Targeted transgenesis at the HPRT locus: an efficient strategy to achieve tightly controlled in vivo conditional expression with the tet system.

The tet-inducible system has been widely used to achieve conditional gene expression in genetically modified mice. To alleviate the frequent difficulties associated with recovery of relevant transgenic founders, we tested whether a controlled strategy of transgenesis would support reliable cell-specific, doxycycline (Dox)-controlled transgene expression in vivo. Taking advantage of the potent hypoxanthine-aminopterin-thymidine selection strategy and an embryonic stem (ES) cell line supporting efficient germ-line transmission, we used hypoxanthine phosphoribosyltransferase (HPRT) targeting to insert a single copy tet-inducible construct designed to allow both glucocorticoid receptor (GR) and beta-galactosidase (beta-Gal) expression. Conditional, Dox-dependent GR and beta-Gal expression was evidenced in targeted ES cells. Breeding ES-derived single copy transgenic mice with mice bearing appropriate tet transactivators resulted in beta-Gal expression both qualitatively and quantitatively similar to that observed in mice with random integration of the same construct. Interestingly, GR expression in mice was dependent on transgene orientation in the HPRT locus while embryonic stem cell expression was not. Thus, a conditional construct inserted in single copy and in predetermined orientation at the HPRT locus demonstrated a Dox-dependent gene expression phenotype in adult mice suggesting that controlled insertion of tet-inducible constructs at the HPRT locus can provide an efficient alternative strategy to reproducibly generate animal models with tetracycline-induced transgene expression.

Effect of high versus low initial doses of L-thyroxine for congenital hypothyroidism on thyroid function and somatic growth.

BACKGROUND AND AIMS: The optimal dose of thyroxine (T4) in congenital hypothyroidism (CH) during infancy is controversial. Higher doses lead to improvement in cognitive scores, but have been linked to later behavioural difficulties. We have examined the effects of initial T4 dosage on somatic growth--a putative surrogate marker of overtreatment. METHODS: 314 CH children (214 girls, 100 boys) were analysed according to initial daily dose of T4: Group 1 (25 mug, n = 152), Group 2 (30-40 mug, n = 63) and Group 3 (50 mug, n = 99). Thyroid function and weight, length and occipito-frontal head circumference (OFC) standard deviation score (SDS) were compared at 3, 6, 12, 18, 24 and 36 months of age. Linear growth SDS was compared between the three groups using a regression adjustment model at 12 and 18 months of age using birth weight and 3-month data as baselines. Thyroid function was also compared at diagnosis (T 0), and 7-21 days after the start of treatment (T1). RESULTS: At T1 median thyroid stimulating hormone (TSH) for Groups 1, 2 and 3 was 58, 29 and 4.1 mU/l, respectively (p<0.001), Group 3 values remaining significantly lower at 3 and 6 months. Median free T4 (fT4) was within or just above the reference range in all groups at T1, but 7.4% of Group 1 had values <9 pmol/l compared with 5.1% and 0% for Groups 2 and 3, respectively. At 3 months weight, length and OFC SDS values were -0.39, -0.35, 0.09; -0.30, -0.47, 0.32; and -0.03, -0.13, 0.18 for Groups 1, 2 and 3, respectively, indicating relatively large OFC in all infants. A regression adjustment model showed no significant difference in growth rate from baseline and 12 or 18 months of age, between the three groups. CONCLUSION: An initial T4 dose of 50 mug daily, normalises thyroid function several months earlier than lower-dose regimes, with no evidence of sustained somatic overgrowth between 3 months and 3 years.

Endothelin-1 gene and endothelial nitric oxide synthase gene polymorphisms in adolescents with juvenile and obesity-associated hypertension.

Hypertension is an increasing public health problem all over the world. Essential hypertension accounts for more than 90% of cases of hypertension. It is a complex genetic, environmental and demographic trait. New method in molecular biology has been proposed a number of candidate genes, but the linkage or association with hypertension has been problematic (lack of gene-gene and gene-environment interaction). It is well known that genetic influences are more important in younger hypertensives, because children are relatively free from the common environmental factors contributing to essential hypertension. The association studies compare genotype ferquencies of the candidate gene between patient groups and the controls, in pathways known to be involved in blood pressure regulation. This study examined three polymorphisms of these factors encoding genes (ET-1 G+5665T (Lys198Asn), endothelial nitric oxide synthase (eNOS) T-786C promoter polymorphism and 27-bp repeat polymorphism in intron 4) in adolescents with juvenile essential and obesity-associated hypertension. Significant differences were found in the G/T genotype of the ET-1 polymorphism in the hypertensive and obese+hypertensive patients (body mass index (BMI) > 30). A strong association was detected between the BMI and the polymorphism of the ET-1 gene. It seems that ET-1 gene polymorphism plays a role in the development of juvenile hypertension associated with obesity. Although no significant differences were seen in the case of the eNOS promoter polymorphism and the eNOS 4th intron 27-bp repeat polymorphism. It seems that eNOS may play a role, but this is not the main factor in the control of blood pressure; it is rather a fine regulator in this process. This study with adolescents facilitates an understanding of the genetic factors promoting juvenile hypertension and obesity.

Vascular changes play a role in the pathogenesis of necrotizing enterocolitis in asphyxiated newborn pigs.

Necrotizing enterocolitis (NEC) is the most common acquired gastrointestinal emergency in neonates. We have developed an animal model of NEC in asphyxiated newborn pigs and investigated the effects of asphyxia on blood flow in superior mesenteric artery and abdominal aorta, cardiovascular data, arterial acid-base and blood gas parameters, and endothelial cytoskeletal structure in mesenteric microvasculature. Anesthetized, mechanically ventilated newborn pigs were included in two groups: piglets underwent severe asphyxia, and sham-operated control animals. A cardiovascular and metabolic failure developed in asphyxiated piglets approximately 1 h after the induction: severe hypotension and bradyarrhythmia were seen and significant reductions of the blood flow were measured in the superior mesenteric artery and abdominal aorta during the critical phase. Rearrangement of cytoskeletal actin structure corresponding to enhanced vascular permeability was seen with bodipy phallacidin in mesenterial endothelium of asphyxiated piglets after a 24-h recovery period. In conclusion, severe vasomotor changes during asphyxia may result in mesenteric endothelial dysfunction implicated in increased vascular permeability, edema formation, and development of NEC in asphyxiated piglets.

Is the partial pressure of carbon dioxide in the blood related to the development of retinopathy of prematurity?

AIMS: To determine the role of carbon dioxide in the development of retinopathy of prematurity (ROP). METHODS: This was a retrospective cohort study of 25 consecutive infants admitted to the neonatal unit with continuously recorded physiological data. The daily mean and standard deviation (SD) of transcutaneous carbon dioxide partial pressure (tcPCO(2)) was compared between infants who had stage 1 or 2 ROP and stage 3 ROP. The time spent hypocarbic (<3 kPa) and/or hypercarbic (>10 kPa and >12 kPa) was also compared between these groups. Intermittent arterial carbon dioxide tension was also measured and compared with the simultaneous tcPCO(2) data. RESULTS: There were no significant differences in carbon dioxide variability or time spent hypocarbic and/or hypercarbic between the ROP groups on any day. 86% of transcutaneous values were within 1.5 kPa of the simultaneous arterial value. CONCLUSION: TcPCO(2) measurement can be a very useful management technique. However, in this cohort neither variable blood carbon dioxide tension nor duration of hypercarbia or hypocarbia in the first 2 weeks of life was associated with the development or severity of ROP.

[Management of hydatid disease of the lung]. / A tüdó hydatid megbetegedése és kezelése.

Cystic echinococcosis is a worldwide zoonose which is not infectious from man to man occurring seldom in our country. The diagnosis and the treatment of a case of a 4-year-old girl with large left-sided lung cyst were presented. Diagnosis was based on history, clinical findings, imaging techniques (conventional X-ray examination, ultrasonography, computer tomography), eosinophilia (7-50%) in blood smear, leucocytosis (28,000), increased sedimentation of blood (85 mm/hour), significantly elevated antibody against of Echinococcus in immunodiagnostic test (passive haemagglutination) with high sensitivity and specificity, light microscopic radiological and scanning electronmicroscopic analysis of cyst content. Continuous thoracic drainage, twice percutan drainage under CT guidance and a new technique for treatment as Puncture-Aspiration-Injection-Respiration and lavage with hypertonic sodium chlorate, long-term chemotherapy with benzimidazole-carbamates (Vermox: 20 mg/kg/day, Zentel: 30-50 mg/kg/day) were reported. The cyst was grown down into a solid mass as large as 4 cm. The body-weight of this child has grown 6 kilograms and laboratory parameters were normalized.