Saturday, April 20, 2013

Sounds to Cure

Sounds can have a powerful effect on living beings - humans, animals, plants. Relaxing music can have a healing effect. A new study showed this specifically for premature babies.

Live ocean disc whoosh sounds, gato box rhythms, and parent's sung
lullabies - these sounds have been found to be especially beneficial increasing infants' capacity to feed, sleep, and self-regulate.

Baby's hearing develops in the womb. The very first sound unborn baby  hears at about 16 weeks of development is the mother's heartbeat. Gato - a small rectangular wooden drum - creates a rhythm in soft timbre that reminds the heartbeat. Ocean waves resemble the fluid sounds of the womb, as well as inhalation and exhalation sounds. And a sweet lullaby could definitely soothe anyone who has problems trying to get to sleep or suffer with insomnia - as this is one of the oldest, most natural forms of human interaction that brings feelings of warmth and togetherness.

REFERENCES
Loewy J, Stewart K, Dassler AM, Telsey A, Homel P.The Effects of Music Therapy on Vital Signs, Feeding, and Sleep in Premature Infants. Pediatrics. 2013 Apr 15. [Epub ahead of print

Thursday, February 7, 2013

Big Data of Sounds

Hearing begins with the ears, but it's more than the sum of sounds. We are able to recognize piano notes and experience music, understand speech in noisy surroundings and localize voice in 3D.  Is it because the sound transmitted to the inner ear is broken down into frequencies and mapped onto the brain like musical notes are mapped on a piano keyboard? But are not we able to hear different things at once in three dimensions? Are not we translating frequencies into meanings on the fly, processing Big Data better than any famous statistician? As Jacob Oppenheim and Marcelo Magnasco showed that simple decomposition of sounds into its components by Fourier transform loses important information about the sound's duration, something that our brain is actually able to overcome. Humans can beat the limits of Fourier analysis, and the Brain processes the big data of sounds better than existing algorithms do. As a matter of fact, training our brain on music makes us better in math and problem solving skills. While inability to process signals in the brain leads to developmental disorders. More to discover, more to learn.

REFERENCES

Oppenheim, Jacob N., and Marcelo O. Magnasco. "Human Time-Frequency Acuity Beats the Fourier Uncertainty Principle." arXiv preprint arXiv:1208.4611(2012).

Díaz, Begoña, et al. "Dysfunction of the auditory thalamus in developmental dyslexia." Proceedings of the National Academy of Sciences 109.34 (2012): 13841-13846.

Tuesday, March 22, 2011

Can Your Baby Hear Well?

About 2 to 3 out of every 1,000 children in the United States are born deaf or hard-of-hearing. Nine out of every 10 children who are born deaf are born to parents who can hear. 


Unfortunately existing hearing tests do not always catch hearing loss in newborns. According to a new study, one-third of children later treated for deafness with cochlear implants had actually passed the newborn screening.
Thumbnail of chart; click to display full-size image.

The graph on the right shows summary rates of the percentage of newborns screened for hearing loss prior to hospital discharge based on individual State reports posted on the Early Hearing Detection and Intervention Program (EHDI), 1999–2005 Web site. Trend data on newborn hearing screening rates are also available from the DHHS Healthy People 2010 Project (US DHHS, 2006) and from CDC Wonder: Healthy People 2010. Newborn hearing screening rates increase in a linear fashion from 46.1% in 1999 to 82.9% in 2002; thereafter, while the rates continue to increase, the trend line begins to flatten out, reaching 91.5% in 2005. 
So more babies are screened for hearing loss while they are still in the hospital before they go home. 


Yet, as researchers at Children's Memorial Hospital in Chicago found out - by  looking at the records of 127 children who had hearing problems severe enough to be treated with cochlear implants: one-third of these babies had passed the newborn hearing test.

This is not necessarily because the screening is not accurate, but rather the result of the fact that some hearing loss develops slowly. Babies at risk for progressive deafness include those who had cytomegalovirus infections, and those who were in a neonatal intensive care unit.

The earlier children with hearing problems get help, the better they will do at developing language skills. And more testing screens may be needed - Perhaps, even including genetic tests like those developed by Harvard's Center for PErsonalized Genetic Medicine. Or more at-home screening, including iPhone apps or  other inexpensive devices.


References

Nancy Melinda Young, MD; Brian Kip Reilly, MD; Larisa Burke, BA
Limitations of Universal Newborn Hearing Screening in Early Identification of Pediatric Cochlear Implant Candidates. Arch Otolaryngol Head Neck Surg. 2011;137(3):230-234. doi:10.1001/archoto.2011.4


U.S. Department of Health and Human Services. Chapter 28: Vision and Hearing. In:Healthy People 2010 Midcourse Review. Washington, DC: U.S. Government Printing Office, December 2006. (Available at www.healthypeople.gov/


White KR. Research review—Early hearing detection and intervention programs: Opportunities for genetic services. Am J Med Genet 2004; 130A: 29–36.

Thursday, July 15, 2010

Temperature-induced hearing loss

There are many reasons why people loose hearing. Environmental factors  - especially prolonged loud noise and infection or injury - are among the leading causes in the US (figure on the right). Drugs, and chemical toxins could also play a role. Genes accounts for less than half of causes. Gene-environment interactions are contributing too. 
  • Drug induced - some medications can result in damage to the auditory system with prolonged use. They are called ototoxic. Here are a few drugs that are known to cause hearing loss: aminoglycoside antibiotics (such as streptomycin, neomycin, kanamycin); salicylates in large quantities (aspirin), loop diuretics (lasix, ethacrynic acid); and drugs used in chemotherapy regimens (cisplatin, carboplatin, nitrogen mustard). Genetics may predispose to vulnerability to drugs.
  • Noise-induced hearing loss (NIHL) - this is hearing loss due to exposure to either a sudden, loud noise or exposure to loud noises for a period of time. A dangerous sound is anything that is 85 dB (sound pressure level - SPL) or higher. Genetics may determine vulnerability thresholds to noise.
  • Temperature-induced hearing loss.  Genetics could cause temporary hearing loss caused by a high body temperature. They recover some time after their body temperature has returned to normal.  
It is well known that high fevers cause hearing loss. High fevers account for about 1,200 to 1,800 cases of hearing loss in the US each year. Artificially-induced high body temperature  - for example by a strenuous workout in a 105 degree room - may be the culprit too.
Mutations in the otoferlin (OTOF) gene  - known to cause neurosensory nonsyndromic recessive deafness - have been recently linked to rare temporary hearing loss caused by a high body temperature.
In one of the cases examined, hearing of a young boy in the morning was better than in the afternoon, and temperature measurements showed that his body temperature in the afternoon was generally higher than that in the morning. Hospital examination showed that when his body temperature rose above 36.5°C, the  hearing loss was severe (70-80dB HL) and this symptom could last for a whole day. The boy with the temperature-dependent hearing loss had two variant OTOF genes, each of which is not usually seen in normal-hearing people.
Another study of a family with three children whose hearing was sensitive to temperature also linked their ailments to OTOF gene.

References

Fukushima K, Ramesh A, Srisailapathy CR, et al. (1996). An autosomal recessive nonsyndromic form of sensorineural hearing loss maps to 3p-DFNB6. Genome Res. 5 (3): 305–8. PMID 8593615

Varga, R. (2005). OTOF mutations revealed by genetic analysis of hearing loss families including a potential temperature sensitive auditory neuropathy allele Journal of Medical Genetics, 43 (7), 576-581 DOI: 10.1136/jmg.2005.03861

Wang, D., Wang, Y., Weil, D., Zhao, Y., Rao, S., Zong, L., Ji, Y., Liu, Q., Li, J., Yang, H., Shen, Y., Benedict-Alderfer, C., Zheng, Q., Petit, C., & Wang, Q. (2010). Screening mutations of OTOF gene in Chinese patients with auditory neuropathy, including a familial case of temperature-sensitive auditory neuropathy BMC Medical Genetics, 11 (1) DOI: 10.1186/1471-2350-11-79

Marlin, S., Feldmann, D., Nguyen, Y., Rouillon, I., Loundon, N., Jonard, L., Bonnet, C., Couderc, R., Garabedian, E., & Petit, C. (2010). Temperature-sensitive auditory neuropathy associated with an otoferlin mutation: Deafening fever! Biochemical and Biophysical Research Communications, 394 (3), 737-742 DOI: 10.1016/j.bbrc.2010.03.06

Wednesday, December 16, 2009

Drug-induced hearing loss: new SNPs in old genes

Drug-induced ototoxicity is known and well documented. Merck manual  lists several antibiotics (streptomycin, neomycin, vancomycin), chemotherapeutic drugs (such as cisplatin), diuretics (like ethacrynic acid and furosemide), Quinine and Salicylates among the prime suspects.

The impact of these drugs on individuals depends on their genetic makeup.

Here is a new addition to the collection of genes associated with hearing loss caused by gene-environment-interaction:  Genetic variants in TPMT and COMT have been found to affect hearing of children receiving cisplatin chemotherapy (Ross et al., 2009)

220 drug-metabolism genes are suspected to be responsible for genetic susceptibility to cisplatin-induced hearing loss in children. Metabolism genes such as Glutathione S-transferases and megalin were previously studied. Genotyping of 1,949 SNPs in these candidate genes in an initial cohort of 54 children lead to  identification of new genetic variants in TPMT (rs12201199, P value = 0.00022, OR = 17.0, 95% CI 2.3–125.9) and COMT (rs9332377, P value = 0.00018, OR = 5.5, 95% CI 1.9–15.9.

What do we know about these genes?

TPMT is aS-adenosyl methionine-dependent methyltransferase that converts 6TI to 6MMPr. Its sequence is conserved in human, chimpanzee, dog, cow, rat, chicken, and zebrafish.  Hard to say how our ancestors were exposed to this compounds, but as thiopurines are known inhibitors of de novo purine synthesis and cellular proliferation, it makes sense to have ways to deal with this molecule.

The enzyme is mostly known because it metabolizes thiopurine drugs via S-adenosyl-L-methionine as the S-methyl donor and S-adenosyl-L-homocysteine as a byproduct. Accordingly, genetic polymorphisms that affect this enzymatic activity are correlated with variations in sensitivity and toxicity to drugs such as 6-mercaptopurine within individuals. A pseudogene for this locus is located on chromosome 18q

COMT is a Catechol-O-methyltransferase that catalyzes the transfer of a methyl group from S-adenosylmethionine to catecholamines - chemicals produced in the medulla of the adrenal gland. COMT is also known for its role in the metabolism of catechol drugs used in the treatment of hypertension, asthma, and Parkinson disease.
Location: 22q11.21-q11.23|22q11.21

Now that we know, what can we do with the new SNP information?

Perhaps, investigate cost-effectiveness of genotyping for ototoxycity implications - clinical trial  NCT00521950 is already doing it for Inflammatory Bowel Diseases. 

Friday, December 4, 2009

The Ear Blog

Welcome to the Ear Blog!

Hearing has always been the Cinderella of the senses, but we can't undermine its importance. Among all the senses, this is the one we are most likely to lose.
The fascinating world of the inner ear consists of the smallest bones, spirals and fluid-field channels, along with tiny sensory units called hair cells. We are born with about 15,000 of them in each ear, and are subjecting these remarkable structures to constant damage from drugs, iPods, many other silence-disrupting technologies, even diets and aging. We'll talk more about it in other bloglications, meanwhile see these animations by TheatricalDesign or play with this one by adjusting the frequency of the sound entering the ear and watch youtube videos.
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