Post-growth Phase Research Articles

Photodynamic treatment of Staphylococcus aureus with non-iron hemin analogs in the presence of hydrogen peroxide.

Bacteria subjected to antiseptic or antibiotic stress often develop tolerance, a trait that can lead to permanent resistance. To determine whether photodynamic agents could be used to counter tolerance, we evaluated three non-iron hemin analogs (M-PpIX; M = Al, Ga, In) as targeted photosensitizers for antimicrobial photodynamic inactivation (aPDI) following exposure to sublethal H2O2. Al-PpIX is an active producer of ROS whereas Ga- and In-PpIX are more efficient at generating singlet oxygen. Al- and Ga-PpIX are highly potent aPDI agents against S. aureus and methicillin-resistant strains (MRSA) with antimicrobial activity (3 log reduction in colony-forming units) at nanomolar concentrations. The aPDI activities of Al- and Ga-PpIX against S. aureus were tested in the presence of 1 mM H2O2 added at different stages of growth. Bacteria exposed to H2O2 during log-phase growth were less susceptible to aPDI but bacteria treated with H2O2 in their postgrowth phase exhibited aPDI hypersensitivity, with no detectable colony growth after treatment with 15 nM Ga-PpIX.

The Optimal Control Chart Selection for Monitoring COVID-19 Phases: A Case Study of Daily Deaths in the USA.

Epidemiologists frequently adopt statistical process control tools, like control charts, to detect changes in the incidence or prevalence of a specific disease in real time, thereby protecting against outbreaks and emergent health concerns. Control charts have proven essential in instantly identifying fluctuations in infection rates, spotting emerging patterns, and enabling timely reaction measures in the context of COVID-19 monitoring. This study aims to review and select an optimal control chart in epidemiology to monitor variations in COVID-19 deaths and understand pandemic mortality patterns. An essential aspect of the present study is selecting an appropriate monitoring technique for distinct deaths in the USA in 7 phases, including pre-growth, growth, and post-growth phases. Stage-1 evaluated control chart applications in epidemiology departments of 12 countries between 2000 and 2022. The study assessed various control charts and identified the optimal one based on maximum shift detection using sample data. This study considered at Shewhart (Javid Shabbir2, ) control charts and exponentially weighted moving average (EWMA) control chart with smoothing parameters were all investigated in this study. In Stage-2, we applied the EWMA control chart for monitoring because of its outstanding shift detection capabilities and compatibility with the present data. Daily deaths have been monitored from March 2020 to February 2023. Control charts in epidemiology show growing use, with the United States leading at 42% applications among top countries. During the application on COVID-19 deaths, the EWMA chart accurately depicted mortality dynamics from March 2020 to February 2022, indicating six distinct stages of death. The third and fifth waves were extremely catastrophic, resulting in a considerable loss of life. Significantly, a persistent sixth wave appeared from March 2022 to February 2023. The EWMA map effectively determined the peaks associated with each wave by thoroughly examining the time and amount of deaths, providing vital insights into the pandemic's progression. The severity of each wave was measured by the average number of deaths. The United States entered a seventh phase (6th wave) from March 2022 to February 2023, marked by fewer deaths. While reassuring, it remains crucial to maintain vaccinations and pandemic control measures. Control charts enable early detection of daily COVID-19 deaths, providing a systematic strategy for government and medical staff. Incorporating the EWMA chart for monitoring immunizations, cases, and deaths is recommended.

Impact of reduction of susceptibility to SARS-CoV-2 on epidemic dynamics in four early-seeded metropolitan regions

As we enter a chronic phase of the SARS-CoV-2 pandemic, with uncontrolled infection rates in many places, relative regional susceptibilities are a critical unknown for policy planning. Tests for SARS-CoV-2 infection or antibodies are indicative but unreliable measures of exposure. Here instead, for four highly-affected countries, we determine population susceptibilities by directly comparing country-wide observed epidemic dynamics data with that of their main metropolitan regions. We find significant susceptibility reductions in the metropolitan regions as a result of earlier seeding, with a relatively longer phase of exponential growth before the introduction of public health interventions. During the post-growth phase, the lower susceptibility of these regions contributed to the decline in cases, independent of intervention effects. Forward projections indicate that non-metropolitan regions will be more affected during recurrent epidemic waves compared with the initially heavier-hit metropolitan regions. Our findings have consequences for disease forecasts and resource utilisation.

Monitoring of three-phase variations in the mortality of COVID-19 pandemic using control charts: where does Pakistan stand?

BackgroundAt the end of December 2019, the world in general and Wuhan, the industrial hub of China, in particular, experienced the COVID-19 pandemic. Massive increment of cases and deaths occurred in China and 209 countries in Europe, America, Australia, Asia and Pakistan. Pakistan was first hit by COVID-19 when a case was reported in Karachi on 26 February 2020. Several methods were presented to model the death rate due to the COVID-19 pandemic and to forecast the pinnacle of reported deaths. Still, these methods were not used in identifying the first day when Pakistan enters or exits the early exponential growth phase.ObjectiveThe present study intends to monitor variations in deaths and identify the growth phases such as pre-growth, growth, and post-growth phases in Pakistan due to the COVID-19 pandemic.MethodsNew approaches are needed that display the death patterns and signal an alarming situation so that corrective actions can be taken before the condition worsens. To meet this purpose, secondary data on daily reported deaths in Pakistan due to the COVID-19 pandemic have been considered. The n}{} c and exponentially weighted moving average (EWMA) control charts have been used for monitoring variations.ResultsThe n}{} c-chart shows that Pakistan switches from the pre-growth to the growth phase on 31 March 2020. The EWMA chart demonstrates that Pakistan remains in the growth phase from 31 March 2020 to 17 August 2020, with some indications signaling a decrease in deaths. It is found that Pakistan moved to a post-growth phase for a brief period from 27 July 2020 to 28 July 2020. Pakistan switches to re-growth phase with an alarm on 31/7/2020, right after the short-term post-growth phase. The number of deaths starts decreasing in August in that Pakistan may approach the post-growth phase shortly.ConclusionThis amalgamation of control charts illustrates a systematic implementation of the charts for government leaders and forefront medical teams to facilitate the rapid detection of daily reported deaths due to COVID-19. Besides government and public health officials, it is also the public’s responsibility to follow the enforced standard operating procedures as a temporary remedy of this pandemic in ensuring public safety while awaiting a suitable vaccine to be discovered.

Diferencias fisicoquímicas de suelo suplementado con pilas eléctricas

Existen prácticas de campesinos en el departamento del Caquetá y testimonios de personas en la ciudad de Florencia que involucran el uso de pilas eléctricas como base del abono orgánico para plantas. Frente a la hipótesis que las pilas eléctricas pueden contribuir al desarrollo saludable de una planta, se planteó como objetivo del presente estudio, evaluar la incidencia de las pilas eléctricas en las propiedades físicas y químicas de una muestra de suelo destinado a la siembra de fríjol. El experimento consistió en un diseño completamente al azar (DCA) con arreglo factorial 1 x 4, donde el factor A corresponde fríjol y el factor B a la variedad de pilas eléctricas (genéricas y alcalinas) con tres repeticiones. En cada tratamiento se determinó: pH, acidez intercambiable (A.I.), carbono orgánico (C.O), cenizas, color y conductividad. El estudio permitió evidenciar que la adición de pilas eléctricas al suelo favorece la absorción de la energía solar, haciendo que la temperatura media del suelo tienda a ser más elevada lo que tendería a promover una germinación rápida en las semillas, aspecto positivo en la etapa germinativa de estas. No obstante, puede incidir en la baja liberación de nitrógeno al suelo, en sus fases posteriores al crecimiento.

Downwind effects on an arid dunefield from an evolving urbanised area

The impacts of urbanised zones on aeolian dynamics are little understood, particularly within arid areas. This study examines the large-scale influence of a growing tourist resort in Gran Canaria Island, Spain, on the sedimentary dynamics of an arid dunefield. Direct downwind effects from the urban area on the dune field surface are modelled for pre-growth and post-growth phases of the urban development. The geomorphological changes observed in the area stretching from the shoreline to the inland transgressive dune field were documented through aerial photographic and LiDAR evidence. Impacts of the urban growth on airflow, as well as those induced by tourists in the upper beach zone (de-vegetation), are examined through analysis of topographic changes. These impacts on the system are shown to have been synergistic in driving the development of a composite dune ridge, formed by the coalescence of smaller dunes into a distinctive aeolian accumulation ridge.

Identification of senescence and death in Emiliania huxleyi and Thalassiosira pseudonana: Cell staining, chlorophyll alterations, and dimethylsulfoniopropionate (DMSP) metabolism

We measured membrane permeability, hydrolytic enzyme, and caspase‐like activities using fluorescent cell stains to document changes caused by nutrient exhaustion in the coccolithophore Emiliania huxleyi and the diatom Thalassiosira pseudonana, during batch‐culture nutrient limitation. We related these changes to cell death, pigment alteration, and concentrations of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) to assess the transformation of these compounds as cell physiological condition changes. E. huxleyi persisted for 1 month in stationary phase; in contrast, T. pseudonana cells rapidly declined within 10 d of nutrient depletion. T. pseudonana progressively lost membrane integrity and the ability to metabolize 5‐chloromethylfluorescein diacetate (CMFDA; hydrolytic activity), whereas E. huxleyi developed two distinct CMFDA populations and retained membrane integrity (SYTOX Green). Caspase‐like activity appeared higher in E. huxleyi than in T. pseudonana during the post‐growth phase, despite a lack of apparent mortality and cell lysis. Photosynthetic pigment degradation and transformation occurred in both species after growth; chlorophyll a (Chl a) degradation was characterized by an increase in the ratio of methoxy Chl a : Chl a in T. pseudonana but not in E. huxleyi, and the increase in this ratio preceded loss of membrane integrity. Total DMSP declined in T. pseudonana during cell death and DMS increased. In contrast, and in the absence of cell death, total DMSP and DMS increased in E. huxleyi. Our data show a novel chlorophyll alteration product associated with T. pseudonana death, suggesting a promising approach to discriminate nonviable cells in nature.

Dynamic Metabolic Modeling for a MAB Bioprocess

Production of monoclonal antibodies (MAb) for diagnostic or therapeutic applications has become an important task in the pharmaceutical industry. The efficiency of high-density reactor systems can be potentially increased by model-based design and control strategies. Therefore, a reliable kinetic model for cell metabolism is required. A systematic procedure based on metabolic modeling is used to model nutrient uptake and key product formation in a MAb bioprocess during both the growth and post-growth phases. The approach combines the key advantages of stoichiometric and kinetic models into a complete metabolic network while integrating the regulation and control of cellular activity. This modeling procedure can be easily applied to any cell line during both the cell growth and post-growth phases. Quadratic programming (QP) has been identified as a suitable method to solve the underdetermined constrained problem related to model parameter identification. The approach is illustrated for the case of murine hybridoma cells cultivated in stirred spinners.

Differential expression of fibromodulin mRNA associated with tendon fibril growth: isolation and characterization of a chicken fibromodulin cDNA.

A 450 bp cDNA fragment similar to that encoding bovine fibromodulin was isolated using a screening procedure to isolate genes differentially expressed between the pre- and post-growth phases of fibril growth in the developing chicken embryo metatarsal tendon. Using this fragment, a 2.4 kb cDNA clone for chicken fibromodulin was isolated from a lambda ZAP library, and the 5' rapid amplification of cDNA ends technique was employed to clone the 5'end of the fibromodulin cDNA. The full-length cDNA contained an open reading frame coding for a 380-amino-acid protein. There was approximately 80% similarity with human, rat and bovine fibromodulins, which confirmed its identity as fibromodulin. Structural features of the deduced sequence include an 18-amino-acid signal peptide, cysteine residues in conserved positions in the N- and C-terminal regions, and a central leucine-rich domain containing eleven repeats of the sequence LXXLXLXXNXL/I. Features unique to chicken fibromodulin include an additional glycosylation site as well as a decreased number of tyrosine residues that could be sulphated, and therefore potential changes in the charge of the molecule. In addition, there was little similarity among the untranslated regions. When compared with chicken decorin and lumican, fibromodulin showed greater similarity to the other keratan sulphate-containing proteoglycan, lumican. Northern blot analysis revealed a 6-8-fold increase in the fibromodulin mRNA level from day 14 to day 19 of development. In the chicken tendon, collagen fibril growth is a process characterized by a precipitous increase in length during a short developmental period. The necessary changes would require the expression of different genes regulating fibril formation and growth, and interactions between fibromodulin and collagen fibrils may participate in the regulation of collagen fibril growth and matrix assembly.

Reduction of acidurance of streptococcal growth and glycolysis by fluoride and gramicidin.

The acidurance of glycolysis by intact cells of Streptococcus mutans GS-5, Streptococcus salivarius ATCC 25925, and Streptococcus sanguis NCTC 10904 was found to be highly dependent on membrane functions affected by gramicidin, which increases the proton permeability of cell membranes. Plots of % glucose utilized during two hours against suspension pH values for cells suspended in 100 mM phosphate buffer plus 1 mM MgCl2 plus 13.9 mM glucose indicated, for 50% glucose utilization, pH values of 5.0 for S. mutans, 5.7 for S. salivarius, and 6.2 for S. sanguis. Gramicidin treatment shifted these values to 6.0, 6.3, and 6.9, respectively. Growth of S. mutans and S. salivarius in complex media proved to be more acid-sensitive than was glycolysis, and in batch cultures, there was a well-defined, post-growth phase of glycolysis. Minimum pH values for growth and for glycolysis in medium with excess glucose were approximately 4.8 and 4.4, respectively, for S. mutans, and 4.9 and 4.3 for S. salivarius. S. sanguis was less aciduric and showed little differential acid sensitivity, with minimum pH values of about 5.2 for both growth and glycolysis. Fluoride acted to eliminate the differences in acidurance of growth and glycolysis for S. mutans or S. salivarius and to render both processes more acid-sensitive. Thus, glycolysis was more fluoride-sensitive than was growth. Growth was found to be acid-limited in media with initial glucose levels greater than 0.2, 0.3, and 0.5% (weight/volume) for S. sanguis, S. mutans, and S. salivarius, respectively, and to be glucose-limited at lower levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomy of the ovaries of the starfish Asterias rubens (Echinodermata). A histological and ultrastructural study.

The ovaries of the starfish Asterias rubens were studied histologically and ultrastructurally. The reproductive system in female specimens consists of ten separate ovaries, two in each ray. Each ovary is made up of a rachis with lateral primary and secondary folds: the acini maiores and acini minores. The ovarian wall is composed of an outer and in inner part, separated by the genital coelomic sinus. The ovarian lumen contains oocytes in various phases of oogenesis, follicle cells, phagocytosing cells and steroid-synthesizing cells. Oogenesis is divided into four phases: (i) multiplication phase of oogonia, (ii) initial growth phase of oocytes I, (iii) growth phase proper of oocytes I, and (iv) post-growth phase of oocytes I. The granules endoplasmic reticulum and the Golgi complex of the oocytes appear to be involved in yolk formation, while the haemal system, haemal fluid and nurse cells may also be important for vitellogenesis. The haemal system is discussed as most likely being involved in synchronizing the development of the ovaries during the annual reproductive cycle and in inducing, stimulating and regulating the function of the ovaries. Steroid-synthesizing cells are present during vitellogenesis; a correlation between the presence of these cells and vitellogenesis is discussed.