QUESTION CORNER
Why do some dreams remain in our memory for a long
time while some vanish from our memory even while waking from sleep and
we are not able to recollect however hard we try?
T.N. SAMA RAO
Thiruninravur, Tamil Nadu
Dreams
occur during a stage of sleep known as REM (rapid eye movement) sleep,
also known as paradoxical sleep. It is paradoxical in the sense that
although we are sleeping, the brain is actively involved in creating a
visual experience called dream, and its metabolic activity is equivalent
to that in the awake state.
Most
of the dreams are stored in the brain as a learning experience that we
cannot demonstrate or remember. It is for the safety and well being of
the person who has a dream that he/she doesn’t remember them since most
of the dreams that we usually experience are bizarre and often
frightful. That is why during the next stage of sleep ie. slow wave
sleep (SWS), these dreams get washed off and the person gets up not
remembering anything at all.
But
yes, we tend to remember some dreams. It is generally seen that if a
person gets awake suddenly while dreaming out of fright or someone else
forcefully awakens that person while he/she is in REM sleep stage, that
dream gets registered in our memories for short periods. Some very well
known painters of the Renaissance period have employed this technique of
disrupting their REM sleep suddenly and painting their dreams. These
paintings are a presentation of that they were seeing.
In
general, when we do not give enough time for our dreams to wash off as
un-recallable experiences, we tend to remember them, but as a rule, the
brain tries all it can to ensure that we get up remembering nothing at
all.
So it will suffice to say
that dreams are stored as experiences that you cannot recall or tell
someone else, but yes, during special circumstances when you disrupt
your dream state suddenly, you do remember your dreams albeit for short
durations.
KARTIK GUPTA
AIIMS, New Delhi
Smoking causes type II diabetes
The risk of developing diabetes is 30 to 40 per cent higher in smokers than in nonsmokers
The number of diseases causally linked to smoking is ever expanding.— photo: AP
Fifty years since the first U.S. Surgeon General’s
Report in 1964 clearly stated that cigarette smoking was a health
hazard, the 32{+n}{+d}Surgeon General’s Report released recently has
shown that we are yet to fully understand the real magnitude and extent
of tobacco’s diverse adverse effects on the human body. The Report
expands the list of diseases and adverse health effects of smoking.
If
the 2004 report of the Surgeon General concluded that smoking affects
nearly every organ of the body, the latest report provides much more
evidence to support this conclusion made 10 years ago.
The
most important finding for Indians is that smoking is a “cause” of type
II diabetes, and the risk of developing diabetes is 30 to 40 per cent
higher in smokers compared with nonsmokers. Also, the risk increases
with the number of cigarettes smoked. It is already known that smoking
“complicates the treatment” of diabetes.
Another
revelation is that liver and colorectal cancers are caused by smoking.
In effect, the list of cancers caused by smoking has become even longer.
Smoking is found to cause rheumatoid arthritis too.
“Smoking
is a cause of AMD” (age-related macular degeneration) it notes. The
macula of the eye that enables sharp vision gets gradually destroyed
leading to loss of central vision. While quitting smoking helps in
reducing the risk of AMD, the benefits would not show up for 20 or more
years after quitting.
The report clearly notes that the number of diseases causally linked to smoking is ever expanding.
Also,
the evidence of increased risk to many diseases and adverse effects in
those exposed to secondhand smoke is rising. For instance, the increased
risk of suffering from stroke has been positively found to be linked to
smoking.
Higher risk in women
The
notion that women are less vulnerable than men when it comes to
cardiovascular disease has been disproved. The risk of dying from
coronary heart diseases in women aged 35 years and more is actually
“higher than in men,” the report notes. “Women who smoke now have about
the same high risk of death from lung cancer as men,” it adds.
For
the last fifty years tobacco companies have been continuously altering
their strategies to sell their improvised wares to attract youth and
ensure a steady supply of new customers and not to lose existing ones.
Low tar cigarettes, menthol cigarettes, light cigarettes, cigarettes
with filter to cut the amount of nicotine inhaled are some of the new
products launched by them.
Thanks to the tobacco
companies, smokers today are at a greater risk of developing lung cancer
than they did 50 years ago. While the incidence of squamous cell
carcinoma of the lung — the kind of lung cancer most often found in
smokers — has declined, the incidence of another kind of cancer —
adenocarcinoma — has increased “dramatically.”
“Changes
in the design and composition of cigarettes since the 1950s have
increased the risk of adenocarcinoma of the lung, the most common type
of lung cancer,” it notes.
Evidence suggests that
smokers tend to inhale more vigorously when they smoke cigarettes with
“ventilated filters.” As a result, they tend to draw the carcinogens
much more deeply into the lungs. This has resulted in the shift in the
type of carcinoma of the lungs during the past 50 years.
However,
the risk of dying earlier gets reduced if a person quits smoking. While
it is known that smoking shortens life expectancy by 10 years, quitting
by 40 years of age results in 90 per cent reduction of that risk. It is
nearly 40 per cent if a person quits by the age of 60 years. Reducing
the number of cigarettes smoked a day is “much less effective than
quitting entirely.”
Novel materials inspired by burr, tooth and seashells
Biology has inspired many human inventions and we now have an emerging field termedbio-inspired material science
Surrealism:Like this Salvador Dali sculpture, bio-inspired materials may
throw in many surprises and applications in days to come.— photo: AFP
As George de Mestrel was walking his dog one day in the woods of
Switzerland, some burrs (prickly sacs of the plant that hold seeds)
stuck to the dog’s body and Mestrels’s pants. Shaking them off was not
easy. He then looked at them carefully and found hook-like attachments
that held the burr on to the dog and to his trousers. Even as he shook
them off, he thought if only I can add a loop on the other side of the
hook, I can make a device that can replace a zipper. He worked on the
idea for 8 years and the fastener Velcro was born.
Velcro is the
first well-known man-made device or material that was inspired by what
is seen in biology. Plants and animals contain various curious
structures and devices in their body which help them in their daily
life. For the cockleburr and similar plants (we have them in India,
called
Banokra, Chota Dhatura, Marulam Athangi
), the burr is a transportable seed bag which is dispersed across the
land by the animal it sticks to. And for man it became an inspiration to
invent a fastening device.
Biology has inspired many such human
inventions and we now have an emerging field termedbio-inspired material
science. Universities and R &D centers across the world have set up
laboratories where scientists study the unusual (and clever) materials
and devices that are built into or made by plant and animal bodies, try
understand and mimic or model them and create new materials of unusual
properties.
A great example is the material out of which the
spider weaves its web. The web is a trap into which the prey, even heavy
ones such as beetles and lizards, fall and cannot get out. The spider
silk has a density and tensile strength comparable to some metallic
alloys, and can be stretched up to five times its length without
breaking. This has inspired an emerging industry that attempts to make
spider silk- like materials for building structures such as motor car
and aircraft bodies!
The footpad of an ordinary household lizard
is a marvel in itself. We all wonder how in the world it climbs a wall
so fast and runs upside down on the ceiling. Electron microscopic study
of the footpad shows millions of elaborate tiny hair like protuberances
called
setae
which help the foot cling on to any surface – wet or dry, smooth or rough. Each
seta
by itself is nothing to speak of in strength- but arrange thousands or
millions together, they offer strength, the ability to hold on to any
surface, yet release and reattach as the gecko or lizard moves -it works
marvels.
Shivaji is reported to have used one such giant gecko (called
udumbu
in Tamil) to climb a fort wall. While he used the actual animal, today’s
materials scientists are inspired by the gecko to generate artificial
materials with the same remarkable properties.
An important point
that emerges when one studies these unusual biological structures is the
set of microstructures that are assembled to make the macro-object.
While each strand of the spider silk or the
seta
of the lizard is by itself too fragile, weak and brittle, when we put
them together (as a silk fiber or footpad), we gain strength, stability,
toughness and macroscopic properties. A single broomstick is brittle
and easily broken, but tie them up together as broom, it become strong
and unbreakable (note the symbol of the
Aam Admi Party
!) It does not have to be only organic materials like silk or
setae
. Minerals and inorganic materials too are organized in nature to produce strong and tough objects).
A
group of mechanical engineers at the McGill University in Montreal,
Canada have studied the structures of the tooth (made largely of
inorganic material) and sea shells called
nacre
.
The tooth enamel is an organization of long rods perpendicular
to the surface of the tooth, held together by a small fraction of
proteins. It is this that offers the tooth enormous strength. The
nacre
is made up of microscopic tables of chalk, with some proteins and
polysaccharides holding them together. It is the interfaces between the
layers that “give” when the material is stressed, distributing the
energy easily and thus making the entire assembly strong and resistant
to breakage.
See how counterintuitive this idea is! Shock is
absorbed by the microstructures and interfaces, thus dissipating the
energy smoothly, offering the tooth or the
nacre
enormous strength. The McGill group is attempting to use this principle
of putting in interfaces and microstructures in glass, in an attempt to
make glass less brittle, unbreakable and even bendable. What was
otherwise hard and brittle can be made more pliable for use.
The
maverick painter and artist Salvador Dali once painted a “melting” clock
dripping like syrup out of a table. Well, he was not crazy but a
foreteller of the future (as many artists are). Bio-inspired materials
may throw in many surprises and applications in days to come.
D. BALASUBRAMANIAN
dbala@lvpei.org
Immune genes carry imprint of the plague
The plague epidemics that swept Europe repeatedly took
such a toll in human lives that variants of key immune system genes,
which gave a survival advantage, spread in people living there.
Research just published in the
Proceedings of the National Academy of Sciences
uncovered evidence for such evolutionary selection by examining two
ethnic groups in present-day Romania — those of European ancestry and
the Rroma, also known as gypsies. The latter are the descendants of
people who migrated from north-western India and settled in Europe about
1,000 years back.
A team of European
scientists, along with colleagues in India, examined genetic variations,
known as ‘single nucleotide polymorphisms’ (SNPs), in 100 individuals
each of European ancestry and from the Rroma community.
These
SNPs were then compared with the ones found in 500 Punjabis, who were
taken as representing people from the geographic origin of the Rroma.
The
scientists looked for genetic variations that were similar in those of
European lineage and the Rroma and where both differed from the
Punjabis.
This allowed them to identify places
in the genome where the two Romanian ethnic groups had been subjected
to common evolutionary pressures.
“This paper
shows that two human populations with a different ethnic and genetic
background show similar evolutionary pressures due to the environment in
which they live,” observed Mihai G. Netea of the Radboud University
Nijmegen Medical Center in The Netherlands, one of paper’s senior
authors. Both “European and Rroma populations show positive selection in
similar genes of the immune system,” he said in an email.
As
the large plague epidemics in Europe had death rates of up to 30 per
cent to 50 per cent, “it is rational to hypothesise that plague had
major evolutionary effects on the immune system of European
populations,” the paper noted.
The worst of
these epidemics was the one known as the Black Death that devastated the
region in the 14th century and which occurred after the Rroma had
settled there.
The Indian subcontinent, on the
other hand, had escaped the Black Death and the plague epidemics it
suffered had far less impact.
The Europeans
and Rroma showed positive evolutionary selection in SNPs associated with
three genes relating to the immune system that cluster on the same
chromosome. Those genes produce proteins — Toll-like receptors 1, 6 and
10 — that were involved in the immune defence against bacteria,
including
Yersinia pestis
, the one that causes plague.
The scientists
were also able to show that white blood cells with the three gene
variants found in Europeans and Rroma gave a stronger immune response
when exposed to
Y. pestis.
The hypothesis was that these gene variants
increased the survival of individuals who faced the plague, according to
Prof. Netea.
It was not possible to study
this as the research did not investigate patients with plague. “It is a
plausible hypothesis, but no more than that,” he said in his email.
The analysis also showed that a cluster of four genes, including
SLC45A2
that produced light skin pigmentation, was among those that had been evolutionarily selected in Europeans and Rroma.
Not everything was related to the plague and many other pressure factors may have been involved, remarked Prof. Netea.
“Studies
of this nature help us identify genes, particularly in the immune
pathways, that are under evolutionary pressure,” said B.K. Thelma of the
University of Delhi’s Department of Genetics, who is one of the paper’s
authors.
Cancer: low dose gamma radiation shows promise
Holding out potential for effective cancer therapy in
future, researchers from German Cancer Research Centre and the
University of Hyderabad have found a novel anti-tumour role of low dose
of gamma radiation in mice as well as human subjects of pancreatic
cancer.
In the study, the researchers irradiated
pancreatic tumour-bearing mice to low dose of gamma radiation (2Gy)
which is around 20 times less than the dose normally used clinically for
cancer treatment. The lower dose irradiation significantly triggered T
cell immune responses and reduced tumour growth, they found. In a human
clinical study, patients in advanced stage of pancreatic cancer were
irradiated locally with 2Gy dose of gamma radiation in a therapeutic
setting and it produced similar results. In all out of 15 cancer
patients, six were irradiated and the rest were controls.
In
the entire process, macrophages played an indispensable role in
augmenting T-cell aided immunity against established and solid
pancreatic tumours.
Macrophages are the integral part
of both innate and adaptive immune system and normally involved in
destroying invading foreign bodies. Most interestingly, they act like
double-edge swords of immune system and could control as well promote
tumour growth, mentioned Dr. Hridayesh Prakash, (Ramanujan Fellow),
Department of Biochemistry, University of Hyderabad. Dr.Prakash is the
lead author of the study that was published in November 2013 in the
Cancer Cell
journal.
During initial stages of tumour development,
these macrophages possess tumour regulatory potential, mediated by
nitric oxide and pro-inflammatory factors. However, under the influence
of immunosuppressive tumour micro-milieu, they get converted and promote
tumour growth.
In further experiments, the
researchers found that replacement of resident macrophages with gamma
ray programmed macrophages in an adoptive transfer setting was
sufficient to augment T cell immunotherapy and successful tumour
rejection even in the absence of additional irradiation of recipient
tumour-bearing mice.
The researchers also found that
blocking INOS enzyme activity, the key marker of tumour regulatory
macrophages, led to abolishment of T-cell immunotherapy and tumour
rejection.
Dr. Prakash said the study demonstrated
the role of iNOS+ macrophages in conditioning tumour microenvironment
favouring T cell immunotherapy as well as angiogenesis in mice and
successful tumour rejection.
He said their novel findings have tremendous therapeutic potential in dealing with persistent bacterial infections like
H. pylori
which are associated with cancer development. The re-activation of
macrophages was of paramount requirement for both, effective eradication
of pathogens and in minimising the risk of infections that could lead
to cancer.
Shipwreck may yield clues to ancient trade link
In a bid to find clues about the historical link between Rome and
Asia during ancient times, an international team of archaeologists is
set to embark on an excavation drive at the oldest known shipwreck in
the Indian Ocean.
The sunken ship has been sitting on the seafloor
off the southern coast of Sri Lanka for some 2,000 years and was
discovered in 2003.
The shipwreck lies 33 metres below the ocean’s
surface, just off the fishing village of Godavaya where German
archaeologists in the 1990s had discovered a harbour that was an
important port along the maritime Silk Road during the second century
AD.
“Everything is pretty broken but the wreck could fill a gap in
the existing evidence for the trade that brought metals and exotic
commodities like silk from Asia to the Roman world,” Deborah Carlson,
president of the institute of nautical archaeology at Texas A&M
University, was quoted as saying.
He is leading the expedition to the Godavaya wreck with colleagues from the U.S., Sri Lanka and France.
The team expects to start diving in mid-February and continue working through May.
The
sunken ship is a concrete mound of corroded metal bars and a scattering
of other ancient cargo — including glass ingots and pottery.
The
shipwreck was discovered when a local fisherman found ancient artefacts,
including a grinding stone shaped like a small bench.
Carlson partially documented the wreck during three subsequent exploratory campaigns between 2011 and 2013.
Age determination
To determine the age of the wreck, Carlson and team took three wood samples from the mound and got them tested.
The results floored the team and they decided to launch the excavation mission.
The
mound covers an area of about twenty by twenty feet, though the team
has not been able to establish exactly where the shipwreck begins and
ends during their short explorations of the site, said the report on
LiveScience.com.
— IANS
The ship has been lying on the sea bed for 2000 years
The diving expedition will start in mid-february
Managing false smut disease in rice
False smut infestation in rice has been reported from
many places in the State in an alarming proportion. In Cauvery delta
zone, the disease has been reported to an extent of 10-20 per cent
during kharif and rabi seasons.
Another name
Also known as Lakshmi disease, it is caused by a fungus and was believed to be an indication of a bumper crop in the year.
Due
to the infection, individual grains of the panicle get transformed into
greenish spore balls of velvety appearance. Spore balls are small at
first growing gradually to reach one cm or more in diameter.
They
are slightly flattened, smooth, yellow and are covered by a membrane.
The membrane bursts as the result of further growth and the colour of
the ball turns orange and later yellowish-green or black.
Under
congenial conditions like high moisture or rainfall accompanied by
cloudy days during the period between flowering and maturity of grains,
the development of false smut is rapid and causes considerable loss.
Yield
loss is not only due to the occurrence of the smut balls but also due
to increased sterility of kernels adjacent to the smut balls.
The
disease not only reduces the yield but also affects the quality of
grains or seeds. Prominent high yielding rice varieties like CO 43, CR
1009, ADT 38, ADT 39 and BPT 5204 are found susceptible to this
infestation.
Late planting of rice during kharif and rabi seasons,are more susceptible to this problem.
Management
— Healthy disease free seeds alone should be used for sowing.
— Seeds should not be taken from false smut affected fields.
— At the time of harvesting, infected plants should be removed and destroyed
— Field bunds and irrigation channels should be kept clean.
— Excess application of nitrogenous fertilizer should be avoided.
—
Regular monitoring is very essential. Spraying of copper hydroxide at
2.5 gm per litre of water or propiconazole at 1.0 ml per litre will be
more useful.
Quick sealing of gunshot wounds
A new pocket-sized syringe that can seal gunshot wounds within just fifteen seconds has been developed by scientists.
The syringe Called XStat, developed by Oregon-based RevMedx, injects specially coated sponges into wounds.
The
device could boost survival and spare injured soldiers from additional
pain by plugging wounds faster and more efficiently than gauze,
Popular Science
reported.
“That is what we pictured as the perfect
solution: something you could spray in, it would expand, and bleeding
stops,” said John Steinbaugh, former US Army Special Operations medic.
The team used ordinary sponges and cut them into one-centimetre circles.
They then injected the bits of sponge into an animal injury.
“The bleeding stopped. Our eyes lit up. We knew we were onto something,” said Steinbaugh.
Researchers
settled on a sponge made from wood pulp and coated with chitosan, a
blood-clotting, antimicrobial substance found in shrimp shells.
They
added X-shaped markers that make each sponge visible on an x-ray image
in order to ensure that no sponges are left inside the body
accidentally, the report said.
The sponges expand to fill the entire wound cavity in just 15 seconds, creating enough pressure to stop heavy bleeding.
Since the sponges cling to moist surfaces, they aren’t pushed back out of the body by gushing blood.
“By the time you even put a bandage over the wound, the bleeding has already stopped,” Steinbaugh said.
— PTI
