Archive for month: August, 2020

Following ischemic stroke, the integrity of the blood-brain barrier (BBB), which prevents harmful substances such as inflammatory molecules from entering the brain, can be impaired in cerebral areas distant from initial ischemic insult. This disruptive condition, known as diaschisis, can lead to chronic post-stroke deficits, University of South Florida researchers report.
In experiments using laboratory rats modelling ischemic stroke, USF investigators studied the consequences of the compromised BBB at the chronic post-stroke stage.
‘Following ischemic stroke, the pathological changes in remote areas of the brain likely contribute to chronic deficits,’ said neuroscientist and study lead author Svitlana Garbuzova-Davis, PhD, associate professor in the USF Health Department of Neurosurgery and Brain Repair. ‘These changes are often related to the loss of integrity of the BBB, a condition that should be considered in the development of strategies for treating stroke and its long-term effects.’
Edward Haller of the USF Department of Integrative Biology, the co-author who performed electron microscopy and contributed to image analysis, emphasised that ‘major BBB damage was found in endothelial and pericyte cells, leading to capillary leakage in both brain hemispheres.’ These findings were essential in demonstrating persistence of microvascular alterations in chronic ischemic stroke.
While acute stroke is life-threatening, the authors point out that survivors often suffer insufficient blood flow to many parts of the brain that can contribute to persistent damage and disability. Their previous investigation of subacute ischemic stroke showed far-reaching microvascular damage even in areas of the brain opposite from the initial stroke injury. While most studies of stroke and the BBB explore the acute phase of stroke and its effect on the blood-brain barrier, the present study revealed the longer-term effects in various parts of the brain.
The pathologic processes of stroke-induced vascular injury tend to occur in a ‘time-dependent manner,’ and can be separated into acute (minutes to hours), subacute (hours to days), and chronic (days to months). BBB incompetence during post-stroke changes is well-documented, with some studies showing the BBB opening can last up to four to five days after stroke. This suggests that harmful substances entering the brain during this prolonged BBB leakage might increase post-ischemic brain injury.
In this study, the researchers used laboratory rats modelling ischemic stroke and observed injury not only in the primary area of the stroke, but also in remote areas, where persistent BBB damage could cause chronic loss of competence.
The primary focus for therapy development could be restoring endothelial and/or astrocytic integrity towards BBB repair, which may be ‘beneficial for many chronic stroke patients,’ senior authors Cesar V. Borlongan and Paul R. Sanberg suggest. The researchers also recommend that cell therapy might be used to replace damaged endothelial cells.
‘A combination of cell therapy and the inhibition of inflammatory factors crossing the blood-brain barrier may be a beneficial treatment for stroke,’ Garbuzova-Davis said. University of South Florida

Plasma medicine is a new and rapidly developing area of medical technology. Specifically, understanding the interaction of so-called atmospheric pressure plasma jets with biological tissues could help to use them in medical practice. Under the supervision of Sylwia Ptasinska from the University of Notre Dame, in Indiana, USA, Xu Han and colleagues conducted a quantitative and qualitative study of the different types of DNA damage induced by atmospheric pressure plasma exposure. This approach, they hope, could ultimately lead to devising alternative tools for cancer therapy as well as applications in hospital hygiene, dental care, skin diseases, antifungal care, chronic wounds and cosmetics treatments.
To investigate the DNA damage from the so-called non-thermal Atmospheric Pressure Plasma Jet (APPJ), the team adopted a common technique used in biochemistry, called agarose gel electrophoresis. They studied the nature and level of DNA damage by plasma species, so-called reactive radicals, under two different conditions of the helium plasma source with different parameters of electric pulses.
They also identified the effect of water on DNA damage. To do so, they examined the role of reactive radicals involved in DNA damage processes occurring in an aqueous environment. They then compared them to previous results obtained in dry DNA samples.
The next step would involve investigating plasma made from helium mixtures with different molecular ratios of other gases, such as oxygen, nitrous oxide, carbon dioxide and steam, under different plasma source conditions. The addition of another gas is expected to increase the level of radical species, such as reactive oxygen species and reactive nitrogen species, known to produce severe DNA damage. These could, ultimately, help to destroy cancerous tumour cells. Springer

Nanoparticles have a great deal of potential in medicine: for diagnostics, as a vehicle for active substances or a tool to kill off tumours using heat. ETH Zurich researchers have now developed particles that are relatively easy to produce and have a wide range of applications.
If you put your hand over a switched-on torch in the dark, it appears to glow red. This is because long-wavelength red light beams penetrate human tissue more effectively than short-wavelength blue light. ETH Zurich researchers exploit this fact in a new kind of nanoparticles: so-called plasmonic particles, which heat up when they absorb near-infrared light. This could enable them to kill tumour tissue with heat, for instance.

Gold is a popular material for nanoparticles used therapeutically, as it is well tolerated and does not usually trigger any undesirable reactions. In the characteristic ball or sphere shape of nanoparticles, however, gold does not have the necessary properties to work as a plasmonic particle that absorbs sufficiently in the near-infrared spectrum of light to heat up. To do so, it needs to be moulded into a special shape, such as a rod or shell, so that the gold atoms adopt a configuration that starts absorbing near-infrared light, thereby generating heat. Producing such nanorods or nanoshells in sufficient amounts, however, is complex and expensive.
A team of researchers headed by Sotiris Pratsinis, Professor of Particle Technology at ETH Zurich, has now discovered a trick to manufacture plasmonic gold particles in large amounts. They used their existing know-how on plasmonic nanoparticles and made sphere-shaped gold nanoparticles that display the desired near-infrared plasmonic properties by allowing them to be aggregated. Each particle is coated with a silicon dioxide layer beforehand, which acts as a placeholder between the individual spheres in the aggregate. Through the precisely defined distance between several gold particles, the researchers transform the particles into a configuration that absorbs near-infrared light and thus generates heat.

‘The silicon dioxide shell has another advantage’, explains Georgios Sotiriou, first author on the study and, until recently, a postdoc in Pratsinis

Obese people who have stomach surgery to help them lose weight will halve their risk of heart attack according to new research from a team of doctors at the University of East Anglia, University of Manchester and University of Aberdeen.

The procedures, known as bariatric surgery, involve techniques such as gastric banding, which are available on the National Health Service (NHS), UK for selected patients.

New research published today in the International Journal of Cardiology reviewed data from 14 studies involving more than 29,000 patients who underwent bariatric surgery. It reveals that death rates were reduced by 40 per cent, and that heart attacks in particular were reduced by half