Surfactant treatments alter endogenous surfactant metabolism in rabbit lungs

The effect of exogenous surfactant on endogenous surfactant metabolism was evaluated using a single-lobe treatment strategy to compare effects of treated with untreated lung within the same rabbit. Natural rabbit surfactant, Survanta, or 0.45% NaCl was injected into the left main stem bronchus by use of a Swan-Ganz catheter. Radio-labeled palmitic acid was then given by intravascular injection at two times after surfactant treatment, and the ratios of label incorporation and secretion in the left lower lobe to label incorporation and secretion in the right lung were compared. The treatment procedure resulted in a reasonably uniform surfactant distribution and did not disrupt lobar pulmonary blood flow. Natural rabbit surfactant increased incorporation of palmitate into saturated phosphatidylcholine (Sat PC) approximately 2-fold (P less than 0.01), and secretion of labeled Sat PC increased approximately 2.5-fold in the surfactant-treated left lower lobe relative to the right lung (P less than 0.01). Although Survanta did not alter incorporation, it did increase secretion but not to the same extent as rabbit surfactant (P less than 0.01). Alteration of endogenous surfactant Sat PC metabolism in vivo by surfactant treatments was different from that which would have been predicted by previous in vitro studies.

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Evaluation of 99mTc-Label led Vitamin K4 as an Agent for Testicular Imaging

Nuklearmedizin ◽

10.1055/s-0038-1629552 ◽

1991 ◽

Vol 30 (01) ◽

pp. 35-39 ◽

Cited By ~ 1

Author(s):

H. S. Durak ◽

M. Kitapgi ◽

B. E. Caner ◽

R. Senekowitsch ◽

M. T. Ercan

Keyword(s):

Soft Tissue ◽

Room Temperature ◽

Normal Subjects ◽

Left Testis ◽

Wide Range ◽

Activity Ratios ◽

The Right ◽

Radioactivity Levels

Vitamin K4 was labelled with 99mTc with an efficiency higher than 97%. The compound was stable up to 24 h at room temperature, and its biodistribution in NMRI mice indicated its in vivo stability. Blood radioactivity levels were high over a wide range. 10% of the injected activity remained in blood after 24 h. Excretion was mostly via kidneys. Only the liver and kidneys concentrated appreciable amounts of radioactivity. Testis/soft tissue ratios were 1.4 and 1.57 at 6 and 24 h, respectively. Testis/blood ratios were lower than 1. In vitro studies with mouse blood indicated that 33.9 ±9.6% of the radioactivity was associated with RBCs; it was washed out almost completely with saline. Protein binding was 28.7 ±6.3% as determined by TCA precipitation. Blood clearance of 99mTc-l<4 in normal subjects showed a slow decrease of radioactivity, reaching a plateau after 16 h at 20% of the injected activity. In scintigraphic images in men the testes could be well visualized. The right/left testis ratio was 1.08 ±0.13. Testis/soft tissue and testis/blood activity ratios were highest at 3 h. These ratios were higher than those obtained with pertechnetate at 20 min post injection.99mTc-l<4 appears to be a promising radiopharmaceutical for the scintigraphic visualization of testes.

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Enhanced Increases in Cytosolic Ca2+ in ADP-Stimulated Platelets from Patients with Delta-Storage Pool Deficiency – A Possible Indicator of Interactions between Granule-Bound ADP and the Membrane ADP Receptor

Thrombosis and Haemostasis ◽

10.1055/s-0038-1655971 ◽

1997 ◽

Vol 77 (02) ◽

pp. 376-382 ◽

Cited By ~ 15

Author(s):

Bruce Lages ◽

Harvey J Weiss

Keyword(s):

Platelet Rich Plasma ◽

Limited Range ◽

Dense Granule ◽

Receptor Desensitization ◽

Fura 2 ◽

Storage Pool ◽

Low Levels ◽

The Right

SummaryThe possible involvement of secreted platelet substances in agonist- induced [Ca2+]i increases was investigated by comparing these increases in aspirin-treated, fura-2-loaded normal platelets and platelets from patients with storage pool deficiencies (SPD). In the presence and absence of extracellular calcium, the [Ca2+]i response induced by 10 µM ADP, but not those induced by 0.1 unit/ml thrombin, 3.3 µM U46619, or 20 µM serotonin, was significantly greater in SPD platelets than in normal platelets, and was increased to the greatest extent in SPD patients with Hermansky-Pudlak syndrome (HPS), in whom the dense granule deficiencies are the most severe. Pre-incubation of SPD-HPS and normal platelets with 0.005-5 µM ADP produced a dose-dependent inhibition of the [Ca2+]i response induced by 10 µ M ADP, but did not alter the [Ca2+]i increases induced by thrombin or U46619. Within a limited range of ADP concentrations, the dose-inhibition curve of the [Ca2+]i response to 10 µM ADP was significantly shifted to the right in SPD-HPS platelets, indicating that pre-incubation with greater amounts of ADP were required to achieve the same extent of inhibition as in normal platelets. These results are consistent with a hypothesis that the smaller ADP-induced [Ca2+]i increases seen in normal platelets may result from prior interactions of dense granule ADP, released via leakage or low levels of activation, with membrane ADP receptors, causing receptor desensitization. Addition of apyrase to platelet-rich plasma prior to fura-2 loading increased the ADP-induced [Ca2+]i response in both normal and SPD-HPS platelets, suggesting that some release of ADP derived from both dense granule and non-granular sources occurs during in vitro fura-2 loading and platelet washing procedures. However, this [Ca2+]i response was also greater in SPD-HPS platelets when blood was collected with minimal manipulation directly into anticoagulant containing apyrase, raising the possibility that release of dense granule ADP resulting in receptor desensitization may also occur in vivo. Thus, in addition to enhancing platelet activation, dense granule ADP could also act to limit the ADP-mediated reactivity of platelets exposed in vivo to low levels of stimulation.

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Functional Characterization of the mazEF Toxin-Antitoxin System in the Pathogenic Bacterium Agrobacterium tumefaciens

Microorganisms ◽

10.3390/microorganisms9051107 ◽

2021 ◽

Vol 9 (5) ◽

pp. 1107

Author(s):

Wonho Choi ◽

Yoshihiro Yamaguchi ◽

Ji-Young Park ◽

Sang-Hyun Park ◽

Hyeok-Won Lee ◽

...

Keyword(s):

Agrobacterium Tumefaciens ◽

Physiological Function ◽

Functional Characterization ◽

Site Directed Mutagenesis ◽

In Vitro Assays ◽

Cell Growth Inhibition ◽

The Right

Agrobacterium tumefaciens is a pathogen of various plants which transfers its own DNA (T-DNA) to the host plants. It is used for producing genetically modified plants with this ability. To control T-DNA transfer to the right place, toxin-antitoxin (TA) systems of A. tumefaciens were used to control the target site of transfer without any unintentional targeting. Here, we describe a toxin-antitoxin system, Atu0939 (mazE-at) and Atu0940 (mazF-at), in the chromosome of Agrobacterium tumefaciens. The toxin in the TA system has 33.3% identity and 45.5% similarity with MazF in Escherichia coli. The expression of MazF-at caused cell growth inhibition, while cells with MazF-at co-expressed with MazE-at grew normally. In vivo and in vitro assays revealed that MazF-at inhibited protein synthesis by decreasing the cellular mRNA stability. Moreover, the catalytic residue of MazF-at was determined to be the 24th glutamic acid using site-directed mutagenesis. From the results, we concluded that MazF-at is a type II toxin-antitoxin system and a ribosome-independent endoribonuclease. Here, we characterized a TA system in A. tumefaciens whose understanding might help to find its physiological function and to develop further applications.

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Surfactant metabolism in surfactant protein A-deficient mice

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1997.272.3.l479 ◽

1997 ◽

Vol 272 (3) ◽

pp. L479-L485 ◽

Cited By ~ 34

Author(s):

M. Ikegami ◽

T. R. Korfhagen ◽

M. D. Bruno ◽

J. A. Whitsett ◽

A. H. Jobe

Keyword(s):

Lung Tissue ◽

Protein A ◽

Surfactant Protein ◽

Normal Lung ◽

Tissue Slices ◽

Normal Lung Function ◽

Deficient Mice ◽

Surfactant Metabolism

In the present study we asked if surfactant metabolism was altered in surfactant protein (SP) A-deficient mice in vivo. Although previous studies in vitro demonstrated that SP-A modulates surfactant secretion and reuptake by type II cells, mice made SP-A deficient by homologous recombination grow and reproduce normally and have normal lung function. Alveolar and lung tissue saturated phophatidylcholine (Sat PC) pools were 50 and 26% larger, respectively, in SP-A(-/-) mice than in SP-A(+/+) mice. Radiolabeled choline and palmitate incorporation into lung Sat PC was similar both in vivo and for lung tissue slices in vitro from SP-A(+/+) and SP-A(-/-) mice. Percent secretion of radiolabeled Sat PC was unchanged from 3 to 15 h, although SP-A(-/-) mice retained more labeled Sat PC in the alveolar lavages at 48 h (consistent with the increased surfactant pool sizes). Clearance of radiolabeled dipalmitoylphosphatidylcholine and SP-B from the air spaces after intratracheal injection was similar in SP-A(-/-) and SP-A(+/+) mice. Lack of SP-A had minimal effects on the overall metabolism of Sat PC or SP-B in mice.

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Pharmacologically mechanistic basis for the traditional uses of Rumex acetosa in gut motility disorders and emesis

Bangladesh Journal of Pharmacology ◽

10.3329/bjp.v10i3.23406 ◽

2015 ◽

Vol 10 (3) ◽

pp. 548 ◽

Cited By ~ 3

Author(s):

Musaddique Hussain ◽

Shahid Masood Raza ◽

Khalid Hussain Janbaz

Keyword(s):

Rumex Acetosa ◽

Response Curves ◽

Motility Disorders ◽

Traditional Uses ◽

Antiemetic Activity ◽

Rabbit Jejunum ◽

Mechanistic Basis ◽

The Right

In vitro and in vivo studies were undertaken to evaluate the pharmacologically mechanistic background to validate the traditional uses of Rumex acetosa in the treatment of emesis and gastrointestinal motility disorders such as constipation and diarrhea. In rabbit jejunum preparation, methanolic extract of R. acetosa (0.01-1.0 mg/mL) caused a transient spasmogenic effect, followed by the spasmolytic effect (3-10 mg/mL). In presence of atropine, spasmogenic effect was blocked while spasmolytic effect was emerged, suggesting that spasmogenic effect was mediated through activation of muscarinic receptors. Extract inhibited the K+ (80 mM)-induced contraction, suggesting Ca2+-cha-nnel blockade, which was further confirmed when pretreatment of tissue with extract shifted the Ca2+ concentration-response curves to the right, similarly as verapamil. R. acetosa also exhibited the significant antiemetic activity (p<0.05) against different emetogenic stimuli, when compared with chlorpromazine. This study confirms the presence of gut modulator (spasmogenic and spasmolytic) and antiemetic activates, validating its traditional uses.

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Oxygen and Carbon Dioxide Transport Characteristics of the Blood of the Nile Monitor Lizard (Varanus Niloticus)

Journal of Experimental Biology ◽

10.1242/jeb.130.1.27 ◽

1987 ◽

Vol 130 (1) ◽

pp. 27-38

Author(s):

JAMES W. HICKS ◽

ATSUSHI ISHIMATSU ◽

NORBERT HEISLER

Keyword(s):

Carbon Dioxide ◽

Haemoglobin Concentration ◽

Oxygen Affinity ◽

Total Blood ◽

Carbon Dioxide Transport ◽

Monitor Lizard ◽

The Right ◽

Dissociation Curves

Oxygen and carbon dioxide dissociation curves were constructed for the blood of the Nile monitor lizard, Varanus niloticus, acclimated for 12h at 25 and 35°C. The oxygen affinity of Varanus blood was low when Pco2 w a s in the range of in vivo values (25°C: P50 = 34.3 at PCOCO2 = 21 mmHg; 35°C: P50 = 46.2 mmHg at PCOCO2 = 35 mmHg; 1 mmHg = 133.3 Pa), and the oxygen dissociation curves were highly sigmoidal (Hill's n = 2.97 at 25°C and 3.40 at 35°C). The position of the O2 curves was relatively insensitive to temperature change with an apparent enthalpy of oxygenation (ΔH) of −9.2kJ mol−1. The carbon dioxide dissociation curves were shifted to the right with increasing temperature by decreasing total CCOCO2 at fixed PCOCO2, whereas the state of oxygenation had little effect on total blood CO2 content. The in vitro buffer value of true plasma (Δ[HCO3−]pl/-ΔpHpl) rose from 12.0 mequiv pH−1−1 at 25°C to 17.5 mequiv pH−11−1 at 35°C, reflecting a reversible increase of about 30% in haemoglobin concentration and haematocrit levels during resting conditions in vivo.

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SSB facilitates fork substrate discrimination by PriA

10.1101/2020.11.23.394411 ◽

2020 ◽

Author(s):

Hui Yin Tan ◽

Piero R. Bianco

Keyword(s):

Catalytic Efficiency ◽

Maximum Effect ◽

Replication Forks ◽

Replication Process ◽

Replication Restart ◽

Species Specific ◽

The Right ◽

Gene 32

AbstractPriA is a member of the SuperFamily 2 helicase family. Its role in vivo is to reload the primosome onto stalled replication forks resulting in the restart of the previously stalled DNA replication process. SSB is known to play key roles in mediating activities at replication forks and it is known to bind to PriA. To gain mechanistic insight into the PriA-SSB interaction, a coupled spectrophotometric assay was utilized to characterize the ATPase activity of PriA in vitro in the presence of fork substrates. The results demonstrate that SSB enhances the ability of PriA to discriminate between fork substrates 140-fold. This is due to a significant increase in the catalytic efficiency of the helicase induced by DNA-bound SSB. This interaction is species-specific as bacteriophage gene 32 protein cannot substitute for the E.coli protein. SSB, while enhancing the activity of PriA on its preferred fork, both decreases the affinity of the helicase for other forks and decreases catalytic efficiency. Central to the stimulation afforded by SSB is the unique ability of PriA to bind with high affinity to the 3’-OH placed at the end of the nascent leading strand at the fork. When both the 3’-OH and SSB are present, the maximum effect is observed. This ensures that PriA will only load onto the correct fork, in the right orientation, thereby ensuring that replication restart is directed to only the template lagging strand.

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PULMONARY EMPHYSEMA AND OTHER CARDIORESPIRATORY LESIONS AS PART OF THE MARFAN ABIOTROPHY

PEDIATRICS ◽

10.1542/peds.33.3.356 ◽

1964 ◽

Vol 33 (3) ◽

pp. 356-366

Author(s):

Robert P. Bolande ◽

Arthur S. Tucker

Keyword(s):

Connective Tissue ◽

Left Atrium ◽

Pulmonary Emphysema ◽

Left Lung ◽

Left Main ◽

Main Stem Bronchus ◽

Giant Left Atrium ◽

Left Main Stem Bronchus ◽

The Right ◽

Chronic Pulmonary Emphysema

Seven cases of Marfan's syndrome are reviewed clinically, radiologically, and pathologically. Six of the seven cases showed evidence of pulmonary dysaeration: (a) Two of the cases showed compression of the left main-stem bronchus by a giant left atrium with atelectasis of the left lung and compensatory emphysema of the right lung. (b) Two of the cases showed evidence of diffuse chronic pulmonary emphysema. Three cases had bilateral apical bullae. (c) One of the cases developed pneumothorax. The lungs of the children with the Marfan syndrome show precocious maturation of the elastic stroma of the alveolar septae. The pathogenesis of emphysema is discussed in relationship to the Marfan abiotrophy of connective tissue.

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Long-term effects of hyperpolarization-activated inward current blockade on cardiac parasympathetic activity

EP Europace ◽

10.1093/europace/euab116.541 ◽

2021 ◽

Vol 23 (Supplement_3) ◽

Author(s):

A Scridon ◽

VB Halatiu ◽

AI Balan ◽

DA Cozac ◽

GV Moldovan ◽

...

Keyword(s):

Heart Rate ◽

Vagus Nerve ◽

Vagal Stimulation ◽

Sinus Node ◽

Vagal Tone ◽

Right Atrial ◽

The Right

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This work was supported by a grant of the Romanian Ministry of Education and Research, CNCS - UEFISCDI Background The autonomic control of the pacemaker current, If, and the molecular mechanisms underlying parasympathetic If modulation are well understood. Conversely, the effects of chronic If blockade on the parasympathetic nervous system and on the heart rate (HR) response to acute parasympathetic changes are still largely unknown. Such interactions could significantly influence the course of patients undergoing chronic therapy with the If blocker ivabradine. Purpose We aimed to assess the effects of long-term If blockade using ivabradine on cardiac autonomic modulation and on the cardiovascular response to acute in vivo and in vitro parasympathetic stimulation. Methods Radiotelemetry ECG transmitters were implanted in 6 Control and 10 ivabradine-treated male Wistar rats (IVA; 3 weeks, 10 mg/kg/day); sympathetic and parasympathetic heart rate variability parameters were assessed. At the end of the study, the right atrium was removed and right atrial HCN(1-4) RNA expression levels were analyzed. The HR and systolic blood pressure (SBP) responses to in vivo electrical stimulation of the right vagus nerve (2–20 Hz) and the spontaneous sinus node discharge rate (SNDR) response to in vitro cholinergic receptors stimulation using carbamylcholine (10-9–10-6 mol/L) were assessed in 6 additional Control and 10 IVA rats. Results At the end of the study, mean 24-h HR was significantly lower in the IVA compared with the Control rats (301.3 ± 7.5 bpm vs. 341.5 ± 8.3 bpm; p< 0.01). Ivabradine administration led to a significant increase in vagal tone and shifted the sympatho-vagal balance towards vagal dominance (awake, asleep, and over 24-h; all p< 0.05). In the Control rats, in vivo vagus nerve stimulation induced a progressive decrease in both the SBP (p = 0.0001) and the HR (p< 0.0001). Meanwhile, in the IVA rats, vagal stimulation had no effect on the HR (p = 0.16) and induced a significantly lower drop in SBP (p< 0.05). Ivabradine-treated rats also presented a significantly lower SNDR drop in response to carbamylcholine (p< 0.01) and significantly higher HCN4 expression (p = 0.02). Conclusion Long-term If blockade using ivabradine caused a significant increase in vagal tone and shifted the autonomic balance towards vagal dominance in rats. Given the highly proarrhythmic effects of vagal activation at the atrial level, these findings could provide an explanation for the increased risk of atrial fibrillation associated with ivabradine use in clinical trials. In addition, ivabradine reduced the HR response to direct muscarinic receptors stimulation, canceled the cardioinhibitory response and blunted the hemodynamic response to in vivo vagal stimulation, and led to significant sinus node HCN4 up-regulation. These data suggest that ivabradine-induced HCN4 and the consequent If up-regulation could render the sinus node less sensitive to acute vagal inputs and could thus protect against excessive bradycardia induced by acute vagal activation.

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Abstract 418: Caveolar Disruption of L-type Calcium Channel and Ryanodine Receptor Facilitates Atrial Ectopy and Arrhythmogenesis in Heart Failure Mice

Circulation Research ◽

10.1161/res.127.suppl_1.418 ◽

2020 ◽

Vol 127 (Suppl_1) ◽

Author(s):

Di Lang ◽

Lucas ratajczyk ◽

Leonid Tyan ◽

Daniel Turner ◽

Francisco Alvarado ◽

...

Keyword(s):

Heart Failure ◽

Optical Mapping ◽

Ryanodine Receptors ◽

Tissue Level ◽

Confocal Imaging ◽

Right Atrial ◽

Isolated Atria ◽

The Right

Atrial fibrillation (AF) often occurs during heart failure (HF). Ectopic foci that trigger AF, are linked to discrete atrial regions that experience the highest remodeling and clinically used for AF ablation; however, mechanisms of their arrhythmogenic propensity remain elusive. We employed in vivo ECG telemetry, in vitro optical mapping and confocal imaging of Ca 2+ transients (CaT) from myocytes isolated from the right atrial appendage (RAA) and inter-caval region (ICR) of wild type (WT, n=10), caveolin-3 knockout (KO, n=6) and 8-weeks post-myocardial infarction HF (n=8) mice. HF and KO mice showed an increased susceptibility to pacing-induced AF and enhanced ectopy originated exclusively from ICR. Optical mapping in isolated atria showed prolongation of CaT rise up time (CaT-RT) in HF ICR, which suggested a remodeled coupling between L-type Ca 2+ channels (LTCCs) and ryanodine receptors (RyRs) in this specific region. In WT mice, RAA consists of structured myocytes with a prominent transverse-axial tubular system (TATS) while ICR myocytes don’t have TATS. In RAA, CaT-RT depends on LTCCs in TATS triggering RyR, while in ICR, all the LTCCs are localized in surface caveolae where they can activate subsarcolemmal RyRs and lead to a slow diffusion of Ca 2+ inside the cell interior. Downregulation of caveolae was observed specifically in HF ICR. To mimic this, we used cav3-KO mice. Triggered activities were observed in myocytes isolated from HF and KO ICR, which presumably underlie the ectopic activities in tissue level. These myocytes presented significantly unsynchronized sarcoplasmic reticulum (SR) Ca 2+ releases (synchronization index: 10.8±0.9 in WT vs 38.3±4.1 in HF vs 21.5±2.1 in KO, p <0.01 for HF and KO vs WT respectively) especially at the subsarcolemmal space that prolongs CaT-RT (62.2±4.1 ms in WT vs 122.5±12.8 ms in KO, p <0.01). In addition, failing ICR myocytes showed a higher occurrence and size of spontaneous Ca 2+ sparks which were linked to CaMKII activity and associated phosphorylation of RyR. Our findings demonstrate that in HF, caveolar disruption creates “hot spots” for arrhythmogenic ectopic activity emanated from discrete vulnerable regions of the right atrium which are associated with desynchronized SR Ca 2+ release and elevated fibrosis.

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