Hypercholesterolemia Enhances Tolerance to Lethal Systemic Hypoxia in Middle-Aged Mice: Possible Role of VEGF Downregulation in Brain

Predictive Value of Blood Urea Nitrogen to Albumin Ratio in Long-Term Mortality in Intensive Care Unit Patients with Acute Myocardial Infarction: A Propensity Score Matching Analysis

Background

Blood urea nitrogen to albumin ratio (BAR) has been implicated in predicting outcomes of various inflammatory-related diseases. However, the predictive value of BAR in long-term mortality in patients with acute myocardial infarction (AMI) has not yet been evaluated.

Methods

In this retrospective cohort study, the patients were recruited from the Medical Information Mart for Intensive Care III (MIMIC III) database and categorized into two groups by a cutoff value of BAR. Kaplan–Meier (K-M) analysis and Cox proportional hazard model were performed to determine the predictive value of BAR in long-term mortality following AMI. In order to adjust the baseline differences, a 1:1 propensity score matching (PSM) was carried out and the results were further validated.

Results

A total of 1827 eligible patients were enrolled. The optimal cutoff value of BAR for four-year mortality was 7.83 mg/g. Patients in the high BAR group tended to have a longer intensive care unit (ICU) stay and a higher rate of one-, two-, three- and four-year mortality (all p<0.001) compared with those in the low BAR group. K-M curves indicated a significant difference in four-year survival (p<0.001) between low and high BAR groups. The Cox proportional hazards model showed that higher BAR (>7.83) was independently associated with increased four-year mortality in the entire cohort, with a hazard ratio (HR) of 1.478 [95% CI (1.254–1.740), p<0.001]. After PSM, the baseline characteristics of 312 pairs of patients in the high and low BAR groups were well balanced, and similar results were observed in K-M curve (p=0.003).

Conclusion

A higher BAR (>7.83) was associated with four-year mortality in patients with AMI. As an easily available biomarker, BAR can predict the long-term mortality in AMI patients independently.

Metabolic syndrome increases risk of venous thromboembolism recurrence after acute deep vein thrombosis

An improved understanding of which patients are at higher risk of recurrent venous thromboembolism (VTE) is important to designing interventions to reduce degraded quality of life after VTE. Although metabolic syndrome (MetS), the clustering of hypertension, hyperlipidemia, diabetes mellitus, and obesity has been associated with a hypofibrinolytic state, data linking VTE recurrence with MetS remain limited. The purpose of this study was to measure the prevalence of MetS in patients with deep vein thrombosis (DVT) across a large population and determine its effect on VTE recurrence. This was a retrospective analysis of a large statewide database from 2004 to 2017. We measured the frequency with which patients with DVT carried a comorbid International Coding of Diseases diagnosis of MetS components. Association of MetS with VTE recurrence was tested with a multiple logistic regression model and VTE recurrence as the dependent variable. Risk of VTE recurrence conferred by each MetS component was assessed by Kaplan-Meier curves with the log-rank statistic. A total of 151 054 patients with DVT were included in this analysis. Recurrence of VTE occurred in 17% overall and increased stepwise with each criterion for MetS. All 4 components of MetS had significant adjusted odds ratios (OR) for VTE recurrence, with hyperlipidemia having the largest (OR, 1.8), representing the 4 largest ORs of all possible explanatory variables. All 4 MetS variables were significant on Kaplan-Meier analysis for recurrence of VTE. These data imply a role for appropriate therapies to reduce the effects of MetS as a way to reduce risk of VTE recurrence.

A Meta-Analysis of Prognostic Factors in Patients with Posterior Circulation Stroke after Mechanical Thrombectomy

BACKGROUND

Posterior circulation stroke is characterized by poor prognosis because its optimal thrombolysis "time window" is always missed. After mechanical thrombectomy (MT), the recanalization rate of posterior circulation obstruction is significantly increased, but prognosis remains poor. To best manage patients, prognostic factors are needed to inform MT triaging after posterior circulation stroke.

METHODS

A systematic literature search was done for the period through April 2020. Studies included those with posterior circulation stroke cases that underwent MT. The primary outcome measure in this study was the modified Rankin Scale on day 90.

RESULTS

No outcome differences were found in gender, atrial fibrillation, smoking, and coronary artery disease (OR = 1.07, 95% CI: 0.90-1.28; OR = 1.02, 95% CI: 0.82-1.26; OR = 1.26, 95% CI: 0.94-1.68; and OR = 0.84, 95% CI: 0.58-1.22, respectively). Hypertension, diabetes mellitus, and previous stroke correlated with poorer prognosis (OR = 0.61, 95% CI: 0.48-0.77; OR = 0.60, 95% CI: 0.50-0.73; and OR = 0.74, 95% CI: 0.55-0.99, respectively). However, hyperlipidemia correlated with better prognosis (OR = 1.28, 95% CI: 1.04-1.58).

CONCLUSION

Our analysis indicates that hypertension, diabetes mellitus, or previous stroke correlate with poorer outcomes. Intriguingly, hyperlipidemia correlates with better prognosis. These factors may help inform triage decisions when considering MT for posterior circulation stroke patients. However, large, multicenter, randomized controlled trials are needed to validate these observations.

Low density lipoprotein cholesterol values and outcome of stroke patients: influence of previous aspirin therapy

Background: The link between low-density lipoprotein cholesterol (LDL-C) and stroke risk remains controversial and few studies have evaluated the effect of LDL-C after stroke survival.Aims: We assessed the hypothesis proposing the effect of LDL-C on the outcome of stroke patients under the influence of previous Aspirin Therapy.Methods: Associations between LDL-C and outcomes. The effect of LDL cholesterol on stoke outcome was evaluated using Kaplan-Meier methodology, log-rank test, Cox proportional hazard models and Bootstrap Analysis.Results: In a cohort of 342 cases, we observed that among stroke patients with no record of previous aspirin therapy LDL-C levels within recommended range (nLDL-C) are associated to a poor overall survival on (p < 0.001, log-rank test) leading to a 4-fold increased mortality risk in both timeframes of 12 (HR 4.45, 95% CI 1.55-12.71; p = 0.004) or 24 months (HR 4.13, 95%CI 1.62-10.50;p = 0.003) after the first event of stroke. Moreover, modelling the risk of a second event after the first stroke in the timeframe of 24 months demonstrated a predictive capacity for nLDL-C plasmatic levels (HR 3.94, 95%CI 1.55-10.05; p = 0.004) confirmed by Bootstrap analysis (p = 0.003; 1000 replications). In a further step, the inclusion of LDL-C in simulating models equations to predict the risk of a second event in the timeframe of 12 months increased nearly 20% the predictive ability (c-index from 0.763 to 0.956).Conclusion: A worse outcome was seen in stroke patients with normal levels of LDLC, but this finding was restricted to patients not under previous aspirin therapy.

Effect of Intranasally Delivered rh-VEGF165 on Angiogenesis Following Cerebral Hypoxia-Ischemia in the Cerebral Cortex of Newborn Piglets

Background: Vascular endothelial growth factor (VEGF) stimulates vascular genesis and angiogenesis. Cerebral Hypoxia-Ischemia (HI) leads to the reduction of vasculature in the cerebral cortex of newborn piglets. Objective: The present study tests the hypothesis that post-hypoxia intranasal administration of recombinant human VEGF₁₆₅ (rh-VEGF165) for 3 days increases the vascular density in the cerebral cortex of newborn piglets without promoting neovascularization. Design/Methods: Ventilated newborn piglets were divided into three groups (n = 5/group): normoxic (Nx), hypoxic-ischemic (HI), and HI treated with intranasal rh-VEGF165rh-VEGF165 (HI-VEGF). HI piglets were exposed to HI (0.05 FiO2) for 30 min. Recombinant h-VEGF165 (100 ng/kg) was administered 15 min after HI and then once daily for 3 days. The animals were perfused transcardially and coronal brains sections were processed for Isolectin, Hoechst, and ki-67 cell proliferation marker staining. To assess the vascular density, 30–35 fields per animal section were manually counted using image J software. Results: The vascular density (vessels/mm²) was 42.0 ± 8.0 in the Nx group, 26.4 ± 4.8 (p < 0.05 vs. Nx) in the HI group, and 46.0 ± 11.9 (p < 0.05 vs. HI) in the HI-VEGF group. When stained for newly formed vessels, via Ki-67 staining, the vascular density was 5.4 ± 3.6 in the Nx group (p < 0.05 vs. HI), 10.2 ± 2.1 in the HI group, and 10.9 ± 2.9 in the HI-VEGF group (p = 0.72 vs. HI). HI resulted in a decrease in vascular density. Intranasal rh-VEGF165rh-VEGF165 resulted in the attenuation of the HI-induced decrease in vascular density. However, rh-VEGF165 did not result in the formation of new vascularity, as evident by ki-67 staining. Conclusions: Intranasal rh-VEGF165 may prevent the HI-induced decrease in the vascular density of the brain and could serve as a promising adjuvant therapy for hypoxic-ischemic encephalopathy (HIE).

Genomic and phenotypic signatures of climate adaptation in an Anolis lizard

Integrated knowledge on phenotype, physiology, and genomic adaptations is required to understand the effects of climate on evolution. The functional genomic basis of organismal adaptation to changes in the abiotic environment, its phenotypic consequences, and its possible convergence across vertebrates are still understudied. In this study, we use a comparative approach to verify predicted gene functions for vertebrate thermal adaptation with observed functions underlying repeated genomic adaptations in response to elevation in the lizard Anolis cybotes. We establish a direct link between recurrently evolved phenotypes and functional genomics of altitude-related climate adaptation in three highland and lowland populations in the Dominican Republic. We show that across vertebrates, genes contained in this interactome are expressed within the brain, the endocrine system, and during development. These results are relevant to elucidate the effect of global climate change across vertebrates and might aid in furthering insight into gene-environment relationships under disturbances to homeostasis.

Cholesterol Levels Are Associated with 30-day Mortality from Ischemic Stroke in Dialysis Patients

BACKGROUND

We investigated the impact of serum cholesterol levels on 30-day mortality after ischemic stroke in dialysis patients.

METHODS

From the Taiwan Stroke Registry data, we identified 46,770 ischemic stroke cases, including 1101 dialysis patients and 45,669 nondialysis patients from 2006 to 2013.

RESULTS

Overall, the 30-day mortality was 1.46-fold greater in the dialysis group than in the nondialysis group (1.75 versus 1.20 per 1000 person-days). The mortality rates were 1.64, .62, 2.82, and 2.23 per 1000 person-days in dialysis patients with serum total cholesterol levels of <120 mg/dL, 120-159 mg/dL, 160-199 mg/dL, and ≥200 mg/dL, respectively. Compared to dialysis patients with serum total cholesterol levels of 120-159 mg/dL, the corresponding adjusted hazard ratios of mortality were 4.20 (95% confidence interval [CI] = 1.01-17.4), 8.06 (95% CI = 2.02-32.2), and 6.89 (95% CI = 1.59-29.8) for those with cholesterol levels of <120 mg/dL, 160-199 mg/dL, and ≥200 mg/dL, respectively.

CONCLUSIONS

Dialysis patients with serum total cholesterol levels of ≥160 mg/dL or <120 mg/dL on admission are at an elevated hazard of 30-day mortality after ischemic stroke.

Hyperlipidemia is associated with lower risk of poststroke mortality independent of statin use: A population-based study

Background Although statin therapy is associated with reduced stroke and mortality risk, some studies report that higher lipid levels are associated with improved outcomes following ischemic stroke. Aims We examined the association of hyperlipidemia (HLD) combined with statin therapy on all-cause mortality in stroke patients. Methods All stroke patients in the Greater Cincinnati Northern Kentucky region of ∼1.3 million were identified using ICD-9 discharge codes in 2005 and 2010. Stroke patients with and without HLD were categorized based on their reported statin use at baseline or discharge into three groups: no-HLD/no-statins, HLD/no-statins, and HLD/on-statins. Cox proportional hazards model was used to estimate the risk of mortality at 30 days, 1 year, and 3 years poststroke. Results Overall, 77% (2953) of the 3813 ischemic stroke patients were diagnosed with HLD and 72% ( n = 2123) of those patients were on statin medications. The mean age was 70.0 ± 14.6 years, 56% were women, and 21% were black. In adjusted analyses, the HLD/no-statins group showed 35% (adjusted hazard ratio (aHR) = 0.65, 95% CI: 0.46-0.92), 27% (aHR = 0.73, 95% CI: 0.59-0.90), and 17% (aHR = 0.83, 95% CI: 0.70-0.97) reduced risk of mortality at 30 days, 1 year, and 3 years, respectively, poststroke, compared with no-HLD/no-statins group. The HLD/on-statins group showed an additional 17% significant survival benefit at 3 years poststroke compared with HLD/no-statins group. Conclusions A diagnosis of HLD in ischemic stroke patients is associated with reduced short- and long-term mortality, irrespective of statin use. Statin therapy is associated with significant, additional long-term survival benefit.

Prognostic factors for long-term poor outcomes after acute ischemic stroke in very old age (>80 years) patients: Total cholesterol level might differently influence long-term outcomes after acute ischemic stroke at ages above 80 years

AIM

We investigated the differences in determinant factors for functional outcomes between patients aged >80 years and those aged <80 years after acute ischemic stroke (AIS). In particular, we would like to know the differential impacts of initial total cholesterol (TC) levels between the two groups.

METHODS

We defined a poor outcome as 3-6 modified Rankin Scale 90 days after AIS.

RESULTS

In the present study, 2772 participants were enrolled. Among them, 374 patients (13.5%) were aged >80 years, and 1061 patients had a poor outcome 90 days after AIS. The proportion was significantly higher in patients aged >80 years than in those aged <80 years after AIS. Regarding factors relating to poor outcomes, previous history of stroke, stroke severity and stroke subtypes of ischemic stroke were independent factors in patients aged <80 years, and the stroke severity and initial TC level independently influenced the outcome for patients aged >80 years. In particular, risk of poor outcome adjusted for age, stroke severity and subtypes of ischemic stroke for patients (OR [95% CI]) in the first quartile range (≤157 mg%) were 2.21 (1.06-4.62), in the third quartile range (184-210 mg%) 2.76 (1.27-6.01) and in the fourth quartile range (≥211 mg%) 2.75 (1.21-6.24) compared with those in the second quartile range (158-183 mg%) in patients aged >80 years.

CONCLUSIONS

There were also some differences in related factors regarding occurrences of poor outcome between the two groups. In particular, the initial TC level might play a crucial role for the outcome after AIS in the very old population.

Mouse models to study the effect of cardiovascular risk factors on brain structure and cognition

Recent clinical data indicates that hemodynamic changes caused by cardiovascular diseases such as atherosclerosis, heart failure, and hypertension affect cognition. Yet, the underlying mechanisms of the resulting vascular cognitive impairment (VCI) are poorly understood. One reason for the lack of mechanistic insights in VCI is that research in dementia primarily focused on Alzheimer's disease models. To fill in this gap, we critically reviewed the published data and various models of VCI. Typical findings in VCI include reduced cerebral perfusion, blood-brain barrier alterations, white matter lesions, and cognitive deficits, which have also been reported in different cardiovascular mouse models. However, the tests performed are incomplete and differ between models, hampering a direct comparison between models and studies. Nevertheless, from the currently available data we conclude that a few existing surgical animal models show the key features of vascular cognitive decline, with the bilateral common carotid artery stenosis hypoperfusion mouse model as the most promising model. The transverse aortic constriction and myocardial infarction models may be good alternatives, but these models are as yet less characterized regarding the possible cerebral changes. Mixed models could be used to study the combined effects of different cardiovascular diseases on the deterioration of cognition during aging.

Clinical significance of plasma VEGF value in ischemic stroke - research for biomarkers in ischemic stroke (REBIOS) study

Background

Vascular endothelial growth factor (VEGF) is a well-known molecule mediating neuronal survival and angiogenesis. However, its clinical significance in ischemic stroke is still controversial. The goal of this study was to examine the temporal profile of plasma VEGF value and its clinical significance in ischemic stroke with taking its subtypes into consideration.

Methods

We prospectively enrolled 171 patients with ischemic stroke and age- and gender-matched healthy subjects. The stroke patients were divided into 4 subtypes: atherothrombotic infarction (ATBI, n = 34), lacunar infarction (LAC, n = 45), cardioembolic infarction (CE, n = 49) and other types (OT, n = 43). Plasma VEGF values were measured as a part of multiplex immunoassay (Human MAP v1.6) and we obtained clinical information at 5 time points (days 0, 3, 7, 14 and 90) after the stroke onset.

Results

Plasma VEGF values were significantly higher in all stroke subtypes but OT than those in the controls throughout 90 days after stroke onset. There was no significant difference in the average VEGF values among ATBI, LAC, and CE. VEGF values were positively associated with neurological severity in CE patients, while a negative association was found in ATBI patients. After adjustment for possible confounding factors, plasma VEGF value was an independent predictor of poor functional outcome in CE patients.

Conclusions

Although plasma VEGF value increases immediately after the stroke onset equally in all stroke subtypes, its significance in functional outcome may be different among the stroke subtypes.

Are higher total serum cholesterol levels associated with better long-term motor function after ischemic stroke?

OBJECTIVES

The objective of the study was to investigate the prognostic role of total cholesterol (TC) level on the long-term motor function after ischemic stroke.

METHODS

One hundred and fourteen patients with ischemic stroke were included and divided into high total cholesterol (HTC; TC ≧5.18 mmol/l or ≧200 mg/dl) and low total cholesterol (LTC; TC <5.18 mmol/l or <200 mg/dl) groups. The motor outcome was evaluated using the motor score of the Fugl-Meyer assessment (MFMA) at 2 weeks (baseline), 1, 3, 6, and 12 months after stroke. Prognostic factors on the repeated measurements of the MFMA were investigated using the linear mixed regression model.

RESULTS

The TC, basal ganglion lesion, baseline MFMA, first-time stroke, and follow-up time were identified as significant predictors for serial MFMA scores. The HTC group had higher MFMA scores than the LTC group by 2.72 units (95% confidence interval (CI): 0.17, 5.27, P = 0.037). An elevation of one unit of baseline MFMA led to a 0.86 increase (95% CI: 0.82, 0.90, P < 0.001) of subsequent MFMA scores. Subjects with basal ganglion lesions had lower MFMA scores by -3.55 (95% CI: -5.97, -1.14, P = 0.004).

DISCUSSION

Higher total cholesterol at the acute phase of ischemic stroke is a favorable prognostic factor for long-term motor function.

Pharmacological and clinical aspects of heme oxygenase

This review is intended to stimulate interest in the effect of increased expression of heme oxygenase-1 (HO-1) protein and increased levels of HO activity on normal and pathological states. The HO system includes the heme catabolic pathway, comprising HO and biliverdin reductase, and the products of heme degradation, carbon monoxide (CO), iron, and biliverdin/bilirubin. The role of the HO system in diabetes, inflammation, heart disease, hypertension, neurological disorders, transplantation, endotoxemia and other pathologies is a burgeoning area of research. This review focuses on the clinical potential of increased levels of HO-1 protein and HO activity to ameliorate tissue injury. The use of pharmacological and genetic probes to manipulate HO, leading to new insights into the complex relationship of the HO system with biological and pathological phenomena under investigation, is reviewed. This information is critical in both drug development and the implementation of clinical approaches to moderate and to alleviate the numerous chronic disorders in humans affected by perturbations in the HO system.

Classical conditioning of the rabbit's nictitating membrane response is a function of the duration of dietary cholesterol

Modifying dietary cholesterol may improve learning and memory but very high cholesterol can cause pathophysiology and death. Rabbits fed 2% cholesterol for 8, 10 or 12 weeks with 0.12 ppm copper added to distilled water and rabbits fed a normal diet without copper added to distilled water (0 weeks) were given a difficult trace classical conditioning task and an easy delay conditioning task pairing tone with corneal air puff. The majority of cholesterol-fed rabbits survived the deleterious effects of the diet but survival was an inverse function of the diet duration. Compared to controls, the level of classical conditioning and conditioning-specific reflex modification were an inverted "U"-shaped function of diet duration. Highest levels of responding occurred in rabbits on cholesterol for 10 weeks and trace conditioning was negatively correlated with the number of hippocampal beta-amyloid-positive neurons. Rabbits on the diet for 12 weeks responded at levels comparable to controls. The data provide support for the idea that dietary cholesterol may facilitate learning and memory but there is an eventual trade off with pathophysiological consequences of the diet.

High dietary cholesterol facilitates classical conditioning of the rabbit's nictitating membrane response

Studies have shown that modifying dietary cholesterol may improve learning and that serum cholesterol levels can be positively correlated with cognitive performance. Rabbits fed a 0, 0.5, 1 or 2% cholesterol diet for eight weeks and 0.12 ppm copper added to their drinking water received trace and then delay classical conditioning pairing tone with corneal air puff during which movement of the nictitating membrane (NM) across the eye was monitored. We found that the level of classical conditioning and conditioning-specific reflex modification (CRM) as well as the number of beta amyloid-labeled neurons in the cortex and hippocampus were a function of the concentration of cholesterol in the diet. The data provide support for the idea that dietary cholesterol may facilitate learning and memory.

Experimental selection for Drosophila survival in extremely low O(2) environment

BACKGROUND

Cellular hypoxia, if severe enough, results usually in injury or cell death. Our research in this area has focused on the molecular mechanisms underlying hypoxic tissue injury to explore strategies to prevent injury or enhance tolerance. The current experiments were designed to determine the genetic basis for adaptation to long term low O(2) environments.

METHODOLOGY/PRINCIPAL FINDINGS

With long term experimental selection over many generations, we obtained a Drosophila melanogaster strain that can live perpetually in extremely low, normally lethal, O(2) condition (as low as 4% O(2)). This strain shows a dramatic phenotypic divergence from controls, including a decreased recovery time from anoxic stupor, a higher rate of O(2 )consumption in hypoxic conditions, and a decreased body size and mass due to decreased cell number and size. Expression arrays showed that about 4% of the Drosophila genome altered in expression and about half of the alteration was down-regulation. The contribution of some altered transcripts to hypoxia tolerance was examined by testing the survival of available corresponding P-element insertions (and their excisions) under extremely low O(2) conditions. We found that down-regulation of several candidate genes including Best1, broad, CG7102, dunce, lin19-like and sec6 conferred severe hypoxia tolerance in Drosophila.

CONCLUSIONS/SIGNIFICANCE

We have identified a number of genes that play an important role in the survival of a selected Drosophila strain in extremely low O(2) conditions, selected by decreasing O(2) availability over many generations. Because of conservation of pathways, we believe that such genes are critical in hypoxia adaptation in physiological or pathological conditions not only in Drosophila but also in mammals.

Vascular endothelial growth factor improves recovery of sensorimotor and cognitive deficits after focal cerebral ischemia in the rat

Vascular endothelial growth factor (VEGF) is an angiogenesis factor with neurotrophic, neuroprotective and neuroproliferative effects. Depending on the dose, route and time of administration in relation to focal cerebral ischemia, VEGF can improve histological outcome and sensorimotor function in rodents. However, VEGF also increases vascular permeability, which can lead to brain edema and exacerbate ischemic brain injury. Thus, although VEGF is a candidate therapeutic for stroke and other ischemic disorders, its benefit relative to risk is uncertain. Considering that functional rather than histological measures of outcome are probably most relevant to therapeutic prospects for human stroke, we investigated the effects of VEGF after middle cerebral artery occlusion in rats using a series of behavioral tests. We report that VEGF improves functional outcome in ischemic rats, including both sensorimotor and cognitive deficiencies.