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Biomedical subjects

W Lang

Publications and source records attributed to W Lang.

At least 307 records · Page 17Linked to original sources
PubMed1984

Alkaline haematin D-575, a new tool for the determination of haemoglobin as an alternative to the cyanhaemiglobin method. II. Standardisation of the method using pure chlorohaemin.

Chlorohaemin with high purity (greater than 99%), a stable and well-defined compound, can be used as a primary standard for the standardisation of a haemoglobin assay based on alkaline haematin D-575 [6]. Dissolved in a solution of 25 g Triton X-100 per litre of 0.1 mol/l NaOH ('AHD solution'), the millimolar absorbance coefficient of the end product (alkaline haematin D-575) is 6.960 +/- 0.046 [l X mmol-1 X cm-1] at 575 nm. Within the range of haemoglobin concentrations of 5 to 25 g/100 ml there is a strong linear relation between chlorohaemin concentration and absorbance with a deviation of less than or equal to 2% from the theoretical values. As compared to the conventional cyanhaemiglobin standard solutions, standardisation with pure chlorohaemin is the method of choice because of the simplicity of the preparation of standard solutions, which can be done in every laboratory, and the stability of both the solid compound chlorohaemin and its solutions in alkaline Triton X-100. For the first time a real standard for quality control in haemoglobinometry is recommended: a concentrated solution which behaves like blood, i.e. the simulation of all steps in haemoglobin determination (dilution and photometry) is possible.

Heme↗
PubMed1984

Experimental gaze palsies in monkeys and their relation to human pathology.

Lesions were placed in the paramedian pontine reticular formation ( PPRF ) of monkeys and the resulting gaze palsies studied. Brainstem regions were identified by single cell recordings before kainic acid was injected to selectively destroy neuronal cell bodies in the vicinity. Unilateral PPRF lesions led to a loss of all rapid eye movements towards the ipsilateral side. Deficits were identical to those after experimental electrolytic lesions in monkeys, or structural lesions in humans. Bilateral PPRF lesions produced two different syndromes. Rostral PPRF lesions led to a selective loss of horizontal rapid eye movements leaving vertical movements intact. Caudal PPRF lesions led in addition to a severe disruption of vertical rapid eye movements.

Animals↗
PubMed1984

[Filtering of the illumination of the operating field in microsurgery of the eye].

A filter (GG 475, 2 mm thickness) is presented with which the strain to which the patient's retina is subjected through the light used in surgery with operation microscopes can be reduced and which hardly impedes the surgeon's work at all. The effect of the filter on the sensitivity to damage of the retina and on the spectral sensitivity to brightness of the surgeon is demonstrated.

Filtration↗
PubMed1984

Brain potentials related to voluntary hand tracking, motivation and attention.

While there are many behavioural studies available investigating human hand tracking performance, there are none that include recording of cerebral potentials. Sixteen subjects tracked a visual or a tactile target by moving a stylus with their right hand. They voluntarily started the stimulus, which moved for 1 s in a first random direction, then for 1's in another direction. The stimulus was given to the left field of vision or tactually to the left palm. Tracking was compared to no-tracking controls. The voluntary initiation was preceded by a Bereitschaftspotential (BP), the change in direction by a contingent negative variation (CNV). Both BP and CNV showed a characteristic right hemispheric parietooccipital (visual task) or centro-parietal asymmetry (tactile task) due to the attention paid to the expected stimulus event ("directed attention potential", DAP). While the DAP outlasted stimulus onset by 0.2 s, fronto-midline areas switched already to positivity 100 ms prior to stimulus onset and more than 300 ms prior to the change in direction. Large P300-like components were elicited by stimulus onset and change in direction.

Attention↗
PubMed1984

[Dialysability of aescin].

In experiments with an artificial kidney (Hollow Fiber Kidney) it could be shown that aescin (Reparil) is fully dialysable. The rate of elimination is mainly dependent on the protein binding (ca. 90%) and not on the permeation rate through the membrane. The concentration of aescin in a serum sample decreased exponentially over a 6-h dialysis period to one-third of the initial concentration.

Diffusion↗
PubMed1983

[Infectious diseases].

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Cholinergic receptor binding and autoradiography in brains of non-neurological and senile dementia of Alzheimer-type patients.

Muscarinic and nicotinic cholinergic receptor distribution was studied by dry-mount autoradiography in brains obtained postmortem from patients with senile dementia of Alzheimer-type (SDAT) and non-neurological controls. Sections were incubated with either [N-methyl-3H]scopolamine, ([3H]NMS) or [125I]alpha-bungarotoxin, ([125I]alpha-BTX). No significant difference in the affinity and number of muscarinic and nicotinic receptors was found in hippocampus, frontal, temporal and cingulate cortex between SDAT patients and non-neurological controls. However, some SDAT cases showed diffuse instead of laminar [3H]NMS labeling in cortical regions. The labeling pattern was not affected by the presence of neuritic plaques and neurofibrillary tangles.

Aged↗
PubMed1983

Cholinergic enzymes in neocortex, hippocampus and basal forebrain of non-neurological and senile dementia of Alzheimer-type patients.

Choline acetyltransferase (ChAT) activity and acetylcholinesterase (AChE) staining were examined in different cortical regions, hippocampal formation and basal forebrain of non-neurological controls and of patients afflicted with senile dementia of Alzheimer type (SDAT). Both enzymes showed a clear topographical distribution in the various regions studied. In SDAT cases, ChAT activity was reduced by 0-60% in the neocortex and by up to 97% in the hippocampus depending on the area and layer examined. In the nucleus of the diagonal band of Broca (NDB) and the medial septal nucleus (MSN), the activity was decreased by 65% and 55%, respectively; no significant change was found in the lateral septal nucleus (LSN), nucleus basalis of Meynert (NBM), substantia innominata (SI) and globus pallidus (GP). Comparable changes were seen in AChE staining. The results indicate that degeneration or dysfunction of cholinergic neurons in the medial septal area and possibly neocortex is an important characteristic of SDAT.

Acetylcholinesterase↗
PubMed1983

Determination of growth kinetics in a renal sarcoma of the rat by double labeling with 14C- and 3H-thymidine.

An in vitro double-labeling technique for determination of kinetic growth parameters was tested; 13 renal sarcomas of rats were incubated after excision under standardized conditions with 14C- and 3H-thymidine successively. Another ten tumors were evaluated after in vivo double injection of 14C and 3H-thymidine into sarcoma-bearing animals. In both groups histoautoradiography was performed using a simple stripping-film method. Results including labeling indices, mitotic indices, length of DNA-synthesis phase and cell-production rate obtained by both methods were in excellent agreement. All values fitted those determined in earlier experiments using a continuous labeling and a fraction-labeled-mitoses method in vivo. Theoretical considerations on the calculation of kinetic parameters by double labeling have been added. The experimental results found in this study represent a base for evaluation of biopsies from human tumors.

Animals↗
PubMed1983

Human cerebral potentials and visuomotor learning.

Cortical potentials during visuomotor learning were investigated in man using two hand tracking tasks: (i) direct tracking (T) and (ii) inverted (mirror) tracking (IT). Negative cerebral potentials were higher during the IT task over several cortical areas but in particular over the supplementary motor area (SMA). The acquisition of motor skill as measured in the IT task, was highly correlated with the enhancement of the negative potential. This correlation only held for the frontolateral and frontomedial cortex including the SMA but not for the other electrodes.

Cerebral Cortex↗
PubMed1983

Frontal hemispheric differences in the Bereitschaftspotential associated with writing and drawing.

Twenty right-handed subjects participated in a study investigating the cerebral potentials related to three complex actions: (1) writing one's own signature, (2) drawing a pentagram, and (3) fast meaningless scribbling. The Bereitschaftspotential (BP, readiness potential) started as early as 3 s prior to writing, 2.5 s prior to drawing, but only 1.5 s prior to scribbling. In all three tasks, the BP had its earliest onset over the supplementary motor area (SMA). BP topography was shifted towards the frontal lobes when compared to encephalographic activity reflecting simple finger movements, and was very weak in retro-rolandic leads. The side of the performing hand, as assessed from scribbling, was reflected in a contralateral preponderance of the precentral BP. The maximum BP (about 6 microV) was, in all three tasks, located in FCz (mid fronto-central) overlying the SMA. This location is different from that for simple finger movements, when the maximum is at the vertex. Hemispheric differences were found over the frontal cortex and were characteristic for the verbal and spatial tasks involved: for writing, the BP was significantly larger left frontally than right (even after considering the effect of the performing hand from scribbling), and the difference was largest prior to the onset of movement; for drawing, the BP was larger over the right than over the left frontal lobe, and the difference was largest during the movement.

Action Potentials↗
PubMed1983

[Animal experimental studies on the pharmacokinetics of carteolol].

From investigations in rats and dogs it is known that the proportion of 5-(3-tert-butylamino-2-hydroxy-propoxy)-3, 4-dihydro-2(1H)-quinolinone hydrochloride (carteolol hydrochloride, Endak, Endak mite) absorbed after oral administration is 60-80%. In dogs (as in human beings) most of it is excreted via the kidneys, but in rats biliary elimination predominates. In addition to 8-hydroxycarteolol--which also possesses pharmacological activity--the main metabolites found in dogs and rats are glucuronides of carteolol and 8-hydroxycarteolol. The elimination half-lives in dogs, rats and rabbits are between 1.2 and 3.0 h. Distribution studies point to the existence of a blood-brain barrier (rats and dogs) and a placental barrier (mice). The apparent volume of distribution measured after i.v. injection was from 2.5 to 8.5 l/kg depending on species. Passage into the milk was demonstrated in rats. Plasma protein binding is minimal. In a long-term study in dogs there was no evidence of cumulation except at the very high dosage of 200 mg/kg.

Animals↗