 |
Record 1
from database: MEDLINE
 Return
To Top
- Title
- HgEDTA complex inhibits GTP
interactions with the E-site of brain
beta-tubulin.
- Author
- Duhr EF; Pendergrass JC; Slevin JT;
Haley BE
- Address
- Division of Medicinal Chemistry and
Pharmaceutics, College of Pharmacy,
University of Kentucky Medical Center,
Lexington.
- Source
- Toxicol Appl Pharmacol, 1993 Oct,
122:2, 273-80
- Abstract
- We have found that EDTA and EGTA
complexes of Hg2+, which conventional
wisdom has assumed are biologically
inert, are potentially injurious to
the neuronal cytoskeleton. Tubulin, a
major protein component of the
neuronal cytoskeleton, is the target
of multiple toxicants, including many
heavy metal ions. Among the mercurials,
inorganic mercuric ion (Hg2+) is one
of the most potent inhibitors of
microtubule polymerization both in
vivo and in vitro. In
contrast to other heavy metals, the
capacity of Hg2+ to inhibit
microtubule polymerization or disrupt
formed microtubules cannot be
prevented by the addition of EDTA and
EGTA, both of which bind Hg2+ with
very high affinity. To the
contrary, the addition of these two
chelating agents potentiates Hg2+
inhibition of tubulin polymerization.
Results herein show that HgEDTA and
HgEGTA inhibit tubulin polymerization
by disrupting the interaction of GTP
with the E-site of brain beta-tubulin,
an obligatory step in the
polymerization of tubulin. Both HgEDTA
and HgEGTA, but not free Hg2+,
prevented binding of [32P]8N3GTP, a
photoaffinity nucleotide analog of GTP,
to the E-site and displaced bound
[32P]8N3GTP at low micromolar
concentrations. This complete
inhibition of photoinsertion into the
E-site occurred in a concentration-
and time-dependent fashion and was
specific for Hg2+ complexes of EDTA
and EGTA, among the chelating agents
tested. Given the ubiquity of Hg2+ in
the environment and the widespread use
of EDTA in foodstuffs and medicine,
these mercury complexes may pose a
potentially serious threat to human
health and play a role in diseases of
the neuronal cytoskeleton.
- Language of Publication
- English
- Unique Identifier
- 94024905
Return
To Top
- MeSH Heading (Major)
- Brain|*DE/ME; Edetic Acid|*PD;
Guanosine Triphosphate|AA/DU/*ME;
Mercury|*PD; Tubulin|*DE/ME
- MeSH Heading
- Affinity Labels|DU; Animal;
Azides|DU; Binding Sites|DE; Human; In
Vitro; Magnesium|PD; Male; Phosphorus
Radioisotopes|DU; Photochemistry;
Protein Binding|DE; Rats; Rats,
Sprague-Dawley; Support, Non-U.S.
Gov't; Support, U.S. Gov't,
Non-P.H.S.; Support, U.S. Gov't,
P.H.S.
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0041-008X
- Country of Publication
- UNITED STATES
Record 2
from database: MEDLINE
Return
To Top
- Title
- A simple ICP-MS procedure for the
determination of total mercury in
whole blood and urine.
- Author
- Kalamegham R; Ash KO
- Address
- Department of Pathology, University
of Utah Medical Center, Salt Lake City
84108.
- Source
- J Clin Lab Anal, 1992, 6:4, 190-3
- Abstract
- A simple and sensitive procedure for
total mercury in whole blood and urine
using inductively coupled plasma-mass
spectrometry (ICP-MS) is described.
Specimens are prepared by
precipitation-extraction with 50% v/v
hydrochloric acid containing EDTA and
cysteine, centrifuged, and filtered
through fritended screening column;
the filtrates are directly analyzed by
ICP-MS. The method is linear between 2
and 200 micrograms/L in the specimen
with an absolute sensitivity of 0.2
microgram/L in the final supernatant.
The assay variability at various
concentrations (microgram/L) of
mercury are as follows: intra-assay
whole blood (n = 20)-4.6 +/- 0.6 (c.v.
12.3%), 18.3 +/- 1.1 (c.v. 6.1%), 56.4
+/- 2.8 (c.v. 5.0%); inter-assay whole
blood (n = 15)-5.7 +/- 1.0 (c.v.
16.8%), 19.7 +/- 2.7 (c.v. 13.5%), and
50.1 +/- 6.9 (c.v. 13.7%); urine (n =
20)-9.3 +/- 1.2 (c.v. 12.9%), 29.6 +/-
2.2 (c.v. 7.4%). Recovery of organic
and inorganic mercury from blood
samples ranges from 91.6% to 110.2%.
The method is suitable for analysis of
total mercury, both organic and
inorganic, in whole blood and urine.
- Language of Publication
- English
- Unique Identifier
- 93019810
Return
To Top
- MeSH Heading (Major)
- Mercury|*BL/*UR; Spectrum Analysis,
Mass|*MT/SN
- MeSH Heading
- Argon; Cysteine; Edetic Acid; Human;
Hydrochloric Acid; Methylmercury
Compounds|BL/UR; Sensitivity and
Specificity
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0887-8013
- Country of Publication
- UNITED STATES
Record 3
from database: MEDLINE
Return
To Top
- Title
- Inhibition of paraoxonase activity
in human liver microsomes by exposure
to EDTA, metals and mercurials.
- Author
- Gonzalvo MC; Gil F; Hernández AF;
Villanueva E; Pla A
- Address
- Department of Legal Medicine,
Faculty of Medicine, Granada, Spain.
- Source
- Chem Biol Interact, 1997 Aug, 105:3,
169-79
- Abstract
- Inhibition of paraoxon hydrolase (paraoxonase)
activity by 'in vitro' exposure to
EDTA, Mg2+, Co2+, Ba2+, La3+, Zn2+,
Cu2+, Hg2+, p-hydroxymercuribenzoate
(p-OH-MB) and phenyl mercuric acetate
(PMA) was investigated in human liver
microsomes. Enzyme activity was
totally inhibited by 1 mM EDTA in a
time-dependent manner, in contrast to
previous data obtained in rat liver
where an EDTA-resistant fraction was
detected. The possible influence of
postmortem changes in these results
was checked in a parallel experiment
using rat livers with different
postmortem intervals. From our results
the existence in human liver of an
EDTA-resistant fraction cannot be
discarded. Ba, La and PMA showed
immediate inhibition. By contrast the
other compounds tested were
time-dependent inhibitors. Ba and Zn
showed the highest IC50 values. Cu and
mercurials (Hg, p-OH-MB, PMA) were the
most potent inhibitors of human liver
paraoxonase. Kinetic analysis (Lineweaver-Burk
and Dixon plots) indicated that
different inhibitors exhibit different
inhibition patterns: competitive
(EDTA, Ba, La, Cu, p-OH-MB and PMA),
non competitive (Zn) and mixed (Hg).
The pretreatment of sample with
dithiothreitol (DTT) protects against
the inhibitory effect of mercurials.
Furthermore after inhibition by
mercurials the activity was restored
by DTT. These results confirmed the
essential role of the -SH groups to
maintain the catalytic activity of
paraoxonase and suggest the existence
of two types of -SH groups that could
differ in their localization.
- Language of Publication
- English
- Unique Identifier
- 97437462
Return
To Top
- MeSH Heading (Major)
- Edetic Acid|*PD; Enzyme
Inhibitors|*PD; Esterases|*AI/ME;
Mercury Compounds|*PD; Metals|*PD;
Microsomes, Liver|DE/*EN
- MeSH Heading
- Animal; Dithiothreitol|PD; Enzyme
Activation; Human; Kinetics; Rats;
Sulfhydryl Compounds|ME; Support,
Non-U.S. Gov't
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0009-2797
- Country of Publication
- IRELAND
Record 4
from database: MEDLINE
Return
To Top
- Title
- Human semen ribonuclease. Location,
properties and inhibition by sodium
dodecyl sulfate, zinc sulfate and
EDTA.
- Author
- Mujica A; Romero G; Hernandez Montes
H
- Address
-
- Source
- Int J Fertil, 1976, :2, 109-13
- Abstract
- Optimal conditions were established
for RNase activity measurement. The
enzyme was measured in human seminal
plasma as well as in spermatozoa.
Results suggest that sperm enzyme may
come from seminal plasma contamination
and that RNase may be used as a marker
enzyme for seminal plasma
contamination. Sodium dodecylsulfate,
a reagent utilized to produce the
solubilization of the spermatozoa,
produced a very strong inhibition of
the RNase at low concentrations (530
muM). Zinc sulfate and EDTA also
produced inhibition of the RNase
activity. Such inhibition may be very
useful in future studies of RNA
metabolism in human spermatozoa.
- Language of Publication
- English
- Unique Identifier
- 76259358
Order
full text for this document
- MeSH Heading (Major)
- Edetic Acid|*PD; Ribonucleases|*/ME;
Semen|*EN; Sodium Dodecyl Sulfate|*PD;
Zinc|*PD
- MeSH Heading
- Dithiothreitol|PD; Human;
Hydrogen-Ion Concentration; Male;
Mercury|PD; Spermatozoa|EN
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0020-725X
- Country of Publication
- UNITED STATES
Record 5
from database: MEDLINE
Return
To Top
- Title
- Effects of plumbous ion on guanine
metabolism.
- Author
- Farkas WR; Stanawitz T
- Address
-
- Source
- J Inorg Biochem, 1979 Aug, 11:1,
31-8
- Abstract
- The enzyme guanine aminohydrolase (guanase)
is inhibited by low levels of Pb2+.
The inhibition is noncompetitive and
the Ki is 3.0 X 10(-6) M. The only
other heavy metals that are inhibitory
at low concentrations are Ag+, which
is 36% more, and Hg2+, which is about
50% less inhibitory than Pb2+. The
inhibition of guanase by Pb2+ and Hg2+
is synergistic and the inhibition of
the enzyme was readily reversed by
EDTA. The relationship of these
studies with guanase and to the
etiology and treatment of saturnine
gout, which appears in humans
suffering from lead poisoning, is
discussed.
- Language of Publication
- English
- Unique Identifier
- 80008188
Return
To Top
- MeSH Heading (Major)
- Aminohydrolases|*AI; Guanine
Deaminase|*AI; Lead|*PD
- MeSH Heading
- Cations, Divalent; Edetic Acid|PD;
Gout|EN/ET; Human; Kinetics; Lead
Poisoning|EN; Mercury|PD; Silver|PD;
Support, U.S. Gov't, P.H.S.; Xanthine
Oxidase|ME
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0162-0134
- Country of Publication
- UNITED STATES
Record 6
from database: MEDLINE
Return
To Top
- Title
- Metal
excretion and magnesium retention in
patients with intermittent
claudication treated with intravenous
disodium EDTA.
- Author
- Guldager B; J‡rgensen PJ;
Grandjean P
- Address
- Department of Surgery, Hiller‡d
Hospital, Denmark.
- Source
- Clin Chem, 1996 Dec, 42:12, 1938-42
- Abstract
- Sixty
patients with intermittent
claudication participated in a
double-blind placebo-controlled trial
of 20 courses of intravenous chelation
therapy with 3 g of disodium EDTA vs
placebo during 5-9 weeks. After the
first infusion, the 24-h urinary
excretion of lead and zinc was
approximately 25-fold higher in the
EDTA-treated group; relative
differences for copper and calcium
were smaller. Urinary magnesium
excretion in the EDTA-treated group
was one-third less than in the control
group. After the treatment period, the
blood lead concentration had decreased
by approximately 73% and the serum
zinc concentration by approximately
34%; other changes in blood
concentrations were negligible. The
loss of essential minerals and the
possible redistribution of lead in the
body may constitute a disadvantage
that should be taken into account in
repeated intravenous EDTA treatment.
- Language of Publication
- English
- Unique Identifier
- 97124459
Return
To Top
- MeSH Heading (Major)
- Edetic Acid|*TU; Intermittent
Claudication|*DT/ME; Magnesium|BL/*ME/UR;
Metals|*UR
- MeSH Heading
- Adult; Aged; Aged, 80 and over;
Calcium|UR; Copper|BL/UR; Double-Blind
Method; Human; Lead|BL/UR; Mercury|BL;
Middle Age; Placebos; Support,
Non-U.S. Gov't; Zinc|BL/UR
- Publication Type
- CLINICAL TRIAL; JOURNAL ARTICLE;
RANDOMIZED CONTROLLED TRIAL
- ISSN
- 0009-9147
- Country of Publication
- UNITED STATES
Record 7
from database: MEDLINE
Return
To Top
- Title
- HgEDTA complex inhibits GTP
interactions with the E-site of brain
beta-tubulin.
- Author
- Duhr EF; Pendergrass JC; Slevin JT;
Haley BE
- Address
- Division of Medicinal Chemistry and
Pharmaceutics, College of Pharmacy,
University of Kentucky Medical Center,
Lexington.
- Source
- Toxicol Appl Pharmacol, 1993 Oct,
122:2, 273-80
- Abstract
- We have found that EDTA and EGTA
complexes of Hg2+, which conventional
wisdom has assumed are biologically
inert, are potentially injurious to
the neuronal cytoskeleton. Tubulin, a
major protein component of the
neuronal cytoskeleton, is the target
of multiple toxicants, including many
heavy metal ions. Among the mercurials,
inorganic mercuric ion (Hg2+) is one
of the most potent inhibitors of
microtubule polymerization both in
vivo and in vitro. In contrast to
other heavy metals, the capacity of
Hg2+ to inhibit microtubule
polymerization or disrupt formed
microtubules cannot be prevented by
the addition of EDTA and EGTA, both of
which bind Hg2+ with very high
affinity. To the contrary, the
addition of these two chelating agents
potentiates Hg2+ inhibition of tubulin
polymerization. Results herein show
that HgEDTA and HgEGTA inhibit tubulin
polymerization by disrupting the
interaction of GTP with the E-site of
brain beta-tubulin, an obligatory step
in the polymerization of tubulin. Both
HgEDTA and HgEGTA, but not free Hg2+,
prevented binding of [32P]8N3GTP, a
photoaffinity nucleotide analog of GTP,
to the E-site and displaced bound
[32P]8N3GTP at low micromolar
concentrations. This complete
inhibition of photoinsertion into the
E-site occurred in a concentration-
and time-dependent fashion and was
specific for Hg2+ complexes of EDTA
and EGTA, among the chelating agents
tested. Given the ubiquity of Hg2+ in
the environment and the widespread use
of EDTA in foodstuffs and medicine,
these mercury complexes may pose a
potentially serious threat to human
health and play a role in diseases of
the neuronal cytoskeleton.
- Language of Publication
- English
- Unique Identifier
- 94024905
Return
To Top
- MeSH Heading (Major)
- Brain|*DE/ME; Edetic Acid|*PD;
Guanosine Triphosphate|AA/DU/*ME;
Mercury|*PD; Tubulin|*DE/ME
- MeSH Heading
- Affinity Labels|DU; Animal;
Azides|DU; Binding Sites|DE; Human; In
Vitro; Magnesium|PD; Male; Phosphorus
Radioisotopes|DU; Photochemistry;
Protein Binding|DE; Rats; Rats,
Sprague-Dawley; Support, Non-U.S.
Gov't; Support, U.S. Gov't,
Non-P.H.S.; Support, U.S. Gov't,
P.H.S.
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0041-008X
- Country of Publication
- UNITED STATES
Record 8
from database: MEDLINE
Return
To Top
Return
To Menu Position #10
- Title
- Trace element studies in three
patients and a fetus with Menkes'
disease. Effect of copper therapy.
- Author
- Nooijen JL; De Groot CJ; Van den
Hamer CJ; Monnens LA; Willemse J;
Niermeijer MF
- Address
-
- Source
- Pediatr Res, 1981 Mar, 15:3, 284-9
- Abstract
- This paper reports the results of a
multielement analysis of postmortem
samples of Menkes patients, of which
one was untreated and two had been
treated for various lengths of time
with intramuscular injections of
copper-EDTA. The findings have been
compared with data from a Menkes fetus
and from controls. The results confirm
that copper accumulates in various
tissues and demonstrate a further
increase in copper levels as a result
of the treatment with copper-EDTA.
Although no clinical improvement was
observed, the levels of some
copper-containing enzymes normalized
during the copper-therapy.
Furthermore, in agreement with the
identification of the copper-binding
protein in the kidney as
metallothionein, it was found that not
only copper, but also zinc, cadmium,
and mercury are trapped in this
tissue. A low copper concentration in
the brain was also found in a Menkes
fetus, indicating that brain damage
might already have occurred before
birth. Speculation Until recently,
Menkes' disease was considered to be
due to copper deficiency. However, the
symptoms are more typical of a storage
disease in which copper is
irreversibly trapped in some tissues,
in particular in the kidneys, by
metallothionein. This abnormal storage
pattern gives rise to copper
deficiency elsewhere in the organism,
particularly in the brain where it may
cause irreversible damage in the
foetus. Parenteral administration of
copper does not lead to clinical
improvement. The only
"therapy" that seems
feasible at present is tracing the
carriers of the disease and advising
abortion when prenatal diagnosis
indicates a male fetus carrying the
disease.
- Language of Publication
- English
- Unique Identifier
- 81174435
Return
To Top
Return
To Menu Position #10
- MeSH Heading (Major)
- Brain Diseases, Metabolic|*DT;
Copper|AN/*TU; Menkes Kinky Hair
Syndrome|DI/*DT; Trace Elements|*AN
- MeSH Heading
- Arsenic|AN; Cadmium|AN; Case Report;
Cobalt|AN; Comparative Study; Edetic
Acid; Female; Fetal Diseases|DI;
Human; Infant; Iron|AN; Male;
Mercury|AN; Molybdenum|AN; Pregnancy;
Selenium|AN; Tissue Distribution;
Zinc|AN
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0031-3998
- Country of Publication
- UNITED STATES
Record 9
from database: MEDLINE
Return
To Top
Return
To Menu Position #10
- Title
- Monoglyceride and diglyceride
lipases from human platelet microsomes.
- Author
- Chau LY; Tai HH
- Address
- Division of Medicinal Chemistry and
Pharmacognosy, College of Pharmacy,
University of Kentucky, Lexington
405367-0082.
- Source
- Biochim Biophys Acta, 1988 Dec,
963:3, 436-44
- Abstract
- In the present study, we have
characterized the properties of both
diglyceride lipase (lipoprotein
lipase, EC 3.1.1.24) and monoglyceride
lipases (acylglycerol lipase, EC
3.1.1.23) in an attempt to assess the
potential roles of these two enzymes
in the release of arachidonate in
activated human platelets. Diglyceride
lipase exhibited maximal activity at
pH 3.5, whereas monoglyceride lipase
showed optimal activity at pH 7.0.
Neither of the lipases were inhibited
by EDTA or stimulated by Ca2+, Mg2+ or
Mn2+. Both enzymes, however, were
strongly inhibited by Hg2+ and Cu2+,
indicating the involvement of
sulfhydryl groups in catalytic
activity. This suggestion was further
supported by their sensitivity toward
sulfhydryl inhibitors, with
monoglyceride lipase being more
susceptible to inhibition. Both
lipases were found to be inhibited to
a different degree by a variety of
antiplatelet drugs blocking
aggregation and arachidonate release.
Kinetic studies indicated that
dichotomous metabolism of
diacylglycerol to monoacylglycerol and
to phosphatidic acid could occur
concurrently, since the apparent Km
values for diglyceride lipase and for
diglyceride kinase were comparable.
Further studies showed that the
specific activity of monoglyceride
lipase was at least 100-fold higher
than that of diglyceride lipase,
indicating that the rate-limiting step
in the release of arachidonate was the
reaction catalyzed by diglyceride
lipase.
- Language of Publication
- English
- Unique Identifier
- 89062521
Return
To Top
Return
To Menu Position #10
- MeSH Heading (Major)
- Blood Platelets|*EN; Carboxylic
Ester Hydrolases|*BL; Lipoprotein
Lipase|*BL; Monoacylglycerol
Lipases|*BL
- MeSH Heading
- Calcium|PD; Copper|PD; Edetic
Acid|PD; Heat; Human; Hydrogen-Ion
Concentration; Kinetics; Magnesium|PD;
Manganese|PD; Mercury|PD;
Microsomes|EN; Platelet Aggregation
Inhibitors|PD; Substrate Specificity;
Sulfhydryl Reagents|PD; Support,
Non-U.S. Gov't; Support, U.S. Gov't,
P.H.S.
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0006-3002
- Country of Publication
- NETHERLANDS
Record
10 from database: MEDLINE
Return
To Top
Return
To Menu Position #10
- Title
- Differential metal response and
regulation of human heavy
metal-inducible genes.
- Author
- Murata M; Gong P; Suzuki K; Koizumi
S
- Address
- Division of Hazard Assessment,
National Institute of Industrial
Health, Kawasaki, Japan.
- Source
- J Cell Physiol, 1999 Jul, 180:1,
105-13
- Abstract
- A number of heavy metal-inducible
genes have been reported, but their
ranges of response to various metal
species are not well known. It is also
unclear if these genes are regulated
through common mechanisms. To answer
these questions, we compared induction
kinetics of human metal-inducible
genes including the MT-IIA (coding for
a metallothionein isoform), hsp70
(coding for the 70-kDa heat-shock
protein), and c-fos genes in HeLa
cells exposed to Zn, Cd, Ag, Hg, Cu(II),
Co, or Ni ions. Transcripts from these
three genes were increased after
exposure to wide ranges of metals, but
each gene was unique in its induction
kinetics. Generally, induction was
observed at lower metal concentrations
in the order of MT-IIA, hsp70, and c-fos.
These genes also showed differential
responses in time course: more rapid
induction was observed in the order of
c-fos, hsp70, and MT-IIA after
exposure to Zn or Cd. Since the
metal-responsive element (MRE) and
heat shock element (HSE) of the MT-IIA
and hsp70 genes, respectively, are
thought to be the cis-acting DNA
elements that mediate metal response,
we compared the properties of proteins
that specifically bind to these
elements. MRE-binding activity was
detected only in the extract from
cells exposed to Zn. By contrast, HSE-binding
activity was detected in extracts from
cells treated with Zn, Cd, Ag, and Cu.
The former was also activated by Zn in
vitro, while the latter was not. Each
of these DNA-binding activities showed
no affinity to the recognition
sequence of the other. These results
demonstrate that the human
metal-inducible genes have broad
ranges of response to a variety of
heavy metals, but suggest that they
are probably regulated through
independent mechanisms.
- Language of Publication
- English
- Unique Identifier
- 99288869
Return
To Top
Return
To Menu Position #10
- MeSH Heading (Major)
- Heat-Shock Proteins 70|*GE;
Metallothionein|*GE; Metals,
Heavy|*PD; Proto-Oncogene Proteins c-fos|*GE
- MeSH Heading
- Blotting, Northern; Cadmium|PD;
Chelating Agents|PD; Cobalt|PD;
Copper|PD; Dose-Response Relationship,
Drug; DNA-Binding Proteins|ME; Edetic
Acid|PD; Gene Expression|DE; Gold|PD;
Hela Cells; Human; Mercury|PD;
Nickel|PD; Nuclear Proteins|ME;
Oligonucleotide Probes; RNA,
Messenger|AN; Transcription Factors|ME;
Transcription, Genetic|PH; Zinc|PD
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0021-9541
- Country of Publication
- UNITED STATES
Record
11 from database: MEDLINE
Return
To Top
Return
To Menu Position #10
- Title
- Mobilisation of heavy metals into
the urine by CaEDTA: relation to
erythrocyte and plasma concentrations
and exposure indicators.
- Author
- Araki S; Aono H; Murata K
- Address
-
- Source
- Br J Ind Med, 1986 Sep, 43:9, 636-41
- Abstract
- To
investigate the effects of calcium
disodium ethylenediamine tetra-acetate
(CaEDTA) on the urinary excretion,
erythrocyte, and plasma concentrations
and exposure indicators of seven heavy
metals, CaEDTA was administered by
intravenous infusion to 20 workers
exposed to lead, zinc, and copper. The
workers' blood lead concentrations
ranged from 22 to 59 micrograms/dl
(mean 38 micrograms/dl (1.8 mumol/l].
The 24 hour urinary excretion of
metals after CaEDTA administration (mobilisation
yield) was on average 13 times the
background excretion for lead, 11
times for zinc, 3.8 times for
manganese, 3.4 times for cadmium, 1.3
times for copper, and 1.1 times for
chromium; no significant increase was
found for mercury. The mobilisation
yield of lead (MPb) was significantly
correlated with whole blood and
erythrocyte concentrations and the
urinary excretion of lead but not with
its plasma concentration; similarly,
the mobilisation yield of cadmium was
significantly correlated with its
erythrocyte concentration. In
addition, MPb was significantly
correlated with intra-erythrocytic
enzyme delta-aminolaevulinic acid
dehydratase activity and urinary
coproporphyrin excretion. The relation
between the mobilisation yield of
heavy metals and their body burden
(and toxic signs) is discussed in the
light of these findings.
- Language of Publication
- English
- Unique Identifier
- 87000506
Return
To Top
Return
To Menu Position #10
- MeSH Heading (Major)
- Edetic Acid|*PD; Erythrocytes|*ME;
Metals|*ME
- MeSH Heading
- Adult; Cadmium|ME; Chromium|ME;
Copper|ME; Environmental Exposure;
Human; Lead|ME; Male; Manganese|ME;
Mercury|ME; Middle Age; Zinc|ME
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0007-1072
- Country of Publication
- ENGLAND
Record
12 from database: MEDLINE
Return
To Top
Return
To Menu Position #10
- Title
- Cyclic adenosine 3':5'-monophosphate
phosphodiesterase activity in
malignant and cyclic adenosine
3':5'-monophosphate-induced
"differentiated"
neuroblastoma cells.
- Author
- Kumar S; Becker G; Prasad KN
- Address
-
- Source
- Cancer Res, 1975 Jan, 35:1, 82-7
- Abstract
- The regulation of cyclic adenosine
3:5-monophosphate (cyclic AMP)
phosphodiesterase activity in
homogenates of malignant and cyclic
AMP-induced "differentiated"
neuroblastoma cells was studied.
Neuroblastoma cells of at least three
mouse and one human clone had both the
low (2 to 4 muM) and the high (66 to
106 muM) Km phosphodiesterase. In
cyclic AMP-induced differentiated
cells the values of Km were decreased,
whereas the values of Vmax appeared to
be slightly increased. Magnesium and
manganese stimulated phosphodiesterase
activity. Calcium, zinc, copper,
mercury, ethylenediaminetetraacetic
acid, and imidazole completely
inhibited phosphodiesterase activity
in malignant cells, whereas the above
agents, except
ethylenediaminetetraacetic acid, only
partially inhibited enzyme activity in
differentiated cells.
Ethylenediaminetetraacetic acid
completely reduced phosphodiesterase
activity in differentiated cells. The
pH optimum for phosphodiesterase
activity was about 8 in both malignant
and differentiated cells. The present
studies show that the values of Km and
Vmax and the sensitivity of
phosphodiesterase activity to divalent
ions change in cyclic AMP-induced
differentiated neuroblastoma cells,
and therefore we propose that the
reverse may be true during malignant
transformation of nerve cells.
- Language of Publication
- English
- Unique Identifier
- 75074120
Return
To Top
Return
To Menu Position #10
- MeSH Heading (Major)
- Cell Differentiation|*; Cyclic
AMP|ME/*PD; Neuroblastoma|*EN;
Phosphoric Diester Hydrolases|*ME
- MeSH Heading
- Adenylate Cyclase|ME; Animal;
Calcium|PD; Caudate Nucleus|EN; Clone
Cells; Copper|PD; Depression,
Chemical; Edetic Acid|PD; Human;
Hydrogen-Ion Concentration;
Imidazoles|PD; Magnesium|PD;
Manganese|PD; Mercury|PD; Mice;
Stimulation, Chemical; Support, U.S.
Gov't, Non-P.H.S.; Time Factors;
Zinc|PD
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0008-5472
- Country of Publication
- UNITED STATES
Record
13 from database: MEDLINE
Return
To Top
Return
To Menu Position #10
- Title
- Erythrocyte porphobilinogen synthase
(delta-aminolaevulinate dehydratase)
activity: a reliable and quantitative
indicator of lead exposure in humans.
- Author
- Mitchell RA; Drake JE; Wittlin LA;
Rejent TA
- Address
-
- Source
- Clin Chem, 1977 Jan, 23:1, 105-11
- Abstract
- We assessed optimal conditions for
assay of porphobillinogen synthase (EC
4.2.1.24) activity in human blood
containing abnormally high
concentrations of lead. Zn2+and -SH,
both required for complete activation
of the enzyme, had additive effects.
Using a modified method based on these
studies, we found blood lead
concentration to be strictly
proportional to ln(activated/nonactivated)
enzyme activity. One brand of
commercially available
"lead-free" tubes contained
a substance that interfered with this
relationship. In vitro studies, with
the modified assay, showed ALAD to be
activated by low concentrations but
inactivated by high concentrations of
Hg2+, Cd2+, and
ethylenediaminetetraacetate. We fouund
no genetically influenced differences
among unexposed individuals when
in(activated/nonactivated) enzyme
activities were compared. The
technique is suitable for use in
screening for lead poisoning in
humans.
- Language of Publication
- English
- Unique Identifier
- 77089786
Return
To Top
Return
To Menu Position #10
- MeSH Heading (Major)
- Erythrocytes|*EN; Hydro-Lyases|*BL;
Lead Poisoning|*DI/*EN;
Porphobilinogen Synthase|*BL
- MeSH Heading
- Cadmium|PD; Edetic Acid|PD; Enzyme
Activation|DE; Glutathione|PD; Human;
Kinetics; Lead|BL/PD; Mercury|PD;
Sodium|PD; Zinc|PD
- Publication Type
- JOURNAL ARTICLE
- ISSN
- 0009-9147
- Country of Publication
- UNITED STATES
Record
14 from database: MEDLINE
Return
To Top
Return
To Menu Position #10
- Title
- Comparati
| | | |
