Altered cerebellum development and dopamine distribution in a rat genetic model with congenital hypothyroidism

Thyroid hormones play crucial roles in the development and functional maintenance of the central nervous system. Despite extensive studies of the neural function of thyroid hormones, little is known about the effects of hypothyroidism on behavioural traits and the mechanisms underlying such effects. In the present study, we report an investigation of congenitally hypothyroid mutant rdw rats, revealing a novel function of thyroid hormones in the central nervous system. The rdw rats were subjected to behavioural analyses such as the rotarod test, open field test and circadian activity measurement. To determine the cause of behavioural disorders, cerebellar morphogenesis was examined by immunohistochemical analysis, and the axonal transport of dopamine in the nigrostriatal pathway was analysed by high-performance liquid chromatography and western blotting. The effects of thyroxine administration to the rdw rats were examined by behavioural analysis. The rdw rats showed severe impairment of motor coordination and balance. This could be explained by the fact that the rats showed severe retardation of cerebellar morphogenesis, which correlates with the small somata and poor dendritic arborisation of Purkinje cells and retarded migration of granule cells particularly during the first two postnatal weeks. Moreover, the rdw rats showed hypoactivity, characterised by decreased circadian locomotor activity. After weaning, thyroxine administration improved the dwarfism in rdw rats but had no effect on cerebellar function. In addition, the rdw rats showed anxiety and depression intrinsically to novel surroundings. Interestingly, the rdw rats showed high levels of dopamine in the substantia nigra and low levels in the striatum, an important centre for the coordination of behaviour. Furthermore, low levels of tubulin in the striatum were detected, indicating the aberrant axonal transport of dopamine in the nigrostriatal pathway as a result of the reduced delivery of microtubules. These findings indicate an important function of thyroid hormones in cerebellar formation and in the regulation of axonal transport of dopamine. Moreover, rdw rats will be useful for studies of brain function and behavioural disorders in congenital hypothyroidism.

Analytical insights into optimality and resonance in fish swimming

This paper provides analytical insights into the hypothesis that fish exploit resonance to reduce the mechanical cost of swimming. A simple body-fluid fish model, representing carangiform locomotion, is developed. Steady swimming at various speeds is analysed using optimal gait theory by minimizing bending moment over tail movements and stiffness, and the results are shown to match with data from observed swimming. Our analysis indicates the following: thrust-drag balance leads to the Strouhal number being predetermined based on the drag coefficient and the ratio of wetted body area to cross-sectional area of accelerated fluid. Muscle tension is reduced when undulation frequency matches resonance frequency, which maximizes the ratio of tail-tip velocity to bending moment. Finally, hydrodynamic resonance determines tail-beat frequency, whereas muscle stiffness is actively adjusted, so that overall body-fluid resonance is exploited.

Multi-system progressive angiomatosis in a dog resembling blue rubber bleb nevus syndrome in humans

A six-year-old, neutered, female golden retriever was presented with generalised, dark purple to black cutaneous nodules and gastrointestinal haemorrhage. Histopathologically, all cutaneous nodules were diagnosed as benign cavernous haemangiomas. Endoscopic analysis revealed similar nodules in the oesophagus, stomach and duodenum. At laparotomy, similar nodules were seen on the visceral peritoneal lining of abdominal organs. Metastatic haemangiosarcoma was ruled out based on histological features and lack of primary tumour in spleen, liver or heart ultrasonographically. Blood loss associated with gastrointestinal haemorrhage was managed with blood transfusion. To the authors' knowledge, this is the first canine case of multi-system progressive angiomatosis resembling blue rubber bleb nevus syndrome in humans.

Mechanisms underlying rhythmic locomotion: interactions between activation, tension and body curvature waves

Undulatory animal locomotion arises from three closely related propagating waves that sweep rostrocaudally along the body: activation of segmental muscles by motoneurons (MNs), strain of the body wall, and muscle tension induced by activation and strain. Neuromechanical models that predict the relative propagation speeds of neural/muscle activation, muscle tension and body curvature can reveal crucial underlying control features of the central nervous system and the power-generating mechanisms of the muscle. We provide an analytical explanation of the relative speeds of these three waves based on a model of neuromuscular activation and a model of the body-fluid interactions for leech anguilliform-like swimming. First, we deduced the motoneuron spike frequencies that activate the muscle and the resulting muscle tension during swimming in intact leeches from muscle bending moments. Muscle bending moments were derived from our video-recorded kinematic motion data by our body-fluid interaction model. The phase relationships of neural activation and muscle tension in the strain cycle were then calculated. Our study predicts that the MN activation and body curvature waves have roughly the same speed (the ratio of curvature to MN activation speed ≈0.84), whereas the tension wave travels about twice as fast. The high speed of the tension wave resulting from slow MN activation is explained by the multiplicative effects of MN activation and muscle strain on tension development. That is, the product of two slower waves (activation and strain) with appropriate amplitude, bias and phase can generate a tension wave with twice the propagation speed of the factors. Our study predicts that (1) the bending moment required for swimming is achieved by minimal MN spike frequency, rather than by minimal muscle tension; (2) MN activity is greater in the mid-body than in the head and tail regions; (3) inhibitory MNs not only accelerate the muscle relaxation but also reduce the intrinsic tonus tension during one sector of the swim cycle; and (4) movements of the caudal end are passive during swimming. These predictions await verification or rejection through further experiments on swimming animals.

Mechanisms underlying rhythmic locomotion: dynamics of muscle activation

We have studied the dynamical properties of tension development in leech longitudinal muscle during swimming. A new method is proposed for modeling muscle properties under functionally relevant conditions where the muscle is subjected to both periodic activation and rhythmic length changes. The 'dual-sinusoid' experiments were conducted on preparations of leech nerve cord and body wall. The longitudinal muscle was activated periodically by injection of sinusoidal currents into an identified motoneuron. Simultaneously, sinusoidal length changes were imposed on the body wall with prescribed phase differences (12 values equally spaced over 2π radians) with respect to the current injection. Through the singular value decomposition of appropriately constructed tension data matrices, the leech muscle was found to have a multiplicative structure in which the tension was expressed as the product of activation and length factors. The time courses of activation and length factors were determined from the tension data and were used to develop component models. The proposed modeling method is a general one and is applicable to contractile elements for which the effects of series elasticity are negligible.

Comparison of predicted and perceived pain from epidural and spinal puncture in patients undergoing elective caesarean section

The intensity of pain expected by patients before an epidural and/or a spinal puncture is uncertain. The main purpose of this study was to identify and compare the intensity of pain predicted and perceived by patients having an epidural and a spinal procedure. After screening for relevant exclusion criteria, 50 women who were undergoing elective caesarean section under combined spinal-epidural anaesthesia (double-segment technique) were enrolled in the study. Infiltration anaesthesia prior to needle insertion was performed for the epidural but not the spinal puncture. Pain assessments, using a 100 mm visual analogue pain scale, were made before (predicted pain) and after (perceived pain) the epidural and the spinal puncture. Predicted pain for epidural and spinal insertion (epidural 60.6 +/- 20.5 mm, spinal: 55.1 +/- 24 mm) was significantly higher than the pain perceived (epidural 36.3 +/- 20 mm, spinal 46.1 +/- 23.2 mm) (epidural P < 0.001, spinal P = 0.031). Patients who were scheduled for an elective caesarean section under combined spinal-epidural anaesthesia predicted 1.2- to 1.7-fold stronger pain intensity than they perceived during the procedure. Patients should be informed that a regional anaesthetic, especially epidural, procedure is often less painful than the patient's expectation.

Mechanisms underlying rhythmic locomotion: body-fluid interaction in undulatory swimming

Swimming of fish and other animals results from interactions of rhythmic body movements with the surrounding fluid. This paper develops a model for the body-fluid interaction in undulatory swimming of leeches, where the body is represented by a chain of rigid links and the hydrodynamic force model is based on resistive and reactive force theories. The drag and added-mass coefficients for the fluid force model were determined from experimental data of kinematic variables during intact swimming, measured through video recording and image processing. Parameter optimizations to minimize errors in simulated model behaviors revealed that the resistive force is dominant, and a simple static function of relative velocity captures the essence of hydrodynamic forces acting on the body. The model thus developed, together with the experimental kinematic data, allows us to investigate temporal and spatial (along the body) distributions of muscle actuation, body curvature, hydrodynamic thrust and drag, muscle power supply and energy dissipation into the fluid. We have found that: (1) thrust is generated continuously along the body with increasing magnitude toward the tail, (2) drag is nearly constant along the body, (3) muscle actuation waves travel two or three times faster than the body curvature waves and (4) energy for swimming is supplied primarily by the mid-body muscles, transmitted through the body in the form of elastic energy, and dissipated into the water near the tail.

Comparison of varying injection rates of saline chasers on intravascular contrast enhancement for dynamic CT in cattle

Dynamic CT was performed in five normal Holstein calves to investigate the effect of saline chasers on intravascular contrast enhancement when administered at three different rates. The five calves were imaged using dynamic CT in a crossover study design. Group A was administered only contrast medium (600 mg iodine/kg, 4 ml/s), while groups B, C and D were administered contrast medium at 30 per cent reduction followed by saline chasers injected at 2, 4 and 8 ml/s, respectively. Attenuation values were obtained from the right and left maxillary arteries and dorsal sagittal sinus. Maximum enhancement value and mean value of the enhancement plateau obtained from the maxillary arteries were significantly lower in group B than in the other groups. The duration of the enhancement plateau was longer in group C than in groups B and D (P<0.05).

Four-year study of lamivudine and adefovir combination therapy in lamivudine-resistant hepatitis B patients: influence of hepatitis B virus genotype and resistance mutation pattern

To investigate the efficacy of long-term lamivudine (3TC) and adefovir dipivoxil (ADV) combination therapy in 3TC-resistant chronic hepatitis B virus (HBV) infected patients, we analysed 28 3TC-resistant patients treated with the combination therapy during 47 months (range, 9-75). At 12, 24, 36, and 48 months, the rates of virological response with undetectable HBV DNA (≤ 2.6 log copies/mL) were 56, 80, 86, and 92%, respectively. Among 17 hepatitis B e antigen (HBeAg)-positive patients, HBeAg disappeared in 24% at 12 months, 25% at 24 months, 62% at 36 months, and 88% at 48 months. When HBV genotypes were compared, patients with genotype B achieved virological response significantly more rapidly than those with genotype C (P=0.0496). One patient developed virological breakthrough after 54 months, and sequence analysis of HBV obtained from the patient was performed. An rtA200V mutation was present in the majority of HBV clones, in addition to the 3TC-resistant mutations of rtL180M+M204V. The rtN236T ADV-resistant mutation was observed in only 25% clones. In vitro analysis showed that the rtA200V mutation recovered the impaired replication capacity of the clone with the rtL180M+M204V mutations and induced resistance to ADV. Moreover, rtT184S and rtS202C, which are known entecavir-resistant mutations, emerged in some rtL180M+M204V clones without rtA200V or rtN236T. In conclusion, 3TC+ADV combination therapy was effective for most 3TC-resistant patients, especially with genotype B HBV, but the risk of emergence of multiple drug-resistant strains with long-term therapy should be considered. The mutation rtA200V with rtL180M+M204V may be sufficient for failure of 3TC+ADV therapy.

Refinement of Plas Samples by Using Afm Image and First Observation of Plas Signals on Amorphous Carbon Nitridea-CNx Films

The shape of several waveguide end of samples for photoluminescence absorption spectroscopy (PLAS) was studied by atomic force microscope (AFM), because there was an experimental problem where some samples for PLAS did not work. Using the result of AFM, the waveguide end was reshaped by plasma dry etching. The shortening of the etching time was an effective method to improve the structure of the waveguide end. Secondly, the PLAS method was extended to the other materials from a-Si:H. The PLAS signal of amorphous carbon nitride a-CNx was detected for the first time. Amorphous carbon nitride a-CNx film itself and the interface between a-CNx and a-Si02 are found as good as a-Si:H and the interface between a-Si:H and a-Si 3N4+x:H, respectively.