Past is prologue: The role of memory retrieval in young children's episodic prospection.

Prior research has revealed a strong link between the ability to remember one's past (i.e., episodic memory) and the ability to envision one's future (i.e., episodic prospection). Indeed, the past holds valuable learning experiences that can inform future choices and plans. Although these abilities both emerge during preschool years, there exist few theoretical accounts of how memory processes might support developmental improvements in prospection abilities. We developed a novel paradigm to determine whether young children (3 and 4 years of age) use past knowledge to inform future choices. Experiment 1 revealed that children find it more difficult to retrieve relevant information from their past when they envision the future versus reflect on the past. Experiment 2 facilitated children's access to past event components and, thereby, eased retrieval of relevant components from memory for future event construction. We discuss results in light of recent proposals on the development of episodic prospection.

From temporal updating to temporal reasoning: Developments in young children's temporal representations.

Evidence from our research on young children's temporal understanding supports Hoerl & McCormack's view that young children rely on a temporal updating system to change representations over time. We propose that the shift from temporal updating to temporal reasoning is enabled by children's expanding representations of event sequences, along with developments in language, memory, and other cognitive competencies.

Children's understanding of yesterday and tomorrow.

A picture-sentence matching task was used to investigate children's understanding of yesterday and tomorrow. In Experiment 1, 3- to 5-year-olds viewed two pictures of an object with a visible change of state (e.g., a carved pumpkin and an intact pumpkin) while listening to sentences referring to past or future actions ("I carved the pumpkin yesterday" or "I'm gonna carve the pumpkin tomorrow") and selected the matching picture. Children performed better with past tense sentences than with future tense sentences, and including tomorrow in future tense sentences increased accuracy. In the next two experiments, 4- and 5-year-olds (Experiment 2) and adults (Experiment 3) completed the same task but with sentences containing conflicting temporal information ("I carved the pumpkin tomorrow"). Children tended to select pictures depicting the outcome of actions regardless of tense or temporal adverb, whereas adults' judgments were based on temporal adverbs. In Experiment 4, 3- to 5-year-olds completed tasks requiring either forward or backward temporal reasoning about sentences referring to before, after, yesterday, today, and tomorrow. Across sentence types, forward temporal reasoning was easier for children than backward temporal reasoning. Altogether, results indicated that children understand yesterday better than tomorrow due to the increased cognitive demands involved in reasoning about future events.

The Human 343delT HSPB5 Chaperone Associated with Early-onset Skeletal Myopathy Causes Defects in Protein Solubility.

Mutations of HSPB5 (also known as CRYAB or αB-crystallin), a bona fide heat shock protein and molecular chaperone encoded by the HSPB5 (crystallin, alpha B) gene, are linked to multisystem disorders featuring variable combinations of cataracts, cardiomyopathy, and skeletal myopathy. This study aimed to investigate the pathological mechanisms involved in an early-onset myofibrillar myopathy manifesting in a child harboring a homozygous recessive mutation in HSPB5, 343delT. To study HSPB5 343delT protein dynamics, we utilize model cell culture systems including induced pluripotent stem cells derived from the 343delT patient (343delT/343delT) along with isogenic, heterozygous, gene-corrected control cells (WT KI/343delT) and BHK21 cells, a cell line lacking endogenous HSPB5 expression. 343delT/343delT and WT KI/343delT-induced pluripotent stem cell-derived skeletal myotubes and cardiomyocytes did not express detectable levels of 343delT protein, contributable to the extreme insolubility of the mutant protein. Overexpression of HSPB5 343delT resulted in insoluble mutant protein aggregates and induction of a cellular stress response. Co-expression of 343delT with WT prevented visible aggregation of 343delT and improved its solubility. Additionally, in vitro refolding of 343delT in the presence of WT rescued its solubility. We demonstrate an interaction between WT and 343delT both in vitro and within cells. These data support a loss-of-function model for the myopathy observed in the patient because the insoluble mutant would be unavailable to perform normal functions of HSPB5, although additional gain-of-function effects of the mutant protein cannot be excluded. Additionally, our data highlight the solubilization of 343delT by WT, concordant with the recessive inheritance of the disease and absence of symptoms in carrier individuals.

Mucopolysaccharidosis-like phenotype in feline Sandhoff disease and partial correction after AAV gene therapy.

Sandhoff disease (SD) is a fatal neurodegenerative disease caused by a mutation in the enzyme ß-N-acetylhexosaminidase. Children with infantile onset SD develop seizures, loss of motor tone and swallowing problems, eventually reaching a vegetative state with death typically by 4years of age. Other symptoms include vertebral gibbus and cardiac abnormalities strikingly similar to those of the mucopolysaccharidoses. Isolated fibroblasts from SD patients have impaired catabolism of glycosaminoglycans (GAGs). To evaluate mucopolysaccharidosis-like features of the feline SD model, we utilized radiography, MRI, echocardiography, histopathology and GAG quantification of both central nervous system and peripheral tissues/fluids. The feline SD model exhibits cardiac valvular and structural abnormalities, skeletal changes and spinal cord compression that are consistent with accumulation of GAGs, but are much less prominent than the severe neurologic disease that defines the humane endpoint (4.5±0.5months). Sixteen weeks after intracranial AAV gene therapy, GAG storage was cleared in the SD cat cerebral cortex and liver, but not in the heart, lung, skeletal muscle, kidney, spleen, pancreas, small intestine, skin, or urine. GAG storage worsens with time and therefore may become a significant source of pathology in humans whose lives are substantially lengthened by gene therapy or other novel treatments for the primary, neurologic disease.

Self-enhancement and the life script in future thinking across the lifespan.

Studies comparing memory and future event simulation find that future events are more positive, and more often depend on life script events (e.g., culturally normative landmark events) than past events. Previous research does not address the link between this positivity bias and the life stage of college-age participants or their reliance on these scripted events. To examine this positivity bias, narratives of past and anticipated future events were elicited from participants aged 18-74 years, and were examined for reliance on the life script and valence ratings. Results showed that, across age groups, future events were rated as more positive than past events, and that life script events were common in the distant future. Notably, whereas younger adult age groups wrote primarily about their own life script events, older participants more commonly wrote about attending the life script events of significant others, such as children and grandchildren. These findings suggest that simulated future events play a valuable role in self-enhancement across the lifespan. Furthermore, the life script can be viewed as a useful search mechanism when one is missing the episodic details that are more available in memories; however, it is not the source of positivity bias for future events.

Ultrasonographic evaluation of adrenal gland size compared to body weight in normal dogs.

The accepted cut-off value for adrenal gland maximum diameter of 0.74 cm to distinguish adrenal gland enlargement in dogs regardless of body weight may not be appropriate for small to medium breed dogs. The purpose of the current retrospective study was to examine adrenal gland dimensions as a function of body weight in healthy dogs in three weight categories (< 10 kg, 10-30 kg, and > 30 kg) representing small, medium, and large breeds, respectively, to establish greater confidence in determining if adrenal gland size is abnormal. The measurements of length (sagittal plane), cranial and caudal pole thickness (sagittal and transverse planes), and caudal pole width (transverse plane) of both adrenal glands were obtained ultrasonographically in clinically healthy dogs (n = 45) with 15 dogs in each weight group. Findings support our hypothesis that adrenal gland size correlates with body weight in normal dogs, and more precise reference intervals should be created for adrenal gland size by categorizing dogs as small, medium, or large breed. The caudal pole thickness of either adrenal gland in a sagittal plane was the best dimension for evaluating adrenal gland size based on low variability, ease, and reliability in measurement.

The development of future thinking: young children's ability to construct event sequences to achieve future goals.

Previous studies suggest that the ability to think about and act on the future emerges between 3 and 5 years of age. However, it is unclear what underlying processes change during the development of early future-oriented behavior. We report three experiments that tested the emergence of future thinking ability through children's ability to explicitly maintain future goals and construct future scenarios. Our main objectives were to examine the effects of goal structure and the effects of working memory demands on children's ability to construct future scenarios and make choices to satisfy future goals. The results indicate that 4-year-olds were able to successfully accomplish two temporally ordered goals even with high working memory demands and a complex goal structure, whereas 3-year-olds were able to accomplish two goals only when the working memory demands were low and the goal structure did not involve additional demands from inferential reasoning and contingencies between the temporally ordered goals. Results are discussed in terms of the development of future thinking in conjunction with working memory, inferential reasoning ability, and goal maintenance abilities.

Dendrimer-enabled transformation of Chlamydia trachomatis.

Lack of a system for genetic manipulation of Chlamydia trachomatis has been a key challenge to advancing understanding the molecular genetic basis of virulence for this bacterial pathogen. We developed a non-viral, dendrimer-enabled system for transformation of this organism and used it to characterize the effects of inserting the common 7.5 kbp chlamydial plasmid into strain L2(25667R), a C. trachomatis isolate lacking it. The plasmid was cloned in pUC19 and the clone complexed to polyamidoamine dendrimers, producing ∼83 nm spherical particles. Nearly confluent McCoy cell cultures were infected with L2(25667R) and reference strain L2(434). At 16 h post-infection, medium was replaced with dendrimer-plasmid complexes in medium lacking additives (L2(25667R)) or with additive-free medium alone (L2(434)). Three h later complexes/buffer were removed, and medium was replaced; cultures were harvested at various times post-transformation for analyses. Real time PCR and RT-PCR of nucleic acids from transformed cultures demonstrated plasmid replication and gene expression. A previous report indicated that one or more plasmid-encoded product govern(s) transcription of the glycogen synthase gene (glgA) in standard strains. In L2(25667R) the gene is not expressed, but transformants of that strain given the cloned chlamydial plasmid increase glgA expression, as does L2(434). The cloned plasmid is retained, replicated, and expressed in transformants over at least 5 passages, and GFP is expressed when transformed into growing L2(25667R). This transformation system will allow study of chlamydial gene function in pathogenesis.

The time travelling self: comparing self and other in narratives of past and future events.

Mental time travel research emphasizes the connection between past and future thinking, whereas autobiographical memory research emphasizes the interrelationship of self and memory. This study explored the relationship between self and memory when thinking about both past and future events. Participants reported events from the near and distant past and future, for themselves, a close friend, or an acquaintance. Past events were rated higher in phenomenological quality than future events, and near self events were rated higher in quality than those about friends. Although future events were more positive than past events, only valence ratings for self and close friend showed a linear increase in positivity from distant past to future. Content analysis showed that this increase in positivity could not be ascribed to choosing events from the cultural life script. These findings provide evidence for the role of personal goals in imagining the future.

Dendrimer-enabled DNA delivery and transformation of Chlamydia pneumoniae.

The chlamydiae are important human pathogens. Lack of a genetic manipulation system has impeded understanding of the molecular bases of virulence for these bacteria. We developed a dendrimer-enabled system for transformation of chlamydiae and used it to characterize the effects of inserting the C. trachomatis plasmid into C. pneumoniae, which lacks any plasmids. The plasmid was cloned into modified yeast vector pEG(KG) and the clone complexed to polyamidoamine dendrimers, producing 50-100 nm spherical particles. HEp-2 cell cultures were infected with C. pneumoniae strain AR-39. Twenty-four hours later, medium was replaced for 3 hours with dendrimer-plasmid complexes, then removed and the medium replaced. Cultures were harvested at various times post-transformation. Real-time PCR and RT-PCR of nucleic acids from transformed cultures demonstrated plasmid replication and gene expression. The cloned plasmid was replicated and expressed in transformants over 5 passages. This system will allow study of chlamydial gene function, allowing development of novel dendrimer-based therapies. FROM THE CLINICAL EDITOR: This team of investigators developed a dendrimer-enabled system for transformation of chlamydiae and successfully utilized it to characterize the effects of inserting the C. trachomatis plasmid into C. pneumonia. This system will allow study of chlamydial gene function, allowing development of novel dendrimer-based therapies.

Dendrimer-enabled modulation of gene expression in Chlamydia trachomatis.

The obligate intracellular bacterium Chlamydia trachomatis is an important human pathogen. The genome of this organism is small but encodes many genes of currently unknown function that are thought to be involved in virulence. Lack of a system for genetic manipulation has been a key challenge to advancing the understanding of molecular genetics underlying virulence for this bacterium. We developed a dendrimer-enabled system for transformation of C. trachomatis, and used it to demonstrate the efficient and highly specific knockdown of transcript levels from targeted genes. Antisense, sense, and other control oligonucleotides targeting two sets of duplicated genes on the chlamydial chromosome were designed, commercially synthesized, and complexed with generation-4 polyamidoamine (PAMAM) dendrimers. The complexes were given to HEp-2 cell cultures infected for 16 h with C. trachomatis serovar K and then removed three hours later. Infected cultures were harvested 6 h after pulsing, and DNA and RNA/cDNA were prepared for assessment of transcript levels compared to those for the same genes in infected cultures, without dendrimer complexation. In all cases, the targeted gene complexed to dendrimer, but not its duplicate, showed up to 90% transcript attenuation. The duration of attenuation can be extended by repeated pulsing, and in some cases transcript levels from multiple genes can be attenuated in the same organism. This system will allow study of chlamydial gene function in pathogenesis, leading to more effective therapies to treat Chlamydia-induced diseases in a targeted manner.

AAVrh10 vector corrects pathology in animal models of GM1 gangliosidosis and achieves widespread distribution in the CNS of nonhuman primates.

GM1 gangliosidosis is a rare, inherited neurodegenerative disorder caused by mutations in the GLB1 gene, which encodes the lysosomal hydrolase acid ß-galactosidase (ß-gal). ß-gal deficiency leads to toxic accumulation of GM1 ganglioside, predominantly in the central nervous system (CNS), resulting in progressive neurodegeneration. LYS-GM101 is an AAVrh.10-based gene therapy vector carrying the human GLB1 cDNA. The efficacy of intra-cerebrospinal fluid injection of LYS-GM101 analogs was demonstrated in GM1 mouse and cat models with widespread diffusion of ß-gal and correction of GM1 ganglioside accumulation in the CNS without observable adverse effects. Clinical dose selection was performed, based on a good-laboratory-practice study, in nonhuman primates (NHPs) using the clinical LYS-GM101 vector. A broadly distributed increase of ß-gal activity was observed in NHP brain 3 months after intra-cisterna magna injection of LYS-GM101 at 1.0 × 1012 vg/mL CSF and 4.0 × 1012 vg/mL CSF, with 20% and 60% increases compared with vehicle-treated animals, respectively. Histopathologic examination revealed asymptomatic adverse changes in the sensory pathways of the spinal cord and dorsal root ganglia in both sexes and at both doses. Taken as a whole, these pre-clinical data support the initiation of a clinical study with LYS-GM101 for the treatment of GM1 gangliosidosis.

The self in autobiographical memory: effects of self-salience on narrative content and structure.

Contemporary models of autobiographical memory attribute a prominent role to the conceptualisation of the self. In an attempt to better understand the impact of the self as an organising feature of autobiographical memory, narratives of personal episodes were elicited, either after a questionnaire about the self (self-prime condition) or after a distractor task (control condition). Participants also wrote a narrative of a turning-point memory, which is by definition a self-focused narrative. Narratives were divided into propositions and analysed for the types of statements used. As predicted, when writing self-focused turning-point narratives participants included more statements relating to the meaning of an event and connecting it to the self, and fewer statements focusing on the who, what, where, and when of the narrative. Narratives written after the self-prime also demonstrated characteristics that were similar to turning-point narratives, although not on all measures. This shift in narrative focus in turning-point and self-primed memory narratives indicates an increased attempt to fulfil goals of coherence rather than correspondence (Conway, 2005). These findings lend insight into the nature of the relationship between the semantic conceptualisation of the self, and the process of retrieving event-specific knowledge in episodic memory.

PAMAM dendrimer-azithromycin conjugate nanodevices for the treatment of Chlamydia trachomatis infections.

Chlamydia trachomatis is an important bacterial pathogen known to be etiological in genital infections, as well as several serious disease sequelae, including inflammatory arthritis. Chlamydiae can persist in infection, making treatment with antibiotics such as azithromycin (AZ) a challenge. The authors explore the use of neutral generation-4 polyamidoamine (PAMAM) dendrimers as intracellular drug-delivery vehicles into chlamydial inclusions. Azithromycin was successfully conjugated with the dendrimers, and the conjugate (D-AZ) released ≈ 90% of the drug over 16 hours. The conjugate readily entered both the Chlamydia-infected HEp-2 cells and the chlamydial inclusions. The conjugate was significantly better than free drug in preventing productive infections in the cells when added at the time of infection, and better in reducing the size and number of inclusions when added either 24 hours or 48 hours post infection. These studies show that dendrimers can deliver drugs efficiently to growing intracellular C. trachomatis, even if the organism is in the persistent form. FROM THE CLINICAL EDITOR: In this report, the use of polyamidoamine dendrimers as intracellular drug-delivery vehicles into chlamydial inclusions is investigated. This method results in efficient intracellular delivery of azithromycin to address chlamydia infection.

Protective immunity to chlamydial genital infection: evidence from animal studies.

In all animal models for chlamydial infection, there is strong evidence for immunity to reinfection; however, immunity is only complete (ie, preventing infection) in the short term. In the long term, animals are only partially immune (ie, they can be reinfected, but infections are usually abbreviated and less intense than the primary infection). This review will target the mechanisms responsible for long-term versus short-term immunity and explore the roles of various components of the host response in immunity to chlamydial genital infection.

The pathogenic role of Chlamydia in spondyloarthritis.

PURPOSE OF REVIEW: Topics relating to the spondyloarthropathies have been reviewed recently, but the detailed roles of Chlamydia trachomatis and C. pneumoniae in induction of spondyloarthritis have not been discussed. This review focuses on new information regarding how these pathogens elicit joint disease, with emphasis on C. trachomatis in its role in Chlamydia-induced reactive arthritis. RECENT FINDINGS: Molecular methods continue to provide insights into the molecular genetic and cell biologic basis for chlamydial pathogenesis. For chlamydiae, residence in the synovium in patients with acute or chronic Chlamydia-induced arthritis involves organisms in an unusual infection state designated persistence. The profiles of overall metabolism and gene expression characteristic of chlamydial persistence have been assessed and unusual aspects noted, including transcriptional attenuation of one hsp60 paralog and upregulation of expression for another. Strain determinations have demonstrated that genital serotypes of C. trachomatis are not present in the joint; rather, inflammation at that site is elicited by ocular serotypes of the organism. This indicates that much remains to be learned concerning the biology of chlamydial dissemination from the urogenital tract. Analyses of undifferentiated spondyloarthritis continue to suggest that chlamydiae, and perhaps other pathogens function in the etiology of the disease. Progress has been made in developing effective treatment for patients with Chlamydia-induced arthritis. SUMMARY: Molecular genetic analyses regarding the role of chlamydiae in induction of inflammatory arthritis have increased our detailed understanding of the pathogenic mechanisms utilized by these organisms in the joint. Importantly, progress has been made in developing effective therapies for treatment of Chlamydia-induced arthritis.

Patients with Chlamydia-associated arthritis have ocular (trachoma), not genital, serovars of C. trachomatis in synovial tissue.

Some individuals with a genital Chlamydia trachomatis infection develop inflammatory arthritis, but it is unknown whether particular chlamydial serovar(s) engender the disease more often than others. We defined serovar in synovial tissues from arthritis patients infected with this organism. DNA from synovial biopsies of 36 patients with PCR-confirmed synovial C. trachomatis was analyzed. Diagnoses included reactive arthritis, undifferentiated oligoarthritis, rheumatoid arthritis, and osteoarthritis. The chlamydial omp1 and trpA genes were amplified, cloned, and 10 or more clones from each sample were sequenced. The cytotoxin locus also was analyzed. omp1 sequences showed 2 patients having only C. trachomatis A serovar, 1 with only B, and 33 having only C, all ocular serovars. Analyses of trpA and the cytotoxin locus uniformly displayed standard ocular serovar characteristics for each patient. Identification of ocular chlamydial serovars in the synovia of arthritis patients is unexpected. These observations suggest that urogenital chlamydial infections, while consisting primarily of organisms of genital serovars, include some of ocular serovar(s). They further suggest that during such infections unknown selection pressures favor establishment of the latter in the synovium to the exclusion of genital serovar chlamydiae.

Abstracting and extracting: causal coherence and the development of the life story.

This study compared life story memories of emerging adults and early adolescents to other autobiographical memories. Participants described three scenes of their respective life stories, a high point, low point, and turning point narrative, and described the connections between them in a fourth narrative. Participants also related four autobiographical narratives from corresponding time periods for comparison. Narratives were analysed for two measures of causal coherence, narrative complexity and meaning making, and for thematic coherence. Life story narratives contained more self-related lessons and insights and greater recognition of complexity than non-life-story narratives, but these differences were confined to narratives of turning points and connections between events. Thematic connections between narratives were more abstract and self-related in life story narratives. Emerging adults' narratives, when compared to those of early adolescents, showed more evidence of self-related abstract thinking and recognition of multiple dimensions. Findings indicate consistent ways in which life story memories differ from other autobiographic memories, and show evidence of development in adolescence.

Does exposure to ambient odors influence the emotional content of memories?

This study examined the effects of implicitly presented odors on the emotional content of memory narratives. Participants were exposed to low levels of perfumes or no odors while they reconstructed a memory from childhood and a recurrent dream. Narratives were analyzed for emotional content using the Linguistic and Inquiry Word Count program. Exposure to perfumes increased the percentage of positive emotion words used by participants in recalling both dreams and childhood memories. In addition, exposure to odors decreased the percentage of negative emotion words that men used in their narratives, whereas the opposite effect was found for women. Discussion focuses on gender differences in written emotional expression, possible ways by which perfumes may exert their effects, and the usefulness of using ambient odors and objective content analysis when studying emotions in memories.