The regulation of Ostertagia ostertagi populations in calves: the effect of past and current experience of infection on proportional establishment and parasite survival

Parasitology ◽  
1987 ◽  
Vol 95 (2) ◽  
pp. 363-372 ◽  
Author(s):  
B. T. Grenfell ◽  
G. Smith ◽  
R. M. Anderson
Keyword(s):  
Death Rate ◽  
Published Data ◽  
Cumulative Number ◽  
Intensity Of Infection ◽  
Decay Function ◽  
Ostertagia Ostertagi ◽  
Parasite Survival ◽  
Parasitic Phase ◽  
Current Experience

SUMMARYA mathematical model of the parasitic phase of the life-cycle of Ostertagia ostertagi in calves is described. The model is used in the re-analysis of previously published data from a long-term trickle infection experiment in which groups of calves were infected daily with graded doses of 3rd-stage (L3) larvae. The results of the analysis are consistent with the hypothesis that the observed changes in the intensity of infection in the calves were the result of a decline in the proportional establishment of ingested L3 larvae, and a rise in the death rate of the 5th-stage worms as the duration of exposure to infection increased. The proportion of ingested L3 larvae that become established in the mucosa can be described as an exponential decay function of the duration of the infection. Within the range of trickle intensities investigated, the function appears to vary independently of the level of exposure to infection. In contrast, the rate of mortality of the 5th-stage worms appears to be an increasing linear function of the total cumulative number of 3rd-stage larvae administered.

The population biology of the parasitic stages of Haemonchus contortus

Parasitology ◽  
1988 ◽  
Vol 96 (1) ◽  
pp. 185-195 ◽  
Author(s):  
Gary Smith
Keyword(s):  
Haemonchus Contortus ◽  
Death Rate ◽  
Population Biology ◽  
Good Description ◽  
A Priori ◽  
Infection Experiment ◽  
Duration Of Infection ◽  
Immune Exclusion ◽  
Parasitic Phase

SUMMARYThe population biology of the parasitic phase of the Haemonchus contortus life-cycle is discussed within the context of a mathematical model of those processes which regulate population density. Parasite death is assumed to be attributable to at least three processes: failure of the 3rd-stage larvae (L3) to exsheath following ingestion, failure to become established following exsheathment (immune exclusion), and mortality of 4th- and 5th-stage worms on the mucosal surface. The proportion of worms which avoid immune exclusion is a declining sigmoidal function of the duration of infection, at least under conditions of continual exposure to L3 larvae. Under the same conditions, the death rate of 4th- and 5thstage worms can be modelled as an increasing linear function of the host's experience of 3rd stage larvae. The model provides a good description of the worm burdens observed during the course of a long-term trickle infection experiment even though a priori arguments indicate that it would be an inadequate representation of events in the field.

Periprocedural risk and long-term outcome of intracranial angioplasty based on a single-centre experience

VASA ◽  
2013 ◽  
Vol 42 (4) ◽  
pp. 264-274
Author(s):  
Dagmar Krajíčková ◽  
Antonín Krajina ◽  
Miroslav Lojík ◽  
Martina Mulačová ◽  
Martin Vališ
Keyword(s):  
Death Rate ◽  
Long Term Outcomes ◽  
Single Centre ◽  
Intracranial Atherosclerotic Stenosis ◽  
Atherosclerotic Stenosis ◽  
Angioplasty And Stenting ◽  
Aggressive Medical Management ◽  
Stroke Death

Background: Intracranial atherosclerotic stenosis is a major cause of stroke and yet there are currently no proven effective treatments for it. The SAMMPRIS trial, comparing aggressive medical management alone with aggressive medical management combined with intracranial angioplasty and stenting, was prematurely halted when an unexpectedly high rate of periprocedural events was found in the endovascular arm. The goal of our study is to report the immediate and long-term outcomes of patients with ≥ 70 % symptomatic intracranial atherosclerotic stenosis treated with balloon angioplasty and stent placement in a single centre. Patients and methods: This is a retrospective review of 37 consecutive patients with 42 procedures of ballon angioplasty and stenting for intracranial atherosclerotic stenosis (≥ 70 % stenosis) treated between 1999 and 2012. Technical success (residual stenosis ≤ 50 %), periprocedural success (no vascular complications within 72 hours), and long-term outcomes are reported. Results: Technical and periprocedural success was achieved in 90.5 % of patients. The within 72 hours periprocedural stroke/death rate was 7.1 % (4.8 % intracranial haemorrhage), and the 30-day stroke/death rate was 9.5 %. Thirty patients (81 %) had clinical follow-up at ≥ 6 months. During follow-up, 5 patients developed 6 ischemic events; 5 of them (17 %) were ipsilateral. The restenosis rate was 27 %, and the retreatment rate was 12 %. Conclusions: Our outcomes of the balloon angioplasty/stent placement for intracranial atherosclerotic stenosis are better than those in the SAMMPRIS study and compare favourably with those in large registries and observational studies.

Update on the Boundaries of the Curly Birch Range

2020 ◽  
pp. 9-21
Author(s):  
L.V. Vetchinnikova ◽  
◽  
A.F. Titov ◽  
◽  
Keyword(s):  
Population Size ◽  
Natural Populations ◽  
Forest Tree ◽  
Published Data ◽  
Population Approach ◽  
Key Factors ◽  
History Of ◽  
Individual Trees ◽  
Karelian Birch

The article reports on the application of the best known principles for mapping natural populations of curly (Karelian) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti – one of the most appealing representatives of the forest tree flora. Relying on the synthesis and analysis of the published data amassed over nearly 100 years and the data from own full-scale studies done in the past few decades almost throughout the area where curly birch has grown naturally, it is concluded that its range outlined in the middle of the 20th century and since then hardly revised is outdated. The key factors and reasons necessitating its revision are specified. Herewith it is suggested that the range is delineated using the population approach, and the key element will be the critical population size below which the population is no longer viable in the long term. This approach implies that the boundaries of the taxon range depend on the boundaries of local populations (rather than the locations of individual trees or small clumps of trees), the size of which should not be lower than the critical value, which is supposed to be around 100–500 trees for curly birch. A schematic map of the curly birch range delineated using this approach is provided. We specially address the problem of determining the minimum population size to secure genetic diversity maintenance. The advantages of the population approach to delineating the distribution range of curly birch with regard to its biological features are highlighted. The authors argue that it enables a more accurate delineation of the range; shows the natural evolutionary history of the taxon (although it is not yet officially recognized as a species) and its range; can be relatively easily updated (e.g. depending on the scope of reintroduction); should be taken into account when working on the strategy of conservation and other actions designed to maintain and regenerate this unique representative of the forest tree flora.

scholarly journals Parenteral Nutrition and Oxidant Load in Neonates

Nutrients ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 2631
Author(s):  
Kandeepan Karthigesu ◽  
Robert F. Bertolo ◽  
Robert J. Brown
Keyword(s):  
Parenteral Nutrition ◽  
Storage Temperature ◽  
Oral Feeding ◽  
Published Data ◽  
Short Term ◽  
Antioxidant Defences ◽  
Term Survival ◽  
Nutrient Sources ◽  
Short Term Survival

Neonates with preterm, gastrointestinal dysfunction and very low birth weights are often intolerant to oral feeding. In such infants, the provision of nutrients via parenteral nutrition (PN) becomes necessary for short-term survival, as well as long-term health. However, the elemental nutrients in PN can be a major source of oxidants due to interactions between nutrients, imbalances of anti- and pro-oxidants, and environmental conditions. Moreover, neonates fed PN are at greater risk of oxidative stress, not only from dietary sources, but also because of immature antioxidant defences. Various interventions can lower the oxidant load in PN, including the supplementation of PN with antioxidant vitamins, glutathione, additional arginine and additional cysteine; reduced levels of pro-oxidant nutrients such as iron; protection from light and oxygen; and proper storage temperature. This narrative review of published data provides insight to oxidant molecules generated in PN, nutrient sources of oxidants, and measures to minimize oxidant levels.

scholarly journals A global association between Covid-19 cases and airborne particulate matter at regional level

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Angelo Solimini ◽  
F. Filipponi ◽  
D. Alunni Fegatelli ◽  
B. Caputo ◽  
C. M. De Marco ◽  
...  
Keyword(s):  
Air Pollution ◽  
Particulate Matter ◽  
Negative Binomial ◽  
Numerical Models ◽  
Regional Level ◽  
Pollution Level ◽  
Observation Data ◽  
Cumulative Number ◽  
Mixed Effect

AbstractEvidences of an association between air pollution and Covid-19 infections are mixed and inconclusive. We conducted an ecological analysis at regional scale of long-term exposure to air-borne particle matter and spread of Covid-19 cases during the first wave of epidemics. Global air pollution and climate data were calculated from satellite earth observation data assimilated into numerical models at 10 km resolution. Main outcome was defined as the cumulative number of cases of Covid-19 in the 14 days following the date when > 10 cumulative cases were reported. Negative binomial mixed effect models were applied to estimate the associations between the outcome and long-term exposure to air pollution at the regional level (PM10, PM2.5), after adjusting for relevant regional and country level covariates and spatial correlation. In total we collected 237,749 Covid-19 cases from 730 regions, 63 countries and 5 continents at May 30, 2020. A 10 μg/m3 increase of pollution level was associated with 8.1% (95% CI 5.4%, 10.5%) and 11.5% (95% CI 7.8%, 14.9%) increases in the number of cases in a 14 days window, for PM2.5 and PM10 respectively. We found an association between Covid-19 cases and air pollution suggestive of a possible causal link among particulate matter levels and incidence of COVID-19.

Psychotic disorders in young adults with perinatally acquired HIV: a UK case series

2020 ◽  
pp. 1-7
Author(s):  
I. Mallik ◽  
T. Pasvol ◽  
G. Frize ◽  
S. Ayres ◽  
A. Barrera ◽  
...  
Keyword(s):  
Mental Health ◽  
Young Adults ◽  
Young People ◽  
Case Series ◽  
Psychotic Episode ◽  
Published Data ◽  
Growing Up ◽  
Term Care ◽  
Perinatally Acquired

Abstract Background Increasing numbers of children with perinatally acquired HIV (PaHIV) are transitioning into adult care. People living with behaviourally acquired HIV are known to be at more risk of psychosis than uninfected peers. Young adults living with PaHIV face numerous risk factors; biological: lifelong exposure to a neurotrophic virus, antiretroviral medication and immune dysfunction during brain development, and environmental; social deprivation, ethnicity-related discrimination, and migration-related issues. To date, there is little published data on the prevalence of psychotic illness in young people growing up with PaHIV. Methods We conducted a retrospective case note review of all individuals with PaHIV aged over 18 years registered for follow up at a dedicated clinic in the UK (n = 184). Results In total, 12/184 (6.5%), median age 23 years (interquartile range 21–26), had experienced at least one psychotic episode. The presentation and course of the psychotic episodes experienced by our cohort varied from short-lived symptoms to long term illness and nine (75%) appear to have developed a severe and enduring mental illness requiring long term care. Conclusion The prevalence of psychosis in our cohort was clearly above the lifetime prevalence of psychosis in UK individuals aged 16–34 years, which has been reported to be 0.5–1.0%. This highlights the importance of clinical vigilance regarding the mental health of young people growing up with PaHIV and the need to integrate direct access to mental health services within the HIV centres providing medical care.

Heterogeneity and the modelling of bacterial spore death: the case of continuously decreasing death rate

1977 ◽  
Vol 23 (11) ◽  
pp. 1501-1507 ◽  
Author(s):  
Ken Sharpe ◽  
Roger M. Bektash
Keyword(s):  
Heat Resistance ◽  
Death Rate ◽  
Bacterial Spore ◽  
Bacterial Spores ◽  
Heating Process ◽  
Published Data ◽  
Model Based

Models for the inactivation of bacterial spores for the case of continuously decreasing death rate are reviewed and extended to show that it is not possible to distinguish between one particular model based upon the innate heterogeneity of the population and that based upon the acquisition of heat resistance during the heating process. Two innate heterogeneity models have been fitted to published data.

Influence of agricultural management on soil organic carbon: A compendium and assessment of Canadian studies

2003 ◽  
Vol 83 (4) ◽  
pp. 363-380 ◽  
Author(s):  
A. J. VandenBygaart ◽  
E. G. Gregorich ◽  
D. A. Angers
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Management Practices ◽  
Agricultural Management ◽  
Organic Fertilizers ◽  
Published Data ◽  
Native Land ◽  
Soc Stocks ◽  
Long Term Studies

To fulfill commitments under the Kyoto Protocol, Canada is required to provide verifiable estimates and uncertainties for soil organic carbon (SOC) stocks, and for changes in those stocks over time. Estimates and uncertainties for agricultural soils can be derived from long-term studies that have measured differences in SOC between different management practices. We compiled published data from long-term studies in Canada to assess the effect of agricultural management on SOC. A total of 62 studies were compiled, in which the difference in SOC was determined for conversion from native land to cropland, and for different tillage, crop rotation and fertilizer management practices. There was a loss of 24 ± 6% of the SOC after native land was converted to agricultural land. No-till (NT) increased the storage of SOC in western Canada by 2.9 ± 1.3 Mg ha-1; however, in eastern Canada conversion to NT did not increase SOC. In general, the potential to store SOC when NT was adopted decreased with increasing background levels of SOC. Using no-tillage, reducing summer fallow, including hay in rotation with wheat (Triticum aestivum L.), plowing green manures into the soil, and applying N and organic fertilizers were the practices that tended to show the most consistent in creases in SOC storage. By relating treatment SOC levels to those in the control treatments, SOC stock change factors and their levels of uncertainty were derived for use in empirical models, such as the United Nations Intergovernmental Panel on Climate Change (IPCC). Guidelines model for C stock changes. However, we must be careful when attempting to extrapolate research plot data to farmers’ fields since the history of soil and crop management has a significant influence on existing and future SOC stocks. Key words: C sequestration, tillage, crop rotations, fertilizer, cropping intensity, Canada

scholarly journals Long-term follow-up after colorectal endoscopic submucosal dissection in 182 cases

2021 ◽  
Vol 09 (02) ◽  
pp. E258-E262
Author(s):  
Christian Suchy ◽  
Moritz Berger ◽  
Ingo Steinbrück ◽  
Tsuneo Oyama ◽  
Naohisa Yahagi ◽  
...  
Keyword(s):  
Case Series ◽  
En Bloc Resection ◽  
Bloc Resection ◽  
Published Data ◽  
Low Grade ◽  
Recurrence Rates ◽  
En Bloc ◽  
Long Term Follow Up

Abstract Background and study aims We previously reported a case series of our first 182 colorectal endoscopic submucosal dissections (ESDs). In the initial series, 155 ESDs had been technically feasible, with 137 en bloc resections and 97 en bloc resections with free margins (R0). Here, we present long-term follow-up data, with particular emphasis on cases where either en bloc resection was not achieved or en bloc resection resulted in positive margins (R1). Patients and methods Between September 2012 and October 2015, we performed 182 consecutive ESD procedures in 178 patients (median size 41.0 ± 17.4 mm; localization rectum vs. proximal rectum 63 vs. 119). Data on follow-up were obtained from our endoscopy database and from referring physicians. Results Of the initial cohort, 11 patients underwent surgery; follow-up data were available for 141 of the remaining 171 cases (82,5 %) with a median follow-up of 2.43 years (range 0.15–6.53). Recurrent adenoma was observed in 8 patients (n = 2 after margin positive en bloc ESD; n = 6 after fragmented resection). Recurrence rates were lower after en bloc resection, irrespective of involved margins (1.8 vs. 18,2 %; P < 0.01). All recurrences were low-grade adenomas and could be managed endoscopically. Conclusions The rate of recurrence is low after en bloc ESD, in particular if a one-piece resection can be achieved. Recurrence after fragmented resection is comparable to published data on piecemeal mucosal resection.

Long-term Aptian marine osmium isotopic record of Ontong Java Nui activity

Geology ◽  
2021 ◽  
Author(s):  
Hironao Matsumoto ◽  
Rodolfo Coccioni ◽  
Fabrizio Frontalini ◽  
Kotaro Shirai ◽  
Luigi Jovane ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Volcanic Eruptions ◽  
Hydrothermal Activity ◽  
Published Data ◽  
Isotopic Data ◽  
Oceanic Plateaus ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Isotopic Records

The early to mid-Aptian was punctuated by episodic phases of organic-carbon burial in various oceanographic settings, which are possibly related to massive volcanism associated with the emplacement of the Ontong Java, Manihiki, and Hikurangi oceanic plateaus in the southwestern Pacific Ocean, inferred to have formed a single plateau called Ontong Java Nui. Sedimentary osmium (Os) isotopic compositions are one of the best proxies for determining the timing of voluminous submarine volcanic episodes. However, available Os isotopic records during the age are limited to a narrow interval in the earliest Aptian, which is insufficient for the reconstruction of long-term hydrothermal activity. We document the early to mid-Aptian Os isotopic record using pelagic Tethyan sediments deposited in the Poggio le Guaine (Umbria-Marche Basin, Italy) to precisely constrain the timing of massive volcanic episodes and to assess their impact on the marine environment. Our new Os isotopic data reveal three shifts to unradiogenic values, two of which correspond to black shale horizons in the lower to mid-Aptian, namely the Wezel (herein named) and Fallot Levels. These Os isotopic excursions are ascribed to massive inputs of unradiogenic Os to the ocean through hydrothermal activity. Combining the new Os isotopic record with published data from the lowermost Aptian organic-rich interval in the Gorgo a Cerbara section of the Umbria-Marche Basin, it can be inferred that Ontong Java Nui volcanic eruptions persisted for ~5 m.y. during the early to mid-Aptian.

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