Adv Exp Med Biol
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Respiratory long-term facilitation (LTF), a prolonged augmentation of respiratory motor output, is induced by intermittent hypoxia in anesthetized or sleeping rats (and humans in limited conditions). Whether such augmentation in the controller response is of physiological benefit in terms of ventilatory stability remains uncertain; its impact on ventilatory stability will be determined to some extent by its effects on CO2 chemoreflex loop gain. ⋯ Whereas a decreased chemoreflex threshold would promote ventilatory stability, increased chemoreflex gain represents a destabilizing influence. Based on these considerations alone, the impact of respiratory LTF on respiratory stability remains unclear.
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Recent advances in near-infrared spectroscopy (NIRS) allow measurements of absolute tissue oxygen saturation (TOI) using spatially resolved spectroscopy (SRS), while enabling better depth sensitivity. However concerns remain regarding the relative contribution of the extracranial circulation to the cerebral NIRS TOI signal. In this study we investigated this during a period of selective rise in cerebral blood flow (CBF) produced by the administration of acetazolamide (ACZ) in 10 healthy volunteers. ⋯ After ACZ administration we were able to observe a significant increase in the velocity of middle cerebral artery (V(mca), measured with the transcranial Doppler (TCD)) which was accompanied by an increase in TOI as monitored by the NIRO 300 with an optode spacing of 5 cm but not with an optode spacing of 1.5 cm. Furthermore a direct relationship was seen between the V(mca) and the TOI measured at 5 cm optode spacing. This work suggests that using this commercial NIRS instrument with an optode spacing of 5 cm one is able to detect the intracranial changes.
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Review Historical Article
The evolution of the biomedical paradigm in oncology: implications for cancer therapy.
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The Risk Assessment Work Group focused on six charge questions related to CHABS, cyanobacteria and their toxins. The charge questions covered the following topics: Research needed to reduce uncertainty in establishing health based guidelines. Research that minimize the cost and maximize the benefits of various regulatory approaches. ⋯ Treatment can reduce the concentrations of both the toxins and the bacteria in the treated water but there is still much to be learned about the effectiveness of most treatment technologies on cyanobacteria and toxin removal. Human exposure to cyanobacteria and their toxins also occurs through incidental ingestion, dermal contact, and inhalation of aerosols during recreational use of surface waters, ingestion of contaminated fish and other foods of aquatic origin, and/or BGAS supplements. Establishing intakes and duration parameters for these exposure scenarios will facilitate the application of risk assessment approaches to these situations.
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Buprenorphine is relatively resistant to reversal by naloxone. We tested the effect of various doses and infusion schemes of naloxone on buprenorphine-induced respiratory depression and compared the data with naloxone-reversal of morphine and alfentanil-induced respiratory depression. ⋯ However, reversal was short-lived. The bell-shaped reversal curve may be related to the existence of two mu-opioid receptor subtypes, one mediating the agonist effects of opioids at low dose, the other mediating antagonistic effects at high dose.