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Biomedical subjects

H Wiegand

Publications and source records attributed to H Wiegand.

At least 73 records · Page 4Linked to original sources
PubMed1983

Repeated surveillance of exposure to thallium in a population living in the vicinity of a cement plant emitting dust containing thallium.

From 1979 to 1981, several medical surveys were carried out among a population living in the vicinity of a cement plant that emitted dust containing thallium until August, 1979. Air, soil, plants, and domestic animals in the area were contaminated by thallium and this led to an increased intake of thallium in the population, mainly due to the consumption of home-grown vegetables and fruit. In order to assess the degree of the individuals' exposure to thallium, thallium levels in 24-h urine samples (TlU) were determined. Three surveys were carried out from September to December, 1979 to assess the degree of thallium exposure of different parts of the general population. Subjects with relatively high exposure, as indicated by the results of the above mentioned population surveys, or those suffering from health disorders that might be related to an increased intake of thallium, were reexamined several times from 1979-1981. Special attention was also given to children attending a kindergarten situated about 0.5 km from the cement plant. As compared to an "unexposed" reference population (mean TlU: 0.3 microgram/l), the majority of the population living in the cement plant area had significantly elevated urinary thallium levels (range: less than 0.1-76.5 micrograms/l) indicating a substantially increased environmental exposure. A reduction of the intake of thallium was mainly achieved by the fact that the population, as advised by the authorities, largely avoided the consumption of home-grown, potentially contaminated foodstuffs. Reports on the teratogenicity of thallium in certain animal species caused great concern that thallium might have exerted teratogenic effects on the newborn of women exposed to thallium during pregnancy. Therefore, an investigation of children born between January, 1978 and August, 1979 (n = 297) was carried out. Although the number of congenital malformations was greater than expected, we conclude, considering carefully all data available, that there is likely no causal relationship between thallium and the occurrence of congenital malformations in the children investigated.

Abnormalities, Drug-Induced↗
PubMed1983

[Microbial contamination of hospital waste].

Hospital wastes from a surgical department (operating unit, intensive care unit, nursery) and household refuse were examined with respect to their bacterial concentrations and species' pattern. The waste samples were processed by active suspending - a new method in the field of waste examination - which allowed gentle homogenization and quantitative microbial counts. Among several established features the most relevant ones like bacterial concentration and relative frequency of bacterial groups (aerobic bacteria, (facultative) anaerobic bacteria, gramnegative bacteria and D-streptococci) indicated, that hospital wastes were not more contaminated than household refuse. Under this aspect, the present practice of hospital waste management, whose main concern is the spread of infectious agents outside the hospital, deserves a reevaluation.

Bacteria↗
PubMed1981

Intake and health effects of thallium among a population living in the vicinity of a cement plant emitting thallium containing dust.

In order to assess the degree of thallium exposure in a population living around a thallium emitting cement plant in a small city in North-West Germany thallium levels in 24 h urine samples of 1,265 subjects and in hair samples of 1,163 subjects were determined. Urinary thallium levels in two groups of subjects living in an urban and a rural area of West Germany were determined for reference. As compared to these subjects the population living around the cement plant exhibited obvious signs of increased thallium intake. The mean urinary thallium concentration was 2.6 micrograms/l and ranged up to 76.5 micrograms/l. In contrast, the mean urinary thallium levels of the two reference groups were 0.2 and 0.4 micrograms/l, respectively. Hair thallium levels of the population living around the cement plant were also markedly increased (mean: 9.5 ng/g). The major route of the population's increased intake of thallium was found to be the consumption of vegetables and fruit grown in private gardens in the vicinity of the cement plant. As was shown by chemical analyses vegetables and fruit grown in these gardens were contaminated by thallium-containing atmospheric dust fall-out caused by emissions of the cement plant. The pulmonary route of uptake as well as other sources did not seem to play a significant role in the population's exposure to thallium. Polyneuritic symptoms, sleep disorders, headache, fatigue and other signs of psychasthenia were found to be the major health effects associated with increased thallium levels in urine and hair. No positive correlation was found between the thallium levels in hair and urine and the prevalence of skin alterations, hair-loss and gastro-intestinal dysfunctions.

Adolescent↗
PubMed1979

Purification and characterization of the hypoxanthine-guanine phosphoribosyltransferase from Saccharomyces cerevisiae.

1. Hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) from Saccharomyces cerevisiae was purified 9400-fold by affinity chromatography giving rise to an electrophoretically homogeneous preparation. 2. The molecular weight of the enzyme was determined by gel filtration with Sephadex G-100 and by sodium dodecylsulfate gel electrophoresis. Both methods reveal a molecular weight of 51,000. 3. The enzyme requires Mg2+ and has its pH optimum at 8.5. 4. Isoelectric focussing as well as gel electrophoresis of the purified extract reveals a single band which exhibits enzyme activity. The isoelectric point of the enzyme is 5.1. 5. The enzyme displays Michaelis-Menten kinetics with apparent Michaelis constants for hypoxanthine, guanine and phosphoribosylpyrophosphate of 23 microns, 18 microns, and 50 microns respectively.

Hypoxanthine Phosphoribosyltransferase↗
PubMed1979

Electrical excitability of motoneurones in early local tetanus.

1. After injection of tetanus toxin into the gastrocnemius muscle of the cat non-synaptic excitability of motoneurones was studied in early local tetanus. Antidromic stimulation of motoneurones was performed onthe toxin-treated side and on the control side of the same cat. 2. The mean resting membrane potential of the motoneurones on the toxin-treated side did not differ from that on the control side. 3. Similarly, no differences were found as to the amplitude of the action potential and its rate of rise as well as to the size and time course of the after-hyperpolarization. 4. The mean input resistance of the motoneurones of the toxintreated side did not differ from that of the motoneurones of the control side. 5. Tetanus toxin did not change the mean refractory period and latency of antidromic responses. 6. It is concluded that the action of tetanus toxin the spinal cord cannot be explained by an action of the toxin on the electrically excitable membrane elements of the motoneurones.

Action Potentials↗
PubMed1978

[Tympanic membrane repair with cartilage and double tissue-layered grafts (author's transl)].

This article describes the technique and advantages of a three layered repair of large perforations of the tympanic membrane using a pallisade of tragal cartilage covered by temporalis fascia and pedicled external auditory canal skin. Large defects of the tympanic membrane can be closed by this method and in addition satisfactory sound transmission can be achieved. The correct positioning of the cartilage graft complex requires training and skill, but an experienced otologist should be able to achieve this in a short time. Early or late reperforation of the graft is extremely rare and late perforations due to otitis media close spontaneously since large defects are not expected. The results in respect of graft durability and hearing improvement are very satisfactory.

Cartilage↗
PubMed1977

Effects of type A botulinum toxin on the cholinergic transmission at spinal Renshaw cells and on the inhibitory action at Ia inhibitory interneurones.

1. The central action of botulinum toxin A (BTA) on the cholinergic transmission at Renshaw cells (RCs) and on the RC-induced inhibition of Ia inhibitory interneurones (IaINs) was studied in anaesthetized cats. BTA was administered by application directly into the spinal cord, injection into a ventral root (L7) and/or injection into the triceps surae (GS) muscle. 2. A direct application of BTA into the spinal cord led to a decrease of the early and the late response of RCs. 3. When the neurotoxin was injected into the GS muscle, the RC activity remained unaffected during the test period (33-46 h after application). 4. No effect appeared up to 10 h after an injection into the ventral root L7. 5. The RC-induced inhibition on IaINs, when tested in animals with local botulismus, remained intact during the test period. 6. From the present results it is suggested that on the spinal level the central action of botulinum toxin predominantly passes on the motoneurones.

Action Potentials↗
PubMed1977

The action of botulinum A neurotoxin on the inhibition by antidromic stimulation of the lumbar monosynaptic reflex.

1. Botulinum toxin type A was injected into gastrocnemius muscles of cats and 2 days later its action on the monosynaptic gastrocnemius reflex and on the recurrent inhibition was investigated. 2. In early local botulism, no significant change in the monosynaptic gastrocnemius reflex was observed. 3. The inhibition by antidromic stimulation of the monosynaptic gastrocnemius reflex was significantly reduced. 4. During the early phases of local botulism an action of botulinum toxin on parts of the soma membrane of the alpha-motoneuron is suggested.

Action Potentials↗
PubMed1976

125I-labelled botulinum A neurotoxin: pharmacokinetics in cats after intramuscular injection.

1. On unilateral injection of sublethal doses of 125I-botulinum A neurotoxin (BTA) into one gastrocnemius muscle of the cat we found after 48 h: a) A disto-proximal gradient of radioactivity (RA) had developed in the sciatic nerve of the injected side. b) The ventral roots of the spinal cord half segments supplying the injected muscle showed a higher RA than the ventral roots of the contralateral control side. c) The spinal cord half segments innervating the injected muscle had a RA much higher than the corresponding segments of the contralateral side. However, a small rise of RA was also observed in the contralateral half segments. 2. In histoautoradiographs of the (ligatured) ventral roots the RA was strictly confined to the intraaxonal space of a few nerve fibres. 3. On injection of equal doses of 125I-BTA into either gastrocnemius muscle we found after 38 h: a) Direct stimulation of only one of the injected muscle caused the RA to reach a higher level in the spinal cord half segments ipsilateral to the stimulated muscle than in the spinal cord half segments of the non-stimulated side. b) Unilateral stimulation of one gastrocnemius nerve under the influence of gallamine or unilateral antidromic stimulation of the dorsal roots L7, S1 failed to cause a difference in RA between stimulated and non-stimulated side.

Animals↗
PubMed1975

Intraaxonal and extraaxonal transport of 125I-tetanus toxin in early local tetanus.

The distribution of radioactivity in the sciatic nerve, the spinal ganglia, the ventral roots and the spinal cord was studied by means of histoautoradiography after injection of 125I-labelled tetanus toxin into gastrocnemius muscles of cats. In the sciatic nerve the major part of the radioactivity was found in the epineurium, but some axons also contained radioactivity. In the ventral root the radioactivity was strictly confined to a few axons; no radioactivity was found in other parts of the ventral root. In the spinal cord the radioactivity was confined to a few motoneurones where it was found in the soma as well as in the dendrites. Transient cooling of the ventral roots prevented the ascent of radioactivity into the spinal cord. Colchicine and vinblastine, after local application to the sciatic nerve, reduced the amount of radioactivity found in the ventral roots and in the spinal cord. However, the same effect was also obtained but to a lesser degree with lumicolchicine. It is concluded that the intraaxonal compartment is involved in the neural ascent of tetanus toxin into the spinal cord.

Animals↗