Reduction in re-rupture rates following implementation of return-to-sport testing after anterior cruciate ligament reconstruction in 313 patients with a mean follow-up of 50 months.

OBJECTIVES: The objective of this study was to assess the mid-term effectiveness of a return to sport (RTS) test in relation to preventing anterior cruciate ligament (ACL) re-rupture and contralateral ACL injury following ACL reconstruction (ACLR). Furthermore, this study aimed to assess the timing of passing a, RTS-test after surgery, and the effect age has on RTS outcomes. METHODS: Patients undergoing ACLR between August 2014 and December 2018 took an RTS-test following rehabilitation. The RTS-test consisted of the Anterior Cruciate Ligament Return to Sport After Injury Scale, a single-leg hop, a single-leg triple hop, a single-leg triple cross-over hop, a box-drop vertical jump down, a single-leg 4-rep max-incline leg press, and a modified agility T test. RTS-passing criteria were ≥90% limb symmetry index in addition to defined takeoff and landing parameters. Mid-term review assessed sporting level, ACL re-injury, and contralateral ACL injury. RESULTS: A total of 352 patients underwent RTS-testing, following ACLR with 313 (89%) contactable at follow-up, a mean of 50 months (standard deviation: 11.41, range: 28-76) after surgery. The re-rupture rate was 6.6% after passing the RTS-test and 10.3% following failure (p â€‹= â€‹0.24), representing a 36% reduction. Contralateral ACL injury rate after surgery was 6% and was 19% lower in those passing the RTS test. The mean age of patients passing their first RTS-test was significantly higher than that of those who failed (p â€‹= â€‹0.0027). Re-ruptures in those who passed the RTS test first time occurred late (>34 months), compared to those who failed first time, which all occurred early (<33 months) (p â€‹= â€‹0.0015). The mean age of re-rupture was significantly less than those who did not sustain a re-rupture (p â€‹= â€‹0.025). CONCLUSION: Passing a RTS-test following ACLR reduces ACL re-rupture by 36.21% and contralateral ACL injury by 19.15% at mid-term follow-up. Younger patients are more likely to fail a RTS-test and are at higher risk of contralateral ACL rupture.

The prevalence of internuclear ophthalmoparesis in a population-based cohort of individuals with multiple sclerosis.

BACKGROUND: Internuclear ophthalmoparesis (INO) occurs in 15-52% of individuals with multiple sclerosis (MS) and is reliably detected by infrared oculography. Methods for diagnosing INO with infrared oculography and the association between INO and MS characteristics need confirmation. We aimed to describe INO prevalence and the clinical characteristics of individuals with MS and INO in a population-based cohort of individuals with MS born in the year 1966 (Project Y). METHODS: Previously described thresholds for the versional dysconjugacy index (VDI), assessed with standardized infrared oculography, were used to detect INO in participants of project Y. Clinical characteristics, visual functioning and complaints were compared between individuals with MS with INO and individuals with MS without INO. RESULTS: Two-hundred-twenty individuals with MS and 110 healthy controls were included. VDI values exceeding the threshold for INO presented in 53 (24%) individuals with MS and 19 controls (13%). INO was associated with male sex, greater disability, worse cognition and worse arm function in individuals with MS. There was no association with disease duration, visual functioning or complaints. CONCLUSIONS: INO is prevalent among individuals with MS aged fifty-three and related to clinical characteristics of MS. INO was more frequently detected in healthy controls than previous studies, implying that oculography based diagnosis of INO requires further refinement.

Follow-up ultrasound in second-trimester low-positioned anterior and posterior placentae: prospective cohort study.

OBJECTIVES: The majority of cases of placenta previa or a low-lying placenta in the second trimester will have a normal placental position in the third trimester. The aim of this study was to assess the accuracy of the distance between the placenta and the internal os of the cervix (IOD) in the second trimester for the prediction of third-trimester low-positioned placenta, and to define a cut-off value at which all cases of third-trimester low-positioned placenta are identified. METHODS: This was a prospective cohort study including women undergoing a transvaginal ultrasound examination between 18 and 24 weeks' gestation who had a low-positioned placenta, defined as an IOD of < 20 mm. Low-positioned placenta included placenta previa, defined as a placenta covering the internal os of the cervix, and a low-lying placenta, defined as a placenta lying near to (within 20 mm) but not overlying the internal os. All women were re-evaluated in the third trimester. Relative risks for a low-positioned placenta in the third trimester were calculated for women with placenta previa vs a low-lying placenta, posterior vs anterior placenta and positive vs negative history of Cesarean section. Multilevel likelihood ratios for ranges of IOD in the prediction of a low-positioned placenta in the third trimester were calculated separately for anteriorly and posteriorly located placentae. Corresponding receiver-operating-characteristics curves were constructed. RESULTS: In total, 958 women were included in the study. In the second trimester, placentae were more frequently located on the posterior side (62.0%) than on the anterior side (38.0%). In the third trimester, 48/958 (5.0%) placentae persisted as a low-positioned placenta. Women with placenta previa in the second trimester had a higher risk of a low-positioned placenta in the third trimester than did those with a low-lying placenta in the second trimester (37/181 (20.4%) vs 11/777 (1.4%); relative risk (RR), 17.9 (95% CI, 8.9-36.0)). Women with a posterior placenta had a higher risk of a low-positioned placenta in the third trimester than did those with an anterior placenta (38/594 (6.4%) vs 10/364 (2.7%); RR, 2.4 (95% CI, 1.2-4.9)), as did women with a history of Cesarean section compared with those without such a history (14/105 (13.3%) vs 34/853 (4.0%); RR, 3.7 (95% CI, 1.9-7.2)). The cut-off value of IOD in the second trimester to identify all cases of an abnormally located placenta in the third trimester was 15.5 mm for posteriorly located placentae, while for anteriorly located placentae the IOD cut-off was lower, namely -4.5 mm, representing a 4.5-mm overlap of the placental edge over the internal os of the cervix. CONCLUSIONS: With incorporation of a safety margin of 5 mm and ensuring that all women with placenta previa undergo a follow-up scan, we recommend lowering the IOD cut-off value for follow-up in cases of an anterior low-positioned placenta from 20 to 5 mm, which would decrease the number of unnecessary follow-up ultrasound examinations without missing any high-risk women. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

IL-10 signaling in dendritic cells controls IL-1ß-mediated IFNγ secretion by human CD4+ T cells: relevance to inflammatory bowel disease.

Uncontrolled interferon γ (IFNγ)-mediated T-cell responses to commensal microbiota are a driver of inflammatory bowel disease (IBD). Interleukin-10 (IL-10) is crucial for controlling these T-cell responses, but the precise mechanism of inhibition remains unclear. A better understanding of how IL-10 exerts its suppressive function may allow identification of individuals with suboptimal IL-10 function among the heterogeneous population of IBD patients. Using cells from patients with an IL10RA deficiency or STAT3 mutations, we demonstrate that IL-10 signaling in monocyte-derived dendritic cells (moDCs), but not T cells, is essential for controlling IFNγ-secreting CD4+ T cells. Deficiency in IL-10 signaling dramatically increased IL-1ß release by moDCs. IL-1ß boosted IFNγ secretion by CD4+ T cells either directly or indirectly by stimulating moDCs to secrete IL-12. As predicted a signature of IL-10 dysfunction was observed in a subgroup of pediatric IBD patients having higher IL-1ß expression in activated immune cells and macroscopically affected intestinal tissue. In agreement, reduced IL10RA expression was detected in peripheral blood mononuclear cells and a subgroup of pediatric IBD patients exhibited diminished IL-10 responsiveness. Our data unveil an important mechanism by which IL-10 controls IFNγ-secreting CD4+ T cells in humans and identifies IL-1ß as a potential classifier for a subgroup of IBD patients.

Removal of synthetic sex hormones by hydrothermal carbonization.

One of the most prominent fields of environmental chemistry is the study and the removal of micro-pollutants from aqueous matrices. Analytical techniques for their identification and quantification are becoming more sensitive and comprehensive and, as a result, an increasing number of drugs have been detected in environmental samples. However, the literature shows that conventional treatments for drinking water and wastewater are not sufficient for remove these compounds. This study aims to check whether the process of hydrothermal carbonization (CHT) is effective in removing the synthetic sex hormones: ethinyl estradiol, gestodene and cyproterone acetate from aqueous samples. The system used in CHT basically consists of a pressurized reactor made of stainless steel and solutions of compounds of interest, both individual and mixed, with a concentration of 1.0 µg.L-1 and a pH range of 2.0 to 3.0. The maximum surface temperature in the reactor was about 180 °C, the internal pressure was 20 bar with 90 minutes for the reaction. Four experiments were conducted, one for each hormone and one with the three hormones together. In individual tests removal of the compounds was found to be 99.8% for ethinyl estradiol, 99.3% for gestodene and 100% for cyproterone acetate. For a mixture of the hormones treated under the same conditions, the mean values of CHT-removal of Ethinylestradiol, Gestodene and Cyproterone Acetate were 99.60%, 96.80% and 68.90%, respectively. The impact of the matrix effect may have affected the efficiency of the hormone removal process by CHT.

Incidence of and risk indicators for vasa praevia: a systematic review.

BACKGROUND: Vasa praevia (VP) is a rare phenomenon that is assumed to increase the risk of severe complications, including fetal death. Critical data on its incidence are lacking, so there is no rational basis for prenatal screening. OBJECTIVES: To review the literature on the incidence and risk indicators for VP. SEARCH STRATEGY: We searched OVID MEDLINE, OVID EMBASE, the Cochrane Library and PubMed for case-control and cohort studies on incidence and risk indicators for VP. SELECTION CRITERIA: Two reviewers selected studies and scored their methodological quality. DATA COLLECTION AND ANALYSIS: We calculated the mean incidence of VP. We constructed 2 × 2 tables cross-classifying potential risk indicators against the incidence of VP to calculate common odds ratios and 95% confidence intervals, using the Mantel-Haenszel method. MAIN RESULTS: We included 13 studies (two prospective cohort studies, ten retrospective cohort studies and one case-control study) reporting on 569 410 patients with 325 cases of VP. Based on ten included cohort studies providing information on the incidence, the mean incidence of VP was 0.60 per 1000 pregnancies. We identified five different risk indicators and markers for VP: second-trimester placenta praevia, conception by assisted reproductive technologies, a bilobed or succenturiate placenta, umbilical cord insertion in the lower third part of the uterus at first-trimester ultrasound and velamentous cord insertion. Almost 83% of the cases of VP had one or more risk indicators. AUTHORS' CONCLUSIONS: In view of the low incidence, screening for VP in an unselected population is not advised. Targeted screening of women with one or more risk indicators as a part of routine mid-gestation scanning should be considered. TWEETABLE ABSTRACT: Vasa praevia is more common in placenta praevia, conception by ART, velamentous cord insertion and bilobed placenta.

Elective repeat cesarean delivery compared with trial of labor after a prior cesarean delivery: a propensity score analysis.

OBJECTIVE: To determine neonatal and short term maternal outcomes according to intentional mode of delivery following a cesarean delivery (CD). STUDY DESIGN: Women pregnant after CD between January 2000 and December 2007 were categorized according to whether they had an elective repeat CD (ERCD) or a Trial of Labor (TOL). Prognostically equal ERCD and TOL groups were created using the propensity score matching technique. Conditional logistic regression was performed to assess differences in neonatal and maternal outcomes. POPULATION: Women in their second ongoing pregnancy with a history of CD. RESULTS: After ERCD the rates of low 5min Apgar score (OR 0.3, 95%CI 0.2-0.5, p<0.001), meconium aspiration (OR 0.0, 95%CI 0-0.7, p=0.02) and birth trauma (OR 0.08, 95%CI 0.002-0.5, p<0.001) were lower compared to TOL. The rate of transient tachypnoea of the newborn (TTN) appears higher in the ERCD group (OR 1.7, 95%CI 1.0-2.8, p=0.04). Uterine rupture (OR 0.1, 95%CI 0.003-0.8, p=0.02) and hemorrhage (OR 0.6, 95%CI 0.5-0.8, p<0.001) occurred less in the ERCD group. CONCLUSION: Neonatal and short term maternal morbidity appears to be lower after ERCD than after TOL. Only TTN was seen more often after ERCD.

Systematic review of accuracy of ultrasound in the diagnosis of vasa previa.

OBJECTIVE: Vasa previa is an obstetric complication in which the fetal blood vessels lie outside the chorionic plate in close proximity to the internal cervical os. In women with vasa previa, the risk of rupture of these vessels is increased, thus potentially causing fetal death or serious morbidity. Our objective was to assess the accuracy of ultrasound in the prenatal diagnosis of vasa previa. METHODS: We searched MEDLINE, EMBASE, the Cochrane Library and PubMed for studies on vasa previa. Two reviewers independently selected studies on the accuracy of ultrasound in the diagnosis of vasa previa. The studies were scored on methodological quality using the Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2). Data on sensitivity and specificity were subsequently extracted. RESULTS: The literature search revealed 583 articles, of which two prospective and six retrospective cohort studies were eligible for inclusion in the qualitative analysis. All studies documented methods suitable for the prenatal diagnosis of vasa previa. Four out of the eight studies used transvaginal ultrasound (TVS) for primary evaluation, while the remaining four studies used transabdominal ultrasound and performed a subsequent TVS when vasa previa was suspected. The QUADAS-2 tool reflected poor methodology in six of the eight included studies, and prenatal detection rates varied from 53% (10/19) to 100% (total of 442,633 patients, including 138 cases of vasa previa). In the two prospective studies (n = 33,795, including 11 cases of vasa previa), transvaginal color Doppler performed during the second trimester detected all cases of vasa previa (sensitivity, 100%) with a specificity of 99.0-99.8%. CONCLUSION: The accuracy of ultrasound in the diagnosis of vasa previa is high when performed transvaginally in combination with color Doppler.

Risk of maternal and neonatal complications in subsequent pregnancy after planned caesarean section in a first birth, compared with emergency caesarean section: a nationwide comparative cohort study.

OBJECTIVE: To compare the difference in risks of neonatal and maternal complications, including uterine rupture, in a second birth following a planned caesarean section versus emergency caesarean section in the first birth. DESIGN: Prospective cohort study. SETTING: Population-based cohort in the Netherlands. POPULATION: Linked data set of outcomes for term caesarean section in a first birth followed by a consecutive delivery. METHODS: We conducted a prospective cohort analysis using data from the Dutch Perinatal Registry. We included primiparous women who gave birth to term singleton infants through planned or emergency caesarean from January 2000 through December 2007, and who had a second singleton delivery during the same period (n = 41,109). Odds ratios and adjusted odds ratios were calculated. MAIN OUTCOME MEASURES: Maternal and neonatal complications, specifically uterine rupture, in second births associated with planned and emergency caesareans in the first birth. RESULTS: Women with a history of a planned caesarean section in the first birth (n = 11,445) had a 0.24% risk for uterine rupture, compared with a 0.16% risk for women with a history of emergency caesarean section (n = 29,664; aOR 1.4, 95% CI 0.8-2.4). In multivariate logistic regression, women with planned caesareans in a first birth had a significantly increased risk of stillbirth (aOR 1.5, 95% CI 1.0-2.2) and postpartum haemorrhage (aOR 1.1, 95% CI 1.0-1.2) in second births, compared with women with emergency caesareans in the first birth. CONCLUSIONS: We found a moderately increased risk of postpartum haemorrhage and a small to moderately increased risk of uterine rupture and stillbirth as a long-term effect of prior planned caesarean delivery on second births.

Increased production of interleukin-21, but not interleukin-17A, in the small intestine characterizes pediatric celiac disease.

Celiac disease (CD) is caused by inflammatory CD4(+) T-cell responses to dietary gluten. It is unclear whether interleukin (IL)-21 and IL-17A contribute to CD onset and lesion severity; therefore, we investigated IL-21 and IL-17A expression in biopsies from pediatric CD patients with different histopathological scores. High numbers of IL-21-producing cells were observed in pediatric CD lesions, even Marsh 1-2 lesions, whereas increased numbers of IL-17 secreting cells were not observed. Intraepithelial lymphocytes, CD4(+) T cells and also neutrophils secreted IL-21. Flow cytometry of lamina propria cells revealed a large population of IL-21- and interferon-γ (IFN-γ)-secreting CD3(+) T cells that did not secrete IL-17A. Adult CD patient biopsies also contained high numbers of IL-21-positive cells; however, enhanced numbers of IL-17-positive cells were observed in a small subgroup of patients with severe lesions. As duodenal tissue damage increases contact with microbe-associated molecular patterns, we hypothesized that microbial sensing by Toll-like receptors (TLRs) modulates T cell-derived cytokine secretion. Costimulation with TLR3 ligands during polyclonal T-cell activation significantly increased IL-21 secretion, whereas TLR2 ligands selectively enhanced IL-17A. These results demonstrate that an IL-17A-independent increase in IL-21 production by CD4(+) T cells is characteristic of pediatric CD. We hypothesize that incidental IL-17 secretion is caused by tissue damage rather than gluten-specific responses.

Adalimumab (antitumour necrosis factor-α) treatment of hidradenitis suppurativa ameliorates skin inflammation: an in situ and ex vivo study.

BACKGROUND: Hidradenitis suppurativa (HS) is a difficult-to-manage disease. Randomized controlled trials with antitumour necrosis factor (TNF)-α biologics have been conducted and in most studies disease activity was reduced. However, the mechanism of action in HS skin is so far unknown. OBJECTIVES: To assess whether anti-TNF-α treatment affects in situ cytokine production and frequency of inflammatory cell populations in HS lesional skin. METHODS: Nine patients with HS, participating in a larger placebo-controlled, double-blind phase IIb clinical trial on the efficacy and safety of adalimumab in patients with moderate to severe HS (M10-467), were randomized and treated for 16weeks. In a mechanism-of-action substudy, biopsies were obtained at fixed time points pre- and post-treatment. One part of the biopsy was cultured for 24h for cytokine release in the culture medium, while another part was used for in situ analysis. RESULTS: Secretion of cytokines, including interleukin (IL)-1ß, CXCL9 [monokine induced by interferon-γ (MIG)], IL-10, IL-11, B-lymphocyte chemoattractant (BLC) and IL-17A, was significantly elevated in HS. Adalimumab treatment was associated with decreased production of cytokines in HS skin, especially IL-1ß, CXCL9 (MIG) and BLC. Treatment significantly reduced the number of CD11c+,CD14+ and CD68+ cells in HS lesional skin. The numbers of CD3+ and CD4+ T cells, and CD20+ and CD138+ B cells were also reduced by adalimumab treatment. CONCLUSIONS: Adalimumab treatment inhibits important cytokines and inflammatory cell numbers in lesional HS skin, especially levels of IL-1ß and numbers of inflammatory CD11c+ dendritic cells.

Alterations in leucocyte subsets and histomorphology in normal-appearing perilesional skin and early and chronic hidradenitis suppurativa lesions.

BACKGROUND: Current insight into the histopathological course of events during disease progression in hidradenitis suppurativa (HS) is fragmentary. OBJECTIVES: To identify histological alterations and leucocyte subsets in normal-appearing perilesional skin, and early and chronic HS lesions. METHODS: In this observational study we examined eight perilesional skin samples, and six early and 10 chronic prototypic HS lesions, as well as skin samples from four healthy donors using in situ immunostaining. RESULTS: Perilesional skin showed mild psoriasiform hyperplasia and follicular plugging as well as a low-grade influx of tryptase-positive mast cells, CD3+ T cells, CD138+ plasma cells and factor XIIIa+ dendritic cells. In early HS lesions, neutrophilic abscess formation and influx of mainly macrophages, monocytes and dendritic cells predominated. In chronic disease, the infiltrate expanded with markedly increased frequencies of CD20+ and CD79a+ B cells and CD138+ plasma cells. As in early lesions, free keratin fibres were detected in the dermis and within giant cells. Single detached keratinocytes and strands of follicular epithelium were observed in the dermis, the latter frequently expressing Ki67, indicative of active proliferation. CONCLUSIONS: Psoriasiform hyperplasia, follicular plugging and low-grade leucocytic infiltration are already present in normal-appearing perilesional skin. Keratin fibres in the dermis are associated with clinical disease. Early lesions are characterized by neutrophilic abscess formation and influx of mainly histiocytes, and chronic lesions mainly by expansion of B cells and plasma cells in 'pseudo' follicles. Proliferating strands of follicular epithelium may initiate fistula formation. Mast cells are increased in all stages of HS including perilesional skin.

Elevated levels of tumour necrosis factor (TNF)-α, interleukin (IL)-1ß and IL-10 in hidradenitis suppurativa skin: a rationale for targeting TNF-α and IL-1ß.

BACKGROUND: The pathogenesis of hidradenitis suppurativa (HS) is largely unknown and the disease is difficult to treat. Patients are in high need of an effective treatment. Although it is not known whether the levels of tumour necrosis factor (TNF)-α are aberrant in HS skin, anti-TNF-α biologics are used, with variable clinical efficacy. OBJECTIVES: To determine the cytokine profile in lesional and perilesional HS skin. METHODS: We cultured 20 lesional and 10 normal-appearing perilesional HS skin samples, seven psoriasis and six healthy control skin samples in a transwell culture system. Two distinct cytokine bead arrays were used to measure the spectrum of inflammatory cytokines in the culture supernatant. Results from HS skin samples were compared with those of healthy and psoriasis skin. RESULTS: The proinflammatory cytokines interleukin (IL)-1ß and TNF-α as well as the anti-inflammatory cytokine IL-10 were significantly elevated in HS skin. Elevated levels of these cytokines were also found in perilesional HS skin. Fold increases relative to control skin of IL-1ß, TNF-α and IL-10 in HS were 31, 5 and 34, compared with psoriasis: 4, 1 and 2, respectively. Levels of all three cytokines showed a trend towards a positive correlation with disease severity. IL-2, IL-4, IL-5 and interferon-γ were hardly detectable in HS or healthy control skin. CONCLUSIONS: This study shows for the first time that IL-1ß, TNF-α and IL-10 levels are elevated in HS skin. These data provide a rationale for therapies with biologics targeting cytokines such as TNF-α and IL-1.

Physical fitness, body fatness, and physical activity: The Amsterdam Growth and Health Study.

The purpose of this study was to examine sex-specific longitudinal relationships between physical fitness (cardiopulmonary and neuromotor fitness) and body fatness (sum of skinfolds) and to examine the influence of physical activity (weighted activity score) on these relationships. The data were obtained from the Amsterdam Growth and Health Study (AGHS), an observational longitudinal study of 98 females and 83 males, with six repeated measurements over a period from 13 to 27 years of age. The longitudinal relationship between body fatness and physical fitness was analyzed using generalized estimating equations (GEE). For each of the eight fitness items used as outcome variables, standardized regression coefficients were calculated for the relationships with body fatness and for the relationships with physical activity with and without correcting for height and weight. In all analyses, body fatness was inversely related to running speed, standing high jump, leg lift speed, and maximal oxygen uptake. Physical activity was positively related to leg lift speed and maximal oxygen uptake, and only in females to the standing high jump. Thus, body fatness is inversely related to most fitness items, while physical activity is positively related to only several fitness items. Further, body fatness and physical activity are independently related to physical fitness. Am. J. Hum. Biol. 12:593-599, 2000. Copyright 2000 Wiley-Liss, Inc.

Involvement of a humoral factor in regulation of body weight in parabiotic rats.

Excessive food intake and obesity was induced in one member of parabiotic pairs by electrical stimulation (three 30-min sessions/day for 2 wk) of the lateral hypothalamus (LH). The nonstimulated partners reduced spontaneous food intake the fatter the stimulated animals became. This reduced food intake resulted in a decreased body weight, fat content, and fat-free solid body mass. The decrease of food intake was not due to changed social behavior of the obese partner. It must be attributed to transmission of a humoral satiety factor. The very first stimulation of the LH in the stimulated partners resulted in a large increase in blood glucose and glucagon level without much change in the insulin level. These changes in blood parameters were probably due to strong sympathetic arousal. In the nonstimulated animals there were practically no changes in these parameters. One week of fattening resulted in increased basal glucose and insulin levels in the stimulated animals and decreased glucose levels in the nonstimulated partners, in which the basal insulin levels remained nearly normal. Basal glucagon levels were the same in both partners and did not differ from the prefattening situation. At that time during stimulation the obese animals showed a large increase in glucose and glucagon levels and a decrease in insulin level. On the other hand the nonstimulated animals showed a slow gradual increase in glucose and insulin level due to transmission from their fat partners because of the large gradient in these substances between the animals. These phenomena were still more pronounced after 2 wk of fattening. It is tentatively concluded that the humoral satiety factor is neither circulating insulin nor glucagon nor one of the major circulating nutrients.