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Biomedical subjects

B Ludwig

Publications and source records attributed to B Ludwig.

At least 127 records · Page 7Linked to original sources
PubMed1987

The genes of the Paracoccus denitrificans bc1 complex. Nucleotide sequence and homologies between bacterial and mitochondrial subunits.

The genes for the three subunits of the cytochrome bc1 complex from the bacterium Paracoccus denitrificans were identified by screening a gene library constructed in pBR 322 for expression using a cytochrome c1-specific antibody. These three genes coding for the FeS subunit, cytochrome b, and cytochrome c1 were located on contiguous sites on the genome in a presumed operon arrangement. The DNA-deduced amino acid sequence shows that all three subunits are homologous to corresponding polypeptides of the mitochondrial cytochrome bc1 complex. Cytochrome c1 of Paracoccus is much larger than its mitochondrial counterpart due to an extra 150 amino acids of unique, highly acidic composition; in addition, it is most likely synthesized as a precursor polypeptide.

Amino Acid Sequence↗
PubMed1987

Subunit II of cytochrome c oxidase from Paracoccus denitrificans. DNA sequence, gene expression and the protein.

Cytochrome c oxidase from the bacterium Paracoccus denitrificans, while being related to the mitochondrial enzyme in many ways, consists of only two to three different subunits. For the identification of its genes, a Paracoccus DNA library was constructed and screened with specific antibodies for expression of cloned inserts in E. coli. A positive clone expressing immunoreactive products in the molecular mass region of authentic subunit II revealed a high homology of its DNA-deduced amino acid sequence with subunit II sequences of the mitochondrial oxidases; several typical features, such as the transmembrane folding pattern and the presumed copper-binding site, are highly conserved between prokaryotic and mitochondrial polypeptides. A comparison with peptide sequencing data of the purified subunit established the presence of a characteristic N-terminal extension as well as a longer C terminus in the initial translation product of the Paracoccus subunit; by mass spectroscopy, the first N-terminally blocked residue of the mature polypeptide was identified as a pyroglutamate. No code abnormalities, but a highly specific codon usage were observed; no evidence for a localization of the subunit I gene directly adjacent to this gene has been obtained.

Amino Acid Sequence↗
PubMed1987

Neuroradiological aspects of infantile spasms.

With the modern noninvasive brain imaging methods, cerebral lesions of different types and degrees can frequently be determined in infants with West syndrome. In CT examinations preceding the spasms and the ACTH therapy, "idiopathic" forms of infantile spasms were rare. The CT findings consistent with perinatal or postnatal encephalopathy were more frequent than those found with embryonic or fetal lesions alone. The fact that pathognomonic changes cannot be determined, may reflect the low specificity of CT diagnosis in infants with chronic CNS diseases. A slight and mostly transient enlargement of CSF spaces during ACTH therapy is a probable side-effect of the medication. In infants with persistent or progressive enlargement of the CSF spaces, however, this alteration appears to be mainly due to pre-existing brain damage. CT examinations of infants with West syndrome should be performed because prognostic information may be obtained and in a few cases operations to drain CSF may be necessary.

Humans↗
PubMed1987

Nonoptical definition of applanation surface.

Based on the Imbert-Fick law and the theoretical considerations of Goldmann, new applanation tonometers were designed, still using an applanation diameter of 3.06 mm to avoid a new biometric calibration. Three different electronic recording devices were used for the area assessment. An optical, a capacitance and a digital line sensor were tested in first calibration experiments.

Animals↗
PubMed1986

Bilateral lesions of the putamina.

13 cases of bilateral necrosis of the putamina in children and adults are reported. CT shows similar parenchymal defects, though clinical data reveal different histories, causes and circumstances of the damage. The relationship between CT findings and clinical symptoms is investigated, and the neurological dysfunctions resulting from symmetrical areas of necrosis in each putamen are discussed.

Adolescent↗
PubMed1985

The role of subunit III in bovine cytochrome c oxidase. Comparison between native, subunit III-depleted and Paracoccus denitrificans enzymes.

In order to obtain information on the role of subunit III in the function and aggregation state of cytochrome c oxidase, the kinetics of ferrocytochrome c oxidation by the bovine cytochrome c oxidase depleted of its subunit III were studied and compared with those of the oxidase isolated from P. denitrificans which contains only two subunits. The aggregation state of both enzymes dispersed in dodecyl maltoside was also compared. The two-subunit oxidase from P. denitrificans gave linear Eadie-Hofstee plots and the enzyme resulted to be monomeric (Mr = 82 000) both, in gel filtration and sucrose gradient centrifugation studies. The bovine heart subunit III depleted enzyme, under conditions when the P. denitrificans cytochrome c oxidase was in the form of monomers, was found to be dimeric by sucrose gradient centrifugation analysis. At lower enzyme concentrations monomers were, however, detected by gel filtration. Depletion of subunit III was accompanied by the loss of small polypeptides (VIa, VIb and VIIa) and of almost all phospholipid (1-2 molecules were left per molecule of enzyme). The electron-transfer activity of the subunit III-depleted enzyme showed a monophasic Eadie-Hofstee plot, which upon addition of phospholipids became non-linear, similar to that of the control bovine cytochrome c oxidase. One of the roles of subunit III may be that of stabilising the dimers of cytochrome c oxidase. Lack of this subunit and loss of phospholipid is accompanied by a change in the kinetics of electron transfer, which might be the consequence of enzyme monomerisation.

Animals↗
PubMed1985

[Efficiency and efficacy of neuroradiologic diagnosis of brain diseases in childhood].

The younger the child, the more pronounced are the distinctions from adults in brain anatomy, structural changes, and neuropathological symptoms. Ultrasonography can give information about most age-typical conditions when the fontanelles are open. Craniocerebral malformations or tumors should always be shown by computed tomography. Magnetic resonance imaging has above all provided improved diagnostic information about myelination, nonhemorrhagic parenchymal changes, and infratentorial and peribasilar processes. Indications for angiography are limited in general to cases of vascular malformations. Isotope scintigraphy, ventriculography and pneumencephalography are indicated only in exceptional cases.

Brain↗
PubMed1984

[Therapy of the hypertensive crisis with urapidil. Various effects on patients with or without coronary disease].

The effect of urapidil on various hemodynamic and echocardiographic parameters has been investigated in 36 patients with hypertensive emergencies (14 patients with coronary artery disease, 22 patients without coronary artery disease). During treatment with urapidil, blood pressure decreased in both groups by 35%, the heart rate decreased slightly (3-8%). The mean pulmonary artery pressure decreased by 45% (coronary patients) respectively 36% (non-coronary patients), the pulmonary capillary wedge pressure by 59% (coronary patients) resp. 48% (non-coronary patients). Cardiac output increased in both groups by about 20%. In the echocardiogram, both groups showed decreases in the diameters of left atrium and left ventricle, and an increase in the fractional shortening of the left ventricle. Patients with coronary artery disease required less urapidil than non-coronary patients.

Acute Disease↗
PubMed1984

The value of CT in diagnosis and prognosis of different inborn neurodegenerative disorders in childhood.

Inborn errors of metabolism in 40 children have been investigated by computed tomography to obtain data on the degree of cerebral involvement in neurodegenerative and storage disorders: 20 children had various mucopolysaccharidoses, 8 sphingolipidoses , 3 mucolipidoses, 2 oligosaccharidoses , 3 ceroidlipofuscinoses and 4 had various leucodystrophies . Diagnosis in all patients except Alexander's disease was established by biochemical or histological means. The main findings on CT were cerebral atrophy with enlargement of the ventricles and the subarachnoid spaces and hypodensity of the white matter. The degree of cerebral atrophy seemed to develop according to the age of the patients, as could be seen from the patients with mucopolysaccharidosis III, metachromatic leucodystrophy and GM1-gangliosidosis. Hypodensity of the white matter was found in mucopolysaccharidosis I-H, II-B, VI, in mucolipidosis II and in patients with leucodystrophies . On the other hand, there was great variability in these CT findings even in siblings, as seen in four patients with mucopolysaccharidosis VI. Among the series there were several patients who did not show any abnormalities in CT, so that a negative CT did not exclude these disorders, even the leucodystrophies . CT features such as cerebral atrophy or hypodensity were helpful in the evaluation of these disorders, though a diagnosis could not be made by CT alone.

Adolescent↗
PubMed1984

Reno-cerebral oxalosis induced by xylitol.

A 20-year-old man suffering from Crohn's disease developed coma and generalized seizures following ileocecal resection. During postoperative parenteral feeding he received xylitol in an unusually high concentration. CT examinations a few days before death showed intense hypodensity and swelling of brainstem and basal ganglia and increasing triventricular dilatation. Autopsy revealed, mainly in the brainstem and cerebellum, a destruction of intracerebral, intracerebellar and leptomeningeal vessel walls by birefringent crystals (probably calcium oxalate), an early inflammatory reaction and severe brain edema with final tonsillar herniation. The same crystalloid deposits were found in the kidneys.

Adult↗