[Acute respiratory stridor in infancy]

Infantile subglottic hemangioma is a pediatric tumor of endothelial cells characterized by an initial phase of rapid proliferation (around 6 months), followed by slow involution, often leading to complete regression following the first year of life. It is most frequently found in females and it usually it occurs also in the skin. From its position it can cause a progressive airway obstruction, so early diagnosis and treatment are very important. Many treatments have been described in the literature, including systemic steroids, intralesional steroid injection, carbon dioxide laser therapy, submucous resection, interferon alfa-2 and also tracheostomy as last approach. This case report discusses a 6-month old infant, that arrived to our attention for an acute two-way stridor. Laringoscopy under general anesthesia showed a subocclusive subglottic haemangioma that closed 70% of the laryngeal airway. In agreement with our ENT specialist it was decided to begin systemic steroid therapy, first by i.v. ingection during intensive therapy with rinotracheal intubation and mechanic ventilation; after the canula removal and the hemangioma reduction, the patient took oral steroids with a gradual reduction of the dose. This case evidences the importance of laryngoscopy in the diagnosis of subglottic haemangioma; it also proves the importance of multi-disciplinary collaboration with ENT specialist and dermatologist for the diagnosis and treatment of this kind of patient. It also shows that systemic steroids are an effective alternative in the management of obstructive pediatric subglottic hemangiomas.

A novel frame-shift deletion causing analbuminaemia in an Italian paediatric patient

BACKGROUND

Analbuminaemia (OMIM #103600) is a rare autosomal recessive disorder manifested by the absence or severe reduction of circulating serum albumin in homozygous or compound heterozygous subjects. The trait is caused by a variety of mutations within the albumin gene.

DESIGN

We report here the clinical and molecular characterization of a new case of congenital analbuminaemia in a 4-year-old Italian girl diagnosed on the basis of the low level of circulating albumin (= 10.0 g L(-1)). The albumin gene was screened by single-strand conformation polymorphism and heteroduplex analysis and the mutated region submitted to DNA sequencing.

RESULTS

The proband was found to be homozygous, and both parents heterozygous, for a novel deletion in exon 8 (c.920delT). The subsequent frame-shift should have given rise to a putative polypeptide chain of 304 amino acid residues, which we could not identify in the proband's serum.

CONCLUSIONS

A novel analbuminaemia causing mutation was identified and characterized at the clinical level in a child. The molecular diagnosis of the trait is based on the rapid localization of the mutation within the albumin gene by single-strand conformation polymorphism and heteroduplex analysis, followed by DNA sequencing of the mutated region.

Major differences in bleeding symptoms between factor VII deficiency and hemophilia B

SUMMARY BACKGROUND

The autosomally-inherited factor VII (FVII) deficiency and X-linked hemophilia B offer an attractive model to investigate whether reduced levels of FVII and FIX, acting in the initiation and amplification of coagulation respectively, influence hemostasis to a different extent in relation to age and bleeding site.

METHODS

Hemophilia B patients (n = 296) and FVII-deficient males (n = 109) were compared for FVII/FIX clotting activity, F7/F9 genotypes and clinical phenotypes in a retrospective, multi-centre, cohort study.

RESULTS

Major clinical differences between diseases were observed. Bleeding occurred earlier in hemophilia B (median age 2.0 years, IR 0.9-5.0) than in FVII deficiency (5.2 years, IR 1.9-15.5) and the bleeding-free survival in FVII deficiency was similar to that observed in 'mild' hemophilia B (P = 0.96). The most frequent disease-presenting symptoms in hemophilia B (hematomas and oral bleeding) differed from those in FVII deficiency (epistaxis and central nervous system bleeding). Differences were confirmed by analysis of FVII-deficient women.

CONCLUSIONS

Our data support the notion that low FVII levels sustain hemostasis better than similarly reduced FIX levels. On the other hand, minute amounts of FVII, differently to FIX, are needed to prevent fatal bleeding, as indicated by the rarity of null mutations and the associated life-threatening symptoms in FVII deficiency, which contributes towards shaping clinical differences between diseases in the lowest factor level range. Differences between diseases are only partially explained by mutational patterns and could pertain to the specific roles of FVII and FIX in coagulation phases and to vascular bed-specific components.

Gastrointestinal lesions in parvovirus B19 infection

A 13-year-old girl with persistent fever, pharyngitis, acute anaemia, peripheral blood and bone marrow positive for parvovirus B19 DNA.Microscopic findings of gastrointestinal biopsy showed diffuse vacuolar alteration of the cytoplasma of duodenal enterocytes and virological analysis demonstrated the presence of parvovirus in lymphocytes of the duodenal wall's epithelial layer.In unexplained gastrointestinal pathologies, the role of parvovirus B19 infection should be investigated.

Reduced factor VII and factor VIII levels and prolonged thrombin-generation times during a healthy diet in middle-aged women with mild to moderate cardiovascular disease risk

BACKGROUND

No experimental study has investigated the effect of whole-diet therapies on a wide range of hemostatic parameters, and their relationship with metabolic and inflammatory markers. Such information was sought in middle-aged women with moderate cardiovascular disease (CVD) risk subjected to an integrated healthy diet.

METHODS

Forty-nine premenopausal women were screened for C-reactive protein levels > or =1 mg L(-1) and at least one additional CVD risk factor. Sixteen women (age: 43-54 years) were selected and received a 12-week diet (four phases) integrating National Cholesterol Education Program-Adult Treatment Panel-III recommendations with components of a Mediterranean-style diet.

RESULTS

We observed a reduction in body mass index (BMI) (P = 0.001), waist circumference (P = 0.005), total (P = 0.011) and low-density lipoprotein (LDL) cholesterol levels (P = 0.035). Antigen levels of coagulation factor (F)VII (P = 0.003) and FVIII (P = 0.005) were clearly reduced by dietary intervention, which also appeared to decrease circulating tissue factor but not fibrinogen and von Willebrand factor (VWF) antigen levels. Levels of FVIII and tumor necrosis factor-alpha, among the inflammation markers, showed the highest correlation, particularly before the intervention (r = 0.55, P = 0.032). Only this cytokine influenced FVIII variation over time, thus highlighting new relations between coagulation and cellular components of inflammation. The functional effect of diet on coagulation was indicated by markedly prolonged thrombin generation initiation and propagation times (lag time, P = 0.002; time to peak, P = 0.005).

CONCLUSIONS

The changes observed in coagulation initiation and amplification phases, body composition and lipid profile could translate into a remarkable decrease in the risk for cardiovascular disease. Our observations suggest novel relationships between coagulation and inflammatory components.

Vitamin K-induced modification of coagulation phenotype in VKORC1 homozygous deficiency

BACKGROUND

Combined vitamin K-dependent clotting factor (VKCF) deficiency type 2 (VKCFD2) is a rare bleeding disorder caused by mutated vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) gene.

METHODS AND RESULTS

An Italian patient with moderate to severe bleeding tendency was genotyped, and found to be homozygous for the unique VKORC1 mutation (Arg98Trp) so far detected in VKCFD2. The activity levels of VKCFs were differentially reduced, and inversely related to the previously estimated affinity of procoagulant factor propeptides for the gamma-carboxylase. The normal (factor IX) or reduced antigen levels (other VKCFs) produced a gradient in specific activities. Vitamin K supplementations resulted in reproducible, fast and sustained normalization of PT and APTT. At 24 h the activity/antigen ratios of VKCFs were close to normal, and activity levels were completely (factor VII and IX), virtually (prothrombin, factor X and protein C) or partially (protein S) restored. Thrombin generation assays showed a markedly shortened lag time. The time to peak observed at low tissue factor concentration, potentially mimicking the physiological trigger and able to highlight the effect of reduced protein S levels, was shorter than that in pooled normal plasma. At 72 h the thrombin generation times were normal, and the decrease in activity of procoagulant VKCFs was inversely related to their half-life in plasma. The improved coagulation phenotype permitted the uneventful clinical course after invasive diagnostic procedures.

CONCLUSIONS

Modification of coagulation phenotypes in VKCFD2 after vitamin K supplementation was clinically beneficial, and provided valuable patterns of factor specific biosynthesis, half-life and decay.

Airway inflammation and lung function decline in childhood post-infectious bronchiolitis obliterans

Post-infectious bronchiolitis obliterans (PBO) is a rare form of chronic obstructive lung disease in children with few data on the pulmonary function outcome and underlying inflammatory process. The aim of this study was to determine the change in lung function over time and to investigate by bronchoalveolar lavage (BAL) the inflammatory characteristics of pulmonary involvement. Eleven Caucasian children with PBO were evaluated to estimate the average rate of change in lung function indices using a mixed model. The differential cytology and lymphocyte subsets of BAL fluid were analyzed. The median follow-up was 10.2 (IQR 3.2-12) years. The estimated forced expiratory volume in 1 sec (FEV1) had a baseline intercept of 57% predicted (62% predicted after bronchodilator) at 10 years of age which fell at a rate of 1.01% per year whereas the estimated forced expiratory flow 25-75 (FEF25-75) had a baseline intercept of 36% predicted (42% predicted after bronchodilator) at 10 years of age which fell at a rate of 1.04% per year. The estimated FEV1/FVC ratio had a baseline intercept of 70% (74% after bronchodilator) at 10 years of age which declined with an average slope of 1.02% per year (-1.10% per year after bronchodilator). Although the baseline and post-bronchodilator level of estimated FVC was abnormal (68% and 69% predicted, respectively) it did not change significantly with time. The median disease duration at BAL evaluation was 3.7 (IQR 0.7-8) years. The percentage differential cell counts were characterized by a significant increase in neutrophils (median 50%, IQR 1-66%), and a slight increase of lymphocytes (median 14%, IQR 7.5-15%). In conclusion, pulmonary function in childhood PBO is characterized by significant airway obstruction which deteriorates over time. The presence of an ongoing inflammatory process could explain the decline in lung function over time.

[Geminivirus replication: rolling circle mechanism in plants]

Geminiviruses are single-stranded DNA viruses that infect most plants worldwide. They replicate through a rolling circle mechanism which allows the production of a large amount of single-stranded viral DNA. This mechanism has been studied in detail for prokaryotic replicons but has also been described for eukaryotic replicons. The viral Rep protein is the key element in this process and combines three functions essential for replication: recognition of the viral origin of replication, cleavage of the origin and production of the primer necessary to replicate the viral DNA, and a replicative helicase activity. Furthermore by associating with several host proteins Rep interferes with the cell cycle control to produce a favourable environment for the replication of the virus. Recent advances have been reported concerning the demonstration of the helicase activity of Rep protein and the tertiary structure of its N-terminal domain; our review will focus on these two aspects in relation with the rolling circle replication mechanism.

Cryptic deletions are a common finding in "balanced" reciprocal and complex chromosome rearrangements: a study of 59 patients

Using array comparative genome hybridisation (CGH) 41 de novo reciprocal translocations and 18 de novo complex chromosome rearrangements (CCRs) were screened. All cases had been interpreted as "balanced" by conventional cytogenetics. In all, 27 cases of reciprocal translocations were detected in patients with an abnormal phenotype, and after array CGH analysis, 11 were found to be unbalanced. Thus 40% (11 of 27) of patients with a "chromosomal phenotype" and an apparently balanced translocation were in fact unbalanced, and 18% (5 of 27) of the reciprocal translocations were instead complex rearrangements with >3 breakpoints. Fourteen fetuses with de novo, apparently balanced translocations, all but two with normal ultrasound findings, were also analysed and all were found to be normal using array CGH. Thirteen CCRs were detected in patients with abnormal phenotypes, two in women who had experienced repeated spontaneous abortions and three in fetuses. Sixteen patients were found to have unbalanced mutations, with up to 4 deletions. These results suggest that genome-wide array CGH may be advisable in all carriers of "balanced" CCRs. The parental origin of the deletions was investigated in 5 reciprocal translocations and 11 CCRs; all were found to be paternal. Using customized platforms in seven cases of CCRs, the deletion breakpoints were narrowed down to regions of a few hundred base pairs in length. No susceptibility motifs were associated with the imbalances. These results show that the phenotypic abnormalities of apparently balanced de novo CCRs are mainly due to cryptic deletions and that spermatogenesis is more prone to generate multiple chaotic chromosome imbalances and reciprocal translocations than oogenesis.

A case of furuncular myiasis associated with systemic inflammation

Cutaneous myiasis is a common travel-associated dermatosis caused by fly larvae. We report an unusual case of furuncular myiasis caused by Dermatobia hominis that was associated with signs of systemic inflammation. In this case study, morphological and novel molecular approaches were used to identify and characterize the larvae responsible for human infestation.

Narcolepsy-cataplexy associated with precocious puberty

In children, narcolepsy may be the symptom of a brain lesion or genetic disease. The authors report two cases with severe narcolepsy-cataplexy emerging in childhood in close temporal association with obesity and precocious puberty.

Intracellular readthrough of nonsense mutations by aminoglycosides in coagulation factor VII

BACKGROUND

Nonsense mutations in coagulation factor (F) VII potentially cause a lethal hemorrhagic diathesis. Readthrough of nonsense mutations by aminoglycosides has been studied in a few human disease models with variable results.

OBJECTIVES

We investigated the K316X and W364X FVII mutations, associated with intracranial hemorrhage, and their correction by aminoglycosides. The rare nonsense mutations in FVII represent favorite models to test this strategy, because even tiny increases in the amount of functional full-length protein in patients could ameliorate hemorrhagic phenotypes.

RESULTS

A FVII-green fluorescent protein (GFP) chimaera provided us with a fluorescent model of FVII expression in living cells. Appreciable fluorescence in cells transfected with nonsense FVII-GFP mutants was detected upon geneticin treatment, thus demonstrating suppression of premature translation termination. To investigate the rescue of FVII function, nonsense variants of the native FVII without GFP (p316X-FVII and p364X-FVII) were transfected and found to secrete low amounts of FVII (approximately 1% of Wt-FVII activity), thus suggesting a spontaneous stop codon readthrough. Geneticin treatment of cells resulted in a significant and dose-dependent increase of secreted FVII molecules (p316X-FVII, 24 +/- 12 ng mL(-1), 3.6 +/- 0.8% of Wt-FVII activity; p364X-FVII, 26 +/- 10 ng mL(-1), 3.7+/-0.6%) characterized by reduced specific activity, thus indicating the synthesis of dysfunctional proteins. Similar results were observed with gentamicin, a commonly used aminoglycoside of potential interest for patient treatment.

CONCLUSIONS

Our approach, extendable to other coagulation factors, represents an effective tool for a systematic study of the effects of aminoglycosides and neighboring sequences on nonsense codon readthrough. These results provide the rationale for a mutation-specific therapeutic approach in FVII deficiency.

Antigenic and genetic characterization of rabies viruses isolated from domestic and wild animals of Brazil identifies the hoary fox as a rabies reservoir

Fifty Brazilian rabies viruses, collected from many different animal species and several regions of the country, were characterized by partial sequencing of the central, variable region of the P gene, a locus useful for sensitive molecular epidemiological studies. Phylogenetic analysis of the sequences, which included comparison with other rabies strains recovered from throughout the Americas, identified three main groups of Brazilian viruses, arbitrarily designated BRL-1 to BRL-3. BRL-1 was found in terrestrial carnivores and clusters with other American strains of the cosmopolitan lineage. BRL-2 comprised two distinct isolates, recovered from two species of non-haematophagous bats, that had evolutionary links to insectivorous-bat-derived strains of North America. BRL-3 consisted of isolates from vampire bats and from livestock species probably infected via contact with vampire bats. The terrestrial group was further subdivided into three subtypes: BRL-1a was associated exclusively with dogs and cats, while BRL-1b and BRL-1c were found exclusively in hoary foxes. These observations strongly support the role of the Brazilian hoary fox as a rabies reservoir. Screening of representative Brazilian rabies viruses against a collection of anti-rabies monoclonal antibodies (mAbs) identified a small panel of mAbs that could be used to discriminate between all Brazilian subgroups as defined by genetic classification in this study.

Molecular bases of type II protein S deficiency: the I203-D204 deletion in the EGF4 domain alters GLA domain function

OBJECTIVE

To characterize the first type II protein S (PS) deficiency affecting the epidermal growth factor (EGF)4 domain, a calcium-binding module with a poorly defined functional role.

PATIENTS

The proband suffered from recurrent deep vein thrombosis and showed reduced PS anticoagulant activity (31%), and total, free PS antigen and C4bBP levels in the normal range.

RESULTS

Reverse transcription-polymerase chain reaction analysis showed the presence of the IVSg-2A/T splicing mutation that, by activating a cryptic splice site, causes the deletion of codons Ile203 and Asp204. Free PS, immunopurified from proband's plasma, showed an altered electrophoretic pattern in native condition or in the presence of Ca2+. The recombinant PS (rPS) mutant showed reduced anticoagulant (<10%) and activated protein C-independent activities (24-38%) when compared with wild-type rPS (rPSwt). Binding of the rPS variant to phospholipid vesicles (Kd 235.7 +/- 30.8 nM, rPSwt; Kd 15.2 +/- 0.9 nM) as well as to Ca2+-dependent conformation-specific monoclonal antibodies for GLA domain was significantly reduced.

CONCLUSIONS

These data aid in the characterization of the functional role of the EGF4 domain in the anticoagulant activities of PS and in defining the thrombophilic nature of type II PS deficiency.

Expression of the normal factor V allele modulates the APC resistance phenotype in heterozygous carriers of the factor V Leiden mutation

BACKGROUND

Functional defects of the protein C pathway, detectable in plasma as activated protein C (APC) resistance, are a prevalent risk factor for venous thrombosis. The factor V (FV) Leiden mutation causes APC resistance by interfering with the APC-mediated inactivation of both FVa and FVIIIa. Co-inheritance of FV Leiden and quantitative FV deficiency on different alleles, a rare condition known as pseudo-homozygous APC resistance, is associated with pronounced APC resistance and 50% reduced FV levels, because of non-expression of the non-Leiden FV allele.

OBJECTIVES

The role of normal FV in modulating the APC resistance phenotype in carriers of FV Leiden was investigated in patients with pseudo-homozygous APC resistance and in model systems.

PATIENTS/METHODS

Four functional plasma assays probing both components of APC resistance (susceptibility of FVa to APC and cofactor activity of FV in FVIIIa inactivation) were employed to compare seven clinically and genetically characterized FV Leiden pseudo-homozygotes to 30 relatives with different FV genotypes (including 12 FV Leiden heterozygotes and seven carriers of FV deficiency) and to 32 unrelated FV Leiden homozygotes.

RESULTS AND CONCLUSIONS

All assays consistently indicated that FV Leiden pseudo-homozygotes are significantly more APC-resistant than heterozygotes and indistinguishable from homozygotes. Thrombin generation measurements in FV-deficient plasma reconstituted with purified normal FV and FV Leiden confirmed these observations and showed that the expression of the normal FV allele is an important modulator of APC resistance in FV Leiden heterozygotes. These findings provide an explanation for the higher thrombotic risk of FV Leiden pseudo-homozygotes when compared with heterozygotes.

The factor V Glu1608Lys mutation is recurrent in familial thrombophilia

BACKGROUND

Co-inheritance of heterozygous factor V deficiency with FV Leiden enhances the activated protein C resistance (APCR) associated with this mutation, resulting in pseudo-homozygous APCR. The role of FV deficiency in modulating thrombotic risk in this rare condition is poorly understood.

METHODS AND RESULTS

We have identified in thrombophilic patients with FV deficiency a novel FV gene mutation (c. 4996G>A), predicting the Glu1608Lys substitution in the A3 domain. The heterozygous mutation was detected in three unrelated patients, two carriers of the FV Leiden mutation, and one of the FVHR2 haplotype. The Glu1608Lys change was also present in two subjects with mild FV deficiency, and absent in 200 controls. The FV1608Lys carriers showed reduced mean FV activity (42% +/- 12%) and antigen (53% +/- 18%) levels and, in Western blot analysis, reduced amounts of intact platelet FV. The restriction fragment length polymorphism (RFLP) study identified two haplotypes underlying the mutation, which suggests that it is recurrent. In heterozygous subjects the amount of FV1608Lys mRNA in white blood cells was similar to that produced by the counterpart alleles (FVWt or FVHR2). Recombinant FV1608Lys (rFV1608Lys), detected by Western blot in the conditioned medium, was indistinguishable from rFVWt and FV antigen and activity were found to be respectively 44% +/- 20% and 13% +/- 4% of rFVWt.

CONCLUSIONS

Our data indicate that FVGlu1608Lys predicts a CRM (plasma)/CRMred (cell culture) FV deficiency, and may contribute to thrombophilia in carriers of FV Leiden and FVHR2 haplotype via a pseudo-homozygosity mechanism. Our findings help to define the molecular bases of FV deficiency and thrombophilia.