scholarly journals INTRAPOPULATION KINETICS OF THE MITOTIC CYCLE

1965 ◽  
Vol 25 (2) ◽  
pp. 179-189 ◽  
Author(s):  
Jesse E. Sisken ◽  
Luciano Morasca
Keyword(s):  
Generation Time ◽  
Mitotic Cycle ◽  
Tritiated Thymidine ◽  
Age Distribution ◽  
Time Lapse ◽  
Human Amnion ◽  
Generation Times ◽  
The Right ◽  
Kinetics Of ◽  
Autoradiographic Detection

Data obtained with time lapse cinemicrographic techniques showed that the distribution of generation times for exponentially proliferating human amnion cells in culture is skewed to the right and that reciprocals of generation times appear normally distributed. As shown for bacteria, the true age distribution is much broader than theoretical distributions which fail to take into account the dispersion of generation times. By means of the technique utilizing autoradiographic detection of tritiated thymidine in cells whose mitotic histories were recorded by time lapse cinemicrography, it was shown that the G1 distribution is similar to the generation time distribution but is more variable. In our experiments, the G2 + prophase distribution resembled the generation time and G1 distributions. The data suggested two possibilities for S: either it is relatively constant, or it is inversely related to the lengths of G1 and G2 + prophase. Since G1 is more variable than the total cycle, and G2 + prophase more variable than the computed sum of S + G2 + prophase + metaphase, it was concluded that the relationships between parts of the cycle are non-random and that compensating mechanisms apparently help regulate the lengths of successive parts of the mitotic cycle in individual cells.

scholarly journals TIMING OF DNA SYNTHESIS IN THE MITOTIC CYCLE IN VITRO

1961 ◽  
Vol 9 (3) ◽  
pp. 509-518 ◽  
Author(s):  
Jesse E. Sisken ◽  
Riojun Kinosita
Keyword(s):  
Dna Synthesis ◽  
Generation Time ◽  
Mitotic Cycle ◽  
Tritiated Thymidine ◽  
Lung Cells ◽  
Human Amnion ◽  
Cells In Culture ◽  
Single Colony ◽  
Distribution Of Values

A study was made of the timing of DNA synthesis in the mitotic cycle under conditions where the average mitotic cycle of populations of human amnion and kitten lung cells in culture was variable. Three types of experiments were performed: (a) Autoradiographs were made of incorporated tritiated thymidine in cells whose mitotic histories were recorded microcinematographically allowing the measurement of telophase + G1 along with the total length of the mitotic cycle. (b) Measurement of the G2 + prophase part of the mitotic cycle was performed under various conditions by exposing cells to tritiated thymidine and observing the increase in labeled metaphases plus anaphases as a function of time. (c) The effect of a change in pH on parts of the mitotic cycle was tested by continuously photographing a single colony of cells first at pH 7.8 and then at pH 7.1. All of our data point to the same conclusion; namely, that within a population of cells with a given generation time, the length of each of the measurable parts of the mitotic cycle has a particular distribution of values and that, when there is a change in the generation time, under our conditions only the T + G1 distribution changes.

scholarly journals THE TIME OF SYNTHESIS AND THE CONSERVATION OF MITOSIS-RELATED PROTEINS IN CULTURED HUMAN AMNION CELLS

1967 ◽  
Vol 34 (1) ◽  
pp. 97-110 ◽  
Author(s):  
Jesse E. Sisken ◽  
Elaina Wilkes
Keyword(s):  
Time Lapse ◽  
Major Effect ◽  
Human Amnion ◽  
Daughter Cells ◽  
Low Concentrations ◽  
Associated Proteins ◽  
A Cell ◽  
Quantitative Analyses ◽  
Related Proteins ◽  
Kinetics Of

p-Fluorophenylalanine (PFPA), an analogue of phenylalanine which may be incorporated into proteins, increases the duration of mitosis. In the present experiments, based upon quantitative analyses of time-lapse cinemicrographic films, brief treatments of cells with PFPA are shown to affect the duration of metaphase in only those cells which enter division during or shortly after treatment. The offspring of cells with prolonged metaphases also tend to have prolonged metaphases. Analyses of the kinetics of the appearance of prolonged metaphases indicate that some protein specifically associated with mitosis is synthesized primarily during a period which corresponds closely to G2. The manner in which the defect is passed on to daughter cells indicates that the protein involved is conserved and reutilized by daughter cells for their subsequent divisions. Comparable experiments performed with low concentrations of puromycin indicate that the major effect of PFPA is due to its incorporation into protein rather than its ability to inhibit protein synthesis. The fact that puromycin-induced effects can also be passed on to daughter cells is interpreted to mean that cells make only specific amounts of some mitosis-associated proteins and that if a cell "inherits" a deficiency in such protein it is not able to compensate for the deficiency.

scholarly journals CELL POPULATION KINETICS OF EXCISED ROOTS OF PISUM SATIVUM

1965 ◽  
Vol 27 (1) ◽  
pp. 179-189 ◽  
Author(s):  
Jack Van't Hof
Keyword(s):  
Cell Population ◽  
Mitotic Cycle ◽  
Sucrose Concentration ◽  
Tritiated Thymidine ◽  
Cycle Duration ◽  
Population Kinetics ◽  
Pea Roots ◽  
Mitotic Figures ◽  
Kinetics Of ◽  
Subsequent Rise

The cell population kinetics of excised, cultured pea roots was studied with the use of tritiated thymidine and colchicine to determine (1) the influence of excision, (2) the influence of sucrose concentration, (3) the average mitotic cycle duration, and (4) the duration of mitosis and the G1, S, and G2 periods of interphase.1 The results indicate that the process of excision causes a drop in the frequency of mitotic figures when performed either at the beginning of the culture period or after 100 hours in culture. This initial decrease in frequency of cell division is independent of sucrose concentration, but the subsequent rise in frequency of division, after 12 hours in culture, is dependent upon sucrose concentration. Two per cent sucrose maintains the shortest mitotic cycle duration. The use of colchicine indicated an average cycle duration of 20 hours, whereas the use of tritiated thymidine produced an average cycle duration of 17 hours.

scholarly journals SYNTHESIS OF DEOXYRIBONUCLEIC ACID BY MICRO- AND MACRONUCLEI OF TETRAHYMENA PYRIFORMIS

1962 ◽  
Vol 13 (2) ◽  
pp. 193-203 ◽  
Author(s):  
Barbara B. McDonald
Keyword(s):  
Dna Synthesis ◽  
Generation Time ◽  
Deoxyribonucleic Acid ◽  
Tritiated Thymidine ◽  
Tetrahymena Pyriformis ◽  
Type Ii ◽  
Total Period ◽  
Daughter Cells ◽  
Generation Times ◽  
The Times

Evidence as to the times of DNA synthesis in micronucleate Tetrahymena pyriformis (mating type II, variety 1) has been obtained by briefly exposing individuals of different ages to tritiated thymidine, returning them to non-radioactive medium, fixing at division, and preparing autoradiographs. A variable length of interphase, ranging from a few minutes to about 2 hours, has been found to precede the initiation of macronuclear DNA synthesis. Once begun, however, the period of synthesis appears to be similar in all cells, regardless of generation time, and has been estimated at 1 to 1½ hours. Under the conditions of these experiments, the time elapsing between the end of synthesis and subsequent division into daughter cells ranges from approximately 1½ to 2½ hours in generation times long enough to allow such variability. Division of the micronucleus occurs shortly before the cell begins to divide; its DNA synthesis starts immediately and continues after cell division for a total period estimated at about an hour.

La juventud rural en Colombia: estudio crítico sobre el acceso a la formación académica superior

2016 ◽  
Vol 9 (14) ◽  
pp. 166-181
Author(s):  
Elvis Pinzón Laitón
Keyword(s):  
Higher Education ◽  
Time Lapse ◽  
The State ◽  
Media Education ◽  
Rural Sector ◽  
Life Project ◽  
Life Styles ◽  
The Right ◽  
Public Politics

El escrito demuestra que los(as) jóvenes del sector ru- ral, con relación a la educación superior, requieren de una pronta y justa atención por parte del Estado para ayudarlos(as) a superar las dificultades que afrontan una vez terminan la educación media, de modo que no vean frustrado el desarrollo de su proyecto de vida. Enfatiza en la importancia de la formulación y ejecución de polí- ticas públicas claras y adecuadas a las necesidades de los egresados de aquellos municipios distantes a las universi- dades, caso específico los de Tununguá, Boyacá, Colom- bia. Defiende la educación como el medio más importante para el desarrollo del sector rural en el país; esto implica cobertura, ayuda económica, orientación a las familias y compromiso del (la) joven para hacer parte de procesos formativos a nivel profesional en el campo de conocimien- to de su preferencia, y de esta forma acceder a otros estilos de vida para su familia, en el marco de un país que recono- ce el derecho a la igualdad.The writing shows that the young’s of the rural sector in relation to higher education, require a prompt and fair attention of the state to help to overcome the difficulties they face once, they finish their media education studies, frustrating the development of the life project, of each teenage, which is built in this time lapse. It focuses on the importance of the formulation and execution of clear public politics suitable to the necessity of the graduates of those towns distant of the universities as is the specific case of Tununguá (Boyacá, Colombia). It defends the ed- ucation line the most suitable media for the development of the rural sector in our country. It implies coverage, economic help, orientation to the families and commit- ment of the young to make part of formative processes at professional level in the knowledge field the student selects and on this way to get other life styles for their families inside the framework of a country that promul- gates the right to equality. 

Behaviour ofStreptococcus lactisin heat treated (80 °C for 30 min) or sterilized cow's and ewe's milk

1983 ◽  
Vol 50 (3) ◽  
pp. 357-363 ◽  
Author(s):  
Francisco J. Chavarri ◽  
Jose A. Nuñez ◽  
Manuel Nuñez
Keyword(s):  
Acid Production ◽  
Generation Time ◽  
Buffer Capacity ◽  
Cow’S Milk ◽  
Cow's Milk ◽  
Vitamin Content ◽  
Streptococcus Lactis ◽  
Generation Times ◽  
Heat Treated ◽  
Ewe's Milk

SummaryGeneration times and acid production after 6 and 24 h by 20 strains ofStreptococcus lactisof dairy origin were determined in heat treated (80 °C for 30 min) and sterilized cow's and ewe's milk. Ewe's milk enhanced growth of the streptococci, with significantly (P< 0·001) shorter generation times and higher acid production after 6 h incubation than cow's milk, probably due to its higher vitamin content. The stronger buffer capacity of ewe's milk allowed a higher (P< 0·001) acid production after 24 h than cow's milk. A stimulatory effect of sterilization on generation time and acid production after 24 h was observed in cow's milk. However, the heat treated ewe's milk was shown to be a better substrate than sterilized ewe's milk forStr. lactis.

Nanostructured Doped Silica Films Application as Sensitive Layers for Chemical Sensors

2013 ◽  
Vol 684 ◽  
pp. 7-11
Author(s):  
Sergey Krutovertsev ◽  
Alla Tarasova ◽  
Olga Ivanova ◽  
Larisa Krutovertseva
Keyword(s):  
Initial Conditions ◽  
Sol Gel ◽  
Silica Films ◽  
Adsorption Activity ◽  
Developed Surface ◽  
Sol Gel Process ◽  
Sensitive Characteristics ◽  
The Right ◽  
Kinetics Of ◽  
Matrix Factors

The sensor behavior of nanostructured doped silica films produced by sol-gel way were examined. Hygroscopic substances and polyoxometalates were used as additives to make more significant sensitive characteristics of initial matrix. Factors that have effect on sol preparation and films forming were investigated. Adsorption activity of the sensitive films was studied and it was shown that the films had a highly developed surface with nano-size pores. Change of initial conditions of sol-gel process gives opportunity to influence on kinetics of gel formation and consequently, on structure and properties of final materials. The study showed that the conditions of the environment affected the sensors characteristics markedly, which can be improved by choosing of the right procedure of forming and treatment. Influence of type and additive substances quantity into doped films was discussed in the paper

scholarly journals Cell kinetics of human tumors by in vitro bromodeoxyuridine labeling.

1989 ◽  
Vol 37 (9) ◽  
pp. 1449-1454 ◽  
Author(s):  
J S Meyer ◽  
J Nauert ◽  
S Koehm ◽  
J Hughes
Keyword(s):  
Tritiated Thymidine ◽  
S Phase ◽  
Dna Flow Cytometry ◽  
Breast Carcinomas ◽  
Brdu Labeling ◽  
The Central Nervous System ◽  
Labeling Method ◽  
Kinetics Of

We labeled active S-phase cells in primary breast carcinomas with a modified 5-bromo-2'-deoxyuridine (BrdU) procedure using a silver-enhanced colloidal gold visualization step. Separate samples of 29 tumors were labeled with BrdU or tritiated thymidine ([3H]-dThd), and the labeling indices (LI) from the two methods were equivalent (Spearman's correlation coefficient = 0.96). Three breast carcinomas were incubated in various mixes of both BrdU and [3H]-dThd and developed sequentially for each. Paired photomicrographs showed that the same nuclei were labeled by either precursor. The in vitro method yielded LIs similar to those reported after in vivo pulse BrdU labeling for tumors of the central nervous system. The BrdU LI correlated significantly (r = 0.76, p less than 0.001) with % S-phase by DNA flow cytometry in 33 breast carcinomas. The BrdU labeling method is simpler and more rapid than the [3H]-dThd procedure (1-2 days for completion for the former, 7-10 days for the latter), and it provides an equivalent measurement of proliferative index.

scholarly journals Karakteristik Katarak Kongenital di RSUD Provinsi NTB Periode 2018-2019

2021 ◽  
Vol 1 (12) ◽  
pp. 946-956
Author(s):  
Rani Salsabilla ◽  
Marie Yuni Andari ◽  
Monalisa Nasrul
Keyword(s):  
General Hospital ◽  
Age Distribution ◽  
Secondary Data ◽  
The West ◽  
Congenital Cataracts ◽  
Natural Birth ◽  
History Of ◽  
The Right ◽  
The City ◽  
Descriptive Method

Congenital cataracts are the leading cause of blindness in children. Lens opacity in early life has the potential to cause permanent visual impairment if not treated promptly. Cataract surgery performed at the right time can prevent children from amblyopia (lazy eye). This study aims to determine the characteristics of congenital cataracts at the West Nusa Tenggara Provincial General Hospital in the 2018-2019 period. This research uses descriptive method. The data used is secondary data from medical records of congenital cataract patients at the West Nusa Tenggara Provincial General Hospital in the 2018-2019 period. In the 2018-2019 period, 40 children had congenital cataracts. Most of the cataract sufferers were women (52.5%); living outside the city of Mataram (92.5%) with an age distribution of under 12 months (95%) and the rest over 12 months. For infants under 12 months, 53 percent have been diagnosing at the age of 1-2 months. The characteristics of congenital cataracts found were generally bilateral (52.5%), had standard birth weight (52.5%), history of natural birth delivery (67.5%), and had other extraocular congenital abnormalities (72.5%). Most patients with congenital cataracts in the West Nusa Tenggara Provincial General Hospital have been diagnosing at a (pretty/moderately) early age of 1-2 months at the beginning of their lives. So, with appropriate and prompt therapy, hoping that it can reduce the risk of amblyopia.

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