Lunar and tidal periodicity of molting and reproduction in stomatopod crustacea: a selfish herd hypothesis     

ML Reaka 《Canadian Metallurgical Quarterly》1976,150(3):468-490

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RL Gamble  ML Coonfield  GE Schaller 《Canadian Metallurgical Quarterly》1998,95(13):7825-7829

ETR1 represents a prototypical ethylene receptor. Homologues of ETR1 have been identified in Arabidopsis as well as in other plant species, indicating that ethylene perception involves a family of receptors and that the mechanism of ethylene perception is conserved in plants. The amino-terminal half of ETR1 contains a hydrophobic domain responsible for ethylene binding and membrane localization. The carboxyl-terminal half of the polypeptide contains domains with homology to histidine kinases and response regulators, signaling motifs originally identified in bacteria. The putative histidine kinase domain of ETR1 was expressed in yeast as a fusion protein with glutathione S-transferase and affinity purified. Autophosphorylation of the purified fusion protein was observed on incubation with radiolabeled ATP. The incorporated phosphate was resistant to treatment with 3 M NaOH, but was sensitive to 1 M HCl, consistent with phosphorylation of histidine. Autophosphorylation was abolished by mutations that eliminated either the presumptive site of phosphorylation (His-353) or putative catalytic residues within the kinase domain. Truncations were used to delineate the region required for histidine kinase activity. An examination of cation requirements indicated that ETR1 requires Mn2+ for autophosphorylation. These results demonstrate that higher plants contain proteins with histidine kinase activity. Furthermore, these results indicate that aspects of ethylene signaling may be regulated by changes in histidine kinase activity of the receptor.  相似文献   

    

R Ruiz-Maldonado  L Tamayo-Sanchez  ML Orozco-Covarrubias 《Canadian Metallurgical Quarterly》1998,16(3):553-569

Oral retinoids are molecules derived from vitamin A that represent one of the most important steps forward in dermatologic therapeutics in the present century. The treatment of acne, severe psoriasis, and severe disorders of keratinization, prevalent diseases in children and adolescents, have radically changed since the advent of oral retinoids. Like most highly-effective medications, oral retinoids also have important untoward effects. Specialists, and in particular, dermatologists and pediatricians should be prepared to maneuver the delicate balance between therapeutic efficacy and side effects in order to give the pediatric patient the maximum benefit with the lowest possible risk.  相似文献   

    

J Karjalainen  A Kanervo  ML V?is?nen  B Forsblom  E Sarkiala  H Jousimies-Somer 《Canadian Metallurgical Quarterly》1993,6(2-3):207-212

A total of 259 Gram-negative Porphyromonas-like rods isolated from subgingival plaque samples of 16 family-owned dogs with naturally occurring periodontitis were characterized phenotypically by biochemical reactions, metabolic end products and enzymatic activities (API-ZYMTM, RoscoTM). Four distinct groups were found. Group A isolates (63) were asaccharolytic, lipase negative, trypsin positive and produced phenylacetic acid (PAA) from peptone-yeast extract glucose broth. Unlike P. gingivalis strains they were catalase positive. Group B isolates (42) differed from those of group A by a positive lipase reaction and from those of group D by failing to ferment sugars. Group C isolates (88) were asaccharolytic and did not produce PAA. They were alpha-fucosidase, N-acetyl-beta-glucosaminidase (beta-NAG) and trypsin negative, resembling P. endodontalis, but unlike human isolates, they were catalase positive. Subgroup C.1 isolates (6) differed from those of parent group C by producing minor amounts of PAA, and subgroup C.2 isolates (12) were beta-NAG positive. Group D isolates (46) were weakly fermentative, lipase, catalase and trypsin positive, and produced PAA. They resembled the B (P.) salivosus type strain which, in our hands, fermented weakly glucose, lactose and mannose. Two isolates could not be assigned to any of the previous groups.  相似文献   

    

F Pregliasco  V Minolfi  A Boschin  A Andreassi  ML Profeta 《Canadian Metallurgical Quarterly》1995,11(6):693-695

In a seroepidemiological study performed to investigate immunity against poliomyelitis in a population of drug addicts in a rehabilitative residential centre we demonstrated a widespread lack of poliovirus neutralizing antibodies. This was more evident in the HIV positive subjects, 27% of whom were seronegative for poliovirus type 1, 27% for type 2 and 34% for type 3, with 11% seronegative for all three types. These results indicate a gap in immunity to poliomyelitis in the examined population.  相似文献   

    

CR Doering  TS Ray  ML Glasser 《Canadian Metallurgical Quarterly》1992,45(2):825-828

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GH Chen  LM Kuang  ML Ge 《Canadian Metallurgical Quarterly》1996,53(15):9540-9543

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MR Ujhelyi  AP Winecoff  M Schur  T Frede  MB Bottorff  M Gabel  ML Markel 《Canadian Metallurgical Quarterly》1996,110(3):784-790

BACKGROUND: Transplantation of lung allografts from the same donor into 2 recipients (\"twinning\") provides an opportunity to study recipient and donor factors that influence early allograft function. METHODS: Twenty-seven pairs of recipients were identified and evaluated using multivariate logistic regression analysis (p < 0.05). Four measures of early graft function were analyzed: alveolar-arterial gradient in the operating room, first alveolar-arterial gradient in the intensive care unit, alveolar-arterial gradient at 24 hours, and days of mechanical ventilation. RESULTS: Analysis of the pooled data without regard to pairing showed that alveolar-arterial gradient in the operating room was influenced by donor age, length of donor hospitalization, recipient mean pulmonary artery (PA) pressure at unclamping, and transplantation of a left lung. The alveolar-arterial gradient in the intensive care unit was correlated with donor age, donor cause of death, and mean PA pressure on arrival in that unit. Only mean PA pressure remained significant at 24 hours. Days of mechanical ventilation was determined by mean PA pressure on arrival in the intensive care unit, drop in mean PA pressure during operation, and diagnosis of the recipient. In the paired analysis, receiving a left lung, recipient diagnosis (pulmonary hypertension worse than others), and need of cardiopulmonary bypass were significantly associated with immediate graft dysfunction, although these influences did not persist beyond the immediate postoperative period. Donor arterial oxygen tension and time of ischemia were not significant predictors in any analysis. CONCLUSIONS: Immediate allograft function was associated with donor-related characteristics initially, but these lost importance over the ensuing 24 hours. Recipient PA pressure was an immediate and persisting influence. In the analysis of differences in function between the members of each pair, transplantation of the left lung, recipient diagnosis, and cardiopulmonary bypass were identified, but their influence did not persist beyond the first 6 hours.  相似文献   

    

BC Hilman  ML Aitken  M Constantinescu 《Canadian Metallurgical Quarterly》1996,39(1):70-86

With increasing life span of patients with CF, more women with CF are becoming pregnant and others are seeking information about the risks involved during pregnancy and delivery. A striking limitation of the available information is the lack of large prospective studies of pregnant patients with CF matched for age and disease severity compared with their non-pregnant cohorts. A study investigating the effect of pregnancy on morbidity and mortality is being completed by the Cystic Fibrosis Foundation. We recommend that all women with CF be offered contraceptive measures and counseling on the maternal and fetal risks of pregnancy, including the genetic risks for the child. The issue of who will raise the child in the event of subsequent morbidity or maternal mortality should ideally be prospectively discussed.  相似文献   

    

YJ Zhao  J Wang  ML Tod  LJ Rubin  XJ Yuan 《Canadian Metallurgical Quarterly》1996,81(6):2595-2603

Endogenous prostacyclin (PGI2; epoprostenol) is a potent endothelium-derived pulmonary vasodilator. However, the effects of exogenous PGI2 on isolated arteries could be either relaxant or contractile, depending on the species and organ studied. The present study investigated the distal pathways involved in the PGI2-induced contraction in rat intrapulmonary artery (PA) and relaxation in lamb PA. When vessels were precontracted with 30 mM K+, PGI2 (1 microM) induced relaxation in lamb PA but caused contraction in rat PA. Use of 30 mM K+, phenylephrine, serotonin, angiotensin II, or hypoxia to precontract the vessels did not alter the contractile effect of PGI2 in rat PA. Nevertheless, PGI2 produced a mild relaxation in rat PA precontracted by U-46619, a thromboxane A2 (TxA2)-receptor agonist, whereas the TxA2-receptor blocker SQ-29548 (0.1-0.5 microM) abolished the contractile response in rat PA. These data suggest that PGI2-induced contraction is mediated by activation of TxA2 receptors. The PGI2-induced modest relaxation in rat PA, which was only observed when TxA2 receptors were blocked by SQ-29548, suggests that the PGI2-mediated vasorelaxant pathway is diminished in these vessels. Simultaneous application of forskolin, an adenylate cyclase activator, and rolipram, a phosphodiesterase inhibitor, caused similar relaxation in both rat and lamb PA. This suggests that the adenosine 3',5'-cyclic monophosphate-dependent relaxing pathway is intact in rat PA and is comparable to that in lamb PA. On the basis of these data, we conclude that the pathways responsible for the paradoxical effects of PGI2 on rat and lamb PA are located upstream of the adenosine 3',5'-cyclic monophosphate-dependent relaxing pathway and that a paucity of PGI2 receptors in rat PA may be responsible.  相似文献