Point mutation in the stalk of angiotensin-converting enzyme causes a dramatic increase in serum angiotensin-converting enzyme but no cardiovascular disease.

BACKGROUND: Angiotensin-converting enzyme (ACE) metabolizes many small peptides and plays a key role in blood pressure regulation. Elevated serum ACE is claimed to be associated with an increased risk for cardiovascular disease. Previously, two families with dramatically increased serum ACE were described, but no systematic survey of affected individuals was performed, and the molecular background of this trait is unknown. METHODS AND RESULTS: Eight families were identified with autosomal dominant inheritance of a dramatic (5-fold) increase of serum ACE activity. Strikingly, no clinical abnormalities were apparent in the affected subjects. Isolated blood cells were used for genetic and biochemical analysis. The level of ACE expression on the blood leukocytes and dendritic cells and total cell-associated ACE of the affected individuals was similar to that in nonaffected relatives; however membrane-bound mutant ACE was much more efficiently clipped from the cell surface compared with its wild-type counterpart. A point mutation causing Pro1199Leu in the stalk region of the ACE molecule cosegregates with the increase in serum ACE (LOD score, 6.63). CONCLUSIONS: A point mutation in the stalk region of the ACE protein causes increased shedding, leading to increased serum ACE, whereas cell-bound ACE is unaltered, and affected individuals exhibit no clinical abnormalities. These findings qualify the importance of serum ACE and establish a new determinant of ACE solubilization.

A comparison of genomic structures and expression patterns of two closely related flanking genes in a critical lung cancer region at 3p21.3.

In the search for a tumour suppressor gene in the 3p21.3 region we isolated two genes, RBM5 and RBM6. Gene RBM5 maps to the region which is homozygously deleted in the small cell lung cancer cell line GLC20; RBM6 crosses the telomeric breakpoint of this deletion. Sequence comparison revealed that at the amino acid level both genes show 30% identity. They contain two zinc finger motifs, a bipartite nuclear signal and two RNA binding motifs, suggesting that the proteins for which RBM5 and RBM6 are coding have a DNA/RNA binding function and are located in the nucleus. Northern and Southern analysis did not reveal any abnormalities. By SSCP analysis of 16 lung cancer cell lines we found only in RBM5 a single presumably neutral mutation. By RT-PCR we demonstrated the existence of two alternative splice variants of RBM6, one including and one excluding exon 5, in both normal lung tissue and lung cancer cell lines. Exclusion of exon 5 results in a frameshift which would cause a truncated protein of 520 amino acids instead of 1123 amino acids. In normal lung tissue, the relative amount of the shorter transcript was much greater than that in the lung tumour cell lines, which raises the question whether some tumour suppressor function may be attributed to the derived shorter protein.

RFP2, c13ORF1, and FAM10A4 are the most likely tumor suppressor gene candidates for B-cell chronic lymphocytic leukemia.

Occurrence of 13q14 deletions between D13S273 and D13S25 in B-cell chronic lymphocytic leukemia (B-CLL) suggests that the region contains a tumor suppressor gene. We constructed a PAC/cosmid contig largely corresponding to a 380-kb 13q14 YAC insert that we found deleted in a high proportion of B-CLL patients. We found seven genes by exon trapping, cDNA screening and analysis/cDNA extension of known expressed sequence tags. One appeared to originate from another region of 13q. Recent publications have focused on two of the genes that most likely do not have a tumor suppressor role. This study evaluates the remaining four genes in the region by mutation scanning and theoretical analysis of putative encoded products. No mutations suggestive of a pathogenic effect were found. The 13q14 deletions may be a consequence of an inherent instability of the region, an idea supported by our finding of a considerable proportion of AluY repeats. Deletion of putative enhancer sequences and/or genes in the region may result in an inactivation of tumor suppression by a haploinsufficiency mechanism. We conclude that RFP2, c13ORF1, and a chromosome 13-specific ST13-like gene, FAM10A4, are the most likely candidates for such a type of B-CLL TSG.

Mutation frequency of cystic fibrosis transmembrane regulator is not increased in oligozoospermic male candidates for intracytoplasmic sperm injection.

OBJECTIVE: To examine the frequency of anomalies of the vas deferens and the frequency of mutations of the cystic fibrosis transmembrane regulator (CFTR) gene in male candidates for intracytoplasmic sperm injection (ICSI) who had severe oligoasthenoteratozoospermia. DESIGN: The clinical data for male candidates for ICSI were studied. The three most frequent cystic fibrosis (CF)-causing CFTR mutations in the Dutch population (deltaF508, A455E, and G542X) and the three most frequent CFTR mutations potentially causing congenital bilateral absence of the vas deferens (CBAVD) in the Dutch population (deltaF508, R117H, and IVS8-5T) were analyzed. Delta I507 is also detected by the deltaF508 test. Samples of DNA from patients identified as CFTR mutation carriers were subjected to denaturing gradient gel electrophoresis analysis with use of a two-dimensional electrophoretic technique. SETTING: University-based center for reproductive medicine and clinical genetics. PATIENT(S): Male candidates for ICSI who had oligoasthenoteratozoospermia and no history of operative sterilization and refertilization. Males with a chromosomal aberration or a Y-chromosome microdeletion were excluded. INTERVENTION(S): Semen and blood samples were collected from the patients at their first visit to the clinic. MAIN OUTCOME MEASURE(S): Frequency of anomalies of the vas deferens and frequency of mutations of the CFTR gene in male candidates for ICSI who had oligoasthenoteratozoospermia. RESULT(S): None of the patients had abnormalities of the vas deferens at physical examination. In 4 of the 150 chromosomes (75 patients), a CFTR mutation was found, yielding a CFTR mutation frequency of 2.7% (95% confidence interval, 1.0-6.7%). None of the patients had two CFTR mutations. CONCLUSION(S): The frequency of congenital abnormalities of the vas deferens in patients with oligoasthenoteratozoospermia is low. The frequencies of the CFTR mutations identified in this cohort did not differ significantly from the frequencies found in the normal Dutch population.

Renal response to converting enzyme blockade.

To investigate the renal actions of the converting enzyme inhibitor enalaprilic acid, incremental doses of this drug were infused into the renal artery of hypertensive patients just before renal angiography. One group (n = 6) received doses of 0.1, 0.3 and 1 microgram/kg per min, while in another group (n = 7) doses of 1, 3 and 10 micrograms/kg per min were given. Each dose was infused for 10 min, at the end of which renal blood flow was assessed by means of xenon-washout. At the same time, blood was sampled from the renal artery and vein for determination of converting enzyme, renin and angiotensin II. Enalaprilic acid caused a dose-related suppression of converting enzyme activity, which was maximal at a dose of 1 microgram/kg per min; arterial levels fell more steeply than venous ones. Angiotensin II disappeared in parallel with the drop in converting enzyme. Renal blood flow, on the other hand, began to increase only when 3 micrograms/kg per min was given, and no further changes occurred with the highest dose. Intra-arterial blood pressure fell only when the highest dose was given. Renin secretion tended to increase, but changes were not statistically significant. It is concluded that systemic suppression of converting enzyme is needed for renal vasodilatation to occur. However, the renal vascular response comes well before blood pressure falls.

The ideal neutron energy spectrum of 241AmLi(α,n)10B sources.

The pure and unperturbed (ideal, at birth) spectra of (241)AmLi(α,n)(10)B sources were determined using Monte Carlo simulations, along with the neutron spectrum measured outside a source's encapsulation. Various parameters that affect photon and neutron yields and energy distributions were investigated. The source's microparticle size was deduced. Subsequently, the calculated theoretical neutron energy spectra of the (241)AmLi(α,n) reaction were compared to both the ideal spectra and the calculation of Geiger and van der Zwan predominantly used since early 1970s.

Targeting dendritic cells with antigen via dendritic cell-associated promoters.

The induction of tumor-specific immune responses is largely dependent on the ability of dendritic cells (DCs) to present tumor-associated antigens to T lymphocytes. Therefore, we investigated the use of DC-associated promoter-driven genetic vaccines to specifically target DC in vivo. Restricted expression of vaccine-encoding genes in DC should enhance specificity and improves their safety for clinical applications. Hereto, 3-5 kb upstream sequences of the murine genes encoding CD11c, DC-SIGN, DC-STAMP and Langerin were isolated, characterized and subcloned into enhanced green fluorescent protein (EGFP) reporter constructs. Upon electroporation, EGFP was expressed in DC cell lines, but not in other cell lines, confirming DC-restricted promoter activity. When these promoters were cloned into a construct upstream of the gene for ovalbumin (OVA), it appeared that DC-STAMP promoter-driven expression of OVA (pDCSTAMP/OVA) in DC yielded the most efficient OVA-specific CD4+ and CD8+ T-cell responses in vitro. Administration of pDC-STAMP/OVA in vivo, using the tattoo gun vaccination system, evoked specific immune responses as evidenced in a mouse tumor model. Adoptively transferred pDC-STAMP/OVA-transfected DCs induced strong CD8+ T-cell proliferation in vivo. These experiments demonstrate that our DC-directed promoter constructs are potential tools to restrict antigen expression in DC and could be implemented to modulate DC function by the introduction of relevant proteins.

The burden of disease of retinal vein occlusion: review of the literature.

Retinal vein occlusion (RVO) is the second most common cause of vision loss due to retinal vascular disease. A literature review was undertaken to understand the epidemiology, clinical consequence, current practice patterns, and cost of RVO. Pertinent articles were identified by computerized searches of the English language literature in MEDLINE supplemented with electronic and manual searches of society/association proceedings and bibliographies of electronically identified sources. Population-based studies report a prevalence rate of 0.5-2.0% for branch RVO and 0.1-0.2% for central RVO. The 15-year incidence rate is estimated to be 1.8% for branch RVO and 0.2% for central RVO. Patients with RVO report lower vision-related quality of life than those without ocular disease. Available treatment options are limited. Until recently there was no treatment for central RVO. Laser photocoagulation is only recommended for branch RVO in patients who have not experienced severe vision loss. Emerging evidence on the effectiveness of intravitreal anti-vascular endothelial growth factor therapy and dexamethasone intravitreal implant is promising. Information on the treatment patterns and cost of RVO is extremely limited with one retrospective analysis of secondary insurance payment data identified and limited to the United States population only. A better understanding of the economic and societal impact of RVO will help decision makers evaluate emerging medical interventions for this sight-threatening disease.

DC-SCRIPT: nuclear receptor modulation and prognostic significance in primary breast cancer.

BACKGROUND: Nuclear receptors, including estrogen receptor (ER), progesterone receptor (PR)-B, peroxisome proliferator-activated receptor gamma, and retinoic acid receptor alpha, have been implicated in breast cancer etiology and progression. We investigated the role of dendritic cell-specific transcript (DC-SCRIPT) as coregulator of these nuclear receptors and as a prognostic factor in breast cancer. METHODS: The effect of DC-SCRIPT on the transcriptional activity of nuclear receptors was assessed by luciferase reporter assays. DC-SCRIPT expression in normal and tumor tissue from breast cancer patients was analyzed by polymerase chain reaction and immunohistochemistry. The prognostic value of tumor DC-SCRIPT mRNA expression was assessed in three independent cohorts of breast cancer patients: a discovery group (n = 47) and a validation group (n = 97) (neither of which had received systemic adjuvant therapy) and in a tamoxifen-treated validation group (n = 68) by using a DC-SCRIPT to porphobilinogen deaminase transcript ratio cutoff of 0.15 determined in the discovery group. Univariate and multivariable Cox proportional hazards model analyses were performed. All statistical tests were two-sided. RESULTS: DC-SCRIPT suppressed ER- and PR-mediated transcription in a ligand-dependent fashion, whereas it enhanced the retinoic acid receptor alpha- and peroxisome proliferator-activated receptor gamma-mediated transcription. In breast tissue samples from nine patients, DC-SCRIPT mRNA was expressed at lower levels in the tumor than in the corresponding normal tissue (P = .010). Patients in the discovery group with high tumor DC-SCRIPT mRNA levels (66%) had a longer disease-free interval than those with a low DC-SCRIPT mRNA level (34%) (hazard ratio [HR] of recurrence for high vs low DC-SCRIPT level = 0.23, 95% confidence interval [CI] = 0.06 to 0.93, P = .039), which was confirmed in the validation group (HR of recurrence = 0.50, 95% CI = 0.26 to 0.95, P = .034). This prognostic value was confined to patients with ER- and/or PR-positive tumors (discovery group: HR of recurrence = 0.16, 95% CI = 0.03 to 0.89, P = .030; validation group: HR of recurrence = 0.42, 95% CI = 0.19 to 0.91, P = .028) and was also observed in the second validation group (HR = 0.46, 95% CI = 0.22 to 0.97, P = .040). DC-SCRIPT was an independent prognostic factor after correction for tumor size, lymph node status, and adjuvant therapy (n = 145; HR = 0.50, 95% CI = 0.29 to 0.85, P = .010). CONCLUSION: DC-SCRIPT is a key regulator of nuclear receptor activity that has prognostic value in breast cancer.

Increased expression of CCL18, CCL19, and CCL17 by dendritic cells from patients with rheumatoid arthritis, and regulation by Fc gamma receptors.

BACKGROUND: Dendritic cells (DC) have a role in the regulation of immunity and tolerance, attracting inflammatory cells by the production of various chemokines (CK). Fc gamma receptors (Fc gamma R) may be involved in regulation of the DC function. OBJECTIVE: To assess the expression of CK by immature (iDC) and mature DC (mDC) and its regulation by Fc gamma R in patients with RA and healthy donors (HC). METHODS: Expression of CK by DC from patients with RA and from HC was determined by real time quantitative PCR and ELISA. DC were derived from monocytes following standardised protocols. To study the potential regulation by Fc gamma R, iDC were stimulated with immune complexes (IC) during lipopolysaccharide (LPS) induced maturation. The presence of CK was studied in synovial tissue from patients with RA, osteoarthritis, and healthy subjects by RT-PCR and immunohistochemistry. RESULTS: iDC from patients with RA had markedly increased mRNA levels of the CK CCL18 and CXCL8. Upon maturation with LPS, expression of CCL18, CCL19, CXCL8, CCL3, and CCL17 increased dramatically, reaching significantly higher levels in patients with RA. Monocytes failed to express these CK, except for CXCL8 and CCL3. IC-mediated triggering of the Fc gamma R on DC from patients with highly active RA down regulated all CK, whereas the reverse was seen when DC from patients with low disease activity and healthy donors were stimulated. CCL18 was significantly increased in RA synovial tissue. CONCLUSION: Increased CK expression by DC was found in patients with RA. This expression is partly regulated by Fc gamma R triggering and results in an inhibitory DC subtype in RA upon Fc gamma R-mediated triggering.

DC-STAMP, a novel multimembrane-spanning molecule preferentially expressed by dendritic cells.

Dendritic cells (DC) are unique in their ability to present antigen to naive T cells, and therefore play a central role in the initiation of immune responses. Characterization of DC-specific genes may help to unravel the mechanism underlying their potent antigen presenting capacity. Here we describe the identification of a novel transcript, isolated by random sequencing of a cDNA library prepared from monocyte-derived DC, which we termed DC-specific transmembrane protein (DC-STAMP). DC-STAMP is specifically expressed by DC, and not in a panel of other leukocytes or non-hematopoietic cells. Interestingly, DC-STAMP was also detected in activated but not resting blood DC. The DC-STAMP transcript encodes a 470-amino acid protein containing seven putative transmembrane domains. Expression of a DC-STAMP-GFP fusion protein in 293 cells indicates that DC-STAMP is expressed at the cell surface, and has an intracellular C terminus. Surprisingly, no sequence homology was found with any other protein or multimembrane-spanning receptor. Therefore, we propose that DC-STAMP is a novel DC-specific multimembrane-spanning protein, representing a new group of transmembrane proteins.

Improvement of fragment and primer selection for mutation detection by denaturing gradient gel electrophoresis.

Denaturing gradient gel electrophoresis (DGGE) is one of the most powerful methods for mutation detection currently available. For successful application the appropriate selection of PCR fragments and PCR primers is crucial. The sequence of interest should always be within the domain with the lowest melting temperature. When more than one melting domain is present the fragment is generally divided into several smaller ones. This, however, is not always necessary. We found that simple modifications of PCR fragments and primer sequences may substantially reduce the number of amplicons required. Furthermore, by plotting the (natural) melting curves of fragments without a GC-clamp, we could explain why fragments theoretically perfect for DGGE in practice failed to reveal mutations. Alternative fragment selection and the use of modified primers (addition of T/A or G/C tails) result in the detection of mutations that originally remained undetected. Our studies extend the utility of DGGE by using a minimum of PCR fragments and achieving a maximum of mutation detection.

MSH2 and MLH1 mutations in sporadic replication error-positive colorectal carcinoma as assessed by two-dimensional DNA electrophoresis.

Replication errors (RER) are frequently seen in both sporadic and hereditary forms of colorectal cancer. In hereditary nonpolyposis colorectal cancer (HNPCC), RER is associated with defects in DNA mismatch repair genes. Two of these genes, MSH2 and MLH1, account for a major share of this cancer syndrome. In order to assess the role of these genes in sporadic RER+ colorectal carcinoma, we have carried out a mutation analysis of MSH2 and MLH1 by two-dimensional (2-D) DNA electrophoresis, including heteroduplexing and separation in a denaturing gradient. All exons were amplified using multiplex PCR and were separated on the basis of both size and base pair composition under a single set of experimental conditions. Exons showing a spot position different from normal were sequenced. In screening 33 unselected, sporadic RER+ colorectal tumors, a germline mutation accompanied by loss of heterozygosity in tumor tissue was found in two patients. They were among the 4 patients out of the 33 screened that were diagnosed before the age of 50 years. In 8 of the remaining 31 tumors (26%), presence of somatic mutations (9 in total) could be demonstrated. While suggesting involvement of other genes in a substantial part of sporadic RER+ colorectal carcinomas, our results also demonstrate a clear role of MSH2 and MLH1 in these sporadic tumors and show that young sporadic RER+ colorectal carcinoma patients have a high probability of germline mutations. This has important implications for genetic testing and management of young colorectal cancer patients and their families.