Tonotopic Order in the Adult and Developing Auditory System of the Rat as Shown by c-fos Immunocytochemistry

Immediate éarly genes such as the proto-oncogene c- fos can be expressed in neurons following synaptic excitation by sensory stimulation. C- fos immunocytochemistry has subsequently been shown to be a very sensitive marking technique for neuronal activity. Here, antibodies against the c- fos protein product Fos were used to map the tonotopic organization in the auditory system of adult and developing rats. After stimulating adult rats with pure-tone pulses, bands of Fos-immunoreactive neurons revealed the frequency representation in seven brainstem nuclei: all three subdivisions of the cochlear nucleus, the lateral superior olive, the medial nucleus of the trapezoid body, the ventral nucleus of the trapezoid body, the rostral periolivary nucleus, the dorsal nucleus of the lateral lemniscus and the inferior colliculus. With the exception of the dorsal cochlear nucleus and the inferior colliculus, tonotopicity has not been previously demonstrated in the brainstem nuclei of the rat. During development two striking results were obtained. First, beginning at postnatal day 14 (i.e. ∼2 days after physiological hearing begins in rats), not only low but also high frequencies were able to induce strong Fos immunoreactivity, indicating that gradual recruitment of formerly unresponsive high-frequency sites does not occur in the rat. Second, a gradual age-related shift of the position of isofrequency bands was not seen in any of the nuclei, suggesting that changes in frequency-place code do not occur after 2 weeks postnatally. These results indicate that the rat's auditory brainstem nuclei achieve their adult-like tonotopic organization early on, implying a somewhat different developmental time course than is found in other mammalian species.     

Human papillomavirus in high- and low-risk areas of oesophageal squamous cell carcinoma in China

To examine the potential roles of human papillomavirus (HPV) in oesophageal squamous cell carcinoma (ESCC) development, we examined the presence of HPV DNA in paraffin-embedded ESCC tissues collected from two areas with different ESCC incidence rates in China, that is, Gansu (n=26) and Shandong (n=33), using PCR with SPF10 primers, or PCR with GP5+/GP6+ primers combined with Southern blot hybridisation. HPV genotype was determined by the INNO-LiPA HPV genotyping kit. HPV DNA was detected in 17 cases (65%) in Gansu, where ESCC incidence is much higher than in Shandong, where HPV was positive in two samples (6%). HPV genotypes 16 and 18 were detected in 79 and 16% of HPV-positive samples, respectively. Real-time PCR analysis suggested the presence of integrated form of HPV DNA in all the HPV-16-positive samples, but its viral load was estimated to be only <1-2 copies cell(-1). We could not detect HPV 16/18 E6 protein expression by immunostaining in any of the HPV-16-positive samples. Neither p16(INK4a) nor p53 expression was related to HPV presence in ESCCs. Further studies seem warranted to examine the possible aetiological roles of HPV in ESCC.     

Neurotoxicity of reactive aldehydes: the concept of "aldehyde load" as demonstrated by neuroprotection with hydroxylamines

The concept of "oxidative stress" has become a mainstay in the field of neurodegeneration but has failed to differentiate critical events from epiphenomena and sequalae. Furthermore, the translation of current concepts of neurodegenerative mechanisms into effective therapeutics for neurodegenerative diseases has been meager and disappointing. A corollary of current concepts of "oxidative stress" is that of "aldehyde load". This relates to the production of reactive aldehydes that covalently modify proteins, nucleic acids, lipids and carbohydrates and activate apoptotic pathways. However, reactive aldehydes can also be generated by mechanisms other than "oxidative stress". We therefore hypothesized that agents that can chemically neutralize reactive aldehydes should demonstrate superior neuroprotective actions to those of free radical scavengers. To this end, we evaluated hydroxylamines as aldehyde-trapping agents in an in vitro model of neurodegeneration induced by the reactive aldehyde, 3-aminopropanal (3-AP), a product of polyamine oxidase metabolism of spermine and spermidine. In this model, the hydroxylamines N-benzylhydroxylamine, cyclohexylhydroxylamine and t-butylhydroxylamine were shown to protect, in a concentration-dependent manner, against 3-AP neurotoxicity. Additionally, a therapeutic window of 3 h was demonstrated for delayed administration of the hydroxylamines. In contrast, the free radical scavengers TEMPO and TEMPONE and the anti-oxidant ascorbic acid were ineffective in this model. Extending these tissue culture findings in vivo, we examined the actions of N-benzylhydroxylamine in the trimethyltin (TMT) rat model of hippocampal CA3 neurodegeneration. This model involves augmented polyamine metabolism resulting in the generation of reactive aldehydes that compromise mitochondrial integrity. In the rat TMT model, NBHA (50 mg/kg, sc, daily) provided 100% protection against neurodegeneration, as reflected by measurements of KCl-evoked glutamate release from hippocampal brain slices and septal high affinity glutamate uptake. In contrast, ascorbic acid (100 mg/kg, sc, daily) failed to protect CA3 neurons from TMT toxicity. In summary, our data support further evaluation of the concept of "aldehyde load" in neurodegeneration and the potential clinical investigation of agents that are effective traps for reactive aldehydes.     

Early dissemination rates of Friend murine leukaemia virus variants correlate with late pathogenesis

FIS-2, a less oncogenic, immunosuppressive variant of the Friend murine leukaemia virus (F-MuLV), was used to explore whether the differences in biological features were related to early virus dissemination rates or sites of replication. We found that erythroblasts were the primary target cells for both F-MuLV and FIS-2, while B- and T-cells were infected later in the infection. Although FIS-2 replicated to similar titres as F-MuLV, we observed a delay in peak viraemia titre and in the number of virus-positive cells in bone marrow and spleen. Studies including the chimeric viruses RE3 (FIS-2LTR with a F-MuLV background) and RE4 (F-MuLV LTR with a FIS-2 background) indicated that the delay in dissemination was due to mutations in FIS-2 LTR. The kinetics for early virus replication correlated with previously reported mean latency time for virus-induced erythroleukaemia in mice inoculated as newborns and with the onset of immunosuppression in adult mice. In addition, F-MuLV-induced late immunosuppression coincided with signs of erythroleukaemia and persistent viraemia. FIS-2 induced a more moderate late immunosuppression without persistent viraemia or signs of erythroleukaemia. Overall, our findings indicated that early viral replication is a prognostic factor in murine retrovirus-induced pathogenesis.     

Time's arrow and pupillary response

The psychological arrow of time refers to our experience of the forward temporal progression of all natural processes. To investigate whether and how time's arrow is mentally coded in individual everyday events, a relatedness judgment task was used. The items each consisted of a verb (probe) and an adjective or participle (target). The temporal orientation between probe and target was varied either corresponding to the chronological orientation (e.g., shrinking-small) or corresponding to the reverse orientation (e.g., shrinking-large). Reaction times, error rates, and pupillary responses were recorded. Chronological items were processed faster than reverse items. These findings suggest that time's arrow is mentally coded in single everyday events. Pupil dilation and results of principal component analyses suggest top-down influences in the processing of temporally related items.     

Quantitative single-voxel spectroscopy: the reciprocity principle for receive-only head coils

PURPOSE: To correct MR spectra for local changes in the coil sensitivity for a widely used coil setup, consisting of a transmitting body coil and a receive-only head coil. MATERIALS AND METHODS: The method relies on the reciprocity principle for the body coil and a correction factor for signal amplitudes between body coil and head coil. The correction is based either on the local flip angle dependence of the stimulated echo acquisition mode signal (TFC) or on the automatic RF calibration (RFC). Water phantoms of different volumes were used to simulate variable coil loads, and B1 field inhomogeneities were assessed by varying the voxel position. Furthermore, the correction was tested by longitudinal measurements in one volunteer. RESULTS: The correction in vitro yields a reduction of the variation coefficient of the water signal by about 77% (TFC) and 66% (RFC) for different coil loads, as well as 55% (TFC) for variable voxel positions. Slightly lower reductions were assessed for the variation coefficients of the metabolite signals in vivo. CONCLUSION: This approach adequately compensates for local changes in coil sensitivity, when acquiring MR spectra with a receive-only head coil.     

Viral load of HPV in esophageal squamous cell carcinoma

We previously reported the presence of HPV DNA in esophageal squamous cell carcinoma (ESCC) cases from Hong Kong and Sichuan. The role of HPV in the carcinogenesis of ESCC remains unclear, partly due to the large variations in infection rates reported by different studies. While some of these variations may truly reflect different HPV infection rates in ESCC among different geographic regions, differences in sensitivity and specificity of the detection methods used also contribute. In the present study, we used quantitative real-time PCR to determine the copy numbers of HPV-16 and HPV-18 in ESCC from 5 different regions of China with different incidence rates of ESCC. Conforming to our previous reports, HPV infection was detected in 2-22.2% of samples. Infection with HPV-16 was again shown to be more common than that with HPV-18 among Chinese ESCC patients. The copy number of HPV-16 in these ESCC cases ranged from < or =1 to 157 copies/genome equivalent, with 65% of samples harboring fewer than 10 copies/genome equivalent. The median copy number of HPV-18 was 4.9/genome equivalent. Assays were validated using cervical carcinoma cell lines with known copy numbers of HPV-16 or HPV-18. The relatively low HPV copy number and infection rate in ESCC suggest that HPV is unlikely to play as essential a role in the carcinogenesis of ESCC as in cervical cancer. However, with the consistent detection of oncogenic HPVs in ESCC from some regions of China, the possibility of HPV infection being one of the multiple risk factors of ESCC in some geographic areas cannot be excluded.     

Physical activity and breast cancer risk among female physical education and language teachers: a 34-year follow-up

The cohort consisted of 1,489 Finnish female physical education and 8,560 language teachers born after 1920 and alive in 1967. The 2 study populations were similar in social class and way of living and clearly discordant in physical activity both during their university studies and later in life. The incidence of breast cancer among these teachers up to the year 2000 was assessed through a record linkage with the Finnish Cancer Registry. The number of breast cancer cases among physical education teachers was 61 in 32,862 person-years and among language teachers was 404 in 177,188 person-years. In Poisson-regression analysis, the incidence rate ratio--adjusted for age, calendar time, number of children and age at first birth--for physical education vs. language teachers was overall 0.83 (95% confidence interval 0.63-1.09). This relative rate was 0.79 (0.46-1.36) in ages <50 years and 0.86 (0.62-1.18) in ages > or =50 years. Our study is concordant with the hypothesis that life-long physical activity may reduce the risk of breast cancer.     

Impact of acute vivax malaria on the immune system and viral load of HIV-positive subjects

Objective To explore the mechanisms of malariotherapy for human immunodeficiency virus (HIV)-infected patients and to identify which stage(s) of HIV infection is suitable for the treatment of malariotherapy. Methods Therapeutic acute vivax malaria was induced and terminated after 10 fever episodes in 12 HIV-1-infected subjects: Group 1 (G1) had 5 patients with CD4 T-cell counts &gt;=500/μl at baseline, Group 2 (G2) had 5 patients with CD4 at 499-200/μl and Group 3 (G3) had 2 patients with CD4&lt;200/μl (not included in statistical analysis). Enzyme-Linked-Immuno-Sorbent Assay (ELISA) was used to measure plasma levels of cytokines and soluble activation markers. Flow cytometry was used to measure levels of lymphocyte subsets and phenotypes and CD4 cell apoptosis. Bayer bDNA assay was used to test plasma levels of HIV-1 RNA (viral load). Samples were taken and tested twice before malaria (baselines), three times during malaria and seven times after termination of malaria (at day 10 and 1, 3, 6, 12, 18 and 24 months). Results Levels of plasma tumor necrosis factor-α (TNF-α), soluble TNF-α receptor-2 (sTNF-RII), neopterin (NPT) and soluble IL-2 receptor (sIL-2R) significantly increased during malaria and sharply reduced to baselines post malaria in all groups. Stronger responses of the aforementioned factors were seen in G2 than in G1 during malaria (P=0.081, 0.001, 0.013, 0.020). CD4 count and percentage; CD4/CD8 ratio and CD25+ and CD4+CD25+ percentages increased but HLA-DR+ percentage decreased either during or post malaria in G2. Most G2 patients experienced sustained increase but most G1 patients underwent natural history decline of CD4 counts and percentages during 2-year follow-up. Percentage of apoptotic CD4 cells decreased post malaria in all groups. G3 patients had weaker immune responses, however, one advanced AIDS patient in this group experienced clinical improvement after malariotherapy. Most of the 12 patients experienced increase of HIV viral load during malaria but the viral load returned to baseline levels 1-3 months after cure of malaria and remained near baseline levels for up to two years. Conclusions Part of the mechanisms of malariotherapy is to induce high levels of cytokine activities and subsequently the changes of T-lymphocyte subsets and phenotypes in HIV-infected patients.These findings suggest that malariotherapy may treat HIV-1-infected patients whose CD4 baselines are in the range of 500-200/μl.