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Biomedical subjects

K H Hoffmann

Publications and source records attributed to K H Hoffmann.

At least 19 recordsLinked to original sources
PubMed2005

Isolation of precursor cells (PCs) from human dental follicle of wisdom teeth.

The dental follicle is an ectomesenchymal tissue surrounding the developing tooth germ. It is believed that this tissue contains stem cells and lineage committed progenitor cells or precursor cells (PCs) for cementoblasts, periodontal ligament cells, and osteoblasts. In this study, we report the isolation of PCs derived from dental follicle of human third molar teeth. These fibroblast-like, colony forming and plastic adherent cells expressed putative stem cell markers Notch-1 and Nestin. We compared gene expressions of PCs, human mesenchymal stem cells (hMSCs), periodontal ligament cells (PDL-cells) and osteoblasts (MG63) for delimitation of PCs. Interestingly, PCs expressed higher amounts of insulin-like growth factor-2 (IGF-2) transcripts than hMSCs. Differentiation capacity was demonstrated under in vitro conditions for PCs. Long-term cultures with dexamethasone produced compact calcified nodules or appeared as plain membrane structures of different dimensions consisting of a connective tissue like matrix encapsulated by a mesothelium-like cellular structure. PCs differentially express osteocalcin (OCN) and bone sialoprotein (BS) after transplantation in immunocompromised mice but without any sign of cementum or bone formation. Therefore, our results demonstrate that cultured PCs are unique undifferentiated lineage committed cells residing in the periodontium prior or during tooth eruption.

Adolescent↗
PubMed2005

[Monoaminergic transmitters in the cerebrospinal fluid of patients with acute, chronic, and intermittent pain. Interface between pain and depression?].

BACKGROUND AND STUDY PURPOSE: Pain and depression share similar neurobiological characteristics, and it is a common clinical observation that pain and depression may coincide in the same patient. They also appear to influence each other in the process of chronification. Furthermore, there is a complex coupling of pain and depression by monoaminergic transmitter system. PATIENTS AND METHODS: On the basis of these findings, norepinephrine (NE), epinephrine (E), dopamine (DOP), 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and vanillylmandelic acid (VMA) concentrations were determined in the cerebrospinal fluid (CSF) in patients with acute (20), chronic (27), and episodic pain syndrome (44) in a prospective study. The biochemical parameters were correlated to self-assessment pain and depression scores. The control group consisted of 13 pain-free patients with diseases affecting the muscular system. RESULTS: Patients with chronic and episodic pain syndromes had significantly more depressive and psychovegetative symptoms compared to patients with acute pain. In patients with acute pain, DOP was significantly higher than in controls and chronic and episodic pain patients. In addition DOP was positively correlated to self-assessment pain score (p*<0.05). In patients with chronic and episodic pain, NE and 5-HIAA were positively correlated to the duration of disease and were significantly lower than in the control group. In neither of these two groups could significant correlations be established between these parameters and pain or depression self-assessment scores. In all groups, positive correlations were seen between the neurotransmitter and their metabolites. CONCLUSION: The pathological decrease of NE and 5-HIAA in the CSF points to the crucial role of noradrenergic and serotonergic transmitter systems in the generation, modulation, and perpetuation of chronic and episodic pain syndromes. It indicates that antidepressants are effective drugs in these diseases. However, a discriminative neurochemical pattern between pain and depression could not be established. The demonstration of polyvalent correlations between different neurotransmitters is indicative of complex neurobiological coupling between cortical, limbic, and hypothalamic neuronal networks on the one hand and the nociceptive descending system on the other hand in the genesis of pain and depression.

Acute Disease↗
PubMed2005

In vitro differentiation of human dental follicle cells with dexamethasone and insulin.

The dental follicle is an ectomesenchymally derived connective tissue harboring precursor cells for the tooth supporting apparatus. In this study, we examined gene expression of freshly isolated human dental follicle cells during osteogenic differentiation in vitro. These plastic adherent fibroblastic cells express Notch-1, nestin and vimentin. We differentiated dental follicle cells with dexamethasone or insulin-based protocols into membrane-like structures containing mineralizing foci. An analysis of mineralized tissue with atomic force microscopy illustrated a bone and cementum-like structure. A real-time RT-PCR analysis was developed to investigate expression of typical osteoblast or cementoblast related genes during differentiation. Gene expressions of osteocalcin (OCN), bone morphogenic protein (BMP)-2 and nestin were increased during the both differentiation approaches. Our work demonstrates differentiation of dental follicle cells with an insulin-based protocol for the first time.

Adult↗
PubMed2004

Cloning and tissue-specific localization of cricket-type allatostatins from Gryllus bimaculatus.

Cricket- or B-type allatostatins [W(X(6))W-amides] inhibit the biosynthesis of juvenile hormones in vitro in crickets. Peptides of this family are present also in other insects where they may bare different functions. Here we report the identification of a partial sequence of the B-type preproallatostatin from Gryllus bimaculatus. By PCR screening of a random primer cDNA library and by RACE, a 535bp 3'cDNA sequence was obtained which encodes a putative translation product of 85 amino acids, containing three copies of Grybi-AST B1 and one copy each of Grybi-AST B2, Grybi-AST B3, and Grybi-AST B6. The last represents a novel member of this peptide family. By means of one-step RT-PCR, RNA dot blot, and RT in situ PCR analyses the mRNA expression of the gene in the central nervous system and the digestive tract of female adult crickets was demonstrated. The results confirm that the B-type allatostatins of G. bimaculatus are brain-gut peptides.

Amino Acid Sequence↗
PubMed2003

Molecular characterisation of cDNAs from the fall armyworm Spodoptera frugiperda encoding Manduca sexta allatotropin and allatostatin preprohormone peptides.

Allatotropin (AT) is a 13-residue amidated neuropeptide, first isolated from pharate adult heads of the tobacco hornworm, Manduca sexta (Manse-AT), which strongly stimulates the biosynthesis of juvenile hormones (JH) in the corpora allata (CA) of adult moths. In Spodoptera frugiperda, a cDNA that encodes 134 amino acids, including an AT peptide, has been cloned. The S. frugiperda allatotropin mature peptide (Spofr-AT) [GFKNVEMMTARGFa] is identical to that isolated from M. sexta. The basic organization of the Spofr-AT precursor is similar to that of Agrius convolvuli, M. sexta, Pseudaletia unipuncta, and Bombyx mori with 83-93% amino acid sequence identity. The Spofr-AT gene is expressed in at least three mRNA isoforms with 134, 171 and 200 amino acids, differing from each other by alternative splicing. All allatostatins (AS) have an inhibitory action on the JH biosynthesis in the CA. A cDNA that encodes 125 amino acid residues including one copy of the Manse-AS peptide has been cloned from S. frugiperda (Spofr-AS; QVRFRQCYFNPISCF). The basic organization of the Spofr-AS precursor is similar to that of P. unipuncta with 85% amino acid sequence identity. Using one step RT-PCR for semi-quantification of the gene expression, we showed that the three mRNAs of the Spofr-AT gene and the Spofr-AS gene are expressed in brains of last instar larvae, prepupae, pupae, and adults of both sexes of S. frugiperda with variable intensity.

Amino Acid Sequence↗
PubMed2003

Expression of allatostatins in the Mediterranean field cricket, Gryllus bimaculatus de Geer (Ensifera, Gryllidae).

The allatostatin (AST) type A gene of the cricket Gryllus bimaculatus encodes a hormone precursor including at least 14 putative peptides with a common C-terminus Y/FXFGL/Iamide. By RT-PCR we have analyzed the expression of the allatostatin precursor in various tissues of 0-21 days old adult virgin and mated females. In 3-day-old virgin females, the gene is strongly expressed in the brain (oesophageal ganglion), the suboesophageal ganglion and the caecum, but to a lower extent in other parts of the digestive tract (ileum, midgut, colon), and in various other tissues such as the fat body, ovaries and female accessory reproductive glands. In the brain and ovaries of virgin females, the AST expression is rather constant throughout adult life, whereas in brains of mated animals, expression is low until day 7, but increases sharply from day 8 onwards to reach values triple those before day 7. In ovaries of mated animals AST gene expression is also age-dependent, with high expression rates during the first 4 days after imaginable moult, a second but smaller peak from day 15 to 21, and very low values in between. In the fat body of virgin crickets allatostatin expression is high during the first 9 days after ecdysis and declines thereafter, whereas in mated animals two peak values, day 1 and day 6, are observed, and a third peak in older animals.

Aging↗
PubMed2001

The allatostatin gene of the cricket Gryllus bimaculatus (Ensifera, Gryllidae).

The gene encoding allatostatins (AST) of the FGLamide family from the cricket Gryllus bimaculatus is expressed in the brain. The mRNA, which contains four polyadenylation signals, encodes a hormone precursor that is split into at least 14 putative hormones. Five of them have been previously found in the cricket, six to seven others, or their close homologues, are known from other insects. Hormone AST 2 contains an internal cleavage site and may exist in a shorter version 2b. The hormones AST 3 and 4 are identical. The cDNA sequence revealed that a single point mutation and a single deletion eliminated an additional hormone between AST 12 and 13. The deduced hormone precursor is very similar to that in cockroaches, but is different from a shorter precursor in locusts, indicating that the gene evolved very fast in the latter. Regions conserved between cockroaches and crickets include parts of the acidic spacers that separate clusters of hormones, suggesting that these spacers may have additional functions.

Animals↗
PubMed2001

Best possible strategy for finding ground states.

Finding the ground state of a system with a complex energy landscape is important for many physical problems including protein folding, spin glasses, chemical clusters, and neural networks. Such problems are usually solved by heuristic search methods whose efficacy is judged by empirical performance on selected examples. We present a proof that, within the large class of algorithms that simulate a random walk on the landscape, threshold accepting is the best possible strategy. In particular, it can perform better than simulated annealing and Tsallis statistics. Our proof is the first example of a provably optimal strategy in this area.

Algorithms↗
PubMed2001

[Stress analysis of the human mandible in standard trauma situations with numerical simulation].

For the stress analysis of the human mandible a flexible simulation concept basing on finite element-method has been developed. One of the main issues is the prediction of fractures as a consequence of known forces as well as the forensic reconstruction of the traumatologic situation. At first, the individual geometry was reconstructed by 3D-CT-Scans. To reduce the simulation efforts, for the time being the anisotropic structural mechanics of the jaw bone was neglected in favour of an homogeneous and isotropic material law. Assuming the Von-Mises-Stress as a failure indicator the results of the simulations were in good agreement with typical traumatologic situations. For further validation of the model, a real failure case, shown on a radiograph of a injured human mandible with three fractures, was simulated and, by this, the real incident was reconstructed. Reasonable planned extensions of the actual simulation concept have the regard on the nerve channel, the temporomandibular joint's function, the paradontal apparatus and the individual mechanical properties of the bone.

Biomechanical Phenomena↗
PubMed2000

Structure elucidation and biological activity of an unusual adipokinetic hormone from corpora cardiaca of the butterfly, Vanessa cardui.

A structurally unusual member of the adipokinetic hormone/red pigment-concentrating hormone peptide family was isolated from corpora cardiaca of the painted lady butterfly, Vanessa cardui. Its primary structure was assigned by Edman degradation and nano-electrospray-time-of-flight mass spectrometry as pQLTFTSSWGGK (Vac-AKH). Vac-AKH represents the first 11mer and the first nonamidated peptide in this family. The peptide shows significant adipokinetic activity in adult specimens of V. cardui. Injection of 10 pmol of synthetic Vac-AKH into 4-day-old decapitated males resulted in an approximately 150% increase of hemolymph lipids after 90 min. Half maximal adipokinetic activity was achieved with about 0. 1 pmol of Vac-AKH. During a 2-h incubation of corpora cardiaca/corpora allata complexes in medium containing 50 mM KCl, significant amounts of Vac-AKH were released from the glands.

Amino Acid Sequence↗
PubMed2000

[A modular software concept for individual numerical simulation (FEM) of the human mandible].

A new modular software concept for individual numerical simulation of the human mandible using the finite element method (FEM) is presented. The main task is an individual analysis of regional stress and stress-compatibility on the basis of computed tomographic data in individual patients. Simulation should, however, also be possible in parallel with biomechanical experiments, or for further research projects. For this purpose, rapid and uncomplicated generation of the FEM model, easy modification of input data, and short computation times are required. Practical use in the clinical setting makes appreciable additional demands on the individual software components.

Biomechanical Phenomena↗
PubMed1997

Cerebrospinal fluid neuropeptides and monoaminergic transmitters in patients with trigeminal neuralgia.

The pathogenesis of trigeminal neuralgia remains largely unknown. "Peripheral" as well as "central" causes have been suggested. To investigate the role of serotonergic, noradrenergic, dopaminergic, and peptidergic systems, we determined the concentrations of epinephrine, norepinephrine, and their breakdown product, vanillylmandelic acid, in the cerebrospinal fluid of 16 patients (55.3 +/- 8.3 years) with trigeminal neuralgia. As a marker for the dopaminergic system, we determined cerebrospinal fluid concentrations of dopamine and its metabolite, homovanillic acid. As a marker for the serotonergic system, we measured cerebrospinal fluid levels of the serotonin metabolite, 5-hydroxyindoleacetic acid. In addition, levels of the neuropeptides, substance P and somatostatin, were determined. The concentration of norepinephrine (P < 0.01) and its metabolite, vanillylmandelic acid, (P < 0.05) were significantly decreased in our patients. The level of the dopamine metabolite, homovanillic acid, was also significantly reduced (P < 0.01). Also significantly decreased was 5-hydroxyindoleacetic acid (P < 0.01). Substance P was significantly elevated (P < 0.05). Somatostatin was significantly decreased (P < 0.05). We hypothesize that the sum of complex neurochemical changes plays a role in the pathogenesis of trigeminal neuralgia. The elevated substance P could support the concept of a neurogenic inflammation in the trigeminovascular system, whereas changes in the monoaminergic transmitters and their metabolites seem to reflect a more central dysfunction possibly due to a longer duration of the disease and an accompanying depression.

Biogenic Monoamines↗
PubMed1997

Hormonal regulation in insects: facts, gaps, and future directions.

There are two main classes of hormones in insects: 1) the true hormones produced by epithelial glands and belonging to the ecdysteroids or juvenile hormones and 2) the neuropeptide hormones produced by neurosecretory cells. Members of these classes regulate physiological, developmental, and behavioral events in insects. Detailed accounts are given on isolation, identification, structure-activity relationships, mode of action, biological function, biosynthesis, inactivation, metabolism, and feedback for hormones involved in 1) metabolic regulation such as the adipokinetic/hypertrehalosemic peptides and the diuretic and antidiuretic peptides; 2) stimulation or inhibition of muscle activity such as the myotropic peptides; 3) control of reproduction, growth, and development such as allatotropins, allatostatins, juvenile hormones, ecdysteroids, folliculostimulins and folliculostatins, ecdysis-triggering and eclosion hormones, pheromone biosynthesis activating neuropeptides, and diapause hormones; and 4) regulation of tanning and of color change. Because of the improvements in techniques for isolation and structure elucidation, there has been rapid progress in our knowledge of the chemistry of certain neuropeptide families. With the employment of molecular biological techniques, the genes of some neuropeptides have been successfully characterized. There are, however, areas that are still quite underdeveloped. These are, for example, 1) receptor studies, which are still in their infancy; 2) the hormonal status of certain sequenced peptides is not clarified; and 3) functional studies are lacking even for established hormones. The authors plead for a concerted effort to continue research in this field, which will also advance our knowledge into the use of insect hormones as safer and species-specific molecules for insect pest management.

Amino Acid Sequence↗
PubMed1997

[Faulty regulation of the hypothalamo-hypophyseal-adrenal axis and chronobiological manifestations in cluster headache].

Cluster headache is a rare very severe disorder that is clinically well characterized with a relatively poorly understood pathophysiology. Although peripheral structures are postulated to be involved in triggering the pain attacks, chronobiological changes like the cluster period and the complex dysbalance of the sympathetic and parasympathetic nervous system point to a "central" genesis of cluster headache. To check neuroendocrine changes in cluster headache, in 12 patients (43.4 +/- 6.3 years) during the cluster period cortisol and ACTH were determined four-times a day (7.00, 12.00, 17.00, 23.00) in the plasma. To prove the central genesis of cluster headache, in the cerebrospinal fluid (CSF) the neurotransmitters norepinephrine, epinephrine, dopamine and the metabolites 5-hydroxyindolacetic acid (5-HIAA), homovanillic acid (HVA) and vanillymandelic acid (VMA) were determined. The values of cortisol and ACTH were significantly elevated in the morning (p < 0.01, p < 0.05) and at night (p < 0.01, p < 0.01) in comparison to the control patients. The daily mean value of cortisol was significantly increased compared to controls (p < 0.01). In the CSF norepinephrine (p < 0.05), HVA (p < 0.01) and 5-HIAA (p < 0.01) decreased to significant low levels compared to control patients. We found significant correlations between cortisol/ACTH and norepinephrine and 5-HIAA. Moreover, our results indicate that the higher cortisol the longer the duration of the cluster period. The results of this study confirm changes of the hypothalamic-pituitary-adrenal axis due to the chronobiological changes in cluster headache. The reduced values of neurotransmitters in the CSF are compatible with the hypothesis of a central genesis of cluster headache.

Adrenocorticotropic Hormone↗