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Jones MV, Harrison NL. Effects of volatile anesthetics on the kinetics of inhibitory postsynaptic currents in cultured rat hippocampal neurons. J Neurophysiol 1993; 70:1339-49. [PMID: 7506753 DOI: 10.1152/jn.1993.70.4.1339] [Citation(s) in RCA: 135] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
1. The effects of the volatile anesthetics enflurane, halothane, and isoflurane on gamma-aminobutyric acid (GABA) receptor-mediated inhibitory postsynaptic currents (IPSCs) were studied in cultured rat hippocampal neurons. The experimental concentrations of anesthetics were measured directly using gas chromatography. All three anesthetics increased the overall duration of IPSCs, measured as the time to half-decay (T1/2). Clinically effective concentrations of anesthetics [between 0.5 and 1.5 times MAC (minimum alveolar concentration)] produced between 100 and 400% increases in T1/2. These effects were fully reversible, and did not involve alterations in the reversal potential for the IPSC (EIPSC). 2. The decay of the IPSC was fitted as a sum of two exponential functions, yielding a fast component (tau fast = 20 ms), and a slow component (tau slow = 77 ms), such that the fast component accounted for 79% of the IPSC amplitude and 52% of the total charge transfer. All three anesthetics produced concentration-related increases in the amplitude and charge transfer of the slow component, while simultaneously decreasing the amplitude and charge transfer of the fast component. Thus T1/2 approximated tau fast under control conditions, but approximated tau slow in the presence of the anesthetics. 3. Varying the calcium chelating agents in the recording pipettes had no effect on the quality or magnitude of alterations in IPSC kinetics produced by halothane, suggesting that variations in intracellular calcium levels are not required for the effect of halothane on the time course of the IPSC. 4. The (+)-stereoisomer of isoflurane produced greater increases in the duration of the IPSC than the (-)-isomer when applied at approximately equal concentrations, suggesting that there is a structurally selective site of interaction for isoflurane that modulates the GABAA receptor. 5. These results suggest that the previously shown abilities of volatile anesthetics to potentiate responses to exogenously applied GABA and to prolong the duration of GABA-mediated synaptic inhibition may be due to an alteration in the gating kinetics of the GABAA receptor/channel complex. Prolongation of synaptic inhibition in the CNS is consistent with the physiological effects that accompany anesthesia and may contribute to the mechanism of anesthetic action.
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Harrison NL, Kugler JL, Jones MV, Greenblatt EP, Pritchett DB. Positive modulation of human gamma-aminobutyric acid type A and glycine receptors by the inhalation anesthetic isoflurane. Mol Pharmacol 1993; 44:628-32. [PMID: 7690453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The interactions of the inhalation anesthetic agent isoflurane with ligand-gated chloride channels were studied using transient expression of recombinant human receptors in a mammalian cell line. Isoflurane enhanced gamma-aminobutyric acid (GABA)-activated chloride currents in cells that expressed heteromeric GABAA receptors consisting of combinations of alpha 1 or alpha 2, beta 1, and gamma 2 subunits and in cells that expressed receptors consisting of combinations of only alpha and beta subunits. Receptors consisting of alpha 2 and gamma 2 subunits were poorly expressed but were sensitive to isoflurane. Receptors consisting of beta 1 and gamma 2 subunits were not expressed. Isoflurane also enhanced glycine-activated chloride currents through homomeric alpha glycine receptors but did not enhance GABA currents in cells expressing homomeric rho 1 receptors. These results show that not all ligand-gated chloride channel receptors are sensitive to isoflurane and, therefore, that the anesthetic interacts with specific structural determinants of these ion channel proteins.
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Lovinger DM, Zimmerman SA, Levitin M, Jones MV, Harrison NL. Trichloroethanol potentiates synaptic transmission mediated by gamma-aminobutyric acidA receptors in hippocampal neurons. J Pharmacol Exp Ther 1993; 264:1097-103. [PMID: 8383736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
We have examined the actions of trichloroethanol (TCEt), the active metabolite of the general anesthetic chloral hydrate, on responses mediated by gamma-aminobutyric acid (GABA)A receptors in response to application of exogenous GABA and activation of endogenous GABAergic transmission, by using hippocampal neurons in cell culture and in brain slices. In the presence of TCEt, Cl- current activated by exogenous GABA was both enhanced in amplitude and prolonged, leading to a net increase in total charge passing through GABAA receptor channels. Prolongation of GABA-activated current increased in magnitude in a concentration-dependent manner from 0.2 to 10 mM TCEt. Inhibitory postsynaptic currents produced at synapses between pairs of cultured GABAergic neurons or by activation of interneurons in hippocampal slices were also prolonged by TCEt, at concentrations from 0.5 to 10 mM. Application of TCEt at concentrations of 1 mM and above produced a small amplitude current which was directed outwardly at -40 mV in neurons in which methylsulfate or gluconate was the major intracellular anion and directed inwardly in neurons filled with Cl-. Our observations indicate that TCEt potentiates GABAergic transmission; presumably by potentiating the function of GABAA receptors in a manner similar to barbiturate or steroid anesthetics. This action is likely to contribute to the general anesthetic effect of TCEt which occurs after chloral hydrate administration.
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Stephens PJ, Jones MV. Reduced ribosomal thermal denaturation in Listeria monocytogenes following osmotic and heat shocks. FEMS Microbiol Lett 1993; 106:177-82. [PMID: 8454183 DOI: 10.1111/j.1574-6968.1993.tb05955.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Increased thermotolerance of Listeria monocytogenes induced by exposure to a high NaCl concentration or a sublethal heat shock was concurrent with increased thermal stability of the 30S ribosomal subunit as measured by differential scanning calorimetry. It is proposed that protection of the 30S subunit is a critical mechanism for increased thermotolerance.
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Coote PJ, Jones MV, Edgar K, Cole MB. TPK gene products mediate cAMP-independent thermotolerance in Saccharomyces cerevisiae. JOURNAL OF GENERAL MICROBIOLOGY 1992; 138:2551-7. [PMID: 1336794 DOI: 10.1099/00221287-138-12-2551] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Incubation of Saccharomyces cerevisiae with the plant cytokinin N6-(delta 2-isopentenyl)adenine (2iP) resulted in an induction of thermotolerance similar to that induced by sublethal temperatures. Intracellular cAMP levels did not change significantly either during incubation at a sublethal temperature or in the presence of 2iP or ethanol. This suggested that stress-induced thermotolerance is triggered by a mechanism independent of cAMP activation. However, measurement of stress-induced thermotolerance in two mutant strains (tpk1, tpk2, TPK3; tpk1, TPK2, tpk3) each deficient in two of the catalytic subunits of the cAMP-dependent protein kinase (cAPK), revealed that sublethal heat induces thermotolerance by a mechanism part-mediated by the catalytic subunits of cAPK. In contrast, 2iP and ethanol induced thermotolerance by a mechanism fully dependent on the catalytic subunits of cAPK for expression. Therefore, this implies there must be an alternative novel mechanism, other than cAMP, for activating cAPK during stress. Sublethal heating resulted in large increases in intracellular trehalose levels which correlated with the induction of thermotolerance. However, incubation in 2iP or ethanol had no significant effect. This suggests trehalose synthesis is either coincidental with heat stress or that different stress factors induce thermotolerance by alternative mechanisms. Incubation with protein synthesis inhibitors reduced the levels of trehalose synthesized during sublethal heating, suggesting that synthesis of trehalose-6-phosphate synthase during heat stress could be accounting for the increased trehalose levels.
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Jones MV, Brooks PA, Harrison NL. Enhancement of gamma-aminobutyric acid-activated Cl- currents in cultured rat hippocampal neurones by three volatile anaesthetics. J Physiol 1992; 449:279-93. [PMID: 1326046 PMCID: PMC1176079 DOI: 10.1113/jphysiol.1992.sp019086] [Citation(s) in RCA: 131] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
1. The effects of the volatile anaesthetics enflurane, halothane and isoflurane on gamma-aminobutyric acid (GABA)A receptor-mediated chloride currents were studied in cultured rat hippocampal neurones. Transient current responses were obtained by brief pressure application of GABA to the cell body of neurones under voltage clamp. 2. All three anaesthetics increased the peak amplitude and duration of current 2. All three anaesthetics increased the peak amplitude and duration of current responses to brief applications of GABA. These effects were fully reversible, and did not involve alterations in the reversal potential for GABA responses. 3. The experimental concentrations of anaesthetics were measured directly using gas chromatography. The enhancement of GABA currents increased with increasing anaesthetic concentration. Clinically effective concentrations of anaesthetics (between 1 and 1.5 times MAC (minimum alveolar concentration) produced significant enhancement of GABA currents. 4. These results demonstrate that the changes in the time course of synaptic inhibition reported in the presence of the volatile anaesthetics are likely to result from modification of the function of postsynaptic GABAA receptor-channel complexes. These findings also support the hypothesis that GABAA receptor complexes serve as common molecular target sites for a variety of structurally diverse anaesthetic molecules.
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Coote PJ, Cole MB, Jones MV. Induction of increased thermotolerance in Saccharomyces cerevisiae may be triggered by a mechanism involving intracellular pH. JOURNAL OF GENERAL MICROBIOLOGY 1991; 137:1701-8. [PMID: 1835495 DOI: 10.1099/00221287-137-7-1701] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Incubation of Saccharomyces cerevisiae at sub-lethal temperatures results in an increase in thermotolerance. This process is dependent not only on the sub-lethal temperature but also on the duration of sub-lethal heating. This indicates that the mechanism inducing thermotolerance is a time/temperature dose response. Other factors that induce thermotolerance include exposure to ethanol, sorbic acid and low external pH values. These factors induce thermotolerance after incubation in the presence of protein synthesis inhibitors, and they are all known to affect the intracellular pH (pHi). The acquisition of increased thermotolerance is minimal with sub-lethal heating under neutral external pH conditions. However, when the external pH is reduced to 4.0 the level of induced thermotolerance increases to a maximum value. Using a specific ATPase inhibitor, diethylstilboestrol (DES), ATPase activity was shown to be essential for the cell to survive heat stress. In addition, measurement of acid efflux, or ATPase activity, revealed that proton pumping from the cell increased by approximately 50% at sublethal temperatures that induce thermotolerance. This work has clearly implicated pHi perturbation as the triggering mechanism conferring thermotolerance on S. cerevisiae.
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Anderson WA, Hedges ND, Jones MV, Cole MB. Thermal inactivation of Listeria monocytogenes studied by differential scanning calorimetry. JOURNAL OF GENERAL MICROBIOLOGY 1991; 137:1419-24. [PMID: 1919516 DOI: 10.1099/00221287-137-6-1419] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The effect of NaCl on the thermal inactivation of Listeria monocytogenes has been investigated by conventional microbiological techniques and by using differential scanning calorimetry (DSC). Addition of 1.5 M-NaCl to cells grown at lower NaCl concentrations significantly increases the tolerance of cells to mild heat stress (56-62 degrees C). DSC thermograms show five main peaks which are shifted to higher temperatures in the presence of 1.5 M-NaCl. Measurement of loss of viability in the calorimeter gave good correlation between cell death and the first major thermogram peak at two NaCl concentrations. The time course of the loss of this first peak when cells were heated and held at 60 degrees C in the calorimeter matched the loss of viability, whereas the peak attributable to DNA showed little change during this process. The use of DSC to investigate the mechanisms involved in thermal inactivation is discussed.
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Jones MV, Johnson MD, Herd TM. Sensitivity of yeast vegetative cells and ascospores to biocides and environmental stress. Lett Appl Microbiol 1991. [DOI: 10.1111/j.1472-765x.1991.tb00552.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Jones MV, Bellamy K, Alcock R, Hudson R. The use of bacteriophage MS2 as a model system to evaluate virucidal hand disinfectants. J Hosp Infect 1991; 17:279-85. [PMID: 1677653 DOI: 10.1016/0195-6701(91)90272-a] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A model system which would closely reflect the resistance of poliovirus but could be easily performed in any microbiology laboratory would offer considerable advantages for rapidly screening hand decontamination products. The use of the bacteriophage MS2 as a simple model for virucidal testing has been evaluated. In suspension tests the sensitivity of MS2 to alcohols, organic acids and alkalis generally reflected that observed in studies using poliovirus. MS2 could be applied and recovered from the hands of volunteers with high efficiency. Furthermore MS2 proved to be a suitable replacement for Escherichia coli in a standard hand-decontamination test.
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Cole MB, Jones MV, Holyoak C. The effect of pH, salt concentration and temperature on the survival and growth of Listeria monocytogenes. THE JOURNAL OF APPLIED BACTERIOLOGY 1990; 69:63-72. [PMID: 2118897 DOI: 10.1111/j.1365-2672.1990.tb02912.x] [Citation(s) in RCA: 214] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Factorially designed experiments have been used to study the growth and survival of Listeria monocytogenes in different combinations of pH and salt concentrations at ambient and chill temperatures. Survival at low pH and high salt concentration was strongly temperature dependent. The minimum pH values that allowed survival after 4 weeks from an initial 10(4) cells were 4.66 at 30 degrees C, 4.36 at 10 degrees C and 4.19 at 5 degrees C. These limits were salt dependent, low (4-6%) salt concentrations improved and higher concentrations reduced survival at limiting pH values. The lowest pH that allowed a 100-fold increase in cell numbers within 60 d was 4.66 at 30 degrees C but this was increased to 4.83 at 10 degrees C. At 5 degrees C growth occurred at pH 7.0 but not at pH 5.13. Simple predictive models describing the effect of hydrogen-ion and salt concentration on the time for at least a 100-fold increase in numbers at 10 degrees C and 30 degrees C were constructed after analysis of the results for a least squares fit to a quadratic model. The interactions between salt and hydrogen-ion concentration on growth were found to be purely additive.
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Ewart WR, Jones MV, Primi MP. Bombesin changes excitability of rat brain stem neurons sensitive to gastric distension. THE AMERICAN JOURNAL OF PHYSIOLOGY 1990; 258:G841-7. [PMID: 2360630 DOI: 10.1152/ajpgi.1990.258.6.g841] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The responses of single neurons in the dorsal vagal complex to physiological gastric distension were investigated in anesthetized control and capsaicin-treated rats. In both groups, the responses of brain stem neurons to close arterial injection of the regulatory peptide bombesin (BBS) were studied. These experiments observed whether selective chemical deafferentation by capsaicin caused any significant change in the central representation of responses to gastric distension and peripheral BBS administration. In 43 animals a total of 49 neurons was studied, 21 of which were in rats pretreated with capsaicin. In normal animals, the majority of neurons (89%, n = 28) responded in the same manner (increase or decrease in firing rate) to gastric distension and peripheral BBS administration. Of the 21 neurons studied in capsaicin-treated rats, 76% responded in the same direction to gastric distension and BBS. Two neurons responsive to gastric distension failed to respond to BBS. There was no significant difference between the proportion of neurons responding both to gastric distension and BBS in normal and capsaicin-treated rats. Responses to both gastric distension and BBS were abolished by bilateral cervical vagotomy in both groups of rats. In these experiments, BBS apparently acted on peripheral receptors near the stomach to produce, via the vagus nerve, effects on neuronal excitability in the dorsal vagal complex. Almost all of these neurons were also responsive to activation of gastric mechanoreceptors. The responses of dorsal vagal complex neurons to gastric distension and peripheral BBS were capsaicin insensitive, which is in contrast to the action of cholecystokinin under the same conditions.
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King BF, Jones MV, Ewart WR. Immunohistochemical localisation of a gastrin-releasing peptide-like material in area postrema, nucleus of the solitary tract and vagal motor nucleus in the brainstem of rat. JOURNAL OF THE AUTONOMIC NERVOUS SYSTEM 1989; 28:97-104. [PMID: 2625506 DOI: 10.1016/0165-1838(89)90082-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The presence of an endogenous gastrin-releasing peptide (GRP)-like peptide in the hindbrain of rat was demonstrated immunohistochemically using antisera directed against the N-terminus and C-terminus of GRP. N-terminal and C-terminal-like immunoreactive material were distributed throughout the nucleus of the solitary tract (NTS), dorsal motor nucleus of the vagus (DMV) and tractus solitarius (TS), as well as in areas postrema (AP) and substantia gelatinosa separating AP from NTS. Positive immunostaining was localised to a dense network of nerve fibres which project longitudinally along the neuraxis. Immunolabelled cell bodies were observed rostral to the obex, principally in the mediolateral subnucleus of NTS. These immunopositive neurones project their axons caudally and longitudinally towards the commissural subnucleus of the NTS. Immunolabelled cell bodies also were found in AP; they projected their axons caudally and ventrally towards NTS. Positive immunostaining was blocked by pre-adsorbing antisera with either GRP (1 nmol/ml) or bombesin (3 nmol/ml), but was unaffected by substance P (30 nmol/ml) and spared by capsaicin pretreatments which deplete sensory nerves of their peptide content. The results indicate that NTS neurons containing a GRP-like peptide connect the rostral and caudal regions of the dorsal vagal complex by way of longitudinal nerve tracts descending NTS and TS. Some neurons in AP also contain a GRP-like peptide and appear to connect with the dorsal vagal complex.
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Ewart WR, Jones MV, King BF. Central origin of vagal nerve fibres innervating the fundus and corpus of the stomach in rat. JOURNAL OF THE AUTONOMIC NERVOUS SYSTEM 1988; 25:219-31. [PMID: 3069891 DOI: 10.1016/0165-1838(88)90026-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The origin of vagal nerve fibres innervating the anterior and posterior walls of the fundus and corpus of the rat stomach was investigated using the axon tracing dye, Fast blue. The secretomotor nerve supply to the rat stomach was predominantly ipsilateral. A large majority (98-99%) of the vagal perikarya innervating the anterior fundus and corpus were located on the left side of the brainstem. A large majority (96-99%) of the vagal perikarya innervating the posterior fundus and corpus were located on the right side. Vagal perikarya were arranged in longitudinal, dorsal cell columns which extended beyond the normally accepted cytoarchitectural limits of the dorsal motor nucleus of the vagus (DMV). A few vagal cells innervating the fundus were also found in the nucleus ambiguus. Vagal cell columns innervating the anterior and posterior fundus extended rostrocaudally over a distance of up to 4 mm and projected caudally as far as the cervical spinal cord. Vagal cell columns innervating the anterior and posterior corpus were more compact, extended over a distance of 2-3 mm, and projected rostrally as far as the inferior salivatory nucleus of the glossopharyngeal nerves. Vagal cell columns for the fundus and corpus overlapped in the region of the DMV which lay immediately ventral to the area postrema. Between one-third to one-half of the vagal cells innervating the fundus and corpus were concentrated under the area postrema. A simple form of viscerotopic organisation appears to occur within the vagal cell columns innervating the fundus and corpus.
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Jones MV, Rowe GB, Jackson B, Pritchard NJ. The use of alcoholic paper wipes for routine hand cleansing: results of trials in two hospitals. J Hosp Infect 1986; 8:268-74. [PMID: 2878032 DOI: 10.1016/0195-6701(86)90123-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The use of alcoholic paper hand wipes by nursing staff was assessed in two trials. No significant changes in total viable counts from finger imprint samples were observed when wipes were used, but some decrease in samples positive for Enterobacteriaceae and Staphylococcus aureus was recorded. The wipes were found to be pleasant and convenient to use. It is concluded that wipes are an acceptable alternative to soap and water for routine hand cleansing.
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Jones MV, Spencer WN. Thermostability of enzymes of the tricarboxylic acid cycle of Bacillus coagulans. Antonie Van Leeuwenhoek 1985; 51:193-201. [PMID: 4037783 DOI: 10.1007/bf02310012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The thermostability of four enzymes of the tricarboxylic acid cycle has been studied in the facultative thermophile, Bacillus coagulans. Although isocitrate dehydrogenase appeared to be more temperature-sensitive in whole-cell extracts of cultures grown at 30 degrees C compared with that in cultures grown at 55 degrees C, this difference could be largely eliminated by the removal of cell-wall material. The specific activity of each of the enzymes examined was approximately threefold higher in cultures grown at 55 degrees C than in those grown at 30 degrees C. The maximum temperature, Arrhenius plot and effect of stabilizing agents for each enzyme were examined and found to be independent of growth temperature. Sodium chloride (10% w/v) was an effective protective agent for fumarase, aconitase and malate dehydrogenase. Protection from thermal denaturation of isocitrate dehydrogenase, aconitase and fumarase but not malate dehydrogenase was also given when the enzymes were heated in the presence of their substrates. These results are discussed in light of the generalized theories of facultative thermophily which have been proposed.
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Jones MV, Spencer WN, Edwards C. Temperature-dependent Azide Sensitivity of Growth and ATPase Activity in the Facultative Thermophile, Bacillus coagulans. Microbiology (Reading) 1984. [DOI: 10.1099/00221287-130-1-95] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Johnson GN, Palahniuk RJ, Tweed WA, Jones MV, Wade JG. Regional cerebral blood flow changes during severe fetal asphyxia produced by slow partial umbilical cord compression. Am J Obstet Gynecol 1979; 135:48-52. [PMID: 38666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We studied the effects of severe partial asphyxia on regional cerebral blood flow and arterial blood pressure in the unanesthetized, physiologically stable fetal lamb. Cerebral blood flow was measured by the microsphere technique before and during partial umbilical cord compression. Asphyxia sufficient to decrease pH from 7.40 to 7.04 and reduce oxygen saturation from 50% to 19% increased cerebral blood flow to all areas of the brain with the largest increases going to the brain stem (275% of control) and deep cerebral structures (240% of control). Fetal arterial blood pressures increased from a mean of 58 mm Hg to a mean of 71 mm. Hg during asphyxia. The blood pressure increases correlated closely with the regional cerebral blood flow increases. There was a poor correlation between cerebral blood flow increases and changes in Paco2' pH, or oxygen saturation. We conclude that during severe fetal asphyxia arterial blood pressure is the critical factor in determining cerebral blood flow.
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Dawson H, Jones MV. Cell Wall Turnover During Myxospore Formation in Myxococcus xanthus. ACTA ACUST UNITED AC 1979. [DOI: 10.1099/00221287-112-1-143] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Jones MV. Physiological role for the membrane bound ascorbate-TMPD oxidase in pseudomonas putida. Arch Microbiol 1975; 102:275-9. [PMID: 168828 DOI: 10.1007/bf00428378] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The activity of the membrane-bound ascorbate-TMPD oxidase in Pseudomonas putida varies with growth conditions and age of the culture. A comparison of the effects of cyanide and azide on the oxidation of various substrates suggests that ascorbate-TMPD oxidase is not the terminal oxidase for NADH or succinate oxidation. However, it does have a role in the oxidation of nicotinate, and may act as an additional terminal oxidase under certain other growth conditions.
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Jones MV. The effects of trypsin on the membrane-bound nicotinic acid oxidase in Pseudomonas ovalis Chester. FEBS Lett 1973; 38:57-60. [PMID: 4359145 DOI: 10.1016/0014-5793(73)80512-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Jones MV, Craig DB. Venous reaction to plastic intravenous cannulae: influence of cannula composition. CANADIAN ANAESTHETISTS' SOCIETY JOURNAL 1972; 19:491-7. [PMID: 4647157 DOI: 10.1007/bf03005810] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Jones MV, Hughes DE. The oxidation of nicotinic acid by Pseudomonas ovalis Chester. The terminal oxidase. Biochem J 1972; 129:755-61. [PMID: 4349118 PMCID: PMC1174177 DOI: 10.1042/bj1290755] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In cell-free extracts of Pseudomonas ovalis nicotinic acid oxidase is confined to the wallmembrane fraction. It is associated with an electron-transport chain comprising b- and c-type cytochromes only, differing proportions of which are reduced by nicotinate and NADH. CO difference-spectra show two CO-binding pigments, cytochrome o (absorption maximum at 417nm) and another component absorbing maximally at 425nm. Cytochrome o is not reduced by NADH or by succinate but is by nicotinate, which can also reduce the ;425' CO-binding pigment. The effects of inhibitors of terminal oxidation support the idea of two terminal oxidases and a scheme involving the ;425' CO-binding pigment and the other components of the electron-transport chain is proposed.
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