A rapid screening for steroid 21-hydroxylase mutations in patients with congenital adrenal hyperplasia. Mutations in brief no. 247. Online

Steroid 21-hydroxylase deficiency is the major cause of congenital adrenal hyperplasia (CAH). CAH due to 21-hydroxylase deficiency is divided into three classes: salt-wasting (classical), non-classical and simple virilizing, reflecting different degrees of clinical severity. Using polymerase chain reaction (PCR) and allele-specific oligonucleotide hybridisation (ASO), we screened the DNA of 62 Caucasian CAH families (heterozygous parents and children) for 14 different and frequently-found CYP21-mutations (HGMD). Of the 62 patients (21 males, 41 females), 26 females and 11 males had the classical or salt-wasting form, 3 females and 1 male had the non-classical form and 14 females and 7 males had simple virilizing CAH. More than 60% of the patients were compound-heterozygous. We found the mutations on 110 alleles (out of 124 alleles). There were 30 CYP21 gene deletions/conversions, 3 substitutions (P30L) in exon 1, 30 splice mutations (c.93-13A/C>G) in intron 2, 26 point mutations (I172N) in exon 4, one cluster of mutations (I236N, V237E, M239K) in exon 6, 8 mutations (V281L and 1760-1761insT) in exon 7, and 8 nonsense (Q318X) and 4 missense (R356W) mutations in exon 8. Our study supports the case for using this rapid technique for CAH-family screening as long as alleles from both affected patients and parents are screened in parallel.

Purification and reconstitution of an integral membrane protein, the photoreaction center of Rhodobacter sphaeroides, using synthetic sugar esters

Detergents are indispensable reagents for the extraction and solubilization of integral membrane proteins, but their removal from a reconstituted phospholipid-protein complex is usually desirable. In this paper, we describe a novel method in which the synthetic sugar esters 6-O-octanoyl-beta-D-glucose (OG) or 6-O-octanoyl-beta-D-mannose (OM) are used as detergents for both the isolation and the rapid reconstitution of the photosynthetic reaction center protein of Rhodobacter sphaeroides. Following solubilization of the reaction center with OG or OM and reconstitution of this protein in liposomes, a convenient removal of these detergents was achieved within less than two hours by hydrolytic cleavage of the sugar esters using immobilized lipases. Best results were achieved with lipase from Bacillus sp. immobilized on silica gel.

Msx2 deficiency in mice causes pleiotropic defects in bone growth and ectodermal organ formation

The composite structure of the mammalian skull, which forms predominantly via intramembranous ossification, requires precise pre- and post-natal growth regulation of individual calvarial elements. Disturbances of this process frequently cause severe clinical manifestations in humans. Enhanced DNA binding by a mutant MSX2 homeodomain results in a gain of function and produces craniosynostosis in humans. Here we show that Msx2-deficient mice have defects of skull ossification and persistent calvarial foramen. This phenotype results from defective proliferation of osteoprogenitors at the osteogenic front during calvarial morphogenesis, and closely resembles that associated with human MSX2 haploinsufficiency in parietal foramina (PFM). Msx2-/- mice also have defects in endochondral bone formation. In the axial and appendicular skeleton, post-natal deficits in Pth/Pthrp receptor (Pthr) signalling and in expression of marker genes for bone differentiation indicate that Msx2 is required for both chondrogenesis and osteogenesis. Consistent with phenotypes associated with PFM, Msx2-mutant mice also display defective tooth, hair follicle and mammary gland development, and seizures, the latter accompanied by abnormal development of the cerebellum. Most Msx2-mutant phenotypes, including calvarial defects, are enhanced by genetic combination with Msx1 loss of function, indicating that Msx gene dosage can modify expression of the PFM phenotype. Our results provide a developmental basis for PFM and demonstrate that Msx2 is essential at multiple sites during organogenesis.

Angiotensin II blockade and low-protein diet produce additive therapeutic effects in experimental glomerulonephritis

BACKGROUND

Transforming growth factor-beta (TGF-beta) overexpression plays a key role in the accumulation of extracellular matrix in acute and chronic renal diseases. Recent studies have suggested that the degree of reduction in pathological TGF-beta overexpression can be used as a therapeutic index to evaluate the antifibrotic potential of pharmacological angiotensin II (Ang II) blockade in renal disease. Using this target, we found that treatment with the angiotensin I-converting enzyme inhibitor enalapril or the Ang II type 1 receptor antagonist losartan reduced TGF-beta overexpression more effectively at doses clearly higher than those required to control blood pressure. However, both forms of Ang II blockade were only partially effective in normalizing TGF-beta expression. This study investigated whether a greater antifibrotic, TGF-beta-reducing benefit can be achieved when Ang II blockade is combined with dietary protein restriction.

METHODS

Mesangioproliferative glomerulonephritis was induced in male Sprague-Dawley rats on a normal-protein diet. Treatment with a low-protein diet and/or maximally effective doses of enalapril or losartan was started one day after disease induction. On the fifth day, 24-hour urine protein excretion was measured. On the sixth day, cortical kidney tissue was taken for periodic acid-Schiff staining. Isolated glomeruli were used for mRNA extraction or were placed in culture for determination of production of TGF-beta1, the matrix protein fibronectin, and the protease inhibitor plasmin activator inhibitor type 1 (PAI-1) by enzyme-linked immunosorbent assay.

RESULTS

Compared with untreated nephritic animals on a normal-protein diet, a single treatment with enalapril, losartan, or low-protein diet significantly reduced glomerular TGF-beta production, albeit to a similar degree of approximately 45%. A moderate, but significant further reduction in pathological TGF-beta expression of a total of 65% for enalapril and 60% for losartan was achieved when these drugs were combined with low-protein feeding. This reduction in TGF-beta overexpression paralleled decreased proteinuria, glomerular matrix accumulation, and overproduction of fibronectin and PAI-1.

CONCLUSIONS

Ang II blockade and low-protein diet have additive effects on disease reduction, suggesting that disease progression in humans with chronic renal failure may be slowed more effectively when Ang II blockade and low-protein diet are combined. Since maximal pharmacological Ang II inhibition was used, it is likely that dietary protein restriction further reduces pathological TGF-beta overexpression by mechanisms different from those of enalapril or losartan.

Tandem antifibrotic actions of L-arginine supplementation and low protein diet during the repair phase of experimental glomerulonephritis

BACKGROUND

Based upon the central role transforming growth factor-beta (TGF-beta) overexpression appears to play in renal fibrotic diseases, we have recently advocated reduction of TGF-beta as a therapeutic target. As part of efforts to determine the strength of this approach, we have undertaken studies to quantitate the effects of currently used and promising therapies in terms of their potential to reduce markers of disease in anti-thymocyte-serum (ATS)-glomerulonephritis in the rat. Here we assess the therapeutic effect of L-arginine supplementation, which has been shown to reduce fibrosis in a number of hypertensive models, given alone or in combination with low protein diet and started 24 hours after disease induction.

METHODS

Glomerulonephritis was induced by intravenous injection of OX-7 monoclonal antibody into 200 g Sprague-Dawley rats. Twenty-four hours later animals were placed in groups that were either untreated, treated with 1% L-arginine in drinking water or 6% protein diets or both. On the fifth day of disease 24-hour urine specimens were collected and systemic blood pressure was measured. On the sixth day rats were anesthetized. Kidneys were perfused, tissue was taken for PAS staining and glomeruli were isolated. Aliquots of glomeruli were used for RNA preparation and for culture to determine 72-hour production of TGF-beta, fibronectin and plasminogen activator-type 1 (PAI-1), which were assayed by ELISA on culture supernatants. Measures of nitrate and nitrite (NOx) production included plasma NOx, urinary NOx and glomerular production of NOx in culture.

RESULTS

All disease measures except proteinuria and including matrix accumulation, TGF-beta, fibronectin and PAI-1 production and mRNA expression for TGF-beta, fibronectin and PAI-1 were significantly and similarly reduced by about 50% in groups treated with L-arginine or with low protein diet. Proteinuria was reduced in low protein treated but not in L-arginine supplemented rats. Neither systemic blood pressure nor measures of NO synthesis showed differences between groups that could be attributed to L-arginine supplementation. In contrast, disease-related increases in glomerular production of NOx were markedly reduced by low protein. Combined therapy resulted in small, but statistically significant decreases in most measures of disease.

CONCLUSIONS

L-arginine supplementation reduces fibrotic disease in ATS-induced glomerulonephritis if started after disease induction. The absence of evidence for increased NO production related to L-arginine supplementation suggests that L-arginine is acting here through different pathways from those demonstrated in hypertensive models of disease. The data support the ideas that TGF-beta reduction is a valid therapeutic target and that quantitation of TGF-beta reduction is a useful approach for comparing antifibrotic drug candidates.

Heart failure in arrhythmogenic right ventricular dysplasia-cardiomyopathy

Sudden arrhythmic death and heart failure are essential factors influencing the prognosis of arrhythmogenic right ventricular dysplasia-cardiomyopathy. Heart failure is a rare, but often lethargic event although little is known about morphology, time course and non-invasive predictors.

METHOD

In a retrospective study of a consecutive cohort of 121 patients with ARVD over a follow-up period of up to 12 years morphological features of heart failure, time course from the initial diagnosis and standard 12-lead ECG as a non-invasive predictor of developing heart failure were analysed.

RESULTS

Heart failure occurred in 13 patients (11%) with isolated right ventricular dilatation and loss of function in 10 cases (77%) and biventricular failure in three cases (23%). Patients developed NYHA class IV in four cases, class III-IV in two cases and class II in seven cases in 4-8 years. In standard ECG of 12 patients (92%) complete right bundle branch block was present at the time of initial diagnosis (n=6) or in a time interval of 4 years (n=6). Morphological distinction of isolated right and biventricular heart failure could be achieved not only by imaging techniques such as echocardiography or cardioangiography, but also by standard ECG with right atrial hypertrophy and an increased mean precordial QRS dispersion of 47.1+/-18.9 ms in cases of right heart failure and biatrial hypertrophy and a reduced precordial QRS dispersion of 33.0+/-23.1 ms in cases of biventricular heart failure.

CONCLUSIONS

Heart failure in ARVD consists of isolated right ventricular and biventricular dilatation and pump failure in a time course of 4-8 years after developing complete right bundle branch block as a strong non-invasive predictor from standard 12-lead ECG.

Risk stratification of sudden cardiac death and malignant ventricular arrhythmias in right ventricular dysplasia-cardiomyopathy

Arrhythmogenic right ventricular dysplasia-cardiomyopathy is in most cases a benign cause of ventricular arrhythmias in young patients. The major reason of mortality is sudden arrhythmic death with an annual rate of 2-3% as the first manifestation of the disease in most cases. Little is known about risk factors of sudden arrhythmic death so far. The purpose of the retrospective study was to classify risk factors from invasive and non-invasive examinations.

METHODS

In a cohort of 121 consecutive patients sampled from 1986 to 1998 the value of right ventricular dilatation, left ventricular involvement analysed by angiocardiography or echocardiography and standard ECG parameters such as precordial T wave inversions, right precordial ST elevation, precordial QRS dispersion, left precordial JT interval prolongation and complete right bundle branch block were determined. The whole cohort of patients were divided into two groups with high arrhythmic risk (aborted or non-aborted sudden death, recurrent ventricular tachycardia despite medical treatment, recurrent syncopes) and low risk (frequent ventricular premature beats, non sustained ventricular tachycardia, uneventful course under medical therapy).

RESULTS

From angiocardiography or echocardiography in a quantitative approach right ventricular dilatation (p<0.0001) and additional left ventricular abnormalities (p<0.0001) could be identified as major risk factors. From an ECG point of view increased precordial QRS dispersion > or =50 ms (p<0.01) with complete right bundle branch block and right ventricular dilatation in most cases and precordial T wave inversions beyond V3 (p<0.0001) and the phenomenon of left precordial JT interval prolongation (JT dispersion > or =30 ms) in cases of additional left ventricular abnormalities represented non-invasive predictors of recurrent arrhythmic events. Right precordial ST segment elevation could be excluded as risk factor of sudden arrhythmic death.

CONCLUSIONS

Right ventricular dilatation with ECG depolarisation abnormalities and additional left ventricular involvement with striking ECG repolarisation abnormalities could be identified as strong risk factors of recurrent arrhythmic events in ARVD with unfavorable prognosis.

Pax1 and Pax9 synergistically regulate vertebral column development

The paralogous genes Pax1 and Pax9 constitute one group within the vertebrate Pax gene family. They encode closely related transcription factors and are expressed in similar patterns during mouse embryogenesis, suggesting that Pax1 and Pax9 act in similar developmental pathways. We have recently shown that mice homozygous for a defined Pax1 null allele exhibit morphological abnormalities of the axial skeleton, which is not affected in homozygous Pax9 mutants. To investigate a potential interaction of the two genes, we analysed Pax1/Pax9 double mutant mice. These mutants completely lack the medial derivatives of the sclerotomes, the vertebral bodies, intervertebral discs and the proximal parts of the ribs. This phenotype is much more severe than that of Pax1 single homozygous mutants. In contrast, the neural arches, which are derived from the lateral regions of the sclerotomes, are formed. The analysis of Pax9 expression in compound mutants indicates that both spatial expansion and upregulation of Pax9 expression account for its compensatory function during sclerotome development in the absence of Pax1. In Pax1/Pax9 double homozygous mutants, formation and anteroposterior polarity of sclerotomes, as well as induction of a chondrocyte-specific cell lineage, appear normal. However, instead of a segmental arrangement of vertebrae and intervertebral disc anlagen, a loose mesenchyme surrounding the notochord is formed. The gradual loss of Sox9 and Collagen II expression in this mesenchyme indicates that the sclerotomes are prevented from undergoing chondrogenesis. The first detectable defect is a low rate of cell proliferation in the ventromedial regions of the sclerotomes after sclerotome formation but before mesenchymal condensation normally occurs. At later stages, an increased number of cells undergoing apoptosis further reduces the area normally forming vertebrae and intervertebral discs. Our results reveal functional redundancy between Pax1 and Pax9 during vertebral column development and identify an early role of Pax1 and Pax9 in the control of cell proliferation during early sclerotome development. In addition, our data indicate that the development of medial and lateral elements of vertebrae is regulated by distinct genetic pathways.

Eya1-deficient mice lack ears and kidneys and show abnormal apoptosis of organ primordia

Haploinsufficiency for human EYA1, a homologue of the Drosophila melanogaster gene eyes absent (eya), results in the dominantly inherited disorders branchio-oto-renal (BOR) syndrome and branchio-oto (BO) syndrome, which are characterized by craniofacial abnormalities and hearing loss with (BOR) or without (BO) kidney defects. To understand the developmental pathogenesis of organs affected in these syndromes, we inactivated the gene Eya1 in mice. Eya1 heterozygotes show renal abnormalities and a conductive hearing loss similar to BOR syndrome, whereas Eya1 homozygotes lack ears and kidneys due to defective inductive tissue interactions and apoptotic regression of the organ primordia. Inner ear development in Eya1 homozygotes arrests at the otic vesicle stage and all components of the inner ear and specific cranial sensory ganglia fail to form. In the kidney, Eya1 homozygosity results in an absence of ureteric bud outgrowth and a subsequent failure of metanephric induction. Gdnf expression, which is required to direct ureteric bud outgrowth via activation of the c-ret Rtk (refs 5, 6, 7, 8), is not detected in Eya1-/- metanephric mesenchyme. In Eya1-/- ear and kidney development, Six but not Pax expression is Eya1 dependent, similar to a genetic pathway elucidated in the Drosophila eye imaginal disc. Our results indicate that Eya1 controls critical early inductive signalling events involved in ear and kidney formation and integrate Eya1 into the genetic regulatory cascade controlling kidney formation upstream of Gdnf. In addition, our results suggest that an evolutionarily conserved Pax-Eya-Six regulatory hierarchy is used in mammalian ear and kidney development.

Rapid FMR1-protein analysis of fetal blood: an enhancement of prenatal diagnostics

Fragile-X syndrome, a frequent cause of inherited mental retardation, is characterised in almost all cases by a CGG-repeat expansion that is located within the FMR-1 gene and that prevents the expression of fragile-X mental retardation protein (FMRP). We describe a test that simultaneously allows the rapid detection of FMRP in fetal lymphocytes and distinguishes these from fetal erythrocytes. Routine molecular genetic methods fail in the rare cases where protein expression is blocked, although there is no repeat expansion. Furthermore, they are unsuitable in cases of advanced pregnancy. Our test proves extremely valuable under both these circumstances.

Sigma factor displacement from RNA polymerase during Bacillus subtilis sporulation

As Bacillus subtilis proceeds through sporulation, the principal vegetative cell sigma subunit (sigma(A)) persists in the cell but is replaced in the extractable RNA polymerase (RNAP) by sporulation-specific sigma factors. To explore how this holoenzyme changeover might occur, velocity centrifugation techniques were used in conjunction with Western blot analyses to monitor the associations of RNAP with sigma(A) and two mother cell sigma factors, sigma(E) and sigma(K), which successively replace sigma(A) on RNAP. Although the relative abundance of sigma(A) with respect to RNAP remained virtually unchanged during sporulation, the percentage of the detectable sigma(A) which cosedimented with RNAP fell from approximately 50% at the onset of sporulation (T(0)) to 2 to 8% by 3 h into the process (T(3)). In a strain that failed to synthesize sigma(E), the first of the mother cell-specific sigma factors, approximately 40% of the sigma(A) remained associated with RNAP at T(3). The level of sigma(A)-RNAP cosedimentation dropped to less than 10% in a strain which synthesized a sigma(E) variant (sigma(ECR119)) that could bind to RNAP but was unable to direct sigma(E)-dependent transcription. The E-sigma(E)-to-E-sigma(K) changeover was characterized by both the displacement of sigma(E) from RNAP and the disappearance of sigma(E) from the cell. Analyses of extracts from wild-type and mutant B. subtilis showed that the sigma(K) protein is required for the displacement of sigma(E) from RNAP and also confirmed that sigma(K) is needed for the loss of the sigma(E) protein. The results indicate that the successive appearance of mother cell sigma factors, but not necessarily their activities, is an important element in the displacement of preexisting sigma factors from RNAP. It suggests that competition for RNAP by consecutive sporulation sigma factors may be an important feature of the holoenzyme changeovers that occur during sporulation.

The gene for cherubism maps to chromosome 4p16

Cherubism is an autosomal dominant disorder that may be related to tooth development and eruption. It is a disorder of age-related bone remodeling, mostly limited to the maxilla and the mandible, with loss of bone in the jaws and its replacement with large amounts of fibrous tissue. We have used a genomewide search with a three-generation family and have established linkage to chromosome 4p16. Three other families affected with cherubism were also genotyped and were mapped to the same locus. The combined LOD score is 4.21 at a recombination fraction of 0, and the locus spans an interval of approximately 22 cM.

From rats to man: a perspective on dietary L-arginine supplementation in human renal disease

Experimental studies have shown both therapeutic and detrimental consequences of modifying dietary L-arginine intake in renal diseases which likely reflect the complexity of L-arginine metabolism. L-Arginine intake is semi-essential and provides substrate for a number of L-arginine metabolites involved in renal pathology. Dietary L-arginine restriction has been identified as a key mediator of the beneficial effects of low protein diets on human renal fibrosis. Supplementing dietary L-arginine in renal diseases with increased iNOS expression appears to be detrimental and thus, may be harmful in immune-mediated human kidney disorders. Increasing L-arginine intake is beneficial in experimental models of hypertensive renal disease. Based upon available data, we believe additional questions must be answered experimentally, not only to prevent an adverse outcome in humans, but to enhance our chances of human trials which will result in substantially better amelioration of disease than currently available.

L-Arginine supplementation increases mesangial cell injury and subsequent tissue fibrosis in experimental glomerulonephritis

BACKGROUND

Mesangial cell lysis in the antithymocyte serum (ATS)-induced model of glomerulonephritis is dependent on the generation of cytotoxic nitric oxide (NO) through transient induction of NO synthase (iNOS). We hypothesized that increased availability of L-arginine (L-Arg) during mesangial cell lysis might provide iNOS with increased substrate leading to increased lysis, and that this increased lysis would be reflected in more severe fibrotic disease at day 6.

METHODS

To ensure whole body equilibration with high L-Arg at the time of injury, rats were pretreated with 1% L-Arg in drinking water for one week prior to the administration of ATS. Animals were sacrificed six hours after ATS injection when previous experiments had indicated iNOS induction had occurred and at six days. At six hours, plasma was obtained for L-Arg levels and nitrite/nitrate (NOx) content. Renal tissues were taken for histological evaluation of glomerular cell counts, macrophage infiltration (ED-1), and iNOS expression. Glomeruli were isolated for detection of iNOS mRNA and placed in culture to study the dependence of NO production on L-Arg concentration. In rats sacrificed at six days, L-Arg supplementation was stopped 16 hours after ATS injection. Fibrotic disease was evaluated by urinary protein excretion, histological assessment of glomerular cell number, matrix accumulation, and production of transforming growth factor-beta1 and matrix components fibronectin and plasminogen activator inhibitor type-1 (PAI-1) by isolated glomeruli in culture.

RESULTS

At six hours, the glomerular cell number was significantly reduced by ATS injection (P < 0.01) and further significantly (P < 0. 05) reduced by L-Arg feeding [normal control (NC) = 64.2 +/- 1, ATS = 53.4 +/- 0.7, ATS + L-Arg = 50.8 +/- 0.7]. Disease increased macrophage infiltration and iNOS protein and iNOS mRNA levels markedly (P < 0.01), whereas L-Arg feeding did not further increase these variables. Plasma L-Arg levels (nmol/ml) were reduced by disease (NC = 121 +/- 9, ATS = 84 +/- 13, P < 0.01) and elevated by L-Arg feeding (ATS + L-Arg = 166 +/- 12, P < 0.01). Plasma NOx was significantly increased by ATS and further increased by ATS + L-Arg (P < 0.05). Production of NOx by cultured glomeruli showed striking L-Arg concentration dependence in six hours but not in normal glomeruli. In the group sacrificed at day 6, day 2 proteinuria was higher in the ATS + L-Arg group compared with the ATS alone group (P < 0.05). Measures of fibrotic disease at day 6 all showed large increases over control with ATS alone (P < 0.01), and further small, but significant increases when L-Arg was combined with ATS (P < 0.05).

CONCLUSIONS

The results indicate that if given during disease induction, L-Arg supplementation can enhance iNOS-dependent tissue injury by providing increased substrate. Although the increase in injury with L-Arg supplementation was small, it led to increased fibrosis at day 6. These data predict that in diseases with repeated iNOS-dependent tissue injury, L-Arg supplementation may produce cumulative increases in tissue fibrosis.

Developmental expression of Pax1/9 genes in urochordate and hemichordate gills: insight into function and evolution of the pharyngeal epithelium

The epithelium of the pharynx contributes to the formation of gills in hemichordates, urochordates, cephalochordates and primitive vertebrates, and is therefore a key structure for understanding developmental mechanisms underlying the establishment of chordate body plans. Pax1- and Pax9-related genes encode transcription factors which are expressed in the pharyngeal region of cephalochordates as well as in the vertebrate pharyngeal pouch epithelium that forms the thymus and parathyroid glands. To explore the molecular basis underlying the occurrence and modifications of the pharyngeal epithelium during evolution, we isolated cDNA clones for Pax1- and Pax9-related genes of urochordates (HrPax1/9 of Halocynthia roretzi and CiPax1/9 of Ciona intestinalis) and a hemichordate (PfPax1/9 of Ptychodera flava) from gill cDNA libraries. Each gene is present as a single copy per haploid genome. All of the cDNAs encode typical paired domains and octapeptides but not a homeodomain, as is also true of other Pax1- and Pax9-related genes. Molecular phylogenetic analysis based on comparison of the paired domain amino-acid sequences suggests that HrPax1/9, CiPax1/9 and PfPax1/9 belong to the Pax1/9 subfamily, and that they are descendants of a single precursor of Pax1/Pax9. Screening of HrPax1/9 cDNA clones yielded six different types of transcripts which were generated by alternative splicing. Northern blot, RT-PCR/Southern and in situ hybridization analyses revealed that HrPax1/9, CiPax1/9 and PfPax1/9 are not expressed during early embryogenesis but are expressed in the epithelia of differentiating gills, suggesting that these genes encode gill-specific transcription factors. The Pax1/9 genes therefore might provide the first developmental genetic corroboration of hypotheses of organ-level homology that unifies hemichordates, urochordates and cephalochordates.

Immunogenicity of a combined hepatitis B and Haemophilus influenzae type b conjugate vaccine in Alaska Native infants

Hepatitis B and Haemophilus influenzae b (Hib), prevalent diseases in Alaska Native infants, have been reduced 95% following universal vaccination. Therefore, we were interested in studying a new combined Hib and hepatitis B vaccine in this population.

METHOD

Healthy Alaska Native infants free from Hib and hepatitis B exposure were randomized into four groups, three with different lots of bivalent Hib and hepatitis B vaccine, and one with Hib and hepatitis B monovalent controls. The Hib component had 7.5 micrograms of polyribosylribitol phosphate polysaccharide (PRP) bound to 125 micrograms of Neisseria meningitidis outer membrane protein complex (OMP); the hepatitis B component was 5 micrograms of recombinant hepatitis B surface antigen. The vaccines were given at 2 months, 4 months, and 12-15 months of age.

RESULTS

There were no differences in the responses to the bivalent compared to the monovalent controls except for a lower Hib anti-PRP level at 12-15 months in the bivalent recipients; this did not persist after the booster.

CONCLUSION

A combined Hib and hepatitis B vaccine appears immunogenic. The recommended schedule for the Hib component (PRP-OMP) of 2 months, 4 months, and 12-15 months appears to promote an optimal response to the hepatitis B component as well.

Two independent mutations in a family with neurofibromatosis type 1 (NF1)

We report on two independent alterations of the NF1 gene in a three-generation kindred with neurofibromatosis type 1 (NF1). Using temperature gradient gel electrophoresis (TGGE) in a mutation analysis of exon 31 of the NF1 gene we detected the previously reported nonsense mutation R1947X. This C-to-T transition at codon 1947 in exon 31 is considered to represent a mutation "hot spot" of the NF1 gene due to 5mCpG deamination. All living family members together with their genomic DNA were included in this investigation. However, the mutation R1947X was absent from two undoubtedly affected siblings of the propositus. Another NF1 mutation (889-2A-->G) was identified in the two sibs by the protein truncation test (PTT). The novel splice site mutation 889-2A-->G results in a skip of NF1 exon 7 during splicing and protein truncation due to frameshift. The two NF1 alterations are linked to different paternal haplotypes. In our study of a three-generation kindred, R1947X represents a de novo mutation whereas 889-2A-->G is an inherited splice mutation. Implications for phenotype variation are discussed.

De novo deletion (14)(q11.2q13) including PAX9: clinical and molecular findings

A 3 year old boy with a de novo deletion (14)(q11.2q13) of paternal origin encompassing the region from D14S264 to D14S70 is described. The patient presented with severe psychomotor retardation, bilateral cleft lip/palate, bilateral colobomas of the optic nerves and retinas, agenesis of the corpus callosum, pes calcaneovarus, reduced oesophageal peristalsis, and swallowing difficulties. This is the first reported case of PAX9 hemizygosity in humans. Haploinsufficiency of the PAX9 gene might be expected to cause some of the developmental defects and the dysphagia. Another haploinsufficiency candidate gene, the bZIP transcription factor gene NRL, which is specifically expressed in neuronal cells and the eye during embryogenesis, was excluded from the deletion interval.

Teeth. Where and how to make them

Organs have to develop at precisely determined sites to ensure functionality of the whole organism. Organogenesis is typically regulated by a series of interactions between morphologically distinct tissues. The developing tooth of the mouse is an excellent model to study these processes and we are beginning to understand the networks regulating reciprocal tissue interactions at the molecular level. Synergistic and antagonistic effects of signaling molecules including FGFs and BMPs are recursively used to induce localized responses in the adjacent tissue layer (mesenchyme or epithelium). However, at different phases of odontogenesis these secreted growth factors have distinct effects and at the same time they are regulated by different upstream factors. The mesenchymal transcription factors Msx1 and Pax9 are initially regulated by epithelial FGFs and BMPs, but subsequently they function upstream of these signaling molecules. This cascade provides a molecular model by which reciprocal tissue interactions are controlled.

Altered regulation of platelet-derived growth factor receptor-alpha gene-transcription in vitro by spina bifida-associated mutant Pax1 proteins

Mouse models show that congenital neural tube defects (NTDs) can occur as a result of mutations in the platelet-derived growth factor receptor-alpha gene (PDGFRalpha). Mice heterozygous for the PDGFRalpha-mutation Patch, and at the same time homozygous for the undulated mutation in the Pax1 gene, exhibit a high incidence of lumbar spina bifida occulta, suggesting a functional relation between PDGFRalpha and Pax1. Using the human PDGFRalpha promoter linked to a luciferase reporter, we show in the present paper that Pax1 acts as a transcriptional activator of the PDGFRalpha gene in differentiated Tera-2 human embryonal carcinoma cells. Two mutant Pax1 proteins carrying either the undulated-mutation or the Gln --> His mutation previously identified by us in the PAX1 gene of a patient with spina bifida, were not or less effective, respectively. Surprisingly, Pax1 mutant proteins appear to have opposing transcriptional activities in undifferentiated Tera-2 cells as well as in the U-2 OS osteosarcoma cell line. In these cells, the mutant Pax1 proteins enhance PDGFRalpha-promoter activity whereas the wild-type protein does not. The apparent up-regulation of PDGFRalpha expression in these cells clearly demonstrates a gain-of-function phenomenon associated with mutations in Pax genes. The altered transcriptional activation properties correlate with altered protein-DNA interaction in band-shift assays. Our data provide additional evidence that mutations in Pax1 can act as a risk factor for NTDs and suggest that the PDGFRalpha gene is a direct target of Pax1. In addition, the results support the hypothesis that deregulated PDGFRalpha expression may be causally related to NTDs.

Targeting TGF-beta overexpression in renal disease: maximizing the antifibrotic action of angiotensin II blockade

BACKGROUND

Overproduction of transforming growth factor-beta (TGF-beta) is a key mediator of extracellular matrix accumulation in fibrotic diseases. We hypothesized that the degree of reduction of pathological TGF-beta expression can be used as a novel index of the antifibrotic potential of angiotensin II (Ang II) blockade in renal disease.

METHODS

One day after induction of Thy 1.1 glomerulonephritis, rats were treated with increasing doses of the Ang I converting enzyme (ACE) inhibitor enalapril and/or the Ang II receptor blocker losartan in the drinking water. Six days after disease induction the therapeutic effect on glomerular TGF-beta overexpression was evaluated.

RESULTS

Both enalapril and losartan reduced TGF-beta overproduction in a dose-dependent manner, showing a moderate reduction at doses known to control blood pressure in renal forms of hypertension. A maximal reduction in TGF-beta expression of approximately 45% was seen for both drugs starting at 100 mg/liter enalapril and 500 mg/liter losartan, with no further reduction at doses of enalapril up to 1000 mg/liter or losartan up to 2500 mg/liter. Co-treatment with both drugs was not superior to single therapy. Consistent with our hypothesis that reduction in TGF-beta expression is a valid target, other disease measures, including glomerular matrix accumulation, glomerular production and mRNA expression of the matrix protein fibronectin and the protease inhibitor plasminogen-activator-inhibitor type 1 (PAI-1) closely followed TGF-beta expression.

CONCLUSIONS

The data suggest that these therapies act through very similar pathways and that, in order to more effectively treat renal fibrosis, these drugs must be combined with other drugs that act by different mechanisms.