Heterozygous germline mutations in BMPR2, encoding a TGF-beta receptor, cause familial primary pulmonary hypertension

Primary pulmonary hypertension (PPH), characterized by obstruction of pre-capillary pulmonary arteries, leads to sustained elevation of pulmonary arterial pressure (mean >25 mm Hg at rest or >30 mm Hg during exercise). The aetiology is unknown, but the histological features reveal proliferation of endothelial and smooth muscle cells with vascular remodelling (Fig. 1). More than one affected relative has been identified in at least 6% of cases (familial PPH, MIM 178600). Familial PPH (FPPH) segregates as an autosomal dominant disorder with reduced penetrance and has been mapped to a locus designated PPH1 on 2q33, with no evidence of heterogeneity. We now show that FPPH is caused by mutations in BMPR2, encoding a TGF-beta type II receptor (BMPR-II). Members of the TGF-beta superfamily transduce signals by binding to heteromeric complexes of type I and II receptors, which activates serine/threonine kinases, leading to transcriptional regulation by phosphorylated Smads. By comparison with in vitro studies, identified defects of BMPR-II in FPPH are predicted to disrupt ligand binding, kinase activity and heteromeric dimer formation. Our data demonstrate the molecular basis of FPPH and underscore the importance in vivo of the TGF-beta signalling pathway in the maintenance of blood vessel integrity.

Vaginal progesterone reduces the rate of preterm birth in women with a sonographic short cervix: a multicenter, randomized, double-blind, placebo-controlled trial

OBJECTIVES

Women with a sonographic short cervix in the mid-trimester are at increased risk for preterm delivery. This study was undertaken to determine the efficacy and safety of using micronized vaginal progesterone gel to reduce the risk of preterm birth and associated neonatal complications in women with a sonographic short cervix.

METHODS

This was a multicenter, randomized, double-blind, placebo-controlled trial that enrolled asymptomatic women with a singleton pregnancy and a sonographic short cervix (10-20 mm) at 19 + 0 to 23 + 6 weeks of gestation. Women were allocated randomly to receive vaginal progesterone gel or placebo daily starting from 20 to 23 + 6 weeks until 36 + 6 weeks, rupture of membranes or delivery, whichever occurred first. Randomization sequence was stratified by center and history of a previous preterm birth. The primary endpoint was preterm birth before 33 weeks of gestation. Analysis was by intention to treat.

RESULTS

Of 465 women randomized, seven were lost to follow-up and 458 (vaginal progesterone gel, n=235; placebo, n=223) were included in the analysis. Women allocated to receive vaginal progesterone had a lower rate of preterm birth before 33 weeks than did those allocated to placebo (8.9% (n=21) vs 16.1% (n=36); relative risk (RR), 0.55; 95% CI, 0.33-0.92; P=0.02). The effect remained significant after adjustment for covariables (adjusted RR, 0.52; 95% CI, 0.31-0.91; P=0.02). Vaginal progesterone was also associated with a significant reduction in the rate of preterm birth before 28 weeks (5.1% vs 10.3%; RR, 0.50; 95% CI, 0.25-0.97; P=0.04) and 35 weeks (14.5% vs 23.3%; RR, 0.62; 95% CI, 0.42-0.92; P=0.02), respiratory distress syndrome (3.0% vs 7.6%; RR, 0.39; 95% CI, 0.17-0.92; P=0.03), any neonatal morbidity or mortality event (7.7% vs 13.5%; RR, 0.57; 95% CI, 0.33-0.99; P=0.04) and birth weight < 1500 g (6.4% (15/234) vs 13.6% (30/220); RR, 0.47; 95% CI, 0.26-0.85; P=0.01). There were no differences in the incidence of treatment-related adverse events between the groups.

CONCLUSIONS

The administration of vaginal progesterone gel to women with a sonographic short cervix in the mid-trimester is associated with a 45% reduction in the rate of preterm birth before 33 weeks of gestation and with improved neonatal outcome.

Mutations in PROP1 cause familial combined pituitary hormone deficiency

Combined pituitary hormone deficiency (CPHD) in man denotes impaired production of growth hormone (GH) and one or more of the other five anterior pituitary hormones. Mutations of the pituitary transcription factor gene POU1F1 (the human homologue of mouse Pit1) are responsible for deficiencies of GH, prolactin and thyroid stimulating hormone (TSH) in Snell and Jackson dwarf mice and in man, while the production of adrenocorticotrophic hormone (ACTH), luteinizing hormone (LH) and follicle stimulating hormone (FSH) is preserved. The Ames dwarf (df) mouse displays a similar phenotype, and appears to be epistatic to Snell and Jackson dwarfism. We have recently positionally cloned the putative Ames dwarf gene Prop1, which encodes a paired-like homeodomain protein that is expressed specifically in embryonic pituitary and is necessary for Pit1 expression. In this report, we have identified four CPHD families with homozygosity or compound heterozygosity for inactivating mutations of PROP1. These mutations in the human PROP1 gene result in a gene product with reduced DNA-binding and transcriptional activation ability in comparison to the product of the murine df mutation. In contrast to individuals with POU1F1 mutations, those with PROP1 mutations cannot produce LH and FSH at a sufficient level and do not enter puberty spontaneously. Our results identify a major cause of CPHD in humans and suggest a direct or indirect role for PROP1 in the ontogenesis of pituitary gonadotropes, as well as somatotropes, lactotropes and caudomedial thyrotropes.

Molecular assembly of an aptamer-drug conjugate for targeted drug delivery to tumor cells

The conjugation of antitumor drugs to targeting reagents such as antibodies is a promising method that can increase the efficacy of chemotherapy and reduce the overall toxicity of the drugs. In this study, we covalently link the antitumor agent doxorubicin (Dox) to the DNA aptamer sgc8c, which was selected by the cell-SELEX method. In doing so, we expected that this sgc8c-Dox conjugate would specifically kill the target CCRF-CEM (T-cell acute lymphoblastic leukemia, T-cell ALL) cells, but with minimal toxicity towards nontarget cells. The results demonstrated that the sgc8c-Dox conjugate possesses many of the properties of the sgc8c aptamer, including high binding affinity (K(d)=2.0+/-0.2 nM) and the capability to be efficiently internalized by target cells. Moreover, due to the specific conjugation method, the acid-labile linkage connecting the sgc8c-Dox conjugate can be cleaved inside the acidic endosomal environment. Cell viability tests demonstrate that the sgc8c-Dox conjugates not only possess potency similar to unconjugated Dox, but also have the required molecular specificity that is lacking in most current targeted drug delivery strategies. Furthermore, we found that nonspecific uptake of membrane-permeable Dox to nontarget cell lines could also be inhibited by linking the drug with the aptamer; thus, the conjugates are selective for cells that express higher amounts of target proteins. Compared to the less effective Dox-immunoconjugates, these sgc8c-Dox conjugates make targeted chemotherapy more feasible with drugs having various potencies. When combined with the large number of recently created DNA aptamers that specifically target a wide variety of cancer cells, this drug-aptoconjugation method will have broad implications for targeted drug delivery.

Role of the angiotensin type 2 receptor gene in congenital anomalies of the kidney and urinary tract, CAKUT, of mice and men

Angiotensin type 2 receptor gene null mutant mice display congenital anomalies of the kidney and urinary tract (CAKUT). Various features of mouse CAKUT impressively mimic human CAKUT. Studies of the human type 2 receptor (AGTR2) gene in two independent cohorts found that a significant association exists between CAKUT and a nucleotide transition within the lariat branchpoint motif of intron 1, which perturbs AGTR2 mRNA splicing efficiency. AGTR2, therefore, has a significant ontogenic role for the kidney and urinary tract system. Studies revealed that the establishment of CAKUT is preceded by delayed apoptosis of undifferentiated mesenchymal cells surrounding the urinary tract during key ontogenic events, from the ureteral budding to the expansive growth of the kidney and ureter.

Aptamer-nanoparticle strip biosensor for sensitive detection of cancer cells

We report an aptamer-nanoparticle strip biosensor (ANSB) for the rapid, specific, sensitive, and low-cost detection of circulating cancer cells. Known for their high specificity and affinity, aptamers were first selected from live cells by the cell-SELEX (systematic evolution of ligands by exponential enrichment) process. When next combined with the unique optical properties of gold nanoparticles (Au-NPs), ANSBs were prepared on a lateral flow device. Ramos cells were used as a model target cell to demonstrate proof of principle. Under optimal conditions, the ANSB was capable of detecting a minimum of 4000 Ramos cells without instrumentation (visual judgment) and 800 Ramos cells with a portable strip reader within 15 min. Importantly, ANSB has successfully detected Ramos cells in human blood, thus providing a rapid, sensitive, and low-cost quantitative tool for the detection of circulating cancer cells. ANSB therefore shows great promise for in-field and point-of-care cancer diagnosis and therapy.

Mutation in the gene for bone morphogenetic protein receptor II as a cause of primary pulmonary hypertension in a large kindred

BACKGROUND

Most patients with primary pulmonary hypertension are thought to have sporadic, not inherited, disease. Because clinical disease develops in only 10 to 20 percent of persons carrying the gene for familial primary pulmonary hypertension, we hypothesized that many patients with apparently sporadic primary pulmonary hypertension may actually have familial primary pulmonary hypertension.

METHODS

In a study conducted over 20 years, we developed a registry of 67 families affected by familial primary pulmonary hypertension. Through patient referrals, extensive family histories, and correlation of family pedigrees, we discovered shared ancestry among five subfamilies. We established the diagnosis of primary pulmonary hypertension by direct evaluation of patients and review of autopsy material and medical records. We assessed some family members for mutations in the gene encoding bone morphogenetic protein receptor II (BMPR2), which has recently been found to cause familial primary pulmonary hypertension.

RESULTS

We linked five separately identified subfamilies that included 394 known members spanning seven generations, which were traced back to a founding couple in the mid-1800s. Familial primary pulmonary hypertension has been diagnosed in 18 family members, 12 of whom were first thought to have sporadic disease. The conditions of 7 of the 18 were initially misdiagnosed as other cardiopulmonary diseases. Six members affected with familial primary pulmonary hypertension and 6 of 10 at risk for carriage have been undergone genotype analysis, and they have the same mutation in BMPR2, a transversion of thymine to guanine at position 354 in exon 3.

CONCLUSIONS

Many cases of apparently sporadic primary pulmonary hypertension may be familial. Failure to detect familial primary pulmonary hypertension results from incomplete expression within families, skipped generations, and incomplete family pedigrees. The recent discovery of mutations in BMPR2 should make it possible to identify those with susceptibility to disease.

siRNA therapeutics: big potential from small RNAs

RNA interference (RNAi) is now an umbrella term referring to post-transcriptional gene silencing mediated by either degradation or translation arrest of target RNA. This process is initiated by double-stranded RNA with sequence homology driving specificity. The discovery that 21-23 nucleotide RNA duplexes (small-interfering RNAs, siRNAs) mediate RNAi in mammalian cells opened the door to the therapeutic use of siRNAs. While much work remains to optimize delivery and maintain specificity, the therapeutic advantages of siRNAs for treatment of viral infection, dominant disorders, cancer, and neurological disorders show great promise.

Localization of the gene for familial primary pulmonary hypertension to chromosome 2q31-32

Primary pulmonary hypertension (PPH), an often fatal disease, is characterized by elevated pulmonary artery pressures in the absence of a secondary cause. Endovascular occlusion in the smallest pulmonary arteries occurs by proliferation of cells and matrix, with thrombus and vasospasm. Diagnosis is often delayed because the initial symptoms of fatigue and dyspnea on exertion are nonspecific and definitive diagnosis requires invasive procedures. The average life expectancy after diagnosis is two to three years with death usually due to progressive right heart failure. The aetiology of the disease is unknown. Although most cases appear to be sporadic, approximately 6% of cases recorded in the NIH Primary Pulmonary Hypertension Registry are inherited in an autosomal dominant manner with reduced penetrance. Following a genome-wide search using a set of highly polymorphic short tandem repeat (STR) markers and 19 affected individuals from six families, initial evidence for linkage was obtained with two chromosome 2q markers. We subsequently genotyped patients and all available family members for 19 additional markers spanning approximately 40 centiMorgans (cM) on the long arm of chromosome 2. We obtained a maximum two-point lod score of 6.97 at theta = 0 with the marker D2S389; multipoint linkage analysis yielded a maximum lod score of 7.86 with the marker D2S311. Haplotype analysis established a minimum candidate interval of approximately 25 cM.

Aptamer-based microfluidic device for enrichment, sorting, and detection of multiple cancer cells

The ability to diagnose cancer based on the detection of rare cancer cells in blood or other bodily fluids is a significant challenge. To address this challenge, we have developed a microfluidic device that can simultaneously sort, enrich, and then detect multiple types of cancer cells from a complex sample. The device, which is made from poly(dimethylsiloxane) (PDMS), implements cell-affinity chromatography based on the selective cell-capture of immobilized DNA-aptamers and yields a 135-fold enrichment of rare cells in a single run. This enrichment is achieved because the height of the channel is on the order of a cell diameter. The sorted cells grow at the comparable rate as cultured cells and are 96% pure based on flow cytometry determination. Thus, by using our aptamer based device, cell capture is achieved simply and inexpensively, with no sample pretreatment before cell analysis. Enrichment and detection of multiple rare cancer cells can be used to detect cancers at the early stages, diagnose metastatic relapse, stratify patients for therapeutic purposes, monitor response to drugs and therapies, track tumor progression, and gain a deeper understanding of the biology of circulating tumor cells (CTCs).

Genetic mutations in surfactant protein C are a rare cause of sporadic cases of IPF

BACKGROUND

While idiopathic pulmonary fibrosis (IPF) is one of the most common forms of interstitial lung disease, the aetiology of IPF is poorly understood. Familial cases of pulmonary fibrosis suggest a genetic basis for some forms of the disease. Recent reports have linked genetic mutations in surfactant protein C (SFTPC) with familial forms of pulmonary fibrosis, including one large family in which a number of family members were diagnosed with usual interstitial pneumonitis (UIP), the pathological correlate to IPF. Because of this finding in familial cases of pulmonary fibrosis, we searched for SFTPC mutations in a cohort of sporadic cases of UIP and non-specific interstitial pneumonitis (NSIP).

METHODS

The gene for SFTPC was sequenced in 89 patients diagnosed with UIP, 46 patients with NSIP, and 104 normal controls.

RESULTS

Ten single nucleotide polymorphisms in the SFTPC sequence were found in IPF patients and not in controls. Only one of these created an exonic change resulting in a change in amino acid sequence. In this case, a T to C substitution resulted in a change in amino acid 73 of the precursor protein from isoleucine to threonine. Of the remaining polymorphisms, one was in the 5' UTR, two were exonic without predicted amino acid sequence changes, and six were intronic. One intronic mutation suggested a potential enhancement of a splicing site.

CONCLUSIONS

Mutations in SFTPC are identified infrequently in this patient population. These findings indicate that SFTPC mutations do not contribute to the pathogenesis of IPF in the majority of sporadic cases.

Regulation of singlet oxygen generation using single-walled carbon nanotubes

We have designed a novel photodynamic therapy (PDT) agent using protein binding aptamer, photosensitizer, and single-walled carbon nanotube (SWNT). The PDT is based on covalently linking a photosensitizer with an aptamer then wrapping onto the surface of SWNTs, such that the photosensitizer can only be activated by light upon target binding. We have chosen the human alpha-thrombin aptamer and covalently linked it with Chlorin e6 (Ce6), which is a second generation photosensitizer. Our results showed that SWNTs are great quenchers to singlet oxygen generation (SOG). In the presence of its target, the binding of target thrombin will disturb the DNA interaction with the SWNTs and cause the DNA aptamer to fall off the SWNT surface, resulting in the restoration of SOG. This study validated the potential of our design as a novel PDT agent with regulation by target molecules, enhanced specificity, and efficacy of therapeutic function, which directs the development of photodynamic therapy to be safer and more selective.

Genetic anticipation and abnormal gender ratio at birth in familial primary pulmonary hypertension

The genetic basis of familial primary pulmonary hypertension (FPPH) is unknown, but the clinical and pathologic features are the same as in sporadically occurring primary pulmonary hypertension (PPH). Because few families with this disease have been reported, the mode of inheritance and genetic features have not been clearly established. We previously reported a tendency for decreasing age of onset in subsequent generations of affected families. The purpose of this study was to examine the pattern of inheritance in a large number of families in an attempt to find clues to pathogenesis. From 24 families we studied 429 members, 124 of whom were known to carry the gene for disease. We constructed cumulative mortality curves for each gender of the 99 affected individuals. We analyzed gender ratios of progeny of affected members and carriers and compared age at death of affected members by generation. More females (160) than males (122) were born to persons carrying the gene, p < 0.01, suggesting selective wastage of male fetuses or an abnormal primary sex ratio. Genetic anticipation was confirmed; the age at death was 45.6 +/- 14.5 versus 36.3 +/- 12.6 versus 24.2 +/- 11 standard deviation (SD) years in successive generations, p < 0.05. Five cases of male-to-male transmission were observed, excluding X-linkage. Age at death was the same for males and females. More females had the gene (84 females, 40 males) and more females with the gene developed disease (72 of 84 females [86%] versus 27 of 40 males [68%]). The disease has highly variable penetrance among families.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular recognition of acute myeloid leukemia using aptamers

Cell surface proteins can play important roles in cancer pathogenesis. Comprehensive understanding of the surface protein expression patterns of tumor cells and, consequently, the pathogenesis of tumor cells, depends on molecular probes against these proteins. To be effectively used for tumor diagnosis, classification and therapy, such probes would be capable of specific binding to targeted tumor cells. Molecular aptamers, designer DNA/RNA probes, can address this challenge by recognizing proteins, peptides and other small molecules with high affinity and specificity. Through a process known as cell-SELEX, we used live acute myeloid leukemia (AML) cells to select a group of DNA aptamers that can recognize acute myeloid leukemia cells with dissociation constants (Kds) in the nanomolar range. Interestingly, one aptamer (KH1C12), compared with two control cell lines (K562 and NB4), showed significant selectivity to the target AML cell line (HL60) and could recognize the target cells within a complex mixture of normal bone marrow aspirates. The other two aptamers KK1B10 and KK1D04 recognize targets associated with monocytic differentiation. Our studies demonstrate that the selected aptamers can be used as a molecular tool for further understanding surface protein expression patterns on tumor cells and thus providing a foundation for effective molecular analysis of leukemia and its subcategories.

Cell-surface sensors for real-time probing of cellular environments

The ability to explore cell signalling and cell-to-cell communication is essential for understanding cell biology and developing effective therapeutics. However, it is not yet possible to monitor the interaction of cells with their environments in real time. Here, we show that a fluorescent sensor attached to a cell membrane can detect signalling molecules in the cellular environment. The sensor is an aptamer (a short length of single-stranded DNA) that binds to platelet-derived growth factor (PDGF) and contains a pair of fluorescent dyes. When bound to PDGF, the aptamer changes conformation and the dyes come closer to each other, producing a signal. The sensor, which is covalently attached to the membranes of mesenchymal stem cells, can quantitatively detect with high spatial and temporal resolution PDGF that is added in cell culture medium or secreted by neighbouring cells. The engineered stem cells retain their ability to find their way to the bone marrow and can be monitored in vivo at the single-cell level using intravital microscopy.

Carbon nanotubes protect DNA strands during cellular delivery

To protect against nuclease digestion, or single-strand binding protein interactions, oligonucleotides for targeted delivery into intracellular systems must be stable. To accomplish this, we have developed single-walled carbon nanotubes as a carrier for single-stranded DNA probe delivery. This has resulted in superior biostability for intracellular application and, hence, has achieved the desired protective attributes, which are particularly important when DNA probes are used for intracellular measurements. Specifically, when bound to single-walled carbon nanotubes, DNA probes are protected from enzymatic cleavage and interference from nucleic acid binding proteins. Moreover, and equally important, our study shows that a single-walled carbon nanotube-modified DNA probe, which targets a specific mRNA inside living cells, has increased self-delivery capability and intracellular biostability when compared to free DNA probes. Therefore, this new conjugate provides significant advantages for basic genomic studies in which DNA probes are used to monitor intracellular levels of molecules.

Anatomic constraints on cognitive theories of category specificity

Many cognitive theories of semantic organization stem from reports of patients with selective, category-specific deficits for particular classes of objects (e.g., fruit). The anatomical assumptions underlying the competing claims can be evaluated with functional neuroimaging but the findings to date have been inconsistent and insignificant when standard statistical criteria are adopted. We hypothesized that category differences in functional brain responses might be small and task dependent. To test this hypothesis, we entered data from seven PET studies into a single multifactorial design which crossed category (living vs man-made) with a range of tasks. Reliable category-specific effects were observed but only for word retrieval and semantic decision tasks. Living things activated medial aspects of the anterior temporal poles bilaterally while tools activated a left posterior middle temporal region. These category-by-task interactions provide robust evidence for an anatomical double dissociation according to category and place strong constraints on cognitive theories of the semantic system. Furthermore they reconcile some of the apparent inconsistencies between lesion studies and functional neuroimaging data.

Nucleic acid aptamers for biosensors and bio-analytical applications

Oligonucleotides were once considered only functional as molecules for the storage of genetic information. However, the discovery of RNAzymes, and later, DNAzymes, unravelled the innate potential of oligonucleotides in many other biological applications. In the last two decades, these applications have been further expanded through the introduction of Systematic Evolution of Ligands by EXponential enrichment (SELEX) which has generated, by repeated rounds of in vitro selection, a type of molecular probe termed aptamers. Aptamers are oligonucleic acid (or peptide) molecules that can bind to various molecular targets and are viewed as complements to antibodies. Aptamers have found applications in many areas, such as bio-technology, medicine, pharmacology, microbiology, and analytical chemistry, including chromatographic separation and biosensors. In this review, we focus on the use of aptamers in the development of biosensors. Coupled with their ability to bind a variety of targets, the robust nature of oligonucleotides, in terms of synthesis, storage, and wide range of temperature stability and chemical manipulation, makes them highly suitable for biosensor design and engineering. Among the many design strategies, we discuss three general paradigms that have appeared most frequently in the literature: structure-switching, enzyme-based, and aptazyme-based designs.

Alterations in oestrogen metabolism: implications for higher penetrance of familial pulmonary arterial hypertension in females

Mutations in bone morphogenetic protein receptor type 2 (BMPR2) cause familial pulmonary arterial hypertension (FPAH), but the penetrance is reduced and females are significantly overrepresented. In addition, gene expression data implicating the oestrogen-metabolising enzyme CYP1B1 suggests a detrimental role of oestrogens or oestrogen metabolites. We examined genetic and metabolic markers of altered oestrogen metabolism in subjects with a BMPR2 mutation. Genotypes for CYP1B1 Asn453Ser (N453S) were determined for 140 BMPR2 mutation carriers (86 females and 54 males). Nested from those subjects, a case-control study of urinary oestrogen metabolite levels (2-hydroxyoestrogen (2-OHE) and 16alpha-hydroxyoestrone (16alpha-OHE(1))) was conducted in females (five affected mutation carriers versus six unaffected mutation carriers). Among females, there was four-fold higher penetrance among subjects homozygous for the wild-type genotype (N/N) than those with N/S or S/S genotypes (p = 0.005). Consistent with this finding, the 2-OHE/16alpha-OHE(1) ratio was 2.3-fold lower in affected mutation carriers compared to unaffected mutation carriers (p = 0.006). Our findings suggest that variations in oestrogens and oestrogen metabolism modify FPAH risk. Further investigation of the role of oestrogens in this disease with profound sex bias may yield new insights and, perhaps, therapeutic interventions.

Enrichment of cancer cells using aptamers immobilized on a microfluidic channel

This work describes the development and investigation of an aptamer modified microfluidic device that captures rare cells to achieve a rapid assay without pretreatment of cells. To accomplish this, aptamers are first immobilized on the surface of a poly(dimethylsiloxane) microchannel, followed by pumping a mixture of cells through the device. This process permits the use of optical microscopy to measure the cell-surface density from which we calculate the percentage of cells captured as a function of cell and aptamer concentration, flow velocity, and incubation time. This aptamer-based device was demonstrated to capture target cells with >97% purity and >80% efficiency. Since the cell capture assay is completed within minutes and requires no pretreatment of cells, the device promises to play a key role in the early detection and diagnosis of cancer where rare diseased cells can first be enriched and then captured for detection.

Molecular basis for familial isolated growth hormone deficiency

Nuclear DNA from four individuals with familial isolated growth hormone (somatotropin) deficiency (IGHD) type A was studied by restriction endonuclease analysis. By using 32P-labeled human growth hormone (hGH) cDNA sequences as a probe, patterns seen after various digestions indicated that these individuals were homozygous for a deletion of at least 7.5 kilobases (kb) of DNA. This deletion includes the gene that encodes the normal growth hormone but does not include the variant growth hormone gene. Restriction patterns of DNAs from all family members agreed with an autosomal recessive mode of inheritance of the deletion that correlates with the clinical phenotype. Furthermore, independent assortment of the two types of hGH genes suggests that these genes are nonallelic. These findings indicate that, in these families, IGHD type A is caused by deletion of the normal hGH genes and that this disorder can occur in the presence of variant hGH genes.

Angiotensin converting enzyme gene polymorphism: potential silencer motif and impact on progression in IgA nephropathy

Since the renin angiotensin system (RAS) is established as an important factor in renal disease progression, we determined whether RAS alleles that have been linked to variability in outcome in several cardiovascular diseases also affect progression of IgA nephropathy. These genetic variants include: (1) angiotensin I converting enzyme deletion polymorphism in intron 16 (ACE I/D), reported to be associated with increased risk of myocardial infarction as well as left ventricular hypertrophy; (2) a point mutation in the angiotensinogen (Agt) gene resulting in a methionine to threonine substitution at residue 235 (M235T), reported to be associated with hypertension in Caucasians; and (3) an angiotensin receptor type I (ATR) A to C transition at bp 1166 (A1166C) which shows synergy with the deleterious effects of the ACE DD genotype in myocardial infarction. We examined these polymorphisms by PCR amplification of genomic DNA samples from 64 Caucasian patients in the USA (age 6 to 83 years) with biopsy-proven IgA nephropathy whose renal status was followed for an average of almost seven years. Patients who presented with and maintained normal serum creatinine (Cr, < 1.5 mg/dl), had ACE genotype frequencies of II:35%, ID:61%, DD:4%. By contrast, in patients with progression (initially normal Cr increased to a mean of 4.5 +/- 0.86 mg/dl), ACE genotype frequencies were II:22%, ID:44%, DD:33% (P = 0.057 by Fishers's exact test, vs. non-progressors). The association of the DD genotype with progression was even more striking when patients with other risk factors (hypertension and/or heavy proteinuria) were excluded. In this subgroup, the genotype frequencies in patients with stable creatinine versus those with deterioration in renal function was 53%, 47%, and 0% versus 0%, 40%, and 60%, respectively, for II, ID, and DD genotypes (P = 0.009 by Fisher's exact test, progressors vs. non-progressors). Further, sequence analysis of the I gene polymorphism revealed a potential 13 bp silence motif. Neither the Agt 235T nor the ATR A 1166C gene variants, however, was associated with deterioration of renal function. Taken together, these results indicate that, although polymorphism in each of the three genes in the RAS system has been linked to cardiovascular diseases, only the ACE I/D polymorphism is associated with progressive deterioration in renal function in IgA nephropathy. Since previous observations link ACE polymorphism with ACE activity, these findings imply a widespread importance of ACE in modulating destructive processes in different organs.

Using photons to manipulate enzyme inhibition by an azobenzene-modified nucleic acid probe

The ability to inhibit an enzyme in a specific tissue with high spatial resolution combined with a readily available antidote should find many biomedical applications. We have accomplished this by taking advantage of the cis-trans photoisomerization of azobenzene molecules. Specifically, we positioned azobenzene moieties within the DNA sequence complementary to a 15-base-long thrombin aptamer and then linked the azobenzene-modified cDNA to the aptamer by a polyethylene glycol (PEG) linker to make a unimolecular conjugate. During the photoisomerization of azobenzene by visible light, the inhibition of thrombin is disabled because the probe hybridizes with the cDNA in the trans-azobenzene conformation so that the aptamer cannot bind its target thrombin. However, when UV light is applied, melting of the hairpin structure (duplex) is induced via trans-to-cis conversion, thereby changing conformation of the aptamer and making the aptamer free to bind to and inhibit its target thrombin. By using standard clotting assays, we measured the IC(200) of various probe designs in both states and concluded the feasibility of using photon energy to temporally and spatially regulate these enzymatic reactions. Thus, we can report the development of DNA probes in the form of photon-controllable (thrombin) inhibitors, termed PCIs, and we expect that this approach will be highly beneficial in future biomedical and pharmaceutical applications.

Etiology of growth hormone deficiency in little, Ames, and Snell dwarf mice

There are three recessive genes (little, Snell, and Ames) which cause dwarfism and GH deficiency in mice. These genes are nonallelic, and in the case of little mice, GH deficiency is isolated, while Snell and Ames dwarfs have deficiencies of GH as well as other anterior pituitary hormones. Previous reports in which restriction endonuclease analyses were used suggested that the GH genes are grossly intact in each of these types of dwarfs. In this report, ultrastructural studies of the anterior pituitary glands of little mice showed a deficiency or absence of secretory granules within somatotropes, while Snell and Ames dwarf pituitaries lacked identifiable somatotropes. Furthermore, there were deficiencies of GH precursor RNA and mRNA in total RNA from little pituitaries, while GH transcripts appeared to be absent in total RNA from Snell or Ames dwarf pituitaries. Thus, the primary defect in little mice may be in the production of GH transcripts, while GH deficiency in Snell and Ames dwarfs is probably due to defects other than alterations of the GH genes.

Respiratory complications of achondroplasia

Nine patients with achondroplasia who were seen over a three-year period developed significant respiratory complications. Eight had sleep-disordered breathing, including obstructive sleep apnea in five, for which two required tracheostomy. Of the seven patients with significant hypoxemia, five had clinical evidence of cor pulmonale and recurrent pulmonary infiltrates. Two patients died, one with autopsy findings of compression of the medulla at the level of the foramen magnum and one with respiratory and cardiac failure. Appropriate therapy for our patients depended on recognition of the mechanisms that led to the respiratory complications, including (1) chest deformity, (2) upper airway obstruction and sleep-disordered breathing, (3) neurologic complications, and (4) coincidental chronic pulmonary conditions such as asthma.