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L Harms

Publications and source records attributed to L Harms.

At least 37 records · Page 2Linked to original sources
PubMed1993

Effects of potassium channel openers and their antagonists on rat locus coeruleus neurones.

1. Intracellular recordings were obtained from a pontine slice preparation of the rat brain containing the locus coeruleus (LC). Two openers of ATP-sensitive potassium (K(ATP)) channels, RO 31-6930 (10 microM) and cromakalim (100 microM) decreased the spontaneous discharge of action potentials without altering their amplitude or duration. Neither compound changed the resting membrane potential. 2. Of two K(ATP) channel blockers, tolbutamide (300 microM) increased the firing rate, while glibenclamide (3 microM) only tended to do so. In addition, both compounds antagonized the effect of RO 31-6930 (10 microM). Neither glibenclamide (3 microM) nor tolbutamide (300 microM) altered the resting membrane potential. 3. Tetrodotoxin (0.5 microM) depressed the firing, but did not influence the inhibitory action of RO 31-6930 (10 microM). The excitatory amino acid antagonist, kynurenic acid (500 microM), did not change the spontaneous discharge of action potentials. 4. Small shifts (2-4 mV) of the membrane potential by hyper- or depolarizing current injections markedly decreased and increased the firing rate, respectively. 5. Noradrenaline (100 microM) hyperpolarized the cells and decreased their input resistance. This effect was not antagonized by glibenclamide (3 microM) or tolbutamide (300 microM). Ba2+ (2 mM), a blocker of both ATP-sensitive and inwardly rectifying potassium channels, abolished the effects of RO 31-6930 (10 microM) and noradrenaline (100 microM). 6. These data suggest that K(ATP) channels are present on the noradrenergic LC neurones, but are not coupled to alpha 2-adrenoceptors.

Action Potentials↗
PubMed1992

Excitatory effects of adenosine 5'-triphosphate on rat locus coeruleus neurones.

Pontine slices of the rat brain were used for extracellular recording of the frequency of spontaneous action potentials of locus coeruleus (LC) neurones. In the absence of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), alpha,beta-methyleneadenosine 5'-triphosphate (alpha,beta-meATP; 0.3-30 mumol/l) and 2-methylthio ATP (0.3-100 mumol/l), but not ATP (1-100 mumol/l) increased the firing rate. In the presence of DPCPX 0.1 mumol/l, all three purinoceptor agonists were active, the potency order being alpha,beta-meATP greater than 2-methylthio ATP = ATP. Preincubation of the slices with tetrodotoxin (TTX) 0.5 mumol/l decreased the spike discharge but did not alter the percent facilitatory effect of alpha,beta-meATP 30 mumol/l. There was no desensitization to alpha,beta-meATP 10 mumol/l on repeated or continuous application. Suramin 100 mumol/l selectively depressed the effect of alpha,beta-meATP 30 mumol/l without interfering with the effect of equiactive concentrations (10-100 mumol/l) of glutamic acid. The concentration-response curve of alpha,beta-meATP was shifted in a parallel manner to the right by suramin 10 mumol/l. While DPCPX 0.1 mumol/l facilitated firing, suramin 100 mumol/l did not change it. In conclusion, LC neurones may possess P2-purinoceptors of an unidentified type, which share some P2x characteristics.

Action Potentials↗
PubMed1992

Depolarization of rat locus coeruleus neurons by adenosine 5'-triphosphate.

Intracellular recordings were performed in a pontine slice preparation of the rat brain containing the locus coeruleus. The enzymatically stable P2-purinoceptor agonist alpha,beta-methylene ATP increased the firing rate without altering the amplitude or shape of action potentials; the afterhyperpolarization following a spike was not changed either. When locus coeruleus neurons were hyperpolarized by current injection in order to prevent spontaneous firing, alpha,beta-methylene ATP produced depolarization and a slight increase in the apparent input resistance. A combined application of kynurenic acid and bicuculline methiodide failed to alter the alpha,beta-methylene ATP-induced depolarization, and tetrodotoxin only slightly depressed it. A gradual shift of the membrane potential by hyperpolarizing current injection led to a corresponding decrease, but no abolition or reversal of the alpha,beta-methylene ATP effect. In the hyperpolarized region, the current-voltage curve of alpha,beta-methylene ATP came into close approximation with, but did not cross, the control curve. Elevation of the external K+ concentration, or the intracellular application of Cs+ by diffusion from the microelectrode, depressed the response to alpha,beta-methylene ATP; external tetraethylammonium was also inhibitory. External Ba2+ and Cs+ had no effect or only slightly decreased the alpha,beta-methylene ATP-induced depolarization. A low Na+, or a low Ca2+ high Mg2+ medium, as well as the presence of Co2+ in the medium, markedly reduced or even abolished the depolarization by alpha,beta-methylene ATP. ATP itself did not produce consistent changes in the membrane potential or input resistance. However, in the presence of the P1-purinoceptor antagonist 8-cyclopentyl-1,3-dipropylxanthine, ATP consistently increased the firing rate and evoked an inward current. In conclusion, P2-purinoceptor activation appears to depolarize locus coeruleus neurons by inhibiting a persistent potassium current, and at the same time opening calcium-sensitive sodium channels or calcium-sensitive non-selective cationic channels.

Adenosine Triphosphate↗
PubMed1992

A 38-year-old female trauma victim of a car bomb.

This case profoundly affected prehospital and hospital care providers alike. Most Midwestern areas have small cities and towns, and most of our trauma results from accidents, not deliberate, senseless human acts. There is a quality of life in our community that does not involve doing things like this to others. If our staff was this affected, it is sobering to think of the profound adjustment required of the victim.

Adult↗
PubMed1990

[A contribution to "stiff man" syndrome].

A patient with the clinical symptoms of the "Stiff-man"-syndrome, but an atypical course was introduced. Symptoms and course were compared with similar cases mentioned in literature. The "Stiff-man"-syndrome is probably a disease of central origin affecting the relationship between inhibitory and excitatory regulation of the muscle tonus, especially the exteroceptive reflex mechanisms. Several pathological processes of the CNS can be held responsible for the disturbance of the balance in this regulatory system.

Deglutition Disorders↗
PubMed1989

Inability of sonography to detect imminent ovulation.

Sonographic visualization of the cumulus oophorus or of morphologic alterations in the wall of the dominant follicle have been reported to be reliable signs of imminent ovulation when conventional transabdominal sonography is used. To determine if transvaginal sonography could allow a more frequent and confident prediction of imminent ovulation, we prospectively monitored 22 ovulatory menstrual cycles in four women undergoing artificial insemination and in 13 normally menstruating volunteers. Scanning was done on alternate days in the periovulatory period; a 7.5-MHz transvaginal transducer was used. Despite the improved resolution obtained with transvaginal sonography, confident identification of the cumulus oophorus or of mural changes in the follicle was not possible in any of the cycles followed. No other consistent follicular characteristic predicted imminent ovulation. We conclude that confident prediction of imminent ovulation is not possible with sonographic analysis.

Adult↗
PubMed1989

[Neuroradiologic diagnosis of elongated spinal tumors].

Elongated spinal space-occupying lesions are infrequent but not rare. They are found at all ages, most frequently in the thoracic spinal canal and are primarily of gliomatous origin. A survey of our cases from the last 25 years shows the enormous progress in the diagnosis of such processes. This applies to technical quality as well as improved diagnostic information of modern methods and significantly less discomfort to the patient. In the case of suspected space-occupying lesions, a consecutive diagnostic program is recommended, that implies first conventional radiographs of the structure of the spine (including tomography if necessary) followed by myelography with modern positive contrast media. Myelography should be combined with CT. Plain CT-scans can demonstrate hypodense or calcified tumours. MRT provides essential additional information by three dimensional imaging and the corresponding signal processing techniques. With increasing MRT-capacities and improving image quality medullary tumours will primarily investigated with this method. The relations between multiple intramedullary cavities can be explored by endomyelography before drainage.

Adolescent↗
PubMed1989

[A CT localization frame--an improved method for preoperative localization of intracranial processes].

A new CT localization equipment for cerebral processes is presented. As compared to the methods used until now it offers the advantage that no direct marking on the shaven skull must be provided. The parameters resulting during the CT examination with applied localization frame enable the preoperative localization at any desired time. A precondition is the use of an identical device by the surgeon. The use of the methods is explained.

Brain Neoplasms↗
PubMed1988

Serum and seminal plasma prolactin concentrations in men with normospermia, oligospermia, or azoospermia.

Semen analyses were performed and serum and seminal plasma prolactin (PRL) concentrations were determined in 165 samples from 120 men seen with their wives because of infertility. The mean (+/- standard deviation) serum and seminal plasma PRL concentrations were 6.5 +/- 3.3 and 7.5 +/- 3.1 ng/ml, respectively. The mean concentrations of PRL in serum and seminal plasma were similar in groups of men divided by sperm concentration. Seven men had an increased serum PRL concentration. Three of these 7 men had sperm concentrations less than 20 million/ml and none of these 7 men had an increased seminal plasma PRL concentration. Four men had an increased seminal plasma PRL concentration; the serum PRL concentration, sperm concentrations, and motilities were normal in all 4. No man had a decreased serum or seminal plasma PRL concentration. Increased serum PRL concentrations were found infrequently and the increase was slight (23.2 ng/ml or less). Seminal plasma PRL concentrations were related directly to sperm concentrations and motilities, relationships that were statistically significant.

Humans↗
PubMed1988

[The epidural hematoma--diagnostic peculiarities, clinical courses and therapeutic results in a 12-year-study].

Over the past twelve years, diagnoses were applied to and operations performed on 71 patients exclusively for epidural haematoma. A retrospective classification and assessment was made of clinical courses, preoperative angiography as well as of findings recorded from computed tomography and direct clinical examination. The pattern of epidural haematoma was found to be characterised by different clinical courses. Highly useful findings were obtained from direct clinical examination, including fracture in 89 per cent of the above cases and injuries to soft tissue in 85 per cent. A correlation was found to exist between development of haematoma (degree of compression) and postoperative neurological condition. Six operations had to be repeated for postoperative haemorrhage or residual haematoma. The lethality amounted to 15.4 per cent.

Adolescent↗
PubMed1988

[Chronic subdural hematoma. A comparison of bore hole trepanation and craniotomy].

Within the period from 1981 to 1986 a total of 65 patients with 74 (9 bilateral) chronic subdural haematomas (CSH) were operated on. First symptoms, preceding diseases, accompanying factors and neurological findings were listed and evaluated retrospectively. Preoperative CT criteria and postoperative CT controls of the course were put in relation to the clinical development of the findings obtained with different surgical techniques. The comparison of borehole trepanation (37 haematomas) and large craniotomy (37 heamatomas) shows advantages with respect to the retrogression of the haematomas (CT), the postoperative clinical course and the complications in favour of the patients subjected to borehole trepanation.

Adolescent↗
PubMed1986

[A simple aid for the localization of intracranial tumors in cerebral computer tomography].

The exact localizing co-ordination of small intracranial, space-occupying processes is sometimes difficult. As a simple aid for exact localization of such processes a "rod headband" is presented, which consists of a leather strap with exchangeable plastic rods and can be put on the patient's forehead for a CT examination. The artifact-free representation of the little rods in the axial CT layers makes it possible to localize intracranial processes more exactly. Until now, the "rod headband" has been used for ten patients with the following indications: Needle biopsies of intracranial space-occupying processes, cerebral abscess punctures, haematoma punctures, and as a pre-operative localization aid for intracranial tumours.

Brain Abscess↗
PubMed1984

[Value of computer tomography in the diagnosis of impression fractures of the cranial vault].

There are only few statements about the validity of computed tomography for the identification of impression fractures of the skull cap. The diagnostic information of roentgenograms without contrast medium and computed tomograms of a total of 15 patients were evaluated and compared. It was found that computed tomography was slightly superior to conventional X-ray examinations with respect to the diagnostic accuracy. Exact localisation, size, shape, and position of the bony impressions can be better appraised by the assessment in several axial CT section planes. The simultaneous consideration of the sequelae of the intracranial traumata by computed tomography enables a complete assessment of the craniocerebral trauma. The appropriate combination of conventional X-ray diagnosis with computed tomography should lead to an optimum diagnostic information also for these clinical pictures.

Adolescent↗