Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Population Decrease”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed2002

[Analysis of underage births among girls in the city of Poznan in 1996-2001].

Negative natural increase in the population, decrease of total fertility rate, as well as older age of first pregnancy are characteristic phenomena for the population of Poznań. At the other end of the spectrum there are cases of underage pregnancies where young mothers are emotionally immature and unprepared to act as a mother. An analysis of underage deliveries based on medical notes was conducted in Gynecological/Obstetric Ward in District General Hospital in Poznań in the years 1996-2001. In the research following factors were considered: duration of the pregnancy, maternal age, reasons for admission of the parturient, as well as neonatal Apgar score, birth weight and number of children delivered. Out of all deliveries there were 2.3% of underage deliveries in the period studied. Amongst the parturients the majority (60.4%) were 17 years old and 15 of them were multiparas who already delivered one baby in the past. There was only one case of twins. 75.3% were normal deliveries, 20.9% cesarean section--both between 38-42 gestational weeks as within the population of all parturients. Main reasons for admission were: the risk of premature labour, PIH, foetal malposition. There were 241 underage deliveries with one stillbirth. The weight of the majority of the newborn fell between 2500-3999 g. In 10 cases the condition of the newborn was considered serious and very serious.

Adolescent↗
PubMed1976

Monoclonal B-lymphocytes in peripheral blood of patients with plasma cell myeloma. Relation to activity of the disease.

Antisera were produced in rabbits against idiotypic determinants of the myeloma protein from 3 patients with IgG-k myeloma. The antisera did neither cross-react nor react with normal immunoglobulin (Ig). Idiotypic Ig-structures were demonstrated by indirect immunofluorescence (IFL) on 70-94% of peripheral B-lymphocytes inuntreated patients. The total numbers of circulating B-lymphocytes were increased with a simultaneous decrease of T-lymphocytes. Only one of the patients had blood lymphocytes which stained for cytoplasmic Ig with idiotypic antiserum. The monoclonal lymphocyte population decreased gradually during treatment. Plasma cell counts in bone marrow, IgG concentration in serum and erythrocyte sedimentation rate decreased simultaneously, whilt the haemoglobin concentration increased. Very few monoclonal lymphocytes were present during remission. Later, the monoclonal lymphocyte population began to increase in 2 of the patients in parallel with clinical signs indicating relapse. It is concluded that presence of monoclonal B-lymphocytes indicates dissemination of the disease and that they may belong to the malignant cell clone.

B-Lymphocytes↗
PubMed1979

Proton magnetic resonance studies of 5,6-saturated thymidine derivatives produced by ionizing radiation. Conformational analysis of 6-hydroxylated diastereoisomers.

The conformational properties of ten 6-hydroxylated dihydrothymidine derivatives including the various diastereoisomers of 5,6-dihydroxy-5,6-dihydrothymidine, 6-hydroxy-5,6-dihydrothymidine and 5-bromo-6-hydroxy-5,6-dihydrothymidine have been studied by 250 MHz proton magnetic resonance in aqueous solutions. A close correlation has been established between the carbon-6 configuration and the osidic conformation. The increase in the amplitude of the puckering within the furanose ring compared to that of thymidine or 2'-deoxyuridine is more pronounced for the levorotatory (6S) nucleosides than for the dextrorotatory (6R) diastereoisomers. The importance of the 2' endo conformer population decreases in the following order: (-) greater than (+) greater than thymidine. The absence of destabilizing effects on the g+ rotameric population about the C(4')-C(5') bond denotes the lack of any interaction between the exocyclic hydroxymethyl group and the 6-hydroxyl function or the 2-keto group. The 5,6-saturated nucleosides adopt a preferential anti conformation. The comparison has been extended to syn nucleosides which show opposite trends in the sugar conformation and g+ distribution.

Magnetic Resonance Spectroscopy↗
PubMed1990

Radiosensitivity throughout the cell cycle and repair of potentially lethal damage and DNA double-strand breaks in an X-ray-sensitive CHO mutant.

The response to ionizing radiation of synchronized and plateau-phase populations of xrs-5 cells was studied at the DNA and cellular level. Induction and repair of DNA double-strand breaks (dsb) were measured by the non-unwinding filter elution technique. Biphasic survival curves were obtained throughout the cell cycle as well as in the plateau phase, suggesting the presence in the cultures of a radiation-sensitive and a radiation-resistant subpopulation. Delayed plating of plateau-phase xrs-5 cells did not significantly modify cell survival indicating a deficiency in the repair of potentially lethal damage (PLD). Post-irradiation treatment with araA further indicated a deficiency in the repair of a form of PLD sensitive to this drug in the radiation-sensitive subpopulation. The radiosensitivity of synchronized populations decreased as cells progressed through S. Cells in late S were found to be most resistant to radiation, whereas cells irradiated in G2 + M had a sensitivity similar to that of cells irradiated in G1. The decrease in radiosensitivity in S was tentatively attributed to an increase in the proportion of radioresistant cells in the cell population. Preliminary analysis of the results obtained, assuming the presence of two subpopulations showing an exponential response as a function of dose, indicated no change in the D0 values of the radiation-sensitive and the radiation-resistant component throughout the cell cycle. The D0 value of the radiation-resistant component was similar to the D0 of repair-proficient CHO cells. At no stage in the cell cycle were shoulder-type survival curves observed. Transient expression of the xrs-5 repair gene may underlie the observed variation of radiosensitivity throughout the cell cycle. This gene expression could occur either at random, in a subpopulation of cells independent of cell cycle phase, or in a specific manner related to gene replication and the hemimethylated state transiently found immediately thereafter. It is proposed that the resistant tail observed in the survival curves throughout the cell cycle is due to the former phenomenon, and the decreased radiosensitivity in late S to the latter. xrs-5 cells were found to be deficient in dsb repair in the plateau phase of growth, as well as in G1 and mid-S phase. The latter observation indicates that the reduction in radiation sensitivity in S is not associated with a modulation in the ability of cells to repair dsb.

Animals↗
PubMed2003

Seasonal prevalence and susceptibility to agrochemicals of Tyrophagus similis (Acari: Acaridae) in spinach buds and agricultural soil under greenhouse conditions.

Seasonal prevalence of Tyrophagus similis was investigated from 1997 to 1998 in two spinach greenhouses in central Japan. Susceptibility of T. similis to agrochemicals was also tested in the laboratory. Tyrophagus similis density in the soil was low during the high temperature period from May to August. The density rapidly increased in late autumn and remained at a high level during the cool season from December to February. The number further increased in April and then rapidly decreased in May. The high temperatures in the greenhouses from spring to early autumn are considered the main causes of population decrease. Mites on spinach buds increased the number after those on and in the soil increased. Mites attacked spinach buds mostly in late autumn and early spring. Dichlorvos did not reduce the number of mites in either greenhouse even though it was highly toxic under laboratory condition. This discrepancy suggests that the mites in both the soil and spinach buds had little direct contact with the chemicals. These data suggest that once crop damage by mites is detected, it is usually too late to use chemicals, and that mites that live in the buds are protected from agrochemicals.

Animals↗
PubMed1992

Epidemic and demographic interaction in the spread of potentially fatal diseases in growing populations.

The spread of a potentially fatal infectious disease is considered in a host population that would increase exponentially in the absence of the disease. Taking into account how the effective contact rate C(N) depends on the population size N, the model demonstrates that demographic and epidemiological conclusions depend crucially on the properties of the contact function C. Conditions are given for the following scenarios to occur: (i) the disease spreads at a lower rate than the populations grows and does not modify the population growth rate: (ii) the disease initially spreads at a faster rate than the population grows and lowers the population growth rate in the long run and the following three subscenarios are possible: (iia) the population still grows exponentially, but at a slower rate; (iib) population growth is limited, but the population size does not decay; (iic) population increase is converted into population decrease.

Animals↗
PubMed2005

An age-structured model with delay mortality.

Many species experience aperiodic mortality. Yet, there is little or no understanding of how this event affects population dynamics. We have considered one of the most simple class of age-structured models, namely, the MacKendrick Von Foerster type equations with suitable modifications to suit the purpose of this study. The main result shows the effect of delay in the estimate of the population. If the delay parameter is taken as a period, then the model equations describe the dynamics of seasonal insects such as locusts whose large population decreases very fast.

Age Factors↗
PubMed1980

Ontogeny of B lymphocyte function. VIII. Failure of thymus cells from aged donors to induce the functional maturation of B lymphocytes from immature donors.

The role of thymus cells in mediating a step in the ontogeny of the capacity of the B cell population to produce a heterogeneous, high-affinity, primary, plaque-forming cell (PFC) response was further investigated. It was shown that the thymus acquires the capacity to facilitate this step in B cell differentiation between 3 and 4 weeks of age in C57BL/6 mice. This corresponds to the age at which te splenic B cell population of these mice naturally acquires the capacity to produce high-affinity PFC. The differentiation of the B cell population. It was further shown that regulates this step in the cells to facilitate the maturation of B cell population. It was further shown that the ability of thymus cells to facilitate the maturation of the B cell population decreases with age and is already markedly reduced in 30-week-old, long-lived, C57BL/6 mice. A qualitative or quantitative decrease in thymic function may thus be responsible for age-related changes in the function of the B cell population.

Aging↗
PubMed1978

Ca2+ binding, ATP-dependent Ca2+ transport, and total tissue Ca2+ in embryonic and adult avian dystrophic pectoralis.

Avian muscular dystrophy is an autosomal recessive genetic disease characterized by early hypertrophy and loss of function of pectoralis major. The disease is progressive, ultimately resulting in atrophy and heavy lipid deposition. Previous investigators have noted a decrease in the ability of the dystrophic sarcoplasmic reticulum to concentrate Ca2+. More recently, other investigators have shown an abnormal calcium uptake in avian dystrophic sarcoplasmic reticulum. They indicated, using freeze-fracture techniques, that a 90 A particle of the vesicle membrane exhibited a decreased population and suggested that they might be the ATPase involved in calcium transport. Our studies confirm earlier observations of a decreased rate of Ca2+ uptake and Ca2+ binding capacity of dystrophic fragmented sarcoplasmic reticulum vesicles which are isolated from both embryonic and adult pectoralis. These observations correlate in turn with a 75% drop in the Ca:ATP transport efficiency of the dystrophic sarcoplasmic reticulum determined by measuring the rate of 32Pi liberation from gamma-ATP32 during active calcium transport by the isolated sarcoplasmic reticulum SR. In addition, we have found a quantitative deficiency in a 65,000 dalton component of the dystrophic fragmented SR at the time of myoblast fusion by measuring 35S-Methionine incorporation into the SR, coupled to high resolution polyacrylamide gel electrophoresis and radioautography. Analysis of total tissue calcium by atomic absorption spectroscopy revealed a decrease in the total calcium content of dystrophic muscle.

Adenosine Triphosphate↗
PubMedDate not supplied

The consumption bomb.

The explosion of the population bomb has long been predicted to cause massive famine in overpopulated countries. Rising consumption, even in a time of decreasing population growth rates, now threatens adverse global health effects more severe than localised famines. The world faces potential ecological entrapment. This has two dimensions: planetary eco-impoverisation and planetary eco-pathology. Eco-impoverisation, the depletion of natural capital, arises as the limit of the global human carrying capacity approaches. Eco-pathology, the disruption of ecological support systems, arises because of the way the biosphere has been modified by human activity and is caused particularly by unsustainable consumption for human purposes. Despite encroaching ecological entrapment, the dominant economic paradigm claims record levels of growth; a paradox that needs recognition. Reasons for denial of the gravity of ecological entrapment are discussed. Ways are suggested to defuse the consumption bomb and avert ecological entrapment.

Conservation of Natural Resources↗
PubMedDate not supplied

Assessment of selected co-stimulatory, adhesion and activatory molecules and cytokines of Th(1)/Th(2) balance in acute lymphoblastic leukemia in children.

INTRODUCTION: Recent years have seen a rise in the importance of cytokine production and co-stimulatory/activatory molecule expression in the immune response in leukemia. The aim of our study was to assess the function of T lymphocytes in children with acute lymphoblastic leukemia (ALL) during remission induction based on selected cytokine and co-stimulatory/activatory molecule expression. MATERIAL/METHODS: The study group consisted of 50 children with ALL (B cell precursor). Peripheral blood samples were taken before treatment (day 0), after the prednisone prophase (day 8), and during (day 15) and after (day 33) remission induction. The percentages of T cells with interferon (IFN)-gamma (Th(1)), interleukin (IL)-4 (Th(2)) and IL-2 receptor (IL-2R), CD28, CTLA-4, CD38, ICAM-1, and HLA-DR expression were assessed by tricolor flow cytometry. RESULTS: At the time of diagnosis we noted higher percentages of T cells with adhesion molecule ICAM-1, activation molecule CD38 expression, and an increased population of Th(2 )cells (IL-4) compared with the control group. During and after remission induction we observed a decreased population of CD38(+) T cells, elevated percentages of helper T lymphocytes with IL-2R expression, and a rise in helper T lymphocytes producing IFN-gamma (Th(1)). During fever/infection, higher levels of activated T lymphocytes (CD4(+)HLA-DR(+), CD8(+)HLA-DR(+)), a rise in Th1, and no change in Th(2 )populations were observed. CONCLUSIONS: The results suggest T cell activation and Th(2 )predominance at the time of diagnosis and during remission induction in ALL in children. These results confirm the involvement of cellular immunity in the leukemic process and can be used in immune therapy in leukemia.

CD28 Antigens↗
PubMed1993

Transfusion therapy: improved patient care and resource utilization.

Improving the quality of medical care while reducing costs is one of the major challenges facing the health care system in the United States. At a 1020-bed, tertiary-care, teaching hospital, the Transfusion Committee modified transfusion practice by establishing new transfusion guidelines based upon national standards rather than local practices and by implementing educational and monitoring systems. Over a 3-year period, the number of transfusions decreased, the types of transfused components changed, and the waste due to unused components decreased. From the baseline of Fiscal Year (FY) 1989 (89), the number of exposures to components from allogeneic blood donors for the patient population decreased by 11,015 in FY 90, 14,067 in FY 91, and 16,990 in FY 92, thereby decreasing the risk of transfusion-transmitted disease, transfusion reaction, and alloimmunization. As compared to costs in FY 89, the altered transfusion practices resulted in cost savings of $376,269 in FY 90, $566,375 in FY 91, and $684,704 in FY 92. Over the 3-year period, exposures to components from allogeneic blood donors for the patient population were reduced by 42,072, and the total cost savings was $1,627,348. The methodology and results should be reproducible at other hospitals.

Blood Component Transfusion↗
PubMed2002

Mantled howler population of Hacienda La Pacifica, Costa Rica, between 1991 and 1998: effects of deforestation.

A survey of the mantled howler (Alouatta palliata) population on Hacienda La Pacifica, Guanacaste, Costa Rica, was done in July and August of 1998 to determine population parameters following deforestation due to major canal construction between 1990 and 1994. The survey was carried out in a manner identical to our 1991 survey and consisted of a single pass and two re-surveys of all forested areas of the farm. As canal construction effectively increased fragmentation of the habitat, we predicted decreased population and group size over this time. Results indicated that between the 1991 and 1998 survey, group size decreased but not significantly, and there were significantly fewer adult males and adult females per group. Population size, however, remained unchanged as there was an increase in animals in the immature age classes. An increase in the infant to adult female ratio suggests a stable or even expanding population, which could represent recovery from the initial disturbance of deforestation. Thus, despite changes in the forest and land use patterns, the area now appears to support the same number of howlers as found in previous surveys.

Age Factors↗
PubMed1999

Monitoring methanotrophic bacteria in hybrid anaerobic-aerobic reactors with PCR and a catabolic gene probe.

We attempted to mimic in small upflow anaerobic sludge bed (UASB) bioreactors the metabolic association found in nature between methanogens and methanotrophs. UASB bioreactors were inoculated with pure cultures of methanotrophs, and the bioreactors were operated by using continuous low-level oxygenation in order to favor growth and/or survival of methanotrophs. Unlike the reactors in other similar studies, the hybrid anaerobic-aerobic bioreactors which we used were operated synchronously, not sequentially. Here, emphasis was placed on monitoring various methanotrophic populations by using classical methods and also a PCR amplification assay based on the mmoX gene fragment of the soluble methane monooxygenase (sMMO). The following results were obtained: (i) under the conditions used, Methylosinus sporium appeared to survive better than Methylosinus trichosporium; (ii) the PCR method which we used could detect as few as about 2,000 sMMO gene-containing methanotrophs per g (wet weight) of granular sludge; (iii) inoculation of the bioreactors with pure cultures of methanotrophs contributed greatly to increases in the sMMO-containing population (although the sMMO-containing population decreased gradually with time, at the end of an experiment it was always at least 2 logs larger than the initial population before inoculation); (iv) in general, there was a good correlation between populations with the sMMO gene and populations that exhibited sMMO activity; and (v) inoculation with sMMO-positive cultures helped increase significantly the proportion of sMMO-positive methanotrophs in reactors, even after several weeks of operation under various regimes. At some point, anaerobic-aerobic bioreactors like those described here might be used for biodegradation of various chlorinated pollutants.

Aerobiosis↗
PubMed1983

Epidemiologic characteristics of mortality from diabetes with acidosis or coma, United States, 1970-78.

Deaths due to diabetes with acidosis or coma (DAC) in the United States from 1970 through 1978 were analyzed to determine epidemiologic characteristics associated with mortality likely to be due to diabetic ketoacidosis (DKA), a complication of diabetes mellitus considered largely preventable. Annual age-adjusted rates for DAC deaths decreased during the study period, and the secular trend was significant in all regional, race, and sex groups examined. General population-based mortality rates increased linearly with age, were higher in non-Whites than in Whites among persons aged greater than 14, were higher in females, and increased significantly with age in both races and both sexes. By region, rates were lowest in the West. DAC mortality rates specific to estimated diabetic populations decreased annually from 1970 to 1978 in all race and sex groups, and were highest at age greater than or equal to 65, but did not show significant linear increases with age, except in non-Whites. These results indicate declining secular trends, as well as age, race, sex, and regional differences in the risk of such deaths. Further studies are warranted to determine factors contributing to these differences.

Adolescent↗
PubMedDate not supplied

[Malaria transmission in 1999 in the rice field area of the Kou Valley (Bama), (Burkina Faso)].

A longitudinal study based on mosquitoes sampled by larvae prospecting and adult catches on humans was carried out during 1999 in the rice field area of the Kou Valley (South-West Burkina Faso) to evaluate the malaria transmission level. Two sites were studied: VK5 located in the rice field centre and VK7 in the periphery. Irrigation is sub-permanent and two crops are grown each year: from February to June during the dry season and from July to November during the rainy season. A man sleeping in VK5 without any protection is exposed to more than 60,000 mosquito bites/year. Two majors vectors are present: Anopheles gambiae sl. and An. funestus. The An. gambiae M form which breeds in rice fields constitutes the majority of the complex. At the periphery of the rice fields, we observed a mix of M and S forms during the rainy season, the latter form coming from classical breeding sites created by rainfall (residual puddles). An. arabiensis is rare in this environment while we can find it in sympathy with An. gambiae in the surrounding savannah. An. gambiae remains present throughout the year. Its dynamics depends closely on both season and rice cycle. There are two density peaks, in March (210 bites/man/night) and in July (306 b/m/n), corresponding to the moment when rice is planted. The latter peak is more important due to additional productivity of residual puddles created by rainfall. These large and very young populations can not transmit malaria. Growing rice reduces larvae productivity: transmission occurs when the adult population decreases and becomes older. Variations in parity rate and sporozoitic index are inversely related to mosquito density. Finally, the An. gambiae population is lowest during the dry season in January when irrigation stops. An. funestus does not develop in rice fields but rather in drains made of dirt, in addition to the classical natural breeding sites at the end of the rainy season. The density of An. funestus is 25 to 30 times smaller than that of A. gambiae, as observed during 8 months in VK5 and 10 months in VK7, with a peak of 16 b/m/n in January. Its mean parity rate and sporozoitic index is higher than those of An. gambiae. An. funestus plays an additional role in malaria transmission at the same period as An. gambiae but more shortly and less intensively. Finally, malaria transmission is due mainly to An. gambiae (90%) and, to a lesser extent, to An. funestus (10%). It occurs in VK5 during two periods of four month search : from May to August and from November to February. In VK7, transmission is also bimodal but it occurs more extensively throughout the year with only July and Septemberas exemptions of transmission. The annual inoculation rate amounts to 697 and 515 infected bites per man. This value is higher than those obtained in 1984/1985 : 50 and 60 infected bites per man per year. This increase is due to both the growth of aggressive vectorial density and the sporozoitic index. Growth of adult density can be explained by the environmental modification and/or better adaptation of vectorial species. The sporozoitic index of vectors has been obtained using Elisa, which is twice as sensitive as the microscopic observations used in 1984/1985. This can partly explain the increase in the sporozoitic index. Other hypotheses in relation to human parasitological inputs have to be evaluated more accurately. The level and rhythm of transmission in the rice field in 1999 are more important than those registered in the surrounding savannah the same year. However, this important transmission is not proportionally related to the high vectorial density found in rice fields. Probably, it does not imply more malaria diseases, but its intensity and rhythm could concentrate malaria cases in young people with an early acquisition of premunition. Pyrethroid impregnated bednets should be used to prevent malaria especially since high mosquito nuisance drives local populations to use it and since the An. gambiae M form is particularly susceptible to this class of insecticides.

Adult↗
PubMed2003

[Individual and modular biomass dynamics of Kingdonia uninflora population in Qinling Mountain].

The individual and modular biomass dynamics of Kingdonia uninflora populations in Qinling Mountain were studied systematically. They could be expressed by Logistic equation. The ratio of leaf to bud biomass of population decreased with its increasing age, whereas the ratio of the root system to the subterranean stem biomass increased. The individual and each modular biomass of different populations at different altitudes were significant different (P < 0.05), which were larger at altitude 2700-2900 m than at the lower and higher altitudes. The rate of leaf biomass decreased as altitude rose, whereas that of the subterranean stem increased. In the favorable area, the rate of root system biomass was less, whereas the bud biomass was bigger compared with other habitats. The individual growth and modular biomass accumulation were closely related to habitat condition.

Altitude↗
PubMed1980

Populations of methane-producing bacteria and in vitro methanogenesis in salt marsh and estuarine sediments.

Most probable numbers (MPNs) of methanogens in various salt marsh and estuarine sediments were determined with an anaerobic, habitat-simulating culture medium with 80% H(2) plus 20% CO(2) as substrate. Average MPNs for the short Spartina (SS) marsh sediments of Sapelo Island, Ga., were maximal at the 5- to 7-cm depth (1.2 x 10/g of dry sediment). Populations decreased to approximately 880/g of dry sediment at the 34- to 36-cm depth. There was no significant difference between summer and winter populations. In tall Spartina (TS) marsh sediments, average populations were maximal (1.2 x 10/g of dry sediment) in the upper 0- to 2-cm zone; populations from the 5- to 36-cm zones were similar (average of 9 x 10/g of dry sediment). Methanogenic populations for TS sediments of James Island Creek marsh, Charleston, S.C., were similar (average of 3 x 10/g of dry sediment) for all depths tested (0 to 22 cm), which was comparable to the trend observed for TS sediments at Sapelo Island, Ga. Sediment grab samples collected along a transect of James Island Creek and its adjacent Spartina marsh had MPNs that were approximately 20 times greater for the region of Spartina growth (average of 10/g of dry sediment) compared with the channel (approximately 5 x 10 methanogens per g of dry sediment). A similar trend was found at Pawley's Island marsh, S.C., but populations were approximately one order of magnitude lower. In vitro rates of methanogenesis with SS sediments incubated under 80% H(2)-20% CO(2) showed that the 5- to 7-cm region exhibited maximal activity (51 nmol of CH(4) g h), which was greater than rates for sediments above and below this depth. SS sediment samples (5 to 7 cm) incubated under 100% N(2) and supplemented with formate exhibited rates of methanogenesis similar to those generated by samples under 80% H(2)-20% CO(2). Replacing the N(2) atmosphere with H(2) resulted in an eightfold decrease in the rate of methanogenesis. In vitro methanogenic activity by TS salt marsh sediments, incubated under 80% H(2)-20% CO(2), was similar for all depths tested (0 to 22 cm). TS sediment samples (0 to 7 cm) supplemented with formate and incubated under 100% N(2) had greater rates of methanogenesis compared with unsupplemented samples.

Journal Article↗