If he had not been harassed every time to take an X-ray to prove that he was not the
host of some latent tuberculosis,
Purvesh Khatri might not have
come up with a new test to identify those with the active form of
“Every time, I had to do anything with my daughter’s school
they would ask me to get the TB
(Mantoux) test done — that I’m
negative,” Khatri, assistant professor of medicine at Stanford
University, told India Abroad.
The test relies on a rash developing as a result of the body
reacting to sub-dermal injection
of a small amount of tuberculin,
an extract from the bacterium
that causes tuberculosis. The idea
is that if the body is familiar with
TB, it will react to the tuberculin with a more spectacular
rash — one beyond 10 mm in diameter in a normal person
– is asked to take an X-ray to preclude the possibility of
“The current test is nonsensitive and non-specific,” he
said, pointing out that most Indians who have taken the
BCG vaccine in their childhood are sensitized to tuberculin, and so Mantoux tests on them throw up false positives.
Despite this, Khatri tested negative the first two times he
“Now every time they do it, it (shows up as) positive
because I have a very strong immune response,” he said.
“I’ve been tested one time too many.”
Finally, Khatri had enough.
“The last time was the worst,” Khatri said. “They would
just not agree that I had been vaccinated (and so showed a
strong immune response). They kept saying, ‘You have
latent TB, sir.’ And that just got on my nerves.”
Khatri told the clinic staff, ‘No, it’s because you’ve been
testing me that I’m now positive.’ It made no difference.
He can’t stop laughing as he admits, “That was the very
personal motivation for doing
this.” But as most people are wont
to, Khatri did not kick an avail-
able dustbin and go off in high
dudgeon, muttering ‘idiots’ or
worse under his breath. For, his
own lab works on infectious dis-
Khatri’s team uses publicly
available data to find sensitive
and specific diagnostics and ther-apies for different diseases.
When they turned to TB, they
were looking at how the immune
system responded when faced
with a pathogen like the tuberculosis bacteria. They found there
were responses common to a
group of pathogens, and some
pathogen-specific responses – in
this case, for TB.
Specifically, they found three
genes – GBP5, DUSP3, and
KLF2 – that were producing proteins in those people who had active tuberculosis. Though
these genes could all come on in patients with certain other
diseases, their activity could be used as a triage test, to tell
investigators to run other TB tests on these patients.
“What we have found – and this is not conclusive yet;
there’s just a hint – is that our signature (the three active
genes) is enriched in M1 macrophages (a kind of white
blood cell), which releases (germ-fighting) interferon
gamma,” he said. Interferon gamma release is seen primarily in active TB, when the immune response is high, and
not in the latent form of the disease.
Though HIV suppresses certain types of immune system
cells called T-cells, it has only a minor effect on the signature the Khatri team to locate people with active TB.
Because the team had already experiences with diagnostics with in other conditions – such as sepsis – or predicting
vaccine response to influenza, the work on distinguishing
changes produced by active TB was easier. They relied on
1,023 blood data sets from people of all ages from places as
diverse as Malawi and Kenya and the United Kingdom.
The advantages of the test include the fact that it works in
children, and that it relies on blood and not sputum. This
is important because when people begin treatment for TB
they become asymptomatic and can’t generate enough spu-
tum for the test.
“None of the treatments today can monitor treatment
response,” said Khatri, adding that his team’s analysis suggests it could do just that. “What we have been able to
show… is that as the patient goes through treatment the
score reduces, and at the end treatment, it looks like a
healthy person’s score,” he said.
Khatri optimistically expects that, FDA willing, the
Khatri test could be routinely used for monitoring TB in
about three years.
About future work, Khatri said his lab is focused on
translational medicine, including such cutting-edge areas
of research as broad-spectrum antiviral drugs, which do
not exist yet.
Khatri — the son of Jayantilal, a bank manager and
Ranjan — grew up all over Gujarat, thanks to his father
having a transferable job. “They really pushed for science,”
he said, adding that they told him, ‘Just be honest with
what you do. Make sure you never hurt anybody. Make sure
you can help people out.’
Khatri earned his undergraduate degree in communica-
tions and electronics engineering from Sardar Patel
University in Vallabh Vidya Nagar, Anand district, Gujarat.
“My dad never thought I would be a researcher. He wanted
me to become a mechanical engineer,” Khatri said, explain-
ing that computers was just coming up when he began
studying them more than 20 years ago.
He came to Michigan to study computer science at
Wayne State University but found he wanted to do a little
more. “I moved into bioinformatics when I was a master’s
student because I couldn’t do programming for the rest of
my life,” Khatri said, suppressing a laugh. “I was still programming, but programming with some purpose. I developed tools that would allow us to analyze biomedical data.”
“I’ve been switching careers every four years or so,” he
said, laughing. “I’m finally settled on translational research
in immunology. We’ll see how long that lasts, but right now
that’s what I’m doing.”
A Khatri blood test could finally rein in TB
Travelers flying into India and not carrying dutiable goods won’t need to fill the Customs declaration form. Only travelers with prohibited and dutiable goods need to fill the once mandatory declaration form.
w Foreign travelers’ duty free allowance has also been increased to Rs 15,000 from the existing Rs 8,000, from April 1. w The duty free allowance of two liters of liquor or wines, 125 cigarettes, 50 cigars and 125 grams tobacco for passengers will continue. w The increase in allowance is applicable only to pas- sengers traveling by air. w Male Indian passengers, who have lived abroad for over one year, can bring gold jewelry of up to 20 grams with a value cap of Rs 50,000. Lady passen- gers can carry 40 grams of gold jewelry with a value cap of Rs 100,000.
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in India from April 1 along with providing them with opportu-
nities to grow.
“I bring a different perspective largely
due to the fact that I come from a different
generation than the other candidates and
councilmembers. That brings a new way
of thinking to the table. I want to work
with the residents to ensure a better
future for Cupertino,” he says.
Won’t the campaign be a huge challenge
for him? Parth says he has received overwhelming support from residents.
“When I decided I wanted to run for city
council I talked to many community lead-
ers and residents. I am fully aware that
this election will be challenging but I
decided to run and am confident that I
can come out ahead because of how I have
differentiated myself from the other can-
What are the big issues in this election?
Parth says Cupertino confronts a split opinion between residents on whether the city
should continue developing or if they need
to rethink certain large-scale development
projects such as the Vallco shopping mall.
Many residents are concerned about the
new projects being proposed because they
believe it will overcrowd schools and cause
more traffic while taking away from the
suburban environment that Cupertino provides.
“Traffic is one of the biggest concerns,
especially since Apple is adding thousands
of jobs in Cupertino with its new building.
Cupertino should focus on growth that is
sustainable. Many of these proposed proj-
ects will change the landscape of Cupertino
for decades to come.”
“I think there needs to be a more open
discussion between the residents and the
city,” says Parth, “where all the pros and
cons are laid out and discussed. My dreams
for the future include continuing on with
politics, hopefully moving forward to repre-
sent my district, state, and even country
The boy who wants to be president