Naloxone reduces ventilatory depression of brain hypoxia

To assess whether endogenous opioids participate in respiratory depression due to brain hypoxia, we determined the ventilatory response to progressive carboxyhemoglobinemia (1% CO, 40% O2) before and after administration of naloxone (NLX, 0.1 mg/kg iv). Minute ventilation (VI) and ventral medullary surface pH (Vm pH) were measured in six anesthetized, peripherally chemodenervated cats. NLX consistently increased base-line hyperoxic VI from 618 +/- 99 to 729 +/- 126 ml/min (P less than 0.05). Although NLX did not alter the Vm pH response to CO [initial alkalosis, Vm pH +0.011 +/- 0.003 pH units, followed by acidosis, Vm pH -0.082 +/- 0.036 at carboxyhemoglobin (HbCO) 55%], NLX attenuated the amount of ventilatory depression; increasing HbCO to 55% decreased VI to 66 +/- 6% of base line before NLX and to 81 +/- 9% of base line after NLX (P less than 0.05). The difference in response after NLX was primarily the result of a linear increase in tidal volume (VT) with decreasing Vm pH (delta VT = 60.3 ml/-pH unit) which was absent before NLX. To assess whether the site of action of the endogenous opioid effect was the central chemosensors, the ventilatory and Vm pH response to progressive HbCO was determined in three additional cats before and after topical application of NLX (3 X 10(-4) M) to the ventral medullary surface. The effect of topical NLX was similar to systemic NLX; significant attenuation of the reduction in VI with increasing HbCO. We conclude that 1) endogenous opioids mediate a portion of the depression of ventilation due to acute brain hypoxia, and 2) this effect is probably at the central chemosensitive regions.     

Reversal of sucrose inhibition of Lemna flowering by adenine derivatives

Sucrose inhibition of flowering in Lemna perpusilla 6746 wasat least partially reversed by 5'-AMP, cyclic 3',5'-AMP, 5'-ADP,5'-ATP and K₂HPO₄. These results are in contrast to those reportedfor L. gibba in which reversal was effected by cyclic AMP, butnot by other adenine derivatives. ¹ This work was supported by National Science Foundation GrantGB-12955. (Received June 11, 1973; )     

How the Enga Cope with Frost in the 21st Century: Food Insecurity,Migration, and Development in the Papua New Guinea Highlands

Human Ecology - We use a mixed methods approach to examine high-altitude subsistence horticulturalists’ responses to food insecurity caused by El Niño related droughts and frosts in the...     

Tyrphostins inhibit the epidermal growth factor receptor-mediated breakdown of phosphoinositides

In response to epidermal growth factor (EGF) and the Ca2+ ionophore A23187, the total phosphatidylinositides (IPT) increased in A431 human epidermoid carcinoma cells 1.8- and 2.0-fold and in the EGF-dependent A431/Clone 15-2 cells 3.0- and 8.0-fold, respectively, over basal levels. Both responses were inhibited by the antiproliferative agents tyrphostins, but the EGF-induced increase in IPT was inhibited to a much greater extent than that induced by the ionophore. Tyrphostins which are potent EGF-receptor kinase inhibitors were also potent in blocking the EGF-induced production of phosphoinositides. The less potent tyrphostins were found to inhibit the EGF-dependent IPT formation more weakly. These results support the notion that phospholipase C is activated through its phosphorylation by the EGF receptor.     

HuD, a paraneoplastic encephalomyelitis antigen, contains RNA-binding domains and is homologous to Elav and Sex-lethal.

A neuronal antigen (HuD) recognized by the sera of patients with antibody-associated paraneoplastic encephalomyelitis has been isolated by screening a lambda cerebellar expression library. The recombinant antigen provides an unambiguous assay for this rare condition associated with small cell lung cancer. The recombinant antigen has been used to identify specific infiltrating lymphocytes in tumors and affected brain tissues of patients with antibody-associated paraneoplastic encephalomyelitis and sensory neuronopathy. HuD mRNA is uniquely expressed in brain tissue. The HuD protein shows a remarkable homology to the Drosophila proteins Elav and Sex-lethal and is likely to play a role in neuron-specific RNA processing.