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Biomedical subjects

A Rieger

Publications and source records attributed to A Rieger.

At least 73 records · Page 4Linked to original sources
PubMed1996

A bulged region of the hepatitis B virus RNA encapsidation signal contains the replication origin for discontinuous first-strand DNA synthesis.

Human hepatitis B virus (HBV) is a small DNA virus that replicates inside the viral nucleocapsid by reverse transcription of an RNA intermediate. Encapsidation of this RNA pregenome is mediated by the interaction of the viral replication enzyme P with the structured 5'-proximal RNA element epsilon; replication was thought to start in the 3'-proximal direct repeat DR1*. However, recent data obtained with the duck hepatitis B virus indicated a novel, discontinuous mechanism of negative-strand DNA synthesis. Here we demonstrate, using DNA transfection of complete HBV genomes, that the 3'-half of a 6-nucleotide bulge in HBV epsilon whose primary sequence is not important for encapsidation serves as template for a short DNA primer that is subsequently transferred to DR1*. Apparently, P protein copies any template sequence that does not interfere with epsilon structure; however, altered primary sequences can induce polymerase stuttering, resulting in extended primers containing more than one equivalent of the template sequence. The importance of the bulged structure is emphasized by the dependence of primer length on bulge size. Transfer specificity is in part controlled by sequence complementarity. The strategy of using the 5' encapsidation signal as the origin of replication for discontinuous negative-strand DNA synthesis, common to mammalian and avian hepadnaviruses, suggests the evolutionary origin of hepatitis B viruses to lie between that of modern retroviruses and primitive retroelements like the Mauriceville retroplasmid.

Base Sequence↗
PubMed1995

Distinct requirements for primary sequence in the 5'- and 3'-part of a bulge in the hepatitis B virus RNA encapsidation signal revealed by a combined in vivo selection/in vitro amplification system.

Hepatitis B virus (HBV) is a small DNA virus that replicates by reverse transcription of a terminally redundant RNA, the pregenome. Specific packaging of this transcript into viral capsids is mediated by interaction of the reverse transcriptase, P protein, with the 5'-proximal encapsidation signal epsilon, epsilon-function is correlated with the formation of a hairpin structure containing a bulge and a loop, each consisting of 6 nt. To analyse the importance of primary sequence in these regions, we have combined selection of encapsidation competent individuals from pools of randomized epsilon-sequences in transfected cells with in vitro amplification, thus bypassing the current experimental limitations of the HBV system. While no alterations of the authentic loop sequence were detectable, many different sequences were tolerated in the 3'-part of the bulge. However, at the two 5'-proximal bulge positions the wt sequence was strongly selected for, indicating that for RNA packaging close contacts between protein and the 5'- but not the 3'-part of the bulge are important. Such a bipartite organisation provides a structural basis for the recently demonstrated special role of the 3'-part of the bulge as template for the first nucleotides of (-)-strand DNA in HBV reverse transcription.

Base Sequence↗
PubMed1995

[Endotracheal intubation with propofol and fentanyl].

The routine use of succinylcholine for endotracheal intubation is being increasingly questioned. Initial studies have suggested that a combination of propofol and alfentanil without a muscle relaxant can provide good intubating conditions. However, most of these initial studies either did not have a double-blind design or did not include a control group with muscle relaxants. In this study, intubation conditions using fentanyl/propofol without a muscle relaxant were compared with the combinations of fentanyl/propofol/succinylcholine and sodium thiopental/succinylcholine. MATERIAL AND METHODS. Following approval from the local ethics committee and written consent, 100 gynaecological patients (ASA I, II) were included in this study. The study was carried out in a double blind, randomized and prospective manner. Black perfusor syringes and extension sets were used, and the drugs administered were diluted to equal volumes. For induction, group 1 (n = 25) received 0.1 mg fentanyl, 1 mg vecuronium, sodium thiopental (demand-adapted) and succinylcholine 1 mg/kg; group 2 (n = 25) received 0.1 mg fentanyl and propofol (demand-adapted); group 3 (n = 25) received 0.2 mg fentanyl and propofol (demand-adapted); group 4 (n = 25) received 0.1 mg fentanyl, 1 mg vecuronium, propofol (demand-adapted) and succinylcholine 1 mg/kg. Each patient was assessed prior to induction with regard to visualization of the pharynx (grade I-IV). Following induction, jaw relaxation (grade I-IV) and the laryngoscopic visualization of the glottis (grade I-IV) were assessed. During the intubation, the position and movements of the vocal cords (grade I-IV) and patient movement during and 1 min following the intubation were assessed. The overall assessment of the intubation was graded (grade I-IV) by the anaesthetist and the anaesthetic nurse. Postoperatively the patients were questioned regarding muscle pain (grade I-IV). Before, during and after endotracheal intubation arterial haemoglobin oxygen saturation, heart rate and arterial blood pressure were monitored. RESULTS. There were no intergroup differences with regard to age, height, weight and preanaesthetic visualization of the pharynx. In group 1 an average of 5.5 +/- 1.2 mg/kg sodium thiopental was required. There were no significant differences in group 2, 3 and 4 with respect to the dose of propofol (2.4, 2.2 and 2.2 mg/kg). No intergroup differences were noted with regard to jaw relaxation, laryngoscopic visualization of the glottis and patients' movements during intubation. Statistically significant intergroup differences occurred with regard to the position and movements of vocal cords during intubation (group 3 worse than groups 1, 2, 4) and the patients' movements 1 min after intubation (group 2 worse than group 3). Significant intergroup differences also occurred with regard to the overall assessment of the intubation by the anaesthetist (group 3 worse than groups 2, 4) and the anaesthetic nurse (group 3 worse than group 4) and the postoperative muscle pain (group 1 worse than groups 2, 3). CONCLUSION. The use of 0.1 mg fentanyl/sodium thiopental/succinylcholine results in no better intubating conditions than 0.1 mg fentanyl plus propofol. Under these conditions, without the use of a muscle relaxant, it is possible to carry out safe endotracheal intubation in cases where no complications are anticipated.

Adult↗
PubMed1995

Stereotactic cysto-ventricular shunting in diencephalic (arachnoid) cysts and failure in cystic craniopharyngeoma.

Stereotactic cysto-ventricular shunting in three patients with congenital (subependymal cyst of the 3rd ventricle, subependymal cyst of the foramen of Monro, cyst of cavum septi pellucidi) and in a female patient with a large cystic suprasellar craniopharyngeoma is dealt with in this paper. The first operation was performed in May 1992 and the latest, being considered in this paper, in October 1993. All patients were admitted to our hospital suffering from signs of increased intracranial pressure. CT-scans revealed on the one hand an obstructive hydrocephalus subjected to the cystic arachnoid lesions, on the other hand a large hypodense suprasellar cystic tumor. After stereotactic puncture of the arachnoid cysts, aspiration of their contents as well as biopsy of the wall, a silicone catheter was implanted, thus constructing a permanent communication between the cyst and the lateral or third ventricle. The internal catheter was connected to a subcutaneous burr-hole reservoir. All these patients recovered uneventfully without neurological deficits. There were no operative complications. Follow-up CT-scans showed no recurrences of the cysts and obstructive hydrocephalus. In the patient with the suprasellar craniopharyngeoma at first a stereotactic puncture of the cyst was performed. After recurrence the tumor was directly approached by an frontotemporal craniotomy. The histological examination revealed now a craniopharyngeoma. After renewed recurrence a stereotactic cysto-ventriculostomy with internal shunt implantation was performed. However, in this case this method was unsuccessful, documented by follow-up CT-scans. Resulting from our experiences, it is quite obvious that the stereotactic internal shunt implantation seems to be a safe, proper and reliable method in the treatment of arachnoid cystic lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Safe and normothermic massive transfusions by modification of an infusion warming and pressure device.

A fluid-warming pressure infusion device (H-500/H25i, Level 1) was modified to meet the demands for safe, normothermic, and effective massive transfusions. By incorporating an autoventing 40 microns filter (Pall AV-SP), which was originally manufactured for use in an extracorporal circulation, the risk of accidental air embolism can be eliminated. Feasibility and efficiency of this model were tested in ten patients. The mean volume transfused and infused (packed red cells and colloids) was 6750 mL (SD +/- 2519) during a mean period of acute volume resuscitation of 55 minutes (SD +/- 30). Calculated flow rates averaged 140 mL/min, which were sufficient to stabilize all but one patient. This patient subsequently died because of uncontrollable surgical bleeding. Body temperature remained stable with a minimal mean drop of -0.3 degrees C. Supplying the Level 1 warming and pressure device with a Pall AV-SP filter allows for safe, effective, and demand-adapted massive transfusions in a large number of trauma patients at a reasonable cost.

Blood Transfusion↗
PubMed1995

Relevance of carbohydrate-deficient transferrin as a predictor of alcoholism in intensive care patients following trauma.

Every second traumatized patient is a chronic alcoholic. Chronic alcoholics are at risk due to an increased morbidity and mortality. Reliable and precise diagnostic methods for detecting alcoholism are mandatory to prevent posttraumatic complications by adequate prophylaxis. The patient's history, however, is often not reliable, and conventional laboratory markers are not sensitive or specific enough. The aim of this study was to investigate whether carbohydrate-deficient transferrin (CDT) is a sensitive and specific marker to detect alcoholism in traumatized patients. One hundred and five male traumatized patients or their relatives gave their written informed consent to participate in this institutionally approved study. All patients were transferred to the intensive care unit after admission to the emergency room, followed by surgical treatment. Diagnostics included an alcoholism-related questionnaire, conventional laboratory markers (mean corpuscular volume, gamma-glutamyltransferase, aspartate aminotransferase, and alanine aminotransferase), and CDT sampling (microanion-exchange chromatography, turbidimetry, and radioimmunoassay, respectively). Only patients in whom a reliable history could be obtained were included. Alcoholism was diagnosed if the patients met the Diagnostic and Statistical Manual of Mental Disorders criteria for chronic alcohol abuse or dependence. The administration of fluids before CDT sampling was carefully documented. Patients did not differ significantly regarding age, Trauma and Injury Severity Score, and Acute Physiology and Chronic Health Evaluation score. The sensitivity of the CDT research kit was 70% and of the commercially available kit CDTect was 65%. Early sampling in the emergency room and before administration of large volumes of fluid increased the sensitivity to 83% for the CDT research kit and 74% for CDTect, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Feasibility and rate of leucocyte depletion with a single leucocyte depletion filter during massive transfusion.

BACKGROUND: The study examines the feasibility and rate of leucocyte depletion with a single leucocyte depletion filter in combination with the Level 1 heat exchanging infusion/transfusion device H-500/H-25i during massive transfusions. MATERIALS AND METHODS: LeukoGuard-6 filters (LG-6) were manufactured to fit the infusion sets of the Level 1 H-500/H-25i. This modified device was used intraoperatively in six patients with severe haemorrhage. Following determination of the white cell counts (WCC) in each buffy coat poor red cell concentrate prior to administration, WCC were then obtained from blood sampled directly distal to the filter after the first and after the last red cell concentrate was given. Leucocytes were determined in the Nageotte chamber and then calculated to determine leucocytes/250 ml (therapeutic unit). Parameters of feasibility (time for preparation of the system, the amount of transfused red cell concentrates, time interval of transfusions) were recorded. RESULTS: The mean volume of red cell concentrates which were transfused and filtered by a single filter was 2,708 ml (S.D. +/- 797 ml) within a mean time interval of 42.5 min (S.D. +/- 26 min). With a mean WCC of 1.17 +/- 0.68 x 10(9) leucocytes/250 ml in the red cell concentrate prior to filtration the LG-6 achieved a log-3 reduction of leucocyte counts. During the transfusion the WCC distal to the filter increased on average by a factor of 3 (from 0.9 x 10(6) leucocytes/250 ml following the first blood unit to 2.7 x 10(6) leucocytes/250 ml following the last), but remained below 5 x 10(6). CONCLUSION: Modification of the Level 1 H-500/H-25i system by incorporating the LG-6 leucocyte depletion filter provides a significant reduction of the WCC in the transfused red cell concentrates during massive transfusion. The rate of leucocyte depletion by a single leucocyte depletion filter achieves low leucocyte counts which are documented to be of therapeutical value. As the significance of leucocyte-reduced blood products for patients with haemorrhagic shock following trauma or major surgery has still to be elucidated, the presented device may be useful in the performance of future studies related to this subject.

Blood Volume↗
PubMed1995

[Modified Kirschner wire insertion for direct ventral screw fixation of dens fractures].

Since 1985 25 patients with a fracture of the odontoid process (dens) were operated in the Neurosurgical Department of the Justus-Liebig-University in Giessen. An early stabilization through an anterior approach was favoured for type II fractures, and for displaced type III injuries, according to the classification of Anderson and d'Alonzo. Two double threaded screws were implanted to reach a compression between the fragments and a stabilization of rotation. With patients having a large thoracic volume and/or a short neck there are often problems, to insert the K-wires in the correct angle, before the screw fixation is performed. For these cases we have developed a new device for the K-wire insertion. After technical examinations in specimen the device was successfully applied in clinical use. This device with its inherent advantages is presented and discussed in this paper.

Bone Screws↗
PubMed1995

[Correlation between the gradient constant of the theoretical pressure volume diagram (PVD) and the pressure volume index (PVI) in relation to brain pulse amplitude-mean pressure function].

In 54 neurosurgical patients--suffering from intracranial tumors, hydrocephalus or different kinds of brain injury--a catheter was implanted in the lateral ventricle for continuously monitoring of the intracranial pressure (ICP). The intraventricular injection of defined amounts of sodium clearance (1-2 cm3) was followed by increased values of intracranial mean pressure--(pm) and pulse-amplitude- (PA). The recorded data showed a high significant correlation after regression analysis. After determination of the pressure-volume-index (PVI) and the theoretical pressure-volume-diagram it was examined whether there is a linear correlation between the parameters of the craniospinal space (id) reserves (constant of gradient, (PVI, K of PVD)) and the gradients (CA) of the linear PA-PM-function. A significant linear relationship, however of weak degree, could be found between these two parameters. The linear PA-PM-function, therefore, can only be understood in restricted circumstances as a direct parameter of the intracranial spacial reserves. The underlying facts of these problems are dealt within this paper.

Brain Injuries↗
PubMed1994

A review on Fc epsilon RI on human epidermal Langerhans cells.

In order to show the surface expression of Fc epsilon RI on human epidermal Langerhans cells (LC), we examined monomeric IgE binding to LC. We demonstrated that the majority of epidermal LC were able to bind monomeric IgE. IgE binding to LC could neither be prevented by preincubation of the tissue with monoclonal antibodies (mAb) against either Fc epsilon RII/CD23 or Fc gamma RII/CD32, nor by the addition of lactose, but could be entirely abrogated by preincubation with the anti-Fc epsilon RI mAb 15-1. These data show that epidermal LC express Fc epsilon RI molecules.

Humans↗
PubMed1994

Stereotactic cysto-ventricular shunting in diencephalic (arachnoid) cysts.

Stereotactic cysto-ventricular shunting in three patients with congenital (subependymal cyst of the 3rd ventricle, subependymal cyst of foramen of Monroi, cyst of cavum septi pellucidi) is dealt with in this paper. The first operation was performed in May 1992 and the latest, being considered in this paper, in January 1993. All patients were admitted to our hospital suffering from increased intracranial pressure. CT-scans revealed an obstructive hydrocephalus subjected to the cystic lesions. After stereotactic puncture of these cysts, aspiration of their contents as well as biopsy of the wall a silicone catheter was implanted, thus constructing a permanent communication between the cyst and the lateral or 3rd ventricle. The internal catheter was connected to a subcutaneous burr-hole reservoir. All patients recovered uneventfully without neurological deficits. There were no operative complications. Follow-up CT-scans showed no recurrences of the cysts and obstructive hydrocephalus. Resulting from our experiences, it is quite obvious that the stereotactic internal shunt implantation seems to be a safe, proper and reliable method in the treatment of such cystic lesions. Open craniotomy or intracorporal shunting procedures and their immanent complications can be avoided for most cases of congenital intracranial cysts. It should, therefore, be the aim of further clinical investigations to prove the value of this method in additional cases.

Arachnoid Cysts↗
PubMed1993

Intranasal fentanyl titration for postoperative pain management in an unselected population.

A randomized, double-blind study was undertaken to investigate the suitability of intranasally administered fentanyl for postoperative pain management under routine conditions in an unselected population. For postoperative pain relief, patients received either 0.027 mg fentanyl intranasally and sodium chloride 0.9% intravenously (intranasal group, n = 53) or sodium chloride 0.9% intranasally and 0.027 mg fentanyl intravenously (intravenous group, n = 59). These doses were repeated every 5 min until the patients were free of pain or refused further analgesia. Pain severity was evaluated before beginning opioid titration and 5, 10, 15, 20, 30, 40, 50, 60, 70 and 80 min thereafter. Adequate pain relief was achieved in 52 of 53 patients in the intranasal and in all patients in the intravenous group. Pain intensities evaluated on a 101-point numerical rating scale as well as on a verbal rating scale decreased significantly in both study groups within 5 min. At the 15 min measurement point, numerical rating scale pain intensity and at the 10 and 20 min point, verbal rating scale pain intensity was significantly lower in the intravenous group. The incidence of side effects was low in both groups and no patient complained of intranasal pain. Intranasally administered fentanyl would appear to be suitable for the management of postoperative pain.

Administration, Intranasal↗
PubMed1993

An intramolecular disulfide bridge between Cys-7 and Cys61 determines the structure of the secretory core gene product (e antigen) of hepatitis B virus.

Hepatitis B virus, the prototypic member of the Hepadnaviridae, is a small enveloped DNA virus that replicates via reverse transcription. Efficient usage of its compact 3.2-kb genome is exemplified by the pre-C/C gene from which two proteins with largely overlapping primary sequences but distinctly different properties are synthesized: the self-assembling core protein p21c (hepatitis B core antigen [HbcAg]) and the secretory, nonparticulate protein p17e (hepatitis B e antigen [HbeAg]). Mature p17e carries a 10-amino-acid N-terminal extension with a Cys residue (Cys-7). Using transient transfection of a human liver cell line with constructs expressing wild-type p17 or a series of Cys mutants of p17, we show that Cys-7 forms an intramolecular S-S bond to Cys61, which in assembly-competent core proteins is available for intermolecular disulfide bonds between two neighboring subunits. Removal of the Cys-7/Cys61 bond by mutating either residue has differential effects: in the absence of Cys-7, secretion is relatively efficient and independent of Cys61; however, the molecules are exported as homodimers exhibiting both HBe and HBc antigenicity. In the absence of Cys61, the nonpaired Cys-7 interferes with secretion efficiency. The amino acid sequence flanking Cys-7 also contributes to the formation of the proper intramolecular S-S bond. These results suggest that the Cys-7/Cys61 bond imposes on p17e a conformation that is critical for its secretion and distinct biophysical and antigenic properties. This mechanism adds selective disulfide formation to the repertoire of hepatitis B virus for efficient use of its tiny genome.

Amino Acid Sequence↗
PubMed1993

[Anesthetic-induced heart arrest. A case report of 2 infants with previously unrecognized muscular dystrophy].

We report two boys aged 4 and 10 months who suffered cardiac arrests after induction of anaesthesia. Both infants had no personal or family history of myopathy. In both cases anaesthesia was induced by inhalation with halothane and N2O/O2 (70/30). To facilitate tracheal intubation both were given succinylcholine after the administration of atropine. The 4-month-old developed muscle rigidity and cardiac arrest occurred immediately after tracheal intubation. Resuscitation was unsuccessful. Laboratory findings during resuscitation showed elevated serum potassium levels of more than 10 mmol/l and serum creatine phosphokinase 17.700 IU/l. Histopathologic examination of the skeletal muscle revealed congenital muscular dystrophy. In the older boy no muscle contractures were noted after administration of succinylcholine. He developed bradycardia that progressed to asystole 15 min after induction of anaesthesia. After 1 h of resuscitation a sinus rhythm could be established. The boy developed myoglobinuria and his serum creatine phosphokinase reached a maximum level of 45,000 IU/l on the 2nd day. The child survived and made a complete recovery. Two months later a muscle biopsy taken from the quadriceps showed marked muscular dystrophy. Duchenne's muscular dystrophy could be excluded. The most likely underlying reasons for these complications are discussed: anaesthesia-induced acute rhabdomyolysis or malignant hyperthermia.

Anesthesia↗
PubMed1992

Topological analysis of the hepatitis B virus core particle by cysteine-cysteine cross-linking.

The nucleocapsid, or core particle, of hepatitis B virus is formed by 180 subunits of the core protein, which contains Cys at positions 48, 61, 107 and 183, the latter constituting the C terminus. Upon adventitious oxidation, some or all of these cysteine residues participate in the formation of disulphide bridges, leading to polymerization of the subunits within the particle. To utilize the cysteine residues as topological probes, we reduced the number of possible intersubunit crosslinks by replacing these residues individually, or in all combinations, by serine. A corresponding set of variants was constructed within the context of an assembly-competent core protein variant that lacks the highly basic C-terminal region. Analysis, by polyacrylamide gel electrophoresis under non-reducing conditions, of the oxidative crosslinking products formed by the wild-type and mutant proteins expressed in Escherichia coli, revealed a clear distinction between the three N-proximal, and the C-terminal Cys: N-proximal Cys formed intermolecular disulphide bonds only with other N-proximal cysteine residues, leading to dimerization. Cys48 and Cys61, in contrast to Cys107, could be crosslinked to the homologous cysteine residues in a second subunit, and are therefore located at the dimer interface. Cys 183 predominantly formed disulphide bonds with Cys183 in subunits other than those crosslinked by the N-proximal cysteine residues. Hence, the polymers generated by oxidation of the wild-type protein are S-S-linked dimeric N-terminal domains interconnected via Cys183/Cys183 disulphide bonds. The intermolecular crosslinks between the N-proximal cysteine residues were apparently the same in the C-terminally truncated and in the full-length proteins, corroborating the model in which the N-terminal domain and the C terminus of the HBV core protein form two distinct and structurally independent entities. The strong tendency of the N-terminal domain for dimeric interactions suggests that core protein dimers are the major intermediates in hepatitis B virus nucleocapsid assembly.

Amino Acid Sequence↗