Risk factors for mortality in patients with anti-NMDA receptor encephalitis

OBJECTIVE

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a severe autoimmune disorder with a mortality of 5%-7%, but few studies have focused on the predictors of death in this disease. In this study, we aim to investigate predictors and causes of death in patients with anti-NMDAR encephalitis.

METHODS

In this cohort study, patients with anti-NMDAR encephalitis were enrolled at the West China Hospital of Sichuan University between June 2011 and October 2015. The outcomes of patients were evaluated by long-term follow-up. Cox regression analysis was used to assess the association between potential predictors and death.

RESULTS

Altogether 96 patients were included in this study, and 11 died after median 24.5 (7-57) months of follow-up. The mortality of anti-NMDAR encephalitis was 11.46%. Multivariate analysis results showed that Glasgow Coma Scale (GCS) score ≤8 at admission (HR=15.917, 95% CI=1.729-146.562; P=.015), the number of complications (HR=7.772, 95% CI=1.944-31.072; P=.004), and admission to an intensive care unit (HR=70.158, 95% CI=2.395-2055.459; P=.014) were significantly associated with increased risk of mortality. Twelve patients received second-line immunotherapy, and the cohort was relatively under-treated compared with other studies. The main causes of death were severe pneumonia, multiple organ dysfunction syndrome, and refractory status epilepticus.

CONCLUSION

GCS score ≤8 at admission, number of complications, and admission to an intensive care unit are predictors of death. Management of complications may improve the prognosis of anti-NMDAR encephalitis.

The antisense expression of

Although phosphoenolpyruvate carboxylases (PEPCs) are reported to be involved in fatty acid accumulation, nitrogen assimilation, and salt and drought stresses, knowledge regarding PEPC gene functions is still limited, particularly in peanuts (Arachis hypogaea L.). In this study, the antisense expression of the peanut PEPC isoform 1 (AhPEPC1) gene increased the lipid content by 5.7%–10.3%. This indicated that AhPEPC1 might be related to plant lipid accumulation. The transgenic plants underwent more root elongation than the wild-type under salinity stress. Additionally, the specific down regulation of the AhPEPC1 gene improved the salt tolerance in peanuts. This is the first report on the role of PEPC in lipid accumulation and salt tolerance in peanuts.

Controlling Kondo-like Scattering at the SrTiO3-based Interfaces

The observation of magnetic interaction at the interface between nonmagnetic oxides has attracted much attention in recent years. In this report, we show that the Kondo-like scattering at the SrTiO3-based conducting interface is enhanced by increasing the lattice mismatch and growth oxygen pressure PO2. For the 26-unit-cell LaAlO3/SrTiO3 (LAO/STO) interface with lattice mismatch being 3.0%, the Kondo-like scattering is observed when PO2 is beyond 1 mTorr. By contrast, when the lattice mismatch is reduced to 1.0% at the (La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 (LSAT/STO) interface, the metallic state is always preserved up to PO2 of 100 mTorr. The data from Hall measurement and X-ray absorption near edge structure (XANES) spectroscopy reveal that the larger amount of localized Ti(3+) ions are formed at the LAO/STO interface compared to LSAT/STO. Those localized Ti(3+) ions with unpaired electrons can be spin-polarized to scatter mobile electrons, responsible for the Kondo-like scattering observed at the LAO/STO interface.

Developmental Eye Movement (DEM) Test Norms for Mandarin Chinese-Speaking Chinese Children

The Developmental Eye Movement (DEM) test is commonly used as a clinical visual-verbal ocular motor assessment tool to screen and diagnose reading problems at the onset. No established norm exists for using the DEM test with Mandarin Chinese-speaking Chinese children. This study aims to establish the normative values of the DEM test for the Mandarin Chinese-speaking population in China; it also aims to compare the values with three other published norms for English-, Spanish-, and Cantonese-speaking Chinese children. A random stratified sampling method was used to recruit children from eight kindergartens and eight primary schools in the main urban and suburban areas of Nanjing. A total of 1,425 Mandarin Chinese-speaking children aged 5 to 12 years took the DEM test in Mandarin Chinese. A digital recorder was used to record the process. All of the subjects completed a symptomatology survey, and their DEM scores were determined by a trained tester. The scores were computed using the formula in the DEM manual, except that the “vertical scores” were adjusted by taking the vertical errors into consideration. The results were compared with the three other published norms. In our subjects, a general decrease with age was observed for the four eye movement indexes: vertical score, adjusted horizontal score, ratio, and total error. For both the vertical and adjusted horizontal scores, the Mandarin Chinese-speaking children completed the tests much more quickly than the norms for English- and Spanish-speaking children. However, the same group completed the test slightly more slowly than the norms for Cantonese-speaking children. The differences in the means were significant (P<0.001) in all age groups. For several ages, the scores obtained in this study were significantly different from the reported scores of Cantonese-speaking Chinese children (P<0.005). Compared with English-speaking children, only the vertical score of the 6-year-old group, the vertical-horizontal time ratio of the 8-year-old group and the errors of 9-year-old group had no significant difference (P>0.05); compared with Spanish-speaking children, the scores were statistically significant (P<0.001) for the total error scores of the age groups, except the 6-, 9-, 10-, and 11-year-old age groups (P>0.05). DEM norms may be affected by differences in language, cultural, and educational systems among various ethnicities. The norms of the DEM test are proposed for use with Mandarin Chinese-speaking children in Nanjing and will be proposed for children throughout China.

PCB1254 exposure contributes to the abnormalities of optomotor responses and influence of the photoreceptor cell development in zebrafish larvae

Polychlorinated biphenyls (PCBs), a group of highly toxic environmental pollutants, have been report to influence the visual system development in children. However, the underlying mechanism is unclear. The study was aim to investigate the effects of continuous PCBs exposure on optomotor response (OMR) and retinal photoreceptor cell development-related gene expression in zebrafish larvae. The fertilized zebrafish embryos were exposed to PCBs at concentrations of 0.125, 0.25, 0.5, and 1mg/L until 7 days post-fertilization. Control groups with blank and 0.01% methanol were also prepared. OMR test was used to detect the visual behavior. The mRNA expression of the CRX, RHO, SWS1, and SWS2 was assessed by the Quantitative Real-Time PCR. The OMR test showed that the visual behavior of the larvae was most sensitive when the grating spatial frequency was 0.20LP/mm and the moving speed was 25cm/s. Moreover, the proportion of positively swimming fish was significantly reduced in the 0.5 and 1mg/L PCB1254 treatment group (P<0.05) compared with the controls. In addition, the expression of SWS2 was significantly down-regulated in all PCB1254 treatment groups (P<0.05), whereas the decreased expression of the CRX, RHO and SWS1 was found in the 0.5 and 1mg/L PCB1254 groups (P<0.05). This is the first report to demonstrate that continue exposure of zebrafish larvae to PCBs causes photoreceptor cell development-related gene expression changes that lead to OMR behavioral alterations. Analysis of these visual behavioral paradigms may be useful in predicting the adverse effects of toxicants on visual function in fish.

miR-148a is Associated with Obesity and Modulates Adipocyte Differentiation of Mesenchymal Stem Cells through Wnt Signaling

Obesity results from numerous, interacting genetic, behavioral, and physiological factors. Adipogenesis is partially regulated by several adipocyte-selective microRNAs (miRNAs) and transcription factors that regulate proliferation and differentiation of human adipose-derived mesenchymal stem cells (hMSCs-Ad). In this study, we examined the roles of adipocyte-selective miRNAs in the differentiation of hMSCs-Ad to adipocytes. Results showed that the levels of miR-148a, miR-26b, miR-30, and miR-199a increased in differentiating hMSCs-Ad. Among these miRNAs, miR-148a exhibited significant effects on increasing PPRE luciferase activity (it represents PPAR-dependent transcription, a major factor in adipogenesis) than others. Furthermore, miR-148a expression levels increased in adipose tissues from obese people and mice fed high-fat diet. miR-148a acted by suppressing its target gene, Wnt1, an endogenous inhibitor of adipogenesis. Ectopic expression of miR-148a accelerated differentiation and partially rescued Wnt1-mediated inhibition of adipogenesis. Knockdown of miR-148a also inhibited adipogenesis. Analysis of the upstream region of miR-148a locus identified a 3 kb region containing a functional cAMP-response element-binding protein (CREB) required for miR-148a expression in hMSCs-Ad. The results suggest that miR-148a is a biomarker of obesity in human subjects and mouse model, which represents a CREB-modulated miRNA that acts to repress Wnt1, thereby promoting adipocyte differentiation.

Are sporadic fidgety movements as clinically relevant as is their absence?

BACKGROUND

Infants with normal fidgety movements at 3 to 5 months after term are very likely to show neurologically normal development, while the absence of fidgety movements is an early marker for an adverse neurological outcome, mainly cerebral palsy (CP). The clinical significance of so-called sporadic fidgety movements (i.e., fidgety movements occur isolated in a few body parts and are of 1- to 3-second-duration) is not yet known.

AIMS

Our objective was to determine whether infants who had developed CP and had sporadic fidgety movements have a better outcome than infants who did not have fidgety movements.

STUDY DESIGN

Longitudinal study. Retrospective analysis of prospectively collected data.

SUBJECTS

61 infants who developed CP (46 male, 15 female; 29 infants born preterm; videoed for the assessment of movements and postures at 9 to 16 weeks post-term age).

OUTCOME MEASURES

The Gross Motor Function Classification System (GMFCS) was applied at 3 to 5 years of age.

RESULTS

There was no difference between children diagnosed with CP who had sporadic fidgety movements at 9 to 16 weeks post-term age (n = 9) and those who never developed fidgety movements (n = 50) with regard to their functional mobility and activity limitation at 3 to 5 years of age. One infant had normal FMs and developed unilateral CP, GMFCS Level I; the remaining infant had abnormal FMs and developed bilateral CP, GMFCS Level II.

CONCLUSIONS

There is no evidence that the occurrence of occasional isolated fidgety bursts indicates a milder type of CP.

Increased locomotor activity and non-selective attention and impaired learning ability in SD rats after lentiviral vector-mediated RNA interference of Homer 1a in the brain

Our previous studies found that Homer 1a, a scaffolding protein localized at the post-synaptic density (PSD) of glutamatergic excitatory synapses, is significantly down-regulated in the brain of spontaneous hypertensive rats (SHR), an animal model of attention deficit hyperactivity disorder (ADHD). Furthermore, a first-line treatment drug for ADHD, methylphenidate, can up-regulate the expression of Homer 1a. To investigate the possible role of Homer 1a in the etiology and pathogenesis of ADHD, a lentiviral vector containing miRNA specific for Homer 1a was constructed in this study. Intracerebroventricular injection of this vector into the brain of Sprague Dawley (SD) rats significantly decreased Homer 1a mRNA and protein expression levels. Compared to their negative controls, these rats displayed a range of abnormal behaviors, including increased locomotor activity and non-selective attention and impaired learning ability. Our results indicated that Homer 1a down-regulation results in deficits in control over behavioral output and learning similar to ADHD.

Learning Chronobiology by Improving Wikipedia

Although chronobiology is of growing interest to scientists, physicians, and the general public, access to recent discoveries and historical perspectives is limited. Wikipedia is an online, user-written encyclopedia that could enhance public access to current understanding in chronobiology. However, Wikipedia is lacking important information and is not universally trusted. Here, 46 students in a university course edited Wikipedia to enhance public access to important discoveries in chronobiology. Students worked for an average of 9 h each to evaluate the primary literature and available Wikipedia information, nominated sites for editing, and, after voting, edited the 15 Wikipedia pages they determined to be highest priorities. This assignment ( http://www.nslc.wustl.edu/courses/Bio4030/wikipedia_project.html ) was easy to implement, required relatively short time commitments from the professor and students, and had measurable impacts on Wikipedia and the students. Students created 3 new Wikipedia sites, edited 12 additional sites, and cited 347 peer-reviewed articles. The targeted sites all became top hits in online search engines. Because their writing was and will be read by a worldwide audience, students found the experience rewarding. Students reported significantly increased comfort with reading, critiquing, and summarizing primary literature and benefited from seeing their work edited by other scientists and editors of Wikipedia. We conclude that, in a short project, students can assist in making chronobiology widely accessible and learn from the editorial process.

Homer expression in the hippocampus of an animal model of attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a pervasive neurobehavioral disorder. We previously demonstrated differential expression of some isoforms of Homer, a family of scaffolding proteins localized to the postsynaptic density of glutamatergic excitatory synapses, in the spontaneous hypertensive rat (SHR), which is the most frequently used animal model of ADHD. Since these changes were observed in the prefrontal cortex (PFC), a critical structure in ADHD, it was hypothesized that these Homer isoforms may play a role in ADHD. The present study aimed to extend these findings to the hippocampus, which has direct connections to the PFC and subserves attention and cognition, two functions that are disturbed in ADHD. Hippocampal mRNA and protein expression of several Homer isoforms were investigated in both SHR and control Wistar-Kyoto (WKY) rats using reverse transcription-polymerase chain reaction and Western blotting, respectively. Both mRNA and protein for Homer 1a and Homer 2a/b, but not Homer 1b/c, were expressed at significantly lower levels in the hippocampus of SHR compared to WKY rats. The effects of methylphenidate (MPH) on spatial learning and memory in SHRs were also examined using the Morris water maze and on hippocampal expression of Homer isoforms. MPH improved spatial learning and memory and up-regulated hippocampal expression of Homer 1a and Homer 2a/b, but not Homer 1b/c, in SHRs. The animal model of ADHD may have altered expression of Homer 1a and Homer 2a/b in the hippocampus, in addition to the PFC. Future studies will focus on elucidating the specific mechanisms of Homer 1a and Homer 2a/b in ADHD.

Abnormal synaptic plasticity in basolateral amygdala may account for hyperactivity and attention-deficit in male rat exposed perinatally to low-dose bisphenol-A

If the pregnant and lactating female rats are exposed to environmental levels of bisphenol-A (BPA), their male offspring will display hyperactivity and attention-deficit. In patients with attention-deficit/hyperactivity disorder (ADHD), the size of the amygdala is reported to be reduced. This study examined functional alterations in the basolateral amygdala (BLA) of the postnatal 28-day-old male offspring exposed perinatally to BPA (BPA-rats). We specifically focused on the synaptic properties of GABAergic/dopaminergic systems in the BLA. A single electrical stimulation of the capsule fibers evoked multispike responses with an enhanced primary population spikes (1st-PS) in the BPA-rats. A single train of high-frequency stimulation of the fibers induced NMDA receptor (NMDAR) dependent long-term potentiation (LTP) in BPA-rats, but not in control rats. Also, paired-pulse inhibition (PPI, GABA-dependent) in control rats was reversed to paired-pulse facilitation (PPF) in BPA-rats. Perfusion of slices obtained from BPA-rats with the GABA(A) receptor (GABA(A)R) agonist muscimol blocked the multispike responses and LTP, and recovered PPI. By contrast, the dopamine D1 receptor antagonist SCH23390 abolished LTP and attenuated the increased amplitude of 1st-PS in BPA-rats. Conversely, blockade of GABA(A)R by bicuculline could produce the multispike responses and PPF in BLA in control rats. Furthermore, in BLA the infusion of SCH23390, muscimol or the NMDAR blocker MK801 ameliorated the hyperactivity and improved the deficits in attention. These findings suggest that the perinatal exposure to BPA causes GABAergic disinhibition and dopaminergic enhancement, leading to an abnormal cortical-BLA synaptic transmission and plasticity, which may be responsible for the hyperactivity and attention-deficit in BPA-rats. This article is part of a Special Issue entitled 'Synaptic Plasticity & Interneurons'.

[Longitudinal study of the physical catch-up growth in 84 preterm appropriate for gestational age infants]

OBJECTIVE

To study the growth rhythm of preterm appropriate for gestational age (AGA) infants by investigating their physical catch-up growth characteristics.

METHODS

Eighty-four preterm AGA newborns (44 males and 40 females) with gestational ages between 28-36 weeks were enrolled. The weight, length and head circumference were evaluated by Z score according to the criterions of actual and corrected ages.

RESULTS

The preterm infants had the catch-up growth in weight, length and head circumference in the first year of life. The growth velocity within the first three months was the highest. The velocity in the weight catch-up was higher than that in the length.

CONCLUSIONS

The fastest growing period is the early three month of life in preterm AGA infants. The catch-up growth in weight and length is unbalanced.

Abstract P3-14-20: Phase 1 Dose-Escalation Study of the Investigational HER2/EGFR Inhibitor TAK-285 in Patients with Advanced Cancer

Background and Objectives: TAK-285 is a novel, orally active, dual HER2/EGFR inhibitor. Nonclinical data show that TAK-285 has high selectivity and specificity for binding to HER family kinases, and has demonstrated anti-tumor activity in a BT-474 mouse xenograft model of breast cancer. Nonclinical data also indicate that TAK-285 is not a substrate for the efflux transporters P-gp and BCRP and penetrates an intact blood-brain barrier in rats. This phase 1 dose-escalation study in patients with advanced cancer aimed to determine the safety and pharmacokinetic (PK) profile.

Methods: Adults had advanced histologically confirmed non-hematologic malignancies, life expectancy &gt;12 weeks, adequate bone marrow, liver and renal function, ECOG PS 0-2, and were refractory to other treatments. Oral TAK-285 was escalated from 50 to 500 mg QD or BID for 21 or 28 consecutive days of a 28-day cycle until disease progression or unacceptable toxicity was observed.

Results: At the data cut-off of 04/23/10, the dose-escalation portion was complete, and the RP2D expansion cohort is ongoing. Preliminary data from the dose-escalation cohorts are reported. 43 patients (median age 60 years [43-76]) were enrolled: 30% ≥65 years, 51% female, and 86% white. Dose levels were 50 mg QD (N=4), 50 mg BID (N=7), and 75 mg BID (N=6) on d 1-21; and 150 mg (N=6), 225 mg (N=4), 325 mg (N=3), 400 mg (N=6), and 500 mg (N=7) BID on d 1-28. Median duration of exposure across all cohorts was 52 days (3-267). Four patients experienced a DLT in Cycle 1: 1 patient (50 mg BID) had Grade 3 pancreatitis; 1 patient (150 mg BID) had Grade 3 chest pain and Grade 3 hypoxia; 1 patient (500 mg BID) had Grade 3 increased ALT; and 1 patient (500 mg BID) had Grade 3 diarrhoea and Grade 3 hypokalaemia. The MTD was 400 mg BID d 1-28. 30 patients (70%) discontinued TAK-285, primarily due to disease progression (n=19, 44%) or an AE (n=9, 21%). Most frequent AEs were fatigue (37%), diarrhoea (35%), nausea (26%), anorexia (21%), vomiting (16%), and elevated AST (16%). 58% of patients had a drug-related AE; the most frequent were diarrhoea (21%), fatigue (19%), and rash (includes rash, rash maculo-papular and rash macular; 12%). 35% of patients had a grade 3/4 AE; the most common were hypokalaemia (7%), ileus, abdominal pain, and hypoxia (5% each). Grade 3/4 AEs related to TAK-285 were the DLTs in Cycle 1 and Grade 4 rhabdomyolysis in 1 patient (400 mg BID, d 1-28) in Cycle 3. 42% of patients experienced a serious AE (SAE); the only SAE seen in &gt;1 patient was ileus (n=2). 4 (9%) patients had fatal AEs; none were considered related to TAK-285. Absorption was fast: plasma concentrations peaked 2-3 hours post-dose. Steady-state plasma exposures increased with dose in a greater than dose-proportional manner, with PK steady-state achieved by Day 8. Accumulation was noted with BID dosing (mean accumulation ratio, 2.4 at MTD); there was moderate fluctuation in plasma concentrations over the steady-state dosing interval (mean Cmax:Cmin ratio, 2.4 at MTD).

Conclusions: The MTD for TAK-285 was 400 mg BID d 1-28. The RP2D cohort is ongoing and includes CSF collection to assess the CNS distribution of TAK-285. Updated safety as well as efficacy data for the dose escalation cohorts will be presented.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-14-20.

Effects of NYGGF4 knockdown on insulin sensitivity and mitochondrial function in 3T3-L1 adipocytes

NYGGF4 is a recently discovered gene that is involved in obesity-associated insulin resistance. It has been suggested that mitochondrial dysfunction might be responsible for the development of insulin resistance induced by NYGGF4 overexpression. In the present study, we aimed to define the impact of down-regulating NYGGF4 expression by RNA interference (RNAi) on the insulin sensitivity and mitochondrial function of 3T3-L1 adipocytes. The results revealed that NYGGF4 knockdown enhanced the glucose uptake of adipocytes, which reconfirmed the regulatory function of NYGGF4 in adipocyte insulin sensitivity. However, an unexpected observation was that knockdown of NYGGF4 reduced intracellular ATP concentration and promoted an increase in mitochondrial transmembrane potential (ΔΨm) and reactive oxygen species (ROS) level without affecting mitochondrial morphology or mtDNA. Therefore, the role of NYGGF4 in mitochondrial function remains unclear, and further animal studies are needed to explore the biological function of this gene.

Prefrontal cortex Homer expression in an animal model of attention-deficit/hyperactivity disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is a pervasive neurobehavioral disorder affecting approximately 5% of children and adolescents and 3% of adults, and the prefrontal cortex (PFC) may play the most critical role in the expression of ADHD. Converging previous studies indicate a potential role of Homer--a scaffolding protein family localized at the postsynaptic density (PSD) of glutamatergic excitatory synapses--in behavioral pathologies associated with neuropsychiatric disorders. Accordingly, we speculate that these Homer isoforms might contribute to the etiology and development of ADHD.

METHOD

We investigated the differential mRNA and protein expressions of several Homer isoforms in the PFC of the spontaneous hypertensive rat/Wistar-Kyoto rats (SHR/WKY), the most frequently used animal model of ADHD, using RT-PCR and western blotting. Furthermore, we examined the effects of methylphenidate (MPH) exposure on the behaviors and the expression of different Homer isoforms in the PFC of SHR, using Làt maze, RT-PCR and western blotting, respectively.

RESULTS

Homer 1a and Homer 2a/b, but not Homer 1b/c, were expressed at a significantly lower levels in the PFC of SHR compared with WKY. MPH exposure decreased the locomotor activity and non-selective attention of SHR, and it up regulated the expression of Homer 1a and Homer 2a/b, but not Homer 1b/c, in the PFC of SHR.

CONCLUSION

It is plausible that Homer 1a and Homer 2a/b may be involved in the etiology and pathogenesis of ADHD. Future work will focus on elucidating the specific mechanisms of Homer 1a and Homer 2a/b in ADHD.

Gene expression profiles in the prefrontal cortex of SHR rats by cDNA microarrays

We have undertaken cDNA microarrays to identify differentially expressed genes in the prefrontal cortex (PFC) of spontaneously hypertensive-rat (SHR), a rodent model of attention deficit hyperactivity disorder (ADHD) versus control Wistar-Kyoto (WKY) rats. The analysis of the gene expression profiles indicated that 57 genes were up-regulated and 97 genes were down-regulated in the PFC of SHR. These predominately expressed genes included genes involved in neural development, immunity, transcription factor, monoamine neurotransmitter, metabolism, signal transduction, apoptosis and so on. Although more detailed analyses are necessary, it is anticipated that further study of genes identified will provide insights into their specific roles in the etiology of ADHD.

LYRM1, a novel gene promotes proliferation and inhibits apoptosis of preadipocytes

OBJECTIVE

To characterize a novel gene, Homo sapiens LYR motif containing 1 (LYRM1), that is highly expressed in omental adipose tissue of obese subjects.

METHODS AND RESULTS

RT-PCR and western blot analysis confirmed that both mRNA and protein levels of LYRM1 were higher in omental adipose tissue of obese subjects than in normal weight subjects. RT-PCR analysis demonstrated that LYRM1 expression is widely distributed, with the highest levels of expression occurring in adipose tissue. A fusion protein of LYRM1 and green fluorescent protein as well as western blot analysis were used to identify the subcellular localization of LYRM1 in the nucleus. Based on Oil red O staining and the expression profile of specific differentiation markers, ectopic LYRM1 expression was not found to significantly affect adipogenesis. MTT assays and cell cycle analysis showed that LYRM1 promotes preadipocyte proliferation, and data from annexin V-FITC and caspase-3 activity assays further determined that LYRM1 can inhibit apoptosis of preadipocytes.

CONCLUSIONS

By increasing cell proliferation and lowering the rate of apoptosis, LYRM1 has the potential to modulate the size of the preadipocyte pool and influence adipose tissue homeostasis.