Online chromatic and scale-space microvessel-tracing analysis for transmitted light optical images.

Limited contrast in transmitted light optical images from intravital microscopy is problematic for analysing tumour vascular morphology. Moreover, in some cases, changes in vasculature are visible to a human observer but are not easy to quantify. In this paper two online algorithms are presented: scale-space vessel tracing and chromatic decomposition for analysis of the vasculature of SW1222 human colorectal carcinoma xenografts growing in dorsal skin-fold "window" chambers in mice. Transmitted light optical images of tumours were obtained from mice treated with the tumour vascular disrupting agent, combretastatin-A-4-phosphate (CA4P), or saline. The tracing algorithm was validated against hand-traced vessels with accurate results. The measurements extracted with the algorithms confirmed the known effects of CA4P on tumour vascular topology. Furthermore, changes in the chromaticity suggest a deoxygenation of the blood with a recovery to initial levels in CA4P-treated tumours relative to the controls. The algorithms can be freely applied to other studies through the CAIMAN website (CAncer IMage ANalysis: http://www.caiman.org.uk).

Hydroxyurea for primary stroke prevention in children with sickle cell anaemia in Nigeria (SPRING): a double-blind, multicentre, randomised, phase 3 trial.

BACKGROUND: In high-income countries, standard care for primary stroke prevention in children with sickle cell anaemia and abnormal transcranial Doppler velocities results in a 92% relative risk reduction of strokes but mandates initial monthly blood transfusion. In Africa, where regular blood transfusion is not feasible for most children, we tested the hypothesis that initial moderate-dose compared with low-dose hydroxyurea decreases the incidence of strokes for children with abnormal transcranial Doppler velocities. METHODS: SPRING is a double-blind, parallel-group, randomised, controlled, phase 3 trial of children aged 5-12 years with sickle cell anaemia with abnormal transcranial Doppler velocities conducted at three teaching hospitals in Nigeria. For randomisation, we used a permuted block allocation scheme with block sizes of four, stratified by sex and site. Allocation was concealed from all but the pharmacists and statisticians. Participants were assigned in a 1:1 ratio to low-dose (10 mg/kg per day) or moderate-dose (20 mg/kg per day) oral hydroxyurea taken once daily with monthly clinical evaluation and laboratory monitoring. The primary outcome was initial stroke or transient ischaemic attack, centrally adjudicated. The secondary outcome was all-cause hospitalisation. We used the intention-to-treat population for data analysis. The trial was stopped early for futility after a planned minimum follow-up of 3·0 years to follow-up for participants. This trial was registered with ClinicalTrials.gov, number NCT02560935. FINDINGS: Between Aug 2, 2016, and June 14, 2018, 220 participants (median age 7·2 years [IQR 5·5-8·9]; 114 [52%] female) were randomly allocated and followed for a median of 2·4 years (IQR 2·0-2·8). All participants were Nigerian and were from the following ethnic groups: 179 (82%) people were Hausa, 25 (11%) were Fulani, and 16 (7%) identified as another ethnicity. In the low-dose hydroxyurea group, three (3%) of 109 participants had strokes, with an incidence rate of 1·19 per 100 person-years and in the moderate-dose hydroxyurea group five (5%) of 111 had strokes with an incidence rate of 1·92 per 100 person-years (incidence rate ratio 0·62 [95% CI 0·10-3·20], p=0·77). The incidence rate ratio of hospitalisation for any reason was 1·71 (95% CI 1·15-2·57, p=0·0071), with higher incidence rates per 100 person-years in the low-dose group versus the moderate-dose group (27·43 vs 16·08). No participant had hydroxyurea treatment stopped for myelosuppression. INTERPRETATION: Compared with low-dose hydroxyurea therapy, participants treated with moderate-dose hydroxyurea had no difference in the stroke incidence rate. However, secondary analyses suggest that the moderate-dose group could lower incidence rates for all-cause hospitalisations. These findings provide an evidence-based guideline for the use of low-dose hydroxyurea therapy for children with sickle cell anaemia at risk of stroke. FUNDING: National Institute of Neurological Disorders and Stroke.

An elevated 8-isoprostaglandin F2 alpha (8-iso-PGF2α) in COVID-19 subjects co-infected with malaria.

INTRODUCTION: the most recently discovered severe acute respiratory syndrome Coronavirus 2 (SARS-COV-2) that causes COVID-19, subjected the entire world in turmoil health-wise and economically. With higher burden of malaria in Nigeria and other sub-Saharan African countries coupled with fragile healthcare system and delivery, these may pose a threat in the diagnosis and management of COVID-19 patients co-infected with malaria. Free radicals have been implicated in the progression and pathogenesis of malaria and COVID-19 through Fenton's reaction and cytokine storm respectively. METHODS: the current research comprises of seventy-four (74) participants; 20 apparently healthy controls and 54 COVID-19 patients (34 among which were co-infected with malaria). Serum levels of 8-iso PGF2α and Alphatocopherol were determined among the study participants using ELISA technique and colorimetric assay, respectively. RESULTS: results revealed statistically significant elevation of 8-iso PGF2α in COVID-19 patients co-infected with malaria compared to COVID-19 patients only, and this may be due to increase production of free radicals. Furthermore, a significant decrease of Alphatocopherol was observed in COVID-19 co-infected with malaria compared to COVID-19 patients due to increase utilization of antioxidants in counterbalancing the negative effect of free radicals generated. CONCLUSION: conclusively, SARS-COV-2 patients co-infected with malaria might be predisposed to oxidative stress and low Alphatocopherol. The increase in oxidative stress is proportional to malaria parasite density and inversely related to Alphatocopherol levels. This implies that oxidative stress is notably higher and such patients may have a severer form of the COVID-19. Increased 8-iso-PGF2α in co-infection and decreased alphatocopherol levels can reflect the severity and adverse outcomes compared to COVID-19 naïve because of their tremendous involvement in the pathogenesis and progression of diseases.

Flow-mediated vascular remodeling in hypertension: relation to hemodyamics.

BACKGROUND AND PURPOSE: Changes in shear and medial wall stress induced by blood flow contribute to vascular remodeling, but details of these relations remain undefined. We hypothesized that remodeling has a strong genetic component and that phenotypic responses to hemodynamic stress will differ among rat strains. Here, we characterized phenotypic traits related to carotid remodeling in the 2 rat strains that we previously showed the greatest difference in shear stress regulation: Genetically Hypertensive (GH) and Brown Norway (BN) rat strains. METHODS: Left internal and external carotid arteries were ligated and blood flow was reduced in the left common (LCA) by 90% and increased in the right common carotid artery (RCA) by 60%. Rats were studied for up to 28 days after flow modification and carotid outer diameters were measured in vivo, and wall and luminal components by histomorphometry, to obtain indices of remodeling. Blood flow and pressure measurements were made at corresponding time points. RESULTS: By day 28, remodeling in the GH was greater in response to high flow than in BN, and shear stress was normalized. In contrast, remodeling in the BN was greater in the low flow LCA than in GH. Media stress was greater in GH than BN for any value of carotid shear stress and remained relatively unchanged in low flow, but markedly increased in high flow remodeling. Importantly, pressure was not a major determinant of flow remodeling in these conditions. CONCLUSIONS: There are key differences in the ability of carotids in GH and BN rats to adhere to hemodynamic laws during vascular remodeling. GH rats exhibit intact regulatory mechanisms for increased, but not reduced, shear stress. Moreover, the ability to maintain physiological shear and media stresses during vascular remodeling in response to modified flow appears to be intrinsically "genetically" determined.

Shear stress is differentially regulated among inbred rat strains.

An important compensatory response to atherosclerosis is vascular remodeling, with maintenance of vessel lumen diameter and shear stress. Both hemodynamic and environmental factors contribute to vascular remodeling and shear stress regulation, and the process is probably also influenced by genetic factors. To establish an animal model for genetic analysis of shear stress regulation and vascular remodeling, we studied the effects of chronic flow alteration in four inbred rat strains. By ligating the left internal and external carotid arteries, we caused a approximately 90% decrease in left common carotid blood flow and a approximately 50% increase in right (contralateral) common carotid flow. After 4 weeks of altered flow, there were significant interstrain differences with respect to the change in carotid outer diameter (OD), the relationship between flow and shear stress, and the extent to which shear stress was normalized. Genetically hypertensive rats (GH) exhibited the greatest reduction in shear stress in response to increased flow, stroke-prone spontaneously hypertensive rats (SHR-SP) exhibited a smaller response, and Brown Norway (BN) rats exhibited the smallest response. SHR-SP and GH also differed significantly in outward remodeling (defined as an increase in lumen and vessel diameter) in increased flow arteries. In response to decreased flow, BN rats exhibited the smallest reduction in shear stress. These findings demonstrate significant strain-dependent differences in shear stress regulation and vascular remodeling in response to altered flow. This study emphasizes the important role of genetic factors in vascular remodeling and suggests that genetic analysis of these strains will provide novel insights into the underlying mechanisms.

Ethylmalonic encephalopathy-report of two cases.

Ethylmalonic encephalopathy is a rare metabolic disease presenting in infancy with developmental delay, acrocyanosis, petechiae, chronic diarrhea and early death. The biochemical characteristics of this autosomal recessive disease are urinary organic acid abnormalities. Recently it has been found to be caused by mutations in the ETHE1 gene, located on Ch19q13. Only about 30 patients have been reported, and we describe two additional cases. The first patient showed a typical clinical picture and biochemical abnormalities, with additional atypical clinical features. Neuroimaging studies showed extensive changes. A new homozygous mutation in exon 3 of the ETHE1 gene was found. The second patient was not investigated genetically; however besides the typical clinical picture and biochemical profile he was found to have cytochrome C oxidase deficiency.

Comparison of simultaneous measurements of blood pressure by tail-cuff and carotid arterial methods in conscious spontaneously hypertensive and Wistar-Kyoto rats.

We determined the validity of systolic blood pressure (SBP) measured by tail-cuff blood pressure (TCBP) with direct intra-arterial measurements. In conscious, restrained Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR), carotid artery (CA) BP and TCBP were simultaneously measured. In both WKY and SHR strains, highly significant correlations between CABP and TCBP were found and Bland-Altman analyses showed no bias when the two methods were compared. The limits of agreement between CABP and TCBP in WKY and SHR were wide and reproducibility of pressure measurements by either technique was poor, with some evidence for strain-dependent differences. Pressure measurements made over short time frames, however, showed close agreement between CABP and TCBP. Acetylcholine-induced reductions in pressure were equivalently detected by tail-cuff and direct arterial measurement in both strains but angiotensin II-induced pressure elevations were over-estimated by tail-cuff in SHR. Telemetered SBP measurements in conscious rats were highly variable in a strain-dependent manner.

Sex-specific differences in cerebral arterial myogenic tone in hypertensive and normotensive rats.

Cerebral blood flow (CBF) is maintained constant despite changes in systemic blood pressure (BP) through multiple mechanisms of autoregulation such as vascular myogenic reactivity. Our aim was to determine myogenic characteristics of cannulated middle cerebral arteries (MCA) in male and female stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto rats (WKY) at 12 wk of age under pressurised no-flow conditions. MCA pressure-diameter relationships (20-200 mmHg) were constructed in active (with calcium) and passive (without calcium) conditions, and myogenic and mechanical properties were determined. Myogenic reactivity in WKY (P < 0.05) and SHRSP (P < 0.05) males was impaired compared with their female counterparts. Comparison of SHRSP with WKY in males revealed similar myogenic reactivity, but in females SHRSP exhibited augmented myogenic reactivity (P < 0.05). In both sexes, myogenic tone yielded at lower pressure in SHRSP compared with WKY vessels (120-140 vs. 140-180 mmHg). Stress-strain relationships and elastic moduli in WKY rats showed that vessels were stiffer in females than in males. Conversely, in SHRSP, male vessels were stiffer than female vessels. Comparison of strains in males indicated that stiffness was increased in SHRSP compared with WKY vessels, whereas the converse was observed in females. These findings demonstrate that MCA myogenic and distensibility characteristics exhibit significant sex- and strain-dependent differences. Inappropriate myogenic adaptation and augmented vascular stiffness, particularly in male SHRSP, are potential limiting factors in blood flow autoregulation and may increase the predisposition for stroke-related cerebrovascular events.