Endothermic force generation, temperature-jump experiments and effects of increased [MgADP] in rabbit psoas muscle fibres   总被引：2，自引：1，他引：1  

M. E. Coupland  G. J. Pinniger  K. W. Ranatunga 《The Journal of physiology》2005,567(2):471-492

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Crossbridge and non-crossbridge contributions to tension in lengthening rat muscle: force-induced reversal of the power stroke   总被引：5，自引：1，他引：4  

G. J. Pinniger  K. W. Ranatunga  G. W. Offer 《The Journal of physiology》2006,573(3):627-643

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Pressure-induced changes in the isometric contractions of single intact frog muscle fibres at low temperatures     

F. Vawda  K. W. Ranatunga  M. A. Geeves 《Journal of muscle research and cell motility》1995,16(4):412-419

Summary Effects of increased hydrostatic pressure (range 0.1–10 MPa) on isometric twitch and tetanic contractions of single intact muscle fibres, isolated from frog tibialis anterior muscle, were examined at 4–12° C. The tension changes produced on exposure to steady high pressures are compared with those produced on exposure to low concentrations of caffeine (0.5 mm, subthreshold for contracture) and when pressure is rapidly released during a contraction. The peak twitch tension was potentiated by pressure accompanied by increased rate of tension rise and increased duration; the pressure sensitivity of twitch tension was 8% mPa^-1. The correlation between the rate of tension rise and peak tension in caffeine-induced twitch tension potentiation was quantitatively similar to that in pressure-induced twitch potentiation. Experiments involving the rapid release of pressure (2 ms) during twitch contractions demonstrate that high pressure need only be maintained for a brief period during the early part of tension development to elicit full twitch potentiation. The tetanic tension was depressed by pressure (1% MPa^-1). Results demonstrate that the major effect of increased hydrostatic pressure on intact muscle fibres, which results in tension potentiation, is complete very early during contraction and is similar to that of caffeine.  相似文献   

Apoptotic U1-70 kd is antigenically distinct from the intact form of the U1-70-kd molecule   总被引：2，自引：0，他引：2  

Greidinger EL  Foecking MF  Ranatunga S  Hoffman RW 《Arthritis and rheumatism》2002,46(5):1264-1269

OBJECTIVE: To determine whether immune responses to an apoptotically modified form of a human lupus autoantigen can be distinguished from immune responses to the intact form of the same antigen. METHODS: Immunoblot and enzyme-linked immunosorbent assay techniques were used to test human autoimmune sera for the presence of antibodies to apoptotic forms of the U1- 70-kd small nuclear RNP antigen, while antibody recognition of intact U1-70 kd was blocked. RESULTS: poptosis-specific U1-70-kd antibodies were identified by immunoblot in 15 of 29 sera with antibodies to intact U1-70 kd and in 2 of 25 sera without measurable antibodies to intact U1-70 kd. Bacterially produced, purified, caspase-cleaved U1-70 kd without additional posttranslational modifications was a target of apoptosis-specific antibodies in 3 of 9 U1-70-kd-positive sera tested. CONCLUSION: The apoptotic form of U1-70 kd displays B cell epitopes that are not displayed on the intact form of U1-70 kd. Caspase cleavage in the absence of additional posttranslational modifications is sufficient to induce the display of some of these epitopes. Immunity to apoptotically modified proteins can develop against caspase-cleaved forms or against forms that undergo additional posttranslational modification.  相似文献   

Upper-air observation indicators predict outbreaks of asthma exacerbations among elementary school children: integration of daily environmental and school health surveillance systems in Pennsylvania     

Youssefagha AH  Lohrmann DK  Jayawardene WP  El Afandi GS 《The Journal of asthma》2012,49(5):464-473

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Percutaneous fluoroscopic removal of a knotted Swan–Ganz catheter in a patient with a persistent left‐sided superior vena cava     

DG Ranatunga  MG Richardson  DM Brooks 《Journal of Medical Imaging and Radiation Oncology》2007,51(2):182-185

Knotting of intravascular catheters is an uncommon but a well‐recognized occurrence. The Swan–Ganz catheter (SGC) is the one that knots most commonly. A case of a knotted SGC is described in a patient with a persistent left‐sided superior vena cava, and we propose that the presence of a left‐sided superior vena cava is a risk factor for knot formation not previously reported. We review the published work on the risk factors for knot formation and on the techniques used to remove knotted SGC. We describe a technique using a gooseneck snare and Omni Flush catheter (Angiodynamics, Queensbury, NY, USA) to loosen and untie a knotted SGC.  相似文献   

Differentiation of fast and slow muscles in the rat after neonatal denervation: A physiological study     

M. H. Elmubarak  K. W. Ranatunga 《Journal of muscle research and cell motility》1988,9(3):219-232

Summary Whether an intact innervation is essential for postnatal muscle differentiation was examined in the rat by recording physiological contraction parameters. Muscles in one leg were denervated neonatally (within 24 h of birth) and, between 3–28 days after the operation, their contractions were compared with those of the contralateral control muscles. Experiments were performed on the extensor digitorum longus (edl, a fast muscle) and the soleus (a slow muscle) muscles and contractions were recordedin vitro, at 35 C and with direct stimulation. When compared with the control muscles, 3–4-day-old neonatally denervated fast and slow muscles had longer twitch contractions, higher twitch/tetanus ratios and certain other specific differences in their contraction parameters. These denervation-induced changes in neonatal muscles were essentially similar to those produced 3–7 days after denervation in the differentiated (4-week-old) fast muscle. Despite differences in their absolute values, the contraction parameters of neonatally denervated and control edl muscles changed similarly during development, indicating that postnatal differentiation of fast muscle fibres is independent of a neuronal influence. In the case of the neonatally denervated soleus muscle, the developmental changes in contraction parameters, i.e. shortening of the twitch duration, increase of rate of rise and rate of relaxation in the tetanus and increase of the maximum shortening velocity, were more pronounced than in the control slow muscle; also, there were similarities with the pattern of fast muscle differentiation. Thus, muscle fibre differentiation in soleus becomes altered towards that of a fast muscle after neonatal denervation.  相似文献   

Acute human self-poisoning with the N-phenylpyrazole insecticide fipronil--a GABAA-gated chloride channel blocker   总被引：3，自引：0，他引：3  

Mohamed F  Senarathna L  Percy A  Abeyewardene M  Eaglesham G  Cheng R  Azher S  Hittarage A  Dissanayake W  Sheriff MH  Davies W  Buckley NA  Eddleston M 《Journal of toxicology. Clinical toxicology》2004,42(7):955-963

OBJECTIVE: Fipronil, a broad spectrum N-phenylpyrazole insecticide that inhibits GABAA-gated chloride channels, has been in use since the mid-1990s. A high affinity for insect compared to mammalian GABA receptors results in lower animal toxicity than other insecticides blocking this channel. To date, only two accidental cases of fipronil poisoning in humans have been published. CASE SERIES: We report seven patients with fipronil self-poisoning seen prospectively in Sri Lanka together with pharmacokinetics for four patients. Non-sustained generalized tonic-clonic seizures were seen in two patients (peak measured plasma fipronil concentrations 1600 and 3744 microg/L); both were managed with diazepam without complications. A patient with a peak measured plasma concentration of 1040 microg/L was asymptomatic throughout his stay. Plasma concentration was still high at discharge 3-4 days post-ingestion when the patients were well. Retrospective review of >1000 pesticide poisoning deaths since 1995 found only one death from fipronil-based products. In contrast to the good outcome of the above cases, this patient required intubation and ventilation and had continuous fits despite therapy with barbiturates and benzodiazepines. CONCLUSIONS: Our experience with prospectively observed patients suggests that fipronil poisoning is characterized by vomiting, agitation, and seizures, and normally has a favorable outcome. Management should concentrate on supportive care and early treatment of seizures. However, further experience is needed to determine whether increased susceptibility to fipronil or larger doses can produce status epilepticus.  相似文献   

What are the roles of the many different types of potassium channel expressed in cerebellar granule cells?     

Mathie A  Clarke CE  Ranatunga KM  Veale EL 《Cerebellum (London, England)》2003,2(1):11-25

Potassium (K) channels have a key role in the regulation of neuronal excitability. Over a hundred different subunits encoding distinct K channel subtypes have been identified so far. A major challenge is to relate these many different channel subunits to the functional K currents observed in native neurons. In this review, we have concentrated on cerebellar granule neurons (CGNs). We have considered each of the three principal super families of K channels in turn, namely, the six transmembrane domain, voltage-gated super family, the two transmembrane domain, inward-rectifier super family and the four transmembrane domain, leak channel super family. For each super family, we have identified the subunits that are expressed in CGNs and related the properties of these expressed channel subunits to the functional currents seen in electrophysiological recordings from these neurons. In some cases, there are strong molecular candidates for proteins underlying observed currents. In other cases the correlation is less clear. We show that at least 26 potassium channel alpha subunits are moderately or strongly expressed in CGNs. Nevertheless, a good empirical model of CGN function has been obtained with just six distinct K conductances. The transient KA current in CGNs, seems due to expression of Kv4.2 channels or Kv4.2/4.3 heteromers, while the KCa current is due to expression of large-conductance slo channels. The G-protein activated KIR current is probably due to heteromeric expression of KIR3.1 and KIR3.2. Perhaps KIR2.2 subunits underlie the KIR current when it is constitutively active. The leak conductance can be attributed to TASK-1 and or TASK-3 channels. With less certainty, the IK-slow current may be due to expression of one or more members of the KCNQ or EAG family. Lastly, the delayed-rectifier Kv current has as many as six different potential contributors from the extensive Kv family of alpha subunits. Since many of these subunits are highly regulated by neurotransmitters, physiological regulators and, often, auxiliary subunits, the resulting electrical properties of CGNs may be highly dynamic and subject to constant fine-tuning.  相似文献   

Dietary intake of vitamin E and folic acid in a defined population in Sri Lanka     

Mendis S  Bulugahapitiya DU  Ranatunga PK  Gunawardene PR  Kandegedera PG 《The Ceylon medical journal》1999,44(1):25-27

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