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Biomedical subjects

M Ludwig

Publications and source records attributed to M Ludwig.

At least 145 records · Page 8Linked to original sources
PubMed1999

Phosphoenolpyruvate carboxykinase in the C(4) monocot Urochloa panicoides is encoded by four differentially expressed genes.

Previous screening of a cDNA library of leaf poly(A(+)) RNA from Urochloa panicoides, a phosphoenolpyruvate carboxykinase (PCK)-type C(4) monocot, led to the characterization of cDNAs encoding the U. panicoides PCK subunit PCK1. A second PCK sequence, designated PCK2, has now been found by rescreening the library. The deduced PCK2 polypeptide is 626 residues in length, has a predicted molecular mass of 68,686 D, and is 96% identical to the deduced PCK1 sequence. Isolation and characterization of genomic DNA fragments revealed that the PCK1 and PCK2 genes are each closely linked to another PCK gene. These additional genes have been designated PCK3 and PCK4, respectively. In each case, the second gene is located upstream and in the same transcriptional orientation as the gene characterized through cDNA analysis. A reverse transcription-polymerase chain reaction assay was used to demonstrate that PCK1 and PCK2 transcripts predominate in leaves, whereas PCK3 and PCK4 transcripts predominate in roots. Moreover, accumulation of PCK1 and PCK2 transcripts is light dependent. Direct N-terminal sequencing of PCK polypeptides purified from leaves demonstrated that PCK2 is produced. These results strongly suggest that PCK1 and PCK2 are involved in the photosynthetic CO(2)-concentrating mechanism active in U. panicoides.

Amino Acid Sequence↗
PubMed1999

Enhanced proteoglycan deposition in the airway wall of atopic asthmatics.

Increased extracellular matrix (ECM) deposition in the airway wall contributes to the airway wall remodeling observed in asthmatics. Although alterations in collagen have been well described, less is known about changes in other components of the ECM, particularly proteoglycans (PGs). Endobronchial biopsies were obtained from seven patients with mild atopic asthma and six normal control subjects. Tissues were blocked in OCT and frozen in isopentane. Sections were immunostained with antibodies for the small leucine-rich PGs, lumican, biglycan, decorin, and fibromodulin and for versican, a large chondroitin sulfate PG. We calculated the area of positive staining in the subepithelial layer, correcting for basement membrane length. Lumican, biglycan, and versican were localized predominantly in the subepithelial layer of the airway wall in all groups. PG deposition was significantly increased in asthmatics as compared with that in control subjects. Furthermore, the degree of PG immunoreactivity was significantly correlated with airway responsiveness in the asthmatics (lumican; r = -0.77, p < 0.05; biglycan: r = -0.76, p < 0.05; versican: r = -0.74, p = 0.06). Our results suggest that PGs may play a role in airway wall remodeling and thereby, airway mechanics in asthma.

Asthma↗
PubMed1999

Outcome of antibiotic therapy with ciprofloxacin in chronic bacterial prostatitis.

Chronic bacterial prostatitis (CBP) is a rare infection of the prostate with Escherichia coli being the predominant causative pathogen. Appropriate antimicrobial therapy is mandatory for cure. We report on our experience with a 4-week regimen of ciprofloxacin in 40 men suffering from CBP due to E. coli. Follow-up was conducted over a period of 12 to 24 months. The microbiological work-up included an analysis of expressed prostatic secretions (EPS) and semen. Eradication of the pathogen in EPS was achieved in 92% of patients 3 months after therapy and in about 70 to 80% of patients evaluated 12 and 24 months after treatment, respectively. Treatment failure was not associated with the presence of prostatic calculi, as assessed by transrectal ultrasonography. After successful therapy, mean EPS pH decreased significantly from 7.95 to 7.35. Significant bacteriospermia with E. coli was detected in 21/22 (95.5%) patients before treatment and in 6/22 (27.3%) patients 6 months after therapy. Our data reconfirm ciprofloxacin as an excellent antimicrobial agent in the therapy of CBP. However, eradication of the pathogen is unpredictable and cannot be achieved in every case. Further studies should correlate microbiological treatment success with symptomatic relief, as assessed by standardised questionnaires.

Adult↗
PubMed1999

[Medical treatment of uterine fibroids with the LHRH antagonist: Cetrorelix].

A depot preparation of the LHRH-antagonist Cetrorelix was used for the preoperative treatment of 20 premenopausal women with symptomatic uterine fibroids to undergo surgery. In an open, prospective and randomised study, 60 mg of this depot preparation were administered i.m. at the second day of cycle. Patients were randomised for a second dosage of 60 mg or 30 mg to be injected on day 21 or day 28 of treatment according to the degree of estradiols' suppression (< 50 pg/mL). The operation was carried out after six or eight weeks of treatment according to the timing of second dosages administration. Weekly transvaginal sonography as well as MRI before and after Cetrorelix treatment were performed for fibroids volume assessment; 16 patients showed satisfactory suppression of gonadotrophins and sexual steroids. No flare up effect was to be observed. In this group of patients the maximum reduction in fibroids size was of 33.5% at the end of treatment. After 14 days of treatment the reduction was of 31.3%. Within the group of good responders (reduction of fibroids size > 20%) the volume of the biggest fibroid after 14 days of treatment was of 56.7% of the initial assessment. Although MRI showed minor mean shrinkage rates of only 25.4% of the initial volume, these differences in comparison to transvaginal sonography were not statistically significant. The avoidance of any flare up phenomenon by the LHRH-antagonist may explain this fast reduction in size. The basic advantages of this treatment modality are the reduction of treatment time with a fast restoration of the ovarian function. The rate of poor responders may be reduced by improving the galenic preparation.

Adult↗
PubMed1999

[Possibilities and limits of assisted reproduction].

The term assisted reproductive technologies (ART) describes all treatment procedures which include more than the natural intercourse to conceive. The most invasive procedure is intracytoplasmic sperm injection (ICSI), which was introduced in 1993. By ICSI the successful treatment of couples with severe male factor infertility, even in cases of azoospermia, became possible. In cases where only immature forms of spermatogenesis are present in the testicular tissue, pregnancies could also be achieved. The limiting factor with greatest influence on the success rate of ART procedures is the female's age. In this context the treatment of postmenopausal women by oocyte donation, as well as ooplasma donation to overcome the negative influence of the female's age on oocyte quality are extreme examples of ethically questionable ART procedures. Until now several 100,000 children worldwide have been born subsequent to ART and especially in vitro fertilisation. No increase in the malformation rate neither after IVF nor after IVF/ICSI have been reported so far. However, because of the lack of prospective controlled studies using standardised evaluation procedures and having enough statistical power to prove the security of ICSI for the newborn children, the German statutory health insurance bodies have ceased to pay ICSI costs as of July 1999. The data on the success of ICSI, the known data on the newborn and developing children and the decisions of the medical services of the German statutory health insurance bodies are presented in discussed in this paper.

Female↗
PubMed1998

kappa-opioid regulation of neuronal activity in the rat supraoptic nucleus in vivo.

We investigated the influence of endogenous kappa-opioids on the activity of supraoptic neurons in vivo. Administration of the kappa-antagonist nor-binaltorphimine (200 micrograms/kg, i.v.), increased the activity of phasic (vasopressin), but not continuously active (oxytocin), supraoptic neurons by increasing burst duration (by 69 +/- 24%) and decreasing the interburst interval (by 19 +/- 11%). Similarly, retrodialysis of nor-binaltorphimine onto the supraoptic nucleus increased the burst duration (119 +/- 57% increase) of vasopressin cells but did not alter the firing rate of oxytocin cells (4 +/- 8% decrease). Thus, an endogenous kappa-agonist modulates vasopressin cell activity by an action within the supraoptic nucleus. To eliminate kappa-agonist actions within the supraoptic nucleus, we infused the kappa-agonist U50,488H (2.5 micrograms/hr at 0.5 micrograms/hr) into one supraoptic nucleus over 5 d to locally downregulate kappa-receptor function. Such infusions reduced the spontaneous activity of vasopressin but not oxytocin cells and reduced the proportion of cells displaying spontaneous phasic activity from 26% in vehicle-infused nuclei to 3% in U50, 488H-infused nuclei; this treatment also prevented acute inhibition of both vasopressin and oxytocin cells by U50,488H (1000 micrograms/kg, i.v.), confirming functional kappa-receptor downregulation. In U50, 488H-infused supraoptic nuclei, vasopressin cell firing rate was increased by nor-binaltorphimine (100 and 200 micrograms/kg, i.v.) but not to beyond that found in vehicle-treated nuclei, indicating that these cells were not U50,488H-dependent. Thus, normally functioning kappa-opioid mechanisms on vasopressin cells are essential for the expression of phasic firing.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1998

Differences in elasticity of vinculin-deficient F9 cells measured by magnetometry and atomic force microscopy.

We have investigated a mouse F9 embryonic carcinoma cell line, in which both vinculin genes were inactivated by homologous recombination, that exhibits defective adhesion and spreading [Coll et al. (1995) Proc. Natl. Acad. Sci. USA 92, 9161-9165]. Using a magnetometer and RGD-coated magnetic microbeads, we measured the local effect of loss and replacement of vinculin on mechanical force transfer across integrins. Vinculin-deficient F9Vin(-/-) cells showed a 21% difference in relative stiffness compared to wild-type cells. This was restored to near wild-type levels after transfection and constitutive expression of increasing amounts of vinculin into F9Vin(-/-) cells. In contrast, the transfection of vinculin constructs deficient in amino acids 1-288 (containing the talin- and alpha-actinin-binding site) or substituting tyrosine for phenylalanine (phosphorylation site, amino acid 822) in F9Vin(-/-) cells resulted in partial restoration of stiffness. Using atomic force microscopy to map the relative elasticity of entire F9 cells by 128 x 128 (n = 16,384) force scans, we observed a correlation with magnetometer measurements. These findings suggest that vinculin may promote cell adhesions and spreading by stabilizing focal adhesions and transferring mechanical stresses that drive cytoskeletal remodeling, thereby affecting the elastic properties of the cell.

Animals↗
PubMed1998

Interruption of central noradrenergic pathways and morphine withdrawal excitation of oxytocin neurones in the rat.

1. We have tested the hypothesis that morphine withdrawal excitation of oxytocin neurones that follows from administration of naloxone to morphine-dependent rats is a consequence of excitation of noradrenergic neurones. 2. Female rats were made morphine dependent by intracerebroventricular (i.c.v.) infusion of the opioid at increasing doses over 5 days. On the sixth day, the rats were anaesthetized with urethane or pentobarbitone and prepared for blood sampling to determine plasma oxytocin by radioimmunoassay or for in vivo extracellular recording of the firing rate of identified oxytocin neurones from the supraoptic nucleus. Morphine withdrawal was induced by intravenous (i.v.) injection of the opioid antagonist naloxone (5 mg kg-1). 3. In one group of rats the noradrenergic projections to the hypothalamus were lesioned by i.c.v. injection of 6-hydroxydopamine immediately prior to the induction of morphine dependence. In these rats the oxytocin secretion induced by i.v. cholecystokinin was reduced to 9 % of that seen in sham-lesioned rats but in contrast, no attenuation of morphine withdrawal-induced oxytocin secretion was observed. 4. i.c.v. infusion of the alpha1-adrenoreceptor antagonist benoxathian, at up to 5.3 microg min-1, dose- dependently inhibited the withdrawal excitation of oxytocin neurones in morphine-dependent rats under urethane anaesthesia, and benoxathian reduced withdrawal-induced oxytocin secretion to 37 % of that of vehicle-infused rats. i.c.v. benoxathian also inhibited the activity of oxytocin neurones in morphine-naïve rats. Similarly, microdialysis administration of 2 mM benoxathian directly onto the surface of the supraoptic nucleus reduced the activity of oxytocin neurones by 53 %. 5. Thus noradrenergic systems are not essential for the expression of morphine withdrawal excitation, since chronic neurotoxic destruction of the noradrenergic inputs to the hypothalamus did not affect the magnitude of withdrawal-induced oxytocin secretion. However, tonically active noradrenergic inputs influence the excitability of oxytocin neurones, and acute antagonism of this noradrenergic tone can powerfully impair the ability of oxytocin neurones to exhibit morphine withdrawal excitation.

Adrenergic alpha-Antagonists↗
PubMed1998

Differences in F9 and 5.51 cell elasticity determined by cell poking and atomic force microscopy.

We studied the elasticity of both a wild type (F9) mouse embryonic carcinoma and a vinculin-deficient (5.51) cell line, which was produced by chemical mutagenesis. Using cell poking, we measured the effects of loss of vinculin on the elastic properties of these cells. F9 cells were about 20% more resistant to indentation by the cell poker (a glass stylus) than were 5.51 cells. Using the atomic force microscope to map the elasticity of wild type and vinculin-deficient cells by 128 X 128 force scans, we observed a correlation of elasticity with cell poking elastometric measurements. These findings, as well as previous atomic force, rheologic, and magnetometric measurements [Goldmann and Ezzell, Exp. Cell Res. 226 (1996) 234-237; Ezzell et al., Exp. Cell Res. 231 (1997) 14-26], indicate that vinculin is an integral part of the cytoskeletal network.

Animals↗
PubMed1998

Haemophilia B: database of point mutations and short additions and deletions--eighth edition.

The eighth edition of the haemophilia B database (http://www.umds.ac. uk/molgen/haemBdatabase.htm ) lists in an easily accessible form all known factor IX mutations due to small changes (base substitutions and short additions and/or deletions of <30 bp) identified in haemophilia B patients. The 1713 patient entries are ordered by the nucleotide number of their mutation. Where known, details are given on: factor IX activity, factor IX antigen in circulation, presence of inhibitor and origin of mutation. References to published mutations are given and the laboratories generating the data are indicated.

Computer Communication Networks↗
PubMed1998

Ankylosing spondylitis and infections of the female urogenital tract.

Thirty-two female patients with confirmed ankylosing spondylitis (AS) and 33 women of similar age with pure ileitis terminalis Crohn were examined for genitourinary infection. Urethral syndrome was found in 15 out of 32 patients with AS: 11 of them had urethritis and 4 urethritis associated with vaginitis. Five women of the control group suffered from urethritis. In all cases with genitourinary infection, Chlamydia trachomatis was isolated. By comparing the AS-patients (urogenital infection group and the non-infected group) with regard to other present clinical parameters, it was found, as expected, that the erythrocyte sedimentation rate in the 1st hour was significantly higher in the infected group. In addition, the infected patients had a significantly higher incidence of enthesopathy, involvement of the spinal column, and higher C-reactive protein values (CRP > or = 5 mg/l). A family history of AS was equally present. Other clinical parameters, such as inflammatory involvement of the joints and HLA-B27 correlation, did not differ significantly between infected and non-infected patients.

Adult↗
PubMed1998

Morphological classification of nuchal skin in human fetuses with trisomy 21, 18, and 13 at 12-18 weeks and in a trisomy 16 mouse.

An increase in the nuchal translucency that can be detected at 10-14 weeks of gestation by ultrasound forms the basis for a screening test for chromosomal abnormality. Several mechanisms leading to this increase in skin thickness have been proposed, including changes of the extracellular matrix, cardiac defects and abnormalities of the large vessels. This study examines the composition of the extracellular matrix of the skin in gestational age-matched fetuses with trisomy 21, 18 and 13 from 12-18 weeks. Immunohistochemistry was applied with monoclonal and polyclonal antibodies against collagen type I, III, IV, V and VI and against laminin and fibronectin. Collagen type VI gene expression was further studied by in situ hybridization to detect differences in expression patterns of COL6A1, COL6A3 and COL1A1 between normal fetuses and those with trisomy 21. The ultrastructure of tissue samples was studied by transmission electron microscopy (TEM) and additionally by immunogold TEM. Further, we examined the morphology of the skin in an animal model for Down's syndrome, the murine trisomy 16, by light and TEM. The dermis of trisomy 21 fetuses was richer in collagen type VI than that of normal fetuses and other trisomies, and COL6A1, located on chromosome 21, was expressed in a wider area than COL6A3, which is located on chromosome 2. Collagen type I was less abundant in the skin of trisomy 18 fetuses, while the skin of all three trisomies contained a dense network of collagen type III and V in comparison with normal fetuses. Collagen type IV, of which two genes are located on chromosome 13, was expressed in the basement membranes of the skin in all fetuses and additionally in the dermal fibroblasts only of trisomy 13 fetuses. Likewise, laminin was present in all basement membranes of normal and trisomic fetuses as well as in dermal fibroblasts of fetuses with trisomy 18. LAMA1 and LAMA3 genes are located on chromosome 18. Dermal cysts were found in the skin of trisomy 18 and 13, but not in trisomy 21 and normal fetuses. Ultrastructural findings showed that an extracellular precipitate containing glycosaminoglycans was regularly present in the skin of trisomy 21 fetuses and murine trisomy 16 embryos. In conclusion, this study suggests that the skin edema in fetal trisomies is characterized by specific alterations of the extracellular matrix that may be attributed to gene dosage effects as a result of a genetic imbalance due to the condition of fetal trisomy.

Animals↗
PubMed1998

Structural organisation of the gene encoding the alpha-subunit of the human amiloride-sensitive epithelial sodium channel.

The human amiloride-sensitive epithelial sodium channel (ENaC) is a member of the degenerin/ENaC family of ion channels and regulates fluid and electrolyte absorption across a number of epithelia, including kidney, colon and lung. Native ENaC has been shown to be a multimer made up of at least three homologous subunits (alpha, beta, gamma) and mutations affecting the channel complex have been identified in various human diseases. "Gain of function" mutations in one of the three ENaC subunits have been found to cause pseudoaldosteronism (Liddle's syndrome) and ENaC "reduction of function" mutations are found in patients affected with the recessive form of pseudohypoaldosteronism (PHA) type 1. In this report, we describe the genomic organisation of the human alphaENaC gene. Human alphaENaC consists of 13 exons spanning 17 kb on chromosome 12p13 and contains at least eight Alu sequences. In addition to the intron/exon boundaries, we have deciphered almost all the intron sequences and 475 bp of the CCAAT-less and TATA-less 5' flanking region.

Base Sequence↗
PubMed1998

Naloxone-induced supersensitivity of oxytocin neurones to opioid antagonists.

Here we report that a single administration of naloxone to conscious rats produces no significant increase in oxytocin release, but when repeated 3-4 days later results in a large release of oxytocin. Plasma oxytocin concentrations were measured in conscious and urethane-anaesthetized rats pretreated with naloxone or isotonic saline on Day 1. On Days 2, 3 or 4, a second dose of naloxone was given, producing an increase in oxytocin secretion in naloxone-pretreated groups (P < 0.05 vs. controls) on Day 3 and 4, but not on Day 2. The specificity of the opioid antagonist supersensitivity was determined by injection of the kappa-antagonist nor-binaltorphimine (nor-BNI). Pretreated rats (naloxone, saline or nor-BNI, Day 1) received an additional acute nor-BNI injection (Day 4) which increased plasma oxytocin concentration in the three groups. However, this increase was higher in naloxone-pretreated rats with no differences between the nor-BNI- and saline-pretreated animals. Measurements of electrical activity of single supraoptic nucleus oxytocin neurons and of plasma oxytocin concentration (Day 4) showed that naloxone modestly enhanced the responsiveness of oxytocin neurons to cholecystokinin (CCK) in naloxone-pretreated rats (by comparison with saline-pretreated rats), but had only a small effect on basal firing rate that did not differ between naloxone-pretreated rats and saline-pretreated rats. To investigate whether naloxone-pretreatment modified the effect of morphine on CCK-induced oxytocin release, on Day 4 CCK was injected i.v. with or without morphine. Morphine at a dose of 0.1 mg/kg did not affect CCK-induced oxytocin release, whereas 1 mg/kg of morphine blocked this release in both saline- and naloxone-pretreated rats. The results suggest that naloxone induces opioid antagonist supersensitivity on oxytocin secretion, mainly by up-regulating kappa-opioid mechanisms on oxytocin nerve terminals in the posterior pituitary.

Animals↗
PubMed1998

Dendritic release of vasopressin and oxytocin.

In addition to the release of neurotransmitters from their axon terminals, several neuronal populations are able to release their products from their dendrites. The cell bodies and dendrites of vasopressin- and oxytocin-producing neurones are mainly located within the hypothalamic supraoptic and paraventricular nuclei and neuropeptide release within the magnocellular nuclei has been shown in vitro and in vivo. Local release is induced by a range of physiological and pharmacological stimuli, and is regulated by a number of brain areas; locally released peptides are mainly involved in pre- and postsynaptic modulation of the electrical activity of magnocellular neurones. Spatial and temporal differences between peptide release within the nuclei and that from the distant axonal varicosities indicate that the release mechanisms are at least partially independent, supporting the hypothesis of locally regulated dendritic release of vasopressin and oxytocin. In this respect, magnocellular neurones show similarities to other neuronal populations and thus autoregulation of neuronal activity by dendritic neuromodulator release may be a general phenomenon within the brain.

Animals↗
PubMed1998

Serum concentration of vascular endothelial growth factor cannot predict the course of severe ovarian hyperstimulation syndrome.

Vascular endothelial growth factor (VEGF) is stated to be a possible promoter of the development and the severity of ovarian hyperstimulation syndrome (OHSS). The secretion of VEGF in granulosa cells seems to be human chorionic gonadotrophin (HCG) dependent. In this prospective study, the data of 10 patients suffering from severe OHSS with ascites and pleural effusions (haematocrit, fluid balance, serum HCG, serum oestradiol) were analysed. The serum VEGF concentration declined during the period of clinical improvement but provided no additional diagnostic information for the further course of OHSS. VEGF was neither an early marker of improvement, nor of worsening of the clinical picture of the OHSS. Serum oestradiol concentrations and serum VEGF concentrations showed a statistical correlation (r = 0.33, P < 0.001). There was no correlation between haematocrit and VEGF, nor between serum HCG and VEGF. To conclude, although VEGF may be involved in the pathogenesis of OHSS, it is not an important clinical marker for the course of an OHSS.

Ascites↗