scholarly journals Regrowth of Mycobacterium tuberculosis Populations Exposed to Antibiotic Combinations Is Due to the Presence of Isoniazid and Not Bacterial Growth Rate

2019 ◽  
Vol 63 (12) ◽  
Author(s):  
Charlotte L. Hendon-Dunn ◽  
Henry Pertinez ◽  
Alice A. N. Marriott ◽  
Kim A. Hatch ◽  
Jon C. Allnutt ◽  
...  
Keyword(s):  
Growth Rate ◽  
Mycobacterium Tuberculosis ◽  
Time Course ◽  
Bacterial Population ◽  
Slow Growth ◽  
Bacterial Growth Rate ◽  
Content Type ◽  
Slow Growth Rate ◽  
Antibiotic Efficacy ◽  
Fast Growth Rate

ABSTRACT Modulation of the growth rate in Mycobacterium tuberculosis is key to its survival in the host, particularly with regard to its adaptation during chronic infection, when the growth rate is very slow. The resulting physiological changes influence the way in which this pathogen interacts with the host and responds to antibiotics. Therefore, it is important that we understand how the growth rate impacts antibiotic efficacy, particularly with respect to recovery/relapse. This is the first study that has asked how growth rates influence the mycobacterial responses to combinations of the frontline antimycobacterials, isoniazid (INH), rifampin (RIF), and pyrazinamide (PZA), using continuous cultures. The time course profiles of log-transformed total viable counts for cultures, controlled at either a fast growth rate (mean generation time [MGT], 23.1 h) or a slow growth rate (MGT, 69.3 h), were analyzed by the fitting of a mathematical model by nonlinear regression that accounted for the dilution rate in the chemostat and profiled the kill rates and recovery in culture. Using this approach, we show that populations growing more slowly were generally less susceptible to all treatments. We observed a faster kill rate associated with INH than with RIF or PZA and the appearance of regrowth. In line with this observation, regrowth was not observed with RIF exposure, which provided a slower bactericidal response. The sequential additions of RIF and PZA did not eliminate regrowth. We consider here that faster, early bactericidal activity is not what is required for the successful sterilization of M. tuberculosis, but instead, slower elimination of the bacilli followed by reduced recovery of the bacterial population is required.

Growth Kinetics and Formation of Uniform Self-Assembled InAs/GaAs Quantum Dots at

2007 ◽  
Vol 124-126 ◽  
pp. 539-542
Author(s):  
Eui Tae Kim ◽  
Anupam Madhukar
Keyword(s):  
Growth Rate ◽  
Quantum Dots ◽  
Growth Kinetics ◽  
Slow Growth ◽  
Fast Growth ◽  
Slow Growth Rate ◽  
Self Assembled ◽  
Kinetics Of ◽  
Fast Growth Rate ◽  
2D To 3D

We discuss the growth kinetics of InAs/GaAs self-assembled quantum dots (QDs) using two different InAs deposition rates, relatively fast growth rate of 0.22 ML/sec and slow growth rate of 0.054 ML/sec. With increasing InAs deposition amount to 3.0 ML, the QD density was almost constant after 2D to 3D island transition at the slow deposition rate while the QD density kept increasing and the QD size distribution was relatively broad at the fast growth rate. After the 2D to 3D transition, at the slow growth rate, further deposited In adatoms seemed to incorporate primarily into already formed islands, and thus contribute to equalize island size. The photoluminescence (PL) full-width at half maximum (FWHM) of 2.5 ML InAs QDs at 0.054 ML/sec was 23 meV at 78K. The PL characteristics of InAs/GaAs QDs were degraded significantly after thermal annealing at 550 oC for 3 hours.

scholarly journals Mycobacterium tuberculosis Is Resistant to Isoniazid at a Slow Growth Rate by Single Nucleotide Polymorphisms in katG Codon Ser315

PLoS ONE ◽  
2015 ◽  
Vol 10 (9) ◽  
pp. e0138253 ◽  
Author(s):  
Rose E. Jeeves ◽  
Alice A. N. Marriott ◽  
Steven T. Pullan ◽  
Kim A. Hatch ◽  
Jon C. Allnutt ◽  
...  
Keyword(s):  
Growth Rate ◽  
Mycobacterium Tuberculosis ◽  
Single Nucleotide Polymorphisms ◽  
Slow Growth ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Slow Growth Rate

scholarly journals THE ABUNDANCE OF ORNAMENTAL CORALS AFTER MASS DIE OFF IN 1997 ON THE PADANG SHELF REEF SYSTEM, WEST SUMATERA, INDONESIA

2016 ◽  
Vol 8 (1) ◽  
pp. 29-38 ◽  
Author(s):  
Ofri Johan ◽  
Anjang B. Prasetio ◽  
Idil Ardi ◽  
Amran R. Syam ◽  
Norman J. Quinn
Keyword(s):  
Growth Rate ◽  
Coral Species ◽  
Slow Growth ◽  
Survey Method ◽  
Pocillopora Damicornis ◽  
Slow Growth Rate ◽  
Massive Coral ◽  
Belt Transect ◽  
Line Intercept ◽  
Fast Growth Rate

ABSTRACTThe Indonesian Ministry of Marine Affairs and Fisheries aims to establish export quota ornamental corals based on scientifically-founded data from the natural environment. The purpose of this study was to determine the abundance of ornamental coral after mass die off in 1997. Ornamental corals were classified into three groups based on the guideline of ornamental coral propagation for trading purposes. Classification categories are rapid (3-6 months), middle (8-12 months), and slow growth rate (>24 months), which relates to their harvesting time when transplanted for the trade purpose. The survey method used line intercept transects to get coral condition data and belt transect with 2 m width to get ornamental coral data. Both line and belt transect have 30 m length and with three replicates. The study showed number of colony and abundance of ornamental coral for fast growth rate group such as Acropora sp (1348 col & 7.49 col/m2), Galaxea sp, Hydnophora exesa, H. microconus, Pocillopora damicornis, Stylopora sp and Montipora sp with the highest abundant found on Acropora sp and Montipora sp (1348 col & 7.49 col/m2). Whereas the coral which from middle growth rate were Leptoseris sp, Pavona sp, Platygyra sp, Favia sp, Favites sp with the highest abundant found on Favia sp (101 col & 0.56 col/m2).  Coral species typically used for ornamental coral trade within the slow growth rate category such massive coral were not found on this survey. Due to the massive coral die-off in 1997 and the paucity of ornamental corals, the utilization of ornamental coral should be supported by coral transplantation and the broodstock of slow growth of coral taken from other area.  Keywords: ornamental coral, abundant, mass die off, Padang Waters

scholarly journals THE ABUNDANCE OF ORNAMENTAL CORALS AFTER MASS DIE OFF IN 1997 ON THE PADANG SHELF REEF SYSTEM, WEST SUMATERA, INDONESIA

2016 ◽  
Vol 8 (1) ◽  
Author(s):  
Ofri Johan ◽  
Anjang B. Prasetio ◽  
Idil Ardi ◽  
Amran R. Syam ◽  
Norman J. Quinn
Keyword(s):  
Growth Rate ◽  
Coral Species ◽  
Slow Growth ◽  
Survey Method ◽  
Pocillopora Damicornis ◽  
Slow Growth Rate ◽  
Massive Coral ◽  
Belt Transect ◽  
Line Intercept ◽  
Fast Growth Rate

<p align="center"><strong>ABSTRACT</strong></p><p>The Indonesian Ministry of Marine Affairs and Fisheries aims to establish export quota ornamental corals based on scientifically-founded data from the natural environment. The purpose of this study was to determine the abundance of ornamental coral after mass die off in 1997. Ornamental corals were classified into three groups based on the guideline of ornamental coral propagation for trading purposes. Classification categories are rapid (3-6 months), middle (8-12 months), and slow growth rate (&gt;24 months), which relates to their harvesting time when transplanted for the trade purpose. The survey method used line intercept transects to get coral condition data and belt transect with 2 m width to get ornamental coral data. Both line and belt transect have 30 m length and with three replicates. The study showed number of colony and abundance of ornamental coral for fast growth rate group such as <em>Acropora</em> sp (1348 col &amp; 7.49 col/m<sup>2</sup>), <em>Galaxea </em>sp, <em>Hydnophora</em> <em>exesa</em>, <em>H. microconus</em>, <em>Pocillopora damicornis</em>, <em>Stylopora</em> sp and <em>Montipora</em> sp with the highest abundant found on Acropora sp and Montipora sp (1348 col &amp; 7.49 col/m<sup>2</sup>). Whereas the coral which from middle growth rate were <em>Leptoseris</em> sp, <em>Pavona</em> sp, <em>Platygyra</em> sp, <em>Favia</em> sp, <em>Favites</em> sp with the highest abundant found on <em>Favia</em> sp (101 col &amp; 0.56 col/m<sup>2</sup>).  Coral species typically used for ornamental coral trade within the slow growth rate category such massive coral were not found on this survey. Due to the massive coral die-off in 1997 and the paucity of ornamental corals, the utilization of ornamental coral should be supported by coral transplantation and the broodstock of slow growth of coral taken from other area.  </p><p><strong>Keywords: </strong>ornamental coral, abundant, mass die off, Padang Waters</p>

EFFECT OF GROWTH RATE ON THE INCIDENCE OF OSTEOCHONDROSIS IN GROWING SWINE

1984 ◽  
Vol 64 (1) ◽  
pp. 139-146 ◽  
Author(s):  
T. NAKANO ◽  
F. X. AHERNE ◽  
J. J. BRENNAN ◽  
J. R. THOMPSON
Keyword(s):  
Growth Rate ◽  
Slow Growth ◽  
Average Daily Gain ◽  
Experimental Period ◽  
Slow Growth Rate ◽  
Metatarsal Bones ◽  
Group I ◽  
Group Ii ◽  
Daily Gain ◽  
Fast Growth Rate

Eighty-eight, 4-wk-old Yorkshire × Landrace pigs (44 barrows and 44 gilts) averaging 8.0 kg were used to study the effect of growth rate on the incidence of osteochondrosis and some characteristics of hind limb bones. Forty-eight pigs (Group I) were fed control diets through the starter to finisher phases, while for the remaining 40 pigs (Group II), nutrient densities of starter and grower diets were increased to enhance growth rate. At an average liveweight of 94 kg, animals wer slaughtered, and humeri, ulnae, radii, and femurs were visually and histologically examined for soundness of cartilage and subchondral bone. Average daily gain was greater for Group II than for Group I during both the starter (0.58 vs. 0.43 kg, P < 0.01) and grower (0.84 vs. 0.74 kg, P < 0.05) phases, as was intended, and also greater (0.74 vs. 0.68 kg, P < 0.05) for Group II for the overal experimental period. The faster growth rate in Group II did not affect (P > 0.05) the incidence and severity of osteochondrosis in any joint (or bone) site examined. This was consistent with the nonsignificant (P > 0.05) correlations between growth rate and soundness scores of joint and bone, and the similarity (P > 0.05) of the soundness scores of pigs with fast growth rate (average daily gain, 0.82–1.00 kg), intermediate growth rate (0.74–0.76 kg), and slow growth rate (0.53–0.67 kg). Bone characteristics of the femur, tibia, and metatarsal bones were not influenced (P > 0.05) by growth rate. Key words: Growth rate, osteochondrosis, bone characteristics, swine

scholarly journals Simple and Rapid Method To Determine Antimycobacterial Potency of Compounds by Using Autoluminescent Mycobacterium tuberculosis

2014 ◽  
Vol 58 (10) ◽  
pp. 5801-5808 ◽  
Author(s):  
Sreevalli Sharma ◽  
Ekaterina Gelman ◽  
Chandan Narayan ◽  
Deepa Bhattacharjee ◽  
Vijayashree Achar ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Slow Growth ◽  
Gc Content ◽  
Content Type ◽  
Slow Growth Rate ◽  
Drug Candidates ◽  
Luminescence Assay ◽  
Bactericidal Activities ◽  
Time Required

ABSTRACTA major obstacle in the process of discovery of drugs againstMycobacterium tuberculosisis its extremely slow growth rate and long generation time (∼20 to 24 h). Consequently, determination of MICs and minimum bactericidal concentrations (MBCs) of potential drug candidates using current methods requires 7 days (resazurin-based MIC assay [REMA]) and 1 month (CFU enumeration), respectively. We employed a synthetic luciferase operon optimized for expression in high-GC-content bacteria and adapted it for use in mycobacteria. Using luminescence-based readouts, we were able to determine the MICs and bactericidal activities of approved tuberculosis (TB) drugs, which correlated well with currently used methods. Although luminescence-based readouts have been used previously to determine the MICs and bactericidal activities of approved TB drugs, in this study we adapted this assay to carry out a pilot screen using a library of 1,114 compounds belonging to diverse chemical scaffolds. We found that MICs derived from a 3-day luminescence assay matched well with REMA-based MIC values. To determine the bactericidal potencies of compounds, a 1:10 dilution of the cultures from the MIC plate was carried out on day 7, and the bactericidal concentrations determined based on time to positivity in 2 weeks were found to be comparable with MBC values determined by the conventional CFU approach. Thus, the luminescent mycobacterium-based approach not only is very simple and inexpensive but also allowed us to generate the information in half the time required by conventional methods.

Time-Energy Budgets During Reproduction and the Evolution of Single Parenting in the Superb Lyrebird

1986 ◽  
Vol 34 (3) ◽  
pp. 351 ◽  
Author(s):  
A Lill
Keyword(s):  
Growth Rate ◽  
Brood Size ◽  
Slow Growth ◽  
Bird Species ◽  
Egg Laying ◽  
Energy Budgets ◽  
Brood Care ◽  
Single Parenting ◽  
Slow Growth Rate ◽  
Small Brood

Estimated expenditures on brood-care by unassisted female superb lyrebirds, obtained through time-energy budgeting, were compared with published values for other bird species. With the exception of nestbuilding, estimated daily expenditures were relatively low, due mainly to the small brood size and low level of parental attentiveness. It is suggested that the traits which reduce daily brood-care expenditures, particularly the small brood size and extremely slow growth rate, may have evolved as adaptations which enabled deserted females operating close to maximal capacity to cope with single-parenting. Male parental involvement could probably increase the growth rate of the young, but not brood size; moreover, egg- laying was sufficiently asynchronous to afford multiple mating opportunities to parentally emancipated males. However, the slow growth rate of the young results in relatively large overall brood-care expenditures for females. Investments by males of up to 50% of daylight hours and 45% of BMR on singing at the height of the mating season were comparable with those of partially emancipated, polygynous males of other species. They probably reflect the high level of competition to control good display areas and to advertise status and quality to widely spaced females.

scholarly journals Effect of physiological age of stem and IBA treatment on rooting of branch cuttings of Taxus baccata L.

1970 ◽  
pp. 01-07
Author(s):  
Saumitro Das ◽  
L.K. Jha
Keyword(s):  
Growth Rate ◽  
Large Scale ◽  
Slow Growth ◽  
Physiological Age ◽  
Taxus Baccata ◽  
Practical Solution ◽  
Slow Growth Rate ◽  
Rooting Response ◽  
Himalayan Yew ◽  
Rooting Capacity

The natural population of Taxus baccata L. (Himalayan Yew) throughout the Indian Himalayan Region is greatly reduced due to its extensive and reckless exploitation for “Taxol” an anticancer drug. The effects of overexploitation are exacerbated by the species poor regeneration process, slow growth rate and prolonged seed dormancy. Therefore vegetative propagation by branch cuttings seems to be only practical solution for its large scale multiplication. A study was conducted on six candidate trees (CTs) to examine the effect genotype, physiological age of stem, IBA treatment on rooting of Taxus baccata cuttings. Results revealed that rooting behaviour of cuttings was significantly affected by all the factors under study. Among the six CTs studied, CT 2 (from BSI, Shillong) had given the highest rooting response (46.28%). The juvenile cuttings have the higher rooting capacity; however the callusing was more prominent in mature cutting. The influence of IBA treatment was also significant for rooting where 1000 was most effective for stimulating rooting juvenile cuttings and 2000 ppm in mature cuttings.

scholarly journals Mycobacterium tuberculosis Rv2700 Contributes to Cell Envelope Integrity and Virulence

2019 ◽  
Vol 201 (19) ◽  
Author(s):  
Edward R. Ballister ◽  
Marie I. Samanovic ◽  
K. Heran Darwin
Keyword(s):  
Growth Rate ◽  
Mycobacterium Tuberculosis ◽  
Cell Envelope ◽  
Bacterial Species ◽  
Transmembrane Helix ◽  
Antibiotic Sensitivity ◽  
Uncharacterized Protein ◽  
Content Type ◽  
Cell Envelopes ◽  
Envelope Functions

ABSTRACT The cell envelope of Mycobacterium tuberculosis is a key target for antibiotics, yet its assembly and maintenance remain incompletely understood. Here we report that Rv2700, a previously uncharacterized M. tuberculosis gene, contributes to envelope integrity. Specifically, an Rv2700 mutant strain had a decreased growth rate, increased sensitivity to antibiotics that target peptidoglycan crosslinking, and increased cell envelope permeability. We propose that Rv2700 be named a “cell envelope integrity” gene (cei). Importantly, a cei mutant had attenuated virulence in mice. Cei shares predicted structural homology with another M. tuberculosis protein, VirR (Rv0431), and we found that a virR mutant had growth rate, antibiotic sensitivity, and envelope permeability phenotypes similar to those of the cei mutant. Both Cei and VirR are predicted to consist of a transmembrane helix and an extracellular LytR_C domain. LytR_C domains have no known function, but they are also found in a family of proteins, the LytR-Cps2A-Psr (LCP) enzymes, that perform important cell envelope functions in a range of bacteria. In mycobacteria, LCP enzymes attach arabinogalactan to peptidoglycan, and mycobacterial LCP enzyme mutants have phenotypes similar to those of virR- and cei-deficient strains. Collectively, our results suggest that LytR_C domain proteins may contribute to the cell envelope functions performed by LCP proteins. This study provides a framework for further mechanistic investigations of LytR_C proteins and, more broadly, for advancing our understanding of the cell envelopes of mycobacteria and other medically and economically important genera. IMPORTANCE Mycobacterium tuberculosis causes about 1.5 million deaths per year. The unique composition of the Mycobacterium tuberculosis cell envelope is required for this bacterium to cause disease and is the target for several critical antibiotics. By better understanding the mechanisms by which mycobacteria assemble and maintain their cell envelope, we might uncover new therapeutic targets. In this work, we show that a previously uncharacterized protein, Rv2700, is important for cell envelope integrity in Mycobacterium tuberculosis and that loss of Rv2700 attenuates virulence in mice. This family of proteins is found in a broad group of bacterial species, so our work provides a first insight into their potential functions in many species important to the environment, industry, and human health.

Sign in / Sign up

Export Citation Format

Share Document