Have you ever wondered how your body knows when is it time to pass stool and when is it the time to pass only gas? Have you ever wondered how both existing in the same route usually do not create confusion? It is like as humans, we know when we need to use the loo or when we must excuse ourselves only for a few seconds. So, how does it happen? Your digestive system is an intricate network of organs, nerves, and muscles which work in harmony. Among its many functions, one of them is to be able to differentiate gas and stool, and it is an essential one as it prevents embarrassing accidents.

How Does Your Body Know?

Your gastrointestinal (GI) tract is the long tube that runs from your mouth to your anus. Once food moves through your stomach and intestines, the digestion process is complete, and waste material gathers in the rectum—the final storage area before elimination.

Directly below the rectum is the anal canal, which serves as the passage between the rectum and the anus. This final section of your GI tract plays a crucial role in distinguishing between gas and stool.

Your Body Has Gatekeeper

These gatekeepers are called the sphincters. Let's have a look how it works:

• The internal anal sphincter – This involuntary muscle remains tightly closed at rest, maintaining continence.
• The external anal sphincter – This voluntary muscle gives you control over when to pass stool or gas.

As per gastroenterologists, the external sphincter is our squeeze muscle and when we feel the urge to poop but are not present in the right place, we engage this muscle to hold it in. Whereas the internal sphincter automatically tightens to prevent any accidental leakage.

Anal Sampling Mechanism

One of the key reasons you can distinguish gas from stool is the rectoanal inhibitory reflex (RAIR)—also known as the anal sampling mechanism.

Here’s how it works:

When the rectum fills with gas or stool, the internal sphincter temporarily relaxes, allowing a small amount of contents to enter the anal canal.

Sensory receptors in the anal mucosa (a specialized membrane lining the anal canal) then "sample" the contents to determine whether it’s gas, liquid, or solid.

If it’s gas, your body knows it’s safe to release. If it’s solid, the external sphincter stays engaged until you decide it’s time to poop.

What is extremely essential in such a scenario is our body's ability to differentiate between gas and stool. Scientists believe that it involves a high concentration of sensory nerve endings in the anal canal that helps us understand the difference. These work due to some of the specialized nerve receptors, which include:

• Meissner’s corpuscles – Sensitive to touch and vibration
• Pacinian corpuscles – Detect pressure changes
• Krause end-bulbs – Respond to temperature shifts
• Genital corpuscles – Sensitive to friction and texture

In fact, a study titled Anorectal Sampling: A Comparison of Normal and Incontinent Patients examined how the anal sampling mechanism contributes to continence. The researchers compared 18 individuals with fecal incontinence to 18 healthy controls. It found that spontaneous sampling, which is referred to as the ability to detect rectal contents occurred in 16 out of 18 healthy individuals but only 6 out of 8 incontinent patients. This study supported the idea that the anal sampling mechanism plays a crucial role in maintaining continence. When it malfunctions, people struggle to differentiate between gas and stool, leading to accidental leakage.

Squirrels could be natural hosts of the mpox virus (MPXV) -- that causes monkeypox disease -- according to a recent study by German researchers.

The team from the Helmholtz Institute for One Health (HIOH) identified the fire-footed rope squirrel (Funisciurus pyrropus) as a likely natural reservoir of the MPXV.

The study published in the journal Nature revealed that sooty mangabeys – a primate found in West Africa -- can contract mpox by eating infected squirrels. The disease may present mild lesions, but it can also cause more severe skin lesions or even be fatal.

"Identifying the animal sources of the virus and the exposure routes that lead to inter-species transmission are key steps towards understanding spillover mechanisms and developing effective prevention measures to mitigate the risk of transmission to humans," said Livia V. Patrono, one of the senior authors at HIOH.

Squirrels Suspected MPXV Hosts

While squirrels have long been suspected as potential reservoirs for MPXV, their role was confirmed after an investigation of an mpox outbreak among wild sooty mangabeys (Cercocebus atys) in Côte d'Ivoire.

During the outbreak, reported in early 2023, nearly one-third of the primates showed clinical signs of disease, and four infants died.

The team conducted viral genome sequencing and found that the infected monkeys carried a virus that was nearly identical to an MPXV strain identified in a fire-footed rope squirrel found dead 12 weeks earlier nearby.

Further, the team analyzed fecal samples from the mangabeys. A sample collected eight weeks before the outbreak's onset contained DNA from both the virus and the rope squirrel. This provided strong evidence of interspecies transmission at that moment.

Sooty mangabeys have been previously observed catching and eating fire-footed rope squirrels, which provide a direct route for the transmission of viruses.

Mpox Continues To Spread Globally

Although mpox is no longer a public health emergency, outbreaks of clade I and clade II strains of the mpox virus are continuing in many countries around the world, especially in Africa.

Last week, Madagascar announced the country's first death from mpox, a 3-year-old girl from the island nation’s eastern city of Toamasina.

The WHO has also confirmed that two cases of the recombinant strain – combining genomic elements of clades Ib and IIb of the monkeypox virus (MPXV) – have been identified to date: one in the United Kingdom and one in India.

Mpox is an infectious disease caused by the monkeypox virus (MPXV), part of the Orthopoxvirus genus, which also includes the virus that causes smallpox.

It spreads through close physical contact, including sexual contact, and in some cases through contaminated materials or respiratory droplets.

Symptoms typically include fever, swollen lymph nodes, rash, and/or lesions.

The global health body has also urged all countries to “remain alert to the possibility of MPXV genetic recombination.” It has also urged for continued epidemiological surveillance, sequencing, vaccination of at-risk groups, and infection prevention and control measures.

An international group of scientists has created an artificial intelligence tool that can estimate a woman’s likelihood of developing breast cancer within the next four years.

The AI tool, known as the BRAIx risk score, analyzes mammogram images to generate an individualized risk assessment and flag women who may face a higher chance of developing the disease.

It may not only show the current risk but also predict the future risk, enabling early detection and treatments for a better outcome.

According to the findings published in The Lancet Digital Health journal, nearly one in 10 women ranked in the top 2 percent of risk by the AI tool were diagnosed with breast cancer within four years. This was despite previously receiving a clear screening result.

“These risk scores enable future development of personalized screening pathways to transform population breast cancer screening and save lives,” said corresponding author Helen M. L. Frazer of the University of Melbourne.

Frazer noted that identifying women who appear cancer-free but carry very high risk -- comparable to those with inherited BRCA1 or BRCA2 mutations -- will unravel both hereditary and non-hereditary causes of breast cancer.

From one-size-fits-all screening to personalization

Breast cancer screening programs have significantly lowered mortality rates -- by roughly 40-50 percent among women aged 50 to 74. However, most screening systems still apply the same approach to all women, regardless of individual risk.

Traditional screening tools use genetics, breast density, and questionnaires to estimate breast cancer risk. On the other hand, new AI-based screening tools, such as BRAIx personalizes screening by gathering information already present in breast scan images to better identify who is at higher risk.

“Our results show that conventional mammographic density is a far weaker predictor of breast cancer risk than the BRAIx risk score, even for interval cancers,” the researchers said in the paper. Interval cancers are aggressive tumors diagnosed after a negative mammogram.

The BRAIx Tool

The BRAIx risk score was developed using mammograms from nearly 400,000 women. To prove its efficacy, the AI tool was tested on data from almost 96,000 women from Australia and then confirmed in an independent Swedish population of over 4,500 women.

The findings showed that:

• The BRAIx risk score estimated breast cancer risk more accurately than the traditional risk factors, such as breast density, country of birth, and even family history.

• For the top 2 percent of women with the highest BRAIx risk score, the probability of a cancer diagnosis within 4 years was 9.7 percent -- a risk level exceeding that typically seen in women with inherited BRCA1 or BRCA2 mutations.

The BRAIx risk score can:

• Make breast screening more personalised,
• Improve early cancer detection,
• Reduce false alarms,
• Save lives without increasing costs

Global Breast Cancer Burden

Breast cancer continues to be the most common cancer among women worldwide.

A recent study published in The Lancet Oncology journal predicted that the number of new cases of the deadly disease will reach more than 3.5 million globally in 2050 -- rising by a third from 2.3 million in 2023.

Annual deaths from the disease will also rise by 44 percent -- from around 764,000 to 1.4 million.

However, not smoking, getting sufficient physical activity, lowering red meat consumption, and having a healthy weight can help prevent over a quarter of healthy years lost to illness and premature death from breast cancer.

People who survived a COVID-19 infection can be at significant risk for kidney disease, acute kidney injury, and chronic kidney disease. compared to individuals who were not infected, according to a study.

The study, published online in the journal Communications Medicine, revealed that COVID patients have

• a 2.3-times higher risk of acute kidney injury
• a 1.4-times higher risk of chronic kidney disease
• a 4.7 times higher risk of kidney failure

“While we’re in the post-pandemic era, this shows that COVID-19 history is an important variable when considering the long-term impact of the infection on kidney function and disease,” said first author Yue Zhang, who was at Pennsylvania State University, US, while conducting the study. Zhang is currently a postdoctoral scholar at Johns Hopkins Bloomberg School of Public Health.

How Was The Study Conducted?

For the study, data on over 3 million working-age adults in the United States were analyzed.

The team compared the effect of influenza, another common viral infection that affects kidney health, and people with a history of COVID infection on kidney infections.

Using a machine learning model, the individuals were followed between 180 and 540 days for the emergence of new acute or sudden kidney disease.

The results showed that:

• Both COVID and the flu can worsen kidney health
• Flu caused a mild and temporary effect
• COVID increased the risk of acute kidney injury for a longer duration
• COVID survivors developed kidney disease within a few hours to a few days
• COVID patients had a longer-term chronic and end-stage kidney disease.

How COVID Worsens Kidneys Health

The Penn State researchers explained that kidney cells express high levels of the primary protein receptors that SARS-CoV-2 uses to enter and infect cells. Kidney cells also produce specialized enzymes that help viruses enter cells.

According to Kidney Health Australia, an acute COVID infection can impact the kidneys with fevers and respiratory symptoms, and/or worsening blood sugar control.

The US National Institutes of Health stated that renal dysfunction is an increasing clinical indicator of COVID propagation.

Citing several studies, the NIH said that the most common clinical manifestation is proteinuria -- found in more than half of the COVID patients. In addition, hematuria, elevated blood urea nitrogen, and elevated serum creatinine are other common features in Covid survivors with poor kidney health.

Nasr Ghahramani, Professor of Medicine at Penn State College of Medicine, stressed the need for COVID survivors, especially those with diabetes and high blood pressure, to take "more frequent and more prolonged monitoring of their kidney function" to enable early detection and better outcomes.