential transcriptional activity of eukaryotic chromatin domains. Here, we report that the extent of H4 acetylation within euchromatin and heterochromatic domains is linked with DNA replication rather than with transcriptional activity, whereas H3 acetylation remains fairly constant throughout the cell cycle. Compared with euchromatin, plant nucleolus organizers were more strongly acetylated at H4 during mitosis but less acetylated during S phase, when the nucleolus appeared to be (at least transiently) devoid of nucleosomes. Deposition-related acetylation of lysines 5 and 12 of H4 seems to be conserved in animals and plants and extended to K16 in plants. A possibly species-specific above-average acetylation at lysines 9/18 and 14 of H3 appeared in 4',6-diamidino-2-phenylindole (DAPI)-stained heterochromatin fractions. These results were obtained by combining immunodetection of all acetylatable isoforms of H3 and H4 on mitotic chromosomes and nuclei in G1, early S, mid-S, late S, and G2 phases of the field bean with identification of specific chromatin domains by fluorescence in situ hybridization or DAPI staining. In addition, the histone acetylation patterns of distinct domains were compared with their replication and transcription patterns.

Maturation and pro-peptide cleavage of beta-secretase

Amyloid beta-peptide is generated by two sequential proteolytic cleavages mediated by beta-secretase (BACE) and gamma-secretase. BACE was recently identified as a membrane-associated aspartyl protease. We have now analyzed the maturation and pro-peptide cleavage of BACE. Pulse-chase experiments revealed that BACE is post-translationally modified during transport to the cell surface, which can be monitored by a significant increase in the molecular mass. The increase in molecular mass is caused by complex N-glycosylation. Treatment with tunicamycin and N-glycosidase F led to a BACE derivative with a molecular weight corresponding to an unmodified version. In contrast, the mature form of BACE was resistant to endoglycosidase H treatment. The cytoplasmic tail of BACE was required for efficient maturation and trafficking through the Golgi; a BACE variant lacking the cytoplasmic tail undergoes inefficient maturation. In contrast a soluble BACE variant that does not contain a membrane anchor matured more rapidly than full-length BACE. Pro-BACE was predominantly located within the endoplasmic reticulum. Pro-peptide cleavage occurred immediately before full maturation and trafficking through the Golgi.

Brain expression of presenilins in sporadic and early-onset, familial Alzheimer's disease

BACKGROUND

Mutations in the presenilin proteins cause early-onset, familial Alzheimer's disease (FAD).

MATERIALS AND METHODS

We characterized the cellular localization and endoproteolysis of presenilin 2 (PS2) and presenilin 1 (PS1) in brains from 25 individuals with presenilin-mutations causing FAD, as well as neurologically normal individuals and individuals with sporadic Alzheimer's disease (AD).

RESULTS

Amino-terminal antibodies to both presenilins predominantly decorated large neurons. Regional differences between the broad distributions of the two presenilins were greatest in the cerebellum, where most Purkinje cells showed high levels of only PS2 immunoreactivity. PS2 endoproteolysis in brain yielded multiple amino-terminal fragments similar in size to the PS1 amino-terminal fragments detected in brain. In addition, two different PS2 amino-terminal antibodies also detected a prominent 42 kDa band that may represent a novel PS2 form in human brain. Similar to PS1 findings, neither amino-terminal nor antiloop PS2 antibodies revealed substantial full-length PS2 in brain. Immunocytochemical examination of brains from individuals with the N141I PS2 mutation or eight different PS1 mutations, spanning the molecule from the second transmembrane domain to the large cytoplasmic loop domain, revealed immunodecoration of no senile plaques and only neurofibrillary tangles in the M139I PS1 mutation stained with PS1 antibodies.

CONCLUSIONS

Overall presenilin expression and the relative abundance of full-length and amino-terminal fragments in presenilin FAD cases were similar to control cases and sporadic AD cases. Thus, accumulation of full-length protein or other gross mismetabolism of neither PS2 nor PS1 is a consequence of the FAD mutations examined.

A home program of rehabilitation for moderately severe traumatic brain injury patients. The DVHIP Study Group

We have recently reported the results of a prospective controlled randomized trial comparing home versus inpatient cognitive rehabilitation for patients with moderate to severe head injury. That study showed no overall difference in outcomes between the two groups.(1) In this article, we provide further details of the home program arm of the study. All patients in the home program received medical treatment as needed, a multidisciplinary in-hospital evaluation, and TBI counseling before entering the eight-week home program, which then included guidance on home activities, as well as weekly telephone calls from a psychiatric nurse.

Characterization of reutericyclin produced by Lactobacillus reuteri LTH2584

Lactobacillus reuteri LTH2584 exhibits antimicrobial activity that can be attributed neither to bacteriocins nor to the production of reuterin or organic acids. We have purified the active compound, named reutericyclin, to homogeneity and characterized its antimicrobial activity. Reutericyclin exhibited a broad inhibitory spectrum including Lactobacillus spp., Bacillus subtilis, B. cereus, Enterococcus faecalis, Staphylococcus aureus, and Listeria innocua. It did not affect the growth of gram-negative bacteria; however, the growth of lipopolysaccharide mutant strains of Escherichia coli was inhibited. Reutericyclin exhibited a bactericidal mode of action against Lactobacillus sanfranciscensis, Staphylococcus aureus, and B. subtilis and triggered the lysis of cells of L. sanfranciscensis in a dose-dependent manner. Germination of spores of B. subtilis was inhibited, but the spores remained unaffected under conditions that do not permit germination. The fatty acid supply of the growth media had a strong effect on reutericyclin production and its distribution between producer cells and the culture supernatant. Reutericyclin was purified from cell extracts and culture supernatant of L. reuteri LTH2584 cultures grown in mMRS by solvent extraction, gel filtration, RP-C(8) chromatography, and anion-exchange chromatography, followed by rechromatography by reversed-phase high-pressure liquid chromatography. Reutericyclin was characterized as a negatively charged, highly hydrophobic molecule with a molecular mass of 349 Da. Structural characterization (A. Höltzel, M. G. Gänzle, G. J. Nicholson, W. P. Hammes, and G. Jung, Angew. Chem. Int. Ed. 39:2766-2768, 2000) revealed that reutericyclin is a novel tetramic acid derivative. The inhibitory activity of culture supernatant of L. reuteri LTH2584 corresponded to that of purified as well as synthetic reutericyclin.

Phosphorylation of the beta-amyloid precursor protein at the cell surface by ectocasein kinases 1 and 2

The beta-amyloid precursor protein (betaAPP) is one of the rare proteins known to be phosphorylated within its ectodomain. We have shown previously that betaAPP can be phosphorylated within secretory vesicles and at the cell surface (Walter, J., Capell, A., Hung, A. Y. , Langen, H., Schnölzer, M., Thinakaran, G., Sisodia, S. S., Selkoe, D. J., and Haass, C. (1997) J. Biol. Chem. 272, 1896-1903). We have now specifically characterized the phosphorylation of cell surface-located betaAPP and identified two ectoprotein kinases that phosphorylate betaAPP at the outer face of the plasma membrane. By using selective protein kinase inhibitors and by investigating the usage of ATP and GTP as cosubstrates, we demonstrate that membrane-bound betaAPP as well as secreted forms of betaAPP can be phosphorylated by casein kinase (CK) 1- and CK2-like ectoprotein kinases. The ectodomain of betaAPP was also phosphorylated by purified CK1 and CK2 in vitro, but not by protein kinases A and C. Phosphorylation of betaAPP by ectoprotein kinases and by purified CK1 and CK2 occurred within an acidic domain in the N-terminal half of the protein. Heparin strongly inhibited the phosphorylation of cell-surface betaAPP by ecto-CK1 and ecto-CK2, indicating a regulatory role of this extracellular matrix component in betaAPP phosphorylation.

Rad51 accumulation at sites of DNA damage and in postreplicative chromatin

Rad51, a eukaryotic RecA homologue, plays a central role in homologous recombinational repair of DNA double-strand breaks (DSBs) in yeast and is conserved from yeast to human. Rad51 shows punctuate nuclear localization in human cells, called Rad51 foci, typically during the S phase (Tashiro, S., N. Kotomura, A. Shinohara, K. Tanaka, K. Ueda, and N. Kamada. 1996. Oncogene. 12:2165-2170). However, the topological relationships that exist in human S phase nuclei between Rad51 foci and damaged chromatin have not been studied thus far. Here, we report on ultraviolet microirradiation experiments of small nuclear areas and on whole cell ultraviolet C (UVC) irradiation experiments performed with a human fibroblast cell line. Before UV irradiation, nuclear DNA was sensitized by the incorporation of halogenated thymidine analogues. These experiments demonstrate the redistribution of Rad51 to the selectively damaged, labeled chromatin. Rad51 recruitment takes place from Rad51 foci scattered throughout the nucleus of nonirradiated cells in S phase. We also demonstrate the preferential association of Rad51 foci with postreplicative chromatin in contrast to replicating chromatin using a double labeling procedure with halogenated thymidine analogues. This finding supports a role of Rad51 in recombinational repair processes of DNA damage present in postreplicative chromatin.

Sequence conservation and variability of imprinting in the Beckwith-Wiedemann syndrome gene cluster in human and mouse

In human and mouse most imprinted genes are arranged in chromosomal clusters. This linked organization suggests coordinated mechanisms controlling imprinted expression. We have sequenced 250 kb in the centre of the mouse imprinting cluster on distal chromosome 7 and compared it with the orthologous Beckwith-Wiedemann gene cluster on human chromosome 11p15.5. This first comparative imprinting cluster analysis revealed a high structural and functional conservation of the six orthologous genes identified. However, several striking differences were also discovered. First, compared with the mouse the human sequence is approximately 40% longer, mostly due to insertions of two large repetitive clusters. One of these clusters encompasses an additional gene coding for a homologue of the ribosomal protein L26. Second, pronounced blocks of unique direct repeats characteristic of imprinted genes were only found in the human sequence. Third, two of the orthologous gene pairs Tssc4/TSSC4 and Ltrpc5/LTRPC5 showed apparent differences in imprinting between human and mouse, whereas others like Tssc6/TSSC6 were not imprinted in either organism. Together these results suggest a significant functional and structural variability in the centre of the imprinting cluster. Some genes escape imprinting in both organisms whereas others exhibit tissue- and species-specific imprinting. Hence the control of imprinting in the cluster appears to be a highly dynamic process under fast evolutionary adaptation. Intriguingly, whereas imprinted genes within the cluster contain CpG islands the non-imprinted Ltrpc5 and Tssc6/TSSC6 do not. This and additional comparisons with other imprinted and non-imprinted regions suggest that CpG islands are key features of imprinted domains.

Igf2 imprinting in development and disease

Igf2 is one of the first imprinted genes discovered and occupies a centre stage in the study of imprinting. This is because it has dramatic effects on the control of fetal growth, it is involved in growth disorders and in cancer, it interacts with products of other imprinted genes, and its imprinting status is under complex regulation in a cluster of tightly linked imprinted genes. Here we review briefly the key features of Igf2 imprinting in normal development and in disease, and hope to show what a fascinating subject of study this gene and its biology provides.

Genetics of atopy in a mouse model: polymorphism of the IL-5 receptor alpha chain

To study the genetics of atopy systematically we established a mouse model that provides the general phenotype of atopy: the early response characteristic of IgE-dependent eczema or atopic dermatitis, and the diagnostic test of atopy, the skin-prick test. Using an immediate cutaneous hypersensitivity test (ICHS) against birch pollen extract we could classify A/J and C57BL/6 (B6) inbred mouse strains respectively as high responder and low responders. The F1 hybrids were found to be high responders with incomplete penetrance. Backcrossing F1 mice to the low responder B6 strain yielded three classes of responders, high, intermediate, and low. A genome-wide microsatellite screen of the backcross progeny disclosed suggestive linkage to a microsatellite marker on chromosome 6 close to the locus of the IL-5 receptor alpha chain. Its allelic variation in A/J and B6 strains was investigated and two major differences were detected. Firstly, a nucleotide exchange in the 5' untranslated region of B6 mRNA resulted in increased transcription/translation of a reporter construct. Higher expression of the receptor on the cell surface would be expected to favor an allergic immune response. Secondly, the two alleles are differentially spliced so as to yield two soluble isoforms in A/J mice versus one in B6 mice. Higher expression of soluble IL-5R would be expected to reduce the level of allergy through capture of IL-5. Thus both findings conform to the expectation based on susceptibility to atopy and thus identify the IL-5R alpha chain as a likely contributor to the genetics of atopy.

Cognitive rehabilitation for traumatic brain injury: A randomized trial. Defense and Veterans Head Injury Program (DVHIP) Study Group

CONTEXT

Traumatic brain injury (TBI) is a principal cause of death and disability in young adults. Rehabilitation for TBI has not received the same level of scientific scrutiny for efficacy and cost-efficiency that is expected in other medical fields.

OBJECTIVE

To evaluate the efficacy of inpatient cognitive rehabilitation for patients with TBI.

DESIGN AND SETTING

Single-center, parallel-group, randomized trial conducted from January 1992 through February 1997 at a US military medical referral center.

PATIENTS

One hundred twenty active-duty military personnel who had sustained a moderate-to-severe closed head injury, manifested by a Glasgow Coma Scale score of 13 or less, or posttraumatic amnesia lasting at least 24 hours, or focal cerebral contusion or hemorrhage on computed tomography or magnetic resonance imaging.

INTERVENTIONS

Patients were randomly assigned to an intensive, standardized, 8-week, in-hospital cognitive rehabilitation program (n=67) or a limited home rehabilitation program with weekly telephone support from a psychiatric nurse (n=53).

MAIN OUTCOME MEASURES

Return to gainful employment and fitness for military duty at 1-year follow-up, compared by intervention group.

RESULTS

At 1-year follow-up, there was no significant difference between patients who had received the intensive in-hospital cognitive rehabilitation program vs the limited home rehabilitation program in return to employment (90% vs 94%, respectively; P=.51; difference, 4% [95% confidence interval ¿CI¿, -5% to 14%]) or fitness for duty (73% vs 66%, respectively; P=. 43; difference, 7% [95% CI, -10% to 24%]). There also were no significant differences in cognitive, behavioral, or quality-of-life measures. In a post-hoc subset analysis of patients who were unconscious for more than 1 hour (n = 75) following TBI, the in-hospital group had a greater return-to-duty rate (80% vs 58%; P=. 05).

CONCLUSIONS

In this study, the overall benefit of in-hospital cognitive rehabilitation for patients with moderate-to-severe TBI was similar to that of home rehabilitation. These findings emphasize the importance of conducting randomized trials to evaluate TBI rehabilitation interventions. JAMA. 2000;283:3075-3081

Separation of presenilin function in amyloid beta-peptide generation and endoproteolysis of Notch

Most of the genetically inherited Alzheimer's disease cases are caused by mutations in the presenilin genes, PS1 and PS2. PS mutations result in the enhanced production of the highly amyloidogenic 42/43 amino acid variant of amyloid beta-peptide (Abeta). We have introduced arbitrary mutations at position 286 of PS1, where a naturally occurring PS1 mutation has been described (L286V). Introduction of charged amino acids (L286E or L286R) resulted in an increase of Abeta42/43 production, which reached almost twice the level of the naturally occurring PS1 mutation. Although pathological Abeta production was increased, endoproteolysis of Notch and nuclear transport of its cytoplasmic domain was significantly inhibited. These results demonstrate that the biological function of PS proteins in the endoproteolysis of beta-amyloid precursor protein and Notch can be separated.