Growing mini livers, the left hand, & safe weight gain during pregnancy | Last Week in Science (7 April 2024)

The left hand

Are you left handed and wonder what made you so? Around 10% of the global population use their left hand predominantly for doing most of their tasks.

Multiple genes have been associated with left handedness in the studies done so far. One such gene is TUBB4B that forms tubulin protein. Tubulin forms microtubules that are required for movement of cell, its shape, its growth and division. Defects in tubulin gene is seen in many neurodevelopmental diseases.

In the current study, researchers in the Netherlands have found a rare mutation in the tubulin gene that is present in left handed people. This mutation is different than the one which causes diseases. So, how does a protein decide which hand you would use? The researchers think that when the brain is developing in the fetus - tubulin makes the right side of the brain different from the left, thus making right side dominant. The right side of the brain controls the left side of the body and vice versa . This does not mean that there are left or right brained people as for most of the functions - language processing, making art, and feeling emotions both sides of the brain have different roles to play. 

The role of tubulin seems to be important in shaping the asymmetry of brain. Brain asymmetry means that the left and right hemispheres are not exactly the same in terms of which aspects of a function of the body they control. Further studies on the role of tubulin in making the brain asymmetric may hold answers for how the brain develops and how minor changes can lead to diseases.

Growing mini livers inside a human body

In a first of its kind clinical trial, a patient with liver failure has been administered cells that will grow into mini livers inside their body.

Liver is essential for our survival as it is involved in removing toxins from blood, helping in digestion and utilization of food. The current treatment for liver failure is liver transplant from a healthy donor. Transplant requires not just a donor but also the matching of the donor with the recipient so that the body's immune system does not attack the donor liver, which too can be fatal. LyGenesis, a company in Pennsylvania USA, has come up with an innovative solution to get past the shortage of a matching liver for transplant. This treatment strategy worked well in mice, dogs, and pigs and has now been tested in a human.

The treatment involves injecting donor liver cells into the recipient's lymph nodes present near the liver. Lymph nodes are present in large numbers in the body and help the body to fight infections, so modifying a few of them should not cause any harm. The injected lymph nodes have been shown to form mini livers and taking over the functions of liver. The patient receiving this treatment is now on immunosuppressive medications and will be followed up to find if the treatment has been successful.

LyGenesis has plans to grow kidneys and pancreas too in the near future if the mini livers are successful. They also plan to use patient's own stem cells so that there is no risk of rejection of the donor cells.

Reference: ‘Mini liver’ will grow in person’s own lymph node in bold new trial

Safe weight gain during pregnancy in obese women

For the healthy growth of the developing embryo, more calories and thus weight gain is essential during pregnancy. WHO recommends guidelines for how much weight gain is required during pregnancy based on the weight of the mother. No weight gain is needed in the first trimester, but second trimester onwards a steady increase in weight every week is advised.

A weight gain of 5 - 10 kgs is advised for obese women (early pregnancy BMI before 14 weeks' gestation ≥30) during pregnancy, but the absence of systematic studies have made weight gain guidelines risky for obese women and the baby. Obesity increases the risk of diabetes or increased blood pressure during pregnancy and chances of stillbirth or death of the baby. It can also cause heart diseases after pregnancy. The chances of developing these conditions increase with weight gain during pregnancy.

A recent study at Karolinska Institutet, Sweden has found that a minimum of 5 kgs weight gain may not be needed. The scientists studied the medical records of 15,760 pregnant women with obesity in Sweden. They found that 2-3 kgs of weight gain is healthier and beneficial for both the mother and the baby as opposed to the recommended 5 kgs. The study suggests the need for revising the weight gain guidelines for obese women so as to reduce the pregnancy related complications for the baby or the mother.

Edited by Ashish Gourav