Chlorambucil-monoglutathionyl conjugate is sequestered by human alpha class glutathione S-transferases.

The spontaneous reaction of 110 microM chlorambucil (4-[p-[bis(2-chloroethyl)amino]phenyl]-butanoic acid; CHB) with 5 mM GSH at 37 degrees C in physiological phosphate-buffered saline for 35 min gave primarily the monoglutathionyl derivative, 4-[p-[N-2-chloroethyl,N-2-S-glutathionylethyl]amino]phenyl]-butano ic acid; CHBSG) and the diglutathionyl derivative, 4-[p-[bis(2-S-glutathionylethyl]amino]phenyl]-butanoic acid (CHBSG2) with small amounts of the hydroxy-derivatives: 4-[p-[N-2-chloroethyl,N-2-hydroxy-ethyl]amino] phenyl-butanoic acid (CHBOH) and 4-[p-[N-2-S-glutathionylethyl-2-hydroxyethyl]amino]phenyl]-butanoi c acid (CHBSGOH). The inclusion of approximately physiological amounts of human glutathione S-transferases (GSTs) A1-1, A2-2, P1-1, M1a-1a M3-3 or P1-1 (for nomenclature see Mannervik et al., 1992, Biochem. J., 282, 305) had little or no catalytic effect on these reactions as determined by loss of CHB. However, GTSs A1-1 and A2-2 were associated with a significant increase of CHBSG at the expense of CHBSG2 + CHBSGOH suggesting that these GTs sequestered CHBSG at the active site. This interpretation was supported by inhibition studies which showed that CHBSG was a pure competitive inhibitor of the activity of GSTs A1-1 and A2-2 towards 1-chloro-2,4-dinitrobenzene with Ki's of 1.3 and 1.2 microM respectively. GSH transferases P1-1 and M1a-1a were inhibited by CHBSG above 10 microM. Incubation of 2 microM CHB, a concentration which may be of more significance for chemotherapy, in the presence or absence of GST A1-2 (20-50 microM) showed catalysis of GSH monoconjugation equivalent to 18% of the spontaneous rate. However, the dominant effect again was the sequestration of CHBSG which reached 74.3 +/- 1.5 (SEM)% of the total reactants at 60 min compared to 28.9 +/- 0.3(SEM)% in controls. CHBSG, although possessing a potential electrophilic centre, showed no detectable alkylation of plasmid DNA but indirect evidence was obtained that it alkylated other cellular macromolecules. It is concluded that the contribution of GSTs to catalysis of CHB detoxication will depend on factors not previously considered, namely the relative molarities of CHB, CHBSG and GSTs, and the cellular capacity to excrete CHBSG to relieve product inhibition.     

Is it advantageous to strengthen the cement-metal interface and use a collar for cemented femoral components of total hip replacements?

The mechanism of initiation of loosening of cemented femoral components is now known. It is debonding at the cement-metal interface. Current data strongly support the concept that a collar and improvement of the cement-metal interface are valuable. Precoating and having a roughened surface proximally and distally on the stem contribute to extended longevity of the cement-metal interface. Using contemporary instrumentation, collar-calcar contact can be achieved regularly and, once achieved, is well maintained for years.     

Book Reviews

Book reviews in this article:
Biopsy Pathology of Melanocytic Disorders . W.J. M oor and T. K rausz (1992).
Topical Corticosteroids . Edited by H.I.M aibach and C.S urber (1992).     

Influence of infiltrating lobular histology on local tumor control in breast cancer patients treated with conservative surgery and radiotherapy

To determine the influence of infiltrating lobular histology on local tumor control, the authors studied 49 patients with Stages I and II infiltrating lobular breast carcinoma treated by limited excision of the tumor and radiotherapy between 1968 and 1981 (median follow-up, 75 months). Results were compared with those in 561 cases of infiltrating ductal carcinoma similarly treated during the same period. The 5-year actuarial risk of local recurrence was similar for patients with infiltrating lobular or ductal carcinoma when the latter was evaluated as a single group (12% versus 11%). However, the 12% 5-year actuarial local recurrence risk for patients with infiltrating lobular carcinoma was intermediate between that for patients with infiltrating ductal carcinomas with an extensive intraductal component (23%) and those without an extensive intraductal component (5%). The pattern of recurrence in the breast was similar in the infiltrating lobular and ductal groups. All recurrences in patients with infiltrating lobular carcinoma and 80% of recurrences in the infiltrating ductal group occurred in the vicinity of the primary tumor (P = not significant). None of the clinical or morphologic features examined significantly influenced the risk of local recurrence in patients with infiltrating lobular carcinoma. The authors conclude that combined conservative surgery and radiotherapy appear to be a reasonable treatment option for patients with infiltrating lobular carcinoma, but further follow-up will be required to confirm these results.     

Construction and validation of a Parkinson's disease mutation genotyping array for the Parkin gene.

Parkin mutations account for the majority of familial and sporadic early onset Parkinson's disease (EOPD) cases with a known genetic association. More than 100 mutations have been described in the Parkin gene that includes homozygous, compound heterozygous, and single heterozygous mutations. We have designed a Parkin mutation genotyping array (gene chip) that includes published Parkin sequence variants and allows their simultaneous detection. The chip was validated by screening 85 PD cases and 47 controls previously tested for Parkin mutations. Similar genotyping microarrays have been developed for other genetically heterogeneous diseases including age-related macular degeneration. Here, we show the utility of a genotyping array for Parkinson's disease by analysis of 60 subjects from the Genetic Epidemiology of Parkinson Disease (GEPD) study that includes 15 early-onset PD case probands and 45 relatives.     

Distal radial fractures Injectable calcium phosphate bone cement versus conventional treatment

AMEDLINEsearchwasconductedtoidentifystudiespublishedfromJanuary1999toMarch2004thatcom-paredinjectablecalciumphosphatebone(NorianSRS)cementwithconventionaltreatmentindistalradialfrac-tures.Fromalistof13articlesidentifiedfromthesearchstrategy,fourarticleswe…