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H Mentzel

Publications and source records attributed to H Mentzel.

At least 19 recordsLinked to original sources
PubMed2006

Peripheral bone status in rheumatoid arthritis evaluated by digital X-ray radiogrammetry and compared with multisite quantitative ultrasound.

The development of secondary osteoporosis in rheumatoid arthritis (RA) has recently become well recognized, characterized by demineralization at axial and in particular periarticular peripheral bone sites. Our aim was to evaluate multisite quantitative ultrasound (QUS) compared to digital X-ray radiogrammetry (DXR) by the quantification of cortical bone loss dependent on the severity of RA. Fifty-three patients with verified RA underwent QUS measurements (Sunlight Omnisense 7000) with estimation of the speed of sound (QUS-SOS) at the distal radius and at the phalanx of the third digit. Also, bone mineral density (DXR-BMD) and metacarpal index (DXR-MCI) were estimated on metacarpals II-IV using DXR technology. Additionally, Larsen score and Steinbroker stage were assessed. Disease activity of RA was estimated by disease activity score 28 (DAS 28). For the group with minor disease activity (3.2 5.1), QUS-SOS of the radius revealed a significant correlation to DXR-BMD (R = 0.71) and DXR-MCI (R = 0.84), whereas for QUS-SOS (phalanx) no significant association to the DXR parameters was shown. The DXR parameters and, to a lesser extent, the QUS data also demonstrated pronounced declines in the case of accentuated disease activity (DAS > 5.1). Both DXR-BMD (-25.9 %, P < 0.01) and DXR-MCI (-38.6 %, P < 0.01) revealed a notable reduction dependent on the severity of RA. Otherwise, QUS-SOS marginally decreased, with -2.6% (radius) and -3.9% (phalanx). DXR revealed a significant reduction of DXR-BMD as well as DXR-MCI dependent on the severity of RA and surpassed multisite QUS as a promising diagnostic tool.

Absorptiometry, Photon↗
PubMed1999

Decreased frontal activation in schizophrenics during stimulation with the continuous performance test--a functional magnetic resonance imaging study.

The Continuous Performance Test (CPT) has become an essential constituent of the neuropsychological investigation of schizophrenia. Also, a vast number of brain imaging studies, mostly PET investigations, have employed the CPT as a cognitive challenge and established a relative hypofrontality in schizophrenics compared to controls. The aim of the present investigation was to clarify whether this predescribed hypofrontality could also be verified using functional magnetic resonance imaging (fMRI). 20 healthy volunteers and 14 schizophrenics on stable neuroleptic medication were included. Imaging was performed using the CPT-double-T-version and a clinical 1.5 T MRI-scanner with a single slice technique and a T(2)*-weighted gradient-echo-sequence. The schizophrenics exhibited a decreased activation in the right mesial prefrontal cortex, the right cingulate and the left thalamus compared to controls. These results obtained by fMRI are discussed in relation to published findings using PET.

Adult↗
PubMed1994

Biochemical, molecular, and functional characterization of porin isoforms from potato mitochondria.

The mitochondrial outer membrane of eukaryotic cells contains a voltage-dependent anion channel termed porin. In the organisms studied so far only one type of porin has been identified at the protein level. Here we present a biochemical and molecular genetic analysis of two different porin polypeptides of M(r) 34,000 and 36,000 from the outer membranes of potato mitochondria (termed POM 34 and POM 36, respectively). N-terminal sequencing and the use of labeled oligonucleotide mixtures derived from these amino acid sequences allowed the isolation of cDNA clones encoding the 34- and 36-kDa proteins. They have similar steady state protein levels and share about 75% identical amino acids suggesting that they represent isoforms. In addition, a third cDNA clone coding for a slightly different isoform of the 36-kDa protein was characterized. The polypeptides encoded by the three cDNA clones share the highest degree of sequence identity with mitochondrial porins from fungi and mammals. Tentative models of the secondary structure of the 34- and 36-kDa proteins suggest the occurrence of a 16-stranded beta-barrel typical for bacterial and mitochondrial porins. Purification of the 34-kDa protein by hydroxyapatite chromatography allowed conductance measurements in artificial bilayers. The 34-kDa protein is a voltage-dependent, channel-forming component with single channel conductances of 3.5 and 2.0 nanosiemens in 1 M KCl. In spite of the striking functional similarities to mitochondrial porins from other organisms neither the 34- nor the 36-kDa proteins are able to complement the respiratory defect of a yeast por- mutant.

Amino Acid Sequence↗
PubMed1994

Primary structure and expression of a gene encoding the cytosolic ribosomal protein S4 from potato.

The primary structure of a cDNA clone encoding the S4 protein from the small subunit of 80S ribosomes from potato was determined. Cytosolic ribosomal protein S4 is hydrophilic and has a prevalence for positively charged residues. In potato it is 264 amino acids long and contains a putative nuclear targeting signal close to the N-terminus. Having 65-69% identical amino acids cytosolic ribosomal protein S4 from mammals, fungi and plants belongs to the highly conserved proteins. The S4 gene is transcribed in all potato tissues analysed and has a relatively high expression level in comparison to nuclear genes encoding mitochondrial proteins.

Amino Acid Sequence↗
PubMed1994

[Infections caused by Flavobacterium meningosepticum in patients in a neonatal intensive care unit].

During a period of three and a half months 7 neonates from a neonatal intensive care unit became infected by F. meningosepticum, serotype B. The pathogens could be isolated from the tracheal secretions and--less frequently--from throat swabs, gastric juice and nose swabs. Environmental sampling led to the isolation of F. meningosepticum from the humidification fluid of the respirator, from vaporizers as well as from the artificial ventilation tubing. F. mengingosepticum was found in the water of humidifiers from 3 children, who developed neither a colonization nor an infection. In a number of cases the patients' environment was contaminated with F. meningosepticum prior to colinization or infection. Nearly identical resistance patterns against the antibiotics tested, could be demonstrated for the isolated strains. The primary source of infection could not be identified, it is supposed however that the index patient had been admitted to the hospital nine months before. A strict hygienic policy, like consequently performed hand hygiene, adequate processing of ventilation equipment and application of sterile tubings led to extinction of the infections. During subsequent environmental controls, F. meningosepticum could not be isolated.

Anti-Bacterial Agents↗
PubMed1993

[The clinical course and therapy of massive theophylline poisoning].

With suicidal intent a 72-year-old man swallowed 5.8 g aminophylline in a non-retard solution. The theophylline plasma level on admission was 120 mg/l. He had to be intubated when respiratory arrest occurred. Within the first hour he developed cerebral seizures, polymorphous ventricular premature systoles, atrial fibrillation with an irregular ventricular rate and, finally, recurrent episodes of ventricular fibrillation with prolonged circulatory shock (heart rate 120-140/min with a systolic blood pressure of 60 mm Hg for 3 hours) and severe metabolic acidosis (potassium 2.28 mmol/l, phosphate 0.21 mmol/l, pH 7.03, base excess -20.8 mmol/l). He was treated with massive fluid replacement (6.2 l in the first 12 hours), electrolyte substitution to counteract the marked hypokalaemia and hypophosphataemia, repeated defibrillation and antiarrhythmic drugs (lidocaine 240 mg/h and metoprolol twice 5 mg), as well as anticonvulsive treatment (diazepam, 10 mg twice, followed by midazolam 5 mg/h). Detoxication measures consisted initially of gastric lavage followed by high-dosage enteric administration of charcoal (210 g over 36 h), as well as haemoperfusion for 4 h. Full recovery was achieved and the patient was discharged in good health after 3 weeks.

Aged↗
PubMed1992

RNA and DNA binding zinc fingers in Xenopus TFIIIA.

The nine tandem zinc finger repeats in the 5S gene-specific transcription factor IIIA (TFIIIA) from Xenopus mediate specific binding to 5S DNA as well as to 5S ribosomal RNA. A comparative functional analysis of a systematic set of TFIIIA zinc finger combinations reveals that most, if not all, participate in both DNA and RNA binding. Minimal sets of fingers sufficient for DNA and RNA recognition are different. In RNA binding, most finger elements are found to be functionally equivalent. However, the nonessential finger 6 exhibits RNA binding characteristics distinct from the other eight modules. The secondary/tertiary structure of the central domain in 5S RNA, not its primary sequence, is found to carry the essential structural information for TFIIIA binding in Xenopus oocytes. Taken together, our findings suggest that RNA and DNA binding are overlapping, though separable functions of the nine zinc finger elements in TFIIIA, occurring via fundamentally different molecular mechanisms.

Animals↗
PubMed1992

[Eye diseases and visual disability in extremely low birth weight infants].

79 consecutively treated very low birth weight newborns (less than 1000 g) were systematically examined in the postpartal period and after a follow-up of 2 to 5.5 years. Retinopathy of prematurity was found in 19 eyes of 10 children (maximum stage III-IV). At a minimum age of 2 and maximum age of 6 years, when 42 of these children could be reexamined, including all children with earlier retinopathy of prematurity, 10 children suffered from minimal to moderate retinal pathology due to inactive retinopathy of prematurity (4 eyes with dragging of vessels and macula), but 9 children exhibited a minor visual disability due to strabism, higher ametropia, anisometropia, and amblyopia. This stresses the need for opthalmological follow-up in low birth weight babies with 6 months and 3-4 years of age.

Child, Preschool↗
PubMed1991

Delivery of very premature infants: does the caesarean section rate relate to mortality, morbidity, or long-term outcome?

A retrospective analysis of obstetric factors influencing mortality and morbidity of very premature infants (1500 g, less than or equal to 32 weeks' gestation) was undertaken. The study included 275 such infants born in the Department of Obstetrics of the University of Tübingen during the period January 1977 to June 1987. The caesarean section rate of very preterm infants increased from 28% during the period 1977-1982 to 87% during the period 1982-1987 (P less than 0.005), accompanied by an increase in survival rate from 63% to 70%. The improvement in survival rate was statistically significant for the group with birth weight 751-1000 g (P less than 0.01). The overall mortality rate was 31% after caesarean section and 36% after vaginal delivery. Amongst the causes of death of the non-survivors, acidosis was more frequent and amniotic infection syndrome less frequent in the infants delivered vaginally than in those delivered abdominally. The proportion of children with normal development at two years of age was significantly (P less than 0.02) greater amongst those born in 1982-1987 than in those born in 1977-1981. The interpretation of these findings is by no means clear but must include the hypothesis that the increased caesarean section rate may be incidental and in no way related to the improved outcome.

Acidosis↗
PubMed1990

The Xenopus laevis poly(A) binding protein is composed of multiple functionally independent RNA binding domains.

A family of eukaryotic RNA binding proteins is defined by the conserved RNP motif. The poly(A) binding protein has four such motifs. We report on the isolation and structural characterization of several variant cDNA clones, as well as of a gene encoding this protein in Xenopus laevis embryos. Wild-type protein as well as truncated versions carrying isolated single motifs or artificial combinations of two and more such elements were characterized for their ability to bind specifically to RNA homopolymers. Three of the isolated repeats were functional in specific RNA binding, whereas the N-terminal RNP motif was non-functional. Combinatorial effects in RNA binding were measured with constructs carrying multiple repeats, which were not predictable from the activity of isolated domains.

Amino Acid Sequence↗
PubMed1989

Second-order repeats in Xenopus laevis finger proteins.

The primary structure of 342 finger repeats encoded in 42 different cDNA clones isolated from Xenopus laevis oocyte and gastrula cDNA libraries has been determined. Comparative sequence analysis of the predicted protein sequences results in a consensus repeat sequence that has an extended conserved segment of 16 amino acid residues, including the evolutionary conserved H/C link element, connected to a highly variable segment that is located in the finger loop region. Groups of tandem finger repeats are found to be organized in distinct higher-order structural units, with a pair of mutually distinct fingers being the most frequently observed second-order repeat unit. Structural features observed are discussed in respect to existing models for Zn finger structure and function.

Amino Acids↗
PubMed1989

Effect of cesarean section on outcome in high- and low-risk very preterm infants.

The effect of mode of delivery on the survival and morbidity of 24- to 32-week infants (500-1500 g) was studied in 262 consecutive deliveries. The study population was divided into high-risk (e.g., hypertension) and low-risk (e.g., incompetence of the cervix) groups by evaluation of risk factors. 194 very preterm newborn were classified as high risk and 68 as low risk. In both groups the perinatal outcome of vaginal delivery and cesarean section delivery was compared. Cesarean section was associated with a highly significantly improved survival rate in the high-risk group, but was not associated with differences in fetal outcome in the low-risk group. The results of this study do not support primary cesarean section as the method of delivery for all very preterm fetuses.

Adult↗
PubMed1988

Oocyte and somatic 5S ribosomal RNA and 5S RNA encoding genes in Xenopus tropicalis.

We have investigated the structure of oocyte and somatic 5S ribosomal RNA and of 5S RNA encoding genes in Xenopus tropicalis. The sequences of the two 5S RNA families differ in four positions, but only one of these substitutions, a C to U transition in position 79 within the internal control region of the corresponding 5S RNA encoding genes, is a distinguishing characteristic of all Xenopus somatic and oocyte 5S RNAs characterized to date, including those from Xenopus laevis and Xenopus borealis. 5S RNA genes in Xenopus tropicalis are organized in clusters of multiple repeats of a 264 base pair unit; the structural and functional organization of the Xenopus tropicalis oocyte 5S gene is similar to the somatic but distinct from the oocyte 5S DNA in Xenopus laevis and Xenopus borealis. A comparative sequence analysis reveals the presence of a strictly conserved pentamer motif AAAGT in the 5'-flanking region of Xenopus 5S genes which we demonstrate in a separate communication to serve as a binding signal for an upstream stimulatory factor.

Animals↗
PubMed1987

A split binding site for TFIIIC on the Xenopus 5S gene.

We have previously shown that of the two functional domains which constitute the Xenopus 5S gene promoter the common, conserved box A element is directly involved in the binding of the common transcription factor IIIC. Here, we describe the investigation of the role of the 5S gene specific promoter element, box C, in transcription factor binding. Analysis of 22 different single site basepair changes reveals that mutations created within the 5'-region of this segment interfere with transcription due to a reduced affinity for TFIIIA, whereas sequence alterations introduced into the 3'-region of the same element similarly inhibit transcription, but do not result in a measurable defect in TFIIIA binding. Instead, they clearly reduce the affinity for TFIIIC. DNase I protection experiments with TFIIIA on 5S mutants which have an increased spacing of box A and box C demonstrate that TFIIIA recognizes a specific box A sequence element and that the factor has to be properly aligned on the DNA template in order to allow stable complex formation with TFIIIC to proceed. The structural and functional organization of protein binding signals on the 5S gene internal control region will be discussed in regard to these results.

Animals↗
PubMed1986

Improved outcome in very low birth weight infants from 1977 to 1983.

Changes of mortality and neurological morbidity in 351 very low birth-weight infants cared for in the neonatal intensive care unit of the Children's Hospital Tübingen during the years 1977 to 1983 are reported. The main finding was a survival rate increasing from 69.5% in 1977-79 to 76.6% in 1982-83 and a coinciding frequency of severe neurological sequelae decreasing from 9.2%-3.7%. The incidence of minor neurodevelopmental problems remained unchanged. However, mortality after discharge was found to be increased during the period observed. In conclusion, the intensification of neonatal intensive care in our hospital did not only reduce mortality but also the rate of severe neurological sequelae, thus not only survival rate but also the quality of survival could be improved.

Germany, West↗
PubMed1986

Obstetrical and neonatal risk factors in very low birth weight infants related to their neurological development.

An analysis of pre- and perinatal risks in very low birth weight (VLBW) infants showed that children later suffering from severe neurodevelopmental sequelae were exposed to a significantly higher number of risk factors compared to normally developed VLBW controls. This was not only due to a higher incidence of specific risks, but to the accumulation of risk factors, which consequently made an ischaemic or haemorrhagic brain lesion more likely to occur. This result suggests that brain lesions in VLBW infants are essentially multifactorial. The improved outcome of VLBW infants cared for in the NICU of the Children's Hospital of Tübingen during 1977-1983 was accompanied by a decreasing incidence of obstetrical and neonatal risks. This was mainly due to more frequent transport in utero, earlier obstetrical intervention, and immediate postnatal stabilization of the infant's condition. These changes in perinatal care strategy evidently favoured the postnatal course and thus also improved the neurodevelopmental outcome.

Female↗