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Biomedical subjects

I Schmidt

Publications and source records attributed to I Schmidt.

At least 73 records · Page 4Linked to original sources
PubMed1995

[Goiter incidence in Germany is greater than previously suspected].

BACKGROUND: The data regarding goitre prevalence in Germany is based on calculation arising out of dissimilar studies conducted among inhomogeneous study groups. The aim of our study was to collect data towards prevalence of goitre, thyroid size and structure through a prospective nationwide survey conducted using identical examination methods and study protocol. PATIENTS AND METHOD: A total number of 6815 subjects belonging to various age groups and spread over 32 regions in Germany participated in our thyroid ultrasound study conducted with a 7.5 MHz transducer. Information regarding nutrition, use of iodised table salt and iodine containing medicine and/or substances were collected through a questionnaire. The volumetry and age related normal values were followed as per the guidelines set by Deutsche Gesellschaft für Endokrinologie. RESULTS: Enlarged thyroid was seen in 50% of 18 to 70 year age group, 52% of 11 to 17 year age group and in 21% of children up to 10 years. Focal lesions were detected in 2.5% of subjects below 18 years and in 30% of women and 21% of men over 18 years. A positive correlation between age, thyroid volume and number of thyroid nodules was seen. Up to 83% of the examined subjects admitted to using iodised table salt. Children consuming iodised salt were found to have smaller thyroid glands. No correlation was found between the consumption of iodised salt and thyroid size in the adolescent age group and young adults. CONCLUSION: The prevalence of goitre in Germany is higher than it has been reported. The study underlines the insufficiency of the present goitre prophylaxis. Only an iodine prophylaxis (table salt, food products, fodder) backed by legislative measures can bring about a real breakthrough.

Adolescent↗
PubMed1995

Localization and organization of phenol degradation genes of Pseudomonas putida strain H.

The genetic organization of the DNA region encoding the phenol degradation pathway of Pseudomonas putida H has been investigated. This strain can utilize phenol or some of its methylated derivatives as its sole source of carbon and energy. The first step in this process is the conversion of phenol into catechol. Catechol is then further metabolized via the meta-cleavage pathway into TCA cycle intermediates. Genes encoding these enzymes are clustered on the plasmid pPGH1. A region of contiguous DNA spanning about 16 kb contains all of the genetic information necessary for inducible phenol degradation. The analysis of mutants generated by insertion of transposons and cassettes indicates that all of the catabolic genes are contained in a single operon. This codes for a multicomponent phenol hydroxylase and meta-cleavage pathway enzymes. Catabolic genes are subject to positive control by the gene product(s) of a second locus.

Amino Acid Sequence↗
PubMed1995

Pronounced juvenile circadian core temperature rhythms exist in several strains of rats but not in rabbits.

Torpor-like circadian variations of core temperature are well documented for suckling-age Zucker rat pups. To determine (1) whether this juvenile circadian rhythm is as strongly expressed in other rat strains, and (2) whether a similar rhythm is expressed in rabbit pups, we recorded core temperature and metabolic rate of artificially reared pups. Wistar, Brown Norway, and Long Evans pups were studied for 30 h under moderate cold loads (ambient temperature = 28 degrees C) when 9-11 days old, i.e. at the age and ambient temperature for which the rhythm has been most thoroughly characterized in Zucker rats. Chinchilla bastard rabbit pups were studied under similar conditions when they were 3-8 days old, the youngest age at which the rhythm can be easily detected in rats. Rat pups of each strain showed clear circadian rhythms with sharp decreases of core temperature and metabolic rate in subjective morning. Core temperature amplitudes were in the order Wistar < Brown Norway < Zucker < Long Evans strain. In contrast, the rabbit pups maintained stable high levels of core temperature and metabolic rate throughout the day. A torpor-like decrease of core temperature in the morning is thus not a peculiarity of the Zucker rat strain but also occurs in other pigmented rat strains, whereas rabbit pups at a similar developmental stage do not show a circadian core temperature rhythm.

Animals↗
PubMed1995

[Muscle incoordination phenomena after surgical management of proximal rupture of the biceps tendon].

A significant atrophy of the biceps brachii muscle without decreasing maximal force during flexion in the elbow joint was shown at least 1.5 years after surgical refixation in 6 patients with a tendon-rupture of the long head of the right biceps. A decreased myoelectrical activity was found in the caput longum region of the muscle. The decrease correlates with an increase of spectral myoelectrical power in the region of caput breve or brachioradialis muscle. In addition compensatory recruitment processes can be supposed because of changed spectral myoelectrical power in the low-frequency bands. Changes of the morphological structure of the muscle were only found in 1 patient by sonography.

Arm Injuries↗
PubMed1995

Juvenile circadian core temperature rhythm in Wistar and lean (Fa/-) Zucker rat pups.

We compared the daily rhythms of cold defense in Wistar and lean (Fa/-) Zucker rat pups isolated from maternal care. Pups, born in a colony with lights-on from 7:00 to 19:00, were artificially reared from 10 to 13 days of age in continuous light at moderate cold loads, while we recorded core temperature (Tc) and metabolic rate (MR). Pups of both strains showed daily rhythms distinctly different from those of adult rats: on the first day of artificial rearing Tc steeply decreased shortly before the time of lights-on in the breeding colony and reached a daily minimum of 31.8 +/- 0.4 degree C at 7:17 +/- 17 min in Zucker pups (+/- SE, N = 24) and of 33.4 +/- 0.2 degree C at 8:59 +/- 9 min (N = 25) in Wistar pups. On each day, the average daily minimum Tc was significantly higher in Wistar than in Zucker rats, whereas the daily maximum Tc were close to 36 degrees C in both strains. The daily rhythms of MR resembled those of Tc. We conclude that circadian differences of cold defense, which must be expected to influence a variety of behavioral and physiological parameters, are not a peculiarity of Zucker rat pups but also occur, though with a smaller amplitude, in 10-day-old Wistar pups.

Animals↗
PubMed1995

Reliability of individual diagnostic criterion items for psychoactive substance dependence and the impact on diagnosis.

OBJECTIVE: Reliability of diagnostic criterion items for psychoactive substance dependence and the impact of each on the reliability of the diagnosis were analyzed. METHOD: As part of a reliability study for a new interview developed for the multisite Collaborative Study on the Genetics of Alcoholism (COGA), data were collected from both within-center and across centers. The impact of each diagnostic item on the reliability of the substance dependence diagnosis was studied by forcing each item to be reliable one at a time and recomputing the kappa statistic for the diagnosis. RESULTS: Findings indicated that the majority of individual diagnostic criterion items were reliable; 87% and 81% were in the fair or better range of reliability for the within- and cross-center studies, respectively. Individual kappa estimates were statistically similar for the two studies. Reliability findings for two classes of substance, alcohol and cocaine, were good, while those for stimulants were less satisfactory. CONCLUSIONS: Forcing items one at a time to be reliable did not affect reliability of the overall substance dependence diagnosis, because more than one criterion item changed from Time 1 to Time 2. Because no single item was influential, weighting criteria equally, as is done in the DSM and ICD classification systems, appears to be a reasonable approach.

Adolescent↗
PubMed1995

[Principles of osteosynthesis of the hand].

In cases of joint fractures as well as in dislocated and open fractures of the hand special standards concerning operation methods have to be set. Treatment of soft tissue damage accompanying the fracture is in no other region of the body so important. Therefore the current efforts for development of an AO-classification for fractures of the hand taking into account the soft tissue damage are of major significance. Special features of miniosteosynthesis compared to conventional osteosynthesis are the subject of this study. The use of the miniplate especially in juxtaarticular fractures of the hand due to complex injuries or replantations can overcome the disadvantages of joint-bridging K-wires. Osteosyntheses of the hand are making high technical demands on surgeons and are not at all operations for beginners.

Bone Plates↗
PubMed1995

[Indications for a new joint-bridging miniature external fixator in primary and secondary management of complex hand injuries].

25 patients with injuries of the hand were treated by a new external minifixator. A specific joint bridging construction makes it possible to treat severe joint fractures by ligamentotaxis. Another indication is the preoperative continuous elongation treatment in severe contractures of the fingers. The minifixator can be made dynamic and can also be used for interfragmental compression or distraction.

Adult↗
PubMed1994

The thylakoid translocation of subunit 3 of photosystem I, the psaF gene product, depends on a bipartite transit peptide and proceeds along an azide-sensitive pathway.

Subunit 3 of photosystem I (PSI-3), the product of the nuclear psaF gene, is the docking protein for plastocyanin during photosynthetic electron transport in thylakoid membranes and is synthesized in the cytosol with a transit peptide that resembles structurally the bipartite targeting signals of hydrophilic, lumenal components such as plastocyanin. In organello import experiments performed with the authentic PSI-3 precursor and chimeric polypeptides consisting of residue-correct fusions of transit peptides and mature proteins derived from different plastid proteins demonstrate that the PSI-3 transit peptide is indeed capable of translocating proteins into the thylakoid lumen and that, conversely, mature PSI-3 depends on a bipartite transit peptide for its thylakoid transfer. Of the three recently described translocation/integration pathways for nucleus-encoded proteins carrying bipartite transit peptides that are distinct in their physiological requirements and strictly protein-specific, PSI-3, like plastocyanin and the 33-kDa protein of the oxygen-evolving complex, is translocated by a pathway that involves stromal factors but no proton gradient across the membrane. It is not affected by saturating amounts of the precursor for the 23-kDa protein of the oxygen-evolving complex that follows the latter route. Thylakoid translocation of PSI-3 is, however, impaired in the presence of sodium azide, which indicates that a homolog to the bacterial SecA protein might be involved in this process suggesting, thus, a prokaryote-like translocation pathway. The azide-sensitive factor appears to interact predominantly with the transit peptide of a precursor protein, since chimeras consisting of a presequence from an azide-resistant precursor and a mature part of an azide-sensitive polypeptide are still translocated in the presence of the inhibitor.

Azides↗
PubMed1994

Interaction between the aphid transmission factor and virus particles is a part of the molecular mechanism of cauliflower mosaic virus aphid transmission.

Cauliflower mosaic virus (CaMV) aphid transmission factor (ATF or P18) is presumed to interact with both virus particles and vector mouthparts, thereby mediating virus aphid transmission. We developed a protein-protein binding assay and our results clearly show that virus particles bind strongly and specifically to P18 whether P18 was obtained from plants, a baculovirus expression system, or the pGEX-3X Escherichia coli expression system. We overproduced, using the pGEX-3X expression system, various fragments of P18 and thereby demonstrated that the C-terminal 31 amino acid residues are responsible for the interaction. Using PCR-based mutagenesis, 2 amino acid residues essential for interaction were identified. Point substitutions (amino acids 157 from Ile to Asn or 159 from Gly to Ser) were sufficient to abolish the interaction, whereas another mutation (amino acid 158 from Ile to Ser) had no effect on P18 virus binding. We evaluated whether there was a correlation between the ability of P18 to interact with CaMV particles and its biological activity. Aphid transmission assays were carried out and we demonstrated that the loss of the virus binding capacity had a dramatic effect on the ability of P18 to mediate aphid transmission. Thus, our results suggest that binding between P18 and virus particles is likely to be one of the molecular mechanisms involved in CaMV aphid transmission.

Animals↗
PubMed1994

The presequence of a chimeric construct dictates which of two mechanisms are utilized for translocation across the thylakoid membrane: evidence for the existence of two distinct translocation systems.

The translocation of plastocyanin across the thylakoid membrane in Pisum sativum has been studied in reconstitution assays and using chimeric constructs. The reconstitution assays demonstrate that plastocyanin translocation is absolutely dependent on the presence of a stromal factor(s) and nucleotide triphosphates (NTPs), whereas neither element is required for the translocation of the 23 or 16 kDa proteins of the oxygen-evolving complex. Previous studies had revealed that the transthylakoidal delta pH is essential for translocation of the 23 and 16 kDa proteins but unnecessary for plastocyanin translocation. The basis for these mechanistic differences has been tested by analysing the translocation of a chimeric construct consisting of the presequence of the 23 kDa protein linked to the mature plastocyanin sequence. This construct is efficiently imported into thylakoids in the absence of stromal extracts or NTPs and translocation across the thylakoid membrane within intact chloroplasts is totally inhibited by the uncoupler nigericin: the translocation requirements are thus identical to those of the pre-23 kDa protein and diametrically opposite to those of pre-plastocyanin. Transport across the thylakoid membrane of a second fusion protein, consisting of the presequence of the 16 kDa protein linked to mature plastocyanin, is also dependent on a delta pH. The data suggest that two distinct systems are involved in the translocation of proteins across the thylakoid membrane, with each system recognizing specific signals within the presequences of a subset of lumenal protein precursors.

Amino Acid Sequence↗
PubMed1994

Is the circadian core temperature rhythm of juvenile rats due to a periodic blockade of thermoregulatory thermogenesis?

Previous studies have demonstrated an endogenous circadian rhythm of core temperature (Tc) in suckling-age rat pups. Our aim was to establish whether the low and irregular Tc at the beginning of the light phase is caused by a temporary blockade of thermoregulatory thermogenesis. We therefore isolated and artificially fed 10-day-old pups for 30 h at five ambient temperatures (Ta), ranging from thermoneutrality to severe cold loading, while continuously recording Tc and metabolic rate (MR). During the maximum phase of the Tc rhythm MR increased linearly with decreasing Ta--to as much as 260% of the daily mean MR at thermoneutrality (TNMR)--so that Tc decreased less than 1 degree C with increasing cold load. During the minimum phase, the MR at all but the lowest Ta fell to, or even below, the TNMR and the amplitude of the Tc rhythm increased from 2 to 5 degrees C with increasing cold load. Under the most severe cold load, however, a further decrease of the minimum Tc was prevented by an increase of MR to 135% of the TNMR. Supplementing the continuously fed synthetic milk with noradrenaline (1.2 mg kg-1 h-1) during the minimum phase of the Tc rhythm increased MR upto 290% of the TNMR. The loose regulation of Tc during the minimum phase of the juvenile circadian Tc rhythm is thus not caused by a peripheral impairment of thermogenic capacity at the beginning of the light phase.

Animals↗
PubMed1994

Sympathetically and nonsympathetically mediated onset of excess fat deposition in Zucker rats.

To evaluate whether a low sympathetic activity is essential for the onset of Zucker rat obesity, we artificially reared fa/fa and Fa/fa littermates from 4 days of age with identical amounts of milk containing norepinephrine (NE). The NE concentration was adjusted to keep the mass-specific metabolic rate (MR) roughly either 100 or 50% above its thermoneutral level. At both doses, no genotype difference in total MR occurred before day 16, but between 16 and 21 days of age, total MR of fa/fa pups was 10% less than that of their Fa/fa littermates. The 21-day-old fa/fa pups had approximately 1 g more body fat than their lean littermates, and this was energetically accounted for to 50-80% by their lower MR and to 10-25% by the reduced growth of their fat-free dry mass. We conclude that factors not dependent on decreased sympathetic outflow trigger the onset of excess fat deposition in the 3rd postnatal wk, even if sympathetic activity was high throughout the previous weeks during which excessive fat deposition is mainly dependent on decreased thermoregulatory thermogenesis.

Animals↗
PubMed1994

A new, semi-structured psychiatric interview for use in genetic linkage studies: a report on the reliability of the SSAGA.

Within- and cross-center test-retest studies were conducted to study the reliability of a new, semistructured, comprehensive, polydiagnostic psychiatric interview being used in a multisite genetic linkage study of alcoholism. Findings from both studies indicated that reliability for the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) was high for DSM-III-R substance dependence disorders, but less so for substance abuse disorders. Reliability of depression was good in both studies, but mixed for antisocial personality disorder (ASP). Findings are presented in terms of specific substance dependence and abuse diagnoses, as well as for depression and ASP. Criterion-specific reliabilities are examined by type of substance used. Although SSAGA was designed to provide for broad phenotyping of alcoholism, review of its new features suggests its suitability for a variety of family studies, not just those focusing on substance abuse.

Adolescent↗
PubMed1993

Paracrystalline structure of cauliflower mosaic virus aphid transmission factor produced both in plants and in a heterologous system and relationship with a solubilized active form.

Cauliflower mosaic virus (CaMV) aphid transmission factor (ATF), produced in a baculovirus expression system, forms paracrystalline structures, as demonstrated by electron microscopic observations. Similar paracrystals were also found in CaMV-infected plants, using immunogold techniques, thus providing the first evidence of such a structure for the CaMV ATF (P18). We demonstrated that the paracrystals can be solubilized to provide an active form of the CaMV ATF which can also be reverted into the paracrystalline aggregated form. This suggests that the paracrystalline structures might act as a source of active CaMV ATF or be the form in which it is stored within the infected cells. A point mutation within the CaMV gene II (which encodes the ATF) leads to the loss of both the paracrystalline structures and the ATF activity. Hence, the paracrystalline structure seems to be a feature of the native (unmodified ) CaMV ATF.

Animals↗