Scientists build computer from DNA molecules
S
cientists at
the Weizmann Institute,
Israel have built a DNA computer
that is so small that a trillion of them
could fit in a test tube and perform a
billion operations per second with 99.8
per cent accuracy. Instead of using
figures and formulas to solve a
problem, the microscopic computer's
input, output and softwares are made up of DNA molecules, which store and
process encoded information in living
organisms. It is the first programmable
autonomous computing machine in
which the input, output, software and
hardware are all made up of
biomolecules. Scientists see such DNA
computers as future competitors for
their more conventional counterparts
because miniaturization is reaching its
limits and DNA has the potential to be
much faster than conventional computers.
The new model could form the
basis of a DNA computer in the near
future that could potentially operate
within human cells and act as a
monitoring device to detect potentially
disease-causing changes and
synthesize drugs to fix them. It could
even form the basis of computers for
screening DNA libraries in parallel
without sequencing each molecule.
This would speed up the acquisition of
knowledge about DNA, which can
hold more information in a cubic
centimetre than a trillion CDs. The
double helix molecule that contains
human genes stores data on four
chemical bases – known by the
letters
A, T, C and G – giving it
massive
memory capability that scientists are
only just beginning to tap into.
Jan-
Feb, 2002 Vatis Update:
Biotechnology
New family ties to asthma
I
n
addition to environment
factors, asthma has a strong genetic components,
and several chromosomal regions are
linked with susceptibility to asthma and
allergy. By taking advantage of the
similarities between mouse and human
genomes, Jennifer McIntire and co-
workers have identified a new family of
candidate asthma-susceptibility genes.
Asthma is a chronic debilitating
disease that is characterized by airway
hyper reactivity and inflammation.
Allergic asthma is the most common form
of the disease and is thought to result from
immune responses to normally harmless inhaled antigens. This leads
to the accumulation of effector cells, such as
mast cells and eosinophils, and the release
of inflammatory mediators. T-helper type
2 (TH2) responses underpin the development of allergic responses. In this respect, it is intriguing that a region of
human chromosomes 5 associated with
susceptibility to asthma (5q23-35)
contains many genes that regulate TH2-cell
development – including the interleukins
ILA, IL5, IL13, IL9 and IL12p40 – but
none of these has yet been proven to be an
asthma-suscepatibility gene.
Allergen – induced airway
hyperreactivity (AHR) in mice is an
experimental model of asthma. Cogenic
mice strains were generated in which
AHR-susceptible BALB/c mice carry
small segments of chromosomes from resistant
DBA/2
mice. The congenic
mouse strains were then screened for
reduced IL-4 production and resistance to AHR. This approach identified a
susceptibility locus which is homologous
with human 5q33, and has been named
Tapr
(T
cell and airway phenotype
regulator).
Fine mapping of the locus shows
that
Tapr
is
distinct from the IL4 gene cluster, IL12p40, and other candidate genes
found in
the syntenic region of human
chromosomes 5. Positional cloning of Tapr
uncovered a new family of three
genes that are named Tim. Tim1,
Tim2
and Tim3 are transmembrane proteins with
extracellular immunoglobulin-like and mucin-like domains, and an intracellular
tail with tyrosine phosposphorylation sites.
The human homologue of Tim1 is the
hepatitis A virus receptor (HAVR), which
might explain the inverse relationship between HAV infection and allergic
diseases.
Sequencing of Tim1 and Tim3
showed major polymorphisms between the
susceptible and resistant mouse strains.
But how might Tim variants influence TH2
development? The mechanism is
not
clear, but it seems that Tim expression by
activated T cells early in activation might
be crucial in controlling the polarization of
T cells for TH2-cytokine secretion.
January
2002, Nature Reviews
Immunology. Vol. 2
Novel
antibiotic found in human sweat
R
esearchers in Germany have discovered an antimicrobial
peptide produced by human sweat
glands. They believe that this
molecule, called dermcidin, could play
an important part in the first line of
defence against pathogenic
microorganisms that affect the skin. Its
activity might help to explain
observations that link frequent washing
with increased susceptibility to skin
infections. Other mammalian
antimicrobial peptides, called
cathelicidins and B-defensins, are
expressed in human keratincytes in
response to inflammatory stimuli or
injury, “but this peptide is the first one
to be expressed constitutively”, says
Garbe. He suggests that the peptide
might account for the scarcity of skin
infections compared with infection in
other organs. Dermicidin was shown to
have antimicrobial activity against
Escherichia coli, Enterococcus
faecalis, Staphylococcus aureus, and
Candida albicans at pH values and salt
concentrations resembling those in
human sweat. Asked about the possible
application of these findings, Garbe
says: “The obvious thing would be to
synthesise the peptide and use it in
creams…..as there are illness of the
skin which are directly linked
colonisation by bacteria, such as
Pseudomonas aeruginosa”. He
adds
that using a naturally
produced
compound should have the advantage
of not inducing resistance or allergies.
“If we are to produce it by means of
gene technology, we cannot do it in
bacteria because the peptide kills them,
so we are planning to try using plants”,
he concludes.
February
2002, The Lancet Vol. 2
Hand-held device detects fake drugs
A
simple
device that is normally
used to examine urine specimens
can also be used to detect counterfeit
drugs, says Michael Green, who
reported his findings at the American Society of Tropical medicine and
Hygiene’s 50th Annual Meeting
(Atlanta, USA; Nov 11-15). If
someone takes a drug and it doesn’t
work, you’re suspicious. Or, if you’re
very observant, you’ll see that the labelling may be slightly different or
the drug doesn’t took quite right.
Mainly, if the price is a lot lower than
the normal price, then that raises our
suspicions and we’d check it out” adds
Green. But it is not possible to do
detailed investigations of suspect drugs
in less-developed countries that lack
resources and technical expertise. And
so Green and co-workers developed a
simple test using a hand-held
refractometer, a
“low-tech” device
that measures the specific gravity of
urine samples and costs less than
US$100. They realised that by
measuring the specific gravity of
certain dissolved drugs, a drug tester
could ascertain the amount of
active
ingredient in a tablet, and thus detect a
bogus medication. Although the
method cannot identify an unknown
drug, and may not work for all drugs (excipients, buffers, and flavouring
could interfere), it “could be used as a
first line of defense against counterfeit
drugs”.
The tester simply takes a
sample of the medication, pulverises it,
dissolves it in alcohol, and filters out
any remaining solids. A drop of the
clear solution is placed on the
refractometer, which gives the
refractive index. That index can be
converted to specific gravity and
compared with a standard already
established for that particular drug.
January
2002, The Lancet Vol. 2
Never ceasing wonder
A
lready hailed as a wonder drug, the
humble aspirin can also combat
common viruses, reveals research
carried out by Thomas Shenk and his
team at Princeton University in New
Jersey, USA. The researchers have
found that close relatives of aspirin can
block common viruses known as the
human cytomegaloviruses (CMV),
which are members of the family that
causes cold sores and herpes
infections. CMV, present in one tenth
of the population, can cause hearing
problems in babies born to infected
mothers and kill patients with reduced
immunity, such as those suffering from
AIDS. Shenk and his colleagues have
shown that aspirin-like drugs can stop
CMV from replicating in infected
cells. The drugs do this by blocking
production of cyclooxygenase 2, an
enzyme better known as COX-2. The
enzyme helps in the making of
prostaglandin E2, a chemical that
triggers fever and inflammation. But
prostaglandin E2 can be
commandeered by viruses to help them
multiply. Shenk showed that
fibroblasts (taken from human
foreskins) infected with CMV made 50
times more prostaglandin E2 than
normal. But the cells stopped making
E2 as soon as they were exposed to the
aspirin-like drugs. At the same time,
virus production by the cells dropped
100-fold.
March
31, 2002 Down To Earth
Trials on
Alzheimer’s vaccine drug suspended
T
rials of a vaccine against
Alzheimer;s disease, which was being used on 360 people with mild to
moderate disease, have been suspended
after 12 volunteers became seriously
ill. The vaccine, known as AN1792, is
being developed by the Irish based
pharmaceutical company Elan, in
partnership with Wyeth-Ayerst
Laboratories.
March
2, 2002 BMJ Vol. 324
Minimum
standard of care defined for HIV patients with cancer
An
international panel convened by
WHO has drawn up draft
guidelines for a minimum standard of
care for patients with the most
common HIV- associated cancers in
Africa. These are Kaposi’s sarcoma,
non-Hodgkin’s lymphoma and
squamous cell carcinoma of the
conjunctiva. Kaposi’s sarcoma and
non-Hodgkin’s lymphoma are
responsive to treatment but they are
not curable. The only realistic public
health approach to them is palliative
care. The guidelines for this include
advice on human resources,
infrastructure, clinical management,
quality of life, and anti retroviral
therapy.
Bulletin of the World Health
Organization 2002
New research needed for polio
endgame
WHO
has prepared a research agenda to investigate how and
when immunization against polio can be discontinued after polio eradication
is achieved. The WHO Department of
Vaccines and Biologicals is
establishing a steering committee for
this work; its task is to ensure that the
Technical Consultative Group for
Polio Eradication will have the
relevant scientific data on the post-
eradication vaccination policy options. These will be submitted to the World
Health Assembly for a decision. The
budget for the research agenda is
US$ 1 million a year for the next five
years. The following five areas of
research will be covered:
Surveillance for vaccine-derived
polioviruses Effectiveness of inactivated polio vaccine in stopping
transmission
of polioviruses. How to discontinue oral polio vaccination safely if no alternative
vaccine is used Long-term poliovirus excretors Type of vaccine to use for
an
outbreak response in the post immunization era.
World Health Organization 2002
Some plants can reduce pollution
Plants are magic wands that can do wonders to us. Some of them can
even act as “bioremediators” – they
can either absorb or break down
pollution particles into harmless
components. Research about this is
being conducted in many places. The
Hong Kong Baptist University claims
that trees like Leucaena leucocephala
and Acacia confusa can
be used for
restoring landfills. A study conducted
by Lucknow-based National Botanical
Research Institute (NBRI) shows that
mycorhizal fungi present in plant roots
can absorb copper and zinc. The
institute is even attempting to show in
field conditions that chromium can be
removed from soil using plants such as
Scripus lacustris and
Typha latifolia.
Another study carried out by NBRI in
collaboration with the University of Munchen, Germany, shows that
aquatic plants like Hydrilla
verticillata
and Vallisneria spiralis
have enzymes
to detoxify heavy metals like
cadmium, lead and mercury.
However, despite its economic
viability, the technique has failed to
take off. “People are unwilling to grow
bioremediators as they do not give a
cash return,” says Sarita Sinha, a
scientist at NBRI.
March 15, 2002, Down To Earth
Better surveillance needed for second colorectal cancers
Despite
intensive surveillance after
treatment of an initial cancer, the
incidence of second primary colorectal
cancer remains high in patients with a
history of the disease. Green and co-workers analysed
data from 3278 patients with resected
stage II or stage III colorectal cancer
who participated in a multicentre
adjuvant chemotherapy trial that
included surveillance based on current,
but unproven guidelines: colonoscopy
1 year after treatment and every 3-5
years if results are normal.
During 15 245 patient–years of
follow-up, 42 cases of second primary
colorectal cancers developed. The
standardized incidence ratio was 1.6
compared with the Surveillance,
Epidemiology, and End results (SEER)
programme and 6.8 compared with the
National Polyp Study. Paul Limburg (Mayo Clinic,
Rochester, MN, USA) warns that the
high rate of second cancers reflects “a
failure in patient management”, and
stresses that both physicians and
patients “need to do a
better job of
adhering to existing guidelines” for the
detection of synchronous and second
cancers. Colonoscopy is the preferred
method, he notes, but computed
tomography colonography is an option
if colonoscopy can’t be completed
because of an obstructing tumour.
The researchers note that their study does not prove that more frequent
colonoscopy would have improved patients’ outcomes, and that
any recommendations for changes in
surveillance strategies must take into
account the complications and cost of
the technique.
February 23, 2024 The Lancet
Vol. 359
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Cardiovascular risk of diabetes
Two
thirds of people with diabetes
are unaware that they have an
increased risk of cardiovascular
disease and stroke, according to a poll of
2008 diabetic individuals released on Feb 19 by the American Diabetes
Association. Many knew little about steps they could take to decrease
their cardiovascular risk, such as taking aspirin, reducing their cholesterol concentrations, and
stopping smoking.
February 23, 2024 The Lancet
Vol. 359
Vaccine news from the different worlds
t
seems that vaccine development
has never had such a high profile.
With vaccines available against
smallpox and anthrax, how exactly
they should be used to combat the
threat of bioterrorism has been a
subject of debate in the US
press. A
feature in The Washington Post
pointed out that existing vaccines to
potential bioterrorism agents were
“developed decades ago and can cause
severe side effects or even death” and
advised its readers against investing in
vaccine development.
Although acknowledging the risks, Warren Leary, writing in The
New York Times, advocated
voluntary
|vaccination against smallpox – “even if
only part of the population were
vaccinated, the bang for the terrorist’s
buck could be drastically curtailed”.
Meanwhile, ongoing efforts to
develop vaccines for the big killers –
HIV, malaria and tuberculosis – have
not hit the headlines. Although the
BBC World Service did report on
a
“promising” new malaria vaccine
undergoing clinical trial in the Gambia.
The low-key tone was perhaps
appropriate given that the vaccine only
protected 47% of individuals. Another
report from the BBC News provided
a
timely warning that “Weak vaccines
strengthen disease”. This story covered
the predictions of Edinburgh based
epidemiologists that, in the case of
chronic diseases, such as malaria,
vaccines that are less than 100%
effective have the potential to do more
harm than good. Specifically, vaccines
that only protect a proportion of the
population could lead to outbreaks of
more virulent forms of disease and the
news article claims that this “could kill
more people that any vaccination
programme would save”.
January 2002, Nature Reviews
Immunology. Vol. 2
Manufacturing snRNPs
Spinal muscular atrophy is genetic
disease in which motor neurons in
the spinal cord degenerate. The protein
encoded by this gene is called survival
of motor neurons (SMN) and is one
component of the large multiprotein
SMN complex. Diverse cellular
processes rely on RNA-protein
assemblies, and the SMN complex is
involved in the orderly construction of
the small nuclear ribonucleoprotein
particles (snRNPs) involved in pre-
messenger RNA splicing.
Yong et al.
show that the
SMN complex recognizes one of the
four stem loops (SL1) of the U1 snRNA and that this region is
necessary and sufficient for SMN complex interaction. A distinct region is
responsible for gathering the Sm proteins, which form a heteroheptameric
ring encircling the snRNA; together they comprise the core of the U1 snRNP.
Some Sm proteins contain an Arg-Gly motif, and a separate complex, called
the methylosome, uses the protein methyltransferase PRMT5 to N-methylate
the arginine symmetrically, as shown by Freisen et
al. and Meister et al. The
resulting dimethylarginine is recognized
by SMN, facilitating the supply of Sm proteins to the SMN complex.
March 15,2002, Science Vol. 295
Mapping the fission yeast
Scientist
have mapped all the genes of the fission yeast (Schizosaccharomyces
pombe), which
they hope will provide new insights into basic cell biology. An
international team led by Paul Nurse of Cancer
Research Centre, the UK, has done the sequencing, S. pombe is the sixth organism to have its genome
sequenced. The others include humans, the nematode worm, the fruit fly and
mustard weed. The sequencing is being considered significant as 50 of the
4,824 genes in the yeast are linked to human diseases such as cystic
fibrosis, hereditary deafness, diabetes and cancer.
March 31, 2024 Down To
Earth
Predicting cancer
A simple
blood test might be used
successfully to predict the chances of a person contracting lung cancer.
Researchers at Columbia University, New York, USA, used blood samples that
had been collected 13 years ago and found that people whose white blood
cells were damaged were at a higher risk of getting cancer. According to the
group of researchers, this damage is mainly due to exposure to polycyclic
aromatic hydrocarbons (PAH), which binds to the genetic material. The group
measured this bound PAH. While tobacco smoking releases PAH, they are also
emitted from cars, power plants and during the process of cooking certain
food.
February
15, 2002 Down To Earth
Were you born intelligent?
Recent research claims that the
intellectual ability is influenced
greatly by environment and may not be hereditary. Psychologist Dennis
Garlick, of the University of Sydney in Australia, suggests that
intelligence is created when neural connections in the brain are
changed in response to environmental cues. According to Garlick, recent
advances in neuroscience and cognitive science have suggested that different
intellectual abilities require different neural connections in the brain.
Thus, environmental conditions that allow favourable connections
to be developed lead to a better intellect.
February
15, 2002 Down To Earth
Lens solution is no solution
Common types of contact lens solutions may leave
behind remnants of a micro-organism that can cause a potentially serious eye
infection, say Austrian researchers. They suggest that contact lens wearers
doubly protect themselves by not only disinfecting their lenses, but
also ensuring that their contacts’ storage cases are very clean. A
multi-purpose solution and a one-step hydrogen peroxide solution fails
to expunge the tiny organism Acanthamoeba,
that can cause an inflammatory condition in the cornea
called keratitis. Infrequently,
the infection can lead to blindness.
April, 2002 Health Action
Pressure tactics
Nearly nine out of 10 people who had acupuncture
for physical ailments say the treatment relieved their pain, according to
preliminary results of a large German study. The study, involving some
40,000 patients, is the largest acupuncture study ever undertaken,
according to the researchers. Study coordinator Dr. Hans-Joachim
Trampisch from the Ruhr-University of Bochum said that in his
opinion, previous studies on acupuncture did not involve enough
patients or were not conducted scientifically. “I am a medical
statistician,” he said. “I am not an advocate of acupuncture.”
Of the patients in the study, almost 90 per cent claimed that
acupuncture treatments had resulted in relief from pain,
according to a press release. Of those patients, around half
suffered from back pain, and the rest from headaches and a
degenerative disease of the joint. The average age of study
participants was around 58 years.
April,
2002 Health Action
New
rabies vaccine for India
The development of an indigenous cell culture
vaccine for rabies at the Pasteur Institute of India at Coonoor, south
India, promises to deliver a safe vaccine for the local population. Of the
approximately 60,000 people who die of rabies annually worldwide, 3000 are
from India alone. The vaccine
will be similar to the one called “Abhayrab” which was developed last
year in Ootacamund (also in south India) by the Human Biological
Institute, a unit of the National Dairy Development Board. It is produced
with the vero-cell lines as a substrate. These are cell lines derived from kidney cells of the vervet
monkey. “Vero vaccines are considered to be safe by the WHO, with the recommendation that the
DNA content of the vaccine be less than 300/pg/dose,” says S N
Madhusudan, Associate Professor of
Neurovirology at the National Institute of Mental Health and Neurosciences,
Bangalore. Although there are no data on the actual potency of the vaccine,
Madhusudan is optimistic that it will
be more than 2.5 IU/mL (the required potency).
“About half the rabies vaccines
used in India currently are the simple sheep-brain rabies vaccine” he adds.
These vaccines are cheap, but are painful (ten subcutaneous injections of
5 ml each), and carry the rare but
serious potential risk of demyelinaton. The imported vero cell line
vaccines are commonly used in the cities but are more expensive at around
US$33 for the whole course. The new tissue culture vaccine on the other
hand, should be available for about $
15 since the Pasteur is a government
institute that operates on a not-for-
profit basis.
September 2001, The Lancet
Warning on Serzone
The FDA has issued
a warning that cases of life-
threatening hepatic
failure have been
reported in patients
using nefazodone hydrochloride
(Serzone, Bristol-Myers Squibb,
Princeton, NJ), a
treatment for depression. Patients taking Serzone
should be advised
to report signs and
symptoms of liver
dysfunction such as jaundice,
anorexia, or gastrointestinal complaints to
their physician immediately. If
they develop evidence of hepatocellular
injury, such as increased serum aspartate
aminotransferase
or serum alanine at
levels three
times or higher than the upper limit of normal, they should be
withdrawn from
the drug and should
not be considered
for re-treatment.
March 6, 2024 JAMA
Vol. 287
Drug for pediatric liver disease
T
he FDA has
approved nitisinone capsules for use
as an adjunct to dietary
restriction of tyrosine and
phenylalanine in
the treatment of
hereditary
tyrosinemia type 1 (HT-1).
Nitisinone was studied in
more than 200 patients
whose median age was 9 months when
therapy started. The drug’s
effectiveness was inferred by its
effect on
reduction of concentration of
succinylacetone in plasma and urine
to a level below the reference limit,
and by normalization of erythrocyte
porphobilinogen synthase
activity. Resulting improvements in
these indices were statistically
significant (P<.001).
When the drug was combined with
a restricted
dietary intake of tyrosine and phenylalanine,
the 4-year survival rate of children
under 2 months of age at the time of
diagnosis was 88% compared with a
survival rate of 29% for
children
treated with dietary restrictions
alone. The most common adverse effects
of nitisinone (such as corneal opacity,
keratitis, and photophobia, 2%
each) were related to high tyrosine
levels caused by dietary indiscretion.
March 6, 2024 JAMA Vol. 287
Mango a valuable food medicine
The Mango is used
as food in all stages of its
development. Green or unripe mango is a
rich source of starch and pectin and a
fair source of vitamin B1, B2
and niacin. It is sour in
taste because of the
presence of oxalic, citric, malic and
succiniac acids. The ripe fruit is very wholesome and nourishing .
The chief food ingredient of
mango is sugar. An analysis of the
ripe mango shows it to consist of
moisture 81.10 %, Protein 0.6%, fat
0.4%, , fiber 0.7% and carbohydrate
16.9% per 100 grams of edible portion.
Its mineral and vitamin contents are
calcium 14mg. % phosphorus 16mg.
%, iron 1.3mg.%, carotene 2743mcg,
thiamine 0.08mg, riboflavin
0.09mg, niacin 0.9 mg. And vitamin C 16.0
mg.% / 100 grams. The average energy
value of mango is about 74
calories. The unripe fruit is acidic,
astringent and
antiscorbutic. The ripe mango is antiscorbutic, diuretic, laxative,
invigorating, fattening and astringent. It
gives tone to the heart,
improve
complexion and stimulate
appetite. The
unripe mango protect from the adverse
effects of hot, scorching winds.
A drink prepared from the unripe
mango by cooking it in hot ashes and
mixing the pith with sugar and water,
is an effective remedy
for heat
exhaution and heat stroke. Unripe green
mangoes are beneficial in the
treatment of gastro-
intestinal
disorders. Eating one or two mangoes in which
seeds are not fully formed with salt
and honey is found to be very effective
medicine for summer diarrhoea,
dysentery, piles, morning
sickness, chronic
dyspepsia, indigestion and constipation. Ripe mangoes are beneficial in the
treatment of
night blindness. Liberal use of mangoes
during the season will be very
effective
and will prevent development of
refractive errors,
dryness of the
eyes, softening of the cornea, itching
and burning in the eyes. All bacterial invasions are due to
poor epithelium.
Liberal use of mangoes during
the season contributes towards formation
of healthy epithelium, there
by preventing frequent attacks
of common infections such as cold,
rhinitis and sinusitis. The tender leaves of the mango
tree are considered useful in diabetes. An infusion is
prepared for fresh leaves by soaking
them overnight and squeezing them
well in water in the morning. This
filtrates should be taken every morning to
control early
diabetes.
April 2000, Nisargopchar
Varta
Vol. 4
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