scholarly journals The role of biotic factors during plant establishment in novel communities assessed with an agent-based simulation model

2017 ◽  
Author(s):  
Janina Radny ◽  
Katrin M Meyer
Keyword(s):  
Survival Rate ◽  
Simulation Model ◽  
Native Species ◽  
Native Plants ◽  
Survival Rates ◽  
High Survival ◽  
Native Community ◽  
Establishment Success ◽  
Positive Effects ◽  
Negative Effect

Background. Establishment success of non-native species can be influenced by interactions with native competitors and novel enemies. Magnitude of interactions between species is mediated by traits, e.g. reflecting competitive strength or defence mechanisms. We combine the concepts to investigate the importance of species traits for successful establishment in a novel community exhibiting biotic resistance in the form of competition and herbivory. Methods. We developed an individual-based simulation model that tracks survival rate of non-native plants in a native community. Non-native plants are characterized by high or low values of traits relevant for interaction with competitors and herbivores. Results. Traits related to competition had a much greater impact on survival of non-native species than traits related to defence. Survival rates of strong competitors never fell below 50% while survival of weak competitors averaged about 10%. Weak competitors were also much more sensible to competitive pressures including community density, composition and asymmetry while strong competitors responded negatively to changes in competition intensity but hardly to composition or density of native community. High initial numbers of non-native individuals did decrease survival rate of strong competitors but slightly increased survival rate of weak competitors. In the current model configuration we detected only minor advantages in terms of higher survival from high defensive ability as compared to low defensive ability under enemy attack. Surprisingly, herbivory increased survival rate of species classified as weak competitors. Discussion. High survival rates of strong competitors relate to a higher chance of establishment as compared to weak competitors. However, the negative effect of high initial numbers for strong competitive non-natives indicates a self-thinning effect, probably through creation of a highly competitive milieu. For weak competitors, our model predicted increasing survival rates at high initial densities. Positive effects of high propagule pressure have been proposed in field studies and are underlined with this model. However, our model largely overestimated mortality as compared to the preceding experiment. This could be improved by implementing more sophisticated competition modes and traits reflecting tolerance and avoidance of competition by non-native plants. This would, however, be very costly in terms of parameterization. Herbivory had a very low negative effect on survival in general and an advantage of high defence was almost untraceable. However, the positive effect of herbivory on survival of weak competitors indicated that herbivory should not be neglected in estimation of establishment success of species. Although the immediate and expected effect of herbivory might be small, side effects as weakening of resident competitors might play an important role for establishment in a new community.

scholarly journals The role of biotic factors during plant establishment in novel communities assessed with an agent-based simulation model

2017 ◽  
Author(s):  
Janina Radny ◽  
Katrin M Meyer
Keyword(s):  
Survival Rate ◽  
Simulation Model ◽  
Native Species ◽  
Native Plants ◽  
Survival Rates ◽  
High Survival ◽  
Native Community ◽  
Establishment Success ◽  
Positive Effects ◽  
Negative Effect

Background. Establishment success of non-native species can be influenced by interactions with native competitors and novel enemies. Magnitude of interactions between species is mediated by traits, e.g. reflecting competitive strength or defence mechanisms. We combine the concepts to investigate the importance of species traits for successful establishment in a novel community exhibiting biotic resistance in the form of competition and herbivory. Methods. We developed an individual-based simulation model that tracks survival rate of non-native plants in a native community. Non-native plants are characterized by high or low values of traits relevant for interaction with competitors and herbivores. Results. Traits related to competition had a much greater impact on survival of non-native species than traits related to defence. Survival rates of strong competitors never fell below 50% while survival of weak competitors averaged about 10%. Weak competitors were also much more sensible to competitive pressures including community density, composition and asymmetry while strong competitors responded negatively to changes in competition intensity but hardly to composition or density of native community. High initial numbers of non-native individuals did decrease survival rate of strong competitors but slightly increased survival rate of weak competitors. In the current model configuration we detected only minor advantages in terms of higher survival from high defensive ability as compared to low defensive ability under enemy attack. Surprisingly, herbivory increased survival rate of species classified as weak competitors. Discussion. High survival rates of strong competitors relate to a higher chance of establishment as compared to weak competitors. However, the negative effect of high initial numbers for strong competitive non-natives indicates a self-thinning effect, probably through creation of a highly competitive milieu. For weak competitors, our model predicted increasing survival rates at high initial densities. Positive effects of high propagule pressure have been proposed in field studies and are underlined with this model. However, our model largely overestimated mortality as compared to the preceding experiment. This could be improved by implementing more sophisticated competition modes and traits reflecting tolerance and avoidance of competition by non-native plants. This would, however, be very costly in terms of parameterization. Herbivory had a very low negative effect on survival in general and an advantage of high defence was almost untraceable. However, the positive effect of herbivory on survival of weak competitors indicated that herbivory should not be neglected in estimation of establishment success of species. Although the immediate and expected effect of herbivory might be small, side effects as weakening of resident competitors might play an important role for establishment in a new community.

scholarly journals The role of biotic factors during plant establishment in novel communities assessed with an agent-based simulation model

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5342 ◽  
Author(s):  
Janina Radny ◽  
Katrin M. Meyer
Keyword(s):  
Survival Rate ◽  
Simulation Model ◽  
Native Species ◽  
Native Plants ◽  
Survival Rates ◽  
Species Traits ◽  
Native Community ◽  
Competition Intensity ◽  
Positive Effects ◽  
Successful Establishment

Background Establishment success of non-native species is not only influenced by environmental conditions, but also by interactions with local competitors and enemies. The magnitude of these biotic interactions is mediated by species traits that reflect competitive strength or defence mechanisms. Our aim was to investigate the importance of species traits for successful establishment of non-native species in a native community exhibiting biotic resistance in the form of competition and herbivory. Methods We developed a trait-based, individual-based simulation model tracking the survival of non-native plants in a native community. In the model, non-native plants are characterized by high or low values of competition and defence traits. Model scenarios included variation of initial number of non-natives, intensity of competitive interaction, density of herbivores and density as well as mixture of the native community. Results Traits related to competition had a much greater impact on survival of non-native species than traits related to defence. Survival rates of strong competitors never fell below 50% while survival of weak competitors averaged at about 10%. Weak competitors were also much more susceptible to competitive pressures such as community density, composition and competition intensity. Strong competitors responded negatively to changes in competition intensity, but hardly to composition or density of the native community. High initial numbers of non-native individuals decreased survival rate of strong competitors, but increased the survival rate of weak competitors. Survival under herbivore attack was only slightly higher for plants with high defensive ability than for those with low defensive ability. Surprisingly, though, herbivory increased survival of species classified as weak competitors. Discussion High survival rates of strong non-native competitors relate to a higher probability of successful establishment than for weak competitors. However, the reduced survival of strong competitors at high initial numbers indicates a self-thinning effect, probably mediated by a strongly competitive milieu. For weak competitors, our model emphasizes positive effects of high propagule pressure known from field studies. General effects of herbivory or defence abilities on survival were not supported by our model. However, the positive effect of herbivory on survival of weak competitors indicated side effects of herbivory, such as weakening resident competitors. This might play an important role for establishment of non-natives in a new community.

scholarly journals Survival Rate of 1008 Short Dental Implants with 21 Months of Average Follow-Up: A Retrospective Study

2020 ◽  
Vol 9 (12) ◽  
pp. 3943
Author(s):  
João Caramês ◽  
Ana Catarina Pinto ◽  
Gonçalo Caramês ◽  
Helena Francisco ◽  
Joana Fialho ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Survival Rate ◽  
Dental Implants ◽  
Cox Regression ◽  
Survival Rates ◽  
High Survival ◽  
Implant Survival ◽  
Posterior Maxilla ◽  
Clinical Records

This retrospective study evaluated the survival rate of short, sandblasted acid-etched surfaced implants with 6 and 8 mm lengths with at least 120 days of follow-up. Data concerning patient, implant and surgery characteristics were retrieved from clinical records. Sandblasted and acid-etched (SLA)-surfaced tissue-level 6 mm (TL6) or 8 mm (TL8) implants or bone-level tapered 8 mm (BLT8) implants were used. Absolute and relative frequency distributions were calculated for qualitative variables and mean values and standard deviations for quantitative variables. A Cox regression model was performed to verify whether type, length and/or width influence the implant survival. The cumulative implant survival rate was assessed by time-to-event analyses (Kaplan–Meier estimator). In all, 513 patients with a mean age of 58.00 ± 12.44 years received 1008 dental implants with a mean follow-up of 21.57 ± 10.77 months. Most implants (78.17%) presented a 4.1 mm diameter, and the most frequent indication was a partially edentulous arch (44.15%). The most frequent locations were the posterior mandible (53.97%) and the posterior maxilla (31.55%). No significant differences were found in survival rates between groups of type, length and width of implant with the cumulative rate being 97.7% ± 0.5%. Within the limitations of this study, the evaluated short implants are a predictable option with high survival rates during the follow-up without statistical differences between the appraised types, lengths and widths.

scholarly journals Prospective evaluation of multitarget treatment of pediatric patients with helical intensity-modulated radiotherapy

2020 ◽  
Vol 196 (12) ◽  
pp. 1103-1115
Author(s):  
Maria-Elena A. Salfelder ◽  
Kerstin A. Kessel ◽  
Uwe Thiel ◽  
Stefan Burdach ◽  
Severin Kampfer ◽  
...  
Keyword(s):  
Survival Rate ◽  
Side Effects ◽  
Survival Rates ◽  
Young Patients ◽  
Intensity Modulated Radiotherapy ◽  
High Survival ◽  
Single Target ◽  
Number Of Patients ◽  
Grade 3

Abstract Background and purpose Radiotherapy (RT) is persistently gaining significance in the treatment of pediatric tumors. However, individual features of a growing body and multifocal stages complicate this approach. Tomotherapy offers advantages in the treatment of anatomically complex tumors with low risks of side effects. Here we report on toxicity incidence and outcome of tomotherapy with a focus on multitarget RT (mtRT). Materials and methods From 2008 to 2017, 38 children diagnosed with sarcoma were treated with tomotherapy. The median age was 15 years (6–19 years). Toxicity was graded according to the Common Terminology Criteria for Adverse Events v.4.03 and classified into symptoms during RT, acutely (0–6 months) and late (>6 months) after RT, and long-term sideeffects (>24 months). Results The main histologies were Ewing sarcoma (n = 23 [61%]) and alveolar rhabdomyosarcoma (n = 5 [13%]). RT was performed with a median total dose of 54 Gy (40.5–66.0 Gy) and a single dose of 2 Gy (1.80–2.27 Gy). Twenty patients (53%) received mtRT. Median follow-up was 29.7 months (95% confidence interval 15.3–48.2 months) with a 5-year survival of 55.2% (±9.5%). The 5‑year survival rate of patients with mtRT (n = 20) was 37.1 ± 13.2%, while patients who received single-target RT (n = 18) had a 5-year survival rate of 75 ± 10.8%. Severe toxicities (grade 3 and 4) emerged in 14 patients (70%) with mtRT and 7 patients (39%) with single-target RT. Two non-hematological grade 4 toxicities occurred during RT: one mucositis and one radiodermatitis. After mtRT 5 patients had grade 3 toxicities acute and after single-target RT 4 patients. One patient had acute non-hematological grade 4 toxicities (gastritis, pericarditis, and pericardial effusion) after mtRT. Severe late effects of RT occurred in 2 patients after mtRT and in none of the single-target RT patients. No severe long-term side effects appeared. Conclusion Our results showed acceptable levels of acute and late toxicities, considering the highly advanced diseases and multimodal treatment. Hence, tomotherapy is a feasible treatment method for young patients with anatomically complex tumors or multiple targets. Especially mtRT is a promising and innovative treatment approach for pediatric sarcomas, delivering unexpectedly high survival rates for patients with multifocal Ewing sarcomas in this study, whereby the limited number of patients should invariably be considered in the interpretation.

scholarly journals Efficiency and efficacy of vitrification in 35 654 sibling oocytes from donation cycles

2020 ◽  
Vol 35 (10) ◽  
pp. 2262-2271
Author(s):  
D Cornet-Bartolomé ◽  
A Rodriguez ◽  
D García ◽  
M Barragán ◽  
R Vassena
Keyword(s):  
Survival Rate ◽  
Embryo Transfer ◽  
Live Birth ◽  
Survival Rates ◽  
High Survival ◽  
Reproductive Outcomes ◽  
Ongoing Pregnancy ◽  
Oocyte Vitrification ◽  
Sibling Oocytes ◽  
Donor Oocytes

Abstract STUDY QUESTION Is oocyte vitrification/warming as efficient and effective as using fresh oocytes in donation cycles? SUMMARY ANSWER IVF with vitrified donor oocytes is less efficient than using fresh oocytes, but its efficacy remains comparable to that of fresh cycles. WHAT IS KNOWN ALREADY Oocyte vitrification is used to preserve the reproductive potential of oocytes. A small number of randomized controlled trials carried out by experienced groups have shown that this technique provides fertilization, pregnancy, implantation and ongoing pregnancy rates comparable to those of fresh oocytes. However, large registry-based analyses have consistently reported lower live birth rates (LBRs) in cycles using vitrified oocytes. It is not clear whether this decrease may be due to the effect of vitrification per se on the oocytes or to the lower efficiency of the technique, as some of the oocytes do not survive after warming. STUDY DESIGN, SIZE, DURATION Retrospective cohort analysis of 1844 cycles of oocyte donation (37 520 oocytes), each donor in the study provided enough oocytes for at least one reception cycle with fresh oocytes (2561 cycles) and one reception cycle with vitrified oocytes (2471 cycles) from the same ovarian stimulation (sibling oocytes). Overall, 35 654 oocytes were considered in the analysis. All embryo transfers (n = 5032) were carried out between 2011 and 2017. PARTICIPANTS/MATERIALS, SETTING, METHODS Differences in reproductive outcomes after the first embryo transfer were evaluated using Pearson’s Chi-squared test and regression analysis adjusted for recipient’s age, BMI, sperm origin and state, day of embryo transfer, morphological score and number of transferred embryos. We performed two additional sub-analyses, to test whether the efficiency and/or effectiveness of vitrification/warming impacts reproductive results. One analysis included paired cycles where the same number of fresh and vitrified oocytes were available for ICSI (SAME sub-analysis), while the second analysis included those cycles with a 100% survival rate post-warming (SAME100 sub-analysis). MAIN RESULTS AND THE ROLE OF CHANCE Baseline and cycle characteristics of participants were comparable between groups. Overall, fertilization rates and embryo morphological scores were significantly lower (P < 0.001) when using vitrified oocytes; moreover, vitrified oocytes also resulted in lower reproductive outcomes than sibling fresh oocytes using both unadjusted and adjusted analyses: ongoing pregnancy (32.1% versus 37.5%; P < 0.001; OR 0.88, 95% CI 0.77, 1.00) and live birth (32.1% versus 31.9%; P = 0.92; OR 1.16, 95% CI 0.90, 1.49). However, when the efficiency of warming was taken into account, reproductive outcomes in recipients became comparable: ongoing pregnancy (33.5% versus 34.1%; P = 0.82; OR 1.11, 95% CI 0.87, 1.43) and LBR (32.1% versus 32%; P = 0.97; OR 1.15, 95% CI 0.89, 1.48). Moreover, after selecting only cycles that, in addition to having the same number of oocytes available for ICSI, also had 100% post-warming survival rate in the vitrified group, reproductive outcomes were also comparable between fresh and vitrified oocytes: ongoing pregnancy (34.8% versus 32.4%; P = 0.42; OR 1.32, 95% CI 0.98, 1.77) and live birth (32.9% versus 31.0%; P = 0.52; OR 1.27, 95% CI 0.95, 1.71), indicating that reproductive outcomes of these cycles are affected by the efficiency of the vitrification/warming technique performed rather than the oocyte damage due to the fast cooling process to which oocytes are subjected. LIMITATIONS, REASONS FOR CAUTION An open vitrification system was used for all cases, and oocyte vitrification/warming was performed by experienced embryologists with consistently high survival rates; caution must be exerted when extrapolating our results to data obtained using other open vitrification systems, closed vitrification systems or to IVF units with survival rates <90%. WIDER IMPLICATIONS OF THE FINDINGS This is the largest cohort study comparing reproductive outcomes of vitrified and fresh sibling donor oocytes to date. We found that, when the number of oocytes available after warming is equal to the number of fresh oocytes, reproductive results including live birth are comparable. Consequently, the efficiency of vitrification must be taken into account to achieve the same reproductive outcomes as with fresh oocytes. We recommend implementing strict indicators of vitrification/warming efficiency in clinics and refining vitrification/warming protocols to maximize survival. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by intramural funding of Clínica EUGIN and by the Secretary for Universities and Research of the Ministry of Economy and Knowledge of the Government of Catalonia (GENCAT 2015 DI 048). The authors declare no conflicts of interest. TRIAL REGISTRATION NUMBER N/A.

scholarly journals High in vitro survival rate of sheep in vitro produced blastocysts vitrified with a new method and device

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Sergio Ledda ◽  
Jen M. Kelly ◽  
Stefano Nieddu ◽  
Daniela Bebbere ◽  
Federica Ariu ◽  
...  
Keyword(s):  
Survival Rate ◽  
Survival Rates ◽  
Blastocyst Stage ◽  
Hatching Rate ◽  
High Survival ◽  
Apoptotic Cells ◽  
Embryo Survival ◽  
New Device ◽  
In Vitro Survival

Abstract Background To advance the use of embryo vitrification in veterinary practice, we developed a system in which embryo vitrification, warming and dilution can be performed within a straw. Ovine in vitro produced embryos (IVEP) were vitrified at either early (EBs: n = 74) or fully expanded blastocyst stage (FEBs: n = 195), using a new device named “E.Vit”, composed by a 0.25-mL straw with a 50-μm pore polycarbonate grid at one end. Embryos at each stage (EBs and FEBs) were vitrified by either Two-step (TS) or Multi-step (MS; 6 different concentrations of vitrification solutions) protocol. Non-vitrified embryos (n = 102) were maintained in in vitro culture as a control. Warming consisted of placing the straws directly into 1.5 mL tubes containing a TCM-199 solution with three decreasing concentrations of sucrose. Blastocyst re-expansion, embryo survival and hatching rate were evaluated at 2, 24 and 48 h post warming. The number of apoptotic cells was determined by TUNEL assay. Results Blastocyst re-expansion (2 h) after warming was higher (P < 0.05) in FEBs group, vitrified with the MS and TS methods (77.90% and 71.25%, respectively) compared with the EBs group (MS: 59.38% and TS: 48.50%, respectively). Survival rates of vitrified FEBs after 24 h IVC were higher (P < 0.001) in both methods (MS and TS) than vitrified EBs (MS: 56.25%; TS: 42.42%) and was higher (P < 0.05) in the MS method (94.19%) compared with those in TS (83.75%). After 48 h of culture the hatching rate for FEBs vitrified in MS system (91.86%) was similar to control (91.89%), but higher than FEB TS (77.5%) and EBs vitrified in MS (37.5%) and TS (33.33%). Number of apoptotic cells were higher in EBs, irrespective of the system used, compared to FEBs. The number of apoptotic cells in FEBs vitrified with MS was comparable to the control. Conclusions A high survival rate of IVP embryos can be achieved by the new “E.Vit” device with hatching rates in vitro comparable with control fresh embryos. This method has the potential for use in direct embryo transfer in field conditions.

scholarly journals In Vivo Activity and Pharmacokinetics of Ziracin (SCH27899), a New Long-Acting Everninomicin Antibiotic, in a Murine Model of Penicillin-Susceptible or Penicillin-Resistant Pneumococcal Pneumonia

2000 ◽  
Vol 44 (4) ◽  
pp. 1010-1018 ◽  
Author(s):  
Erjian Wang ◽  
Marie Simard ◽  
Yves Bergeron ◽  
Denis Beauchamp ◽  
Michel G. Bergeron
Keyword(s):  
Survival Rate ◽  
Half Life ◽  
Survival Rates ◽  
High Survival ◽  
Once Daily ◽  
Concentration Time ◽  
Pharmacokinetic Properties ◽  
Long Acting ◽  
Immunocompetent Mice

ABSTRACT The effectiveness of ziracin (SCH27899), a novel everninomicin, was at first investigated against lethal pneumonia caused by a penicillin-susceptible Streptococcus pneumoniae strain. A single intravenous injection of ziracin at a dose of 60 mg/kg of body weight given at 18 h postinfection protected 100% mice and led to the complete clearance of bacteria from their lungs. The activity of ziracin was observed to be the same as that of ceftriaxone: the 50% protective doses (PD50s) of ziracin and ceftriaxone were 24.8 and 24.6 mg/kg, respectively. Evaluation of this therapy with leukopenic mice showed that a single injection of ziracin protected 75% of these mice. A delay in therapy with ziracin, which was initiated at 48 h postinfection with 30 mg/kg given once daily for 3 days, resulted in an 83% survival rate of immunocompetent mice. The efficacy of ziracin was further compared to that of vancomycin against lethal pneumonia caused by a penicillin-resistant S. pneumoniae strain in leukopenic mice. The PD50s of ziracin and vancomycin were 40.5 and 44.2 mg/kg, respectively. Treatment with ziracin at 30 mg/kg once daily for 2 days (initiated 18 h postinfection) yielded an 83% survival rate and achieved complete eradication of the bacteria. The results were the same as those obtained with vancomycin administered at 15 mg/kg twice daily for 2 days. It is notable that the high survival rates for mice treated with ziracin were associated with effective eradication of the bacteria and rapid recovery of pulmonary tissues from pneumonia. The pharmacokinetic properties of ziracin, ceftriaxone, and vancomycin were estimated following intravenous administration of a single dose of 30 mg/kg to immunocompetent mice. The half-life of ziracin was observed to be longer than those of ceftriaxone and vancomycin (2.3 h versus 1.0 and 0.36 h in the bloodstream and 3 h versus 1.9 and 0.45 h in lung tissues). The areas under the concentration-time curves (AUCs) in lung tissue for ziracin versus those for ceftriaxone and vancomycin were 36 μg · h/g versus 20 and 9.5 μg · h/g. The prolonged half-life and high AUC for ziracin in tissue contributed to its excellent in vivo activities.

scholarly journals First estimates of survival and densities of invasive alien Eastern cottontail (Sylvilagus floridanus) in Italy: a capture-recapture approach

2019 ◽  
Author(s):  
Jacopo Cerri ◽  
Sandro Bertolino
Keyword(s):  
North America ◽  
Native Species ◽  
Survival Rates ◽  
Northern Italy ◽  
High Survival ◽  
Sylvilagus Floridanus ◽  
Open Population ◽  
Capture Recapture ◽  
Eastern Cottontail ◽  
Selection Of

The Eastern cottontail (Sylvilagus floridanus) has become invasive in Central and Northern Italy, where it affects prey-predator dynamics between native species. Although many different studies explored survival rates and the density of cottontails in North America, no information is available for its invasive range. Between December 2003 and October 2005, a capture-recapture scheme for Eastern cottontails was enforced on the Orba River, Italy. We fitted an open-population Cormack-Jolly-Seber model to estimate survival of adult individuals (n=258) and their density in the study area. Adult cottontails showed a constant survival (phi = 0.84 ± 0.02) across the various sessions, as well as between individuals of different sexes. Capture probabilities and densities varied seasonally, with densities ranging between 2.06 ± 1.24 and 8.00 ± 4.60 cottontails/hectare, with an average of 4.72 individuals/hectare.Eastern cottontails are characterized by high survival and high densities, in their invaded range in Italy. Although densities are comparable to those reported in North America, our analysis focused on adult cottontails only and overall densities are certainly higher. Moreover, our estimates, obtained through a capture-recapture approach, were higher than those reported in previous studies from Italy that adopted nocturnal spotlight censuses. Spotlight transects are likely to underestimate cottontail densities, due to nocturnal habitat selection of cottontails, which might decrease their detectability.

scholarly journals COMORBIDITY AND SURVIVAL OF PATIENTS WITH CHRONIC KIDNEY DISEAS STAGE 5 D

2017 ◽  
pp. 30-39 ◽  
Author(s):  
I. M. Shifris ◽  
I.O. Dudar
Keyword(s):  
Chronic Kidney Disease ◽  
Survival Rate ◽  
Survival Rates ◽  
Medical Community ◽  
Comorbid Conditions ◽  
Single Patient ◽  
Significant Relation ◽  
Incidence Data ◽  
Study Results ◽  
Negative Effect

Annual expansion of dialysis population, high mortality, considerable expenses on specialized medical care are evoked the medical community to research comorbidities, that undoubtedly has an influence on course of chronic kidney disease VD stage (CKD VD st.) and prognosis. Aim. The aim of this study was to investigate the prevalence and structure of comorbid conditions in patients with CKDVD stage, and determinate the relation between comorbidities and survival rate in dialysis population. Materials and methods. It was studied the prevalence and structure of comorbidities among 204 patients with CKD VD st. (125 on hemodialysis [HD], 51 on peritoneal dialysis [PD], and 28 on hemodiafiltration [HDF]). All recorded concomitant diseases with its incidence data and coand polymorbidity indices were analyzed in consideration of renal replacement therapy (RRT). The survival rates were assessed in according with indices of comorbidity by Kaplan - Mayer methodology. Results. The performed analysis was demonstrated that in almost single patient had no mononosologicalpathology. The numbers of concomitant diseases were 3,55, 3,3 и 3,4 3,3per patient on HD, HDF and PD, respectively, without significant relation with RRT modality. In according with the study results the most common comorbid conditions, irrespective from RRT modality, were anaemia (88%), arterial hypertension (86%), and secondary hyperparathyroidism (40%). The proposed modified index of polymorbidities was revealed as the universal marker of survival rate in patients with CKD VD st. Conclusion. Thus the considerable prevalence of comorbid conditions in population ofpatients with CKD VD st. irrespective of RRT modality has significant negative effect on prognosis.

A MODEL FOR PREDICTING POPULATION DISTRIBUTION AMONG DEVELOPED AND DEVELOPING COUNTRIES

2014 ◽  
Vol 8 (1) ◽  
pp. 1-26
Author(s):  
Nissim Ben-David ◽  
Evyatar Ben David ◽  
Zvi Winer
Keyword(s):  
Developing Countries ◽  
Survival Rate ◽  
World Bank ◽  
Population Distribution ◽  
Survival Rates ◽  
Fertility Rate ◽  
Rate Of Change ◽  
High Survival ◽  
Age Group ◽  
High Survival Rate

We present a theoretical model that enables to predict population distribution according to fertility and survival rates for each age group. Using World Bank data, we estimated the relation between fertility rate of change and survival probabilities. Our findings show that fertility rate of change is reduced in countries with low or medium survival rate of infants. Conversely, it increased for those with a high survival rate of infants. If the survival rate of infants converges to 1, the fertility rate of change converges to zero, moving the country to steady size of population at age 1.  

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