Medical Bulletin 24/January/2023

Here are the top medical news for the day:

Emotional ‘blunting’ caused by common antidepressants explained in new study

Scientists have worked out why common anti-depressants cause around half of users to feel emotionally ‘blunted’. In a study published recently, they show that drugs affect reinforcement learning, an important behavioral process that allows us to learn from our environment.

A team led by researchers at the University of Cambridge, in collaboration with the University of Copenhagen, recruited healthy volunteers and administered escitalopram, an SSRI known to be one of the best-tolerated, over several weeks and assessing the impact the drug had on their performance on a suite of cognitive tests.

Reference:

Langley, C, Armand, S, et al. Chronic escitalopram in healthy volunteers has specific effects on reinforcement sensitivity: A double-blind, placebo-controlled semi-randomised study. Neuropsychopharmacology; 23 Jan 2023; DOI: 10.1038/s41386-022-01523-x

New genetic disorder that causes susceptibility to opportunistic infections revealed in new study

An international consortium, has discovered a new genetic disorder that causes immunodeficiency and profound susceptibility to opportunistic infections including a life-threatening fungal pneumonia.

The error in this case of in-born error of immunity or IEI is a mutation in the gene for the protein IRF4, a transcription factor that is pivotal for the development and function of B and T white blood cells, as well as other immune cells.

In the current study, the consortium identified seven patients from six unrelated families across four continents with profound combination immunodeficiency who experienced recurrent and serious infections, including pneumonia caused by the fungus Pneumocystis jirovecii. Each patient had the same mutation in the DNA-binding domain of IRF4.

Reference:

Rubén Martínez-Barricarte et al,A multimorphic mutation in IRF4 causes human autosomal dominant combined immunodeficiency,Science Immunology,doi 10.1126/sciimmunol.ade7953

New mechanism for MRSA virulence discovered

Researchers at Mount Sinai, in collaboration with researchers at New York University, have published a study that sheds light on the mechanisms behind the severity, or virulence, of methicillin-resistant Staphylococcus aureus (MRSA) blood stream infections. The study, reveals that MRSA has undergone repeated mutations in the sarZ gene, a transcriptional regulator responsible for regulating virulence gene expression, leading to increased severity of blood stream infections in mouse models.

Reference:

Harm van Bakel et al,MRSA lineage USA300 isolated from bloodstream infections exhibit altered virulence regulation,Cell Host & Microbe,doi 10.1016/j.chom.2022.12.003