Identification of a parathyroid hormone in the fish Fugu rubripes.

A PTH gene has been isolated from the fish Fugu rubripes. The encoded protein of 80 amino acid has the lowest homology with any of the PTH family members. Fugu PTH(1-34) had 5-fold lower potency than human PTH(1-34) in a mammalian cell system. INTRODUCTION: Parathyroid hormone (PTH) is the major hypercalcemic hormone in higher vertebrates. Fish lack parathyroid glands, but there have numerous attempts to identify and isolate PTH from fish. MATERIALS AND METHODS: Polymerase chain reaction (PCR) was performed with primers based on preliminary data from the Joint Genome Institute database. PCR amplification was performed on genomic DNA isolated from Fugu rubripes. PCR products were purified and DNA was sequenced. All sequence was confirmed from more than one independently amplified PCR product. Multiple sequence alignments were carried out, and the percentage of identities and similarities were calculated. An unrooted phylogenetic tree, using all the known PTH and PTH-related protein (PTHrP) amino acid sequences, was determined. Synthetic peptides were tested in a biological assay that measured cyclic adenosine 3',5'-monophosphate formation in UMR106.1 cells. Rabbit polyclonal antisera specific for N-terminal human PTHrP and one rabbit polyclonal antiserum specific for N terminus hPTH were used to test the cross-reactivity with fPTH(1-34) in immunoblots.     

Anxiolytic activity of adenosine receptor activation in mice.

1. Purine analogues have been examined for anxiolytic- and anxiogenic-like activity in mice, by use of the elevated plus-maze. 2. The selective A1 receptor agonist, N6-cyclopentyladenosine (CPA) had marked anxiolytic-like activity at 10 and 50 microg kg(-1), with no effect on locomotor performance at these doses. 3. The A1 selective adenosine receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (CPX) had no significant effect on anxiety-related measures or locomotor behaviour, but blocked the anxiolytic-like activity of CPA. The hydrophilic xanthine, 8-(p-sulphophenyl) theophylline did not prevent anxiolysis by CPA. 4. Caffeine had anxiogenic-like activity at 30 mg kg(-1) which was prevented by CPA at 50 micro kg(-1). 5. The A2 receptor agonist, N6-[2-(3,5-dimethoxyphenyl)-2(2-methylphenyl)-ethyl]adenosine (DPMA) had no effect on anxiety behaviour but depressed locomotor activity at the highest dose tested of 1 mg kg(-1). The A2 receptor antagonist, 1,3-dimethyl-l-propargylxanthine (DMPX) had no effect on anxiety-related measures or locomotion and did not modify the anxiolytic-like activity of CPA. 6. Administration of DPMA in combination with anxiolytic doses of CPA prevented the anxiolytic-like activity of the latter. 7. The results suggest that the selective activation of central A1 adenosine receptors induces anxiolytic-like behaviour, while the activation of A2 sites causes locomotor depression and reduces the effects of A1 receptor activation. The absence of any effect of CPX alone suggests that the receptors involved in modulating behaviour in the elevated plus-maze in mice are not activated tonically by endogenous adenosine.     

pH control in rat skeletal muscle during exercise,recovery from exercise,and acute respiratory acidosis

We used ³¹P magnetic resonance spectroscopy to compare the response of rat skeletal muscle to three kinds of proton load. During exercise (tetanic sciatic nerve stimulation), protons from lactic acid were buffered passively and consumed by net hydrolysis of phosphocreatine (PCr). During recovery from exercise, the pH-dependent efflux of protons produced by PCr resynthesis could be partially inhibited by amiloride or 4,4′-diisothiocyanostilbene-2,2′-disulphonate (DIDS), implicating both sodiudproton and bicarbonatelchloride exchange, but was not inhibited by simultaneous respiratory acidosis. In early recovery, up to 30% of proton efflux was mediated by lactatelproton cotransport. During acute respiratory acidosis at rest, the eventual change in muscle pH was consistent with passive buffering and was unaffected by amiloride or DIDS, implying no significant contribution of proton fluxes.     

The pharmacology of recombinant GABAA receptors containing bovine alpha 1, beta 1, gamma 2L sub-units stably transfected into mouse fibroblast L-cells.

1. Responses to gamma-aminobutyric acid (GABA) were evoked in mouse fibroblast L-cells stably transfected with bovine, alpha 1, beta 1, gamma 2L sub-units of the GABAA receptor. Expression was stimulated via a steroid-inducible promoter system. 2. In near symmetrical intracellular and extracellular chloride concentrations, GABA evoked inward currents at negative holding potentials that reversed at +5 mV and displayed slight outward rectification. Concentration-response curves were fitted well by the logistic equation. GABA had a pEC50 = 5.1 +/- 0.1 and the curves had a slope of 1.9 +/- 0.1. 3. Responses to GABA were antagonized by bicuculline, picrotoxin and penicillin. The action of bicuculline was competitive (pA2 = 6.4) whilst the block by picrotoxin was uncompetitive and strongly agonist-dependent. 4. Benzodiazepine receptor agonists potentiated responses to 3 microM GABA. The rank order of potency was FG 8205 > flunitrazepam > zolpidem > C1218872. FG 8205 and C1218872 produced markedly lower maximal potentiations with efficacies 0.4 and 0.6 x that of flunitrazepam, respectively. The potencies of zolpidem and C1218872 observed are in agreement with the BZ1 type pharmacology of this sub-unit combination. The potentiation of GABA by flunitrazepam was antagonized by flumazenil with a Ki of 3.8 nM. 5. GABA responses were potentiated in the presence of pentobarbitone and alphaxalone. The response was also noticeably broadened by these compounds due to a decrease in the response decay rate. Concentrations of pentobarbitone of 100 microM and above evoked an inward current in the absence of GABA. Alphaxalone up to 10 microM did not evoke a direct response.(ABSTRACT TRUNCATED AT 250 WORDS)     

Robot-assisted thoracoscopic brachytherapy for lung cancer: comparison of the ZEUS robot, VATS, and manual seed implantation.

OBJECTIVE: Interstitial brachytherapy is becoming an accepted treatment option for lung cancer patients for whom surgery poses a high risk. Robotic surgery has the potential to deliver brachytherapy seeds into tumors while keeping surgeons at a safe distance from the radioactive source. Our aim was to compare the accuracy, number of attempts, and time needed to place seeds next to a target when using a manual technique, video-assisted thoracoscopic surgery (VATS), and the ZEUS robot for minimally invasive surgery (MIS). METHODS: A brachytherapy seed injector was developed and attached to one of the ZEUS robotic arms. Four subjects each inserted inactive dummy brachytherapy seeds into clear agar-gelatin cubes containing a 1.6-mm stainless steel ball target. Two orthogonal radiographs were taken of each agar cube, and the corresponding distances were measured in triplicate using ImageJ processing software. The mean distance between the center of each seed and the corresponding target was calculated using the Pythagorean theorem. Comparisons were made using analysis of variance, t-tests, and Kruskal-Wallis tests, as appropriate. RESULTS: A total of 384 tests (128 for each technique) were performed. The median accuracies for the manual technique, VATS, and ZEUS were 1.8 mm (range: 0.9-6.7 mm), 2.4 mm (range: 1.0-11.3 mm), and 3.6 mm (range: 1.3-16.7 mm), respectively (p < 0.01). The median numbers of attempts for the manual technique, VATS, and ZEUS were 1 (range: 1-5), 4 (range: 1-14), and 3 (range: 1-20), respectively (p < 0.01). The median times for the manual technique, VATS, and ZEUS were 3.0 s (range: 1-43 s), 86.5 s (range: 6-372 s), and 64.5 s (range: 5-356 s), respectively (p < 0.01). CONCLUSIONS: The manual technique is the most accurate, least traumatic, and fastest method of inserting seeds into tumors. The ZEUS robotic platform was able to place seeds beside a target within a clinically acceptable distance, with an acceptable amount of trauma and time required. It achieved results equal to or better than those obtained with VATS.