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Biomedical subjects

U Heim

Publications and source records attributed to U Heim.

At least 19 recordsLinked to original sources
PubMed2001

Amino acid permeases in developing seeds of Vicia faba L.: expression precedes storage protein synthesis and is regulated by amino acid supply.

Full length cDNAs encoding three amino acid permeases were isolated from seed-specific libraries of Vicia faba. The predicted proteins VfAAP1, VfAAP3 and VfAAP4 share up to 66% identity among themselves. Functional characterization of VfAAP1 and VfAAP3 in a yeast mutant showed that these permeases transport a broad range of amino acids. However, VfAAP1 had a preference for cysteine and VfAAP3 for lysine and arginine. VfAAP1 was highly expressed in cotyledons at early developmental stages and moderately in other sink tissues. Its peak of expression in cotyledons corresponded to the appearance of storage protein transcripts, suggesting that this transporter fulfills an important role in providing amino acids for storage protein biosynthesis. VfAAP3 was expressed most abundantly in maternal tissues, that is in roots, stems, gynoecia, pods and seed coats at different developmental stages. VfAAP4 transcripts could not be detected by northern hybridization. In situ hybridization showed that VfAAP1 mRNA is distributed throughout cotyledon storage parenchyma cells, but could not be detected in the abaxial epidermal cell layer. It also accumulate in the chlorenchyma and thin-walled parenchyma cells of seed coats. VfAAP1 mRNA levels were lower in cotyledons cultured in the presence of glutamine, whereas expression of a vicilin storage protein gene was up-regulated under similar conditions. Cysteine repressed the expression of the GUS reporter gene under control of the VfAAP1 promoter, suggesting that this transporter is modulated at the transcriptional level. Regulation of amino acid transport in relation to storage protein accumulation is discussed.

Amino Acid Transport Systems↗
PubMed2000

Antisense-inhibition of ADP-glucose pyrophosphorylase in developing seeds of Vicia narbonensis moderately decreases starch but increases protein content and affects seed maturation.

The small subunit of a Vicia faba ADP-glucose pyrophosphorylase (AGP) cDNA was expressed in antisense orientation in Vicia narbonensis under the control of the seed-specific legumin B4 promoter. From several independent transgenic lines both ADP-glucose pyrophosphorylase AGP-mRNA and AGP enzyme activity were reduced by up to 95% in the cotyledons during the mid- to late-maturation phase. Starch was moderately decreased and sucrose was increased. In two of three lines, transcripts encoding the large subunit of AGP and the storage protein vicilin were increased, whereas legumin B-mRNA was decreased. Transcripts of other storage-associated genes were not altered. The cotyledons contained more protein and total nitrogen. Despite the reduction in starch, total carbon was not decreased and dry weight was unchanged. Compared to the wild type, transgenic seeds contained more water and accumulated dry weight during a longer period, and therefore had a prolonged seed-filling period. Transgenic cotyledon cells of comparable age to the wild type were more highly vacuolated and contained smaller starch grains, indicating a delay in cellular differentiation. We conclude that a specific alteration in carbon metabolism can have pleiotropic effects on water and nitrogen content and induces temporal changes in seed development.

Cotyledon↗
PubMed1999

Phosphoenolpyruvate carboxylase in developing seeds of Vicia faba L.: gene expression and metabolic regulation.

To analyze the role of phosphoenolpyruvate carboxylase (PEPCase, EC 4.1.1.31) during seed development, two cDNA clones encoding two isoforms of PEPCase were isolated from a seed-specific library of Vicia faba. The two sequences (VfPEPCase1 and VfPEPCase2) have a sequence identity of 82 and 89% on the nucleotide and amino acid levels. The VfPEPCase1 mRNA was found to be predominantly expressed in roots and developing cotyledons whereas the VfPEPCase2 mRNA was more abundant in green and maternal tissues. In the cotyledons, PEPCase mRNAs accumulated from early to mid cotyledon stage and decreased thereafter. The PEPCase activity increased continuously during cotyledon development. The enzyme was strongly activated by glucose-6-phosphate, but not by glucose, fructose or sucrose. Asparagine was weakly activating whereas malate, aspartate and glutamate were inhibitory. The inhibitors became less effective with increasing pH. Aspartate was a much stronger inhibitor of cotyledonary PEPCase than glutamate at both pH 7.0 and 7.5. The sensitivity of PEPCase to malate inhibition decreased from early to mid cotyledon stage at a time when storage proteins are synthesized. This indicates activation on the protein level, possibly by protein phosphorylation. Nitrogen starvation in the presence of hexoses but not sucrose decreased mRNA levels of VfPEPCase1 and enzyme activity, indicating control on the mRNA level by both carbon and nitrogen. It is concluded that in developing cotyledons PEPCase is probably important for the synthesis of organic acids to provide carbon skeletons for amino acid synthesis.

Base Sequence↗
PubMed1998

Expression of a yeast-derived invertase in developing cotyledons of Vicia narbonensis alters the carbohydrate state and affects storage functions.

In plants the carbohydrate state provides signals to adjust metabolism to specific physiological conditions. Storage-active sink organs like seeds often contain high levels of sucrose. In order to change the sugar status during seed development a yeast-derived invertase gene was expressed in Vicia narbonensis under control of the LeguminB4 promoter. A signal sequence targeted the invertase to the apoplast in maturing embryos. In the cotyledons, sucrose was decreased whereas hexoses strongly accumulated. There was a major reduction of starch whereas proteins were less affected. Vacuoles of cotyledon cells were enlarged and dry seeds wrinkled. Transcripts and enzyme activity of sucrose synthase, the small and large subunit of ADP-glucose pyrophosphorylase as well as vicilin were downregulated. Sucrose phosphate synthase and legumin-mRNAs were not affected. Analysing single seeds with different sucrose levels revealed a positive correlation of sucrose concentration to mRNA levels of sucrose synthase and most pronounced to ADP-glucose pyrophosphorylase-mRNA levels as well as to starch content. Glucose on the other hand did not show any correlation. After feeding 14C-sucrose in vitro, the invertase-expressing cotyledons partitioned less carbon into starch compared to the wild-type. In the transgenic cotyledons, a relatively higher amount was directed into proteins compared to starch. We conclude that starch accumulation in developing cotyledons could be a function of sucrose concentration. Our results are consistent with a possible sucrose-mediated induction of storage-associated differentiation indicated by upregulation of specific genes of the starch synthesis pathway.

Carbohydrate Metabolism↗
PubMed1998

[Combined fractures of the radius and the ulna at the elbow level in the adult. Analysis of 120 cases after more than 1 year].

PURPOSE OF THE STUDY: The purpose of this study was to increase the knowledge about these rare and serious injuries and to produce guidelines for a more successful ORIF. MATERIAL: 120 cases of combined fractures in adults with late results (minimum one year) stored in the AO Documentation-Center between 1979 and 1989 were analyzed. Monotrauma was dominant, additional injuries were rare. No vasculo-nervous lesions were reported. 15 fractures were open. For the ulna 4 fractures types were isolated, fractures of the coronoid process and the radial head (CR) 25 cases. Olecranon and radial head fracture (OR) 22 cases. Combination of anterior (coronoid) and posterior (olecranon) ulnar fracture with radial head fracture (COR) 41 cases. Metaphyseal ulnar and radial head fractures (MR) 32 cases. For the radial head we have distinguished partial (61) and complete (59) fractures, the latter including 14 neck fractures. RESULTS: In the CR type indirect fixation technique was never perfect. Best results were obtained after ORIF of partial radial fractures. After resection, arthrosis (8/11) and valgus (8/11) were very frequent. In the OR type the stability was restored in simple fractures by the tension band technique even when the radial head was resected. In the severe COR type good results were rare. Arthrosis was important and frequent (36/41) especially after radial head resection. In the MR type ORIF of the radial head combined with ulnar plating gave the best results. Ulnar union was delayed or missing in 13 cases especially after radial head resection. Functional results after one year were better than expected on X-rays. This was due to immediate ORIF (92/120) and early mobilization. There were only 3 infections and 2 reflex-dystrophies. DISCUSSION: The Coronoid is the key-fragment of the ulna. It is best reduced in CR-Type under vision by an anterior approach. In COR-lesions its reduction should be the first step of ulnar ORIF. Comminutions in OR, COR and MR-Types showed a high number of delayed or non union. The reason may be a biological weakness (reduced vascularization) in these areas. Therefore we advocate for bridging plates (and cancellous grafts) for the stabilization of such areas, especially for the metaphysis where a strong valgus force appears after radial resection. Radial head as the lateral pillar of the elbow should be restored by ORIF in partial fractures (excellent results) and even in complete fractures (5/10 excellent results) under favourable conditions. Prosthesis is indicated in severe radial comminution or serious ulnar instability.

Adult↗
PubMed1997

A role for sugar transporters during seed development: molecular characterization of a hexose and a sucrose carrier in fava bean seeds.

To analyze sugar transport processes during seed development of fava bean, we cloned cDNAs encoding one sucrose and one hexose transporter, designated VfSUT1 and VfSTP1, respectively. sugar uptake activity was confirmed after heterologous expression in yeast. Gene expression was studied in relation to seed development. Transcripts were detected in both vegetative and seed tissues. In the embryo, VfSUT1 and VfSTP1 mRNAs were detected only in epidermal cells, but in a different temporal and spatial pattern. VfSTP1 mRNA accumulates during the midcotyledon stage in epidermal cells covering the mitotically active parenchyma, whereas the VfSUT1 transcript was specific to outer epidermal cells showing transfer cell morphology and covering the storage parenchyma. Transfer cells developed at the contact area of the cotyledonary epidermis and the seed coat, starting first at the early cotyledon stage and subsequently spreading to the abaxial region at the late cotyledon stage. Feeding high concentrations of sugars suppressed both VfSUT1 expression and transfer cell differentiation in vitro, suggesting a control by carbohydrate availability.

Carbohydrate Metabolism↗
PubMed1996

Molecular cytogenetic characterisation of the terminal heterochromatic segment of the B-chromosome of rye (Secale cereale).

The terminal heterochromatic segments of the long arms of 20 rye B-chromosomes were isolated by means of laser microdissection technology. Also the remaining portions of the long arms, along with the short arms of the same chromosomes were isolated. Each sample was used for degenerate oligonucleotide primer-polymerase chain reaction (DOP-PCR) amplification reactions. The resulting products were used as probes for chromosome in situ hybridisation experiments, and in Southern hybridisation to digests of 0B and +B DNA. Competition hybridisation of these probes with 0B DNA allowed the detection of B-specific sequences. The terminal heterochromatin of the rye B-chromosome contains both B-specific sequences and sequences also present on the A-chromosomes of rye. The B-specific D1100 family is the major repeat species located in the terminal heterochromatin. Primers designed to the cloned sequence (E1100) were used to search for related low copy sequences in 0B DNA. The sequences of the PCR products revealed no similarities to that of the clone E1100 except for the primer sequences. The possible origin of this sequence is discussed in the context of models for the evolution of the rye B-chromosome.

Base Sequence↗
PubMed1995

Cell-type specific, coordinate expression of two ADP-glucose pyrophosphorylase genes in relation to starch biosynthesis during seed development of Vicia faba L.

Several cDNA clones encoding two different ADP-glucose pyrophosphorylase (AGPase, EC 2.7.7.27) polypeptides denoted VfAGPC and VfAGPP were isolated from a cotyledonary library of Vicia faba L. Both sequences are closely related to AGPase small-subunit sequences from other plants. Whereas mRNA levels of VfAGPP were equally high in developing cotyledons and leaves, the mRNA of VfAGPC was present in considerable amounts only in cotyledons. During development of cotyledons, both mRNAs accumulated until the beginning of the desiccation phase and disappeared afterwards. The increase of AGPase activity in cotyledons during the phase of storage-product synthesis was closely followed by the accumulation of starch. The AGPase activity in crude extracts of cotyledons was insensitive to 3-phosphoglycerate whereas the activity from leaves could be activated more than five-fold. Inorganic phosphate inhibited the enzyme from both tissues but was slightly more effective on the leaf enzyme. There was a correlation at the cellular level between the distribution of VfAGPP and VfAGPC mRNAs and the accumulation of starch, as studied by in-situ hybridisation and by histochemical staining in parallel tissue sections of developing seeds, respectively. During the early phase of seed development (12-15 days after fertilization) VfAGPase mRNA and accumulation of starch were detected transiently in the hypodermal, chlorenchymal and outer parenchymal cell layers of the seed coat but not in the embryo. At 25 days after fertilization both synthesis of VfAGPase mR-NA and biosynthesis of starch had started in parenchyma cells of the inner adaxial zone of the cotyledons. During later stages, the expression of VfAGPase and synthesis of starch extended over most of the cotyledons but were absent from peripheral cells of the abaxial zone, provascular and procalyptral cells.

Amino Acid Sequence↗
PubMed1995

Seed coat-associated invertases of fava bean control both unloading and storage functions: cloning of cDNAs and cell type-specific expression.

We have studied the molecular physiology of photosynthate unloading and partitioning during seed development of fava bean (Vicia faba). During the prestorage phase, high levels of hexoses in the cotyledons and the apoplastic endospermal space are correlated with activity of cell wall-bound invertase in the seed coat. Three cDNAs were cloned. Sequence comparison revealed genes putatively encoding one soluble and two cell wall-bound isoforms of invertase. Expression was studied in different organs and tissues of developing seeds by RNA gel analysis, in situ hybridization, enzyme assay, and enzyme activity staining. One extracellular invertase gene is expressed during the prestorage phase in the thin-walled parenchyma of the seed coat, a region known to be the site of photoassimilate unloading. We propose a model for an invertase-mediated unloading process during early seed development and the regulation of cotyledonary sucrose metabolism. After unloading from the seed coat, sucrose is hydrolyzed by cell wall-bound invertases. Thus, invertase contributes to establish sink strength in young seeds. The resultant hexoses are loaded into the cotyledons and control carbohydrate partitioning via an influence on the sucrose synthase/sucrose-phosphate synthase pathway. The developmentally regulated degradation of the thin-walled parenchyma expressing the invertase apparently initiates the storage phase. This is characterized by a switch to a low sucrose/hexoses ratio. Feeding hexoses to storage-phase cotyledons in vitro increases the sucrose-phosphate synthase/sucrose synthase ratio and changes carbohydrate partitioning in favor of sucrose. Concomitantly, the transcript level of the major storage product legumin B is downregulated.

Base Sequence↗
PubMed1994

The legumin gene family: a reconstructed Vicia faba legumin gene encoding a high-molecular-weight subunit is related to type B genes.

Nucleotide sequence information from a partial genomic clone, a cDNA clone, a RACE clone and a PCR fragment was combined to reconstruct the first reported complete gene sequence encoding a large legumin subunit, designated LelB3. The length difference to the well-characterized major legumin subunits is caused by an extended glutamine/glutamic acid-rich region encoded by the C-terminal part of the alpha chain. Amino acid sequence comparisons reveal that gene LelB3 is more closely related to B-type than to A-type legumin genes of Vicia faba. Gene LelB3 is a member of a small gene family as indicated by published (Pich and Schubert, Biol Zbl 112 (1993); 342-350) and limited own data.

Amino Acid Sequence↗
PubMed1993

A sucrose-synthase gene of Vicia faba L.: expression pattern in developing seeds in relation to starch synthesis and metabolic regulation.

Copy-DNA clones encoding a single class of sucrose-synthase (SUCS; EC 2.4.1.13) subunit have been isolated and sequenced from a Vicia faba L. seed cotyledonary library. Southern analyses indicated the existence of only one gene. Transcript levels determined by Northern blot hybridisation steadily increased until the middle of development [25-35 days after flowering (DAF)] and declined thereafter. Sucrose levels approximately paralleled levels of SUCS mRNA. The activity of SUCS increased with decreasing fructose and glucose concentrations and peaked about 10 d later than mRNA levels. In-vitro culture experiments demonstrated that increasing the sucrose concentration leads to increased levels of SUCS mRNA. The SUCS mRNA was also synthesised in seed-coat tissue, but in lower amounts than in cotyledons and with a different developmental profile. The early peak level of SUCS mRNA (20 DAF) in seed coats coincided with the peak in the amount of sucrose and with a peak of transiently synthesised starch.

Amino Acid Sequence↗
PubMed1993

[Malleolar fractures with ankle joint instability--experience with the positioning screw].

UNLABELLED: Malleolar fractures with an unstable ankle joint require additional stabilization. Different implants exist: We present the results of 135/155 patients treated with the so-called positioning screw. In 123 patients the positioning screw showed a spontaneous loosening with functional treatment and was therefore removed with the rest of the implants after eight to twelve months. In twelve cases the screw was broken. In 3/21 patients with the old 3.5 mm cortical screw with a core diameter of 1.9 mm in a correct position and in 9/113 patients with the new 3.5 mm cortical screw with inner core of 2.4 mm in an incorrect position. CONCLUSION: Positioning screws require early removal only if they fail to loosen or if a persistent limitation of dorsiflexion is still present after three months.

Adult↗
PubMed1992

[Surgical treatment of radial head fracture].

Fractures of the radial head are often combined with ligament ruptures or subluxations creating instability of the elbow joint. Cartilage avulsions of the capitellum trapped between the fragments are a frequent observation. We advocate ORIF for displaced fractures. The posterolateral approach avoiding compression of the radial nerve may be prolonged proximally with an osteotomy of the humeral epicondyle giving full overview of the circumference of the head. It allows the harvesting of cancellous bone used as a graft to fill in articular depressed areas or metaphyseal defects. The stabilisation is achieved with thin screws of 1.5 mm diameter introduced in different planes, their head slightly sunken in the cartilage. Lately miniplates have been used in cases of neck fractures with surprisingly good functional results. The author reports about the results in 42 of 49 operated patients.

Bone Screws↗
PubMed1991

[Incidence of antibodies to Borrelia burgdorferi in dogs in small animal practice in North Bavaria].

With help of indirect immunofluorescent assay antibodies were detected to Borrelia burgdorferi, agent of Lyme borreliosis in 46 (35.5%) serum samples of 130 randomly selected dogs of a small animal practice in Northern Bavaria. A positive reaction of the indirect immunofluorescent assay was demonstrated in 15 cases in a serum dilution of 1:64, in 9 cases in a serum dilution of 1:128, in 5 cases in a serum dilution of 1:256, in 2 cases in a serum dilution of 1:512, in 3 cases in a serum dilution of 1:1024, in 2 cases in a serum dilution of 1:2048 and in 10 cases in a serum dilution of 1:4096 and higher. There was significant correlation between the symptoms pain of segments or muscles in dorsal region, between painful arthritis, between paralysis of hind legs or between chronic erythema ("hot spot") and the positive reaction of the immunofluorescent assay in the serum dilution of 1:256 ("borderline titre") and higher.

Animals↗
PubMed1990

[Role of the fibula in distal tibial fracture].

Analysing 1077 fractures of the distal segment of the tibia the author found specific morphologies of the accompanying fibula fractures when axial dislocations exist. In valgus position compression and bending forces induce multifragmentary fractures of the diaphysis or impactions of the metaphysis. In varus position bending and traction forces create simple oblique or transverse fractures. The ligaments of the syndesmosis are rarely ruptured when the fibula is fractured. They may remain undamaged when the fibula is intact. Ruptures of the fibulotalar and fibulocalcanear ligaments are not uncommon. The internal fixation of the fibula remains the first step of the AO-tactics for the operative treatment of Pilon-tibial fractures. The initial axial position must be respected. In valgus cases there will be postoperative compression forces (pillar function), in varus cases traction forces (tension band function) acting on the repaired fibula. Indirect reduction techniques ought to be used for complex fibula fractures.

Ankle Injuries↗
PubMed1990

[Peritendinitis calcarea of the hand, a case report].

The authors present three cases of peritendinitis calcarea in the extensor tendons of the wrist and the flexor tendons of the fingers. The symptoms were gout-like pain attacks and local inflammation. In the X-rays calcification was seen within the tendon sheath. The symptoms and the calcification disappeared spontaneously in a few months. In these rare cases there is no indication for surgery.

Adult↗