8-beam local oscillator array at 4.7 THz generated by a phase grating and a quantum cascade laser.

We present an 8-beam local oscillator (LO) for the astronomically significant [OI] line at 4.7 THz. The beams are generated using a quantum cascade laser (QCL) in combination with a Fourier phase grating. The grating is fully characterized using a third order distributed feedback (DFB) QCL with a single mode emission at 4.7 THz as the input. The measured diffraction efficiency of 74.3% is in an excellent agreement with the calculated result of 75.4% using a 3D simulation. We show that the power distribution among the diffracted beams is uniform enough for pumping an array receiver. To validate the grating bandwidth, we apply a far-infrared (FIR) gas laser emission at 5.3 THz as the input and find a very similar performance in terms of efficiency, power distribution, and spatial configuration of the diffracted beams. Both results represent the highest operating frequencies of THz phase gratings reported in the literature. By injecting one of the eight diffracted 4.7 THz beams into a superconducting hot electron bolometer (HEB) mixer, we find that the coupled power, taking the optical loss into account, is in consistency with the QCL power value.

Mitochondrial Lon regulates apoptosis through the association with Hsp60-mtHsp70 complex.

Human Lon protease is a mitochondrial matrix protein with several functions, including protein degradation, mitochondrial DNA (mtDNA) binding, and chaperone activity. Lon is currently emerging as an important regulator of mitochondria-contributed tumorigenesis due to its overexpression in cancer cells. To understand the mechanism of increased Lon in tumor cells, we studied the interactome to identify the chaperone Lon-associated proteins by proteomics approaches using the cells overexpressing Lon. In the present study, we designed a method connecting co-immunoprecipitation (Co-IP) to in-solution digestion for the shotgun mass spectrometry. We identified 76 proteins that were putative Lon-associated proteins that participated in mitochondrial chaperone system, cellular metabolism and energy, cell death and survival, and mtDNA stability. The association between Lon and NDUFS8 or Hsp60-mtHsp70 complex was confirmed by Co-IP and immunofluorescence co-localization assay. We then found that the protein stability/level of Hsp60-mtHsp70 complex depends on the level of Lon under oxidative stress. Most importantly, the ability of increased Lon-inhibited apoptosis is dependent on Hsp60 that binds p53 to inhibit apoptosis. These results suggest that the mechanism underlying cell survival regulated by Lon is mediated by the maintenance of the protein stability of Hsp60-mtHsp70 complex. This new knowledge of chaperone Lon interactome will allow us to better understand the cellular mechanism of Lon in mitochondrial function and of its overexpression in enhancing cell survival and tumorigenesis.

Clinical significance of tumor suppressor PTEN in colorectal carcinoma.

BACKGROUND: It has been demonstrated that the deletion, mutation, hypermethylation and subcellular location of the tumor suppressor phosphatase and tensin homologue (PTEN) are closely correlated with carcinogenesis, progression and prognosis of malignancy. Both mutation and the microsatellite instability of the PTEN gene influence regulation of the PI3K/Akt signaling pathway. This study investigated whether loss of nuclear PTEN is correlated with chemosensitivity, clinicopathological parameters and survival. METHODS: Intracellular levels of PTEN of multiple cell lines of colorectal carcinoma (CRC) were evaluated by Western blotting and immunocytochemistry. The chemosensitivity of cell lines with various expression levels of PTEN was evaluated using 5-flurouracil (5-FU), oxaliplatin and irinotecan (CPT), and clinical significance was evaluated by immunohistochemical analysis of 133 CRC specimens. RESULTS: Colon cancer cell lines HT-29, LoVo and SW480 differed in expression of PTEN, with high, moderate and low levels, respectively. HT-29 and LoVo PTEN expression was suppressed by a low concentration of 5-FU and oxaliplatin; however, SW480 was insensitive to these chemotherapeutic agents. Nuclear PTEN was overexpressed in most (>80%) normal colon mucosa samples, but the incidence significantly decreased (89.2% → 53.4%) in the CRC group. PTEN in the nucleus was negatively correlated with tumor size and vascular invasion in CRC, and CRC patients with negative PTEN expression in the nucleus exhibited poor survival. CONCLUSION: Cell lines with a high expression of PTEN are sensitive to chemotherapy with 5-FU and oxaliplatin. Nuclear PTEN expression gradually decreases after malignant transformation, and loss of PTEN expression in the nucleus is associated with tumor progression and poor clinical outcome in CRC.

Brain serotonin depletion attenuates heatstroke-induced cerebral ischemia and cell death in rats.

To explore the importance of brain serotonin (5-hydroxytryptamine) in the heatstroke-induced cerebral ischemia and neuronal injury, we evaluated the effects of heatstroke on brain serotonin release, survival time, cerebral hemodynamic changes, and neuronal cell damage in rats with or without brain serotonin depletion produced by 5,7-dihydroxytryptamine. In vivo voltammetry was used to measure changes in extracellular concentrations of serotonin in the anterior hypothalamus, striatum, and frontal cortex. After the onset of heatstroke, rats without brain serotonin depletion displayed hyperthermia, decreased mean arterial pressure, increased intracranial pressure, decreased cerebral perfusion pressure, decreased cerebral blood flow, increased cerebral serotonin release, and increased cerebral neuronal damage compared with those of normothermic control rats. However, when the cerebral serotonin system was destroyed by 5,7-dihydroxytryptamine, the heatstroke-induced arterial hypotension, intracranial hypertension, ischemic damage to the brain, and elevated cerebral serotonin release were reduced. In addition, the survival time of the heatstroke rats was prolonged after the depletion of brain serotonin. The data indicate that brain serotonin depletion attenuates heatstroke-induced cerebral ischemia and cell death in rats.

Increased survival in experimental rat heatstroke by continuous perfusion of interleukin-1 receptor antagonist.

In order to assess the possible therapeutical value of interleukin-1 receptor antagonist (IL-1 ra) in the treatment of heatstroke, we evaluated the effects of heatstroke on survival time (interval between onset of heatstroke and death), systemic and striatal hemodynamic changes, and extent of striatal neuronal damage in rats treated with saline or IL-1 ra. The survival time of the heatstroke rats which received normal saline (single injection or continuous perfusion) was about 17 min. The heatstroke-induced ischemic damage to striatal neurons was due to systemic arterial hypotension, intracranial hypertension, decreased cerebral perfusion, and striatal dopamine (DA) accumulation (275%). Rats treated with a single injection of IL-1 ra (200 mu g/kg, i.v.) immediately after the onset of heatstroke survived much longer (91 min) than the controls. The prolongation of survival induced by IL-1 ra was brought about by attenuation of the arterial hypotension, intracranial hypertension, decreased cerebral perfusion, ischemic damage to striatal neurons, and striatal DA release value (204%). Furthermore, after continuous perfusion of IL-1 ra (200 mu g/kg per h, i.v.) immediately after the onset of heatstroke, the striatal DA release value of the rats was further reduced to 140% while the survival time of the rats was prolonged to up to 10 h from the onset of heatstroke. Thus, it appears that continuous i.v. perfusion of IL-1 ra is a good choice for heatstroke therapy.

Interleukin-1 receptor antagonist increases survival in rat heatstroke by reducing hypothalamic serotonin release.

During onset of heatstroke, rats displayed higher values of hypothalamic serotonin release and score f hypothalamic neuronal damage, and lower values of mean arterial pressure and hypothalamic blood flow compared with normothermic control rats. In another group in which interleukin-1 receptor antagonist (IL-1 ra; 200 micrograms/kg, i.v.) was injected 30 or 60 min after the start of heat exposure, the augmented hypothalamic serotonin release, diminished hypothalamic blood flow, arterial hypotension and hypothalamic neuronal damage during heatstroke were reduced as compared to the saline control group. The survival time (interval between onset of heatstroke and death) of the heatstroke rats was prolonged by treatment with IL-1 ra. The data indicate that IL-1 ra increases survival during rat heatstroke by reducing hypothalamic serotonin release.

Dopamine depletion protects striatal neurons from heatstroke-induced ischemia and cell death in rats.

To explore the importance of brain dopamine in the heatstroke-induced striatal ischemia and neuronal injury, we compared the temporal profile of the heatstroke-induced striatal extracellular dopamine release, striatal blood flow, and striatal neuronal loss in rats with or without striatal dopamine depletion produced by 6-hydroxydopamine. In vivo voltammetry was used in rats to measure changes in extracellular concentrations of dopamine in the corpus striatum. Striatal neuronal damage was rated on a scale from zero to three (0, no damage; 3, maximum cell loss). The autoradiographic diffusible tracer technique was used for the measurement of striatal blood flow. After the onset of heatstroke, the heatstroke rats without brain dopamine depletion displayed hyperthermia, decreased mean arterial pressure, increased intracranial pressure, decreased cerebral perfusion pressure, decreased striatal blood flow, increased striatal dopamine release, and increased score of striatal neuronal damage as compared with those of normothermic controls. However, when the striatal dopamine system was destroyed by 6-hydroxydopamine, the heatstroke-induced arterial hypotension, intracranial hypertension, ischemic damage to the striatum, and elevated striatal dopamine release were reduced. In addition, the survival time of the heatstroke rats was prolonged after depleting striatal dopamine. Thus it appears that dopamine depletion protects striatal neurons from heatstroke-induced ischemia and cell death.

Interleukin-1 receptor antagonist attenuates the heat stroke-induced neuronal damage by reducing the cerebral ischemia in rats.

The effects of interleukin-1 receptor antagonist (IL-Ira) on both local cerebral blood flow and neuronal damage of the hypothalamus, corpus striatum, cortex or thalamus were assessed in rats with heat stroke. Heat stroke was induced by exposing the urethane-anesthetized rats to a high ambient temperature (42 degrees C). Damage to the hypothalamus, corpus striatum, cortex or thalamus was scored on a scale of zero to three modified from the grading system of Pulsinelli and colleagues in which: 0 = normal, 1 = few neurons damaged, 2 = many neurons damaged, and 3 = all neurons damaged. During the onset of heat stroke, as compared to those of normothermia controls, the heat stroke rats displayed a higher value of colonic temperature or neuronal damage score, as well as a lower value of local cerebral blood flow or mean arterial blood pressure. In addition, compared to those of normothermic, control rats, the heat stroke rats had increased interleukin-1 and tumor necroting factor production in the diencephalon, brain stem and cortex. The heat stroke-induced neuronal damage and diminished local cerebral blood flow in different brain structures, as well as the systemic hypotension, were attenuated in animals pretreated with IL-1ra (200 micrograms/kg, iv) 30 min before the onset of heat stroke. The results indicate that IL-1ra attenuates the heat stroke-induced cerebral neuronal damage by reducing cerebral ischemia in rats.

Hypothalamic dopamine release and local cerebral blood flow during onset of heatstroke in rats.

BACKGROUND AND PURPOSE: Brain dopamine has been implicated as a mediator of brain neuronal damage resulting from ischemic injury. Augmented interleukin-1 production and cerebral ischemia occurred during onset of heatstroke. This study has attempted to ascertain whether heatstroke resulting from hyperthermia causes an increase in hypothalamic dopamine release and to assess whether the administration of an interleukin-1 receptor antagonist (IL-1ra) can attenuate heat-stroke formation. METHODS: Both local cerebral blood flow and hypothalamic dopamine release during onset of heatstroke were assessed in saline-treated rats and in rats treated with an IL-1ra. Heat-stroke was induced by exposing the animals to a high ambient temperature. Hypothalamic dopamine release was determined by carbon fiber electrodes combined with in vivo differential pulse amperometry. RESULTS: During onset of heatstroke, rats with heatstroke displayed higher values of colonic temperature, higher values of hypothalamic dopamine release, and lower values of blood flow in different brain regions compared with normothermic control rats. In another separate experiment in which IL-1ra (200 micrograms/kg IV) was injected 30 minutes before onset of heatstroke, both the augmented hypothalamic dopamine release and diminished cerebral blood flow during onset of heatstroke were significantly attenuated. In addition, the survival time (interval between onset of heatstroke and death) of the rats with heatstroke was prolonged by pretreatment with IL-1ra. CONCLUSIONS: These results suggest that an increase in hypothalamic dopamine release and a decrease in local cerebral blood flow occur during onset of heatstroke. Pretreatment with IL-1ra attenuates the heatstroke formation resulting from cerebral ischemia by reducing hypothalamic dopamine release.

Interleukin-1 beta production during the onset of heat stroke in rabbits.

During the onset of heat stroke, rabbits displayed hyperthermia (42.8 degrees C), decreased arterial blood pressure, increased intracranial pressure, decreased cerebral perfusion pressure and increased interleukin-1 beta production (in both the hypothalamus and plasma), compared to those of normothermic, control rabbits. In addition, the heat-stroke animals which received an i.v. injection of interleukin 1-receptor antagonist (200 micrograms/kg) had a survival time (interval between onset of heat stroke and death) longer than that of the heat-stroke animals which received control-vehicle solution. The data indicate that interleukin-1 production plays a role in pathogenesis of heat stroke in rabbits.

Alterations of cardiovascular functional parameters after onset of heat stroke in rats.

The effects of heat stroke formation on electrocardiogram (ECG) and blood pressure (BP) waveform parameters were assessed in rats under urethane anesthesia. Heat stroke was induced by exposing anesthetized rats to an environmental temperature of 42 degrees C. The movement in which arterial pressure began to decrease was taken as the onset of heat stroke. It was found that the duration of either P were, Q wave, R wave, S wave, T wave or QRS complex, as well as the amplitude of either P wave, Q wave, S wave or T wave were not affected after onset of heat stroke. However, the amplitude of R wave, the P-P interval, the R-R interval and the Q-T interval were significantly decreased after onset of heat stroke. In addition, the peak amplitude of systolic wave, dicrotic notch, diastolic wave, the duration of either systolic wave, a whole BP cycle, diastolic wave or dicrotic wave, the pulse pressure, as well as the mean arterial pressure were also decreased after onset of heat stroke. On the other hand, heat stroke formation increased the heart rate. The results demonstrated that alterations of these ECG and BP waveform parameters occurred after onset of heat stroke in rats.