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This chapter addresses key questions about the basis of cancer susceptibility in African people, as well as the uniqueness of the population genetics and genotype–phenotype relationship that resulted during social transition. Social transition encompasses the change of lifestyle from a rural subsistence one into an urban market-oriented, technology dependent, and predominantly sedentary mode of life, as well as changes that occur in the population genetics as a result of changes from ethnically defined structured populations into panmictic populations of an urban nature, as currently seen in megacities. Although humans passed through several periods of transition in history, the current one is the most profound.
Soil alkalinity imposes important limitations to lupin productivity; however, little attention has been paid to investigate the effects of soil alkalinity on plant growth and development. Many lupins are sensitive to alkaline soils, but Lupinus albus material from Egypt was found to have tolerance to limed soils. The aim of this study was to compare the growth response of two cultivars of L.albus L. – an Egyptian cultivar, P27734, and an Australian cultivar, Kiev Mutant, to different soil pH levels and to understand the physiological mechanisms underlying agronomic alkalinity tolerance of P27734. Plants were grown under three pH levels (5.1, 6.7, and 7.8) in a temperature-controlled glasshouse. For both cultivars, the greatest dry mass production and carboxylate exudation from roots were observed at alkaline pH. The better performance of the Egyptian cultivar at high pH was entirely accounted for by its greater seed weight. From a physiological perspective, the Australian cultivar was as alkaline-tolerant as the Egyptian cultivar. These findings highlight the agronomic importance of seed weight for sowing, and both cultivars can be used in alkaline soils.
Residual right ventricular outflow obstruction during Tetralogy of Fallot repair necessitates peri-operative revision often requiring trans-annular patch with its negative sequels. Bidirectional Glenn shunt in this setting reduces trans-pulmonary gradient to avoid revision.
Bidirectional Glenn shunt was added during Tetralogy repair in patients with significant residual obstruction. A total of 53 patients between January, 2011 and June, 2018 were included. Final follow-up was conducted in July, 2018.
Mean age at operation was 5.63±3.1 years. Right to left ventricular pressure ratio reduced significantly (0.91±0.09 versus 0.68±0.05; p<0.001) after bidirectional Glenn, avoiding revision in all cases. Glenn pressures at ICU admission decreased significantly by the time of ICU discharge (16.7±3.02 versus 13.5±2.19; p<0.001). Pleural drainage ≥ 7 days was seen in 14 (26.4%) patients. No side effects related to bidirectional Glenn-like facial swelling or veno-venous collaterals were noted. Mortality was 3.7%. Discharge echocardiography showed a mean trans-pulmonary gradient of 32.11±5.62 mmHg that decreased significantly to 25.64±5 (p<0.001) at the time of follow-up. Pulmonary insufficiency was none to mild in 45 (88.2%) and moderate in 6 (11.8%). Mean follow-up was 36.12±25.15 months (range 0.5–90). There was no interim intervention or death. At follow-up, all the patients were in NYHA functional class 1 with no increase in severity of pulmonary insufficiency.
Supplementary bidirectional Glenn shunt significantly reduced residual right ventricular outflow obstruction during Tetralogy of Fallot repair avoiding revision with satisfactory early and mid-term results.
Introduction: The effectiveness of intravenous alteplase is highly time dependent, and very short door-to-needle times (DNT) of 30 minutes or less have been reported in single centre hospitals, but never in an entire population. QuICR (Quality Improvement and Clinical Research) Alberta Stroke Program aimed to reduce DNT to a median of 30 minutes across the Canadian province of Alberta. Methods: We used the Improvement Collaborative Methodology from early 2015 to September 2016 with participation from all 17 Stroke Centres in Alberta. This methodology included 4 face-to-face workshops, site visits, webinars, data collection, data feedback, intensive process mapping, and process improvements. We compared data in the pre-intervention period from 2009-2014 (collected during the Alberta Provincial Stroke Strategy) to data in the post-intervention period from March 2016-February 2017 (collected during the QuICR DTN Collaborative). Data from January 2015-February 2016 were excluded, as improvements were being implemented during this time. Results: There were a total of 2,322 treated cases in the pre- and post-intervention periods. The results show that the median DNT dropped from 68 minutes (n=1846) in the pre-intervention period to 36 minutes (n=476) in the post-intervention period (p<0.001). There were reductions in DNT across all hospital types: median DNT dropped from 63 to 32 minutes in Urban Tertiary Centres (p<0.001), from 73 to 32 minutes in Community with 24/7 neurology (p<0.001), from 85 to 62 minutes in Community with limited/no neurology (p<0.001), and from 74 to 52.5 minutes in rural centres (p<0.001). Conclusion: There were 21.5 to 41 minute reductions in median DNT across all hospital types including smaller rural and community hospitals. A targeted multi-site improvement collaborative can be an effective intervention to reduce DNT across an entire population.
To examine the potential links between activity spaces, the food retail environment and food shopping behaviours for the population of young, urban adults.
Participants took part in the Canada Food Study, which collected information on demographics, food behaviour, diet and health, as well as an additional smartphone study that included a seven-day period of logging GPS (global positioning system) location and food purchases. Using a time-weighted, continuous representation of participant activity spaces generated from GPS trajectory data, the locations of food purchases and a geocoded food retail data set, negative binomial regression models were used to explore what types of food retailers participants were exposed to and where food purchases were made.
Toronto, Montreal, Vancouver, Edmonton and Halifax, Canada.
Young adults aged 16–30 years (n 496). These participants were a subset of the larger Canada Food Study.
Demographics, household food shopper status and city of residence were significantly associated with different levels of exposure to various types of food retailers. Food shopping behaviours were also statistically significantly associated with demographics, the activity space-based food environment, self-reported health and city of residence.
The study confirms that food behaviours are related to activity space-based food environment measures, which provide a more comprehensive accounting of food retail exposure than home-based measures. In addition, exposure to food retail and food purchasing behaviours of an understudied population are described.
Simulation models are used widely in pharmacology, epidemiology and health economics (HEs). However, there have been no attempts to incorporate models from these disciplines into a single integrated model. Accordingly, we explored this linkage to evaluate the epidemiological and economic impact of oseltamivir dose optimisation in supporting pandemic influenza planning in the USA. An HE decision analytic model was linked to a pharmacokinetic/pharmacodynamics (PK/PD) – dynamic transmission model simulating the impact of pandemic influenza with low virulence and low transmissibility and, high virulence and high transmissibility. The cost-utility analysis was from the payer and societal perspectives, comparing oseltamivir 75 and 150 mg twice daily (BID) to no treatment over a 1-year time horizon. Model parameters were derived from published studies. Outcomes were measured as cost per quality-adjusted life year (QALY) gained. Sensitivity analyses were performed to examine the integrated model's robustness. Under both pandemic scenarios, compared to no treatment, the use of oseltamivir 75 or 150 mg BID led to a significant reduction of influenza episodes and influenza-related deaths, translating to substantial savings of QALYs. Overall drug costs were offset by the reduction of both direct and indirect costs, making these two interventions cost-saving from both perspectives. The results were sensitive to the proportion of inpatient presentation at the emergency visit and patients’ quality of life. Integrating PK/PD–EPI/HE models is achievable. Whilst further refinement of this novel linkage model to more closely mimic the reality is needed, the current study has generated useful insights to support influenza pandemic planning.
The aim of the present research was to assess factors associated with first-lactation milk yield in dairy heifers, including maternal and environmental factors, factors related to the development of the heifer and factors related to its offspring such as gender of the calf. In addition, the potential underlying mechanism, in particular metabolic adaptations, was further explored. Data on body growth, reproduction and milk yield of 74 Holstein Friesian heifers on three herds in Flanders (Belgium) were collected. At birth, body measurements of the heifers were recorded and blood samples were taken (in order) to determine basal glucose and insulin concentrations. Body measurements were assessed every 3 months until first calving, and gender and weight of their first calf were recorded. Information on fertility and milk yield of the heifer and its dam were collected from the herd databases. Daily temperature and photoperiod were recorded from the database of the Belgian Royal Meteorological Institute. Linear mixed models were run with herd as a random factor, to account for differences in herd management. Heifers grew 867±80.7 g/day during their first year of life and were inseminated at 14.8±1.34 months. First calving took place at 24.5±1.93 months, at a weight of 642±61.5 kg and heifers produced 8506±1064 kg energy corrected milk during their first 305-day lactation. Regression models revealed that none of the maternal factors such as milk yield and parity, nor the growth of the heifer during the 1st year of life were associated with milk yield during first lactation. Age, and to a lesser extent BW at first parturition were positively associated with first-lactation milk yield. In addition, the season of birth, but not calving, had a significant influence on milk yield, with winter-born heifers producing less than heifers born in any other season. The lower yielding winter-born heifers had higher insulin concentrations at birth, whereas glucose concentrations were similar, the latter being suggestive for lower insulin sensitivity of the peripheral tissues. Furthermore, environmental temperature at the end of gestation was negatively correlated with neonatal insulin concentrations. In conclusion, results of the present study suggest heifers born during the hotter months are born with a higher peripheral insulin sensitivity, finally leading to a higher first-lactation milk yield.
Background: Stroke is often preceded by transient symptoms. Although global stroke rates have been shown to be declining, previous studies have reported inconsistent temporal trends of transient ischemic attacks (TIA). The objective of the current study is to report the temporal trends of TIA admissions and outcomes in Canada over the last 11 years. Methods: We conducted a complete population cohort study using a national administrative database to study the temporal trend of age- and sex-adjusted TIA admission rates in Canada from 2003 to 2013. We also determined the rates of TIA and stroke diagnoses in the emergency department in the province of Ontario during the same period. We used multivariable analyses to study discharge location after acute hospitalization as well as 90-day stroke and/or TIA readmission rates. Results: Of 425,799 admissions to an acute care hospital for all stroke and TIA, 71,443 (16.8%) were TIA. The age- and sex-standardized rates of TIA admission decreased significantly during the study period from 30.0 to 20.6 per 100,000 (p<0.0001). In Ontario, decreasing TIA admissions is mirrored by decreasing rates of TIA directly discharged from the emergency department (55.1 to 46.8 per 100,000, p = 0.002). The odds of 90-day readmission rates for stroke or TIA are also decreasing (adjusted odds ratio, 0.97; 95% confidence interval, 0.96-0.99). Conclusions: We show that TIA admission rates have declined in the past 11 years in Canada, reflecting improved vascular risk reduction and stroke care. Future studies to confirm our findings on improved stroke or TIA recurrence rates are necessary.
Background: Interhospital transfer is an important but resource-intensive pattern of care. The use for stroke patients is highly dependent upon health system structure. We examined the impact of hospital transfers for stroke care in Canada. Methods: We analyzed hospital administrative data within the Canadian Institute for Health Information (CIHI) Database for the 3 fiscal years 2011/12, 2012/13 and 2013/14. Patients with clinical stroke syndrome (ischemic or hemorrhagic) were identified using International Classification of Diseases. Stroke centers were defined by Heart & Stroke Foundation of Canada stroke report. Results: During the 3-year period,397 patients in Canada (excluding Quebec) were admitted to hospital for clinical stroke syndrome. Median age was 75 (interquartile range [IQR] 64–84) years; 50.6 % were male. Less than 5% (n=4030) of patients were transferred. Patients transferred to stroke centers were younger (p<0.001) and had shorter median length of stay (p<0.001). The highest probability of discharge home was associated with sole care at stroke center (43.8%). Transfer to stroke center from community hospital had the highest probability for discharge to rehabilitation facility (25%) and lowest to either long-term (2.1%) or complex community care (2.0%). Transferred patients had lower mortality at discharge. Conclusion: Younger patients were transferred more frequently to stroke centers; older patients were more likely treated in community hospitals. Sole stroke center care was associated with high discharge rate to home; transfer to a stroke center was associated with high discharge rate to rehabilitation and lower mortality rates.
Prenatal development is known to be extremely sensitive to maternal and environmental challenges. In this study, we hypothesize that body growth and lactation during gestation in cattle reduce nutrient availability for the pregnant uterus, with consequences for placental development. Fetal membranes of 16 growing heifers and 27 fully grown cows of the Belgian Blue (BB) breed were compared to determine the effect of body growth on placental development. Furthermore, the fetal membranes of 49 lactating Holstein Friesian (HF) cows and 27 HF heifers were compared to study the impact of dam lactation compared to dam body growth. After parturition, calf birth weight and body measurements of dam and calf were recorded, as well as weight of total fetal membranes, cotyledons and intercotyledonary membranes. All cotyledons were individually measured to calculate both the surface of each individual cotyledon and the total cotyledonary surface per placenta. Total cotyledonary surface was unaffected by breed or the breed×parity interaction. Besides a 0.3 kg lower cotyledonary weight (P=0.007), heifer placentas had a smaller total cotyledonary surface compared with placentas of cows (0.48±0.017 v. 0.54±0.014 m2, respectively, P<0.001). Within the BB breed, fetal membranes of heifers had a 1.5 kg lower total weight and 1.0 kg lower intercotyledonary membrane weight (P<0.005) compared with cows. A cotyledon number of only 91±5.4 was found in multiparous BB dams, while growing BB heifers had a higher cotyledon number (126±6.7, P<0.001), but a greater proportion of smaller cotyledons (<40 cm2). Within the HF breed, no parity effect on intercotyledonary membrane weight, cotyledon number and individual cotyledonary surface was found. Placental efficiency (calf weight/total cotyledonary surface) was similar in HF and BB heifers but significantly higher in multiparous BB compared with multiparous HF dams (106.0±20.45 v. 74.3±12.27 kg/m2, respectively, P<0.001). Furthermore, a seasonal effect on placental development was found, with winter and spring placentas having smaller cotyledons than summer and fall placentas (P<0.001). Main findings of the present study are that lactation and maternal growth during gestation entail a comparable nutrient diverting constraint, which might alter placental development. However, results suggest that the placenta is able to manage this situation through two potential compensation mechanisms. In early pregnancy the placenta might cope by establishing a higher number of cotyledons, while in late gestation a compensatory expansion of the cotyledonary surface is suggested to meet the nutrient demand of the fetus.
Tomato product consumption and estimated lycopene intake are hypothesised to reduce the risk of prostate cancer. To define the impact of typical servings of commercially available tomato products on resultant plasma and prostate lycopene concentrations, men scheduled to undergo prostatectomy (n 33) were randomised either to a lycopene-restricted control group ( < 5 mg lycopene/d) or to a tomato soup (2–2¾ cups prepared/d), tomato sauce (142–198 g/d or 5–7 ounces/d) or vegetable juice (325–488 ml/d or 11–16·5 fluid ounces/d) intervention providing 25–35 mg lycopene/d. Plasma and prostate carotenoid concentrations were measured by HPLC. Tomato soup, sauce and juice consumption significantly increased plasma lycopene concentration from 0·68 (sem 0·1) to 1·13 (sem 0·09) μmol/l (66 %), 0·48 (sem 0·09) to 0·82 (sem 0·12) μmol/l (71 %) and 0·49 (sem 0·12) to 0·78 (sem 0·1) μmol/l (59 %), respectively, while the controls consuming the lycopene-restricted diet showed a decline in plasma lycopene concentration from 0·55 (sem 0·60) to 0·42 (sem 0·07) μmol/l ( − 24 %). The end-of-study prostate lycopene concentration was 0·16 (sem 0·02) nmol/g in the controls, but was 3·5-, 3·6- and 2·2-fold higher in tomato soup (P= 0·001), sauce (P= 0·001) and juice (P= 0·165) consumers, respectively. Prostate lycopene concentration was moderately correlated with post-intervention plasma lycopene concentrations (r 0·60, P =0·001), indicating that additional factors have an impact on tissue concentrations. While the primary geometric lycopene isomer in tomato products was all-trans (80–90 %), plasma and prostate isomers were 47 and 80 % cis, respectively, demonstrating a shift towards cis accumulation. Consumption of typical servings of processed tomato products results in differing plasma and prostate lycopene concentrations. Factors including meal composition and genetics deserve further evaluation to determine their impacts on lycopene absorption and biodistribution.
The objective of the present retrospective cohort study was to evaluate potential associations between environmental factors and dam characteristics, including level of milk production during gestation, and insulin traits in newborn Holstein calves. Birth weight and gestational age of the calves at delivery were determined. On the next day, heart girth, wither height and diagonal length of both the calves and their dams were measured. Parity, body condition score and age at calving were recorded for all dams. For the cows, days open before last gestation, lactation length (LL), length of dry period (DP) and calving interval were also calculated. The magnitude and shape of the lactation curve both quantified using the MilkBot model based on monthly milk weights, were used to calculate the amount of milk produced during gestation. Using the same procedure, cumulative milk production from conception to drying off (MGEST) was calculated. A blood sample was collected from all calves (n=481; 169 born to heifers and 312 born to cows) at least 5 h after a milk meal on day 3 of life to measure basal glucose and insulin levels. In addition, an intravenous glucose-stimulated insulin secretion test was performed in a subset of the calves (n=316). After descriptive analysis, generalized linear mixed models were used to identify factors that were significantly associated with the major insulin traits (Insb, basal insulin level; QUICKI, quantitative insulin sensitivity check index; AIR, acute insulin response; DI, disposition index) of the newborn calves. The overall average birth weight of the calves was 42.7±5.92 kg. The insulin traits were significantly associated with gender and season of birth when data of all calves were analyzed. In addition, the insulin traits in calves born to cows were significantly associated with MGEST, DP and LL. The Insb was estimated to be higher in calves born to the cows having passed a higher MGEST (P=0.076) and longer DP (P=0.034). The QUICKI was estimated to be lower in calves born to the cows having passed a higher MGEST (P=0.030) and longer DP (P=0.058). Moreover, the AIR (P=0.009) and DI (P=0.049) were estimated to be lower in male compared with female calves. Furthermore, the AIR (P=0.036) and DI (P=0.039) were estimated to be lower in calves born to cows having passed a longer LL. The decisive effects of MGEST, DP and LL in cows on the insulin traits of their calves may provide a basis for developing managerial interventions to improve metabolic health of the offspring.
We analyzed a 10-year stroke administrative dataset to examine trends in admissions, mortality, and discharge destination in Canada.
We conducted an analysis of hospital administrative data from April 1st 2003 to March 31st 2013 from the Canadian Institute of Health Information’s Discharge Abstract Database. Ten-year trends for population-based age- and sex-standardized admission rates were calculated. We reviewed 10-year trends in absolute stroke admissions for differences between provinces and age groups. Stroke 30-day in-hospital mortality rates were calculated and adjusted for sex, age, stroke type and comorbidities. We documented changes in discharge location for ischemic and hemorrhagic stroke patients discharged from acute care.
The rate of hospital admissions has declined from 140.2 to 117.5 (per 100,000 people). The number of absolute stroke admissions within provinces increased in Alberta and British Columbia (21.7% and 16.2% respectively). The proportion of stroke patients aged 40-69 years old increased by 4.8% (p<0.0001) over the 10 years, whereas the proportion aged over 70 decreased by 4.9% (p<0.0001). Risk-adjusted 30-day in-hospital mortality decreased from: 18.5% to 14.9% for all strokes; 15.2% to 12.1% for ischemic strokes; 35.6% to 29.7% for intracerebral hemorrhage; and 25.1% to 18.0% for subarachnoid hemorrhage. The absolute increase in patients requiring inpatient and outpatient support increased by 4% (p<0.0001).
The rate of admissions for stroke is decreasing but there is an increase in stroke admissions for younger patients. In-hospital mortality is decreasing; fewer patients are going directly home without services and more are requiring support services.
Ultrathin colloidal PbS nanosheets are synthesized using organometallic precursors with chloroalkane cosolvents, resulting in tunable thicknesses ranging from 1.2 nm to 4.6 nm. We report the first thickness-dependent photoluminescence spectra from lead-salt nanosheets. The one-dimensional confinement energy of these quasi-two-dimensional nanosheets is found to be proportional to 1/L instead of 1/L2 (L is the thickness of the nanosheet), which is consistent with results calculated using density functional theory as well as tight-binding theory.
This study examines the trends and determinants of child marriage among women aged 20–49 in Bangladesh. Data were extracted from the last six nationally representative Demographic and Health Surveys conducted during 1993–2011. Simple cross-tabulation and multivariate binary logistic regression analyses were adopted. According to the survey conducted in 2011, more than 75% of marriages can be categorized as child marriages. This is a decline of 10 percentage points in the prevalence of child marriage compared with the survey conducted in 1993–1994. Despite some improvements in education and other socioeconomic indicators, Bangladeshi society still faces the relentless practice of early marriage. The mean age at first marriage has increased by only 1.4 years over the last one and half decades, from 14.3 years in 1993–1994 to 15.7 years in 2011. Although the situation on risk of child marriage has improved over time, the pace is sluggish. Both the year-of-birth and year-of-marriage cohorts of women suggest that the likelihood of marrying as a child has decreased significantly in recent years. The risk of child marriage was significantly higher when husbands had no formal education or little education, and when the wives were unemployed or unskilled workers. Muslim women living in rural areas have a greater risk of child marriage. Women's education level was the single most significant negative determinant of child marriage. Thus, the variables identified as important determinants of child marriage are: education of women and their husbands, and women's occupation, place of residence and religion. Programmes to help and motivate girls to stay in school will not only reduce early marriage but will also support overall societal development. The rigid enforcement of the legal minimum age at first marriage could be critical in decreasing child marriage.
In the absence of established methicillin-resistant Staphylococcus aureus (MRSA) screening programs, many centers use a history of a positive culture or a nasal screen as a surrogate for preoperative MRSA colonization status. We aimed to evaluate the test characteristics of these surrogates.
Retrospective cohort study.
Veterans Affairs Boston Healthcare System surgical patients with a preoperative nasal MRSA polymerase chain reaction (PCR) screen.
We assessed the performance of a history of a MRSA-positive culture or a positive nasal MRSA PCR screen during the year prior to surgery for predicting the preoperative nasal PCR screen result. The associations between MRSA history and postoperative outcomes, including MRSA cultures and infections, were also evaluated.
Among 4,238 patients, a positive MRSA culture history had a sensitivity of 19.7% (95% confidence interval [CI], 15.4%–24.8%) and positive predictive value of 57.3% for the preoperative nasal MRSA status. The specificity of MRSA culture history was 99% (95% CI, 98.5%–99.2%). Prior-year nasal MRSA screen results had similar test characteristics. A history of a MRSA-positive culture was associated with an increased risk of postoperative MRSA-positive cultures (risk ratio [RR], 3.54 [95% CI, 1.70–7.37], P< .001) but not of infections (RR, 1.71 [95% CI, 0.58–5.01]), after adjustment for preoperative nasal MRSA status, vancomycin surgical prophylaxis, surgical scrub, and age.
A history of a MRSA-positive culture and a positive nasal PCR screen are poor surrogate markers of preoperative colonization status, missing at least 70% of MRSA-colonized patients. Prior-year history is also not independently associated with MRSA-related postoperative infections. Strong consideration should be given to preoperative MRSA screening in patients at high risk for surgical complications.
The objective of this study was to detect structural and functional changes in the left and right ventricles in obese Egyptian adolescents.
Methods and results
Anthropometric and echocardiographic parameters, including tissue Doppler imaging, were obtained from 70 obese adolescents with average body mass index of 34 plus or minus 3.8 and compared with 50 age- and sex-matched controls, with a body mass index of 21.6 plus or minus 1.9. Cardiac dimensions, stroke volume, left ventricular and right ventricular systolic and diastolic functions were evaluated. The obese group had a higher end-diastolic septal and posterior wall thickness and left ventricular mass index than the non-obese group. Body mass index, mid-arm and hip circumference values showed significant correlations with these echocardiographic variables. Systolic and diastolic functions of the left ventricle were normal in both groups, although stroke volume was high in the obese group. The right ventricle tissue Doppler parameters were similar in both groups. However, the S wave of the septal/lateral tricuspid valve annulus was reduced in the obese group, but not to the level reflecting systolic dysfunction. This was inversely correlated with hip, waist, and mid-arm circumference. Stepwise multiple regression analysis showed that the mid-arm and hip circumference followed by the body mass index are significant predictors of these early cardiac abnormalities.
Left ventricular hypertrophy is present in obese children, although both systolic and diastolic functions are normal. Tissue Doppler imaging revealed a minor, but still significant, reduction in the right ventricular systolic function. Mid-arm and hip circumference are predictors of left ventricular hypertrophy.
The world is currently experiencing loss of biodiversity due to direct and indirect anthropogenic causes unparalleled in human history. In this chapter, we expound on the importance of evolutionary thinking in our efforts to mitigate this loss. In Otto Frankel's (1974) words, ‘reinforcing the grounds for nature conservation with an evolutionary perspective may help to give conservation a permanence which a utilitarian, and even an ecological grounding, fails to provide in men's minds'. A simple argument-from-definition could be presented to justify this presumption: evolution is defined as change in the frequencies of genes and gene variants over space and time; population genetics deals with the intraspecific component of this dynamic; conservation genetics is applied population genetics, hence the direct link between evolution and conservation genetics. We aim to put forth a more synthetic justification based on the analysis of empirical studies that link evolutionary processes with conservation objectives.
A number of recent reviews (Avise, 2010; Frankham, 2010) and books (Allendorf and Luikart, 2007; Avise, 2008) have documented historical developments in conservation biology that led to the emergence of the relatively young subdiscipline of conservation genetics. Awareness of the importance of conserving heritable variation dates back to Charles Darwin's days (Darwin, 1876). The 1960s and 1970s heralded molecular techniques that enabled quantifying heritable variation in natural populations (Hillis et al., 1996). In 1970 and 1974, building on these technological developments, but more significantly concerned over the vanishing genetic diversity of crop plants as a result of monoculture and the introduction of input-needy high-yielding crops in areas of genetic diversity, Otto Frankel published seminal papers on the urgent need to conserve genetic diversity. This led to changes in awareness not only among the scientific community, but also among the general public, particularly among conservation oriented non-governmental organisations (NGOs) and other civic groups (Mooney, 1996). A meeting of ecologists and evolutionary geneticists was held in 1978 aimed at integrating their respective approaches to mitigating the problem of extinction (Allendorf and Luikart, 2007) and acknowledging that conserving genetic diversity plays a significant role in this. The subsequent publication of Frankel and Soulé's book Conservation and Evolution in 1981 and the launch of the journal Conservation Genetics in 2000 represent significant milestones. The first dedicated conservation genetics textbook by Frankham was published in 2002 (Frankham et al., 2002).
To determine whether preoperative nasal methicillin-resistant Staphylococcus aureus (MRSA) carriage is a significant predictor of postoperative infections, after accounting for surgical infection risk and surgical prophylaxis.
Retrospective cohort study.
Veterans Affairs (VA) Boston patients who had nasal MRSA polymerase chain reaction screening performed in the 31 days before clean or clean contaminated surgery in 2008–2009.
Postoperative MRSA clinical cultures and infections, total surgical site infections (SSIs), and surgical prophylaxis data were abstracted from administrative databases. MRSA infections were confirmed via chart review. Multivariate analysis of risk factors for each outcome was conducted using Poisson regression. SSI risk index was calculated for a subset of 1,551 patients assessed by the VA National Surgical Quality Improvement Program.
Among 4,238 eligible patients, 279 (6.6%) were positive for preoperative nasal MRSA. Postoperative MRSA clinical cultures and infections, including MRSA SSIs, were each significantly increased in patients with preoperative nasal MRSA. After adjustment for surgery type, vancomycin prophylaxis, chlorhexidine/alcohol surgical skin preparation, and SSI risk index, preoperative nasal MRSA remained significantly associated with postoperative MRSA cultures (relative risk [RR], 8.81; 95% confidence interval [CI], 3.01–25.82) and infections (RR, 8.46; 95% CI, 1.70–42.04). Vancomycin prophylaxis was associated with an increased risk of total SSI in those negative for nasal MRSA (RR, 4.34; 95% CI, 2.19–8.57) but not in patients positive for nasal MRSA.
In our population, preoperative nasal MRSA colonization was independently associated with MRSA clinical cultures and infections in the postoperative period. Vancomycin prophylaxis increased the risk of total SSI in nasal MRSA-negative patients.