Determination of tissue thermal conductivity by measuring and modeling temperature rise induced in tissue by pulsed focused ultrasound.

A tissue thermal conductivity (Ks) is an important parameter which knowledge is essential whenever thermal fields induced in selected organs are predicted. The main objective of this study was to develop an alternative ultrasonic method for determining Ks of tissues in vitro suitable for living tissues. First, the method involves measuring of temperature-time T(t) rises induced in a tested tissue sample by a pulsed focused ultrasound with measured acoustic properties using thermocouples located on the acoustic beam axis. Measurements were performed for 20-cycle tone bursts with a 2 MHz frequency, 0.2 duty-cycle and 3 different initial pressures corresponding to average acoustic powers equal to 0.7 W, 1.4 W and 2.1 W generated from a circular focused transducer with a diameter of 15 mm and f-number of 1.7 in a two-layer system of media: water/beef liver. Measurement results allowed to determine position of maximum heating located inside the beef liver. It was found that this position is at the same axial distance from the source as the maximum peak-peak pressure calculated for each nonlinear beam produced in the two-layer system of media. Then, the method involves modeling of T(t) at the point of maximum heating and fitting it to the experimental data by adjusting Ks. The averaged value of Ks determined by the proposed method was found to be 0.5±0.02 W/(m·°C) being in good agreement with values determined by other methods. The proposed method is suitable for determining Ks of some animal tissues in vivo (for example a rat liver).

Influence of locomotor training on the structure and myosin heavy chains of the denervated rat soleus muscle.

OBJECTIVE: Mechanism of denervation atrophy remains poorly understood. In particular, the question about irreversibility of the late atrophy is still open. Therefore, in the present study, we investigated whether and how a passive movement can affect a progress of atrophy in rat soleus muscle. To address this issue, a locomotor training on a treadmill was applied to rats with their right hindlimb muscles denervated. METHODS: The hindlimb muscles were denervated by cutting the sciatic nerve. Starting either 7 days or 1 month after the surgery, the animals were trained on a treadmill. Two months after denervation, the soleus muscle was investigated using light and electron microscopy and biochemical methods. Control soleus muscles were obtained from non-trained animals: the untreated and the 2-month denervated. RESULTS: Locomotor training caused slight increase in denervated rat soleus muscle weight and significant increase in its fiber diameter. The training positively affected some of the factors that were believed to be the reasons of atrophy irreversibility, because of significant increase in the number of capillary blood vessels and muscle fiber nuclei with the concomitant decrease in the number of severely damaged muscle fibers and amount of collagen. Morphology of the contractile apparatus was also improved as more regular organization of sarcomeres and the hexagonal arrangement of myosin filaments was evident. Moreover, the amount of myosin heavy chains (MHC) significantly increased after training. The effects were more evident in the animals with longer training. CONCLUSION: Passive movement seems to attenuate some of the pathologic processes within the denervated muscle.

Ultrastructure of diaphragm from dystrophic alpha-sarcoglycan-null mice.

alpha-Sarcoglycan is a 50 kDa single-pass transmembrane glycoprotein exclusively expressed in striated muscle that, together with beta-, gamma-, and delta-sarcoglycan, forms a sub-complex at the muscle fibre cell membrane. The sarcoglycans are components of the dystrophin-associated glycoprotein (DAG) complex which forms a mechanical link between the intracellular cytoskeleton and extracellular matrix. The DAG complex function is to protect the muscle membrane from the stress of contractile activity and as a structure for the docking of signalling proteins. Genetic defects of DAG components cause muscular dystrophies. A lack or defects of alpha-sarcoglycan causes the severe type 2D limb girdle muscular dystrophy. alpha-Sarcoglycan-null (Sgca-null) mice develop progressive muscular dystrophy similar to the human disorder. This animal model was used in the present work for an ultrastructural study of diaphragm muscle. Diaphragm from Sgca-null mouse presents a clear dystrophic phenotype, with necrosis, regeneration, fibre hypertrophy and splitting, excess of collagen and fatty infiltration. Some abnormalities were also observed, such as centrally located nuclei of abnormal shape, fibres containing inclusion bodies within the contractile structure, and fibres with electron-dense material dispersed over almost the entire cell. Additionally, unusual interstitial cells of uncertain identity were detected within muscle fibres. The abnormal ultrastructure of the diaphragm from Sgca-null mice is discussed.

A phase II study of gemcitabine plus cisplatin in patients with advanced non-small cell lung cancer: clinical outcomes and quality of life.

The aim of the present phase II study was to assess the activity and safety of gemcitabine-cisplatin combination in advanced NSCLC, and to evaluate the impact of this regimen in terms of symptom benefit and quality of life (QOL). Eighty patients with pathologically confirmed advanced (stage IIIB and IV) NSCLC were enrolled into this study. Gemcitabine was administered on days 1, 8 and 15 at a dose of 1000 mg/m(2), and cisplatin was given on day 2 at a dose of 100 mg/m(2). The cycles were repeated every 4 weeks. The impact of treatment on QOL and on tumor-related symptoms was evaluated with the validated EORTC forms (QLQ-C30 and LC-13). The regimen was relatively well tolerated. Myelosuppresion was the principal toxicity. Grade 3/4 neutropenia, thrombocytopenia and anemia occurred in 58, 65 and 30% of patients respectively. In 143 cycles (35%) the administration of gemcitabine on day 15 was omitted due to myelosuppresion. Non-hematological toxicities were generally mild. Among the 76 patients available for response evaluation, there were 5 complete responses (7%) and 26 partial responses (34%); an overall response rate of 41%. The median duration of response was 8.0 months. The median survival for all 80 patients was 11.0 months and the actuarial 1-year survival probability 45%. During therapy global QOL improved in 22% of patients and particular functional domains increased in 19-37% of patients. Dyspnea was released in 36% of patients, fatigue in 45%, chest pain in 38%, shoulder pain in 27%, cough in 44%, and hemoptysis in 75%. The mean intensity scores of the last three symptoms decreased significantly with therapy. Our study confirmed relatively high efficacy of the gemcitabine-cisplatin combination in patients with advanced NSCLC. Of particular importance was that treatment with gemcitabine-cisplatin combination in a large proportion of patients was also associated with remarkable symptomatic release and with improvement of QOL. However, the high frequency of myelotoxicity-related gemcitabine omissions on day 15 of the cycle indicates that modification of the schedule should be considered in standard care.