Genetic variation in ICF syndrome: evidence for genetic heterogeneity

ICF syndrome is a rare autosomal recessive immunoglobulin deficiency, sometimes combined with defective cellular immunity. Other features that are frequently observed in ICF syndrome patients include facial dysmorphism, developmental delay, and recurrent infections. The most diagnostic feature of ICF syndrome is the branching of chromosomes 1, 9, and 16 due to pericentromeric instability. Positional candidate cloning recently discovered the de novo DNA methyltransferase 3B (DNMT3B) as the responsible gene by identifying seven different mutations in nine ICF patients. DNMT3B specifically methylates repeat sequences adjacent to the centromeres of chromosome 1, 9, and 16. Our panel of 14 ICF patients was subjected to mutation analysis in the DNMT3B gene. Mutations in DNMT3B were discovered in only nine of our 14 ICF patients. Moreover, two ICF patients from consanguineous families who did not show autozygosity (i.e. homozygosity by descent) for the DNMT3B locus did not reveal DNMT3B mutations, suggesting genetic heterogeneity for this disease. Mutation analysis revealed 11 different mutations, including seven novel ones: eight different missense mutations, two different nonsense mutations, and a splice-site mutation leading to the insertion of three aa's. The missense mutations occurred in or near the catalytic domain of DNMT3B protein, indicating a possible interference with the normal functioning of the enzyme. However, none of the ICF patients was homozygous for a nonsense allele, suggesting that absence of this enzyme is not compatible with life. Compound heterozygosity for a missense and a nonsense mutation did not seem to correlate with a more severe phenotype.     

The distribution of bronchial responsiveness to histamine and exercise in 527 children and adolescents

The aim of the study was to describe the bronchial responsiveness to inhaled histamine and exercise in a randomly selected group of 527 children and adolescents from Copenhagen, aged between 7 to 16 years. The distribution of the bronchial responsiveness was described as (1) the provoking concentration that causes a 20% reduction in FEV1 (2) the dose-response slope (DRS), that is, the linear slope of the dose-response curve, and (3) reduction in FEV1 after 6 minutes of exercise on a treadmill. The distribution of the concentration that causes a 20% reduction in FEV1 in the responsive range was not significantly different from a unimodal distribution, although the findings were skewed toward the less responsive end of the range (p greater than 0.05). The subjects with asthma represented a subgroup within the responsive distribution tail rather than a separate distribution peak. In asymptomatic individuals, the values of DRS were distributed symmetrically on a logarithmic scale. The deviation from normal was such that the standard deviation only slightly underestimated the "normal" range. The distribution of the bronchial response to exercise was found to be significantly different from a normal distribution. However, a significant relationship was found between the bronchial response to inhaled histamine and exercise (p less than 0.0001). We conclude that there is a log-normal distribution of the bronchial response to inhaled histamine in a random sample of children and adolescents.     

Searching the schizophrenic brain for temporal lobe deficits: a systematic review and meta-analysis

BACKGROUND: Several empirical studies have found temporal lobe impairments in many patients with schizophrenia. The strength and consistency of this evidence, however, has not been evaluated and synthesized quantitatively. Hence, we ask to what extent are temporal cortices really defective in schizophrenia? METHODS: Meta-analytical methods were used to determine the magnitude of evidence in support of structural and physiological temporal-hippocampal system deficits in schizophrenia. We report effect sizes from studies since 1980 that used structural (CT, MRI) and functional (SPECT, PET) neuroimaging methods. RESULTS: Both structural and functional imaging literatures are distinguished by heterogeneity whereby most patients show normative temporal function and structure, a minority shows diminished values and some patients demonstrate augmented function and structure rather than a deficit. CONCLUSIONS: The findings are hard to incorporate within single disease models that propose major involvement of the temporal system in schizophrenia, at least at the degree of resolution obtained with current imaging technology.     

Hydatidiform mole: genetic markers in diploid abortuses with macroscopic villous enlargement

In a series of diploid abortion specimens with gross villous enlargement the parental origin was determined by chromosomal heteromorphisms, HLA typing, and enzyme analysis. Diploid androgenesis was the mechanism in 33 cases; in 28 cases the most likely origin was by duplication of a haploid sperm after fertilization of an anucleated ovum, whereas heteromorphisms in five cases indicated a dispermic origin. In one macroscopically complete molar specimen all marker techniques applied indicated a normal conception. In two homozygous specimens a second cell line with both maternal and paternal contributions indicated a twin gestation, whereas, in four conceptuses twinning was suggested solely by HLA determination or ultrasound scan. The observation of a heterogeneous origin of diploid moles, as indicated by three marker systems studied simultaneously, emphasizes that additional information about the frequency of different types of molar conceptions may be obtained by this approach.     

Ex vivo expansion and prophylactic infusion of CMV-pp65 peptide-specific cytotoxic T-lymphocytes following allogeneic hematopoietic stem cell transplantation.

Cytomegalovirus reactivation and infection post-allogeneic hematopoietic stem cell transplant continue to cause morbidity and mortality. Current pharmacologic therapies are limited by side effects. Adoptive transfer of ex vivo generated cytomegalovirus-specific T cells has the potential to restore immunity, prevent cytomegalovirus, and circumvent the need for pharmacologic therapies. We have generated donor-derived cytomegalovirus-specific cytotoxic T cells using dendritic cells pulsed with the HLA-A2 restricted nonapeptide NLVPMVATV (NLV) derived from the cytomegalovirus-pp65 protein. These cytotoxic T cells have been given prophylactically to 9 recipients aged 4 to 65 years on or after day 28 post-allogeneic hematopoietic stem cell transplant. Only 2 of 9 recipients received T cell depletion in vivo or in vitro. There were no immediate adverse reactions to the infusions. During 97-798 days of follow-up, 2 recipients developed cytomegalovirus reactivation; neither developed cytomegalovirus disease or required pharmacotherapy. Three recipients developed acute graft versus host disease after infusion. Two recipients died, 1 from thrombotic thrombocytopenia purpura secondary to cyclosporine, 1 from complications of graft versus host disease. A transient increase in numbers of cytomegalovirus-specific T cells demonstrated by NLV-tetramer binding was seen in 6 recipients. Prophylactic adoptive transfer of NLV-specific T cells is safe and may be effective in preventing cytomegalovirus reactivation.     

Effect of advanced age on p-aminohippurate-induced inhibition of renal tubular secretion in male Fischer 344 rats

The effect of aging on glomerular filtration, effective renal plasma flow and on the responsiveness of the renal tubular anion secretory system to inhibition by 4-aminobenzoylglycine (p-aminohippurate, PAH) was examined in young (5-month) and old (22-month) Fischer 344 male rats. Plasma clearance, protein binding and renal extraction of [131I]o-iodohippurate, [125I]iothalamate and HPLC-purified [99mTc]mercaptoacetyltriglycine (MAG3), were used as in vivo probes of renal function. The effect of advanced age, without concomitant PAH, on the disposition of these markers was initially determined in ketamine anesthetized, temperature-maintained male rats, ages 5, 14 and 22 months by means of constant infusion clearance studies. Aging per se decreased (P less than 0.05) the kidney-weight normalized or body weight-normalized GFR and effective renal plasma flow rates. GFR values averaged 1.67, 1.43 and 1.32 ml/min per g kidney for the 5-, 14- and 22-month-old rats, respectively. Kidney- or body weight-normalized clearances of MAG3 and o-iodohippurate showed similar (25-27%) decreases, whereas the absolute values (ml/min) for GFR, o-iodohippurate and MAG3 clearance rates were not altered by aging. The effective filtration fraction, extraction ratio and plasma protein binding were also unchanged by advanced age. Overall, the age-related decreases in renal function were minimal in Fischer-344 rats, compared to other species. Differences in data normalization, species and gender account, in part, for discrepancies observed when comparing results in different studies on the effects of advanced age on renal function. Subsequently, we examined the effect of aging on the renal responsiveness to inhibition of tubular anion secretion using constant rate PAH infusion studies, adjusted for age-related changes in renal function. Aging did not alter PAH-induced inhibition of iodohippurate secretion. Inhibition of MAG3 elimination was more pronounced in the old rats compared to the young controls.     

An iron metabolism study in humans by means of stable tracers

An investigation of iron metabolism in a female patient volunteer by administration of stable iron isotopes as tracers was performed. The applied methodology had already been tested in rabbits in comparison with radioactive tracer technique. The subject under study was given 58Fe solution intravenously and about 45 min later 57Fe solution orally. Ten blood samples were drawn at different times within 522 min from injection. Single iron isotopes content in plasma samples was determined by proton nuclear activation. A Compton suppressor system was utilized to improve the detector limits. The characteristic parameters of iron plasma clearance and of iron intestinal absorption were determined.     

Hypouricaemia and inappropriate secretion of antidiuretic hormone in small cell bronchogenic carcinoma

Hypouricaemia has been observed in patients with the syndrome of inappropriate secretion of antidiuretic hormone (IADH). Accordingly, 69 patients with untreated bronchogenic small cell carcinoma were examined for IADH. Serum urate was also measured. IADH was proven in 25 (35%) of the 69 patients. The median serum concentration of urate in these patients was 0.26 mmol/l (range 0.13-0.50), compared to 0.36 mmol/l (0.21-0.60) in the 44 patients without IADH. The difference is statistically significant (p less than 0.01), but serum urate--when used alone--is lacking in both sensitivity and specificity for the diagnosis of IADH.     

Regulation of tissue-degrading factors and in vitro invasiveness in progression of breast cancer cells

Hormone-independent growth and invasiveness represent phenotypic properties acquired during early progression of breast cancer. We compared human mammary adenocarcinoma cells, MCF-7, which are estrogen-dependent and poorly metastatic, with the estrogen-independent and highly metastatic subline, MCF7/LCC1, with regard to expression of tissue-degrading factors of the matrix metalloproteinase (MMP)-and urokinase (uPA)-dependent degradative pathways, as well as for their in vitro invasive properties. Both cell lines showed low constitutive mRNA expression of the MMP inhibitor TIMP-1. Baseline expression of TIMP-2 mRNA was also very low in MCF-7 cells, whereas the MCF7/LCC1 level was much higher (~10- fold). Furthermore, both cell lines revealed low constitutive capacity to migrate in an in vitro invasion assay. Treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA; 100 nM) induced the mRNAs for TIMP-1 as well as for MMP-1, MMP-9, the uPA receptor, and the uPA inhibitor PAI-1, am ongst which only the responses of MMP-9 and PAI-1 were cell-specific. The mRNA levels of MMP-9 and PAI-1 were ~10-fold and ~15-fold higher in MCF7/LCC1 cells compared to MCF-7 cells. The secretion of immuno-reactive PAI-1 was considerably elevated (. 20-fold) in TPA-treated MCF7/LCC1 cells, whereas the TPA-dependent level of 92-kDa MMP-9 was only ~2-fold higher in MCF7/LCC1 cells than in MCF-7 cells. In both cell lines treatment with TPA was associated with an increase (~10-fold) in in vitro migration, which in the MCF7/LCC1 cells was significantly attenuated by a reconstituted basement membrane extract (Matrigel). These data suggest that TPA-responsive in vitro invasive properties that are probably associ-ated with PAI-1 expression may co-vary with progression from hormone-dependent to -independent breast cancer. © Rapid Science 1998     

Open-field behavior and the peripheral sympathetic nervous system in the MR/N and MNR/N rat strains

The Maudsley Reactive (MR) and Maudsley Non-Reactive (MNR) strains of rats, respectively selected by P. L. Broadhurst for high and low open-field defecation (OFD), were acquired by the National Institutes of Health in 1963 at the 21st generation of inbreeding and have been inbred as the MR/N and MNR/N strains at that location for more than 40 generations. The present experiment shows that, despite the lack of deliberate selection for more than 40 generations, the strains still differ predictably in OFD. Strain differences in open-field activity, originally found to be inversely associated with those in OFD, have also been preserved. The existence of an association between the peripheral sympathetic system and OFD originally established in the Har derivation of the Maudsley strains was also confirmed in the MR/N and MNR/N strains: MR/N male rats, with the relatively higher levels of OFD, exhibited lower concentrations of norepinephrine (NE) in spleen and descending colon than MNR/N rats. The pattern of biochemical and morphological findings obtained in this study and previous data indicate that the MNR/N and the MNR/Har strains are both derived from the British stocks of this strain carrying the agouti allele (AA). A distinction should be made between these strains and the MNRA/Har strain, which carries the nonagouti allele (aa) and which has been genetically isolated from the Nonreactive strains bearing the agouti allele since early in the selection experiment.Supported by Grant GM 28874 from the National Institute of General Medical Sciences.