The development of the tongue and morphological and cytological changes in taste discs of Rana esculenta

From the 38th developmental stage of the tadpole of Rana esculenta the process of tongue formation consists in the fast growth of the lining of the oral cavity floor anteriorly and faucially. This process is accompanied by the development of taste organs on the dorsal side of the tongue. At developmental stages 39-42 taste disc anlages are covered by a layer of ordinary epithelial cells. At these stages, in some cells of a taste disc single synaptic-like vesicles with an electron-dense core appear. Apart from that, as early as at stage 42 differentiation of the cells of a taste disc can be observed at the ultrastructural level. It is only at the 44th stage that all cell types characteristic for the mature TD can be distinguished in TEM (i.e., taste cells, basal cells and three kinds of associate cells: mucous, wing and sustentacular). Starting from that stage changes in the cell membrane can be observed indicating the presence of afferent synaptic junctions. The antibody used in the experiment was raised against neuron-specific enolase (NSE). At each of the developmental stages investigated (38, 42, 45) nerve fibres within the connective tissue beneath the epithelium of a taste disc anlage were immunopositive for NSE. From stage 42 onwards neural elements present in the basal part of the epithelium of a taste disc anlage were also NSE-positive. Basal cells did not show immuno-reactivity for NSE at any of the developmental stages investigated.     

Comparison of hepatitis C viral loads in patients with or without coinfection with different genotypes

Hepatitis C virus genotyping was assessed for 257 chronic hepatitis C patients with viral loads above 1,000 IU/ml. Twelve patients were coinfected with more than one genotype. Their median viral loads did not differ significantly from those observed for monoinfected patients, which in turn did not vary significantly among different genotypes.     

Trypanosoma cruzi antigen that interacts with the beta1-adrenergic receptor and modifies myocardial contractile activity

Previously, we have demonstrated that plasma membranes from the parasite Trypanosoma cruzi (T. cruzi) recognize and adhere to host cells through parasite surface attachment molecules that have affinity for beta(1)-adrenergic receptors (beta(1)-ARs) on target organs. In this report we identify a parasite protein that not only interacts with beta(1)-ARs, but also displays beta-agonist-like activity. We demonstrate that a recombinant maltose binding protein fusion of Tc13 Tul (MBP-Tc13 Tul), a member of the T. cruzi antigen 13 family of surface antigen proteins, competes for binding sites with the beta-adrenergic receptor antagonist [125I]-CYP on membranes purified both from CHO cells expressing human beta(1)-ARs and from rat atria. The competition is prevented by pre-treating MBP-Tc13 Tul with antibodies directed against the EPKSA repeat domain of Tc13 Tul, implicating this portion of the molecule in binding to the beta(1)-AR. Furthermore, MBP-Tc13 Tul activates rat myocardial beta(1)-ARs, resulting in synthesis of cyclic adenosine monophosphate (cAMP) and an increase in cardiac contractility. These biological effects are selectively suppressed by the beta(1)-AR antagonist atenolol, by a synthetic peptide corresponding to the second extracellular loop of the human beta(1)-AR, and by the anti-EPKSA repeat antibodies. These results imply that the Tc13 Tul cell-surface antigen of T. cruzi plays a central role in misregulating the beta(1)-AR following parasite infection, and may be a causative factor of dysautonomic syndrome described in Chagas' disease.     

Neural changes in cat auditory cortex after a transient pure-tone trauma

Here we present the changes in cortical activity occurring within a few hours after a 1-h exposure to a 120-dB SPL pure tone (5 or 6 kHz). The changes in primary auditory cortex of 16 ketamine-anesthetized cats were assessed by recording, with two 8-microelectrode arrays, from the same multiunit clusters before and after the trauma. The exposure resulted in a peripheral threshold increase that stabilized after a few hours to on average 40 dB in the frequency range of 6-32 kHz, as measured by the auditory brain stem response. The trauma induced a shift in characteristic frequency toward lower frequencies, an emergence of new responses, a broadening of the tuning curve, and an increase in the maximum of driven discharges. In addition, the onset response after the trauma was of shorter duration than before the trauma. The results suggest the involvement of both a decrease and an increase in inhibition. They are discussed in terms of changes in central inhibition and its implications for tonotopic map plasticity.     

Effects of L-carnitine on neutrophil functions in aged rats

Several age-related alterations occur at the cellular level in the immune system leading to a decrease in the immune response. The present study was designed to determine the effect of L-carnitine on impaired neutrophil functions of aged rats. For this reason, superoxide anion radical production, chemotaxis and phagocytic activity were studied in the neutrophils obtained from the peripheral blood of young and old rats. We orally gavaged L-carnitine (50 mg/kg b.w. per day) or control vehicle into young (2 months) and aged (24 months) rats for 30 consecutive days. The neutrophils of aged rats exhibited an increase in superoxide anion production and decline in phagocytosis and chemotaxis when compared with that in young rat neutrophils. Superoxide anion production in aged rats was significantly decreased by L-carnitine treatment which was accompanied with a significant enhancement of chemotactic and phagocytic activity being restored to control levels. These findings demonstrated that L-carnitine is capable of restoring the age-related changes of neutrophil functions.     

Surface chemistry modulates focal adhesion composition and signaling through changes in integrin binding

Biomaterial surface properties influence protein adsorption and elicit diverse cellular responses in biomedical and biotechnological applications. However, the molecular mechanisms directing cellular activities remain poorly understood. Using a model system with well-defined chemistries (CH₃, OH, COOH, NH₂) and a fixed density of the single adhesive ligand fibronectin, we investigated the effects of surface chemistry on focal adhesion assembly and signaling. Surface chemistry strongly modulated integrin binding and specificity—₅β₁ integrin binding affinity followed the pattern OH>NH₂=COOH>CH₃, while integrin _Vβ₃ displayed the relationship COOH>NH₂OH=CH₃. Immunostaining and biochemical analyses revealed that surface chemistry modulates the structure and molecular composition of cell-matrix adhesions as well as focal adhesion kinase (FAK) signaling. The neutral hydrophilic OH functionality supported the highest levels of recruitment of talin, -actinin, paxillin, and tyrosine-phosphorylated proteins to adhesive structures. The positively charged NH₂ and negatively charged COOH surfaces exhibited intermediate levels of recruitment of focal adhesion components, while the hydrophobic CH₃ substrate displayed the lowest levels. These patterns in focal adhesion assembly correlated well with integrin ₅β₁ binding. Phosphorylation of specific tyrosine residues in FAK also showed differential sensitivity to surface chemistry. Finally, surface chemistry-dependent differences in adhesive interactions modulated osteoblastic differentiation. These differences in focal adhesion assembly and signaling provide a potential mechanism for the diverse cellular responses elicited by different material properties.     

Heart rate response during incremental exercise in master runners

We analyzed the kinetics of heart rate (HR) response during incremental treadmill exercise in thirteen master runners (62 +/- 1 yr). The HR/running speed (HR/S) relationship showed the existence of a point of downward deflection (HR(d)) in only approximately 31% of the subjects. Resting echocardiographic evaluations showed similar heart dimensions in all of the subjects. In conclusion, HR does not seem to show a curvilinear response (downward deflection) in most aged athletes.     

Retrospective analysis of antiretroviral HIV treatment success based on medical history or guided by the reverse hybridisation LiPA HIV genotyping system

The changes in viral load and CD4(+) count at 3 and 6 months in a group of 166 HIV-infected patients was evaluated. The new therapy was chosen based on the medical history procedures for 70 patients, and in 96 patients it was guided by the partial or complete result of the line probe assay (LiPA) HIV RT and Protease resistance tests. The absolute difference from the baseline of the log viral load at 3 and 6 months was significantly different between the two groups when adjusted for baseline viral load (P < 0.0001) and stayed significant when intention-to-treat analysis was carried out (P < 0.001). The absolute difference of the CD4(+) count was not significantly different when adjusted for baseline CD4(+) (P = 0.854, 3 months; P = 0.06, 6 months). The proportion of patients with a viral load 相似文献