Læknaneminn - 01.10.1996, Page 111

Af þessu má sjá að sjúklingamir voru veikari en viðmiðun-
arbörnin áður en þau veiktust af þarmadrepsbólgunni og þau
fengu sjaldnar brjóstamjólk í fyrstu gjöf. Hins vegar er ekki
hægt að draga þá ályktun af þessum gögnum að þarmadreps-
bólga komi til vegna of hraðrar aukningar í fæðugjöf.
Diagnostic tools in acute leukemia with
special reference to rearrangements of IgH
and TCR genes
Lóa Guðdrún Davíðsdóttir1.
Tor Olofsson2
'LHI, 2Blodcentralen Lund University Hospital,
University of Lund.
Introduction: The diagnosis and classification of acute
leukemia is primarily based on microscopical evalutation on
blood and bone marrow smears. Determination of the
immunophenotype by flow cytometric analysis of cell surface
antigens and karyotypic analysis for determination of
chromosomal aberrations are important for subclassification
of the different types of acute leukemia. In acute lymphocyt-
ic leukemia of B-lymphoid origin, pre-B-ALL, the gene for
the immunoglobulin heavy chain, IgH, is rearranged in a
majority of cases, and in many cases also the gene for T-cell
receptor delta-chains (TCR-d) is rearranged. The aim of the
study was to develop the technique for detection of TCR-d
gene rearrangement by souther blot and PCR in a number of
cases of acute leukemia previously characterized by IgH gene
rearrangement studies, and to evaluate how TCR-d re-
arrangement studies can contribute to the possibilites for
PCR detection of minimal residual disease, MRD, in acute
leukemia
Methods: 15 patients with pre-B-ALL, 10 patients with
T-ALL, and 12 patients with other neoplastic haematological
diseases, were studied. All these patients had previously been
subjected to southern blot analysis for detection of RFLP
(restriction fragment length polymorphism) with regard to
IgH and TCR-beta rearrangements, and the blotting
membranes were rehybridized with a TCR-delta probe
constructed by PCR and random labelled with radioactive
isotope. In addition DNA extracted from the leukemic cells
at diagnosis was subjected to PCR analysis, where two pri-
mers (VlDJl and V2D3) were used, for detection ofTCR-
delta rearrangements; in one case the PCR product was is-
olated and sequenced and an allele specific PCR primer was
constructed for future use in detection of MRD.
Results: Pre-B-ALL patients (15): 5 patients turned out to
be positive forTCR delta rearrangment in southern blot ana-
lysis, 5 were negative and 5 showed deletion of theTCR delta
gene segment. All the positive results were also positive in
PCR analysis (3 for VlDJl and 5 for V2D3). One of the
negative southern blot results were positive on PCR (both
Rannsóknarverkefni 4. árs læknanema, útdrættir
primers). T-ALL patients (10): Four turned out to have re-
arrangments on the southern blot analysis, two were negative
and four had deletion of the segment. Two of the positive
results were also positive in PCR analysis (the VIDJ1) pri-
mer= and two were negative. Nonne of the negative south-
ern blot results were positive in PCR.
Conclusion: This limited study has shown that the TCR-
delta gene was rearranged in 2/3 of the pre-B-All patients stu-
died (10/15) as shown in southern blot analysis. This is in
agreement with reports in the literature. However, in five of
these cases the rearrangement had resulted in deletion of the
TCR, delta gene, which excludes the possibility to detect the
rearrangement by PCR and to construct allele specific pri-
mers for MRD-detection. However, in selected cases
characterisation of both the IgH and the TCR-delta gene re-
arrangement by sequencing provide the opportunity to det-
ect MRD by two independent PCR techniques
Faraldsfræði og sýklalyfjanæmi valinna
Gram-neikvæðra sýkla á
Sjúkrahúsi Reykjavíkur 1985-1995
Margrét Geirsdóttir1,
Anna S. Þórisdótdr, Már Kristjánsson2.
‘LHl, 2Smitsjúkdómadeild Sjúkrahúss Reykjavíkur.
Inngangur: Ónæmi baktería fyrir sýklalyfjum fer vaxandi
einkum á spítölum, þar sem við mikla sýklalyfjanotkun verð-
ur val (sýklalyfjaval) á ónæmari sýklum. Sýklalyfjaónæmi
hlýst aðallega af þremur verkunarháttum, sem geta verið
skráðir á iitningi eða plasmíði. Þeir eru: Ensímniðurbrot á
sýklalyfjum; breyting á markpróteinum í sýklum og minnkuð
sýklalyfjaupptaka annaðhvort vegna minnkaðs gegndræpis
frumuhimnu eða virks útflutnings á sýklalyfjum úr frumu.
Helsta orsökin fyrir ónæmi baktería gegn fi-laktam sýkla-
lyfjum er viðvera K-laktamasa, sem gera lyfin óvirk m.þ.a.
rjúfa fi-laktam hring þeirra. Undanfarna áratugi hefur tíðni
á plasmíðskráðum K-laktamösum aukist verulega í enter-
obakteríum. Helstir þeirra eru TEM-1, TEM-2 og SHV-1
ensímin, sem brjóta niður fyrstu kynslóðar cefalóspórín og
flest penicillín. Extended sprectrum K-laktamasar (ESL) eru
mikilvæg afbrigði þessara ensíma. Þeir eru með breiðara
verkunarsvið og brjóta því líka niður ahnarrar og þriðju kyn-
slóðar cefalóspórín og mónóbaktam sýklalyf.
Sýklalyfjanæmi baktería og þióun þess frá árinu 1985, þeg-
ar tölvuskráning ræktunarskýrslna og næmisprófa hófst á S.R,
hefur elcki verið mikið skoðuð. I ljósi þessa sjást forsendur
rannsóknar okkar, sem hefur þann tilgang að fá hugmynd um
ónæmi valinna Gram-neikvæðra stafa fyrir tilteknum sýkla-
lyfjum og kanna tilveru ESfiL í enterobakteríum.
Efniviður og aðferðir: Rannsóknin var tvíþætt. Annars
vegar voru upplýsingar úr gagnagrunni spítalans skoðaðar og
hinsvegar voru gerð næmispróf.
LÆKNANEMINN
101 2. tbl. 1996, 49. árg.