Tag Archives: human body

Cold virus ‘hides’ and multiplies in tonsils and adenoids, even in people without symptoms

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A new study has found that the virus responsible for the common cold can quietly persist in the human body, even in individuals who show no symptoms.

Researchers from the University of São Paulo in Brazil discovered that the rhinovirus can reside deep within the tonsils and adenoids—tissues located at the back of the throat—effectively using them as reservoirs. The study, based on samples from 293 children undergoing surgical removal of these tissues, revealed that the virus can infect key immune cells and remain there undetected for extended periods.

Unlike its typical behaviour—where it infects the surface lining of the nose and throat, multiplies rapidly, and is cleared by the immune system within a week—the virus was found to penetrate deeper layers of tissue. There, it infects long-lived immune cells such as B lymphocytes and CD4 T cells, allowing it to persist without destroying them.

This hidden presence may help explain why cold outbreaks often occur shortly after schools reopen. Children carrying the virus without symptoms can unknowingly transmit it to others in close, indoor environments, triggering wider infections.

The study further found that nearly half of the children tested carried the virus in at least one site—tonsils, adenoids, or nasal secretions—even though they were symptom-free at the time of surgery. Evidence also suggested that the virus remained active and capable of spreading.

Researchers say these lymphoid tissues may act as a “virus reservoir,” potentially supporting long-term immune memory. However, this persistence could also have downsides. In children with asthma, for instance, lingering viruses may trigger inflammation and worsen symptoms.

The findings also raise concerns about diagnostic accuracy. Detecting rhinovirus in throat swabs may not always indicate an active infection, as the virus could be lingering from a previous illness. This could complicate treatment decisions, particularly in respiratory cases.

Scientists are now exploring whether such dormant viruses could reactivate in patients with weakened immune systems, potentially leading to complications without any new external exposure.

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A folding sheet robot that can deliver drugs with precision is here

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A new magnetorheological fluid-based soft robot created by the researchers includes reversible t robot with reversible gastrointestinal tract medical applications.

Millions of people around the world are infected with gastrointestinal tract diseases and the conventional drug delivery system lacks high targeting capacity with chances of side effects of systemic drug delivery. The development of magnetic soft robots has become an innovative solution to minimally invasive medical procedures, due to their miniaturity, untethered locomotion and their agile movements. Nonetheless, the current magnetic soft robots have severe constraints of multi-angle folding, real time reconfigurable magnetization, and compliance with the irregular and constrained gastrointestinal cavity, which are the barriers to clinical use of targeted drug delivery.

In order to solve these problems, a research team, comprising of researchers at China University of Mining and Technology, Soochow University, RWTH Aachen University and the University of Oxford created a magnetic soft sheet robot with magnetorheological fluids. The robot takes the form of a four-layered fully-soft sheet, which consists of upper and bottom layers of linear low-density polyethylene surface, a core layer of magnetorheological fluids and a polyamide nylon mesh support layer. The robot is non-magnetized in zero magnetic field, weighing 0.55 g (a weight of 30 mm in length, 10 mm in width, 1.5 mm in thickness), which is small (30 mm in length, 10 mm in width, 1.5 mm in thickness), which removes unwanted magnetic interference in the human body.

The main novelty of such robot is the magnetization, which can be reconfigured in real time, and the performance by reversible folding. The magnetic particle chains along the magnetic field direction can be generated by the internal magnetorheological fluids within milliseconds under the external magnetic and the magnetization direction can be dynamically readjusted using the spatial magnetic field. Propelled by a 5 degree of freedom magnetic field platform, the robot can be folded to a one third size of the original to move in slender intestinal tracts and unfolded to a large surface area to move in a stable fashion within the stomach cavity-achieving the flexible adaptation to the different spatial sizes of the gastrointestinal tract.

  • The research group used the fabrication of five prototypes of the soft sheet robot with varying magnetorheological fluid densities (3.0 g/mL to 4.2 g/mL) and a series of motion performance tests under various environments.
  • The robot was found to have a stable flip, steering and folding motion on smooth surfaces, on flexible fluff surfaces and on slope surfaces and also in environment with underwater. It was also able to maintain consistent performance of movement even under load (carrying biodegradable hydrogel drugs with a mass of 0.15 g, which is about 30 percent of the own mass of the robot).
  • The ex vivo porcine stomach experiments, which mimicked the human gastrointestinal environment, were done to have critical validation. The robot was able to reach any predetermined location in the porcine stomach in an average of 5 minutes and firmly secured to the point of drug release with the loaded hydrogel drugs dissolving within 30 minutes to create localized targeted therapy in 10 repetitions.
  • Also, the ultrasonic detection technology (Voluson E10), was able to trace real-time movements of the robot in closed gastric cavity, which proved traceable and controllable in closed biological environments- a technical assurance in monitoring robots in clinical practices.

The biocompatibility tests continued to confirm the safety of the robot when used in human body: the robot was immersed in the simulated gastric juice (pH 1.2) and intestinal juice (pH 6.8) at 37degC after 24 hours and no rupture of its surfaces, expansion of its volume and deformation of the shape were observed. It was revealed that no exceeding of the safety levels was detected in the extract solutions by the heavy metals and harmful substances and no bacterial colonies were obtained in the tests related to the growth of microbial cultures, which indicates the biocompatibility and non-toxicity of the robot in the gastrointestinal tract environment.

The research team observed that the magnetic soft sheet robot has overcome the technical bottlenecks of the conventional magnetic soft robots in terms of folding capability and magnetization ability. It has the benefit of untethered drive, complete soft-structure, and excellent targeting precision, which render it the best noninvasive medical device to deliver drugs to the gastrointestinal tract.

 

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