Imaging of cerebral blood flow markers in Huntington''s disease using single photon emission computed tomography.

Single photon emission computed tomography (SPECT) imaging of six Huntington's disease patients revealed a striking reduction in regional uptake of cerebral blood flow markers in vivo. Similar changes were found in one patient with "early stage" disease. The findings are compared with parallel magnetic resonance imaging (MRI) studies, and in one case, results of postmortem examination.     

Chemical derivatization as a strategy to enhance detectability of agents used in cancer management

The bioanalysis of drugs used in the management of cancer is often complicated by the lack of selectivity and sensitivity. Chemical derivatization of these drugs prior to their chromatographic analysis represents a viable strategy to improve chromatographic resolution and to enhance detectability. This review provides examples of how this approach can meet these objectives. Derivatization of racemic cyclophosphamide with a chiral acylating agent, following hydroxyalkylation to introduce a reactive centre into the molecule, provides the basis for its stereospecific analysis. The analysis of dianhydrogalactitol is described, in which diethyldithiocarbamate is used as a nucleophilic derivatizing agent that improves chromatographic behaviour and analytical sensitivity. The final example that is described is the design and preparation of improved fluorogenic reagents (o-phthalaldehyde analogues) for the derivatization of peptides and application of these reagents to the trace analysis of leu-enkephalin in plasma.     

In vivo and in vitro studies of the site of inhibitory action of omeprazole on adrenocortical steroidogenesis

Summary The site of omeprazole inhibition of adrenal steroidogenesis has been sought in vivo by analyzing the patterns of urinary steroid metabolite excretion after 6 days of treatment with placebo/omeprazole.Excretion rates of androsterone, aetiocholanolone, dehydroepiandrosterone, 11 hydroxyandrosterone, tetrahydrocortisone, tetrahydrocortisol and cortolone were reduced, indicating a block at an early step in steroidogenesis, possibly cholesterol side-chain cleavage. In vitro studies have confirmed this finding by measuring conversion of added precursors to cortisol in isolated bovine adrenocortical cells. Cortisol synthesis from added 20 hydroxycholesterol was inhibited by 83% in the presence of 100 µg omeprazole/ml. Conversion from pregnenolone and progesterone and their 17 hydroxylated derivatives was inhibited by 20–40% whereas cortisol production from added 11 deoxycortisol was not affected.These data suggest that omeprazole primarily inhibits cholesterol cleavage and does not inhibit 3 hydroxysteroid dehydrogenase, 17 hydroxylase or 11 hydroxylation; 21 hydroxylase activity may be marginally attenuated.     

Fat mass is an important determinant of whole body bone density in premenopausal women but not in men.

We recently reported that total body fat mass is the principal determinant of bone density in normal postmenopausal women. We have now reexamined the relationships among these variables and lean mass in 68 healthy premenopausal women and 51 men. Areal bone density (BMD), fat mass, and lean mass were measured in total body scans by dual-energy, x-ray absorptiometry. In women, BMD was correlated with weight (r = 0.69), fat mass (r = 0.60), and lean mass (r = 0.55). In men, the respective correlations were 0.56, 0.26 (NS), and 0.51. Multiple regression analysis confirmed a codependence of female BMD on fat and lean masses, whereas male BMD was related only to lean mass. Because BMD is an areal not volumetric density, it is dependent on body size. The analysis was therefore repeated using BMD/height as an index of "true" density. Correlations with fat mass were little changed but those with lean mass were reduced (women) or eliminated (men). By multiple regression, female BMD/height was related to fat mass alone, and in men there was a borderline effect of fat (P = 0.05) but none of lean mass. As a second method to exclude a scale artifact, fat mass was expressed as percent body weight. It was related to BMD (r = 0.48) only in women. It is concluded that bone density is closely related to fat mass in premenopausal women, but less so in men. In both sexes, apparent relationships between BMD and lean mass are artifacts attributable to the use of areal density (which is dependent on body size) as a surrogate for volumetric density. The mechanism of this fat-bone density relationship is an important question to be addressed in bone biology.     

Clonal growth of tumors on tissue-specific biomatrices and correlation with organ site specificity of metastases

We have found that neoplastic transformation alters the ability of cells to grow on substrata of tissue extracts, "biomatrices", enriched in extracellular matrix. Tumor cells were able to survive and grow at lower densities and on more types of biomatrices than normal cells. When plated at high densities (greater than 10(5) cells/60 mm dish), tumor cells attached with equal efficiency and grew at similar rates and to equivalent saturation densities on biomatrices derived from all tissues. However, at low (10(2)-10(4)/60-mm dish) seeding densities, the tumor cells grew only on certain types of biomatrix. For the various hepatoma and mammary carcinoma cell lines tested, the tissue specificity in clonal growth on biomatrices correlated with their organ site specificity for metastasis in vivo in immunosuppressed, athymic nude mice. Analysis of the effects of purified matrix components (adhesion proteins, collagens, glycosaminoglycans) indicated that only the glycosaminoglycans influenced density-dependent survival and growth of tumor cells with effects that differed with respect to the cell's metastatic potential. The results indicate that the ability of tumor cells to colonize specific tissues represents, in part, regulation of low density survival and growth by extracellular matrix and are suggestive that one of the matrix components responsible may be proteoglycans or their glycosaminoglycan chains.     

Variations in Helicobacter pylori lipopolysaccharide to evade the innate immune component surfactant protein D

Helicobacter pylori is a common and persistent human pathogen of the gastric mucosa. Surfactant protein D (SP-D), a component of innate immunity, is expressed in the human gastric mucosa and is capable of aggregating H. pylori. Wide variation in the SP-D binding affinity to H. pylori has been observed in clinical isolates and laboratory-adapted strains. The aim of this study was to reveal potential mechanisms responsible for evading SP-D binding and establishing persistent infection. An escape variant, J178V, was generated in vitro, and the lipopolysaccharide (LPS) structure of the variant was compared to that of the parental strain, J178. The genetic basis for structural variation was explored by sequencing LPS biosynthesis genes. SP-D binding to clinical isolates was demonstrated by fluorescence-activated cell sorter analyses. Here, we show that H. pylori evades SP-D binding through phase variation in lipopolysaccharide. This phenomenon is linked to changes in the fucosylation of the O chain, which was concomitant with slipped-strand mispairing in a poly(C) tract of the fucosyltransferase A (fucT1) gene. SP-D binding organisms are predominant in mucus in vivo (P = 0.02), suggesting that SP-D facilitates physical elimination. Phase variation to evade SP-D contributes to the persistence of this common gastric pathogen.     

Mutation analysis of the spastin gene (SPG4) in patients with hereditary spastic paraparesis

BACKGROUND—Hereditary spastic paraparesis is a genetically heterogeneous condition. Recently, mutations in the spastin gene were reported in families linked to the common SPG4 locus on chromosome 2p21-22.
OBJECTIVES—To study a population of patients with hereditary spastic paraparesis for mutations in the spastin gene (SPG4) on chromosome 2p21-22.
METHODS—DNA from 32 patients (12 from families known to be linked to SPG4) was analysed for mutations in the spastin gene by single strand conformational polymorphism analysis and sequencing. All patients were also examined clinically.
RESULTS—Thirteen SPG4 mutations were identified, 11 of which are novel. These mutations include missense, nonsense, frameshift, and splice site mutations, the majority of which affect the AAA cassette. We also describe a nucleotide substitution outside this conserved region which appears to behave as a recessive mutation.
CONCLUSIONS—Recurrent mutations in the spastin gene are uncommon. This reduces the ease of mutation detection as a part of the diagnostic work up of patients with hereditary spastic paraparesis. Our findings have important implications for the presumed function of spastin and schemes for mutation detection in HSP patients.


Keywords: spastin; hereditary spastic paraparesis; mutation; recessive     

Epidemiologic and diagnostic evaluation of a recent mumps outbreak using oral fluid samples.

OBJECTIVE: To determine the optimal strategy to investigate mumps virus infection in a partially vaccinated cohort. STUDY DESIGN: 122 oral fluid and serum samples were collected in a recent outbreak in Ireland. The largest age cohort, students aged 18-21 years old attending third level institutions, were investigated using virus isolation, detection of mumps specific IgM, IgG, RT-PCR and molecular genotyping. RESULTS: 97% of patients had both detectable serum IgM and IgG. Mumps virus RNA was detected in 17 oral fluid samples and 14 of these originated from a single geographic location. Only 6 of the IgM positive samples had detectable mumps virus RNA whereas this could be detected in 11 IgM negative samples. Genotyping studies revealed that genotypes G and J were co-circulating during this outbreak. CONCLUSIONS: The use of an oral fluid sample to detect mumps virus RNA and IgM offers a major improvement over serological diagnosis in acute infection in both non-vaccinated or partially vaccinated individuals, and has the advantage that specimens are collected non-invasively.     

The magnitude and encephalogenic potential of autoimmune response to MOG is enhanced in MOG deficient mice

Myelin oligodendrocyte glycoprotein (MOG) is a minor component of central nervous system myelin presumably implicated in the pathogenesis of Multiple Sclerosis (MS). Immunization with MOG leads to the development of Experimental Autoimmune Encephalomyelitis (EAE), the experimental model of MS. It has been suggested that its encephalitogenic potential may be due to the lack of MOG self-immune tolerance. To clarify this, we have generated a MOG deficient mouse (MOG(-/-)) strain. Surprisingly, MOG(35-55)specific proliferation and Th1-type cytokine production were markedly enhanced in MOG(-/-)mice compared to wild type control. Furthermore, adoptive transfer of MOG(35-55)specific T cells, isolated from MOG deficient mice, into wild-type recipients resulted in the development of a more severe disease, indicating a high capacity of MOG(-/-)T cells to initiate effector responses. Interestingly, T cell reactivity to overlapping MOG peptides in MOG(-/-)mice did not reveal new potential immunodominant epitopes in H-2(b)mice. Taken together, our data suggests that MOG self-tolerance modulates the encephalitogenic potential of autoreactive MOG T cells in the periphery.