Fractal analysis approach in the characterisation of cerebrovascular complexity in asymptomatic cerebral small vessel disease

Cerebral small vessel disease (CSVD) refers to a spectrum of clinical and neuroimaging findings caused by pathological damage of small vessels of the cerebral parenchyma. Cerebral white matter hyperintensity (WMH) is one of the commonest neuroimaging findings of CSVD. Often, CSVD is diagnosed once the symptoms developed. Detection of the underlying vascular structural changes might facilitate early disease risk stratification and disease monitoring as vascular alteration precedes cerebral parenchymal injury. Of interest, fractal analysis allows us to quantitatively measure the complexity of the cerebral vascular structure in terms of fractal dimension (Df). The cerebral vascular Df changes are indicative of inefficient tissues perfusion which renders the cerebral parenchyma vulnerable to damage. The aim of this study is to explore a novel vascular neuroimaging marker of asymptomatic CSVD by characterising the complexity of the circle of Willis (CoW) and its tributaries as measured by Df. An exploratory cross-sectional study was conducted involving 22 subjects of age between 25 - 75 years old with low to moderate QRISK2 score who underwent magnetic resonance imaging/angiography (MRI/MRA) examination. These subjects presented with or without WMH. The cerebral vascular complexity of the MRA image was characterised using Df. The cerebral vascular Df was compared between asymptomatic subjects with (WMH+; n = 8) and without cerebral WMH (WMH-; n = 14). Furthermore, cerebral vascular Df was also compared between asymptomatic subjects with both CSVD risk factors and cerebral WMH (RF+ & WMH+; n = 6), subjects with CSVD risk factors only (RF+ & WMH-; n = 5), and subjects without both CSVD risk factors and cerebral WMH (RF- & WMH-; n = 9). Simple linear regression (SLR) was performed between QRISK2 score and cerebral vascular Df. Mean cerebral vascular Df was significantly lower in the WMH+ group than WMH- group. Moreover, the mean cerebral vascular Df of the RF+ & WMH- and RF+ & WMH+ groups were significantly lower than RF- & WMH- group. The SLR model had indicated that increased QRISK2 score significantly predicted reduction in cerebral vascular Df. The cerebral vascular Df was reduced in the subjects with CSVD risk factors and asymptomatic CSVD subjects with WMH. The SLR model had indicated that QRISK2 score significantly predicted cerebral vascular Df. The results indicate that cerebral vascular Df is a promising biomarker of asymptomatic CSVD subjects with WMH. Larger-scaled studies are required to explore its potential in a broader population setting

Reduced cerebral vascular fractal dimension among asymptomatic individuals as a potential biomarker for cerebral small vessel disease

Cerebral small vessel disease is a neurological disease frequently found in the elderly and detected on neuroimaging, often as an incidental finding. White matter hyperintensity is one of the most commonly reported neuroimaging markers of CSVD and is linked with an increased risk of future stroke and vascular dementia. Recent attention has focused on the search of CSVD biomarkers. The objective of this study is to explore the potential of fractal dimension as a vascular neuroimaging marker in asymptomatic CSVD with low WMH burden. Df is an index that measures the complexity of a self-similar and irregular structure such as circle of Willis and its tributaries. This exploratory cross-sectional study involved 22 neurologically asymptomatic adult subjects (42 ± 12 years old; 68% female) with low to moderate 10-year cardiovascular disease risk prediction score (QRISK2 score) who underwent magnetic resonance imaging/angiography (MRI/MRA) brain scan. Based on the MRI findings, subjects were divided into two groups: subjects with low WMH burden and no WMH burden, (WMH+; n = 8) and (WMH−; n = 14) respectively. Maximum intensity projection image was constructed from the 3D time-of-flight (TOF) MRA. The complexity of the CoW and its tributaries observed in the MIP image was characterised using Df. The Df of the CoW and its tributaries, i.e., Df (w) was significantly lower in the WMH+ group (1.5172 ± 0.0248) as compared to WMH− (1.5653 ± 0.0304, p = 0.001). There was a significant inverse relationship between the QRISK2 risk score and Df (w), (rs = −.656, p = 0.001). Df (w) is a promising, non-invasive vascular neuroimaging marker for asymptomatic CSVD with WMH. Further study with multi-centre and long-term follow-up is warranted to explore its potential as a biomarker in CSVD and correlation with clinical sequalae of CSVD

Our students are they healthy?

Background: Cardiovascular disease remains the leading cause of death worldwide. Recent studies showed an alarming trend for cardiovascular risk profile among young adults. Among the many risk factors of cardiovascular disease, cholesterol is considered as the required risk factor. This study is part of a clinical trial approved by IIUM ethical committee. Methodology: A total of 63 male subjects came to join the study. After a briefing session, only 33 subjects agreed to enroll and were screened. Each subject was assessed by a physician. Their weight, height, blood pressure (supine and upright), heart rate, and ECG were taken. Blood samples were withdrawn from antecubital vein for fasting lipid profile. Subjects were asked to fast overnight (10 hours) prior to screening. Result: Their mean (SD) age was 22.9 (2.2) years, their mean (SD) BMI was 22.7 (3.2), their supine systolic (SBP) and diastolic (DBP) blood pressure were 111.9 (9.8)mmHg and 68.0 (6.5)mmHg, their standing SBP and DBP were 117.6 (9.8)mmHg and 74.5 (7.1)mmHg, the total cholesterol was 4.8 (0.7)mmol/L, HDL was 1.3 (0.2)mmol/L, LDL was 3.0 (0.7)mmol/L and triglyceride was 1 (0.7)mmol/L. the total cholesterol level in this study’s participants was significantly higher than in general Malaysian population aged 30-40 (4.8 vs. 4.5)(p<0.05). The proportion of study participants with hypercholesterolemia is 28.1% (26.6% in NHMS 2011). Conclusion: The total cholesterol levels among IIUM students in our study were significantly higher as compared to general Malaysian population aged 30-40 years

Timed pregnancy in rats: a simple and reliable approach in determining the stage of oestrous for non-histologists

There are a few approaches that enable us to time the pregnancy. Recent techniques had shown that observation of unstained smear is more practical than stained smear. However, with simple modifications, methylene blue dye staining technique can be a practical and reliable approach for non-histologists. 10 healthy fertile male and 30 female Sprague Dawley rats age 10 weeks old were acclimatized. At 12 weeks old, the oestrous cycle of the female rats were determined. Two to three drops of normal saline ( NaCl 0.90%) was flushed into the vagina for three times. One to two drops of the cells suspension was placed on the slide .The slide was dried with a hot plate. The cells suspension was treated with 0.1% methylene blue dye for 20 to 30 seconds. The surplus was removed from the slide by dipping in a container filled with slowly running tap water for three times. The slide can be immediately examined under the light microscope at 40x and 100x magnification. The four oestrous cycle stages namely proestrous, estrous, metestrous and diestrous were clearly identified with the methylene blue dye staining method. All 30 female rats were successfully impregnated. The methylene blue dye treatment can be done within 20-30 seconds, as compared to 45 minutes in previous study. The smear can be accurately observed by the beginners directly under the light microscope without the aid of histologists. The methylene blue dye stained smear is easy to interpret as the characteristics of the cells are well discernible, relatively inexpensive and doesn’t requires complex preparation

Cardiovascular risks profile in young non-smoker male IIUM students in Kuantan campus

Background: Cardiovascular disease remains the leading cause of death worldwide. Recent studies showed an alarming trend for cardiovascular risk profile among young adults. Among the many risk factors of cardiovascular disease, cholesterol is considered as the required risk factor. This study is part of a clinical trial approved by IIUM ethical committee. Methodology: A total of 63 male subjects came to join the study. After a briefing session, only 33 subjects agreed to enroll and were screened. Each subject was assessed by a physician. Their weight, height, blood pressure (supine and upright), heart rate, and ECG were taken. Blood samples were withdrawn from antecubital vein for fasting lipid profile. Subjects were asked to fast overnight (10 hours) prior to screening. Result: Their mean (SD) age was 22.9 (2.2) years, their mean (SD) BMI was 22.7 (3.2), their supine systolic (SBP) and diastolic (DBP) blood pressure were 111.9 (9.8)mmHg and 68.0 (6.5)mmHg, their standing SBP and DBP were 117.6 (9.8)mmHg and 74.5 (7.1)mmHg, the total cholesterol was 4.8 (0.7)mmol/L, HDL was 1.3 (0.2)mmol/L, LDL was 3.0 (0.7)mmol/L and triglyceride was 1 (0.7)mmol/L. the total cholesterol level in this study’s participants was significantly higher than in general Malaysian population aged 30-40 (4.8 vs. 4.5)(p<0.05). The proportion of study participants with hypercholesterolemia is 28.1% (26.6% in NHMS 2011). Conclusion: The total cholesterol levels among IIUM students in our study were significantly higher as compared to general Malaysian population aged 30-40 years

High perinatal sodium chloride exposure and blood pressure response to chronic high sodium challenge in adult rats

Background: An insult during a critical period of fetal development may result in increased risk for development of hypertension. Objective: This study aims at evaluating the effects of high maternal dietary sodium during pregnancy and lactation on their offspring’s blood pressure at 16 weeks upon 1 month of high dietary sodium challenge. Materials and methods: Normotensive female Sprague-Dawley rats were subjected to timed pregnancy. Pregnant rats were randomly divided into two groups and were fed normal-sodium diet (1.0%NaCl)(n=10) or high-sodium diet (3.0%NaCl) (n=10) during pregnancy and four weeks of lactation. The offspring were weaned at 4 weeks old, Thereafter, both groups were fed with NSD (1.0%NaCl) until 12 weeks old and then challenge with 3%NaCl diet for 4 weeks. Blood pressure was measured in the offsprings at 12 and 16 weeks old. Results: At 12 weeks old, the offspring’s systolic blood pressure (SBP) were significantly higher in HSD than NSD dams respectively (138.42mmHg±2.62 vs 127.27mmHg±2.00). Upon high-sodium challenge, at 16 weeks, the offspring’s SBP were significantly higher in HSD than NSD dams (143.04mmHg ±3.09 vs 131.45mmHg ±1.37). The offspring’s SBP of HSD dams were significantly greater at 16 weeks than at 12 weeks old respectively (143.04mmHg±3.09 vs 138.42mmHg±2.62). Similarly, the offspring SBP of NSD dams were significantly greater at 16 weeks than at 12 weeks old respectively (131.45mmHg ±1.37 vs 127.27mmHg ±2.00). No difference in the heart rate and food intake in both groups at 12 and 16 weeks. However, the body weight of the offspring HSD dams at 12 and 16 weeks are significantly different (389.73g±4.65 vs 443.77g±4.46 ). Similarly, the body weight of the offspring NSD dams at 12 and 16 weeks are also significantly different (384.79g±2.28 vs 434.55g±2.99). Conclusions: This suggests that there were no differences in offspring’s SBP response upon chronic high-sodium challenge in both HSD and NSD dams offspring. However, the offspring of HSD dams is at greater risk of developing hypertension than NSD dams

Perinatal programming of hypertension on exposure to high and low sodium chloride diet during pregnancy and lactation in Sprague-Dawley rats

Background: Adverse conditions in utero may lead to hypertension during in later life, however inconsistency of the result has been reported. Objective: This experiment aims at studying the effects of high and low maternal dietary sodium on their offspring’s blood pressure at 4 and 8 weeks. Materials and methods: Normotensive female rats were subjected to timed pregnancy. Pregnant rats were randomly divided into three groups and were fed either low-sodium diet (LSD) (0.145%NaCl) (n=10), normal-sodium diet (NSD) (1.0%NaCl) (n=10) or high-sodium diet (HSD) (3.0%NaCl)(n=10) during pregnancy and 4 weeks of lactation. The offsprings were weaned at 4 weeks old. Thereafter, all the three groups were fed with normal-sodium diet (1.0%NaCl) for another 4 weeks. Results: At 4 weeks old, the offsprings of HSD dams have significantly higher systolic blood pressure(SBP) compared to NSD group respectively (119.44mmHg ±1.8 vs 103.65mmHg ±0.92). There were no differences in the offspring’s SBP between NSD and LSD dams at 4 weeks old. Nevertheless, at 8 weeks old, the offspring’s of LSD dams have significantly higher SBP as compared to NSD dams (130.13±1.45mmHg vs 120.26mmHg±1.09). Similarly, at 8 weeks old, the offspring of HSD dams have significantly higher SBP as compared to NSD dams 131.06±1.49mmHg vs 120.26mmHg±1.09). The offspring’s heart rate, average food intake and body weight were similar between all the three groups at 4 and 8 weeks. Conclusions: This suggests that the offspring of both HSD and LSD have greater propensity to develop higher blood pressure and it is pertinent to consider optimum dietary sodium consumption during. pregnancy

Maternal blood pressure during gestation: the effects of low and high salt intake during pregnancy in normotensive sprague dawley rats

Background: Current evidence indicates mixed findings with regard to the effects of low and high maternal dietary salt intake during pregnancy on the maternal blood pressure. Objective: This study investigates the effects of low and high maternal dietary salt intake on the systolic blood pressure (SBP) at third week of gestation as compared to pre-pregnancy SBP. Methodology: 30 female Sprague Dawley normotensive rats were randomly assigned into three groups based on maternal dietary salt concentration; low salt (0.145% NaCl, n=10), normal salt (1.0% NaCl, n =10) and high salt (3.0% NaCl, n=10). Food intake and maternal body weight were recorded. SBP (mmHg) and heart rate (HR) were measured during pre-pregnancy and at third week of pregnancy by using non-invasive tail cuff blood pressure monitoring device. Results: There were comparable pre-pregnancy body weight, mean daily food intake, HR and SBP (116.5± 1.54 vs. 118.07 ± 1.22 vs. 115.83 ± 1.76) among LSD, NSD and HSD dams respectively. There were no significant differences in maternal mean daily food intake throughout the pregnancy, body weight at third week of gestation, HR and SBP (113.67± 2.74 vs. 111.37 ± 1.84 vs. 113.93 ± 2.11) at third week of gestation among LSD, NSD and HSD dams respectively. Statistically significant difference in term of SBP between pre-pregnancy and third week of gestation was only seen in the NSD dams (118.07 ±1.22 vs. 111.37 ±1.84) (P<0.05). HR was comparable among the three dams. Conclusion: The SBP decreases in all maternal groups at third week of gestation. However, within group analysis revealed that only NSD dams has significantly lower SBP at third week of gestation as compared to pre- pregnancy SBP. The decrement of SBP is more pronounced in the NSD dams depicting the possibilities of aberration in the expected cardiovascular physiological changes in LSD and HSD dams

Cerebral small vessel disease (CSVD) – lessons from the animal models

Cerebral small vessel disease (CSVD) refers to a spectrum of clinical and imaging findings resulting from pathological processes of various etiologies affecting cerebral arterioles, perforating arteries, capillaries, and venules. Unlike large vessels, it is a challenge to visualize small vessels in vivo, hence the difficulty to directly monitor the natural progression of the disease. CSVD might progress for many years during the early stage of the disease as it remains asymptomatic. Prevalent among elderly individuals, CSVD has been alarmingly reported as an important precursor of full-blown stroke and vascular dementia. Growing evidence has also shown a significant association between CSVD’s radiological manifestation with dementia and Alzheimer’s disease (AD) pathology. Although it remains contentious as to whether CSVD is a cause or sequelae of AD, it is not far-fetched to posit that effective therapeutic measures of CSVD would mitigate the overall burden of dementia. Nevertheless, the unifying theory on the pathomechanism of the disease remains elusive, hence the lack of effective therapeutic approaches. Thus, this chapter consolidates the contemporary insights from numerous experimental animal models of CSVD, to date: from the available experimental animal models of CSVD and its translational research value; the pathomechanical aspects of the disease; relevant aspects on systems biology; opportunities for early disease biomarkers; and finally, converging approaches for future therapeutic directions of CSVD