How age relates to spatial navigation performance: Functional and methodological considerations

Aging effects have often been reported for spatial navigation performance. Moreover, navigation performance is thought to be an early marker of pathological aging. Yet, the cognitive complexity of navigation and large individual variation in healthy population make it difficult to pinpoint the precise aging mechanisms involved. We performed a systematic literature review with specific attention to functional dissociation between the tasks used and methodological characteristics. The literature search resulted in 39 articles in which age comparisons were made for large-scale navigation measures. Outcomes were categorized into the domains of landmark, location (egocentric and allocentric), and path knowledge (route and survey). Results indicate that clear functional dissociation exists between these navigation knowledge domains. Aging effects are found for path knowledge most convincingly, while landmark and egocentric location knowledge are frequently omitted in assessment. The participant samples reported often neglect adult, middle aged participants, while this group could be highly informative to the aging process as well. Moreover, having a clear image of age-related performance across the lifespan could be a valuable addition towards the early detection of pathological aging through navigation performance.     

An evaluation of wayfinding abilities in adolescent and young adult males with autism spectrum disorder

BackgroundWayfinding refers to traveling from place to place in the environment. Despite some research headway, it remains unclear whether individuals with Autism Spectrum Disorder (ASD) show strengths, weaknesses, or similarities in wayfinding compared with ability-matched typically developing (TD) controls.MethodThe current study tested 24 individuals with ASD, 24 mental-ability (MA) matched TD (MA-TD) controls, and 24 chronological-age (CA) matched TD (CA-TD) controls. Participants completed a route learning task and a survey learning task, both programmed in virtual environments, and a perspective taking task. Their parents completed questionnaires assessing their children’s everyday wayfinding activities and competence.ResultsOverall, CA-TD controls performed better than both the ASD group and the MA-TD group in both wayfinding tasks and the perspective taking task. Individuals with ASD performed similarly to the MA- TD controls on wayfinding performance except for backtracking routes. Perspective taking presented an area of deficit for people with ASD and it predicted individual differences in route learning and survey learning. Parents’ reports did not predict their children’s wayfinding performance. Two mini meta-analyses, including previous studies and the current study, showed a significant deficit in route learning, but not in survey learning for the ASD group relative to MA-TD controls.ConclusionsAlthough participants with ASD showed impairments in wayfinding relative to CA-TD controls, the impairment is not specific to their ASD, but rather due to their mental age. Nevertheless, route reversal in route learning may present unique difficulty for people with ASD beyond the effects of mental age.     

Novel fabrication of fluorescent silk utilized in biotechnological and medical applications

Silk fibroin (SF) is a natural polymer widely used and studied for diverse applications in the biomedical field. Recently, genetically modified silks, particularly fluorescent SF fibers, were reported to have been produced from transgenic silkworms. However, they are currently limited to textile manufacturing. To expand the use of transgenic silkworms for biomedical applications, a solution form of fluorescent SF needed to be developed. Here, we describe a novel method of preparing a fluorescent SF solution and demonstrate long-term fluorescent function up to one year after subcutaneous insertion. We also show that fluorescent SF labeled p53 antibodies clearly identify HeLa cells, indicating the applicability of fluorescent SF to cancer detection and bio-imaging. Furthermore, we demonstrate the intraoperative use of fluorescent SF in an animal model to detect a small esophageal perforation (0.5 mm). This study suggests how fluorescent SF biomaterials can be applied in biotechnology and clinical medicine.     

Thin silk fibroin films as a dried format for temperature stabilization of inactivated polio vaccine

Current inactivated polio vaccine (IPV) products are sensitive to both freezing and elevated temperatures and therefore must be shipped and stored between 2 °C and 8 °C, a requirement that imposes financial and logistical challenges for global distribution. As such, there is a critical need for a robust, thermally stable IPV to support global polio eradication and post-eradication immunization needs. Here, we present the development of air-dried thin films for temperature stabilization of IPV using the biomaterial silk fibroin. Thin-film product compositions were optimized for physical properties as well as poliovirus D-antigen recovery and were tested under accelerated and real-time stability storage conditions. Silk fibroin IPV films maintained 70% D-antigen potency after storage for nearly three years at room temperature, and greater than 50% potency for IPV-2 and IPV-3 serotypes at 45 °C for one year. The immunogenicity of silk fibroin IPV films after 2-week storage at 45 °C was assessed in Wistar rats and the stressed films generated equivalent neutralizing antibody responses to commercial vaccine for IPV-1 and IPV-2. However, the absence of IPV-3 responses warrants further investigation into the specificity of ELISA for intact IPV-3 D-antigen. By demonstrating immunogenicity post-storage, we offer the air-dried silk film format as a means to increase IPV vaccine access through innovative delivery systems such as microneedles.     

Chromosome Abnormalities and Absolute Telomere Lengths of Leukocytes from Silk Weavers with Emphasis on Potential Genotoxicity and Mutagenicity of Silk Dyes

Objectives: This study is aimed to assess the possible genotoxicity and mutagenicity of silk dyes on silk weavers.Methods: Peripheral blood leukocytes were obtained from 24 silk weavers and 24 age- and sex-matched controls innortheastern Thailand. After mitogen stimulation in culture, chromosome abnormalities were examined using Giemsabanding and the absolute telomere length (aTL) was measured with SYBR green qRT-PCR. To confirm genotoxic andmutagenic effects of silk dyes, leukocytes from one each of healthy male and female volunteers were cultured withvarious concentrations of 3 dark red silk dyes under the presence of mitogen. Chromosome abnormalities and thetelomere length were determined as above. Results: The proportion of normal metaphase in the silk weaving workerswas significantly lower than that in controls. The frequency of chromosome aberrations was higher in the silk weaversthan in control group. Polyploidy was detected only in the silk weavers. The aTL was significantly shorter in the silkweavers than in control group (p < 0.05). When leukocytes from normal volunteers were stimulated with mitogen underthe presence of various concentrations of 3 silk dyes, suppressed the mitotic index (MI) and normal metaphase, whereasthe proportion of prophase and the incomplete chromosome forming increased significantly. All dyes induced polyploidy.Dye #CA5 induced structural changes in male leukocytes, whereas #30 induced the changes in female leukocytes.The #CA5 increased aTL of normal leukocytes in a dose-dependent manner. Conclusions: All dyes, especially #CA5,have high genotoxicity and mutagenicity to induce chromosome aberrations and telomeric instability. Taken all thoseresults together, regular health checking of silk weavers who have been exposed to those dyes is critically necessaryto prevent various chemical-induced carcinogenesis.     

Plasma and urinary cortisol levels after dexamethasone in affective disorders

The validity of the dexamethasone suppression test was evaluated for the differential diagnosis of primary and secondary depressions.Forty hospitalized psychiatric patients (14 primary depressed, 15 secondary depressed and 11 non-depressed controls) were studied. The Research Diagnostic Criteria of Spitzer et al. (1978) were used to classify these patients.Eight out of the 14 primary depressed patients had an abnormally high plasma cortisol at 4 p.m. after dexamethasone. Only 2 out of the 15 secondary depressed patients and none of the 11 controls had an abnormal response to dexamethasone.Based on these results, the dexamethasone suppression test has a sensitivity of 57%, a specificity of 87% and a predictive value of 80%.The determination of urinary free cortisol excretion does not improve the performance of the test.     

Use of immunoblot technique for detection of human IgE and IgG antibodies to individual silk proteins

Allergenic proteins were extracted from one silk batch that was imported to be used as filling material for bed mattresses and rugs. IgE and IgG antibodies to the extracted silk proteins were measured by RAST in sera of nine silk-sensitive persons as well as in sera of healthy control donors. Silk proteins were fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis into 12 polypeptides of molecular weights between 14 and 70 kilodaltons. By means of the immunoblot technique, IgE and IgG antibodies to the individual silk polypeptides could be detected. Sera of silk-sensitive persons contained high titers of IgE and low titers of IgG antibodies to the separated silk polypeptides. Sera of control donors contained low IgG antibody titers to a limited number of these polypeptides.