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Biomedical subjects

M Ludwig

Publications and source records attributed to M Ludwig.

At least 217 records · Page 12Linked to original sources
PubMed1994

Opioids influence neurohypophysial but not central oxytocin release following direct hyperosmotic stimulation of the supraoptic nucleus in urethane-anaesthetised rats.

Microdialysis was used to apply an osmotic stimulus (0.5 M NaCl-aCSF) into both supraoptic nuclei (SON) to investigate the role of endogenous opioid peptides in the control of both central and peripheral oxytocin release in response to this stimulus. There were no differences in central peptide release during direct hyperosmotic stimulation between groups of rats given either vehicle, morphine (5 mg/kg) or naloxone (5 mg/kg) intravenously. Naloxone potentiated oxytocin release into blood; this suggests that endogenous opioid peptides at the level of the neurohypophysis, but not in the SON are important modulators of oxytocin release to this stimulus. However morphine blocked oxytocin release into blood indicative of a central inhibitory action on the firing rate of oxytocin neurones, contrasted with insensitivity to morphine of oxytocin secretion from the dendrites stimulated directly by hyperosmolarity.

Animals↗
PubMed1994

Haemophilia B: database of point mutations and short additions and deletions, fifth edition, 1994.

The fifth edition of the haemophilia B database lists in easily accessible form all known factor IX mutations due to small changes (base substitutions and short additions and/or deletions of < 30bp) identified in haemophilia B patients. The 1,142 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, and origin of mutation. References to published mutations are given and the laboratories generating the data are indicated.

Databases, Factual↗
PubMed1994

Systemic osmotic stimulation increases vasopressin and oxytocin release within the supraoptic nucleus.

Vasopressin (VP) and oxytocin (OT) are released within the hypothalamic nuclear region in response to direct microdialysis with hypertonic solutions. Experiments were performed to determine whether systemic osmotic stimulation causes changes in intranuclear peptide release within the supraoptic nucleus (SON). A hypertonic sodium chloride solution was injected intraperitoneally (i.p.) or intravenously (i.v.) and microdialysis techniques were used to simultaneously monitor central and peripheral peptide release in urethane anesthetized rats. Systemic osmotic stimuli elicited increases in intranuclear peptide release which were delayed and long-lasting, occurring over a 2.5 h period. In contrast, plasma peptide levels peaked at 30-min after the stimulus. The results demonstrate that increased plasma sodium elicits an increase in VP and OT release into the extracellular space of the hypothalamic SON. The different patterns of peptide release in plasma and brain point toward the possibility of independently regulated release into the different compartments.

Animals↗
PubMed1994

Simultaneous monitoring of intracerebral release and behavior: endogenous vasopressin improves social recognition.

We previously reported that direct osmotic stimulation of the supraoptic nucleus (SON) of rats via a microdialysis probe produces a robust 'rebound' release of endogenous vasopressin (AVP) into the extracellular fluid of this hypothalamic nucleus. We now demonstrate in a combined microdialysis and push-pull perfusion study that this intranuclear release is accompanied by increased AVP release in the septum. Simultaneous monitoring of intranuclear release and behavioral performance in the same animal indicated a significant correlation between the amount of endogenously released AVP and improved social memory based on the olfactory discriminative capacities of adult male rats. This memory improvement was partially blocked by local administration of a AVP V1 receptor antagonist either into the SON or septum. These findings indicate that direct osmotic stimulation of the supraoptic nucleus, which increases intracerebral vasopressin release, improves the acquisition and/or processing of olfactory stimuli. Thus, the endogenous neuropeptide fulfills one of the major criteria for being causally involved as a neurotransmitter/neuromodulator in behavioral performance.

Animals↗
PubMed1994

Transrectal prostatic sonography as a useful diagnostic means for patients with chronic prostatitis or prostatodynia.

OBJECTIVE: To evaluate the sonographic changes that occur in patients with chronic prostatitis and compare them with those of non-inflammatory prostatodynia using transrectal prostatic sonography (TPS). PATIENTS AND METHODS: In a prospective study, TPS findings were analysed in 88 men with chronic prostatitis and 53 patients with prostatodynia, all of whom had undergone a standardized diagnostic procedure to detect inflammation. RESULTS: A statistically significant accumulation of prostatic calcifications and unilateral seminal gland alterations was demonstrated in patients with chronic inflammation. Nevertheless, both findings were also present in patients with prostatodynia (22% and 11%, respectively). CONCLUSION: TPS is widely recommended for differential diagnosis in cases of chronic prostatitis and prostatodynia. Prostatic calcifications and seminal vesical abnormalities are regarded as typical signs of inflammation. The results of this study show that these sonographic abnormalities are indicative but do not prove the presence of chronic prostatitis.

Adult↗
PubMed1994

Osmotic stimulation of the supraoptic nucleus: central and peripheral vasopressin release and blood pressure.

Experiments were performed to determine the effect of direct osmotic stimulation of the supraoptic nucleus (SON) on central and peripheral vasopressin (AVP) release and arterial pressure. A microdialysis method was used to deliver hyperosmotic NaCl, mannitol or urea bilaterally into the SON and to sample SON extracellular fluid and blood. Simultaneous brain and blood microdialysis showed that hyperosmotic NaCl increased central and peripheral AVP release and increased mean arterial pressure (MAP). The pressor response was not blocked by intravenous injection of a V1-receptor antagonist, D(CH2)5Tyr(Me)AVP, suggesting that circulating AVP was not involved in that response. Hyperosmotic mannitol or urea caused an increase in central peptide release, but failed to affect MAP or peripheral AVP release. The results suggest that central AVP release within the SON may be due to osmoreceptor stimulation while the peripheral effects on AVP release and MAP are specific for sodium. The results also demonstrate the utility of brain and blood microdialysis for the delivery of stimuli into specific brain regions with simultaneous monitoring of central and peripheral peptide release.

Animals↗
PubMed1994

Effect of elastase on oscillation mechanics of lung parenchymal strips.

Using isolated parenchymal strips from degassed rat lungs, we studied the contribution of the collagen-elastin network to lung tissue hysteretic behavior. Strips were suspended in an organ bath filled with Krebs solution (37 degrees C, pH 7.4) continuously bubbled with 95% O2-5% CO2. One end of the strip was attached to a force transducer and the other to a servo-controlled lever arm. Sinusoidal oscillations of 2.5% of resting length were applied at 1 Hz. Measurements were sampled under baseline conditions at different levels of stress (sigma = 10-26 g/cm). Porcine pancreatic elastase (0.05 IU.mg tissue-1.ml Krebs solution-1) was then added to the bath, and tension and length were measured continuously for 15 min at sigma = 15 g/cm. After washout, measurements were repeated at sigma = 10-26 g/cm. Elastance (E) and resistance (R) were calculated using the equation of motion. Hysteresivity (eta), the structural damping coefficient, was obtained using the following equation: eta = (R/E) pi 2f, where f is frequency. At baseline, we found that E and R were significantly dependent on sigma (P < 0.01), whereas eta was unchanged. During enzymatic digestion with elastase, there were significant decreases of tension, E, and R and no change in eta. Significant increases in E and R were found when these parameters were compared at the same sigma before and after treatment. Again, eta did not change. The constancy of eta after elastase suggests that disruption of the elastin-collagen network does not alter the coupling between elastic and dissipative processes in lung tissue.

Animals↗
PubMed1994

[Infections of the ejaculate by sexually transmissible pathogens].

Certain ejaculate infections can be traced back to sexually transmitted microorganisms, such as Neisseria gonorrhoeae, Chlamydia trachomatis, Ureaplasma urealyticum and Trichomonas vaginalis. To varying extents, these microorganisms cause such classical genital infections as urethritis, epididymitis and prostatitis as well as subclinical genital tract infections. Several different pathomechanisms are under discussion for infection of the ejaculate: reduction of spermatogenesis resulting from testicular damage, autoimmune processes induced by inflammation, direct influence on the spermatozoal function, disturbances in spermatozoal transport, secretory dysfunction of the male accessory sex glands and leukocytospermia with secondary influence on ejaculate parameters. The relevance of these microorganisms for the localization of the inflammatory process within the genital tract are discussed in detail. Their importance for male fertility is a matter of debate. In particular, the significance of C. trachomatis and U. urealyticum, both of which are detectable in the urethra, is still uncertain and cannot be assessed conclusively. Further information allowing delimitation of an infection resulting from bacterial colonization may be provided, on the one hand, by biochemical markers for an inflammatory reaction and indicators of an immune response in the ejaculate, e.g. PMN elastase, complement C3, or coeruloplasmin, and on the other hand, by secretion markers such as alpha-glucosidase, PSA and phosphatase. Whether the assessment of these markers and indicators can help to clarify the inflammatory origin of infertility in individual cases remains doubtful.

Acute-Phase Proteins↗
PubMed1994

[Preparation of critical point dried specimens of mouse embryos with a laser scalpel].

We investigated the use of a laser scalpel for tissue sparing demonstration of the deep structures of critical point dried specimens. A Nd:YAG-Laser emitted pico-second pulses (wavelength 1064 nm, pulse width 30 ps) at pulse energies varying from 1 microJ to 6 mJ was used. Differences in the effects on sputtered and unsputtered specimens were found. We separate the floor of the mouth and pharyngeal fornix in mouse embryos (10. developmental day). It was concluded the laser scalpel is superior to conventional mechanical dissecting methods when applied to small dried specimens. The advantages and disadvantages of the laser scalpel are discussed.

Animals↗
PubMed1994

[Paroxetine in the treatment of depression in geriatric patients--a double-blind comparative study with fluoxetine].

A 6-week double-blind, parallel group study compared paroxetine and fluoxetine in 106 depressed geriatric inpatients (aged 65 to 85 years). Patients presenting acutely with major depressive episode DSM-III-R 296.2 (HAMD > 18 on 21 item scale) were randomized to receive paroxetine (20-40 mg, n = 54) or fluoxetine (20-60 mg, n = 52) following a 3-7 day washout. Primary criteria was the reduction of Hamilton Depression Rating Scale Score (HAMD). Furthermore Montgomery-Asberg Depression Rating Scale (MADRS) and the Clinical Global Impression Scale (CGI) were used. Cognitive functions were assessed with the Mini-Mental-State Examination (MMSE) and the Sandoz Clinical Assessment Geriatric Scale (SCAG). The results showed a comparable reduction in the depression rating scales between the two treatment groups after 6 weeks. However, there was a statistically significant difference (p < 0.05) in HAMD, MADRS, SCAG, MMSE and cognitive subscales of HAMD and SCAG at week 3 in favour of paroxetine, which even was seen after 6 weeks in the SCAG. There were no significant differences between the treatment groups and the number of adverse events reported or in overall tolerability.

Aged↗
PubMed1994

Paroxetine in the elderly depressed patient: randomized comparison with fluoxetine of efficacy, cognitive and behavioural effects.

The efficacy of paroxetine and fluoxetine and their effects on cognitive and behavioural function were compared in a 6 week, double-blind, randomized study of 106 elderly depressed patients (aged 61 to 85 years). Antidepressant efficacy was assessed using the Hamilton depression rating scale (HAMD), Montgomery-Asberg Depression Rating Scale (MADRS) and Clinical Global Impression (CGI) scale. The Sandoz Clinical Assessment Geriatric scale (SCAG), the Mini-Mental State Examination (MMSE), and HAMD cognitive factor scores were used to assess cognitive and behavioural function. Paroxetine demonstrated comparable efficacy to fluoxetine in the treatment of elderly depressed patients, but at the end of treatment, there was a significantly higher proportion of responders to paroxetine than to fluoxetine. Both treatments produced improvements in all measures of cognitive and behavioural function, but paroxetine was significantly superior to fluoxetine from Week 3, indicating a possible early effect. There was no difference between the two agents in either the tolerability or safety of treatment.

Aged↗
PubMed1993

Recurrent mutations in the factor IX gene: founder effect or repeat de novo events. Investigation of the German haemophilia B population and review of de novo mutations.

The investigation of 114 unrelated patients, representing about half the sample of the German haemophilia B population, enabled us to delineate the causative mutation in 103 (90.4%) haemophilic factor IX genes. Of these 103 cases 84 (81.6%) turned out to be unique molecular events, the remainder being repeats. Haplotype analysis revealed that the great majority, if not all, of these recurrent observations occurred independently. This conclusion is supported by our finding that three de novo mutations could be demonstrated at two sites of frequent mutation. A further 20 de novo events could be established in an unselected sample of 37 families with sporadic haemophilia B and 37 families with a history of the disease. Altogether, the germ line of origin could be determined in 21 of these 23 cases, thereby indicating a ratio of male to female mutation rates close to 2. On the basis of the data available, it is becoming clear that rearrangements in the factor IX gene (35.4% of de novo cases) are responsible for haemophilia B at a higher frequency than has been observed today (12.3%). More than two-thirds of the de novo cases cause the severe form of the disease, thereby reflecting the deficit of these haemophilic genes in the actual gene pool because of excess mortality in the past. In addition 40% (12/30) of the de novo single-base mutations were transitions at CpG dinucleotides. Compared with the expected at-random frequency, this observation indicates an 83-fold enhancement of mutation at CpG.

DNA Mutational Analysis↗
PubMed1993

A double-blind study of paroxetine compared with fluoxetine in geriatric patients with major depression.

A 6-week, double-blind, parallel group study compared the efficacy and tolerability of paroxetine and fluoxetine in 106 depressed geriatric outpatients (age, > or = 65 years). Patients with an acute major depressive episode were randomized to receive either paroxetine (20 to 40 mg; N = 54) or fluoxetine (20 to 60 mg; N = 52) after a 3- to 7-day washout. Efficacy evaluations at weeks 1, 3, and 6 used the 21-item Hamilton Rating Scale for Depression (HAM-D). Cognitive function was assessed by use of the Mini-Mental State Examination (MMSE) and the Sandoz Clinical Assessment Geriatric Scale (SCAG). Tolerability was assessed by response to a nonleading question concerning adverse events. There were no significant differences between treatments at week 6 on the HAM-D total, change from baseline. However, there was a statistically significant difference (p < 0.05) at week 3 in favor of paroxetine. Results from the MMSE and SCAG showed that, during treatment, patients in the paroxetine group were characterized by greater improvement in cognitive function than were those in the fluoxetine group. This result was statistically significant at week 3 for both scales (p < 0.05). Adverse events occurred most frequently within the gastrointestinal and nervous systems for both drugs, with no significant differences between treatments.

Aged↗
PubMed1993

Simultaneous microdialysis in blood and brain: oxytocin and vasopressin release in response to central and peripheral osmotic stimulation and suckling in the rat.

Simultaneous microdialysis in blood and brain has been used to monitor the release of both oxytocin and vasopressin into the systemic circulation (jugular vein/right atrium) and within the hypothalamic supraoptic nucleus of rats. Both home-made probes for blood and brain microdialysis revealed detectable nonapeptide concentrations under basal conditions and differential responses to a variety of stimuli. In urethane-anesthetized male rats, bilateral stimulation of the supraoptic nucleus by microdialyzing hypertonic medium (1 M NaCl) not only significantly increased the intranuclear release of both oxytocin and vasopressin (p < 0.05), but also their release from the neurohypophysis into blood (p < 0.05). In poststimulation microdialysates sampled from blood, the nonapeptides reached basal levels again, whereas intranuclear levels were further elevated. Intraperitoneal injection of hypertonic saline, on the other hand, resulted not only in the well-known increased peripheral release of oxytocin and vasopressin (p < 0.01 each), but also in a delayed increase in intranuclear oxytocin (p < 0.05). In contrast, intranuclear vasopressin release failed to change within the 90-min period following osmotic stimulation. In conscious lactating rats, suckling increased oxytocin contents in microdialysates sampled simultaneously in blood and the supraoptic nucleus (p < 0.05 each) further validating the microdialysis techniques used. The in vivo recovery in blood of approximately 65% determined using both radiolabeled and endogenous oxytocin provides a rough estimate to assess nonapeptide concentrations in plasma from 30-min or even 10-min blood microdialysis data.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

A scale associated protein of Apedinella radians (Pedinellophyceae) and its possible role in the adhesion of surface components.

Monoclonal antibodies have been generated against cell surface components of the unicellular phytoflagellate Apedinella radians (Pedinellophyceae). One monoclonal antibody, designated Arg 1E5/1B1, labels a scale associated protein (SAP) of 145 kDa. Immunofluorescence microscopy of whole cells as well as immunoelectron microscopy of whole cell mounts and thin sections using Arg 1E5/1B1 have shown that the SAP is located on the proximal surface of body scales and spine-scales. Its specific location suggests that the SAP may play a role in the adhesion of these surface components to the cell membrane and/or to one another. The potential of monoclonal antibody Arg 1E5/1B1 as a tool to study cell surface morphogenesis and the role of the endomembrane system in A. radians is discussed.

Animals↗