Biomedical subjects

J Mitchell

Publications and source records attributed to J Mitchell.

500 records · Page 28Linked to original sources

PubMedDate not supplied

cDNA cloning and characterization of a novel squid rhodopsin kinase encoding multiple modular domains.

Rhodopsin phosphorylation is one of the key mechanisms of inactivation in vertebrate and invertebrate visual signal transduction. Here we report the cDNA cloning and protein characterization of a 70-kDa squid rhodopsin kinase, SQRK. The cDNA encoding the 70-kDa protein demonstrates high sequence identity with octopus rhodopsin kinase (92%) and mammalian beta-adrenergic receptor kinases (63-65%), but only 33% similarity with bovine rhodopsin kinase, suggesting that invertebrate rhodopsin kinases may be structurally similar to beta-adrenergic receptor kinases. This cDNA encodes three distinct modular domains: RGS, S/TKc, and PH domains. The native SQRK is an eye-specific protein that is only expressed in photoreceptor cells and the optic ganglion as determined by immunoblotting. Purified SQRK is able to phosphorylate both squid and bovine rhodopsin. Squid rhodopsin phosphorylation by purified SQRK was sensitive to both Mg2+ and GTPgammaS but was insensitive to Ca2+/CaM regulation. The ability of SQRK to phosphorylate rhodopsin was totally lost in the presence of SQRK-specific antibodies. Our results suggest that SQRK plays an important role in squid visual signal termination.

Amino Acid Sequence↗

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An evaluation of epidural bupivacaine with and without meperidine in labor.

BACKGROUND: One aim of epidural analgesia during childbirth is to provide satisfactory pain relief with minimal side effects. We hypothesized that a combination of opioid and local anesthetic would better achieve this aim than either drug alone. This study compared the efficacy and side effects of epidural meperidine and bupivacaine combined to those of meperidine and bupivacaine alone. METHODS: One hundred consenting nulliparas requesting epidural analgesia in labor were randomly assigned to receive, in a double-blind fashion, one of five treatments. These were 25 mg meperidine, 12.5 mg bupivacaine, 25 mg meperidine plus 12.5 mg bupivacaine, 25 mg bupivacaine, and 37.5 mg bupivacaine. Efficacy of analgesia and side effects were assessed before and after each dose. Leg strength was measured with a force meter and blood flow to each foot with a blood perfusion monitor. The neurobehavioral state of the newborn was assessed by a pediatrician who was blind to treatment using a neurologic and adaptive capacity scoring system. RESULTS: Thirty-seven women did not achieve satisfactory analgesia after the first dose of test medication; these predominantly were those who received 25 mg meperidine (n = 12) or 12.5 mg bupivacaine (n = 11). Nausea decreased after the initial dose with all treatments (p less than 0.01), whereas shivering increased in patients receiving bupivacaine (p less than 0.01). There was a reduction in leg strength and an increase in blood flow associated with the two higher bupivacaine treatments (p less than 0.01), and with both parameters the dependent limb was most affected. Overall patient satisfaction was greatest in the group receiving meperidine plus bupivacaine. Neonatal neurologic and adaptive capacity scores did not differ significantly among the treatment groups. CONCLUSION: The low-dose combination of meperidine and bupivacaine used in this trial proved a satisfactory preparation for epidural administration during the early stages of labor.

Adult↗

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