Categories
COVID-19

Long COVID (PASC)

By Suhani Khandelwal

Published 8:53 PM EST, Thurs April 22, 2021

Introduction

Post-Acute Sequelae of SARS-CoV-2 infection (PASC) or chronic COVID syndrome (CCS) and long-haul COVID or Long COVID. 

Recent studies have shown that COVID-19 has long term impacts on patients health, irrelevant of their age and medical history. For example, 35% of COVID  symptomatic adults with a positive outpatient test reported that even 2–3 weeks later they had not returned to their original state of health. Furthermore, 20% of the subjects between 18 to 34 years who were in good health, confirmed that some of the symptoms were prolonged. The US Center for Disease Control and Prevention (CDC) lists fatigue, shortness of breath, joint and chest pain as some of the long-term symptoms of COVID-19. Coronavirus long-haulers have also reported cognitive impairment, depression and headaches.  

The impact of SARS, however, continues as survivors’ exercise capacity and health status are significantly impaired for over 24 months. Another study revealed that 40% of people recovering from SARS still had chronic fatigue symptoms 3.5 years after being diagnosed. This may be because long COVID affects organs and can cause inflammation of the heart muscles, pulmonary issues, hair loss and skin rashes. However, we still do not know just how long these symptoms will persist or why they occur.

Reference Studies

At the Jin Yin-tan Hospital in Wuhan, over a span of 5 months, 1733 patients undertook a series of symptom questionnaires, physical examinations, and a six-minute walking test to study the long term impact of COVID. In it, 63% of subjects reported fatigue or muscle weakness and 26% had sleep difficulties. In addition, 23% of participants experienced anxiety or depression. Severely ill patients had significantly impaired pulmonary diffusion capacities, abnormal chest imaging manifestations, and had the longest recovery period. Furthermore, the decline of neutralising antibodies raises concern for severe acute respiratory syndrome coronavirus 2 re-infection.

As far as researchers know now, there is no one type of person who is more likely to suffer from long-term COVID-19 symptoms and issues, though some doctors say they are seeing far more females showing such symptoms. Ryan Hurt, an internist who leads post-COVID-19 syndrome research at the Mayo Clinic, said that even though only 10% of the approximately 20,000 COVID positive patients are considered long-haulers at the clinic, 60-80% of them are women.

Organ damage caused by COVID-19

Although COVID-19 is seen as a disease that primarily affects the lungs, it can damage many other organs, increasing the risk of long-term health problems. Organs that may be affected by COVID-19 include:

  • Heart- Imaging tests taken months after recovery from COVID-19 have shown lasting damage to the heart muscles, even in people who only experienced mild COVID-19 symptoms. Increasing the risk of heart failure and other heart diseases in the future.
  • Lungs- The type of pneumonia often associated with COVID-19 can cause long-standing damage to the tiny air sacs (alveoli) in the lungs. The resulting scar tissue can lead to long-term breathing problems.
  • Brain- Strokes, seizures and Guillain-Barre syndrome, a condition that causes temporary paralysis, have also been associated with COVID. Increase the risk of developing Parkinson’s disease and Alzheimer’s disease.

Blood clots and blood vessel problems

COVID-19 can make blood cells more likely to clump up and form clots. While large clots can cause heart attacks and strokes, much of the heart damage caused by COVID-19 is believed to stem from small clots blocking capillaries in the heart.

Other parts of the body affected by blood clots include the lungs, legs, liver and kidneys. COVID-19 can also weaken blood vessels and cause them to leak, contributing to potentially long-lasting problems with the liver and kidneys.

Problems with mood and fatigue

People who have severe symptoms of COVID-19 often have to be treated in a hospital’s intensive care unit and are often put on ventilators. Simply surviving this experience can make a person more likely to later develop post-traumatic stress syndrome, depression and anxiety.

Because it’s difficult to predict long-term outcomes from the new COVID-19 virus, scientists are looking at the long-term effects seen in related viruses, such as the virus that causes severe acute respiratory syndrome (SARS).

Many people who have recovered from SARS have gone on to develop chronic fatigue syndrome, a complex disorder characterized by extreme fatigue that worsens with physical or mental activity but doesn’t improve with rest. The same may be true for people who have had COVID-19.

Many long-term COVID-19 effects still unknown

Much is still unknown about how COVID-19 will affect people over time. However, researchers recommend that doctors closely monitor people who have had COVID-19 to see how their organs are functioning after recovery. Many large medical centres are opening specialized clinics to provide care for people who have persistent symptoms or related illnesses after they recover from COVID-19.

It’s important to remember that most people who have COVID-19 recover quickly. But the potentially long-lasting problems from COVID-19 make it even more important to reduce the spread of the disease by following precautions such as wearing masks, avoiding crowds and keeping hands clean.

Suhani Khandelwal, Youth Medical Journal 2021

References

https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)32656-8/fulltext

https://www.nature.com/articles/d41586-021-00586-y

https://www.webmd.com/lung/what-is-long-covid-pasc

https://theconversation.com/how-many-people-get-long-covid-and-who-is-most-at-risk-154331

https://www.mayoclinic.org/diseases-conditions/coronavirus/in-depth/coronavirus-long-term-effects/art-20490351

https://www.who.int/docs/default-source/coronaviruse/risk-comms-updates/update-36-long-term-symptoms.pdf?sfvrsn=5d3789a6_2

Categories
Biomedical Research

The Future of Genetic Engineering

By Suhani Khandelwal

Published 10:56 PM EST, Sun March 21, 2021

Can Genetic Engineering Save Our Planet's Biodiversity? | College of  Natural Resources News

Introduction

Genetic engineering is the process of using recombinant DNA (rDNA) technology to alter the genetic makeup of an organism. Conventionally, humans have manipulated genomes indirectly by controlling breeding and selecting offspring with desired traits. Genetic engineering involves the direct manipulation of one or more genes. Most often, a gene from another species is added to an organism’s genome to give it the desired phenotype.

Recombinant DNA technology started with pretty simple things like cloning very small pieces of DNA and growing them into bacteria and has now evolved into a massive field where whole genomes can be cloned and moved from cell to cell, to cell-using variations of techniques that all would come under genetic engineering as a very broad definition.

New genetic technologies are exhilarating and terrifying. Society might successfully overcome diseases by tweaking individual genomes or selecting specific embryos to avoid health problems. But it may also give rise to “super-humans” who are optimized for certain characteristics (like intelligence or looks) and exacerbate inequalities and extreme discrimination in society.

How It’s Done: CRISPR

CRISPR (pronounced “crisper”) is shorthand for “CRISPR-Cas9.” CRISPRs are specialized stretches of DNA. The protein Cas9 (or “CRISPR-associated”) is an enzyme that acts like a pair of molecular scissors, capable of cutting strands of DNA.

Improving Gene Editing by Promoting Error-free Repair of CRISPR/Cas9-cut  DNA | Technology Networks

CRISPR technology is a simple yet powerful tool for editing genomes. It allows researchers to easily alter DNA sequences and modify gene function. Its many potential applications include correcting genetic defects, treating and preventing the spread of diseases, and improving crops. However, its future of great promise also raises ethical concerns.

CRISPR technology was adapted from the natural defense mechanisms of bacteria and archaea (the domain of single-celled microorganisms). These organisms use CRISPR-derived RNA and various Cas proteins, including Cas9, to foil attacks by viruses and other foreign bodies. They do so mainly by chopping up and destroying the DNA of a foreign invader. When these components are transferred into other more complex organisms, it allows for the manipulation of genes, or “editing.”

The First Genetically Engineered Human Babies

He Jiankui became widely known in November 2018 after he had claimed that he had created the first human genetically edited babies, twin girls known by their pseudonyms, Lulu and Nana. The announcement in November 2018 of Lulu and Nana, who were born healthy by mid-October 2018, was initially praised in the press as a major scientific advancement. But following scrutiny on how the experiment was executed, He Jiankui received widespread condemnation.

He Jiankui affair - Wikipedia
He Jiankui

He announced that he had modified a key gene in a number of human embryos in a way alleged to confer resistance to HIV. The modification might be passed on to the offspring of children born with it. He recruited couples in which the father was infected with HIV and the mother was not. In a talk at the International Summit on Human Genome Editing in Hong Kong, China, He said he wanted to spare the babies the possibility of becoming infected with HIV later in life. The technique could be used to reduce the HIV/AIDS disease burden in much of Africa, he argued, where those infected often face severe discrimination.

The Future

This news a couple of years ago shocked the world. But although this use of advanced technology to change the human gene pool was premature, it was an indication of how genetic science will alter our healthcare, the way we make babies, the nature of the babies we make, and, ultimately, our sense of who and what we are as a species.

This shift in our healthcare will ensure that millions of people will have their genomes sequenced as the foundation of their treatment.

These huge datasets of genetic and life information will then make it possible to go far beyond the simple genetic analysis of today and to understand far more complex human diseases and traits influenced by thousands of genes. Our understanding of this complex genetic system within the vaster ecosystem of our bodies and the environment around us will transform healthcare for the better and help us cure dreadful diseases that have plagued our ancestors for centuries.

But as revolutionary as this challenge will be for medicine, the healthcare applications of the genetics revolution are merely stations along the way to the ultimate destination – a deep and fundamental transformation of our evolutionary trajectory as a species.

As the genetic and health data pools grow, analysis of large numbers of sequenced genomes will make it possible to apply big data analytics to predict some very complex genetic disease risks and the genetic components of traits like height, IQ, temperament, and personality style with increasing accuracy. This process is what we call “polygenic scoring.”

The most profound application of all this will be in our reproduction of progeny or “baby-making.” Before making a decision about which of the fertilized eggs to the implant, women undergoing in vitro fertilization (IVF) will be able to decide to have a small number of cells extracted from their pre-implanted embryos and sequenced. With CRISPR and other advanced technology, this can be used to screen for single-gene mutation diseases and other relatively simple disorders. Polygenic scoring, however, will soon make it possible to screen these early-stage pre-implanted embryos to assess their risk of complex genetic diseases and even to make predictions about the heritable parts of complex human traits. The most intimate elements of being human will start feeling like high-pressure choices needing to be made by parents.

Adult stem cell technologies will then likely make it possible to generate hundreds or thousands of a woman’s own eggs from her blood sample or a skin graft. This would open the doors of reproductive possibility and allow parents to choose embryos with exceptional potential capabilities from a much larger set of options.

The complexity of human biology will obviously place certain limits to the extent of possible gene edits that can be made to these embryos, but all of biology, including our own, is extremely flexible. How else could have all the diversity of life today emerged from a single cell nearly four billion years ago? The limit of our imagination will become the most substantial barrier to our re-forming biology.

Conclusion

The same tools that will help cure our worst sicknesses, save our children, extend our lifespan, allow us to live healthier, more robust lives will also open the door to inevitable exploitation. Prospective parents with the best of intentions or governments with negligent regulatory structures or aggressive ideas of how population-wide genetic engineering should be used to enhance national competitiveness or achieve some other goal could drive us into a genetic arms race that could undermine our essential diversity, dangerously divide societies, lead to dangerous, destabilizing, and potentially even deadly conflicts between us, and threaten our very humanity.

Suhani Khandelwal, Youth Medical Journal 2021

References

https://www.genome.gov/genetics-glossary/Genetic-Engineering

https://www.economist.com/open-future/2019/04/25/how-genetic-engineering-will-reshape-humanity

https://www.livescience.com/58790-crispr-explained.html

https://www.sciencemag.org/news/2019/12/chinese-scientist-who-produced-genetically-altered-babies-sentenced-3-years-jail

https://leaps.org/our-genetically-engineered-future-is-closer-than-you-think/particle-1