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Biomedical subjects

B Zieger

Publications and source records attributed to B Zieger.

At least 37 records · Page 2Linked to original sources
PubMed1999

[The quality of the care of children and adolescents within the realm of conventional x-ray diagnosis--a pilot study].

PURPOSE: The aim of the study was to evaluate the current quality of the outpatient radiodiagnostic care of children and adolescents as demonstrated for the example of conventional X-ray procedures. MATERIALS AND METHODS: A consecutive series of 166 outpatient X-rays, selected by fixed criteria, was analysed according to both diagnostic aspects and radiation protection. RESULTS: The X-rays examined were mainly gathered from orthopedic and radiological practices and from hospital radiological departments. The majority of these outpatient X-rays showed significant deficiencies regarding exposure, appropriate field size, and focussing or positioning of the patient. After the evaluation of the 166 X-rays by a total-score, 25% (42/166) of the X-rays were considered to be diagnostically insufficient. CONCLUSIONS: Improvements in outpatient radiodiagnostics are necessary to ensure adequate radiodiagnostic care of children and adolescents.

Adolescent↗
PubMed1998

In vivo expression of murine platelet glycoprotein Ibalpha.

We have performed a systematic in vivo evaluation of gene expression for the glycoprotein (GP) Ibalpha subunit of the murine platelet adhesion receptor, GP Ib-IX-V. This study is warranted by in vitro observations of human GP Ibalpha expression in cells of nonhematopoietic lineage and reports of regulation of the GP Ibalpha gene by cytokines. However, an in vivo role for a GP Ib-IX-V receptor has not been established beyond that described for normal megakaryocyte/platelet physiology and hemostasis. Our Northern analysis of mouse organs showed high levels of GP Ibalpha mRNA in bone marrow with a similar expression pattern recapitulated in mice containing a luciferase transgene under the control of the murine GP Ibalpha promoter. Consistently high levels of luciferase activity were observed in the two hematopoietic organs of mice, bone marrow (1,400 relative light units/microg of protein [RLUs]) and spleen (500 RLUs). Reproducible, but low-levels of luciferase activity were observed in heart, aorta, and lung (30 to 60 RLUs). Among circulating blood cells, the luciferase activity was exclusively localized in platelets. No increase in GP Ibalpha mRNA or luciferase activity was observed after treatment of mice with lipopolysaccharides (LPS) or tumor necrosis factor-alpha (TNF-alpha). We conclude the murine GP Ibalpha promoter supports a high level of gene expression in megakaryocytes and can express heterologous proteins allowing an in vivo manipulation of platelet-specific proteins in the unique environment of a blood platelet.

Animals↗
PubMed1998

Structure and expression of the human septin gene HCDCREL-1.

Septins are a family of highly conserved filament-forming proteins that have been shown to mediate cytokinesis and cytoskeletal organization in fungi and Drosophila. The gene encoding the human septin family member HCDCREL-1 has been shown to be transcribed from a locus immediately adjacent to that of the platelet glycoprotein (GP) Ib b. The HCDCREL-1 gene possesses a non-consensus polyadenylation signal that apparently is not efficiently utilized, resulting in the expression of a readthrough transcript also containing the platelet GPIb beta coding region. As a first step in understanding the regulation and function of HCDCREL-1, we have analyzed the structure of this gene and characterized its expression in a variety of human cells. Our results indicate that the gene is expressed at high levels in platelets and neural tissue, and is transcriptionally complex.

Base Sequence↗
PubMed1998

[Diagnosis of vesicoureteral reflux with echo-enhanced micturition urosonography].

AIM: To ascertain the diagnostic efficacy of reflux sonography with the application of the echo-enhancing agent Levovist in comparison with X-ray voiding cystourethrography (VCUG). PATIENTS AND METHODS: Echo-enhanced voiding urosonography (VUS) and VCUG were performed successively in one examination session in 114 children referred for the investigation of possible vesicoureteral reflux (VUR). After sonography of the urinary tract the bladder was filled with normal saline and Levovist was administered. Reflux was diagnosed when hyperechogenic, floating microbubbles appeared in the ureters or renal pelvises. RESULTS: A total of 226 kidney-ureter units were available for analysis. Reflux was diagnosed in 80 units. All grades of reflux were represented. In 15 kidney-ureter units VUR was diagnosed with echo-enhanced VUS but was not seen at VCUG. The contrary was true in 3 units. High sensitivity and specificity in comparison to the VCUG could be attributed to the echo-enhanced VUS. The long imaging window attainable with Levovist makes the documentation of convincing images possible, contributing to the high diagnostic efficacy. CONCLUSION: Echo-enhanced VUS is comparable to VCUG in the diagnosis of reflux.

Adolescent↗
PubMed1998

Sonomorphology and involution of the normal urachus in asymptomatic newborns.

BACKGROUND: The number of reports on the sonomorphology of the urachus or urachal remnants in neonates and the pattern of involution is limited. OBJECTIVE: To determine whether a sonographically visible urachus in the first months of life is a pathologic condition and whether postnatal involution can be demonstrated by ultrasound. MATERIALS AND METHODS: A total of 102 asymptomatic infants (premature and term newborns) were examined with a high-resolution 7.5-MHz linear transducer between 0 and 60 days of age. In 70 infants, a second examination followed 3-5 months later. RESULTS: In all infants, the urachus could be identified on the first examination. Different morphological types were differentiated. There was no difference between premature and term newborns in the morphology of the urachus. Spontaneous involution of the urachus was observed in all infants receiving a second examination, and they most often showed a fusiform urachal remnant at the apex of the bladder. CONCLUSION: Involution of the urachus is not complete at birth and can be followed up sonographically in the first months of life. This knowledge should prompt a new strategy in young infants with a discharging umbilicus or even an infected urachus. Instead of early surgery, a conservative approach under sonographic control seems reasonable, because there is a chance of spontaneous involution and any abnormal development can be detected by ultrasound.

Female↗
PubMed1998

Percutaneous renal biopsy in children: a 27-year experience.

BACKGROUND: The introduction of automated biopsy devices and the localization of the kidney by ultrasound were aimed at optimizing efficacy and safety of the percutaneous renal biopsy procedure. We evaluated these technological advances in our renal biopsies performed in children. METHODS: We sequentially used the Silverman needle (1969-1974), the TruCut needle (1974-1990), and the automated Biopty device (1990-1996). Fluoroscopy was used to localize the kidney until 1985, ultrasound examination prior to biopsy from 1985 to 1992, and direct ultrasound guidance since 1992. A total of 962 native kidney biopsies and 119 allograft biopsies were performed. RESULTS: In the native kidney biopsies, the introduction of the Biopty device and ultrasound guidance were independently associated with fewer passes required to obtain adequate tissue and more glomeruli per specimen. The rate of biopsies yielding more than 9 glomeruli increased from 69 to 92% (p < 0.05). The number of glomeruli harvested per centimeter core length was inversely related to patient age (p < 0.01). More appropriate cortical tissue was retrieved in renal allograft biopsy specimens with the application of the new techniques. The occurrence of macroscopic hematuria (9. 6%) in the native kidney biopsies was not affected by the puncture or localization technique applied, but subcapsular hematomas were documented more often with the Biopty device (42%) than with the TruCut needle (16%), probably due to improved ultrasound equipment. In the whole series 2 patients died, and 3 others required renal surgery and 4 blood transfusions. CONCLUSIONS: The automated ultrasound-guided procedure is a feasible and reliable technique for percutaneous renal biopsy in children. It gives a greater yield of diagnostic tissue without increasing the rate of clinical complications.

Adolescent↗
PubMed1997

New families with von Willebrand disease type 2M (Vicenza).

The variant von Willebrand disease (vWd) variant type 2M (Vicenza) was identified in 13 patients of 7 unrelated families. 11 patients were from different parts of germany and 2 patients from Turkey. Hitherto this variant of vWd has been described only in two families originating from the province of Vicenza in Northern Italy. Characteristically this type of vWd shows the supranormal multimers of von Willebrand factor (vWf) in plasma similar to those seen in normal plasma after desmopressin infusion. Clinically, the patients present with bleeding symptoms. Other laboratory abnormalities include reduced values for vWf antigen (vWf: Ag), factor VIII coagulant activity (VII:C), ristocetin cofactor activity (RiCof) and collagen binding activity (vWf: CBA). The hereditary transmission of this variant is consistent with an autosomal dominant mode of inheritance. The patients with vWd type 2M (Vicenza) could be allocated into two subgroups: type "platelet normal" with normal vWf properties in platelets and type "platelet low" with reduced vWf: Ag levels in platelets.

Adult↗
PubMed1997

Alternative expression of platelet glycoprotein Ib(beta) mRNA from an adjacent 5' gene with an imperfect polyadenylation signal sequence.

Glycoprotein (GP) Ib is a major component of the platelet membrane receptor for von Willebrand factor, designated the GP Ib-IX-V complex. GP Ib is composed of two subunits (GP Ib(alpha) and GP Ib(beta)) each synthesized from separate genes. The 206 amino acid precursor of GP Ib(beta) is synthesized from a 1.0-kb mRNA expressed by megakaryocytes and was originally characterized from cDNA clones of human erythroleukemic (HEL) cell mRNA, a cell line exhibiting megakaryocytic-like properties. The cell line CHRF-288-11 also exhibits megakaryocytic-like properties, but synthesizes two related GP Ib(beta) mRNA species of 3.5 and 1.0 kb. We performed cDNA cloning experiments to identify the origin of the 3.5-kb transcript and determine its relationship to the 1.0-kb GP Ib(beta) mRNA found in megakaryocytes, platelets, and HEL cells. Our cloning experiments demonstrate that the longer transcript results from a nonconsensus polyadenylation recognition sequence, 5'AACAAT3', within a separate gene located upstream to the platelet GP Ib(beta) gene. In the absence of normal polyadenylation the more 5' gene uses the polyadenylation site within its 3' neighbor, the platelet GP Ib(beta) gene. This newly identified 5' gene contains an open reading frame encoding 369 amino acids with a high degree of sequence similarity to an expanding family of GTP-binding proteins.

Amino Acid Sequence↗
PubMed1997

[Osteomyelitis during the growth period. Diagnostic imaging].

In acute osteomyelitis of childhood a rapid diagnosis and initiation of antibiotic therapy is necessary in order to prevent late sequelae. Thus, diagnostic imaging plays a crucial role. If acute osteomyelitis is suspected in a child, imaging starts with conventional radiography in order to exclude other differential diagnoses. This is followed by sonography for the purpose of diagnosing a subperiosteal abscess or joint fluid from which the causative organism could be isolated. If the diagnosis is unclear, the next step should be either MRI or 99mTc-MDP bone scan, depending on the possibility of clinical localization and the site of the suspected lesion. MRI is superior to bone scan in depicting the exact anatomy, which is extremely important in spinal osteomyelitis and preoperatively. The bone scan can show the whole skeleton in one examination and should be favored if there is no definite localization or in suspected multifocal osteomyelitis. Rarely scintigraphy with labeled white blood cells is indicated. The 67Ga scan, however, should not be used in children because of the high level of radiation exposure. The different imaging modalities are described in detail and an imaging diagnostic workup is outlined.

Acute Disease↗
PubMed1997

Cloning and deduced amino acid sequence of human nicotinamide nucleotide transhydrogenase.

Pyridine nucleotide transhydrogenases (E.C.1.6.1.1) are integral proteins of the inner mitochondrial membrane. These enzymes are part of the energy-transfer system of the respiratory chain and specifically catalyze the transfer of a hydride ion between nicotinamide adenine dinucleotide, NAD(H), and oxidized nicotinamide dinucleotide phosphate, NADP(H). Here we report the sequence of full-length cDNA clone containing the coding sequence for human mitochondrial nicotinamide nucleotide transhydrogenase. The characterized cDNA contains an insert of 4,232 base pairs with a 91% sequence identity to a previously characterized bovine transhydrogenase cDNA. The deduced human polypeptide sequence displays a high degree of sequence similarity, 97%, to the bovine polypeptide and a comparison of the two sequences is presented.

Amino Acid Sequence↗
PubMed1996

Inherited defects of the protein C anticoagulant system in childhood thrombo-embolism.

Childhood thrombo-embolism is mostly the result of inherited thrombophilia or vascular insults combined with risk factors such as peripartal asphyxia, fetopathia diabetica, exsiccosis, septicaemia, central lines, congenital heart disease, cancer, trauma, surgery or elevated antiphospholipid antibodies. Inherited thrombophilia includes mainly defects of the protein C pathway, resistance to activated protein C, protein C or protein S deficiency. Resistance to activated protein C, in the majority of cases caused by the point mutation Arg 506 Gln of the factor V gene, has emerged as the most important hereditary cause of thrombo-embolism in adults and children. However, since an acquired risk of thrombo-embolic complications frequently masks the inherited deficiency in affected children, children with thrombo-embolism should have adequate laboratory evaluation for inherited coagulation disorders, especially the protein C pathway. Until more data on childhood thrombo-embolism are available, treatment recommendations will continue to be extrapolated from guidelines for adults.

Blood Coagulation↗
PubMed1996

Bilateral renal venous thrombosis in a neonate associated with resistance to activated protein C.

Renal venous thrombosis (RVT) is a serious complication of neonates. In most cases the underlying cause of RVT remains unclear. Here we report a neonate with bilateral RVT and adrenal haemorrhage associated with a heterozygous mutation of the gene encoding for clotting factor V, resulting in resistance to activated protein C. Vigorous thrombolytic therapy with urokinase followed by recombinant tissue plasminogen activator dissolved the thrombus in the inferior vena cava and restored perfusion of both kidneys. However, a haemorrhagic rupture of the right kidney occurred, requiring emergency nephrectomy. Despite reperfusion of the left kidney and resumption of urine output, the patient remained dialysis dependent. Due to persistent adrenal insufficiency, long-term substitution of hydrocortisone was necessary. The patient was prophylactically treated with coumarin during the first 6 months of life and is now waiting for renal transplant at the age of 1 year.

Anticoagulants↗
PubMed1996

Controlling elements of platelet glycoprotein Ib alpha expression.

Our objectives are to define and characterize molecular events of megakaryocytopoiesis and platelet production by analyzing the in vivo expression of platelet glycoprotein (GP) receptors. Our studies target the platelet GP Ib-IX-V complex since the congenital absence of the receptor results in the Bernard-Soulier syndrome, a condition linking the expression of the complex to normal platelet morphogenesis. We have previously described the generation of a transgenic mouse colony expressing the alpha-subunit (GP Ib alpha) of the human platelet GP Ib-IX-V complex. These studies established methodologies to manipulate GP Ib-IX-V on the platelet surface and examine unique aspects of hemostasis, megakaryocytopoiesis, platelet structure and platelet release. Our recent studies have defined the genetic elements supporting the megakaryocytic-expression of GP Ib alpha. These results are defining essential cis-acting elements responsible for the expression of GP Ib alpha and are providing insights into molecular events coinciding with the release of normal platelets into the bloodstream.

Animals↗
PubMed1995

Identification of a candidate missense mutation in a family with von Willebrand disease type IIC.

A screening project to identify candidate molecular defects causing von Willebrand disease type IIC (VWD IIC) in a German family was carried out using polymerase chain reaction (PCR) amplification of all 52 exons of the von Willebrand factor (VWF) gene, subsequent electrophoresis of single and double stranded DNA and direct sequencing of PCR products with aberrant electrophoretic patterns. Only one candidate mutation, G550R, caused by a G-->A transition, was detected in exon 14 of the pro-VWF gene sequence. This mutation was not found on 200 chromosomes of normal individuals. The propositus was homozygous for the mutation and for an extended intragenic haplotype, composed of eight polymorphic markers. Further family members were heterozygous for the mutation and were phenotypically normal or only mildly affected, in accordance with the recessive pattern of inheritance for VWD type IIC. The mutation could influence one of the presumed active centers for the suspected multimerizing enzymatic activity of pro-VWF localized in the D1 and D2 domain, which corresponds to exon 5 and exon 14 of the VWF gene.

Amino Acid Sequence↗
PubMed1977

The stereochemistry of the addition of glycerol to D-galactal, catalyzed by beta-D-galactosidase.

On incubation with beta-D-galactosidase, D-galactal-2-d (1) plus glycerol yielded 1-deoxyglycerol-1-yl 2-deoxy-beta-D-lyxo-hexopyranoside-2(S)-d. By 1H-n.m.r. analysis, it was shown that the hydrogen atom introduced on C-2 is trans-related to the aglycon moiety. In contrast to this stereospecific, enzyme-catalyzed addition, the reaction of phenol with peracetylated 1, catalyzed by p-toluenesulfonic acid, which yields phenyl 3,4,6-tri-O-acetyl-2-deoxy-alpha-D-lyxo-hexopyranoside-2-d, was shown to entail both a trans and a cis addition.

Catalysis↗