suspended animation
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RESUME
> > T H E S T U D Y O F S U S P E N D E D A N I M A T I O N
100
090
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030
020
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AL
L R
IGH
T R
ES
ER
VE
D
NO
PA
RT
OF
TH
IS B
OO
K M
AY
BE
US
ED
OR
RE
PR
O-
DU
CE
D I
N A
NY
FO
RM
OR
BY
AN
Y E
LE
CT
RO
NIC
OR
M
EC
HA
NIC
AL
M
EA
NS
, IN
CL
UD
ING
IN
FO
RM
AT
ION
S
TO
RA
GE
A
ND
R
ET
RIE
VA
L
SY
ST
EM
S,
WIT
H-
OU
T P
ER
MIS
SIO
N I
N W
RIT
ING
FR
OM
TH
E C
OP
Y-
RIG
HT
OW
NE
RS
, E
XC
EP
T B
Y A
RE
VIE
WE
R W
HO
MA
Y Q
UO
TE
BR
IEF
PA
SS
AG
E I
N A
RE
VIE
W.
\\
PR
INT
ED
IN
US
A
SUSPENDED ANIMATION IS THE SLOWING DOWN OF LIFE PROCESS BY EXTERNAL MEANS WITHOUT TERMINATION.”
“
SUSPENDED ANIMATION IS THE SLOWING DOWN OF LIFE PROCESS BY EXTERNAL MEANS WITHOUT TERMINATION.”
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SLO W I N G
LIFE
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SLO W I N G
LIFE
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IN
TR
OD
UC
TIO
N
Sus
pen
ded
an
imat
ion
is
the
pro
cess
of
slow
ing
met
abol
ism
and
oth
er a
ctiv
ity
asso
ciat
ed w
ith
liv-
ing
thro
ugh
exte
rnal
mea
ns (
such
as
appl
ying
col
d)
wit
hout
cau
sing
dea
th. T
his
idea
has
led
to a
ll so
rts
of s
cien
ce f
icti
on a
pplic
atio
ns o
f su
spen
ded
anim
a-ti
on,
the
mos
t co
mm
on e
xam
ple
is p
utti
ng t
he i
dea
of p
utti
ng a
stro
naut
s in
sus
pend
ed a
nim
atio
n du
r-in
g sp
ace
flig
hts
of in
cred
ibly
long
dur
atio
n.
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TH
IS I
S N
OT
CR
YO
NIC
S
Whe
n pe
ople
typ
ical
ly t
hink
of
susp
ende
d an
imat
ion
and
life
exte
nsio
n, t
hey
ofte
n ge
t co
nfus
ed b
etw
een
susp
ende
d an
imat
ion
and
the
idea
of
cryo
nics
. +
In c
ryon
ics,
a p
erso
n is
lite
rally
fro
zen
usin
g liq
uid
nitr
ogen
. The
per
son
tech
nica
lly d
ead.
The
cry
onic
s pr
opon
ents
bel
ieve
tha
t, a
s te
chno
logy
dev
elop
s, a
fr
ozen
per
son
cold
be
rean
imat
ed, o
r br
ough
t ba
ck
to li
fe. S
ome
peop
le h
ave
chos
en t
o ha
ve t
heir
bod
ies
froz
en a
t th
e m
omen
t of
dea
th u
sing
cry
onic
s w
ith
the
idea
tha
t, d
ecad
es o
r ce
ntur
ies
from
now
, the
y co
uld
be r
eani
mat
ed a
nd t
he c
ause
of
thei
r de
ath
can
be t
reat
ed. I
wou
ld s
ay t
his
is s
cien
ce f
icti
on,
expe
ct t
hat
the
free
zing
par
t ha
s al
read
y ha
ppen
ed,
wha
t ha
sn’t
hap
pene
d is
tha
t w
hole
rev
ivin
g a
nd
trea
ting
par
t in
the
fut
ure.
\\
EX
TE
ND
ING
LIF
E
Sus
pend
ed a
nim
atio
n is
an
enti
rely
dif
fere
nt t
hing
. D
octo
rs a
re lo
okin
g in
to t
he p
ossi
bilit
ies
of p
laci
ng
a pe
rson
in a
sta
te o
f su
spen
ded
anim
atio
n du
ring
ce
rtai
n su
rgic
al p
roce
dure
s to
, in
esse
nce,
buy
tim
e to
fix
thi
ngs.
Not
onl
y th
at, b
ut t
here
are
als
o ot
her
way
s to
ach
ieve
sus
pene
d an
imat
ion
than
sim
ply
mak
ing
a bo
dy c
old
(suc
h as
hyd
roge
n su
lfid
e ga
s in
th
e co
rrec
t do
sag
e w
hich
sus
pend
s th
at n
eed
for
oxyg
en in
the
bod
y). T
here
has
bee
n re
sear
ches
in
whi
ch a
nim
als
wer
e re
anim
ated
aft
er b
eing
in
a “t
echn
ical
ly d
ead”
sta
te f
or t
hree
hou
rs. T
his
line
of
rese
arch
is f
unde
d by
the
Nat
iona
l Ins
titu
tes
of H
ealt
h an
d ot
her
scie
ntif
ic o
rgan
izat
ions
.
+
If s
uspe
nded
an
imat
ion
can
be d
evel
oped
for
use
in
trau
ma
and
othe
r se
vere
sit
uati
ons,
it
wou
ld h
ave
the
pote
n-ti
al
to
incr
ease
th
e su
rviv
al
rate
fr
om
thes
e pr
oced
ures
, th
ereb
y ex
tend
ing
lif
e. T
his
line
of
rese
arch
cou
ld h
ave
a va
riet
y of
hel
pful
app
lica-
tion
s, i
nclu
ding
su
stai
ning
th
e fu
ncti
on o
f or
gans
of
cri
tica
lly i
ll pe
ople
, Ic
hino
se s
aid.
It
may
als
o be
po
ssib
le t
o us
e th
e fi
ndin
g fo
r pa
tien
ts u
nder
goin
g su
rger
y.
+
This
wou
ld b
e an
adv
ance
, be
caus
e an
esth
esia
usu
ally
cau
ses
bloo
d pr
essu
re t
o dr
op.
Cur
rent
ly h
ypot
herm
ia i
s th
e on
ly p
rove
n w
ay t
o de
crea
se m
etab
olic
rat
e an
d co
nfer
som
e pr
otec
-ti
on w
hen
bloo
d fl
ow t
o th
e or
gans
is
impa
ired
or
purp
osel
y re
duce
d. H
owev
er, h
ypot
herm
ia h
as s
ome
adve
rse
effe
cts,
incl
udin
g de
pres
sing
car
diov
ascu
-la
r fu
ncti
ons
and
bloo
d cl
otti
ng. I
f w
e ca
n fi
gure
out
ho
w h
ydro
gen
sulf
ide
redu
ces
met
abol
ic r
ate
wit
h-ou
t de
pres
sing
myo
card
ial f
unct
ion,
we
may
be
able
to
red
uce
met
abol
ism
and
pro
tect
org
ans
wit
hout
us
ing
hypo
ther
mia
.
H E A R T R A T E D E C R E A S E D
B R E A T H I N G R A T E
D E C R E A S E D
C O R E B O D Y T E M P E R A T U R E
D E C R E A S E D
A C T I V I T Y L E V E L
D E C R E A S E D
B L O O D P R E S S U R E
N O R M A L
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R E D U C E D I N M E T A B O L I C R A T E
SUSPENDED ANIMATION COULD CONVERT NEAR CERTAIN DEATH TO 90% SURVIVAL.
PH
YS
ICA
L P
RO
PE
RT
IES
ME
LT
ING
P
OIN
T
CH
EM
ICA
L P
RO
PE
RT
IES
BO
ILIN
G
PO
INT
Ga
s
Ac
idic
-82
°C
-60
°C
Co
lor
les
s
Po
iso
no
us
Fla
mm
ab
le
19
1 K
21
3 K
-11
6°
F
-76
°F
N A M E
HYDROGEN SULPHIDE
D E N S I T Y
C A S N O . U N I T
7783-06-4 YY9FVM7NSN
S
H H
M O L E C U L A R F O R M U L A M O L E C U L A R M A S S
34.08g mol^-1
92.1°0.001363g cm^-3
KEY INGREDIENT: HYDROGEN SULPHIDE
Hydrogen sulfide is the chemical compound with the formula H S. It is a color-less, very poisonous, flammable gas with the characteristic foul odor of rotten eggs at concentrations up to 100 parts per million. It often results from the bacterial breakdown of organic matter in the absence of oxygen, such as in swamps and sewers. It also occurs in volcanic gases, natural gas, and some well waters. The human body produces small amounts of H S and uses it as a signaling molecule. +Hydrogen sulfide is slightly heavier than air; a mixture of H S and air is explosive. Hydrogen sulfide and oxygen burn with a blue flame to form sulfur dioxide (SO ) and water. In general, hydrogen sulfide acts as a reducing agent.
2
2
2
2
H S
H S2
2
+
+
+
+
+
+
+
+
HY
DR
OG
EN
S
ULP
HID
E IS
ALS
O
PR
OD
UC
ED
B
Y S
OM
E
CE
LLS
OF
T
HE
HU
MA
N
BO
DY
IN
S
MA
LL
AM
OU
NT
S
AN
D H
AS
A
NU
MB
ER
O
FB
IOLO
GIC
AL
SIG
NA
LLIN
G
FU
NC
TIO
NS
H S2 H S2 H S2
Hydrogen sulfide is most commonly obtained by its separation from sour gas, which is natural gas with high content of H S. It can also be produced by reacting hydrogen gas with molten elemental sulfur at about 450°C. Hydrocarbons can replace hydrogen in this process. +Sulfate-reducing bacteria generate usable energy under low-oxygen conditions by using sulfates to oxidize organic compounds or hydrogen; this produces hydrogen sulfide as a waste product. +The standard lab prepartion is to gently heat ferrous sulfide (FeS) with a strong acid in a Kipp generator. FeS + 2HCl > FeCl + H S. A less well-known and more convenient alternative is to react aluminium sulfide with water: 6 H O + Al S > 3H S + 2Al(OH) +This gas is also produced by heating sulfur with solid organic compounds and by reducing sulfurated organic compounds with hydrogen. Hydrogen sulfide is also a by product of some reactions and caution should be taken when production is likely as exposure can be fatal.
Small amounts of hydrogen sulfide occur in crude petroleum, but natural gas can contain up to 90%. Volcanoes and some hot springs (as well as cold springs) emit some H S, where it probably arises via the hydrolysis of sulfide minerals. For example, MS + H O > MO + H S. +About 10% of total global emissions of H S is due to human activity. By far the largest industrial route to H S occurs in petroleum refineries: The hydrodesulfurization process liberates sulfur from petroleum by the action of hydrogen. The resulting H S is converted to elemental sulfur by partial combustion via the Claus process, which is a major source of elemental sulfur. Other anthropogenic sources of hydrogen sulfide include coke ovens, paper mills (using the sulfate method), and tanneries. H S arises from vir- tually anywhere where elemental sulfur comes in contact with organic material, especially at high temperatures. +Hydrogen sulfide can be present naturally in well water. In such cases, ozone is often used for its removal; an alternative method uses a filter with manganese dioxide. Both methods oxidize sulfides to much less toxic sulfates.
Hydrogen sulfide is considered a broad-spectrum poison, meaning that it can poison several different systems in the body, although the nervous system is the most affected. The toxicity of H S is comparable with that of hydrogen cyanide. It forms a complex bond with iron in the mitochondrial cytochrome enzymes, thus preventing cellular respiration. +Since hydrogen sulfide occurs naturally in the body, the environment and the gut, enzymes exist in the body capable of detoxifying it by oxidation to (harmless) sulfate. Hence, low levels of hydrogen sulfide may be tolerated indefinitely. At some threshold level, believed to average around 300–350 ppm, the oxidative enzymes become overwhelmed. Many personal safety gas detectors, such as those used by utility, sewage and petroche- mical workers, are set to alarm at as low as 5 to 10 ppm and to go into high alarm at 15 ppm. +An interesting diagnostic clue of extreme poisoning by H S is the discoloration of copper coins in the pockets of the victim. Treatment involves immediate inhalation of amyl nitrite, injections of sodium nitrite, inhalation of pure oxygen, administration of bronchodilators to overcome eventual bronchospasm, and in some cases hyperbaric oxygen therapy (HBO). HBO therapy has anecdotal support and remains controversial. +Exposure to lower concentra- tions can result in eye irritation, a sore throat and cough, nausea, shortness of breath, and fluid in the lungs. These effects are believed to be due to the fact that hydrogen sulfide combines with alkali present in moist surface tissues to form sodium sulfide, a caustic. These symptoms usually go away in a few weeks. Long-term, low-level exposure may result in fatigue, loss of appetite, headaches, irritability, poor memory, and dizziness. Chronic exposure to low level H S (around 2 ppm) has been implicated in increased miscarriage and reproductive health issues among Russian and Finnish wood pulp workers, but the reports have not been replicated.
Hydrogen sulfide is produced in small amounts by some cells of the mammalian body and has a number of biological signaling functions. (Only two other such gases are currently known: nitric oxide (NO) and carbon monoxide (CO)). The gas is produced from cysteine by the enzymes cystathionine beta-synthase and cystathionine gammalase. It acts as a relaxant of smooth muscle and as a vasodilator and is also active in the brain, where it increases the response of the NMDA receptor and facilitates long term potentiation, which is involved in the formation of memory. Eventually the gas is converted to sulfite in the mitochondria by thiosulfate reductase, and the sulfite is further oxidized to thiosulfate and sulfate by sulfite oxidase. The sulfates are excreted in the urine. +Due to its effects similar to nitric oxide, hydrogen sulfide is nrecognized as potentially protecting against cardiovascular disease. The cardioprotective role effect of garlic is caused by catabolism of the polysulfide group in allcin to H S, a reac- tion that could depend on reduction mediated by glutathione. +Though both nitric oxide and hydrogen sulfide have been shown to relax blood vessels, their mechanisms of action are different: while NO activates the enzyme guanylyl cyclase, H S activates ATP-sensitive potassium channel in smooth muscle cells. Researchers are not clear how the vessel-relaxing responsibilities are shared between nitric oxide and hydrogen sulfide. However, there exists some evidence to suggest that nitric oxide does most of the vessel relaxing work in large vessels and hydrogen sulfide is responsible for similar action in smaller blood vessels.
\ \ P R O D U C T I O N
\ \ T O X I C I T Y
\ \ O C C U R R E N C E
\ \ F U N C T I O N I N T H E B O D Y
22 2
22
2
2
2
2
2
2
2
2 2 23 3
2 2
2
LOW
DO
SE
S O
F H
YD
RO
GE
N S
ULP
HID
E,
TH
E S
EW
ER
GA
S,
CA
N S
AF
ELY
SLO
W D
OW
N B
OT
H M
ETA
BO
LIS
M A
ND
SO
ME
CA
RD
IOV
AS
CU
LAR
FU
NC
TIO
N,
PR
OD
UC
ING
A S
US
PEN
DED
AN
I-
MA
TIO
N L
IKE
STA
TE T
HA
T IN
CLU
DE
A S
UB
STA
NTI
AL
DEC
REA
SE
IN H
EAR
T R
ATE
WIT
HO
UT
A D
RO
P IN
BLO
OD
PR
ESS
UR
E.
H
S I
ND
UC
ES
A
SU
SP
EN
DE
D A
NIM
AT
ION
LI
KE
STA
TE
IN
MIC
E
2
+ + + + + + + +
MICE
0 0 1 0 2 0 3 0 4 0 5 0 6 0
+ + + + + + + +
MICE
Pre
viou
s in
vest
igat
ions
int
o th
e ef
fect
s of
low
-dos
e hy
drog
en s
ulfi
de s
how
ed
that
the
gas
cou
ld l
ower
bod
y te
mpe
ratu
re a
nd m
etab
olic
rat
e an
d al
so i
m-
prov
ed s
urvi
val
of m
ice
who
se o
xyge
n su
pply
had
bee
n re
stri
cted
. But
sin
ce
hypo
ther
mia
its
elf
cuts
met
abol
ic n
eeds
, it
was
unc
lear
whe
ther
the
red
uced
bo
dy t
empe
ratu
re w
as r
espo
nsib
le f
or t
he o
ther
obs
erve
d ef
fect
s. T
he c
urre
nt
stud
y w
as d
esig
ned
to i
nves
tig
ate
both
tha
t qu
esti
on a
nd t
he e
ffec
ts o
f hy
drog
en s
ulfid
e in
hala
tion
on
the
card
iova
scul
ar s
yste
m.
+Th
e re
sear
cher
s m
easu
red
fact
ors
such
as
hear
t ra
te,
bloo
d pr
essu
re,
body
tem
pera
ture
, re
spir
atio
n an
d ph
ysic
al a
ctiv
ity
in n
orm
al m
ice
expo
sed
to lo
w-d
ose
(80
ppm
) hy
drog
en s
ulfi
de f
or s
ever
al h
ours
. The
y an
alyz
ed c
ardi
ac f
unct
ion
wit
h el
ectr
o-ca
rdio
gram
s an
d ec
hoca
rdio
grap
hy a
nd m
easu
red
bloo
d ga
s le
vels
. Whi
le s
ome
mic
e w
ere
stud
ied
at r
oom
tem
pera
ture
, oth
ers
wer
e ke
pt in
a w
arm
env
iron
men
t ab
out
98º
F to
pre
vent
the
ir b
ody
tem
pera
ture
s fr
om d
ropp
ing.
T H E M I C E W E R E P U T I N
A C H A M B E R F I L L E D W I T H
A I R L A C E D W I T H 8 0
P A R T S P E R M I L L I O N O F
H Y D R O G E N S U L P H I D E
7 0 8 0
Dea
th i
sN
’T c
au
sed
by
ox
ygen
de-
p
riv
ati
on
its
elf,
bu
t b
y a
ch
ain
of
da
ma
gin
g c
hem
ica
l r
eac
tio
ns
th
at
ar
e tr
igg
ered
by
sh
ar
ply
dr
op
pin
g
ox
yg
en
le
ve
ls.
Re
ce
nt
re
se
ar
ch
h
as
sh
ow
n t
hat
hyd
ro
gen
su
lph
ide
ca
n i
nd
uc
e a
su
sp
end
ed a
nim
ati
on
li
ke s
tate
wh
ere
hyd
ro
gen
su
lfid
e ta
kes
th
e p
lac
e o
f o
xyg
en, p
rev
en-
tin
g t
ho
se
dea
dly
rea
cti
on
s f
ro
m
tak
ing
pla
ce.
As
a r
esu
lt,
no
ch
ain
r
eac
tio
n,
no
cel
l d
eath
. Th
is s
ug
- g
es
ts
th
e p
os
sib
ilit
y o
f in
du
cin
g
su
sp
en
de
d a
nim
at
ion
-lik
e s
tat
es
fo
r m
edic
al
ap
pli
ca
tio
ns
in t
he
fu-
tu
re
to
pr
ev
en
t t
iss
ue
da
ma
ge
; d
eath
in
str
ok
e o
r h
ear
t a
tta
ck
vic
tim
s;
pr
eser
ve
tra
ns
pla
nta
ble
o
rg
an
s f
or
lo
ng
er;
bu
y ti
me
for
h
um
an
tr
au
ma
pa
tien
ts.
HYDROGEN SULPHIDE+ OXYGENW H A T W O U L D H A P P E N ?
Hydrogen sulfide binds with iron in cytochrome enzymes, disrupting a critical step in a process called oxidative phosphorylation, in which oxygen is burned to produce energy in the form of a substance called ATP. By blocking oxygen from binding to the iron, hydrogen sulfide stops cellular respiration and energy production completely. When energy production is inhibited, body temperature and metabolic rate are severely reduced. Enzymes exist in the body that can detoxify hydrogen sulfide by oxidation to (harmless) sulfate. As a result, low levels of sulfide may be tolerated indefinitely. +When the oxygen levels are too low for respiration but high enough to allow metabolic activity, damage occurs because the cells continue to struggle to live. Under these conditions, seizures, cell death, coma and finally death can occur. However, decreasing the oxygen levels significantly stops all metabolic activity and the animals enter the state of suspended animation.
W E A L L N E E D O X Y G E N T O L I V E. I F Y O U D O N ’ T G E T I T F O R A F E W M I N U T E S Y O U D I E . B U T S O M E T H I N G E L S E I S G O I N G O N I N S I D E T H I S R AT. H E I S N ’ T D E A D .
H2S + O2 = SUSPENDED ANIMATION
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TH
E E
XP
ER
IME
NT
Man
y or
gani
sms
resp
ond
to c
hang
es in
env
iron
men
tal c
on-
diti
ons
by e
nter
ing
into
a s
uspe
nded
ani
mat
ion–
like
stat
e in
w
hich
a d
ecre
ase
in m
etab
olic
rat
e (M
R)
is f
ollo
wed
by
a re
duct
ion
in c
ore
body
tem
pera
ture
(C
BT)
. Reg
ulat
ed in
- du
ctio
n of
a h
ypom
etab
olic
sta
te i
s hy
poth
esiz
ed t
o ha
ve
grea
t m
edic
al b
enef
it f
or a
var
iety
of
cond
itio
ns,
incl
udin
g is
chem
ia a
nd r
eper
fusi
on in
jury
, pyr
exia
, and
oth
er t
raum
a.
Sus
pend
ed a
nim
atio
n–lik
e st
ates
may
als
o be
use
ful
for
crea
ting
ben
efic
ial h
ypot
herm
ia in
sur
gic
al s
itua
tion
s an
d fo
r im
prov
ing
orga
n pr
eser
vati
on
2 : 0 0 0 4 : 0 0 0 6 : 0 0
TH
E
EX
PE
RI-
ME
NT
E N D O F E X P O S U R E
C O R E B O D Y T E M P E R A T U R E ( ° C )
> > >
> > >
T I M E ( H O U R S )
4 0
3 5
2 0
1 5
1 0
0 5
0 0
\\
TH
E E
XP
ER
IME
NT
0 8 : 0 0
- 5 M I N U T E S
+ 5 M I N U T E S
+ 6 M I N U T E S
+ 1 H O U R R E C O V E R Y
C O N T R O L A T M O S P H E R E
C A R B O N D I O X I D E P R O D U C T I O N
O X Y G E N C O N S U M P T I O N
A M B I E N T T E M P E R A T U R E
Inhi
biti
ng o
xida
tive
pho
spho
ryla
tion
rev
ersi
bly
indu
ces
the
stat
es o
f pr
ofou
nd h
ypom
etab
olis
m in
sev
eral
mod
el o
rgan
-is
ms.
Bec
ause
hyd
roge
n su
lfid
e (H
2S) i
s a
spec
ific
, pot
ent,
an
d re
vers
ible
inhi
bito
r of
com
plex
IV
(cy
toch
rom
e c
oxi-
dase
), t
he t
erm
inal
enz
yme
com
plex
in t
he e
lect
ron
tran
s-po
rt c
hain
, we
hypo
thes
ized
tha
t it
cou
ld r
educ
e M
R a
nd C
BT
in m
amm
als.
+
Whe
n m
ice
wer
e ex
pose
d to
80
ppm
of
H S
, th
eir
oxyg
en (
O2)
con
sum
ptio
n dr
oppe
d by
50%
and
th
eir
carb
on d
ioxi
de (
CO
2) o
utpu
t dr
oppe
d by
60%
wit
hin
the
firs
t 5
min
utes
. If
left
in
this
env
iron
men
t fo
r 6
hour
s,
thei
r M
R d
ropp
ed b
y 90
%. T
he M
R o
f co
ntro
l mic
e, a
s ju
dged
fr
om O
2 co
nsum
ptio
n an
d C
O2
outp
ut in
crea
ses.
Thi
s dr
op
in M
R w
as f
ollo
wed
by
a dr
op i
n C
BT
to 2
°C a
bove
am
bien
t te
mpe
ratu
re.
The
aver
age
CB
T of
the
se m
ice
reac
hed
a m
inim
um o
f 15
°C i
n an
am
bien
t te
mpe
ratu
re o
f 13
°C.
At
this
min
imum
CB
T, b
oth
CO
ou
tput
and
O
cons
umpt
ion
was
10%
of
norm
al,
and
the
brea
thin
g ra
te o
f th
e m
ice
de-
crea
sed
from
120
bre
aths
per
min
ute
(BP
M)
to l
ess
than
10
BP
M. A
fter
6 h
ours
of
expo
sure
to
H
S, t
he m
ice
wer
e re
turn
ed t
o ro
om a
ir a
nd t
empe
ratu
re, a
nd t
heir
MR
and
CB
T re
turn
ed t
o no
rmal
+
Expo
sing
mic
e to
var
ying
con
cen-
tr
atio
ns o
f H
S
rev
eale
d a
linea
r re
lati
onsh
ip b
etw
een
the
conc
entr
atio
n of
H
S a
nd C
BT.
CB
T dr
oppe
d fa
ster
and
re
ache
d lo
wer
tem
pera
ture
s as
con
cent
rati
ons
of H
S
in-
crea
sed
from
0 t
o 80
ppm
, sug
gest
ing
that
the
eff
ects
of
H S
are
con
cent
rati
on-d
epen
dent
. How
ever
, thi
s M
R r
educ
-ti
on is
not
dep
ende
nt o
n am
bien
t tem
pera
ture
.
+B
ecau
se
H S
can
be
toxi
c in
hig
h do
ses,
we
cond
ucte
d be
havi
oral
and
fu
ncti
onal
test
s, s
elec
ted
from
the
SH
IRPA
pro
toco
l, to
ass
ay
for
H S
ind
uced
dam
age.
No
beha
vior
al o
r fu
ncti
onal
dif
-fe
renc
es i
n th
e m
ice
wer
e de
tect
ed a
fter
exp
osur
e to
80
ppm
of
H S
for
6 h
ours
. In
the
abse
nce
of H
S, n
o ef
fect
on
CB
T w
as o
bser
ved.
In a
ddit
ion,
oth
ers
repo
rt n
o lo
ng-t
erm
he
alth
eff
ects
wit
h th
ese
H S
con
cent
rati
ons.
+
The
se-
quen
tial
dro
p in
MR
and
CB
T ob
serv
ed in
mic
e ex
pose
d to
80
ppm
of
H S
is s
imila
r to
tha
t ob
serv
ed w
hen
anim
als
init
iate
hi
bern
atio
n, d
aily
tor
por,
or
esti
vati
on. O
n-de
man
d in
duct
ion
of a
sus
pend
ed a
nim
atio
n–lik
e st
ate
coul
d pr
ovid
e in
sig
ht
into
the
mec
hani
sms
that
gov
ern
natu
ral s
tate
s of
red
uced
m
etab
olis
m. L
ower
ing
met
abol
ic d
eman
d in
thi
s w
ay c
ould
be
used
to
redu
ce p
hysi
olog
ical
dam
age
resu
ltin
g fr
om t
raum
a an
d m
ight
impr
ove
outc
omes
aft
er s
urge
ry.
2
22
2
22
2
2
2
2
2
2
2
2
3 02 01 00 0
0 5
1 0
1 5
2 0
2 5
3 0
3 5
4 0
4 5
5 0
5 5
H 2 S C O N C E N T R A T I O N ( p p m )
C O R E B O D Y T E M P E R A T U R E ( ° C )
> > >
>>
>
8 06 0 7 05 0
>>
>>
>>
>
>>
>
>
>
>>
>>
>>
>>
TH
EIR
BR
EA
TH
ING
RA
TE
FE
LL F
RO
M 1
20
BR
EA
TH
S
PE
R M
INU
TE
TO
ON
LY 2
5 B
RE
AT
HS
PE
R M
INU
TE
.
H E A R T R A T E
B R E A T H I N G R A T E
T E M P E R A T U R E
80°
60°
50°
40°
30°
20°
10°1 1 °
37°
00°
70°
80°
60°
50°
40°
30°
20°
10°1 1 °
00°
The mice stopped moving and appeared to lose conscious-ness within minutes of breathing the air and H S mixture. The animals’ heart rate dropped nearly 50 percent, from 100 beats per minute to 040 beats per minute during hy-drogen sulfide administration, but there was no significant change in blood pressure or the strength of the heart beat. While respiration rate also decreased from 120 breaths to 25 breaths per minute, there were no changes in blood oxy- gen levels, suggesting that vital organs were not at risk of oxygen starvation. +During exposure their metabolic rates dropped by an astonishing 90%, and their core body temperatures fell from 37°C to as low as 11°C. +The mice kept at room temperature had the same drop in body temperature seen in earlier studies, but those in the warm environment maintained normal core body temperatures. The same metabolic and cardiovascular changes were seen in both groups, indicating that they did not depend on the reduced body temperature, and analyzing the timing of those changes showed that metabolic reduction actually began before body temperature dropped. +The mice were kept in this condition for six hours. When they were revived, they were tested to see if suspended animation had any effects on their behavior or their brain function. It did not, and all the mice were perfectly normal.
2
ASTO- NISHING DROP
RESULT
T H E I R M E T A B O L I C R A T E D R O P P E D B Y 9 0 %
H E A R T R A T E B R E A T H I N G T E M P E R A T U R E
1 0 0 > 0 4 0 H P M 1 2 0 > 2 5 B P M 3 7 ° C > 1 1 ° C
70°
>>
100
040
R E G U L A R H E A R T B E A T P E R M I N U T E
H E A R T B E A T A F T E R H S I S I N D U C E D2
H E A R T R A T E
B R E A T H I N G R A T E
C O R E B O D Y T E M P E R A T U R E
1 0 0 H P M>>
> 1 2 0 B P M
3 7 ° C
0 4 0 H P M
0 2 5 B P M
1 1 ° C
TH
E M
ICE
WE
RE
KE
PT
IN T
HIS
CO
ND
ITIO
N F
OR
S
IX H
OU
RS
. WH
EN
TH
EY
W
ER
E R
EV
IVE
D, T
HE
Y
WE
RE
TE
ST
ED
TO
SE
E
IF S
US
PE
ND
ED
AN
IMA
-T
ION
HA
D A
NY
EF
FE
CT
S
SIX
HO
UR
S. A
FT
ER
T
HE
MIC
E R
ET
UR
NE
D
BR
EA
TH
ING
FR
ES
H
NO
RM
AL
AIR
, TH
EY
Q
UIC
KLY
RE
TU
RN
ED
T
O N
OR
MA
L.
>
FUTURE
O R G A N S P R E S E R V A T I O N
S T O K E S
C A N C E R T H E R A P Y
T R A U M A P A T I E N T S
H E A R T A T T A C K
Squ
irre
ls,
bear
s, s
nake
s an
d m
any
othe
r an
i-
mal
s hi
bern
ate
natu
rally
, so
me
mor
e de
eply
th
an o
ther
s. H
uman
s ha
ve b
een
know
n to
hi-
be
rnat
e by
acc
iden
t. A
Nor
weg
ian
skie
r w
as
resc
ued
in 1
999
afte
r be
ing
subm
erge
d in
icy
w
ater
for
mor
e th
an a
n ho
ur. S
he h
ad n
o he
art-
be
at a
nd h
er c
ore
body
tem
pera
ture
was
57°
F (n
orm
al is
98.
6). S
he r
ecov
ered
. Can
adia
n to
d-
dler
Eri
ka N
ordb
y w
ande
red
outs
ide
at n
ight
and
ne
arly
fro
ze t
o de
ath
in 2
00
1. S
he w
ore
only
a
diap
er a
nd T
-shi
rt. I
t w
as m
inus
11
°F (
-24
Cel
sius
). W
hen
foun
d, h
er h
eart
had
sto
pped
be
atin
g fo
r tw
o ho
urs
and
her
body
tem
pera
-tu
re w
as 6
1°F.
She
suf
fere
d se
vere
fro
stbi
te
but
requ
ired
no
ampu
tati
ons
and
othe
rwis
e re
cove
red.
+“U
nder
stan
ding
the
con
nec-
ti
ons
betw
een
rand
om i
nsta
nces
of
seem
ingl
y m
irac
ulou
s, u
nexp
lain
ed s
urvi
val
in s
o ca
lled
clin
ical
ly d
ead
hum
ans
and
our
abili
ty to
in-d
uce
- an
d re
vers
e -
met
abol
ic q
uies
cenc
e in
mod
el
orga
nism
s co
uld
have
dra
mat
ic i
mpl
icat
ions
fo
r m
edic
al
care
,” R
oth
said
. “I
n th
e en
d I
susp
ect
ther
e w
ill b
e cl
inic
al b
enef
its
and
it
will
cha
nge
the
way
med
icin
e is
pra
ctic
ed,
beca
use
we
will
, in
sh
ort,
be
able
to
bu
y pa
tien
ts t
ime.
”
I+In
ext
rem
e do
ses,
the
hyd
rog
en s
ulfi
de i
s th
ough
t to
bin
d to
cel
ls i
n pl
ace
of o
xyge
n to
sh
ut d
own
the
orga
nism
’s m
etab
olis
m.
Upo
n br
eath
ing
norm
al a
ir a
gain
, th
e m
ice
“qui
ckly
re
gain
ed n
orm
al f
unct
ion
and
met
abol
ic a
cti-
vi
ty w
ith
no l
ong-
term
neg
ativ
e ef
fect
s,”
the
rese
arch
ers
repo
rt. T
hey
plan
on
to t
est
the
tech
niqu
e on
la
rger
m
amm
als
next
. D
oc-
tors
are
loo
king
int
o th
e po
ssib
iliti
es o
f pl
ac-
ing
a pe
rson
in
a st
ate
of s
uspe
nded
ani
ma-
tion
du
ring
ce
rtai
n su
rgic
al
proc
edur
es
to
buy
tim
e to
fix
thin
gs.
+Th
ere
are
also
oth
er
way
s to
ach
ieve
sus
pend
ed a
nim
atio
n th
an
sim
ply
mak
ing
a bo
dy c
old
(suc
h as
hyd
roge
n su
lfid
e g
as i
n th
e co
rrec
t do
sag
e w
hich
sus
-pe
nds
that
nee
d fo
r ox
ygen
in t
he b
ody)
. The
re
has
been
res
earc
h in
whi
ch a
nim
als
wer
e re
-vi
ved
afte
r be
ing
in a
“te
chni
cally
dea
d” s
tate
fo
r th
ree
hour
s. T
his
line
of r
esea
rch
is f
unde
d by
the
Nat
iona
l In
stit
utes
of
Hea
lth
and
othe
r sc
ient
ific
org
aniz
atio
ns. I
f sus
pend
ed a
nim
atio
n ca
n be
dev
elop
ed fo
r us
e in
trau
ma
and
othe
r si
- tu
atio
ns, i
t w
ould
hav
e th
e po
tent
ial t
o in
crea
se
the
surv
ival
rat
e fr
om t
hese
pro
cedu
res,
and
he
nce
exte
ndin
g lif
e.
A G
AS
PR
OV
EN
DE
AD
LY I
N
CH
EM
ICA
L W
EA
PO
NS
CO
ULD
O
NE
DA
Y B
E U
SE
D T
O P
UT
P
EO
PLE
IN
TO
LIF
E-S
AV
ING
S
US
PE
ND
ED
AN
IMA
TIO
N.
EX
TE
ND
S L
IFE
Alr
eady
the
re a
re c
ompa
nies
tha
t w
ill g
ladl
y fr
eeze
the
dea
d in
hop
es s
ome
way
of
curi
ng
and
revi
ving
the
m m
ight
dev
elop
in t
he f
utur
e.
The
fiel
d is
cal
led
cryo
nics
. So
far,
no o
ne h
as
been
bro
ught
bac
k. T
he t
rick
wit
h th
e m
ice
did
not
requ
ire
any
free
zing
. In
stea
d, t
he r
oden
ts
brea
thed
air
lac
ed w
ith
hydr
ogen
sul
fide
, a
chem
ical
pro
duce
d na
tura
lly i
n th
e bo
dies
of
hum
ans
and
othe
r an
imal
s. W
ithi
n m
inut
es,
the
mic
e st
oppe
d m
ovin
g an
d so
on t
heir
cel
l fun
c-ti
ons
appr
oach
ed t
otal
inac
tivi
ty.
+H
uman
s us
e hy
drog
en s
ulfi
de t
o “b
uffe
r ou
r m
etab
olic
fl
exib
ility
,” R
oth
expl
aine
d. “
It’s
wha
t al
low
s ou
r co
re t
empe
ratu
re t
o st
ay a
t 98
.6 d
egre
es, r
e-
gar
dles
s of
whe
ther
we’
re in
Ala
ska
or T
ahit
i.”
This
lin
e of
res
earc
h co
uld
have
a v
arie
ty o
f he
lpfu
l ap
plic
atio
ns,
incl
udin
g su
stai
ning
the
fu
ncti
on o
f or
gans
of
crit
ical
ly i
ll pe
ople
, Ich
i-no
se s
aid.
It m
ay a
lso
be p
ossi
ble
to u
se t
he
find
ing
for
pati
ents
und
ergo
ing
surg
ery.
Thi
s w
ould
be
an a
dvan
ce, b
ecau
se a
nest
hesi
a us
- ua
lly c
ause
s bl
ood
pres
sure
to
drop
as
wel
l. +
“Cur
rent
ly,
hypo
ther
mia
is
the
only
pro
ven
way
to
decr
ease
met
abol
ic r
ate
and
conf
er
som
e pr
otec
tion
whe
n bl
ood
flow
to
the
o-r
gans
is im
pair
ed o
r in
tent
iona
lly r
educ
ed, s
uch
as d
urin
g r
educ
ed,
such
as
duri
ng c
ompl
ex
car
diac
sur
gery
,” Ic
hino
se s
aid.
“How
ever
, hyp
o-
ther
mia
has
som
e ad
vers
e ef
fect
s, i
nclu
ding
de
pres
sing
car
diov
ascu
lar
func
tion
s an
d bl
ood
clot
ting
. If
we
can
fig
ure
out
how
hyd
rog
en
sulf
ide
red
uces
met
abol
ic r
ate
wit
hout
de-
pr
essi
ng m
yoca
rdia
l fu
ncti
on, w
e m
ay b
e ab
le
to r
educ
e m
etab
olis
m a
nd p
rote
ct o
rgan
s w
ith-
ou
t us
ing
hypo
ther
mia
.”
+One
cav
eat
to t
his
rese
arch
so
far
is t
hat
hydr
ogen
sul
fide
mig
ht
prod
uce
this
res
ult
in m
ice
and
othe
r na
tura
lly
hibe
rnat
ing
spec
ies
muc
h m
ore
read
ily t
han
othe
r sp
ecie
s, in
clud
ing
hum
ans,
Ichi
nose
sai
d.
The
rese
arch
ers
inte
nd t
o ex
tend
the
stu
dy t
o bi
gger
ani
mal
s, s
uch
as s
heep
and
pig
s to
see
if
they
hav
e th
e sa
me
card
iac
and
hem
odyn
amic
re
acti
on. “
If t
he s
ame
thin
g h
appe
ns in
tho
se
spec
ies
that
wou
ld b
e m
uch
mor
e in
tere
st-
ing,
” Ic
hino
se s
aid.
+
Red
uced
leve
ls o
f ox
y-
gen
supp
ly s
pec
ific
ally
, can
be
a m
ajor
cau
se
of c
ellu
lara
nd t
issu
e da
mag
e in
don
or o
rgan
s an
d in
the
bod
ies
of i
ndiv
idua
ls t
hat
have
suf
- fe
red
seve
re
bloo
d lo
ss
or
bloo
d fl
ow
ob-
stru
ctio
n in
suc
h ca
ses
as h
eart
att
acks
or
stro
kes.
In c
ases
suc
h as
the
se, r
esto
ring
an
adeq
uate
oxy
gen
supp
ly is
not
alw
ays
easy
.
+In
add
itio
n, e
xpos
ure
to h
ydro
gen
sulf
ide
may
im
prov
e ca
ncer
tre
atm
ent
by a
llow
ing
pati
ents
to
tol
erat
e hi
gher
rad
iati
on d
oses
wit
hout
da-
m
agin
g he
alth
y ce
lls. C
ance
r ce
lls a
ren’
t dep
en-
dent
on
oxyg
en t
o g
row
and
are
the
refo
re
mor
e re
sist
ant
to r
adia
tion
tha
n su
rrou
ndin
g he
alth
y ce
lls,
whi
ch n
eed
oxyg
en t
o liv
e. R
oth
hypo
thes
izes
tha
t te
mpo
rari
ly r
educ
ing
oxyg
en
cons
umpt
ion
in h
ealt
hy c
ells
cou
ld m
ake
them
a
less
-vul
nera
ble
targ
et f
or r
adia
tion
and
che
- m
othe
rapy
and
thu
s sp
are
norm
al t
issu
e du
r-in
g hi
gh-d
ose
canc
er t
hera
py.
+Th
is w
ork
coul
d al
so b
e us
ed t
o pu
t as
tron
auts
in
sus-
pend
ed a
nim
atio
n on
long
spa
ce f
light
s th
ereb
y de
crea
sing
the
nee
d fo
r fo
od a
nd o
xyge
n.
+
It i
s di
ffic
ult
to o
vers
tate
the
im
pact
the
se
tech
niqu
es c
ould
hav
e on
hea
lth
care
, par
ticu
-la
rly
in t
he t
reat
men
t of
pat
ient
s w
ith
seve
re
inju
ries
. Be
they
fro
m c
ar c
rash
es, f
alls
, exp
o-su
re, o
r w
ork-
rela
ted
inci
dent
s, a
ccid
ents
are
th
e fi
fth-
lead
ing
caus
e of
dea
th in
Am
eric
a an
d th
e nu
mbe
r on
e ki
ller
of p
eopl
e un
der
age
44,
resu
ltin
g in
mor
e th
an 4
9,00
0 de
aths
a y
ear.
A G
AS
PR
OV
EN
DE
AD
LY I
N
CH
EM
ICA
L W
EA
PO
NS
CO
ULD
O
NE
DA
Y B
E U
SE
D T
O P
UT
P
EO
PLE
IN
TO
LIF
E-S
AV
ING
S
US
PE
ND
ED
AN
IMA
TIO
N.
SU
RG
ER
Y P
AT
IEN
TS
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
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9 8 9 H O W A R D S T . S A N F R A N C I S C O , C A 9 4 1 0 5
7 9 N E W M O N T G O M E R Y S T . S A N F R A N C I S C O , C A 9 4 1 0 5
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